Biomedical subjects

D L Loriaux

Publications and source records attributed to D L Loriaux.

At least 19 recordsLinked to original sources

PubMed1995

Inhibition of dexamethasone binding to human glucocorticoid receptor by New World primate cell extracts.

To determine if New World primates express an inhibitor that influences glucocorticoid receptor (GR) binding characteristics, we examined [3H]dexamethasone binding in cytosol prepared from B95-8 lymphoid cells, derived from the cotton top tamarin (Saguinus oedipus), in combination with cytosol prepared from human or rat tissues. B95-8 cytosol inhibited specific binding of [3H]dexamethasone (P < 0.01) when mixed with cytosol prepared from either a human lymphoid cell line (HL) or rat thymus. The inhibitory activity was heat labile and trypsin sensitive. Peak inhibitory activity was found in the 150-200 kd fractions after Sephacryl G-200 ultrafiltration. Scatchard analysis of [3H]dexamethasone binding using mixed cytosol showed a diminished GR apparent binding affinity when compared to HL cytosol. Kinetic studies using mixed cytosol indicated that B95-8 cytosol did not affect the apparent dissociation rate of [3H]dexamethasone. These data demonstrate that B95-8 cells contain a competitive inhibitor that prevents binding of dexamethasone to its cognate receptor.

Animals↗

PubMed1992

Endocrinology.

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Endocrinology↗

PubMed1992

Urine free cortisol in the high-dose dexamethasone suppression test for the differential diagnosis of the Cushing syndrome.

OBJECTIVE: To develop criteria for interpreting the high-dose dexamethasone suppression test using urine free cortisol as an end point for the differential diagnosis of the Cushing syndrome. DESIGN: Retrospective review. SETTING: Inpatient research ward. PATIENTS: Patients (118) with surgically confirmed causes of the Cushing syndrome: 94 with pituitary disease, 14 with primary adrenal disease, and 10 with ectopic adrenocorticotropic hormone (ACTH) secretion. MAIN OUTCOME MEASURES: The sensitivity, specificity, and diagnostic accuracy were determined for the high-dose dexamethasone suppression test using urine free cortisol and using 17-hydroxysteroid excretion. For each analysis, patients with pituitary disease were considered to be "diseased" and patients with nonpituitary disease were considered to be "non-diseased". The level of suppression that gave 100% specificity was determined for each steroid. RESULTS: The accuracy of urine free cortisol when used as an end point in the high-dose dexamethasone suppression test was equivalent to that of 17-hydroxysteroid excretion. At all levels of sensitivity and specificity, however, the degree of suppression of urine free cortisol used for the diagnosis of pituitary disease was greater than that of 17-hydroxysteroid excretion. The likelihood ratios for pituitary disease based on urine free cortisol suppression of greater than 50%, of greater than 80%, and of greater than 90% were 4.2, 10.1, and "infinite," respectively. Suppression of urine free cortisol greater than 90% or suppression of 17-hydroxysteroid excretion greater than 64% was associated with 100% specificity. When these criteria were combined, the percentage of correct predictions (102 of 118 [86%; 95% CI, 78% to 92%]) was higher than that obtained using either steroid alone (89 of 118 [75%; CI, 65% to 83%]) (P = 0.009) and higher than that obtained using the traditional criterion of 50% suppression for 17-hydroxysteroid excretion (95 of 118 [80%; CI, 71% to 87%]) (P = 0.016). CONCLUSIONS: In the high-dose dexamethasone suppression test, the degree of suppression of urine free cortisol used for the diagnosis of pituitary disease is greater than that traditionally used for 17-hydroxysteroid excretion. The diagnostic performance of the test is improved by measuring both urine free cortisol and 17-hydroxysteroid excretion and by requiring greater suppression of both steroids.

17-Hydroxycorticosteroids↗

PubMed1992

Delayed endometrial maturation induced by daily administration of the antiprogestin RU 486: a potential new contraceptive strategy.

