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Biomedical subjects

K Vondra

Publications and source records attributed to K Vondra.

At least 73 records · Page 4Linked to original sources
PubMed1983

The effect of five days' fasting on skeletal muscle enzymes in obese men.

The effect of 120 hours' (five days) fasting on the activity of some enzymes of energy metabolism in skeletal muscles was investigated in six obese young men. The results revealed a significant decline in the activity of the following enzymes: triosophosphate dehydrogenase (by 20%), glycerol-3-phosphate dehydrogenase (by 24%), lactate dehydrogenase (by 13%), citrate synthase (by 20%), hydroxyacyl-CoA dehydrogenase (by 40%), while the hexokinase and malate dehydrogenase activities were not significantly altered. Contrary to muscles of non-obese healthy men (Vondra, Bass, Brodan, Kuhn, Andĕl, Veselková and Vítek 1982), a smaller decline of activities of the investigated enzymes occurred together with a paradoxical change of the enzyme pattern, namely a predominance of carbohydrate catabolism and a decline of the role of fatty acids in muscle energy metabolism.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed1983

Muscle enzyme activities and fibre composition (m. vastus lateralis) and efficiency of the cardiorespiratory system in cross-country skiers.

Fourteen male cross-country skiers (class I and II, average age 20.5 years) were examined by biochemical and histochemical methods. The activity of selected enzymes of energy metabolism and the percentage ratio of different types of muscle fibres (m. vastus lateralis) were assessed. Furthermore, the maximum values of the cardiorespiratory system and post-loading pH and blood lactate were determined after performance on a treadmill. The mitochondrial enzyme activities were relatively high with a considerable scatter in the values of HOADH activity. The glycolytic enzyme activities were on the same level as in subjects not engaged in sports. The percentage composition of muscle fibres was as follows: FG - 7.56 %, FOG - 30.65 % and SO - 61.79 %. Oxygen consumption VO2 max.kg-1 was 67.44 ml.min-1, pulse oxygen 24.76 ml, post-load pH 7.24 and blood lactate concentration 6.98 mmol.l-1. There was positive correlation between CS enzyme activity and oxygen uptake (VO2 max), pulse oxygen and percentage of SO muscle fibres. The mean values found in the athletes examined in the present study corresponded to values of middle distance runners.

Adult↗
PubMed1982

Enzyme activity patterns of energy metabolism in skiers of different performance levels (M. quadriceps femoris).

Changes in the activity of muscle enzymes of energy metabolism were studied in two groups of skiers (A, B) with a different sports performance (triosephosphate dehydrogenase-TPDH, lactate dehydrogenase-LDH, glycerol-3-phosphate dehydrogenase-GPDH, hexokinase-HK, malate dehydrogenase-MDH, citrate synthase-CS, hydroxyacyl,CoA dehydrogenase-HOADH). 1. In a group of ski-runners (A) significantly higher activities of CS, MDH, HOADH in the preparatory period (October) and also at the end of the competition period (March) were found in athletes with higher sports performance. 2. Significantly lower activities of LDH, GPDH, MDH, CS, HOADH were found in downhill skiers (group B). 3. Some significant correlations were established, both between the activities of individual enzymes (TPDH, GPDH, HK, CS, HOADH) and between the enzymes and indicators of functional capacity (MDH, CS, HOADH, VO2max, HRmax, O2-pulse max, body fat, laboratory performance).

Body Composition↗
PubMed1982

Rate of LCAT-mediated cholesterol esterification and serum lipids during etiroxate therapy in hyperlipoproteinemia.

Changes in the rate of the plasma cholesterol ester production mediated by lecithin: cholesterol acyltransferase (LCAT, E.C. 2.3.1.43) were examined in 15 patients suffering from types II and IV HLP who had been treated for 14 weeks with etiroxate. Whereas the plasma cholesterol concentration decreased significantly only in the initial phase of the therapy, the rate of cholesterol esterification increased gradually and attained at the end of the study a value exceeding by 50% the initial level. The final fractional turnover rate nearly equalled that characteristic for the control group of healthy subjects, in spite of the fact that the concentration of plasma cholesterol in the diseased subjects was higher by 50-100%. Triglyceride concentration decreased only transitorily in the course of the therapy with etiroxate. It is concluded that etiroxate is likely to normalize the rate of cholesterol turnover in the endogenous pool.

Body Weight↗
PubMed1982

Activities of muscle energy supplying enzymes after 5 days complete fasting in young men.

