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Biomedical subjects

G Sharma

Publications and source records attributed to G Sharma.

At least 55 records · Page 3Linked to original sources
PubMed1991

Effect of ethanol on cadmium-induced lipid peroxidation and antioxidant enzymes in rat liver.

We have investigated the effects of the intragastric administration of cadmium (10 mg/kg body weight) and ethanol (5.56 g/kg body weight) alone as well as in combination on hepatic lipid peroxidation, the antioxidant defense system, and the morphology of liver in rats. Cadmium given in combination with ethanol led to a marked increase in cadmium accumulation in liver compared to the level in rats treated only with cadmium. Further, cadmium and ethanol coexposure produced a more pronounced elevation in lipid peroxidation (L-px), which was associated with a significantly greater inhibition of antioxidant enzymes, glutathione peroxidase (GSH-px; EC 1.11.1.9), glutathione reductase (GR; EC 1.6.4.2) and superoxide dismutase (SOD; EC 1.15.1.1), than cadmium treatment alone. The levels of glutathione (GSH) and total thiols (TSH) also decreased significantly after cadmium and ethanol coexposure. On histopathological examination, it was observed that the livers of rats coexposed to cadmium and ethanol showed a marked degeneration of hepatocytes which was not seen in rats treated only with cadmium.

Animals↗
PubMed1991

An influenza virus containing nine different RNA segments.

The packaging mechanism of segmented RNA viruses has not been well studied. Specifically, it has not been clear whether influenza A viruses package only eight RNA segments or whether virus particles contain more than eight segments. Using a newly developed ribonucleoprotein (RNP) transfection method, we engineered an influenza virus which must contain nine different RNA segments rather than the usual eight in order to survive under the experimental growth conditions. This result is compatible with a mechanism of packaging which allows influenza virus to encapsidate more than eight RNA segments. We also suggest that the virus packages its RNAs randomly and that this random packaging results in infectious viruses with the required ("right") complement of RNA segments.

Animals↗
PubMed1991

Effect of ethanol on cadmium uptake and metabolism of zinc and copper in rats exposed to cadmium.

Effects of chronic administration of cadmium and ethanol, alone as well as in combination, on the uptake of cadmium and its interaction with other essential trace elements in various tissues of adult rats were investigated. Cadmium given in combination with ethanol led to a pronounced increase in cadmium absorption and accumulation in all the tissues studied relative to both non-exposed controls and rats treated with cadmium alone. Both cadmium and ethanol exhibited specific effects on copper and zinc levels of the tissues. These effects often were significantly altered when the animals were co-exposed to cadmium and ethanol. The results suggested that although both cadmium and ethanol individually pose a hazard to essential trace metal homeostasis of various organs, co-exposure can pose a major threat since animals exposed to ethanol absorb much more cadmium than their unexposed counterparts.

Absorption↗
PubMed1990

Remnant model of renal failure in the dog: avoidance of second surgery by chemical nephrectomy.

Experimental chronic renal failure in the dog is usually studied by a two-step surgical procedure. However, it is becoming increasingly difficult, due to animal welfare concerns, to get permission for such procedures in Canada. We describe a method for obviating the need for second surgery by injecting absolute alcohol into a renal artery, which leads to immediate functional nephrectomy.

Animal Welfare↗
PubMed1989

Evaluation of desferrioxamine mesylate on survival, and prevention of histopathological changes in the liver, in haemorrhagic shock: an experimental study in dogs.

Desferrioxamine mesylate (desferal) an iron chelating agent was investigated in anaesthetized standard haemorrhagic shock (HS) dogs with elective hypotension at 35 +/- 5 mmHg for 4 h and return of withdrawn blood (ROWB) thereafter. Observations were made in respect of serum iron elevation over 4 h and survival and recovery pattern over 72 h after ROWB. Influence of the drug on histopathological changes of shock in liver were studied in non-survival experiments (dogs sacrificed after 4 h of elective hypotension). Desferal administration (25 mg/kg i.m.) at 30 min after initial bleeding, increased the 72 h survival from 10% (controls) to 50%, and reduced the serum iron elevation from 63.3% (controls) to 9.44%. The single control survivor remained unconscious till 24 h and sluggish in activity up to 72 h. Three of the drug treated survivors regained consciousness by 2 h, activity by 24 h and all were normally active by 72 h. Severe congestive and degenerative changes in liver, present in the controls, were markedly reduced in severity and incidence in those given desferal. It is suggested that iron decompartmentalization in the hypoxic tissues in HS with its consequent rise in serum and intracellular pool, plays a pivotal role in progression towards irreversibility. Desferal, an effective intracellular iron chelator, possibly arrests the widespread cellular damage caused through enhanced iron-catalysed .OH radical generation in shock state.

Animals↗
PubMed1989

Involvement of an inducible factor in interferon-gamma-mediated accumulation of HLA gene transcripts.

