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Biomedical subjects

W L Mosterd

Publications and source records attributed to W L Mosterd.

9 recordsLinked to original sources
PubMed1995

Hemorheological response to prolonged exercise--no effects of different kinds of feedings.

Thirty-one male triathletes performed three experimental trials at one week intervals, with either a semi-solid or liquid carbohydrate feeding, or a liquid placebo. Exercise consisted of three hours of alternately cycling, running, cycling, and running at 75% VO2 max. Venous blood samples were taken before and immediately after the exercise. Viscometry was performed with a Contraves LS-30 viscometer and erythrocyte deformability was measured with the LORCA, a laser diffractometric system. Exercise caused a significant increase in whole blood and plasma viscosity, hematocrit, and osmolality, and a very small, but significant decrease in erythrocyte deformability, irrespective of the feedings consumed. Changes were not related to exercise performance, as defined by the maximal test time, probably due to a large fluid intake. The intake of different amounts of carbohydrate had no influence on the hemorheological parameters, probably since water content was equal among feedings. Erythrocyte deformability changes were small in comparison with the other hemorheological changes and a correlation between erythrocyte deformability and other parameters was absent. This may be due to erythrocyte properties to counterbalance volume shifts to ensure an optimal oxygen delivery in the microcirculation.

Adult↗
PubMed1994

Direct recording of EDP-EDV relationship in isolated rat left ventricle: effect of diastolic crossbridge formation.

OBJECTIVE: The aim was to investigate whether the end diastolic pressure-end diastolic volume (EDP-EDV) relationship of the left ventricle can be influenced by calcium dependent elements, especially at low values of end diastolic pressure. METHODS: Isolated rat hearts were perfused in a modified Langendorff perfusion system. The EDP-EDV relationship of the left ventricle was investigated. Pressure was recorded with a microtip pressure catheter and volume with a microconductance catheter. Crossbridge cycling was affected by adding calcium antagonists (verapamil, diltiazem, nifedipine at 2.10(-7) M) or by adding the Mg-ATPase blocker BDM (2,3-butanedione-2-monoxime, 10(-3) M) to the perfusate. RESULTS: The above had a negative inotropic effect in systole. At EDP = 0 after stimulation the active isovolumetric pressure was zero. In diastole, BDM shifted the EDP-EDV relationship to slightly smaller EDVs. A decrease of about 5% in the EDV was found at lower EDP values. Ca2+ antagonists increased the EDV up to 40-80% at low EDP values. At higher EDP values only a small increase of EDV (about 10%) was found after verapamil perfusion. The results obtained are interpreted in terms of a three step crossbridge model. CONCLUSIONS: At low EDP, diastolic volume is dependent upon weakly bound crossbridges as a function of the [Ca2+] in the cardiac cell.

Animals↗
PubMed1994

Physical inactivity as a risk factor for coronary heart disease: a WHO and International Society and Federation of Cardiology position statement.

Coronary heart disease is responsible for a considerable amount of the morbidity and mortality from chronic diseases in industrialized countries. Many countries have therefore adopted prevention policies designed to reduce the prevalence of three of the major risk factors for coronary heart disease--high serum cholesterol, smoking, and high blood pressure. Physical inactivity is, however, also an important risk factor for developing coronary heart disease. This article presents a position statement by WHO and the International Society and Federation of Cardiology on physical inactivity and coronary heart disease.

Coronary Disease↗
PubMed1994

Differences in u-PA and t-PA increase during acute exercise: relation with exercise parameters.

Plasma levels of urokinase-type (u-PA Ag) and tissue-type (t-PA Ag) plasminogen activator are both enhanced during physical exercise. Whether, the extent of the increase and the post-exercise clearance rate of the two activators are comparable is not known. We studied the changes in u-PA Ag, t-PA Ag and t-PA activity during a standardized exercise test comprising submaximal and maximal exercise intensity. During submaximal (recreational) exercise, increases in u-PA are mainly due to changes in plasma volume, submaximal exercise demonstrates a continuous rise in level of t-PA Ag. During maximal performance peak levels of u-PA and t-PA Ag do not coincide in time and magnitude, moreover, u-PA Ag rather than t-PA Ag is related to t-PA Act. From these results we conclude that independent mechanisms regulate the exercise-induced plasma levels of u-PA and t-PA.

Adult↗
PubMed1990

A double-blind randomized multicenter dose-ranging trial of intravenous streptokinase in acute myocardial infarction.

Intravenous streptokinase administration is now a widely applied therapy for patients in the early hours of acute myocardial infarction (AMI). The dosages used do not appear to be based on comparative clinical investigations. Therefore a double-blind randomized trial was carried out to establish the optimal dose of streptokinase. A total of 189 patients who had symptoms of AMI for less than 4 hours were treated with 200,000, 750,000, 1,500,000 or 3,000,000 IU streptokinase intravenously. At coronary angiography 2.8 +/- 2.7 hours (mean +/- standard deviation) after the start of streptokinase infusion, patency of the infarct-related coronary artery was observed in 38, 75, 60 and 82% of the patients, respectively, in the 4 groups. The result of the dosage of 200,000 IU was significantly poorer than that of the other dosages (p less than 0.01). The result of a dosage of 3,000,000 IU was significantly better than that of 1,500,000 IU (p less than 0.05), but the differences with 750,000 IU were not significant. Blood transfusion was required in 4 patients (2%), distributed over the 4 groups in 0, 2, 1 and 1 of the patients. One patient had major bleeding; this patient had been treated with 750,000 IU. The 3-month mortality-rate in the whole study population was 5%. Thus, of the 4 doses of streptokinase tested, 750,000 IU is the minimal therapeutic dosage, and the arguments for 1,500,000 IU as standard therapy for comparison with other fibrinolytic drugs are poor. The best results in this study were achieved with 3,000,000 IU, but further research will be needed to establish the efficacy and safety of this new regimen.

Aged↗