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  • 1
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 591 (1990), S. 0 
    ISSN: 1749-6632
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Allgemeine Naturwissenschaft
    Materialart: Digitale Medien
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  • 2
    ISSN: 1435-1803
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Bei 12 Versuchshunden wurde die Technik nachSalazar zur Erzeugung von elektrisch induzierten Koronarthrombosen angewandt. Als Kontrolle dienten weitere 6 Hunde. Elektrokardiographische, hämodynamische, biochemische und hämatologische Untersuchungen wurden vor, während und 24 Stunden nach elektrischer Reizung durchgeführt. Bei allen Versuchshunden (mit elektrischer Reizung) traten innerhalb von 2 Stunden nach Thrombusbildung Rhythmusstörungen auf. Aufgrund des Anstiegs von SGOT und SGPT wurden Myokardnekrosen nachgewiesen, dagegen waren die beobachteten hämodynamischen Veränderungen sehr gering. Licht- und elektronenmikroskopische Untersuchungen der Koronararterien zeigten schwere Läsionen der Gefäßwände nach Katheterisierung der Koronararterien. Ein intrakoronarer Thrombus wurde bei allen Tieren nach Anwendung elektrischer Ströme gefunden, ebenso jedoch auch bei 2 Kontrollhunden. Diese Untersuchungen zeigen, daß für die Bildung von Thrombosen der Koronararterien unterschiedliche Ursachen verantwortlich zu machen sind. Dieses Myokardinfarkt-Modell am nicht eröffneten Thorax ist zur Untersuchung frühzeitiger Rhythmusstörungen geeignet, besonders wegen des häufigen Auftretens der Dysrhythmien bei niedriger Mortalität. Das Modell erscheint jedoch nicht dafür geeignet, neue Arzneimittel mit antithrombotischer Wirkung zu testen, weil die Ursache der Thrombusbildung vielfältig und nicht kontrollierbar ist.
    Notizen: Summary TheSalazar technique for electrical induction of coronary thrombosis, was used in 12 dogs, whereas a control procedure was followed in 6 other dogs. Electrocardiographic, hemodynamic, biochemical and hematological studies were carried out before, during and 24 hours after electrical stimulation. Chaotic rhythm appeared in all electrically stimulated dogs 24 hours after thrombus formation. Muscle necrosis was evident as indicated by the increase in SGOT and SGPT, but the observed hemodynamic changes were rather small. Light and electron microscopic studies of the coronary arteries showed important lesions in the vessel wall of the catheterized coronary arteries and an intracoronary thrombus was found in all the animals electrically stimulated as well as in two control dogs. These studies also revealed a multiple origin of coronary artery thrombus formation. This closed chest model for acute myocardial infarction is well suitable for the study of early dysrhythmias, especially because of the high incidence of dysrhythmia and the low mortality rate. The model is not suitable to study new chemical compounds with anti-thrombotic activity, because of the multiple uncontrollable origin of the coronary thrombus.
    Materialart: Digitale Medien
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  • 3
    ISSN: 1432-0428
    Schlagwort(e): Keywords Insulin resistance ; arterial stiffness ; healthy subjects ; women ; population.
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Aims/hypothesis. The insulin resistance syndrome is related to arterial stiffness in diabetic subjects. Whether the insulin resistance syndrome is also related to arterial stiffness in non-diabetic subjects is less clear. We studied the association between variables of the insulin resistance syndrome in relation to arterial distensibility in healthy middle-aged non-diabetic women. Methods. This study was done in 180 non-diabetic women, aged 43–55, selected from the general population. Arterial distensibility was assessed in the carotid artery. The associations were evaluated using linear regression analyses. Results. Strong associations were found between arterial distensibility and the variables of the insulin resistance syndrome: body mass index, waist-to-hip ratio, high-density-lipoprotein-cholesterol, triglycerides, glucose, insulin, apolipoprotein A1, plasminogen activator inhibitor-1-antigen and tissue-type plasminogen activator-antigen. After additional adjustment for mean arterial pressure, common carotid arterial distensibility remained associated with body mass index: β-coefficient (95 % confidence interval) per kg/m2: –0.24 (–0.42; –0.06); waist-to-hip ratio: –26.62 (–40.59; –12.65) per m/m; triglycerides: –1.42(–2.77; –0.08) per mmol/l; plasminogen activator inhibitor–1-antigen: –0.01 (–0.02; –0.00) per ng/ml