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  • Polymer and Materials Science  (112,478)
  • Chinese hamster
  • Obesity
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Der Anaesthesist 49 (2000), S. 317-320 
    ISSN: 1432-055X
    Keywords: Schlüsselwörter Anamnese ; Intubationsschwierigkeiten ; Adipositas ; Prämedikation ; Atemdepression ; Key words Preanaesthetic visit ; difficult airway ; Obesity ; Premedication ; Respiratory depression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract Based on a case report, we offer brief guidelines on the perioperative management of patients with Sleep-Apnea-Syndrome (SAS) who present with a high incidence of a difficult airway and a high risk of respiratory depression during the perioperative period. A 39 year old male patient with a body mass index of 34,22 kg/m2 and receiving continuous-positive-airway-pressure- (CPAP) therapy for known SAS was scheduled for elective plastic surgery. After induction of anaesthesia and direct laryngoscopy no adequate airway could be established and the patient became hypoxic, hypercapnic and developed hypotension and bradycardia. With the use of a laryngeal mask airway the patient was stabilized and did not show neurologic sequale after immediate awakening. The following fiberoptic intubation of the awake patient, still showing tendency of upper airway obstruction, confirmed the difficult anatomical structures. The subsequent general anesthesia was uneventful. The patient received CPAP therapy and was monitored during the first postoperative night in the Intensive Care Unit. He made an uneventful recovery. He was advised to have regional anaesthesia or planned fiberoptic intubation, where possible, in the case of further anesthetic intervention. SAS has major implications for the anaesthesiologist and whenever patients exhibiting the high risk factors (obesity, male sex, history of intense snoring, impaired daytime performance, nonrefreshing daytime naps) are presented for surgery this condition should be considered. Elective surgery should be postponed until after adequate examination and treatment when necessary. Patients with SAS should always be suspected of having cardiopulmonary dysfunctions such as hypertension, cardiac dysrhythmia or cor pulmonale. It is most important to avoid sedative premedication, to initiate CPAP therapy preoperatively, to encourage regional anaesthesia if possible and to ensure close monitoring over the complete perioperative period. Planned fiberoptic intubation, preferably with surgical personnel available for an emergency airway, is a safe method for the induction of anaesthesia. Postoperatively, patients are at high risk from respiratory depression, even in the awake state. Postoperative opioid analgesia, no matter what route, should only be given under close monitoring. Independently of regional or general anaesthesia there is an increased risk of respiratory depression in the middle of the first postoperative week, suspected to be caused by the catching up on lost REM-sleep, due to shifts in the normal sleep pattern during the first postoperative days.
    Notes: Zusammenfassung Ausgehend von einem Fallbeispiel stellen wir wesentliche Aspekte der perioperativen anästhesiologischen Betreuung von Schlaf-Apnoe-Patienten dar. Wir berichten über einen adipösen, 39-jährigen, männlichen Patienten [Body-Mass-Index (BMI)=34,22 kg/m2] mit bekanntem Schlaf-Apnoe-Syndrom (SAS), der sich in Intubationsnarkose einem plastisch-chirurgischen Eingriff unterziehen sollte. Nach Narkoseeinleitung erwies sich die Maskenbeatmung als erschwert und die konventionelle Intubation (Mallampati II/Cormack-Lehane IV) als unmöglich. Nach Platzierung einer Larynxmaske und mehrfachen Korrekturen der Position war eine adäquate Oxygenierung, bei allerdings weiterhin eingeschränkter Ventilation möglich. Es wurde nun der Entschluss gefasst, den Patienten erwachen zu lassen, und dann eine fiberoptische Wachintubation durchzuführen. Kurzfristig kam es im Rahmen der Narkoseeinleitung zur Hypoxie, Hyperkapnie, Bradykardie und Hypotonie. Unmittelbar nach dem Erwachen des Patienten, der adäquate neurologische Reaktionen zeigte, bestand weiterhin die Tendenz zur oberen Atemwegsobstruktion. Nach Schleimhautanästhesie und schwieriger fiberoptischer Wachintubation erfolgte eine problemlose Allgemeinanästhesie. Der postoperative Verlauf war bei anfänglicher Intensivüberwachung und Continuous-Positive-Airway-Pressure- (CPAP) Beatmung unauffällig. Der Patient wurde auf die erschwerte Intubation für etwaige weitere anästhesiologische Interventionen hingewiesen. Bei Schlaf-Apnoe-Patienten sollte aufgrund der möglichen Obstruktion der oberen Atemwege immer mit Intubationschwierigkeiten gerechnet und die fiberoptische Wachintubation in Erwägung gezogen werden.
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  • 2
    ISSN: 1248-9204
    Keywords: Incisional hernia ; Intraperitoneal ; Adhesion prevention ; Obesity ; Mesh
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A case report of a giant abdominal wall defect in a 62-year-old woman is reported. Diabetes and severe overweight (BMI: 52) were noted as associated risk factors. Previous surgical treatment had been performed in 1982 using a retromuscular polypropylene mesh. This treatment failed in 1998. Preoperative medical treatment was started 8 months before for skin infection. Progressive pneumoperitoneum was used to create a space to accommodate herniated viscera and facilitate fascial repair with minimal tension. To palliate the parietal defect, we used a new mesh placed intraperitoneally. This mesh was made up of a dual facing mesh combining a three-dimensional polyester covered on one of its sides with an adhesion-preventive, hydrophilic and absorbable film (Parietex® Composite-Sofradim). The borders of the defect were individualized by total excision of the hernial sac. A subtotal colectomy with handsewn ileocolic anastomosis had to be performed to allow for reintroduction of the small bowel into the cavity. The omentum was used as a complementary barrier to cover the abdominal viscera as well as the ileocolic anastomosis. Two 20 × 25 cm meshes were juxtaposed to ensure a very broad parietal application and secured on the posterior abdominal sheath. A dermolipectomy completed the procedure, after closing the anterior wall without tension. No parietal complication was noted and the patient recovered normal activity within 2 months. In view of the good results found in the literature of intraperitoneal mesh placement, this new mesh should be considered as a very useful approach to large incisional abdominal hernia.
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  • 3
    ISSN: 1423-0127
    Keywords: Obesity ; Ethanol ; Myocardial contraction ; Cell shortening ; Intracellular Ca2+ transients
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Obesity plays a pivotal role in metabolic and cardiovascular diseases. Certain types of obesity may be related to alcohol ingestion, which itself leads to impaired cardiac function. This study analyzed basal and ethanol-induced cardiac contractile response using left-ventricular papillary muscles and myocytes from lean and obese Zucker rats. Contractile properties analyzed include: peak tension development (PTD), peak shortening amplitude (PS), time to PTD/PS (TPT/TPS), time to 90% relaxation/relengthening (RT90/TR90) and maximal velocities of contraction/shortening and relaxation/relengthening (±VT and ± dL/dt). Intracellular Ca2+ transients were measured as fura-2 fluorescence intensity (ΔFFI) changes and fluorescence decay time (FDT). In papillary muscles from obese rats, the baseline TPT and RT90 were significantly prolonged accompanied with low to normal PTD and ± VT compared to those in lean rats. Muscles from obese hearts also exhibited reduced responsiveness to postrest potentiation, increase in extracellular Ca2+ concentration, and norepinephrine. By contrast, in isolated myocytes, obesity reduced PS associated with a significant prolonged TR90, normal TPS and ± dL/dt. Intracellular Ca2+ recording revealed decreased resting Ca2+ levels and prolonged FDT. Acute ethanol exposure (80–640 mg/dl) caused comparable concentration-dependent inhibitions of PTD/PS and ΔFFI, associated with reduced ±VT in both groups. Collectively, these results suggest altered cardiac contractile function and unchanged ethanol-induced depression in obesity.
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  • 4
    ISSN: 1432-198X
    Keywords: Key words Deflazacort ; Renal transplantation ; Renal function ; Body growth ; Obesity ; Bone mineralization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Deflazacort (DFZ) has been proposed as an alternative drug for immunosuppression after renal transplantation (TX), with fewer side effects than conventional glucocorticoids. We investigated renal function, body growth, body fat, and bone mineral density (BMD) after switching from oral methylprednisolone (MPR) to equivalent doses of DFZ 1–9 years after TX in 20 patients aged 5–20 years, selected because of severe adverse effects from previous steroid therapy. At conversion the patients received a mean dose of 7.4±2.4 mg DFZ/m2 per day. The drug was continued for a mean of 3.7 (1.2–5.5) years. Under DFZ, the glomerular filtration rate dropped slightly (NS). A single rejection episode occurred. Growth velocity significantly improved in the 1st year on DFZ treatment and height standard deviation score (SDS) increased steadily after introduction of DFZ (from –2.64 to –1.96 after 4 years, P=0.06). However, in 10 prepubertal children the height gain (+0.20 SDS in 2 years on DFZ) was not significant and the overall mean annual growth rate after TX was similar to that in 10 matched prepubertal TX children on continued MPR treatment. Relative obesity, estimated from mean body mass index corrected for height, was reduced from +1.11 SDS at the start of DFZ to +0.71 SDS after 2 years (P=0.03) and to +0.39 SDS after 4 years (NS). BMD-SDS of the lumbar spine (L2–4) increased after 1 year on DFZ (P=0.005). In conclusion, DFZ is well tolerated and safe in pediatric patients after TX. It improves relative obesity and bone mineralization. However, body growth is not significantly influenced pre puberty.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Archives of gynecology and obstetrics 263 (2000), S. 116-118 
    ISSN: 1432-0711
    Keywords: Key words 6-sulfatoxymelatonin ; Hyperprolactinemia ; Obesity ; Insomnia ; Depression ; Postmenopause
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  There is little information about the interaction between melatonin, sexual steroids and neuroendocrine system in postmenopausal females, even if former research showed that melatonin is clearly involved in human physiology and pathophysiology. We evaluated the overnight urinary excretion of 6-sulfatoxymelatonin (6-SMT) using a radioimmunoassay in 60 postmenopausal women. The group has been divided into patients with insomnia (10), hyperprolactinemia (7), depression (9), obesity (7) and controls (27). Compared to controls 6-SMT values were significantly higher in depressive females. Patients with hyperprolactinemia showed a trend toward a significantly elevated average nocturnal melatonin concentration. Melatonin levels were significantly lower in patients with insomnia and obese postmenopausal females than in controls. Since previus studies described lower melatonin levels in postmenopausal than in premenopausal women, the indication of melatonin-therapy, especially for sleep disorders in this collective, can be handled more generously. Melatonin should be prescribed restrictively in patients with depression and in those with hyperprolactinemia. The role of melatonin in obese females remains unclear.
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  • 6
    ISSN: 1432-1262
    Keywords: Keywords Pilonidal sinus ; Limberg flap ; Obesity ; Body mass index
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Recurrence of pilonidal sinus disease after surgical intervention is not a very rare problem although sophisticated reconstruction procedures have been developed. Recurrence is thought to be related to the anatomical status of the patients, i.e., depth of the intergluteal groove. Obese patients have deeper intergluteal grooves. The aim of this study was to use body mass index (BMI) as an objective indicator of obesity to determine whether there is a relationship between BMI and recurrence of pilonidal sinus disease. BMI was calculated preoperatively in 114 patients with pilonidal sinus disease who were treated by excision and Limberg flap transposition between 1996–1999 in general surgery departments of two university hospital clinics. Fifteen patients were referred to our clinics after surgical intervention carried out at other institutions. Their average BMI was calculated by using their hospital records. The mean follow-up period was 24 months (range 10–36). Six of the 114 patients (5%) had recurrence. The mean BMI of patients with and without recurrence was 29.35 and 27.415, respectively (P〈0.05). The mean BMI of 15 patients referred to us because of recurrent disease was 29.41; however, that of patients with primary pilonidal sinus disease was 27.212 (P〈0.05). Their BMI before their first operation was 29.30. This was also significantly higher than patients with primary disease (P〈0.05). We conclude that obese patients with high BMI have a higher risk of recurrence of pilonidal sinus disease after surgical intervention.
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  • 7
    ISSN: 1432-5233
    Keywords: Key words Euglycemic hyperinsulinemic clamp ; Obesity ; Type 2 diabetes mellitus ; Acanthosis nigricans
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The aim of this research was the evaluation of polymorphonuclear leukocyte (PMN) membrane fluidity in subjects with insulin resistance. Insulin sensitivity, in fact, may be influenced by plasma membrane fluidity. We enrolled 19 subjects with insulin resistance previously demonstrated during an euglycemic hyperinsulinemic clamp. PMN membrane fluidity was studied by labeling intact cells with the fluorescent probe 1-[4-(trimethyl-amino)phenyl]-6-phenyl-1,3,5-hexatriene and calculating the fluorescence polarization degree. The measurement was made before and after incubation of PMNs with two activating agents: 4-phorbol 12-myristate 13-acetate (PMN) and N-formyl-methionyl-leucyl-phenylalanine (fMLP). The baseline data showed a reduction of PMN memebrane fluidity in subjects wit insulin resistance. After PMN activation with PMA and fMLP, no significant variation in membrane fluidity was present in PMNs from normals, while in those from subjects with insulin resistance a slight decrease in PMN membrane fluidity was found only after activation with fMLP. The behavior of PMN membrane fluidity, before and after activation, distinguishes insulin-resistant subjects from normal controls, although the effect cannot be directly correlated with the degree of insulin resistance.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Coloproctology 22 (2000), S. 76-80 
    ISSN: 1615-6730
    Keywords: Key Words Acne ; Hidradenitis ; Smoking ; Obesity ; Treatment ; Recurrent disease ; Esthetical result ; Schlüsselwörter Akne ; Hidradenitis ; Rauchen ; Adipositas ; Behandlungsstrategie ; Rezidiv ; Kosmetisches Ergebnis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Acne inversa ist eine chronisch rezidivierend verlaufende, entzündliche Erkrankung der intertriginösen, terminalen Haarfollikel, die früher auch unter den Namen Hidradenitis suppurativa, Pyodermia fistulans sinifica oder Acne tetrade bekannt war. Wie bei der Acne vulgaris besteht der pathogenetische Mechanismus in einer Verstopfung des Haarfollikelostiums mit nachfolgender Ruptur des Follikels. Dies führt zu einer chronischen, granulomatösen Entzündung, welche durch Superinfektionen, Abszess- und Fistelbildung kompliziert wird. In dieser Studie wurden Krankheitsverlauf, Histologie, bakterielle Besiedelung und das Ergebnis der durchgeführten Operationen und Wundbehandlungen beurteilt. Hierzu untersuchten wir 66 Patienten mit Acne inversa, die zwischen 1987 und 1999 in unserer Klinik behandelt worden waren. Bei allen Patienten wurden die befallenen Hautareale radikal exzidiert. Die Wundheilung erfolgte sekundär. Wir fanden die Krankheit bei beiden Geschlechtern gleich häufig, das mittlere Erkrankungsalter war 22,5 Jahre bei Krankheitsbeginn und 34,7 Jahre bei Vorstellung in unserer Klinik. Die mittlere Krankheitsdauer war elf Jahre. Mehr als die Hälfte der Patienten hatten eine positive Familienanamnese. 80% der Patienten waren Raucher, 80% der männlichen Patienten litten auch unter einem Pilonidalsinus im Gegensatz zu 57% der Frauen. Nur 45% der männlichen Patienten hatten einen Befall der Inguinal- oder Perianalregion im Gegensatz zu 90% der Frauen. Es bestand keine Korrelation der Krankheitsaktivität mit Hauttyp, Adipositas oder anderen Krankheiten, insbesondere nicht mit der atopischen Dermatitis, dem Morbus Crohn oder der Colitis ulcerosa. Histologisch ließen sich bei allen Patienten Zeichen der follikulären Okklusion und einer fibrosierenden granulomatösen Dermatitis nachweisen. Darüber hinaus zeigten sich in der überwiegenden Zahl der Fälle abszedierende Fistelgänge, welche mit unterschiedlich verhornten und stark entzündlich alterierten pathologischen Epitehltypen ausgekleidet waren. Präoperativ konnte in den meisten Fällen eine Besiedelung mit Staphylococcus aureus nachgewiesen werden. Geringfügige Rezidive entstanden in 23% der Fälle, jedoch mussten nur 5,75% der Patienten ein zweites Mal operiert werden. Über 90% der Patienten waren mit dem ästhetischen und funktionellen Ergebnis der Behandlung zufrieden. Da der entzündliche Prozess von den terminalen Haarfollikeln der intertriginösen Areale ausgeht, muß es das Ziel der chirurgischen Therapie sein, diese zu entfernen. Die radikale Exzision kombiniert mit offener Wundheilung ist eine zuverlässige Behandlungsstrategie, welche nur in gefingfügigem Ausmaß zu Rezidiven führt und deren kosmetisches und funktionelles Ergebnis zufriedenstellend ist.
