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  • 1
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Biochimie 67 (1985), S. 785-789 
    ISSN: 0300-9084
    Keywords: DNA ; DNA chain breaks ; chemical modification ; coupures de chaines ; modification selective ; oligonucleotides ; oligonucleotides ; polynucleotides ; targeted reagents
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1608-3245
    Keywords: DNA ; kinetics ; oligonucleotide derivatives ; photomodification ; sensitization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Quantitative characteristics of thermodynamic and kinetic cooperativity arising in the process of photomodification of a single-stranded DNA fragment with binary systems of oligonucleotide conjugates forming an active site on the target were studied. Oligonucleotides of the binary system were complementary to adjacent segments of the DNA target, and contained arylazide (X) and perylene (S) residues covalently attached to their terminal phosphates. Upon irradiation at the perylene absorption wavelength, the target was modified by the arylazide residue, which was activated owing to the contiguity with the sensitizing perylene group in the tandem complex. Basing on the kinetic data, the constants of association of both derivatives of oligonucleotides with the target were determined: K x = 1.13 · 106 M–1, K s = 1.49 · 104 M–1. It was determined that association of both oligonucleotides with the target proceeded with a positive cooperativity characterized by parameter α = 45. The kinetic cooperativity parameter β was found to be approximately equal to 200; this characterized the acceleration of target modification in complex with the binary reagent versus that in the absence of sensitizer.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1573-6857
    Keywords: Antisense oligonucleotides ; affinity modification ; DNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Development of efficient methods for synthesis of oligonucleotides and oligonucleotide analogs has opened up the possibility of designing a broad spectrum of affinity reagents for specific modification of nucleic acids and proteins. These affinity reagents are used for investigation of the topology of ribosomes and nucleic acid polymerases. Oligonucleotides and their analogs are already used for suppression of specific gene expression and for elucidation of the physiological role of their products. Oligonucleotide derivatives appear to offer considerable promise as potential gene-targeted drugs such as antivirals and specific inhibitors of oncogene expression.
    Type of Medium: Electronic Resource
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  • 4
    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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