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Publication
Journal: Journal of Clinical Investigation
April/24/1997
Abstract
Congenital lipoid adrenal hyperplasia (lipoid CAH) is the most severe form of CAH in which the synthesis of all gonadal and adrenal cortical steroids is markedly impaired. We report here the clinical, endocrinological, and molecular analyses of two unrelated Japanese kindreds of 46,XX subjects affected with lipoid CAH who manifested spontaneous puberty. Phenotypic female infants with 46,XX karyotypes were diagnosed with lipoid CAH as newborns based on a clinical history of failure to thrive, hyperpigmentation, hyponatremia, hyperkalemia, and low basal values of serum cortisol and urinary <em>17</em>-hydroxycorticosteroid and <em>17</em>-<em>ketosteroid</em>. These patients responded to treatment with glucocorticoid and 9alpha-fludrocortisone. Spontaneous thelarche occurred in association with increased serum estradiol levels at the age of 10 and 11 yr, respectively. Pubic hair developed at the age of 12 yr 11 mo in one subject and menarche was at the age of 12 yr in both cases. Both subjects reported periodic menstrual bleeding and subsequently developed polycystic ovaries. To investigate the molecular basis of the steroidogenic lesion in these patients, the StAR gene was characterized by PCR and direct DNA sequence analyses. DNA sequence analysis revealed that one patient is homozygous for the Gln 258 Stop mutation in exon 7 and that the other patient is a compound heterozygote with the Gln 258 Stop mutation and a single A deletion at codon 238 in the other allele causing a frame-shift, which renders the StAR protein nonfunctional. These findings demonstrate that ovarian steroidogenesis can be spared to some extent through puberty when the StAR gene product is inactive. This is in marked contrast to the early onset of severe defects in testicular and adrenocortical steroidogenesis which are characteristics of this disease.
Publication
Journal: Journal of Clinical Endocrinology and Metabolism
December/28/1986
Abstract
The therapeutic value of ketoconazole for long term treatment of patients with Cushing's syndrome was studied. Seven patients with Cushing's disease and one with an adrenal adenoma received 600-800 mg/day ketoconazole for 3-13 months. Plasma ACTH, cortisol, and dehydroepiandrosterone sulfate levels and urinary cortisol, <em>17</em>-<em>ketosteroid</em>, and tetrahydro-11-deoxycortisol excretion were determined periodically during the treatment period. Plasma ACTH and cortisol responses to CRH stimulation were determined before and during treatment. Rapid and subsequently persistent clinical improvement occurred in each patient; plasma dehydroepiandrosterone sulfate and urinary <em>17</em>-<em>ketosteroid</em> and cortisol excretion decreased soon after the initiation of treatment, subsequently remaining normal or nearly so throughout the treatment period. Urinary tetrahydro-11-deoxycortisol excretion increased significantly. Plasma cortisol levels decreased. Plasma ACTH levels did not change, and individual plasma ACTH and cortisol increments in response to CRH were comparable before and during treatment. The cortisol response to insulin-induced hypoglycemia improved in one patient and was restored to normal in another. The seven patients tested recovered normal adrenal suppressibility in response to a low dose of dexamethasone during ketoconazole treatment. Ketoconazole is effective for long term control of hypercortisolism of either pituitary or adrenal origin. Its effect appears to be mediated by inhibition of adrenal 11 beta-hydroxylase and <em>17</em>,20-lyase, and it, in some unknown way, prevents the expected rise in ACTH secretion in patients with Cushing's disease.
Publication
Journal: Journal of steroid biochemistry
May/16/1984
Abstract
We previously suggested [Steroids 33, (1979) 3; Steroids 37, (1981) 6] that cultured genital skin fibroblasts should prove useful for screening of potential antiandrogens in human and living target cells. "Serenoa repens" lipidic extract (S.R.E.) was recently reported (Br. J. Pharmacol., in press) to inhibit androgen action in animals. The present investigation was designed to study the antiandrogenicity of this compound in human cells: we therefore analyzed the effects of S.R.E. on the intracellular conversion of testosterone (T) to 5 alpha-reduced derivatives, and we investigated interaction of S.R.E. with the intracellular androgen-receptor complex. Since the chemical structure of the active component of S.R.E. is still unknown, results are expressed in U/ml (one unit is defined as the amount of S.R.E. required to inhibit 50% of the specific binding (IC50) of [3H]1881 to rat prostate cytosol). S.R.E. at different dilutions (5.7 to 28.6 U/ml) is added to culture media containing [3H]T or [3H]dihydrotestosterone (DHT) and incubated at 37 degrees C with cultured fibroblasts. 28.6 U/ml S.R.E. significantly alters the formation of DHT and strongly inhibits 3 <em>ketosteroid</em> reductase mediated conversion of DHT to 5 alpha-androstane-3 alpha, <em>17</em> beta-diol, characterized radiochemically by thin-layer chromatography. S.R.E. is a good competitor for the whole cell androgen receptor: 7.1 U/ml S.R.E. gives 50% inhibition of the binding of 2 X 10(-9) M [3H]DHT to its receptor. Competitive binding assays after cell fractionation indicate that S.R.E. is less potent in nuclear than in cytosol receptors. Sucrose gradient centrifugation of the radioactive cell lysate of fibroblasts demonstrates that 28.6 U/ml S.R.E. abolishes 70% of the 3.6 S receptor-complex radioactive peak. The present studies show that S.R.E. inhibits 5 alpha-reductase, 3-<em>ketosteroid</em> reductase and receptor binding of androgens in cultured human foreskin fibroblasts. As the search for the ideal antiandrogen continues, S.R.E. appears to be a new type of antiandrogenic compound as therapeutics for the treatment of benign prostatic hypertrophy, hirsutism and so forth.