    Notes: Abstract Acne inversa is a chronic, recurrent, fistula- and abscess-forming disease formerly called hidradenitis suppurativa, pyodermia fistulans sinifica or acne tetrade. Like in acne vulgaris, the main pathogenetic mechanism consists of follicular occlusion with subsequent inflammation of the pilosebaceous unit. The aim of this study was to determine the outcome of the surgical procedure and wound management applied in our clinic, to indentify pathogenetic factors contributing to the course of the disease and to evaluate acne inversa patients with special respect to clinical manifestations, histology and bacterial colonisation. We evaluated 66 patients with acne inversa, treated in our clinic between 1987 and 1999. Radical excision combined with open wound healing was performed in all patients. We found both sexes equally frequent, mean age at disease onset was 22.5 years, mean age at the presentation was 34.7 years, mean duration of disease was 11 years. 55% of patients also had a family history of acne inversa. 80% of patients were smokers. 80% of males suffered also from pilonidal sinus compared to 57% of females, while only 45% of males had inguinal or perianal lesions compared to 90% of females. There was no correlation of disease activity or prevalence with other diseases, especially not with atopic dermatitis, Crohn's disease or colitis ulcerosa. Histologically most patients showed follicular occlusion, fibrosing granulomatous dermatitis and formation of sinus tracts lined by pathologicall differentiated epithelia. Staphylococcus aureus was frequently found pre-operatively. Minor recurrent disease on operated sites was noted in 23% of patients, but only 5.75% of patients required further surgical intervention. Over 90% of patients were satisfied with functional and esthetical result. Since the inflammatory process clearly emerges from the pilosebaceous unit, the aim of surgical treatment has to be the elimination of hair follicle bearing skin from the affected intertriginous areas. Radical excision combined with subsequent open wound healing has proven to be a reliable treatment resulting in minimal recurrent disease and satisfactory cosmetic result.
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  • 9
    ISSN: 1573-7284
    Keywords: Adolescents ; Body mass index ; Obesity ; Poland ; Secular trend
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The main aim of this study was to examine changes in relative weight and prevalence of obesity across a ten-year period among 14-year-old boys according to parental education level. Data from two surveys, carried out in 1987 and 1997, of boys attending the 7th grade of primary schools in Wrocław were used in the analysis. The heights and weights of 3165 boys aged 14 years selected from cohort of 6969 7th and 8th grade boys from all primary schools of the city Wrocław were used. The data of the second sample of 14-year-old boys (n = 1014) were obtained from a health examination study carried out in the Silesian Centre for Preventive Medicine, `DOLMED', in Wrocław in 1997. All boys attended the 7th grade of 34 randomly selected primary schools from a total of 129 schools in the city of Wrocław. Social status was assessed on the basis of parental education level scored to four categories: university, secondary school, trade school, and elementary school. The prevalence of overweight and obesity was defined as the percentage of children above the 85th and 95th percentiles of the body mass index (BMI), the means of which were 21.27 and 23.75 kg/m2 respectively. Prevalence of overweight among boys is slightly lower in the 1997 sample, whereas the prevalence of obesity shows the opposite trend and is higher by more than one percent in comparison with the 1987 sample. Similar trends of declining medians and increasing variance are observed in all educational groups. The differences in medians between the two samples within educational groups did not achieve statistical significance for the groups with parents with education at elementary level and fathers with university education. There is a trend toward increasing prevalence of obesity across the decade considered, according to father's education level. With respect to mother's education levels, the most dramatic changes in BMI and obesity occurred in the elementary education group, where the percentage of obese subjects increased more than twofold. A significant increase is also observed in the group with parents attaining university education.
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  • 10
    ISSN: 1573-7284
    Keywords: Age ; Alcohol intake ; Coffee ; γ-Glutamyltransferase ; Obesity ; Smoking
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The potential inverse association between coffee intake and serum γ-glutamyltransferase (GGT) was examined in a cross-sectional study involving 1353 Japanese male office workers aged 35–59 years in Osaka, Japan. Those who had serum aminotransferases exceeding the normal range and/or who had been administered medical care for, or had a past history of, liver disease were excluded. Multiple linear regression analysis and analysis of covariance were used to control for confounding variables (age, body mass index, alcohol use, and cigarette smoking) and to examine possible interactions. From the linear regression analysis, coffee intake was inversely related to serum GGT levels independently of age, body mass index, alcohol intake, and cigarette smoking. All of the latter variables were also independently and positively associated with serum GGT levels. When the interactions between coffee and each of four covariates on serum GGT were evaluated by adding each interaction term to the above regression model, significant negative interactions were observed for age and cigarette smoking. From the analysis of covariance, lower levels of serum GGT associated with coffee consumption were more evident in the older age group and at the higher levels of cigarette smoking. These findings suggest that coffee consumption is inversely related to serum GGT and that coffee may inhibit the inducing effects of aging and possibly of smoking on serum GGT in the liver.
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  • 11
    ISSN: 1573-7284
    Keywords: Child ; Italy ; Obesity ; Social class
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The aim of this study was to determine whether socio-economical status (SES) is associated with overweight and obesity in prepuberal children. In an area of North-Western Italy a sample of 1420 children, aged 10–11 years, had his/her height and weight recorded, (overweight and obesity were defined, respectively, as relative body weight ≥120% and ≥140%), and parents were requested to compile a questionnaire exploring some demographic and social conditions. 23% of the sample resulted overweight or obese. Prevalence rate ratios (PRR) of overweight and obesity (together) were calculated, adjusting for parents' age, parents' area of birth, and school district. PRR for mother's lowest educational level compared to the highest was 1.59 (95% CI: 1.19–2.13), while for father's education was 1.21 (0.90–1.63). PRRs for ‘unemployed’ or ‘manual’ mother compared to ‘upper non manual’ were respectively 1.83 (1.20–2.79) and 2.20 (1.31–3.68), while for ‘unemployed’ or ‘manual’ father were 2.63 (1.97–2.63), and 1.63 (1.27–2.09). The cultural resources of the mother, and the economical resources of the family seem to influence the prevalence of weight gain in prepuberal children. This should be taken into account when planning programs for the prevention or reduction of obesity in children.
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  • 12
    ISSN: 1573-6849
    Keywords: Chinese hamster ; comparative mapping ; genome evolution ; mouse ; reciprocal chromosome painting
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cross-species reciprocal chromosome painting was used to determine homologous chromosomal regions between the laboratory mouse and Chinese hamster. When mouse chromosome-specific paints were hybridized to Chinese hamster chromosomes, paints specific for mouse chromosomes 3, 4, 9, 14, 18, 19 and X each painted a single chromosomal region, whilst other mouse paints delineated multiple discrete chromosomal regions. The mouse Y paint produced non-specific signals on Chinese hamster chromosomes. Nineteen mouse autosome paints identified a total of 47 homologous chromosome regions in the genome of the Chinese hamster. Hybridization of Chinese hamster paints to mouse chromosomes not only confirmed the above results, but also identified which of the chromosomal regions of these two species were homologous. In total, 10 Chinese hamster autosomal paints detected 38 homologous autosomal segments in the mouse genome. A comparative chromosome map was established based on these reciprocal chromosome painting patterns. This map forms the basis for exchanging gene mapping information between the species and for studying genome evolution.
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  • 13
    Electronic Resource
    Electronic Resource
    Springer
    European journal of epidemiology 16 (2000), S. 899-905 
    ISSN: 1573-7284
    Keywords: Diet ; Endometrial cancer ; Macro-nutrients ; Micro-nutrients ; Obesity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract To evaluate the role of nutritional factors in the etiology of endometrial cancer, we performed a case-cohort analysis using data from women enrolled in the National Breast Screening Study in Canada from 1980 to 1985. For this analysis, a subcohort was constructed by selecting a 10% random sample from the 56,837 women in the dietary cohort. Cases were the 221 women diagnosed with incident adenocarcinoma of the endometrium during follow-up to December 31, 1993 and ascertained by record linkage to the Canadian Cancer Database. Information on usual diet at enrolment and other epidemiological variables was collected by means of self-administered questionnaires. Hazard ratios were obtained from proportional hazards regression models, with estimation of robust standard errors. We found a strong association of endometrial cancer with body mass index 〉25 kg/m2 (hazard ratio 2.72, 95% CI: 2.06–3.50). Endometrial cancer risk was not associated significantly with intakes of total energy, carbohydrates, proteins, total fat and major fatty acids, total dietary fiber and various types of fibers, vitamin C, E and A, folic acid, β-carotene, lutein, or cryptoxanthin. Some decrease in risk was noted with relatively high intakes of saturated fat, animal fat or lycopene. The associations observed in the study were independent of total energy intake and most non-dietary risk factors. The study suggests that dietary intakes of energy and most major nutrients are not related to the risk of endometrial cancer among Canadian women.
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  • 14
    ISSN: 1432-2307
    Keywords: Key words Autopsy ; Factor V gene ; Obesity ; Pulmonary embolism ; Sudden death
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Several clinical and environmental conditions are causally related to sudden death from acute pulmonary thromboembolism (APT). Morbid obesity, despite its frequency and association with adverse health effects, is usually considered at most only an additive risk factor for APT. We reviewed protocols and histories from 7227 consecutive autopsies performed between 1985 and 1996 at the Mayo Clinic, including all deaths from APT where no clinical or environmental risk factor could be identified in the study. Body mass indices (BMI) were calculated and compared with those of age- and sex-matched controls who had died suddenly and naturally without evidence of APT. Resistance to activated protein C is the most common molecular clotting defect predisposing to APT, and it is caused by a point mutation in the factor V gene (R506Q). Genomic DNA was extracted from archival tissues of all cases and controls, and the R506Q status was determined by polymerase chain reaction amplification, restriction endonuclease digestion, and direct sequencing. APT was found as the immediate cause of death in 433 patients, with 36 (8%) having no previously established risk factors. Twenty-four of these persons (67%) were morbidly obese (BMI 〉30 kg/m2), compared with only five controls (14%, P〈0.0001). Four patients in both groups, each with a BMI 〈30 kg/m2, had at least one allele positive for R506Q. Morbid obesity is an independent risk factor in cases of sudden death from APT after the exclusion of previously established clinical, environmental, and molecular risk factors.
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  • 15
    ISSN: 1432-1459
    Keywords: Key words Intracranial pressure ; Cerebral venous thrombosis ; Coagulation ; Thrombophilia ; Obesity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Evidence suggests that isolated intracranial hypertension (iIH) is often associated with cerebral venous thrombosis (CVT). In eight patients referred to our Institution for iIH who were later shown to harbor CVT we have performed a comprehensive coagulation work-up, including genetic tests for inherited predisposition to thrombophilia, to clarify the etiology of sinus venous thrombosis. All subjects were women. All but one were overweight. There were high plasma concentrations of D dimer, thrombin-antithrombin complexes or prothrombin fragments 1 and 2, further supporting the neuroimaging diagnosis of CVT. Importantly, seven of eight cases had a raised level of plasminogen activator inhibitor 1, a well known inhibitor of fibrinolysis related to obesity. Tissue plasminogen activator levels were elevated accordingly. Factor V gene mutation was present in one subject, and the 20210 prothrombin gene mutation was found in another individual. Three patients had elevated plasmatic levels of homocysteine. In conclusion, the present study provides solid evidence that impaired fibrinolysis probably related to overweight, acting in concert with other prothrombotic abnormalities, is involved in the pathogenesis of CVT presenting as iIH.
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  • 16
    Electronic Resource
    Electronic Resource
    Springer
    European journal of applied physiology 80 (1999), S. 233-239 
    ISSN: 1439-6327
    Keywords: Key words Energy expenditure ; Obesity ; Carbohydrate and fat oxidation ; Blood lactate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In this study we compared substrate use at submaximal intensities of a maximal graded exercise test (GXT) with that derived from equivalent intensities during continuous submaximal steady-state exercise in obese and normal-weight women. Sedentary obese (n = 20, body fat 〉30%) and normal-weight (n = 15, body fat ≤30%) women performed three treadmill tests with concurrent metabolic measurements. Maximal oxygen consumption (V˙O2max) was determined using the Bruce protocol, followed by two, randomly assigned, continuous 15-min, steady-state exercise bouts, on different days; one bout at 50% and one bout at 75% V˙O2max. Analysis of variance revealed no significant differences between groups for blood lactate or respiratory exchange ratio (R) values at any point during exercise. Therefore, obese and normal-weight group data were combined for subsequent analyses. The R at 50% V˙O2max from the GXT [0.83 (0.01)] was significantly (P 〈 0.05) lower than at 8 min [0.90 (0.01)] and 15 min [0.89 (0.01)] of steady-state exercise, whereas at 75% V˙O2max, the GXT R [0.96 (0.01)] was similar to that seen at 8 min [0.96 (0.01)] and at 15 min of steady-state exercise [0.93 (0.01)]. Blood lactate values at 50% V˙O2max were similar between the GXT [1.66 (0.10) mM] and steady-state exercise [1.65 (0.09) mM], but at 75% V˙O2max the GXT blood lactate values [2.58 (0.21) mM] were lower than after 15 min of steady-state exercise [4.65 (0.46) mM]. Total exercise fat oxidation was greater at 50% compared to 75% V˙O2max. There was no difference in substrate use between sedentary obese and normal-weight women either at rest or during steady-state exercise at the same relative intensity. Total fat oxidation was greater during low- (50% V˙O2max) compared to high-intensity (75% V˙O2max) exercise. Data from a GXT cannot be used to predict R or substrate utilization values for the purpose of exercise prescription.
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  • 17
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    European journal of epidemiology 15 (1999), S. 41-49 
    ISSN: 1573-7284
    Keywords: Child ; Kuwait ; Matched case–control study ; Obesity ; Risk factors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The prevalence of adult obesity in Kuwait is among the highest in the Arab peninsula, and cardiovascular disease, for which obesity is a risk factor, is the leading cause of death. This study reports familial and environmental factors associated with childhood obesity; in addition to adverse effects of obesity on children's serum lipids, lipoproteins, apolipoproteins, insulin, and blood pressure profiles. The authors carried out a pair-matched case–control study including 460 obese (body mass index 〉90th percentile of the age/sex specific reference value of the National Center for Health Statistics), school children 6 to 13 years old matched by age and gender to 460 normal weight controls. We ascertained obese children in a cross-sectional survey of a representative sample of 2400 school children selected from 20 schools by multistage stratified random sampling. Biochemical variables and blood pressure were adversely affected in obese children. The conditional logistic regression analysis showed that family history of obesity, and diabetes mellitus, respiratory and bone diseases in child were significant associated factors with obesity after adjusting for social and behavioural factors. Physical activity and parental social class were not significant. We recommend early preventive measures with emphasis on families in which one or both parents are overweight.