OBJECTIVE: Our objective was to determine if a progesterone antagonist might interdict the development of a secretory endometrium. STUDY DESIGN: Eleven normally cycling women not at risk for pregnancy received RU 486 (1 mg/day orally) or placebo throughout one menstrual cycle in a randomized, double-blind, crossover fashion. Estradiol, progesterone, and placental protein 14 were measured every 3 days; luteinizing hormone was measured until the midcycle surge was detected. An endometrial biopsy was performed on luteal phase day 7 to 9 and interpreted with Noyes' criteria. Differences between treatment groups were analyzed by the Student t test. RESULTS: RU 486 delayed ovulation, retarded endometrial maturation, and reduced peak levels of placental protein 14 without affecting gonadal steroid production. The abnormalities in endometrial morphology and function are similar to those seen in infertile women with luteal phase defects. CONCLUSION: We hypothesize that this regimen of antiprogestin administration may prevent implantation and offer a novel strategy for fertility control.

Adult↗

PubMed1992

The effect of pubertal delay on adult height in men with isolated hypogonadotropic hypogonadism.

To determine whether delay of puberty alters adult height, we retrospectively evaluated the adult height of 41 patients who met rigorous criteria for the diagnosis of isolated hypogonadotropic hypogonadism. The adult height of these patients was compared with the mean height of normal American men at age 18 in the 1979 National Center for Health Statistics survey and with the mean adult height of 50 male normal volunteers who had been studied on the same wards as the patients with hypogonadotropic hypogonadism. The mean adult height of the men with isolated hypogonadotropic hypogonadism was 179.7 cm, which exceeded the height of the 50 control subjects and the normal American men (both 176.8 cm) by 2.9 cm (P less than 0.05 and P less than 0.006, respectively). The mean age at treatment to induce puberty was 20.0 yr, which corresponded to a mean delay in the onset of puberty of more than 8 yr relative to normal males. The final height of the men with hypogonadotropic hypogonadism correlated significantly with the duration of pubertal delay (r = 0.32, P = 0.04). Most of the enhanced mean adult height of the patients with isolated hypogonadotropic hypogonadism was attributable to those patients in whom treatment to induce puberty had been delayed to age 18 or greater. The mean adult height of these patients was 182.4 cm, or 5.6 cm greater than the mean height of the 50 controls or of normal American men (P less than 0.001). The mean adult height of patients whose treatment began between 10 and 17 yr of age was 175.0 cm, which did not differ significantly from that of normal men. We conclude that prolonged delay of puberty (6 or more yr) in men with isolated hypogonadotropic hypogonadism is associated with a modest increase (approximately 5 cm) of adult height.

Adolescent↗

PubMed1992

Evidence for a critical role of progesterone in the regulation of the midcycle gonadotropin surge and ovulation.

Serum concentrations of progesterone begin to rise just before the midcycle gonadotropin surge that leads to ovulation. To examine the role of progesterone in the regulation of these events, we evaluated the effects of a low dose (1 mg/day, orally) of the antiprogesterone RU 486 on the timing of the gonadotropin surge and ovulation in normally cycling women. The drug or a placebo was given for 5 or 15 days, starting when the dominant follicle reached 14-16 mm. RU 486 consistently delayed the timing of the midcycle gonadotropin surge and the subsequent collapse of the dominant follicle, despite rising estradiol concentrations and normal follicular development. Unexpectedly, RU 486 also delayed the emergence of the periovulatory progesterone rise. The addition of progesterone (5-10 mg/day, im, for 2 days) to a 5-day course of RU 486 after the emergence of a mature follicle readily induced LH and FSH surges and completely reversed the effects of RU 486 at midcycle. Our results suggest that RU 486 delays the midcycle gonadotropin surge and ovulation by suppressing or antagonizing an ovarian progestational signal. Progesterone may, thus, represent the ultimate ovarian signal to the estrogen-primed hypothalamic-pituitary unit to trigger the gonadotropin surge that leads to ovulation.

Adult↗

PubMed1991

Petrosal sinus sampling with and without corticotropin-releasing hormone for the differential diagnosis of Cushing's syndrome.

