Search PubMed⌕ Search

Biomedical subjects

K McCoy

Publications and source records attributed to K McCoy.

At least 73 records · Page 4Linked to original sources
PubMed1989

Falling in love.

Explore the source record for details and available documents.

Humans↗
PubMed1988

An acid protease secreted by transformed cells interferes with antigen processing.

The major excreted protein of malignantly transformed mouse fibroblasts (MEP), which is the precursor to lysosomal cathepsin L, was used to study the effect of exogenous acid proteases on antigen processing. When MEP and native pigeon cytochrome c were added to Chinese hamster ovary (CHO) cells expressing transfected major histocompatability complex class II gene products, the antigen-specific T-cell hybridoma 2B4 did not respond to the antigen. MEP appears to destroy the antigen in an acid compartment of the presenting cell because: (a) MEP is only active as a protease under acid conditions; (b) mannose 6-phosphate inhibited the internalization of MEP and blocked its effect on antigen processing; (c) the destruction required the simultaneous entry of the antigen and MEP into the cells; and (d) cytochrome c fragment 66-104 which does not need to be processed stimulated 2B4 in the presence of MEP. These results support the hypothesis that antigen processing requires internalization of the antigen into an acidic compartment, and they provide a new model for the investigation of the contribution of acid proteases to the reduced immunocompetence of tumor-bearing animals.

Animals↗
PubMed1988

Weight, composition, mitosis, cell death and content of progesterone and DNA in the corpus luteum of pregnancy in the ewe.

Changes in luteal weight from about Day 20 to near term, and in quantitative histology as assessed by ultrastructural morphometry and light microscopic counts of mitosis and cell death on Days 30, 60, 100 and 142, were studied in 168 pregnant ewes. Luteal weight (mean +/- s.d.) remained constant at 0.56 +/- 0.11 g until Day 120, and fell thereafter to reach 0.31 +/- 0.11 g after Day 140 (P less than 0.01). Up to Day 100, quantitative aspects of the composition of the luteal tissue showed no significant change, and values for volume density, cytoplasmic:nuclear ratio, cell number/mm3 and cell volume were comparable to values previously obtained for corpora lutea (CL) of the cycle. By Day 142 structural evidence of luteal regression was present, but regressive changes were much more marked in some CL than others. Mitosis was seen in a few cells (0.02-0.04%) on all of the days studied, but never in large luteal cells. Cell death was rarely seen up to Day 100, but had increased in incidence by Day 142 (P less than 0.01). Luteal progesterone content, 55.2 +/- 15.9 nmol/g on Day 30, was not significantly changed on Days 60, 100 or 142. It is concluded that (1) structural regression of the CL of pregnancy does not begin until much later than the time (about Day 50) when pregnancy ceases to depend on the CL; (2) structural luteal regression begins before parturition, but its time of onset and/or rate of progression vary widely between animals; and (3) large and small luteal cells remain as distinctive populations throughout pregnancy, and their numbers at all stages can be accounted for by survival of the cells which differentiate during the genesis of the CL.

Animals↗
PubMed1981

Deficiency in cells expressing terminal transferase in autoimmune (motheaten) mice.

The extensive breakdown of immune homeostasis in the motheaten mouse (me/me) has been ascribed to a single gene defect on chromosome 6 (ref. 1). These mice develop skin lesions within the first week of life, do not thrive, and die within the first 3--8 weeks. There is severe hypergammaglobulinaemia with multiple species of circulating autoantibody and deposition of immune complexes in the thymus, skin, lungs and kidneys. A single gene defect producing such catastrophic results may provide an important model for understanding autoimmune phenomena. We report here a virtual absence of terminal deoxynucleotidyl transferase-positive (TdT+) cells in the bone marrow, thymus and spleen of motheaten mice. TdT is a DNA polymerase which has the unique capacity to polymerize nucleotides in the absence of template direction. Although no in vivo biological function of this enzyme has been established, its unique appearance in the bone marrow and thymus of adult mammals and its in vitro biochemical activity have led to a proposed role for TdT in the somatic diversification of lymphocytes. Bone marrow TdT+ cells have been shown to belong to both T and B cell populations and may also include precursor cells common to these lineages. Although the role of TdT in the acquisition of appropriate T- and B-cell specificities is not known, our results are the first to correlate the virtual absence of TdT+ cells with a severe autoimmune syndrome. We investigated the level of TdT+ cells in neonatal me/me mice and their normal littermates and the susceptibility of TdT+ cells to circulating autoantibody in motheaten mouse serum.

Animals↗
PubMedDate not supplied

The heroin epidemic in New York City: current status and prognoses.

Since 1989, heroin production worldwide has risen; in New York City, as its purity rose and prices fell, street-level markets were restructured and offered heroin in addition to cocaine and crack (which had been popular during the 1980s). While officials estimate that there are between 500,000 and one million hard-core, chronic heroin users nationwide, evidence of supplemental users heralding another heroin era includes: more overdoses and overdose deaths, greater demand for treatment, larger seizures of heroin at all levels of distribution and related arrests, and broader media coverage. In this article, the authors describe the characteristics of populations in which there may have been a percentage increase of new users, such as young middle- or upper-class European-Americans, young Puerto Ricans and recent Haitian and Russian immigrants. The abstinence of young African-Americans is also noted. The article ends with a preliminary needs assessment of the new users in the areas of health (including AIDS), housing, employment, treatment, arrest and imprisonment.

Administration, Inhalation↗