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Biomedical subjects

J Shani

Publications and source records attributed to J Shani.

At least 145 records · Page 8Linked to original sources
PubMed1977

Prolactin and luteinizing hormone levels before and after parturition in rats bearing either single or multiple embryos.

Levels of prolactin and LH were determined in serum and pituitary during the last days of pregnancy and post partum in rats bearing single and multiple embryos. In rats with a single embryo serum prolactin and LH levels were significantly lower during the last 2 days of pregnancy and post partum than in rats bearing multiple embryos. While large increases were recorded in serum prolactin and LH levels in the rats with multiple embryos between days 21 and 22 of gestation, in the group with single embryos changes occurred in LH level only. Throughout the experiment pituitary prolactin was lower in rats with a single embryo than in those with multiple embryos in spite of the sharp drop in prolactin level in the group with multiple embryos from day 21 to 22. No differences were observed in the pituitary LH levels of either group during the days preceding parturition, but in the rats with multiple embryos there was a sharp drop in LH level post partum. It seems that the reduced serum prolactin level in the rats with a single embryo was associated with inhibition of pituitary prolactin synthesis and release, whereas the decreased serum LH level resulted from impaired release but not synthesis. These results support the hypothesis of a regulatory role for the placenta in pituitary prolactin and LH synthesis and release, either by hypothalamus-pituitary stimulation, or perhaps by way of the ovaries, through regulation of ovarian steroid production.

Animals↗
PubMed1977

Specific binding of prolactin to seminal vesicle, prostate and testicular homogenates of immature, mature and aged rats.

Ovine prolactin was iodinated by the lactoperoxidase method and purified by gel filtration on Sephadex G-100. The binding ability of the labelled hormone was determined, by incubation with liver homogenate from rabbits in late pregnancy, to be 8-8% total binding/mg protein, of which 86% was specific. The fraction of 125I-labelled ovine prolactin which bound most strongly was subsequently used to study its binding to rat seminal vesicle, prostate and testicular homogenates. The total binding to the seminal vesicle homogenate taken from mature (80-day-old) rats was the highest (11-69%/mg protein), but the greatest degree of binding specificity (82-6%) was to immature (30-day-old) rat prostate. Both total and specific binding to rat testicular homogenate were consistently very low. The binding specificity was demonstrated by displacement studies: while ovine prolactin caused displacement of specific binding, human chorionic gonadotropin, rat thyrotropin and human follicle-stimulating hormone did not cause any significant displacement of bound 125I-labelled ovine prolactin. Affinity constants (Ka) and binding capacities for the seminal vesicle and prostate homogenates were determined by Scatchard analysis and the effect of age on these parameters was studied. There was no difference in Ka between the aged (220-day-old), immature and mature rat tissue homogenates; however, a significant fall in binding capacity was observed in the mature rat prostate, and a further fall in the aged rat prostate. No such change was observed in the binding capacity of the seminal vesicle, as estimated by Scatchard analysis, although total and specific binding to the mature homogenates was higher than that of the other age groups.

Age Factors↗
PubMed1977

A model for prediction of chemotherapy response to 5-fluorouracil based on the differential distribution of 5-[18F]fluorouracil in sensitive versus resistant lymphocytic leukemia in mice.

The distribution of 5-[18F]fluorouracil has been compared in two variants of the same tumor in c57bL X DBA/2 F1 mice: solid L1210 lymphocytic leukemia tumor susceptible to 5-fluorouracil treatment and the same tumor, made resistant to the drug over a 34-generation span. Significant differences in 5-[18F]fluorouracil distribution were observed, most notably in the tumor:blood ratios at 12 hr postinjection. The drug-responsive tumor showed a 20:1 concentration ratio, whereas the drug-resistant tumor only had a 4:1 concentration ratio. We postulate that these differences, observed here in this animal tumor model, may be a reflection of similar ratio differences in humans. This technique may allow, by noninvasive quantification of tumor:blood ratios following administration of 5-[18F]fluorouracil to man, the differentiation of those human tumors that are likely to respond to drug therapy from those in which the response will be minimal or nil.

Animals↗
PubMed1976

Adverse reactions to radiopharmaceuticals.

This review covers the side effects and adverse reactions to radiopharmaceuticals that were reported in the literature over the past 25 years. The information published prior to 1970 is sporadic, but due to the increased utilization of nuclear medicine procedures and the recognition that radiopharmaceuticals may have pharmacologic side effects, a registry has existed since 1971 to tabulate information on such effects. This survey is medical, rather than pharmaceutical in emphasis and so the adverse reactions are classified according to the target-organ systems involved rather than according to the specific radionuclides or to pharmaceuticals. If any of the radiopharmaceuticals of present or past use are not mentioned in this review, it is because no reports on their side effects were retrived by us. Hopefully, the organized registry system suggested by the Society of Nuclear Medicine (SNM) will enable a more complete recording of side effects from radiopharmaceuticals in the future.