and borderline significant associated with high-density-lipoprotein-cholesterol: 1.93 (–0.01; 3.87; p = 0.07) per mmol/l. Clustering of variables of the insulin resistance syndrome was strongly related to decreased arterial distensibility which remained after adjustment for mean arterial pressure. No association was found between arterial distensibility and variables that are not part of the insulin resistance syndrome: total cholesterol, LDL-cholesterol and apolipoprotein B. Conclusion/interpretation. The results of this study show that variables of the insulin resistance syndrome are associated with decreased arterial distensibility of the common carotid artery in healthy non-diabetic subjects. [Diabetologia (2000) 43: 665–672]
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Inflammation research 15 (1984), S. 612-626 
    ISSN: 1420-908X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The evidence for an impact of platelet-derived 5-hydroxytryptamine (5-HT) on local tissue perfusion is reviewed. By interacting with 5-HT2 serotonergic receptors, 5-HT, directly or through amplification, activates platelets, endothelial and vascular smooth muscle cells producing platelet aggregation, vascular permeability increase and large vessel constriction. Pharmacodissection in experimental animals with selective serotonergic 5-HT2 receptor antagonists, e.g. ketanserin, shows that 5-HT largely contributes to the platelet-mediated increase in vascular permeability, to platelet-vessel wall interaction during hemostasis, to cardiopulmonary dysfunction provoked by thromboembolism and to the platelet-mediated inhibition of peripheral collateral circulation. Clinical results obtained with ketanserin further substantiate an involvement of platelet-derived 5-HT in the pathogenesis of impaired tissue perfusion in some cardiovascular conditions.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 278 (1973), S. 261-269 
    ISSN: 1432-1912
    Schlagwort(e): Platelets ; Serotonin Storage ; Lidoflazine ; Dipyridamole
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary At low concentrations in vitro (starting at 5×10−8 M), lidoflazine reduces the velocity of serotonin uptake by human platelets suspended in Tyrodealbumin. Inhibition is of a non-competitive type and is not enhanced by prolonged compound incubation. At higher concentrations (starting at 1.6×10−6 M) lidoflazine causes release of radioactive serotonin from platelets. The extent of release is dependent on concentration, duration of incubation and temperature and is not reduced by calcium chelation or papaverine pre-treatment. Similar but less pronounced effects on uptake and release reactions occur with dipyridamole. The possible mode of action of lidoflazine on platelet storage of serotonin is discussed.
    Materialart: Digitale Medien
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  • 6
    ISSN: 1432-2013
    Schlagwort(e): Pyruvate ; Transient ischemia ; Adenine nucleotides ; Enzyme release ; Workload ; Working rat heart
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract In the present study the hemodynamic and metabolic effects of pyruvate (5 mM), added as cosubstrate to glucose (11 mM) perfused, transiently ischemic, isolated working rat hearts, were evaluated. During 2 h of normoxic perfusion pyruvate improved functional stability, prevented depletion of glycogen and triacylglycerol stores, and increased non-esterified fatty acid (NEFA) levels, even at relatively high workloads. The elevated NEFA levels are in line with the notion that pyruvate competes with endogenously produced fatty acids for oxidative energy production. After 45 min of global ischemia pyruvate was found (a) to affect markedly the relative contribution of ATP, ADP and AMP to the total adenine nucleotide content and (b) to stimulate the degradation of glycogen and to enhance the accumulation of lactate, suggesting enhanced anaerobic ATP rroduction. After restoration of flow pyruvate reduced the incidence of fibrillation and markedly improved recovery of cardiac output at both normal and high workload. Pyruvate did neither attenuate the release of lactate dehydrogenase, a marker for cell death, nor improve the conservation of the total adenine nucleotide and ATP content of hearts reperfused for 30 min. The latter findings indicate that hemodynamic recovery during reperfusion in the presence of pyruvate is neither related to the absolute tissue content of ATP nor to a reduction of irreversible cell damage, and suggest that pyruvate exerts its advantageous hemodynamic effects rather by improving the condition of reversibly damaged cells during reperfusion.
