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Biomedical subjects

A Singh

Publications and source records attributed to A Singh.

At least 505 records · Page 28Linked to original sources
PubMed1992

Consumption of a dehydrated ration for 31 days at moderate altitudes: status of zinc, copper, and vitamin B-6.

Intake of energy zinc, copper, and vitamin B-6 and indexes of zinc, copper and vitamin B-6 status were determined for eight men who consumed a high-carbohydrate dehydrated ration for 31 days of high activity at moderate altitudes (2,400 to 4,300 m). Data were collected 2 months before exposure (PRE), four times during the month at moderate altitudes (ALT), and 1 month after return (RET). Mean (+/- standard error) energy intake was 2,725 +/- 215, 3,430 +/- 79, and 3,370 +/- 215 kcal/day during PRE, ALT, and RET, respectively. Zinc and copper intakes averaged 10.6 +/- 1.6 and 1.0 +/- 0.1 mg/day during PRE and increased significantly to 16.9 +/- 0.7 and 3.5 +/- 0.1 mg/day during ALT; zinc and copper intakes were 15.5 +/- 1.6 and 1.9 +/- 0.3 mg/day for RET, respectively. Similarly, vitamin B-6 intake was significantly higher during ALT (PRE = 2.2 +/- 0.5 mg/day; ALT = 4.2 +/- 0.4 mg/day; and RET = 2.6 +/- 0.4 mg/day) as compared with PRE and RET. No significant changes were noted for plasma zinc, copper, or their related proteins or plasma or erythrocyte pyridoxal-5'-phosphate. Finally, no changes in urinary excretion of zinc were observed. The results indicate that dehydrated rations provide zinc, copper, and vitamin B-6 in amounts above the Recommended Dietary Allowances. Such diets may be consumed for at least 1 month without compromising status for these nutrients.

Adult↗
PubMed1992

Dermal exposure to detergents.

Epidermal erosion and a 40-60% increase in histamine content of skin were observed in guinea pigs treated with different concentrations of detergents. The primary irritation indices of these animals ranged between 0.3 and 1.5. Eight human subjects with skin lesions attributable to detergent exposure were patch tested with 500 mg of detergents. A positive reaction was observed in 7 of 8 cases. In 4 cases reaction was observed within 24-48 h, while 3 cases had a severe reaction after 72 h. IgA and IgM levels were raised in 2 subjects. This study highlights the irritancy potential and toxic effects of detergent products available in Indian markets.

Animals↗
PubMed1992

Induction and regulation of D-xylose catabolizing enzymes in Fusarium oxysporum.

In Fusarium oxysporum DSM 841, the requirement of oxygen was found to be associated with the induction of key D-xylose catabolizing enzymes. NADPH-linked D-xylose reductase and NAD-linked xylitol dehydrogenase. Both enzymes were detected in cell free extracts of F. oxysporum grown in the medium containing D-xylose, L-arabinose and D-galactose as substrate. D-xylose, L-arabinose and D-galactose were also found to be substrates for NADPH-linked activities. However, unlike xylitol, neither L-arabitol nor galactitol supported the NAD-linked reactions, suggesting the diversion of metabolic pathways of L-arabinose and D-galactose from that of D-xylose following formation of pentitol.

Aldehyde Reductase↗
PubMed1992

Dermal toxicity of paraphenylenediamine.

The guinea pigs were dermally exposed to paraphenylenediamine (PPD) and in presence of an oxidising agent hydrogen peroxide for 15 and 30 d to assess their effects on some enzymes, lipid peroxidation and histamine contents in the skin. The activities of acid and alkaline phosphatases, beta-glucuronidase, gamma glutamyl transpeptidase, histidase and tyrosinase were enhanced after application of either PPD or PPD plus hydrogen peroxide. The lipid peroxidation and histamine contents also showed marked elevation following exposure to the chemicals.

