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Biomedical subjects

I Nir

Publications and source records attributed to I Nir.

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

Differentiation and activity of mast cells following immunization in cultures of lymph-node cells.

An extensive clonal differentiation into mast cells from primitive blast cell precursors occurred when lymph node cells obtained from mice immunized with horse serum were cultured on mouse embryonic skin monolayers. Horse serum was always present in the culture as a constituent of the nutritional medium. Mast cells developed to lesser extent also in cultures prepared from non-immunized mice. However, a clear difference in mast cell-granule ultrastructure and in histamine content was noted between the two. In cultures of lymph nodes cells from non-immunized mice the granules were tiny and uniform in size and in staining density; whereas granules in the immune cultures were larger and non-uniform in size and in staining density, and the intragranular organization manifested alterations of various forms. The content of intracellular histamine per 10(6) mast cells was about equal in both cultures. However, much more free histamine (per 10(6) mast cells) gradually accumulated in cultures of the immune lymph node cells, indicating higher rates of synthesis and release of histamine. The mast cells were readily degranulated by heat-inactivated (IgG1) sera of the mice used as donors of the lymph node cells. 92% of the mast cells were degranulated and as much as 80% of the histamine was released. The degranulation was accompanied by an immediate (albeit reversible) response of the fibroblast cells in the monolayer. A shift of the well-stretched cytoplasm of the fibroblasts opened numerous 'window' over the whole monolayer. The degranulated mast cells survived the process and could be maintained further in the cultures. Moreover, they were capable of repeated degranulation, releasing 50% of their histamine, even after four degranulation cycles performed over a 7 days' period of culture. No cytotoxic effect on the mast cells was noted and the histamine content in culture, 3 days after degranulation, seemed to be higher than in the undergranulated control cultures--suggesting an intensified rate of histamine synthesis.

Animals↗
PubMed1977

Effects of obesity induced by overfeeding on body temperature, the testis and plasma testosterone of the male Japanese quail.

Male Japanese quail, force-fed for 4 weeks, showed a marked increase in weight resulting mainly from the deposition of fat. 2. Obesity, induced by forced feeding, was accompanied by increases in colonic temperature (about 0-3 degrees C), peripheral leg temperature (about 3 degrees C) and by a decrease of the mid-scapular skin temperature (about 0-6 degrees C). 3. Testicular weight decreased by 30% during the period of overfeeding and the spermatozoa concentration in the testis and ducti deferentes decreased by 50%. There was also a small increase in the cholesterol concentration of the testis; testicular cholesterol concentration was negatively correlated with testicular weight. 4. A marked decrease in the concentration of the plasma testosterone was accompanied by regression of the tail and by a reduction in the volume of cloacal foam secreted.

Animal Feed↗
PubMed1977

The relative growth of internal organs in light and heavy breeds.

The relative weights of the gastro-intestinal segments and of some other internal organs from light and heavy breed chicks from hatching to 21 days of age were compared. 2. The relative weight of the duodenum and jejunum was higher in the light breed than in the heavy one, the reverse relationship was found for the ileum and caecum. 3. The relative growth of the pancreas, heart, cerebrum and cerebellum was greater in the light breed.

Animals↗
PubMed1977

Acute effect of delta1-tetrahydrocannabinol on the hypothalamo-pituitary-ovarian axis in the rat.

Administration of delta1-tetrahydrocannabinol (delta1-THC), the principal psychoactive ingredient of cannabis, to proestrous rats (2 mg/rat, i.p., between 12.00 and 16.00 h) suppressed the proestrous rise in the plasma levels of LH, FSH and prolactin (Prl) and caused a 24 h delay in ovulation. Furthermore, the increased accumulation of prostaglandins of the E-type (PGE) in the ovaries, normally seen on the evening of proestrus, was prevented. Earlier (08.00-10.30 h) or later (18.00 h) administration of the drug on the day of proestrus was only partially effective in inhibiting ovulation. The suppressive effects of delta1-THC on ovulation and gonadotropin secretion were prevented by administration of gonadetropin releasing hormone (GnRH, 0.2 microgram/rat) 1 h after the drug, indicating that the central action of delta1-THC was exerted on the hypothalamus and not on the pituitary gland. Administration of ovine luteinizing hormore (oLH, 2.5 microgram/rat at 16.30 h on the day of proestrus restored ovulation and ovarian PGE accumulation in Nembutal-treated rats, but not in delta1-THC-treated rats; higher doses of oLH (5-10 microgram/rat) reversed the action of delta1-THC on these two parameters.

