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Biomedical subjects

I Nir

Publications and source records attributed to I Nir.

At least 145 records · Page 8Linked to original sources
PubMed1982

Corticotrophin and corticosterone secretion following delta 1-Tetrahydrocannabinol, in intact and in hypothalamic deafferentated male rats.

Adult male rats, either intact (N) or bearing complete hypothalamic deafferentations (CHD), were injected with delta 1-tetrahydrocannabinol (THC: 5 mg/kg BW, IP). Forty-five minutes later, they were decapitated and trunk blood was collected for serum ACTH and corticosterone (CS) determinations. In the N animals, serum levels of both ACTH and CS were markedly elevated in the drug-treated, as compared to the vehicle-treated group (approximately 8-fold and 10-fold, respectively). In CHD rats, on the contrary, THC administration did not significantly alter serum concentrations of either ACTH or CS. These results demonstrate (1) that acute treatment with THC stimulates the secretion of ACTH as well as of CS; and (2) that extrahypothalamic sites and/or neural pathways mediate this effect.

Adrenocorticotropic Hormone↗
PubMed1982

Effect of constant light and darkness on pituitary and serum gonadotropin and sex hormone levels of parturient rats.

Exposure of rats to continuous darkness throughout gestation produced a threefold increase in their serum prolactin and a moderate one in their serum LH levels on the day preceding delivery. Parallel decreases in pituitary prolactin and LH contents were experienced indicating enhanced release of the hormones. In the animals kept in constant light only prolactin release was increased before delivery, their LH levels were unaffected, although diminished pituitary contents due to decreased synthesis were evident. Following parturition the photo-induced prolactin levels in serum and pituitary disappeared, but the LH values of the rats exposed to both extremes of illumination persisted, in contrast to those of the control animals kept in alternating light (12 L : 12 D) whose values fell abruptly. Serum oestradiol was affected neither by darkness nor light but serum progesterone concentrations were depressed before delivery in the rats kept in darkness even more than in the control animals. Exposure to continuous darkness shortened the duration of gestation. The marked tendency to deliver during the daytime hours was not influenced by exposure to continuous darkness but was completely abolished by constant light. It is suggested that the strongly decreased serum progesterone levels--possibly brought about by the high prolactin concentrations observed before parturition--may be contributing to the earlier onset of delivery in the rats exposed to continuous darkness.

Animals↗
PubMed1982

The skeleton, an important site of lipogenesis in the chick.

Studies in vitro and in vivo with chicks using 14C-1-acetate have shown that the bone could be an important site of lipogenesis. The in vitro relative activities of various bones in incorporating 14C into fatty acids varied from one tenth to one third of hepatic activity. The bone marrow activity attained about two thirds that of the liver. In vitro and in vivo activities of bones were highly correlated (r = 0.902). The activity of compact parietal bones was the lowest. Estimates of lipogenesis in vivo in various tissues (% of total incorporation) were as follows: liver, 45; skeleton, 23; skin and small intestine, 6. Incorporation by muscles, adipose tissue and kidneys were negligible.

Acetates↗
PubMed1982

Darkness-elicited changes in rat reproduction not mediated by pineal gland.

Serum and pituitary LH, prolactin and progesterone changes recorded in parturient rats exposed to continuous darkness throughout pregnancy were not prevented by early ablation of the pineal gland. Similarly, the shorter gestation period observed in rats kept in continuous darkness and the overwhelming tendency of rats in general to deliver during the light period (real or subjective), persisted in the pinealectomized animals. Darkness-induced endocrine changes in rat dams during the perinatal period appear not to be mediated by the pineal gland.

Animals↗
PubMed1981

Role of the pineal gland in male rats chronically exposed to increased temperature.

The effects of the pineal gland on endocrine function (especially those of the gonads) were investigated in male rats chronically exposed to increased temperature. Weanling male rats were either pinealectomized (Px) or sham-operated (Sh). Following one week of recovery, animals were assigned to either control temperature of 21 +/- 1 degree C (PxC and ShC) or a temperature of 35 +/- 1 degrees C (PxH and ShH). The animals were kept at their respective temperature for at least 30 days. In both groups (PxH and ShH) exposure to increased temperature resulted in a significant reduction in body and hypophysial weights, and in serum LH and testosterone levels as compared with the respective controls (PxC and ShC). Rectal temperature and serum corticosterone were also significantly increased. No changes were found in pineal hydroxyindole-O-methyltransferase activity of sham-operated rats kept in increased temperature (ShH vs. ShC). Pinealectomy alone (PxC vs. ShC) did not alter any of the measured parameters, except for increased pituitary LH content. Increased temperature plus pinealectomy (PxH vs. PxC; and PxH vs. ShH) caused a significant reduction in pituitary LH content and further accentuated (PxH vs. ShH) the diminished serum LH and testosterone levels evoked by exposure to high temperature. The results suggest that in male rats the pineal gland may play a role in moderating the changes in the reproductive processes that are induced by increased temperature.

Animals↗
PubMed1981

Comparison of ruminal and post-ruminal digestion of a concentrate feed in the young calf.

