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Biomedical subjects

A Sen

Publications and source records attributed to A Sen.

At least 199 records · Page 11Linked to original sources
PubMed1984

The effect of calcium on the bilayer stability of lipids from bovine rod outer segment disk membranes.

The phase behavior of bovine rod outer segment disk lipids has been investigated using freeze-fracture and 31P nuclear magnetic resonance (NMR) techniques. 31P-NMR spectra of isolated disk membranes were taken as a function of temperature between 25 degrees C and 45 degrees C. The 31P-NMR spectrum characteristic of phospholipid bilayers was observed at all temperatures both in the absence of Ca2+ and in the presence of 10 mM and 50 mM Ca2+. A similar study was performed on lipids isolated from the disk membranes. In the absence of Ca2+ only lamellar phase behavior was observed. In the presence of less than 10 mM Ca2+, however, there was a change in morphology to non-lamellar structures. Removal of the Ca2+ caused the system to reassume the lamellar form.

Animals↗
PubMed1984

In search of a super solution: controlled trial of glycine-glucose oral rehydration solution in infantile diarrhoea.

In a double blind trial a glycine fortified oral glucose electrolyte solution was evaluated in a group of infants and small children (n=25) with moderate to severe dehydration due to acute diarrhoea, and was compared with a matched control group (n=26) receiving only glucose based oral rehydration solution. It is seen that the diarrhoea stool output, duration of diarrhoea, and volume of oral rehydration fluid required to achieve and maintain hydration are significantly lower in the group receiving glycine fortified glucose electrolyte solution. The possibility of developing an oral rehydration solution which could also act as an absorption promoting drug is discussed.

Administration, Oral↗
PubMed1984

Nucleotide sequence of the transforming gene of m1 murine sarcoma virus.

The v-mosm1 nucleotide sequence codes for a protein that is 376 amino acids long. Although the N-terminus is homologous with that of the v-mos124 protein, the C-terminus is substantially different from the C-termini of all other examined mos proteins, suggesting that this region is nonessential and perhaps cleaved. Overall, v-mosm1 has greater homology with c-mos than does v-mos124, but mutually exclusive differences between c-mos and each of the v-mos genes preclude linear descent and suggest a common ancestral murine sarcoma virus.

Amino Acid Sequence↗
PubMed1984

Accumulation of unesterified arachidonic acid in ischemic canine myocardium. Relationship to a phosphatidylcholine deacylation-reacylation cycle and the depletion of membrane phospholipids.

Studies in ischemic canine left ventricle have shown that the depletion of membrane phospholipids is a critical event in the development of a sarcolemmal calcium permeability defect and associated irreversible myocyte injury. The mechanism of phospholipid loss is unclear, but may be due to the activation of endogenous phospholipases. Since arachidonic acid is a fatty acid found almost entirely in phospholipid, increases in arachidonate provide evidence for increased phospholipase activity. The present study was designed to examine the temporal relationship of the accumulation of free arachidonate with the onset of phospholipid depletion during fixed ligation of the left anterior descending coronary artery in canine myocardium. The following results were demonstrated in ischemic canine myocardium: (1) the accumulation of unesterified arachidonate is minimal during 10-30 minutes of ischemia, but is significantly increased after prolonging the duration of ischemia to 1-3 hours; (2) significant increases in arachidonate precede the development of a significant decrease in total phospholipid content; (3) the decrease in the arachidonate content of phosphatidylcholine is accompanied by similar decreases in all of the fatty acyl moieties; (4) the arachidonate content of lysophosphatidylcholine and diacylglycerol are unchanged during myocardial ischemia; (5) there is evidence of a deacylation-reacylation cycle in phosphatidylcholine prior to the accumulation of free arachidonate; (6) the fatty acyl specificity of the lysophosphatidylcholine acyltransferase corresponds to the pattern of fatty acyl remodeling of phosphatidylcholine during early myocardial ischemia. These data suggest that the accumulation of arachidonate may be a more sensitive measure of phospholipid degradation than the decrease in total phospholipid content in ischemic canine myocardium. It is postulated that the defective reacylation of arachidonate into phosphatidylcholine may contribute to the net loss of membrane phospholipid during myocardial ischemia.

1-Acylglycerophosphocholine O-Acyltransferase↗
PubMed1984

Packing pattern of DNA in bacteriophage T2.

Osmotic shock was applied to phage T2 in such a manner that the compact-mass of DNA was released from phage. The shape of this compact-mass of DNA was studied under electron microscope. It appeared that the DNA was packed into an elongated icosahedron similar to the phage head.

DNA, Viral↗
PubMed1983

Fatty acylcarnitine accumulation and membrane injury in ischemic canine myocardium.

Although previous work has shown that long chain fatty acylcarnitine derivatives accumulate in ischemic canine myocardium, their role in the production of irreversible injury and associated sarcolemmal membrane injury is undefined. The present study examines the temporal and topographic relationship of the accumulation of long chain acylcarnitine with the uptake of technetium pyrophosphate and tissue calcium content during ligation of the left anterior descending coronary artery (LAD) in canine myocardium. After 60 minutes of fixed LAD ligation, there was no significant increase in long chain acylcarnitine content in the ischemic subendocardium compared with the corresponding nonischemic value. However, the ischemic subendocardium was irreversibly injured at this time, as assessed by a 4-fold increase in tissue calcium content and a 20-fold increase in technetium-99m pyrophosphate uptake after reperfusion. The ischemic subepicardium showed a 41% increase in long chain acylcarnitine content compared with the corresponding nonischemic subepicardium. However, the ischemic subepicardium contained only 50% of the calcium content and 10% of the technetium-99m pyrophosphate uptake found in the ischemic subendocardium. It is concluded that increases in fatty acylcarnitine can be dissociated from the development of irreversible ischemic injury during fixed LAD occlusion in ischemic canine myocardium.

