Search PubMed⌕ Search

Biomedical subjects

K M Anderson

Publications and source records attributed to K M Anderson.

At least 181 records · Page 10Linked to original sources
PubMed1980

Stabilization of human breast cancer progesterone (5020) receptor by sodium molybdate.

Inclusion of the salt, sodium molybdate, at 20 mmol/l concentration during the determination of progesterone receptor in human breast cancer cytosols was associated in a number of samples with marked stabilization of binding by the radioactive ligand, 5020, to 8S and 4S receptors. Both the percent of positive patients and the absolute amount of PR were increased, with the appearance of 8S peaks where none had been evident in controls without the salt, and increased amounts of 8S and 4S binding in other samples. In addition, results from some dextran-coated charcoal assays were altered, and positive samples incubated in the presence of the salt frequently yielded higher values of PR. Finally, estrogen receptor values determined by SDG assays have been increased in the presence of the salt. Routine addition of sodium molybdate to samples analyzed for PR by centrifugation overnight can be expected to yield an increased percent of receptor-positive patients with higher average concentration of receptor, compared with results of previous methodology. Its presence during the dextran-coated charcoal assay can also alter the measured binding. Although the stability of ER during overnight centrifugation is greater, in some patients additional receptor can be detected when buffers include this salt.

Breast Neoplasms↗
PubMed1980

Sodium molybdate increases the amount of progesterone and estrogen receptor detected in certain human breast cancer cytosols.

When sodium molybdate is added at a final concentration of 20 mM, additional 8S and 4S progesterone (3H-R5020) receptor can be detected in the cytosols from a number of human breast cancers. Additional estrogen receptor also could be measured in some cytosols, and a quantitative temperature-dependent conversion of 8S to 4S binding molecules achieved. Sodium molybdate also prevented the loss of binding activity that occurred when cytosols were incubated at 30 degrees in the absence of added estradiol. In addition to increasing the amount of progesterone receptor, and to a lesser extent estrogen receptor that may be detected, elicidation of the mechanism by which this salt stabilized receptors should contribute to further understanding of how cytosol steroid receptor content and function is regulated.

Breast Neoplasms↗
PubMed1980

Adriamycin-induced alterations of the action potential in rat papillary muscle.

The present study investigates the effects of adriamycin on the electrophysiological properties of the myocardium as monitored by intracellular recordings of the cardiac action potential. ADR was administered to rats at a dose of 20 mg . kg-1 given as a single intravenous injection or in four daily doses of 5 mg . kg-1 each. Twenty-four hours following the last injection, papillary muscles were removed and intracellular recordings of the action potential were sampled from the tissue. In another set of experiments, papillary muscles were removed from non-injected, control animals and superfused in vitro with adriamycin at a concentration of 200 mumol . litre-1. Several parameters of the action potential were measured and compared with control values in both in vivo and in vitro experiments. In all studies, the major effect of adriamycin on the cardiac action potential was shown to be a prolongation of the duration at 20%, 50% and 98% repolarisation. Adriamycin did not appear to exert its effect by depression of cell metabolism, as superfusion with NaCN or dinitrophenol reduced the action potential duration. The upstroke velocity, which is proportional to the sodium conductance, was unaltered by ADR; it appears that ADR alters conductance of calcium and/or potassium across the myocardial membrane by an as yet unknown mechanism.

Action Potentials↗
PubMed1980

Isolation of viable rat ventral prostate epithelial and nonepithelial cells.