Pre-ruminant calves were pair-fed a concentrate feed in either liquid form (LC) from a nipple bottle or in dry form (DC). We then studied the effects of these two forms of feed on body weight gain, feed utilization, digestibility, digestive enzyme secretion and volatile fatty acids in the rumen liquor. The live weight gain of calves receiving the liquid concentrate was depressed by 34 p. 100. The digestibility of total dry matter, protein, starch and energy was lower in the LC than in the DC group. The daily amounts of trypsin, chymotrypsin and amylase excreted in the faeces were similar in both groups. Lipase secretion was significantly increased in the LC group. Due to a 2.7-fold increase in the amount of faeces excreted, faecal digestive enzyme concentration was depressed in the LC group. Feeding dry concentrate to young calves reduced the pH in the rumen liquor and markedly increased the concentration of volatile fatty acids, especially C2, C3 and C4. The processes occurring in the rumen increased the digestibility of the concentrate protein by about 60 p. 100 and that of starch by 20 p. 100.

Amylases↗
PubMed1981

Composition and amino acid content of carcass, skin and feathers of the growing gosling.

1. Growth rate, food intake and utilisation were determined for goslings (Anser cireneus) from hatching to 7 weeks of age. 2. The relative weight of the carcass (body without feathers, skin or intestinal content) decreased from 0.83 of total body weight at hatching to 0.73 at 7 weeks. The skin relative weight increased from 0.12 at hatching to 0.17 at 2 weeks of age and subsequently remained constant. The weight of feathers increased from 0.034 of body weight at hatching to 0.08 at 7 weeks. 3. The fat of the carcass and skin increased during the 7-week experimental period. The skin retained about half of the total body fat. 4. While amino acid compositions of feathers and skin proteins were quite similar to data reported for other birds, carcass proteins were lower in methionine and lysine.

Amino Acids↗
PubMed1981

Correlation between radionuclides uptake and ultrastructural features of tight junctions in the capillary wall of meningiomas.

The uptake of Tc-99m pertechnetate and Co-57 bleomycin and the ultrastructure of small blood vessels were studied in 10 cases of meningioma. When thin sections of 120 contact areas between adjacent endothelial cells were examined, 92% of the intercellular contacts contained one to three punctate tight junctions. Freeze fracture preparations revealed fascia occludens with one to four sealing strands. These findings are consistent with the high permeability the meningiomas displayed for both of the radiopharmaceuticals.

Capillaries↗
PubMed1981

Ultrastructural and clinical observations on skin metastases from breast cancer patients following intralesional treatment with MER/BCG vaccine.

Ultrastructural and clinical investigations were carried out on skin metastases in patients with advanced breast cancer, following intralesional therapy with MER/BCG vaccine. A total of 65 tumoral lesions in 5 patients were injected with MER. Clinical responses were correlated with light and electron microscopic observations. Regressing tumor lesions showed substantial macrophage and lymphocyte infiltration and severe damage to tumor cells. Activated macrophages with secondary lysosomes and contacts between macrophages and tumor cells were widely observed. In 1 patient with limited cellular immune response, clinical regression was not evident and many tumor cells were ultrastructurally intact.

BCG Vaccine↗
PubMed1980

Melatonin-induced changes in blood and pituitary luteinizing hormone and prolactin levels during the perinatal period in rat dams.

Following melatonin implants into pregnant rats throughout the entire period of gestation, the prenatal level of LH was significantly lowered in serum and the pituitary, while that of prolactin was enhanced in serum and diminished in the pituitary. After parturition, most of the melatonin-induced changes in LH and prolactin disappeared, being replaced by compensatory stimulation of release and synthesis of LH and inhibition of release of prolactin. Neither the abrupt physiological decline of serum progesterone, nor the enhanced level of oestrogen present during the period preceding delivery seem to be affected by melatonin. The findings were observed in both sham-operated (control) and pinealectomized animals, thus suggesting that melatonin exerts its inhibitory action on hypothalamic LH-RH and PIF not by utilizing an additional antigonadotropic pineal factor and not by the steroid sex hormones.

Animals↗
PubMed1980

Compensatory growth and sexual maturity in broiler females reared under severe food restriction from day of hatching.

1. Compensatory growth and the onset of lay were studied in White Rock broiler females severely restricted in food intake from day of hatching. 2. When changed to feeding ad libitum the restricted birds gained weight rapidly, but stabilised at a mean body weight 500 to 700 g less than that of controls fed ad libitum. Egg production was similar to that of controls. 3. Birds maintained at low mean body weight ( 2 224 g at 42 weeks) by continued restriction did not come into lay. In groups maintained at somewhat higher mean body weights (2 300 to 2 700 g) for period of up to a year, some birds came into lay. 4. Birds fed ad libitum showed accelerated development of comb, ovary and oviduct and weighed 2 300 to 2 700 g between 14 and 15 weeks of age, but did not come into lay until 20.5 weeks of age. 5. These results suggest that a minimum body weight and age may be required for the onset of lay in this strain.

Animals↗