Publication
Journal: Archives of Disease in Childhood
October/1/1976
Abstract
Pituitary, adrenal, and pancreatic functions were investigated in 9 patients with thalassaemia major. 9 a.m. plasma ACTH values were 148-480 pg/ml (normal range 15-70 pg/ml). Cortisol and growth hormone response to insulin-induced hypoglycaemia was normal in all. 24-hour urinary excretions of <em>17</em>-<em>ketosteroids</em> and <em>17</em>-hydroxycorticosteroids were normal. There was normal cortisol response to intramuscular injection of ACTH. In a physiological adrenal stimulation test there was a significantly smaller response to each physiological dose of tetracosactrin. 4 patients had diabetic glucose tolerance tests--none are clinically diabetic. The mean plasma glucose utilization constant (Kgl=2-02) is significantly smaller than normal. Plasma insulin response both in the oral and the intravenous glucose tolerance test was significantly smaller than normal. The data were consistent with severe and widespread impairment of endocrine function and a plausible explanation would be iron deposition in endocrine organs. It is suggested that pituitary hyperfunction of ACTH secretion is due to target organ unresponsiveness which can be shown in its early stages only by a physiological test of the adrenal cortex. Skin pigmentation in thalassaemia seems to be due to the melanophore-stimulating effect of this raised plasma ACTH.
Authors
Publication
Journal: Journal of Clinical Endocrinology and Metabolism
February/14/2004
Publication
Journal: New England Journal of Medicine
October/12/1994
Abstract
BACKGROUND
Hirsutism in women is usually caused by benign adrenal or ovarian disorders, but it can also be caused by adrenal carcinoma. The most effective way to identify such carcinomas is not known.
METHODS
We measured serum and urinary steroids before and after the administration of 3 mg of dexamethasone per day for five days in 14 hirsute women with histologically proved adrenal tumors (12 adrenal carcinomas and 2 adrenal adenomas) and in 73 women with hirsutism of non-neoplastic origin.
RESULTS
All the women with adrenal tumors had elevated basal serum concentrations of testosterone or dehydroepiandrosterone sulfate, as compared with 36 of the 73 women with non-neoplastic hirsutism (sensitivity, 100 percent; 95 percent confidence interval, 77 to 100; specificity, 50 percent; 95 percent confidence interval, 38 to 62). After the administration of dexamethasone, serum dehydroepiandrosterone sulfate concentrations and urinary <em>17</em>-<em>ketosteroid</em> excretion decreased to values similar to those in normal women in all the women with non-neoplastic hirsutism, but in none of the 12 with adrenal tumors who were tested. All the women who did not have adrenal tumors had serum cortisol concentrations below 3.3 micrograms per deciliter (90 nmol per liter) after dexamethasone administration, whereas in all 12 patients tested who had tumors the values were higher. The suppression of serum dehydroepiandrosterone sulfate and cortisol and urinary <em>17</em>-<em>ketosteroid</em> excretion excluded the likelihood of adrenal tumors with a sensitivity of 100 percent (95 percent confidence interval, 74 to 100) and a specificity of 100 percent (95 percent confidence interval, 89 to 100).
CONCLUSIONS
Among women with hirsutism, an adrenal tumor is unlikely if the patient has normal basal serum concentrations of testosterone and dehydroepiandrosterone sulfate. In women in whom these concentrations are elevated, a tumor is unlikely if the serum concentration of dehydroepiandrosterone sulfate and urinary <em>17</em>-<em>ketosteroid</em> excretion are in the normal basal range and the serum cortisol concentration is less than 3.3 micrograms per deciliter after the administration of dexamethasone.