Earlier studies with a cDNA clone (C5-4) complementary to an interferon (IFN)-gamma-inducible mRNA showed that in human fibroblasts (FS-4), IFN-gamma induced the transcription of the cognate gene, but it required new protein synthesis (Caplen and Gupta, J. Biol. Chem. 263, 332-339, 1988). To determine whether such a strategy is used for the regulation of other cellular genes by IFN-gamma, the regulation of the HLA class I and class II genes and another cellular gene for which a cDNA clone was isolated (C13) was studied. The results indicate that: (i) HLA-B (class I) and C13 gene expression was transcriptionally activated by IFN-gamma and IFN-alpha 2, and it did not require new protein synthesis. (ii) In contrast, the transcription of the HLA-DR alpha was activated by IFN-gamma (and not by IFN-alpha 2), but the accumulation of -DR alpha gene transcripts was strongly inhibited by cycloheximide or anisomycin, which indicated that there was a requirement for some newly synthesized protein factor(s) in this process, apparently at a step subsequent to transcriptional activation. We obtained evidence indicating that the putative protein factor(s) required is actually induced by IFN-gamma. (iii) IFN-gamma-induced transcription of the HLA-B gene was not inhibited by anisomycin or cycloheximide, but the accumulation of HLA-B transcripts plateaued sooner. This latter effect was not due to any toxicity of these inhibitors because it was observed if cycloheximide was added together with IFN-gamma, but not if it was added a few hours later. Furthermore, if cycloheximide was added 24 h after IFN-gamma, it actually caused a superinduction of HLA-B transcripts. The results suggest that some newly synthesized protein factor(s) may be required also for maximal accumulation of HLA-B gene transcripts following treatment with IFN-gamma. The results indicate a dual regulation of HLA class I and class II genes by IFN-gamma, and involvement of multiple mechanisms in the regulation of cellular gene expression by IFN-gamma.

Genes, MHC Class I↗
PubMed1989

Protection by desferrioxamine against histopathological changes of the liver in the post-oligaemic phase of clinical haemorrhagic shock in dogs: correlation with improved survival rate and recovery.

Haemorrhagic shock was produced in anaesthetized dogs, by rapid arterial bleeding to mean arterial blood pressure 35 mmHg, and maintained oligaemic for 4 h followed by return of withdrawn blood(ROWB). Dogs were observed for 72 h after ROWB for survival and recovery, and, for histopathological (HP) studies on liver, dogs were sacrificed 2 h after ROWB in non-survival experiments. Desferrioxamine mesylate (25 mg/kg) was administered intra-muscularly at 2,3 and 4 h after blood loss in survival experiments and for HP studies the drug was given at 4 h in one group and at 2 h plus 4 h after blood loss in the second group. With the drug given at 3 or 4 h, survival was 70% and 100% while in the 2 h and the untreated groups it was 50%. Recovery was rapid in all the drug treated survivors, few became conscious within 30 min, showed slight activity by 4-6 h, all were almost normally active by 24 and fully so by 72 h after ROWB. All the 5 control survivors remained unconscious/drowsy upto 24 h; 3 were sluggish at 72 h. By group analysis, serum iron elevation during the oligaemic and at the end of the post-oligaemic phase was less in the drug-treated animals. HP changes of shock in the liver studied by light microscopy, were markedly reduced in severity and were less prevalent in the drug-treated dogs. The salutory effects of desferrioxamine may be due to inhibition of iron catalyzed free-radical production and tissue damage, through its strong iron chelating action. It may have a therapeutic advantage in this emergency condition without the disadvantages of toxicity inherent in prolonged use.

Animals↗
PubMed1986

Construction of genomic libraries of mycobacterial origin: identification of recombinants encoding mycobacterial-specific proteins.

A complete genomic library from Mycobacterium vaccae (2785 recombinants) and a partial genomic library of M. leprae and BCG (300 and 1750 clones, respectively) were constructed in the plasmid pBR322. Bam HI was selected as the restriction endonuclease for obtaining DNA cleavage products. Evidence was obtained for limited expression of the cloned mycobacterial DNA inserts in Escherichia coli. A recombinant has been identified which codes for antigen immunoreactive with rabbit anti-M. leprae antibody but not with anti-H37Rv antibody.

Antigens, Bacterial↗
PubMed1981

Age-dependent changes in esterases of Callosobruchus maculatus Fab. (Bruchidae: Coleoptera).

Age-dependent changes, quantitative as well as qualitative, in esterase activity were found by assaying crude extracts of Callosobruchus maculatus. There is increase in esterase activity in both the sexes with advancing age in bruchids. Esterase from old bruchids showed several additional electrophoretic bands which did not appear in assays of young bruchids; in addition there is an increase in staining intensity of the bands. A rapid increase in esterase activity during the last days of life may be responsible for producing energy used in various metabolic processes in an attempt to escape death.

Aging↗
PubMed1980

Age-related glycogen changes in bruchids.

Quantitative measurements of glycogen in aging bruchids showed there was a considerable decrease (> 50%) with age except on the fifth day when an increase was observed, followed by a decrease on the sixth day. The variations in glycogen content with age suggests that glycogen serves as one of the energy sources responsible for the maintenance of metabolism in the process of aging in bruchids.

Aging↗
PubMed1978

Cytogenetic effects of influenza virus infection on male germ cells of mice.

Swiss albino male mice were administered two doses (1 and 2 HA units) of influenza A2 Hong Kong/68 virus IP. The incidence of chromosomal anomalies in spermatocytes was analysed at various times post infection and was found to be significantly higher than in controls, indicating that the influenza virus had induced these anomalies.

Animals↗