Acid Phosphatase↗
PubMed1992

Percutaneous transabdominal hepatic needle biopsies in dogs.

Ninety-six (4/dog) percutaneous transabdominal hepatic needle biopsy specimens were obtained from 24 dogs each weighing 10 to 24 kg. Two biopsies were performed in each dog prior to and 5 days after hepatopathy was experimentally induced. Information pertaining to the difficulty encountered in obtaining hepatic tissue is reported for the first of each pair of biopsies. All specimens were of diagnostic quality for light and electron microscopic evaluation. Adverse consequences (morbidity or mortality) resulting from the biopsy technique were not observed by monitoring of vital signs in the immediate postprocedure period and at 4 weeks. Recovery to an ambulatory state was seen in less than or equal to 30 minutes, except in 1 dog, in which prolonged recovery was attributed to acetylpromazine-induced hypotension.

Acepromazine↗
PubMed1992

Hormonal responses to ingesting water or a carbohydrate beverage during a 2 h run.

Ingestion of fluids providing carbohydrate and electrolytes extends endurance times during prolonged exercise. To understand the contribution of these factors, we examined hormonal, physiologic, and metabolic responses to ingesting water (W) or a 7% glucose polymer/fructose/electrolyte solution (GPFE) in 10 men (age: 30 +/- 2 yr, VO2max: 57.4 +/- 3.2 ml.kg-1.min-1) who ran on a treadmill for 2 h at 60-65% of their VO2max. Subjects drank 200 ml of W or GPFE at 0-time and every 30 min while running (30,60, and 90 min). Changes in serum sodium, potassium, and osmolality; heart rate; plasma lactate and glucose; and serum insulin and plasma norepinephrine were similar for both fluid treatments. In contrast, changes in serum free fatty acids (FFA), plasma cortisol, and arginine vasopressin (AVP) differed across fluid treatments: with GPFE, exercise abolished the rise in plasma cortisol, and attenuated the rise in both AVP and FFA. The observed suppression of cortisol and AVP was not related to changes in any of the parameters examined, but were strongly correlated with each other. These findings suggest that adding carbohydrate and electrolytes to fluids ingested during prolonged exercise decreases activation of the hypothalamic-pituitary-adrenal axis, a potentially beneficial change. However, mobilization of FFA was also decreased. The mechanism by which they occur remains elusive.

Adult↗
PubMed1992

Plasma zinc uptake from a supplement during submaximal running.

The uptake of zinc (Zn) into the plasma after the ingestion of 25 mg of Zn from multivitamin-mineral supplement was studied in 10 men during running (R) and control (C) conditions; the R was for 2 h at 60-65% of their maximal oxygen uptake. Subjects took the supplement with 200 ml of deionized water before the R or C (0-time). Blood was drawn before the Zn load and every 30 min for 3 h. By 2 h, plasma Zn concentrations had risen to values that were 151 +/- 7% and 149 +/- 5% of (0-time) R and C concentrations, respectively. Furthermore, the average rates of Zn uptake into the plasma did not differ between the R and C (4.4 vs 3.8 mumol.l-1.h-1) conditions. Finally, areas under the curve were not different (R: 13.2 +/- 1.8 mumol.l-1.3h-1; C: 11.5 +/- 1.5 mumol.l-1.3h-1). In summary, submaximal endurance running did not affect plasma Zn uptake and therefore absorption of Zn from a supplement taken just prior to exercise. The effect of chronic exercise on Zn absorption remains to be determined.

Absorption↗
PubMed1992

Regional variation in ontogeny of class II antigens in enterocytes of mouse small intestine.