    Materialart: Digitale Medien
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  • 7
    ISSN: 1432-2013
    Schlagwort(e): Radioactive Microspheres ; Regional Myocardial Blood Flow ; Diameter Distribution of Microspheres ; Coronary Artery Occlusion
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary In this study, we have tried to determine the magnitude of the inaccuracy of the radioactive microsphere method — due to variations in the diameter distribution of the spheres — for measuring regional myocardial blood flow after coronary artery occlusion. In 5 mongrel dogs, three types of 15 μm microsperes, labelled with125I,141Ce or85Sr, were injected simultaneously after the descending branch of the left coronary artery had been ligated. Myocardial samples were taken from the left ventricle and divided into four groups according to the number of spheres per sample. The radioactivity of the various isotopes per gram tissue was expressed as percentage of their activity per milliliter of the reference sample. The diameter distribution of microspheres, labelled with each of the isotopes, was determined light-microscopically in suspensions belonging to three different batches. The relative error, as determined from the difference in relative radioactivity of the various types of microspheres in the tissue samples, was higher than the theoretical error for each of the number of spheres per sample. It is very likely that this discrepancy is caused by the differences in diameter distribution of the various types of microspheres, resulting in non-random error. The smaller spheres tended to go to low flow areas and the larger ones to high flow areas. Because of the non-randomness, the error due to diameter variations in the spheres can be diminished by randomizing the order of injection of the various isotopes. The present study indicates that the relatively high degree of accuracy of the microsphere method for the determination of blood flow to large parts of the myocardium with an unimpeded coronary circulation, as was described in literature, cannot be extrapolated to the determination of regional myocardial blood flow after coronary artery occlusion, when the combination of small tissue samples, variations in the diameter distribution of the spheres and an unevenly distributed myocardial blood flow unfavourably affect the accuracy of the method.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    Springer
    Pflügers Archiv 340 (1973), S. 35-50 
    ISSN: 1432-2013
    Schlagwort(e): Myocardial Wall Thickness ; Strain Gauge Device ; Coronary Artery Occlusion ; Reactive Hyperemia ; Isoprenaline
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Changes in left ventricular myocardial wall thickness (MWT) were studied in open-chest dogs using a specially designed strain gauge device. The total systolic increase in MWT was 10%, of which about 30% occurred during the isovolumic phase of contraction. These values are lower than those obtained with cineradiographic techniques. A possible explanation for this divergency is discussed. Calculation of MWT changes showed that increases between 7% and 18% are required to eject resting stroke volumes. Intravenous injections of isoprenaline showed a log dose-dependent augmentation of the total increase in MWT during systole. Coronary artery occlusion resulted in a fall in the total systolic MWT increase and a decrease in MWT at the end of diastole, which can both be explained by an increase in left ventricular end-diastolic volume. The temporary rise in total systolic MWT increase over the control value, following release of a prolonged occlusion, disappeared when an induced coronary artery stenosis had abolished diastolic reactive hyperemia. This indicates a relationship between coronary blood flow and the extent of total MWT increase in systole.
    Materialart: Digitale Medien
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  • 9
    ISSN: 1432-1041
    Schlagwort(e): Hypercholesterolaemia ; HMG-CoA-reductase inhibitors ; Pravastatin ; vessel wall properties ; arterial distensibility ; arterial compliance
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract Hypercholesterolaemia is a risk factor for atherosclerosis and induces endothelial dysfunction. Endothelial dysfunction may increase vascular tone and arterial stiffness and as a consequence may decrease arterial distensibility (DC) and arterial compliance (CC). It is hypothesized that lipid-lowering therapy may enhance DC and CC. Therefore, the present study investigates the effect of lipid-lowering therapy with pravastatin on the haemodynamics, DC and CC of the elastic common carotid artery (CCA), and the muscular femoral (FA) and brachial (BA) arteries in patients with primary hypercholesterolaemia. After an 8-week placebo run-in period with a low-cholesterol diet, 19 patients with total cholesterol concentrations of between 6.5 and 9.0 mmol·l−1 and triglyceride concentrations 〈4 mmol·l−1 entered a double-blind placebo controlled crossover study. Patients received pravastatin 40 mg o.d. or placebo, each for 8 weeks. Throughout the study the lipid-lowering diet was continued. With pravastatin, total cholesterol, low-density lipoprotein cholesterol (LDL-C) and triglycerides were decreased (total cholesterol 26%, LDL-C 35%, triglycerides 16%), while high-density lipoprotein cholesterol (HDL-C) was not changed. Other laboratory values remained within the normal range. Blood pressure, heart rate, cardiac function and systemic vascular resistance were not influenced by pravastatin. Compared to placebo, diameter, distensibility and compliance of all arteries were not statistically significantly changed with pravastatin. These data suggest that, in patients with mild to moderate primary hypercholesterolaemia, short-term lowering of plasma cholesterol does not alter the haemodynamics and vessel wall properties of large arteries.
    Materialart: Digitale Medien
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  • 10
    ISSN: 1432-1041
    Schlagwort(e): ketanserin ; intermittent claudication ; Doppler velocimetry ; capillary microscopy ; macro/microcirculation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The effect of ketanserin on macrocirculatory and microcirculatory blood flow was investigated in a placebo-controlled, double-blind trial in 11 patients suffering from intermittent claudication using Doppler velocimetry and intravital skin capillary microscopy, respectively. After 1 year of treatment no significant change was observed either in the ketanserin or the placebo group. It appears that ketanserin has no significant effect on macrocirculatory blood flow and microcirculatory nutritional skin blood flow in patients with intermittent claudication.
    Materialart: Digitale Medien
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