Dipicolinic acid (DPA), present in large amount bacterial spores, has been proposed to act as an endogenous photosensitizer spore photoproduct formation. The mechanism involves a triplet-triplet energy transfer from DPA thymine. However, up now, no spectroscopic studies have performed determine the interaction between compound and nucleobase, probably due its photolability aqueous solutions. He...

Corynebacterium parvum induces rapid proliferation of spleen cells with concomitant rapid increases in DNA synthesis as measured by [3H]thymidine uptake and increase in DNA polymerase activity. Cell number increased exponentially over 10 days. DNA polymerase activity increased 8-fold after C. parvum stimulation. The rapidity of response indicated a population response to the stimulus, and the d...

It has been previously demonstrated (1) that the length of the period of DNA synthesis (S period) as measured by uptake of tritiated thymidine is approximately the same in several animal cells. Since the length of this period (with a range of 6/~ to 8 hours) appears to be independent of the species of the cell, the chromosome number, the cells of human diploid strains in long term cultivation.

Diiron enneacarbonyl, colloidal iron particles used for removing monocytes, enhanced the 3H-thymidine uptake into the mitogen-stimulated human lymphocytes in serum-free medium, whereas neither silica particles, latex particles, carbonyl iron powder nor iron pentacarbonyl did. Because monocytes had no influence on the enhancing effect or diiron enneacarbonyl did not bind to PHA, it was suggested...

UNLABELLED Using different tracers of tumor metabolism, the application of PET for monitoring gene therapy with the suicide gene herpes simplex virus thymidine kinase (HSVtk) is investigated in this in vitro study. METHODS Morris hepatoma cells were transfected with a retroviral vector bearing the HSVtk gene, and different clones were established by selection with the neomycin analog G418. Th...

The regression of mammary tumor MTW9after resection of mammosomatotropic tumor MtTWS has been studied further. Twenty-four hr after resection of MtTWS, MTW9 DNA was increased while incorporation of thymidine-3H into MTW9 was decreased. Uptake of a-aminoisobutyric acid, glycine, methionine, and possibly phenylalanine into the trichloroacetic acid-soluble fraction of MTW9 slices was reduced 24 hr...

A fraction (60F) having cytotoxic and antitumor activities was obtained from cell-free extract of group A Streptococcus pyogenes by precipitating with 50% to 60% saturated ammonium sulfate. 60F showed cytotoxic activity inhibiting the uptake of 3H-thymidine by S180 sarcoma cells and enhancing 51Cr-release from 51Cr-labeled cells. 60F showed also antitumor activity, depressing tumor growth and p...

[3H]thymidine uptake and colony counts are quantitative and inexpensive methods for studying Spiroplasma growth. Using these techniques, we demonstrated subtle effects on the growth of suckling mouse cataract agent of medium alterations, inoculum size, and freezing of cultures. In addition, suckling mouse cataract agent multiplied more actively under aerobic than under anaerobic conditions. The...

Ciprofloxacin was tested for its inhibitory or stimulatory effects on concanavalin A- and phytohemagglutinin-stimulated proliferation (measured by [3H]thymidine uptake) of human peripheral blood mononuclear cells and murine splenocytes. Ciprofloxacin did not diminish or enhance mononuclear cell proliferation at concentrations of 5 to 125 micrograms/ml. Further, the proliferative response of spl...

Peripheral blood monocytes and synovial macrophages obtained from 21 patients with rheumatoid arthritis and from 13 controls were cultured with autologous peripheral blood lymphocytes and stimulation measured by thymidine uptake. Rheumatoid macrophages and monocytes induced a small but significant degree of lymphocyte transformation, and those from the controls did not. The degree of stimulatio...