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Biomedical subjects

G Harris

Publications and source records attributed to G Harris.

At least 199 records · Page 11Linked to original sources
PubMed1975

The effects of thymidine and its analogues on the differentiation of antibody-forming cells.

Thymidine (Tdr) and its analogues 5-fluorodeoxyuridine (FUdr) and 5-bromodeoxyuridine (BUdr) inhibited the development of antibody-producing cells (PFC) in cultures of explants of rabbit spleen stimulated with sheep red cells in vitro. They were effective in this respect, even at concentrations too low to inhibit cell division. The results indicated that Tdr had produced its effects by a selective action on DNA and RNA synthesis. In view of what is known about the mechanisms of action of Tdr and its analogues to interfere with DNA-dependent events in cells, these results supported the idea that DNA synthesis, unrelated to the needs for cell division, was required for the development of antibody-producing capacity by PFC in these cultures.

Animals↗
PubMed1975

Thymidine kinase of mouse spleen cells in vivo and in vitro.

The thymidine kinase activity of mouse spleen cells was found to parallel their DNA-synthesizing ability, both in vivo and in vitro. In the former case, more than 90% of the activity of these cells was found in the cytoplasmic fraction. This activity was labile, as was its template mRNA, compared with the nuclear component. The nuclear enzyme increased during culture of the lymphocytes in vitro. Mitogenic stimulation with concanavalin A resulted not only in a greater enhancement of the nuclear activity, but also in a marked increase in the amount of cytoplasmic enzyme. This effect appeared to be mediated via stabilization of the mRNA for the cytoplasmic component. These differences have been considered, especially with respect to the cellular changes that occurred during culture and mitogenic stimulation.

Animals↗
PubMed1975

DNA synthesis in rabbit spleen explants. Its relationship to cell division.

The synthesis of DNA, as measured by the incorporation of [3H]-thymidine into the nuclei of cells of cultured explants of rabbit spleen, has been studied and correlated with estimation of DNA content of these nuclei using Feulgen densitometry, with and without colcemid arrest. Observations of the proportion of nuclei labelled with [3H]thymidine and their DNA content indicated that many cells were incorporating this precursor for DNA synthesis without the concomitant increases in DNA expected of cells in division cycle. Colcemid arrest failed to produce the changes in DNA content expected of a cell population as rapidly dividing as the labelling kinetics suggested. The results indicated that [3H]thymidine-labelled material, possibly DNA, was being transferred between cells and this accounted for the increased labelling index seen after pulsing with [3H]thymidine. The suppression of [3H]thymidine uptake by hydroxyurea indicated that this was not repair synthesis of damaged DNA.

Animals↗
PubMed1975

The labelling of peripheral blood lymphocytes of the mouse with [3H]thymidine.

The labelling of lymphocytes in the peripheral blood of mice following a single injection of [3H]thymidine was studied in autoradiographs exposed for 185 days before processing. The proportion of labelled cells was found to be greater than could be accounted for by new lymphocyte production. In addition, stimulation by sheep red cells 2 hours after giving [3H]thymidine resulted in the appearance of more labelled lymphocytes in the blood, but the greatest differences from control mice occurred relatively late in the immune response after cell proliferation in the responding lymphoid organ had reverted to control levels. The results are discussed on the basis that they indicate synthesis of DNA and reutilization of label by lymphocytes, which then circulate in the blood, these processes possibly occurring in the bone marrow and lymphoid tissues.

Animals↗