Biomedical subjects

Bruce R Carr

Publications and source records attributed to Bruce R Carr.

10 recordsLinked to original sources

PubMed2003

Profiling transcript levels for steroidogenic enzymes in fetal tissues.

Cytochrome P450 (CYP) and hydroxysteroid dehydrogenase enzymes are involved in the conversion of cholesterol to steroid hormones. These enzymes are primarily expressed in the placenta, adrenal and gonads. Interestingly, some of these enzyme activities have been demonstrated in non-endocrine tissues, where they may be involved in important paracrine and autocrine actions. This is particularly the case in the human fetus where steroid precursors circulate at high levels and could be metabolized within tissues to produce active steroid hormones. Herein, we tested the hypothesis that transcripts for steroidogenic enzymes are expressed in fetal tissues other than the classical steroidogenic organs. To test this hypothesis, real-time reverse transcription polymerase chain reaction (RT-RTPCR) assays were developed that quantify mRNA levels for steroidogenic acute regulatory protein (StAR), cholesterol side-chain cleavage (CYP11A), 3beta-hydroxysteroid dehydrogenase types 1 and 2 (HSD3B1 and HSD3B2), 17alpha-hydroxylase (CYP17), 21-hydroxylase (CYP21), 11beta-hydroxylase (CYP11B1), aldosterone synthase (CYP11B2) and aromatase (CYP19). The use of RT-RTPCR allows the specific detection of these transcripts at levels that would not be detectable using northern analysis. In addition, this method can detect levels of transcript that would not lead to sufficient protein for detection of enzymatic activity of protein by western analysis. Thus, this methodology can detect low levels of expression that could play a role in regulating intra-tissue concentrations of steroid hormone. Total RNAs used for RT-RTPCR analysis were isolated from several human fetal tissues, including adrenal, testis, ovary, placenta, aorta, brain, liver, kidney, heart, lung, pancreas, prostate, stomach, and thymus. Our findings suggest that RT-RTPCR is a powerful tool for the examination of steroidogenic enzyme mRNA expressions. Using this approach, we have identified and quantified transcript levels of StAR and steroidogenic enzymes in several endocrine and non-endocrine fetal tissues. Even though some of the mRNA levels measured in these peripheral tissues are extremely lower in respect to the steroidogenic tissues, they could be sufficient to produce local (i.e. autocrine and paracrine) effects because produced steroids are not diluted into the entire circulation. These findings open new perspectives on the role of steroid hormones synthesized locally as probable regulatory factors of the development of several organ systems.

3-Hydroxysteroid Dehydrogenases↗

PubMed2003

Effects of metformin on body mass index, menstrual cyclicity, and ovulation induction in women with polycystic ovary syndrome.

OBJECTIVE: Metformin has been used as a treatment in many studies of the infertility associated with polycystic ovary syndrome (PCOS). We will review the literature on this topic as it specifically relates to changes in body mass index (BMI), improvement in menstrual cyclicity, and effects on ovulation and pregnancy rates. DESIGN: Review of studies addressing biochemical and clinical changes in women with PCOS on metformin. MAIN OUTCOME MEASURE(S): Changes in BMI, menstrual cyclicity, ovulation rate, and pregnancy rate. RESULT(S): Metformin has been shown to produce small but significant reductions in BMI. Multiple observational studies have confirmed an improvement in menstrual cyclicity with metformin therapy. The studies addressing the concomitant use of metformin with clomiphene citrate initially predicted great success, but these have been followed by more modest results. There is little data in the literature concerning the use of metformin and hMGs. CONCLUSION(S): Some (but not all) women with PCOS have improvements in their menstrual cycles while on metformin. The data supporting the use of metformin in ovulation induction with clomiphene citrate and hMG remain to be confirmed by large, randomized, prospective studies.

Body Mass Index↗

PubMed2003

Effect of gonadotropin-releasing hormone agonist and medroxyprogesterone acetate on calcium metabolism: a prospective, randomized, double-blind, placebo-controlled, crossover trial.