Publication
Journal: Endocrinology and Metabolism Clinics of North America
July/14/1999
Abstract
Androgens are secreted by both the ovaries and adrenal glands in response to their respective trophic hormones LH and ACTH. Androgens in women are not specifically under negative feedback control by these pituitary hormones because they are by-products of estradiol and cortisol secretion. Rather, androgen secretion seems to be regulated mostly by intraglandular mechanisms. Functional ovarian hyperandrogenism is found in about 70% of patients with PCOS. It is characterized by excessive secretion of <em>17</em>-hydroxyprogesterone in response to GnRH agonist or hCG stimulation. Failure of dexamethasone to suppress plasma free testosterone normally in the presence of normal adrenocortical suppression is also typical. Functional adrenal hyperandrogenism is found in about half of patients with PCOS. It is most often characterized by moderately increased secretion of the <em>17</em>-<em>ketosteroid</em> DHEA in response to ACTH. The most likely cause of the excessive androgen secretion by both glands seems to be abnormal regulation (dysregulation) of the <em>17</em>-hydroxylase and <em>17</em>,20-lyase activities of P-450c<em>17</em>, the rate-limiting step in androgen biosynthesis. There are also subtle generalized disturbances of steroid metabolism, including tendencies toward excessive estrogen and cortisol secretion. The cause of dysregulation of steroidogenesis is unknown. The hyperinsulinemia that is compensatory for resistance to the glucose-metabolic effect of insulin seems to have a role in many cases. In most cases, intrinsic intraovarian or intra-adrenal autocrine or paracrine regulatory mechanisms are most likely malfunctioning.
Publication
Journal: Journal of Endocrinology
August/6/1982
Abstract
Circadian changes in plasma 18-hydroxy-11-deoxycorticosterone (18-OH-DOC), total and unbound cortisol were studied in four groups: seven healthy young men, six elderly men, six elderly women and six elderly demented patients of both sexes. The daily activities of the subjects were synchronous; blood samples were taken every 4 h and 4 hourly urine samples were collected only from the young men. A circadian rhythm was defined for plasma 18-OH-DOC, total and unbound cortisol in all groups; the secretory patterns of these steroids were parallel, as were the profiles of urinary 18-OH-DOC and unconjugated cortisol. When compared with respect to sex, the 24-h mean level of total cortisol was higher in women; that of unbound cortisol was higher in the three groups of elderly patients than in the young men. No major changes in plasma steroids were observed between elderly demented patients (mainly women) and healthy elderly women. The phasing of total and unbound cortisol showed no major modifications with age, sex or senile dementia. Acrophases of 18-OH-DOC were earlier in elderly patients than in young men. Amplitudes were not modified with sex in elderly patients but were always lower in the demented patients. A circadian rhythm was defined for 18-OH-DOC, unconjugated cortisol, <em>17</em>-hydroxycorticosteroids (<em>17</em>-OH-CS) and <em>17</em>-<em>ketosteroids</em> in the urine of the young men. The acrophases of 18-OH-DOC and unbound cortisol were close, as were those of <em>17</em>-OH-CS and <em>17</em>-<em>ketosteroids</em>. The lag was short between the acrophases of 18-OH-DOC in plasma and urine and between those of plasma unbound cortisol and urinary unconjugated cortisol; it was much larger between the acrophases of plasma total cortisol and <em>17</em>-OH-CS. Thus, the process of ageing, and the possible alterations in the central nervous system which are often seen in normal ageing, induced no major modifications in the temporal organization of adrenocortical function, even in subjects who were very advanced in age.
Publication
Journal: Archives of surgery (Chicago, Ill. : 1960)
April/10/1994
Abstract
OBJECTIVE
To determine the frequency of subclinical hormone secretion in incidentally discovered adrenal masses.
METHODS
We reviewed the radiologic reports of <em>17</em>79 consecutive computed tomographic scans of the chest, abdomen, and pelvis.
METHODS
Regional referral medical center.
METHODS
Eighty-nine patients with abnormalities of one or both adrenal glands were identified. Patients with nonadrenal gland malignant neoplasms, primary aldosteronism, adrenal hemorrhage, and death or severe illness were not investigated. The final study group consisted of 26 patients with incidentally discovered adrenal masses.
METHODS
Aldosterone secretion was assessed by measuring plasma renin activity and the plasma aldosterone concentration in patients with unexplained hypokalemia. We evaluated cortisol secretion by performing a 1-mg overnight dexamethasone suppression test and by measuring the corticotropin concentration at 8 AM by a sensitive method. In patients with low corticotropin values, we also measured the 24-hour urinary excretion of free cortisol and <em>17</em>-<em>ketosteroids</em> and assessed diurnal variation by measuring plasma cortisol concentrations at 8 AM and 4 PM. Adrenal medullary function was studied by measuring urinary free catecholamines.