The ontogeny of major histocompatibility class II antigens in small intestine enterocytes of postnatal C3H/He mice was investigated. Cryosections of duodenal, jejunal, and ileal segments from 7-, 14-, 16-, 20-, 21-, 23-, 25-, 27-, 28-day-old and 7-week-old mice were stained for the class II antigens with MRC OX6 monoclonal antibodies by peroxidase-antiperoxidase labelling. In adults, the duodenum exhibited least expression of class II antigens that increased progressively towards the ileum. The expression in the villous epithelium was first seen in the duodenum and jejunum 21 days after birth but the ileal enterocytes did not exhibit any class II antigens. The earliest appearance (21 days postnatal) of class II antigens in the enterocytes coincides with the age of weaning which suggests that immunologic stimulation by ingested antigens after weaning may influence expression of these antigens. At day 28 after birth, the duodenum and jejunum expressed levels comparable to those in the adults. The first expression of the antigens seen in the ileum was at day 28 postpartum. Crypt epithelium of the three regions of the small intestine showed expression similar to that of corresponding regional villous enterocytes. We conclude that there is an age-dependent regional variation in the expression of class II antigens in enterocytes, and the expression increases with age. The variation in expression of the class II antigens in enterocytes of postnatal mice is attributed to the developmental status of the tissue. The nature of postnatal expression of the antigens is important since an early appearance of these antigens may have implications in autoimmunity.

Aging↗
PubMed1992

Chronic multivitamin-mineral supplementation does not enhance physical performance.

The effects on physical performance of 90 d of supplementation with a high potency multivitamin-mineral supplement were studied in a double-blind, placebo-controlled design. Twenty-two healthy, physically active men were randomly assigned to a supplement (S) or placebo (P) group; both groups had similar physical characteristics. Performance was assessed from maximal aerobic capacity, endurance capacity, and isokinetic tests. Supplementation did not affect maximal aerobic capacity: pre and after approximately 12 wk of supplementation values for maximal oxygen consumption (48.5 +/- 1.3 vs 46.2 +/- 1.1 ml.kg-1.min-1), maximal heart rate (186 +/- 2 vs 187 +/- 2 beats.min-1) or treadmill time (19.96 +/- 0.48 vs 19.99 +/- 0.37 min) did not differ in the S group; similar findings were noted in the P group. Performance during the 90-min endurance run, as assessed from heart rates, rectal temperatures, and plasma glucose, lactate and adrenocorticotropin values, was not affected by treatment. Similarly, muscle strength and endurance were not affected. Thus, supplementation did not affect physical performance in well-nourished men who maintained their physical activity.

Adult↗
PubMed1992

Dermal exposure of hexachlorophene to guinea pigs.

The skins of guinea pigs were exposed to 50 mg/kg hexachlorophene (HCP) for 7, 15 or 30 days. The activities of skin marker enzymes (beta-glucuronidase, histidase, tyrosinase) increased, but glutathione decreased. Lipid peroxidation and histamine contents increased during different time intervals. The histopathological changes showed damage to epidermis and dermis. Depending on the duration of exposure, HCP produces biochemical and histopathological damage to skin.

Animals↗
PubMed1992

Radiographic and neuro-SPECT imaging in an immature third ventricle teratoma: case report.

We report a case of an immature teratoma of the third ventricle, which was preoperatively thought to be a choroid plexus papilloma. The diagnosis was made by biopsy since the radiographic (CT, MRI), angiographic and scintigraphic findings ([99mTc]pertechnetate, 99mTc-DTPA, 99mTc-HMPAO brain SPECT) were nonspecific. Disruption of the blood-brain barrier is the mechanism for radionuclidic and contrast tumoral uptake and is demonstrated by marked contrast enhancement on CT and focal concentration on [99mTc]pertechnetate and 99mTc-DTPA images. No suppression of [99mTc]pertechnetate tumor uptake was observed following the administration of potassium perchlorate. Increased concentration of tumor protein is suggested by the increased signal on the T1-weighted magnetic resonance images and high [99mTc]pertechnetate uptake. The tumor's detection on the 99mTc-HMPAO brain SPECT was due to its intraventricular location. A number of potential mechanisms for brain tumor localization of 99mTc-HMPAO are discussed.

