Biomedical subjects

F Stanczyk

Publications and source records attributed to F Stanczyk.

8 recordsLinked to original sources

PubMed1998

Role of calciotrophic hormones in calcium mobilization of lactation.

The postpartum period can be a time when profound changes in calcium metabolism and bone mineral density (BMD) occur, particularly in association with lactation. We investigated the hypothesis that calciotrophic hormones [1,25-dihydroxyvitamin D, 25-hydroxyvitamin D, and parathyroid hormone (PTH)] are different by lactation practice or hormone status [PTH-related peptide (PTHrP), estradiol, and prolactin] and have a potential role in the bone loss and recovery associated with lactation. 1,25-Dihydroxyvitamin D, 25-hydroxyvitamin D, PTH, femoral BMD, PTHrP, prolactin, estradiol, and bone turnover markers were measured at 2 wk and at 2, 4, 6, 12, and 18 mo postparturition in 115 postpartum women aged 20-40 y (parity: 0-1). Lumbar spine BMD was measured at 2 wk and at 6, 12, and 18 mo during the postpartum period. PTH, 1,25-dihydroxyvitamin D, and 25-hydroxyvitamin D concentrations were nonlinear across the 18-mo postpartum period. Between baseline and 18 mo postparturition, PTH and 1,25-dihydroxyvitamin D concentrations did not decline, while there was a substantial decline in 25-hydroxyvitamin D concentrations. PTH, 1,25-dihydroxyvitamin D, and 25-hydroxyvitamin D concentrations did not differ by lactation practice or by PTHrP, estradiol, or prolactin status. These classic calciotrophic hormones were not associated with concentrations of bone turnover markers or changes in BMD in lactating women. In summary, patterns of change in calciotrophic hormones (PTH, 1,25-dihydroxyvitamin D, and 25-hydroxyvitamin D) in the 18-mo postpartum period appeared to be independent of PTHrP, estradiol, prolactin, or lactation status and were not associated with bone turnover markers. These data do not support the hypothesis that these three calciotrophic hormones are a central part of the calcium mobilization associated with the bone loss of lactation.

Adult↗

PubMed1997

Single-dose pharmacokinetics of sublingual versus oral administration of micronized 17 beta-estradiol.

OBJECTIVE: To investigate the pharmacokinetic profiles of different doses of micronized 17 beta-estradiol administered by oral or sublingual routes. METHODS: Single doses of micronized 17 beta-estradiol were administered orally (1 mg, 0.5 mg) or sublingually (1 mg, 0.5 mg, 0.25 mg) to six postmenopausal women in a randomized clinical trial. We calculated pharmacokinetic parameters for estradiol (E2) and estrone (E1) of maximum serum concentration, time to maximum serum concentration, terminal half-life, area under the concentration curve, and oral clearance. Serum levels of E1 sulfate also were compared at 4, 12, and 24 hours after dosing. RESULTS: Sublingual administration resulted in rapid absorption with significantly higher E2 levels than did comparable oral dosing. Estrone levels did not vary with route of administration but correlated with the dosage administered. Estrone sulfate levels correlated with the dosage administered and also tended to be higher with sublingual administration. Sublingual administration resulted in a significantly lower E1 to E2 ratio during the 24 hours than did oral administration. CONCLUSION: Sublingual administration of micronized 17 beta-estradiol results in a rapid, burst-like absorption into the systemic circulation, yielding high E2 levels that fall rapidly over the first 6 hours.

Administration, Oral↗

PubMed1997

Medroxyprogesterone interferes with ovarian steroid protection against coronary vasospasm.

Cardiovascular disease, the major cause of death in post-menopausal women, can be reduced by replacement of ovarian steroid hormones. To compare medroxyprogesterone with progesterone as the progestin in hormone replacement therapy from the standpoint of coronary artery vasospasm, we treated ovariectomized rhesus monkeys with physiological levels of estradiol-17 beta in combination with medroxyprogesterone or progesterone for four weeks. Coronary vasospasm in response to pathophysiological stimulation without injury showed that progesterone plus estradiol protected but medroxyprogesterone plus estradiol failed to protect, allowing vasospasm. We conclude that medroxyprogesterone in contrast to progesterone increases the risk of coronary vasospasm.

Animals↗

PubMed1997

Prostate-specific antigen in female serum, a potential new marker of androgen excess.

Prostate-specific antigen (PSA) is present at very low concentrations in female serum, but it can now be measured with highly sensitive immunoassays. We have found that in female tissues the PSA gene is regulated by steroid hormones through the action of steroid hormone receptors. Thus, we examined whether female serum PSA is associated with hyperandrogenic states. Serum PSA levels were compared between 22 hirsute women with a Ferriman-Gallwey score higher than 8 and 50 women without hirsutism. The results show that PSA levels were higher in hirsute women in comparison with controls. In hirsute women, levels of PSA and 3 alpha-androstanediol glucuronide (3 alpha-AG), a specific metabolite of androgen action, showed a significant positive correlation, whereas PSA and 3 alpha-AG showed a significant negative correlation with patient age. Receiver operating characteristic (ROC) analysis revealed that 3 alpha-AG was a slightly better marker of androgen excess than PSA. We conclude that female serum PSA may be a new biochemical marker of androgen action in females.

Adolescent↗

PubMed1996

Elevated parathyroid hormone-related peptide associated with lactation and bone density loss.

