Mediation by an androgen receptor of the stimulatory effect of testosterone on the growth of a fibrosarcoma in the rat.

We studied the effect of testosterone on the growth of a 20- methylcholanthrene-induced transplanted fibrosarcoma and assayed androgen receptors in this tumor. The effect of an antiandrogen in male rats and the comparative tumor growth in females confirmed the androgen sensitivity. A synthetic androgen that strongly binds to the androgen receptor was used to characterize the binding activity in nuclear extracts of tumor.

Thiazolidine-4-carboxylate and 2-phenylthiazolidine-4-carboxylate are active as cysteine precursors but have no effect on growth of a methionine-dependent tumor in rats.

Diets with partial replacement of sulfur amino acids by thiazolidine-4-carboxylate or 2-phenylthiazolidine-4-carboxylate were fed to normal and to rhabdomyosarcoma-bearing rats (methionine-dependent tumor) to evaluate their efficacy as cysteine precursors and as antitumor agents. Food intake, weight gain, food efficiency and plasma albumin and plasma sulfur amino acid concentrations were not different when these diets were compared with isosulfurous diets containing either methionine or N-acetylcysteine. 2-Phenylthiazolidine-4-carboxylate induced a lower plasma glutathione (GSH) level than the latter diets.

Effect of severely alkali-treated casein on gastrointestinal transit and selected intestinal enzyme activities.

Alkaline treatment of proteins leads to chemical changes which alter the proteins' digestibility. Severely alkali-treated casein (0.2N NaOH, 80 degrees C, 1 hour) in the diet reduces food intake and growth of young but not of adult Sprague Dawley rats.

[Formation of trypsin inhibitors during alkaline treatment of proteins].

Casein is submitted to a severe alkaline treatment (NaOH 0,2 or 0,5 N, 1 hr., 80 degrees C). The hydrolysis by pancreatic enzymes (trypsin or chymotrypsin) is reduced in vitro and, in the case of the more severe treatment, stopped.