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Biomedical subjects

I Nir

Publications and source records attributed to I Nir.

At least 109 records · Page 6Linked to original sources
PubMed1986

Quantitative analysis of tight junctions and the uptake of 99mTc in human gliomas.

The structural dimensions of capillary tight junctions and the uptake of 99mTc pertechnetate in human gliomas were studied. Quantitative analysis revealed a correlation between the uptake of radionuclides and the length of endothelial tight junctions. It is suggested that brain scintigraphy might be used for the selection of malignant brain tumors with altered tight junctions which might be accessible to chemotherapy with water-soluble agents.

Blood-Brain Barrier↗
PubMed1986

Immunocytochemical localization of opsin in the inner segment and ciliary plasma membrane of photoreceptors in retinas of rds mutant mice.

Homozygous 020/A mutant mice bearing the rds gene for slow inherited retinal degeneration have been observed to develop normal photoreceptor inner segments connecting cilia and synaptic contacts but fail to form outer segments. Their retinas are responsive to light, however. In order to assess the sources of these physiological responses we investigated the distribution of opsin in photoreceptors by means of immunoelectron microscopy. Opsin was detected in the inner segment plasma membrane and the distal ciliary plasma membrane. Antibody also bound to lamellar and vesicular membranes in the interphotoreceptor space and, in a small fraction of the photoreceptors, to membranes projecting from the distal cilium. These membranes may represent abortive formation of rod discs in this form of retinal degeneration. Failure to form an organized outer segment may contribute to the persistence of opsin in the inner segment plasma membranes of adult mutant mice.

Animals↗
PubMed1985

The effect of delta 1tetrahydrocannabinol on luteinizing hormone release in castrated and hypothalamic deafferented male rats.

delta 1Tetrahydrocannabinol (THC) acutely suppresses tonic serum luteinizing hormone (LH) and prolactin levels in adult male rats. The exact site of its action has not been identified. We have performed complete hypothalamic deafferentation (CHD), which disrupts the medial basal hypothalamus (MBH) from the rest of the CNS, but did not abolish the ability of THC to suppress hypothalamic-pituitary responses in gonadectomized male rats. This was shown by the equal reduction in serum levels of LH and prolactin in non-deafferented (ND) and CHD animals. These results indicate that THC is able to act inside the MBH and that the MBH-pituitary axis remains responsive to its inhibitory effect despite interruption of the neural connections between the MBH and extrahypothalamic areas. However, the corticotropin releasing factor neurons in the MBH appear functionally impaired as a result of the transection and become unresponsive to the normally produced THC stimulation. Different patterns of action seem to govern the various hypophyseal hormones controlled by the hypothalamus, suggesting that the release of LH releasing hormone and prolactin inhibiting factor might be maintained by the activity of neurons surviving inside the island.

Afferent Pathways↗
PubMed1985

Effect of lysine vasopressin in depressed patients on mood and 24-hour rhythm of growth hormone, cortisol, melatonin and prolactin.

Lysine-8-vasopressin (LVP) for 10 days and in doses up to 13.5 LVP units did not significantly alter the Hamilton Depression Rating Scale scores of 12 severely depressed, treatment-resistant patients who were evaluated in a double-blind crossover study. The 24-h rhythms of melatonin, cortisol, growth hormone and prolactin appeared remarkably stable over the course of repeated measurement. LVP administration did not affect these 24-h rhythms.

Adult↗
PubMed1985

Metabolic and anatomical adaptations of heavy-bodied chicks to intermittent feeding. I. Food intake, growth rate, organ weight, and body composition.

Chicks of a heavy-bodied strain were deprived of food on alternate days from 14 to 83 days of age. Relative food intake was depressed by intermittent feeding to 25 days of age, after which the deprived chicks resumed the relative intake of the ad libitum-fed controls, i.e., the relative intake on repletion day was twice that of the control chicks. Following an adaptation period of 2 weeks, the relative growth rate of the intermittently fed chicks exceeded that of the control group, the excessive growth being due to an increase on the day of repletion which was more than twice that of the control birds. Body fat concentration was depressed by intermittent feeding throughout the experimental period. Although, in ad libitum-fed chicks, periodical deposition of body protein and fat was parallel throughout the experimental period, in the treated chicks, protein deposition prevailed initially and fat deposition prevailed at the end of the experimental period. Intermittent feeding was accompanied by a consistent increase in the relative weight of the liver, pancreas, and gastrointestinal tract, including the small intestine. The differences in food intake, growth, body composition, and gastro-intestinal tract between heavy- and light-breed chicks exposed to intermittent feeding are discussed.

Adaptation, Physiological↗
PubMed1984

delta 1-Tetrahydrocannabinol-induced circling behavior in rats: a possible measure of psychotomimetic activity?

