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Biomedical subjects

N Srivastava

Publications and source records attributed to N Srivastava.

At least 91 records · Page 5Linked to original sources
PubMed1992

Expression of low density lipoprotein receptor, apolipoprotein AI, AII and AIV in various rat organs utilizing an efficient and rapid method for RNA isolation.

Intact RNA from various rat organs was isolated by an efficient and rapid method. This method of RNA isolation is a modification of an earlier method that uses guanidinium isothiocynate followed by extraction in the presence of sarcosyl, acetate and phenol. The RNA obtained by the method reported here was comparable with the RNA prepared by the CsCl2 ultracentrifugation method and the commercially available kit based on published methods. The quality of RNA was found suitable for Northern blotting analysis, RNase protection assays and reverse transcriptase-polymerase chain reaction (RT-PCR). Since reverse transcriptase is active in the buffer used for Taq DNA polymerase, only one reaction needs to be set up. We also found that the use of aurintricarboxylic acid in the RNA preparation prevents the degradation of RNA during storage. Expression of low density lipoprotein (LDL) receptor, apolipoprotein (apo) AI, AII and AIV mRNAs were quantified in various rat organs. Our results indicated that rat LDL receptor mRNA is expressed in several organs whereas apoAI and AIV mRNAs were expressed mainly in the liver and intestine. However, apo AII mRNA is expressed mainly in the liver. Unlike mice and some species of monkeys, in the rat apoAI mRNA is expressed at 5-6 times higher levels in the intestine compared to liver. Apo AIV mRNA abundance was also found to be several fold higher in intestine compared to hepatic tissues. We present here, for the first time, data on the absolute amounts of LDL receptor, apoAI, AII and AIV mRNA in various rat organs which were quantified by a novel RNase protection/solution hybridization assay.

Animals↗
PubMed1991

Phosphoinositides of sheep platelets plasma membranes.

Phospholipid composition of sheep blood platelets and its various plasma membrane fractions have been analyzed. Based on their flotation rates in discontinuous sucrose density gradient centrifugation, three membrane fractions were isolated. 5'-Nucelotidase and alkaline phosphatase were distributed nearly equally in all the three membrane fractions. However these membrane fractions showed differences in the distribution of phosphatidyl ethanolamine, phosphatidyl choline and phosphoinositides. Phosphatidyl ethanolamine was predominant in fraction I (11.05 micrograms PLP/mg protein) while phosphatidyl choline was predominant in fractions II and III (110.10 and 68.30 micrograms PLP/mg protein respectively). Phosphatidyl inositol (Ptd-InsP) was equally distributed in all three membrane fractions. However, both Ptd-InsP and phosphatidyl inositol 4,5-bisphosphate were about 4-fold higher in fraction II (73.55 and 89.89 micrograms PLP/mg protein respectively).

Animals↗
PubMed1991

RNA processing enzymes RNase III, E and P in Escherichia coli are not ribosomal enzymes.

We recently showed that RNase III can process a small stable RNA, precursor 10Sa RNA, that accumulates in an rne (RNase E) strain at non-permissive temperatures. Precursor 10Sa (p10Sa) RNA is processed to 10Sa RNA in two steps, the first step is catalyzed by RNase III in the presence of Mn2+ but not Mg2+. It was shown that RNase III cosediments with membrane preparation from wild type as well as RNase III overexpressing cells. However, the possibility of membrane preparation contamination with ribosomes could not be ruled out. Here we show that RNase III, E and P are not associated with ribosomes. E. coli cells were opened either by alumina grinding or by sonication and fractionated into cytosolic and pellet fractions. The characterization of membrane preparations was done by assaying NADH oxidase, a bona fide membrane enzyme. Ribosomes prepared by alumina grinding were found to be contaminated with small fragments of membrane which contained RNase III activity. RNase III and NADH oxidase activities were present in the ribosomal preparations which could be solubilized by reagents that dissolve the inner membrane. Isopycnic sucrose gradient centrifugation of the membrane and ribosomal preparations also confirmed that RNase III fractionated with the inner membrane. Similarly RNase P activity was found in the corresponding fractions when isopycnic centrifugation of membrane and ribosome preparations was carried out. RNase E activity was also found to be present mostly in the post-ribosomal supernatant. These findings show that RNase III, E and P are not ribosomal enzymes.

Cell Membrane↗
PubMed1991

Role of oesophageal electrocardiograms in differentiation of old anteroseptal myocardial infarction from emphysema in cases with poor R wave progression in precordial leads.

R wave height, S wave depth and the R/S ratio on electrocardiograms obtained with unipolar oesophageal lead recorded at various levels were studied in 54 cases with emphysema without myocardial infarction and 46 cases with healeeed anteroseptal myocardial infarction. All patients had poor R wave progression in anterior precordial leads. The criterion of R wave height of greater than or equal to 7.5 mm at the ventricular level oesophageal electrocardiogram was most sensitive (85.7%), specific (80%) and accurate (82.4%) for the diagnosis of healed anteroseptal myocardial infarction.