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  • 18
    ISSN: 1573-7284
    Keywords: Italy ; Obesity ; School
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Childhood and adolescent obesity prevalence rates have steadily increased in industrialised countries in the last 20 years. Current rates of obesity range between 6 and 30%. Several studies showed that risk factors for weight gain in school age are strongly linked to low physical activity and family environmental factors (parents' education and job, number of family members, number of hours spent on watching television, etc.). In order to plan a nutritional and health educational programme, a study was conducted on the nutritional status of the school age population of the Province of Frosinone, Central Italy, and family factors that can influence it. Three percentage of the school age population of the Province of Frosinone (2053 students) and their families were randomly sampled from the Province school district database. In each of the 12 recruited schools, a meeting with teachers and students was arranged to discuss aims and methods of research and to collect informed consent by students. Each student was interviewed about physical activity, and underwent the following measurements: height, weight, bicipital, tricipital, sub-scapular and over-iliacal skinfolds, sexual development. Students' parents were asked to answer a questionnaire about family structure, parents' educational level and job, parents' height and weight, presence in the family of pathologies as hypertension or diabetes. One thousand three hundred fifty-seven students (66% of the target population) and 1802 parents (66.5% of the responders' population) agreed to enter the study. Students' age range was 8 years (11–19 years; mean age was 14.9, SD, 2.55). Among them 8.4% were considered obese, with a higher prevalence in male population (9.8%) as compared to female population (6.5%). Of these responders, 21.4 % were considered at risk of overweight with no statistical difference due to gender. Statistically significant correlations of teenagers' risk of overweight and obesity with nutritional conditions of parents, mother's educational level and amount of weekly physical activity were observed. Number of children in the family, parents' age and job do not appear to be correlated to obesity or risk of overweight. Our results show that, although the prevalence of obesity in the students population in the Province of Frosinone is comparable to other Italian Provinces and lower than other industrialised countries such as USA, the percentage of students at risk of overweight is particularly high. Main risk factors for developing obesity seem to be linked to parents' nutritional conditions, mother's educational level and children's physical inactivity and this should lead to intensify efforts for preventive interventions both at family level (focused on parents) and at school.
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  • 19
    ISSN: 1573-3297
    Keywords: Obesity ; eating ; common environment ; unique environment ; heritability ; twins ; gene–environment interaction ; behavior
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Psychology
    Notes: Abstract Human obesity is associated with greater-than-average energy intake, although relatively few studies have tested the heritability of food intake. The present study examined the genetic architecture of measured caloric intake during laboratory test meals in 36 monozygotic and 18 dizygotic twin pairs. A series of analyses tested the hypotheses that (1) there would be a genetic influence on total caloric intake, (2) there would be genes influencing total caloric intake above and beyond those influencing body composition, (3) there would be a phenotypic association between total caloric intake and fat mass above and beyond any genetic influences, and (4) there would be genetic influences on macronutrient intake (i.e., fat, carbohydrate, and protein intake) above and beyond total caloric intake. Results suggested genetic influences on age- and sex-adjusted total caloric intake (24–33% of the variance), although 95% confidence intervals were wide and suggested that “true” heritability estimates might be considerably lower or higher. Caloric intake was influenced by both common and unique environmental factors. Greater-than-average caloric intake was associated with increased adiposity, despite probable genetic influences on both phenotypes. Finally, there was evidence for macronutrient-specific familial influences, although the extent to which they were genetic or environmental in origin could not be teased apart. Results suggest that human obesity may be influenced by behaviors that are themselves genetically regulated. However, further studies are needed to obtain more precise heritability estimates and a better understanding of the conditions under which genetic influences on energy intake emerge.
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  • 20
    ISSN: 1573-7284
    Keywords: Cigarette smoking ; Menstruation ; Nutrition ; Obesity ; Race ; Reproductive history ; Sex hormones
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract While irregular menstruations have been associated with lower cumulative exposure to the ovarian steroids, shorter regular cycles have been postulated to increase the cumulative exposure. Epidemiological correlates with menstrual patterns were analyzed among 4900 premenopausal women aged 45 or younger from the New York University Women's Health Study. The length of regular menstrual cycles increased with increasing age at menarche, body mass index and parity, but decreased with age, nonwhite racial background and current smoking. The likelihood of irregular cycles increased with increasing age, body mass index and number of cigarettes smoked per day. With adjustment for age, body mass index and number of cigarettes smoked per day, the risk of irregular cycles was marginally positively associated with total fat intake.
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  • 21
    ISSN: 1573-2649
    Keywords: Health-Related Quality of Life ; Obesity ; Weight loss
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract To examine the effect of treatment-induced weight loss on Health-Related Quality of Life (HRQL), 38 mildly-to-moderately overweight persons recruited to participate in a study to examine the efficacy of a lifestyle modification treatment program completed a sociodemographic questionnaire, the Beck Depression Inventory (BDI), the Medical Outcomes Study Short-Form Health Survey (SF-36, as an assessment of HRQL), and underwent a series of clinical evaluations prior to treatment. After baseline evaluations, participants were randomly assigned to either a program of lifestyle physical activity or a program of traditional aerobic activity. Participants again completed the SF-36 and BDI after the 13-week treatment program had ended. Weight loss averaged 8.6 ± 2.8 kg over the 13-week study. We found that weight loss was associated with significantly higher scores (enhanced HRQL), relative to baseline, on the physical functioning, role-physical, general health, vitality and mental health domains of the SF-36. The largest improvements were with respect to the vitality, general health perception and role-physical domains. There were no significant differences between the lifestyle and aerobic activity groups on any of the study measures. These data indicate that, at least in the short-term, weight loss appears to profoundly enhance HRQL.
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  • 22
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    International urogynecology journal 9 (1998), S. 140-144 
    ISSN: 1433-3023
    Keywords: Constitution ; Physical work ; Obesity ; Urinary incontinence ; Women
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Urinary incontinence in women is a common and complex problem which can be defined and classified as stress, urge and mixed incontinence. Three of the eight most common risk factors are obesity, constitution and physical work, in addition to age, length of menstrual cycle, number of pregnancies, education and level of health awareness. Women with the diagnosis of urinary incontinence were invited to respond to questionnaires on a voluntary basis. The three factors found to be associated with urinary incontinence are increased body weight, strong osteomuscular structure and hard physical work. These indicate that the work of a health team must take a holistic approach to women even before the phenomenon of urinary incontinence occurs.
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  • 23
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    Hernia 2 (1998), S. 175-177 
    ISSN: 1248-9204
    Keywords: Incisional hernia ; Obesity ; Postoperative complications ; Suture technique ; Wound healing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The aim of this study was to report the incidence of incisional hernias following midline laparotomy incisions after 12 months and after 8 years. 374 patients who underwent midline laparotomy between August 1989 and December 1990 were included. The wounds were closed with a continuous suture and the technique was monitored by the suture length to wound length ratio. The incidence of incisional hernia, defined as a palpable defect in the fascia or a protrusion beyond this level, was monitored at 12 months and after 8 years. Early wound dehiscence occurred in 3 patients (1%) and wound infection in 32 (9%). At the 12-month examination 58 (20%) incisional hernias were detected in 292 patients. After 8 years 142 patients were examined and 5 (3%) hernias were found. All hernias that caused inconvenience or required surgical repair were detected at 12 months follow-up. Most hernias appearing later have probably been overlooked at the first examination.
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  • 24
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    Monatsschrift Kinderheilkunde 146 (1998), S. 1192-1196 
    ISSN: 1433-0474
    Keywords: Schlüsselwörter Body-mass-Index ; Übergewicht ; Adipositas ; Key words Body Mass Index ; Overweight ; Obesity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Objective: To examine changes in Body Mass Index (BMI) in children in the last twenty years and to determine the prevalence of overweight and obesity. Design and Subjects: Body height and body weight were measured in Jena school children 7 to 14 years of age in cross-sectional anthropological investigations in 1975, 1985 and 1995 and from these measurements the Body Mass Index (BMI) was calculated. The investigated children were classified as overweight or obese by the age- and sex-specific 90th or 97th percentile values of BMI from Rolland-Cachera et al. [31] recommended by the European Childhood Obesity Group. Results: Between 1975 and 1995 the BMI of Jena children increased. The prevalence of overweight and obesity among the children increased also. These changes were striking between 1985 and 1995. Conclusions: Changing living conditions, e. g. changes in the leisure-time lifestyle, in dietary practices and in the families, related to the unification of Germany in 1989, may be caused this trend.
    Notes: Zusammenfassung Fragestellung/Hintergrund: Es wurden Veränderungen des Body-mass-Index (BMI) bei Kindern in den letzten 20 Jahren untersucht und die Prävalenz von Übergewicht und Adipositas bestimmt. Methode und Probanden: Körperhöhe und Körpergewicht wurden im Rahmen anthropologischer Querschnittsuntersuchungen in den Jahren 1975, 1985 und 1995 bei 7- bis 14jährigen Jenaer Kindern erfaßt und daraus der Body-mass-Index berechnet. Die Einstufung der untersuchten Kinder als übergewichtig und adipös erfolgte anhand der von der European Childhood Obesity Group empfohlenen alters- und geschlechtsspezifischen 90. oder 97. Perzentile für den BMI von Rolland-Cachera et al. [31]. Ergebnisse: Zwischen 1975 und 1995 stieg der BMI der Jenaer Kinder an. Der prozentuale Anteil von Kindern, die als übergewichtig oder adipös einzustufen sind, nahm ebenfalls zu. Diese Veränderungen fielen zwischen 1985 und 1995 besonders deutlich aus. Schlußfolgerungen: Veränderte Lebensbedingungen, wie z. B. Änderungen beim Freizeitverhalten, beim Ernährungsverhalten oder in der Familienstruktur, die im Zusammenhang mit der politischen Wende im Jahr 1989 auftraten, werden als Ursache für diesen Trend angesehen.
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  • 25
    ISSN: 1432-198X
    Keywords: Key words: Kidney length ; Body weight ; Body mass index ; Systolic blood pressure ; Obesity ; Hypertension
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Somatometric parameters, renal size, and systolic blood pressure (SBP) were studied in 406 patients referred to pediatric nephrology and urology clinics. These patients included 269 females (66%), 67 African Americans (17%), and 87 patients with essential hypertension (21%). Z scores for the study population were comparable to published standards for height, kidney length, and SBP. Weight and body mass index scores were significantly greater than predicted from the standards, especially in the subset of patients with essential hypertension. Age, height, weight, body mass index, kidney length, and SBP all correlated with one another; however, on multiple regression analysis of SBP with the other five independent variables, only weight proved to have a significant correlation. Furthermore, the relationship of kidney length with SBP was positive and hypertensive patients had greater kidney size than published standards. These data do not support reduced kidney size in the population with essential hypertension, nor is there support for a convincing correlation between kidney length and SBP in the general pediatric population. Body weight correlates best with blood pressure. These findings warrant further study in a less-select population. Prevention and treatment of obesity may thus be of prime importance in addressing hypertension in children.
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  • 26
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    European journal of clinical pharmacology 54 (1998), S. 621-625 
    ISSN: 1432-1041
    Keywords: Key words Vancomycin ; Obesity ; Pharmacokinetic variability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Objectives and methods: Vancomycin hydrochloride dosing requirements in morbidly obese patients with normal renal function were computed to determine the dose of vancomycin necessary to achieve target steady-state peak and trough concentrations and compared with a normal weight population. Results: Morbidly obese patients [total body weight (TBW) 165 kg, ideal body weight (IBW) 63 kg] required 31.2 mg · kg−1 · d−1 TBW or 81.9 mg · kg−1 · d−1 IBW to achieve the target concentrations. Normal weight patients (TBW 68.6 kg) required 27.8 mg · kg−1 · d−1 to achieve the same concentrations. Because of altered kinetic parameters in the morbidly obese patients (obese: t1/2=3.3 h, V=52 l, CL =197 ml · min−1; normal: t1/2=7.2 h, V=46 l, CL=77 ml · min−1, 20 of 24 patients required q8h dosing (1938 mg q8h) compared with q12h dosing (954 mg q12h) in all normal weight patients in order to avoid trough concentrations that were too low for prolonged periods. There was a good correlation between TBW and CL, but only fair correlation between TBW and V. Conclusion: Doses required to achieve desired vancomycin concentrations are similar in morbidly obese and normal weight patients when TBW is used as a dosing weight for the obese (approximately 30 mg · kg−1 · d−1). Shorter dosage intervals may be needed when dosing morbidly obese patients so that steady-state trough concentrations remain above 5 μg · ml−1 in this population. Because of the large amount of variation in required doses, vancomycin serum concentrations should be obtained in morbidly obese patients to ensure that adequate doses are being administered. Dosage requirements for morbidly obese patients with renal dysfunction require further study.
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  • 27
    ISSN: 1432-2013
    Keywords: Key words Exercise ; Fatigue ; Obese women ; Obesity ; Lactate threshold ; Lactate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  A series of untrained, healthy, obese women (body mass index 32.5 ± 0.9 kg·m–2) were subjected to a protocol of intense exercise on a cycloergometer and compared with lean controls (body mass index 20.9 ± 0.5 kg·m–2). Physiological parameters, blood lactate, bicarbonate, plasma metabolites, oxygen consumption and CO2 production were measured. Impedance-derived extracellular water and plasma changes in lactate and bicarbonate were used to determine changes in bicarbonate pools and lactate-displaced CO2. From these and respiratory gases, the respiratory quotient was calculated and thence overall fuel consumption. Anaerobic energy during exercise accounted for about 1.8% of all energy consumed in the lean but only 0.7% in the obese. Obese women fatigued at lower workloads and energy expenditure levels than did the lean, and their lactate buildup was similar when compared on the basis of fat-free mass. The data support the postulation of fatigue being triggered by a combination of factors: stretched cardiovascular work would be the main factor for obese women, in part limiting lactate production. For lean women, the triggering factor for fatigue could be the loss of buffering capacity; but it is the combination of stretching cardiovascular capacity, exhaustion of glycogen and available glucose and increase in lactate/loss of bicarbonate buffer that determines the onset of fatigue.
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  • 28
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    Acta diabetologica 35 (1998), S. 117-129 
    ISSN: 1432-5233
    Keywords: Key words Incretin ; Gastric inhibitory polypeptide ; Glucagon-like peptide 1 ; Gut hormones ; Type 2 diabetes ; Type 1 diabetes ; Obesity ; New treatment modalities
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Glucagon-like peptide 1 (GLP-1) is a physiological incretin hormone from the lower gastrointestinal tract, partially explaining the augmented insulin response after oral compared to intravenous glucose administration in normal humans. In addition, GLP-1 also lowers glucagon concentrations, slows gastric emptying, stimulates (pro)insulin biosynthesis, and reduces food intake upon intracerebroventricular administration in animals. Therefore, GLP-1 offers some interesting perspective for the treatment of type 2, and perhaps also for type 1 diabetic patients. The other incretin hormone, gastric inhibitory polypeptide (GIP), has lost almost all its activity in type-2 diabetic patients. In contrast, GLP-1 glucose-dependently stimulates insulin secretion in type-2 diabetic patients and exogenous administration of GLP-1 ([7–37] or [7–36 amide]) in doses elevating plasma concentrations to approximately three to four times physiological postprandial levels fully normalizes fasting hyperglycaemia and reduces postprandial glycaemic increments. Due to rapid proteolytic cleavage, which results in an inactive or even antagonistic fragment, GLP-1 [9–36 amide], and to rapid elimination, the half-life of GLP-1 is too short to maintain therapeutic plasma levels for sufficient periods by subcutaneous injections of the natural peptide hormone. Current research aims to characterize GLP-1 analogues with more suitable pharmacokinetic properties than the original peptide. Given the large amount of GLP-1 present in L cells, it also appears worthwhile to search for more agents that could `mobilize' this endogenous pool of GLP-1.
