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Biomedical subjects

K K Singh

Publications and source records attributed to K K Singh.

At least 19 recordsLinked to original sources
PubMed1992

Interrogative suggestibility among adolescent boys and its relationship with intelligence, memory, and cognitive set.

This study investigates some of the hypotheses generated by the Gudjonsson and Clark model of interrogative suggestibility. The subjects were 40 adolescent boys (11-16 years), who completed the Gudjonsson Suggestibility Scale and instruments measuring intellectual skills, memory, field-dependence, hostility, and attitudes towards persons in authority. Suggestibility correlated negatively with I.Q. and memory capacity, and positively with field-dependence.

Adolescent↗
PubMed1992

Genetic nature of vitiligo.

Four hundred vitiligo patients and 100 non-vitiliginous controls were studied to find out the prevalence of vitiligo in relatives of patients and controls. The difference was found to be statistically highly significant. The data reflected that there is some genetic mechanism involved in the etiology of vitiligo. Respective relatives of all forms of the disease in the vitiligo group showed a clear preponderance compared to controls. There was clustering of affected relatives in vitiligo cases compared to controls. The ratio of affected and unaffected siblings with unaffected parents or one parent affected, the ratio in the children of probands, the ratio in children of affected paternal and maternal grandparents of probands, suggest the polygenic nature of vitiligo.

Adult↗
PubMed1992

Alternative topogenic signals in peroxisomal citrate synthase of Saccharomyces cerevisiae.

The tripeptide serine-lysine-leucine (SKL) occurs at the carboxyl terminus of many peroxisomal proteins and serves as a peroxisomal targeting signal. Saccharomyces cerevisiae has two isozymes of citrate synthase. The peroxisomal form, encoded by CIT2, terminates in SKL, while the mitochondrial form, encoded by CIT1, begins with an amino-terminal mitochondrial signal sequence and ends in SKN. We analyzed the importance of SKL as a topogenic signal for citrate synthase, using oleate to induce peroxisomes and density gradients to fractionate organelles. Our experiments revealed that SKL was necessary for directing citrate synthase to peroxisomes. C-terminal SKL was also sufficient to target a leaderless version of mitochondrial citrate synthase to peroxisomes. Deleting this tripeptide from the CIT2 protein caused peroxisomal citrate synthase to be missorted to mitochondria. These experiments suggest that the CIT2 protein contains a cryptic mitochondrial targeting signal.

Amino Acid Sequence↗
PubMed1991

Mitochondrial protein import: isolation and characterization of the Saccharomyces cerevisiae MFT1 gene.

Mitochondrial targeting of an Atp2-LacZ fusion protein confers a respiration-defective phenotype on yeast cells. This effect has been utilized to select strains that grow on nonfermentable carbon sources, some of which have decreased levels of hybrid protein localized to the organelle. Many of the mutants obtained were also temperature-sensitive for growth on all media. The recessive mft (mitochondrial fusion targeting) mutants have been assigned to three complementation groups. MFT1 was cloned and sequenced: it encodes a 255 amino acid protein that is highly basic and has no predicted membrane-spanning domains or organelle-targeting sequences. The MFT1 gene is 91% identical to an open reading frame 3' of the SIR3 gene. Evidence is presented that these two closely related genes could represent a recent gene duplication.

Amino Acid Sequence↗
PubMed1991

Metabolic changes induced during adaptation of Saccharomyces cerevisiae to a water stress.

When exponentially growing Saccharomyces cerevisiae was transferred from a normal high water activity growth medium (aw 0.997) to a medium containing 8% NaCl low water activity growth medium (aw 0.955), glycerol accumulation during the first eight hours of the adaptation was both retarded and greatly diminished in magnitude. Investigation of the underlying reasons for the slow onset of glycerol accumulation revealed that not only was overall glycerol production reduced by salt transfer, but also the rates of ethanol production and glucose consumption were reduced. Measurement of glycolytic intermediates revealed an accumulation of glucose-6-phosphate, fructose-6-phosphate, fructose 1,6 bisphosphate and phosphoenolpyruvate in S. cerevisiae 3 to 4 h after transfer to salt, suggesting that one or more glycolytic enzymes were inhibited. Potassium ions accumulated in S. cerevisiae after salt transfer and reached a maximum about 6 h after transfer, whereas the sodium ion content increased progressively during the adaptation period. The trehalose content also increased in adapting cells. It is suggested that inhibition of glycerol production during the initial period of adaptation could be due to either the inhibition of glycerol-3-phosphate dehydrogenase by increased cation content or the inhibition of glycolysis, glycerol being produced glycolytically in S. cerevisiae. The increased accumulation of glycerol towards the end of the 8-h period suggests that the osmoregulatory response of S. cerevisiae involves complex sets of adjustments in which inhibition of glycerol-3-phosphate dehydrogenase must be relieved before glycerol functions as a major osmoregulator.