RESULTS
One patient had unrecognized primary aldosteronism, two patients had elevated free catecholamine excretion, and three patients (12%) had subclinical Cushing's syndrome.
CONCLUSIONS
Based on our observations and a review of the literature, we conclude that subclinical hormone secretion, especially cortisol secretion, is more common in patients with incidentally discovered adrenal masses than previously appreciated. Surgeons and anesthesiologists must be alert to the possibility that adrenal insufficiency or a hypertensive crisis may develop in the perioperative period in patients with incidentally discovered adrenal masses.
Publication
Journal: Hypertension
January/19/2015
Abstract
Pulmonary arterial hypertension (PAH) is a debilitating and deadly disease with no known cure. Heart failure is a major comorbidity and a common cause of the premature death of patients with PAH. Increased asymmetrical right ventricular hypertrophy and septal wall thickening compress the left ventricular cavity and elicit diastolic heart failure. In this study, we used the Sugen5416/hypoxia/normoxia-induced PAH rat to determine whether altered pyridine nucleotide signaling in the failing heart contributes to 1) increased oxidative stress, 2) changes in metabolic phenotype, 3) autophagy, and 4) the PAH-induced failure. We found that increased reactive oxygen species, metabolic maladaptation, and autophagy contributed to the pathogenesis of right ventricular remodeling and hypertrophy that lead to left ventricular diastolic dysfunction. In addition, arterial elastance increased in PAH rats. Glucose-6-phosphate dehydrogenase is a major source of pyridine molecule (nicotinamide adenine dinucleotide phosphate), which is a substrate for nicotinamide adenine dinucleotide phosphate oxidases in the heart. Dehydroepiandrosterone, a <em>17</em>-<em>ketosteroid</em> that reduces pulmonary hypertension and right ventricular hypertrophy, inhibited glucose-6-phosphate dehydrogenase, decreased oxidative stress, increased glucose oxidation and acetyl-coA, and reduced autophagy in the hearts of PAH rats. It also decreased arterial stiffness and improved left ventricular diastolic function. These findings demonstrate that pyridine nucleotide signaling, at least partly, mediates PAH-induced diastolic heart failure, and that reduction of glucose-6-phosphate dehydrogenase-derived nicotinamide adenine dinucleotide phosphate is beneficial to improve left ventricle diastolic function.
Publication
Journal: Journal of Endocrinology
March/16/1983
Abstract
The circannual rhythms of plasma 18-hydroxy-11-deoxycorticosterone (18-OH-DOC), total and free cortisol have been documented on a circadian basis in January, March, June and October in seven young men (24 years old), six elderly men, six elderly women and six elderly demented subjects, both men and women, in their eighties. Blood samples were drawn every 4 h over a 24-h period at each sampling session and urine samples were collected at 4-h intervals only from the young men. A circadian rhythm of <em>17</em>-hydroxy-corticosteroids (<em>17</em>-OH-CS), <em>17</em>-<em>ketosteroids</em> (<em>17</em>-KS), urinary free cortisol and 18-OH-DOC was defined for each of the four seasons with stable acrophases throughout the year and the same excretory profiles. A circannual rhythm was validated in young men for <em>17</em>-OH-CS, urinary free cortisol and 18-OH-DOC but not for <em>17</em>-KS. A circadian rhythm of plasma free cortisol, the active form of the hormone, plasma total cortisol and plasma 18-OH-DOC was validated in all groups and at all the seasons at which samples were taken. The secretory profiles of 18-OH-DOC, free and total cortisol were very similar, with no differences attributable to age, sex or mental condition except for the levels of plasma free cortisol and 18-OH-DOC which were higher and lower respectively in the elderly subjects. Whereas a circannual rhythm of plasma 18-OH-DOC was validated for all groups, a circannual rhythm of both free and total cortisol in the plasma was validated in young men but not in any group of elderly subjects. This loss of the circannual rhythmicity of cortisol in the elderly may reflect the decrease with age of the capacity to adapt to seasonal external factors.
Publication
Journal: Archives of Disease in Childhood
May/25/1981
Abstract
In 11 children aged between 2 and <em>17</em> years with (nonsalt-losing) congenital adrenal hyperplasia (21-hydroxylase deficiency) blood was drawn at 90-minute intervals during a 24-hour period and levels of <em>17</em>-hydroxyprogesterone, testosterone, and cortisol were measured. Levels of <em>17</em>-<em>ketosteroids</em> and pregnanetriol were measured too in 24-hour urine samples. These measurements were taken under different regimens of treatment and after interruption of treatment. Cortisol level rose and fell rapidly after administered corticosteroid, and reached unphysiologically high levels. Testosterone levels showed pronounced variations but stayed in the normal range for most of the time even in untreated patients; thus testosterone provides a poor control parameter. Levels of <em>17</em>-hydroxyprogesterone showed extreme fluctuations and very high peak levels in untreated patients; standard treatment with two or three daily doses of corticosteroids did not prevent a pronounced rise in its level after midnight. After the first morning dose of hydrocortisone a very steep fall was observed. The 24-hour pregnanetriol excretion correlated well with the corresponding total integrated <em>17</em>-hydroxyprogesterone area. It is concluded that single <em>17</em>-hydroxyprogesterone values are unlikely to give adequate information about the quality of treatment.