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  • 29
    ISSN: 1432-5233
    Keywords: Key words Bioelectric impedance ; Body water ; Obesity ; Non-insulin-dependent diabetes ; Insulin-dependent diabetes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Since bioelectrical characteristics correspond well to body water compartments, this study investigated bioelectrical differences between type 1 and type 2 diabetic subjects that could reflect differences in body water compartments. We investigated cross-sectionally 612 adult subjects, classified into 10 groups according to sex and disease (control, obese normal glucose tolerant, non-obese type 2 diabetes, obese type 2 diabetes, type 1 diabetes). Resistance (R), reactance (Xc) and phase angle (PA) were measured (800 μA – 50 kHz alternating current). The bioelectrical vector was obtained by plotting R and Xc normalized for height (ht), it is easily identified on the basis of the length (inversely related to the total body water, likewise R) and direction, given by the PA (inversely related to the extra-/intra-cellular water – ECW/ICW –). Results show that disease and sex had a significant (ANOVA: P〈0.0001 for both F disease and F sex) and independent effect on both R/ht and Xc/ht; no difference was found between type 2 and type 1 diabetic groups. A bioelectrical vector with a lower PA characterized both type 2 and type 1 diabetic groups. An independent positive correlation between fasting plasma glucose and R/ht and a negative correlation between fasting plasma glucose and PA were observed. These findings suggest a non-different body water content and distribution between type 2 and type 1 diabetic subjects; the bioelectrical vector indicates a higher ECW/ICW in type 2 and type 1 diabetic compared to non-diabetic subjects.
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  • 30
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    International journal of anthropology 13 (1998), S. 117-128 
    ISSN: 1824-3096
    Keywords: Obesity ; systolic blood pressure ; diastolic blood pressure ; body composition ; anthropometry ; impedance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Estimates of relationships between blood pressures and anthropometric structure or body composition were made on a total sample of 414 children, taking age and sex into account. A subsample of 250 children was formed from obese (or slightly obese) subjects. A different pattern in anthropometric structure and body composition resulted in relation to a different degree of obesity. A canonical correlation analysis was carried out for each sex, in which a multivariate measure of the linear association between heart-circulatory functionality parameters, on the one hand, and all the anthropometric traits and body composition parameters, on the other, was computed. This association resulted statistically significant in both sexes, also if a difference was observed as concerns the traits that most heavily contributed to the relation-ships between sets of variables, with an evident sexual dimorphism also in infancy. The necessity of preventive measures and sanitary screening also during infancy was pointed out.
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  • 31
    ISSN: 1439-6327
    Keywords: Key words Exercise ; Obesity ; Lipoproteins ; Glucose tolerance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We characterized the effect of ten days of training on lipid metabolism in 6 [age 37.2 (2.3) years] sedentary, obese [BMI 34.4 (3.0) kg · m−2] males with normal glucose tolerance. An oral glucose tolerance test was performed prior to and at the end of the 10 d of training period. The duration of each daily exercise session was 40 min at an intensity equivalent to ˜75% of the age predicted maximum heart rate. Blood measurements were performed after an overnight fast, before and at the end of the 10 d period. Plasma triacylglycerol was significantly (p 〈 0.05) reduced following exercise training (2.15 ± 0.29 vs. 1.55 ± 0.28 mmol · l−1). Very low density lipoprotein-triacylglycerol was also significantly (p 〈 0.05) reduced (1.82 ± 0.3 vs. 1.29 ± 0.29 mmol · l−1). No significant changes in high density lipoprotein-cholesterol were observed as a result of training. Following training fasting plasma glucose and fasting plasma insulin were significantly reduced [Glucose: 5.9 (0.2) mmol · l−1 vs. 5.3 (0.22) mmol · l−1 (p 〈 0.05); Insulin 264.3 (53.8) ρ · mol · l−1 vs. 200.9 (30.1) ρ · mol · l−1, p = 0.05]. The total area under the glucose curve during the OGTT decreased significantly (p 〈 0.05). These preliminary data suggest that short-term exercise, without concomitant loss of body mass, induces favorable changes in plasma triacylglycerol, and very low density lipoprotein-triacylglycerol and glucose tolerance but has no effect on high density lipoproteincholesterol.
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  • 32
    ISSN: 1573-7284
    Keywords: High lipids ; Hypertension ; Obesity ; Prevalence ; Region
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Objectives: the study was set up to explore regional disparities in France in the annual prevalence of cardiovascular risk factors (hypertension, high lipids, obesity, diabetes and tobacco consumption) and protective factors (alcohol intake) in members of the GAZEL Cohort and to determine which, if any, risk factors followed the same north-south gradient as the one known for cardiovascular mortality. Methods: the population studied comprised 18,070 subjects aged from 35 to 50 years, employed by the French national gas and electricity company. Every year from 1989 to 1993 they received a self-administered questionnaire by mail. From the replies, differences in risk factor prevalence were evaluated by an odds ratio adjusted for sex and age, using a marginal model. Results: a regional effect was found (p 〈 0.001) for arterial hypertension, with high odds ratios in northern France and low ratios in the south east, for high lipids, with high odds ratios in Champagne, the Loire region and Upper Normandy and low ratios in the south east and the Paris area, and for obesity, with high odds ratios in the north and north east and low ratios in the south, south east and west. Conclusion: these results show a gradient between the north and south east for hypertension, obesity, and to a lesser degree high lipids. This gradient corresponds to the known regional disparities for cardiovascular mortality.
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  • 33
    ISSN: 1573-7284
    Keywords: Alcohol ; Cholesterol ; High density lipoprotein ; Obesity ; Occupational health ; Physical activity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We studied some life-style characteristics that may predict changes in total serum cholesterol and cholesterol bound to high density lipoproteins (HDL-cholesterol) in a sample of 980 healthy Spanish employees of both sexes who were followed for three years. All workers participated in a multifactorial program aimed at preventing cardiovascular disease. Linear regression models were fitted with changes in total and HDL-cholesterol as the dependent variables, after eliminating variability due to the influence of basal values. The association between lifestyle factors and lipid changes was controlled for dietary modifications. In the multivariate analysis, decreases in body mass index, and in alcohol consumption were associated with significant reductions in total serum cholesterol. Maintaining sports at post-test or starting to practice them in the interim was also significantly and independently associated with favourable changes in serum cholesterol. Leisure-time exercise (p=0.002) and giving up smoking (p = 0.06) were each associated with increased HDL-cholesterol.
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  • 34
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    Plant foods for human nutrition 53 (1998), S. 15-28 
    ISSN: 1573-9104
    Keywords: Cholesterol ; Diabetes ; Glucose ; Guar gum ; Low-density-lipoprotein ; Obesity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of guar gum derived from the endosperm of Cyamopsis tetragonoloba (75% soluble fiber, 7.6% insoluble fiber, 2.16% crude protein, 0.78% total lipids, 0.54% ash and 9.55% moisture) on food intake, levels of blood serum cholesterol, triacylglycerols, glucose and LDL and HDL-cholesterol were studied. The effects of guar gum on indices of protein absorption and utilization were also investigated. Diets containing 0%, 10% and 20% (w/w) guar gum or 10% and 20% cellulose powder (reference) were fed to normal rats for 60 days. The rats fed the guar gum diets showed significantly (p ≤ 0.05) lower levels of blood serum cholesterol, triacylglycerols, reduced food intake and body weight gain. Furthermore, a concomitant increase in HDL-cholesterol with a substantial elevation of the HDL/LDL cholesterol ratio were noted. Guar gum decreased blood serum glucose only during the first month of the experiment, and no changes in the indices of protein absorption and utilization were found. The guar gum caused a 10% increase in the small intestine length and a 25% retardation in the intestinal transit. The results of this research suggested that guar gum could potentially be effective in the treatment of hypercholesterolemia and obesity in humans.
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  • 35
    ISSN: 1573-7284
    Keywords: BMI ; Height ; Increase ; Obesity ; Prevalence ; Secular trends ; Weight
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Objective: To examine the secular trend of weight, height and obesity among young Portuguese males at the time of military inspection for national conscription purposes in the region of Lisbon, during the last thirty years. Design: Cross-sectional study, based on the review of military census files. Setting: Military selection centre of Lisbon. Subjects and methods: In Portugal, military service is obligatory and medical inspections are carried out every year on males at the age of twenty. For study purposes, representative samples were taken from the young male population undergoing inspection for the Armed Forces on a five year basis, between 1960 and 1990 in the region of Lisbon. Weight and height were evaluated by a trained team, using standard measurement instruments and procedures. Results: A progressive and significant increase in weight, height and BMI of the young male population was found between 1960 and 1990. For certain variables the increase was also statistically significant within a five-year period, as it was the case for height between 1965–1980 and for weight between 1985–1990. The increase in BMI experienced some minor fluctuation along the reference period, however, it was statistically significant between 1985–1990. The increase in weight and in BMI was greater in the highest percentiles and particularly noticeable between 1985 and 1990. The percentage of young males with BMI over 25 kg/m2 was of 8.1% in 1960 and of 18.0% in 1990, while those having a BMI over 27 kg/m2 varied between 3.6% and 6.4% in the same period, respectively. The percentage of young adult males with BMI higher than 25 kg/m2 doubled between 1960 and 1990.
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  • 36
    ISSN: 0006-3525
    Keywords: folding type-specific secondary structure propensities ; amino acids ; α-helical proteins ; β sheet proteins ; α/β proteins ; α+β proteins ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Folding type-specific secondary structure propensities of 20 naturally occurring amino acids have been derived from α-helical, β-sheet, α/β, and α+β proteins of known structures. These data show that each residue type of amino acids has intrinsic propensities in different regions of secondary structures for different folding types of proteins. Each of the folding types shows markedly different rank ordering, indicating folding type-specific effects on the secondary structure propensities of amino acids. Rigorous statistical tests have been made to validate the folding type-specific effects. It should be noted that α and β proteins have relatively small α-helices and β-strands forming propensities respectively compared with those of α+β and α/β proteins. This may suggest that, with more complex architectures than α and β proteins, α+β and α/β proteins require larger propensities to distinguish from interacting α-helices and β-strands. Our finding of folding type-specific secondary structure propensities suggests that sequence space accessible to each folding type may have differing features. Differing sequence space features might be constrained by topological requirement for each of the folding types. Almost all strong β-sheet forming residues are hydrophobic in character regardless of folding types, thus suggesting the hydrophobicities of side chains as a key determinant of β-sheet structures. In contrast, conformational entropy of side chains is a major determinant of the helical propensities of amino acids, although other interactions such as hydrophobicities and charged interactions cannot be neglected. These results will be helpful to protein design, class-based secondary structure prediction, and protein folding. © 1998 John Wiley & Sons, Inc. Biopoly 45: 35-49, 1998
    Additional Material: 6 Ill.
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  • 37
    Electronic Resource
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    New York : Wiley-Blackwell
    Biopolymers 45 (1998), S. 69-83 
    ISSN: 0006-3525
    Keywords: DNA branched junctions ; branch migration ; superhelical torque ; control of DNA structure ; endonuclease VII ; nanomechanical device ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: DNA branched junctions are analogues of Holliday junction recombination intermediates. Partially mobile junctions contain a limited amount of homology flanking the branch point. A partially mobile DNA branched junction has been incorporated into a synthetic double-stranded circular DNA molecule. The junction is flanked by four homologous nucleotide pairs, so that there are five possible locations for the branch point. Two opposite arms of the branched junction are joined to form the circular molecule, which contains 262 nucleotides to the base of the junction. This molecule represents a system whereby torque applied to the circular molecule can have an impact on the junction, by relocating its branch point. Ligation of the molecule produces two topoisomers; about 87% of the product is a relaxed molecule, and the rest is a molecule with one positive supercoil. The position of the branch point is assayed by cleaving the molecule with endonuclease VII. We find that the major site of the branch point in the relaxed topoisomer is at the maximally extruded position in the relaxed molecule. Upon the addition of ethidium, the major site of the branch point migrates to the minimally extruded position. © 1998 John Wiley & Sons, Inc. Biopoly 45: 69-83, 1998
    Additional Material: 9 Ill.
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  • 38
    ISSN: 0006-3525
    Keywords: conformation ; aggregation ; κ-carrageenan ; flow field-flow fractionation ; multiangle light scattering ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The relatively novel combination of flow field-flow fractionation (FFF) and multiangle light scattering (MALS) was employed to study a nondegraded κ-carrageenan in different 0.1M salt solutions. The applicability of the technique was tested, and the effects of salt type and salt composition on the molar mass and radius of gyration were studied. A conformational ordering was induced at room temperature by switching the solvent from 0.1M NaCl (coil form) to 0.1M NaI (helix form). An approximate doubling of the average molar mass and an increase in radius of gyration was then observed, in agreement with results obtained previously using size exclusion chromatography-MALS. This increase in size was attributed to conformational ordering and to the formation of double helices. Severe aggregation was observed above 40% CsI in the 0.1M mixed salt solution of CsI and NaI. This was ascribed to the association of helices into large aggregates. For these large associates, having molar masses of several millions, a reversal of the elution order in flow FFF was detected. © 1998 John Wiley & Sons, Inc. Biopoly 45: 85-96 1998
    Additional Material: 10 Ill.
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  • 39
    Electronic Resource
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    Biopolymers 45 (1998), S. 119-133 
    ISSN: 0006-3525
    Keywords: conformations of D-alanyl-D-alanine ; β-lactam ; structural overlay ; AMBER force field ; AM1 ; ab initio ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In this article a conformational analysis of the D-alanyl-D-alanine dipeptide, both charged and neutral, has been carried out. The preferred conformations were determined by means of ab initio and semiempirical quantum, together with empirical force field calculations. The AMBER* force field and the 6-31 + G** and 6-31G** ab initio levels give rise to a coincident minimum energy structure, which, on the other hand, differs from that determined by AM1, 3-21 + G, and 3-21G. The solvent effect on the different charged and neutral conformations have been considered through the AMSOL semiempirical method. A quantification regarding the structural similarities between the different dipeptide conformations and the ampicillin has been performed. The results show that the best overlay is attained by the minimum structure energy obtained by using the 6-31 + G** methodology, which presents a planar amidic nitrogen. © 1998 John Wiley & Sons, Inc. Biopoly 45: 119-133, 1998
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  • 40
    ISSN: 0006-3525
    Keywords: chemical oxidation ; cellulose ; conformational transition ; capillary viscosity ; microcalorimetry ; calcium ions ; gels ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The conformational behavior of different molecular weight fractions of a synthetic C6-oxidized derivative of cellulose were investigated by means of capillary viscometry, CD, and microcalorimetric measurements. Experiments were carried out in the presence of either monovalent or divalent counterions.The experimental data indicated that C6-oxidized cellulose can assume an ordered extended conformation at low ionic strength, induced by the intrachain repulsions of negative charges. This conformation was suggested to be very similar to the fully extended structure of cellulose. In addition to this, upon increasing the ionic strength, a conformational transition of the order-to-disorder type occurred. In fact, the screening of the electrostatic repulsions introduced a number of conformational kinks into the cellulosic backbone, which enabled the polymer to assume a more coiled conformation hence producing less viscous aqueous solutions. © 1998 John Wiley & Sons, Inc. Biopoly 45: 157-163, 1998
    Additional Material: 6 Ill.
