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Biomedical subjects

D L Loriaux

Publications and source records attributed to D L Loriaux.

At least 163 records · Page 9Linked to original sources
PubMed1986

Pulsatile administration of human corticotropin-releasing hormone in patients with secondary adrenal insufficiency: restoration of the normal cortisol secretory pattern.

Human corticotropin-releasing hormone (hCRH) was administered in a pulsatile fashion to eight patients with secondary adrenal insufficiency. These patients were selected on the basis of a normal or exaggerated plasma ACTH response to exogenous ovine CRH, suggesting sparing of the corticotrophs. A continuous 48-h iv infusion of ACTH to restore the adrenal glands to an ACTH-responsive state preceded hCRH administration. Eight 1 microgram/kg bolus injections of hCRH were administered in a 24-h period. The time intervals between hCRH injections were selected to resemble the frequency of spontaneously occurring secretory episodes of plasma ACTH and cortisol. Four of the patients underwent a second study, of identical design, in which normal saline injections were administered instead of hCRH. Pulsatile hCRH treatment resulted in a secretory pattern of ACTH and cortisol similar to that in normal subjects. ACTH and cortisol levels during saline administration were low and had no circadian variation. These findings indicate that exogenous CRH is able to restore normal basal ACTH and cortisol secretory patterns when given in an appropriate manner. It is possible that the pulsatile administration of hCRH may prove to be a more physiological technique for restoring adrenal function of patients with corticotroph-sparing secondary adrenal insufficiency and may avoid some of the complications of glucocorticoid administration.

Adrenal Insufficiency↗
PubMed1986

Glucocorticoid receptors in Epstein-Barr virus-transformed lymphocytes from patients with glucocorticoid resistance and a glucocorticoid-resistant New World primate species.

Members of a previously reported family with glucocorticoid resistance and several New World primates have high plasma cortisol concentrations without any signs of glucocorticoid excess. The glucocorticoid receptor in circulating leukocytes and cultured skin fibroblasts from these patients and the animals is characterized by a decreased affinity for dexamethasone. On the other hand, the cell content of receptor is similar to that of corresponding tissues of normal humans. Detailed biochemical-biophysical studies of the glucocorticoid receptor in this familial syndrome and animal model became possible with the use of Epstein-Barr virus-transformed lymphocyte lines. Cell lines from patients with this syndrome and from the marmoset (Saguinus oedipus) contained decreased amounts of glucocorticoid receptors with concomitant decreases in nuclear receptor content compared to cultured Epstein-Barr virus-transformed lymphocytes from normal human subjects. This may reflect diminished induction of glucocorticoid receptor during viral transformation of cells from the patients and the animal model. Receptors from a severely affected glucocorticoid-resistant patient and the marmoset had decreased affinity for dexamethasone. Evidence for a mild affinity defect of the glucocorticoid receptor in a patient with asymptomatic glucocorticoid resistance was obtained by increased hormone-receptor dissociation at an elevated temperature. Thermal stability, mero-receptor formation, thermal activation of cytosolic receptor, and mol wt of receptors from all cell lines were normal. Only the receptors of the severely affected patient had a discernible defect in temperature-induced activation of intact cells. We conclude that the major detectable change in the receptor in both the patients and the animal model is the decreased affinity for glucocorticoid. Viral receptor induction is decreased in both patient and marmoset cells. The physiological relevance of this phenomenon is not known. Gross receptor molecule changes or changes in its stability at higher temperatures were not found. Mixing studies did not show involvement of cytosolic modifiers or inhibitors. Mutation(s) of the receptor molecule leading to low affinity for the hormone is the most likely explanation of the isolated glucocorticoid resistance in the patients. The glucocorticoid resistance of the New World primate, which is part of generalized steroid hormone resistance, appears to be a result of more complex changes.

Animals↗
PubMed1986

Growth hormone (GH) responses to GH-releasing hormone during pubertal development in normal boys and girls: comparison to idiopathic short stature and GH deficiency.

