PubMed Health⌕ Search

Biomedical subjects

R Petrásek

Publications and source records attributed to R Petrásek.

At least 37 records · Page 2Linked to original sources
PubMed1988

In vivo studies of the relationship between the activation of lipid metabolism, postirradiation bone marrow cell proliferation and radioresistance of mice.

The effect of adaptation to intermittent feeding on the in vivo biosynthesis of fatty acids and total lipids in the epididymal adipose tissue, the liver and the bone marrow was studied in adult male mice (CBA/JPh x C57BL@10 ScSnPh)F1. At the same time the effects of the same experimental stimulus on the rate of regeneration (proliferation) of bone marrow cells after sublethal irradiation of animals and on the overall radioresistance of mice expressed as 30 days survival after whole-body gamma irradiation were determined. Intermittent feeding in mice has been shown to have a significant effect on the biosynthesis of fatty acids and total lipids in all the tissues studied, including bone marrow cells, the intensity of the effect being closely dependent on the duration of the experimental stimulus. Maximum stimulation of lipogenesis during realimentation was observed approximately within 1 week of adaptation, with a reduction of the metabolic responses thereafter. The intensity of bone marrow cell proliferation in mice irradiated in the realimentation phase was inversely proportional to the preirradiation degree of biosynthesis of fatty acids and total lipids: in a period of lower lipogenetic capacity of cells in the tissue studied (around the weeks 2-5 of adaptation) an increase in the regeneration potential of bone marrow cells was observed together with increased radioresistance of the mice. During the 1-week of adaptation the opposite proved to be the case. Attention is drawn to the possible participation of prostaglandins and lipid peroxides in the responses observed.

Adaptation, Biological↗
PubMed1983

Ontogenetic development of skinfold thickness of the trunk in childhood and its relation to Rohrer's index.

The study was aimed at the investigation of the ontogenetic development of thickness of five skinfolds on the trunk in children ranging in age from 1 1/2 to 15 years in relation to Rohrer's index of body fullness. The studies which yielded the basic data were carried out in 1976-1978 on 10,661 children of both sexes (5,322 girls; 5,339 boys) from the whole territory of Czechoslovak Socialistic Republic. The studies yielded the following results: In the course of the early postnatal ontogenesis all five investigated skinfolds of the trunk showed on the average a slight decrease up to the age of three to five years. However, subsequently the thickness of all skinfolds increased, more markedly in girls than in boys. Throughout the investigated period the thickness of all investigated skinfolds remained larger in girls as compared to boys. This difference increased with increasing age. A more marked increase of mean skinfold thickness with increasing age due to the larger amount of subcutaneous fat was present in both sexes in abdominal regions and in in distal parts of the thorax as compared to its upper part, where the increase was more marked than in the subscapular region. The calculated mean values of Rohrer's index of body fullness were systematically decreasing in both sexes throughout the investigated period of life regardless of the development of the measured skinfold thickness. An exception formed the last two age groups of girls (13-14, 14-15 years of age), where, obviously with the onset of increasing total body weight, the calculated mean values showed again only a very slight increase. The actual differences of skinfold thickness and thus possibly also of the amount of subcutaneous fat between individual populations probably were due rather to social and economic factors. However, satisfactory nutrition was observed not only in highly developed, but also in some underdeveloped communities. However, it was not possible to exclude the influence of ethnical factors. This was confirmed by the comparison of our results with the data obtained in primitive rural populations as well as with those ascertained in highly developed countries in industrial populations.

Adolescent↗
PubMed1982

[Atherogenesis].

Explore the source record for details and available documents.

Animals↗
PubMed1982

Metabolic turnover of fatty acids, cholesterol and lipoproteins in response to atherogenic factors in experimental atherosclerosis.

In experiments on two animal species we studied the effect of age, altered motor activity and alimentary experimental atherosclerosis on a variety of variables of lipid metabolism, particularly on cholesterol and fatty acid levels and formation. Fatty acid and cholesterol cumulation in tissues, including the rat aorta, increases with age (from 2 to about 20 months of age), while their formation decreases. A decrease of motor activity seems to be at play in this phenomenon in older animals and is apparently due especially to a faster rate of decrease of lipid degradation with ageing. Enforced increase of motor activity in rats (60 or 120-day adaptation on a treadmill - 18 m/min/3 hr/day) results in a decreased tissue cumulation of lipids including cholesterol despite their increased formation. In animals of the same age but allowed a limited amount of motor activity the situation produces reverse changes in lipid levels and formation. Changes in lipid metabolism are effected also by a higher level of spontaneous activity (induced by a higher number of young in the litter) and by increased motor activity of the dams during pregnancy. Hyperkinetic animals show a uniform exogenous (alimentary) cholesterol turnover. However their alimentary cholesterol absorption and high-density lipoprotein cholesterol turnover are elevated. Two respectively 10 months following the intake of 2% of dietary cholesterol minipigs exhibit elevated cholesterolaemia, reduced endogenous cholesterol synthesis in the liver and the aorta versus a decreased endogenous fatty acid synthesis. Plasma/vascular wall cholesterol transport in hypercholesterolaemic animals is about 50% higher, while the level of cholesterol in the medium remains constant. Most experimental animals show histologic evidence of incipient atheromatous changes not earlier than 10 months following the start of experimental diet.

