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Biomedical subjects

V Misra

Publications and source records attributed to V Misra.

At least 145 records · Page 8Linked to original sources
PubMed1983

Lung mitochondria in experimental asbestosis.

Alterations in lung mitochondria were followed in guinea pigs at different periods after a single intratracheal injection of chrysotile dust. Cytochrome c oxidase and succinic dehydrogenase activities showed gradual increase after 90 days, whereas monoamine oxidase remained unaffected throughout the study. There was an increase in glutamate dehydrogenase activity in postmitochondrial as well as in mitochondrial fractions, the latter being accompanied by decreased latency of the enzyme. Mitochondria from asbestotic lung appeared to be more swollen than in normal animals at and after 90 days of exposure. There were fluctuations in the contents of different phospholipids as a result of asbestosis. Beyond 90 days, collagen and mucopolysaccharides also increased. The results confirm the contention that pulmonary mitochondria are among the major target sites in asbestosis.

Animals↗
PubMed1983

Comparative studies on ecotoxicology of synthetic detergents.

To predict the comparative toxicological response of synthetic detergents on aquatic ecosystems, the effects of various concentrations of neutralized alkyl benzene sulfonate were studied. The median tolerance limit at 48 hr, 95% confidence limit, slope function, presumable harmless concentration, and rate of survival of different species of aquatic fauna such as water fleas (Daphnia magna), mosquito larvae (Culex pipiens), slug worms (Tubifex rivulorum), snails (Lymnaea vulgaris), tadpoles (Rana cyanophlyctis), and fish fingerlings (Cirrhina mrigala) were followed at 0, 24, 48, 72, and 96 hr. Any effect on quality of the water was also tested after the addition of various concentrations of detergents. The results showed that water fleas are more susceptible to detergent toxicity than fish fingerlings, tadpoles, slug worms, snails, and mosquito larvae. Behavioral changes were also observed as an index for detergent toxicity. The relative toxicity of the detergents to various species is discussed in relation to selective ecotoxicological response.

Animals↗
PubMed1983

Adsorption of nucleic acids on asbestos fibers in vitro.

Adsorption of DNA and RNA, accompanied by liberation of orthophosphate, occurred on contact with chrysotile asbestos fibers. This indicated that interaction of macromolecules and their components may be a factor, possibly involved in the manifestation of the toxic effect of asbestos fibers.

Adsorption↗
PubMed1983

Susceptibility of bovid herpesvirus 1 to antiviral drugs: in vitro versus in vivo efficacy of (E)-5-(2-Bromovinyl)-2'-deoxyuridine.

The relative efficacies of a variety of antiviral drugs against bovid herpesvirus 1 was investigated. (E)-5-(2-Bromovinyl)-2'-deoxyuridine and trifluorothymidine were found to be inhibitory at doses of 0.01 micrograms/ml in in vitro yield reduction and plaque reduction assays. In contrast, acylovir was inactive even at concentrations as high as 1,000 micrograms/ml. Other drugs, including phosphonoformic acid, 9-beta-D-arabinofuranosyladenine, 5-iodo-2-deoxyuridine, and 1-beta-D-arabinofuranosylcytosine were active at concentrations previously shown to inhibit herpes simplex virus. Oral administration of (E)-5-(2-bromovinyl)-2'-deoxyuridine to calves infected with bovid herpesvirus 1 had no effect on the level of virus shedding, clinical signs, or susceptibility to secondary bacterial infection with Pasteurella haemolytica. The reason for this lack of in vivo activity was that sufficient levels of the drug in blood were not achieved by oral administration.

Animals↗
PubMed1983

Inhibition of glycosylation of bovine herpesvirus 1 glycoproteins by the thymidine analog (E)-5-(2 Bromovinyl)-2'-deoxyuridine.

(E)-5-(2-Bromovinyl)-2'-deoxyuridine (BVdU) was phosphorylated by the bovine herpesvirus 1 (BHV-1)-induced thymidine kinase and subsequently incorporated into viral DNA, resulting in DNA that was more dense than DNA from untreated cells. Incorporation of the drug did not result in the termination of replicating BHV-1 DNA molecules since radioactively labeled DNA synthesized in drug-treated and untreated cells sedimented at similar rates in alkaline sucrose gradients. No differences were observed in the electrophoretic mobility of [35S]methionine-labeled viral polypeptides synthesized in treated and untreated cells, although [3H]glucosamine-labeled viral glycoproteins synthesized in treated cells were of a lower molecular weight than those in untreated cells. In BVdU-treated cells, unlike untreated cells, immature neutral and basic precursors of the mature viral glycoproteins accumulated. Although BVdU-treated and untreated cells contained similar amounts of virus, very little virus was released into the culture supernatant from BVdU-treated cells. Our results suggest that BVdU partially inhibits the glycosylation of BHV-1 glycoproteins. BVdU-sensitive glycosylation, however, is not necessary for expression of these glycoproteins on the surface of infected cells since the glycoproteins could be labeled on intact cells with 125I and because BVdU-treated cells remained sensitive to antibody-dependent, cell-mediated cytotoxity mediated by anti-BHV-1 serum. The phosphorylation of BVdU was a prerequisite for its effect on glycosylation since the glycoproteins of a thymidine kinase-deficient mutant of BHV-1 were not affected.