The effect of 5 days' complete fasting on the activity of 7 enzymes of energy supplying metabolism was studied in the vastus lateralis muscles of 9 healthy male volunteers. There was a significant decrease of lactate dehydrogenase (by 66%), triosephosphate dehydrogenase (by 61%), malate:NAD dehydrogenase (by 48%), hexokinase (by 40%), 3-hydroxyacyl-CoA-dehydrogenase (by 40%), triosephosphate dehydrogenase/3-hydroxyacyl-CoA-dehydrogenase (by 35%), citrate synthase (by 33%). Glycerolphosphate:NAD dehydrogenase activity did not decrease significantly. These findings suggest a) that utilization of the major energy substrates decreases; b) that the decrease mainly concerns the catabolism of carbohydrates, that of fatty acids to a lesser extent; c) that the decreased capacity of carbohydrate catabolism is partly compensated for by the predominance of the more economic aerobic-oxidative pathway; d) that the reducing equivalents formed in the cytosol may be transported via the glycerolphosphate shuttle into the respiratory chain to a greater extent, so that a greater portion is not lost by the reduction of pyruvate to lactate.

Adult↗
PubMed1982

Metabolic studies in postmyocardial infarction patients.

One hundred and seven patients registered in the secondary preventive programme in Prague 4 were followed up for an average period of 3 years. The endpoints of the study were taken as criteria of the progression of clinical atherosclerosis (non-fatal myocardial infarction, cardiovascular death). The authors tried to detect the causes responsible for the high prevalence of impaired glucose tolerance, diabetes and hyperlipoproteinaemia. They analyzed the interrelationships of food intake, insulin secretion, serum fatty acids and lipoprotein phenotypes. There were 6% of non-fatal myocardial reinfarctions and 13% of cardiovascular death after 3 years. Multiple regression analysis identified the following 3 factors closely associated with cardiovascular death: 1) history of myocardial infarction 2) low proportion of linoleic acid in total lipids 3) hyperlipoproteinaemia. The authors show that analysis of the relationships of triglycerides, insulin and serum fatty acids could be of value for identifying the factors involved in a faster progression of atherosclerosis.

Blood Glucose↗
PubMed1982

Cholesterol turnover and risk factors for the development of coronary heart disease.

Lecithin cholesterol acyltransferase (LCAT) appears to be one of the factors controlling the intravascular turnover rate of cholesterol. LCAT activity in healthy subjects is significantly higher in men than in women of the same relative body weight, total and free cholesterol and triglycerides. In healthy men sleep deprivation induced a decrease in LCAT activity combined with a decline of serum cholesterol concentration; consequently, the intravascular turnover rate of cholesterol did not significantly change. In hypertensive patients the decrease in cholesterol turnover rate correlated with the degree of hypertension and the response of blood pressure to medication. Reduced turnover rate of cholesterol was more frequent in men than in women, in spite of higher plasma cholesterol concentration in the latter. During a 4-month period of treatment etiroxate of hyperlipoproteinemia II and IV, the only significant change in plasma cholesterol level was a drop observed after the first two weeks; on the other hand, the turnover rate of cholesterol rose gradually and approached normal values due to a highly increased LCAT activity. Obesity and diabetes were associated with a high percentage of deviations in the studied parameters of cholesterol metabolism. The turnover rate of cholesterol measured three months after acute myocardial infarction was below normal in 80% of patients, whereas hypercholesterolemia was manifested in only less than 40%. The results imply that the intravascular turnover rate of cholesterol estimated by measurement of LCAT activity may be a suitable indicator of the internal balance of cholesterol, substantially more delicate and discriminative than a mere determination of the actual plasma concentration of cholesterol or plasma lipoprotein. Judging by our observations, deviations in the internal dynamics of cholesterol may play an important role in the pathogenesis of coronary atherosclerosis.

Cholesterol↗
PubMed1981

Effects of sleep deprivation on the activity of selected metabolic enzymes in skeletal muscle.

The effect of 120-h sleep deprivation on the activity of selected enzymes of energy metabolism in skeletal muscle was studied in seven healthy volunteers. The results showed a significant decrease in the activity of malate dehydrogenase, citrate synthase, glycerol-3-phosphate dehydrogenase and lactate dehydrogenase. Triosephosphate dehydrogenase, hexokinase, and hydroxyacyl-CoA-dehydrogenase activities showed an insignificant decrease. The findings are indicative of (1) decreased aerobic oxidation capacity; (2) reduced function of reducing-equivalent carriers from cytosol across the mitochondrial membrane; (3) relative accentuation of the non-aerobic glycolytic pathway; (4) a prediabetic type of muscle metabolism.

3-Hydroxyacyl CoA Dehydrogenases↗