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Biomedical subjects

K R Harrap

Publications and source records attributed to K R Harrap.

At least 145 records · Page 8Linked to original sources
PubMed1972

The uptake and utilization of chlorambucil by lymphocytes from patients with chronic lymphocytic leukaemia.

It has been shown that lymphocytes isolated from the peripheral blood of patients with chronic lymphocytic leukaemia do not modify the mustard group of chlorambucil, as has been demonstrated previously in Yoshida ascites cells. However, lymphocytes from patients with an unsatisfactory clinical course or poor response to treatment were able to modify the aromatic region of the drug molecule; little change occurred in the aromatic absorption of intracellular chlorambucil in patients who responded to treatment. This simple test may provide a rapid assessment of a patient's potential response to chemotherapy.

Chlorambucil↗
PubMed1969

Some effects of chlorambucil on enzymes of glutathione metabolism in drug-sensitive and -resistant strains of the Yoshida ascites sarcoma.

1. Yoshida ascites cells from a strain sensitive to chemotherapy with alkylating agents contained elevated activities of the two enzymes directly responsible for glutathione synthesis, in comparison with a resistant cell strain. The activities of the glutathione-degrading enzyme gamma-glutamyltranspeptidase were comparable in both cell strains. 2. After parenteral administration of chlorambucil to rats carrying either strain of tumour, the activities of the glutathione-synthetic enzymes increased in the sensitive cells, but remained unchanged in the resistant cells. Drug treatment was without effect on the gamma-glutamyltranspeptidase activity of either cell strain. 3. The activities of a number of enzymes concerned in the oxidoreduction of glutathione remained unchanged after the administration of chlorambucil to rats carrying either strain of cells.

Acyltransferases↗
PubMedDate not supplied

ZD1694 (Tomudex): a new thymidylate synthase inhibitor with activity in colorectal cancer.

ZD1694 (Tomudex) is a new antifolate which is a specific inhibitor of thymidylate synthase (TS). Evidence suggests that ZD1694 has a spectrum of activity that only partially overlaps with 5-fluorouracil (modulated with leucovorin) against colon tumours in vitro. Potent cytotoxic activity is dependent upon active uptake into cells via the reduced folate/methotrexate cell membrane carrier (RFC) and subsequent metabolism to polyglutamated forms (tri, tetra and pentaglutamates). These polyglutamates are approximately 60-fold more active as TS inhibitors and are not effluxed readily from cells. Extensive polyglutamation also occurs in various mouse tissues (e.g. small intestinal epithelium, liver and kidney), resulting in high tissue/plasma drug ratios which persist for a prolonged period. ZD1694 has antitumour activity in mice, although the high plasma thymidine in this species complicates: (1) the interpretation of therapeutic index; (2) tumour types in which activity is likely to be observed; and (3) translation of doses and schedules for clinical evaluation. ZD1694 entered clinical study and has completed Phase I and II evaluation, with activity observed in several tumour types. Appreciable activity in the Phase II colorectal study (29% objective response rate on interim analysis) led to the current Phase III study, randomised against 5-fluorouracil/leucovorin.

Animals↗