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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Diseases of the colon & rectum 40 (1997), S. 939-945 
    ISSN: 1530-0358
    Keywords: Laparoscopy ; Port site implants ; Colectomy ; Complications ; Pneumoperitoneum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract BACKGROUND: An increased risk of laparoscopic port wound tumor implantation in the presence of overt or covert abdominal malignancy has been identified. PURPOSE: A porcine laparoscopic colectomy model has been used to quantify the influence surgical practices may have on tumor cell implantation. METHODS:51Cr-labeled, fixed HeLa cells were injected intraperitoneally before surgery. Tumor cell contamination of instruments, ports, security threads, and excised wound margins was assessed by gamma counting. RESULTS: Greatest contamination occurred in ports used by the operating surgeon under pneumoperitoneum (64 percent of all port wound tumor cells) and mechanical elevation (76 percent). Gasless surgery in patients in the head-down position increased the rostral accumulation of tumor cells in the abdomen and right upper quadrant port wound by 330 and 176 percent, respectively. Under pneumoperitoneum, port movement was the major contributor to port leakage and wound contamination (21 percent of total recovered wound tumor cells per port). Tumor cells were not carried in aerosol form. Instrument passage and the withdrawal of security threads through the abdominal wall increased port wound contamination 430 and 263 percent, respectively, over pneumoperitoneum control ports. Preoperative lavage reduced by 61 percent, but did not eliminate, wound contamination. CONCLUSION: This porcine model may be used to evaluate surgical factors for the impact on port wound contamination.
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  • 2
    ISSN: 1530-0358
    Keywords: Abscess ; Computed tomography-guided drainage ; Complications ; Anastomotic leak
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract PURPOSE: This study was designed to assess the efficacy of computed tomography-guided percutaneous abscess drainage in intestinal disease. METHODS: Retrospective chart review of patients who underwent percutaneous abscess drainage for complications of intestinal disease with or without surgery between 1990 and 1994. RESULTS: Eighty-two patients with 111 abscesses were identified. Causes of abscess included anastomotic leaks (35 percent), postoperative complications without leak (30 percent), and diverticular disease (23 percent). Complete success (no surgery necessary) was achieved in 53 of 82 patients (65 percent). Nine patients (11 percent) who underwent interval surgery were classified as having partial successes. Twenty-six of 26 (100 percent) well-defined unilocular collections containing pus were successfully drained. Complex abscesses (loculated, poorly defined, multiple, associated with fistula, draining feces) were successfully drained in 35 of 55 patients (63 percent). Success rates varied inversely with the number of complicating factors present. Apache II scores of 15 or higher were associated with decreased success rates. CONCLUSION: Percutaneous abscess drainage is a highly successful technique for treatment of patients with intra-abdominal infection related to intestinal disease. Although several factors are associated with decreased success rates and multiple complicating factors combine to reduce success rates, no identifiable factor or combination of factors preclude the possibility of a successful outcome.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Diseases of the colon & rectum 40 (1997), S. 257-262 
    ISSN: 1530-0358
    Keywords: Heal pouch-anal anastomosis ; Ulcerative colitis ; Crohn's disease ; Familial adenomatous polyposis ; Complications
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract PURPOSE: This study was designed to identify factors associated with pelvic pouch failure. METHOD: A retrospective review of patients undergoing the pelvic pouch procedure with a minimum of 30 months follow-up was conducted. RESULTS: A total of 551 patients had pelvic pouch procedures from 1981 to 1992. Forty-nine patients (8.8 percent) have undergone pouch excision, and 9 (1.6 percent) have been defunctioned, for 58 (10.5 percent) patients with pouch failure. Cause of failure was leakage from the ileoanal anastomosis (IAA) in 21 (39 percent) patients, poor functional results in 13 (23 percent), pouchitis in 7 (12 percent), pouch leakage in 7 (12 percent), perianal disease in 7 (12 percent), and miscellaneous in 3 (5.2 percent). Nine of 22 patients (41 percent) had pouch failure during the first two years, with 2 of 147 patients (1 percent) having failure during the last two years of the study. The 58 patients whose pouches failed (Group 1) were compared with the 493 patients whose pouches did not fail (Group 2). Handsewn IAA (P 〈0.001), tension on the IAA (P 〈0.001), use of a defunctioning ileostomy (P 〈0.01), a diagnosis of Crohn's disease (P 〈0.001), and a leak from the pouch (P 〈0.001) or the IAA (P 〈0.001) were associated with pouch failure. Pouchitis was not a risk factor. CONCLUSION: The majority of pouch failures were caused by leaks at the IAA. Although the leak rate remained stable, leaks following a stapled anastomosis seemed to have a better prognosis than leaks following a handsewn anastomosis. Experience with the pouch procedure and the management of complications likely plays an important role in decreasing the risk of pouch failure.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Diseases of the colon & rectum 40 (1997), S. 112-115 
    ISSN: 1530-0358
    Keywords: Stoma ; Laparoscopy ; Closed technique ; Complications ; Surgical technique
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Stoma creation often involves a separate laparotomy incision. Recently, laparoscopy was suggested to minimize the morbidity associated with conventional open stomal techniques. We describe and evaluate a technique of stoma creation done directly through the stoma site, avoiding both laparotomy and laparoscopy. METHODS: Charts of 36 patients who underwent attempted stoma creation using this closed technique were retrospectively reviewed. RESULTS: A total of 32 patients had stomas successfully created in this fashion (closed group); although four patients failed and required laparotomy (open group), there was an overall success rate of 89 percent. Blood loss (17±5 vs. 350±130 ml; P 〈.001), operative time (52±8 vs. 169±35 minutes; P 〈0.001), and complications (3/32 vs. 4/4;P 〈0.001) favored the closed group. No factors, including diagnosis, obesity, or previous abdominal surgery were identified that contraindicated use of the closed technique. CONCLUSIONS: Stomas can be safely made in a high proportion of patients without the need for laparotomy or laparoscopy. Failure of the closed technique identifies a group of patients who have a high associated operative time, blood loss, and morbidity when laparotomy is used for stoma creation and in whom laparoscopic procedures may improve results.
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  • 5
    ISSN: 1534-4681
    Keywords: Epithelial ovarian cancer ; Second-look laparotomy ; Complications ; Secondary cytoreduction ; Survival
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background: The routine inclusion of second-look laparotomy in the management of patients with epithelial ovarian cancer is controversial. At issue is the justification of morbidity incumbent upon surgery and the possible survival benefit of secondary cytoreduction. Methods: The rate of major complications of surgery was assessed among 100 consecutive patients with FIGO stage III or IV epithelial ovarian cancer who underwent second-look laparotomy. All patients demonstrated a complete clinical and biochemical (CA125 〈35 U/ml) response to first-line therapy. Patients were stratified based on findings at surgery. Patients in group 1 (n=37) had a negative second-look laparotomy. Patients in group 2 (n=35) had only microscopically appreciable disease. Patients in group 3 (n=28) had macroscopic disease. Cytoreductive efforts aimed at resection of all macroscopic disease were carried out for patients in group 3. Results: Thirteen patients (13%) had 15 major complications at surgery. Comparison of the complication rates for patients in groups 1, 2, and 3, of 10%, 8.5%, and 21.4%, respectively, did not achieve statistical significance (p=0.228). The estimated 5-year survival for patients in groups 1, 2, and 3 of 63.9%, 39.8%, and 14.2%, did differ significantly (p〈0.0001). Cytoreductive efforts resulted in the resection of all macroscopic disease in 18 of 28 patients (64.2%) in group 3. The median survival for this group of 18 patients was 33 months, and estimated 5-year survival was 20%. These values do not differ significantly from those observed for patients in group 2. Conclusion: The major complication rate associated with second-look laparotomy is not prohibitive Secondary cytoreductive efforts may result in improved survival for patients with epithelial ovarian cancer.
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  • 6
    ISSN: 1438-8359
    Keywords: Double-lumen tube ; Complications ; Tube troubles ; Airway obstruction ; One-lung ventilation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Purpose Several case reports indicate critical respiratory complications in relation to the double-lumen endobronchial tube (DLT). A prospective survey for the airway problems in using the DLT is presented. Methods One hundred adult patients undergoing thoracotomy for lung cancer were investigated. Tube malposition and airway obstruction were searched using a fiber-optic scope. The endobronchial cuff was positioned just below the trachcal carina while the trachea was intubated with a DLT (Rüsch). The distances of displacement, from the tracheal carina to the bronchial cuff, were measured during anesthesia using an epidural catheter, which had marks every 5 mm. The distances for correcting the tube position were measured at both the bronchial cuff and the level of the teethPaO2,PaCO2 andSPO2 were also measured. Results Malposition (displacement over 5 mm from the correct position) was found in 42 patients, and 40 of them were in a withdrawal direction, occurring at the postural change and during one-lung ventilation, especially during manipulation of the lung hilum. Correcting distances at the level of the teeth were 15.3–3-times longer than those at the bronchial cuff. Airway deformities and gradual withdrawal of the bronchial cuff were found in association with surgical manipulation. Obstruction occurred at the tips of the tracheal tube in four patients and the bronchial tube in six patients, and at the tip of both in two patients. Hypoxemia (PaO2〈60 mmHg) occurred in four patients and hypercapnea (PaCO2〉60 mm Hg) in two patients. Conclusion Most of the DLT obstructions were associated with withdrawal malposition. Great attention to DLT displacement and airway deformity is advised.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Gefässchirurgie 2 (1997), S. 144-149 
    ISSN: 1434-3932
    Keywords: Schlüsselwörter Shunt ; Dialyse ; Offenheitsrate ; Komplikation ; Key words Fistula ; Hemodialysis ; Patency rate ; Complications
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract This paper reports our experience in surgery for hemodialysis access. In the period from 1983 to 1995, 728 operative procedures for hemodialysis access shunts were carried out. These were performed in 391 patients. A total of 599 shunts were placed as the primary form of access, including 423 autologous fistulas in the forearm and 144 in the upper arm. Additionally, 30 PTFE grafts were placed. As proposed, we have seen good functional results of the Brescia-Cimino-fistula in the forearm. Shunts in the upper arm show similar results but a higher rate of complications. PTFE grafts are associated with multiple complications and show a significantly lower rate of patency.
    Notes: Zusammenfassung Ziel der Arbeit ist die Darstellung eigener Erfahrungen als gefäßchirurgisches Zentrum mit der Dialyseshuntchirurgie. Im Zeitraum von 1983–1995 erfolgten in unserer Klinik insgesamt 728 shuntchirurgische Eingriffe an 391 Patienten; 599 Eingriffe waren Neuanlagen von Dialyseshunts. Als autologe Dialysefisteln wurden 423 am Unterarm und 144 am Oberarm angelegt. Bei 30 Dialyseshunts erfolgte die Anlage unter Verwendung von Gefäßprothesen. Erwartungsgemäß fanden sich gute Ergebnisse für die Brescia-Cimino-Fistel am Unterarm. Oberarmfisteln wiesen bei höherer Komplikationsrate gleich gute funktionelle Ergebnisse auf. Prothesenshunts waren komplikationsträchtig und zeigten signifikant schlechtere Funktionszeiten.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Gefässchirurgie 2 (1997), S. 65-68 
    ISSN: 1434-3932
    Keywords: Schlüsselwörter Glutealnekrose ; Aortoiliakale Chirurgie ; Komplikationen ; Key words Gluteal necrosis ; Aorto-iliac surgery ; Complications
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract Chronic hypoperfusion of the hypogastric arteries due to aortoiliac surgery leads to a complex of symptoms well known as Lerich's syndome. In contrast, acute ischemia of the pelvic arterial tree leads to lethal complications [2, 4, 5, 9, 10, 12, 13]. Acute interruption of the hypogastric perfusion mainly occurs after aortoiliac surgery or after selective transcatheter embolisation of the internal iliac artery for control of pelvic bleeding [1, 8]. Several complications may occur after total occlusion: urinary bladder necrosis [6], left colon ischemia, spinal cord ischemia [10], nerve palsy, necrosis of the rectum and gluteal musculature [2, 11–13]. Despite adequate therapy, mortality is over 70% [2]. We report the case of a 66-year-old patient who survived after acute occlusion of the iliac arteries with gluteal necrosis following replacement of the infrarenal aorta with an aortobiiliacal graft.
    Notes: Zusammenfassung Die chronische Minderperfusion im aortoiliakalen Stromgebiet führt zu einem Symptomenkomplex, der als Leriche-Syndrom bekannt ist. Im Gegensatz dazu drohen bei akuter Ischämie nach Verschluß der Beckenarterien schwere Komplikationen mit teilweise letalem Ausgang [2, 4, 5, 9, 10, 12, 13]. Die akute Unterbrechung der aortoiliakalen Perfusion wird überwiegend nach Eingiffen an der Aorta und den Beckenarterien, oder auch nach selektiver kathetergesteuerter Embolisation der Iliakalarterien zur Beherrschung von Blutungen im Beckenbereich beobachtet [1, 8]. Die verschiedenen Komplikationen verteilen sich auf Blasennekrosen [6], linksseitige Kolonischämien und Spinalarterienischämien [10], Nervenausfälle sowie Nekrosen des Rektums und der Glutealmuskulatur [2, 11–13]. Trotz adäquater Therapie beträgt die Letalität über 70% [2]. Wir berichten über einen 66jährigen Patienten, bei dem nach Ausschaltung eines rechtsseitig gedeckt rupturierten Iliakalaneurysmas durch eine Y-Prothese aufgrund eines beidseitigen Verschlusses der Aa. iliacae internae eine bilaterale Glutealnekrose auftrat, der aber dennoch diese meist letale Komplikation überlebte.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Der Chirurg 68 (1997), S. 395-402 
    ISSN: 1433-0385
    Keywords: Key words: Laparoscopic cholecystectomy ; Complications ; Legal consequences. ; Schlüsselwörter: Laparoskopische Cholecystektomie ; Komplikationen ; forensische Konsequenzen.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung. Mit zunehmender Etablierung der laparoskopischen Cholecystektomie treten seit einigen Jahren juristische Aspekte in den Vordergrund. Zur Klärung der Frage, welche Folgen eine kompliziert oder auch fehlerhaft verlaufene laparoskopische Cholecystektomie in juristischer Hinsicht nach sich zieht, wurden die erreichbaren Entscheidungen der Schlichtungsstellen der Ärztekammern sowie der Gerichte aufgearbeitet. Von 40 ausgewerteten Fällen von Behandlungsfehlervorwürfen wurden 16 als Behandlungsfehler anerkannt, 24 mal wurden die Vorwürfe zurückgewiesen. Der häufigste Vorwurf betraf mit 26 Fällen die Gallenwegverletzung. Von diesen 26 Verletzungen wurden 7 als Behandlungsfehler anerkannt, davon 2 als schwere Behandlungsfehler. Als Gründe für anerkannte Behandlungsfehler wurden in den Urteilen im wesentlichen ein verzögertes Umsteigen auf die konventionelle Operation, eine verzögerte Revision, die laparoskopische Durchführung einer Revisionsoperation und das fehlende Umsteigen bei unübersichtlichem Situs genannt.
    Notes: Summary. As laparoscopic cholecystectomy becomes more established, interest in legal aspects increases. The legal cases dealt with in Germany since the introduction of this laparoscopic method in 1989 were studied to determine the legal consequences of complications. Of 40 cases, 16 were judged to be cases of malpractice, whereas 24 were not. The most common cause was injury of the common bile duct (26 cases). Seven of these 26 cases were judged to be cases of malpractice, 2 of these as grave errors. The main reasons for the acceptance of a case as malpractice were delay in changing to conventional cholecystectomy, delayed revision, laparoscopic revisions and not reverting to conventional cholecystectomy in unclear situations.
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  • 10
    ISSN: 1279-8509
    Keywords: Hemophilia ; Complications ; Africa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In order to describe the presenting features at diagnosis and complications of hemophilia in Dakar, we conducted a study of hospital records between October 1991 and January 1993. Twenty-five cases of hemophilia were identified. We found that only 4% of our patients were diagnosed in the first 6 months of life whereas 64% of patients were diagnosed between 6 months and 5 years of age, 32% were detected between 5 years and 14 years of age. The presenting feature at diagnosis was external bleeding in 60% of cases and internal bleeding in 40%. 92% of cases were hemophilia type A and only 8% hemophilia type B. 56% of patients had mild hemophilia, 40% moderate and only 4% severe disease. Hemophiliac arthropathy was present on radiography in 76%. Complications were dominated by repeated joint bleeding, which was present in 92% of patients, and repeated hematomas (80% of patients). A functional handicap was present in 60% of cases. 12% of transfused hemophiliacs developed an inhibitor and 4% of patients were HIV positive. Greater awareness of hemophilia amongst the medical community as well as continued efforts to improve care for hemophiliacs in Senegal are necessary.
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  • 11
    ISSN: 1438-1435
    Keywords: Pancreatitis ; Pleural effusions ; Complications
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Recognition of pleural effusions in acute pancreatitis is important since it carries prognostic implications. This study evaluates the incidence and characteristics of pleural effusions on computed tomography (CT) of patients with mainly an alcohol ingestion etiology of acute pancreatitis. A review of medical records and abdominal CT scans in 50 patients with clinical and laboratory evidence of acute pancreatitis was carried out. All patients were referred for abdominal CT scanning based on an initial clinical presentation consistent with acute pancreatitis and had confirmatory elevation of the corresponding serum enzyme levels. The presence, laterality, and size of any pleural effusions were recorded from the initial sections through the lung bases. Based on a review of medical records, 36 patients (72%) had an alcohol-related etiology of acute pancreatitis. Overall, 10 patients (20%) with acute pancreatitis had pleural effusions on abdominal CT imaging. Five of the effusions were bilateral, three were unilateral right sided, and two were unilateral left sided. Nine of the effusions were small (〈1 cm in maximal height) or medium (1–2 cm) in size. Small and medium-sized pleural effusions are not uncommon in acute pancreatitis. The higher incidence in this study compared to that in earlier reports likely represents the increased sensitivity of cross-sectional imaging for small amounts of pleural fluid. The absence of left-sided effusion predominance in our study group is contrary to much of the earlier literature and may reflect demographic factors, such as etiology and previous history of pancreatitis, although statistical variability must also be considered.
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  • 12
    ISSN: 1433-044X
    Keywords: Schlüsselwörter Acetabulum ; Fraktur ; Operative Behandlung ; Komplikationen ; Ergebnisse ; Key words Acetabulum ; Fractures ; Operative treatment ; Complications ; Results
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Between December 1986 and November 1995, 222 patients with 225 acetabular fractures were treated operatively by three surgeons in the Department of Traumatology and Emergency Surgery of the University Hospitals of the Catholic University of Leuven. Indications for surgery were unstable fracture, displaced fracture through the acetabular dome and fracture with intra-acetabular fracture fragments. There were 37.3% A-fractures, 49.7% B-fractures, and 13% C fractures according to the AO Classification. In 16.4% of fractures there were primary neurological deficits. Patients were treated operatively after an average of 5.0 days. The Kocher-Langenbeck approach was used in 56.9% of cases, the ilio-inguinal approach in 27.1% and the extended iliofemoral approach in 4%. In 7.1% of patients, a primary total hip endoprosthesis was implanted. There was no intra- oder perioperative mortality. The average hospital stay was 26.1 days. In 7.1% of patients, we noted secondary neurological problems. Deep infections were present in 1.3%. In 11.1% of patients a second operative procedure was necessary. We were able to review 175 patients after an average of 2 years. Signs of arthrosis and periarticular ossification were noted on the x-rays: walking distance, hip mobility and pain intensity were asked about and recorded after the clinical examination. In 76% of patients an excellent or good result on the Merle-d'Aubigne scale was obtained. T-fractures and posterior wall fractures were followed by the worst results. During this 9-year period, changes have been made to the preoperative radiological examination carried out, the choice of operative approach and our policy on prevention of thrombosis prophylaxis and postoperative ossification. After thorough preoperative diagnosis and with a meticulous operative technique, it is possible to stabilise the vast majority of acetabular fractures through the three classical approaches. Because the fractures are relatively rare, their diagnosis complex and their surgical treatment difficult, specific training is essential for every acetabular surgeon.
    Notes: In der Zeit zwischen Dezember 1986 und November 1995 wurden in der Klinik für Unfall- und Notfallchirurgie der Universitätskliniken der Katholischen Universität Leuven 222 Patienten mit 225 Acetabulumfrakturen von drei Chirurgen operativ versorgt. Operationsindikationen bestanden bei instabilen Frakturen, verschobenen Frakturen durch das Acetabulumdach und Frakturen mit intraartikulären Frakturfragmenten. Es lagen in 37,3% A-Frakturen, in 49,7% B-Frakturen und in 13% C-Frakturen der AO-Klassifikation vor. Bei 16,4% der Frakturen waren präoperativ neurologische Ausfälle vorhanden. Die Patienten wurden durchschnittlich nach 5,0 Tagen operativ versorgt. Der Kocher-Langenbeck-Zugang wurde in 56,9% verwendet, der ilioinguinale Zugang in 27,1% und der erweiterte iliofemorale Zugang in 4%. Bei 7,1% der Patienten wurde primär eine Totalendoprothese implantiert. Es gab keine intra- oder perioperative Mortalität. Der durchschnittliche Krankenhausaufenthalt betrug 26,1 Tage. Bei 7,1% der Patienten bestanden sekundäre neurologische Probleme, Infektprobleme kamen in 1,3% vor, Sekundäreingriffe waren in 11,1% notwendig. 175 Patienten wurden nach einem durchschnittlichen Zeitraum von 2 Jahren nachuntersucht. Arthrosezeichen und periartikuläre Ossifikationen wurden röntgenologisch, Gehstrecke, Hüftmobilität und Schmerzintensität klinisch ausgewertet; 76% dieser Patienten erhielten ein sehr gutes bis gutes Ergebnis nach der Merle-D'Aubigne-Skala. Die schlechtesten Ergebnisse erhielten die T-Frakturen und die Hinterwandfrakturen. Im Laufe des Neunjahreszeitraums der Studie haben sich präoperative Röntgendiagnostik, die Wahl des operativen Zugangs und die postoperative Versorgung in Bezug auf Thromboseprophylaxe und Prävention von periartikulären Ossifikationen eingehend geändert. Nach ausführlicher präoperativer Diagnostik und mit sorgfältiger Operationstechnik ist es möglich, die Mehrheit der Acetabulumfrakturen durch die drei klassischen Zugänge zu operieren. Weil diese Frakturen eher selten sind, die Diagnostik mühsam und die chirurgische Technik sich schwierig gestaltet, ist eine spezifische Schulung für jeden Acetabulumchirurgen unerläßlich.
