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  • 1
    Electronic Resource
    Electronic Resource
    Defibrillation Causes Immediate Cardiac Dilation in Humans (2003)
    350 Main Street , Malden , MA 02148-5018 , USA , and 9600 Garsington Road , Oxford OX4 2DQ , UK . : Blackwell Science Inc
    Journal of cardiovascular electrophysiology 14 (2003), S. 0 
    Details
    ISSN: 1540-8167
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Introduction: Prior studies in isolated heart tissue have shown both excitation and deexcitation to be the primary mechanism of defibrillation. This article presents the first evidence in man of deexcitation immediately following defibrillation by tracking the heart's mechanical response. Methods and Results: The geometric changes of the ventricular chambers were measured before and after defibrillation in seven human subjects receiving an implantable cardioverter defibrillator (ICD). The ICD was used to produce approximately three episodes of ventricular fibrillation and defibrillation in each subject. Twenty-two two-dimensional echocardiographic images of the right ventricle (RV) and 11 images of the left ventricle (LV) were recorded and analyzed at 30 frames per second. Just over 2 seconds of each episode were digitized, beginning half a second before the defibrillation shock. Individual frames were analyzed to yield cross-sectional, ventricular chamber area as a function of time. Immediately following defibrillation, ventricular chambers dilated with significant fractional area increase (RV: 1.58 ± 0.25, LV: 1.10 ± 0.06), with peak dilation at 194 ± 114 msec. Conclusion: Defibrillation causes a rapid increase in ventricular chamber area due to relaxation of the myocardium, suggesting that defibrillation synchronizes the cardiac cells to the deexcited state in man. (J Cardiovasc Electrophysiol, Vol. 14, pp. 832-836, August 2003)
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1540-8167.2003.02592.x
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  • 2
    Electronic Resource
    Electronic Resource
    Reentry Site During Fibrillation Induction in Relation to Defibrillation Efficacy for Different Shock Waveforms (2001)
    Oxford, UK : Blackwell Science Inc
    Journal of cardiovascular electrophysiology 12 (2001), S. 0 
    Details
    ISSN: 1540-8167
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Reentry Site and Defibrillation Waveform Efficacy. Introduction: Unsuccessful defibrillation shocks may reinitiate fibrillation by causing postshock reentry. Methods and Results: To better understand why some waveforms are more efficacious for defibrillation, reentry was induced in six dogs with 1-, 2-, 4-, 8-, and 16-msec monophasic and 1/1- (both phases 1 msec) 2/2-, 4/4-, and 8/8-msec biphasic shocks. Reentry was initiated by 141 ± 15 V shocks delivered from a defibrillator with a 150- μ F capacitance during the vulnerable period of paced rhythm (183 ± 12 msec after the last pacing stimulus). The shock potential gradient field was orthogonal to the dispersion of refractoriness. Activation was mapped with 121 electrodes covering 4 × 4 cm of the right ventricular epicardium, and potential gradient and degree of recovery of excitability were estimated at the sites of reentry. Defibrillation thresholds (DFTs) were estimated by an up-down protocol for the same nine waveforms in eight dogs internally and in nine other dogs externally. DFT voltages for the different waveforms were positively correlated with the magnitude of shock potential gradient and negatively correlated with the recovery interval at the site at which reentry was induced by the waveform during paced rhythm for both internal (DFT = 1719 + 64.5 ∇ V − 11.1RI; R2= 0.93) and external defibrillation (DFT = 3445 + 150 ∇ V − 22RI; R2= 0.93). Conclusion: The defibrillation waveforms with the lowest DFTs were those that induced reentry at sites of low shock potential gradient, indicating efficacious stimulation of myocardium. Additionally, the site of reentry induced by waveforms with the lowest DFTs was in myocardium that was more highly recovered just before the shock, perhaps because this high degree of recovery seldom occurs during defibrillation due to the rapid activation rate during fibrillation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1540-8167.2001.00581.x
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  • 3
    Electronic Resource
    Electronic Resource
    Persistence of cigarette smoking: familial liability and the role of nicotine dependence (2002)
    Oxford, UK : Blackwell Science Ltd
    Addiction 97 (2002), S. 0 
    Details
    ISSN: 1360-0443
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine , Psychology
    Notes: Aims  It has been suggested that high genetic vulnerability may explain why smoking persists in spite of general acceptance of the health risks of cigarette smoking. Indeed, heritability estimates for smoking persistence range from 27% to 70%. It has also been suggested that genetic influences on smoking persistence may operate through nicotine dependence, which epidemiological studies have found to be an important risk factor for smoking persistence. We examined alternative ways that familial liability to persistence, nicotine dependence and smoking persistence may be related.Design  Cohort study.Setting  South-east Michigan, United States.Participants  A subset of 389 daily smokers informative for familial smoking characteristics from an epidemiological sample of young adults 26–35 years old (n = 979).Measurements  Nicotine dependence criteria were assessed using the NIMH-DIS revised interview and diagnosed according to the DSM-III-R. Familial smoking characteristics were assessed by subject report.Findings  Absent nicotine dependence, daily smokers with medium and high familial density of persistence were at increased risk of smoking persistence (OR = 4.2 and 7.0, respectively). However, familial density of persistence was not associated with smoking persistence among nicotine dependent daily smokers. Level of education also appeared to limit the influence of familial liability, although nicotine dependence also modified this effect.Conclusions  Nicotine dependence does not appear to be in the causal pathway from familial liability to smoking persistence, but rather modifies the association between them.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1360-0443.2002.00211.x
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  • 4
