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  • 1
    Electronic Resource
    Electronic Resource
    Rate Dependent Effects of Procainamide on the Threshold Current for Pacing in the Setting of Postrepolarization Refractoriness in Dogs (1999)
    Oxford, UK : Blackwell Publishing Ltd
    Pacing and clinical electrophysiology 22 (1999), S. 0 
    Details
    ISSN: 1540-8159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Normally, ventricular APD exceeds the VERP. However, under specific circumstances this relation may change and can become inverse. This phenomenon of postrepolarization refractoriness may be caused by a decrease in excitability. The threshold current (TC) for pacing has never been quantified as a possible explanation for these observations. Using a MAP pacing catheter in the right ventricular apex, the rate dependent behavior of TC, VERP, and APD before and after procainamide (dose 20 mg/kg in 10 min + 5 mg/min infusion) was determined in 17 dogs with chronic complete AV block. Initially, TC was determined with 0.1 mA accuracy. Using a pacing current of at least twice TC, VERP and APD showed a similar, rate dependent shortening for PCLs 800, 575, and 350 ms. Procainamide treatment led to an equal, rate independent VERP and APD increase: no post repolarization refractoriness. Subsequently, accuracy for TC determination was increased to 0.01 mA. Comparing PCLs 800 and 250 ms, TC doubled from 0.05 ± 0.01 to 0.10 ± 0.09 mA during control and almost tripled from 0.06 ± 0.02 to 0.17 ± 0.10 mA (P 〈 0.05) after procainamide. Using a fixed pacing current of exactly twice TC found at 800 ms PCL during control, VERP exceeded APD after procainamide treatment at 300 and 250 ms PCL: postrepolarization refractoriness. Increasing the pacing current to twice the rate dependent TC, the relation between VERP and APD normalized: no postrepolarization refractoriness. We conclude that after procainamide, rate dependent TC increase is of major importance for the phenomenon of postrepolarization refractoriness.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1540-8159.1999.tb00441.x
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  • 2
    Electronic Resource
    Electronic Resource
    The Asymptomatic Patient with the Wolff-Parkinson-White Electrocardiogram (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Pacing and clinical electrophysiology 20 (1997), S. 0 
    Details
    ISSN: 1540-8159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Sudden death can be the first manifestation of the Wolff-Parkinson-White (WPW) syndrome. The underlying mechanism being atrial fibrillation with a very high ventricular rate, because of a short anterograde refractory period of the accessory atrioventricular pathway (AP), deteriorating into ventricular fibrillation. Information on the anterograde refractory period of the AP is therefore important to recognize asymptomatic people with the WPW ECG at risk for dying suddenly. Several noninvasive tests are available to identify the low risk patient. Decision making when to interrupt the AP in asymptomatic WPW patients not at low risk requires an invasive study to document the electrophysiological properties of the AP and to determine its exact location.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1540-8159.1997.tb03633.x
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  • 3
    Electronic Resource
    Electronic Resource
    Predictors of Cognitive Test Patterns in Autism Families (1999)
    Oxford, UK and Boston, USA : Blackwell Publishing Ltd.
    The @journal of child psychology and psychiatry 40 (1999), S. 0 
    Details
    ISSN: 1469-7610
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine , Psychology
    Notes: In a case-control study of cognitive performance, tests of intelligence, reading, spelling, and pragmatic language were administered to the parents and siblings of 90 community-ascertained probands with autism (AU group) and to the parents and siblings of 40 similarly ascertained probands with trisomy 21 Down syndrome (DS group). The two samples were comparable for age and parents' education; both groups were well-educated and had above-average intelligence. AU parents scored slightly but significantly lower on the WAIS-R Full Scale and Performance IQ, on two subtests (Picture Arrangement and Picture Completion), and on the Word Attack Test (reading nonsense words) from the Woodcock-Johnson battery. There were no differences between AU and DS siblings. As in earlier studies, AU parents, more often than DS parents, reported a history of early language-related cognitive difficulties; we were not able to replicate this in siblings. AU parents who reported such difficulties scored significantly lower on Verbal IQ, spelling, and the nonsense reading test. AU parents without a history of early language-related cognitive difficulties often had a Verbal IQ that exceeded Performance IQ by more than one standard deviation. AU siblings with early language-related difficulties had similar findings: lower Verbal IQ, poorer spelling, and poorer reading scores, compared to AU siblings without such a history. Parents with a positive history also scored worse on a measure of pragmatic language, the Pragmatic Rating Scale, but not on measures of social-related components of the broader autism phenotype. We propose that cognitive differences in a subset of autism family members are manifestations of the language-related component of the broader autism phenotype, and separate from the social-related component. This is consistent with the hypothesis that there are several genes that may interact to cause autism which segregate independently and have distinguishable manifestations in family members. The hypothesis would be further supported by finding different patterns of genetic loci linked to autism in families where one or both parents has language difficulties.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/1469-7610.00528
