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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Pacing and clinical electrophysiology 21 (1998), S. 0 
    ISSN: 1540-8159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: DDD pacemakers differ considerably in device specific extents of AV delay (AVD) programmability. To demonstrate the requirements of a mean DDD pacemaker patient population optimal AVDs in 200 DDD pacemaker patients (age 8 to 91 years) were estimated by left atrial electrography. The results should help to define an AVD programmability standard. Left atrial electrograms were recorded via a bipolar filtered esophageal lead. The method aims on adjusting the left atrial electrogram to 70 ms prior to the ventricular spike, both during VDD and DDD operation of the pacemaker. In atrial sensed stimulation the optimal AVD varied from 40 to 205 ms (100.5 ± 24.5 ms) and in atrial paced stimulation from 85 to 245 ms (169.1 ±24.5 ms). The difference of the mean values is statistically significant (p 〈 0.001). The difference between both values in the individual patient, the individual AVD correction time, varied from 0 to 170 ms (68.7 ± 26.6 ms). Thus, from our findings requirements on AV delay programmability standard can be derived: AVDs (1) should have a range from 40 to 250 ms, (2) should be independently programmable during atrial sensed and atrial paced operation, ami (3) should provide as nominal settings 100 ms for atrial sensed and 170 ms for atrial paced stimulation.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: We have analysed the capacity of the 11 phase-variable, opacity-associated (Opa) proteins encoded by Neisseria gonorrhoeae MS11 to mediate traversal across polarized monolayers of the human colonic carcinoma T84 cell line. Gonococci expressing either the heparan sulphate proteoglycan (HSPG) binding Opa protein (Opa50) or no Opa protein (Opa−) did not interact with the apical pole of T84 monolayers, whereas the 10 variant Opa proteins previously shown to bind CD66 receptors were found to mediate efficient gonococcal adherence and transepithelial traversal. Consistent with this, T84 cells were shown by reverse transcriptase–polymerase chain reaction (RT–PCR) and immunoblotting to co-express CD66a (BGP), CD66c (NCA) and CD66e (CEA). The recruitment of CD66 receptors by Opa-expressing gonococci indicates their involvement in mediating adherence to the surface of T84 cells, and these bacterial interactions could be inhibited completely using polyclonal antibodies cross-reacting with all of the CD66 proteins co-expressed on T84 cells. Consistent results were obtained when Opa proteins were expressed in Escherichia coli, suggesting that the Opa–CD66 interaction is sufficient to mediate bacterial traversal. Transcytosis of Opa-expressing N. gonorrhoeae or E. coli did not disrupt the barrier function of infected monolayers, as indicated by a sustained transepithelial electrical resistance (TEER) throughout the course of infection, and confocal laser scanning and electron microscopy both suggest a transcellular rather than a paracellular route of traversal across the monolayers. Parallels between the results seen here and previous work done with organ cultures confirm that T84 monolayers provide a valid model for studying neisserial interactions with the mucosal surface, and suggest that CD66 receptors contribute to this process in vivo.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0178-515X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The recovery of recombinant proteins includes a purification process that has to be compressed to a minimum of steps in order to get high yields with a low cost expenditure. A selective liberation of recombinant proteins by cell permeabilization leads to both a high product purity just in the beginning of the recovery process and to a simplification of the cell residue separation compared to the mechanical cell disruption. In case of the purification of the bacterial plasminogen activator Staphylokinase from E. coli cells, yields of 82% with a purity of 46% were attained by utilization of permeabilization by biomass freezing, resuspension in a Tris/EDTA-buffer and following micro-diafiltration. A recovery process without interruption (freezing) is possible due to the addition of guanidine-HCl and Triton X100 to the buffer. These methods were developed on a laboratory-scale.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Der Internist 39 (1998), S. 38-45 
    ISSN: 1432-1289
    Keywords: Schlüsselwörter Azetylsalizylsäure ; Antikoagulation ; Embolie ; arterielle ; Tachyarrhythmien ; supraventrikuläre ; Vorhofflimmern