Publication
Journal: Food and Chemical Toxicology
July/15/2009
Abstract
Different forms of aluminium (Al) are environmental xenobiotics that induce free radical-mediated cytotoxicity and reproductive toxicity. Propolis has been reported to be important antioxidant. Therefore, this study aimed at elucidating the protective effects of propolis against reproductive toxicity of aluminium chloride (AlCl3) in male rats. The first group served as control. Group 2 received 34 mg AlCl3/kg bw (1/25 LD50). Group 3 was administered 50 mg propolis/kg bw/day. Group 4 was treated with AlCl3 plus propolis. Treatment was continued for 70 days. AlCl3 caused a decrease in testes, seminal vesicle and epididymis weights, sperm concentration, motility, testosterone level and the activities of <em>17</em>-<em>ketosteroid</em> reductase, CAT and GST, and GSH content. While, dead and abnormal sperm and testes TBARS concentrations were increased. In the AlCl3-treated group, histopathologic examinations revealed apparent alterations in the testes, where it induced marked lesions in seminiferous tubules. Propolis alone decreased dead and abnormal sperm and TBARS, and increased testosterone, GSH, <em>17</em>-<em>ketosteroid</em> reductase, CAT and GST. Results showed that propolis antagonized the harmful effects of AlCl3. This was proved histopathologically by the great improvement in testes. In conclusion propolis could be effective in the protection against the reproductive toxicity of AlCl3.
Publication
Journal: Journal of Clinical Oncology
February/21/1990
Abstract
Adrenocortical carcinoma (ACC), a very rare tumor in children in the United States, is apparently more common among Brazilian children. We reviewed the medical records of 40 children whose disease was diagnosed between 1966 and 1987. There were 12 boys and 28 girls; their median age was 3.9 years (range, 1 day to 15.7 years). Virilization was the most common clinical sign (37 of 40); other signs included abdominal mass, deepened voice, plethora, hypertension, seizures (seven patients) and, rarely, weight loss (two patients). The median time between first signs or symptoms and diagnosis was 1.4 years (range, 3 days to 5 years). Four of 33 tumors were classified as benign according to the Weiss, van Slooten, or Hough systems (tumor tissue was unavailable for seven patients). Tumors were completely resected in 26 of 38 patients; of those, <em>17</em> are in continuous complete remission, five relapsed, and four have been lost to follow-up. One patient, who had local recurrence, has been in a third complete remission for 18+ months after tumor resection and chemotherapy (cisplatin and etoposide). Of the remaining 14 patients, 11 died of progressive disease, the diagnosis was confirmed at autopsy in two, and one has been lost to follow-up. Univariate analysis disclosed that age greater than or equal to 3.5 years at diagnosis, interval of greater than or equal to 6 months between first symptoms and diagnosis, tumor weight greater than 100 g, tumor size greater than 200 cm3, and high levels of urinary <em>17</em>-<em>ketosteroids</em> (<em>17</em>-KS) and <em>17</em>-hydroxycorticosteroids (<em>17</em>-OH) were associated with an unfavorable outcome. Multivariate analysis disclosed that only a tumor size greater than 200 cm3 independently identifies those patients with an unfavorable prognosis. Among the variables known before surgery, age, and the interval between first symptoms and diagnosis were important predictors of outcome. Our data suggest that some children with ACC and certain clinical characteristics are at high risk of primary treatment failure and, therefore, are good candidates for investigational adjuvant therapy.