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  • 4
    Electronic Resource
    Electronic Resource
    The Effect of Flunarizine and Ryanodine on Acquired Torsades de Pointes Arrhythmias in the Intact Canine Heart (1995)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of cardiovascular electrophysiology 6 (1995), S. 0 
    Details
    ISSN: 1540-8167
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Flunarizine and Ryanodine in Acquired TdP. Introduction: Ryanodine, a specific blocker of the Ca2+ release channel of the sarcoplasmic reticulum, and flunarizine, a[Ca2+], overload blocker, possess antiarrhythmic effects against delayed after depolarizations (DADs) and DAD-dependent arrhythmias. In vitro controversy exists about their effect on early after depolarizations (EADs): no effect was reported on cesium-induced EADs, while ryanodine did prevent EADs induced by isoproterenol. To study the possible role of intracellular Ca2+ overload in acquired EAD-dependent torsades de pointes (TdP) arrhythmias, we tested the effects of flunarizine and ryanodine in our animal model of TdP. Methods and Results: Anaesthetized dogs with chronic AV block received d-sotalol or almokalant followed by pacing. A subset of dogs with reproducible TdP (≥ 3 times) were selected to receive flunarizine (2 mg/kg per 2 min) or ryanodine (10 μg/kg per 10 min). After dsotalol, TdP was induced at a mean cycle length of the idioventricular rhythm (CL-IVR) of 2070 ± 635 msec and a QT(U) interval of 535 ± 65 msec. Induction of TdP was prevented by flunarizine in all experiments (8/8): electrophysiologically this was associated with a decrease in CL-IVR, QT(U), and QTc interval (390 ± 100 to 320 ± 45, P 〈 0.05). Ryanodine prevented TdP induction in 4 of 5 experiments and decreased the CL-IVR, QT(U), and the QTc interval from 385 ± 75 to 320 ± 20 msec (P 〈 0.05). Both drugs also suppressed the almokalant-induced EADs and related ectopic activity. This antiarrhythmic action corresponded with the inability to reinduce TdP by pacing. Conclusions: Blockade of the Ca2+ release channel of the sarcoplasmic reticulum by ryanodine or the reduction of [Ca2+] overload by flunarizine prevents induction of EAD-dependent acquired TdP arrhythmias, suggesting a role for [Ca2+]i overload in acquired TdP.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1540-8167.1995.tb00770.x
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  • 5
    Electronic Resource
    Electronic Resource
    Modulation of Healthy Pig Coronary Arteries by Self-Expanding Stents (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of interventional cardiology 9 (1996), S. 0 
    Details
    ISSN: 1540-8183
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Objectives: To evaluate the expansion ratio of a self-expanding stem over time, and the chronic effect of stent pressure on the vessel wall. Methods: Self-expanding stents, developed by Medtronic Inc. (Minneapolis, MN, USA) and the Rouen group (Letac, Cribier, France), were implanted in 21 normal pig coronary arteries. Animals were sacrificed after recatheterization at 1 day (group I, n = 4), I week (group 2, n = 3), 3 weeks (group 3, n = 5), or 8 weeks (group 4, n = 4). Histological morphometry of the vessel medial and neointimal layers was performed. Changes were related to the, stent diameter and. its force on the vessel wall. Results: The stent expansion ratio gradually increased from 73% to 93% after 8 weeks, which implicates that radial force decreased concomitantly from 0.10 N to 0.03 N. Media compression under the rods ranged from 4l%-66% immediately after stent implantation. The mean compression was unrelated to stent expansion and remained nearly the same (40%-50%) during follow-up. Individual media rod compression ranged from 5%-95%. The neointimal layer on top of the rods increased until the third week after stent implant (neointimal thickness 211 ± 108 μm). The layer significantly decreased at 8 weeks (neointimal thickness 65 ± 9 μm). The cross-sectional neointimal area increased gradually only at the end of the stent during the 8-week follow-up. Conclusions: The self-expanding stent implanted in normal pig coronary arteries reached a gradual relaxation state 8 weeks after implantation due to the persistent radial force. This radial force induces medial wall compression, which was only positively related to the thickness of the neointimal layer at 3 weeks after implant. (J Interven Cardiol 1996;9:45–52)
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1540-8183.1996.tb00594.x
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  • 6
    Electronic Resource
    Electronic Resource
    Hemodynamic Effects in Acute Cardiomyoplasty of Different Wrapped Muscle Activation Times as Measured by Pressure-Volume Relations (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of cardiac surgery 11 (1996), S. 0 
    Details
    ISSN: 1540-8191
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract Background: Correct timing of mechanical interaction between wrapped latissimus dorsi muscle (LDM) and the heart during cardiac systole has been poorly understood and remains a controversial issue. Therefore, left ventricular pressure-volume relations were analyzed in acute cardiomyoplasty while changing the synchronization delays. Methods: Effects of different delays between the sensed cardiac R wave and wrapped muscle contraction were studied in goats submitted to acute left cardiomyoplasty. Conductance and micromanometer catheters were used to evaluate hemodynamics. Systolic contribution of the wrapped muscle was studied in preassisted and assisted beats, whereas diastolic effects were studied in assisted and postassisted beats. Results: At best settings, cardiomyoplasty resulted in a significant (p 〈 0.05) increase in left ventricular ejection fraction (from 42.2 ± 9.2 to 56.7%± 13%), in stroke work (from 2769 ± 1140 to 4271 ± 1717 gm/m2), in dP/dt (from 1185 ± 342 to 1510 ± 285 mmHg/sec), in end-systolic pressure (from 93.5 ± 22.5 mmHg to 97.3 ± 22.3 mmHg), and in peak ejection rate (from 282 ± 64 to 533 ± 241 mL/sec). Stroke volume showed a mean increase of 35% (from 42.2 ± 9.9 mL to 56.9 ± 20.1 mL) during assisted beats. Diastolic function was not substantially impaired at optimal stimulation delay. Incorrect timing of LD contraction resulted in suboptimal improvement or no change in comparison with unassisted hemodynamics. Conclusions: Our study documents support of cardiac performance by LDM. Incorrect timing of heart/wrapped muscle interaction led to suboptimal hemodynamic results. Muscle contraction timing is an important factor in cardiomyoplasty outcome.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1540-8191.1996.tb00042.x
