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Biomedical subjects

R C Gupta

Publications and source records attributed to R C Gupta.

At least 289 records · Page 16Linked to original sources
PubMed1982

32P-postlabeling analysis of non-radioactive aromatic carcinogen--DNA adducts.

A newly developed enzymatic 32P-postlabeling method was applied to the analysis of DNA's containing non-radioactive arylamine, arylamide, and polycyclic aromatic hydrocarbon adducts. DNA reacted in vitro with N-hydroxy-2-amino-fluorene, N-acetoxy-2-acetylaminofluorene, and 7 beta,8 alpha-dihydroxy-9 alpha,10 alpha-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene, respectively, as well as DNA preparations from the liver of rats treated with N-hydroxy-2-acetylaminofluorene and benzo[a]pyrene, respectively, were enzymatically digested to deoxyribonucleoside 3'-monophosphates, which were then converted to [5'-32P]deoxyribonucleoside 3',5'-bisphosphates by T4 polynucleotide kinase-catalyzed [32P]phosphate transfer from [gamma-32P]ATP. The 32P-labeled nucleotides were resolved by anion-exchange t.l.c. on polyethyleneimine-cellulose and detected by autoradiography. Aromatic adduct nucleotides were found to be retained at the origin in aqueous electrolyte solutions, but to migrate as distinct spots in solvents containing 7-8.5 M urea. Advantage was taken of this observation to remove 32P-labeled normal DNA nucleotides from adduct nucleotides. This purification enabled the detection of a single adduct in 10(7)-10(8) normal nucleotides. The method appears applicable to the ultrasensitive detection of a large number of carcinogen--DNA adducts of diverse structure without requiring radioactive carcinogens or specific antibodies.

Animals↗
PubMed1982

Characterization of antigen moiety of HBsAg in the complement fixing immune complexes of hepatitis B virus positive chronic active hepatitis.

Circulating immune complexes (CIC) are frequently found in hepatitis B virus-induced chronic active hepatitis. Since antigen and antibody moieties of complexes are critical in determining many of its pathogenic factors, the constituents of these complexes were investigated with particular attention to the quantity and nature of the HBs antigen moiety of the complexes. Complement fixing immune complexes were isolated from sera of 14 patients with chronic active hepatitis by utilizing conglutinin's unique property to bind C3-fixed complexes. Low pH (2.6) was used to dissociate the complexes. Components of dissociated complexes were separated into antigen and antibody fractions using immobilized Protein A. Both fractions were analysed by electrophoresis in polyacrylamide gel with SDS. The antibody fractions showed heavy and light chains of IgG and IgM. The antigen fractions demonstrated six to 10 protein bands with mol. wt ranging between 17,000 and 120,000 daltons. To define precisely the polypeptide antigen moiety involved in the immune complex formation, a transfer blotting technique was used employing human anti-HBs globulin as probe. Polypeptides with mol. wt 97,000 and 49,000 reacted as antigen moieties of HBsAg. In addition, the levels of HBsAg in the antigen fractions were significantly greater (P less than 0.005) compared to sera from patients with acute hepatitis. Implications of these findings are discussed.

Adult↗
PubMed1981

Immune complexes and autoantibodies in silicosis.

Serum specimens from 53 patients with silicosis were examined for the presence of antinuclear antibodies (ANA), rheumatoid factor (RF), immunoglobulins, and immune complexes. These humoral immunologic parameters were compared with radiographic changes and pulmonary function studies. A significant percentage of patients had an increased prevalence of ANA, RF, and immunoglobulin elevation (IgG, IgA). Immune complexes determined by the Raji-cell assay were detected in 31% of the patients. However, there was no significant correlation between any humoral immunologic abnormality and radiographic changes or declines in pulmonary function tests. These findings suggest that humoral immunologic abnormalities are not directly responsible for the lung changes in silicosis and cannot be used as "guides" to predict severity or progression of disease.

Adult↗
PubMed1981

Pregnancy in suboestrus buffaloes (Bubalus bubalis) after treatment with Prostaglandin F(2) alpha.

Seventy six apparently anoestrous buffaloes, with a palpable corpus luteum at day 43 to 547 post partum, were treated intramuscularly with Prostaglandin, using either 25 mg single dose (Group I), 25 mg double dose 11 days apart (Group II), or 50 mg single dose (Group III). Animals exhibiting oestrus, without any treatment, during the period of experimentation served as control (Group IV). The overall conception rate for the treated animals was 28.8, 51,5, and 69.7 percents after one, two, and three inseminations, respectively. The conception rate, at induced as well as subsequent oestrus, was comparable to control animals. The intergroup differences among treated animals were not significant. The conception rate was greater when the induced heat was more intensely expressed. The subsequent mean oestrus cycle length was similar to controls when all of the treated animals were considered together.

Journal Article↗
PubMed1981

32P-labeling test for DNA damage.

Covalent adducts formed by the reaction of DNA with chemical carcinogens and mutagens may be detected by a 32P-labeling test. DNA preparations exposed to chemicals known to bind covalently to DNA [N-methyl-N-nitrosourea, dimethyl sulfate, formaldehyde, beta-propiolactone, propylene oxide, streptozotocin, nitrogen mustard, and 1,3-bis(2-chloroethyl)-1-nitrosourea] were digested to a mixture of deoxynucleoside 3'-monophosphates by incubation with micrococcal endonuclease (EC 3.1.31.1) and spleen exonuclease (EC 3.1.16.1). The digests were treated with [gamma-32P]ATP and T4 polynucleotide kinase (ATP:5'-dephosphopolynucleotide 5'-phosphotransferase, EC 2.7.1.78) to convert the monophosphates to 5'-32P-labeled deoxynucleoside 3',5'-bis-phosphates. These compounds were then separated on polyethyleneimine-cellulose thin layers in ammonium formate and ammonium sulfate solutions. Autoradiograms of the chromatograms obtained by this high-resolution procedure showed the presence of nucleotides derived from chemically altered, as well as normal, DNA constituents. Maps from DNA exposed to any of the chemicals used exhibited a spot pattern typical for the particular chemical. This method detected a single adduct in 10(5) DNA nucleotides without requiring that the compound under investigation be radioactive and thus provides a useful test to screen chemicals for their capacity to damage DNA by covalent binding.

Animals↗