Biomedical subjects

R L Barbieri

Publications and source records attributed to R L Barbieri.

14 recordsLinked to original sources

PubMed1992

Hormone treatment of endometriosis: the estrogen threshold hypothesis.

In women with recurrent pelvic pain caused by endometriosis, hormonal therapy with a gonadotropin-releasing hormone agonist is an effective alternative to surgical therapy. The basis for medical treatment of endometriosis is that endometriosis lesions are dependent on estradiol for continued growth. Further, end organ tissue varies in its sensitivity to estradiol. This forms the basis of the estrogen threshold hypothesis, that is, that a concentration of estradiol that will partially prevent bone loss may not stimulate endometrial growth. Thus there is a hierarchy of organ response to estradiol such that calcium metabolism is most sensitive followed by gonadotropin secretion, vaginal epithelial growth, lipid metabolism, and liver protein production. Similarly, breast cancer is most sensitive and endometriosis is least sensitive to estrogen. These differences may allow the design of regimens with a gonadotropin-releasing hormone agonist that maintain a therapeutic response and ameliorate potential adverse effects.

Bone Density↗

PubMed1992

Human ovarian 17-ketosteroid oxidoreductase: unique characteristics of the granulosa-luteal cell and stromal enzyme.

OBJECTIVES: We attempted to test the hypothesis that distinct forms of the 17-ketosteroid oxidoreductase exist in the human ovary and to compare its activity in stroma obtained from normally cycling women and from hyperandrogenic women. STUDY DESIGN: Human ovarian granulosa-luteal cell and stromal 17-ketosteroid oxidoreductase were examined in cell incubations and subcellular homogenates. RESULTS: In subcellular homogenates of granulosa-luteal cells 17-ketosteroid oxidoreductase activity was greater in the cytosol fraction than in the membrane fraction. In contrast, in homogenates of both ovarian stroma and Leydig cells its activity was greater in the membrane fraction than in the cytosol fraction. At the substrate concentrations used estrone was a better substrate than androstenedione for the granulosa-luteal cell 17-ketosteroid oxidoreductase. In contrast, androstenedione was a better substrate than estrone for that in ovarian stromal and Leydig cell membranes. In incubations of ovarian stroma from hyperandrogenic women, significantly more testosterone accumulated in the medium per milligram of tissue than in the medium of incubations of ovarian stroma from normally cycling women (142 +/- 48 vs 7.9 +/- 7.5 pg testosterone per milligram of tissue per 48 hours, mean +/- SD, p less than 0.05). The ratio of testosterone to androstenedione was significantly higher in the medium of incubations of ovarian stroma from hyperandrogenic women than in that from normally cycling women (0.61 vs 0.25, mean, p less than 0.05). The ratio of serum testosterone to androstenedione was significantly greater in hyperandrogenic women than in normally cycling control women (0.31 +/- 0.11 vs 0.20 +/- 0.03, mean +/- SD, p less than 0.05). CONCLUSION: The localization (cytosol fraction) and substrate specificity (estrone) of the granulosa-luteal cell 17-ketosteroid oxidoreductase enzyme resembles that seen in human placenta. The localization (membrane fraction) and substrate specificity (androstenedione) of the ovarian stromal 17-ketosteroid oxidoreductase enzyme resembles that seen in Leydig cells. It may be one enzyme that exists in multiple forms or it may be two (or more) enzymes. In some hyperandrogenic women the ovarian stromal 17-ketosteroid oxidoreductase may be more active than in normally cycling women, contributing to an abnormally increased testosterone production rate.

17-Hydroxysteroid Dehydrogenases↗

PubMed1992

Directionality of menstrual flow: cervical os diameter as a determinant of retrograde menstruation.

OBJECTIVE: To develop a mathematical model to examine the factors that control the directionality of menstrual flow. DESIGN: The model consisted of a rigid cavity, filled with a viscous liquid, with three outflow ports: a set of paired outflow ports (fallopian tube ostia) and an additional single outflow port (cervical os). The Darcy-Weisbach equation was used to calculate flow rates through the ports. RESULTS: At cervical os diameters of less than 0.5 mm, more than 50% of flow was through the fallopian tubes over a wide range of values for cervical length and fallopian tube ostia diameter and length. The diameter of the fallopian tube ostia was also an important determinant of the directionality of flow. The lengths of the cervical os and fallopian tube ostia were of secondary importance in determining directionality of menstrual flow. CONCLUSION: If retrograde menstruation is a risk factor for the development of endometriosis, menstruating women with cervical os diameters less than 2.0 mm may be at increased risk for developing endometriosis.

