Elevated serum γ-glutamyl transferase (GGT) levels were found in 29% of 155 chronic
alcoholics undergoing detoxification treatment. Alkaline phosphatase (AP) was increased in 16%,
alanine aminotransferase - SGPT (ALT) in 12% of the patients, while 23% had elevations of either
AP or ALT or both. Of the foregoing parameters, GGT was the best single indicator of liver
involvement. In course of the follow-ups GGT/ALT correlation improved, but GGT/AP correlation
deteriorated. In 9 patients, abstinence during follow-up was associated with progressive decrease in
previously elevated serum GGT. Because of its unique sensitivity, GGT may be useful as a
screening and/or monitoring aid in alcoholism.
Chronic forced feeding of iodine in small doses accelerates mammary tumour appearance in female rats after treatment with 7,12-dimethylbenz-(a)anthracene; extended exposure to cold, which also results in acceleration of metabolism with a transient increase of thyroid function, does not influence carcinogenesis in this model in a similar way.
(1) Alkaline phosphatases were
present in all subcellular fractions obtained by
ultracentrifugation of all the tissues examined.
(2) The highest specific activities (mU/mg protein) were found in the microsomal fractions,
the lowest in the supernatant, with the exception of the mammary tumour examined. (3) A
different thermostability of the enzymes in the
various fractions pointed to the presence of isoenzymes; a biphasic curve gave
evidence of the simultaneous presence of at least two isoenzymes in some particulate
structures. (4) There was no specific thermolabile pattern of alkaline phosphatases in
the malignant tissues examined, assuming the method used is valid for establishing
such differences.
The R3230AC rat mammary adenocarcinoma is a transplantable tumor model, which can be subcultured in vitro and does not metastasize spontaneously. However, when cell suspensions of this tumor are injected intravenously, multiple lung foci develop. These foci were used as source for a cell subpopulation. Prolonged exposure of the original tumor cell line to increasing levels of lectins (concanavalin A and wheat germ agglutinin) resulted in the development of a lectin-resistant subpopulation. Through experimental in vitro exposure to the antiestrogenic compound tamoxifen citrate, a tolerant, karyotypically defined subpopulation was obtained. In the four cell lines studied, heterogeneity was observed in the following parameters: doubling time, steroid receptors, and median chromosome counts. Statistically discernible differences were found. This may represent a model for the effect of selective pressures in the tumor environment, such as endocrine manipulation, leading to the gradual development of resistant cell lines and treatment failure.
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