BACKGROUND: Measurement of adrenocorticotropin levels in plasma from the inferior petrosal sinuses of patients with Cushing's syndrome can distinguish adrenocorticotropin-secreting pituitary tumors (Cushing's disease) from other causes of the syndrome, principally ectopic adrenocorticotropin secretion from an occult tumor. However, it is unknown whether such measurement consistently identifies patients with Cushing's disease and whether testing with corticotropin-releasing hormone (CRH) enhances the value of the procedure. METHODS: We prospectively studied 281 patients with Cushing's syndrome to evaluate the diagnostic efficacy of the procedure. Bilateral sampling was successfully accomplished in 278 patients, with no major morbidity; 262 of these patients underwent sampling before and after administration of ovine CRH. The adrenocorticotropin levels in the samples were used to calculate the ratio of the concentration in plasma from the inferior petrosal sinuses to the concentration in peripheral-blood plasma (the IPS:P ratio). RESULTS: The diagnosis of 246 patients was confirmed surgically as Cushing's disease in 215, as ectopic adrenocorticotropin syndrome in 20, and as primary adrenal disease in 11. An IPS:P ratio greater than or equal to 2.0 in basal samples identified 205 of the 215 patients with Cushing's disease (sensitivity, 95 percent), with no false positive results (specificity, 100 percent). A peak IPS:P ratio greater than or equal to 3.0 after CRH administration identified all 203 of the patients with Cushing's disease who received CRH (sensitivity, 100 percent), with no false positive results (specificity, 100 percent). The sensitivity was much lower when the adrenocorticotropin concentrations in the samples from one sinus were considered alone. In patients with Cushing's disease a difference of greater than or equal to 1.4-fold between the concentrations in the two sinuses (the adrenocorticotropin gradient) predicted the location of the microadenoma in 68 percent of 104 patients during basal sampling and in 71 percent of 105 patients after CRH administration. CONCLUSIONS: Simultaneous bilateral sampling of plasma from the inferior petrosal sinuses, with the adjunctive use of CRH, distinguishes patients with Cushing's disease from those with ectopic adrenocorticotropin secretion with high diagnostic accuracy.

ACTH Syndrome, Ectopic↗

PubMed1991

A novel testis-stimulating factor in familial male precocious puberty.

BACKGROUND: Familial male precocious puberty is a gonadotropin-independent form of precocious puberty that occurs only in males. The cause of the disorder is unknown. To examine the hypothesis that the plasma of boys with familial male precocious puberty contains a novel stimulator of testicular testosterone production, we developed a bioassay using adult male cynomolgus monkeys. METHODS: We collected plasma from 12 boys with familial male precocious puberty, 7 normal prepubertal boys of similar ages and with similar plasma gonadotropin levels, and 1 boy with hypogonadotropic hypogonadism and infused it into the testicular artery of adult male cynomolgus monkeys that had been pretreated with gonadotropin-releasing-hormone antagonist to inhibit the endogenous secretion of gonadotropins. Testicular venous effluent was collected at 15-minute intervals for 3 or 5 hours for the measurement of testosterone. RESULTS: The mean (+/- SE) peak testosterone response, as compared with base line, was significantly greater in the monkeys infused with plasma from the 12 boys with familial male precocious puberty than in the monkeys infused with plasma from the 7 normal prepubertal boys and the boy with hypogonadotropic hypogonadism (385 +/- 51 vs. 184 +/- 25 percent, P less than 0.005) in the three-hour studies. Plasma from 92 percent of the boys with familial male precocious puberty and 12.5 percent of the normal prepubertal boys stimulated a response greater than 195 percent of base-line values. In the animals studied for five hours after receiving a second dose of antagonist, the mean peak testosterone response, as compared with base line, was significantly greater in the monkeys infused with plasma from three boys with familial male precocious puberty than in the monkeys infused with plasma from three normal prepubertal boys (363 +/- 81 vs. 115 +/- 6 percent, P less than 0.01). The mean area under the testosterone-response curve was significantly larger in the monkeys infused with plasma from the boys with familial male precocious puberty in the five-hour studies (154 +/- 34 vs. -58 +/- 10 percent, P less than 0.005), but not in the three-hour studies. CONCLUSIONS: These findings support the presence of a circulating testis-stimulating factor in the plasma of boys with familial male precocious puberty. The production of such a factor would explain the biologic nature of the disorder.