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  • 41
    ISSN: 0006-3525
    Keywords: conformational stability ; biological polyelectrolytes ; enthalpy ; entropy ; conformational transitions ; carrageenan ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new method is proposed for the determination of the enthalpy and entropy changes of nonionic origin upon conformational transition of linear biopolyelectrolytes in solution. For all transition midpoints, defined by given temperature and ionic strength, the total free energy change of the system is zero, which means that the nonionic contribution to the free energy change is equal in value and opposite in sign to the polyelectrolytic one. The counterion condensation theory of linear polyelectrolytes provides for the appropriate analytical expression to be used in such calculations. Linear plots of the proper functions of the calculated free energy changes vs the proper functions of temperature allows for the determination of the enthalpic and entropic terms of the nonionic free energy change of transition.The method has been applied to the extensive available data of the ion-induced conformational change of κ-carrageenan, a linear sulfated galactan extracted from seaweeds. The method has proved very successful, with the results showing a remarkable convergency of the enthalpy values for different monovalent counterions. On the other hand, the above approach has made it possible to explain the known effect of counterion specificity on the transition by a small difference in the nonionic entropic contributions. © 1998 John Wiley & Sons, Inc. Biopoly 45: 203-216, 1998
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  • 42
    ISSN: 0006-3525
    Keywords: uv resonance Raman spectroscopy ; Raman cross section ; hypochromism ; DNA ; deoxynucleoside ; protein ; aromatic amino acid ; virus assembly ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ultraviolet resonance Raman (UVRR) spectra of H2O and D2O solutions of the nucleoside (dA, dG, dC, dT) and aromatic amino acid (Phe, Trp, Tyr) constituents of DNA viruses have been obtained with laser excitation wavelengths of 257, 244, 238, and 229 nm. Using the 981 cm-1 marker of Na2SO4 as an internal standard, Raman frequencies and scattering cross sections were evaluated for all prominent UVRR bands at each excitation wavelength. The results show that UVRR cross sections of both the nucleosides and amino acids are strongly dependent on excitation wavelength and constitute sensitive and selective probes of the residues. The results provide a library of UVRR marker bands for structural analysis of DNA viruses and other nucleoprotein assemblies. © 1998 John Wiley & Sons, Inc. Biopoly 45: 247-256, 1998
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  • 43
    ISSN: 0006-3525
    Keywords: hemoglobin ; hexagonal bilayer ; Lumbricus ; electron microscopy ; three-dimensional reconstruction ; small-angle x-ray scattering ; three-dimensional models ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The quaternary structure of Lumbricus terrestris hemoglobin was investigated by small-angle x-ray scattering (SAXS). Based on the SAXS data from several independent experiments, a three-dimensional (3D) consensus model was established to simulate the solution structure of this complex protein at low resolution (about 3 nm) and to yield the particle dimensions. The model is built up from a large number of small spheres of different weights, a result of the two-step procedure used to calculate the SAXS model. It accounts for the arrangement of 12 subunits in a hexagonal bilayer structure and for an additional central unit of cylinder-like shape. This model provides an excellent fit of the experimental scattering curve of the protein up to h = 1 nm-1 and a nearly perfect fit of the experimental distance distribution function p(r) in the whole range. Scattering curves and p(r) functions were also calculated for low-resolution models based on 3D reconstructions obtained by cryoelectron microscopy (EM). The calculated functions of these models also provide a very good fit of the experimental scattering curve (even at h 〉 1 nm-1) and p(r) function, if hydration is taken into account and the original model coordinates are slightly rescaled. The comparison of models reveals that both the SAXS-based and the EM-based model lead to a similar simulation of the protein structure and to similar particle dimensions. The essential differences between the models concern the hexagonal bilayer arrangement (eclipsed in the SAXS model, one layer slightly rotated in the EM model), and the mass distribution, mainly on the surface and in the central part of the protein complex. © John Wiley & Sons, Inc. Biopoly 45: 289-298, 1998
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  • 44
    ISSN: 0006-3525
    Keywords: conformational changes ; vicinal glycosylation ; branched α-l-Rhap(1-2)[β-d-Galp(1-3)]-β-d-Glc1-OMe trisaccharide ; parent disaccharides ; hydrogen bond ; isotope effect ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Conformations of the α-l-Rhap(1-2)-β-d-Glc1-OMe and β-d-Galp(1-3)-β-d-Glc1-OMe disaccharides and the branched title trisaccharide were examined in DMSO-d6 solution by 1H-nmr. The distance mapping procedure was based on rotating frame nuclear Overhauser effect (NOE) constraints involving C- and O-linked protons, and hydrogen-bond constraints manifested by the splitting of the OH nmr signals for partially deuteriated samples. An “isotopomer-selected NOE” method for the unequivocal identification of mutually hydrogen-bonded hydroxyl groups was suggested. The length of hydrogen bonds thus detected is considered the only one motionally nonaveraged nmr-derived constraint. Molecular mechanics and molecular dynamics methods were used to model the conformational properties of the studied oligosaccharides. Complex conformational search, relying on a regular Φ,Ψ-grid based scanning of the conformational space of the selected glycosidic linkage, combined with simultaneous modeling of different allowed orientations of the pendant groups and the third, neighboring sugar residue, has been carried out. Energy minimizations were performed for each member of the Φ,Ψ grid generated set of conformations. Conformational clustering has been done to group the minimized conformations into families with similar values of glycosidic torsion angles. Several stable syn and anti conformations were found for the 1→2 and 1→3 bonds in the studied disaccharides. Vicinal glycosylation affected strongly the occupancy of conformational states in both branches of the title trisaccharide. The preferred conformational family of the trisaccharide (with average Φ,Ψ values of 38°, 17° for the 1→2 and 48°, 1° for the 1→3 bond, respectively) was shown by nmr to be stabilized by intramolecular hydrogen bonding between the nonbonded Rha and Gal residues. © 1998 John Wiley & Sons, Inc. Biopoly 46: 417-432, 1998
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  • 45
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    Biopolymers 46 (1998), S. 489-492 
    ISSN: 0006-3525
    Keywords: refractive index increment ; proteins ; solvent ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The refractive index increment of a protein solution is a property not only of the protein, but also of the solvent. This is demonstrated theoretically and confirmed experimentally using analytical interferometry. © 1998 John Wiley & Sons, Inc. Biopoly 46: 489-492, 1998
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  • 46
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    Biopolymers 47 (1998), S. 1-1 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No abstract.
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  • 47
    ISSN: 0006-3525
    Keywords: hepatitis A ; synthetic peptides ; CD ; liposomes ; computational study ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The present study was undertaken to examine the structural features that may be important to explain the immunogenicity of the (110-121) peptide sequence (FWRGDLVFDFQV) of VP3 capsid protein of hepatitis A virus. A conformational analysis of the preferred conformations by CD and molecular mechanics was carried out. Present results suggest that the interaction with liposomes as biomembrane model induces and stabilizes the amphipathic β-structure of the peptide.To study the contribution of amino acid replacements at the RGD tripeptide as well as the influence of the peptide chain length on peptide conformation, solid-phase peptide synthesis of several peptide analogs was carried out and the peptide conformation was studied using CD spectroscopy. The results show that the RGD sequence is necessary to induce the β-structure in the presence of liposomes. © 1998 John Wiley & Sons, Inc. Biopoly 45: 479-492, 1998
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  • 48
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    Biopolymers 46 (1998), S. 31-37 
    ISSN: 0006-3525
    Keywords: DNA liquid crystals ; DNA fragments ; screened Coulomb interactions ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The critical volume fractions pertaining to the formation of DNA liquid crystals were obtained from polarization microscopy, 31P-nmr, and phase separation experiments. The DNA length (approximately one to two times the persistence length 50 nm), ionic strength, and counterion variety dependencies are reported. The cholesteric-isotropic transition is interpreted in terms of the coexistence equations, which are derived from the solution free energy including orientational entropy and excluded volume effects. With the wormlike chain as reference system, the electrostatic contribution to the free energy is evaluated as a thermodynamic perturbation in the second virial approximation with a Debye-Hückel potential of mean force. The hard core contribution has been evaluated with scaled particle theory and/or a simple generalization of the Carnahan-Starling equation of state for hard spheres. For sufficiently high ionic strengths, the agreement is almost quantitative. At lower amounts of added salt deviations are observed, which are tentatively attributed to counterion screening effects. The contour length dependence agrees with a DNA persistence length 50 nm. © 1998 John Wiley & Sons, Inc. Biopoly 46: 31-37, 1998
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  • 49
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    Biopolymers 46 (1998), S. 245-252 
    ISSN: 0006-3525
    Keywords: gelatin ; gelation ; atomic force microscopy ; interfacial rheology ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Gelation of gelatin under various conditions has been followed by atomic force microscopy (AFM) with the objective of understanding more fully the structure formed during the gelation process. AFM images were obtained of the structures formed from both the bulk sol and in surface films during the onset of gelation. While gelation occurred in the bulk sol, the extent of helix formation was monitored by measurements of optical rotation, and the molecular aggregation was imaged by AFM. Interfacial gelatin films formed at the air-water interface were also studied. Measurements of surface tension and surface rheology were made periodically and Langmuir-Blodgett films were drawn from the interface to allow AFM imaging of the structure of the interfacial layer as a function of time. Structural studies reveal that at low levels of helical content the gelatin molecules assemble into aggregates containing short segments of dimensions comparable to those expected for gelatin triple helices. With time larger fibrous structures appear whose dimensions suggest that they are bundles of triple helices. As gelation proceeds, the number density of fibers increases at the expense of the smaller aggregates, eventually assembling into a fibrous network. The gel structure appears to be sensitive to the thermal history, and this is particularly important in determining the structure and properties of the interfacial films. © 1998 John Wiley & Sons, Inc. Biopoly 46: 245-252, 1998
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  • 50
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    Biopolymers 48 (1998), S. 65-81 
    ISSN: 0006-3525
    Keywords: nucleotide analogue interference mapping ; phosphorothioate ; group I intron ; interference suppression ; RNA ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In this review I will outline several chemogenetic approaches used to determine the chemical basis of large ribozyme function and structure. The term chemogenetics was first used to describe site-specific functional group modification experiments in the analysis of DNA-protein interactions. Within the past few years equivalent experiments have been performed on large catalytic RNAs using both single-site substitution and interference mapping techniques with nucleotide analogues. While functional group mutagenesis is an important aspect of a chemogenetic approach, chemical correlates to genetic revertants and suppressors must also be realized for the genetic analogy to be intellectually valid and experimentally useful. Several examples of functional group revertants and suppressors have now been obtained within the Tetrahymena group I ribozyme. These experiments define an ensemble of tertiary hydrogen bonds that have made it possible to construct a detailed model of the ribozyme catalytic core. The model includes a functionally important monovalent metal ion binding site, a wobble-wobble receptor motif for helix-helix packing interactions, and a minor groove triple helix. © 1998 John Wiley & Sons, Inc. Biopoly 48: 65-81, 1998
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  • 51
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    Biopolymers 48 (1998), S. 83-96 
    ISSN: 0006-3525
    Keywords: nucleic acid ; disulfide cross-link ; structure ; dynamics ; stability ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In this review I discuss straightforward and general methods to modify nucleic acid structure with disulfide cross-links. A motivating factor in developing this chemistry was the notion that disulfide bonds would be excellent tools to probe the structure, dynamics, thermodynamics, folding, and function of DNA and RNA, much in the way that cystine cross-links have been used to study proteins. The chemistry described has been used to synthesize disulfide cross-linked hairpins and duplexes, higher order structures like triplexes, nonground-state conformations, and tRNAs. Since the cross-links form quantitatively by mild air oxidation and do not perturb either secondary or tertiary structure, this modification should prove quite useful for the study of nucleic acids. © 1998 John Wiley & Sons, Inc. Biopoly 48: 83-96, 1998
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  • 52
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    Biopolymers 48 (1998), S. 113-135 
    ISSN: 0006-3525
    Keywords: divalent cations ; magnesium ; RNA ; ion binding ; RNA folding ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Divalent cations, like magnesium, are crucial for the structural integrity and biological activity of RNA. In this article, we present a picture of how magnesium stabilizes a particular folded form of RNA. The overall stabilization of RNA by Mg2+ is given by the free energy of transferring RNA from a reference univalent salt solution to a mixed salt solution. This term has favorable energetic contributions from two distinct modes of binding: diffuse binding and site binding. In diffuse binding, fully hydrated Mg ions interact with the RNA via nonspecific long-range electrostatic interactions. In site binding, dehydrated Mg2+ interacts with anionic ligands specifically arranged by the RNA fold to act as coordinating ligands for the metal ion. Each of these modes has a strong coulombic contribution to binding; however, site binding is also characterized by substantial changes in ion solvation and other nonelectrostatic contributions. We will show how these energetic differences can be exploited to experimentally distinguish between these two classes of ions using analyses of binding polynomials. We survey a number of specific systems in which Mg2+-RNA interactions have been studied. In well-characterized systems such as certain tRNAs and some rRNA fragments these studies show that site-bound ions can play an important role in RNA stability. However, the crucial role of diffusely bound ions is also evident. We emphasize that diffuse binding can only be described rigorously by a model that accounts for long-range electrostatic forces. To fully understand the role of magnesium ions in RNA stability, theoretical models describing electrostatic forces in systems with complicated structures must be developed. © 1999 John Wiley & Sons, Inc. Biopoly 48: 113-135, 1998
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  • 53
    ISSN: 0006-3525
    Keywords: 1H-nmr ; molecular modeling ; peptaibol ; peptide-lipid interaction ; sodium dodecyl sulfate micelles ; trichorzianin TA VII ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Trichorzianin TA VII, Ac0 U1 A2 A3 U4 J5 Q6 U7 U8 U9 S10 L11 U12 P13 V14 U15 I16 Q17 Q18 Fol19, is a nonadecapeptide member of the peptaibol antibiotics biosynthesized by Trichoderma soil fungi, which is characterized by a high proportion of the α,α-dialkylated amino acids, α-aminoisobutyric acid (Aib, U) and isovaline (Iva, J), an acetylated N-terminus and a C-terminal phenylalaninol (Pheol, Fol). The main interest in such peptides stems from their ability to interact with phospholipid bilayers and form voltage-dependent transmembrane channels in planar lipid bilayers. In order to provide insights into the lipid-peptide interaction promoting the voltage gating, the conformational study of TA VII in the presence of perdeuterated sodium dodecyl sulfate (SDS-d25) micelles has been carried out. 1H sequential assignments have been performed with the use of two-dimensional homo- and -heteronuclear nmr techniques including double quantum filtered correlated spectroscopy, homonuclear Hartmann-Hahn, nuclear Overhauser effect spectroscopy, 1H-13C heteronuclear single quantum correlation, and heteronuclear multiple bond correlation. Conformational parameters, such as 3JNHCαH coupling constants, temperature coefficients of amide protons (Δδ/ΔTNH) and quantitative nuclear Overhauser enhancement data, lead to detailed structural information. Ninety-eight three-dimensional structures consistent with the nmr data were generated from 231 interproton distances and six Φ dihedral angle restraints, using restrained molecular dynamics and energy minimization calculations. The average rms deviation between the 98 refined structures and the energy-minimized average structure is 0.59 Å for the backbone atoms. The structure of trichorzianin TA VII associated with SDS micelles, as determined by these methods, is characterized by two right-handed helical segments involving residues 1-8 and 11-19, linked by a β-turn that leads to an angle about 90°-100° between the two helix axes; residues 18 and 19 at the end of the C-terminal helix exhibit multiple conformations. © 1998 John Wiley & Sons, Inc. Biopoly 46: 75-88, 1998
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  • 54
    ISSN: 0006-3525
