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Biomedical subjects

A Friedman

Publications and source records attributed to A Friedman.

At least 181 records · Page 10Linked to original sources
PubMed1989

The effects of vitamin A, beta-carotene and canthaxanthin on vitamin A metabolism and immune responses in the chick.

Chicks were fed diets containing, 0, 0.85 and 350 mg/kg vitamin A and 1 g/kg beta-carotene or canthaxanthin from hatching. Carotene increased and canthaxanthin depressed plasma and hepatic vitamin A concentrations. High vitamin A levels decreased the concentration of both carotenoids. Neither carotene nor canthaxanthin affected intestinal carotene cleavage in vitro. T-lymphocyte proliferative responses were decreased at low vitamin A intakes and enhanced at the high vitamin A intake. Carotene and canthaxanthin fed with 0.85 mg/kg vitamin A had no effect on immune response and with 350 mg/kg vitamin A prevented the enhancement of the proliferative response. It is concluded that immune response in the chick is modulated by vitamin A; carotene and canthaxanthin effects are probably due to influences on vitamin A metabolism.

Animals↗
PubMed1989

Absence of major histocompatibility complex restriction in the interaction between processed basic protein and Ia of two rat strains.

Antigen fragments, biologically degraded by antigen-presenting cells (APC), combine with Ia positive moieties (IPM) to stimulate antigen-specific T lymphocyte lines. The main objective of this study was to evaluate whether this interaction was determined by the major histocompatibility complex (MHC) genotype of the APC, thus genetically restricting antigen-specific T lymphocyte proliferative responses. To do so, we assayed the capacity of processed basic protein, associated with IPM, to stimulate basic protein specific T lymphocyte lines derived from the Lewis (LW), Brown Norway (BN), and (LW x BN)F1 rat strains. Our findings are that: (a) IPM replaced the requirement for intact APC in proliferative responses of T lymphocytes to processed basic protein; (b) processed basic protein, irrespective of the genotype of APC from which it was prepared, was fully reconstituted by all IPM genotypes tested. Hence, the interaction between processed antigen and IPM was not found to be MHC-restricted. The possible implication of this conclusion is discussed.

Animals↗
PubMed1988

Recombinant human tumor necrosis factor induces acute reductions in food intake and body weight in mice.

We examined the effects of treatment with rHuTNF on food consumption and body weight in C3H/HeJ mice. rHuTNF was administered intraperitoneally either by injections of 3, 12, or 24 micrograms twice a day or by implantation of osmotic pumps that released 0.75, 3, or 12 micrograms per day. Dose-dependent reductions in both food intake and weight were induced by rHuTNF. However, in spite of continued exposure to rHuTNF, the mice developed a resistance to rHuTNF and resumed their pretreatment food intake and weight. Non-immunological factors may play a role in the development of this tolerance, since it developed rapidly and faded within 2 wk of cessation of exposure to rHuTNF.

Animals↗
PubMed1988

Development of beta-amino acid transport in the kidney.

This study focuses on the maturation of the renal beta-amino acid transport system and uses dietary manipulation as a probe. The epithelial surface of the renal proximal tubule is responsible for the conservation of ions and organic solutes including beta-amino acids. This beta-amino acid transport system is stimulated during periods of reduced dietary intake and permits increased excretion following dietary excess. We have examined transport of the sulfur-containing beta-amino acid, taurine, as a measure of this renal adaptive response to fluctuations in dietary sulfur amino acid intake and as a substrate for the beta-amino acid transport system. A precession of taurine uptake values by brush border membrane vesicles (BBMV) prepared from nursing rats from youngest to oldest was evident. However, these membranes demonstrate the full renal adaptive response to altered sulfur amino acid intake after the first week of life. This adaptive response is expressed at the brush border surface by transport changes in both directions ("up regulation" and "down regulation"), through changes in the initial rate (15 sec) of Na+-taurine cotransport. No alterations in the lipid microenvironment of the membrane, as detected by altered membrane fluidity, were uncovered. Although vesicles from 7-day-old pups demonstrate adaptation and accumulate taurine to a limited extent, the accumulation of Na+, which energizes uptake, may be altered, thereby preventing full expression of the adaptive response and of transport capacity at this age.

Amino Acids↗
PubMed1988

Risk identification at the time of admission to coronary care unit in patients with suspected myocardial infarction.