Animals↗

PubMed1991

Daily administration of the progesterone antagonist RU 486 prevents implantation in the cycling guinea pig.

Since progesterone is required to prepare the endometrium for implantation of an embryo, a progesterone antagonist may inhibit nidation and thus prevent pregnancy. We addressed this possibility in the guinea pig, the small laboratory animal whose reproductive physiology most resembles that of women. Daily administration of the antiprogestin RU 486 (0, 1, 2, or 3 mg/kg, subcutaneously) for 9 days after mating inhibited implantation in a dose-dependent fashion. When this compound was given daily throughout the estrous cycle, cyclic vaginal changes, ovulation, and mating were suppressed in up to 17%, 28%, and 55% of animals, respectively. Two of seven mated female animals receiving RU 486, 1 mg/kg/day, had implantation sites. Nidation was completely blocked at higher doses. Thus daily antiprogestin administration prevented pregnancy in sexually active, normally cycling guinea pigs. A similar strategy using a daily antinidatory dose of an antiprogestin may offer a novel approach to human fertility control.

Animals↗

PubMed1991

Daily cortisol production rate in man determined by stable isotope dilution/mass spectrometry.

Growth retardation as well as the development of Cushingoid features in adrenally insufficient patients treated with the currently accepted replacement dose of cortisol (33-41 mumol/day.m2; 12-15 mg/m2.day) prompted us to reevaluate the cortisol production rate (FPR) in normal subjects and patients with Cushing's syndrome, using a recently developed thermospray liquid chromatography-mass spectrometry method. The stable isotope [9,12,12-2H3]cortisol was infused continuously for 31 h at about 5% of the anticipated FPR. Blood samples were obtained at 20-min intervals for 24 h, spun, and pooled in 4-h groups. Tracer dilution in plasma was determined by liquid chromatography/mass spectrometry. The method was validated with controlled infusions in 6 patients with adrenal insufficiency. Results from 12 normal volunteers revealed a FPR of 27.3 +/- 7.5 mumol/day (9.9 +/- 2.7 mg/day) or 15.7 mumol/day.m2; 5.7 mg/m2. day). A previously unreported circadian variation in FPR was observed. Patients with Cushing's syndrome demonstrated unequivocal elevation of FPR and cortisol concentration correlated during each sample period in normal volunteers, indicating that cortisol secretion, rather than metabolism, is mainly responsible for changes in plasma cortisol. Our data suggest that the FPR in normal subjects may be lower than previously believed.

Chromatography, Liquid↗

PubMed1991

Mitotane enhances cytotoxicity of chemotherapy in cell lines expressing a multidrug resistance gene (mdr-1/P-glycoprotein) which is also expressed by adrenocortical carcinomas.

P-Glycoprotein (Pgp), product of the mdr-1 gene, is a 130- to 180-kDa plasma membrane phosphoglycoprotein which mediates multidrug resistance in cell culture by increasing efflux of the natural product chemotherapeutic agents. High levels of expression of mdr-1/Pgp are found in both the normal adrenal and adrenocortical cancers. By RNA in situ hybridization the expression in adrenocortical cancer is shown to be widely distributed. The present study demonstrates that decreased drug accumulation mediated by mdr-1/Pgp can be overcome by clinically achievable concentrations of mitotane (o,p'-DDD). The increase in drug accumulation with the addition of mitotane is due at least in part to a decrease in drug efflux and results in an increase in cytotoxicity when agents of the natural product class are used. This effect is observed in cells with a broad range of mdr-1/Pgp expression, including levels comparable to those found in most adrenocortical cancers. Similar increases in drug accumulation can be demonstrated in an unselected adrenocortical cancer cell line that expresses mdr-1/Pgp. The finding that multidrug resistance mediated by mdr-1/Pgp can be reversed by mitotane provides a rational basis for exploring the use of mitotane in combination with natural product chemotherapeutic agents in adrenocortical cancer.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1991

Adrenal androgen secretion in postadolescent acne: increased adrenocortical function without hypersensitivity to adrenocorticotropin.