Electrocardiography↗
PubMed1990

Interaction of ethanol, cholesterol and vitamin A on phospholipid methylation in hepatic microsomes of rats.

Effect of ethanol, cholesterol and vitamin A either alone or in combination has been studied on cyt P450 and phospholipid methylation in hepatic microsomes of rats. Ethanol increased cyt P450 activity and decreased phospholipid methylation. Cholesterol effects were opposite to ethanol. Combination of cholesterol and ethanol decreased cyt P450 activity and increased phospholipid methylation. Vitamin A, which alone did not affect cyt P450 activity and phospholipid methylation behaved like cholesterol when given along with ethanol.

Animals↗
PubMed1987

Effects of distillery waste on the performance of Cicer arietinum L.

The impact of distillery effluent in various concentrations (1, 2.5, 5, 10, 25, 50, 75 and 100%) on the seed germination, Speed of Germination Index, growth behaviour, leaf area, biomass, net primary productivity, pigment content, reproductive capacity, seed output, seed weight, seed density and the seed protein content of Cicer arietinum L. plants was investigated. The percentage and speed of germination of seeds were increasingly retarded with increase in effluent concentration and at 100% concentration there was no germination. The seedlings exhibited maximum shoot length at 5% concentration and maximum root length at 2.5% concentration. The values of root and shoot lengths, leaf area, biomass, net primary productivity, pigment content, reproductive capacity, seed output, seed weight, seed density and seed protein content in pot plants exhibited a gradual increase from the control up to 5% concentration and decreases at higher concentrations. The very high BOD load and the presence of excessive concentrations of soluble salts could be responsible for the toxicity of the effluent. The effluent at up to 5% concentration was, however, beneficial for the overall growth parameters studied and can thus be used as a liquid fertilizer.

Journal Article↗
PubMed1987

Interaction of ethanol and acute hypoxia (7620 m) on vitamin A distribution in rat organs.

The effect of a moderate dose of ethanol (3 g/kg body weight) and acute hypoxia (282 mmHg pressure) for 6 h on vitamin A content of rat tissue has been investigated. In addition, to find the effect of ethanol administration and hypoxic exposure on freshly absorbed vitamin A, a tracer dose of 3H-retinyl acetate was administered prior to hypoxic exposure. The results indicate that ethanol and hypoxia interfere in the transfer of vitamin A stored as well as freshly absorbed, from intestine to liver. When ethanol administered rats were exposed to hypoxia, the secretion of vitamin A from liver is also disturbed. The vitamin A metabolism in the tissues like kidney and lung are affected adversely on ethanol administration and/or hypoxic exposure. This could be due to interference in the transfer of vitamin A from intestine to liver and secretion of vitamin A from liver into plasma.

Absorption↗
PubMed1984

Vitamin A and biochemical development. I. Effect of postnatal excess vitamin-A administration on lipogenesis in various organs of the rat.

The effect of the administration of an excessive dose of vitamin A (1,000 IU) to rat pups on the 4th, 6th, 8th and 10th days of age was studied on the contents of saponifiable (total fatty acids) and non-saponifiable (cholesterol) lipids. Lipogenesis and cholesterogenesis was studied with the help of sodium-1-14C-acetate incorporation. The heart, liver and lung showed impaired lipogenesis while in the brain only cholesterogenesis was affected.

Acetates↗
PubMed1984

Vitamin A and biochemical development. II. Effect of postnatal excess vitamin-A administration on the activity of pyridine nucleotide-linked dehydrogenases.

The effect of excess vitamin A, (1,000 IU) administration to rat pups on the 4th, 6th, 8th and 10th days of age was studied on the activities of combined HMP dehydrogenases, malic enzyme and isocitrate dehydrogenase on the 11th, 17th and 23rd days of age. The developmental pattern and the effect of vitamin-A administration differs from enzyme to enzyme and organ to organ.

Aging↗
PubMed1983

Effect of house dust mite on serum complement activation and total haemolytic activity in vitro in normal subjects and in patients with bronchial asthma.

House dust mite (Dermatophagoides farinae) has been shown to activate the complement system in vitro by both the classical and alternative pathways in normal serum and in two groups of (skin test positive and skin test negative) patients with bronchial asthma. The activation was dose dependent in the lower range of allergen concentrations. Skin test positive asthmatic subjects showed the maximum activation. Skin test negative patients had activation between skin test positive patients and normal subjects. However, at the higher allergen concentration normal serum and bronchial asthma patients showed similar results.

Asthma↗
PubMed1983

Impaired Myelination in rats given excess vitamin A postnatally.

The effect of postnatal administration of 1000 I.U. of Vitamin A on 4th, 6th, 8th, and 10th day of age to rat pups has been studied on brain myelin lipid and sulphatide synthesis from Na235SO4. Administration of vitamin A reduced brain weight, free cholesterol, phosphatidal ethanolamine and the synthesis of myelin sulphatides from Na235SO4.

Animals↗