OBJECTIVE: The purpose of this study was to prospectively compare the effectiveness of administering medroxyprogesterone acetate (MPA; 20 mg/d) in either the first (protocol A) or last (protocol B) 12-week period as well as a 6-month course of the GnRH agonist (GnRH-a; leuprolide acetate; 1 mg/d, SC) on calcium (Ca) metabolism. DESIGN: Prospective, randomized, double-blind, placebo-controlled, crossover trial. SETTING: Clinical research center, university hospital. PATIENT(S): Twenty women were randomized into protocol A or B, received either MPA or placebo along with GnRH-a, and were then crossed over at 12 weeks to placebo or MPA, for the final 12-week interval of GnRH-a therapy. INTERVENTION(S): Collection of serum and urine samples and measurement of bone density. Sex hormone, calcitropic hormone, and bone density studies were performed at baseline and at 12 and 24 weeks. RESULT(S): In both protocol A and B, LH and E(2) levels declined by 79%-81% and 83%-90% of the baseline, respectively, at 12 and 24 weeks. Serum Ca, phosphorus, alkaline phosphatase, and osteocalcin; 2-h fasting and 24-h urinary Ca excretion; and urinary hydroxyproline levels all increased significantly during GnRH-a treatment alone. Estimated Ca balance decreased significantly during GnRH-a treatment alone. The addition of MPA attenuated the increases in phosphorus, alkaline phosphatase, osteocalcin, and 2-h fasting and 24-h urinary Ca excretion, and the decrease in estimated Ca balance. Comparison of phase order demonstrated that MPA prevented 24-h urinary Ca excretion and urinary hydroxyproline loss and decline in estimated Ca balance when it was added back during the second 12 weeks (protocol B) but not during the first 12 weeks (protocol A). CONCLUSION (S): We conclude that sequential MPA appears to reverse in part the negative effects of GnRH-a on calcitropic hormones and estimated Ca balance.

Adult↗

PubMed2003

Profiling the steroidogenic pathway in human fetal and adult adrenals.

OBJECTIVE: Gene expression clearly underlies the marked structural and functional differences between the human fetal adrenal (HFA) and adult adrenal. We thus measured expression of steroidogenic enzymes and associated cofactors in these tissues. METHODS: Real-time reverse transcriptase polymerase chain reaction was used to quantify transcripts encoding steroidogenic enzymes and the cofactors steroidogenic acute regulatory protein (StAR), cytochrome b5 (CYb5), and P450 oxidoreductase (POR). RESULTS: Cholesterol side-chain cleavage mRNA levels were 1.9-fold higher in the HFA than in the adult adrenal. Compared with a nonsignificant difference in 17alpha-hydroxylase/17,20 lyase mRNA abundance, CYb5 and POR were expressed 2.3-fold and 2.0-fold higher, respectively, in the HFA. Dehydroepiandrosterone (DHEA) sulfotransferase transcript (SULT2A1) was present at 13-fold higher levels in the HFA than the adult. 3beta-Hydroxysteroid dehydrogenase type II (HSD3B2) mRNA was 127-fold higher in the adult adrenal. StAR, 21-hydroxylase, 11beta hydroxylase, and aldosterone synthase mRNA abundance did not differ significantly. CONCLUSION: In the HFA, increased mRNA for cholesterol side-chain cleavage reflects high cholesterol utilization for steroidogenesis. Both CYb5 and POR cofactors may up-regulate 17alpha-hydroxylase/17,20 lyase activity and thus DHEA sulfate production in the HFA. High levels of SULT2A1 mRNA reflect high DHEA sulfonation in the HFA and restricted expression in the adult. Lack of HSD3B2 in the HFA facilitates DHEA synthesis. The novel finding of high levels of 21-hydroxylase and 11beta hydroxylase transcripts in the midgestational HFA merits further investigation. Thus different patterns of steroidogenic enzyme and cofactor gene expression might account for some of the phenotypic differences between the fetal and adult adrenal.

3-Hydroxysteroid Dehydrogenases↗

PubMed2003

The role of the orphan nuclear receptor, liver receptor homologue-1, in the regulation of human corpus luteum 3beta-hydroxysteroid dehydrogenase type II.

After ovulation, ovarian 3beta-hydroxysteroid dehydrogenase type II (HSD3B2) expression increases to enhance the shift of steroidogenesis toward progesterone biosynthesis. Steroidogenic factor-1 (SF-1) is a transcription factor for several genes encoding steroidogenic enzymes. However, the level of SF-1 expression decreases in the human corpus luteum (CL) after ovulation. Liver receptor homolog-1 (LRH-1) is another member of the orphan nuclear receptor family. We hypothesize that LRH-1, rather than SF-1, plays an essential role in the regulation of corpus luteum steroidogenesis. Semiquantitative RT-PCR and real-time PCR were performed to quantify the level of LRH-1 expression and correlate with HSD3B2 level. Cell transfection, mutation analysis, and EMSA were performed to examine the role of LRH-1 in the regulation of HSD3B2. LRH-1 expression was higher in CL, compared with mature ovarian follicles. Cotransfection of granulosa cells with HSD3B2 and LRH-1 resulted in a 10-fold increase of transcription. DAX-1 inhibited LRH-1-stimulated HSD3B2, which was maintained in the presence of dibutyryl cAMP. Mutation of the either of the two putative LRH-1 binding sites, which were confirmed by EMSA, in the HSD3B2 promoter decreased LRH-1 stimulation. Our findings suggest that LRH-1 is highly expressed in CL, and it plays an essential role in the regulation of HSD3B2.

