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Biomedical subjects

S Andrews

Publications and source records attributed to S Andrews.

At least 91 records · Page 5Linked to original sources
PubMed1982

Further dissection of the functional heterogeneity within the OKT4+ and OKT8+ human T cell subsets.

Previous studies have suggested functional heterogeneity within the OKT4+ and the OKT8+ populations. For example, after activation the OKT4+ population contains not only helper cells but also cells capable of suppressing B cell differentiation. Previous studies also indicate that the reciprocal T cell population, OKT8+, does not provide helper activity but contains cytotoxic effector cells and radiosensitive cells important in the suppression of B cell differentiation. Using a new differentiation antigen, OKT17, which recognizes a surface antigen present on the majority of resting normal peripheral T lymphocytes but is present only on a subset of OKT4+ cells after activation, evidence was obtained that two functionally mature subsets can be distinguished within the OKT4+ population itself: OKT4+17+ radiosensitive suppressor cells and OKT4+17- radiosensitive helper cells. Recently, another monoclonal antibody, OKT20, has been described which is present on a small percentage of resting lymphocytes but is expressed in varying proportions on activated T cells. Functional analysis of normal resting human T lymphocytes demonstrated that the OKT20-depleted T cell subset was able to generate cytotoxic cells and to suppress antibody production to the same extent as did OKT8+ cells. On the other hand, when unselected T lymphocytes were cultured for six days in a mixed lymphocyte reaction and then depleted of OKT20 reactive cells, the cytotoxic effector T cells were eliminated. In contrast, OKT20-depleted T cells after identical activation were still able to suppress antibody production. These data provide evidence that following activation of OKT8+ cells, the OKT20 differentiation antigen becomes selectively expressed on cytotoxic effectors but not on suppressor cells.

Antibodies, Monoclonal↗
PubMed1979

Electrophoretic analyses of lactate dehydrogenase C4 in testes and vesicular glands of normal and male sterile translocation mice.

Lactate dehydrogenase (LDH) C, activity was observed in testis extracts from normal mice but was progressively reduced in mice carrying the male-sterile translocations T31H, T32H, T37H, T38H, T40H and T42H, with no detectable activity being observed in the last two mice. None of the vesicular gland extracts from these male-steriles showed LDH-C4 activity, unlike normal mice. The differential LDH-C4 activity in male-sterile testes is interpreted as reflecting the varying stages of the spermatogenic defect during meiosis. In general, early meiotic defects exhibited no LDH-C4 activity whereas late stage (usually after metaphase-1 stage) defect animals exhibited some activity. The results also provide evidence for contaminating sperm being the source of normal vesicular gland LDH-C4 activity.

Animals↗
PubMed1977

The anaerobic oxidation of dihydroorotate by Escherichia coli K-12.

The oxidation of dihydroorotate under anaerobic conditions has been examined using various mutant strains of Escherichia coli K-12. This oxidation in cells grown anaerobically in a glucose minimal medium is linked via menaquinone to the fumarate reductase enzyme coded for by the frd gene and is independent of the cytochromes. The same dihydroorotate dehydrogenase protein functions in both the anaerobic and aerobic oxidation of dihydroorotate. Ferricyanide can act as an artificial electron acceptor for dihydroorotate dehydrogenase and the dihydroorotate-menaquinone-ferricyanide reductase activity can be solubilised by 2 M guanidine-HCl with little loss of activity.

Anaerobiosis↗
PubMed1977

Single-dose trials of monovalent A/New Jersey/76 (Hsw1N1) influenza virus vaccine in children in Durham, North Carolina.

Ninety-two children received single doses of one of 13 monovalent vaccines derived from influenza virus strain A/New Jersey/8/76 (A/NJ), and 18 children received placebo. Five influenza virus vaccines were whole-virus vaccines, and eight were split-product vaccines. Samples of sera were taken once three weeks after vaccination. All of the 29 children receiving whole-virus vaccines developed a titer of antibody to A/NJ virus of greater than or equal to 1:20, and the geometric mean titers were 1:14-1:45. One of the 60 children who received split-product vaccines developed a titer of antibody to A/NJ of greater than or equal to 1:20, and geometric mean titers were all less than 1:10. There was a trend toward correlation between titers of hemagglutination-inhibiting (HAI) antibody to A/NJ and titers of HAI antibody to A/Victoria/3/75 viruses, with a correlation coefficient of 0.40 for children who received whole-virus vaccines. Three of 60 recipients of split-product vaccines and two of 20 recipients of whole virus developed a fever of greater than or equal to 38 C. One of the two febrile children who had received whole-virus vaccine had otitis media. Therefore, reactogenicity of whole-virus vaccines and split-product vaccines appeared to be similar in these children.

Antibodies, Viral↗
PubMed1976

Corneal glycogen synthesis. I. Evidence for a gluconeogenic pathway in beef cornea.

Beef eye anterior chambers were perfused with media containing radiolabeled glycogen precursors. Incorporation of 14C from 1-alanine-U-14C into corneal epithelium glycogen suggested the presence of a gluconeogenic pathway in the eye. Failure to isolate radioactive glucose from 1-alanine-U-14C-containing perfusate after passage through the anterior chamber strongly suggests a corneal site for this pathway.

Alanine↗
PubMed1971

Purification and properties of 3-deoxy-d-arabinoheptulosonic acid-7-phosphate synthetase (phe) from a lambda aroG+ transductant of Escherichia coli.

By incorporating aroG, the structural gene for 3-deoxy-d-arabinoheptulosonic acid-7-phosphate (DAHP) synthetase (phe), into the genome of a heat-inducible susR60 mutant of phage lambda, it has been possible to increase the intracellular levels of DAHP synthetase (phe) in a lysogenized strain of Escherichia coli some 15-fold over levels found in the wild-type strain. By using this strain, the enzyme has been purified approximately 2,000-fold compared with wild type, and various kinetic parameters of the purified enzyme have been studied. In contrast to previous reports, the inhibition by phenylalanine was found to exhibit sigmoidal kinetics, suggestive of cooperative interactions between phenylalanine binding sites. Stimulation of enzyme activity by Co(2+) was minimal (14%).

Aldehyde-Lyases↗