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At least 181 records · Page 10Linked to original sources
PubMed1979

Inhibition of peripheral aromatization of androstenedione to estrone in postmenopausal women with breast cancer using delta 1-testololactone.

To determine if delta 1-testololactone can inhibit the peripheral aromatization of androstenedione (delta), nine postmenopausal women with metastatic breast cancer were studied before and after 2 weeks of therapy with 250 mg of the drug, given every 6 h by mouth. The conversion ratio of delta to estrone (E1) was significantly reduced (P less than 0.005) from a mean (+/-SE) of 0.0098 +/- 0.0025 before to 0.0009 +/- 0.0005 after treatment. The drug's effect on the metabolism of delta seemed to be specific since significant changes in the MCR of delta and in the conversion ratio to testosterone were not observed. That this inhibition of peripheral aromatization had an effect on E1 metabolism was shown by the significant decrease (P less than 0.01) of mean serum E1 levels from 22 +/- 3 pg/ml before to 12 +/- 1 pg/ml after treatment. Serum estradiol levels rose slightly from 8 +/- 0.8 to 12 +/- 4 pg/ml. Serum delta and testosterone levels were unchanged by therapy. These data are consistent with the concept that delta 1-testololactone is a potent inhibitor of peripheral aromatization of delta to E1. This mechanism could explain the antitumor properties of this compound.

Aged↗
PubMed1983

Biological significance of aromatase activity in human breast tumors.

Human breast carcinomas contain aromatase, the enzyme necessary for the conversion of androgens to estrogens. If present in sufficient amounts, aromatase could catalyze the synthesis of estrogens from plasma steroid precursors and produce high breast cancer tissue concentrations. To determine the biological importance of tumor aromatase, we validated a specific and highly sensitive 3H-labeled water release assay for aromatase and used this to quantitate the amount of estrogen synthesized in vitro in breast tumors. As proof of assay validity, the [3H] water release assay detected 22.7 +/- 0.09 (+/- SEM) pmol/g . h estrogen formed vs. 24.7 pmol/g . h with the direct product isolation assay. Of 61 human breast tumors studied, 48 contained measurable aromatase activity, ranging from 5-70.5 pmol estrone formed/g . h. Three aromatase inhibitors (aminoglutethimide, testololactone, and 4-hydroxyandrostenedione) blocked this activity at concentrations similar to those affecting aromatase activity in other tissues. If biologically important, the estrogen formed locally from aromatase would be expected to stimulate production of the progesterone receptor. Under these circumstances, a positive correlation of progesterone receptor and local estrogen production should be found. In contrast, no significant correlation between aromatase activity and progesterone receptor level was observed (r = -0.27; P = NS). In addition, no correlation between estrogen receptor content and aromatase activity was detected. Finally, the amount of aromatase activity present in most tumors was insufficient to produce biologically meaningful saturation of estrogen receptors. These observations suggested that aromatase, while present in the majority of breast cancer tissues, may only be biologically important in those few tumors with very high aromatase activity.

Aminoglutethimide↗
PubMed2006

Heritability of testosterone levels in 12-year-old twins and its relation to pubertal development.

The aim of this study was to estimate the heritability of variation in testosterone levels in 12-year-old children, and to explore the overlap in genetic and environmental influences on circulating testosterone levels and androgen-dependent pubertal development. Midday salivary testosterone samples were collected on 2 consecutive days in a sample of 183 unselected twin pairs. Androgen-induced pubertal development was assessed using self-report Tanner scales of pubic hair development (boys and girls) and genital development (boys). A significant contribution of genetic effects to the variance in testosterone levels was found. Heritability was approximately 50% in both boys and girls. The remaining proportion of the variance in testosterone levels could be explained by nonshared environmental influences. The relatively high correlation between testosterone levels of opposite-sex dizygotic twins suggests that sex differences in genes influencing variation in testosterone levels have not yet developed in pre- and early puberty. Variance in pubertal development was explained by a large genetic component, moderate shared environmental influences, and a small nonshared environmental effect. Testosterone levels correlated moderately (r = .31) with pubertal development; the covariance between testosterone levels and pubertal development was entirely accounted for by genetic influences.