3-Hydroxysteroid Dehydrogenases↗

PubMed2002

Using a low-dose contraceptive in women 35 years of age and over: 20 microg estradiol/100 microg levonorgestrel.

The efficacy, safety, and cycle control of a low-dose oral contraceptive (OC) containing 20 microg ethinyl estradiol (EE) and 100 microg levonorgestrel (LNG) has been demonstrated in a large trial with 1708 women (>or=15 years old with regular menstrual cycles). The objective of this study was to analyze the same parameters in 218 of the 1708 women who were 35 years of age and older. Women were administered the 28-day, combination OC (20 microg EE/100 microg LNG; 21 days active medication/7 days placebo) for up to 3 years. During 3859 cycles evaluated for efficacy, one pregnancy occurred (Pearl index 0.34). The most common adverse events cited as reasons for discontinuation were hypertension (3% of subjects), headache (2%), and metrorrhagia (2%). One subject withdrew as a result of a serious adverse event. Breakthrough bleeding, spotting, and bleeding and spotting occurred in 2.9%, 11.0%, and 6.8%, respectively, of the 3739 cycles evaluated for cycle control. This low-dose, monophasic regimen of 20 microg EE/100 microg LNG is an effective, safe, and tolerable contraceptive and provides good cycle control for women 35 years of age and older.

Adult↗

PubMed2002

Vaginal vault prolapse after nonsurgical and surgical treatment of MAAdullerian agenesis.

BACKGROUND: Women with Mayer-Rokitansky-Küster-Hauser syndrome fail to develop müllerian ducts, present with primary amenorrhea, and an absent or rudimentary uterus and vagina. After creation of a neovagina, vaginal vault prolapse may occur because of lack of support to the artificially created vagina. CASES: The first patient presented with vaginal vault prolapse 10 years after her vagina was mechanically dilated. The second patient presented with vaginal vault prolapse 27 years after a McIndoe procedure. CONCLUSION: Women with Mayer-Rokitansky-Küster-Hauser syndrome with an artificially created neovagina by dilatation or surgical procedure with a graft are at risk for vaginal vault prolapse. They can be successfully treated with abdominal sacrocolpopexy and paravaginal repair.

Adult↗

PubMed2002

Dissecting human adrenal androgen production.

The human adrenal cortex produces aldosterone, cortisol and the so-called adrenal androgens, dehydroepiandrosterone (DHEA) and DHEA sulfate (DHEAS). Within the adult adrenal, the zona glomerulosa produces aldosterone, the zona fasciculata cortisol and the zona reticularis both DHEA and DHEAS. The processes regulating aldosterone and cortisol synthesis are well defined; however, the mechanisms regulating the production of DHEA(S) remain elusive. The emphasis of this review is based on increasing evidence that cytochrome b(5), DHEA sulfotransferase and 3 beta-hydroxysteroid dehydrogenase play crucial roles in regulating production of DHEA(S). Insight into the mechanisms that regulate the synthesis of these key components of DHEA(S) synthesis should provide important clues to the regulation of adrenal androgen biosynthesis.

3-Hydroxysteroid Dehydrogenases↗

PubMed2002

Estrogens.

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Adipose Tissue↗

PubMed2002

The adrenal genetic puzzle: how do the fetal and adult pieces differ?

The basis for the steroidogenic differences between the human fetal adrenal (HFA) and adult adrenal is not well defined. However, gene expression clearly plays a critical role in defining their distinct steroidogenic and structural phenotypes. We used DNA microarrays to compare expression levels of several thousand transcripts between the HFA and adult adrenal gland. Gene profiling was done using seven independent microarrays that contained between 7075 and 9182 cDNA elements. Twenty-five transcripts were found to have a greater than 5-fold difference in expression between HFA and adult adrenals. The largest differences were observed for transcripts that encode insulin-like growth factor-II (IGF-II) (25-fold higher in HFA) and 3beta hydroxysteroid dehydrogenase (3betaHSD) (21-fold higher in adult). The vast majority of the 25 transcripts have not been studied with regard to adrenal function. We also determined the transcripts that had the highest signal intensities, which is an approximate measure of expression level, for both the fetal and adult adrenal RNA samples. The enzyme 24-dehydrocholesterol reductase, which is involved in cholesterol biosynthesis, exhibited the highest signal intensity for fetal adrenal RNA. For adult adrenal mRNA, the expression of 11beta-hydroxylase transcripts was found to have the highest signal intensity ranking. Overall, 10 of the top 20 highest signal intensities were similar for adult and fetal adrenal transcripts. The gene profile data for fetal vs. adult adrenal glands should provide valuable information that could help define mechanisms involved in adrenal growth and development.

Adrenal Glands↗