Search PubMed⌕ Search

Biomedical subjects

I Nir

Publications and source records attributed to I Nir.

At least 163 records · Page 9Linked to original sources
PubMed1979

Ultrastructural basis for different pertechnetate uptake patterns by various human brain tumours.

Patterns of pertechnetate uptake were correlated with ultrastructural properties of the endothelial wall in 14 human brain tumours. In tumours with reduced uptake of the radionuclide, intercellular tight junctions were observed whereas absence of intercellular tight junctions was characteristic of all tumours with an increased uptake of pertechnetate. In some tumours with increased uptake, fenestrated endothelial wall was seen while in others non-fenestrated wall was evident. We concluded that intercellular junctions and not fenestrations affect the permeability of brain tumours to pertechnetate.

Astrocytoma↗
PubMed1979

Pinealectomy-induced changes in blood and pituitary luteinizing and prolactin levels during the last phase of pregnancy in rats.

Serum LH levels were higher in pinealectomized than in sham-operated control rats during all 4 of the last days of pregnancy studied, although reaching significance only during the final 2 days, 21 and 22. Prolactin (Prl) levels in the serum on the final day of pregnancy, and its contents in the pituitary throughout the entire study period, were significantly lower in pinealectomized rats. Pituitary weights were lower in pinealectomized than in control animals during days 21 and 22 of pregnancy, but no differences were found between the 2 groups in the average number of living foetuses and resorptions. The results presented would seem to indicate that during the last phase of pregnancy the pineal gland plays a role in the modification of gonadotropin synthesis and release. It appears that with LH the release, and with Prl mainly the synthesis, is being affected by the pineal, although the release of Prl may be influenced as well.

Animals↗
PubMed1979

Effects of isocaloric supplements of glucose or soyabean oil on lipids in tissues and plasma lipoproteins of starved and overfed chicks.

Chicks were overfed a basic diet supplemented isocalorically by soyabean oil or glucose 1, 2 and 10 days after 1 day of starvation. Carcass lipids resumed the prestarvation level 1 and 2 days after overfeeding with oil or glucose, respectively. After 10 days, an equal amount of lipid, mainly triglycerides, accumulated in the carcasses of both supplement groups. In the liver a transient accumulation of lipid was noticed in the oil-supplemented groups while a continuous increase was found in the glucose-supplemented ones. Hyperlipemia, due essentially to very low density lipoprotein (VLDL), was concomitant to liver lipid concentration. After 1 day, oil overfeeding raised plasma VLDL 6-fold, while the same level of VLDL was obtained within 2 days with glucose supplement. After 10 days, hyperlipemia was reduced in the oil-supplemented group, while it increased in the glucose-supplemented one. The fatty acid fluctuation caused by the treatments in liver lipids and plasma VLDL were grossly similar: the level of linoleic acid was reduced by glucose and increased by oil supplementation; the linoleic acid increase in VLDL preceeded that of liver lipids in the oil-supplemented groups. The results indicate a delayed transport of newly synthesized hepatic lipids in glucose-supplemented animals.

Animal Nutritional Physiological Phenomena↗
PubMed1978

Pineal N-acetyltransferase depression in rats exposed to heat.

Exposure of adult male rats to increased temperature of 33 +/- 1 degrees C for 3 and 10 days brought about decreases in pineal N-acetyltransferase activity. These and previous findings of pineal HIOMT inhibition under similar conditions support the postulation of a possible thermoregulatory role for the pineal gland.

Acetyltransferases↗
PubMed1978

The effect of thyroid hormones on rat pineal indoleamine metabolism in vitro.

The effect of TSH, triiodothyronine (T3) and thyroxine (T4) on basic and noradrenaline (NA)-induced indoleamine metabolism was investigated in rat pineal culture based on the observation that, under the experimental system used, melatonin is formed from its amino acid precursor tryptophan. When added to the culture medium, alone or in the presence of NA, TSH in dosages of 5 and 20 mU had no significant effect on pineal tryptophan metabolism.T4 and 2.5 microgram increased the melatonin concentration and, in the presence of NA 10(-4) M, also induced an increase in N-acetylserotonin (NAS). T3, already at a dosage as low as 0.25 microgram enhanced the melatonin concentration, while 2.5 microgram produced significant increases in concentrations of all pineal indoleamines measured. The latter dosage of T3 also enhanced the NA-stimulated NAS. On adding larger quantities of T4 or T3 to the medium none of the changes encountered with the lower dosages could be seen. The results obtained may suggest a direct positive feedback between the thyroid and pineal glands.