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  • 13
    Electronic Resource
    Electronic Resource
    Springer
    Monatsschrift Kinderheilkunde 145 (1997), S. 1286-1288 
    ISSN: 1433-0474
    Keywords: Schlüsselwörter Septumsabszeß ; Diagnose ; Komplikationen ; Kasuistik ; Key words Septal abscess ; Diagnosis ; Complications ; Case report
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Nasal abscesses are uncommon and therefore have been given little attention in the medical literatur. So there are possible diagnostical problems, especially in children. Immediate therapy is indicated to avoid cosmetic deformity or intracranial infections. Treatment entailsm surgical drainage, reconstruction of the septum, and adequate antibiotic backup. Discussion: Nasal septal abscesses should be considered whenever obstructions in nasal breathing with concomitant raised body temperature and swelling occur after trauma.
    Notes: Zusammenfassung Ein Nasenseptumhämatom bzw. -abszeß ist ein seltenes Krankheitsbild und wird in der medizinischen Fachliteratur nur wenig berücksichtigt. Das führt dazu, daß bei der Diagnose Schwierigkeiten bestehen, was v.a. bei Kindern der Fall zu sein scheint. Eine unmittelbare Therapie zur Vermeidung von kosmetischen Problemen bzw. intrakraniallen Komplikationen ist erforderlich. Diese besteht in einer Drainierung, Rekonstruktion des Septums bzw. antibiotischen Abschirmung. Diskussion: Bei einer nach Trauma auftretenden Behinderung der Nasenatmung mit Fieber und Schwellung ist an einen Septumabszeß zu denken.
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  • 14
    Electronic Resource
    Electronic Resource
    Springer
    Der Chirurg 68 (1997), S. 613-617 
    ISSN: 1433-0385
    Keywords: Key words: Outpatient laparoscopic cholecystectomy ; Outpatient clinic ; Prospective study ; Complications ; Costs ; Cost effective. ; Schlüsselwörter: Ambulante laparoskopische Cholecystektomie ; niedergelassene Operationseinrichtung ; prospektive Studie ; Komplikationen ; Kosten.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung. In einer prospektiven Beobachtungsstudie wurden 140 Patienten erfaßt, die rein ambulant laparoskopisch cholecystektomiert wurden. Das Patientengut entspricht im wesentlichen den Veröffentlichungen stationär operierter Patienten. Es gab keine relevanten intra- und postoperativen Komplikationen. Postoperativ brauchten die Patienten weniger Schmerzmittel, erholten sich schneller und waren schneller wieder arbeitsfähig als Patienten in vergleichbaren Veröffentlichungen stationär operierter Patienten. Die ambulante laparoskopische Cholecystektomie ist eine gute Alternative für Patienten mit geringem oder mittlerem Risiko. Selbst bei verbesserter Ertragssituation für die Operationseinrichtung eröffnet sie außerdem Einsparpotentiale im Gesundheitssystem.
    Notes: Summary. A total of 140 patients underwent outpatient laparoscopic cholecystectomy in an outpatient clinic. Evaluation and follow-up of the patients were done prospectively. Population and preoperative data were comparable to published studies of patients operated on in hospitals. There were no serious intra- or postoperative complications. Postoperatively, patients needed less pain medication, were less tired and returned to work earlier than patients after clinical laparoscopic cholecystectomies. Outpatient laparoscopic cholecystectomy offers a good alternative to patients with moderate operative risks (ASA 1–3). It could reduce costs in the German health system and would be therefore highly cost effective.
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  • 15
    ISSN: 1433-0423
    Keywords: Key words Cytomegalovirus retinitis ; Intraocular sustained release device ; Complications ; Ablatio retinae ; CMV resistance ; Schlüsselwörter CMV-Retinitis ; Ganciclovir-Medikamententräger ; Pars-plana-Implantation ; Komplikationen ; Begleittherapie
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Die Zytomegalievirus-(CMV)-Retinitis als häufigste opportunistische Infektion bei Patienten mit Aids wurde erstmals 1992 mit einem intraokular implantierten Medikamententräger therapiert. Im Jahr 1995 wurden die ersten Medikamententräger in Deutschland implantiert und im Rahmen einer offenen Studie der postoperative Verlauf, die Komplikationen und die Wirkdauer überprüft. Patienten und Methode: 20 Patienten wurden in die Studie eingeschlossen und insgesamt 32 Augen mit einem Ganciclovir-Medikamententräger (Vitrasert™, Fa. Chiron-Adatomed, München) versehen. Alle Patienten bekamen zusätzlich eine orale Ganciclovir- oder adjuvante i. v.-Therapie. Der Medikamententräger besteht aus Ethylenvinylazetat und enthält 4,5 mg Ganciclovir mit einer Freisetzungsrate von 1 μg/h Ganciclovir in den Glaskörper über eine prognostizierte Wirkdauer von 6–8 Monaten. Ergebnisse: Die schwerwiegendste Komplikation war die Ablatio retinae bei 5 Patienten (5 Augen), diese Inzidenz entspricht der Ablationshäufigkeit unserer konservativ (d. h. i. v. oder oral) behandelten Patienten. Resistenz gegen Ganciclovir und andere Nukleosidanaloga war die Ursache für die Progredienz der Retinitis nach Implantation bei 2 Patienten mit nachfolgender Erblindung. In keinem Fall wurde eine CMV-Neuinfektion der nicht betroffenen Augen gesehen, es wurden keine extraokularen CMV-Manifestationen unter systemischer antiviraler Begleittherapie festgestellt. Innerhalb des Untersuchungszeitraums von 12 Monaten trat kein Rezidiv auf. Schlußfolgerung: Die Implantation eines Ganciclovir-Medikamententrägers erlaubt eine zielgerichtete antivirale Therapie der CMV-Retinitis mit dem deutlichen Vorteil der wesentlich selteneren Rezidivhäufigkeit. Extraokulare und Zweitaugen-CMV-Infektionen können durch tolerable systemische Therapieschemata verhindert werden.
    Notes: Summary We performed an open clinical trial to assess the safety and efficacy of a 1 μg/h ganciclovir implant for the treatment of newly and pretreated cytomegalovirus (CMV) retinitis in patients with the acquired immunodeficiency syndrome (AIDS). Patients and methods: Thirty-two eyes (20 patients) received the ganciclovir intraocular device and were prospectively followed up from 30 to 365 days. We used a modified technique for fixation of the device in half of the patients. The modification improved the fixation of the implant with a two-hole technique in the strut. Results: Thirty eyes showed stabilization of the retinitis over the time, but in two patients resistance against ganciclovir and other nucleosid analogue compounds developed. Postoperative complications included vitreous hemorrhage (n = 1), cataract (n = 1), and uveitis anterior (n = 1). Late retinal detachment was seen in five eyes (25 %) at 30 to 60 days after implantation. Followup until 1 year after implantation did not show progression of CMV retinitis in 18 of 20 patients. All received antiviral CMV therapy to protect noninfected eyes and intestinum against CMV infection. Conclusions: The ganciclovir intraocular device seemed to be effective in most cases of CMV retinitis and offers a promising alternative for cytomegalovirus retinitis. Patients pretreated longer than 6 months with i. v. ganciclovir have to be carefully selected for implantation, because resistance against ganciclovir could be three times more likely than in i. v.-therapy naive patients.
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  • 16
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    Der Ophthalmologe 94 (1997), S. 50-52 
    ISSN: 1433-0423
    Keywords: Key words rTPA ; Fibrin ; Eye ; Anterior segment ; Complications ; Schlüsselwörter rTPA ; Fibrin ; Auge ; Vorderabschnitt ; Komplikationen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Seit einigen Jahren wird Gewebeplasminogenaktivator (rTPA) intraokular zur Behandlung persistierender Fibrinmembranen eingesetzt, ohne daß bisher nennenswerte Komplikationen beschrieben wurden. Wir berichten über unsere eigenen Erfahrungen beim Einsatz von rTPA im vorderen Augenabschnitt bei 25 Patienten. Über eine Parazentese wurden komplikationslos jeweils 25 µg rTPA (Actilyse, Dr. Karl Thomae GmbH) in die Vorderkammer gespritzt. Ein Rückgang des Fibrins war – wenn auch bei einigen Augen nur allmählich – in 21 Fällen zu verzeichnen. Als postoperative Komplikationen traten 2mal eine (beherrschbare) Nachblutung und 2mal eine irreversible oberflächliche Hornhauttrübung auf. Die Behandlung einer Fibrinmembran des vorderen Augenabschnitts mit rTPA stellt in vielen Fällen eine sinnvolle Ergänzung der lokalen Steroidgabe dar. Beunruhigend ist für uns jedoch das Auftreten von irreversiblen Hornhautkomplikationen, deren Pathogenese wir uns derzeit noch nicht erklären können. Aufgrund des eindeutigen zeitlichen Zusammenhangs müssen wir jedoch von einer kausalen bzw. toxischen Wirkung des rTPA selbst oder einer der Lösungskomponenten ausgehen.
    Notes: Recombinant tissue plasminogen activator (rTPA) is commonly used in patients with myocardial infarction. Recently, it has also been applied intraocularly to dissolve post-operative fibrin with no serious complications being reported so far. In this study we describe our own experience with rTPA in 25 patients with persisting fibrinous membranes in the anterior segment. rTPA (Actilyse, Dr. Karl Thomae GmbH) was given in a single dose of 25 µg and injected into the anterior chamber via a paracentesis. We did not encounter any complications during the injection of rTPA. In 21 eyes fibrin could be reduced significantly, albeit sometimes only slowly. In 13 patients, the membrane had dissolved almost completely by the following day. In contrast, no success was observed after glaucoma surgery (2 eyes) and in chronic iritis (1 eye), or when fibrin mixed with blood was treated (1 eye). There were two (controllable) post-operative hemorrhages (rTPA after vitrectomy, and for fibrin/blood after cataract surgery). In addition, we noted 2 cases of irreversible superficial corneal clouding (rTPA after cataract surgery). We conclude that injection of rTPA can be a useful addition to steroid treatment in selective cases of persisting fibrin in the anterior segment. Long-standing membranes, however, are unlikely to be dissolved. Care should also be taken and rTPA be avoided when there is evidence of recent bleeding. Most worrying to us were the corneal complications that we cannot explain to date. With regard to the definite time correlation we feel that rTPA or one of the solution components might be the cause of this unusual feature.
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  • 17
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    Der Orthopäde 26 (1997), S. 67-74 
    ISSN: 1433-0431
    Keywords: Schlüsselwörter Kongenitale Hüftluxation ; Offene Reposition ; Zugangswege ; Operationstechnik ; Komplikationen ; Femurkopfnekrose ; Reluxation ; Key words Congenital dislocation of the hip ; CDH ; DDH ; Open reduction ; Surgical approach ; Surgical technique ; Complications ; avascular necrosis ; Recurrent dislocation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Closed reduction of a hip dislocation will prove even more difficult if the dislocation has existed over a longer period of time. The indication is based on several principles: An open reduction may be carried out only after an unsuccessful attempt to perform a closed reduction or at a fixed age limit (12 or 24 months) or based upon arthrographic findings. In our department, for babies up to the age of 12 months, we always try to perform a closed reduction. Between 12 to 24 months, arthrographic findings will determine the choice of method. After the age of two, as a rule, we use an open reduction. The preliminary treatment consists of longitudinal traction. Current methods of approach to the hip joint are the medial approach according to Ludloff or the frontal approach by means of an inguinal incision. With the medial approach, there is greater risk of damaging the circumflex artery; also, a higher rate of avascular necrosis of the femoral head has been observed. Therefore, we only practice the ventral approach. Mainly for cosmetic reasons, however, instead of using the Smith-Petersen procedure, we apply a pure inguinal incision proximal to the inguinal ligament. The approach is found by detaching the muscle tissue at the anterior and interior iliac spine. Medially and laterally of the pelvic ridge, though, the tissue may be left. The joint capsule may be opened in the shape of a T or a V. A t-shape incision offers a better survey, wherby the risk of damaging a vessel is somewhat higher. In addition to resection of the teres ligament, it is necessary to indent the transverse acetabular ligament. Often, aponeurotic recession of the psoas tendon must be performed as well and the labrum indented and pushed outwards before reduction. The risk of insufficient development of the acetabulum can be minimized only if the femoral head is optimally centered. If the femoral head is in a high position (i. e., if the upper ridge of the femoral metaphysis lies higher than the triradiate cartilage), a shortening osteotomy of the femur should always be performed. This is the only possibility of repositioning the femoral head without exercizing exaggerated pressure. On the other hand, we are rather reticent to perform a pelvic osteotomy at the time of repositioning. For children unter 2 years of age, we recommend to that the acetabulum be allowed to develop and that a pelvic osteotomy be performed at a lager period if necessary. Postoperative treatment is given for a period of 12 weeks in a hip-leg cast in the Fettweis position, followed by another 3 months in a splint. Possible complications are redislocations, avascular necrosis of the femoral head and persistent acetabular dysplasia. An optimal technique will considerably reduce the risks of such complications.
    Notes: Zusammenfassung Je länger eine Hüftgelenkluxation besteht, desto schwieriger wird es, sie geschlossen zu reponieren. Für die Indikation der offenen Reposition kann nach verschiedenen Prinzipien vorgegangen werden. Sie kann entweder nur nach mißlungenem geschlossenem Repositionsversuch durchgeführt werden oder aufgrund einer starren Altersgrenze (12 oder 24 Monate) oder auf der Basis von arthrographischen Befunden. An unserer Klinik versuchen wir bis zum Alter von 12 Monaten stets primär geschlossen zu reponieren, zwischen 12 und 24 Monaten richten wir uns nach dem arthrographischen Befund, jenseits des 2. Lebensjahres reponieren wir stets von Anfang an offen. Als Vorbehandlung führen wir eine Extension durch. Als Zugänge zum Hüftgelenk sind der mediale Zugang nach Ludloff sowie der vordere Zugang durch Leistenschnitt gebräuchlich. Die Gefahr der Verletzung der A. circumflexa femoris ist beim medialen Zugang größer, es wurde auch eine höhere Rate von Femurkopfnekrosen beobachtet. Wir benutzen deshalb nur den ventralen Zugang. Die Gelenkkapsel kann T- oder V-förmig eröffnet werden. Die T-förmige Eröffnung erlaubt eine bessere Übersicht, die Gefahr der Gefäßverletzung ist aber etwas größer. Nur wenn es gelingt, den Femurkopf optimal zu zentrieren, kann das Risiko der ungenügenden Pfannenentwicklung minimiert werden. Bei hochstehendem Femurkopf (Oberrand der Femurmetaphyse höher als die Y-Fuge) sollte immer eine Verkürzungsosteotomie des Femurs durchgeführt werden. Nur so kann ohne ungebührlichen Druck der Femurkopf stabil reponiert werden. Hingegen sind wir mit pfannendachplastischen Eingriffen zum Zeitpunkt der Reposition eher zurückhaltend. Bei Kindern unter 2 Jahren lohnt es sich, die Pfannenentwicklung vorerst abzuwarten und allenfalls später einen pfannendachplastischen Eingriff durchzuführen. Die Nachbehandlung erfolgt während 12 Wochen in einem Becken-Bein-Gips in Fettweis-Stellung, anschließend während weiteren 3 Monaten in einer Schiene. Als Komplikationen treten Reluxationen, Femurkopfnekrosen und persistierende Dysplasien der Gelenkpfanne auf.
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  • 18
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    Monatsschrift Kinderheilkunde 145 (1997), S. 729-733 
    ISSN: 1433-0474
    Keywords: Schlüsselwörter Otitis media acuta ; Komplikationen ; Akute Mastoiditis ; Chronische Mastoiditis ; Mastoidektomie ; Therapie ; Key words Otitis media ; Complications ; Acute mastoiditis ; Chronic mastoiditis ; Masked mastoiditis ; Mastoidectomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Antibiotics have led to a substantial decrease in the number of infants developing acute mastoiditis from middle ear infection. However, subacute or chronic mastoiditis can still often be observed, causing a variety of intracranial and extracranial life threating complications. The clinical course, the causative organism, risc factors and the role of surgical therapy were studied in 59 patients with mastoiditis. Masked forms of mastoiditis outnumbered the acute disease 2 to 1. 15% had developed complications, 5% life threatening intracranial complications (Abb. 3). Mastoid surgery was employed in all cases. 7 (12%) children needed repeated surgery because of delayed healing or clinical deterioration. The previous surgery in those cases was found to be inappropriate. Nevertheless, children recovered without any additional morbidity from surgery. Diagnostic and therapeutic strategies are discussed to cope with the difficult problem of chronic mastoiditis, taking into account bacteriologic findings, risk factors and important diagnostic information.
    Notes: Zusammenfassung Die häufigste Komplikation der Otitis media ist die Mastoiditis. Trotz der Antibiotika entwickelt eine nicht zu vernachlässigende Anzahl von Kindern eine subakute, chronische Form der Mastoiditis, die mit den gleichen intra- und extrakranialen Komplikationen einhergehen kann. Es wird über 59 Kinder mit Mastoiditis berichtet, die klinischen Symptome, Keimspektrum, Antibiotikasensibilität und die aufgetretenen Komplikationen werden dargelegt. Bei allen Kindern wurde eine Mastoidektomie durchgeführt. Die diagnostischen und therapeutischen Probleme der chronischen Mastoiditis werden unter Einbeziehung der Risikofaktoren diskutiert.
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  • 19
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    Der Orthopäde 26 (1997), S. 327-335 
    ISSN: 1433-0431
    Keywords: Key words Acetabulum ; Radiographic assessment ; Indications for surgery ; Surgical technique ; Complications ; Schlüsselwörter Acetabulum ; Diagnostik ; Operationsindikation ; Operationstechnik ; Komplikationen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Acetabulumfrakturen sind fast zur Hälfte mit einem Polytrauma vergesellschaftet und in über 80 % der Fälle findet man zusätzliche Verletzungen. Das Operationsziel besteht in der anatomischen Wiederherstellung der Hüftpfanne und Stabilisierung der Fraktur durch Osteosynthese, so daß postoperativ auf jegliche zusätzliche äußere Fixation verzichtet werden kann. Eine penible klinische und radiologische Abklärung ist notwendig, um eine erfolgversprechende Operationsplanung durchführen zu können. In jedem Fall gehören zum Röntgenstandard neben der Beckenübersicht die Zielaufnahme der verletzten Hüfte sowie das Ala- und Obturatorbild. Mit diesen Aufnahmen läßt sich u. a. auch das zentrale Acetabulumsegment („Domfragment“) gut beurteilen. Von besonderer Wichtigkeit ist, die primäre traumabedingte Ischiadicusverletzung genau zu dokumentieren. Auf die Repositionsqualität hat der Operationszeitpunkt ganz erheblichen Einfluß. Die Operation sollte zum frühest möglichen Zeitpunkt durchgeführt und das taktische Vorgehen genau geplant werden. Dabei sind besonders bei komplexen Frakturen und für die Wahl des Zugangs 3D-Rekonstruktionen sehr hilfreich. Ohne Repositionshilfen ist das Operationsziel in vielen Fällen nicht zu erreichen. Als Implantate kommen die vorgebogenen Rekonstruktionsplatten der AO, aber auch gerade Platten in Frage. Die Operationen verlangen große Erfahrung. Behandlungsbedingte Komplikationen sind Nervenschäden, mangelhafte Repositionen, fehlplazierte Implantate, instabile Montagen, Reluxationen u. a. Postoperative Wundinfektionen sind bei Beachtung einer lückenlosen Asepsis niedrig. Dagegen findet man nach ausgedehnten Zugängen oft metaplastische Ossifikationen, die nur bei starker Ausbildung (Brooker III und IV) die Funktion des Hüftgelenks beeinträchtigen. Eine präventive Medikation mit Indometacin ist immer angezeigt. Die generelle Röntgenbestrahlung ist abzulehnen.
    Notes: Summary Almost 50 % of acetabular fractures occur in polytraumatized patients; in over 80 % additional injuries are found. The surgical goal is anatomical restoration of the acetabulum and stable fixation, in order to avoid postoperative external fixation. Careful clinical and radiological evaluation is essential to successful surgery. Standard radiological investigations include an anteroposterior view of the pelvis, a “spot” radiograph of the affected hip as well as obturator and iliac oblique views. The latter arc is especially helpful in assessing the central segment of the acetabulum (“dome fragment”). The documentation of any primarily traumatic sciatic nerve lesion is very important, and the quality of reduction depends greatly on the timing of surgery. The operation should be performed as early as possible after the surgical procedure has been carefully planned. A 3-D CT scan provides good information in choosing the surgical approach for complex fractures. In most cases, adequate reduction cannot be accomplished without appropriate aids. For internal fixation, both curved ASIF plates and straight plates are used. The operation demands a high degree of experience. Postoperative complications include iatrogenic nerve palsy, insufficient reduction, incorrectly placed implants, unstable fixation, redislocation, etc. With scrupulous aseptic conditions, the postoperative wound infection rate is low. Ectopic bone formation can occur after extensive surgical approaches and may, depending on size (Brooker III and IV), impair the range of motion of the hip. Indometacin given perioperatively is always indicated. Postoperative radiation treatment should as a rule be viewed critically.