Child↗
PubMedDate not supplied

A boy with McCune-Albright syndrome associated with GH secreting pituitary microadenoma. Clinical findings and response to treatment.

The McCune-Albright Syndrome (MAS) is a sporadic rare disease first described in 1936 by McCune and separately by Albright. MAS is characterized by a triad of physical signs: café-au-lait spots, polyostotic fibrous dysplasia and autonomous endocrine hyperfunction. MAS is predominantly observed in girls and is rarely reported in males. We report the case of a 9-year old boy with gonadotropin independent precocious puberty, café-au-lait spots, polyostotic fibrous dysplasia and growth hormone hypersecretion.

Adenoma↗
PubMed1987

[The inhibitory effect of miconazole on aromatase activity for androstenedione in human placental and ovarian preparations].

The inhibitory effects of miconazole, an antimycotic agent, on aromatase activity for androstenedione in human placenta (105,000 X g pellet fraction) and ovary (800 X g supernatant fraction) were investigated. Various concentrations (0.1-100 microM) of miconazole, aminoglutethimide or delta 1-testololactone were added to the human placental preparation (1 mg protein) and then the mixture was incubated with [1 beta-3 H]-androstenedione (300 pmol) and NADPH (0.5 mg), at 37 degrees C for 30 minutes in air. The reaction was stopped by 10%-trichloroacetic acid (0.8 ml) and the mixture was extracted with chloroform (3 ml). The residual aqueous phase was subjected to Amberlite XAD-II resin-charcoal column chromatography. The amount of 3H2O obtained was regarded as aromatase activity for androstenedione. The effects of miconazole on aromatase activity in human ovarian preparation was also investigated. Aromatase activity in human placenta was suppressed concentration-dependently by miconazole. The inhibition of aromatase activity by miconazole was significantly higher than that by aminoglutethimide and delta 1-testololactone. The I50 values for the inhibition of aromatase activity by miconazole, aminoglutethimide and delta 1-testololactone were 0.60 microM, 15 microM and 34 microM, respectively. The apparent Km value for androstenedione was 320 nM and the apparent Ki value was 120 nM in this assay. The inhibition of aromatase by miconazole in human ovary was also significantly higher than that by aminoglutethimide (I50 value for miconazole = 0.98 microM; I50 value for delta 1-testololactone = 15 microM). These results indicate that miconazole suppresses aromatase activity for androstenedione reversibly in human placenta and ovaries in vitro.

Aminoglutethimide↗
PubMed1981

Direct evidence in men for a role of endogenous oestrogens on gonadotrophin release.

In six healthy subjects serum oestradiol was selectively decreased by administering an aromatase activity inhibitor, hydrotestolactone (HT). After HT administration serum oestradiol (Oe2) decreased from 18.7 +/- 2.3 (SEM) to 6.7 +/- 0.6 pg/ml whereas testosterone (T) and dihydrotestosterone (DHT) blood levels were not modified. These oestradiol changes were associated with a significant increase in serum LH and FSH concentrations (P less than 0.001). The administration of tamoxifen, an oestrogen antagonist, to 5 subjects caused a sharp increase in LH and FSH levels (P less than 0.001). Oe2 was unchanged after the treatment with tamoxifen, whereas T levels were significantly higher. The sum of these data suggests that oestradiol under physiological conditions plays a specific role in the feedback mechanism of gonadotrophin release.

Adolescent↗
PubMed2006

[Testotoxicosis].

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Aromatase Inhibitors↗
PubMed1986

[New developments in the treatment of oligozoospermia].

New developments in the treatment of oligozoospermia are discussed and critically considered. In particular, the necessity of performing double blind studies to test the efficacy of a drug is stressed. Generally, there is a great need for clinically orientated basic research in andrology since new approaches to scientifically orientated therapy are only possible if our current knowledge on physiology and pathophysiology of male reproductive functions is improved. In addition, a rational therapy can only be performed if sufficient selection criteria are available. The variety of new therapeutic means indicate that in the near future different approaches will be investigated to improve the success of andrological treatment, thus rendering therapy more effective for patients and doctors.

Double-Blind Method↗