The normal ranges for GH responses to GH-releasing hormone (GHRH) have previously been defined for adult men and women. To determine whether the GHRH responses of normal children differ from those of adults and whether children with GH deficiency (GHD) and children who are growing below the first percentile but are otherwise normal (ISS) have GH responses comparable to those of normal children, we studied 90 normal children, 46 girls and 44 boys, with heights between the 10th and 95th percentiles for age, at different pubertal stages. Their responses were compared to those of 24 children with ISS and 32 children with GHD and to values previously measured in young adult men and women. Girls were grouped by Tanner breast stages and boys by testicular volumes. Plasma somatomedin-C, estradiol or testosterone, and bone age were measured in all children. All received a 1 microgram/kg iv bolus dose of GHRH-(1-44)NH2, and GH responses were measured during a 2-h sampling period. Incremental serum GH responses in girls did not change throughout pubertal development and were similar to those of adult women. The responses in boys at midpuberty were somewhat lower (P less than 0.05) than those in either prepubertal boys or adult men. ISS children had mean GH responses [23 +/- 4 (+/- SE) ng/ml] similar to those of normal children. GHD children had significantly lower mean GH responses (11 +/- 3.7 ng/ml) than normal prepubertal children (35 +/- 4.0 ng/ml; P less than 0.01), but the responses of 17 of the 32 GHD children overlapped with the normal range. GH responses to GHRH were not correlated with bone age, weight, height, SmC levels, or estradiol or testosterone concentrations. These results indicate that GH responses to GHRH testing are relatively constant throughout puberty and young adulthood, that ISS children respond normally to GHRH, and that the GHRH test is not a reliable discriminator between individual normal and GHD children.

Adolescent↗
PubMed1986

Growth response relationship between growth hormone dose and short term growth in patients with Turner's syndrome.

Short stature is a common feature of Turner's syndrome. We studied the dose-response relationship between short term linear growth and GH dose using the lower leg-measuring device. Three doses of GH (0.05, 0.15, and 0.45 U/kg, three times weekly) were given sc for 1-month treatment periods. Lower leg growth rate increased significantly during treatment with the 0.15 and 0.45 U/kg doses [1.8 +/- 0.2 (+/- SEM) and 1.7 +/- 0.3 mm/4 weeks). The higher dose of 0.45 U/kg was no more effective than the 0.15 U/kg dose. Serum somatomedin-C levels increased after treatment with each of the three doses of GH, but did not differ in any of the three dosage groups. We conclude that 0.15 U/kg GH, three times weekly, stimulates short term growth in patients with Turner's syndrome. Longer term studies are required to determine if this increased growth rate is sustained.

Adolescent↗
PubMed1986

Adrenal steroid responses to continuous intravenous adrenocorticotropin infusion compared to bolus injection in normal volunteers.

We compared the adrenal steroid responses after synthetic ACTH-(1-24) (Cosyntropin) administration given by either continuous iv infusion or bolus injection in 11 normal women and 6 normal men. Each subject received 250 micrograms Cosyntropin as a bolus iv injection on 1 occasion and as a continuous 2-h iv infusion on another occasion, in random order. There was a 1-week interval between the studies. We measured the plasma levels of cortisol, 11-deoxycortisol, 17-hydroxyprogesterone, progesterone, pregnenolone, 17-hydroxypregnenolone, dehydroepiandrosterone, dehydroepiandrosterone sulfate, delta 5-androstenediol, androstenedione, and testosterone by RIA 15 and 0 min before and 30, 45, 60, and 120 min after administering ACTH. The steroid concentrations and their increments, ratios, or areas above baseline did not differ significantly between the bolus injection and the continuous infusion. Thus, at the dose of 250 micrograms, a bolus ACTH injection stimulates adrenal steroid secretion as effectively as a 2-h continuous ACTH infusion.

Adrenal Cortex Hormones↗
PubMed1986

Are catechol oestrogens obligatory mediators of oestrogen action in the central nervous system? I. Characterization of pharmacological probes with different receptor binding affinities and catechol oestrogen formation rates.