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  • 20
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    Der Anaesthesist 46 (1997), S. 38-42 
    ISSN: 1432-055X
    Keywords: Schlüsselwörter Spinalanästhesie ; Komplikationen ; Spinalkatheter ; Key words Spinal anaesthesia ; Complications ; Spinal catheter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract Life-threatening cardiovascular complications are a serious risk even for healthy patients during spinal/epidural anaesthesia. The incidence of fatal cardiovascular complications for epidural anaesthesia is 1:10000, for spinal anaesthesia 1:7000. In contrast, general anaesthesia has an overall mortality of only 1:28000. Administration of IV fluids to minimise the haemodynaemic reactions of beginning sympatholysis is not always sufficient. In this study, we examined whether fractionated application of local anaesthetics via a spinal catheter would provide better haemodynamic stability. Methods: In a prospective study, we examined the haemodynaemic reactions of 300 patients during single-dose (n=150) versus continuous spinal anaesthesia (CSA) (n=150). Isobaric bupivacaine 0.5% was given through a 29 G Quincke needle (3.5 ml) or a 28 G spinal catheter (1.5 ml as a bolus, followed by 1 ml/10 min until an anaesthetic level of T12 was reached). Results: The sensory and motor effects of both methods were comparable. The T12 level of anaesthesia was achieved with the single-dose method after 10.5 min and with the continuous method after 19.1 min. After single-dose anaesthesia, the blood pressure dropped by 16.5% and the heart rate by 12% compared to the control values. During CSA no significant blood pressure changes were recorded; the heart rate decreased by 8%. In 15 cases vasoconstrictors had to be given to stabilise the lowered blood pressure after single-dose anaesthesia. Conclusion: With the use of CSA, the haemodynamic effects of sympatholysis can be minimised. This method thus has advantages, especially for high-risk cardiovascular patients.
    Notes: In dieser Arbeit sollte untersucht werden, ob die fraktionierte Lokalanästhetikaapplikation über einen Spinalkatheter zu einem stabileren Kreislaufverhalten beitragen kann. In einer prospektiv angelegten Studie wurde das Kreislaufverhalten von 300 Patienten unter einer Single-dose-Spinalanästhesie (n=150) und einer kontinuierlichen Spinalanästhesie (n=150) untersucht. Zur Anästhesie wurde isobares Bupivacain 0,5% verwendet, das über eine 29 G Quincke-Nadel (3,5 ml) oder einen 28 G Spinalkatheter (1,5 ml im Bolus, dann fraktioniert 1 ml/10 min bis zu einem Anästhesieniveau Th 12) gegeben wurde. Die sensible und motorische Qualität beider Verfahren war vergleichbar, das angestrebte Analgesieniveau Th 12 wurde unter der Single-dose-Spinalanästhesie nach 10,5 min erreicht, bei der kontinuierlichen Spinalanästhesie nach 19,1 min. Unter der Single-dose-Spinalanästhesie zeigte sich ein Abfall des Blutdrucks um 16,5% zum Ausgangswert und ein Abfall der Herzfrequenz um 12%. In 15 Verläufen mußten Vasokonstriktoren gegeben werden, um den Blutdruckabfall zu stabilisieren. Bei der kontinuierlichen Spinalanästhesie zeigten sich keine signifikanten Änderungen des Blutdrucks, die Herzfrequenz nahm um 8% ab. Mit der kontinuierlichen Spinalanästhesie werden die Auswirkungen der Sympathikolyse auf die Hämodynamik minimiert. Dieses Verfahren bietet daher bei kardiovaskulären Risikopatienten Vorteile gegenüber der einzeitigen Spinalanästhesie.
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  • 21
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    Der Anaesthesist 46 (1997), S. 697-703 
    ISSN: 1432-055X
    Keywords: Schlüsselwörter Ecstasy ; MDMA ; Intoxikation ; Komplikationen ; Key words Ecstasy ; MDMA ; Intoxication ; Complications
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract The increased consumption of ”ecstasy” (MDMA, 3,4-methylenedioxy-methamphetamine) has also increased the number of life-threatening intoxications. From a Medline search of the years 1992–1996, reports were registered and evaluated. Besides cerebral, cardiorespiratory, renal, and hepatic symptoms, hyperthermia syndromes such as malignant hyperthermia, neuroleptic malignant syndrome, or the serotonin syndrome were common. In addition to a discussion of the intoxication symptoms and their acute and intensive-care therapy, the psychological and physiological effects of ”ecstasy” will be described. Some historical considerations of the topic are included in this review.
    Notes: Zusammenfassung Die Zunahme des „Ecstasy”-Konsums (MDMA, 3,4-Methylendioxymethamphetamin) erhöhte ebenfalls die Anzahl lebensbedrohlicher Intoxikationen. Aus einer Medline-Recherche der Jahre 1992–1996 wurden Berichte über Intoxikationen erfaßt und ausgewertet. Intoxikation mit Ecstasy: Im Vordergrund steht neben zerebralen, kardiopulmonalen, renalen und hepatischen Symptomen auch das Hyperthermie-Syndrom im Sinne einer malignen Hyperthermie, eines neuroleptischen malignen Syndroms oder eines Serotonin-Syndroms. Neben der Diskussion der Intoxikationssymptome und deren möglicher Akut- und Intensivtherapie werden psychische und physische Wirkungen von „Ecstasy” beschrieben und zur Vervollständigung des Themas eine kurze historische Betrachtung der Droge gegeben.
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  • 22
    ISSN: 1432-1238
    Keywords: Key words Cardiac output ; Complications ; Cost ; Dopexamine ; High risk patients ; Intensive care ; Morbidity ; Mortality ; Oxygen delivery ; Resource use ; Surgery
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Objective: To investigate the cost implications of a treatment policy of a deliberate perioperative increase of oxygen delivery in high risk surgical patients. Design: A cost-effectiveness analysis comparing ‘protocol’ high risk surgical patients in whom oxygen delivery was specifically targeted towards 600 ml/min/m2 with ‘control’ patients. Interventions: In a randomised, controlled clinical trial we previously demonstrated a significant reduction in mortality (5.7% vs 22.2%, p=0.015) and morbidity (0.68±0.16 complications vs 1.35±0.20, p=0.008) in ‘protocol’ high risk surgical patients in whom oxygen delivery was specifically targeted towards 600 ml/min per m2 compared with ‘control’ patients. This current study retrospectively analysed the medical care and National Health Service resource use of each patient in the trial. Departmental purchasing records and business managers were consulted to identify M28.9nthe unit cost of these resources, and thereby the cost of treating each patient was calculated. Results: The median cost of treating a protocol patient was lower than for a control patient (£6,525 vs £7,784) and this reduction was due mainly to a decrease in the cost of treating postoperative complications (median £213 vs £668). The cost of obtaining a survivor was 31% lower in the protocol group. Conclusion: Perioperative increase of oxygen delivery in high risk surgical patients not only improves survival, but also provides an actual and relative cost saving. This may have important implications for the management of these patients and the funding of intensive care.
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  • 23
    ISSN: 1432-1238
    Keywords: Key words Viral pneumonia ; Immunosuppression ; Complications
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Pneumonia caused by herpes simplex virus type 1 (HSV1) is rare and occurs in severely immunosuppressed patients. HSV1 can be detected in bronchoalveolar lavage (BAL) from patients presenting with respiratory failure, but its direct effect on disease is difficult to prove. We demonstrate the causative role of HSV1 in the case of a 44-year-old male with Crohn's disease who presented to the intensive care unit with the acute respiratory distress syndrome after surgery. BAL cells were cultured and immunofluorescence confirmed the presence of HSV1 during the first weeks of illness. Increased IgG titers confirmed the diagnosis of a recurrent HSV1 infection. A lung biposy specimen showed fibroproliferation without pathogens. Immunosuppressive therapy had been stopped and acyclovir was introduced at this time. The diagnostic difficulties in this patient underline the importance of early recognition of viral infection as a potential cause of severe pneumonia in severely ill, immunocompromised patients.
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  • 24
    ISSN: 1432-1084
    Keywords: Key words: Bile ducts ; Neoplasms ; Interventional procedure ; Implantation metastasis ; Complications
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Percutaneous transhepatic biliary drainage (PTBD) is the basis for most biliary interventional procedures. We recently observed the occurrence of a subcutaneous implantation metastasis after PTBD in a patient with incurable cholangiocarcinoma. Although tumor cell seeding along the catheter tract is a very rare complication, we think that PTBD should be avoided when curative resection is planned.
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  • 25
    ISSN: 1432-1238
    Keywords: Key words Central venous catheterization ; Venobronchial fistula ; Cardiac surgery ; Complications
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Venobronchial fistula is a rare complication of long-term central venous catheterization. We present the uncommon occurrence of a venobronchial fistula as an acute complication of central venous catheterization during open heart surgery. The factors responsible for this unusual complication and the methods to prevent it are discussed.
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  • 26
    ISSN: 1432-1920
    Keywords: Key words Anterior cervical surgery ; Complications ; Infection ; Computed tomography ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We report a 44-year-old woman who developed an atypical retro-oesophageal abscess 4 years after anterior cervical surgery with fusion (ACSF). She presented with dysphagia but no fever or definite laboratory signs of inflammation. Delayed or chronic dysphagia following Cloward's operation is usually related to graft displacement. Infection may also, more rarely, be encountered in conjunction with dysphagia, but is typically associated with a classical clinical presentation and laboratory results. We recommend that in cases of delayed dysphagia without evidence of graft migration, the possibility of retropharyngeal infection should be considered, even in the absence of clinical signs or supporting laboratory evidence. MRI in this rare delayed complication is nonspecific but suggestive, and hence represents the imaging modality of choice in such situations.
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  • 27
    ISSN: 1432-1920
    Keywords: Key words Angioplasty ; Intracranial artery ; Complications ; Restenosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The purposes of this study were to determine the optimal time for initial follow-up angiography, the restenosis rate after successful intracranial percutaneous transluminal cerebral angioplasty (PTCBA), and finally to identify lesion-specific characteristics for predicting successful angioplasty. Thirty-five patients underwent PTCBA with follow-up angiography 3 and 12 months later. Although 27 lesions were adequately dilated, permanent complications occurred in 3 patients. The restenosis rate at 3 months was 29.6 %; patients without restenosis at 3 months remained free from vessel narrowing at 12 months. Restenosis occurred on severe, eccentric lesions, total occlusions or extremely angulated lesions. There was a strong correlation between sufficient dilatation and lower re- stenosis rate, and concentric and short lesions (type A). We conclude that the optimal time for initial angiographic follow-up is 3 months after PTCBA. PTCBA is most suitable for type A lesions with higher success, lower morbidity and lower restenosis rates.
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  • 28
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    Neuroradiology 39 (1997), S. 282-285 
    ISSN: 1432-1920
    Keywords: Key words Intervertebral disc ; hernia ; Nucleotomy ; Complications
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We reviewed the records of 243 patients treated at 271 disc levels to determine the incidence of side effects and complications of percutaneous nucleotomy. In our early experience there were 7 technical failures (2.5 % of all attempts), of which 6 were at the 5th disc level. The success rate dropped from 67 % at 3 months to 60 % 1 year after treatment due to recurrences in 16 patients (6.6 %). Extruded or sequestered fragments were found in 6 patients (2.4 %), and may have been caused by nucleotomy. However, only one was accompanied by aggravation of symptoms. Discitis was seen in 2 patients (0.8 %), both treated at two separate disc levels. About half the patients experienced increased low back pain, mean duration 9 days, after treatment, and 3 (1.2 %), of whom 2 also had nonorganic disorders, needed admission to hospital because of severe pain. Mild spasm and a sensation of instability were noted by 9.6 % and 25 % of the patients respectively. Injury to nerves, bowels, vessels or ureters or a dural leak never occurred. The study confirms earlier reports that the rate of serious complications is low.
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  • 29
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    Pediatric nephrology 11 (1997), S. 153-155 
    ISSN: 1432-198X
    Keywords: Key words: Acute renal failure ; Complications ; Multivariate analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Various factors were analyzed in 80 consecutive children under 16 years who had acute renal failure (ARF), for various prognostic factors. Overall mortality was 42.5%, with significantly higher levels seen in hemolytic uremic syndrome (68%, P 〈0.05) and associated with cardiac surgery (90.9%, P 〈0.01). Anuria (67.6% vs. 43.5%, P 〈0.05), need for dialysis (85.3% vs. 56.5%, P 〈0.05), neurological complications (50% vs. 6.3%, P 〈0.01), and respiratory complications (35.2% vs. 2.1%, P 〈0.01) were significantly higher in nonsurvivors than survivors. Multiple regression analysis showed the presence of neurological and respiratory complications to be poor prognostic factors.
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  • 30
    ISSN: 1432-198X
    Keywords: Key words: Bladder augmentation ; Renal failure ; Transplantation ; End-stage renal disease ; Complications
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Ten consecutive patients with failure of urinary bladder augmentation (UBA) performed either prior to or after reaching end-stage renal disease (ESRD) were studied. Seven patients developed increased hydroureteronephrosis, infectious complications, and advanced to ESRD after UBA. The mean time to development of ESRD in patients who had UBA performed with moderate chronic renal failure (CRF) was 1.8 years. The UBAs in all seven patients were taken down prior to transplantation. Subsequently, five of these UBA-takedown patients have received kidney grafts and all have stable, good renal function. Three patients had their UBA performed after they reached ESRD, in preparation for renal transplantation. All three of these patients experienced recurrent urosepsis following transplantation, resulting in death in one patient and loss of graft in another. The third patient will undergo takedown of the UBA. This study suggests that UBA may possibly not be the best option for patients with moderate CRF and those awaiting transplantation.
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  • 31
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    Pediatric nephrology 11 (1997), S. 87-95 
    ISSN: 1432-198X
    Keywords: Key words: Angioaccess ; Arteriovenous fistula ; Graft ; Long-dwell catheters ; Complications
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. In the light of many years’ experience in hemodialysis access surgery, the different methods of creating vascular access for dialysis treatment in the pediatric population are described. After presenting the various access types using autologous blood vessels and also heterologous grafts, their specific spectrum of complications is discussed in detail. Summarizing our experience it has to be emphasized that there is no specific angioaccess for children and adolescents, and that most vascular access procedures used in adults are also suitable for use in the young.
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  • 32
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    Der Radiologe 37 (1997), S. 197-204 
    ISSN: 1432-2102
    Keywords: Schlüsselwörter Lebertransplantation ; Komplikation ; Radiologische Diagnostik ; Key words Liver transplantation ; Complications ; Radiological diagnosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Introduction: Orthotopic liver transplantation (OLT) has become an accepted treatment for end-stage liver disease. However, postoperative complications result in significant patient morbidity and mortality. Early detection and treatment of these complications is therefore of utmost importance. Materials and methods: We retrospectively reviewed the postoperative complications of the patients who underwent OLT at our institution. Duplex Doppler sonography and cholangiography were the primary imaging modalities in postoperative evaluation of the transplanted liver. Other important techniques were CT, MRI, and angiography, which may contribute to a reliable diagnosis of vascular or biliary complications. Results: Second to primary organ dysfunction, vascular complications are the most frequent cause of graft loss. Thrombosis of the hepatic artery is the most common and most serious vascular complication, with a reported incidence from 4 to 42 %. Bile duct sludge, leaks and strictures are frequent complications after liver transplantation, which can contribute to graft dysfunction. Biliary tract complications usually occur within the first 3 months and require interventional radiological or surgical therapy. Since liver transplant recipients undergo immunosuppressive therapy, they are at increased risk of developing late post-transplant malignancies, which are best depicted by US, CT or MRI. However, radiological diagnosis of lymphoproliferative disorder has to be confirmed by liver biopsy. Conclusion: Cholangiography and Duplex sonography are routinely used in the postoperative evaluation of patients with OLT. CT, MRI, and angiography are problem-solving tools in equivocal cases.
    Notes: Zusammenfassung Einleitung: Die orthotope Lebertransplantation hat sich zu einer etablierten Therapie bei Lebererkrankungen im Endstadium entwickelt. Der frühe Nachweis und die prompte Therapie eventueller Komplikationen sind für das Überleben des Patienten und des Organs entscheidend. Material und Methode: Es wurden im eigenen Krankengut die postoperativen Komplikationen nach OLT retrospektiv ausgewertet. Die Duplexsonographie und die Cholangiographie erwiesen sich als die primären Untersuchungsmethoden der Wahl zum Nachweis vaskulärer oder biliärer Komplikationen. CT, MRI und die Angiographie waren in Problemfällen wertvolle additive bildgebende Verfahren zur Diagnosesicherung. Ergebnisse: Nach der primären Organdysfunktion sind die vaskulären Komplikationen als häufigste Ursache für den Verlust des Spendeorgans anzuführen. Die Thrombose der A. hepatica ist die häufigste vaskuläre Komplikationen mit einer Inzidenz von 4–42 %. Galleleaks, -sludge und -strikturen sind häufige Komplikationen, die letztlich zu einer Dysfunktion des transplantierten Organs führen können. Biliäre Komplikationen treten gehäuft in den ersten 3 Monaten auf und erfordern eine interventionelle oder chirurgische Therapie. Da Patienten nach OLT einer immunsuppressiven Therapie unterliegen, sind sie einem erhöhten Risiko einen lymphoproliferativen Tumor zu entwickeln ausgesetzt. Diese Posttransplant-Tumore können mit US, CT und MRI ausgezeichnet abgegrenzt werden, erfordern jedoch eine Sicherung der Diagnose durch eine Feinnadelpunktion. Schlußfolgerung: Die postoperative Verlaufskontrolle und der Nachweis von Komplikationen nach OLT ist eine Domäne von Cholangiographie und Duplexsonographie. In Problemfällen kommen CT, MRI und Angiographie zum Einsatz.
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  • 33
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    Der Schmerz 11 (1997), S. 241-246 
    ISSN: 1432-2129
    Keywords: Schlüsselwörter Narkosekomplikationen ; Übelkeit ; Erbrechen ; Key words Anaesthesia ; Audit ; Complications ; Nausea ; Vomiting
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Problem: Postoperative nausea and vomiting remains an important problem. Many risk factors have been identified; however, the importance of postoperative analgesic technique and patient expectation remain poorly defined. Methods:We prospectively collected data on postoperative nausea and vomiting (PONV) in four groups of randomly selected patients (n=50 per group) who received either simple analgesics, nurse-administered intravenous morphine (NAA), patient-controlled analgesia (PCA) with morphine or epidural analgesia with bupivacaine and fentanyl. Patients were questioned regarding any past history of PONV or motion sickness, their preoperative expectation of suffering PONV and satisfaction with their antiemetic therapy. Results: The incidence of nausea was higher in both morphine groups P〈0.05), women (P〈0.05), those less than the median age of their group (P〈0.05) and those with a past history of PONV (P〈0.05) or motion sickness (P〈0.05). Most patients did not expect to experience PONV (19.3%). The incidence of nausea was higher in those expecting to experience PONV than in those not expecting to suffer PONV (P〈0.01). Of those who received postoperative antiemetic treatment, 23.6% were dissatisfied or very dissatisfied with their therapy. Few patients received a prophylactic antiemetic drug (15%). Conclusions: Study results show that patient expectation is a potent predictor of postoperative nausea, a risk factor hitherto ignored in the anaesthetic literature, and that, in the provision of analgesia following major surgery, epidural analgesia is associated with less PONV than intravenous morphine.
    Notes: Zusammenfassung Übelkeit und Erbrechen (PONV) sind nach wie vor ein Problem der postoperativen Phase. Viele Risikofaktoren sind bekannt, jedoch sind die Bedeutung der unterschiedlichen postoperativen analgetischen Regimes und die Erwartungshaltung der Patienten wenig untermauert. Patienten: Prospektiv wurden 4 randomisierte Patientengruppen untersucht (n=50/Gruppe), die postoperativ einfache Analgetika (Gruppe 1), durch eine Krankenschwester verabreichte i.v. Morphingaben (NAA; Gruppe 2), eine patientenkontrollierte Analgesie (PCA; Gruppe 3) und eine Epiduralanalgesie mit Bupivacain und Fentanyl (Gruppe 4) erhielten. Bei den Patienten wurde ermittelt, ob sie bei Voroperationen an Übelkeit und Erbrechen litten. Zusätzlich wurde die Erwartungshaltung der Patienten gegenüber PONV und deren Zufriedenheit mit der antiemetischen Therapie untersucht. Ergebnisse: Die Inzidenz von PONV war bei beiden Morphingruppen, bei Frauen, bei Patienten, die älter waren als der Median der Gruppe, und bei solchen Patienten, die in ihrer Vorgeschichte an PONV und Seekrankheit litten, höher. Die meisten Patienten hatten nicht erwartet, postoperativ Übelkeit und Erbrechen zu erleiden (19,3%). Bei Patienten, die präoperativ PONV erwarteten, war die Inzidenz höher als bei Patienten, die über diese Erwartungshaltung nicht berichteten (p〈0,01). Ein Viertel der Patienten (23,6%) war mit der postoperativen antiemetischen Behandlung unzufrieden oder sogar sehr unzufrieden. Eine präoperative Prophylaxe erhielten 15% der Patienten. Schlußfolgerung: Die Studie zeigt, daß die Erwartungshaltung der Patienten, an postoperativer Übelkeit und postoperativem Erbrechen zu leiden, ein in der Literatur unterschätzer Vorhersagefaktor ist. Bei der postoperativen Schmerztherapie bietet die Epiduralanalgesie im Vergleich zur i.v. Morphingabe deutliche Vorteile.
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  • 34
    ISSN: 1432-1084
    Keywords: Key words: Bone cysts ; Fractures ; Complications ; Cortical defect ; MRI greenstick fractures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Posttraumatic bone-cyst formation is a known but rare process. Typical location is the distal radius, usually as a result of a greenstick fracture. The pathogenesis is unknown; however, subperiosteal migration of fat or hemorrhage with later absorption may cause cyst formation. We present the first reported case of MR imaging of this lesion. At MRI subperiosteal hemorrhage was found to be the cause of cyst formation.