Publication
Journal: Journal of Biological Chemistry
May/19/2009
Abstract
Aldo-ketoreductase 1C (AKR1C) enzymes catalyze the NADPH-dependent reduction of <em>ketosteroids</em> to hydroxysteroids. They are Phase I metabolizing enzymes for natural and synthetic steroid hormones. They convert 5alpha-dihydrotestosterone (Dht, potent androgen) to 3alpha/beta-androstanediols (inactive androgens) and the prodrug tibolone (Tib) to estrogenic 3alpha/beta-hydroxytibolones. Herein we demonstrate for the first time that human AKR1C enzymes (AKR1C1-4) are able to reduce conjugated steroids such as Dht-<em>17</em>beta-glucuronide (DhtG), Dht-<em>17</em>beta-sulfate (DhtS), and Tib-<em>17</em>beta-sulfate (TibS). Product identities were characterized by liquid chromatography-mass spectrometry, and kinetic parameters of the reactions were determined. The product profile of the reduction of each steroid conjugate by the individual AKR1C isoform was similar to that of the corresponding free steroid except for the reduction of DhtG catalyzed by AKR1C2, where a complete inversion in stereochemical preference to 3beta-reduction (with DhtG) from 3alpha-reduction (with Dht and DhtS) was observed. The catalytic efficiency of 3-keto reduction was modestly affected by the presence of a <em>17</em>-sulfate group but severely impaired by the presence of a <em>17</em>-glucuronide group for AKR1C1-3 isoforms. AKR1C4, however, showed superior catalytic efficiencies versus the other isoforms, and those were unaffected by steroid conjugation. Our findings provide evidence for alternative pathways of steroid metabolism where the phase I reaction (reduction) occurs after the phase II reaction (conjugation). Specifically, it is indicated that Dht is metabolized to its metabolite 3alpha-androstanediol-<em>17</em>-glucuronide via the previously unrecognized "conjugation pathway" involving the sequential reactions of UGT2B<em>17</em> and AKR1C4 in liver but via the conventional "reduction pathway" involving the sequential reactions of AKR1C2 and UGT2B15/<em>17</em> in prostate.
Publication
Journal: Archives of Biochemistry and Biophysics
May/18/1995
Abstract
Previous studies have demonstrated that certain <em>17</em>- and 20-<em>ketosteroids</em> are potent inhibitors of the NADP-linked oxidation of glucose 6-phosphate by mammalian glucose 6-phosphate dehydrogenases. This inhibition is uncompetitive with respect to both NADP+ and glucose 6-phosphate. In order to elucidate the detailed mechanism of this rare type of inhibition, we examined the effects of steroids on human glucose 6-phosphate dehydrogenase catalyzing the reverse reaction, i.e., the reduction of the gluconolactone by NADPH. To circumvent problems associated with the known instability of 6-phospho-delta-gluconolactone, the natural product of glucose 6-phosphate oxidation, the more stable 6-phospho-gamma-gluconolactone was used. Dehydroepiandrosterone, epiandrosterone, 16 alpha-bromoepiandrosterone, and dehydroepiandrosterone sulfate all inhibited the reverse reaction uncompetitively with respect to both NADPH and the gamma-lactone. The Ki values for each of these steroids, determined by varying either coenzyme or substrate in both the forward and the reverse reactions, are very similar. These results demonstrate that steroids inhibit glucose 6-phosphate dehydrogenase by binding to the ternary enzyme-coenzyme-substrate ternary complex(es). This is the first direct demonstration that uncompetitive inhibition of a two-substrate enzyme, by compounds other than its substrates or products, can occur by binding of the inhibitor to a ternary enzyme complex.
Publication
Journal: Chemico-Biological Interactions
February/26/2009
Abstract
Aldo-keto reductase (AKR) 1C3 catalyzes the NADPH-dependent reduction of Delta(4)-androstene-3,<em>17</em>-dione to yield testosterone, reduction of estrone to yield <em>17</em>beta-estradiol and reduction of progesterone to yield 20alpha-hydroxyprogesterone. In addition, it functions as a prostaglandin (PG) F synthase and reduces PGH(2) to PGF(2)alpha and PGD(2) to 11beta-PGF(2). Immunohistochemistry showed that AKR1C3 is over-expressed in invasive ductal carcinoma of the breast. Retroviral expression of AKR1C3 in MCF-7 breast carcinoma cells shows that each of the assigned reactions occur in a breast cell microenvironment. Steroid and prostaglandin conversions were monitored by radiochromatography. Prostaglandin conversion was validated by a second method using HPLC coupled to APCI-MRM/MS. The combined effect of the AKR1C3 catalyzed <em>17</em>- and 20-<em>ketosteroid</em> reductions will be to increase the <em>17</em>beta-estradiol:progesterone ratio in the breast. In addition, formation of PGF(2) epimers would activate F prostanoid receptors and deprive PPARgamma of its putative anti-proliferative PGJ(2) ligands. Thus, AKR1C3 is a source of proliferative signals and a potential therapeutic target for hormone-dependent and -independent breast cancer. Two strategies for AKR1C3 inhibition based on non-steroidal anti-inflammatory drugs were developed. The first strategy uses the Ullmann coupling reaction to generate N-phenylanthranilate derivatives that inhibit AKR1C enzymes without affecting PGH(2) synthase (PGHS) 1 or PGHS-2. The second strategy exploits the selective inhibition of AKR1C3 by indomethacin, which did not inhibit highly related AKR1C1 or AKR1C2. Using known structure-activity relationships for the inhibition of PGHS-1 and PGHS-2 by indole acetic acids we obtained N-(4-chlorobenzoyl)-melatonin as a specific AKR1C3 inhibitor (K(I)=6.0muM) that does not inhibit PGHS-1, PGHS-2, AKR1C1, or AKR1C2. Both strategies are informed by crystal structures of ternary AKR1C3.NADP(+).NSAID complexes. The identification of NSAID analogs as specific inhibitors of AKR1C3 will help validate its role in the proliferation of breast cancer cells.
