Biomedical subjects
Publications and source records attributed to S Sakai.
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Properties of prolactin receptors were measured by monitoring [125I]prolactin binding to specific receptor sites on collagenase-dissociated mammary epithelial cells of virgin, pregnant and lactating mice. On a Scatchard plot the data generated a straight line and the estimated dissociation constant (Kd) and number of receptor sites on lactating cells were 0.9 x 10(-9) and 1540 per cell. The [125I]prolactin binding was inhibited in presence of unlabeled prolactin and other lactogenic polypeptide hormones, but not by nonlactogenic polypeptide hormones. The [125I]prolactin binding was sensitive to pronase and trypsin but not to DNAase, RNAase and hyaluronidase. Scatchard plot analysis further showed that while the number of receptors on mammary cells was variable at different stages of endocrine regulated developmental changes of the gland, Kd of the hormone--receptor complex generally remained similar. The high level of prolactin receptors on mammary cells of virgins was reduced during pregnancy and the lactating mammary cells showed a highly elevated level of prolactin receptors. The results demonstrate that specific prolactin receptors can be measured on collagenase dissociated mammary epithelial cells and this method permits a direct assessment of the number of receptors on a per cell basis rather than indirect estimates, based on average DNA or protein content of the tissue, composed of heterogeneous cell types.
Induction of content and activity of hepatic and lung cytochrome P450-dependent monooxygenases by 3-methylcholanthrene (MCA) was studied in male rhesus monkeys. Hepatic microsomes were concomitantly studied for mutagenic activation of N-2-acetylaminofluorene (AAF) as well as with the use of sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Hepatic N-hydroxylation of AAF was increased sixfold to sevenfold after MCA treatment; aryl hydrocarbon hydroxylase was similarly increased in both liver and lung. The hepatic cytochrome P450 content was increased by 50%, and the Soret maximum in the CO-hemoprotein complex was shifted to the blue by 2 nm after MCA induction. Electrophoresis of hepatic microsomes from MCA-treated monkeys showed an increase in a polypeptide band of 54,000 molecular weight. Mutagenic activation of AAF by liver microsomes from untreated rhesus monkeys was low but was increased 40-fold after MCA treatment. No effect was observed on the mutagenic activation of N-hydroxy-2-acetylaminofluorene by liver microsomes after MCA treatment. Rhesus monkeys may provide a model for evaluation of the role of polycyclic hydrocarbon induction in chemically caused cancer and toxicity in primates.
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Forty-nine powdered herbal drugs were analyzed for their mold profile and for the potential presence of three mycotoxins (aflatoxin, sterigmatocystin, ochratoxin A). Aspergillus and Penicillium species were predominant, but Rhizopus, Mucor, Cladosporium, and Aureobasidium spp. were also found in a few samples. Mycotoxins were not detected in any samples, and only one isolated culture was found to be a mycotoxin producer on laboratory media.
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The development of prolactin receptors in the mammary gland after ovariectomy was investigated in pregnant KA mice. Mice were ovariectomized on day 13 of pregnancy and used for the determination of the amount of specific binding of 125I-labelled prolactin to the mammary tissue, and the contents of lactose and nucleic acids in the mammary gland 0, 8, 24, and 72 hr after the operation. The specific binding of 125I-labelled prolactin, lactose and RNA contents in the mammary gland remained low until 8 hr, sharply increased 24 hr and decreased 72 hr after ovariectomy. When ovariectomized mice were treated with 0.2 mg progesterone, pregnancy was maintained and an increase (1.5-fold) in the amount of specific binding was observed with an increase of lactose content. Five mg progesterone completely inhibited lactose synthesis. Cortisol administered with progesterone did not show any specific change at the dose used (0.5 to 10 mg). Although the amount of specific binding was also increased after hysterectomy, this increase (2-fold) did not fully cover the increase after ovariectomy (3-fold). These results suggest that the recepter site for prolactin is induced before the initiation of lactose synthesis caused by ovariectomy during pregnancy.
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Lymphocyte function was examined in Wegener's granulomatosis patients and the following results were obtained. 1) The T and B lymphocyte subpopulation was within the normal range. 2) Lymphocyte blast formation was examined with the use of PHA-P, Con A or TAP (tuberculin active peptide). A decrease in responsiveness against TAP was found in four out of ten patients, but no decrease was observed in responsiveness agains Con A or PHA-P. 3) Skin tests were carried out on seven patients with six different antigens. In two out of seven patients, the skin reactions were decreased against all the antigens used. In the other five patients, skin reactions were observed against only one or two of the antigens used. These results suggest that Wegener's granulomatosis may be associated with a partial deficiency in the cellular immune mechanism.
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