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Zum Thema Als begleitende Präventionsmaßnahme im Hinblick auf das Thromboembolie-Risiko hat sich die Antikoagulation neben der medikamentösen antiarrhythmischen Behandlung supraventrikulärer Tachyarrhythmien bewährt. Grundlage dafür sind mehrere seit 1989 publizierte Studien zur Primär- bzw. Sekundärprävention arterieller Embolien bei Vorhofflimmern. Über die Ergebnisse und die daraus abgeleiteten differenzierten Therapieempfehlungen in Abhängigkeit von den klinischen Verlaufsformen supraventrikulärer Tachyarrhythmien wird hier eingehend referiert. Unbestritten ist die prinzipielle Überlegenheit einer oralen Antikoagulation bei supraventrikulären Tachyarrhythmien, besonders beim Vorhofflimmern. Das gilt auch im Vergleich mit der Embolieprophylaxe durch ASS. Nicht außer Betracht bleiben darf aber das mit der Cumaringabe verbundene Blutungsrisiko. Darauf sei ausdrücklich hingewiesen, da dieses in der ambulanten Praxis, also außerhalb von Studienbedingungen, sicher einen anderen Stellenwert hat. Gründe dafür dürften höhere Komorbitität, höheres Lebensalter der Patienten und möglicherweise auch eine weniger exakte Überwachung der Antikoagulation sein.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Archives of gynecology and obstetrics 257 (1995), S. 602-606 
    ISSN: 1432-0711
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1435-2451
    Keywords: Key words Pancreatic cancer ; p53 ; Antisense oligodeoxynucleotides ; Cell culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Introduction: Pancreatic adenocarcinomas are largely resistant to apoptosis. More than 50% of pancreatic tumors reveal mutations in the p53 tumor suppressor gene. Methods: We investigated the growth of pancreatic tumor cells after downregulation of p53 protein expression by antisense oligodeoxynucleotides. Results: Proliferation and p53 expression of PancTu-I cells overexpressing mutant p53 protein were inhibited by antisense oligodeoxynucleotide treatment. When analyzed, two of three other pancreatic tumor cell lines with mutated p53 were also inhibited in their growth. Two of two wild-type (wt) p53 pancreatic tumor cells were not significantly influenced by p53 expression and were, only to a lesser extent, affected in their proliferation. K562 cells (lacking p53 mRNA) and normal human skin fibroblasts used as a target mismatch control showed no changes in proliferation rates with treatment. The different biological effects in the various cells were not caused by differences in the uptake of the oligodeoxynucleotides as monitored by confocal laser-scanning microscopy. Conclusions: Truncation and 5′- and 3′-lipophilic modifications of the oligodeoxynucleotides drastically enhanced the growth inhibition of PancTu-I cells, which were resistant to apoptosis-inducing agents. Furthermore, a higher sequence-specificity of the observed effects was achieved with these compounds.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Herzschrittmachertherapie & Elektrophysiologie 10 (1999), S. S034 
    ISSN: 1435-1544
    Keywords: Key words Antiarrhythmic therapy – cardiothoracic surgery – atrial fibrillation ; Schlüsselwörter Antiarrhythmische Therapie ; Kardiochirurgie ; Vorhofflimmern
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Hintergrund: Häufigste Arrhythmie im Zusammenhang mit kardiochirurgischen Eingriffen ist das postoperative Vorhofflimmern einschließlich verwandter atrialer Rhythmusstörungen. Da zunehmend ältere Patienten kardiochirurgisch behandelt werden, hat das Interesse an dieser Arrhythmieform mit noch einigen ungeklärten Fragen wieder zugenommen. Ziel und Methode: Darstellung des derzeitigen Kenntnisstandes zum postoperativen Vorhofflimmern unter Berücksichtigung neuerer Literaturmitteilungen. Ergebnisse: In der Regel ist postoperatives Vorhofflimmern vorübergehend, selbstendend und gutartig. Im Falle seines Auftretens sind aber Morbidität, Mortalität und Behandlungskosten höher. Andererseits nimmt das postoperative Vorhofflimmern seinerseits einen ungünstigen Einfluß auf Morbidität und Mortalität. Seine Pathogenese ist multifaktoriell. Eine generelle Prävention kann derzeit nicht empfohlen werden, ist aber in Zukunft denkbar. Die in der Regel nur temporär erforderlichen therapeutischen Überlegungen zu Frequenzkontrolle, Thromboembolieprophylaxe und Rhythmuskontrolle richten sich nach der klinischen Verlaufsform. Schlußfolgerungen: Im Interesse einer Reduktion der Gesamtkomplikationsrate in der Kardiochirurgie bedarf auch das postoperative Vorhofflimmern einer besonderen Aufmerksamkeit.