Animals↗
PubMed1982

Susceptibility of bovine macrophages to infectious bovine rhinotracheitis virus infection.

Infectious bovine rhinotracheitis virus replicated in cultured bovine alveolar macrophages (AM). However, yields of infectious virus were low, with maximum titers approximately 100 times that of the residual inoculum. Immunofluorescence and electron microscopic studies indicated that the majority of macrophages produced viral antigen, but after infection at a multiplicity of 0.1, only 4.1% of AM produced infectious centers. Virus-infected AM culture supernatants possessed interfering activity, probably due to interferon. Incubation of fresh AM with these fluids rendered them refractory to infection. Although AM from infectious bovine rhinotracheitis virus-immune and -susceptible donors were equally permissive and their susceptibility was unaltered by incubation with bacterial lipopolysaccharide, bovine mammary macrophages which were elicited with lipopolysaccharide became nonpermissive when further incubated for 48 h with 1 microgram of lipopolysaccharide per ml. Under these conditions, infected mammary macrophages failed to synthesize viral DNA, and there was reduced synthesis of "late" viral polypeptides.

Animals↗
PubMed1982

Herpesvirus-induced "early" glycoprotein: characterization and possible role in immune cytolysis.

Glycoprotein GVP-11 (molecular weight, 71,500), induced by bovine herpesvirus type 1, was detected on the external surface of infected cells. It could be categorized as an "early" or "beta" class protein since it was synthesized early in the infectious process and its expression was not dependent upon prior viral DNA replication in the infected cells. Monoclonal antibodies directed against GVP-11 immunoprecipitated that glycoprotein and some low-molecular-weight polypeptides from infected cells labeled with either [35S]methionine or [3H]glucosamine. Immunoprecipitation of extracts from cells surface labeled with 125I yielded an additional 138,000-molecular-weight polypeptide. Tunicamycin- or bromovinyl deoxyuridine-treated infected cells yielded polypeptides that were smaller in size than corresponding glycoproteins in untreated cells. Tunicamycin-sensitive glycosylation appeared to be necessary for the expression of the glycoproteins on the surface of the infected cells. The monoclonal antibodies directed against GVP-11 and serum from an immune cow could participate in antibody- and complement-mediated immunocytolysis of infected cells, and this immunocytolysis could be enhanced by arresting cells in the early phase of viral gene expression by treatment with inhibitors of viral DNA synthesis.

Animals↗
PubMed1982

Effect of tunicamycin on rotavirus assembly and infectivity.

Bovine rotavirus grown in the presence or absence of tunicamycin was analyzed with respect to yield of infectious virus, the ratio of complete to incomplete particles, and polypeptide composition. Tunicamycin at a concentration of 1 microgram/ml reduced virus yields by 4 logs and completely prevented the incorporation of [3H]uridine into complete rotavirus particles, as determined by cesium chloride gradient analysis. Concomitant with a reduction in complete particles, three rotavirus polypeptides shifted in their relative position on polyacrylamide gels from 41,900-molecular-weight position (41.9K), 29.3K, and 16.1K to migrate at 35.5K, 22.7K, and 15.5K, respectively. Limited proteolysis indicated that the lower-molecular-weight polypeptides possessed the same constituent peptides as the larger polypeptides, suggesting that they represented the unglycosylated equivalents. These results suggest that interference with glycosylation prevents proper assembly of the outer coat proteins in bovine rotavirus.

Animals↗
PubMed1982

Genetic heterogeneity within individual bovine rotavirus isolates.

The genomic RNA patterns of six different bovine rotavirus isolates were analyzed on high-percentage polyacrylamide gels (12.5, 13.6, and 17.5%). In contrast to the RNA patterns exhibited by conventional gel systems, those on the high-percentage gels showed an improvement in segment resolution which consequently aided in the detection of extensive band splitting in these patterns. The ability to clone out various electrophoretically distinct virus subpopulations from each of the six isolates provided an explanation for the band splitting detected by the high-resolution gels. The significance of the coexistence of genetically distinct rotavirus populations within a single host is discussed.

Animals↗
PubMed1982

Effect of levamisole in immune responses to bovine herpesvirus-1.

