A growth stimulating activity has been recently identified in the rat proximal intestine during the transient stages of adaptation after small bowel resection. This study shows that the growth stimulating activity is associated with all the cells of the crypt-villus axis. At the same time the thymidine kinase activity is detectable in all the cells implying a more extensive proliferative zone d...

A mutant line of BHK21 cells lacking inosinic pyrophosphorylase activity (IPP~ cells) does not incorporate [*H]hypoxanthine, as opposed to wild type BHK cells. When IPP+ and IPP~ cells are grown together in the presence of [H]hypoxanthine, IPP~ cells in contact with IPP+ cells incorporate the marker, as seen by autoradiography. This phenomenon is known as 'metabolic co-operation'. In the presen...

3-[5-{2-(2,3-Dihydroxyprop-1-yl)-o-carboran-1-yl}pentan-1-yl]thymidine (N5-2OH) is a first generation 3-carboranyl thymidine analog (3CTA) that has been intensively studied as a boron-10 ((10)B) delivery agent for neutron capture therapy (NCT). N5-2OH is an excellent substrate of thymidine kinase 1 and its favorable biodistribution profile in rodents led to successful preclinical NCT of rats be...

Unlike their parent strains, zidovudine-resistant derivatives of Escherichia coli KL16 and Salmonella typhimurium NCTC 5710 were found to be incapable of incorporating radiolabelled thymidine into their chromosomal DNA. Since incorporation was still prevented in the presence of EDTA, resistance to zidovudine was not associated with a permeability barrier, but appeared to result from the loss of...

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...

We have used the sequence of the cell-cycle regulatory region of human thymidine kinase promoter to study the DNA-protein interaction in hu man tumor and normal cells. By performing band-shift assays and DNase I footprint analysis, we have demonstrated that human tumor cells exhib ited an elevated level of binding activity to the distal CCAAT box of human thymidine kinase promoter. The expressi...