OBJECTIVE: To investigate the hypothesis that parathyroid hormone-related peptide (PRHrP) may be involved with bone loss and recovery as a means of providing adequate calcium and phosphate to infants. DESIGN: An 18-month prospective cohort study. SETTING: General community setting with recruitment occurring at birthing education classes. PARTICIPANTS: Volunteer sample of 115 postpartum healthy women aged 20 to 40 years, and 0 or 1 parity prior to parturition with no intent to breast-feed or intent to breast-feed at least 6 months. MAIN OUTCOME MEASURES: Parathyroid hormone-related peptide, prolactin, estradiol, 1,25-dihydroxyvitamin D, 24-hydroxyvitamin D, femoral bone mineral density, and bone turnover markers were measured in 115 postpartum women at 2 weeks, 2 months, 4 months, 6 months, 12 months, and 18 months postpartum. Lumbar bone mineral density was measured at 2 weeks, 6 months, 12 months, and 18 months postpartum. RESULTS: Elevated PTHrP values were significantly associated (P<.001) with breast-feeding status, elevated prolactin levels, and lower serum estradiol levels, conditions occurring during lactation. Furthermore, elevated PTHrP levels were negatively and significantly associated (P<.01) over time with bone mineral density change at both the spine and the femoral neck, even after accounting for prolactin levels, breast-feeding status, return of menstruation, estradiol levels, PTH levels, 1,25-dihydroxyvitamin D levels, dietary calcium intake, physical activity, and body size. CONCLUSION: These data clearly support the hypothesis that PTHrP is an alternative mechanism associated with bone loss and recovery during and subsequent to lactation.

Absorptiometry, Photon↗

PubMed1990

Serum hormone levels in pre-menopausal Chinese women in Shanghai and white women in Los Angeles: results from two breast cancer case-control studies.

To assess whether risk of breast cancer in young women is associated with differences in luteal-phase hormone production and to attempt to explain differences in risk of breast cancer of young Shanghai Chinese and Los Angeles white women, two concurrent case-control studies of serum hormone concentrations were conducted. Both studies were carefully controlled for the possible confounding effects of age, weight, height, pregnancy history, and day of the menstrual cycle, by individually matching cases and controls on these factors. Case eligibility was limited to women with localized breast cancer. Sixteen of 39 Shanghai breast-cancer cases were sampled prior to the histologic diagnosis of their disease. The remaining 23 Shanghai cases and all 42 Los Angeles cases were diagnosed, and treated by surgery only, at least six months prior to hormonal evaluation. All subjects were sampled on day 22 of the menstrual cycle. Overall, cases had 13.5% higher serum estradiol concentrations (p = 0.038) with a case-to-control excess of 16.6% in Shanghai subjects (p = 0.089) and 10.8% in Los Angeles subjects (p = 0.23). There were no appreciable differences in amounts of sex-hormone binding globulin between cases and controls. Cases had lower progesterone levels than controls, but the situation was reversed when the analysis was restricted to subjects with evidence of ovulation. Los Angeles controls had 20.6% greater estradiol concentrations than Shanghai controls (p = 0.036); adjustment for body weight accounted for only 25.7% of this difference.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1987

Melatonin: data consistent with a role in controlling ovarian function.

FSH and LH excretion were correlated with melatonin excretion in consecutive daily urines obtained from a normal adult female (27 days), a normal 11-year-old girl (28 days), and an 8-year-old girl with idiopathic sexual precocity (30 days). Additionally pregnanediol-3-glucuronide (PG) excretion was determined in the urines of the adult female. Gonadotropin and PG excretion patterns of the adult female were those associated with a normal menstrual cycle. Excretion of melatonin, mean +/- SD, (11.3 +/- 2.7 vs 4.7 +/- 1.4 ng/h, p less than 0.005) was greater and PG (38.3 +/- 81 vs 124.2 +/- 46.7 ug/h, p less than 0.005) was less during the first 13 days as compared to the subsequent 14 days. Gonadotropin and melatonin excretions correlated positively (first 13 days FSH, r = 0.828; rs = 0.815 and LH, r = 0.816; rs = 0.905, p less than 0.005 and subsequent 14 days FSH, r = 0.607; rs = 0.685, p less than 0.025 and LH, r = 0.490, p less than 0.05; rs = 0.638, p less than 0.025). Excretion of PG and melatonin did not correlate during the first 13 days. However, during the subsequent 14 days they correlated negatively (r = -0.679, p less than 0.005; rs = -0.620, p less than 0.025). During the 28-day period the gonadotropin and melatonin excretion patterns of the 11-year-old girl showed random fluctuations and correlated positively (FSH, r = 0.669; rs = 0.631 and LH, r = 0.690; rs = 0.695, p less than 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1980

Clinical and endocrinologic study of continuous levonorgestrel administration from subcutaneous solid polydimethylsiloxane rods.

Three solid polydimethylsiloxane (Silastic) rods containing levonorgestrel were inserted into the subcutaneous tissue of the volar aspect of the forearm of 8 women. Serum samples were drawn three times a week for 2 months and weekly thereafter for 2 years in 3 of the subjects. The other subjects had serum drawn during the twelfth and last treatment months. Levonorgestrel, estradiol and progesterone were measured in all samples. The subject kept a bleeding record. In comparison to an earlier clinical trial in which 6 hollow capsules of Silastic filled with levonorgestrel were used, the 3 solid levonorgestrel-containing rods provided higher serum levels of levonorgestrel, fewer serum estradiol peaks, only a single episode of ovulation and better bleeding performance.

Adult↗