Bone Marrow↗
PubMed1976

Suppression of luteinizing hormone release by 5alpha-androstane-3alpha, 17 beta-diol and its 3 beta epimer in immature ovariectomized rats.

The effect of 5alpha-androstane-3alpha, 17 beta-diol, its 3 beta epimer and oestradiol benzoate on suppression of LH release after ovariectomy was studied in immature rats. At doses of 50 and 100 mug/100 g body weight/day the 3alpha compound suppressed LH release after ovariectomy to the same extent as 0-1 mug oestradiol benzoate/100 g/day. 3alpha-Androstanediol at a dose of 25 mug/100 g/day suppressed LH release only up to day 45 of life, while the same dose of the 3beta epimer had no effect on LH suppression. The effect of 3beta-androstanediol on inducing precocious vaginal opening was found to be mediated by the ovaries, since it was eliminated by ovariectomy. These results confirm our previous findings on the participation of androstanediol in the normal regulation of LH and in the mechanism of onset of puberty in the rat.

Androstane-3,17-diol↗
PubMed1976

Serum prolactin and LH in chronically-cannulated cycling rats after intra-atrial administration of oxytocin.

Chronically-cannulated female rats that had been adapted to frequent handling were used for a kinetic study where oxytocin was injected into an indwelling atrial cannula and blood sampled every 5-10 min for 2 hr after the injection. The plasma was assayed for prolactin and LH by radioimmunoassay, in order to ascertain whether in cycling rats oxytocin exerts any effect on the circulating level of either hormone. The advantage of this experimental model is that each animal served as a control for itself, and that only minor stress was recorded during the experiments. The results suggest that oxytocin does not alter circulating LH levels, and complement previous reports on the lack of effect of oxytocin on serum prolactin in the cycling rat.

Animals↗
PubMed1975

Interspecies study on the effect of perphenazine on milk yield and composition.

The effects on lactation of perphenazine, a tranquillizer which increases the level of prolactin in the blood, have been studied in cows, goats, guinea-pigs and rabbits. The drug caused a significant depression of milk yield in cows, goats and rabbits, but was without effect on the milk yield of guinea-pigs. It seems probable that the inhibitory effects on lactation were due to the actions of the drug on appetite and behaviour. It is concluded that perphenazine, because of its other actions, is not a suitable agent for studying the physiological effects of increased levels of endogenous prolactin.

Animals↗
PubMed1975

Subcellular morphological changes in the rat kidney after phosphorus burn.

Experimental phosphorus burns were performed on male rats, in order to evaluate the subcellular changes which had occurred as a result of their lesions. In addition to the external wound caused by the burn itself, pathological changes were observed macroscopically and microscopically in various body organs, mainly the kidneys. These were investigated under the electron microscope for subcellular alterations at their damaged sites, and for biochemical aberrations that were observed in those rats. In the phosphorus-burnt rats the glomeruli were ischemic, showed capillary collapse and exhibited proliferation of mesangial areas and basement membrane thickening. Many necrotic cells were observed in the proximal tubule, where large vacuoles containing myelin-like structures were identified. The lumen of the proximal tubules were completely occluded by cell debris and the cytoplasm was necrotic. Due to the damage caused to the glomeruli, high concentrations of serum urea, serum SGPT and PO-4 were assayed in the phosphorus-burnt rats. These changes may account for the high mortality rate after phosphorus burns and may further understanding of the damage as well as ways of approaching it.

Animals↗
PubMed1973

Distribution and blood-to-milk transfer of labeled antibiotics.

RADIOACTIVITY DISTRIBUTION WAS DETERMINED IN SERUM AND MILK OF LACTATING EWES AFTER PARENTERAL ADMINISTRATION OF FIVE LABELED ANTIBIOTICS: (14)C-benzylpenicillin G, (3)H-dihydrostreptomycin, (3)H-tetracycline, (14)C-chloramphenicol, and (14)C-spiramycin. Antibiotic levels were measured simultaneously by microbiological assay. Radiochemical and microbiological assay procedures presented similar kinetic patterns for uptake in serum and penetration into milk, except for tetracycline. Small reductions in milk pH markedly increased the excretion of spiramycin and slightly influenced the milk passage of penicillin, dihydrostreptomycin, and tetracycline but did not alter the transfer of chloramphenicol into milk. Thus, it appears that the five antibiotics penetrate milk in accordance with the nonionic passive diffusion principle, and that good agreement is achieved between the calculated and observed milk/serum ultrafiltrate concentration ratios obtained during equilibrium.

Animals↗