Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Head-Up Tilt-Table Testing: An Overview (1999)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of noninvasive electrocardiology 4 (1999), S. 0 
    Details
    ISSN: 1542-474X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1542-474X.1999.tb00062.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Hypoxia and Hypothermia Enhance Spatial Heterogeneities of Repolarization in Guinea Pig Hearts: (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of cardiovascular electrophysiology 9 (1998), S. 0 
    Details
    ISSN: 1540-8167
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Spatial Autocorrelation of APDs During Arrhythmogenic Insults. Introduction: Regional dispersions of repolarization (DOR) are arrhythmogenic perturbations that are closely associated with reentry. However, the characteristics of DOR have not been well defined or adequately analyzed because previous algorithms did not take into account spatial heterogeneities of action potential durations (APDs). Earlier simulations proposed that pathologic conditions enhance DOR by decreasing electrical coupling between cells, thereby unmasking differences in cellular repolarization between neighboring cells. Optical mapping indicated that gradients of APD and DOR are associated with fiber structure and are largely independent of activation. We developed an approach to quantitatively characterize APD gradients and DOR to determine how they are influenced by tissue anisotropy and cell coupling during diverse arrhythmogenic insults such as hypoxia and hypothermia. Methods and Results: Voltage-sensitive dyes were used to map APs from 124 sites on the epicardium of Langendorff-perfused guinea pig hearts during (1) cycles of hypoxia and reoxygenation and (2) after 30 minutes of hypothermia (32° to 25°C). We introduce an approach to quantitate DOR by analyzing two-dimensional spatial autocorrelation of APDs along directions perpendicular and parallel to the longitudinal axis of epicardial fibers. A spatial correlation length l was derived as a statistical measure of DOR. It corresponds to the distance over which APDs had comparable values, where l is inversely related to DOR. Hypoxia (30 min) caused a negligible decrease in longitudinal θL (from 0.530 ± 0.138 to 0.478 ± 0.052 m/sec) and transverse θT (from 0.225 ± 0.034 to 0.204 ± 0.021 m/sec) conduction velocities and did not alter θL/θT or activation patterns. In paced hearts (cycle length [CL] = 300 msec), hypoxia decreased APDs (123 ± 18.2 to 46 ± 0.6 msec; P 〈 0.001) within 10 to 15 minutes and enhanced DOR, as indicated by reductions of l from 1.8 ± 0.9 to 1.1 ± 0.5 mm (P 〈 0.005). Hypothermia caused marked reductions of θL, (0.53 ± 0.138 to 0.298 ± 0.104 m/sec) and θT (0.225 ± 0.034 to 0.138 ± 0.027 m/sec), increased APDs (128 ± 4.4 to 148 ± 14.5 msec), and reduced l from 2.0 ± 0.3 to 1.3 ± 0.6 mm (P 〈 0.05). l decreased with increased time of hypoxia and recovered upon reoxygenation. Hypoxia and hypothermia reduced l measured along the longitudinal (l1) and transverse (lT) axes of cardiac fibers while the ratio lL/lT remained constant.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1540-8167.1998.tb00897.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Hybrid Pharmacologic and Ablative Therapy: A Novel and Effective Approach for the Management of Atrial Fibrillation (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of cardiovascular electrophysiology 9 (1998), S. 0 
    Details
    ISSN: 1540-8167
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Hybrid Therapy for Atrial Fibrillation. Introduction: Maintenance of sinus rhythm in patients with recurrent atrial fibrillation is often difficult to achieve with pharmacologic therapy. Complex catheter ablative procedures are being developed, but efficacy and safety issues remain to be clarified. We hypothesized that combined pharmacologic and simple ablative therapies in a targeted subset of patients will improve success in the treatment of atrial fibrillation.Methods and Results: We identified 13 patients (mean age 61.5 ± 16.2 years) with atrial fibrillation who converted to electrocardiographic atrial flutter during antiarrhythmic drug treatment. Surface ECG suggested “typical” atrial flutter in 11 patients and “atypical” atrial flutter in 2. Intracardiac mapping and entrainment studies revealed 9 patients had counter-clockwise isthmus-dependent atrial flutter, and the remaining 4 had complex activation patterns, suggesting the presence of multiple wavefronts. All 9 patients with typical atrial flutter underwent successful ablation. None of the 4 patients with complex activation patterns had successful ablation. Patients were followed for recurrences of atrial arrhythmias via clinic visits, record review, and interviews. In patients who underwent successful ablation and continued on antiarrhythmic drugs, 88.9% remain in sinus rhythm after a mean follow-up of 14.3 ± 6.9 months (range 1 to 28).Conclusion: In patients who experience conversion of atrial fibrillation to atrial flutter during antiarrhythmic drug treatment, ablation and continuation of pharmacologic therapy is a safe and effective means of achieving and maintaining sinus rhythm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1540-8167.1998.tb01837.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Magnitude and specificity of temporal gene expression during HIV-1 infection of a CD4+ T cell (1999)
    [s.l.] : Nature America, Inc.
