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Biomedical subjects

M Grunze

Publications and source records attributed to M Grunze.

35 records · Page 2Linked to original sources
PubMed1993

Various intensities of leisure time physical activity in patients with coronary artery disease: effects on cardiorespiratory fitness and progression of coronary atherosclerotic lesions.

OBJECTIVES: This study was designed to define the effect of different levels of leisure time physical activity on cardiorespiratory fitness and progression of coronary atherosclerotic lesions in unselected patients with coronary artery disease. BACKGROUND: It has been shown in various studies that regression of coronary atherosclerotic lesions can be achieved by means of lipid-lowering drugs, reduction of fat consumption and physical exercise. METHODS: Patients were prospectively randomized either to an intervention group (n = 29) participating in regular physical exercise or to a control group (n = 33) receiving usual care. Energy expenditure in leisure time physical activity was estimated from standardized questionnaires and from participation in group exercise sessions. After 12 months of participation, repeat coronary angiography was performed; coronary lesions were measured by digital image processing. RESULTS: After 1 year, patients in the intervention group achieved an increase in oxygen uptake at a ventilatory threshold of 7% (p < 0.001) and peak exercise of 14% (p < 0.05), whereas a significant decrease was observed in patients in the control group. To achieve significant improvement in cardiorespiratory fitness, approximately 1,400 kcal/week had to be expended in the form of leisure time physical activity (p < 0.001). The mean energy expended in such activity was 1,876 +/- 163 kcal/week in the intervention group and 1,187 +/- 97 kcal/week in the control group (p < 0.001). In the intervention group, regression of coronary artery disease was noted in 8 patients (28%), progression of disease in 3 (10%) and no change in coronary morphology in 18 (62%). In contrast, coronary artery disease progressed at a significantly faster rate in patients in the control group (progression in 45%, no change in 49% and regression in 6%) (p < 0.001 vs. intervention). When the two groups were combined, the lowest level of leisure time physical activity was noted in patients with progression of disease (1,022 +/- 142 kcal/week) as opposed to patients with no change (1,533 +/- 122 kcal/week) or regression of disease (2,204 +/- 237 kcal/week) (p < 0.005). CONCLUSIONS: Measurable improvement in cardiorespiratory fitness requires approximately 1,400 kcal/week of leisure time physical activity; higher work loads are necessary to halt progression of coronary atherosclerotic lesions (1,533 +/- 122 kcal/week), whereas regression of coronary lesions is observed only in patients expending an average of 2,200 kcal/week in leisure time physical activity, amounting to approximately 5 to 6 h/week of regular physical exercise.

Coronary Angiography↗
PubMed1992

Myocardial perfusion and regression of coronary artery disease in patients on a regimen of intensive physical exercise and low fat diet.

This intervention program tested the applicability and effects of intensive physical exercise and a low fat diet on progression of coronary atherosclerotic lesions and stress-induced myocardial ischemia in patients with stable angina pectoris. Eighteen patients participated in this program for 1 year; they consumed a low fat, low cholesterol diet (less than 20 energy % fat, cholesterol less than 200 mg/day) and exercised for greater than 3 h/week. Change in coronary morphology was assessed by angiography and digital image processing; stress-induced myocardial ischemia was measured by thallium-201 scintigraphy. Results were compared with those in patients receiving "usual care." In the intervention group, significant regression of coronary atherosclerotic lesions was noted in 7 of the 18 patients; no change or progression was present in 11 patients. In patients receiving usual care, regression was detected in only 1, with no change or progression in 11 patients (different from intervention, p less than 0.05). There was a significant reduction in stress-induced myocardial ischemia, which was not limited to patients with regression of coronary atherosclerotic lesions. Thus, regular physical exercise and a low fat diet may retard progression of coronary artery disease; however, improvement of myocardial perfusion may be achieved independently from regression of stenotic lesions.

Angiography, Digital Subtraction↗
PubMed1992

Regular physical exercise and low-fat diet. Effects on progression of coronary artery disease.

BACKGROUND: Significant regression of coronary and femoral atherosclerotic lesions has been documented by angiographic studies using aggressive lipid-lowering treatment. This study tested the applicability and effects of intensive physical exercise and low-fat diet on coronary morphology and myocardial perfusion in nonselected patients with stable angina pectoris. METHODS AND RESULTS: Patients were recruited after routine coronary angiography for stable angina pectoris; they were randomized to an intervention group (n = 56) and a control group on "usual care" (n = 57). Treatment comprised intensive physical exercise in group training sessions (minimum, 2 hr/wk), daily home exercise periods (20 min/d), and low-fat, low-cholesterol diet (American Heart Association recommendation, phase 3). No lipid-lowering agents were prescribed. After 12 months of participation, repeat coronary angiography was performed; relative and minimal diameter reductions of coronary lesions were measured by digital image processing. Change in myocardial perfusion was assessed by 201Tl scintigraphy. In patients participating in the intervention group, body weight decreased by 5% (p less than 0.001), total cholesterol by 10% (p less than 0.001), and triglycerides by 24% (p less than 0.001); high density lipoproteins increased by 3% (p = NS). Physical work capacity improved by 23% (p less than 0.0001), and myocardial oxygen consumption, as estimated from maximal rate-pressure product, by 10% (p less than 0.05). Stress-induced myocardial ischemia decreased concurrently, indicating improvement of myocardial perfusion. Based on minimal lesion diameter, progression of coronary lesions was noted in nine patients (23%), no change in 18 patients (45%), and regression in 13 patients (32%). In the control group, metabolic and hemodynamic variables remained essentially unchanged, whereas progression of coronary lesions was noted in 25 patients (48%), no change in 18 patients (35%), and regression in nine patients (17%). These changes were significantly different from the intervention group (p less than 0.05). CONCLUSIONS: In patients participating in regular physical exercise and low-fat diet, coronary artery disease progresses at a slower pace compared with a control group on usual care.

