We have studied the effect of pH on the interactions between thymidine kinase, thymidine triphosphate, and 5'-amino-2',5'-dideoxythymidine (5'-AdThd) in purified preparations of the enzyme and in intact 647V cells, a human bladder cancer cell line. Thymidine kinase is competitively inhibited by 5'-AdThd. dTTP feedback inhibits in a noncompetitive fashion. However, 5'-AdThd partially reverses th...

Vitamin A and its derivatives have been postulated to play an important role in renal tubulogenesis and compensatory hypertrophy. This study examined the effects of two carboxylic derivatives of vitamin A on Lewis lung carcinoma-porcine kidney-1 (LLC-PK1) renal tubular epithelial cell mito- and motogenesis and cell size. It was found that all-trans and 13-cis retinoic acids exerted modest, dose...

WK, hen the epithelial cells of the cornea of the dogfish are mechanically injured, a rapid incorporation of tritium-labeled thymidine (H3 thymidine) into deoxyribonucleic acid (DNA) takes place. Incubation in vitro of conical epithelial cells of the dogfish also demonstrates a significant degree of incorporation of thymidine into DNA. The depression of thymidine uptake when the temperature is ...

of bone marrow cells from untreated rabbits. The factor responsible for the decreased uptake was found to be dialyzable and, on paper chromatography in 4 different solvent systems, had the same RF values as did thymidine. Serial dilutions of this factor gave a dose-related response in the bone marrow suspensions that was identical to that obtained with thymidine, 0.01 to 0.25 ¿ig/ml,confirming...

We examined the ability of different freshwater bacterial groups to take up leucine and thymidine in two lakes. Utilization of both substrates by freshwater bacteria was examined at the community level by looking at bulk incorporation rates and at the single-cell level by combining fluorescent in situ hybridization and signal amplification by catalysed reporter deposition with microautoradiogra...

Cadeguomycin markedly stimulated the uptake of thymidine, deoxycytidine and uridine into the acid-insoluble fraction of K562 human leukemic cells, but did not significantly affect adenosine incorporation. The enhancement of pyrimidine nucleoside uptake was 617 fold over the control. Aspartate incorporation into nucleic acid was not significantly blocked by the antibiotic, suggesting that the st...

The effects of gangliosides on human B-cell responses were studied. Of various gangliosides tested, only GM2 and GM3 inhibited production of lgG subclasses and IgM, but not IgA subclasses, and thymidine uptake by human B cells stimulated with SAC plus interleukin-2 (IL-2). In contrast, GM1, GDla, GDlb, GD3, GTlb, and GQlb were without effects. GM2and GM3-induced inhibition were specific, becaus...

Significant differences in the uptake of thymidine-(3)H, percentage of labeled cells, numbers of grains per labeled nucleus, and mitotic rate were noted in rat corneal epithelium along a 24-hr time scale. These were demonstrated by injecting subgroups of five animals every hour during a 24-hr period with thymidine-(3)H, sacrificing them 2 hr later, and analyzing the corneal epithelium by scinti...

Objectives were to determine 1) in vitro effects of bST on function of polymorphonuclear leukocytes and lymphocytes and 2) in vivo effects of bST on leukocyte function of heifers fed to maintain medium or high growth rates. When administered in vitro, bST did not affect function of polymorphonuclear leukocytes. [Methyl-3H]thymidine incorporation by resting lymphocytes was stimulated by 1000 ng/...

In defining host resistance factors in uremia, experiments were designed to assess the effect of renal failure serum upon the reactivity of normal human lymphocytes to phytohemagglutinin in vitro. Normal buffy coat cells were resuspended in sera obtained from normal subjects and from 14 patients with renal failure, then stimulated with phytohemagglutinin M and the cellular response measured by ...