Both glycine and methionine, when added to a suspension of human bone marrow cells, impaired the utilization of deoxyuridine for DNA synthesis, using either the uptake of 3H-deoxyuridine or the subsequent uptake of 3H-thymidine as an index. Homocysteine reduced the uptake of both 3H-deoxyuridine and 3H-thymidine, indicating interference with DNA synthesis after the stage of thymidylate synthesi...

By EFSTRATIOS S. KURTIDES, WALTER A. RAMBACH AND HOWARD L. ALT T HE INCORPORATION of tritiated thymidine by the rat spleen is an accurate and reliable index of erythropoiesis under certain well-defined experimental conditions.1 Since tritiated thymidine uptake by various tissues reflects DNA synthesis, and therefore proliferative activity, changes in the latter will be reflected by parallel cha...

Recent studies have found basic fibroblast growth factor (bFGF), an angiogenic peptide, in retina and have suggested that bFGF is responsible for retinal vascular proliferation. To test the hypothesis that bFGF stimulates 3H-thymidine uptake in retinal vascular cells in vivo, we injected bFGF (100 ng) into the vitreous cavity of six cats at 0 hr and again at 24 hr. Eight control eyes received b...

One assumption made in bacterial production estimates from [3H]thymidine incorporation is that all heterotrophic bacteria can incorporate exogenous thymidine into DNA. Heterotrophic marine bacterium isolates from Tampa Bay, Fla., Chesapeake Bay, Md., and a coral surface microlayer were examined for thymidine uptake (transport), thymidine incorporation, the presence of thymidine kinase genes, an...

These studies explore the effects of an epipodophyllotoxin on the membrane transport and metabolism of thymidine in Ehrlich ascites tumor cells. Uptake of 3H after exposure of cells to [3H]thymidine is characterized by a rapid initial velocity that approx imates membrane transport followed by a slower rate of uptake that parallels the accumulation of phosphorylated derivatives of thymidine, pri...

The initial rate of thymidine-(3)H incorporation into the acid-soluble pool by cultured Novikoff rat hepatoma cells was investigated as a function of the thymidine concentration in the medium. Below, but not above 2 microM, thymidine incorporation followed normal Michaelis-Menten kinetics at 22 degrees , 27 degrees , 32 degrees , and 37 degrees C with an apparent K(m) of 0.5 microM, and the V(m...

SYNOPSIS. Attempts at continuous labeling of Crithidia fasciculata D.N.A with ["H]thymidine led to a pulse-chase situation due to a ccll-mediated conversion of thymidine to thymine in the medium. The uptake of ihymine was slow compared to that of thymidine. Neither the addition of deoxyadenosine nor the sequential addition of several aliquots of ['H] thymidine had an effect on the pattern of la...

The mitogenic effect of the novel lectin prepared from an animal source on human lymphocytes was examined in comparison with that of phytohemagglutinin-p (PHA-p) by the uptake of 3H-thymidine. The uptake of 3H-thymidine by lymphoblasts was enhanced by the treatment with the lectin as well as with PHA-p, though the effect of the lectin was difficult to compare exactly with that of PHA-p.

Receptors for insulin and epidermal growth factor (EGF) have been studied in confluent cultured intact human fibroblast monolayers. 125-I-EGF binds specifically to fibroblast monolayers. Half-maximal binding is observed at 4 times 10 minus 10 M EGF; at saturation of binding approximately 4 times 10-4 molecules of EGF are bound per cell. 125-I-Insulin is also bound specifically by intact monolay...

Human peripheral blood lymphocytes stimulated with Histoplasma capsulatum yeasts were exposed in culture to graded concentrations of ketoconazole or amphotericin B and subsequently assessed for membrane integrity, thymidine uptake, and blastogenesis. Lymphocyte reactivity varied with concentration and duration of exposure to ketoconazole. Overt membrane toxicity resulted from exposure to 40 mic...