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Biomedical subjects

S M Wilson

Publications and source records attributed to S M Wilson.

At least 181 records · Page 10Linked to original sources
PubMedDate not supplied

ras transfection and expression does not induce progression from tumorigenicity to metastatic ability in mouse LTA cells.

Studies testing the ability of a transfected ras oncogene to confer metastatic properties on non-metastatic cells have yielded conflicting results. Most of these studies have used recipient cells at early stages of progression (primary or immortalized, non-tumorigenic lines). In this study we tested the ability of the T24-H-ras oncogene to induce progression of tumorigenic, non-metastatic, murine LTA cells to a metastatic phenotype. Metastatic ability was assessed in complementary assays in two immune-deficient hosts, nude mice (after s.c. injection) and chick embryos (after i.v. injection), to determine if ras transfection affected metastatic properties in hosts lacking an intact immune system. Even with greatly elevated levels of ras p21 protein, pools of ras-transfected cells as well as individual clonal populations remained non-metastatic in both hosts. Serial in vivo passaging did not consistently enhance for either ras expression or metastatic ability. We conclude that expression of an activated ras oncogene in LTA cells does not induce progression from a tumorigenic to a metastatic phenotype. These results are in marked contrast to those obtained for ras expression in most other types. High levels of expression of an activated ras oncogene thus do not always promote progression from tumorigenicity to metastatic ability.

Animals↗
PubMedDate not supplied

No evidence of malonyldialdehyde formation during reoxygenation injury in vitamin E-deficient rat heart.

Vitamin E is an endogenous antioxidant and is known to afford protection against lipid peroxidation. If lipid peroxidation was an important factor in the pathogenesis of reoxygenation injury in heart, then both the extent of lipid peroxidation and cell injury would be expected to be exacerbated in vitamin E-deficient hearts. To study reoxygenation injury in the present experiments, rat hearts were perfused in the Langendorff mode with a modified Krebs-Henseleit buffer under anoxic conditions for 60 min before resuming normoxic perfusion for 20 min. Creatine phosphokinase (CPK) activity and malonyldialdehyde (MDA), a product of lipid peroxidation, were assayed in the perfusate effluent from hearts during reoxygenation injury. Also, myocardial MDA and vitamin E contents were measured in extracts of freeze-clamped heart tissue obtained immediately before and 2 min after reoxygenation. Experiments were performed on hearts from groups of weanling rats fed either a vitamin E-deficient or vitamin E-supplemented diet (50 I.U. vitamin E/kg) for 5 to 6 weeks. After 5 weeks, the myocardial vitamin-E content was 103.8 +/- 5.3 (n = 5) and 11.5 +/- 1.6 (n = 4) ng/mg protein (mean +/- SEM) in the vitamin E-supplemented and vitamin E-deficient groups respectively. Perfused hearts from both dietary groups showed a peak of enzyme release 2 to 3 min after the reintroduction of oxygen, and enzyme release from vitamin E-deficient hearts was two-fold greater than enzyme release from vitamin E-supplemented hearts.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

Simplification of the polymerase chain reaction for detection of Mycobacterium tuberculosis in the tropics.

It has been suggested that the technical complexities, the expense of equipment and consumables, and problems associated with contamination make the polymerase chain reaction (PCR) inappropriate for use in developing countries. These problems were addressed using a novel one-tube nested PCR, small reaction volumes and a 'three room' system for the detection of Mycobacterium tuberculosis. The PCR of sputum samples dried on small filter paper disks was also investigated. Using this strategy 5 smear-positive and 15 smear-negative specimens were correctly identified by PCR. This method of sample collection has the advantage that samples can be sent by post and stored in a minimum of space, and remain viable for PCR for at least 4 years after collection. These and future modifications to the PCR protocol will make the assay more suitable for use in the tropics.

Base Sequence↗
PubMedDate not supplied

Inactivation of mycobacteriophage D29 using ferrous ammonium sulphate as a tool for the detection of viable Mycobacterium smegmatis and M. tuberculosis.

There is still an urgent requirement for more sensitive, cost-effective methods for detection and susceptibility testing of mycobacteria in clinical samples. We have been investigating a simple bacteriophage-based system which could be used for both purposes. As this depends upon the detection of phages which have successfully infected cells, a key step is the efficient removal or inactivation of phages remaining free in the culture medium. We demonstrate here the use of ferrous ammonium sulphate as an effective agent for the inactivation of mycobacteriophage D29 without impairing phage replication in previously infected host bacteria. Using this property, we report the detection of viable Mycobacterium smegmatis, M. bovis BCG and M. tuberculosis using simple low-cost technology. The method is highly sensitive, since it is able to detect 10 colony-forming units of M. smegmatis. It is also rapid, with the detection of M. tuberculosis in sputum specimens within 48 h.

Colony Count, Microbial↗
PubMedDate not supplied

Purine nucleotides modulate proliferation of brown fat preadipocytes.

The hypothesis that purine nucleotides and nucleosides affect brown fat preadipocyte proliferation was tested using isolated rat interscapular brown fat preadipocytes in culture. Daily addition of 100 microM adenosine triphosphate (ATP) (n = 4) to cultures enhanced the relative DNA content by 1.5-fold compared to control cultures (P < 0.05) measured using CyQUANT-GR fluorescence. Higher concentrations of ATP inhibited growth and 500 (n = 2) or 1000 microM ATP (n = 3) almost completely inhibited growth. ATP (100 microM) did not affect while 250-1000 microM ATP decreased protein content relative to control cultures. Adenosine (100 microM; n = 3) did not affect DNA or protein content, but 500 microM and 1000 microM adenosine suppressed brown adipocyte proliferation and inhibited protein synthesis. Cultured brown adipocytes quickly removed or degraded ATP in the culture media as determined by luciferin-luciferase bioluminescence, suggesting that the inhibitory effects of high ATP concentrations may result from its breakdown to adenosine. The results support the conclusion that ATP promotes and adenosine inhibits brown adipocyte proliferation.

Adenosine↗
PubMedDate not supplied

In vivo distribution of injected 14C-dioxyadenine in tissues and organs of normal rats.

A large dose of 2, 8-dioxyadenine-14C was injected intravenously into rats and its fate followed at several intervals during the first 24 hours after administration. The distribution of the radioactive material throughout the various tissues or organs was calculated and expressed as a percentage of the injected dose as well as a specific activity per unit organ weight. It appears that dioxyadenine is rapidly distributed throughout the organs and tissues of the rats and that specific concentration occurs in a few organs. High retention of the radioactive material and a very high specific activity are observed in the kidney. Smaller but significant concentrations of the 14C-compound are also observed in muscle and skin, and cannot be attributed to the presence of residual blood. The radioactive material is gradually released from these tissues and, by 24 hours after injection, 92 per cent of the injected dose is found in the urine. Microscopic observation shows deposition of crystals in the kidney. Crystals are also present in the urine and appear as small slightly yellow spheres.

Adenine↗