Publication
Journal: Molecular Endocrinology
October/4/1998
Abstract
<em>17</em> beta-Hydroxysteroid dehydrogenases/<em>17</em>-<em>ketosteroid</em> reductases (<em>17</em>HSDs) modulate the biological activity of certain estrogens and androgens by catalyzing reductase or dehydrogenase reactions between <em>17</em>-keto- and <em>17</em> beta-hydroxysteroids. In the present study, we demonstrate expression cloning of a novel type of <em>17</em>HSD, chronologically named <em>17</em>HSD type 7, from the HC11 cell line derived from mouse mammary gland. The cloned cDNA, 1.7 kb in size, encodes a protein of 334 amino acids with a calculated molecular mass of 37,3<em>17</em> Da. The primary structure contains segments characteristic of enzymes belonging to the short-chain dehydrogenase/reductase superfamily. Strikingly, mouse <em>17</em>HSD type 7 (m<em>17</em>HSD7) shows 89% identity with a recently cloned rat protein called PRL receptor-associated protein (PRAP). The function of PRAP has not yet been demonstrated. The enzymatic characteristics of m<em>17</em>HSD7 and RT-PCR-cloned rat PRAP (rPRAP) were analyzed in cultured HEK-293 cells, where both of the enzymes efficiently catalyzed conversion of estrone (E1) to estradiol (E2). With other substrates tested no detectable <em>17</em>HSD or 20 alpha-hydroxysteroid dehydrogenase activities were found. Kinetic parameters for m<em>17</em>HSD7 further indicate that E1 is a preferred substrate for this enzyme. Relative catalytic efficiencies (Vmax/K(m) values) for E1 and E2 are 244 and 48, respectively. As it is the case with rPRAP, m<em>17</em>HSD7 is most abundantly expressed in the ovaries of pregnant animals. Further studies show that the rat enzyme is primarily expressed in the middle and second half of pregnancy, in parallel with E2 secretion from the corpus luteum. The mRNA for m<em>17</em>HSD7 is also apparent in the placenta, and a slight signal for m<em>17</em>HSD7 is found in the ovaries of adult nonpregnant mice, in the mammary gland, liver, kidney, and testis. Altogether, because of their similar primary structures, enzymatic characteristics, and the tissue distribution of m<em>17</em>HSD7 and rPRAP, we suggest that rPRAP is rat <em>17</em>HSD type 7. Furthermore, the results indicate that <em>17</em>HSD7 is an enzyme of E2 biosynthesis, which is predominantly expressed in the corpus luteum of the pregnant animal.
Publication
Journal: Seminars in Arthritis and Rheumatism
November/8/1984
Abstract
Using GLC, multiple adrenal corticosteroid urinary metabolites, including androgenic-anabolic, glucocorticoid, pregnanediol, and pregnanetriol, were measured in eight ambulatory female RA patients and eight matched normal control subjects on baseline, ACTH-, and metyrapone-stimulation days under carefully monitored clinical research center protocol. Neither group had been treated previously with any steroid hormones. The 11-deoxy-<em>17</em>-KS metabolites, derived from adrenal androgenic-anabolic steroids, and comprising androsterone, etiocholanolone, and DHA, were significantly lower in RA patients on baseline (P less than .001), ACTH (P less than .005)-, and metyrapone (P less than .02)-stimulation days. To the contrary, the 11-oxy-<em>17</em>-KS metabolites, derived mainly from glucocorticoids, showed some lowered excretion at baseline (P less than .05), but none on ACTH- or metyrapone-stimulation. RA patients had lower tetrahydrocortisone (P less than .001) and tetrahydro-11-deoxycortisol (P less than .01) excretion at baseline, but not during ACTH- or metyrapone-stimulation, than control subjects. Pregnanetriol excretion was lower (P less than .005) in RA patients than control subjects only during ACTH-stimulation. No difference was found between groups in tetrahydrocortisol or pregnanediol excretion on any day studied. Under conditions of oral metyrapone administration (750 mg every four hours for seven doses) each control subject increased their DHA excretion, but no RA patient showed an increase over baseline excretion (P less than .02). Except for 11-deoxy-<em>17</em>-KS, no difference was found in the other metabolites studied during metyrapone stimulation, ie, pregnanediol, pregnanetriol, tetrahydro-11-deoxycortisol, and tetrahydrocortisol. The 24-hour oral metyrapone test provided a greater stimulus to total 11-deoxy-<em>17</em>-KS excretion than an eight-hour intravenous ACTH test in control and particularly RA (P less than .01) subjects even though the DHA excretion decreased in the RA groups. Our findings of lower adrenal androgenic-anabolic metabolite excretion in female RA patients than normal matched control subjects under various conditions and other supportive androgenic hormone and metabolite studies reviewed in the English reports suggest an abnormality of adrenal androgen synthesis or metabolism in RA, whether it be a primary predisposing or secondary factor in disease. The recognized female sex preponderance and age-specific patterns of occurrence of RA are consistent with adrenal androgenic function in adrenarche, adrenopause, and later changes in aging. Metabolite excretion patterns at baseline, ACTH-, and metyrapone- stimulation indicate the greatest relative