The in-hospital clinical course was evaluated in 2,162 consecutive patients admitted with a diagnosis of suspected myocardial infarction. Of these, 1609 patients were considered to be in the high-risk group, based on the presence of 16 clinical criteria present at the time of admission. The remaining 553 patients were classified as low risk. The overall rate of complications in the coronary care unit was greater in the high-risk group, 64%, compared to 26% in the low-risk group (p less than 0.001). Similarly life-threatening events (occurrence or recurrence of ventricular fibrillation, sustained ventricular tachycardia, complete heart block, asystole, or cardiogenic shock) were more common in the high risk-group compared to the low-risk group, 11% and 0.9%, respectively (p less than 0.001). The high-risk group required significantly more interventions, such as electrical cardioversion, temporary pacing, pulmonary artery catheterization, and intraaortic balloon counterpulsation, compared to the low-risk group (20% vs 2%, respectively; p less than 0.001). Myocardial infarction was confirmed in 892 patients in the high-risk group (55%) compared to 90 (16%) in the low-risk group (p less than 0.001). The coronary care unit mortality rate was greater in the high-risk group compared to the low-risk group (8.2% vs 0.4%, respectively; p less than 0.0002). It is concluded that based on readily available clinical criteria at the time of admission, a subgroup of patients at low risk for developing life-threatening complications requiring coronary care unit interventions can be identified and admitted directly to an intermediate-care unit.

Coronary Care Units↗
PubMed1988

The effect of electrolytic lesions in the baso-medial-hypothalamus on the immune response of the chicken.

Electrolytic lesions of the baso-medial-hypothalamus (BMH) cause numerous dysfunctions of the endocrine system, many of which have been implicated in regulating immune responses. The objective of this report was to evaluate the direct effects of electrolytic lesions in the BMH on the immune response of the chicken. Our results indicate that temporary immune response impairment, as evaluated by both T and B lymphocyte related responses, occurred only in birds that expressed both brain damage and endocrine dysfunction, whereas birds expressing brain damage alone had normal immune responses. The possible regulation of immune responses by the BMH via the endocrine system is discussed.

Animals↗
PubMed1988

Treatment of cervical pregnancy with methotrexate.

A case of cervical pregnancy was treated successfully with methotrexate. We used serial beta-human chorionic gonadotropin levels, magnetic resonance imaging, and sonography to diagnose the pregnancy and monitor therapy. Hysterectomy was avoided, and the patient's reproductive capability was preserved. Toxicity was limited to transient elevation of liver transaminases.

Adult↗
PubMed1987

Low-threshold calcium electrogenesis in neocortical neurons.

In slices of parietal neocortex, evidence was obtained for the existence of a low-threshold Ca2+ conductance in most neurons. This conductance became apparent when resting membrane potential was held below -60 mV by continuously injected, depolarizing current. Under these conditions, brief hyperpolarizing pulses were followed by generation of tetrodotoxin (TTX)-resistant, Mn2+-sensitive, low-threshold spikes. The results suggest that in neocortex, as in many subcortical structures, low-threshold Ca current may be responsible for burst generation in some neurons.

Animals↗
PubMed1987

Assessment for evidence of non A-non B hepatitis in patients given n-heptane-suspended heat-treated clotting factor concentrates.

Nineteen patients, (2 adults, 17 children) with inherited bleeding disorders were infused with n-heptane-suspended-heated clotting factor concentrates. Twelve of the nineteen were previously untreated. Six patients were infused with Profilnine Heat-Treated and 13 with Profilate Heat-Treated. Five separate centers participated and were given various lots of concentrates for use. Blood from the seventeen children was sampled prior to entry, at infusion, 2 weeks, 6 weeks, 12 weeks and 6 months after the first infusion. The two adults were sampled every 2 weeks. Twelve of the 19 patients were followed beyond six months. Three patients demonstrated a rise in ALT during the first six months of observation with levels above 2.5 times the upper limit of normal. One of these patients showed a parallel increment in a-CMV IgM titer and a second patient, an adult, had previously received many units of single donor blood components. During the second 6 month observation interval, two patients showed a rise in ALT. One of these patients had been exposed to only one lot of concentrate with no other viral cause being determined. Two additional patients had a moderate increase in ALT up to 98 U/L (normal less than 50). No patients were clinically ill or showed jaundice during these episodes. The hepatitis episode at 11 months in the patient using one lot of concentrate, might suggest a non-viral mechanism in this instance. This study indicates that these concentrates may be associated with episodes of ALT above 2.5 times the upper limit of normal in approximately 20% of the patients treated, but the etiology of the raised ALT may not always be Non A-Non B hepatitis.

Adult↗