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Biomedical subjects

B Singh

Publications and source records attributed to B Singh.

At least 811 records · Page 45Linked to original sources
PubMed1982

Maintenance of long junctional epithelium in the rat.

The dynamics of the long junctional epithelium in rat gingivae were observed over a period of from three to six mo. In addition, the cellular dynamics of the epithelium were also evaluated at the end of three and six mo. The results of this study indicated that this model system cannot be used to study the long-term dynamics of long junctional epithelia. This study also indicated that the epithelial cuff increased in length with time, that it is a self-renewing tissue, and that long junctional epithelia may reduce in length with time due to sulcus deepening which was not related to subepithelial inflammation.

Animals↗
PubMed1981

Antigen recognition. V. Requirement for histocompatibility between antigen-presenting cell and B cell in the response to a thymus-dependent antigen, and lack of allogeneic restriction between T and B cells.

The restrictions imposed by the major histocompatibility complex on T-B-antigen-presenting cell (APC) interactions were studied with an in vivo adoptive transfer system, using mutually tolerant T and B cells taken from one-way fetal liver chimeras. It was found that the B cells and adoptive recipient (which provides APC function) have to share determinants encoded by the left-hand end of the H-2 complex for cooperation, whereas there is apparently no such requirement for T-B cell syngeneicity. Suppression arising from allogeneic effects between the host and the transferred T or B cells was excluded by the use of tolerant as well as normal adoptive recipients; both were functionally equivalent. We conclude that under experimental conditions, unrestricted helper T cell function and concurrent APC-B cell genetic restriction can be demonstrated in vivo.

Animals↗
PubMed1981

Mechanism of participation of medial preoptic area in the hippocampal inhibition of ovulation.

Bilateral hippocampal (HPC) stimulation with anodal direct current on the afternoon of proestrus blocked spontaneous ovulation in 87.5% of the Wistar rats subjected to the experiments. The incidence of the ovulation block by this procedure was reduced to 16.7% on bilateral injection of 0.25 microgram picrotoxin into the medial preoptic area (mPOA) preceding as well as following the stimulation. Ovulation was also blocked in 53.8% of the animals by bilateral injection of 50.0 microgram GABA into mPOA, while only 20.0% animals showed a blockade of ovulation by saline injection into mPOA. These observations indicate that blockade of ovulation by HPC stimulation can be simulated by local injection of GABA into mPOA while the effect of stimulation can be blocked by local injection of picrotoxin. Thus, indicating the possibility of GABA being neurotransmitter involved at the level of mPOA for mediating the inhibitory hippocampal influence on ovulation.

Animals↗
PubMed1981

Monoclonal antibodies showing sequence specificity in their interaction with single-stranded DNAs.

Six hybridoma cell lines which secrete monoclonal antibodies binding to nucleic acids were produced from autoimmune NZB/NZW mice. Four of the antibodies were IgG's and the other two were IgM's. Using a solid phase radioimmunoassay (SPRIA) the binding of the antibodies to over thirty different nucleic acids was estimated. All the antibodies were extremely specific. There was no detectable interaction with various RNAs, and single-stranded DNAs bound more antibodies than duplex or multi-stranded DNAs. In every case the antibodies also showed considerable sequence preferences. For example one monoclonal antibody bound to d(TTC)n but not to d(TCC)n while another interacted strongly with D(TG)n and d(CA)n but not with d(TC)n, d(GA)n or homopolymers. In other cases the patterns of sequence specificity were extremely difficult to interpret although it seems clear that monoclonal antibodies have the potential to distinguish between any two nucleic acids however similar.

Animals↗
PubMed1981

Postdisaster morbidity of the bereaved. A possible role for preventive psychiatry?

Immediately following a rail disaster in Sydney, Australia, on January 18, 1977, in which 83 people were killed, an attempt was made to organize a preventive psychiatry outreach program for the relatives of the bereaved and the survivors. Bereavement counseling was offered to all families considered to be at risk for development of postbereavement morbidity. A follow-up study was performed 15 to 18 months later to assess the level of functioning of the bereaved relatives. The next of kin of 36 victims (43 per cent of the total number killed) were interviewed and filled in questionnaires (general health, Goldberg's General Health Questionnaire, loss, and social support). They included 15 widows, nine widowers, 11 mothers, and eight fathers who had lost children. The trends were for the bereaved spouses to have done better than bereaved parents; the widowers to have done better than the widows; those with a supportive network to have done better than those without one; those who saw the body to have done better than those who did not; and, in addition, there was a tendency for those who had bereavement counseling to do better than those who had no such intervention. Examples are given of several types of outcome, and conclusions are drawn about the results and the difficulties of implementing and evaluating such a program.

Accidents↗
PubMed1981

Low cardiac output states after open heart surgery. Comparative hemodynamic effects of dobutamine, dopamine, and norepinephrine plus phentolamine.

The hemodynamic effects of dobutamine, dopamine, and a combination of norepinephrine-phentolamine were compared in nine patients with low cardiac output state after open heart surgery. Using a Latin square design for drug sequence, each patient was given each drug at three levels by continuous intravenous infusion. For dobutamine and dopamine the doses were 2.5, 5.0 and 10.0 microgram/kg/min; for norepinephrine, 0.02, 0.05 and 0.10 microgram/kg/min with phentolamine in the ratio of 1 (norepinephrine) to 2.5 (phentolamine). Dobutamine and dopamine both produced an increase in heart rate, mean arterial pressure, cardiac index, and stroke volume index. Both drugs reduced total pulmonary and systemic vascular resistance in the dose range of 5.0 to 10.0 microgram/kg/min. When the maximum tolerated doses were compared, the drugs equally increased cardiac index and stroke volume index, but dopamine did so at a smaller dose than dobutamine. At equivalent doses, dobutamine tended to produce less tachycardia and vasoconstriction than dopamine. The norepinephrine-phentolamine combination resulted in increases in both systemic arterial pressure and vascular resistance with no significant increase in cardiac index. Its unique feature was its predictable vasopressor response with absence of chronotropic effects and ventricular irritability.

Cardiac Output, Low↗
PubMed1981

The ontogeny and turnover kinetics of paternal H-2K antigenic determinants on the allogeneic murine placenta.

In previous reports we provided evidence for the expression of paternal H-2Kk antigens on the placenta, accessible to maternal circulation. We have now examined the ontogeny of paternal H-2Kk antigens in the placenta from day 10 to day 17 of gestation and find a steady increase per gram placenta. In order to substantiate the proposal that the placenta functions as an immunoabsorbent barrier preventing the entry of anti-paternal antibodies to the fetus, we monitored the uptake of monoclonal anti-paternal H-2Kk antibody by target (antigen-bearing) and control fetuses and placentas at various intervals after injection. We have previously shown that F(ab')2 anti-H-2Kk behaves like intact immunoglobulin in placental immunoabsorption studies, and demonstrate here that the peak placental uptake of the antibody is not affected by the removal of the Fc portion, whereas its rate of clearance is increased. In contrast to the anti-H-2Kk antibody, monoclonal anti-I-Ak (specificity 17) antibody (IgG2a) shows no placental immunoabsorption.

Animals↗