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Biomedical subjects

W Gibson

Publications and source records attributed to W Gibson.

156 records · Page 9Linked to original sources
PubMed1971

Compartmentalization of spermine and spermidine in the herpes simplex virion.

Enveloped particles of herpes simplex virus produced in human cells in culture contained spermidine and spermine, in a molar ratio of 1.6 +/- 0.2. The spermine present within the nucleocapsid is sufficient to neutralize at least 40% of the viral DNA. Disruption of the envelope with nonionic detergent and urea resulted in the selective loss of spermidine. Exogenous ornithine can function as a precursor to host and viral polyamines only before infection.

Carcinoma↗
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↗
PubMedDate not supplied

First trimester fetal heart rate: response to chorionic villus sampling in the chromosomally normal fetus.

The objective of this prospective study was to evaluate the fetal heart rate before and after the procedure and whether this had any effect on the risk of pregnancy loss following chorionic villus sampling (CVS) and chromosomally normal pregnancies. Four hundred and seventeen pregnancies were evaluated. The heart rate before the procedure was similar for both male and female fetuses. Significant procedure-related changes in fetal heart rate occurred only with male fetuses undergoing the transabdominal CVS technique. Fetal heart rate decelerations following CVS were more common than accelerations. Fetal heart rate changes following CVS were not able to predict the pregnancies ending in spontaneous abortion. Transabdominal CVS had a lower loss rate after the procedure, compared to the transcervical technique (p = 0.0001). Small-for-date fetuses had a higher loss rate after the procedure compared to normal-sized fetuses (p = 0.001).

Abortion, Spontaneous↗
PubMedDate not supplied

A comparative study of frusemide-amiloride and cyclopenthiazide-potassium chloride in the treatment of congestive cardiac failure in general practice.

Forty-seven patients entered this comparison of frusemide-amiloride and cyclopenthiazide-potassium chloride in the treatment of congestive cardiac failure in general practice. Frusemide-amiloride was 'very satisfactory' in 92% of the patients compared to only 55% who took cyclopenthiazide-potassium chloride. Significantly more patients were free of paroxysmal nocturnal dyspnoea and orthopnoea after taking frusemide-amiloride.

Amiloride↗
PubMedDate not supplied

The evolution of trypanosomes infecting humans and primates.

Based on phylogenetic analysis of 18S rRNA sequences and clade taxon composition, this paper adopts a biogeographical approach to understanding the evolutionary relationships of the human and primate infective trypanosomes, Trypanosoma cruzi, T. brucei, T. rangeli and T. cyclops. Results indicate that these parasites have divergent origins and fundamentally different patterns of evolution. T. cruzi is placed in a clade with T. rangeli and trypanosomes specific to bats and a kangaroo. The predominantly South American and Australian origins of parasites within this clade suggest an ancient southern super-continent origin for ancestral T. cruzi, possibly in marsupials. T. brucei clusters exclusively with mammalian, salivarian trypanosomes of African origin, suggesting an evolutionary history confined to Africa, while T. cyclops, from an Asian primate appears to have evolved separately and is placed in a clade with T. (Megatrypanum) species. Relating clade taxon composition to palaeogeographic evidence, the divergence of T. brucei and T. cruzi can be dated to the mid-Cretaceous, around 100 million years before present, following the separation of Africa, South America and Euramerica. Such an estimate of divergence time is considerably more recent than those of most previous studies based on molecular clock methods. Perhaps significantly, Salivarian trypanosomes appear, from these data, to be evolving several times faster than Schizotrypanum species, a factor which may have contributed to previous anomalous estimates of divergence times.

Animals↗