Biomedical subjects
Publications and source records attributed to J Mikeska.
Using the model of mice affected by thyroid hormones, a ferrokinetic analysis was made of the repeatedly observed paradoxical fall in the incorporation of labelled iron into the bone marrow under conditions of the overall stimulation of erythrocyte formation.
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Peroral application of Isoprinosine for 3, 5 and 10 days increases the number and proliferative activity of haemopoietic stem cells (CFUs) in the bone marrow of mice. Changes in the spleen occur later and are manifested by an increase in CFUs proliferative activity and by a transient decrease in CFUs number.
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Feeding of C57BL mice with dried thyroid glands (added to their food) for 10 days activates 59Fe incorporation into splenic heme and decreases peripheral granulocyte levels. The importance of the differentiation of haemopoietic stem cells under these conditions was investigated by using the repopulation assays. Transplantation of bone marrow cells into recipients irradiated on day 10 of treatment with thyroid hormones, i.e., in the phase of activation of erythropoiesis, results in an increase in erythropoiesis and a decrease in granulopoiesis. However, following irradiation and transplantation of animals during the phase of rebound, i.e., approximately 5-8 days after cessation of thyroid hormone treatment, erythropoiesis is depressed and granulopoiesis is activated, the values exceeding markedly the control levels. The practical importance of changes in the host inductive milieu favouring granulopoiesis is documented by the results showing that hormonal marrow has an increased capacity to prolong the survival of animals lethally irradiated in the phase of rebound after pretreatment with thyroid hormones.
Oral administration of dried thyroid gland to C57Bl adult male mice in a dose of 0.6 g per 100 g diet during 10 days increased the metabolic rate and stimulated the erythropoiesis. Three to six days after thyroid pretreatment the radiation resistance of the mice increased, as revealed by their 30-day survival and a higher recovery of peripheral blood cell counts. The period of increased resistance to radiation was correlated with the receding of hypermetabolic effects and with the increase of repopulating abilities of the bone marrow cells.
The possibility of radioprotective action of K and Mg aspartate administered in tap water for ten days prior to X-irradiation was investigated in male mice of the strain C 57 Bl/10. In normal animals, thymus weight was found to be increased by 10-day treatment with K and Mg aspartate. The postirradiation regeneration of spleen weight and incorporation of radioactive iron into the spleen and femoral marrow following sublethal irradiation was favorably modified by the treatment used. Pretreatment of mice with K and Mg aspartate delays the onset of early deaths at irradiation with an absolutely lethal X-ray exposure and raises the percentage of surviving animals after nearly lethal exposures.
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.