    Notes: Background: Atrial fibrillation and related arrhythmias are common after cardiac surgery. As more and more elderly patients are operated on for cardiac diseases, the interest in this arrhythmia is growing again. There are some unresolved problems of this complication. Aims and methods: Reevaluation of atrial fibrillation after cardiac surgery by review of recent literature. Results: Usually postsurgical atrial fibrillation is transient, self-limiting, and benign. Nevertheless, among patients affected by this arrhythmia, morbidity, mortality and costs by hospital stay are higher than without this complication. In addition, postsurgical atrial fibrillation can increase morbidity and mortality by itself. Pathogenesis is multifactorial. Today, general recommendations for prevention of atrial fibrillation following surgery do not exist but may be developed in the future. According to the clinical course, therapy has to consider ventricular rate control, prevention of thromboembolic events, and rhythm control. Usually therapy is restricted to the postoperative time. Conclusions: Atrial fibrillation after cardiothoracic surgery has to be respected in order to minimize overall complication rate.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1435-1544
    Keywords: Key words DDD pacing ; AV delay optimization ; Interatrial conduction time ; telemetry ; sense-event marker ; Schlüsselwörter DDD-Stimulation ; AV-Delay-Optimierung ; Interatriale Leitungszeit ; Telemetrie ; Sensing-Marker
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Hintergrund: Bei DDD-Schrittmacherträgern wird das optimale AV-Delay wesentlich durch die interindividuell unterschiedliche interatriale Leitungszeit bestimmt. Wird diese gemessen, kann durch Addition eines bekannten, mittleren, optimalen Intervalles von 70ms zwischen linksatrialer Depolarisation und ventrikulärem Stimulus ein individuell optimales AV-Delay für VDD- und DDD-Betrieb approximiert werden. Da moderne Schrittmacher über eine Telemetrie verfügen, ist es naheliegend, durch Kombination von rechtsatrialer Telemetrie und linksatrialer Elektrographie (via Ösophagusableitung) vorhandene Programmeroptionen zur individuellen AV-Delay-Programmierung zu nutzen. Studienziele: 1. Prüfung der Eignung rechtsatrialer telemetrischer Elektrogramme oder Sensingmarker als rechtsatriale Referenz. 2. Prüfung der Realisierbarkeit einer Implementierung der linksatrialen Elektrographie in handelsübliche Programmer. Methoden: 1. Mittels eines computerisierten Herzsimulators wurde die Verzögerung telemetrischer atrialer Elektrogramme und Sensingmarker bei 12 Schrittmachern 9 unterschiedlicher Hersteller untersucht. 2. Zur Messung interatrialer Leitungszeiten mit Programmiergeräten wurde die Simultandarstellung des rechtsatrialen Elektrogramms bzw. Markerkanals und der linksatrialen Ableitung mittels externer Hardware- bzw. programmerinterner Softwarefilterung der Ösophagusableitung realisiert. Ergebnisse: Abhängig von der Größe des telemetrischen Delays lassen sich Schrittmachersysteme mit Echtzeittelemetrie (Delay 0-12ms) und Orientierungstelemetrie (Delay 12ms) unterscheiden. Es ließ sich zeigen, daß mit der vorgeschlagenen Implementierung linksatrialer Elektrogramme interatriale zeitliche Relationen sowohl unter Vorhofstimulation als auch bei Vorhofführung an Systemen mit Echtzeittelemetrie bequem erfaßt werden können. Die Voraussetzungen für eine individuelle Programmierung des AV-Delay am Programmiergerät und die automatische Bereitstellung von Programmiervorschlägen sowohl für das Basis- als auch des frequenzmodulierten AV-Delay sind damit erfüllt. Schlußfolgerung: Durch Implementierung einer linksatrialen Ableitung in Schrittmacherprogrammer können interatriale Leitungszeiten leicht erfaßt und die physiologische AV-Delay-Programmierung in der Routine vereinfacht werden.