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  • 35
    ISSN: 1432-0932
    Keywords: Pedicle fixation ; Posterior spine surgery ; Lumbar spine ; Complications
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Medial or lateral pedicle screw penetration with the potential to affect neural structures in a well-known and frequent problem associated with posterior spinal fusion. We evaluated the placement of pedicle screws (n = 141) in 36 patients following posterior lumbar spinal fusion with Socon or Kluger instrumentation via a lateral transpedicular approach. The examination was based on CT and MR images performed after removal of the instrumentation, on average 1 year after implantation. We found seven pedicle screws with lateral cortical penetration of the pedicle and five screws with medial cortical penetration of the pedicle (8.5% pedicle penetration overall). No severe radicular complications accompanied these pedicle penetrations. The mean insertion angles of the pedicle screws at the L4 level were 22.6° and 23.1° for the left and the right side, respectively. At the L5 level the mean insertion angle was 20.5° on the left side and 21.5° on the right, and at the S1 level the mean angle was 16.2° on the left and 15.2° on the right. The results of this study indicate that the lateral transpedicular approach is a safe procedure for pedicle screw insertion.
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  • 36
    ISSN: 1432-0932
    Keywords: Spinal surgery ; Pedicle screws ; Complications ; CT
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A prospective study of the accuracy of titanium pedicle screw placement in 30 low back operations was performed. The postoperative plain radiographs and CT reformation images were evaluated by two independent radiologists. Thirty-two out of 152 screws (21%) perforated the pedicle cortex. One-tenth of the perforations was detected with conventional radiography. In ten patients (33%) all the screws were located within the pedicle. The clinical significance of this study lies in the finding that pedicle perforations are more frequent than is generally believed and that, in spite of the many malplacements, no screw that perforated by less than 4.0 mm caused neurological problems. Only one nerve root lesion was detected.
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  • 37
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    Archives of gynecology and obstetrics 261 (1997), S. 9-13 
    ISSN: 1432-0711
    Keywords: Key words: Misoprostol ; Dinoprostone ; Labor induction ; Complications
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Sixty five pregnant women who had the indication for labor induction were randomized in a clinical trial to receive 100 µg. intravaginal misoprostol or intracervical gel of 0.5 mg dinoprostone. The mean time from induction to delivery for the misoprostol group was 7.6±1.9 versus 8.2±5.9 (hours±SD) for the dinoprostone group. There were no significant differences between groups in gestational age, induced labor rates, type of delivery, fetal outcome and maternal complications. We found that intravaginal misoprostol tablet is as effective as intracervical dinoprostone for inducing second and third trimester labor.
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  • 38
    ISSN: 1433-0385
    Keywords: Key words: Inguinal hernia ; Drainage ; Complications ; Ultrasound. ; Schlüsselwörter: Leistenhernie ; Drainage ; Komplikationen ; Sonographie.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung. In einer prospektiven randomisierten Studie wurden im Rahmen der Shouldice-Reparation primärer Hernien 50 Patienten mit subcutaner Redon-Drainage und 50 Patienten ohne Drainage versorgt. Postoperativ erfaßten wir die Menge des produzierten Wundsekrets in der Drainageflasche sowie durch sonographische Volumetrie, das Maß der subjektiven Beeinträchtigung mittels visueller Analogskala, die Höhe der Entzündungsparameter sowie die Komplikationsrate. Am ersten postoperativen Tag fand sich im drainierten Kollektiv mit 36,0 ml eine signifikant erhöhte Flüssigkeitsproduktion im Vergleich zu 2,5 ml in der Gruppe ohne Drainage. Zwei Wundinfekte wurden ebenfalls im drainierten Kollektiv beobachtet. Percutane Serompunktionen waren bei 8 Patienten, die ohne Drainage operiert wurden, und bei 7 drainierten Patienten notwendig. Das subjektive Empfinden war durch die Drainage nur geringfügig (25,6 vs. 21,4 %, visuelle Analogskala) beeinträchtigt. Die Körpertemperatur war im Drainagekollektiv am 3. postoperativen Tag im Vergleich zur nicht drainierten Gruppe erhöht (37,2 vs. 36,7 °C). Das routinemäßige Einlegen einer Redon-Drainage bei der Reparation primärer Leistenhernien ist aus unserer Sicht nicht indiziert. Vielmehr sollte bei Auftreten einer subcutanen Flüssigkeitsansammlung großzügig die Indikation zur percutanen Punktion gestellt werden.
    Notes: Summary. Following Shouldice repair of a primary inguinal hernia 50 patients were given subcutaneous Redon drains, while another 50 patients underwent operations without drains in a prospective randomized trial. The amount of postoperative wound secretion in the drainage bottle was added to fluid retention established by sonographic volumetric analysis. The degree of personal impairment was estimated by a visual analogue score. Inflammation parameters were recorded as well as the rate of complications. The drain group showed significantly increased fluid production in comparison to the group without drains on the 1st postoperative day (36.0 vs. 2.5 ml). Wound sepsis was found in two patients in the drain group. Seven patients with drains and eight patients without underwent percutaneous seroma puncture. The drain only slightly affected personal impairment (25.6 % vs 21.4 %, visual analogue score). Body temperature was elevated in the drain group on the 3rd day after operation (37.2 vs 36.7 °C). We believe there is no indication for the routine use of a Redon drain in the repair of a primary inguinal hernia. Instead, percutaneous puncture of subcutaneous fluid retentions should be performed.
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  • 39
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    European journal of plastic surgery 20 (1997), S. 202-204 
    ISSN: 1435-0130
    Keywords: Plastic day surgery ; Organization ; Complications ; Patient's opinion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Day surgery is increasing. This article reviews the experiences of day plastic surgery during a period of five years. The evaluation shows a low rate of postoperative complications and a high degree of patient satisfaction. According to the author's opinion a considerable part of elective plastic surgery is suitable for day surgery.
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  • 40
    ISSN: 1435-2451
    Keywords: Hernia repair ; Mesh ; Complications ; Biocompatibility ; Rat model ; Hernienchirurgie ; Netz ; Komplikationen ; Biokompatibilität ; Ratte
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Die moderne Hernienchirurgie bedient sich zunehmend Kunstnetzkonstruktionen zur Bauchwandrekonstruktion. Trotz der unbestrittenen Vorteile der z.Z. verfügbaren Kunstnetze mehren sich Berichte über Spätkomplikationen nach der Implantation. Eine Optimierung der Kunstnetze ist notwendig, bedingt aber ein standardisiertes Tiermodell zur Evaluierung der Biokompatibilität auf funktioneller und morphologischer Ebene. In der vorliegenden Studie werden z.T. handelübliche Polypropylen-und Polyesternetze in einem standardisierten Rattenmodell implantiert und detailliert morphologisch und morphometrisch analysiert. Die morphologisch-morphometrischen Daten werden in Anschluß mit der Funktion der künstlichen Bauchwand korreliert. Zusammenfassend zeigen die Daten, daß die z.Z. gebräuchlichen Netzkonstruktionen überdimensioniert sind und zu einer deutlichen Funktionseinschränkung der künstlichen Bauchwand führen. Die Funktion wird dabei entscheidend durch den Entzündungs- und Fibrosegrad, durch das Fibrosemuster und durch die Zusammensetzung der Extrazellularmatrix beeinflußt. Fibrose und Entzündung werden jedoch weniger durch das Material an sich bestimmt, sondern durch die Materialdichte,-verarbeitung und-ober-fläche. Zukünftige Netzkonstruktionen der 2. Generation sollten zur Verbesserung der funktionell-morphologisch definierten Biokompatibilität eine Reduzierung der Materialmenge und eine materialspezifische Verarbeitung anstreben.
    Notes: Abstract Modern surgical hernia repair depends increasingly on synthetic meshes for reconstruction of the abdominal wall. Despite the undisputed advantages of the synthetic meshes currently available, reports of late complications after implantation are accumulating. It is essential that the synthetic meshes be improved, but this makes a standardized animal model necessary for evaluation of their biocompatibility on both functional and morphological levels. In the present study, commercially available polypropylene and polyester meshes were implanted in a rat model, and detailed morphological and morphometric analysis were carried out. Correlations between the morphological and morphometric data and the function of the artificial abdominal wall were then sought. In summary, the data show that the mesh constructions currently available are oversized and definitely restrict the function of the artificial abdominal wall. The degree of inflammation and fibrosis, the pattern of fibrosis, and the composition of the extracellular matrix exert decisive influences on the function. Fibrosis and inflammation are caused less by the material itself, however, than by its density, the way it is processed, and its surface. Future, that is to say second-generated, mesh constructions should be designed with the aims of reducing the amount of material used and finding material-specific processing methods in mind, to improve the functionally and morphologically defined biocompatibility.
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  • 41
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    Langenbeck's archives of surgery 382 (1997), S. 192-196 
    ISSN: 1435-2451
    Keywords: Liver resection ; Infection ; Complications ; Multiple organ system failure ; Mortality ; Leberresektion ; Infektion ; Komplikationen ; Multiples Organversagen ; Mortalität
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Von 1986–1995 wurden 97 Patienten mit einem Alter 〉65 Jahre einer Leberresektion an der Abteilung für Allgemeinchirurgie des Krankenhauses Lainz, Wien, unterzogen. Das Durchschnittsalter der 39 Männer und 58 Frauen betrug 74±5,5 Jahre. Eine primäre Neoplasie der Leber war der Grund für die Leberresektion bei 35 Patienten, während 16 Patienten wegen eines Gallenblasenkarzinoms und 40 Patienten wegen Lebermetastasen reseziert wurden. In 73% der Patienten wurde eine größere Leberresektion (≥3 Segmente) bei einer gesamten Klinikmortalität von 13,5% durchgeführt. Bei 42 Patienten wurden 65 postoperative Komplikationen registriert, wobei Infektionen bei fast allen Patienten als Hauptproblem darstellten (95%). Die Histologie des Tumors hatte mehr Einfluß auf Klinikmortalität und Morbidität als die Größe der Leberresektion. Alle Komplikationen wurden bei Patienten mit maligner Grunderkrankung beobachtet (p=0,03). Eine ungünstige Auswirkung auf die postoperative Morbidität wurde bei Hepatikus- Gallenblasen-und cholangiozellularen Karzinomen beobachtet (p=0,003). Intraabdominale Infektionen wurden bei 25% unserer Patienten gefunden und waren in 58% auf Gallenleaks zurückzuführen, sie hatten aber keinen signifikanten Einfluß auf das Patientenüberleben. Pneumonie war die Komplikation, die sich besonders auf das Patientenüberleben auswirkte. Wenn eine Pneumonie als spätere Komplikation während eines komplizierten postoperativen Verlaufs auftrat, führte diese Konstellation bei allen betroffenen Patienten zum Tod (p=0,0001). Alle Patienten dieser Gruppe wiesen einen reduzierten Mobilisierungsgrad auf. Eine schwere präoperative Einschränkung der Leberfunktion hatte einen signifikanten Einfluß auf die postoperative Morbidität und Mortalität (p=0,003 und 0,01), ein Zusammenhang der sich bei einem Alter 〉80 Jahre noch verstärkte (p=0,002 und 0,004). Ein signifikantes Risiko für eine höhere postoperative Morbidität bestand nach rechten Lobektomien und erweiterten rechten Lobektomien (p=0,004). Zusammenfassend sind Infektionen mit nahezu jeder postoperativen Komplikation nach Leberresektionen im Alter assoziiert. Pneumonie stellt als Folgekomplikation ein prognostisch ungünstiges Zeichen bei älteren Patienten nach Leberresektionen dar. Patienten 〉65 Jahre und besonders jene 〉80 Jahre sterben eher an den vorwiegend infektiösen postoperativen Komplikationen. Bessere lokale Drainagen können möglicherweise die intraabdominalen Komplikationen reduzieren, und eine frühe Mobilisierung der Patienten ist möglicherweise in der Lage, die Rate systemischer, infektiöser Komplikationen und letztendlich die Klinikmortalität zu verbessern.
    Notes: Abstract From 1986 to 1995, 97 patients older than 65 years of age underwent hepatic resection at the Department of General Surgery, Hospital Lainz, Vienna. The population consisted of 39 men and 58 women with a mean age of 74±5.5 years. Primary neoplasia was the cause of resection in 35 patients, gallbladder cancer in 16 patients, and metastatic disease to the liver in 40 patients. Six patients underwent hepatic resection because of benign disease. The overall rate of major resections (≥3 liver segments) was 73% and the overall mortality was 13.5%. Sixty-five postoperative complications were recorded in 42 patients, and infection was the leading problem in nearly all of these patients (95%). The histologic type of tumor rather than the magnitude of resection had an influence on clinical mortality and morbidity. All complications occurred in patients with malignant disease (P=0.03). Adverse effects on postoperative morbidity were observed in adenocarcinoma of the hepatic ducts, gallbladder carcinoma, and cholangiocellular carcinoma (P=0.003). Intra-abdominal infections were found in 25% of our patients and were due to biliary leakage in 58%, but had no significant impact on survival. Pneumonia was the leading complication in association with patient survival. All patients who developed pneumonia as a late complication during a complicated course died postoperatively (P=0.0001). All of these patients had a reduced grade of mobilization. Severe preoperative liver dysfunction carried a significantly higher risk for postoperative morbidity and mortality (P=0.003 and 0.01), which showed an incremental risk with age 〉80 (P=0.002 and 0.0004). Right lobectomies and extended right lobectomies carried a significantly increased risk for postoperative morbidity (P=0.004). Infection is associated with nearly every complication recorded after hepatic resection in the elderly. Pneumonia as a late complication poses a worse prognosis in elderly patients who underwent hepatic resection. Patients older than 65 years of age and especially those older than 80 years of age are more liable to succumb to complications that are predominantly infectious. Better local drainage procedures may reduce intra-abdominal infectious complications and early mobilization of the patients may improve the rate of systemic infectious complications and final outcome.
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  • 42
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    Langenbeck's archives of surgery 382 (1997), S. 192-196 
    ISSN: 1435-2451
    Keywords: Key words Liver resection ; Infection ; Complications ; Multiple organ system failure ; Mortality ; Schlüsselwörter Leberresektion ; Infektion ; Komplikationen ; Multiples Organversagen ; Mortalität
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Von 1986 – 1995 wurden 97 Patienten mit einem Alter 〉65 Jahre einer Leberresektion an der Abteilung für Allgemeinchirurgie des Krankenhauses Lainz, Wien, unterzogen. Das Durchschnittsalter der 39 Männer und 58 Frauen betrug 74±5,5 Jahre. Eine primäre Neoplasie der Leber war der Grund für die Leberresektion bei 35 Patienten, während 16 Patienten wegen eines Gallenblasenkarzinoms und 40 Patienten wegen Lebermetastasen reseziert wurden. In 73% der Patienten wurde eine größere Leberresektion (≥3 Segmente) bei einer gesamten Klinikmortalität von 13,5% durchgeführt. Bei 42 Patienten wurden 65 postoperative Komplikationen registriert, wobei Infektionen bei fast allen Patienten als Hauptproblem darstellten (95%). Die Histologie des Tumors hatte mehr Einfluß auf Klinikmortalität und Morbidität als die Größe der Leberresektion. Alle Komplikationen wurden bei Patienten mit maligner Grunderkrankung beobachtet (p = 0,03). Eine ungünstige Auswirkung auf die postoperative Morbidität wurde bei Hepatikus- Gallenblasen- und cholangiozellularen Karzinomen beobachtet (p = 0,003). Intraabdominale Infektionen wurden bei 25% unserer Patienten gefunden und waren in 58% auf Gallen-leaks zurückzuführen, sie hatten aber keinen signifikanten Einfluß auf das Patientenüberleben. Pneumonie war die Komplikation, die sich besonders auf das Patientenüberleben auswirkte. Wenn eine Pneumonie als spätere Komplikation während eines komplizierten postoperativen Verlaufs auftrat, führte diese Konstellation bei allen betroffenen Patienten zum Tod (p = 0,0001). Alle Patienten dieser Gruppe wiesen einen reduzierten Mobilisierungsgrad auf. Eine schwere präoperative Einschränkung der Leberfunktion hatte einen signifikanten Einfluß auf die postoperative Morbidität und Mortalität (p = 0,003 und 0,01), ein Zusammenhang der sich bei einem Alter 〉80 Jahre noch verstärkte (p = 0,002 und 0,004). Ein signifikantes Risiko für eine höhere postoperative Morbidität bestand nach rechten Lobektomien und erweiterten rechten Lobektomien (p = 0,004). Zusammenfassend sind Infektionen mit nahezu jeder postoperativen Komplikation nach Leberresektionen im Alter assoziiert. Pneumonie stellt als Folgekomplikation ein prognostisch ungünstiges Zeichen bei älteren Patienten nach Leberresektionen dar. Patienten 〉65 Jahre und besonders jene 〉80 Jahre sterben eher an den vorwiegend infektiösen postoperativen Komplikationen. Bessere lokale Drainagen können möglicherweise die intraabdominalen Komplikationen reduzieren, und eine frühe Mobilisierung der Patienten ist möglicherweise in der Lage, die Rate systemischer, infektiöser Komplikationen und letztendlich die Klinikmortalität zu verbessern.
    Notes: Abstract From 1986 to 1995, 97 patients older than 65 years of age underwent hepatic resection at the Department of General Surgery, Hospital Lainz, Vienna. The population consisted of 39 men and 58 women with a mean age of 74±5.5 years. Primary neoplasia was the cause of resection in 35 patients, gallbladder cancer in 16 patients, and metastatic disease to the liver in 40 patients. Six patients underwent hepatic resection because of benign disease. The overall rate of major resections (≥3 liver segments) was 73% and the overall mortality was 13.5%. Sixty-five postoperative complications were recorded in 42 patients, and infection was the leading problem in nearly all of these patients (95%). The histologic type of tumor rather than the magnitude of resection had an influence on clinical mortality and morbidity. All complications occurred in patients with malignant disease (P = 0.03). Adverse effects on postoperative morbidity were observed in adenocarcinoma of the hepatic ducts, gallbladder carcinoma, and cholangiocellular carcinoma (P = 0.003). Intra-abdominal infections were found in 25% of our patients and were due to biliary leakage in 58%, but had no significant impact on survival. Pneumonia was the leading complication in association with patient survival. All patients who developed pneumonia as a late complication during a complicated course died postoperatively (P = 0.0001). All of these patients had a reduced grade of mobilization. Severe preoperative liver dysfunction carried a significantly higher risk for postoperative morbidity and mortality (P = 0.003 and 0.01), which showed an incremental risk with age 〉80 (P = 0.002 and 0.0004). Right lobectomies and extended right lobectomies carried a significantly increased risk for postoperative morbidity (P = 0.004). Infection is associated with nearly every complication recorded after hepatic resection in the elderly. Pneumonia as a late complication poses a worse prognosis in elderly patients who underwent hepatic resection. Patients older than 65 years of age and especially those older than 80 years of age are more liable to succumb to complications that are predominantly infectious. Better local drainage procedures may reduce intra-abdominal infectious complications and early mobilization of the patients may improve the rate of systemic infectious complications and final outcome.
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  • 43
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    Langenbeck's archives of surgery 382 (1997), S. 49-54 
    ISSN: 1435-2451
    Keywords: Key words Conventional reconstruction ; Abdominal aorta ; Complications ; Endovascular reconstructive surgery ; Schlüsselwörter Rekonstruktive Gefäßchirurgie der Beckenetage ; Komplikationen ; endovaskuläre Rekonstruktion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Im Zeitraum von September 1985 bis Februar 1994 wurde bei 183 Patienten ein rekonstruktiver Eingriff im aortoiliakalen Bereich durchgeführt. Die Grunderkrankung war in 108 Fällen eine arterielle Verschlußkrankheit, in 75 Fällen ein abdominales Aortenaneurysma. Bei 120 Patienten wurde eine Bifurkationsprothese, bei 63 Patienten eine Rohrprothese implantiert. Die Früh- und Spätkomplikationen werden beschrieben, differenziert nach chirurgisch und nichtchirurgisch, wobei die chirurgischen Komplikationen im wesentlichen durch die Prothesenart und durch den Leistenanschluß bedingt waren, während die nichtchirurgischen Komplikationen vom Risikoprofil des Krankenguts abhängig waren. Die Unterschiede in der postoperativen Letalität ergaben sich durch die Dringlichkeit des Eingriffs. Der Stellenwert der endovaskulären Rekonstruktion im Vergleich zur rekonstruktiven Gefäßchirurgie wird diskutiert.
    Notes: Abstract From September 1985 to February 1994, 183 pa- tients (arterial occlusive disease n = 108, abdominal aneurysm n = 75) underwent reconstruction of the abdominal aorta. In 120 patients an aorto-bi-iliac or aorto-bi-femoral reconstruction was performed and in 63 patients a tube-type reconstruction. The early and late postoperative complications are described. The complications were dependent on the choice of graft, the distal anastomosis and the preoperative risk factors. The mortality from elective repairs was compared with the mortality in emergency repairs. The role of endovascular reconstructive surgery in comparison to conventional reconstructive procedures is discussed.
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  • 44
    ISSN: 1435-2451
    Keywords: Key words Hernia repair ; Mesh ; Complications ; Biocompatibility ; Rat model ; Schlüsselwörter Hernienchirurgie ; Netz ; Komplikationen ; Biokompatibilität ; Ratte
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Die moderne Hernienchirurgie bedient sich zunehmend Kunstnetzkonstruktionen zur Bauchwandrekonstruktion. Trotz der unbestrittenen Vorteile der z.Z. verfügbaren Kunstnetze mehren sich Berichte über Spätkomplikationen nach der Implantation. Eine Optimierung der Kunstnetze ist notwendig, bedingt aber ein standardisiertes Tiermodell zur Evaluierung der Biokompatibilität auf funktioneller und morphologischer Ebene. In der vorliegenden Studie werden z.T. handelübliche Polypropylen- und Polyesternetze in einem standardisierten Rattenmodell implantiert und detailliert morphologisch und morphometrisch analysiert. Die morphologisch-morphometrischen Daten werden in Anschluß mit der Funktion der künstlichen Bauchwand korreliert. Zusammenfassend zeigen die Daten, daß die z.Z. gebräuchlichen Netzkonstruktionen überdimensioniert sind und zu einer deutlichen Funktionseinschränkung der künstlichen Bauchwand führen. Die Funktion wird dabei entscheidend durch den Entzündungs- und Fibrosegrad, durch das Fibrosemuster und durch die Zusammensetzung der Extrazellularmatrix beeinflußt. Fibrose und Entzündung werden jedoch weniger durch das Material an sich bestimmt, sondern durch die Materialdichte, -verarbeitung und -oberfläche. Zukünftige Netzkonstruktionen der 2. Generation sollten zur Verbesserung der funktionell-morphologisch definierten Biokompatibilität eine Reduzierung der Materialmenge und eine materialspezifische Verarbeitung anstreben.