In an attempt to define pharmacological probes with which to test the role of catechol oestrogen formation in the central nervous system, five oestrogens (oestradiol-17 beta, oestradiol-17 alpha, 4-fluoro-oestradiol, 2-fluoro-oestradiol and moxestrol (11 beta-methoxy-17 alpha-ethynyloestradiol) were studied for binding to oestrogen receptors and conversion to catechol metabolites. Binding to cytosol oestrogen receptors was measured in the hypothalamus-preoptic area-amygdala (HPA), pituitary gland and uterus of ovariectomized rats. Conversion to catechol oestrogens was tested in microsomes from the HPA, pituitary gland and liver, using a catechol-O-methyltransferase-coupled radioenzymatic assay. Oestradiol-17 alpha was the only weak oestrogen receptor ligand. Binding affinities of the other compounds tested were much higher and comparable to those of oestradiol-17 beta. In contrast, oestradiol-17 alpha was rapidly converted to catechol metabolites, while moxestrol was a relatively poor substrate for catechol oestrogen formation. 4-Fluoro-oestradiol could be 2-hydroxylated but not 4-hydroxylated. 2-Fluoro-oestradiol exhibited impaired 2-hydroxylation but normal 4-hydroxylation.

Animals↗
PubMed1986

Are catechol oestrogens obligatory mediators of oestrogen action in the central nervous system? II. Potencies of natural and synthetic oestrogens for induction of gonadotrophin release and female sexual behaviour in the rat.

The role of catechol oestrogen formation in the mechanism by which circulating oestrogens facilitate gonadotrophin release and female sexual behaviour was explored in adult female rats. The effects of oestradiol-17 beta were compared with those of a group of oestrogens with either a reduced affinity for oestrogen receptors (oestradiol-17 alpha) or a reduced ability to act as substrates for catechol oestrogen formation (2-fluoro-oestradiol, 4-fluoro-oestradiol and moxestrol (11 beta-methoxy-17 alpha-ethynyloestradiol]. Rats were ovariectomized on the evening of dioestrus day 1 of the 4-day oestrous cycle and implanted s.c. 12 h later with infusion pumps containing either one of the test oestrogens or vehicle alone. Infusion rates for oestradiol-17 beta, moxestrol, 2-fluoro-oestradiol and 4-fluoro-oestradiol were adjusted to give concentrations of nuclear oestrogen receptors in the brain and pituitary gland within the range of those found in intact female rats during pro-oestrus. Oestradiol-17 alpha was infused at the same and at a tenfold higher rate than that of oestradiol-17 beta; neither of these treatments with oestradiol-17 alpha significantly increased brain or pituitary gland nuclear oestrogen receptor levels. On the day after the pump was implanted, samples of tail vein blood were withdrawn at 12.00, 14.00, 16.00 and 18.00 h for LH assay. All animals were then injected s.c. with 1 mg progesterone in propylene glycol, and tested for feminine sexual behaviour 5 h later. Oestradiol-17 beta, moxestrol, 2-fluoro-oestradiol and 4-fluoro-oestradiol all elicited pronounced LH surges and facilitated progesterone-triggered proceptive and lordosis behaviours.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Rebound thymic hyperplasia after treatment of Cushing's syndrome.

Rebound thymic hyperplasia has been described in children and young adults after recovery from stress. Similar thymic enlargement has been observed in patients after remission of Cushing's syndrome. In one patient successfully treated for ectopic adrenocorticotropic hormone (ACTH) syndrome by resection of a bronchial carcinoid with a hilar metastasis, the postoperative enlarging mediastinal mass suggested recurrent tumor. In another patient treated for an undetected ectopic ACTH source by a cortisol antagonist, the enlarging thymus could be confused with a thymic carcinoid. The typical thymic appearance on CT and the chronologic relation to declining cortisol levels should prevent such diagnostic errors.