Adult↗
PubMed1991

[Modification of risk factors through physical training and low-fat diet].

This intervention program investigated the applicability and the effects of intensive physical exercise and low-fat diet on the progression of coronary atherosclerotic lesions and stress induced myocardial ischemia in patients with stable angina pectoris. Patients participating in this study were recruited following routine coronary angiography for angina pectoris. Inclusion criteria were male sex, stable symptoms, a willingness to participate in the study for at least twelve months, and coronary artery stenoses well documented by angiography. Exclusion criteria were unstable angina pectoris, left main coronary artery stenosis greater than 25% luminal diameter reduction, severely depressed left ventricular ejection fraction (less than 35%), significant valvular heart disease, insulin-dependent diabetes mellitus, primary hypercholesterolemia (type II hyperlipoproteinemia, low-density lipoprotein greater than 210 mg/dl), and conditions precluding regular physical exercise. 18 patients participated in this program for one year; they consumed a low-fat, low-cholesterol diet (less than 20 energy % fat, cholesterol less than 200 mg/day) and exercised for more than 3 h/week. Myocardial oxygen consumption was estimated from maximum rate-pressure product at peak exercise; it was correlated to stress induced myocardial ischemia, as measured by 201Tl-scintigraphy. Results were compared with those of 18 matched patients on "usual care". In the intervention group, physical work capacity (161 +/- 34 W vs. 194 +/- 42 W) and maximum rate pressure product (25.0 +/- 6.3 x 10(3) vs. 27.2 +/- 5.3 x 10(3)) increased significantly (p less than 0.01). Patients willing to devote time and effort to intensive physical exercise and to comply with a low-fat diet may benefit from this form of therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Artery Disease↗
PubMed1990

Mechanisms of improved physical performance of chronic hemodialysis patients after erythropoietin treatment.

Correction of the anemia that is common among chronic hemodialysis patients by treatment with human recombinant erythropoietin (rHuEPO), even if incomplete, improves physical performance of patients. Oxygen uptake and physical work capacity at maximal work loads and at the anaerobic threshold increase by approximately 20%. Analysis of underlying mechanisms by pulmonary function tests and ergospirometry demonstrate that improved oxygen transport in the blood and its concomitant changes of the anaerobic threshold and heart rate appear to be main causes of improvement. Parameters of respiratory mechanics and gas exchange remain essentially unaltered.

Adult↗
PubMed1986

The surface charge of human glutaraldehyde-fixed erythrocytes.

We measured the number of charged residues at the surface of fresh human erythrocytes after fixation with glutaraldehyde by polyelectrolyte titration using polycations of different chemical composition and various molecular weights. Independent of the reagents used, the number was (8.5 +/- 1.5) X 10(8) negatively charged residues per cell. The surface charge density of 6.3 e/nm2 is considerably higher than that calculated from the electrophoretic mobility for which the surface charge density is calculated to be 0.09 e/nm2.

Aldehydes↗
PubMed1985

Kinetics of 13N-ammonia uptake in myocardial single cells indicating potential limitations in its applicability as a marker of myocardial blood flow.

To study kinetics and principles of cellular uptake of 13N-ammonia, a marker of coronary perfusion in myocardial scintigraphy, heart muscle cells of adult rats were isolated by perfusion with collagenase and hyaluronidase. Net uptake of 13N, measured by flow dialysis, reached equilibrium within 20 sec in the presence of sodium bicarbonate and carbon dioxide (pH 7.4, 37 degrees C). Total extraction, 80 sec after the reaction start, was 786 +/- 159 mumol/ml cell volume. Cells destroyed by calcium overload were unable to extract 13N-ammonia. Omission of bicarbonate and carbon dioxide reduced total extraction to 36% of control. 13N-Ammonia uptake could also be reduced by 50 muM 4,4' diisothiocyanostilbene 2,2' disulfonic acid, by 100 micrograms/ml 1-methionine sulfoximine, and by preincubation with 5 muM free oleic acid. These results indicate that in addition to metabolic trapping by glutamine synthetase, the extraction of 13N-ammonia by myocardial cells is influenced by cell membrane integrity, intracellular-extracellular pH gradient, and possibly an anion exchange system for bicarbonate. For this reason, the uptake of 13N-ammonia may not always provide a valid measurement of myocardial perfusion.

