The value of experience and practice in the routine biochemical analysis of steroid receptors was studied in 2576 different primary breast cancer specimens over five consecutive years. The positivity rate (beyond 3 fm/protein) and the measured concentrations of the steroid receptors increase. The positivity rate and average steroid receptor concentration of the samples immediately frozen is significantly higher compared to the overall sample population. It is concluded that the handling of the specimen before freezing and the experience of the technician play an important role in the routine biochemical analysis of steroid receptors.

Breast Neoplasms↗

PubMedDate not supplied

Independent regulation of growth and steroid receptors in uterus and mammary tumors of rats.

Anti-estrogens and progestagens are synergistically active in the treatment of hormone dependent tumors. The combined action of both compounds in daily treatment schedules are analyzed in rat uterus and in DMBA- induced rat mammary tumors. Tamoxifen in contrast to estradiol does not significantly affect tissue growth, while PgR induction is considerably stimulated by Tamoxifen. It is suggested that the "estrogenic effects" of Tamoxifen and estradiol are separately modulated. When given in sequential combination with anti-estrogens, the anti-tumor response of progestagens is enhanced. Combinations of hormonal treatment based on careful analysis of the regulation processes at target cell level may greatly improve results of anti-tumor therapy.

9,10-Dimethyl-1,2-benzanthracene↗

PubMedDate not supplied

Effects of daily anti-estrogen treatment on uterine growth and progesterone receptor concentrations in adult rat uterus.

The effects of daily Tamoxifen treatment on adult rat uterus weight depend on the degree of estrogenic impregnation of the animal. In intact animals, Tamoxifen caused a decrease of the uterine weight. A weight increase was observed, after castration, which was dose-dependent without reaching saturation even with 500 micrograms of Tamoxifen per day. This uterine weight increase, reaching its peak during the first 24 h after the initial Tamoxifen application, is attributable to water retention. The uterine progesterone receptor (PgR) concentrations are stimulated by daily antiestrogen treatment of intact and castrated animals. This increase in the PgR levels is initially dose-dependent up to 10 micrograms of Tamoxifen per day reaching maximal levels after 4 days of treatment. The results indicate that growth and PgR induction in adult rat uterus are essentially controlled by independent mechanisms, constituting the biological basis of the synergistic effects of anti-estrogens and progestagens.

Animals↗

PubMedDate not supplied

The interaction between different phorbol derivatives and cortisol.

Phorbol derivatives (phorbol-12,13-diacetate, phorbol-12,13-dibenzoate, phorbol-12,13-dibutyrate, and phorbol-12-myristate-13-acetate) interact with cortisol on a molecular basis. These molecular interactions are demonstrated via dexamethasone receptor assays and by changes in spectrophotometric characteristics when equimolar solutions of these phorbol compounds together with cortisol are compared to those of the pure solutions. The phorbol compounds characterized by modifications in the molecular ring structure and by substitution at position C20, lose the capacity to bind cortisol. The tumor promoting effects of phorbol compounds are apparently achieved, in addition to other well-known mechanisms, by neutralizing cortisol, thus suppressing its regulatory effect on cell proliferation.

Animals↗

PubMedDate not supplied

The effects of electric currents on ATP generation, protein synthesis, and membrane transport of rat skin.

Direct electric currents ranging from 10 microA to 1000 microA increase ATP concentrations in the tissue and stimulate amino acid incorporation into the proteins of rat skin. The amino acid transport through the cell membrane, followed by the alpha-aminoisobutyric acid uptake, is stimulated between 100 microA and 750 microA. The stimulatory effects on ATP production and on amino acid transport, apparently mediated by different mechanisms, contribute to the final increased protein synthesizing activity. DNA metabolism followed by thymidine incorporation remains unaffected during the course of current application. The effects on AtP production can be explained by proton movements on the basis of the chemiosmotic theory of Mitchell, while the transport functions are controlled by modification in the electrical gradients across the membranes.

Adenosine Triphosphate↗