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Biomedical subjects

M S Kumar

Publications and source records attributed to M S Kumar.

At least 91 records · Page 5Linked to original sources
PubMed1987

Substance P and luteinizing hormone-releasing hormone levels in the brain of the male golden hamster are both altered by castration and testosterone replacement.

The effects of castration and testosterone (T) replacement on levels of substance P (SP) and luteinizing hormone-releasing hormone (LHRH) were assessed in discrete areas of the male hamster brain. The animals were either castrated, castrated and given a chronically low or high dose of T by Silastic implant, or sham-operated. Brain tissues and trunk blood were collected 3 weeks after surgery. Plasma T levels were maintained within the normal range by the implants but at significantly lower or higher levels than the mean for sham-operated males. Levels of SP and LHRH were quantified in the olfactory bulbs, rostral basal forebrain, anterior hypothalamic and preoptic area, medial basal hypothalamic area, medial basal hypothalamic area and median eminence, and brain stem. In general, castration and T replacement effected opposite changes in levels of SP and LHRH. In the medial basal hypothalamic area and median eminence SP levels were found to be inversely related to the chronic T levels, whereas the LHRH levels were directly correlated. In the anterior hypothalamic and preoptic area, castration reduced levels of SP. Conversely, castration elevated levels of LHRH in this area. This inverse dynamic relationship between changing peptide levels was also observed in the rostral basal forebrain but not in the olfactory bulbs. In most of these forebrain regions, the dose-response curves for the experimental groups could not incorporate the peptide levels in the sham-operated control group. SP levels in the brain stem showed a monotonic inverse relationship to circulating T levels which did include the control group values.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Limiting factors in successful preservation of cadaveric kidneys with ischemia time exceeding 50 hours.

The results of 61 cadaveric allografts preserved for 30 to 76 hours were analyzed to determine the effect of cold ischemia time, the method of preservation, and the type of immunosuppression on early graft viability and long-term graft survival. Preservation in cold storage up to 50 hours gave a low incidence of nonfunction (4%) and of posttransplant dialysis (20%) and a high rate of function both at 1 month (96%) and at 2 years (60%). Cold ischemia time greater than 50 hours caused a significantly increased need for dialysis (58%) but without appreciable difference in graft function at 1 month or at 2 years. Preservation by machine had no advantage over preservation by simple cold storage when the cold ischemia time was less than 50 hours. When cold ischemia time exceeded 50 hours, machine preservation was associated with a significantly reduced incidence of posttransplant dialysis but without significant differences in long-term function at 2 years. With up to 50 hours of cold ischemia and providing there was no ATN, CsA had little nephrotoxicity and gave excellent graft function at 1 month and at 2 years. However, the nephrotoxicity of CsA was markedly increased when the preservation interval exceeded 50 hours, resulting in a significantly increased rate of primary nonfunction and the need for dialysis with a significant decrease in graft function at 1 month and at 2 years. The nephrotoxicity of CsA was considerably decreased or eliminated without affecting its powerful immunosuppressive property when initial immunosuppression was begun with azathioprine with sequential conversion to CsA when graft function was fully established. It is recommended that when cold ischemia is long or when there is ATN, CsA should be used as a sequential therapy to azathioprine after graft diuresis or, alternatively, in much smaller doses as part of a combination therapy with azathioprine.

Azathioprine↗
PubMed1986

HLA, MLR, P and Lewis antigens and living donor renal transplantation in a single centre in the Middle East.

One hundred and fifty-one living donor renal transplants performed in a single centre in Kuwait were analysed for graft survival in relation to HLA matching, mixed lymphocyte reaction (MLR), P and Lewis antigens. There was a significant difference in graft survival (P = .05) but only at 3, 4 and 5 years between HLA identical (97%, 94%, 94%) and haploidentical combinations (83%, 81% and 79%), respectively. The zero haplotype matched combinations were not significantly different in graft survival from the identical or haploidentical groups. Compatibility or incompatibility for P or Lewis antigens did not influence graft survival. The MLR was significant (P = .05) with the MLR negative recipients having 100% graft survival at 4 years compared to 84% in the MLR positive group. In conclusion with an overall actuarial graft survival of 84% at 6 years none of the factors examined 'dramatically' influenced graft survival. The 'Centre Effect' is the main factor influencing graft survival in our Centre.

Blood Group Antigens↗
PubMed1985

Effect of delta 9-THC on brain and plasma catecholamine levels as measured by HPLC.

The effects of chronic administration of delta 9-tetrahydrocannabinol (delta 9-THC) on the plasma and brain catecholamine (CA) levels were measured using high performance liquid chromatography-electrochemical detection (LC-EC) system. Intact male rats were injected daily with vehicle (50 microliter oil) or with delta 9-THC (3 mg/kg body wt) over a period of 25 days. Trunk plasma and tissue from preoptic area (POA) and mediobasal hypothalamus (MBH) were collected and catecholamine levels were detected by LC-EC system coupled to an electronic integrator. Alumina extract of tissue and plasma samples, spiked with the internal standard (dihydroxybenzylamine), were injected into the LC-EC system; the CA were chromatographed and eluted within 12 minutes using sodium phosphate buffer as the mobile phase. delta 9-THC treatment resulted in a significant decrease in plasma and MBH levels of norepinephrine (NE), epinephrine (E), POA levels of NE; and significant increases in MBH levels of dopamine (DA) and dihydroxyphenylacetic acid (DOPAC). Our study indicates for the first time that delta 9-THC treatment significantly alters not only the POA and MBH CA levels, but also the plasma CA levels.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1985

Effects of acute and subchronic delta 9-tetrahydrocannabinol administration on the plasma catecholamine, beta-endorphin, and corticosterone levels and splenic natural killer cell activity in rats.

The effect of acute (1 day) or subchronic (25 days) treatment with delta 9-tetrahydrocannabinol (THC), the major psychoactive constituent of marihuana, on plasma norepinephrine (NE), epinephrine (E), corticosterone, beta-endorphin (beta-end), and splenic natural killer (NK) cell activity of the rat was studied. Groups of animals received subcutaneously, either THC in corn oil + saline (3 mg THC/kg); oil + saline; or THC + naloxone (2 mg naloxone/kg and 3 mg THC/kg). Acute injection of THC with or without naloxone did not significantly change plasma levels of NE, E corticosterone, beta-end, or the NK cell activity. However, subchronic treatment with THC significantly reduced plasma levels of NE, E, corticosterone, and NK cell activity, compared to controls. The plasma beta-end levels were significantly elevated in the THC-treated animals. In the THC + naloxone group of animals, the plasma hormone levels (corticosterone and beta-end) were similar to control levels and the NK cell activity was significantly higher than in THC-treated animals. These results indicate that subchronic exposure to THC results in suppression of splenic NK cell activity. The interaction of THC with the endogenous opiate system appears to be a contributing factor leading to the NK cell suppression in rats. A direct suppressive action of THC or its metabolites on the NK cell is not ruled out by this study.

Animals↗