Biomechanical Phenomena↗

PubMed1992

Effects of age, smoking and vitamins on plasma DHEAS levels: a cross-sectional study in men.

In recent years, relationships of dehydroepiandrosterone and its sulfate ester dehydroepiandrosterone sulfate (DHEAS) with decreased risks of cardiovascular disease as well as a possible role in the aging process have been postulated. To explore the effects of cigarette smoking, a risk factor for cardiovascular disease, as well as age, on the levels of these adrenal androgens, we measured plasma levels of DHEAS in 543 healthy male subjects from the Physicians' Health Study. Blood specimens were collected between August 1982 and December 1984 and stored at -80 C. The overall mean DHEAS level was 3.47 mumol/L (+/- 2.12 SD). DHEAS levels were positively correlated with smoking habits (r = +0.16, P = 0.0002); current smokers had the highest age-adjusted DHEAS concentrations (4.27 mumol/L, P = 0.0005 compared with never smokers), followed by past smokers (3.47 mumol/L, P = 0.02) and never smokers (3.10 mumol/L). A marked linear decline of levels with age was observed, with an average decrease of 3% per year. These data suggest a moderate direct association with cigarette smoking and a powerful influence of age on decreasing levels of DHEAS. After adjusting for age and smoking habits, DHEAS concentrations were also inversely correlated with reported use of multivitamins (r = -0.16, P = 0.0002) and positively correlated with plasma retinol levels (r = 0.14, P = 0.002).

Adult↗

PubMed1992

Hyperandrogenism: new insights into etiology, diagnosis, and therapy.

Mutations in the genes for the insulin receptor, 21-hydroxylase, 11 beta-hydroxylase, and 3 beta-hydroxysteroid dehydrogenase isomerase enzymes are associated with hyperandrogenism. These genetic causes of hyperandrogenism account for less than 10% of all cases. A major goal of future research will be to identify other genetic causes of hyperandrogenism. Evidence continues to accumulate that luteinizing hormone, insulin-like growth factor I, and insulin are major factors regulating ovarian androgen production. Optimal therapy for hyperandrogenism probably includes simultaneous suppression of androgen production and blockade of androgen action.

3-Hydroxysteroid Dehydrogenases↗

PubMed1992

Menstrual cyclicity of CA-125 in patients with endometriosis.

OBJECTIVE: To examine the serum levels of CA-125 in the menstrual, follicular, and luteal phases of the menstrual cycle in women with endometriosis and to determine if serum CA-125 levels drawn during menses improve the clinical utility of the test in diagnosing endometriosis. DESIGN: Serum CA-125 was measured in the menstrual, follicular, and luteal phases of the cycle preceding surgery. CA-125 levels for each phase were categorized by postoperative diagnosis and endometriosis stage. SETTING: The reproductive endocrine unit of a tertiary care university-affiliated hospital. PATIENTS: A total of 65 patients were recruited from the Fertility and Endocrine Unit and the Gynecology Service of Brigham and Women's Hospital. MAIN OUTCOME MEASURE: Serum CA-125 levels were measured by an immunoradiometric assay and were stratified by menstrual cycle phase, diagnosis, and stage of endometriosis. The menstrual cycle phase was confirmed by serum estradiol and progesterone measurements. RESULTS: Serum CA-125 levels in patients with stages II to IV endometriosis were significantly elevated in the menstrual phase compared with levels drawn in the nonmenstrual follicular and luteal phases. The sensitivity and specificity of CA-125 for the diagnosis of endometriosis were not significantly better in the menstrual than in the follicular or luteal phases. CONCLUSIONS: Despite menstrual cyclicity of CA-125, measurement of serum CA-125 during menses does not improve the clinical utility of the test in the diagnosis of endometriosis.