Basal and ACTH-stimulated plasma levels of cortisol, delta 4-androstenedione, and dehydroepiandrosterone (DHEA) were measured in a group of 11 female patients with postadolescent acne resistant to or relapsing after conventional therapy and in a group of 10 normal women without acne or hirsutism. Each patient received, in a blinded random fashion, a series of 5 1-h ACTH tests. For each test a different dose of ACTH-(1-24) was administered, ranging from 0-1 microgram/kg, given as an iv bolus. Blood samples were collected 0, 10, 30, and 60 min after ACTH bolus injection. Patients with acne had slightly higher concentrations of basal cortisol, delta 4-androstenedione, and DHEA than normal controls (P less than 0.05). After ACTH-(1-24) stimulation, the same patients had greater peak and time-integrated DHEA concentrations (P less than 0.03). The ED50 values of the cortisol dose-response curves were similar in patients and normal women (P less than 0.05), suggesting that there are no differences in the sensitivity of the adrenal cortex to ACTH between the acne patients and the controls studied. The ratio of DHEA to cortisol response was significantly elevated in women with acne compared to that in control women, suggesting some preponderance of the delta 5 pathway of steroidogenesis in acne (P less than 0.05). These findings of basal and ACTH-stimulated hypersecretion of delta 5-androgens in patients with postaldolescent acne are consistent with an increased volume of androgen-secreting tissue, rather than hypersensitivity of the adrenal zona reticularis to ACTH.

Acne Vulgaris↗

PubMed1991

Genetic variation of the glucocorticoid receptor from a steroid-resistant primate.

The neotropical cotton-top marmoset (Saguinus oedipus) is a New World primate known to have markedly increased total and free plasma cortisol concentrations when compared with Old World primates including man. The relative end-organ 'resistance' to glucocorticoids found in various New World primates has been attributed to a glucocorticoid receptor (GR) with diminished affinity for glucocorticoids. It has been demonstrated that the marmoset GR has approximately tenfold lower binding affinity for dexamethasone when compared with the human GR. We have examined the primary structure of the marmoset GR by molecular cloning and sequencing of GR functional domains. A library of cDNA clones was constructed in the phage vector gamma gt10 using poly(A)+ RNA from a marmoset-derived lymphoid cell line, and screened using the human GR cDNA. DNA sequencing determined 76 individual nucleotide substitutions in the coding region of the marmoset GR. Comparison of the marmoset GR nucleotide sequence with the human GR cDNA coding region indicated an overall sequence homology of about 97%. Thirty of the nucleotide substitutions lead to alterations in the predicted amino acid sequence (28 amino acid substitutions) of the marmoset GR. The size of the marmoset GR predicted from the 778 amino acids is approximately 90,000 which is in agreement with previous size estimates of the human and marmoset GRs. Alterations of amino acid sequence in the marmoset GR were greatest towards the amino terminus, including the tau 1 domain putatively involved in transcriptional activation. The DNA-binding domain contained an additional codon (arginine).(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗

PubMed1991

Corticotropin-releasing hormone testing in pituitary disease.

The availability of CRH for clinical use and the data so far generated by clinical investigators interested in its application to the problem of Cushing's syndrome have resulted in a new approach to the differential diagnosis of Cushing's syndrome (Fig. 2). Once the diagnosis of Cushing's syndrome is made with certainty, an initial separation into ACTH-dependent versus ACTH-independent categories is made on the basis of the plasma ACTH response to CRH. Plasma ACTH levels in excess of 10 pg/mL imply an ACTH-dependent process. Patients with an ACTH-dependent process are then divided into eutopic versus ectopic sources on the basis of the central to peripheral gradient of ACTH measured in the inferior petrosal sinuses simultaneously 3 to 5 minutes after the administration of CRH, 1 microgram/kg. The average post-CRH gradient in patients with eutopic ACTH-dependent Cushing's syndrome is 50. The lower bound is 3.3. Ectopic sources have a gradient of less than 2. Patients with ACTH-independent Cushing's syndrome can be confidently evaluated with imaging techniques, such as CT or MRI, looking for adrenal neoplasm or the "normal to small" glands characteristic of micronodular adrenal dysplasia.