    Notes: Background: In patients with DDD pacing systems, optimal AV delay is mainly determined by interindividually differing interatrial conduction time. If the latter is measured, individual optimal AV delay in VDD and DDD operation can be approximated by adding a representative, optimal interval of 70ms between left atrial depolarization and ventricular stimulus. In modern pacemakers providing telemetry, combination of right atrial telemetry and left atrial electrography via an esophageal lead could be used to measure interatrial conduction times for individual AV delay programming. Aims of the study: 1. To test the usefulness of telemetric right atrial electrograms and markers as a right atrial measuring reference. 2. To prove the possibility of implementing left atrial electrography into commercial programers. Methods: 1. Using computerized heart simulator, delays of the telemetric electrogram and markers were investigated in 12 DDD systems of 9 different companies. 2. To measure interatrial conduction times with programers, simultaneous recordings of right atrial electrogram and marker channel, resp., and the left atrial electrogram were performed using external hardware or internal software filtering of the esophageal lead. Results: Depending on the range of marker delay, pacing systems with real-time telemetry (delay 0–12ms) and orienting telemetry (delay 12ms) were found. Facilitating left atrial electrogram recording into programers, interatrial time intervals can be measured in DDD and VDD operation in pacing systems with real-time telemetry. These results are prerequisits for individual AV delay programming with the programer. Then both can automatically be proposed, basic AV delay and the frequency modulated AV delay. Conclusion: Facilitating left atrial electrogram recording into pacemaker programers, interatrial conduction times can easily be measured for simplified physiologic AV delay programming during routine check-up.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Herzschrittmachertherapie & Elektrophysiologie 9 (1998), S. S52 
    ISSN: 1435-1544
    Keywords: Key words Amiodarone ; beta-blockers ; sudden cardiac death ; Schlüsselwörter Amiodarone ; Betablocker ; plötzlicher Herztod
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Hintergrund: Der plötzliche Herztod ist ein Tod überwiegend durch ventrikuläre Tachyarrhythmien. Dennoch deutete sich eine daraus ableitbare Senkung der Gesamtmortalität kardialer Risikofälle durch prophylaktisch verabfolgte Antiarrhythmika, abgesehen vom bekannten Effekt der Betablocker, nur für Amiodarone an. Ziel und Methode: Betrachtung der primären Prophylaxe des plötzlichen Herztodes durch Amiodarone mit und ohne zusätzliche Betablockade unter Berücksichtigung neuerer Literaturmitteilungen. Ergebnisse: Der Beweis einer signifikanten Senkung nicht nur des plötzlichen Herztodes, sondern auch der Gesamtmortalität durch Amiodarone gelang erst in Meta-Analysen kontrolliert durchgeführter Studien. Dessen ungeachtet ist aber die Zahl dadurch verhinderter plötzlicher Tode bezogen auf die Gesamtzahl der zu behandelnden Fälle gering. Dieses und das spezifische Nebenwirkungsprofil stehen einer generellen primären Prophylaxe mit Amiodarone entgegen. Eine Kombination mit einem Betablocker könnte Vorteile bringen, was aber durch weitere Studien noch abgeklärt werden muß. Schlußfolgerungen: Derzeit bleibt die Amiodaronegabe zur Primärprophylaxe des plötzlichen Herztodes mit oder ohne Betablocker eine Einzelfallentscheidung bei besonderer Risikokonstellation, bei der nicht in jedem Fall ein ärztlicher Konsens erwartet werden darf.
    Notes: Background: Most sudden cardiac deaths are arrhythmic. Besides the known effects of beta-blockers, among true antiarrhythmic drugs only amiodarone seemed to reduce total cardiac mortality in patients at risk. Aim and method: Reevaluation of amiodarone with or without a beta-blocker in primary prophylaxis of sudden cardiac death after review of recent publications. Results: Only augmentation of case numbers by meta-analyses of controlled trials could demonstrate that amiodarone not only reduces sudden cardiac death but also diminishes total cardiac mortality. However, the number of avoided sudden deaths is small in comparison to the number of treated cases. This and specific side effects of amiodarone contradict a general primary prophylaxis with this drug. An additional benefit by combining amiodarone with beta-blockers seems to exist but has to be proven by further studies. Conclusions: At present, primary prophylaxis of sudden cardiac death with amiodarone with or without a beta-blocker is an individual decision in all cases with special risk considerations.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 59 (1998), S. 189-202 
    ISSN: 0006-3592
    Keywords: artificial neural network (ANN) ; microfiltration ; cell harvesting ; membrane fouling ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Microfiltration is an important unit operation in downstream processing. However, due to the influence of membrane fouling, prediction of the filtration performance for biological suspensions is difficult. This paper describes a modeling approach that allows a comprehensive description of filtration performance. On the basis of experimental data and linguistic information, a specific artificial neural network was developed that predicts the process behavior within a certain range of parameters. This approach allows us to analyze influences of fermentation on filtration. By using extensive simulations, the interactions of 17 parameters were examined and the fouling causes determined. The model was developed for cell harvesting of Escherichia coli through a shear-enhanced module. The method can be applied to any cross-flow filtration process. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 59:189-202, 1998.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
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