    Notes: Abstract Modern surgical hernia repair depends increasingly on synthetic meshes for reconstruction of the abdominal wall. Despite the undisputed advantages of the synthetic meshes currently available, reports of late complications after implantation are accumulating. It is essential that the synthetic meshes be improved, but this makes a standardized animal model necessary for evaluation of their biocompatibility on both functional and morphological levels. In the present study, commercially available polypropylene and polyester meshes were implanted in a rat model, and detailed morphological and morphometric analysis were carried out. Correlations between the morphological and morphometric data and the function of the artificial abdominal wall were then sought. In summary, the data show that the mesh constructions currently available are oversized and definitely restrict the function of the artificial abdominal wall. The degree of inflammation and fibrosis, the pattern of fibrosis, and the composition of the extracellular matrix exert decisive influences on the function. Fibrosis and inflammation are caused less by the material itself, however, than by its density, the way it is processed, and its surface. Future, that is to say second-generated, mesh constructions should be designed with the aims of reducing the amount of material used and finding material-specific processing methods in mind, to improve the functionally and morphologically defined biocompatibility.
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  • 45
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    European archives of oto-rhino-laryngology and head & neck 254 (1997), S. 384-386 
    ISSN: 1434-4726
    Keywords: Chronic otitis media ; Cholesteatoma ; Tympanomastoid surgery ; Complications ; Deafness
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Preoperative and postoperative bone conduction thresholds were compared in 181 chronic ears operated on over a 5-year period between 1990 to 1994. In the majority (92%) of cases the bone conduction thresholds remained unchanged (± 10 dB). Nine ears (5%) showed better thresholds after surgery, with improvements ranging from 11 dB to 25 dB. This improvement was especially noted in ears with severe tympanic pathology. One ear with a large labyrinthine fistula became totally deaf after surgery. In 5 ears (3%) bone-conduction thresholds deteriorated, but remained measurable at all frequencies tested. In these latter cases this impairment ranged from 11 dB to 27 dB. Cholesteatomatous ears having intact ossicular chains were found to be at the highest risk of inner ear damage when “canal wall-down” mastoidectomies were performed. Methods for prevention of sensorineural hearing loss following chronic ear surgery are discussed.
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  • 46
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    European journal of plastic surgery 20 (1997), S. 220-222 
    ISSN: 1435-0130
    Keywords: Pacemaker ; Complications ; Extrusion ; Salvage ; Greater omentum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The extrusion of a pacemaker, due to infectious or mechanical problems, is a condition that usually requires the removal of the device and implantation of a new pacemaker. A case is presented in which an extruded pacemaker was successfully salvaged using the greater omentum as a wrap-around pedicled flap. The current protocol for salvaging exposed pacemakers at the authors' center is described.
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  • 47
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    European journal of plastic surgery 20 (1997), S. 77-79 
    ISSN: 1435-0130
    Keywords: Cleft lip and palate ; Complications ; Length of hospital stay
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We studied the occurrence of early complications of cleft lip and palate surgery by the retrospective study of 132 consecutive cases (160 procedures) operated between three and six months of age. Three children presented with major complications within the immediate postoperative period. All were treated successfully. A local complication directly related to the operation occurred in 7.5% of the cases within the first six postoperative days. In 17%, a general complication not directly related to the operation was observed. The majority of these general complications were cross infections during the hospital stay. These observations led us to reduce the hospital stay to one day for cleft lip and five days for cleft palate and cleft lip and palate operations without compromise to safety but with a reduction of the morbidity and hence the treatment costs and of the child-family disturbance.
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  • 48
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    Angewandte Makromolekulare Chemie 244 (1997), S. 43-66 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The market development of bisphenol-A-polycarbonate has shown higher growth than any other engineering thermoplastic. The reasons can be found in the permanent improvement of the cost/performance-relationship and in the technical use of the variability of the basic structure. Incorporation of specific monomer units leads to tailor-made properties for a wide range of applications, as for example medical devices, electronic parts and glazing.This process has not yet slowed down, rather it is accelerated by new results from research and development. The improvement of flaw behavior and pit replication for new grades of materials for the next generation of compact discs, new grades that can be sterilized by γ-radiation without degradation and the microstructuring by low-energy laser systems are examples for the ongoing expansion of polycarbonate applications. Surface modification by hardcoatings with nanosized particles will allow to enter the fast growing market of glazing.
    Additional Material: 27 Ill.
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  • 49
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    Angewandte Makromolekulare Chemie 244 (1997), S. 67-92 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Polyamide, Polyester und Polyoxymethylen sind mit einem weltweiten Verbrauch von derzeit 2,4 Mio t pro Jahr wichtige technische Kunststoffe. Sie werden aufgrund ihrer besonderen Eigenschaftsprofile überwiegend im Fahrzeugbau und in der Elektroindustrie für hochbelastete Funktionsbauteile eingesetzt. Der vorliegende Beitrag behandelt Polymerisationswege, Eigenschaften und ausgewählte neue Entwicklungen dieser Polymerklassen.Teilaromatische Polyamide stoßen durch ihre Dimensionsstabilität und thermische Belastbarkeit in Anwendungen vor, die bisher Duromeren oder Metallen vorbehalten waren. Glasfaserverstärkte Polyamide mit besonders hoher Dauerwärmebeständigkeit übemehmen wichtige Funktionen im Motorbereich von Fahrzeugen. Polyamid-Blends sind als Karosseriewerkstoffe ein Schlüssel zu leichten Autos mit niedrigem Treibstoffverbrauch. Halogenfrei flammgeschützte Polyamide erhöhen Sicherheit und Umweltverträglichkeit in brandgefährdeten Anwendungsbereichen.Polybutylenterephthalat als technisch wichtigster Polyester eröffnet in Mischung mit amorphen Polymeren neue Perspektiven durch geringerenVerzug und bessere Oberfläche bei glasfaserverstärkten Teilen. Polybutylennaphthalat erweitert den Anwendungsbereich zu höheren Temperaturen. Von Polybutylenterephthalat abgeleitete Copolyester sind biologisch abbaubar und daher vielversprechend für kompostierbare Folien.Polyoxymethylen-Copolymere haben ihre Stärke in der günstigen Kombination aus Steifigkeit, Dimensionsstabilität, Gleit/Reibe-Verhalten und Beständigkeit gegen heißes Wasser und Kraftstoff.Aufgrund ihres hohen und noch weiter steigerungsfähigen Leistungsvermögens werden Polyamide, Polyester und Polyoxymethylen das in den letzten Jahren gezeigte Wachstum in Zukunft weiter ausbauen können.
    Notes: Polyamide, polyester and polyoxymethylene having presently a worldwide sales volume of 2,4 million tons a year are important engineering thermoplastics. Based on their special property profiles they are mainly used in the automotive and electronic industry for high performance functional parts. This contribution presents polymerisation processes, properties, and selected new developments for these polymer classes.Semiaromatic polyamides due to their dimensional stability and thermal resistance lend themselves to applications which were so far reserved for thermosets or metals. Glass fiber reinforce polyamides designed to have the highest possible heat ageing resistance can take important functions under the hood. A polyamide blend used as a material for exterior body parts is key to light weight cars with strongly reduced fuel consumption. Halogene free flame retardant polyamide increases fire safety and environmental safety in flame sensitive applications.Polybutyleneterephthalate as the technically most important polyester offers new perspectives in blends with amorphous polymers leading to lower distortion and better surface quality in glass fiber reinforced parts. Polybutylenenaphthalate is widening the range of application of polyesters towards higher temperatures. Copolyesters derived from polybutyleneterephthalate are biologically degradable and are therefore promising materials for fermentable foils.Polyoxymethylene copolymers show an outstanding combination of stiffness, dimensional stability, friction and wear as well as resistance against hot water and fuel.As a result of their excellent properties and the existing potential for further improvements polyamide, polyester and polyoxymethylene will continue to grow above average in the future.
    Additional Material: 18 Ill.
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  • 50
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    Angewandte Makromolekulare Chemie 244 (1997), S. 121-133 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The world-wide production of polyurethanes has exceeded 6 mio. metric tons in 1994. Compared with the produced amounts of large-scale thermoplastics such as PE, PVC, PP and PS, polyurethanes keep the 5th place.Polyurethanes (PUR) are segmented polymers, which can be synthesized from preformed building blocks in a modular unit construction system. The chemical modules and the various possibilities of combination will be discussed here.Tailor-made polyurethane materials can be divided into two main-fields of application: foams and compact PUR.The main constituents of polyurethane materials are diisocyanates and polyols. These key- chemicals are well characterised with respect to their technological, economical and ecological properties. Taking into account the availability, the masses of production and the experiences that have been collected with the PUR main constituents, these PUR precursors seem to be very mature already.In contrast to this, the PUR-materials made from these building blocks still offer numerous novel problem-solutions, resulting from the variability of the diisocyanate-poly-addition reaction: PUR materials are most commonly segmented into several phases. The formation of hard- and softsegments can be easily demonstrated by looking at thermoplastic polyurethanes (TPU). A deeper understanding of this phase separation and the molecular organisation within these materials promises to realize prospectic polymeric architectures with new and improved properties. PUR materials will still be able to offer new answers to future requirements in balancing economical and ecological needs. By looking at the life-cycles of soft and hard-foams, polyurethane-coatings and thermoplastic PUR-elastomers, this contribution will adress the question: “Is PUR-chemsitry still a challenging field?”
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  • 51
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    Angewandte Makromolekulare Chemie 245 (1997), S. 23-35 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Zugabe von 10-20 Gew.-% Kaliumnitrat (KN03) zu Polyamid 6 (PA 6) vermindert die Brennbarkeit des Polymeren. Das thermische Verhalten der KN03/PA 6-Mischung wurde mittels Thermogravimetrie, Differentialkalorimetrie und Analyse der fluchtigen Anteile untersucht. Feste Zersetzungsprodukte der Mischung wurden mittels Infrarotspektroskopie, Rontgendiffraktometrie und Elektronenresonanzspek-'troskopie analysiert. Es wurde gefunden, daß KNO3 dem Flielßen und Tropfen der Schmelze vorbeugt und die Karbonisierung auf der Oberflache des Polymeren fordert. Das verringert die Brandgefahr und verbessert die Feuerbestandigkeit. Andererseits geht KNO3 mit PA 6 in der kondensierten Phase eine exotherme Reaktion ein und setzt Sauerstoff frei, der wiederum die Brennbarkeit von PA 6 begiinstigt. Der Mechanismus der chemischen Wechselwirkung van KNO3 mit PA 6 wird diskutiert.
    Notes: The addition of 10-20 wt.-% of potassium nitrate (KNO3) to polyamide 6 (PA 6) improves the fire retardance of the polymer. The thermal decomposition behaviour of the PA 6/KN03-mixture was studied using thermogravimetry, differential scanning calorimetry and thermal volatilisation analysis. Solid products of the thermal decomposition of the mixture were analysed by infrared spectroscopy, X-ray diffraction and electron paramagnetic resonance. It was found that KNO, prevents flowing and dripping of the melt and promotes charring on the surface of the polymer which decreases its fire hazard and improves its fire retardance. On the other hand, KNO3 exothermally reacts with PA 6 in the condensed phase and supplies oxygen to the gas phase which increases the combustibility of PA 6. The mechanism of the chemical interaction of KN03 with PA 6 is discussed.
    Additional Material: 8 Ill.
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  • 52
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    Angewandte Makromolekulare Chemie 245 (1997), S. 49-62 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Der Einfluß einer Beimischung von Tricalciumphosphat (TCP), Hydroxyethylmethacrylat (HEMA) und Ethylenglycoldimethacrylat (EGDMA) auf die Eigenschaften eines chirurgischen Knochenzements wurde untersucht. Die in Zugversuchen entstandenen Bruchflächen wurden mittels Rasterelektronenmikroskopie charakterisiert. Der Einfluß der Additive auf den Temperaturanstieg während der Polymerisation wurde geprüft. Zug-, Biege- und Druckfestigkeit des ausgehärteten Zements nahmen mit zunehmendem TCP-Gehalt ab, der Elastizitätsmodul stieg dagegen an. Die Zugfestigkeit nahm mit steigendem HEMA-Gehalt geringfügig zu und blieb oberhalb 15 Gew.-% HEMA konstant. Zug-, Biege- und Druckfestigkeit zeigten bei einem EGDMA-Gehalt von 2 Gew.-% (in HEMA) ein Maximum. HEMA und EGDMA beschleunigten die Polymerisation, wogegen TCP retardierend wirkte.
    Notes: The effects of the addition of tricalcium phosphate (TCP), hydroxyethyl methacrylate (HEMA), and ethylene glycol dimethacrylate (EGDMA) on the properties of standard surgical Simplex-P radiopaque bone cement have been investigated. The fracture surface after tensile test was studied by scanning electron microscopy. The influence of these components on the temperature rise during polymerization was investigated. It was found that the tensile strength, the bending strength, and the compressive strength decreased with increasing TCP content, whereas the inverse was observed for the Young's modulus. The tensile strength slightly increased with increasing HEMA content and then it levelled off when the HEMA content was higher than 15 wt.-%. It seemed that there were maximum tensile, bending and compressive strengths when 2 wt.-% EGDMA (in HEMA) was added. Polymerization occurred more rapidly when HEMA and EGDMA were added, whereas the inverse result was found with TCP.
    Additional Material: 7 Ill.
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  • 53
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    Angewandte Makromolekulare Chemie 245 (1997), S. 89-104 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Polyurethanelastomere wurden in Gegenwart von zwei Dihydroxynaphthalin(DHN)-Verbindungen und deren bromierter Derivate als Kettenverlängerer hergestellt. Als Polyole wurden Polycaprolactondiol und Polytetramethylenglykol und als Diisocyanat-Komponenten Diphenylmethandiisocyanat (MDI) und Dicyclohexylmethan-4,4′-diisocyanat (HMDI) eingesetzt. Der Einfluß der Struktur der Kettenverlängerer auf die physikalischen und thermischen Eigenschaften der Polyurethane wurde untersucht. Wegen der besseren Phasenmischungswirkung der 1,5-DHN-Segmente haben die damit hergestellten Polyurethane höhere Glasübergangstemperaturen und bessere dynamische Eigenschaften als die Polyurethane auf 2,7-DHN-Basis. Der Einbau von bromierten DHN-Einheiten erschwert die Entflammbarkeit. Durch das große freie Volumen der Bromatome wird jedoch die Rotation der DHN-Einheiten eingeschränkt, was zu Polyurethanen mit verringerten Phasenmischungs- und Kristallisationsgraden führt. Die bromhaltigen Polyurethane zeigen zudem eine Verschlechterung der mechanischen und physikalischen Eigenschaften und eine erhöhte Löslichkeit.
    Notes: Polyurethane elastomers were synthesized based on polyols such as poly(caprolactonediol) and poly(tetramethylene glycol), diisocyanates such as diphenylmethane-4,4′-diisocyanate (MDI) and dicyclohexylmethane-4,4′-diisocyanate (HMDI), and two dihydroxynaphthalenes (DHNs) and their brominated derivatives used as chain extenders. The effects of the chemical structures of the chain extenders on the physical and thermal properties of the polyurethanes were investigated. Because of the higher degree of phase mixing of the 1,5-DHN unit, the 1,5-DHN-based polyurethanes have higher Tg values and higher dynamic properties than 2,7-DHN-based polyurethanes. Introduction of bromine atoms increased the flame retardance. However, the large free volume of bromine atoms restricted the rotation of DHNs, thus, directly decreasing the degree of phase-mixing and crystallinity of the polyurethanes. Introducing bromine atoms also decreased the mechanical and dynamic properties and increased the solubility of the polyurethanes.
    Additional Material: 1 Ill.
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  • 54
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    Angewandte Makromolekulare Chemie 245 (1997), S. 139-147 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Aus Poly(oxytetramethylen), 4,4′-Bibenzyldiisocyanat, N-Methyldiethanolamin als Kettenverlängerer und Acrylsäure/Polyacrylsäure als Quaternisierungsagens wurden Poly(etherurethan)-Kationomere hergestellt. In aus diesen Kationomeren hergestellten Filmen wurde Pyrrol (15 Gew.-%) in Gegenwart von CuCl2 polymerisiert. Die Filme wurden mittels dynamisch-mechanischer Analyse, Thermogravimetrie und Differentialthermoanalyse charakterisiert. Die elektrische Leitfähigkeit beträgt für den Film ohne Polypyrrol 7.5 · 10-12 Ω-1 cm-1 und mit Polypyrrol 4.5 · 10-6 Ω-1 cm-1.
    Notes: Poly(ether urethane) cationomers based on poly(oxytetramethylene), 4,4′-bibenzyldiisocyanate, N-methyldiethanolamine as chain extender, and acrylic acid/poly(acrylic acid) as quaternization agent were synthesized. Pyrrole (15 wt.%%) was polymerized in films of the ionomer containing CuCl2. The films were characterized by dynamic mechanical analysis, thermogravimetry and differential scanning calorimetry. The electric conductivity of the film without polypyrrole is 7.5 · 10-12 Ω-1 cm-1, while incorporation of polypyrrole increases the conductivity to 4.5 · 10-6 Ω-1 cm-1.
    Additional Material: 2 Ill.
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  • 55
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    Angewandte Makromolekulare Chemie 245 (1997), S. 155-164 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Wachsartige Monomere und Vernetzer wurden aus kommerziellen Wachsen durch Veresterung mit 2-Hydroxyethylmethacrylat, Glycerindimethacrylat oder Glycidylmethacrylat oder durch Funktionalisierung mit 2-Isocyanatoethylmethacrylat synthetisiert. Die erhaltenen opaken Methacrylate mit Schmelzpunkten zwischen 45 und 80°C wurden in Substanz bzw. Toluollösung in Gegenwart von Radikalinitiatoren polymerisiert. Die Polymeren zeichnen sich durch eine breite Molmassenverteilung aus. Im Gegensatz zur Substanzpolymerisation ist der Doppelbindungsumsatz nach der Lösungspolymerisation nahezu vollständig. Aufgrund der hohen Molmasse der Monomeren ist der beobachtete Polymerisationsschrumpf sehr gering. Polymerisate mit Vernetzermonomeren zeigen eine verbesserte mechanische Stabilität.
    Notes: Waxy monomers and crosslinkers, respectively, were synthesized from commercially available waxes by esterification with 2-hydroxyethyl methacrylate, glycerol dimethacrylate, or glycidyl methacrylate or by functionalization with 2-isocyanatoethyl methacrylate. The resulting opaque methacrylates with melting points between 45 and 80°C were polymerized in bulk and in toluene solution in presence of free radical initiators. The obtained polymers were characterized by a broad molecular weight distribution. Opposite to the bulk polymerization, the double bond conversion in solution polymerization is nearly quantitative. The observed volume shrinkage during polymerization is very low due to the high molecular weight of the monomers. Polymerizates containing crosslinking comonomers exhibit improved mechanical stability.
    Additional Material: 5 Tab.
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  • 56
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 245 (1997), S. 165-181 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The stabilized free-radical precipitation polymerization of the cationic monomer N-(2-methacryloyloxyethyl)-N,N-dimethylbenzylammonium chloride (MADAMBQ) in aqueous solutions of sodium chloride was studied by reaction calorimetry. Poly(ethylene oxide) was used as stabilizer. The rate of polymerization reaches its maximum immediately after initiation and remains nearly constant up to 50 % conversion followed by a decrease that could be described by a first order kinetics. The particles formed are approximately 1 to 30 μm in diameter and are stable over a period of several months.A model based on the theory of homogeneous particle nucleation is suggested to describe the kinetic course of polymerization, taking into account the rate of polymerization in both phases. With the assumption that the concentration of monomer in the phases is determined by a Nernst distribution law, the kinetics of the early stage of polymerization can be modelled reasonably well.The solution polymerization and the unstabilized precipitation polymerization of MADAMBQ was also studied.
    Notes: Die Kinetik der stabilisierten Fällungspolymerisation des kationischen Monomeren N-(2-Methacryloyloxyethyl)-N,N-dimethylbenzylammoniumchlorid (MADAMBQ) in wäßrigen Natriumchlorid-Lösungen wurde mittels Reaktionskalorimetrie untersucht. Polyethylenoxid höherer Molmasse wurde als Stabilisator eingesetzt. Die Reaktionsgeschwindigkeit ist über einen größeren Umsatzbereich nahezu konstant und fällt anschließend mit dem Umsatz annähernd linear ab. Die Teilchengrößenverteilung der gebildeten Dispersion ist bimodal mit Teilchen von etwa 1 bis 30 μm Durchmesser.Zur Beschreibung des Geschwindigkeitsverlaufs der Fällungspolymerisation wird ein Modell vorgeschlagen, das die Polymerisation in der Wasser- sowie in der Polymerphase berücksichtigt. Die Teilchenbildung soll durch homogene Nukleierung erfolgen. Es wird angenommen, daß die Konzentration des Monomeren in den Phasen durch ein Nernstsches Verteilungsgleichgewicht bestimmt wird. Zu Vergleichszwecken wurde auch die Polymerisation von MADAMBQ in Lösung und als nicht stabilisierte Fällungspolymerisation durchgeführt.
    Additional Material: 8 Ill.