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  • 7
    Electronic Resource
    Electronic Resource
    IV. Molecular biology of S-layers (1997)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology reviews 20 (1997), S. 0 
    Details
    ISSN: 1574-6976
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: In this chapter we report on the molecular biology of crystalline surface layers of different bacterial groups. The limited information indicates that there are many variations on a common theme. Sequence variety, antigenic diversity, gene expression, rearrangements, influence of environmental factors and applied aspects are addressed. There is considerable variety in the S-layer composition, which was elucidated by sequence analysis of the corresponding genes. In Corynebacterium glutamicum one major cell wall protein is responsible for the formation of a highly ordered, hexagonal array. In contrast, two abundant surface proteins form the S-layer of Bacillus anthracis. Each protein possesses three S-layer homology motifs and one protein could be a virulence factor. The antigenic diversity and ABC transporters are important features, which have been studied in methanogenic archaea. The expression of the S-layer components is controlled by three genes in the case of Thermus thermophilus. One has repressor activity on the S-layer gene promoter, the second codes for the S-layer protein. The rearrangement by reciprocal recombination was investigated in Campylobacter fetus. 7–8 S-layer proteins with a high degree of homology at the 5′ and 3′ ends were found. Environmental changes influence the surface properties of Bacillus stearothermophilus. Depending on oxygen supply, this species produces different S-layer proteins. Finally, the molecular bases for some applications are discussed. Recombinant S-layer fusion proteins have been designed for biotechnology.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6976.1997.tb00304.x
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  • 8
    Electronic Resource
    Electronic Resource
    Interchange of the active and silent S-layer protein genes of Lactobacillus acidophilus by inversion of the chromosomal slp segment (1996)
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 21 (1996), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The most-dominant surface-exposed protein in many bacterial species is the S-protein. This protein crystallises into a regular monolayer on the outside surface of the bacteria: the S-layer. Lactobacillus acidophilus harbours two S-protein-encoding genes, slpA and slpB, only one of which (slpA ) is expressed. In this study, we show by polymerase chain reaction (PCR) analysis that slpA and slpB are located on a 6 kb chromosomal segment, in opposite orientations. In a small fraction of the bacterial population, this segment is inverted. The inversion leads to interchanging of the expressed and silent S-protein-encoding genes, and places the formerly silent gene behind the S-promoter which is located outside the inverted segment. A 26 bp sequence showing a high degree of similarity with the consensus sequence recognized by the Din family of invertases is present in the region where recombination occurs. Expression of the slpA gene seems to be favoured under laboratory growth conditions because 99.7% of the chromosomes of an L. acidophilus ATCC 4356 broth culture had the slpA gene present at the slp expression site.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1996.401406.x
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  • 9
    Electronic Resource
    Electronic Resource
    Expression, secretion and antigenic variation of bacterial S-layer proteins (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 21 (1996), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The function of the S-layer, a regularly arranged structure on the outside of numerous bacteria, appears to be different for bacteria living in different environments. Almost no similarity exists between the primary sequences of S-proteins, although their amino acid composition is comparable. S-protein production is directed by single or multiple promoters in front of the S-protein gene, yielding stable mRNAs. Most bacteria secrete S-proteins via the general secretory pathway (GSP). Translocation of S-protein across the outer membrane of Gram-negative bacteria sometimes occurs by S-protein-specific branches of the GSP. O-polysaccharide side-chains of the lipopolysaccharide component of the cell wall of Gram-negative bacteria appear to function as receptors for attachment of the S-layer. Silent S-protein genes have been found in Campylobacter fetus and Lactobacillus acidophilus. These silent genes are placed in the expression site in a fraction of the bacterial population via inversion of a chromosomal segment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1996.711442.x
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  • 10
    Electronic Resource
    Electronic Resource
    Untersuchungen über das Wachstum von 38 alten Tuberkelbakterienstämmen (1956)
    Springer
    Journal of molecular medicine 34 (1956), S. 1293-1293 
    Details
    ISSN: 1432-1440
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01477521
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