Cerebral Ventricle Neoplasms↗
PubMed1991

The effect of HP-1 and related neutrophil granule peptides on DNA synthesis in HL60 cells.

The recently isolated cysteine- and arginine-rich peptides of the neutrophil primary granule and the murine intestinal Paneth cell, named defensins or corticostatins, have a number of distinct biological properties. We report the effects of three of these peptides HP-1, HP-1-56 and HP-4 on the incorporation of [3H]thymidine into the DNA of the leukemic cell line HL60. HP-1 and HP-1-56, but not HP-4, inhibited DNA synthesis at 1-50 nM without causing cell death. At higher concentrations the effect was reversed, resulting in a small, but statistically significant increase in DNA synthesis at 1 microM. In contrast HP-4 had no effect on HL60 cells at nanomolar concentrations but was strongly cytotoxic at micromolar concentrations.

Amino Acid Sequence↗
PubMed1991

Superoxide dismutase activity regulation by spermine: a new dimension in spermine biochemistry and sperm development.

Amines are a group of highly important compounds of biological importance; they are known promoters of cell growth, can complex with nucleic acids and can stimulate DNA-primed RNA polymerase activity. Spermine, a polyamine abundantly present in the secretions of the male accessory sex organs, has received no functional attributes till date. This study had been a pioneer attempt to validate the hypothesis of a metalloenzyme activity modulation by spermine and implicit correlations have been drawn.

Animals↗
PubMed1991

Superoxide dismutase activation in thyroid and suppression in adrenal. Novel pituitary regulatory routes.

This study reports that administration of TSH in young female mice results in a concomitant augmentation of SOD activity in the thyroid gland. A strong thyroid-adrenal interdependence was also evident in the form of a marked loss of SOD activity in the adrenal gland in response to TSH administration. Very recently SOD/O2.- system had been identified as a potent H2O2 generator which provides substrate for the action of key enzyme in thyroxine and progesterone biosynthesis, viz. the peroxidase. Thus, these results strongly suggest that trophic hormones tonically stimulate hormone biosynthesis by modulating activation/suppression of specific enzymes, which could be the basis of the tuning sequence.

Adrenal Glands↗
PubMed1991

The isolation and identification of multiple forms of the neutrophil granule peptides from human leukemic cells.

HP-1 is a 30-residue cysteine- and arginine-rich peptide of the human neutrophil primary granule and is the most abundant human representative of the family of peptides variously called defensins and corticostatins. Peptides belonging to this family have many biological activities including the non-oxidative destruction of ingested microorganisms, the inhibition of adrenocorticotropin-stimulated synthesis of glucocorticoids, monocyte chemotaxis, the non-cytolytic inhibition of [3H]thymidine incorporation in HL-60 promyelocyte-like cells and the stimulation of nifedipine-sensitive calcium channels. Using a combination of reversed-phase and size-exclusion high performance liquid chromatography and an HP-1 radio-immunoassay, three immunoreactive peptides were detected and isolated from the promyelocyte-like cell line, HL-60, and from leukocytes of patients with chronic myelogenous and chronic lymphocytic leukemias. One of these peptides was HP-1 itself. A second was identified by gas-phase Edman microsequencing as an amino-terminally extended fragment of the HP-1 precursor which we call HP1-56. The third is likely to arise from enzymatic cleavage of the precursor at a dibasic site. Of the leukemic cells the greatest amount of HP1-56 relative to HP-1 was found in cells from a patient in myeloblastic crisis but overall the richest source of HP1-56 relative to HP-1 was found to be in fetal lung tissue. HP1-56 is difficult to detect in normal peripheral neutrophils and its presence in cells that are actively biosynthesizing primary granule components such as HL-60 may make it useful for studying the biosynthesis of granule polypeptides, their ontogeny, and possibly as a marker protein for leukemic diseases.

Amino Acid Sequence↗