    Keywords: 9-hydroxyellipticine ; DNA ; CD ; linear dichroism ; resonance light scattering ; intercalation ; drug-drug interactions ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The binding of 9-hydroxyellipticine to calf thymus DNA, poly[d(A-T)]2, and poly-[d(G-C)]2 has been studied in detail by means of CD, linear dichroism, resonance light scattering, and molecular dynamics. The transition moment polarizations of 9-hydroxyelliptiycine were determined in polyvinyl alcohol stretched film. Spectroscopic solution studies of the DNA/drug complex are combined with theoretical CD calculations using the final 50 ps of a series of molecular dynamics simulations as input. The spectroscopic data shows 9-hydroxyellipticine to adopt two main binding modes, one intercalative and the other a stacked binding mode involving the formation of drug oligomers in the DNA major groove. Analysis of the intercalated binding mode in poly[d(A-T)]2 suggests the 9-hydroxyellipticine hydroxyl group lies in the minor groove and hydrogen bonds to water with the pyridine ring protruding into the major groove. The stacked binding mode was examined using resonance light scattering and it was concluded that the drug was forming small oligomer stacks rather than extended aggregates. Reduced linear dichroism measurements suggested a binding geometry that precluded a minor groove binding mode where the plane of the drug makes a 45° angle with the plane of the bases. Thus it was concluded that the drug stacks in the major groove. No obvious differences in the mode of binding of 9-hydroxyellipticine were observed between different DNA sequences; however, the stacked binding mode appeared to be more favorable for calf thymus DNA and poly[d(G-C)]2 than for poly[d(A-T)]2, an observation that could be explained by the slightly greater steric hindrance of the poly[d(A-T)]2 major groove. A strong concentration dependence was observed for the two binding modes where intercalation is favored at very low drug load, with stacking interactions becoming more prominent as the drug concentration is increased. Even at DNA : drug mixing ratios of 70:1 the stacked binding mode was still important for GC-rich DNAs. © 1998 John Wiley & Sons, Inc. Biopoly 46: 127-143, 1998
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  • 55
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    Biopolymers 46 (1998), S. 169-179 
    ISSN: 0006-3525
    Keywords: macromolecular carriers ; drug targeting and delivery ; branched chain synthetic polypeptides ; membrane-synthetic polypeptide interaction ; lipid monolayers/bilayers ; polymer therapeutics ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The surface properties at the air/water interface and the interaction of branched chain polymeric polypeptides with a general formula poly[Lys-(DL-Alam-X1)], where X = Π (AK), Ser (SAK), or Glu (EAK), with phospholipids were investigated. Polylysine derivatives with polycationic (SAK, AK) or amphoteric (EAK) were capable to spread and form stable monomolecular layers. The stability of monolayers at the air/water interface was dependent on the side-chain terminal amino acid residue of polymers and can be described by SAK 〈 AK 〈 EAK order. The area per amino acid residue values calculated from compression isotherms were in the same range as compared to those of linear poly-α-amino acids and proteins. Moreover, these polymers interact with phospholipid monomolecular layers composed of dipalmitoyl phosphatidyl choline (DPPC) or DPPC/PG (PG: phosphatidyl glycerol; 95/5, mol/mol). Data obtained from compression isotherms of phospholipids spread on aqueous polymer solutions at different initial surface pressure indicated that insertion into lipid monolayers for SAK or AK is more pronounced than for EAK. The interaction between branched polypeptides and phospholipid membranes was further investigated using lipid bilayers with DPPC/PG and fluorescent probes located either at the polar surface [1-(4-trimethylammonium-phenyl)-6-phenyl-1,3,5-hexatriene (TMA-DPH) sodium anilino naphthalene sulfonate (ANS)] or within the hydrophobic core (DPH) of the liposome. Changes in fluorescence intensity and in polarization were observed when TMA-DPH or ANS, but not DPH were used. Comparative data also indicate that all three polymers interact only with the outer surface of the bilayer, but even the most marked penetration of polycationic polypeptide (SAK) did not result in alteration of the ordered state of the alkyl chains in the bilayer. Taken together, data obtained from mono- or bilayer experiments suggest that the interaction between branched polymers and phospholipids are highly dependent on the charge properties (Ser vs Glu) and on the identity (Ser vs Ala) of side-chain terminating amino acids. The binding of polymers to the model membranes could be mainly driven by electrostatic forces, but the significant role of hydrophilic properties in case of SAK cannot be excluded. © 1998 John Wiley & Sons, Inc. Biopoly 46: 169-179, 1998
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  • 56
    ISSN: 0006-3525
    Keywords: Cα,α-dialkylated glycines ; molecular dynamics ; geometry and conformation ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The relationship between the local backbone conformation and bond angles at Cα of symmetrically substituted Cα,α-dialkylated glycines (Cα,α-dimethylglycine or α-aminoisobutyric acid, Aib; Cα,α-diethylglycine, Deg; Cα,α-di-n-propylglycine, Dpg) has been investigated by molecular dynamics (MD) simulation adopting flat bottom harmonic potentials, instead of the usual harmonic restraints, for the Cα bond angles. The MD simulations show that the Cα bond angles are related to the local backbone conformation, irrespectively of the side-chain length of Aib, Deg, and Dpg residues. Moreover, the N-Cα-C′ (τ) angle is the most sensitive conformational parameter and, in the folded form, is always larger and more flexible than in the extended one. © 1998 John Wiley & Sons, Inc. Biopoly 46: 239-244, 1998
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  • 57
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    Biopolymers 46 (1998), S. 319-327 
    ISSN: 0006-3525
    Keywords: methionine ligation ; parathyroid hormones ; biomimetic ligation ; S-methylation ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In biological systems, both proteolysis and aminolysis of amide bonds produce activated intermediates through acyl transfer reactions either inter- or intramolecularly. Protein splicing is an illustrative example that proceeds through a series of catalyzed acyl transfer reactions and culminates at an O- or S-acyl intermediate. This intermediate leads to an uncatalyzed acyl migration to form an amide bond in the spliced product. A ligation method mimicking the uncatalyzed final steps in protein splicing has been developed utilizing the acyl transfer amide-bond feature for the blockwise coupling of unprotected, free peptide segments at methionine (Met). The latent thiol moiety of Met can be exploited using homocysteine at the α-amino terminal position of a free peptide for transthioesterification with another free peptide containing an α-thioester to give an S-acyl intermediate. A subsequent, proximity-driven S- to N-acyl migration of this acyl intermediate spontaneously rearranges to form a homocysteinyl amide bond. S-methylation with excess p-nitrobenezensulfonate yields Met at the ligation site. The methionine ligation is selective and orthogonal, and is usually completed within 4 h when performed at slightly basic pH and under strongly reductive conditions. No side reactions due to acylation were observed with any other α-amines of both peptide segments as seen in the synthesis of parathyroid hormone peptides. Furthermore, cyclic peptide can also be obtained through the same strategy by placing both homocysteine at the amino terminus and the thioester at the carboxyl terminus in an unprotected peptide precursor. These biomimetic ligation strategies hold promise for engineering novel peptides and proteins. © 1998 John Wiley & Sons, Inc. Biopoly 46: 319-327, 1998
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  • 58
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    Biopolymers 46 (1998), S. 359-373 
    ISSN: 0006-3525
    Keywords: boundary element method ; DNA electrophoresis ; electrophoretic mobility of DNA ; free solution electrophoretic mobility of DNA ; ion relaxation, DNA electrophoresis ; modeling electrophoresis of polyions ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Boundary element methods are used to model the free solution electrophoretic mobility of short DNA fragments. The Stern surfaces of the DNA fragments are modeled as plated cylinders that reproduce translational and rotational diffusion constants. The solvent-accessible and ion-accessible surfaces are taken to be coincident with the Stern surface. The mobilities are computed by solving simultaneously the coupled Navier-Stokes, Poisson, and ion-transport equations. The equilibrium electrostatics are treated at the level of the full Poisson-Boltzmann equation and ion relaxation is included. For polyions as highly charged as short DNA fragments, ion relaxation is substantial. At .11 M KCl, the simulated mobilities of a 20 base pair DNA fragment are in excellent agreement with experiment. At .04 M Tris acetate, pH = 8.0, the simulated mobilities are about 10-15% higher than experimental values and this discrepancy is attributed to the relatively large size of the Tris counterion. The length dependence of the mobility at .11 M KCl is also investigated. Earlier mobility studies on lysozyme are reexamined in view of the present findings. In addition to electrophoretic mobilities, the effective polyion charge measured in steady state electrophoresis and its relationship to the preferential interaction parameter γgG is briefly considered. © 1998 John Wiley & Sons, Inc. Biopoly 46: 359-373, 1998
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  • 59
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    Biopolymers 45 (1998), S. 341-346 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No abstract.
    Additional Material: 5 Ill.
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  • 60
    ISSN: 0006-3525
    Keywords: diffusional encounter ; Brownian dynamics ; average Boltzmann factor ; acetylcholinesterase ; Poisson-Boltzmann ; electrostatics ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The utility of the average Boltzmann factor around the active site of an enzyme as the predictor of the electrostatic enhancement of the substrate binding rate is tested on a set of data on wild-type acetylcholinesterase and 18 charge mutants recently obtained by Brownian dynamics simulations. A good correlation between the average Boltzmann factors and the substrate binding rate constants is found. The effects of single charge mutations on both the Boltzmann factor and the substrate binding rate constant are modest, i.e., 〈5 fold increase or decrease. This is consistent with the experimental results of Shafferman et al. but does not support their suggestion that the overall rate of the catalytic reaction is not limited by the diffusional encounter of acetylcholinesterase and its substrate. © 1998 John Wiley & Sons, Inc. Biopoly 45: 355-360, 1998
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  • 61
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    Biopolymers 45 (1998), S. 469-478 
    ISSN: 0006-3525
    Keywords: molecular dynamics ; hydrated proteins ; crystal structures ; density distributions ; globular proteins ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Using molecular dynamics simulations of fully hydrated proteins and analysis of crystal structures contained in the Protein Data Bank, we develop a transferable set of perpendicular radial distribution functions for water molecules around globular proteins. These universal functions may be used to reconstruct the unique three-dimensional solvent density distribution around every individual protein with a modest error. We discuss potential applications of this solvent treatment in protein x-ray crystallographic refinements and in theoretical modeling. We also present a fast, grid-based algorithm for construction of the perpendicular solvent density distributions. © 1998 John Wiley & Sons, Inc. Biopoly 45: 469-478, 1998
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  • 62
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    Biopolymers 47 (1998), S. 23-29 
    ISSN: 0006-3525
    Keywords: independently folded polypeptide motifs ; miniproteins ; natural target domains ; BBA motif ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In this paper we present a redesign strategy for the development of uniquely folded polypeptide motifs of less than 40 residues. These mini proteins are based on natural target domains, including the zinc finger domains (BBA motif) Nomenclature corresponds to the defined elements of secondary structure, beginning at the N-terminus of the peptide. Roman lettering refers to a specific motif while Greek characters correspond to the elements of secondary structure within that motif. and the disulfide-rich snake and scorpion toxins (BBB motif). These motifs are designed to act as the molecular framework for the construction of novel functional polypeptides. We will explore the structural determinants of the folded BBA motif, inspired by the zinc finger peptides, in relation to the redesign process. © 1998 John Wiley & Sons, Inc. Biopoly 47: 23-29, 1998
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  • 63
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    Biopolymers 47 (1998), S. 75-81 
    ISSN: 0006-3525
    Keywords: ion channel ; synthetic peptide ; de novo design ; template-assembled synthetic proteins ; supramolecular assembly ; membrane protein ; planer lipid bilayers ; amphiphilic peptide ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: To create ion channel function by synthetic peptides is a challenge in the de novo design of artificial membrane proteins. Amphiphilic α-helical motifs of ∼ 20 amino acid residues to span lipid bilayers are most often used for the creation of peptide ion channels. Template molecules to tether helical peptides have been employed to obtain more organized pore structures. Approaches to form molecular assembly of peptides in the membranes by hydrogen bonding have been also investigated. We have developed approaches to assemble helices with individual amino acid sequences to construct artificial helical proteins. Using one of these approaches, four helices corresponding to the voltage sensor segments (S4 in repeat I-IV) of the sodium channel were assembled on a peptide template to give a protein having ion channel activity with rectification. © 1998 John Wiley & Sons, Inc. Biopoly 47: 75-81, 1998
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  • 64
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    Biopolymers 47 (1998), S. 127-142 
    ISSN: 0006-3525
    Keywords: collagen mimetics ; triple helix ; peptoid ; template ; biophysics ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Collagen peptidomimetics have been synthesized as an alternative to natural collagen. The incorporation of unnatural residues such as peptoids in the collagen sequences can demonstrate potent and specific biological activity and enhance the biostability against enzymatic degradation. Furthermore, the use of achiral peptoids simplifies synthetic strategies by reducing racemization problems. The peptoid residue N-isobutylglycine (Nleu) has been successfully incorporated into a series of collagen mimetics composed of Gly-Pro-Nleu, Gly-Nleu-Pro, and Gly-Nleu-Nleu. The discovery of template-assembled collagen mimetics and metal binding ability has laid the foundation for new opportunities in the design of novel collagen mimetic complexes. This review summarizes the synthesis and integrated biophysical analyses of the structures of these collagen mimetics. Solid phase segment condensation techniques have been utilized for the synthesis of the single chain and template-assembled analogues. The characterization of the collagen-like structures has been established by temperature-dependent optical rotation measurements, CD, NMR spectroscopy, and molecular modelling simulations. © 1998 John Wiley & Sons, Inc. Biopoly 47: 127-142, 1998
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  • 65
    ISSN: 0006-3525
    Keywords: non-natural amino acid ; peptide ; squarylium dye ; thin film ; poly(3-methylthiophene) ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We designed a polypeptide that behaves as a photodevice by using a non-natural amino acid with replacement of an α-hydrogen by a squarylium dye and succeeded in syntheses of the non-natural amino acid derivative containing a squarylium and its peptide with trialanine Ala-Ala-Ala. Strong dye-dye interactions were confirmed by absorption and CD spectra for the peptide in 2,2,2-trifluoroethanol solution and in water suspension. The non-natural amino acid derivative could be deposited onto a PMeT/Au electrode by the micelle disruption method. © 1998 John Wiley & Sons, Inc. Biopoly 47: 179-183, 1998
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  • 66
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    Biopolymers 47 (1998), S. 263-263 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No abstract.
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  • 67
    ISSN: 0006-3525
    Keywords: electrostatically driven Monte Carlo method ; cluster analysis ; global energy minimum ; perturbed conformations ; conformational space ; lowest energy conformations ; polypeptide chain ; melittin, membrane-bound portion ; Empirical Conformational Energy Program for Peptides 3 ; annealing methods ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The electrostatically driven Monte Carlo (EDMC) method has been greatly improved by adding a series of new features, including a procedure for cluster analysis of the accepted conformations. This information is used to guide the search for the global energy minimum. Alternative procedures for generating perturbed conformations to sample the conformational space were also included. These procedures enhance the efficiency of the method by generating a larger number of low-energy conformations.The improved EDMC method has been used to explore the conformational space of a 20-residue polypeptide chain whose sequence corresponds to the membrane-bound portion of melittin. The ECEPP/3 (Empirical Conformational Energy Program for Peptides) algorithm was used to describe the conformational energy of the chain. After an exhaustive search involving 14 independent runs, the lowest energy conformation (LEC) (-91.0 kcal/mol) of the entire study was encountered in four of the runs, while conformations higher in energy by no more than 1.8 kcal/mol were found in the remaining runs with the exception of one of them (run 8). The LEC is identical to the conformation found recently by J. Lee, H.A. Scheraga, and S. Rackovsky [(1998) “Conformational Analysis of the 20-Residue Membrane-Bound Portion of Melittin by Conformational Space Annealing,” Biopolymers, Vol. 46, pp. 103-115] as the lowest energy conformation obtained in their study using the conformational space annealing method. These results suggest that this conformation corresponds to the global energy minimum of the ECEPP/3 potential function for this specific sequence; it also appears to be the conformation of lowest free energy. © 1998 John Wiley & Sons, Inc. Biopoly 46: 117-126, 1998
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  • 68
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    Biopolymers 46 (1998), S. 195-200 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No abstract.
    Additional Material: 3 Ill.