A procedure is described for the dispersion, partial purification, and identification of epithelial and nonepithelial cells from the rat ventral prostate, the latter based in part upon the ability of cells to bind androgen. Since initial efforts to mechanically disrupt prostatic tissue at 2 C lysed many cells, minced rat prostates were exposed to collagenase at 37 C and further dispersed by repetitive pipetting and passage through a tissue sieve. Washed cells in culture medium were centrifuged through an isokinetic Ficoll gradient from which three visible fraction (1, 2, and 4) and a less definite fraction 3 were harvested. Characterically, fraction 1 contained cellular debris; fraction 2 contained round nucleated cells, fewer elliptically shaped cells, red blood cells, and rare free cell nuclei; fraction 3 contained somewhat larger elliptical and round cells; and fraction 4 contained larger round and elliptically shaped cells. These were epithelial cells, as judged by electron microscopy. Isolated prostate cells from rats castrated for 24 h were incubated with [3H]testosterone; 80-90% of the retained radioactivity, the majority of which was dihydrotestosterone, was associated with washed cells from fraction 4. Similar results were obtained after in vivo administration of labeled androgen and subsequent analysis of radioactivity in cells from these fractions. Histochemically and enzymatically demonstrable formalin-insensitive acid phosphatase was increased in bands 3 and 4, which were enriched in epithelial cells. Many cells in fractions 2-4 were viable before and after exposure to Ficoll, as estimated by their ability to exclude trypan blue, incorporate radioactive uridine into RNA, generate cell monolayers during 1-4 weeks of culture, and actively metabolize androgens. Compared to fraction 4, cells from fraction 2, considered to be enriched in nonepithelial cells, actively metabolized but bound much less [3H]testosterone and its metabolites. A number of epithelial cells in fraction 4 isolated from prostates dissociated at 2 C were associated with typical-C-type RNA viruses.

Animals↗
PubMed1977

Electron-microscopic visualization of transcriptionally active and less active chromatin fractions from the rat ventral prostate and their content of histones.

The content of histones in transcriptionally active (euchromatin-like (E)) and transcriptionally less active (heterochromatin-like (H)) fractions from the rat ventral prostate was determined. The absolute amount of total histone was less in the E fraction, which contained relatively more stained histone F2b and F3 and less histone F1 than either the H fraction or unfractionated chromatin. The phosphotungstic-acid-stained E fraction was composed predominantly of shorter (50-500 nm) and thinner (5-15 nm) structures. In some preparations, pieces estimated to be 500-1000 + nm in length were present. Spherical structures, from 10 to 20 nm in diameter, some of which were present as 'dimers,' trimers,' or higher-ordered ensembles were seen in the shadow-case E fraction. The stained or shadow-cast H fraction contained longer (200-2000 + nm) and thicker (congruent to 20 nm) fragments with a more complex substructure. When the shadow-cast H fraction was sufficiently dispersed, it had a nodular or 'beaded' appearance.

Animals↗
PubMed1976

Transplantation resistance to mouse ependymoblastoma following immunization with dehistonized syngeneic tumor chromatin.

Female C57BL/J6 mice pretreated with dehistonized ependymoblastoma chromatin rejected 5 x 10(4) or 10(5) s.c.-implanted syngeneic ependymoblastoma cells. Control mice that received Freund's adjuvant containing dehistonized chromatin from normal mouse brain developed palpable tumor nodules in 90% and 35 to 45% of the animals, respectively. Increased binding of spleen lymphocytes from mice pretreated with dehistonized tumor chromatin to Sepharose 4B coupled with components of dehistonized tumor chromatin was observed. This provides initial evidence for the presence of "committed" lymphocytes in mice pretreated with dehistonized chromatin from this mouse ependymoblastoma.

Animals↗
PubMed1975

Solubilized DNA-dependent nuclear RNA polymerases from the mammary glands of late-pregnant rats.

Mammary gland nuclear extracts from late-pregnant Wistar or Sprague-Dwaley rats, analyzed by DEAE-Sephadex chromatography, were found to contain DNA-dependent RNA polymerases, cyclic nucleotide-binding proteins, and cyclic AMP-independent protein kinases. 1. The fractions from chromatographed nuclear extracts which contained nucleolar enzymes or nucleoplasmic enzyme II, bound radioactive cyclic AMP and cyclic GMP. Other fractions also bound cyclic nucleotides, some preferentially associating with one or the other compound. 2. Cyclic AMP increased the amount of RNA formed by several alpha-amanitin-insensitive fractions containing nucleolar enzymes. 3. Cyclic AMP reduced the amount of RNA formed by column fractions which included nucleoplasmic enzyme II. 4. Cyclic GMP increased the amount of RNA synthesized by column fractions containing enzyme II. 5. Two major cyclic AMP-independent protein kinases which did not elute with enzymes Ib and II, and several minor protein kinases were present. These findings may have important implications for understanding the proximate control of transcription. A relationship between them is not established, but is under study.

Amanitins↗