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Biomedical subjects

J Bílek

Publications and source records attributed to J Bílek.

At least 37 records · Page 2Linked to original sources
PubMed1978

Induction of lipid synthesis in mammary organ cultures from mature virgin and pregnant goats.

The hormones needed to induce lipogenesis in mammary organ cultures from mature virgin and pregnant goats were studied. In tissues from both mature virgin goats and goats at week 10 of pregnancy, cultivated in Waymouth medium without hormones, the rate of the incorporation of (1-(14C))-acetate into the lipids was low and decreased throughout culture. In the presence of insulin, the rate of acetate incorporation was maintained at a higher level. Cortisol acted synergistically with insulin, to produce a rate of lipid synthesis higher than that using insulin alone. The further addition of prolactin had little effect on the incorporation of acetate into the lipids of mammary explants from mature virgin goats, but markedly stimulated it in tissue from animals at weeks 9--10 of pregnancy. The maximum increase in the rate of lipid synthesis was achieved in the presence of 0.5 microgram prolactin/ml, whereas with growth hormone 50 microgram/ml was needed for the maximum effect. The initial rate of acetate incorporation into mammary explants from goats at weeks 13 and 18 of pregnancy was high. It was not stimulated by the hormones during culture, however, and decreased more rapidly in the absence of hormones than in their presence. The rate of acetate incorporation into the lipids was in agreement with the histological evaluation of the secretory response of the mammary explants after cultivation. The secretory response to prolactin and the rate of the incorporation of acetate into the lipids were highest in goats at weeks 9--10 of pregnancy while in tissues from goats at weeks 13 and 18 were not stimulated and decreased during culture.

Animals↗
PubMed1978

Changes in insulin and prolactin responsiveness of goat mammary tissue during ontogenesis and pregnancy.

Mammary tissue of goats in different stages of ontogenesis and pregnancy were organ cultured and their insulin and prolactin responsiveness was studied. Based on the synthesis of DNA in the presence of insulin and tissue secretory responses to prolactin, the responsive tissues were found in young goats up to 3 month of age (prolactin responsive only up to 24 days of age), in mature virgin goats at the end of breeding season, mature virgin goats with precocious lactation and in nulliparous goats from the 8th week of pregnancy. Unresponsive tissues were found in goats from 4.5 month of age to the maturity. The high number of antral follicles in goat ovaries was found to be coincident with high mammary insulin and prolactin responsiveness during ontogenesis. It appears that ovarian and placental steroids and placental lactogen render the goat mammary tissue responsive to insulin and prolactin in organ culture.

Animals↗
PubMed1977

Some properties of the goat placental lactogen.

Goat placental lactogen was partially purified from a medium collected after placental tissue incubation. The data obtained by disc electrophoresis and isoelectric focusing experiments, as well as by means of radioreceptor assay methods, provide evidence of the similarity between the goat and ovine placental lactogen.

Animals↗
PubMed1977

Studies on DNA synthesis in goat mammary organ culture under the influence of various hormones.

A study has been made of the hormones required for stimulation of DNA synthesis in organ culture of mammary tissue of goats. On culture in Waymouth's medium without added hormones the incorporation of 6-3H-thymidine into DNA was low. The addition of insulin caused a high stimulation of thymidine incorporation. However, the addition of cortisol, prolactin, growth hormone, 17beta-estradiol, progesterone alone or in combination had no effect on DNA synthesis. The minimal effective concentration of insulin was 0.1 mug ml-1. The addition of calf serum caused slight stimulation of DNA synthesis. When the mammary explants were exposed to a combination of serum and insulin, the rate of thymidine incorporation was always additive suggesting that DNA synthesis was affected independently by serum and insulin.

Animals↗
PubMed1977

Effect of estradiol and progesterone on udder growth in goats in vivo and lipid synthesis in goat mammary tissue in vitro.

The effect of estradiol-17beta (E) and progesterone (P) and E, P and deprenon (D; an inhibitor of prolactin secretion) treatment on udder growth, colostrum-like formation and on the induction of lipid synthesis in mammary organ culture were studied. Administration of E and P for 8-14 days induced udder growth and colostrum formation. Intensive mammary growth and udder distention with secretion occurred following hormone treatment. Simultaneous administration of D prevented both udder growth and colostrum formation. In mammary explants from E, P and D treated goats the rate of incorporation 14C-acetate into lipids was increased by insulin (I), cortisol (F) and prolactin (M) as compared with the effect of I or I plus F. The tissue from placebo treated goats and goats treated with E and P responded to M either slightly or not at all. The high sensitivity of mammary tissue from goats treated with E, P and D to M was demonstrated immediately following the administration of E and P for 8 days and also 10 days after the treatment, but not 23 days following hormone administration.

Acetates↗
PubMed1975

Effect of ergoline derivative VUFB-6638 on the adenohypophysial prolactin concentration in rats.

The compound VUFB-6638 (N-/D-6-methyl-8-isoergolin-I-yl/N'-N'-diethylurea hydrogen maleinate) was administered for four consecutive days to lactating rats in daily oral doses of 0.1, 1.0 and 2.0 mg/kg. The adenohypophysial prolactin concentration decreased by 34% to 68%, respectively. Moreover, this compound reduced or even completely suppressed the lactation. In view of the assumed relations between prolactin and breast carcinoma, a potential use of the drug is noted.

Animals↗