ACTH Syndrome, Ectopic↗
PubMed1986

The ovine corticotropin-releasing hormone stimulation test and the dexamethasone suppression test in the differential diagnosis of Cushing's syndrome.

We gave a standard dexamethasone suppression test and an ovine corticotropin-releasing hormone (CRH) stimulation test to 41 patients with adrenocorticotrophic hormone (ACTH)-dependent hypercortisolism to determine the efficacy of each test in the differential diagnosis of Cushing's syndrome. Twenty-nine of thirty-three patients with Cushing's disease and 0 of 8 patients with ectopic secretion of ACTH responded to the ovine CRH test with increased levels of cortisol. When a cortisol response was judged as positive for Cushing's disease, the CRH test had a diagnostic sensitivity, specificity, and accuracy of 88%, 100%, and 90%, respectively. Twenty-nine patients with Cushing's disease and 1 patient with ectopic secretion of ACTH responded to the dexamethasone suppression test. A combined-test strategy requiring negative results from both tests to exclude a diagnosis of Cushing's disease yielded superior sensitivity (100%) and diagnostic accuracy (98%). Thus, the ovine CRH test works as well as the standard dexamethasone suppression test in discriminating between Cushing's disease and ectopic ACTH secretion. The diagnostic power of each test is enhanced when the two tests are combined.

17-Hydroxycorticosteroids↗
PubMed1986

Ultrasonography of Turner's syndrome.

Pelvic sonographic studies were performed on 15 phenotypic females with Turner's syndrome and varying X chromosome abnormalities. In those individuals with the 45XO karyotype, the ovaries were not visible, consistent with the classic description of absent or fibrous streak ovaries. The patients who were chromosomal mosaics showed a range of findings from absent to infantile to normal adult-size ovaries. Turner's syndrome should be suggested in individuals with delayed onset of puberty, primary amenorrhea, and short stature in whom pelvic ultrasonography fails to reveal ovaries. On the other hand, the detection of ovarian tissue by pelvic ultrasonography does not exclude the diagnosis of Turner's syndrome but does suggest that an X chromosomal abnormality other than 45XO is probably present.

Adolescent↗
PubMed1985

Pharmacologic suppression of the fetal adrenal gland in utero. Attempted prevention of abnormal external genital masculinization in suspected congenital adrenal hyperplasia.

21-Hydroxylase deficiency results in congenital adrenal hyperplasia and leads to masculinization of the external genitalia of affected females. This complication could be avoided if fetal adrenal gland function were suppressed. A woman with mild 21-hydroxylase deficiency whose previous female child had classic congenital adrenal hyperplasia with masculinization was given dexamethasone beginning at the tenth week of gestation. Maternal estriol and cortisol values indicated rapid and sustained fetal and maternal adrenal gland suppression. At 39 weeks' gestation, the patient was spontaneously delivered of a female neonate with normal external genitalia. Postnatal tests indicated the infant was a single heterozygote for 21-hydroxylase deficiency. This study demonstrates prolonged suppression of the fetal adrenal gland with dexamethasone and suggests it might prevent abnormal masculinization in fetuses with severe congenital adrenal hyperplasia.

Adrenal Cortex↗
PubMed1985

Precocious puberty associated with neurofibromatosis and optic gliomas. Treatment with luteinizing hormone releasing hormone analogue.

Seven children with central precocious puberty and either neurofibromatosis and/or optic gliomas were referred to the National Institutes of Health, Bethesda, Md, for evaluation and treatment with the long-acting luteinizing hormone releasing hormone analogue (LHRHa) D-Trp6-Pro9-NEt-LHRH. Only six of the seven children chose to receive treatment. Four children presented with neurofibromatosis, three of whom also had optic gliomas; the remaining three children had isolated optic gliomas, without other neurocutaneous stigmas. All had central precocious puberty mediated by activation of the hypothalamic-pituitary-gonadal axis. Six months of LHRHa therapy caused suppression of gonadotropin and sex steroid levels, stabilization or regression of secondary sexual characteristics, and decreases in growth velocity and the rate of bone age maturation. We conclude that LHRHa therapy is effective in the treatment of central precocious puberty secondary to neurofibromatosis and/or optic gliomas.

