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Biomedical subjects

V Thurston

Publications and source records attributed to V Thurston.

6 recordsLinked to original sources
PubMed2000

A physiological model to predict xenobiotic concentration in fish.

A physiological model was developed to estimate fish body toxicant load based on information regarding the chemical exposure regime, fish body weight, lipid content and oxygen uptake. The general model was tested in which an oxygen database (OXYREF) was used to predict fish toxicant body burden. Based on the quantitative analysis, it was shown that the model was reliable and accurate in estimating fish body burden of a number of non-metabolized aquatic toxicants. This modified model possesses some functional reality which enables more realistic predictions, making it useful in the practice of aquatic environmental risk assessment.

Journal Article↗
PubMed2000

Relationship between toxicant transfer kinetic processes and fish oxygen consumption.

Three organic compounds of different hydrophobicity, 1,2,4,5-tetrachlorobenzene (TeCB), 3,4,5,6-tetrachloroguaiacol (TeCG) and 4,6-dichlorobenzenediol (DBD), were chosen as the test chemicals to carry out a series of investigations to look at the relationship between toxicant transfer and fish metabolic rate. A significant correlation was found between the toxicant uptake rate constant (k(1)) and fish oxygen consumption, regardless of fish size and species. This correlation was improved when fish toxicant body load was expressed on a percent body lipid basis. Similarly, there also existed a significant relationship between the toxicant depuration rate constant (k(2)) and fish oxygen uptake for a range of chemicals with different octanol/water partition coefficients (K(ow)).

Journal Article↗
PubMed1988

Activated ras oncogenes in human thyroid cancers.

Human thyroid epithelial (follicular) cells give rise to two malignant tumors--"follicular" carcinomas, which metastasize almost exclusively via the bloodstream, and "papillary" carcinomas, which metastasize predominantly via lymphatics (Williams, E. D. In: W. Duncan (ed.), Recent Results in Cancer Research: Thyroid Cancer, pp. 47-55. Berlin: Springer-Verlag, 1980). We have investigated whether this contrast in biological behavior might be associated with different patterns of oncogene activation. DNA transfection analysis of five follicular and ten papillary cancers indeed showed a statistically significant difference in the pattern of genes responsible, activated ras oncogenes being found in 80% of follicular tumors but only 20% of papillary tumors. In addition, in follicular cancers we have found activation of all three ras oncogenes (H-ras, K-ras, and N-ras), the first time that this has been demonstrated in a primary human tumor type (as opposed to cell lines). We suggest therefore that ras activation may be an important determinant of metastatic capability in these epithelial cancers.

Animals↗
PubMed1988

Agent-specific ras oncogene activation in rat thyroid tumours.

Activated ras oncogenes have been detected in a number of rodent tumour model systems (Balmain et al., 1986; Barbacid 1987), in which chemical carcinogens have been the most widely used inducing agents. We have investigated the involvement of activated oncogenes in a single well-characterised tumour model, rat thyroid neoplasia, produced not only by chemical carcinogen (nitrosomethylurea, NMU) and by ionizing radiation but also by elevated trophic stimulation alone. We have indentified a striking specificity in patterns of ras oncogene activation, with exclusively Ha-ras activated in 87% of NMU-induced tumours and exclusively Ki-ras activated in 60% of radiation-induced tumours.

Amitrole↗
PubMed1982

The effect of radiation on thyroid C cells.

To study the effects of radiation from 131I on thyroid C cells, new born rats were given 0.5 or 10 muCi 131I and studied at 3 monthly intervals over 2 years. Routine stains, calcitonin immunolocalization and quantitation were used to study follicular and C cells. Both radiation doses led to almost complete disappearance of C cells, with only scattered morphological abnormal surviving cells. After a year, some animals showed focal reappearance of C cells; these isolated cluster were interpreted as clones of cells, derived after a considerable lag period, from the very few surviving C cells which had not been sterilized. This focal regeneration was dose dependent. It is concluded that C cells are much more radiosensitive to radiation from 131I than follicular cells. These observations support the use of 131I therapy in the treatment of post-operative thyroid deposits of medullary carcinoma.

Age Factors↗