Antigens, Tumor-Associated, Carbohydrate↗

PubMed1991

Effects of growth hormone administration on dehydroepiandrosterone sulphate, androstenedione, testosterone and cortisol metabolism during nutritional repletion.

This study evaluated whether pharmacological doses of recombinant human growth hormone (hGH) influences androgen or cortisol metabolism during nutritional repletion following prolonged illness. Stable hospitalized adults (three males, seven female) receiving constant calorie and protein intake were studied. An initial control week was followed by a treatment period during which hGH (10 mg/day s.c.) was administered daily. Prior to hGH treatment, serum and 24-h urinary concentrations of dehydroepiandrosterone sulphate (DS) were below the normal range; serum androstenedione and testosterone concentrations were within the lower limit of normal. In contrast, serum cortisol (F) and 24-h urinary F excretion were normal. During hGH treatment, nitrogen balance became positive and plasma insulin-like growth factor I (IGF-I) concentrations rose five to seven-fold. However, serum DS, androstenedione, testosterone and F, and urinary F excretion did not change, while 24-h urinary DS excretion fell significantly. Growth hormone administration markedly stimulated protein anabolism but did not increase the low concentrations of circulating androgens or alter the disassociation between adrenal androgen and F release in stable hospitalized males and females. Thus, hGH does not appear to function as a cortical adrenal androgen stimulating hormone (CASH) or regulate adrenal cortisol or gonadal androgen release in this clinical setting.

Adrenal Cortex↗

PubMed1991

Overall body fat and regional fat distribution in young women: quantification with MR imaging.

Overall body fat and its distribution in different regions are important predispositions to known aberrations in lipid and glucose metabolism. The accuracy of MR imaging in estimating overall body fatness and regional fat distribution at individual landmarks was determined by comparing it with well-accepted measures by deuterium-oxide (D2O) dilution and bioimpedance analysis. Fourteen normal young women (athletes and control subjects) were studied. A total of 308 axial, T1-weighted, spin-echo MR images over a specific region in the trunk (21-24 scans per subject) were obtained. Morphometric computer image analysis was performed to determine the subcutaneous, internal, and total fat volumes in each image. The data were analyzed in two ways: data from all slices were summed to assess overall body fatness, and six anatomic landmarks were chosen for regional comparisons. MR-determined estimates of overall body fatness strongly correlated with total body fat measures by D2O dilution in both total fat (r = .91) and subcutaneous fat (r = .92) determinations. Athletes in both the low- and high-intensity training phases had significantly lower values of MR-determined total body fatness than did control subjects. Parallel to total body fatness, athletes had significantly lower MR-determined ratios of total fat/total volume in four of six individual landmarks compared with control subjects. Our experience suggests that MR is an accurate method to quantify overall body fatness, when compared with D2O dilution and bioimpedance analysis. MR could also discriminate regional components of subcutaneous and internal body fat at individual landmarks.

Adipose Tissue↗

PubMed1991

Hyperandrogenism: new insights into diagnosis and therapy.

Many different disease processes can result in a phenotype of hirsutism, anovulation, and oligomenorrhea or amenorrhea. An important goal of reproductive endocrinologists is to identify specific genetic diseases that can produce the hyperandrogenic phenotype. Two genetic disorders that can result in the hyperandrogenic phenotype are 1) mutations in the 21-hydroxylase gene (adrenal hyperplasia), and 2) mutations in the insulin receptor gene (the syndrome of hyperandrogenism-insulin resistance and acanthosis nigricans). The identification of these two genetic causes of hyperandrogenism provides the opportunity to investigate new approaches to prenatal diagnosis and therapy, genetic analysis of pedigrees, and innovative forms of therapy.

Acanthosis Nigricans↗

PubMed1979

Danazol binding to rat androgen, glucocorticoid, progesterone, and estrogen receptors: correlation with biologic activity.

Danazol was found to possess androgenic and glucocorticoid activity in rat bioassays. In contrast, danazol displayed no significant estrogenic activity. In support of these findings, danazol bound to the 8 S androgen receptor of rat prostate cytosol and to the glucocorticoid receptor of rat liver cytosol, but danazol did not bind well to the estrogen receptor of the rat uterus. Finally, danazol bound to the progesterone receptor of the rat uterus, but controversy continues as the whether danazol possesses progestational, antiprogestational, or no progestational effects.