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  • 57
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Cellulosepulver, hergestellt durch Nitrierung von Eichen-Furfural-Lignocellulose, wurde mit Acrylamid radikalisch gepfropft. Die Pfropfreaktion wurde sowohl in Gegenwart eines äußeren Magnetfeldes (0,15-0,35 T) als auch ohne Magnetfeld durchgeführt. Der Einfluß von Monomerkonzentration, Initiatorkonzentration, Polymerisationszeit und temperatur sowie der magnetischen Feldstärke auf den Polymerisationsverlauf wurde untersucht. Es wurde festgestellt, daß der Pfropfumsatz mit zunehmender Feldstärke signifikant ansteigt.
    Notes: Cellulose powder obtained from oak furfural lignocellulose by nitration reaction was grafted with acrylamide using a radical initiation. The grafting reactions were carried out and compared both in presence and in absence of a continuous external magnetic field with the intensity extended between 0.15-0.35 T. The effect of monomer and initiator concentration, time and temperature of reaction and magnetic field intensity onto the grafting process were examined. It was observed that the presence of a magnetic field leads to a significant increase of the graft conversion.
    Additional Material: 4 Ill.
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  • 58
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Poly(L-milchsäure) ist ein biokompatibler, semikristalliner, thermoplastischer Polyester mit ungünstigen mechanischen Eigenschaften. Daher wurde in einem “reactive blending”-Prozeß ein Acrylkautschuk, n-Butylacrylat, mittels einer Suspensionspolymerisation in Wasser auf in einem organischen Lösungsmittel gelöste Poly(L-milchsäure) gepfropft. Die gebildeten Copolymeren konnten isoliert und durch NMR-Spektroskopie und DSC-Messungen charakterisiert werden. Die Untersuchung der mechanischen Eigenschaften ergab keine befriedigenden Ergebnisse, weil die Kautschukphase wahrscheinlich aus viskosen linearen Makromolekülen besteht und daher keine elastischen Eigenschaften besitzt. In weiteren Arbeiten soll der Syntheseweg so modifiziert werden, daß durch den Einbau von Diacrylaten eine zumindest partielle Vernetzung der Kautschukphase erreicht wird.
    Notes: Poly(L-lactic acid) is a biocompatible polyester, semicrystalline, thermoplastic, with low versatility in mechanical properties. To overcome this problem, a reactive blending procedure was performed by grafting an acrylic rubber, n-butyl acrylate, via water suspension polymerization onto poly(L-lactic acid) dissolved in an organic solvent. It was possible to isolate the copolymeric phase formed from the two polymers and characterize it by using NMR and DSC techniques. Mechanical tests on blends gave no satisfactory response, probably because the rubbery phase is composed essentially of viscous linear macromolecules, not able to perform elastic properties. Work is in progress to modify the synthetic pathway to incorporate diacrylates in order to realize a rubbery phase at least partially cross-linked.
    Additional Material: 7 Ill.
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  • 59
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Zur Entwicklung von neuen Styrol-Butadien-Kautschuken (SBRs) für Reifenanwendungen sind mehrere Arten von Zinn-Polymer-Bindungen (Styryl-, Butadienyl-, Isoprenyl- and α-Methylstyryl-Zinn) sowohl in linearen als auch in verzweigten Ketten untersucht worden. Die dynamisch-mechanischen Eigenschaften von Vulkanisaten mit Ruß wurden analysiert, um eine Beziehung zwischen den Strukturparametern der Polymeren und den Materialeigenschaften herzustellen. Der Polymer-Füll-stoff-Wechselwirkungsparameter, der durch das Verhältnis von mechanischen und dynamischen Termen definiert ist, wurde zur Charakterisierung der Verbindungen herangezogen. Der Einbau von verschiedenen Zinn-Polymer-Bindungen in lineare und in verzweigte SBR-Ketten bewirkte eine Verbesserung der Hystereseeigenschaf-ten der Vulkanisate und eine Veranderung des Wechselwirkungsparameters.
    Notes: Following the development of new SBRs for tyre applications, several kinds of tin-polymer bonds (styryl-, butadienyl-, isoprenyl- and α-methylstyryltin) have been studied, in both branched and linear chains.Dynamic-mechanical properties of the carbon black vulcanizates have been analyzed to establish a relationship between structural parameters of polymers and compound properties. The filler-polymer interaction parameter, defined by a ratio of mechanical and dynamic terms, has been used for the evaluation of the compounds. The introduction of different types of tin-polymer bonds, in branched and linear chains of the SBRs, implies an improvement in the hysteresis properties of the vulcanizates as well as a modification of the interaction parameter.
    Additional Material: 1 Ill.
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  • 60
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Copoly (amid-ether) rnit zwei unteschiedlichen Aminfunktionalitäten wurden als antistatische Modifikatoren für Polyethylenterephthalatfasern (PET) eingesetzt. Die tertiären Aminogruppen schmelzegesponnener Copolymerfilamente wurden rnit drei Alkylierungsmitteln umgesetzt, wobei ein Sulfobetain, ein Carbobetain bzw. Ammoniumionen gebildet wurden. Dadurch wurde der scheinbare spezifische Widerstand der Filamente auf größfienordnungsmäßfiig 106 bis 108 Ω/cm verringert. Da sich die quaternisierten Copolymeren beim Blend-Spinnen rnit PET zersetzen, wurden Blendfasern von PET mit einem Copolymeren nach dem Schmelzespinnen einer Quaternisierung oder Vernetzung rnit Alkylierungsmitteln bzw. Epoxyvernetzern unterzogen, was die antistatischen Eigenschaften der Fasern im Vergleich rnit der unbehandelten Faser verbesserte. Insbesondere die mit Epoxiden vernetzten Fasern wiesen antistatische Eigenschaften auf, wie sie mit dieser Modifizierungsmethode bislang nicht erreicht wurden. Die antistatischen Eigenschaften blieben nach dem Fkben erhalten, da sowohl die hydrophilen als auch die ionischen Gruppen auf der Faseroberflache immobilisiert waren. Da Quaternisierung bzw. Vernetzung in einem Arbeitsgang rnit dem Verspinnen und Verstrecken der Fasern innerhalb einer kurzen Reaktionszeit erfolgen, sollte diese “spin-finishing„ genannte Methode konventio- nellen Verfahren bezuglich Kosten und Produktivitat uberlegen sein.
    Notes: Copoly(amide-ethers) containing two types of tertiary amine units were made as antistatic modifiers for poly(ethylene terephthalate) (PET) fibers. The filaments of the copolymers were melt-spun and reacted with three alkylating agents in order to quaternize the tertiary amine into a sulfo-betaine, a carbobetaine, and an ammonium ion. The apparent electric resistivity of the filaments was greatly reduced by this reaction, being in the range of 106 to 108 Ω/cm. However, because these quaternized copolymers incurred decomposition during blend spinning with PET, a blend PET fiber containing one type of copoly(amide-ether) was melt-spun and subjected to quaternization of the amino groups as well as to surface crosslinking with various alkylating and epoxy agents. The quaternized blend fibers obtained showed improved antistatic properties compared with the original blend fiber. Particularly, the fibers crosslinked with epoxy compounds were found to have the best antistatic properties that had ever been attained with this type of modification. The antistatic properties were retained even after dyeing, because both hydrophilic and ionic groups had been effectively immobilized on the surface. Since this quaternization and crosslinking could be conducted on-line with spinning and drawing within a short reaction time, this modification technique is called “spin-finishing method”, which should be superior to the conventional methods in terms of cost performance and productivity.
    Additional Material: 4 Ill.
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  • 61
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 249 (1997), S. 33-46 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Filme aus Polyethylen niedriger Dichte (LDPE) wurden mit rauchender Salpetersäure behandelt. Die Oberflächeneigenschaften sowie die Bildung polarer Gruppen wie auf der geätzten Filmoberfläche wurden mit SEM-, IR- und XPS-Methoden analysiert. Die mechanische Festigkeit eines aus dem geätzten LDPE-Film und einem Epoxidharz hergestellten Laminats sowie die Bedruckbarkeit der geätzten Oberflächen wurden untersucht und mit einer unbehandelten Probe verglichen. Die Oberflächenrauhigkeit und die Gegenwart polarer Gruppen erhöhen die mechanische Festigkeit des Laminats aus dem geätzten Film durch mechanische Verankerung und chemischer Wechselwirkungen. Die Oberfläche des behandelten LDPE-Films ist besser bedruckbar als die des unbehandelten Films.
    Notes: Low-density polyethylene (LDPE) films were treated with fuming nitric acid (FNA). The surface characteristics and also the insertion of polar groups like on the etched LDPE film surface were measured by SEM, IR and XPS analyses, respectively. The mechanical performance of a laminate of the etched film with epoxy resin and also the printability of the etched film surface were tested and compared with the unetched sample. The surface roughening and the presence of polar groups enhance the mechanical strength of the laminate of FNA-treated film due to mechanical interlocking and chemical interaction. The printability of the treated film surface is also superior to that of the untreated LDPE film surface.
    Additional Material: 10 Ill.
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  • 62
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 249 (1997), S. 11-32 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: This paper reports on polymer membranes characterized by a surface layer of hydroxyalkyl derivatives of cellulose. Water compatible polymers like hydroxyalkyl derivatives of cellulose are preferably those exhibiting good chemical stability and desired membrane characteristics. Normally, water-compatible polymers used in the coating solutions must be rendered water-insoluble after coating. By adapting crosslinking conditions on separation problems, the membranes are useful for many processes in the fields of biotechnology, food and chemical industry.The membranes presented here possess the advantage of being highly resistant to chemical and biological degradation and, hence, have long lifetimes under many process conditions.
    Notes: Es wird die Entwicklung hydrophiler Polymermembranen diskutiert, die nach Beschichtung mit Celluloseethern und anschließender Vernetzung auf den asymmetrischen Trägermembranen interessante Permeations- und Trenneigenschaften bei hervorragenden chemischen Stabilitäten, vor allem beim Membrantrennverfahren der Nanofiltration, aufzeigen. Weiterhin werden Aussagen zu den Gastrenneigenschaften der Celluloseetherkompositmembranen getroffen.Erläutert werden die Permeations- und Trenndaten der Kompositmembranen in Korrelation zur Vernetzung der Celluloseether anhand verschiedener Einflußgrößen, was qualitative und gegebenenfalls quantitative Aussagen zum Vernetzungsmechanismus der Celluloseetherderivate erlaubt. Dabei stehen die Vernetzungstemperatur, der Einfluß der katalysierenden Wasserstoffionen und bedingt die Vernetzungszeit im Vordergrund. Abgerundet werden die Arbeiten durch Ermittlungen rheologischer Daten, die in Zusammenhang zu den Vernetzungsreaktionen und damit zu membranspezifischen Größen stehen.Infolge der hervorragenden chemischen Stabilität der Celluloseether werden Einsatzmöglichkeiten der Kompositmembranen zur Nanofiltration niedermolekularer Verbindungen aus organisch hochbelasteten Systemen beschrieben.
    Additional Material: 30 Ill.
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  • 63
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    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 251 (1997), S. 13-21 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Polysulfide wurden mit hoher Ausbeute durch Hochtemperatur-Lösungspolykondensation von 4,4′-Dimercaptobiphenyl mit ausgewählten aliphatischen und aromatisch-aliphatischen Dihalogenkohlenwasserstoffen hergestellt. Um die optimalen Polykondensationsbedingungen zu bestimmen, wurde der Einfluß folgender Faktoren auf die reduzierte Viskosität und die Ausbeute der Polysulfide ermittelt: Art des organischen Lösungsmittels, Art des Halogenwasserstoff-Akzeptors, Konzentration der organischen Reagenzien, Reaktionstemperatur und -zeit. Die Polykondensation des Dithiols mit Bis(4-chlormethylphenyl)methan wurde als Modellsystem eingehender untersucht. Die Polysulfidstrukturen wurden mittels Elementaranalyse, IR-Spektroskopie und Röntgenstrukturanalyse bestätigt. Aus der thermogravimetrischen Analyse wurden die Zersetzungstemperatur, der Gewichtsverlust bei dieser Temperatur und das Maximum der Zersetzungsgeschwindigkeit erhalten. Weiterhin wurden einige physikalisch-chemische, mechanische und dielektrische Eigenschaften ermittelt. Die beste thermische und chemische Bestandigkeit zeigt das aus dem Dithiol und 4,4′-Bis(chlormethyl)biphenyl hergestellte Polysulfid, was auf dessen vorwiegend aromatische Struktur zuriickgefuhrt werden kann.
    Notes: Polysulfides were synthesized with high yield by high-temperature solution polycondensation of 4,4′-biphenyldithiol with selected aliphatic and aromatic-aliphatic hydrocarbon dihalides. To determine the optimum polycondensation conditions, the influence of the following factors on reduced viscosity and yield was studied: type of organic solvent, type of hydrogen halide acceptor, concentration of reagents, reaction temperature, and reaction time. A thorough examination was carried out only for the polycondensation of dithiol with bis(4-chloromethylphenyl)methane chosen as model system. The structures of the polysulfides were confirmed by elemental analysis, X-ray analysis, and infrared spectroscopy. The temperature of initial decomposition, the percentage of mass loss, and the temperature of the fastest decomposition, process were determined from curves of differential thermal and thermogravimetric analysis. Some physicochemical, mechanical and electrical properties were determined. The highest thermal and chemical resistance has been found for the polysulfide obtained from 4,4′-biphenyldithiol and 4,4′-bis(chloromethyl)biphenyl, probably because of the predominantly aromatic structure.
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  • 64
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 251 (1997), S. 61-72 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Drie organisch-anorganische Hybridmaterialien wurden nach dem Sol-Gel-Verfahren durch kovalenten Einbau von Poly(styrol-co-methylmethacrylat)(Poly(St-co-MMA))-, Polymethylmethacrylat(PMMA)- und Polystyrol(PS)-Struktureinheiten in ein SiO2-Netzwerk hergestellt und als Füllstoffe (bis zu 60 Gew.-%) in Dentalharzen verwendet. Der Einfluß der Füllstoffe auf einige mechanische Eigenschaften der Harze wurde untersucht. Die Härte der gefüllten Dentalharze nahm mit steigendem Füllstoffgehalt zu, wogegen die Biegefestigkeit abnahm. Die Druckfestigkeit der gefüllten Harze war besser als die des ungefüllten Harzes, nahm jedoch mit steigendem Füllstoffgehalt ab.
    Notes: By incorporating poly(methyl methacrylate) (PMMA), polystyrene (PS), and poly(styrene-co-methyl methacrylate) (poly(St-co-MMA)) structure units covalently into the SiO2 glass network via a sol-gel approach, three organic-inorganic hybrid materials (PMMA-SiO2, PS - SiO2, and poly(St-co-MMA) - SiO2) have been prepared. The three hybrid sol-gel materials were used as filler (up to 60 wt.-%) for dental composite resins. The effect of the three filler materials on several mechanical properties of the dental composite resins was investigated. The hardness of the filled dental composites increased with increasing filler content, whereas the bending strength decreased. The compressive strength of the composites was improved, compared with the unfilled resin, but decreased with inreasing filler content.
    Additional Material: 6 Ill.
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  • 65
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 251 (1997), S. 107-116 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Adsorption von Benzol, Toluol und p-Xylol (BTX) aus wäßrigen Lösungen mittels hochvernetzter kationischer Stärke mit tertiären Amingruppen wurde untersucht. Der endotherme Adsorptionsvorgang ist vom Anfangs-pH-Wert und der Anfangskonzentration abhängig und kann mit einer Langmuir-Isotherme beschrieben werden.Die Adsorptionswärme (Δ) bei pH 4 beträgt für Benzol, Toluol und Xylol 29,45 kJ mol-1, 34,41 kJ mol-1 bzw. 35,58 kJ mol-1, bei pH 10 30,17 kJ mol-1, 35.56 kJ mol-1 bzw. 39,39 kJ mol-1. Die adsorbierte Menge nimmt in der Reihenfolge Benzol 〉 Toluol 〉 Xylol ab.
    Notes: The removal of benzene, toluene and p-xylene (BTX) compounds from aqueous solutions with highly crosslinked cationic starch containing tertiary amine groups was investigated. The adsorption process has found to be initial pH- and initial concentration-dependent, endothermic, and follows the Langmuir isothermal adsorption.The heats of adsorption (ΔH) at initial pH = 4 of benzene, toluene and p-xylene compounds are 29.45 kJ mol-1, 34.41 kJ mol-1, and 35.58 kJ mol-1, respectively, those at initial pH = 10 are 30.17 kJ mol-1, 35.56 kJ mol-1, and 39.39 kJ mol-1, respectively. The order of the amount of adsorbed BTX compounds on the adsorbent is benzene 〉 toluene 〉 p-xylene.
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  • 66
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    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 251 (1997), S. 157-170 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Bi-Sr-Ca-Cu-Komplexverbindungen von Polymethacrylsäure (PMAA) und Kresolnovolaken, die als Precursoren für Hochtemperatursupraleiter (HTSL) eingesetzt werden, sowie deren Cu-Komplexsalze wurden ESR-spektroskopisch und thermogravimetrisch untersucht. In den PMAA-Proben wurden drei verschiedene Cu2+-Spezies nachgewiesen: i) Cu2+-Paare, ii) isolierte Cu2+-Ionen und iii) Cu2+-Cluster. Bei niedrigem Cu-Gehalt der Proben bilden die Cu2+-Paar-Bindungen den Hauptanteil, bei hohem Cu-Gehalt überwiegen die Clusterbindungen. In den Novolakproben wurden nur isolierte Cu2+-Ionen und Cu2+-Cluster nachgewiesen. Die Einführung der Cu-Ionen erniedrigt die thermische Stabilität der Polymeren, der thermische Abbau erfolgt stufenweise. In den PMAA-Proben wird die erste Abbaustufe bei ≈ 220°C durch die Cu2+-Paar-Komplexe verursacht.
    Notes: Bi-Sr-Ca-Cu complexes of poly(methacrylic acid) (PMAA) and cresol novolac, which are precursors for high-temperature superconductors (HTSC) and Cu complexes of those polymers were investigated by ESR spectroscopy and thermogravimetry. In the PMAA samples three different kinds of Cu2+ species were detected: i) Cu2+ pairs, ii) isolated Cu2+ ions and iii) Cu2+ clusters. While Cu2+ pairs are the main species at low Cu concentrations, clusters become dominant at high Cu contents. In the novolac samples Cu2+ was only detected in isolated sites and clusters. The introduction of Cu ions lowered the thermal stability of the polymers and led to a stepwise decomposition. In the PMAA samples the first decomposition step at ≈ 220°C is caused by the Cu2+ pair complexes.
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  • 67
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    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 251 (1997), S. 193-205 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Neodymchlorid-2-ethylhexanolate mit der allgemeinen Formel NdCl3 · nL wurden durch eine Liganden-Austauschreaktion zwischen Neodymchloridisopropanolat (I) und 2-Ethylhexanol (EH) hergestellt. Die Hexanolate NdCl3 · 1,5 EH (II) und NdCl3 · 2,5 EH (III) wurden durch Elementaranalyse und Gravimetrie charakterisiert. Die katalytische Aktivität der Hexanolate bei der Homopolymerisation von 1,3-Butadien in Gegenwart von Triethylaluminium wurde untersucht. Die Verbindung III zeigte eine höhere Aktivität als die Verbindung II. Höhere Katalysator- und Cokatalysatorkonzentrationen sowie eine höhere Temperatur steigerten den Umsatz, wogegen die Viskosität der Produkte abnahm. Mit zunehmender Reaktionszeit erhöhten sich sowohl der Umsatz als auch die Viskosität. Die cis-1,4-Konformation wurde durch die Variation von Temperatur und Cokatalysatorkonzentration beeinflußt. Der gesamte Anteil der cis-1,4-Stuktur lag jedoch in allen Fällen über 99%, während die Produkte nur einen sehr geringen Vinyl-Anteil von 〈1% enthielten. Die Zugabe einer elektronenspendenden Verbindung verringerte den cis- 1,4-Gehalt aber auf 87%.
    Notes: Neodymium chloride 2-ethylhexanolates of the general formula NdCl3 · nL were prepared by ligand exchange reaction between neodymium chloride ispropanolate (I) and 2-ethylhexanol (EH). These hexanolates, NdCl3 · 1.5 EH (II) and NdCl3 · 2.5 EH (III), were characterized by elemental analysis and gravimetry. The catalytic activity of these hexanolates in combination with triethyl aluminium in the homopolymerization of 1,3-butadiene was studied, and the activity was found to be higher with III than II. The conversions increased with increasing the catalyst and co-catalyst concentrations and the temperature, whereas the intrinsic viscosity decreased. The conversions and the intrinsic viscosity decreased. The conversions and the intrinsic viscosity increased with reaction time. The cis-1,4 structure was influenced by variation in temperature and co-catalyst concentration, however, the total cis-1,4 structure was always more than 99% with very low vinyl content (〉1%). Addition of an external electron donor decreased the cis-1,4 content to 87%.
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  • 68
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: MgCl2-Träger für einen Ethylenpolymerisationskatalysator wurden mit Hilfe der Rekristallationsmethode hergestellt, wobei Methanol als Lösungsmittel diente. Der Einfluß verschiedener Lösungsmethoden des rekristallisierten MgCl2-Alkohol-Adduktes auf die morphologischen Charakteristika der Katalysatoren wurde untersucht. Die Lösungsmethode beeinflußt die Eigenschaften der Katalysatoren beträchtlich. Die dargestellten Katalysatoren wiesen unterschiedliche Ti/Mg-Verhältnisse auf, sowohl was die Oberfläche als auch die gesamten Katalysator-Partikel betrifft. Betrachtet man die Ti-Verteilung und Aktivitätsprofile, dann erweisen sich nicht nur die Polymerisationsbedingungen, sondern auch die Ti-Verteilung auf dem Katalysator als wichtige Faktoren, welche die Dichte der Polymeren beeinflussen.
    Notes: The MgCl2 supports for an ethylene polymerization catalyst were prepared by the recrystallization method using methanol as a solvent. The effects of different desolvation methods of the recrystallized MgCl2-alcohol adduct on the morphological characteristics of the catalysts were examined. The desolvation method greatly affects the characteristics of the catalyst. The prepared catalysts had different Ti/Mg ratios with respect to both surface content and entire catalyst particles. Considering Ti distribution and activity profiles, not only the polymerization conditions but also the Ti distribution on the catalyst appear to be an important factor which affects the bulk density of the polymers.