Adrenal Gland Neoplasms↗

PubMed1991

The treatment of Cushing's syndrome and adrenal cancer.

Cushing's syndrome can be classified as either ACTH-dependent or ACTH-independent, and appropriate treatment depends on an accurate differential diagnosis as the treatment modality is different for each category. This article details the therapies now being used and their success rates.

Adrenal Gland Neoplasms↗

PubMed1990

Cortisol production rate in childhood and adolescence.

We studied the daily cortisol production rate in 33 normal children and adolescents, using a stable isotope-dilution technique employing high-performance liquid chromatography-mass spectrometry. Two indwelling intravenous catheters were inserted and tracer 9,12,12-2H3-cortisol (deuterated cortisol) was infused continuously for 30 hours. After 6 hours of tracer infusion to allow for equilibration, blood was obtained every 20 minutes for 24 hours. The mean (+/- SD) cortisol production rate was 9.5 +/- 2.5 mg/day (6.8 +/- 1.9 mg/m2/day). Cortisol production rate did not vary with sex or pubertal stage. These results suggest that the cortisol production rate in children and adolescents is significantly lower than previously estimated.

Adolescent↗

PubMed1990

Petrosal sinus sampling: discordant lateralization of ACTH-secreting pituitary microadenomas before and after stimulation with corticotropin-releasing hormone.

Petrosal sinus sampling was performed 171 times in 157 patients with known or suspected Cushing disease. In all cases, samples for measuring adrenocorticotropic hormone (ACTH) levels were obtained from both inferior petrosal sinuses and a peripheral vein, both before and after intravenous corticotropin-releasing hormone (CRH) administration. In seven examinations in seven patients, a ratio, or gradient, between the ACTH levels in the inferior petrosal sinuses existed in the samples obtained prior to CRH stimulation; however, poststimulation samples demonstrated reversal of the gradient, suggesting lateralization to the contralateral side of the pituitary gland. Data from surgical exploration of the pituitary gland were available for six of these patients, all of whom had adenomas. Prestimulation samples provided correct lateralization in three patients, and in two patients the poststimulation samples provided correct lateralization. One patient had a midline adenoma. When the results of pre- and poststimulation petrosal sinus sampling conflict, neither can be relied on uniformly to provide correct lateralization of ACTH-secreting pituitary adenomas.

Adenoma↗

PubMed1990

Primary cortisol resistance presenting as isosexual precocity.

Primary cortisol resistance (PCR) is a rare cause of hypercortisolism and usually does not produce clinical manifestations. This report describes primary cortisol resistance in a boy with isosexual precocity. A 6 7/12-yr-old boy had Tanner stage 3 pubic hair, accelerated linear growth, and advanced bone age (10 yr), but normal (for age) tests. There were no features of glucocorticoid excess. Serum androstenedione and dehydroepiandrosterone concentrations were 4.7 +/- 0.3 nmol/L (mean +/- SEM of four measurements; normal less than 1.2) and 13.5 nmol/L (single measurement; normal, 1.0-2.2), respectively. The serum testosterone concentration was 0.9 nmol/L (normal, less than 0.7), and FSH and LH were normal. Serum cortisol concentrations were 1590 +/- 110 nmol/L (normal, 190-630) and 580 +/- 60 nmol/L (normal, 50-410) at 0800 and 2000 h, respectively. Serum cortisol responded normally to insulin-induced hypoglycemia. Glucocorticoids and adrenal androgens were resistant to suppression by dexamethasone. The Kd of [3H]dexamethasone binding to the glucocorticoid receptors of mononuclear leukocytes was increased (6.4 +/- 0.8 nM; mean +/- SEM of four determinations; normal, 1.4-3.4; P less than 0.001), but the binding capacity was normal. This patient with isosexual precocity has PCR, as indicated by functionally abnormal glucocorticoid receptors and hypercortisolism without other clinical or biochemical manifestations of Cushing's syndrome. Excessive adrenal stimulation by ACTH caused increased secretion of both cortisol and adrenal androgens, and the latter caused the clinical manifestations. PCR should be considered in other male children with isosexual precocity or female children with heterosexual precocity.

Adrenal Glands↗