Animals↗
PubMed1983

Difference between tortoise and hen lysozymes in the mode of association with N-acetyl D-glucosamine as revealed by proton magnetic resonance spectroscopy.

Tortoise lysozyme, unlike hen lysozyme, does not distinguish between the alpha- and beta-anomeric forms of N-acetyl D-glucosamine. This indicates that alpha- and beta-anomeric forms of the inhibitor have the same affinities and experience identical magnetic environments in tortoise lysozyme. The dissociation constant of tortoise lysozyme-inhibitor complex was calculated from chemical shift data and found to be 3.5 X 10(-2) M. The enthalpy of dissociation was calculated to be 5.0 kcal/mol.

Acetylglucosamine↗
PubMed1983

Estimation of domain length of chicken erythrocyte chromatin.

Chromatin of chicken erythrocyte nuclei was extracted by digestion with micrococcal nuclease. The length distribution of the soluble chromatin was determined by gel electrophoresis and electron microscopy. These results were fitted with a theoretical distribution which was an outcome of the domain model proposed by Igo-Kemenes and Zachau (Igo-Kemenes, T. and H.G. Zachau (1977) Cold Spring Harbour Symp. Quant. Biol. 42, 109-118). A domain length of 45 kbp was obtained.

Animals↗
PubMed1983

Correlation between reaction time and intelligence in psychometrically similar groups in America and India.

The relationship between psychometrically tested reasoning ability, or general intelligence (Raven's Progressive Matrices), short-term memory (forward and backward digit span), and measures of reaction time (RT), including visual and auditory simple RT and four degrees of choice RT, was investigated in groups of unskilled workers, mostly of below average, borderline, or retarded mental ability, selected in the United States and in India. Both groups showed parallel phenomena with respect to the relative difficulty of the various RT tests, their factor structure, and their theoretically expected correlations with psychometric intelligence, although the correlations were lower (and generally nonsignificant) in the Indian group, most likely because of this group's greater restriction in range of ability. The findings, overall, are consistent with other recent studies of RT and intelligence, which indicate that our standard IQ tests reflect basic cognitive processes, particularly speed of information processing, involved in individual differences in intellectual ability, and not merely differences in specific acquired knowledge, skills, or cultural background.

Adolescent↗
PubMed1983

Antibodies of predetermined specificity detect two retroviral oncogene products and inhibit their kinase activities.

Oligopeptides predicted from the nucleotide sequence of the oncogene v-fes of feline sarcoma virus (FeSV) were synthesized chemically and used to generate specific antibodies. Antisera against a 12-amino-acid-long oligopeptide (12-mer) located 42 residues from the carboxyl terminus of the v-fes coding sequence efficiently recognized the transforming proteins encoded by Snyder-Theilen (ST) and Gardner-Arnstein (GA) strains of FeSV. This 12-mer also contains 10 amino acid residues homologous in order and position to those predicted from the nucleotide sequence of the oncogene v-fps of avian Fujinami sarcoma virus (FSV). The anti-12-mer immunoprecipitated the FSV-specific transforming protein molecules from FSV-transformed cells. Binding of these antipeptide antibody molecules to the v-fes and the v-fps gene products inhibited their associated tyrosine-specific protein kinase (EC 2.7.1.37) activities. The ability to generate such site-specific antisera to the products of related oncogenes will be valuable in the molecular characterization of retroviral transforming proteins and their normal cellular homologs.

Antibody Specificity↗
PubMed1982

DNA methylation in mouse cells in culture as measured by restriction enzymes.

Methylation of DNA in normal mouse cultured 3T3 cells and in their virally or chemically transformed derivatives was studied. DNA methylation was studied by restriction with HpaII, MspI, or HpaII plus MspI. DNA from the chemically transformed cells was cleaved about twice as often with HpaII than was the DNA of normal and virally transformed cells. Digests with MspI and HpaII plus MspI were identical in all cell lines studied. Densitometry of the restriction patterns allowed an estimate of total DNA methylation from the weight average lengths. The chemically transformed cell line showed 25% reduction in methylation compared to the other cell lines. Southern blot hybridization using satellite DNA showed that these sequences followed a pattern of modification similar to that of total DNA.

Animals↗
PubMed1982

Formation of inverted lipid micelles in aqueous dispersions of mixed sn-3-galactosyldiacylglycerols induced by heat and ethylene glycol.

The formation of 'lipidic' particles corresponding to inverted lipid micelles in freeze-fracture replicas of aqueous dispersions of mono- and digalactosyldiacylglycerols can be greatly enhanced either by increasing the temperature from which the samples are thermally quenched or by the addition of cryoprotectants such as ethylene glycol. In the case of the heated samples, the lipids tend to form quasi-crystalline structures consisting of sheets of 8-9 nm diameter particles organised on an orthorhombic lattice. The orientation of alternate sheets varies giving rise to a characteristic herring-bone pattern. Ethylene glycol-treated samples, in contrast, form more regular structures consisting of 13-16 nm diameter particles. Lowering the temperature from which the samples are quenched and/or decreasing the concentration of ethylene glycol reduces the frequency of formation of such structures. A number of intermediate states associated with the reincorporation of the lipid molecules of the inverted micelles into the lamella phase are also identified. The factors influencing particle formation are briefly discussed. It is concluded that the destabilisation of lipid-water interactions play a major role in this process.

Colloids↗