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Biomedical subjects

A Singh

Publications and source records attributed to A Singh.

At least 865 records · Page 48Linked to original sources
PubMed1976

Masked abnormal drainage of the inferior vena cava into the left atrium.

A 6 year old boy with a large atrial septal defect, partial anomalous pulmonary venous drainage and unrecognized anomalous insertion of the inferior vena cava into the left atrium had cyanosis after closure of the atrial defect. Repeat study revealed direct drainage of the inferior vena cava into the left atrium with moderate arterial oxygen desaturation. At repeat operation an unusual positioning of the inferior vena cava was seen. After reopening of the atrial defect, the pulmonary venous and systemic venous drainage anomalies were identified. A Dacron patch was inserted so as to divert flow to the proper atrium. Repeat catheterization 3 months after operation revealed a normal heart with no obstruction; arterial oxygen saturation was normal. The child has continued to do well 3 years after operation.

Blood Vessel Prosthesis↗
PubMed1976

Serum lipid profiles in patients of myocardial infarction in the Chandigarh area (Northern India).

To study the incidence of hyperlipoproteinaemia in patients with myocardial infarction (MI) in the Chandigarh area, estimations of various lipids have been carried out in 83 patients. A serial study has been carried out in 31 patients. Serum lipoproteins and uric acid were also estimated. Results show an incidence of only 18% hypercholesterolaemia in patients with MI and 15% in normal subjects. Age-wise distribution of hypercholesterolaemia was slightly higher in 41-60 years old patients when compared with other age groups. No other abnormality in lipid profile was observed. Hyperuricaemia was not observed. These results, therefore, differ markedly from those of similar studies published from the western world.

Adult↗
PubMed1976

Melanotic neuroectodermal tumour of infancy: report of a case.

A case of melanotic neuroectodermal tumour occurring in a seven-month-old male infant is reported. The aetiopathogenesis, clinical features, treatment and prognosis of the condition are discussed. Tumours of the jaw in infancy are extremely rare, and pigmented tumours still rarer. One such case of pigmented tumour of the maxilla is the subject of this report.

Humans↗
PubMed1976

Resistance of Salmonella serotypes to chloramphenicol.

A total of 704 Salmonella strains isolated from various sources were tested for their resistance to chloramphenicol. The results indicate that 36 out of 46 serotypes, comprising 671 strains (95.4%), were sensitive to chloramphenicol up to a level of 10 mug per ml of medium. Most of the strains were sensitive at concentrations between 2 mug and 4 mug of chloramphenicol per ml of medium. None of the strains isolated from animals, including poultry, was resistant. The results indicate that in India resistance of Salmonella strains to chloramphenicol has not increased over the years though this may have occurred in other parts of the world.

Animals↗
PubMed1976

Hemolysis following correction of double-outlet right ventricle.

A 41/2-year-old child developed a severe degree of intravascular hemolysis within 24 hours after intraventricular correction of double-outlet right ventricle with a Dacron patch. The child developed jaundice, with a serum bilirubin of 4.3 mg. per cent. The hematocrit value fell from 47 to 25 per cent and the reticulocyte count rose to 22 per cent. The hemolysis diminished after 3 weeks and completely disappeared after 6 weeks. We presume that the hemolysis was due to turbulence caused by a long, curved patch and that its disappearance coincided with the endothelialization of the patch. The child is well 3 years after the operation.

Anemia, Hemolytic↗
PubMed1976

Effect of cholera enterotoxin preparations on cutaneous response in rabbit under varied conditions.

Enterotoxic activity of two preparations obtained from Vibrio cholerae, B-53-6 Inaba and B-53-10 Ogawa was tested in ligated ileal loops of rabbit. The biologically active enterotoxic preparations were further used to study the permeability reaction in rabbit skin. Cutaneous response tended to be linear only with higher concentrations of the toxin and showed maximum blueing intensity between 16 and 24 hrs of intracutaneous inoculation. Exposure of enterotoxin preparations to elevated temperatures greatly reduced the cutaneous response and the activity was completely lost at 100 degrees C. Change in pH towards alkaline side lowered the permeability activity to lesser extent as compared to a shift on acidic side. However, a residual activity could still be detected when pH of the enterotoxins was lowered to 3 at 30 degrees C for 4 hrs.

Animals↗
PubMed1975

Colchicine administration to mice: a metabolic and ultrastructural study.

A single injection of colchicine has been administered to normal albino mice, and the metabolic effects as well as the hepatic ultrastructural changes resulting from this treatment have been studied at various time intervals. A marked decrease in circulating triglyceride levels was evident 4 hours after colchicine injection and was maximum after 11 hours. It coincided with a marked increase in hepatic triglyceride content. Twenty hours after colchicine administration, plasma triglyceride levels and hepatic triglyceride content had returned to normal values. Similar changes in the levels of circulating proteins were observed although their magnitude was less than that observed for triglycerides. Ultrastructurally, colchicine treatment resulted in the virtual disappearance of the microtubules from the hepatocytes, and in the appearance of many clusters of vesicles containing very low density lipoprotein-like particles which eventually transformed into lipid droplets. These ultrastructural alterations were also completely reversible, the reversibility coinciding with the morphological reappearance of microtubules. Finally, colchicine treatment resulted in marked metabolic changes that are interpreted as representing an attempt, by the organism, to keep adequate energy sources during the period of lack of circulating triglycerides.

Amino Acids↗
PubMed1975

Familial hyperlipoproteinemia and gallstones.