    Additional Material: 3 Ill.
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  • 69
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    Angewandte Makromolekulare Chemie 253 (1997), S. 89-97 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Aromatische Poly(etherketon)e mit Ferrocen-Einheiten in der Hauptkette wurden durch direkte Polykondensation von 1,1′-Ferrocendicarbonsäure mit Diphenylether oder 1,4-Diphenoxybenzol hergestellt. Als Katalysatoren wurden Trifluormethansulfonsäure, Methansulfonsäure/P2O5 (Eatons Reagens) oder Trifluormethansulfonsäure/P2O5 verwendet. Polykondensationen bei Raumtemperatur für 24 h ergaben Poly(arylenetherketon)e mit Grenzviskositäten bis zu 40 mL g-1. Die Monoacylierung von Diphenylether mit Ferrocencarbonsäure wurde im Hinblick auf die Effektivität von Eatons Reagens als Katalysator und Lösungsmittel eingehender untersucht.
    Notes: Aromatic poly(ether ketone)s with ferrocene units in the main chain were prepared by direct polycondensation of 1,1′-ferrocenedicarboxylic acid with diphenyl ether or 1,4-diphenoxybenzene using various catalysts such as trifluoromethanesulfonic acid (triflic acid), a combination of methanesulfonic acid/P2O5 (Eaton's reagent) or a combination of triflic acid/P2O5. Polycondensations at room temperature for 24 h gave poly(arylene ether ketone)s with inherent viscosities up to 40 mL g-1. Monoacylation of diphenyl ether with ferrocenecarboxylic acid was studied in detail in order to show the efficiency of polymer formation employing Eaton's reagent as catalyst and solvent.
    Additional Material: 6 Ill.
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  • 70
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    Angewandte Makromolekulare Chemie 251 (1997), S. 73-80 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die mechanischen und strukturellen Eigenschaften von Blends aus Phenolphthalein-Polyethersulfon und ultrahochmolekularem Polyethylen (UHMWPE) wurden anhand von Zug- und Biegeversuchen, Raster- und Transmissionselektronenmikroskopie untersucht. Die Zugabe einer geringen Menge UHMWPE (2 Gew.-%) führt zu einer Verstärkung der PES-C-Matrix. Höhere UHMWPE-Konzentrationen verschlechtern die mechanischen Eigenschaften. Die Strukturuntersuchungen zeigen, daß die Blends im gesamten Zusammensetzungsbereich mehrphasig sind. Bei geringen UHMWPE-Konzentrationen ist die UHMWPE-Phase gleichmäßig verteilt und entlang der Fließrichtung orientiert, was mit der starken Grenzflächenadhäsion zur Verbesserung des mechanischen Verhaltens beiträgt. Mit steigender UHMWPE-Konzentration nimmt die Domänengröß der UHMWPE-Phase zu.
    Notes: Mechanical and structural properties of blends of phenolphthalein poly(ether sulfone) (PES-C) with ultra-high molecular weight polyethylene (UHMWPE) were investigated using tensile and bending testing, scanning electron microscopy and transition electron microscopy. The incorporation of minor amounts of UHMWPE (2 wt.-%) into PES-C has a reinforcement effect. With higher concentrations of UHMWPE, the mechanical properties decrease gradually. Structural studies demonstrated that the blends are multiphasic in the whole composition range. The minor UHMWPE, dispersed uniformly and oriented along the flow direction, as well as the strong interfacial adhesion contribute to the increase of the mechanical performance of the blends. The domain size of the UHMWPE phase was found to increase with the increase of its concentration.
    Additional Material: 6 Ill.
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  • 71
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    Angewandte Makromolekulare Chemie 251 (1997), S. 117-130 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Ein Redoxcopolymeres, ein makroporöses Poly(Styrol-co-Divinylbenzol) (S/DVB)-Harz mit N-Bromsulfonamidgruppen, wurde angewandt, um Cyanide aus wäßrigen Lösungen zu entfernen. Dieses Harz enthält aktives Brom in den funktionellen Gruppen (1.86 mmol g-1, 3.72 meq g-1) und weist Oxidationseigenschaften auf. Es wurde sowohl in statischen als auch in dynamischen Systemen für die Oxidation von Cyanidionen zu nichttoxischen Verbindungen angewandt. Die Reaktionen wurden in wäßrigen Lösungen mit 26-2600 mg L-1 CN- bei unterschiedlichen pH-Werten durchgeführt. Die Ergebnisse zeigten, daß dieses Harz die Cyanide leicht zu Cyanaten oxidiert, die ca. 1000 mal weniger toxisch sind. Bei Kontakt mit dem Harz fiel die Cyanidkonzentration in den Lösungen unter 0.05 mg L-1 CN-. Die —SO2NBrNa-Gruppen gingen dabei in —SO2NH2-Gruppen über. Diese konnten wiederum mit Natriumhypochlorit- und Natriumbromid-Lösungen reaktiviert werden. Es wurde auch eine Alternative zu der Cyanidionenoxidation mit N-Bromsulfonamid-Harz untersucht, indem ein analoges N-Chlorsulfonamid-Harz in Gengenwart von katalytischen Mengen von Bromiden angewandt wurde.
    Notes: A redox copolymer, macroporous poly(styrene-co-divinylbenzene) (S/DVB) resin having N-bromosulfonamide groups, was used for removal of cyanide ions from aqueous solutions. This resin contains active bromine in functional groups (1.86 mmol g-1, i. e. 3.72 meq g-1) and shows oxidative properties. It was employed in static and flow system for oxidation of cyanide ions to non-toxic compounds. The reactions were carried out in aqueous media containing 26-2600 mg L-1 CN- at different pH values. The data showed that the resin having active bromine easily oxidized cyanides, forming cyanates being 1000-times less toxic than cyanides. In contact with the resin the concentration of cyanides in tested solutions dropped below 0.05 mg L-1 CN-. During the oxidation processes the —SO2NBrNa groups transform to —SO2NH2 groups. They can be reactivated by use of sodium hypochlorite and bromide solutions. As an alternative to oxidation of cyanides by N-bromosulfonamide resin, the oxidation of these ions by N-chlorosulfonamide resin with addition of a small amount of bromides was examined.
    Additional Material: 3 Ill.
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  • 72
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    Angewandte Makromolekulare Chemie 251 (1997), S. 207-208 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: No Abstract
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  • 73
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    Angewandte Makromolekulare Chemie 252 (1997), S. 33-43 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Novel Polyester glycols with alkyl side groups were used for the improvement of thermal stability and hydrolytic stability of polyester urethane elastomers. The novel polyester glycols used are poly( β -methyl- δ -valerolactone)glycol (PMVL), poly(3-methyl pentamethylene adipate) glycol (PMPA), poly(nonamethylene-co-2-methyl octamcthylene carbonate) gycol (PNCO). A mixture of PNCO and poly(dimethyl siloxane)gycol (PNCO/PDMS) was also used. Polyurethane network elastomers were prepared from 4,4′-diphenylmethane diisocyanate (or 2,4-tolylene diisocyanate), and a mixture of 1,4-butane diol and trimethylol propane by a prepolymer method. Mechanical properties, Tg, thermal stability, and hydrolytic stability were measured. Morphology were also measured by means of polarizing microscopy, dynamic viscoelastometer, and ESR. The properties of novel polyurethane elastomers have good mechanical properties comparable to those of the general purpose polyester urethanes, and better thermal and hydrolytic stability than PTMG-based polyurethane. These polyurethane elastomers were exposed in out door during 2 year in Nagasaki, JAPAN. The novel polyurethane clastomers held alomost constant values for gel fraction, swelling ratio, relative modulus during 12 months, while poly(oxytetramethylene oxide)-based polyurethane as a control decreased the these values. Relationship of degradation behaviors with chemical structure and morphology were discussed.
    Additional Material: 9 Ill.
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  • 74
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    Angewandte Makromolekulare Chemie 252 (1997), S. 139-151 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: In the chain oxidation of N-alkylamides with molecular oxygen, propagation is the ratedetermining step under conditions when the oxidation rate is independent of oxygen pressure. The oxidizability of lactams and lactam-based polyamides correlates with the energy of the formation of N-alkylamide radical by abstraction of hydrogen from the methylene group adjacent to nitrogen. While for lactams this energy depends on the number of carbons in the lactam ring, for N-alkylamides and polylactams such dependence is not observed.
    Additional Material: 1 Tab.
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  • 75
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    Angewandte Makromolekulare Chemie 252 (1997), S. 179-193 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: An X-band EPR-Imaging apparatus which allowed us to determine the distribution of nitroxyl radicals within solid samples of polymeric materials containing hindered amine stabilizers, is described. It is shown that EPR Imaging represents a powerful tool for investigating the growth and decay of nitroxyls formed in polymers irradiated under air for long periods. Since the variations of the radical concentration can be monitored both in time and in the space, this technique provides valuable information not easily attainable by means of other methods.
    Additional Material: 7 Ill.
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  • 76
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    Angewandte Makromolekulare Chemie 252 (1997), S. 237-256 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A re-examination of the photo-oxidation mechanism of poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) at both long and short irradiation wavelengths under accelerated conditions is reported. The formation rate of poly-2,6-dimethylphenoxy (PDMP) radicals, have been observed by esr spectroscopy, while benzylic-type radicals have been detected by spin trapping experiments using nitrosodurene under UV irradiation conditions. The changes of FTIR spectra obtained under accelerated photo-oxidative conditions show the formation of primary oxidation products such as aromatic aldehydes and quinones. The direct formation of radical cations and superoxide anions by a photo-induced electron-transfer reaction is suggested under our conditions. In addition, some results on the of photo-oxidation PPO/PS blends as a function of polystyrene tacticity are also reported. In the case of syndiotactic polystyrene the blend photostability shows some differences in comparison with the blend containing atactic polystyrene. This effect has been ascribed to the absence of excimers in syndiotactic polystyrene which are not revealed by fluorescence measurements. Finally, the chemical modification of PPO with bromine gave a bromomethylated PPO with different amounts of CH2 Br groups, which has been used for further substitution reactions with alkoxy sodium salts of 4-hydroxy-2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) and 4-hydroxy-1,2,2,6,6-pentamethylpiperidine (PMPP). The accelerated photo-oxidation of a modified copolymer PPO-PMPP containing a 60% PMPP moieties as side groups and its blends with pure PPO has been followed by FTIR and esr spectroscopies. Some comparisons with a commercially available hindered amine light stabilizers (HALS) and a modified copolymer PPO-PMPP are also reported under the same photo-oxidative conditions.
    Additional Material: 9 Ill.
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  • 77
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    Angewandte Makromolekulare Chemie 253 (1997), S. 27-49 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: For innovative applications of plastics, which take advantage of special properties of polymeric materials, comprehensive understanding on strengthening and toughening mechanisms is required. The temperature-dependent mechanical behaviour of PMMA, PS and PC under dynamic loading conditions were investigated by means of an instrumented Charpy impact tester. The elastic-plastic fracture mechanics parameters, the energy-determined J-integral, and the deformation-determined crack opening displacement, δ, enable to do structure-related quantification of micromechanical processes. The J-integral values showed a maximum, resulting from an energy-dissipative process. The maximum values for PMMA occurred at 50°C and for PC at 40°C , which is related to the secondary(β) relaxation as evaluated from the frequency dependence of the mechanical loss factor. The 0-relaxation initiated shear deformation mechanisms, which led to a local increase of toughness. In polycarbonate, toughness is strongly increased due to a stress-induced shear flow process at temperatures higher than -25°C. Correlations between morphology and toughness can be derived with the help of optical investigations of stable crack propagation on fracture surfaces.
    Notes: Innovative Kunststoffanwendungen, die die speziellen Eigenschaften polymerer Werkstoffe gezielt ausnutzen, erfordern vertiefte Kenntnisse über festigkeits- und zähigkeitsbestimmende Mechanismen. Das sich in Abhängigkeit von der Temperatur ändernde Werkstoffverhalten von PMMA, PS und PC wurde bei dynamischer Beanspruchung mittels instrumentierter Kerbschlagbiegeprüfung bestimmt. Mit der verformungsbestimmten Rißöffnungsverschiebung δ und dem energiebestimmten J-Integral stehen Kenngrößen der Fließbruchmechanik zur Verfügung, die eine strukturbezogene Quantifizierung der temperaturabhängigen mikromechanischen Prozesse erlauben. Die J-Integralwerte zeigen für PMMA bei 50°C und für PC bei -60°C ein durch einen energiedissipativen Prozeß verursachtes Maximum. Dieses Maximum steht, wie sich aus der Interpretation der Frequenzabhängigkeit des mechanischen Verlustfaktors ergibt, mit der Neben(β)-Relaxation in Beziehung. Dabei initiiert die β-Relaxation Scherdeformationsmechanismen, die ihrerseits die lokale Zähigkeitserhöhung bewirken. Ab -25°C führt für PC ein spannungsinduzierter Scherfließprozeß zu einer erheblichen Zähigkeitssteigerung. Durch die Einbeziehung lichtmikroskopischer Untersuchungen des stabilen Rißfortschritts auf der Bruchfläche können Morphologie-Zähigkeits-Korrelationen abgeleitet werden.
    Additional Material: 16 Ill.
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  • 78
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    Angewandte Makromolekulare Chemie 253 (1997), S. 71-88 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Eine Reihe von Polyamidimid-Polyimid-Blockcopolymeren (PAI-PI-BCPs) wurde durch Polykondensation von PAI-Blöcken mit Amino-Endgruppen und PI-Blöcken mit Anhydrid-Endgruppen hergestellt. Zur Synthese der Blöcke mit Molekulargewichten im Bereich von ca. 2000 bis 15000 wurden nur technisch leicht zugängliche Monomere, wie Trimellitsäureanhydridchlorid, Benzophenontetracarbonsäuredianhydrid, 4,4′-Diaminodiphenylmethan, 2,4-Toluylendiamin und 4,4′-Diaminodiphenylsulfon eingesetzt. Dabei zeigte sich, daß durch den blockartigen Aufbau die Löslichkeit-und damit die Verarbeitbarkeit-im Vergleich zu den reinen, unlöslichen Polyimiden wesentlich verbessert werden konnte, bei nahezu gleichbleibender Thermostabilität. So wurden BCPs mit guten mechanischen Eigenschaften, Thermostabilitäten bis ca. 480°C (Thermogravimetrie, 5% Gewichtsverlust) und guten Löslichkeiten in Dimethylacetamid und anderen polaren aprotischen Lösungsmitteln erhalten.
    Notes: New poly(amide-imide)-poly(imide) block copolymers (PAI-PI-BCPs) were prepared by polycondensation of amino-terminated PAI-blocks with anhydride-terminated PI-blocks. For the syntheses of the blocks with molecular weights from 2000 to 15000 only commercially available monomers were used, e.g. trimellitic acid anhydride chloride, benzophenone tetracarboxylic acid dianhydride, 4,4′-diaminodiphenylmethane, 2,4-toluenediamine and 4,4′-diaminodiphenylsulfone. The BCPs were shown to have better solubility compared to the pure, insoluble PIs with only minor decrease of the thermostability. Thus, BCPs with good mechanical properties, thermostabilities up to 480°C (thermogravimetric analysis, 5% weight loss) and good solubility in dimethylacetamide and other polar aprotic solvents were obtained.
    Additional Material: 4 Tab.
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  • 79
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Eine Reihe von Polysiloxan/Poly(N-acetyliminoethylen)-(PSiO/PNAI)-Block- und -Pfropfcopolymeren wurde durch Polymerisation von 2-Methyl-2-oxazolin (MeOZO) mit funktionellen Polysiloxan-Prepolymeren als Initiatoren synthetisiert. Die Copolymeren wurden mit IR- und 1H NMR-Spektroskopie sowie Elementaranalyse, Differentialkalorimetrie und Thermogravimetrie charakterisiert. Der Einbau sowohl von hydrophoben als auch von hydrophilen Sequenzen verleiht den Polymeren amphiphile Eigenschaften. Ihre Eigenschaften in Lösung und als Feststoffe lassen die Produkte für Anwendungen als nichtionische Emulgatoren, Oberflächenmodifikatoren, Gele, usw. geeignet erscheinen.
    Notes: A series of polysiloxane/poly(N-acetyliminoethylene) (PSiO/PNAI) block and graft copolymers were synthesized by the initiation of 2-methyl-2-oxazoline (Me-OZO) polymerization with functional polysiloxane prepolymers. The copolymerization products were characterized by IR- and 1H NMR spectroscopy, elemental analysis, DSC and thermogravimetry. The insertion of both hydrophobic and hydrophilic sequences in the macromolecular structure induces a behavior characteristic of amphiphilic compounds. Their solution and solid state behavior evidenced peculiarities which make them able to act as nonionic emulsifiers, surface modifiers, gels, etc.
    Additional Material: 4 Ill.
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  • 80
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Der Zustand von Wasser in Protonenaustausch-Membranen, hergestellt durch Pfropfen von Styrol auf Polyvinylidenfluorid-Filme (PVDF-g-PS) mittels Elektronenstrahlen und anschließendes Sulfonieren (PVDF-g-PSSA), wurde mittels Differentialkalorimetrie (DSC), Raman-Spektroskopie und Rontgen-Diffraktion (SAXS) ermittelt. Die Raman-Untersuchungen zeigten, daß einzelne Wassermolekule durch hydrophobe Wechselwirkungen an die Polymerketten gebunden sind. Die DSC-Untersuchungen zeigten, daß Wasser in den Membranen in drei verschiedenen Umgebungen vorliegt: nicht gefrierendes ionisch gebundenes Wasser, gefrierendes freies Wasser und gefrierendes gebundenes Wasser. Die Menge an nicht gefrierendem Wasser betragt unabhangig vom Pfropfungsgrad etwa 10 H2O/SO3H (mol/mol). Die Menge an gefrierendem Wasser ist stark vom Pfropfungsgrad abhangig. Oberhalb eines Pfropfungsgrades von 50% werden Werte von 40 H20/S03H (mol/mol) erreicht. Die Leitfahigkeit von nur nicht gefrierendes Wasser enthaltenden Membranen ist gering, d. h., das ionisch gebundene Wasser kann nicht allein die fur den Transport von Protonen und Wasser notwendigen Kanale bilden. Die SAXS Untersuchungen zeigten, daß Wasser/Sulfonsaure-Cluster in Membranen aus hydratisiertem PVDF-g-PSSA mit einem Bragg-Abstand von 25 Å gebildet werden. Diese Cluster formen die Kanale fur den Ionentransport und die Leitfähigkeit.
    Notes: The state of water in proton exchange membranes prepared by pre-irradiation (electron beam, 100 kGy) grafting of styrene onto poly(vinylidene fluoride) films (PVDF-g-PS), followed by sulfonation (PVDF-g-PSSA), has been studied with thermal analysis, Raman spectroscopy and small angle X-ray diffraction (SAXS). Raman spectra show that, in addition to free liquid water in the membranes, single water molecules are weakly bound to the polymer backbone. Thermal analysis shows that there are three types of water molecules in the membrane; non-freezable water associated with the ionic sites, freezable free water, and freezable bound water. The amount of non-freezable water is around 10 H2O/SO3H (mol/mol), and is independent of the degree of grafting (d.o.g.). The amount of freezable water is strongly dependent on the d.o.g. as long as the grafting has not penetrated the whole of the film, and reaches a value of around 40 H2O/SO3H (mol/mol) above a d.o.g. of 50%. The conductivity of membranes containing only the non-freezable water is low, i. e. the ionically bound water alone does not form the domains necessary for proton and water transport. SAXS measurements show that water/sulfonic acid clusters in hydrated PVDF-g-PSSA membranes with a Bragg distance of 25 Å are formed; these form the ion conducting channels in the membrane.
    Additional Material: 9 Ill.
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  • 81
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    Angewandte Makromolekulare Chemie 253 (1997), S. 211-211 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 82
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    Angewandte Makromolekulare Chemie 253 (1997), S. 201-210 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Zug- und Biegemoduli von preßgeformten Polypropen-Probekörpern mit unterschiedlichen Oberflächenkristallinitäten wurden basierend auf der Annahme eines Schicht-Verbund-Modells untersucht. Es zeigte sich, daß die Spannungs-Dehnungs-Kurven der Zugversuche und die Werte der Biegeablenkung im wesentlichen von der Oberfächenkristallinität abhängen, jedoch erwiesen sich die Bruchspannungen als von der Oberflächenkristallinität unabhängig. Es wird angenommen, daß das beobachtete Zug- und Biegeverhalten der Proben auf der Grundlage eines Schicht-Verbund-Modells, bei dem eine massive, starre Platte zwischen zwei weichen Schichten eingebettet ist, charakterisiert werden kann.
    Notes: The tensile and flexural moduli of the compression-molded sheets of polypropene with different surface layer crystallinity were investigated based on a layered composite model. It was found that the tensile stress-strain curve and flexural deflection depended largely on the surface layer crystallinity, but the ultimate strain-at-break values were independent of the surface layer crystallinity. It is suggested that the tensile and flexural behavior can be characterized using a layered composite model in which a bulk plate was sandwiched between two surface layers.
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  • 83
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    Angewandte Makromolekulare Chemie 252 (1997), S. 45-54 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Addition of HALS-stabilisers, the cut-off wavelength of the light source, the temperature and the oxygen pressure have an influence on the UV-degradation mechanism of polyolefins. All these parameters influences the conversion of oxygen into polymeric carbonyls. The results are explained assuming that the initiation of the UV-degradation of pololefins is due to substrate-oxygen charge transfer complexes (CTCs).
    Additional Material: 10 Ill.