    Electronic Resource
    Electronic Resource
    Nucleotide sequence and transcriptional analysis of the type A2 neurotoxin gene cluster in Clostridium botulinum (2004)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 235 (2004), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The nucleotide sequences of the upstream regions of the botulinum neurotoxin type A1 (BoNT/A1) cluster of Clostridium botulinum strain NCTC 2916 and the BoNT/A2 cluster of strain Kyoto-F were determined. A novel gene, designated orfx3, was identified following the orfx2 gene in both clusters. ORF-X2 and ORF-X3 exhibit similarity to the BoNT cluster associated P-47 protein. The BoNT/A1 and BoNT/A2 clusters share a similar gene arrangement, but exhibit differences in the spacing between certain genes. Sequences with similarity to transposases were identified in these intergenic regions, suggesting that these differences arose from an ancestral insertion event. Transcriptional analysis of the BoNT/A2 cluster revealed that the genes of the cluster are primarily synthesized as three polycistronic transcripts. Two divergent polycistronic transcripts, one encoding the orfx1, orfx2, and orfx3 genes, the second encoding the p47, ntnh, and bont/a2 genes, are transcribed from conserved BoNT cluster promoters. The third polycistronic transcript, expressed at low levels, encodes the positive regulatory botR gene and the orfx genes. This is the first complete analysis of a botulinum toxin A2 cluster.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.2004.tb09561.x
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  • 5
    Electronic Resource
    Electronic Resource
    Microbial ferric iron reductases (2003)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology reviews 27 (2003), S. 0 
    Details
    ISSN: 1574-6976
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Almost all organisms require iron for enzymes involved in essential cellular reactions. Aerobic microbes living at neutral or alkaline pH encounter poor iron availability due to the insolubility of ferric iron. Assimilatory ferric reductases are essential components of the iron assimilatory pathway that generate the more soluble ferrous iron, which is then incorporated into cellular proteins. Dissimilatory ferric reductases are essential terminal reductases of the iron respiratory pathway in iron-reducing bacteria. While our understanding of dissimilatory ferric reductases is still limited, it is clear that these enzymes are distinct from the assimilatory-type ferric reductases. Research over the last 10 years has revealed that most bacterial assimilatory ferric reductases are flavin reductases, which can serve several physiological roles. This article reviews the physiological function and structure of assimilatory and dissimilatory ferric reductases present in the Bacteria, Archaea and Yeast. Ferric reductases do not form a single family, but appear to be distinct enzymes suggesting that several independent strategies for iron reduction may have evolved.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/S0168-6445(03)00043-3
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  • 6
    Electronic Resource
    Electronic Resource
    Geographic Variation in Patient Surveillance After Radical Prostatectomy (2000)
    Springer
    Annals of surgical oncology 7 (2000), S. 339-346 
    Details
    ISSN: 1534-4681
    Keywords: Prostate cancer ; Radical prostatectomy ; Recurrent cancer ; Geographical variation ; Follow-up
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background: Prostate cancer is often diagnosed early enough in its clinical course to permit radical prostatectomy to be done with curative intent, yet many patients experience tumor recurrence. Most patients receive postoperative surveillance, but the intensity of testing varies appreciably. We sought to evaluate the influence of geographic location on the variability of surveillance intensity. Methods: Questionnaires pertaining to postoperative surveillance were mailed to 4467 members of the American Urological Association (AUA). Practice pattern variation was assessed among 24 large metropolitan statistical areas, among nine United States census regions, and by health maintenance organization penetration rate. Results: Of 4467 urologists surveyed, 1416 (32%) responded and 1050 (24%) responses were evaluable. Correlation analysis showed that mean follow-up intensity across modalities surveyed was highly correlated across tumor, node, metastasis (TNM) stages and years postsurgery. We found no significant main effects attributable to metropolitan statistical area, United States (US) census region, or health maintenance organization (HMO) penetration rate for commonly used surveillance modalities: serum prostate-specific antigen (PSA), office visit, and urinalysis. For infrequently used modalities, there were minimal effects on testing intensity of US census region, metropolitan statistical area, and HMO penetration rate. Few two-way and three-way interactions were significant. Conclusions: The utilization of commonly used surveillance modalities by urologists caring for patients after radical prostatectomy is not affected by metropolitan statistical area, US census region, or HMO penetration rate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s10434-000-0339-8
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  • 7
    Electronic Resource
    Electronic Resource
    Regulation of Proton Flow and ATP Synthesis in Chloroplasts (2000)
    Springer
    Journal of bioenergetics and biomembranes 32 (2000), S. 501-506 
    Details
    ISSN: 1573-6881
    Keywords: CF1 ; ATP synthase ; proton flow ; electron transport ; slip
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract The chloroplast ATP synthase is strictly regulated so that it is very active in the light (rates of ATP synthesis can be higher than 5 μmol/min/mg protein), but virtually inactive in the dark. The subunits of the catalytic portion of the ATP synthase involved in activation, as well as the effects of nucleotides are discussed. The relation of activation to proton flux through the ATP synthase and to changes in the structure of enzyme induced by the proton electrochemical gradient are also presented. It is concluded that the γ and ε subunits of CF1 play key roles in both regulation of activity and proton translocation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005669008974
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