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Biomedical subjects

A Berg

Publications and source records attributed to A Berg.

At least 271 records · Page 15Linked to original sources
PubMed1984

Image Analysis of Geo-Induced Inhibition, Compression, and Promotion of Growth in an Inverted Helianthus annuus L. Seedling.

The growth responses of a sunflower seedling (Helianthus annuus L.), subjected to repeated inversion, were characterized by time-lapse recording in conjunction with video image analysis. The investigation revealed a characteristic response pattern and established that the directional movement of the seedling is achieved by both inhibition and stimulation of growth in the normal growing regions. The complex growth changes in contiguous regions of the hypocotyl are such as seem to be inexplicable in terms of an environmentally imposed gradient of a single growth substance.

Journal Article↗
PubMed1984

[Changes in sympathetic activity in 18 postinfarct patients following a year of exercise therapy].

18 male post-infarction patients (56 +/- 9 years) were investigated before and after 1 year of controlled physical therapy. Results were compared with those observed in 7 healthy male control subjects (47 +/- 6 years). Left-ventricular impairment of the investigated patients corresponded haemodynamically to stages I and II of the Roskamm-Reindell classification, based on a Swan-Ganz catheter. The influence of physical therapy on plasma catecholamine levels was evaluated; free plasma catecholamines are seen as reference indicators of sympathetic activity. Cycling performance capacity (supine position) of the patients increased from 101 +/- 25 watt to 131 +/- 24 watt. Before and after physical therapy, maximal heart rate responses were similar (121 +/- 17 as compared with 119 +/- 16 min-1). After physical therapy, maximal noradrenaline responses were 16% lower, adrenaline responses down by 25%, and mean arterial blood pressure was 14 mm Hg lower. At identical work-load (50 watt level), reductions after physical therapy amounted to 25% (noradrenaline), 41% (adrenaline), 16% (heart rate), and 21 mm Hg (mean arterial blood pressure).

Blood Pressure↗
PubMed1983

Changes in HDL subfractions after a single, extended episode of physical exercise.

In order to investigate the changes in HDL subfractions induced by a single period of extended physical exercise, 9 endurance-trained adults were examined before and 6 min, 1 and 6 h after a 30 km cross-country race. In contrast to less evident changes in the concentrations of total HDL, apolipoprotein A-I and A-II, there were significant changes in HDL subfractions. Resting levels of protein and cholesterol content of the HDL subfractions 1-3 increased (subfraction 1, density gradient 1.093: 1.68 +/- 0.58 to 3.24 +/- 0.86 mmol/1 cholesterol, P less than 0.001), while the concentrations in HDL subfractions 11-12 decreased proportionately (subfraction 12, density gradient 1.142: 3.68 +/- 0.81 to 2.19 +/- 0.22 mmol/1 cholesterol, P less than 0.001). The results suggest that physical exercise induces an increased formation of HDL particles of lower density from HDL particles of higher density. It was concluded that this formation is related to the catabolism of triglyceride-rich lipoproteins in the post-exercise period.

Cholesterol↗
PubMed1983

Correlations between laboratory testing and distance running performance in marathoners of similar performance ability.

Correlations between distance running performance and laboratory testing were examined in 11 marathoners of similar fitness (VO2max 66.4 +/- 1.7 ml/kg X min). They performed a graded treadmill test and a subsequent 30 km cross-country run. Heart rate, oxygen intake, blood lactate, and plasma catecholamines were measured during the treadmill test. Lactate equivalent, individual lactate threshold, 4 mmol lactate threshold, submaximum (16 km/h running velocity) lactate behavior, submaximum catecholamine responses, submaximum lactate-catecholamine product, measured VO2max, and extrapolated VO2max were examined for their adequacy in the evaluation of distance running capacity. Race times and free urine catecholamines were estimated in the field experiment. Direct correlations were found between race times and minimum lactate equivalent (r = 0.69), submaximum lactate levels (r = 0.52), submaximum catecholamine responses (r = 0.69), submaximum lactate-catecholamine product (r = 0.79), respectively. Inverse correlations were observed between race times and oxygen intake at individual lactate threshold (r = -0.68), 4 mmol lactate threshold (r = -0.76), measured VO2max (r = -0.71), and extrapolated VO2max (r = -0.63). Further correlations were found between submaximum noradrenaline and lactate behavior (r = 0.53), as well as between noradrenaline and adrenaline responses (r = 0.72). No significant correlation was observed between relative heart volumes or catecholamine excretion and race times.