Animals↗

PubMed1978

Estrogen 2-hydroxylase: activity in rat tissues.

Incubation parameters for a radioderivative assay for estrogen 2-hydroxylase have been examined. The assay was found to be specific and sensitive if a chromatographically purified preparation of COMT was used. Estradiol was found to be a better substrate for the 2-hydroxylase than estrone or estriol. The liver had significantly higher estrogen 2-hydroxylase activity than any other tissue examined. The estrogen 2-hydroxylase was highly localized in the microsomal fraction in both the liver and the brain. The male rat was found to have significantly more estrogen 2-hydroxylase activity in the liver than the female rat. In addition, in the male rat liver, the estrogen 2-hydroxylase activity was reversibly inducible by testosterone and was not affected by phenobarbital. In the male and female rat brain the estrogen 2-hydroxylase activities were similar.

Animals↗

PubMed1978

Pituitary gonadotropin responsiveness with danazol.

Danazol (17alpha-pregn-4-en-20-yno-[2,3-d]isoxazol-17-ol) was administered daily for 4 days to castrated female rats. As previously demonstrated, danazol lowered serum levels of luteinizing hormone (LH) in an apparent dose-dependent fashion. Animals which received danazol in a dose sufficient to lower serum LH responded to administered LH-releasing hormone (LHRH) with increases in serum LH levels which were not diminished as compared with those of control animals. Although these experiments do not preclude an effect of danazol directly on the pituitary, the results indicate that this agent probably lowers serum LH primarily by inhibition of hypothalamic LHRH secretion.

Animals↗

PubMed1977

Danazol inhibits steroidogenesis in the rat testis in vitro.

The effects of danazol on steroidogenesis in vitro in the rat testis were examined by studying: 1) androgen synthesis in rat Leydig cells cultured with danazol, 2) danazol binding to rat testis microsomal cytochrome P-450, and 3) enzyme kinetics of danazol inhibition of the microsomal enzymes of testicular steroidogenesis. Concentrations of danazol as low as 1 micrometer suppressed LH-stimulated testosterone and androstenedione production in cultured Leydig cells. The addition of danazol to a preparation of testicular microsomes elicited a type I cytochrome P-450 binding spectrum, with an apparent spectral dissociation constant (Ks) of 4.8 micrometer. Danazol inhibited progesterone and 17alpha-hydroxy-progesterone binding to microsomal P-450 with apparent spectral inhibition constants of 2.4 micrometer and 2.8 micrometer, respectively. Danazol competitively inhibited 3beta-hydroxy-delta5-steroid dehydrogenase-isomerase (apparent enzymatic inhibition constant, KI = 5.8 micrometer), 17alpha-hydroxylase (KI = 2.4 micrometer), 17,20 lyase (KI = 1.9 micrometer), and 17beta-hydroxysteroid dehydrogenase (KI = 4.4 micrometer). These findings indicate that low concentrations of danazol directly inhibit steroidogenesis in the rat testis in vitro.

Androgens↗

PubMed1977

Danazol inhibits steroidogenesis.

Danazol was found to inhibit multiple enzymes of steroidogenesis directly in the pregnant mare serum (PMS)-treated hamster ovary and the rat testis and adrenal in vitro. In the PMS-treated hamster ovary, danazol inhibited 17alpha-hydroxylase, 17,20-lyase, and 3beta-hydroxysteroid dehydrogenase. In the rat testis, danazol inhibited 17alpha-hydroxylase, 17,20-lyase, 3beta-hydroxysteroid dehydrogenase, and 17beta-hydroxysteroid dehydrogenase. In the rat adrenal, danazol inhibited 3beta-hydroxysteroid dehydrogenase, 21-hydroxylase, and 11beta-hydroxylase. Two hours after a subcutaneous injection of 5 mg/kg of danazol to adult male rats, serum luteinizing hormone levels were significantly increased and serum testosterone levels were significantly suppressed. These findings suggest that in the rodent one of danazol's major pharmacologic effects is the direct inhibition of steroidogenesis.

Adrenal Glands↗