121,901 research outputs found
Levosimendan improves diastolic and systolic function in failing human myocardium
No full textCa2+-sensitizers increase myocardial contractility, but may worsen diastolic dysfunction. Levosimendan, through its unique troponin-C interaction, may preserve diastolic function. We investigated the effects of levosimendan (10(-7)-10(-5) M) on diastolic and systolic function in multicellular cardiac muscle preparations from end-stage failing human hearts (1 and 2.5 Hz, 37 degrees C, 1.25 mM [Ca2+], pH 7.4). Levosimendan improved systolic function: at 1 Hz, developed force (F-dev) increased from 13.84 +/- 3.27 to 16.40 +/- 3.57 (10(-7) M, P < 0.05), while diastolic force (F-dia) decreased from 5.32 +/- 0.67 to 4.94 +/- 0.61 mN/mm(2) (P < 0.05). Under control conditions, the increase in stimulation frequency from 1 to 2.5 Hz resulted in a decrease in F-dev of - 0.51 +/- 1.80 mN/mm(2) (negative force-frequency relationship). Levosimendan improved this relationship: at 10-7 M, this change became positive (+1.81 +/- 2.06 mN/mm(2), P < 0.05). Diastolic function was markedly improved in the presence of levosimendan; the increase in F-dia of 1.56 +/- 0.41 mN/mm(2) (control) was attenuated to 0.70 +/- 0.19 nN/mm(2) (P < 0.05). To allow for a more derailed analysis, preparations were sometimes divided into two groups, based on their force-frequency behavior. Twitch timing parameters were accelerated by levosimendan in preparations with a negative force-frequency relationship. Levosimendan improves both systolic and diastolic function in failing human myocardium. Effects are even more pronounced at higher heart rates and under prevailing diastolic dysfunction. (C) 2000 Elsevier Science B.V. All rights reserved
Spin asymmetries in elastic and inelastic scattering of spin-polarized electrons from spin-polarized cesium atoms
No full textBaum G, Pavlovic N, Roth B. Spin asymmetries in elastic and inelastic scattering of spin-polarized electrons from spin-polarized cesium atoms. In: Burgdörfer J, Cohen JS, Datz S, Vance CR, eds. Photonic, Electronic & Atomic Collisions. Princeton: Rinton Press; 2001: 460-470
Potentiation of beta-adrenergic inotropic response with pyruvate in failing human heart and in healthy rabbit myocardium
No full text
A Multi-Language Comparison of Influences on Author Verification using Character N-Grams
No full textWe create a new multi-language corpus for author verification based on Wikipedia talkpages, and evaluate the influence that differences in topic and time have on character n-gram author profiles. Topic alignment between two texts is found to increase author verification precision, and an authors writing style is found to change over time, but not more significantly after 3 years than after 1 year.Information ArchitectureWISElectrical Engineering, Mathematics and Computer Scienc
Potentiation of beta-adrenergic inotropic response with pyruvate in failing human heart and in healthy rabbit myocardium
No full textAppropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
The vanishing author in computer-generated works: a critical analysis of recent Australian case law
No full textAbstract
The use of software is ubiquitous in the creation of many copyright works, yet the requirement in copyright law that every work have a human author who engages in independent intellectual effort means that its use may prevent copyright subsistence. Several recent Australian cases have refocused attention on authorship as an essential criterion of copyright subsistence, and these cases suggest that much computer-produced output may be authorless and thus lack copyright protection. This article, the first in a two-part series, analyses how each case deals with the question of authorship of computer-produced works and why the use of software diminishes copyright protection for a significant number of computer-generated works. The article critiques the application of conventional notions of human authorship developed in the pre-computer age to modern productions and suggests alternative approaches to authorship that satisfy both the major objectives of copyright policy and the need to adapt to the computer age. The article argues that, without a broader judicial approach to authorship of computer-generated works, Parliament must remedy the lacuna in protection for these ‘authorless’ works. Possible solutions for reform are suggested. In a forthcoming article, the author comprehensively examines those reform proposals
Potentiation of beta-adrenergic inotropic response by pyruvate in failing human myocardium
No full textBackground: Pyruvate has been shown to increase contractile function in isolated myocardium and to improve hemodynamics in patients with congestive heart failure. We tested the hypothesis that pyruvate potentiates the inotropic response beta-adrenergic stimulation and to elevated extracellular calcium, since this may be of potential therapeutic value in the clinical setting of acute heart failure in order to circumvent deleterious effects on energy demand as can occur during catecholamine therapy. Methods and Results: We investigated isometrically contracting isolated multicellular muscle preparations from terminal failing human hearth at 37degreesC, pH 7.4, and a stimulation frequency of I Hz. At an extracellular calcium concentration of 1.25 mM, pyruvate ( 10 mM) alone increased developed force (F-dev) from 9.0+/-2.3 to 21.1+/-4.3 mN/mm(2) (n=9, P<0.001) and isoproterenol (1 muM) alone increased F-dev from 9.5+/-2.0 to 31.3+/-5.4 mN/mm(2) (P<0.001), whereas the combination of pyruvate and isoproterenol increased F-dev over-proportionally from 9.0+/-2.3 to 47.4+/-6.4 mN/mm(2) (P<0.01). In a separate series we assessed the combination of pyruvate and calcium. Although F-dev did not increase from 12 to 16 mM [Ca2+](o), 10 mM pyruvate further increased F-dev from 25.8+/-5.0 to 30.6+/-4.7 mN/mm(2) (P<0.01). Rapid cooling contractures revealed that altered myofilament responsiveness and/or sarcoplasmic reticulum (SR) calcium load must underlie the positive inotropic effect of pyruvate. Conclusion: A combination of pyruvate and P-adrenergic stimulation may be of therapeutic value in acute heart failure by reducing the concentrations of potential deleterious catecholamines that are currently necessary to maintain adequate tissue perfusion. (C) 2002 Elsevier Science BY All rights reserved
- …