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  • 84
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    Angewandte Makromolekulare Chemie 252 (1997), S. 69-88 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The applicability of fracture mechanics was studied on UV-exposed HDPE Charpy specimens. The failure distribution of the stress at failure measured in three-points bending tests showed a bifurcation in failure processes. At high stresses yielding occurs, resulting in large strain at failures. At lower stresses crack propagation causes low strain at failures. Due to the bifurcation in failure processes the ductile-brittle transition temperature of exposed specimens is hard to determine.Specimens notched after exposure showed a decrease in the critical stress intensity values. The effective notch depth of exposed specimens was found to be larger than the thickness of the oxidized layer measured by FT-IR and density measurements.
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  • 85
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    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 252 (1997), S. 119-138 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: In the 2-hydroxyphenyl-1,3,5-triazines, the intramolecular hydrogen bond is stronger than in the corresponding 2-hydroxyphenylbenzotriazoles. Compounds with only one aryl group in the 2-hydroxyphenyl-1,3,5-triazine series show proton-transferred fluorescence with large Stokes shift and high quantum yield. No such fluorescence is observed, in contrast, for compunds with three aryi groups bearing no electrondonating groups on the aryl moieties. When the hydrogen atom of the intramolecular hydrogen bond is replaced by CH3, the respective derivative shows fluorescence with a normal Stokes shift.Various copolymers of MA-TIN 1 (2-[2-hydroxy-3-tert.-butyl-5-(O-[2-hydroxy-3-(2-methylpropenoyloxy)propyl]-2-carbonyloxyethyl)phenyl]benzotriazole), and MA-TZ 1 (2,4-Bis(2,4-dimethyl-phenyl)-6-[2-hydroxy-4-(2-hydroxy-3-[2-methylpropenoyloxy])propoxyphenyl]-1,3,5-triazine) with styrene, methyl methacrylate, and methacrylic acid have been synthesized by radical polymerization. The absorption spectra in the longwavelength UV region appear unchanged compared to those of the monomeric UV absorbers indicating that the stabilizer chromophores are conserved intact in the polymer. Both the monomeric and the polymeric stabilizers exhibit a strongly Stokesshifted, temperature-dependent, low-quantum-yield, proton-transferred fluorescence. This may be taken as evidence that the intramolecular hydrogen bond, which is essential for the photostability of this type of UV absorber, remains intact also in the copolymers. Activation energies of the radiationless deactivation process can be evaluated from the temperature dependence of this fluorescence. These energies lie between 4 and 5 kJ/mol for most of the benzotriazole and triazine stabilizers investigated.Fluorescence-decay measurements with crystalline MA-TIN 1 at different temperatures reveal a close correspondence of the temperature dependence between decay times and relative quantum yields. The radiationless process is thence concluded to originate from the proton-transferred level S1'. The decay time at room temperature is estimated at 70 ps, close to the value for crystalline TIN P (2-(2-hydroxy-5-methylphenyl)benzotriazole). The proton-transferred fluorescence of MA-TIN 1 exhibits a biexponential decay profile whereas solid TIN P, in contrast, displays only one single lifetime.
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  • 86
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    New York : Wiley-Blackwell
    Biopolymers 41 (1997), S. 5-25 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Buckling transitions in superhelical DNA are sudden changes in shape that accompany a smooth variation in a key parameter, such as superhelical density. Here we explore the dependence of these transitions on the elastic constants for bending and twisting, A and C, important characteristics to DNA's bending and twisting persistence lengths. The large range we explore extends to other elastic materials with self-contact interactions, modeled here by a Debye-Hückel electrostatic potential.Our collective description of DNA shapes and energies over a wide range of ρ = A/C reveals a dramatic dependence of DNA shape and associated configurational transitions on ρ: transitions are sharp for large ρ but masked for small ρ. In particular, at small ρ, a nonplanar circular family emerges, in agreement with Jülicher's recent analytical predictions; a continuum of forms (and associated writhing numbers) is also observed.The relevance of these buckling transitions to DNA in solution is examined through studies of size dependence and thermal effects. Buckling transitions smooth considerably as size increases, and this can be explained in part by the lower curvature in larger plasmids. This trend suggests that buckling transitions should not be detectable for isolated (i.e., unbound) DNA plasmids of biological interest, except possibly for very large ρ. Buckling phenomena would nonetheless be relevant for small DNA loops, particularly for higher values of ρ, and might have a role in regulatory mechanisms: a small change in superhelical stress could lead to a large configurational change.Writhe distributions as a function of ρ, generated by Langevin dynamics simulations, reveal the importance of thermal fluctuations. Each distribution range (and multipeaked shape) can be interpreted by our buckling profiles. Significantly, the distributions for moderate to high superhelical densities are most sensitive to ρ, isolating different distribution patterns. If this effect could be captured experimentally for small plasmids by currently available imaging techniques, such results suggest a slightly different experimental procedure for estimating the torsional stiffness of supercoiled DNA than considered to date. © 1997 John Wiley & Sons, Inc.
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  • 87
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Molecular mechanics and dynamics calculations were carried out on the disaccharides α-L-Rhap-(1 → 2)-α-L-Rhap-(1 → OMe) (1) and α-L-Rhap-(1 → 3)-α-L-Rhap-(1 OMe) (2), and the trisaccharide α-L-Rhap-(1 → 2)-α-L-Rhap-(1 → 3)-α-L-Rhap-(1 → OMe) (3). The semiflexible conformational behavior of these molecules was characterized by the occupation of a combination of different glycosidic linkage and side-chain conformational positions whose relative occupations were sensitive to dielectric screening. Molecular dynamics simulations of the trisaccharide 3 showed little difference between the linkage conformations in the trisaccharide and the component disaccharides 1 and 2.Experimental optical rotation data of 1 and 2 were obtained as a function of temperature in varying solvents. The molecular models were combined with the semiempirical theory of Stevens and Sathyanarayana to yield calculated optical rotations. Interpretation of the data of both 1 and 2 implied that a combination of conformations, both in glycosidic and side-chain positions, could explain the experimental data. Solvents effects were important in influencing the conformational mix and averaged optical rotation.Three-bond heteronuclear coupling constants 3JC, H were obtained for the glycosidic linkages of 1 and 2 in D2O and DMSO. Analysis of the coupling constants with a Karplus curve showed that small reductions in the glycosidic torsion angles of the conformations of the models used here of ca. 10°-15° in φ and 5°-10° in ψ were required to give better agreement with experiment; a combination of conformations for both 1 and 2 was consistent with the data. There was a negligible influence on the coupling constants of 1 on changing the solvent from D2O to DMSO. © 1997 John Wiley & Sons, Inc.
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  • 88
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    New York : Wiley-Blackwell
    Biopolymers 41 (1997), S. 165-180 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: For a minimalist model of protein folding, which we introduced recently, we investigate various methods to obtain folding sequences. A detailed study of random sequences shows that, for this model, such sequences usually do not fold to their ground states during simulations. Straightforward techniques for the construction of folding sequences, based solely on the target structure, fail. We describe in detail an optimization algorithm, based on genetic algorithms, for the “simulated breeding” of folding sequences in this model. We find that, for any target structure studied, there is not only a single folding sequence but a patch of sequences in sequence space that fold to this structure. In addition, we show that, much as in real proteins, nonhomologous sequences may fold to the same target structure. © 1997 John Wiley & Sons, Inc.
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  • 89
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    New York : Wiley-Blackwell
    Biopolymers 41 (1997), S. 205-212 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The self-association of several N-urethanyl-L-amino acids (N-t-Boc-glycine, N-t-Boc-L-alanine, N-t-Boc-L-methionine, and N-t-Boc-O-Bz-L-tyrosine has been investigated in carbon tetrachloride by Fourier transform (FTIR) spectrometry. The fractions of nonbonded OH and NH groups have been determined from the intensities of the free OH and NH-stretching vibrations. The FTIR spectra have been examined in the carbonyl stretching regions by using Fourier self-deconvolution techniques. The results show that intermolecular hydrogen bonds are formed between the carboxylic acid group of one molecule and the urethane group of another molecule, suggesting that the leading factor for the self-association of N-t-Boc amino acids is the acidity of the OH groups. In N-t-Boc glycine, more heterodimers are formed than in the other amino acids. In N-t-Boc-O-Bz-L-tyrosine where the steric hindrance of the substituent implanted on the Cα atom is higher, the concentration of homodimers and heterodimers is lower than in N-t-Boc-L-alanine or N-t-Boc-L methionine. © 1997 John Wiley & Sons, Inc.
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  • 90
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    New York : Wiley-Blackwell
    Biopolymers 41 (1997), S. 239-250 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A heteropolymer model of randomly self-interacting chains in two dimensions is studied with numerical simulations in order to elucidate the folding mechanism of protein. We find that the model occasionally shows folding propensity depending on the sequence of random numbers given to the chain. We study the thermodynamic and kinematic roles in the folding mechanism by grouping the local energy minima found in the simulations into clusters according to the similarity of their conformations. It is suggested that the local minima to which some heteropolymers show a folding tendency are always the lowest energy states of the energy spectrum within a cluster, though which cluster is selected depends on the sequence. For the eight random sequences we study, we find that the energy gap between the ground state and excited states is little correlated with folding or nonfolding. We rather find that folding propensities are correlated with the global structure of the average energy surface, implying a dominant kinetic role in the folding mechanism, although thermal factors cannot be ignored as the mechanism of choosing the ground state within a cluster of states connected by small deformations. We suggest that a hierarchical cluster structure plays an important role in selecting a unique folded state out of the huge number of local minima of heteropolymers. © 1997 John Wiley & Sons, Inc.
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  • 91
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The nucleocapsid protein NCp7, which is the major genomic RNA binding protein of human immunodeficiency virus type 1, plays an important role in several key steps of the viral life cycle. Many of the NCp7 activities, notably the nucleic acid annealing and the genomic RNA wrapping ones, are thought to be linked to a nonspecific binding of NCp7 to its nucleic acid targets. The mechanism of these activities is still debated but several clues are in favor of an intermediate aggregation of nucleic acids by NCp7. To check and characterize the nucleic acid aggregating properties of NCp7, we investigated the interaction of NCp7 with the model RNA homopolymer, polyA, by quasielastic light scattering and optical density measurements. The ordered growth of monodisperse large particles independently of the nucleic acid size and the almost complete covering of polyA by NCp7 strongly suggested an ordered aggregation mechanism. The aggregate kinetics of growth in the optimum protein concentration range (≥2 μM) were governed by a so-called Ostwald ripening mechanism limited by transfer of NCp7-covered polyA complexes from small to large aggregates. The aggregation process was strongly dependent on both Na+ and Mg2+ concentrations, the optimum concentrations being in the physiological range. Similar conclusions held true when polyA was replaced by 16S + 23S ribosomal RNA, suggesting that the NCp7 aggregating properties were only poorly dependent on the nucleic acid sequence and structure. Finally, as in the NCp7 annealing activities, the basic regions of NCp7, but not the zinc fingers, were found critical in nucleic acid aggregation. Taken together, our data indicate that NCp7 is a highly efficient nucleic acid aggregating agent and strengthen the hypothesis that aggregation may constitute a transient step in various NCp7 functions. © 1997 John Wiley & Sons, Inc.
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  • 92
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The nmr solution conformation of cyclotheonamide A (CtA) was determined in aqueous media. The data produced 15 distance and 10 torsional constraints which were used to generate conformations using restrained simulated annealing (SA) and distance geometry/simulated annealing (DG/SA) calculations. Two different calculation protocols were performed to ensure proper sampling of conformational space and even though the torsional restraints were input differently, both calculation methods yielded the same conformation of CtA. In the structure calculations, all solutions of the Karplus equation were sampled simultaneously using the restrained SA protocol and large ranges were used for the dihedral restraints in the DG/SA protocol because all solutions to the Karplus equation could not be sampled simultaneously. The solution conformation was also compared to the solid state x-ray conformations of CtA bound to thrombin and trypsin. The conformation of the residues important for active site binding (d-Phe, h-Arg, and Pro) are nearly identical in aqueous solution and solid state with largest differences at the a-Ala and v-Tyr residues. CtA appears to be preordered in structure and does not undergo a significant conformational change upon binding to the enzyme active site. © 1997 John Wiley & Sons, Inc.
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  • 93
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    New York : Wiley-Blackwell
    Biopolymers 41 (1997), S. 381-389 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A Monte Carlo Protein Building method to construct the backbone and Cβ atomic coordinates from known Cα coordinates is reported. The method selects values of dihedral angles from ranges established from a statistical analysis of the relationship between dihedral angles of the backbone and Cα coordinates for a protein data base. The averaged coordinates from ten backbone models of a protein were used to define a mean structure that was refined by energy minimization using the AMBER force field (GB/SA). By the latter method the average atomic deviation and rmsd of the backbone and Cβ atoms for 24 proteins is between 0.14 and 0.32 Å (average 0.22 Å) and 0.22 and 0.61 Å (average 0.43 Å), respectively. A comparison with other methods is made. © 1997 John Wiley & Sons, Inc.
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  • 94
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    New York : Wiley-Blackwell
    Biopolymers 41 (1997), S. 391-405 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A model of nine proteins including side-chain atoms have been built from the known Cα coordinates and amino acid sequences using a Monte Carlo Protein Building Annealing method. The Cartesian coordinates for the side-chain atoms were established with bond lengths and angles selected randomly from within previously determined ranges. A simulated annealing technique is used to generate some 300 structures with differing side-chain conformations. The atomic coordinates of the backbone atoms are fixed during the simulated annealing process. The coordinates of the side-chain atoms of 300 low energy conformations are averaged to obtain a mean structure that is minimized with the Cα atoms constrained to their position in the x-ray structure using the OPLS/AMBER force field with the GB/SA water model. The rms deviation of the main-chain atoms (without Cβ) compared with the corresponding crystal structures is in the range 0.20-0.64 Å. The rms deviation of the side-chain atoms is between 1.72 and 2.71 Å and for all atoms is between 1.19 and 1.99 Å. The method is insensitive to random errors in the Cα positions and the computational requirement is modest. © 1997 John Wiley & Sons, Inc.
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  • 95
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    New York : Wiley-Blackwell
    Biopolymers 41 (1997), S. 443-450 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We analyze the electrostatic and hydrodynamic properties of a nuclease from the pathogenic gram-negative bacterium Serratia marcescens using finite-difference Poisson-Boltzmann methods for electrostatic calculations and a bead-model approach for diffusion coefficient calculations.Electrostatic properties are analyzed for the enzyme in monomeric and dimeric forms and also in the context of DNA binding by the nuclease. Our preliminary results show that binding of a double-stranded DNA dodecamer by nuclease causes an overall shift in the charge of the protein by approximately three units of elementary charge per monomer, resulting in a positively charged protein at physiologic pH. In these calculations, the free enzyme was found to have a negative (-1 e) charge per monomer at pH 7. The most dramatic shift in pKa involves His 89 whose pKa increases by three pH units upon DNA binding. This shift leads to a protonated residue at pH 7, in contrast to the unprotonated form in the free enzyme. DNA binding also leads to a decrease in the energetic distances between the most stable protonation states of the enzyme. Dimerization has no significant effect on the electrostatic properties of each of the monomers for both free enzyme and that bound to DNA.Results of hydrodynamic calculations are consistent with the dimeric form of the enzyme in solution. The computed translational diffusion coefficient for the dimer model of the enzyme is in very good agreement with measurements from light scattering experiments. Preliminary electrooptical calculations indicate that the dimer should possess a large dipole moment (approximately 600 Debye units) as well as substantial optical anisotropy (limiting reduced linear electric dichroism of about 0.3). Therefore, this system may serve as a good model for investigation of electric and hydrodynamic properties by relaxation electrooptical experiments. © 1997 John Wiley & Sons, Inc.
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  • 96
    ISSN: 0006-3525
    Keywords: biovector ; light scattering ; lipid ; microgel ; polysaccharide ; soft sphere ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The structure of a new supramolecular drug carrier (named Biovectors - BV) was studied using light scattering and scanning electronic microscopy techniques. This system consists of a polysaccharide core of chemically cross-linked maltodextrins to which phospholipids (and, in some cases, cholesterol) are added. Both polysaccharide cores and BV cross-linked with phosphate (negatively charged) and epichlorhydrin (no net charge) are spherical particles. The increase in the ionic strength of the medium increases the density of the charged polysaccharide cores. The lipid strongly interacts with neutral and negatively charged cores, decreasing both intra- and interparticle interactions. The results (mainly, ρ = Rg/Rh 〈 0.775 in some cases) suggest that BV are gel-like particles of variable density, referred to as microgels or soft spheres. Neutral polysaccharides have a strong tendency to self-aggregate. This self-aggregation of polysaccharide neutral cores is prevented by the addition of lipid or dimethylsulfoxide. © 1997 John Wiley & Sons, Inc. Biopoly 41: 511-520, 1997
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  • 97
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    New York : Wiley-Blackwell
    Biopolymers 41 (1997), S. 533-544 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A dynamical model of interdomain “hinge bending” of T4 lysozyme in aqueous solution has been developed on the basis of molecular dynamics (MD) simulation. The MD model study provides a description of the conformational reorganization expected to occur for the protein in aqueous solution as compared to the crystalline environment. Three different 500 ps molecular dynamics simulations were calculated, each using a distinctly different crystal conformation of T4 lysozyme as the starting points of the MD simulations. Crystal structures of wild-type lysozyme and “open” and “closed” forms of M6I variant structures were analyzed in this study. Large-scale, molecular-conformational rearrangements were observed in all three simulations, and the largest structural change was found for the open form of the M6I allomorph. All three simulated proteins had closed relative to the wild-type crystal structure, and the closure of the “jaws” of the active site cleft occurred gradually over the time course of the trajectories. The time average MD structures, calculated over the final 50 ps of each trajectory, had all adapted to conformations more similar to each other than to their incipient crystal forms. Using a similar MD protocol on cytochrome P450BM-3 [M. D. Paulsen and R. L. Ornstein (1995) Proteins: Structure Function and Genetics, Vol. 27, pp. 237-243] we have found that the opposite type of motion relative to the starting crystal structure, that is, the open form of the crystal structure, had opened to a greater degree relative to the incipient crystal structure form. Therefore we do not believe that either result is merely a simulation artifact, but rather the protein dynamics are due to protein relaxation in the absence of crystal packing forces in the simulated solution environments. © 1997 John Wiley & Sons, Inc. Biopoly 41: 533-544, 1997
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  • 98
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Antibodies induced against intact foot-and-mouth disease Virus (FMDV) particles bind to the retro-inverso analogue of fragment 141-159 of the viral coat protein VP1 of FMDV, variant A, equally well as to the parent peptide. A conformational investigation of this retro-inverso peptide was carried out by nmr spectroscopy and restrained molecular modeling in order to identify the structural basis for the antigenic mimicry between these retro-inverso and parent peptides. In 100% trifluoroethanol a well-defined left-handed α-helical region exists from residue 150 to residue 159, which is consistently present in all conformational families obtained from restrained modelling. A less-defined left-handed helical region is present in the tract 144-148, which is also consistent for all structures. Conformational flexibility exists about Gly149, which leads to two types of structures, either bent or linear. In the bent structures, a three-residue inverse tight turn is found, which can be classified as an inverse γ-turn centered at Gly149. The overall structural features of the retro-inverso peptide are shown to be similar to those of the parent L-peptide. The two molecules, however, are roughly mirror images because they share inherently chiral secondary structure elements. By comparing these conformational conclusions with the x-ray structure of the Fab complex of a corresponding VP1 antigenic fragment, a rationale is proposed to account for the topological requirements of specific recognition that are implied by the equivalent antigenic activity of the natural and retro-inverso compounds. © 1997 John Wiley & Sons, Inc. Biopoly 41: 569-590, 1997.
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  • 99
    ISSN: 0006-3525
    Keywords: Leu-enkephalin ; [13C, 15N]-backbone-labeled ; reverse micelles ; conformation ; CD ; FTIR ; nmr ; distance geometry ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Enkephalin represents one of the bioactive peptide molecules most extensively investigated both in solution and in the crystal state. Depending upon the environment chosen for such studies, three main conformational states were identified for this flexible, linear pentapeptide - i.e., an extended conformation, a single-bend, and a double-bend structure. Since CD and Fourier transform ir (FTIR) spectra of Leu-enkephalin solubilized in negatively charged reverse micelles of bis (2-ethylhexyl)sulfosuccinate sodium salt/isooctane/water were supportive of a restricted conformational space of the aromatic side chains and of a bended type fold, we have analyzed by nmr the conformational preferences of Leu-enkephalin in reverse micelles using a synthetic [13C, 15N]-backbone-labeled sample. The overall conformation derived from nuclear Overhauser effect spectroscopy (NOESY) and 15N-filtered rotating frame NOESY (ROESY) spectra and by distance geometry calculations is a double-bend fold of the backbone that is comparable to one of the known x-ray structures. Thereby the tyrosine side chain is inserted into the hydrophobic core of the reverse micelles in a restrained conformational space as well evidenced by NOEs between the aromatic ring protons and the surfactant. The proximity of the aromatic rings of tyrosine and phenylalanine indicate a preferred structure consistent with the postulated conformation of the opioid peptide in the δ-receptor-bound state. These results confirm the interesting and promising properties of reverse micelles as membrane mimetica. © 1997 John Wiley & Sons, Inc. Biopoly 41: 591-606, 1997
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  • 100
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    New York : Wiley-Blackwell
    Biopolymers 41 (1997), S. 673-702 
    ISSN: 0006-3525
    Keywords: protein folding ; coupling effect ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A 1-4 and 2-3 residue-correlation model is proposed to predict the β-turns in proteins. The average rate of correct prediction for the 455 β-turn tetrapeptides and 4018 non-β-turn tetrapeptides in the training data base is 80.1%, and that for the 223 β-turn tetrapeptides and 12562 non-β-turn tetrapeptides in the testing data base is 80.9%. Compared with the rates of correct prediction based on the residue-independent model reported previously, the quality of prediction is significantly improved by the new model, implying that the correlation effect between the 1st and the 4th residues and that between the 2nd and 3rd residues along a tetrapeptide are important for forming a β-turn in a protein during the process of its folding. © 1997 John Wiley & Sons, Inc. Biopoly 41: 673-702, 1997
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