Animals↗
PubMed1978

Influence of overfeeding on growth, obesity and intestinal tract in young chicks of light and heavy breeds.

1. Heavy-breed (HB) chicks differed from light-breed (LB) ones in their propensity to be overfed. Whereas in the LB chicks the amount by which they could be overfed reached 70% more than the food consumed daily by the ad lib.-fed chicks, in the HB chicks the maximal excess was only 13%. 2. Overfeeding caused a slight but statistically significant increase in the linear growth rate (shank length) of the LB chicks, with an opposite effect in the HB chicks. 3. Overfeeding increased the weight of the crop, proventriculus, small intestine, pancreas, liver and adipose tissue but had no such effect on the heart, cerebrum or cerebellum. 4. Overfeeding had no effect on the specific activities of the pancreatic digestive enzymes, liver xanthine dehydrogenase, or tryptophan oxygenase (EC 1.13.1.12). The increase in the total activities was due entirely to organ hypertrophy. 5. Obesity induced in young chicks had no residual effects on the adult LB chicks, but reduced the linear growth of the adult HB chicks. 6. An explanation for the difference between breeds in response to overfeeding at an early age is discussed.

Adipose Tissue↗
PubMed1978

Visualization of intracellular concanavalin A binding sites in retinal photoreceptors.

Localization of carbohydrate components in retinal photoreceptor cells and membranes was studied. Frog and rat retinas were fixed with glutaraldehyde and embedded in glycol methacrylate or in a mixture of glycol methacrylate, glutaraldehyde and urea. Thin sections were incubated with ferritin-labeled concanavalin A (F-Con A) and stained with osmium vapors. Intensive binding was observed in both rod and cone outer segments. In the rod inner segment, differential binding of F-Con A was demonstrated. While numerous ferritin granules were observed in the myoid zone, only a few were seen in the ellipsoid zone, except for a local accumulation along the plasma membrane. In the rod outer segment, Con A binding sites were closely associated with the disk membranes. Ferritin granules were observed on both sides of the membranes. The relationship between the localization of Con A binding sites and the orientation of visual pigment molecules within the rod outer segments disk membranes was discussed.

Animals↗
PubMed1978

Changes in rodent thyroid hormones and cyclic-AMP following treatment with pineal indolic compounds.

Treatment of rats with pineal indolic compounds 5-methoxytryptophol, 5-hydroxytryptophol and serotonin brought about a significant increase in serum thyroxine levels, while serotonin and melatonin caused an increase in thyroid cAMP content with corresponding decrease in the gland's hormones. The total quantity of cAMP in the thyroid was also increased by melatonin in the organ culture system. All these findings would indicate that some of the pineal indoleamines elicit a direct action on the thyroid by stimulating the adenyl cyclase activity and intrathyroidal cAMP, bringing about increased release of thyroxine into the blood stream, and that this is usually not accompanied by adequate synthesis in the gland. Our observation that continuous darkness, which stimulates pineal activity, also brought about an increase in cAMP, concours with our finding of a stimulatory effect of the indolic compounds on thyroid hormone release.

Animals↗
PubMed1978

Effect of pelleting on the vitamin K activity of various vitamin K3 preparations in chicks.

A study with chicks was conducted to compare the relative vitamin K3 stability of various menadione preparations in mash and pellets. The preparations assayed were menadione sodium bisulfite, menadione sodium bisulfite complex, menadione dimethylpyrimidinol bisulfite and Kastab (a physically stabilized preparation of menadione sodium bisulfite). Pelleting increased the stability of all preparations when measured by the partial thromboplastin assay. The general trend in stability obtained by both procedures was in decreasing order: Kastab, menadione dimethylpyrimidinol bisulfite, menadione bisulfite complex and menadione bisulfite. Stability, determined chemically in vitamin microelement premixes, gave similar results.

Animal Feed↗
PubMed1978

Non-reproductive systems and the pineal gland.

The paper reviews the data accumulated on the interrelationship between the pineal gland and the central nervous system as evidenced by induced neuroanatomical, biochemical and hormonal changes taking place in one system following the activation or inhibition of the other. The possible role of the pineal in modifying behaviour and its involvement in mental impairment is consequently discussed. Further questions dealt with are, whether in addition to the pineal effect via the hypothalamic-pituitary axis on the peripheral non-reproductive glands, thyroid and adrenals, a direct feedback mechanism exists between their hormones and the pineal. The effect of the pineal on the endocrine glands which are known not to be under the direct control of the hypothalamo-pituitary axis, pancreas, thymus and parathyroid, is also discussed.

Adrenal Glands↗