Relatively high dosages of delta 1-tetrahydrocannabinol (delta 1-THC) markedly suppressed almost all normally occurring behavioral elements in rats as observed in both a small and a large open field. This effect persisted following repeated treatment and testing for 3 consecutive days. The psychotropically inert but related compound cannabidiol (CBD) did not suppress behavior, but in contrast had a mild activating effect. Both compounds decreased defecation during the test procedure. In addition, delta 1-THC, but not CBD, induced a bizarre circling and turning response, that was evident over all 3 test days and occurred even when the rats were deeply sedated. It is suggested that an analysis of this phenomenon may be useful in measuring the psychotomimetic action of delta 1-THC and similar compounds in rats.

Animals↗
PubMed1984

delta 1-Tetrahydrocannabinol but not cannabidiol reduces contact and aggressive behavior of rats tested in dyadic encounters.

A low and a high dose of delta 1-tetrahydrocannabinol (delta 1-THC) and of cannabidiol (CBD) were IP injected in rats that had been isolated for 7 days. Forty-five minutes after injection, the rats were tested for social interactions with non-isolated, untreated test partners in dyadic encounters under standardized conditions. Different aspects of social behavior were analyzed. The high dose of delta 1-THC (10 mg/kg) prevented nearly all social interactions. The low dose of delta 1-THC (1 mg/kg) exerted selective and specific effects on social interactions. Social contact behavior, including crawl over/mounting, and social grooming, and aggressive behavior, including fighting, kicking, and biting, were markedly decreased, whereas social exploratory behavior (exploration of the partner and anogenital investigation) and the behavioral item, approach/follow, were hardly affected by delta 1-THC treatment. Both doses of CBD (2 and 20 mg/kg) failed to change the various aspects of social interaction. It is postulated that the effects of delta 1-THC on close and intimate contact behavior of rats may contribute to the understanding of marihuana taking in humans.

Aggression↗
PubMed1984

The effect of meal-feeding and food restriction on body composition, food utilization and intestinal adaptation in light-breed chicks.

The effects of feeding meals, in amounts equivalent to ad lib, intake or to 75% and 50% restriction by intubation, were studied in chicks. Growth estimated by body-weight gain and shank length was improved by tube feeding in the 50%-restricted chicks. Tube feeding increased energy retention at all feeding levels and nitrogen retention in the restricted chicks only. Body fat was increased in the full-fed chicks by intubation and decreased in the 50%-restricted chicks only. Crop and gizzard weights were increased by food restriction and by intubation. Tube-feeding increased the weight of the small intestine at all feeding levels. The activities of the digestive enzymes were lower in the pancreas and higher in the small intestine of the tube-fed chicks than in the voluntarily-fed ones at all feeding levels. It is suggested that synthesis, secretion and stability of the different pancreatic enzymes could be affected diversely by feeding regimens.

Adaptation, Physiological↗
PubMed1984

Immunocytochemical localization of opsin in the cell membrane of developing rat retinal photoreceptors.

Mature retinal rod photoreceptors sequester opsin in the disk and plasma membranes of the rod outer segment (ROS). Opsin is synthesized in the inner segment and is transferred to the outer segment along the connecting cilium that joins the two compartments. We have investigated early stages of retinal development during which the polarized distribution of opsin is established in the rod photoreceptor cell. Retinas were isolated from newborn rats, 3-21 d old, and incubated with affinity purified biotinyl-sheep anti-bovine opsin followed by avidin-ferritin. At early postnatal ages prior to the development of the ROS, opsin is labeled by antiopsin on the inner segment plasma membrane. At the fifth postnatal day, as ROS formation begins opsin was detected on the connecting cilium plasma membrane. However, the labeling density of the ciliary plasma membrane was not uniform: the proximal cilium was relatively unlabeled in comparison with the distal cilium and the ROS plasma membrane. In nearly mature rat retinas, opsin was no longer detected on the inner segment plasma membrane. A similar polarized distribution of opsin was also observed in adult human rod photoreceptor cells labeled with the same antibodies. These results suggest that some component(s) of the connecting cilium and its plasma membrane may participate in establishing and maintaining the polarized distribution of opsin.

Age Factors↗
PubMed1984

Epidermal Langerhans' cells in Behçet's disease.

Langerhans' cells were studied in the epidermis of two patients with active Behçet's disease and compared with those in two normal controls. Ultrastructural morphology and the percentage of Langerhans' cells found were similar in patients' (1.88%) and the control epidermis (1.79%). The density of Langerhans' cells in adjacent sites of the same epidermis was not homogeneous, being in the range of 0.8-2.8% in Behçet's disease and 0.6-4% in the controls. In the controls, Langerhans' cells were distributed unevenly. Some were located near the basal layer of the epidermis while the rest were in the mid and upper layers. In Behçet's disease most Langerhans' cells were in the mid-epidermis, but some were immediately beneath the stratum granulosum. In the Behçet's disease epidermis the area occupied by Langerhans' cells was increased by about 25% and the number of granules found increased by about 44%. It is suggested that in Behçet's disease the Langerhans' cells are in a more active state.