Ammonia↗
PubMed1985

[Quantitative determination of diaphragmatic motility using ultrasound. Comparison with pulmonary function test parameters and thoracic radiography].

Sonography, combined with a geometrical simulation-model, can be used to estimate parameters of pulmonary function tests (PFT). The sensitivity for changes of PFT may be increased by repetitive examinations. This simple inexpensive method is easily reproducible. Additional information concerning diaphragmatic motility is obtained. The value of this method is improved by taking geometric parameters directly from chest radiograph using a suitable computer program.

Adolescent↗
PubMed1982

Lateral segregation of membrane lipids and formation of stable rod-shaped membrane projections in erythrocytes treated with long-chain alcohols.

Human erythrocytes, incubated with sonicated dispersions of phosphatidylcholine, cholesterol and saturated straight-chain alcohols (C16-C18) develop stiff, rod-shaped, hemoglobin-containing membrane projections within 120 min. The number of these 'rods' varies (1-3 per cell), they reach a length of up to 14 microns (twice the cell diameter) and a thickness of 0.3-1.0 microns. 'Rods' may be separated from 'residual cells' by shear flow and centrifugation without severe hemolysis. Lipid analyses carried out on residual cells and rods indicate lateral segregation of the phospholipids of the outer leaf of the membrane lipid bilayer (phosphatidylcholine and sphingomyelin) and of the alcohol applied. Phosphatidylcholine accumulates in the residual cells, sphingomyelin and the alcohol in the rods. No differences in membrane protein patterns were observed between rods and residual cells. The rod-shape is dependent on the presence of the alcohol, extraction of the alcohol converts rods into hemoglobin-containing spheres without lysis. The formation of rods, which is indicative of a lateral phase separation, is discussed in terms of lipid-lipid interactions and with respect to parameters determining the shape of cells.

Alcohols↗
PubMed1981

Influence of enzymatic phospholipid cleavage on the permeability of the erythrocyte membrane: III. Discrimination between the causal role of split products and of lecithin removal.

Cleavage of 55% of the lecithin in intact human erythrocytes by phospholipase A2 (bee venom) markedly inhibits the mediated transport of L-lactate (via the monocarboxylate carrier) and of L-arabinose (via the monosaccharide carrier), while the major anion exchange system (probed by oxalate) and diffusion via the lipid domain (probed by erythritol) remain essentially unaltered. the causal role of the split products, unsaturated fatty acids and saturated lysolecithin, and of lecithin removal were now studied by sequential extraction of split products with serum albumin and by their controlled insertion into normal membranes. Careful choice of the albumin-to-cell ration allowed the extraction of more than 95% or the fatty acids and up to 80% of the lysolecithin without hemolysis. Extraction of fatty acids abolished inhibition of lactate and arabinose transfer, but induced inhibition of anion exchange and translipid permeation. Subsequent extraction of lysolecithin produced no further effects except on lactate transfer, which was inhibited. Exogenous oleic and linoleic acid, at intramembrane concentrations equal to those produced by phospholipase A2, inhibit lactate and arabinose transfer, while accelerating oxalate and erythritol movements, in agreement with effects of endogenous fatty acids. Exogenous lysolecithin inhibits all mediated transfer processes but does not alter translipid permeation. This pattern differs from that obtained for endogenous lysolecithin. The action of exogenous lysolecithin can be suppressed by loading of the cells with cholesterol. Insertion of exogenous lysolecithin into cells depleted of endogenous lysolecithin does not restore the functional state before depletion, indicating that exogenous and endogenous lysolecithin may act differently.

Biological Transport↗
PubMed1980

Dual effect of membrane cholesterol on simple and mediated transport processes in human erythrocytes.

The influence of cholesterol on simple and facilitated transport processes across the membrane of intact human erythrocytes was studied after graded depletion or enrichment of membrane cholesterol by incubation of the cells in phospholipid or phospholipid/cholesterol suspensions. 1. The carrier-mediated transfer of L-lactate and of L-arabinose proved to be enhanced in this effect. In contrast, the self-exchange of SO4(2-), mediated by the inorganic anion-exchange system, and the simple diffusion of erythritol via the lipid phase of the membrane are inhibited by cholesterol. 2. Reversibility of these two opposite effects of cholesterol was demonstrated by measurements on cells depleted again after cholesterol enrichment and enriched again after previous depletion. 3. Certain phospholipids used for preparing the lipid dispersions that are required for cholesterol variation have effects on permeability of their own, due, for example, to traces of contaminants. A discrimination of such artifacts due, for example, to traces of contaminants. A discrimination of such artifacts from the effects of cholesterol is only possible by demonstrating reversibility. 4. The opposite effects of cholesterol on various facilitated transfer processes, which have a correlation in the opposite effects of other modifications of the membrane lipid phase (Deuticke, B., Grunze, M. and Haest, C.W.M. (1979) Alfred Benzon Symposium 14, Munksgaard, Copenhagen, in the press), are indicative of different types of lipid-protein interaction in the erythrocyte membrane.

Arabinose↗