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  • 69
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    Biopolymers 46 (1998), S. 201-214 
    ISSN: 0006-3525
    Keywords: band broadening ; dispersion ; DNA ; gels ; electrophoresis ; fluorescence recovery ; photobleaching ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We determined quantitatively the band broadening effect during gel electrophoresis by measuring the longitudinal dispersion coefficient Dx, with a fluorescence recovery after photobleaching setup, coupled to an electrophoretic cell. We carried out measurements as a function of the electric field, the average pore size, and the molecular length of DNA fragments. Our results are in good agreement with the predictions of the biased reptation model with fluctuations described by T. A. Duke et al. [(1992) Physics Review Letters, vol. 69, pp. 3260-3263]. This agreement is observed on single-stranded DNA [persistence length ≅ 4 nm; B. Tinland et al. (1997) Macromolecules, vol. 30, pp. 5763-5765] in polyacrylamide gels and on double-stranded DNA (persistence length ≅ 50 nm) in agarose gels, two systems where the ratio between the average pore size and the Kuhn length is larger than 1. © 1998 John Wiley & Sons, Inc. Biopoly 46: 201-214, 1998
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  • 70
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    Biopolymers 46 (1998), S. 403-415 
    ISSN: 0006-3525
    Keywords: molecular dynamics ; DNA curvature ; DNA flexibility ; TATA box functionality ; TATA box binding protein (TBP) ; TBP recognition ; TBP binding ; TBP transcriptional activation ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Four 1.5 ns molecular dynamics (MD) simulations were performed on the d(GCTATAAAAGGG) · d(CCCTTTTATAGC) double helix dodecamer bearing the Adenovirus major late promoter TATA element and three iso-composition mutants for which physical and biochemical data are available from the same laboratory. Three of these DNA sequences experimentally induce tight binding with the TATA box binding protein (TBP) and induce high transcription rates; the other DNA sequence induces much lower TBP binding and transcription. The x-ray crystal structures have previously shown that the duplex DNA in DNA-TBP complexes are highly bent. We performed and analyzed MD simulations for these four DNAs, whose experimental structures are not available, in order to address the issue of whether inherent DNA structure and flexibility play a role in establishing these observed preferences. A comparison of the experimental and simulated results demonstrated that DNA duplex sequence-dependent curvature and flexibility play a significant role in TBP recognition, binding, and transcriptional activation. © 1998 John Wiley & Sons, Inc. Biopoly 46: 403-415, 1998
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  • 71
    ISSN: 0006-3525
    Keywords: vibrational CD ; solution conformation ; alanine oligopeptides ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The solution conformation of a number of small, linear alanine oligomers was investigated via ir (or vibrational) CD (VCD). We find that these oligopeptides assume distinct solution conformations that depend primarily on chain lengths, and to a lesser degree on temperature, ionic strength, and pH. As expected, the longer chain oligomers exhibit more distinct VCD features and, presumably, more stable solution structures. At the level of the hexamer, however, aggregation of the peptide occurs. The fast time scale of VCD allows solution structures to be detected that may not be observable using slower techniques such as various forms of nmr spectroscopy. The VCD results reported here confirm that it is generally possible to obtain conformational information for small, linear homo- and heterooligopeptides via VCD spectroscopy. In this respect, the sensitivity of VCD is similar to that of electronic CD. Furthermore, the temperature dependence of the VCD results indicate that at elevated temperatures, the increasing number of conformational states results in a loss of discernible conformers, and consequently, a broadening and weakening of the VCD features. © 1998 John Wiley & Sons, Inc. Biopoly 46: 455-463, 1998
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  • 72
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    Biopolymers 47 (1998), S. 5-22 
    ISSN: 0006-3525
    Keywords: hemoproteins ; model systems ; miniaturized proteins ; mimochromes ; helix structures ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The present paper highlights and reviews current research in the field of hemoprotein models. Hemoproteins have been extensively studied in order to understand structure-function relationships, and to design new molecules with desired functions. A wide number of synthetic analogues have been developed, using quite different approaches. They differ in molecular structures, ranging from simple meso-substituted tetraaryl-metalloporphyrins and peptide-porphyrin conjugates.In this paper we summarize the state of the art on peptide based hemoprotein models. We also report here the approach used by us to develop a new class of molecules, named mimochromes. They can be regarded as miniaturized hemoproteins, because mimochromes are low molecular weight compounds with some structural and functional properties common to those of the parent high molecular weight protein. The basic structure of mimochromes is a deuteroporphyrin ring covalently linked to two helical peptide chains. Two molecules of this series have been fully characterized. All the information derived from their structural analysis has been applied to the design of new analogues with additional functions. © 1998 John Wiley & Sons, Inc. Biopoly 47: 5-22, 1998
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  • 73
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    Biopolymers 46 (1998), S. 503-516 
    ISSN: 0006-3525
    Keywords: discrete charge model of DNA ; dielectric cylinder in water ; effective dielectric constant ; salt effects ; Debye shielding factor ; potential variations in DNA surface ; Boltzmann averaged bending angles ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We have studied electrostatic properties of DNA with a discrete charge model consisting of a cylindrical dielectric core with a radius of 8 Å and a dielectric constant Di = 4, surrounded by two helical strings of phosphate point charges at 10 Å from the axis, immersed in an aqueous medium with dielectric constant Dw = 78.54. Eliminating the dielectric core makes potentials in the phosphate surface less negative by about 0.5 kT/e. Salt effects are evaluated for the model without a dielectric core, using the shielded Coulomb potential. Smearing the phosphate charges increases their potential by about 2.5 kT/e, due mostly to the self-potential of the smeared charge. Potentials in the center of the minor and major grooves vary less than 0.02 kT/e along their helical path. The potential in the center of the minor groove is from 1.0 to 1.7 kT/e, more negative than in the center of the major groove, depending on dielectric core and salt concentration. So multivalent cations and also larger cationic ligands, such as some antibiotics, are likely to adsorb in the minor groove, in agreement with earlier computations by A. and B. Pullman. Dielectric effects on the surface potential and the local potential variations are found to be relatively small. Bending of DNA is studied by placing a multivalent cation, MZ+, in the center of the minor or major groove, curving DNA around it for a certain length, and calculating the free energy difference between the bent and the straight configuration. Boltzmann averaged bending angles, 〈β〉, are found to be maximal in 0.03M monovalent salt, for a length of about 50 or 25 Å of curved DNA when an MZ+ ion is adsorbed in the minor or the major groove, respectively. When the dielectric constant of water is used throughout the calculation, we find maximal bends of 〈β〉 = 11° for M2+ and 〈β〉 = 16° for M3+ in the minor groove, 〈β〉 = 13° for M3+ in the major groove. The absence of bends in DNA adsorbed to mica in the presence of Mg salts supports the role of Mg2+ in “ion bridging” between DNA and mica. The treatment of the effective dielectric constant between two points outside a dielectric cylinder in water is appended. © 1998 John Wiley & Sons, Inc. Biopoly 46: 503-516, 1998
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  • 74
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    Biopolymers 47 (1998), S. 63-73 
    ISSN: 0006-3525
    Keywords: protein de novo design ; novel macromolecules ; topological templates ; Template Assembled Synthetic Proteins (TASP) ; biosensors ; protein folding ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The ultimate goal in protein de novo design is the creation of novel macromolecules with tailor-made receptor, sensory, and catalytic functions. Despite considerable progress in understanding basic rules of secondary structure formation and protein stability, the well-known protein folding problem is still far from being solved and, in general, only a limited number of designed proteins are folded uniquely. In this article the state-of-the-art in protein design is demonstrated on some selected examples, indicating that the construction of protein-like macromolecules mimicking some essential features of natural proteins seems to be within reach. Thus, protein design and mimicry has become an interdisciplinary challenge with most intriguing perspectives. © 1998 John Wiley & Sons, Inc. Biopoly 47: 63-73, 1998
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  • 75
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    Biopolymers 47 (1998), S. 451-463 
    ISSN: 0006-3525
    Keywords: bacteria ; antibiotics ; linear amphipathic α-helical antimicrobial peptides ; peptide-lipid interactions ; membrane permeation ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The increasing resistance of bacteria to conventional antibiotics resulted in a strong effort to develop antimicrobial compounds with new mechanisms of action. Antimicrobial peptides seem to be a promising solution to this problem. Many studies aimed at understanding their mode of action were described in the past few years. The most studied group includes the linear, mostly α-helical peptides. Although the exact mechanism by which they kill bacteria is not clearly understood, it has been shown that peptide-lipid interactions leading to membrane permeation play a role in their activity. Membrane permeation by amphipathic α-helical peptides can proceed via either one of the two mechanisms: (a) transmembrane pore formation via a “barrel-stave” mechanism; and (b) membrane destruction/solubilization via a “carpet-like” mechanism. The purpose of this review is to summarize recent studies aimed at understanding the mode of action of linear α-helical antimicrobial peptides. This review, which is focused on magainins, cecropins, and dermaseptins as representatives of the amphipathic α-helical antimicrobial peptides, supports the carpet-like rather the barrel-stave mechanism. That these peptides vary with regard to their length, amino acid composition, and net positive charge, but act via a common mechanism, may imply that other linear antimicrobial peptides that share the same properties also share the same mechanism. © 1999 John Wiley & Sons, Inc. Biopoly 47: 451-463, 1998
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  • 76
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    Biopolymers 48 (1998), S. 39-55 
    ISSN: 0006-3525
    Keywords: modified nucleotides ; site-specific probes ; RNA structure ; RNA function ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Modified nucleotides can be incorporated site specifically into RNA by the use of total chemical synthesis as well as by use of a variety of recombinant RNA techniques. The range of nucleotide analogues includes modifications to base, sugar, and phosphate for structure-function analysis and for cross-linking studies as well as to answer specific mechanistic questions in RNA catalysis. We describe how RNA containing site-specific modifications are prepared, concentrating in particular on routes involving chemically synthesized oligoribonucleotides, and give examples of their application in studies of the hammerhead and hairpin ribozymes. © 1998 John Wiley & Sons, Inc. Biopoly 48: 39-55, 1998
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  • 77
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    Biopolymers 48 (1998), S. 29-37 
    ISSN: 0006-3525
    Keywords: amide synthase ; catalytic antibodies ; Diels-Alderase ; ideal catalyst platform ; in vitro selection ; Lewis acid ; modified uridines ; modified RNA ; ribozymes ; SELEX ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In this manuscript the catalytic ability of RNA is examined and compared to other biopolymers. Despite having considerably fewer catalytically enabling properties when compared to proteins, the power of in vitro selection has allowed for RNA and DNA catalysts to be isolated. RNA catalysis has been expanded by incorporating modified bases to enrich the structural and functional diversity of RNA. Successful examples of new RNA chemistry using base modifications include carbon-carbon bond forming reactions and creation of highly specific active sites that are capable of recognizing small organic molecules without the need for nucleic acid templating or intercalation. In fact, the scope of functional modifications available for use in the RNA platform may eventually surpass those that are found in proteins and there are already hints that well chosen modifications allow nucleic acid catalysts to take advantage of mechanisms not available to selected protein catalysts for similar reactions. The chemical versatility of RNA is just emerging and future research directions will likely entail more creative methods for functional modification that will lead to new catalysts. © 1998 John Wiley & Sons, Inc. Biopoly 48: 29-37, 1998
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  • 78
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    New York : Wiley-Blackwell
    Biopolymers 48 (1998), S. 137-153 
    ISSN: 0006-3525
    Keywords: RNA ; pseudoknot ; Turnip Yellow Mosaic Virus ; Mouse Mammary Tumor Virus ; Beet Western Yellows Virus ; Simian Retrovirus type-1 ; Hepatitis Delta Virus ; translational frameshifting ; ribozyme ; nmr ; x-ray diffraction ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Recently, several high-resolution structures of RNA pseudoknots have become available. Here we review the progress in this area. The majority of the structures obtained belong to the classical or H-type pseudoknot family. The most complicated pseudoknot structure elucidated so far is the Hepatitis Delta Virus ribozyme, which forms a nested double pseudoknot. In particular, the structure-function relationships of the H-type pseudoknots involved in translational frameshifting have received much attention. All molecules considered show interesting new structural motifs. © 1999 John Wiley & Sons, Inc. Biopoly 48: 137-153, 1998
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  • 79
    ISSN: 1435-232X
    Keywords: Key words Tumor necrosis factor ; Dinucleotide repeat rheumatoid arthritis ; Obesity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Tumor necrosis factor alpha (TNFα) in activated monocytes exerts cytotoxic activity and has a variety of other biological effects. We isolated a polymorphic dinucleotide (CA) repeat sequence from a genomic clone containing the gene located at 6p21.3. High heterozygosity (0.80) makes this polymorphism a useful marker in the genetic study of disorders affecting immunological response and cell differentiation.
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  • 80
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    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 737-748 
    ISSN: 0887-624X
    Keywords: inverse microemulsion polymerization ; MADQUAT ; nucleation ; photopolymerization ; molecular weights ; flocculants ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The polymerization of inverse microemulsions of 2-methacryloyl oxyethyl trimethyl ammonium chloride stabilized by a blend of nonionic emulsifiers (a sorbitan sesquioleate and a sorbitan monooleate) and initiated by UV light in the presence of Azobis(isobutyronitrile) (AIBN) was investigated. The effect of initiator concentration, light intensity, emulsifier concentration, and dispersed phase weight fraction on the polymerization rate (Rp), number of polymer particles (Np), and polymer molecular weight (Mw) was studied. The application of this process to tubular reactors is discussed. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 737-748, 1998
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  • 81
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    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1217-1226 
    ISSN: 0887-624X
    Keywords: polypropylene ; pyrene ; two-solute system ; pulse radiolysis ; solute ionic species ; solute excited states ; low-temperature radiolysis ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A pulse radiolysis study of isotactic polypropylene (PP) film has been carried out with the main aims of investigating charge trapping in an undoped system and solute radical ion generation in an pyrene (Py) doped matrix. In PP, pulse radiolysis gives electron-positive hole pairs. The electron can be stabilized in the undoped system as a trapped electron, et-. The transient absorption spectrum of et- in the near-IR (up to 1800 nm) was observed in the temperature range 30-100 K. This IR absorption was not detected in the case of oxidized PP. In such a matrix electrons can be scavenged by oxidation products generating respective radical-anions (absorption in the UV RANGE, λ 〈 350 nm). In a doped matrix transient absorption bands centered at 450 and 500 nm were observed which can be assigned to the Py radical cation and anion, respectively. The recombination of these ionic species leads to monomer excited-state formation observed during and after the 17 ns pulse. Contrary to the Py-doped polyethylene no excimer emission was detected at room temperature even if Py content in PP was close to 0.02 mol dm-3. The rate of Py radical-ion decay was found to be temperature dependent. Two linear parts of the Arrhenius plot were observed which intersected at ca. 240 K, the glass transition temperature, Tg, for PP. The activation energies calculated for two parts of Arrhenius plot were equal to 111 and ca. 0.78 kJ mol-1 for T 〉 Tg and T 〈 Tg, respectively. Some preliminary results concerning the ionic processes in PP containing two solutes (Py, 3,3′-dimethyldiphenyl) were presented. The mechanism of ionic recombination in PP will be proposed and discussed. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1217-1226, 1998
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  • 82
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    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1345-1348 
    ISSN: 0887-624X
    Keywords: acid functional ; telechelic ; benzyl alcohol ; poly(ε-caprolactone) ; polymerization ; living ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 83
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    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 883-888 
    ISSN: 0887-624X
    Keywords: temperature sensitive ; particle ; emulsion polymerization ; morphology ; adsorption ; enzyme ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two kinds of temperature-sensitive composite polymer particles were prepared by seeded emulsion copolymerizations of (dimethylamino)ethyl methacrylate and ethylene glycol dimethacrylate with 0.14 μm-sized polystyrene and 0.26 μm-sized poly(methylmethacrylate) seed particles. To evaluate the usefulness as a carrier for biomolecules, the enzymatic activities of trypsin adsorbed on these two composite polymer particles were measured at temperatures above and below each lower critical solution temperature (LCST). In both cases, adsorbed trypsin retained its enzymatic activity during repeated adsorption/desorption measurements. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 883-888, 1998
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  • 84
    ISSN: 0887-624X
    Keywords: (1→6)-2,5-anhydro-D-glucitol ; HPLC ; optical resolution ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The cyclopolymerization of 3,4-di-O-allyl-1,2 : 5,6-dianhydro-D-mannitol (1) was carried out using BF3·OEt2 and t-BuOK. The polymer obtained by the polymerization with BF3·OEt2 mainly consisted of (1→6)-bonded 3,4-di-O-allyl-2,5-anhydro-D-glucitol as the five-membered constitutional repeating unit, though it contained a small amount of other cyclic repeating units. On the other hand, during the polymerization using t-BuOK, the stereoregular polymer (1→6)-linked 3,4-di-O-allyl-2,5-anhydro-D-glucitol (2) was synthesized via a regio- and stereoselective mechanism. Cleavage of the allyl ether linkage in polymer 2 occurred to produce the polymer consisting of only 2,5-anhydro-D-glucitol units, i.e., (1→6)-2,5-anhydro-D-glucitol (3). Chromatographic enantioseparation of chloroquine and tröger base has been performed on (3,5-dimethylphenyl)carbamate and 4-methylbenzoate derivatives of 3 as a chiral stationary phase for high-performance liquid chromatography. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 901-909, 1998
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  • 85
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    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 939-947 
    ISSN: 0887-624X
    Keywords: fluorine ; perfluoropolyether ; polyester ; segmented ; thermoplastic ; interfacial synthesis ; thermal transitions ; dynamic-mechanical properties ; chemical resistance ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Linear segmented polyesters containing soft perfluoropolyether (PFPE) and hard aromatic segments are obtained by an interfacial polycondensation reaction of an acyl chloride-ended fluorinated prepolymer with various aromatic diphenols in the presence of phase transfer catalysts (PTC) as accelerators. Experimental conditions for reaching high molecular weights are discussed. The calorimetric analysis (DSC) of all the polyesters synthesized shows a typical biphasic morphology, where a very low Tg (〈 -110°C) corresponding to the segregated PFPE moiety, is always accompanied by another Tg or a higher melting temperature, depending on the nature of the hard phase. Dynamic-mechanical analysis (DMA) has been carried out confirming the DSC results and suggesting diversified mechanical behaviors at the various temperatures in line with the amorphous or semicrystalline nature of the polymer. Chemical resistance was finally tested by dipping in several solvents and chemicals. The new polyesters show high contact angles, a moderate swelling in many organic solvents and excellent stability in aggressive hydrolytic environments. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 939-947, 1998
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  • 86
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    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1919-1928 
    ISSN: 0887-624X
    Keywords: emulsion polymerization ; vinylidene chloride ; kinetics ; sodium lauryl sulfate ; potassium persulfate ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Emulsion polymerization of vinylidene chloride was carried out at 50°C using sodium lauryl sulfate as emulsifier and potassium persulfate as initiator, respectively. Contrary to the results so far reported, the stirring rate did not affect the progress of the polymerization and such an abnormal kinetic behavior as the rate of polymerization suddenly drops in the course of polymerization was not observed. The number of polymer particles produced was proportional to the 0.7 power of the concentration of emulsifier forming micelles and to the 0.3 power of the initial initiator concentration, respectively, and was independent of the initial monomer concentration. The rate of polymerization was in proportion to the 0.3 power of the concentration of emulsifier forming micelles, to the 0.5 power of the initial initiator concentration, to the 0.2 power of the initial monomer concentration, and to the 0.45 power of the number of polymer particles, respectively. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1919-1928, 1998
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  • 87
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    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1961-1964 
    ISSN: 0887-624X
    Keywords: Poly(4,4′-phenylene-3,3′,4,4′-biphenyltetracarboxyimide) ; poly(4,4′-oxydiphenylenepyromellitimide) ; precursor solution ; aprotic polar solvent ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No abstract.