Culture Media↗
PubMed1991

Does breastfeeding influence mortality in children hospitalized with diarrhoea?

The association between breastfeeding and mortality in children hospitalized for diarrhoea was investigated in a prospective manner in 309 subjects below 18 months of age. In multivariate logistic regression analysis, 36 cases who died were compared with 273 controls who were discharged in a satisfactory condition. Breastfeeding had a strong protective effect against mortality even after allowance was made for confounding variables (including nutritional status, chronicity of illness, associated non-enteral infections) and a possible bias of interruption of breastfeeding as an early consequence of the terminal illness. The adjusted odd's ratio (OR) and 95 per cent confidence intervals (95 per cent CI) for the protective effect were 2.7 and 2.1-3.6, respectively. The adjusted OR's (95 per cent CI's) were 6.0 (3.6-10.2), 2.6 (2.0-3.4), and 1.8 (1.4-2.5) for the age intervals 0-6, 7-12, and 13-18 months, respectively (P less than 0.001, less than 0.01, and less than 0.05, respectively). Further stratified analyses suggested a greater benefit in children with severe wasting, severe stunting, protracted illness, and diarrhoea as the sole illness. It is concluded that in children up to 18 months of age, breastfeeding offers substantial protection against death in children hospitalized with diarrhoea.

Breast Feeding↗
PubMed1991

Risk factors for fatal diarrhea in hospitalized children in India.

There is scant information on the risk factors for diarrheal deaths in developing countries. A prospective evaluation was therefore conducted on 382 consecutive children (less than 5 years of age), who were hospitalized with diarrhea. A complete profile, including outcome, was available for 357 patients, 37 of whom died (10.4%). In the univariate analysis, four factors were significantly associated (p less than 0.02) with death: associated major infection (pneumonia, septicemia, or meningitis), severe wasting (less than or equal to 50% weight for age), severe stunting (less than or equal to 85% height for age), and protraction of illness (greater than 14 days). In the multivariate analysis, all four factors retained their significance. The adjusted odds ratios (95% confidence interval) were 4.7 (3.9, 5.6), 3.3 (2.7, 4.0), 1.9 (1.6, 2.3), and 1.5 (1.3, 1.8), respectively. In addition, in children less than 19 months of age (n = 241; 29 deaths) breast-feeding had a significant (p less than 0.001) protective effect (adjusted OR--2.3, 95% CI-1.9-2.8). It is concluded that even in a setting with high diarrheal fatality rates, high-risk children can be identified and targeted for intensive intervention.

Body Height↗
PubMed1990

Immunosuppression due to chronic ochratoxicosis in broiler chicks.

Crystalline ochratoxin A (OA) was added to the feed of broiler chicks at 0.5 ppm and 2.0 ppm, and humoral and cell-mediated immunity (CMI) were studied. CMI was assessed by skin sensitivity testing, graft versus host (GVH) reaction and T lymphocyte count. Humoral immunity was examined by measuring the haemagglutinin (HA) response to sheep RBC (SRBC). In addition, total lymphocyte counts, total serum protein, albumin and globulin were determined and the phagocytic activity of splenic macrophages was measured in the nitroblue tetrazolium test (NBT). The weights of lymphoid organs were also recorded at post-mortem examination of the birds. Highly significant reductions in CMI were indicated by diminished skin sensitivity, GVH reactions and T lymphocyte counts. On the other hand, only the overall HA titres differed significantly between the various treatment groups. Total lymphocyte counts, total serum protein, serum albumin and serum globulin were significantly depressed on the 21st day of intoxication. The number of NBT-positive cells was drastically reduced in both the intoxicated groups compared with controls (P less than 0.05) and the weights of thymus, bursa of Fabricius and spleen of intoxicated birds were significantly reduced. The study illustrated the immunosuppressive effects of ochratoxicosis in broiler chicks.