    Nature genetics 23 (1999), S. 39-40 
    Details
    ISSN: 1546-1718
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Medicine
    Notes: [Auszug] We have developed an application called HAPI (High-Density Array Pattern Interpreter), which facilitates the analysis of microarray data by selecting subsets of genes with specific characteristics and displaying them with dynamic links to web-based databases. This allows comparison of subsets of ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/14288
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Activation and Repolarization Patterns are Governed by Different Structural Characteristics of Ventricular Myocardium: (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of cardiovascular electrophysiology 7 (1996), S. 0 
    Details
    ISSN: 1540-8167
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Activation and Repolarization Patterns. Introduction: Substantial progress has been made in our understanding of transmural activation across ventricular muscle through studies of excitation patterns and potential distributions. In contrast, repolarization sequences are poorly understood because of experimental difficulties in mapping action potential durations (APDs) using extracellular electrodes. Methods and Results: Langendorff-perfused guinea pig hearts and isolated coronaryperfused left ventricular sheet preparations were stained with the voltage-sensitive dye RH-421 and optical APs were recorded with a photodiode array. Epicardial maps were constructed using a triangulation method applied to matrices of activation and repolarization times determined from (dF/dt)max and (d2F/dt2)max′ respectively. Numerical simulations were carried out based on: (1) a modified Luo-Rudy model; (2) the three-dimensional architecture of ventricular fibers; and (3) the intrinsic spatial distribution of APDs. In ventricular sheets, epicardial stimulation elicited elliptical activation patterns with the major axis aligned with the longitudinal axis of epicardial fibers. When the pacing electrode was progressively inserted from epicardium to endocardium, the major axes rotated gradually, clockwise by 45°, and the eccentricity decreased from 2 to 1.14. Repolarization showed a relatively uniform pattern, independent of pacing site, beginning at the apex and spreading to the base. Conclusion: In experiments and simulations, the helical rotation of epicardial excitation isochrones caused by pacing at increasing depth in the myocardium correlated with the helical three-dimensional architecture of ventricular fibers. In contrast, repolarization was independent of the activation sequence and was mainly guided by spatial differences in APDs between apex and base.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1540-8167.1996.tb00558.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Exercise-induced hypoxemia in athletes: Role of inadequate hyperventilation (1992)
    Springer
    European journal of applied physiology 65 (1992), S. 37-42 
    Details
    ISSN: 1439-6327
    Keywords: Alveolar-arterialPO2 difference ; Pulmonary gas exchange ; VO2max ; Hypoxia ; Hyperoxia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary These experiments examined the exercise-induced changes in pulmonary gas exchange in elite endurance athletes and tested the hypothesis that an inadequate hyperventilatory response might explain the large intersubject variability in arterial partial pressure of oxygen (P a02) during heavy exercise in this population. Twelve highly trained endurance cyclists [maximum oxygen consumption (VO2max) range = 65-77 ml·kg−1·min−1] performed a normoxic graded exercise test on a cycle ergometer toVO2max at sea level. During incremental exercise atVO2max 5 of the 12 subjects had ideal alveolar to arterial P02 gradients (P A-aO2) of above 5 kPa (range 5-5.7) and a decline from restingP aO2 (ΔP aO2) 2.4 kPa or above (range 2.4-2.7). In contrast, 4 subjects had a maximal exercise (P A-aO2) of 4.0-4.3 kPa with ΔP aO2 of 0.4-1.3 kPa while the remaining 3 subjects hadP A-aO2 of 4.3-5 kPa with ΔP aO2 between 1.7 and 2.0 kPa. The correlation between PAO2 andP aO2 atVO2max was 0.17. Further, the correlation between the ratio of ventilation to oxygen consumption VSP aO2 and arterial partial pressure of carbon dioxide VSP aO2 atVO2max was 0.17 and 0.34, respectively. These experiments demonstrate that heavy exercise results in significantly compromised pulmonary gas exchange in approximately 40% of the elite endurance athletes studied. These data do not support the hypothesis that the principal mechanism to explain this gas exchange failure is an inadequate hyperventilatory response.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01466272