Publication
Journal: Archives of environmental health
September/23/1987
Abstract
To determine if increased lead absorption was associated with sperm count suppression or perterbation of the hypothalamopituitary system, we compared battery workers (N = 18), who were exposed to high airborne lead levels, with cement workers (N = 18), who were exposed to ambient lead levels. Blood lead, urinary lead, semen lead, and zinc protoporphyrin concentrations were markedly elevated (p less than .001) in battery workers. Battery workers had a significantly shifted (p less than .025) frequency distribution of sperm count (median count, 45 vs. 73 X 10(6) cells/cc, respectively). There were no significant differences between the two groups in mean follicle-stimulating hormone, testosterone, prolactin, luteinizing hormone, or total neutral <em>17</em>-<em>ketosteroid</em> levels. Potential confounding factors (alcohol, cigarette, and coffee consumption, frequency of intercourse, and days of abstinence prior to semen donation) were not significantly different between the two groups. These results suggest a direct toxic effect of increased lead absorption on sperm production or transport in man.
Publication
Journal: Acta Endocrinologica
February/14/2004
Authors
Publication
Journal: Journal of Clinical Endocrinology and Metabolism
April/15/1987
Abstract
The effects of burn trauma in men on the production of adrenal and testicular steroids was investigated. Whereas there were significant increases in serum cortisol levels and urinary <em>17</em>-hydroxycorticosteroid excretion soon after thermal injury, there were significant decreases in serum dehydroepiandrosterone sulfate, dehydroepiandrosterone, androstenedione, and testosterone concentrations during the first 4 weeks following burn trauma. Serum androstenediol and androstenediol sulfate levels also were reduced, though insignificantly, 10-23 days postburn. Serum LH levels were unchanged during the postburn interval. Since urinary <em>17</em>-<em>ketosteroid</em> excretion was normal or below normal rather than increased, the decline in serum C19-steroid levels probably resulted from decreased glandular secretion rather than increased rates of metabolism and excretion. Low dehydroepiandrosterone sulfate and/or testosterone levels were found in some men several months after recovery from their burns. These data suggest that thermal injury leads to acute inhibition of adrenal and testicular C19-steroid secretion, but stimulation of adrenal glucocorticosteroid production, and that endocrine function in many instances is not normalized after complete healing of the burned surfaces. The mechanisms and physiological consequences of such changes in the steroid milieu of men after burn trauma are unknown.
Publication
Journal: Journal of Clinical Endocrinology and Metabolism
October/22/1990
Abstract
A 53-yr-old man with Cushing's disease was found to have a pituitary carcinoma with metastases to the liver and lung which produced both CRH and ACTH simultaneously. Despite removal of the pituitary tumor, his Cushing's disease worsened. Endocrinological examination then demonstrated elevated plasma CRH and markedly elevated plasma ACTH, beta-lipotropin, and cortisol concentrations, increased urinary <em>17</em>-hydroxycorticosteroid and <em>17</em>-<em>ketosteroid</em> excretion, and no suppression of serum cortisol after low or high dose dexamethasone administration. Urinary <em>17</em>-hydroxycorticosteroid excretion increased in response to metyrapone, and lysine vasopressin elicited a striking increase in plasma ACTH. A computed tomographic scan of abdomen revealed multiple hypodense areas in the liver and bilateral adrenal hyperplasia. Postmortem histological examination revealed a necrotic hemorrhagic pituitary carcinoma with metastases to the liver, lung, and olfactory bulb. Immunohistochemical staining, gel filtration, and Northern blot analysis of liver and lung metastases revealed evidence of the production of both CRH and ACTH in these metastases. We concluded that the patient's pituitary carcinoma produced both CRH and ACTH.
Publication