Adult↗
PubMed1981

Studies on the substrate specificity and inducibility of cytochrome P-450meg.

The cytochrome P-450-dependent steroid 15 beta-hydroxylase system in Bacillus megaterium A.T.C.C. 13368 was investigated with regard to its appearance in the cell with respect to the growth curve of the organism, with regard to its inducibility by a number of agents (among them some of the classical inducers of the mammalian liver microsomal cytochrome P-450 system) and with regard to its capacity to convert non-steroidal substances into oxygenated compounds. The enzyme was found to reach a maximum concentration in the cell during the stationary phase of the growth curve. Of all the agents tested as inducers, none showed any capacity to induce cytochrome P-450meg. Finally, of the substances tested as substrates only aniline (p-hydroxylation) was metabolized by the microbial enzyme system. This conversion might be related to the general oxygenase activity of haemoproteins. It is concluded that the substrate specificity of the B. megaterium hydroxylase system is narrow.

Aniline Compounds↗
PubMed1981

Biochemical changes in a 100 km run: carbohydrates, lipids, and hormones in serum.

During the 100 km race in Biel, Switzerland, seven-well trained men (age 33.3 +/- 3.5 years; V02 max. 59.9 +/- ml/kg) have been investigated. Their mean running time over the 100 km distance averaged 10.41 +/- 1.25 h. In contrast to almost unchanged blood glucose and lactate concentrations, blood lipids showed significant changes. Triglycerides decreased about two-fold, whereas glycerol and free fatty acids increased to extremely high concentrations (0.628 and 2.44 mmol/l respectively). Plasma insulin after the run was unaffected, whereas growth hormone, aldosterone and cortisol concentrations were significantly increased. With the exceptions of a still significantly elevated aldosterone and lactate concentration as well as a decreased triglyceride concentration all other values in the blood are restored to normal 24 h after completion of the run.

Adult↗
PubMed1981

[Plasma catecholamines and aerobic-anaerobic capacity in women during graduated treadmill exercise].

Blood levels of adrenalinee, noradrenaline lactate, and glucose, and heart rate and oxygen intake were examined in nine healthy women (29.3 +/- 2.2 years) during a graduated treadmill exercise. At rest there are no differences in these parameters compared with male subjects. During treadmill exercise, two ranges can be distinguished as in male subjects. A range with a slight increase in adrenaline, noradrenaline, and lactate, corresponding to a predominantly aerobic energy supply, and a range with an eight to ten times higher increase of adrenaline, noradrenaline, and lactate related to an additionally increasing anaerobic energy supply. The transition between the two ranges corresponds approximately to the anaerobic threshold, and occurs as in male subjects at an oxygen intake and heart rate of 70--80% and a catecholamine and lactate concentration of 20--30% of the maximal value. At the same exercise level, adrenaline, and noradrenaline are higher than in male subjects. Differences in the relative oxygen intake or the heart rate are similar. During maximal treadmill exercise adrenalin increased by 1,300%, noradrenaline, 1,500%, lactate 1,100% glucose, 30%, the oxygen intake, 1,000%, and the heart rate by about 200%. During ergometric exercise, as in male subjects there is a direct linear correlation between adrenaline and noradrenaline. A direct linear correlation excists between the catecholamines and lactate or glucose levels. Referring to the catecholamines, the lactate level is lower than in male subjects, corresponding to a limitation of acidosis in females.

Adult↗