The effect of levamisole on bovine immune responses to infectious bovine rhinotracheitis virus was assessed under laboratory and commercial feedlot situations. In all instances, levamisole appeared to have a beneficial effect on antibody responses of the cattle after vaccination. In the smaller scale pilot trials, levamisole appeared to be more efficacious when given 7 days after vaccination, presumably when a large amount of viral antigens was present as a result of viral replication. In the larger feedlot trial, however, response to administration of levamisole at the time of vaccination appeared to be slightly better than if given 7 days later. In all instances that animals had an antibody response before they were challenge-exposed with virulent virus, rectal temperature responses remained below 40 C, indicating that a threshold level of immunity may be acquired after the vaccination and that elevation of this threshold level does not necessarily alter the clinical disease. However, the amount of virus replication and shedding after challenge exposure seemed to be correlated with the level of immunity. These results are discussed in relationship to the role of immunity levels to spread of virus within a feedlot.

Animals↗
PubMed1981

Proteins Specified by bovine herpesvirus 1 (infectious bovine rhinotracheitis virus).

An electrophoretic analysis of radioactively labeled, purified, "empty" and DNA-containing infectious bovine rhinotracheitis virions revealed the presence of 25 to 33 structural (virion) polypeptides. A total of 11 of these polypeptides could be labeled with [3H]glucosamine and were identified as glycoproteins. In addition to the 25 structural polypeptides, infectious bovine rhinotracheitis virus infected cells also contained at least 15 nonstructural (nonvirion) polypeptides that were not present in purified virions. Expression of the viral polypeptides in infected cells was controlled temporally. Thus, most viral polypeptides could be categorized as "alpha" (immediate early), "beta" (early), or "gamma" (late) on the basis of their order of appearance in infected cells and whether their syntheses were dependent upon prior viral protein or DNA synthesis. None of the glycoproteins belongs to the alpha class, although at least one (GVP11) was synthesized in the absence of viral DNA synthesis. Serum from a cow in which infectious bovine rhinotracheitis virus lesions were reactivated by dexamethasone precipitated both structural and nonstructural polypeptides.

Animals↗
PubMed1981

Levamisole and bovine immunity: in vitro and in vivo effects on immune responses to herpesvirus immunization.

Levamisole was shown to enhance in vitro blastogenic responses of bovine lymphocytes to nonspecific mitogens (phytohemagglutinin and pokeweed mitogen) as well as to infectious bovine rhinotracheitis virus and purified protein derivative. Greatest enhancement was observed at suboptimal concentrations of viral antigen. In addition to enhancing lymphocyte reactivity levamisole also affected macrophage activity as determined by increased Fc receptor activity and [3H]glucosamine incorporation. Levamisole (5-50 micrograms/mL) enhanced type II immune (or gamma) interferon production by macrophage-lymphocyte cultures. Administration of levamisole and attenuated infectious bovine rhinotracheitis vaccine virus in vivo did not elevate cellular or humoral responses.

Animals↗
PubMed1980

Minor base sequence differences between the genomes of two strains of murine cytomegalovirus differing in virulence.

Two strains of murine cytomegalovirus (MCMV), differing in virulence towards mice, were compared for possible genetic differences. The two strains behaved identically in cell cultures, although the virulent strain gave higher yields of infectious virus in salivary glands. The viral DNAs displayed identical reassociation kinetics, but minor differences in their base sequences were revealed by restriction endonuclease profiles. The endonuclease profile of the "virulent" strain was conserved during serial high multiplicity infection in vitro.

Animals↗
PubMed1980

Reactivation of temperature-sensitive and non-temperature-sensitive infectious bovine rhinotracheitis vaccine virus with dexamethasone.

Latent infections by a temperature-sensitive (ts) infectious bovine rhinotracheitis virus vaccines was produced as frequently as by non-ts vaccine virus. Thus virus could be reactivated in seven of eight ts vaccinates and six of eight non-ts vaccinates after dexamethasone treatment. Virus excretion could be detectable for 1 to 8 days at a level of 2 x 10(6) to 3 x 10(8) plaque-forming units per ml of nasal secretions. The reactivated virus was shown to be the same as the original virus used for vaccination by its inability to grow at the restrictive temperature (39 degrees C) as well as by its restriction endonuclease cleavage pattern.

Animals↗
PubMed1979

Isolation and characterization of recombinant DNA plasmids carrying Drosophila tRNA genes.

Recombinant plasmids carrying Drosophila melanogaster tRNA genes were constructed by ligation of HindIII-cleaved Drosophila DNA to HindIII cut pBR322 DNA. 90 clones were isolated that contained genes for one or more of eleven tRNAs. 43 of the plasmids were characterized by a number of methods: restriction nuclease digestion; agarose gel electrophoresis; hybridization with individual, purified, 125I-labelled Drosophila tRNA molecules and in situ hybridization to Drosophila chromosomes. The results show that several different tRNA genes have been isolated which code for single, specific isoacceptors. The DNAs from 8 plasmids each hybridize to single sites on Drosophila polytene chromosomes. In addition, the data show examples of two different plasmids hybridizing to different loci coding for the same tRNA; this means that we have isolated representatives of tRNA genes which map at widely separated points on the Drosophila genome.

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