Aging↗
PubMed1979

Relation to body fat to age in the Czech population.

Density and percentage of fat in the body were investigated in 403 females and 356 males of Czech population using hydrostatic weighing. The group was divided into four age subgroups ranging from 17 through 22, 23 through 29, 30 through 39 and 40 through 49 years. Fat values were found to increase with age, growing in females and males between the ages of 17 to 49 years from 27.1 to 35.4 and from 16.3 to 26%, respectively. In both sexes, the highest difference in the percentage of fat was observed between the second and third decennium. Body weight was also seen to increase with age up to 40 years of age. On the other hand, from 40 through 49 years a decrease in weight was seen both in male and female means, with the body heights also less in older subjects. The values observed, particularly in females, exceed those reported as a rule in other populations. This is accounted for by nutritional factors such as the amount of calories and composition of food and possibly also by the effect of the genetically given somatotype.

Adipose Tissue↗
PubMed1979

Impact of early nutrition on later development of spontaneous physical activity and lipid metabolism.

Male rats suckled in large litters (more than 12 pups, group A) had significantly higher levels of spontaneous physical activity and temporarily increased food intake (g/100 g body weight) than male rats from small litters (less than 6 pups, group B). Females did not differ. Epididymal fat pads were significantly lighter in males in group A. The concentration of total lipids in the small intestine was significantly higher in females from group A, and the synthesis of lipids was higher in the animals of both sexes from group A. The synthesis of fatty acids in the intestines was significantly greater in both males and females from group A. Cholesterol concentration in the liver and carcass was the same in all groups. Cholesterogenesis was higher in the liver only in males from group B, and in the carcass in the animals of both sexes from group B.

Adipose Tissue↗
PubMed1978

Fatty acid synthesis in vitro in the liver and adipose tissue of rats of various ages.

In white male Wistar rats aged 2, 4, 6, 9, 12, 18 and 32 months, receiving a standard laboratory diet (25 cal% proteins, 22 cal% fat and 53 cal% glycides) we assessed the total amount of fatty acids in the carcass and in vitro lipogenesis in liver and adipose tissue by the means of glucose-14C(U). The amount of body fat increased with age; the highest rate of increase in the percentage of body fat occurs 2 to 4 months after birth. Incorporation of 14C of glucose into total liver lipids attains maximum values in the group of rats age 2 to 4 months. By the age of 6 months lipogenesis decreased to a level observed in all the remaining age groups. In adipose tissue, the incorporation of 14C into total lipids decreased between the age of 2 to 4 months, a further decrease was observed around the age of 6 months. No appreciable changes were noted in any of the older age groups.

Adipose Tissue↗
PubMed1977

Circadian and seasonal variations of some metabolic parameters in the serum of the albino laboratory rat (Rattus norvegicus var. alba).

Total protein (TP), glucose (GL), esterified fatty acids (EFA) and total cholesterol (TC) were determined at 4-hour intervals during the 24-hour cycle in the serum of 270 female Wistar rats, in February, May and July. The results can be summed up under the following points: 1) The differences found between the levels of the given parameters in February, May and July were statistically highly significant. The greatest differences were observed in the TC level, which was lowest in July (0.82 mmol/l) and highest in February (1.87 mmol/l). The highest TP and GL values were found in May (62.5 g/l; 10.69 mmol/l) and the lowest in February (40.1 g/l; 7.8 mmol/l). The smallest differences were observed in the EFA level, which was highest in July (8.09 mEq/l) and lowest in February (6.39 mEq/l). The minimum 24-hour variations in the levels of most of the given parameters during the 24-hour cycle were observed in May (compared with February and July). 2) In a study of TP and GL concentration, the time of day was found to be a very important factor. The maximum TP level during the 24-hour cycle was found most often in the early morning or forenoon, while the blood glucose level was highest at about midday and in some cases in the early morning. The blood cholesterol level was relatively stable during the 24-hour cycle and it is impossible to draw definite conclusions from its fluctuations. Changes in the EFA level during the 24-hour cycle were likewise irregular. 3) Except for cholesterol, interindividual differences in the levels of the given parameters in the various months seem to be statistically non-significant.

Animals↗