17-alpha-Hydroxyprogesterone↗
PubMed1985

Pituitary and gonadal function in the infant son of a patient with hypogonadotropic hypogonadism.

We have evaluated the pituitary-gonadal function of the infant son of a patient with hypogonadotropic hypogonadism. The father was treated with hCG and FSH to induce fertility. The son had normal external genitalia and his testicular volume increased appropriately during early infancy. Basal and post GnRH gonadotropin levels, as well as testosterone concentrations increased during early infancy. The data suggest that this infant had adequate gonadotropin secretion and testicular function. The patient illustrates the potential usefulness of evaluating the pituitary-gonadal function of male infants suspected of having hypogonadotropic hypogonadism.

Adult↗
PubMed1985

Effects of ketoconazole on rat testicular steroidogenic enzymatic activities.

Ketoconazole (K) is an antifungal imidazole derivative which has been shown to be a potent inhibitor of testosterone (T) biosynthesis in rodents and humans. To study the effect of K on rat testicular steroidogenesis we measured the activities of five testicular microsomal steroidogenic enzymes in K-treated rats and controls. Thirty male adult rats were given either 2 mg K or water every 12 hours by mouth during 5 days. Mean testicular weight was similar in both groups of animals. The K-treated group had a T serum concentration of 83 +/- 14 ng/dL whereas it was 94 +/- 16 ng/dL in the control group (NS). The K-treated animals had decreased activities of the 3 beta-hydroxysteroid dehydrogenase (830 +/- 48 vs 2,245 +/- 109 pmol/mg protein/min, P less than 0.001), 17-hydroxylase (243 +/- 5 vs 676 +/- 17 pmol/mg protein/min, P less than 0.001), 17-ketosteroid reductase (31 +/- 2 vs 169 +/- 7 pmol/mg protein/min, P less than 0.001), and aromatase enzymes (92 +/- 6 vs 123 +/- 7 pmol/mg protein/min, P less than 0.01). The 17,20-desmolase activity was similar in both groups of animals (210 +/- 4 vs 171 +/- 18 pmol/mg protein/min). We conclude that K given orally to rats inhibits the activity of several testicular steroidogenic enzymes.

17-Hydroxysteroid Dehydrogenases↗
PubMed1985

Corticotropin releasing factor: basic studies and clinical applications.

Corticotropin releasing factor (CRF) is a newly sequenced peptide first isolated from sheep hypothalami and thought to be an important modulator of both the pituitary-adrenal axis and the sympathetic nervous system. We administered intravenous, intramuscular, and intracerebroventricular CRH to non-human primates and measured plasma ACTH, beta endorphin, cortisol, GH and PRL responses to CRF. In addition, we determined the pharmacokinetic properties of I125 in these primates. We administered CRF as an intravenous bolus or as a continuous infusion to normal volunteers and as an intravenous bolus to patients with disorders of the hypothalamic-pituitary-adrenal axis, such as Cushing's syndrome and adrenal insufficiency, and patients with endogenous depression and mild hypercortisolism, and assessed their plasma ACTH, cortisol, GH and PRL responses. In addition, we determined the pharmacokinetic properties of CRF in man by measuring CRF immunoreactivity in plasma. CRF given intravenously to primates or man is a slowly metabolized, long-acting, secretagogue of ACTH, beta-endorphin and cortisol. When given intracerebroventricularly to primates it stimulates the hypothalamic-pituitary-adrenal axis without escaping into the plasma and it is actively cleared in the CNS. It does not cross the blood brain barrier appreciably when given intravenously. CRF given to primates and men as an intravenous continuous infusion has only mild ACTH stimulating effects and this may be due to an intact cortisol negative feedback system. Finally, CRF causes characteristic plasma hormone responses in patients with Cushing's disease, adrenal insufficiency and depression.

Adrenal Insufficiency↗