Animals↗
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

Drug utilization and adverse drug reactions in medical patients: comparison of two periods, 1969--72 and 1973--76.

A study of drug usage and adverse drug reactions was carried out on 2,771 hospitalized medical patients during 1969--76. Comparison of data between 1969--72 and 1973--76 shows an 11% reduction in the average number of drugs per patient, and a 59% decrease in the incidence of adverse effects, calculated as percent of all exposures. The number of patients affected by adverse reactions during the second period fell by 61%. These data seem to indicate that there was considerable improvement in habits of drug usage in the monitored ward.

Adult↗
PubMed1976

Polysaccharides in lung alveoli.

Rat lung alveolar surfaces and contents were studied after using concanavalin A as a bifunctional agent to link exposed sugars to horseradish peroxidase, in accordance with a technique developed by Bernhard and Avrameas ('71). The Graham and Karnovsky ('69) diaminobenzidine procedure then was used to provide and electron-dense reaction product so as to define the distribution of complex carbohydrates in alveoli. A layer of very dense raction product was intimately associated with the outer leaflets of the luminal plasma membranes of type I and II pneumocytes. Masses of generally less dense reaction product extended irregularly into the alveolar coated by reaction product. When highly ordered tubular myelin bodies were seen, the reaction product filled all the "gutters" created by the intersentions of the membranes. Reasons are presented for believing that the intrinsic periodicity of the tubular myelin may be created and maintained by the domains ol technique. The distribution of autologous albumin, demonstrated by antibody staining by Bignon et al. ('75), apparently coincides with the carbohydrate pattern, suggesting both may be associated as a glycoprotein. The ultimate relationships between carbohydrate moieties and phospholipid membrane systems proved to be of such complexity that we believe it justifiable to think that they also may be truly complexed together.

Albumins↗
PubMed1976

Inhibition of adrenocortical function by intravenous administration of sodium pentobarbital in cocks.

The response of awake and anesthesized cocks with sodium pentobarbital to stressful stimuli has been examined. The stressful stimuli was immersion in cold water. In the awake cocks plasma corticosterone concentration was increased about 4 fold; they started shivering shortly after immersion and recovered after cessation of the treatment. In the anesthesized ones there was no increase in plasma corticosterone concentration, they did not shiver and died shortly after immersion.

Adrenal Cortex↗
PubMed1975

The effect of heat on rat pineal hydroxyindole-omichron-methyl transferase activity.

Exposure of adult male rats to continuously elevated temperature of 32-34 degrees C caused a significant decrease of HIOMT activity involved in the specific metabolic process of production of melatonin, considered an active pineal hormone. The effect was already evident after 24 h exposure and increased further during the next 48 h. The results obtained substantiate previous data that the pineal gland may be involved in the system regulating adaptation to extreme temperature changes.

Acetylserotonin O-Methyltransferase↗
PubMed1975

Substructure in rod photoreceptor membranes.

Frog retinae, fixed only in buffered glutaraldehyde, were embedded for sectioning in glutaraldehyde polymerized with urea. In suitably thin sections globular substructures were seen in negative contrast after ionic staining with uranyl acetate and lead citrate, or after staining with neutralized phosphotungstic acid. Efforts to extract at least some of the lipid from sections before ionic staining enhanced the visualization of the "globules". Exposure to KMnO4 solution, used as an oxidative section stain, also outlined globular substructure in negative contrast, but with the additional feature that positively stained surface "leaflets" associated with the aqueous compartment were well defined. Staining sections with OSO4 vapor resulted in positively stained membranes, but without any evident substructure. However, when sections which previously had been exposed to OSO4 vapor were secondarily stained with uranyl acetate and/or lead citrate, positively stained globular substructures then were revealed. The globular substructures always were centered in the hydrophobic core region of the disc membranes, and symmetrically spanned the full thickness of this layer. The diameter of individual particles approximated 50-55 A. Reasons are presented for the supposition that the evident globules incorporate at least hydrophobic components of rhodopsin molecules. Findings are discussed in relation to various models of disc membrane organization that have been proposed in recent years.

Animals↗