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Software for teaching physiology and biophysics (1992)
    Springer
    Journal of science education and technology 1 (1992), S. 259-274 
    Details
    ISSN: 1573-1839
    Keywords: Educational software ; biophysics software ; physiological software ; bioengineering software ; Hodgkin-Huxley model software ; diffusion software ; single voltage-gated channel software
    Source: Springer Online Journal Archives 1860-2000
    Topics: Natural Sciences in General , Technology
    Notes: Abstract We describe a software library that we have developed to teach biophysics and physiology to undergraduate engineering and science students as well as to medical students. The library, which is under development, now includes software on: (1) the Hodgkin-Huxley model for excitation of action potentials in electrically excitable cells (such as nerve and muscle cells); (2) a random-walk model of diffusion; (3) single voltage-gated ion channels; (4) steady-state chemically mediated transport; and (5) macroscopic diffusion processes. The software is used in a variety of ways: as an integral part of lectures, as the basis of special sessions held in electronic classrooms, as a source of homework assignments, and for special projects defined by the students. We describe the software and some of the pedagogic methods we have used.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00694407
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Mechanisms and dynamics of mechanical strengthening in ligament-equivalent fibroblast-populated collagen matrices (1993)
    Springer
    Annals of biomedical engineering 21 (1993), S. 289-305 
    Details
    ISSN: 1573-9686
    Keywords: Collagen ; Fibroblasts ; Ligament ; Stiffness ; Crosslink ; Collagen gel ; Breaking strength
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract We have measured the dynamics of extracellular matrix consolidation and strengthening by human dermal fibroblasts in hydrated collagen gels. Constraining matrix consolidation between two porous polyethylene posts held rigidly apart set up the mechanical stress which led to the formation of uniaxially oriented fibroblast-populated collagen matrices with a histology resembling a ligament. We measured the mechanical stiffness and tensile strength of these ligament equivalents (LEs) as a function of age at biweekly intervals up to 12 weeks in culture using a mechanical spectrometer customized for performing experiments under physiologic conditions. The LE load-strain curve changed as a function of LE age, increasing in stiffness and exhibiting less plastic-like behavior. At 12 weeks, LEs had acquired up to 30 times the breaking strength of 1-week-old LEs. Matrix strengthening occurred primarily through the formation of BAPN-sensitive, lysyl oxidase catalyzed crosslinks. Sulfated glycosaminoglycan (GAG) content increased monotonically with LE age, reaching levels that are characteristic of ligaments. Cells in the LEs actively incorporated [3H]proline and [35S]sulfate into the extracellular matrix. Over the first three weeks, DNA content increased rapidly but thereafter remained constant. This data represent the first documentation of strengthening kinetics for cell-assembled biopolymer gels and the results suggest that this LE tissue may be a valuable model for studying the cellular processes responsible for tissue growth, repair, and remodeling.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02368184
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...