Animals↗
PubMed1990

In vivo and in vitro measurement of cell mediated immunity in Marek's disease: role of reticuloendothelial system.

Dinitrofluorobenzene (DNFB) contact-sensitivity test and leucocyte adherence inhibition (LAI) test were performed in this study as in vivo and in vitro tests to measure the cell-mediated immunity (CMI) in chickens subjected to stimulation of reticuloendothelial (RE) system, depletion of RE system and other experimental groups after being challenged with Marek's disease (MD) virus. It was found that CMI was lower in the birds with depleted RE system and infected control birds, whereas CMI was higher in the birds with activated RE system and vaccinated birds as revealed by DNFB contact-sensitivity test. In cases of LAI test, the number of LAI-positive birds were highest in the chicks with depleted RE system particularly in 3rd and 4th month of age, when the incidence of MD was also maximum.

Animals↗
PubMed1989

The role of the reticuloendothelial system in the immunopathology of Marek's disease.

The role of macrophages in immunity against Marek's disease (MD) was studied. Chickens of one group were subjected to depletion of macrophages using repeated doses of Francil amorphous silica and those of another group were subjected to activation of macrophages using repeated doses of brewer's thioglycollate broth. Chickens of a third group were vaccinated with herpesvirus of turkeys FC 126 vaccine followed by depletion of macrophages. Chickens of these three groups, as well as groups of healthy unvaccinated and healthy vaccinated chickens, were challenged with virulent MD virus. A sixth group of healthy uninfected chickens was kept as a control. The results, based on clinical signs, gross and histopathological studies and agar gel precipitation test (AGPT) for antibodies, indicated that activation of macrophages enhanced immunity against MD and depletion of macrophages had the opposite effect. The protective effect of vaccination against MD was also lowered by depletion of macrophages. The results of AGPT indicated retardation of MD virus replication by macrophage activation and the reverse on depletion.

Animals↗
PubMed1989

Short-term parenteral nutrition with glucose and Intralipid: effects on serum lipids and lipoproteins.

We prospectively investigated the effect of a 3-wk course of parenteral nutrition with 20% glucose, 4.25% amino acids, and 10% Intralipid on plasma lipids and lipoproteins in a cohort of 12 nutritionally replete patients with inflammatory bowel disease. Mean total serum cholesterol and mean total serum phospholipids increased in parallel throughout the study; density gradient ultracentrifugation demonstrated these increases were due to the appearance of lipoprotein-X. The mean low-density lipoprotein (LDL) mass on the density gradients decreased during the study and high-density lipoprotein (HDL) cholesterol levels decreased by 28% by the end of the third week. Plasma free fatty acids decreased by 42%. These results demonstrate that the glucose and 10% Intralipid regimen caused modest decreases in serum HDL cholesterol and LDL mass and the prompt appearance of lipoprotein-X with attendant hypercholesterolemia and hyperphospholipidemia. Patients undergoing long-term treatment with glucose and Intralipid should be closely monitored for the occurrence of significant dyslipoproteinemia.

Adult↗
PubMed1988

Water stress plating hypersensitivity of yeasts: protective role of trehalose in Saccharomyces cerevisiae.

Water stress plating hypersensitivity was studied in two strains of Saccharomyces cerevisiae, one of them being a mutant incapable of accumulating trehalose to significant levels. The wild-type strain was grown in a defined medium with glucose, maltose or ethanol as carbon/energy source. In each case plating hypersensitivity was demonstrated and resistance to the stress developed in the second half of the exponential growth phase. Development of resistance was accompanied by accumulation of trehalose and was apparently unrelated to glycerol content which, under these conditions, was always low. A qualitatively similar trend was observed in the mutant grown on glucose but trehalose levels remained low and recovery of stress resistance was only slight. Dinitrophenol induced trehalose breakdown in resting yeast and simultaneously induced the onset of plating hypersensitivity. A negative correlation was demonstrated between trehalose content and 'plating discrepancy' (log colony count on 'normal' agar-log colony count on stressing agar) for both strains under all experimental conditions. The correlation held for trehalose contents up to about 50 mg (g dry yeast)-1, above which the yeasts were apparently fully resistant. Trehalose was evidently a more effective compatible solute, per mole, than glycerol.

Colony Count, Microbial↗