Biomedical subjects
Publications and source records attributed to M Dvorak.
Hepatic portal plasma concentrations of free serotonin were found to be transiently but significantly elevated in normal dogs following a single injection of ovine growth hormone into a peripheral vein. The data are consistent with the concept that spike concentrations of growth hormone are capable of altering the splanchnic concentration of agents that are concerned with glucose homeostasis.
The ultrastructure of human ovocytes was studied, the latter having been obtained laparoscopically following induced ovulation, using clomiphene and HCG. Optimum vacuum size for aspiration was tested on embryonated rat ova. It was found to be between 10 kPa and 30 kPa, that is between 100 and 300 mm H2O. Ultrastructural alteration was recordable neither from human nor from rat ovocytes. No change in ultrastructure was obtained either from subsequent in vitro culturing, and some of the ovocytes were embryonated with good success.
In two experiments the effect of feeding dried crushed white and red grape press cake replacing 10--20% of the complex feed mixture A1 and SOL, was studied on the 21 biochemical indicators of blood serum, plasma, suprarenal glands, liver and tissue of fattened pigs. Changes indicating unsuitability of this non-traditional feed were not observed. During feeding red grape press cake, the young pigs of 35kg body weight had a lower concentration of glucose in blood serum, in comparison with the control. The temporary increase of calcium level and decrease of inorganic phosphorus in these animals was accompanied by a lower activity of alkaline phosphatase. White and red grape press cake affected positively the vitamin E level in blood serum. In the muscles of the experimental slaughter pigs protein proportion was increased and fat proportion was decreased.
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The effects of immersion by 5-cm increments on the expiratory reserve volume of the lungs (ERV) and on the vital capacity were studied in the sitting and supine positions. These effects were compared to those produced by continuous negative-pressure breathing when the subjects were in air and were counteracted by positive pressure breathing during immersion. The depth of immersion was also related to definable anatomic landmarks. In the sitting position about one-fourth of the decrease in the ERV was accounted for by the hydrostatic pressure of the water on the abdomen and the remainder by the pressure on the thorax. Immersion to the level of the spinous process of the seventh cervical vertebra was equivalent to 28 cmH2o continuous negative pressure breathing in air. In the supine position, a comparable value was 8 cmH2o. These observations agree well with those of others if differences in the levels of immersion are accounted for.
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The v-myb(AMV) oncogene transforms myelomonocytic cells in vitro and induces acute monoblastic leukemia in chickens. We analyzed the activity of the evolutionarily conserved PEST-like domain (P1 domain) for biochemical and biological activities of v-Myb in ex vivo cultures and in vivo. Deletion of the P1 domain did not affect v-Myb transcriptional activity, intracellular stability, or subcellular localization. However, it resulted in subtle yet important changes in biological activities. Although the mutant DeltaP1 v-Myb protein blocked the terminal differentiation of the monocyte/macrophage lineage as efficiently as the wild type (wt) in ex vivo cultures, it failed to induce the acute phase of monoblastic leukemia, with its fatal consequences, in vivo. Interestingly, in DeltaP1 v-myb-infected animals large numbers of monoblasts, comparable to those induced by wt v-myb, were present in the bone marrow but very few were found in the peripheral blood. The comparison of ex vivo wt- and DeltaP v-Myb bone marrow cells revealed several important features of v-Myb transformation: (i) the proliferation of transformed monoblasts is not an apparent consequence of the differentiation block with these processes being at least in part independent; (ii) the P1 domain is required for proliferation of v-Myb-mediated transformed monoblasts; (iii) the mechanism which renders transformed cells growth factor independent does not involve activation of an autocrine growth factor loop; and (iv) deletion of the P1 domain affects self-adhesion properties of v-myb-transformed monoblasts as well as their interaction with bone marrow stromal cells. These data indicate that the DeltaP1 v-myb mutant and ex vivo bone marrow cell cultures represent a valuable tool for studies on the mechanisms of leukemia formation.