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  • 88
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    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1969-1972 
    ISSN: 0887-624X
    Keywords: hydrosilation ; polymer ; siloxane ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No abstract.
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  • 89
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    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1995-1999 
    ISSN: 0887-624X
    Keywords: poly-γ-D-glutamic acid ; biopolymer ; covalent modification ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Methods for the covalent modification in aqueous solution of poly-γ-D-glutamic acid from Bacillus licheniformis have been studied. Co-derivatization of a synthetic UV-absorbent amine and ethanolamine, using a water-soluble carbodi-imide coupling agent, yielded a water-soluble modified polymer. Derivatization of the polymer was accompanied by cleavage of the γ-linked polypeptide backbone, and a reduction in molecular mass from 170 to 10 kDa. A procedure was developed for the removal of noncovalently bound ligands by treatment with 5 M CaCl2. The polymer sidechains also reacted in aqueous solution with p-nitrophenyl acetate to form covalent linkages. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 1995-1999, 1998
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  • 90
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    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2037-2042 
    ISSN: 0887-624X
    Keywords: radical polymerization ; vinylcyclopropane ; vinylsilane ; desilylation ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and radical polymerization of novel vinylcyclopropanes; 1-carboethoxy-2-trimethylsilyl-2-vinylcyclopropane (1a) and 1-carboethoxy-2-(1-trimethylsilyl)-vinylcyclopropane (1b), were examined. 1a and 1b were prepared by the coupling reaction of 2-trimethylsilylbutadiene with ethyl diazoacetate, which was prepared from glycine ethyl ester hydrochloride. The radical polymerization of 1a and 1b was carried out at 60°C in bulk for 40 h in the presence of 2,2′-azobis(isobutyronitrile) (5 mol % vs. monomer). Poly(1) consisted of a 1,5-ring-opened unit. Desilylation reaction of poly(1) proceeded quantitatively in aqueous hydrochloric acid. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2037-2042, 1998
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  • 91
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    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2021-2027 
    ISSN: 0887-624X
    Keywords: 2,2′-bis(3,4-dicarboxyphenoxy)biphenyl dianhydride ; aromatic polyimides ; solubility ; thermal behavior ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new aromatic tetracarboxylic dianhydride having a crank and twisted noncoplannar structure, 2,2′-bis(3,4-dicarboxyphenoxy)biphenyl dianhydride, was synthesized by the reaction of 4-nitrophthalonitrile with biphenyl-2,2′-diol, followed by hydrolysis and cyclodehydration. The biphenyl-2,2′-diyl-containing aromatic polyimides having inherent viscosities up to 0.66 dL/g were obtained by the conventional two-step procedure starting from the dianhydride monomer and various aromatic diamines. Most of the polyimides were readily soluble in amide-type solvents such as N,N-dimethylacetamide and N-methyl-2-pyrrolidone. The aromatic polyimides had glass transition temperatures in the range of 205-242°C, and began to lose weight around 415°C, with 10% weight loss being recorded at about 500°C in air. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2021-2027, 1998
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  • 92
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    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2069-2079 
    ISSN: 0887-624X
    Keywords: Candida antarctica lipase ; Novozym 435® ; polyester ; enzymatic polymerization ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Preliminary enzymatic polymerization studies in the simple stoichiometric adipic acid/butane-1,4-diol system using lipase B from Candida antarctica, immobilized as Novozym 435®, suggest that in solvent-free conditions a step-growth mechanism operates involving the sequential addition of an AB synthon by esterification mode only. Conversely, in toluene as solvent there is a change to the more facile transesterification mode in line with the conventional polyesterification procedure, pointing to a change in specificity of the lipase. Evidence is drawn from qualitative studies using a series of synthetic intermediates, enabling authentication of product mixtures together with an indication of the comparative reactivity of species along the proposed reaction pathway. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2069-2080, 1998
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  • 93
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    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2111-2117 
    ISSN: 0887-624X
    Keywords: dendritic polymer ; blends ; coatings ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Hybrid blends of poly(amidoamine) PAMAM dendrimers with two linear high polymers, poly(vinyl chloride), PVC, and poly(vinyl acetate), PVAc, are reported. The interaction between the blend components was studied using dynamic mechanical analysis, xenon nuclear magnetic resonance (NMR) spectroscopy, and tensile property measurements. The data suggest a much higher degree of interaction between components of PVAc-containing blends compared to those containing PVC. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2111-2117, 1998
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  • 94
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    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2135-2146 
    ISSN: 0887-624X
    Keywords: SCLC polyurethanes ; azobenzene mesogenic group ; alkyl spacer ; bilayer smectic phases ; hydrogen bonding ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of side chain liquid crystal polyurethanes (CnCNPs), in which the spacer length was varied from 2 to 12 methylene units, were synthesized by the addition polymerization of α-[bis(2-hydroxyethyl)amino]-ω-(4-cyanoazobenzene-4′-oxy)alkanes (CnCN-diols) with hexamethylene diisocyanate. The liquid crystalline properties of CnCNPs were characterized by means of differential scanning calorimetry, polarizing optical microscopy, and X-ray diffraction. Polyurethanes with spacer length 4 or higher exhibited mesomophic properties. C4CNP and C5CNP exhibited an enantiotropic nematic mesophase, while C6-C12CNPs exhibited enantiotropic bilayer smectic mesophases. CnCNPs have a high tendency to crystallize; crystallization is kinetically controlled. Polyurethane's backbone crystallization is closely related to hydrogen bonding. To establish the role of hydrogen bonding in mesophase formation as well as crystallization, Fourier transform infrared spectroscopy studies of CnCNPs were carried out at different temperatures focusing on H-bonds between the N—H and C=O groups of the urethane backbone. With increasing temperature, C=O and N—H stretching bands were evenly shifted to higher wavenumbers, with two exceptions (C4CNP and C5CNP) discussed in detail in the text. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2135-2146, 1998
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  • 95
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    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2169-2176 
    ISSN: 0887-624X
    Keywords: free radical ; initiation ; styrene ; acrylonitrile ; copolymerization ; nitroxide trapping ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The competitive reactions of cyanoisopropyl radicals with the mixed monomers styrene and acrylonitrile have been investigated using the nitroxide radical trapping technique. When the trap concentration is kept low, second, third, and even fourth generation (in terms of successive monomer addition) carbon radicals have been observed as trapped products. The ratio of rate constants for the addition of styrene and acrylonitrile to cyanoisopropyl radicals is 2.7 at 75°C and 5.3 at 105°C. These values are compared with the ratios for reactions of these two monomers with a number of other radicals and discussed in terms of the polarities of the radicals and monomers. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2169-2176, 1998
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  • 96
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    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2193-2200 
    ISSN: 0887-624X
    Keywords: N-phenylated polyamides ; 4,4′-dianilinobiphenyl ; solubility ; thermal behavior ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New N-phenylated aromatic-aliphatic and all aromatic polyamides were prepared by the high-temperature solution polycondensation of 4,4′-dianilinobiphenyl with both aliphatic (methylene chain lengths of 6-11) and aromatic dicarboxylic acid chlorides. All of the aromatic-aliphatic polyamides and the wholly aromatic polyamides exhibited an amorphous nature and good solubility in amide-type and chlorinated hydrocarbon solvents, except for those aromatic polyamides containing p-oriented phenylene or biphenylylene linkages in the backbone; the latter were crystalline and insoluble in organic solvents except m-cresol. The N-phenylated aromatic-aliphatic polyamides and aromatic polyamides had glass transition temperatures in the range of 79-116°C and 207-255°C, respectively, and all the polymers were thermally stable with decomposition temperatures above 400°C in air. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2193-2200, 1998
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  • 97
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    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2237-2245 
    ISSN: 0887-624X
    Keywords: NMR ; polysiloxane, polysiloxane-block-polyimide ; solution imidization ; kinetic analysis ; structure analysis ; spin-lattice relaxation time ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of polysiloxane-block-polyimides were synthesized by solution imidization of the polyamic acids derived from the combination of 3,3′,4,4′-diphenylsulfonetetracarboxylic dianhydride (DSDA), 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP), and diamino(polysiloxane) (PSX (Mw = 750)) in N-methyl-2-pyrrolidone (NMP). Their structures were analyzed by 1H-, 13C-, and 29Si-NMR spectra as well as by IR spectroscopy. The solid-state NMR spectrum was also measured to determine the spin-lattice relaxation time of the copolyimides. The observed relaxation times of both aromatic and polysiloxane segments were similar in the copolyimides having 10-30 wt % of PSX, while those in the copolyimide with 50 wt % of PSX was significantly different. This may be attributed to the morphology change due to the increase in PSX composition in the polymer backbone. The reduced viscosity of the copolyimides could be controlled by changing the monomer ratio in the feed or by adding an end-capping reagent such as phthalic anhydride into the polymerization system. The kinetic study of the solution imidization revealed that the imidization reaction obeyed second-order kinetics. The activation energy calculated for this imidization was 99.2 kJ/mol, being similar to that for the imidization of the DSDA-based aromatic polyimides. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2237-2245, 1998
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  • 98
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    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2229-2235 
    ISSN: 0887-624X
    Keywords: polyarylates ; aromatic polyether ; 2,2-bis(4-hydroxyphenyl)-1,2-diphenylethanone ; solubility ; thermal behavior ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New polyarylates having benzopinacolone units were synthesized from 2,2-bis(4-hydroxyphenyl)-1,2-diphenylethanone and aromatic dicarboxylic acid chlorides. The polymers having an inherent viscosity of 0.71-0.94 dL/g were obtained by the two-phase method using toluene as an organic solvent. The polymers were easily soluble in various organic solvents and had high glass transition temperatures in the range of 200-240°C. An aromatic polyether having benzopinacolone unit was also prepared. However, its inherent viscosity was low because of the occurrence of a side reaction. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2229-2235, 1998
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  • 99
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    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 31-38 
    ISSN: 0887-624X
    Keywords: triblock copolymers ; polycondensations ; telechelic character ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Telechelic oligo(ether-ketone)s containing two trimethylsiloxy end groups and one methyl group per repeating unit were prepared by polycondensation of 4-fluoro-2′-methyl-4′-(trimethylsiloxy)benzophenone. The telechelic character was achieved by cocondensation of a small amount of silylated bisphenol-P. The end groups of the silylated oligo(ether-ketone)s were acetylated by means of acetyl chloride. On the basis of 1H-NMR end group analyses two samples of α,ω-bis(acetoxy) oligo(ether-ketone)s with DP = 14 and DP ∼ 28 were obtained. These oligo(ether-ketone)s and a 70 or 140 fold molar amount of silylated 3,5-bis(acetoxy)benzoic acid were polycondensed at 270°C in bulk. The resulting A-B-A triblock copolymers were fractionated by dissolution in tetrahydrofuran. In three out of four experiments a small fraction of precipitated material rich in oligo(ether-ketone) was isolated. The purified triblock copolymers were characterized by inherent viscosities and NMR spectra. For those samples containing the long oligo(ether-ketone) block a low degree of crystallinity was observed after annealing. Four additional polycondensations were conducted with an initial reaction temperature of 290°C. In this way a completely soluble and amorphous triblock copolymer was obtained. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 31-38, 1998
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 100
    ISSN: 0887-624X
    Keywords: liquid crystalline polymers ; epoxy resins ; thermotropic ; polymer chain extension ; catalytic polyaddition ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This work is a continuation of the authors' earlier investigations of liquid crystalline epoxy resins prepared from diglycidyl ether of 4,4′-dihydroxybiphenyl (DGE-DHBP), which was used as a mesogenic agent, and aliphatic dicarboxylic compounds, which were used as flexible spacers. In this paper, the synthesis and characterization of liquid crystalline epoxy resins, prepared from DGE-DHBP and difunctional aromatic compounds are described. Three series of liquid crystalline epoxy resins were prepared by chain extension of DGE-DHBP with isomeric hydroxybenzoic and benzenedicarboxylic acids as well as diphenols. An isophthalic-terminated polyether was applied to decrease the temperature of phase transitions. The syntheses were carried out by catalytic polyaddition in the melt. Triphenylphosphine was applied as the catalyst. The resulting epoxy resins were investigated by DSC, polarizing microscope as well as by X-ray and IR spectroscopy. The phase transition temperatures and the type of mesophase of the resulting products depend on the character of the functional groups in the chain extender and on the position of the functional groups in the aromatic ring. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 21-29, 1998
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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