Of 108 patients with familial hyperlipoproteinemia between the ages of 22 and 85 years (mean, 55.1 years) 46 (42.6%) had cholelithiasis. Among the 53 patients with type II hyperlipoproteinemia 20 (38%) had gallstones; the male:female ratio was 1:2; the mean serum triglyceride value was significantly higher in those with gallstones. Among the 50 patients with type IV hyperlipoproteinemia 25 (50%) had gallstones; the male:female ratio was 1:1; the mean age was significantly higher in those with gallstones. Among the five patients with type V hyperlipoproteinemia one had gallstones. Electrocardiographic evidence of myocardial damage was present in 47 (44%) of the 108 patients; 18 (39%) of the 46 patients with gallstones showed such abnormalities, while 26 (24%) showed sinus bradycardia.

Adult↗
PubMed1975

Defective membrane systems in dystrophic skeletal muscle of the UM-X7.1 strain of genetically myopathic hamster.

1. The function of mitochondria, sarcotubular membranes (heavy microsomes), sarcolemma and myofibrils from the hind-leg skeletal muscle of about 60- and 150-day-old normal and myopathic (UM-X7.1) hamsters was examined. 2. The mitochondrial calcium uptake as well as mitochondrial phosphorylation and respiratory rates were lower in 60-day-old myopathic skeletal muscle, unlike 150-day-old myopathic animals, when pyruvate-malate and glutamate-malate were used as substrates. However, mitochondria from 150-day-old myopathic animals showed depressed glutamate-dependent respiratory and phosphorylation rates and succinate-supported initial rate of calcium uptake. 3. The microsomal calcium-uptake, but not calcium-binding, and Ca2+-stimulated adenosine triphosphatase (ATPase) activity of the 150-day-old myopathic skeletal muscle were lower than the control values. Although microsomal calcium-binding, calcium-uptake and ATPase activities of the 60-day-old myopathic muscle were not depressed significantly, the initial rate of calcium uptake was less than the control. 4. The sarcolemmal Ca2+-ATPase, but not Mg2+-ATPase or Na+ +K+-ATPase, activity was higher in 60-day-old myopathic muscle whereas the activities of all these enzymes from 150-day-old myopathic animals were higher than the control. On the other hand, the Na+ +K+-ATPase activities from 60- and 150-day-old myopathic animals were inhibited by ouabain to a lesser extent in comparison with the respective control values. 5. The myofibrillar Ca2+-ATPase and Mg2+-ATPase activities as well as inhibition of Mg2+-ATPase due to Na+ and K+ in myopathic muscle were no different from the control values. 6. The results reported here give further support to the view that different membrane systems of the dystrophic muscle are defective.

Adenosine Triphosphatases↗
PubMed1975

Colchicine-binding protein of the liver. Its characterization and relation to microtubules.

Colchicine-binding activity of mouse liver high-speed supernate has been investigated. It has been found to be time and temperature dependent. Two binding activities with different affinities for colchicine seem to be present in this high-speed supernate, of which only the high-affinity binding site (half maximal binding at 5 x 10(-6) M colchicine) can be attributed to microtubular protein by comparison with purified tubulin. Vinblastine interacted with this binding activity by precipitating it when used at high concentrations (2 x 10(-3) M), and by stabilizing it at low concentrations (10(-5) M). Lumicolchicine was found not to compete with colchicine. The colchicine-binding activity was purified from liver and compared with that of microtubular protein from brain. The specific binding activity of the resulting preparation, its electrophoretic behavior, and the electron microscope appearance of the paracrystals obtained upon its precipitation with vinblastine permitted its identification as microtubular protein (tubulin). Electrophoretic analysis of the proteins from liver supernate that were precipitated by vinblastine indicated that this drug was not specific for liver tubulin. Preincubation of liver supernate with 5 mM EGTA resulted in a time-dependent decrease of colchicine-binding activity, which was partly reversed by the addition of Ca++. However, an in vitro formation of microtubules upon lowering the Ca++ concentration could not be detected. Finally, a method was developed enabling that portion of microtubular protein which was present as free tubulin to be measured and to be compared with the total amount of this protein in the tissue. This procedure permitted demonstration of the fact that, under normal conditions, only about 40% of the tubulin of the liver was assemled as microtubules. It is suggested that, in the liver, rapid polymerization and depolymerization of microtubules occur and may be an important facet of the functional role of the microtubular system.

Animals↗
PubMed1975

Genetic and physiological characterization of met15 mutants of Saccharomyces cerevisiae: a selective system for forward and reverse mutations.

One hundred and thirty-three spontaneous and induced mutants of the met15 locus in Saccharomyces cerevisiae were characterized with respect to temperature sensitivity, osmotic remediability, interallelic complementation, and suppressibility by amber and ochre suppressors. Forty mutants are osmotic remedial; 17 of these, and no others, are also temperature-sensitive. Seven of 133 mutations are suppressible by an amber suppressor and 11 are suppressible by an ochre suppressor. Seventy percent of the mutants exhibited interallelic complementation, suggesting that the functional gene product of the met15 gene is a multimeric protein. Relative map positions of 30 met15 were estimated from the frequencies of X-ray-induced mitotic reversion of various heteroallelic diploids. All complementing nonsense mutations are located near one end of the gene in contrast to other nonsense mutations which span most of the gene, thus relating the direction of translation of the mRNA with respect to the fine-structure map. Recombination studies indicated that two of 30 mutants contained deletions of the entire met15 locus. -- It was established that a variety of mutational types, including missense, nonsense, and deletions, are recovered with this unique system in which both forward and reverse mutations can be selected on the basis of methyl mercury resistance and methionine requirement of the met15 mutants.

Alleles↗