Adolescent↗
PubMed1984

Pseudoexfoliation: epidemiology, clinical and scanning electron microscopic study.

The prevalence of pseudoexfoliation among patients of Sephardic origin was more than twice the expected when compared with the ethnic distribution of the population consulting the Rambam Medical Center eye clinic. A strong association between brown irises and pseudoexfoliation was noted. No uniform scanning electron microscope pattern was seen of the pseudoexfoliation.

Aged↗
PubMed1984

Preembedding labeling with biotinylated antibodies and subsequent visualization of the biotin groups exposed on thin sections.

The feasibility of labeling cell membranes with biotinylated ligands and detecting the biotin groups on thin sections was investigated. Fixed retinal tissue was incubated with biotinyl- antiopsin . Half of the biotinyl-antibody labeled retinal tissue was incubated with avidin-ferritin (AvF) and embedded in Epon (preembedding reaction). The second half was embedded in glutaraldehyde cross-linked bovine serum albumin (BSA). Thin sections of this preparation were incubated with AvF to detect biotinyl-antibodies exposed by the sectioning (postembedding reaction). Biotin groups on the thin section surface could be readily visualized with AvF. Stereoscopic images demonstrated that the ferritin particles were localized only on the exposed surface of the thin section. The labeling was highly specific, with a very low background. Quantitative analysis was employed in order to determine the optimal reaction conditions for maximizing the labeling density with minimizing nonspecific binding. The possibility of using biotinylated molecules in the study of dynamic cellular events and for the subsequent intracellular localization of biotin on thin sections is suggested.

Animals↗
PubMed1984

Selection for body weight at eight weeks of age. 17. Overfeeding.

Female chicks from lines selected for high and low body weight and their reciprocal F1 crosses were overfed via force feeding to crop capacity from hatching to 21 days of age. Low-weight line chicks could be overfed at an earlier age to a greater extent than those from the high-weight line and F1 progeny. The degree of overfeeding appeared to be associated with the relative size of certain gastrointestinal components. Differences among lines in their capacity to be overfed were reflected in concomitant changes in body weight and carcass fat. Relationships among feed consumption and growth are discussed within the context of selection for body weight and heterosis under various feeding regimens.

Animals↗
PubMed1984

Fertility and behavioral responses of roosters to diets differing in protein and calcium.

Diets differing in calcium (approximately 3.2 and .9%) and protein (15 and 12%) were fed to assess their effects on fertility, behavior, and physiological traits of White Leghorn males from lines selected for high (HA) and low (LA) antibody titers in response to the administration of sheep erythrocytes. Two trials, terminated when the males were 721 and 380 days of age, respectively, were conducted. In Trial 1, the HA males consumed significantly more feed than the LA males and those fed the low protein diets consumed more feed than those fed the high protein diets. No significant differences in feed intake were observed in Trial 2. Neither line, calcium level, nor protein level had a consistent effect on body weight in either trial. There were no significant first or second order interactions between main effects. Comparisons within ages and trials for percentage and duration of fertility revealed no significant differences between lines, protein level, or calcium level. Although the HA males produced significantly more antibodies to canine erythrocytes, dietary effects on antibody titers, heterophil: lymphocyte ratios, and plasma corticosterone were not significant. Thus, there was no indication that dietary treatments were inducing physiological adaptation. Behavioral adaptations, however, were observed; differences were significant for fear, territoriality, air pecking, and head shaking. It was concluded that behavioral responses symptomatic of nutrient deficiencies occur when no overt deficiency is present; this infers that an animal's well-being cannot be assessed strictly on the basis of behavioral consequences.

Animals↗
PubMed1984

The blood-tissue barrier of human brain tumors: correlation of scintigraphic and ultrastructural findings: concise communication.

Through the first 2 hr, uptake of [Tc-99m]pertechnetate and of Co-57 bleomycin were assessed in 29 brain tumors and were correlated with the ultrastructure of the tumor's capillary endothelium. No difference in uptake was found between the two tracers. Permeability of brain tumors to these agents was found to be governed by the same ultrastructural features that determine permeability in experimental brain tumors: the type of junction between contiguous endothelial cells in the capillaries. Meningiomas, which showed very high uptake of the radiotracers, demonstrated open or punctate junctions with short fusion of apposed membranes. They also showed a large number of pinocytotic vesicles and fenestrae. Capillaries of tumors without uptake had a small number of short tight junctions (less than 0.25 mu) between adjacent endothelial cells and a relatively large number of long junctions (greater than 0.5 mu). In intracerebral tumors that showed relatively high uptake, the reverse was true: most of the junctions were short and only a few long junctions were found. That uptake of [Tc-99m]pertechnetate and of Co-57 bleomycin depends on tumor capillary ultrastructure (which determines the permeability) suggests the possibility of the use of radiopharmaceuticals as in vivo indicators of tumor permeability. Brain scintigraphy may help to asses brain-tumor availability to non-lipid-soluble chemotherapeutic drugs.

Bleomycin↗