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Biomedical subjects

A Chandra

Publications and source records attributed to A Chandra.

170 records · Page 10Linked to original sources
PubMedDate not supplied

Expression of a reverse transcriptase activity in a cell line established from peritoneal macrophages of mice treated with N-methyl-N-nitrosourea.

We have established a cell line from peritoneal macrophages of mice treated intraperitoneally with N-methyl-N-nitrosourea. The present communication describes the identification of an RNA-dependent DNA-polymerase activity in a particulate fraction from supernatants of the cell culture. This activity is similar to retroviral Reverse Transcriptase (RT) based on its template specificity and ionic preference. The proof of the retrovirus-like nature of RT was obtained by ultracentrifugation of the pelleted proteins secreted in the medium on a sucrose gradient. The main RT activity was obtained in fractions of 1.14-1.16 g/ml densities, which are comparable to those of type C retroviruses. The presented data support constitutive expression of the retrovirus gene in a chemically transformed cell line.

Animals↗
PubMedDate not supplied

The establishment of a macrophage-like cell line (Ymnu) from NMRI mice treated with N-methyl-N-nitrosourea. II. Induction of differentiation of Ymnu cells: a cytochemical and immunocytochemical study.

The Ymnu cell line established by us from peritoneal exudate cells of mice treated with methylnitrosourea is of macrophage origin. We have shown that 54% of these cells possess Fc-gamma receptors and can bind opsonized erythrocytes; 30% of these cells express the nonspecific esterase and 65% the Mac-1 antigen, indicating these cells are dedifferentiated. Treatment of the cells with various differentiation inducers led to time-dependent redifferentiation of the cells. The expression of the nonspecific esterase increased to 51.1% (TPA), 42.5% (RA), 63.6% (DMSO), 40.6% (SB). The fraction of Mac-1 positive cells increased to 90.5% (TPA), 80.6% (RA), 84.5% (SB) and decreased to 52.7% (DMSO). The maximal effects of the chemicals on expression of these two parameters were achieved at different times following treatment. While RA and SB were effective after one day, the maximum effect of TPA was seen at day 5.

Animals↗
PubMedDate not supplied

The establishment of a macrophage-like cell line (Ymnu) from NMRI mice treated with N-methyl-N-nitrosourea. I. Characterization of the cell line.

Here we describe the establishment of a cell line from peritoneal exudate cells for NMRI-mice treated with methylnitroso urea, which we designate Ymnu. Tests for macrophage specific characteristics have shown that 54% of Ymnu cells possess Fc-gamma receptors, 30% are nonspecific esterase positive and 65% possess the macrophage specific antigen Mac-1, indicating their macrophage origin. Although of macrophage origin, the majority of these cells are round, 13 microns in diameter. The cells grow partially in suspension and have doubling times varying from 3 to 1.75 days depending on serum concentration. Cultures of Ymnu cells achieve after 14 days densities 4 times higher than those achieved by NIH-3T3 cells. Ymnu cells have lost the anchorage dependence of growth and grew very well on semi-solid media. In addition, they possess an oncogenic potential and build tumors when injected subcutaneously in nude mice.

Animals↗
PubMedDate not supplied

Characterization of the RNA dependent DNA polymerase of bovine leukemia virus.

The reverse transcriptase-RNA dependent DNA polymerase of Bovine Leukemia Virus (BLV) was isolated and characterized. The enzyme has a molecular weight of about 80kd and the isoelectric point is 7.6. The enzyme prefers magnesium, as a divalent cation using synthetic homopolymeric template primer poly (C) oligo (dG). Monoclonal antibodies directed against reverse transcriptase of human immunodeficiency virus type I (HIV-I) did not crossreact with the isolated polymerase.

Antibodies, Monoclonal↗
PubMedDate not supplied

Impaired fecundity in the United States: 1982-1995.

CONTEXT: The 1995 National Survey of Family Growth (NSFG) provides new nationally representative data to test the accuracy of the commonly held assumption that impaired fecundity has been rising in the United States over the past decade. METHODS: Using data from the 1982, 1988 and 1995 rounds of the NSFG, trends in both the proportions and numbers of women with impaired fecundity and of those who received infertility services were examined. Multiple logistic regressions were carried out to estimate the effects of demographic characteristics on the likelihood of currently having impaired fecundity and of ever having received medical help for infertility. RESULTS: The proportion of U.S. women aged 15-44 who reported some form of fecundity impairment rose from 8% in 1982 and 1988 to 10% in 1995, an increase in absolute numbers from 4.6 million to 6.2 million women. Although the proportion of fecundity-impaired women who had ever sought medical help did not change between 1988 and 1995 (44%), the absolute numbers of such women grew by nearly 30%, from 2.1 million to 2.7 million. Women who had ever sought help for fertility problems were older and had a higher income than those who had not, and were more likely to be married. CONCLUSION: The dramatic increase in the numbers of U.S. women with impaired fecundity occurred because the large baby-boom cohort, many of whom delayed childbearing, had reached their later and less fecund reproductive years. This increase in both rates and numbers occurred across almost all age, parity, marital status, education, income, and race and ethnicity subgroups.

Adolescent↗