Plasma free metanephrine, normetanephrine, and 3-methoxytyramine for the diagnosis of pheochromocytoma/paraganglioma.

BACKGROUND: Pheochromocytomas (PHEO) and paragangliomas (PGL) are derived from paraganglia of the sympathetic and parasympathetic nervous system. Most of the sympathetic PHEO/PGL secrete either catecholamine or their metabolites, metanephrines, whereas parasympathetic PHEO/PGL are nonsecretory. We assessed the utility of plasma free 3-methoxytyramine (3MT), normetanephrine (NM), and metanephrine (MN) for the diagnosis of PHEO/PGL. MATERIALS AND METHODS: Sixty-five patients referred to endocrine/ENT clinics were enrolled. Twelve patients with von Hippel-Lindau (VHL), neurofibromatosis type 1 (NF1) and multiple endocrine neoplasia type 2 (MEN2) syndromes were excluded. Remaining 53 patients (39 patients with adrenal, abdominal, cervical and thoracic PHEO/PGL and 14 patients with head and neck PGL (HNPGL) were taken for this study. Sixty-five age- and sex-matched subjects were taken as controls. Plasma levels 3MT, NM, and MN were measured using high-performance liquid chromatography. Receivers operating characteristics was plotted and cut-off levels were established. RESULTS: When compared with controls, there was a 36-, 8.7- and 9.5-fold increase in levels of NM, 3MT and MN in the patients with PHEO/PGL and 7.2- and 2.7-fold increase in 3MT and NM, in the patients with HNPGL, respectively. In malignant PHEO/PGL, there was a 99-, 16- and 20-fold increase and in benign PHEO/PGL, there was 19-, 6.8- and 6.4-fold increase in levels of NM, 3MT, and MN, respectively. NM in combination with MN was high in 97% of the patients with PHEO/PGL. All three metabolites in combination were high in 83% of patients with HNPGL. In malignant PHEO/PGL, 50% subjects had increased levels of both NM and 3MT. CONCLUSIONS: Measurement of plasma-free NM along with 3MT and MN provides a better tool for the diagnosis of PHEO/PGL as well as HNPGL. Further, NM in combination with 3MT can be used for the diagnosis of malignant PHEO/PGL.

Clinical profile and inheritance pattern of CYP21A2 gene mutations in patients with classical congenital adrenal hyperplasia from 10 families.

CONTEXT: Congenital adrenal hyperplasia (CAH) is an autosomal recessive metabolic disorder caused by mutations in the CYP21A2 gene. Genetic diagnosis of 21-OH deficiency causing CAH is more complicated than any other monogenic disorder due to high variability of the locus. The disease has a wide spectrum of clinical variants making it difficult to establish a genotyp-phenotype correlation. Therefore, family studies are necessary to ascertain parental genotype and segregation of the mutant allele among the offspring. AIM: The present study aimed to identify CYP21A2 gene mutations and analyze the segregation pattern in CAH trios (patients and their parents). MATERIALS AND METHODS: A total of ten families having at least one CAH child were recruited. RESULTS: Out of 31 children from ten families, 15 were affected with CAH and 13 of/them (12 females and 1 male) were available for genetic testing. One family had all the children affected with CAH. Compound heterozygous mutations were identified in seven patients (53.8%) whereas p.P30L, In2 and Δ8 bp mutations were present in homozygous state in three (23.1%), two (15.3 %) and one (7.6%) patient respectively. CONCLUSIONS: In majority of the families, mutant alleles observed in the patients were inherited from the parents whereas three families showed sporadic mutations without any paternal or maternal origin. This indicated their novel occurrence due to misalignment of the parental genes and/or large deletion of the gene. Female preponderance was noted in the CAH families and also among the patients raising the possibility of survival advantage among females.

Phenotype, genotype and gender identity in a large cohort of patients from India with 5α-reductase 2 deficiency.

Deficiency of the 5α-reductase 2 enzyme impairs the conversion of testosterone to dihydrotestosterone (DHT) and differentiation of external genitalia, seminal vesicles and prostate in males. The present study describes the phenotype, genotype and gender identity in a large cohort of patients with 5αRD2. All patients underwent detailed clinical evaluation, hormonal profile, karyotyping and molecular analysis of the SRD5A2 gene. The molecular analysis of the SRD5A2 gene showed the presence of mutant alleles in 24 patients. We found 6 novel mutations IVS(1-2) T>C, p.A52T, 188-189insTA, 904-905ins A, p.A12T and p.E57X in our patients. All patients had ambiguous genitalia and the degrees of under-virilization ranged from penoscrotal hypospadias and microphallus to clitoromegaly. The position of gonads was variable in patients with same mutation. All the patients with mutations in the SRD5A2 gene had male gender identity. Those reared as female had gender dysphoria and underwent gender reassignment. Though a specific genotype-phenotype correlation could not be established in our patient but confirming the diagnosis of 5αRD2 with assessment of the SRD5A2 gene may help in appropriate gender assignment.

Plasma testosterone in adult normoglycaemic men: impact of hyperinsulinaemia.

This study analysed the relationship of plasma testosterone with ß-cell secretion, insulin sensitivity and other pituitary-target gland hormones in normoglycaemic adult men. The sample frame was the 'Offspring of individuals with diabetes study' database. A total of 358 offspring of individuals with type-2 diabetes (T2DM) and 287 individuals without known family history of T2DM were recruited for the study. Normoglycaemic men aged ≥18 years (maximum 55) were selected for this analysis. All participants underwent 75 g oral glucose tolerance test (OGTT); blood samples were collected at 0, 30, 60 and 120 min for plasma insulin and C-peptide. Total testosterone, cortisol, adrenocorticotropic hormone, thyroid stimulating hormone and thyroxine (T4) were measured in the fasting sample. A total of 164 men (age 28 ± 7.7 years) were included in analysis. Testosterone correlated negatively with BMI, waist to hip ratio (WHR), area under curve (AUC) of C-peptide and insulin (during OGTT) and was positively correlated with insulin sensitivity (r ~ 0.4). Cortisol and T4 positively correlated (weak) with testosterone (r ~ 0.2). In multivariate analysis, AUC C-peptide, BMI, WHR (negatively) and cortisol (positively) were related to testosterone. Concluding, testosterone correlated negatively with BMI and ß-cell secretion. There was a positive association of testosterone with insulin sensitivity, cortisol and T4.

Presentation and clinical course of Wolfram (DIDMOAD) syndrome from North India.

AIMS: Wolfram syndrome, also known as DIDMOAD, is a relatively rare inherited neurodegenerative disorder, first evident in childhood as an association of juvenile-onset diabetes mellitus and optic atrophy, followed by diabetes insipidus and deafness. The aim of the study was to examine the clinical profile of patients with DIDMOAD syndrome presenting to a tertiary care hospital in north India. METHODS: Clinical presentation of juvenile-onset diabetes mellitus fulfilling the diagnosis of Wolfram syndrome was studied using a prepared standardized form. RESULTS: Subjects with juvenile-onset non-autoimmune diabetes mellitus attending the diabetic clinic at a tertiary care centre in north India were followed for 10 years and a diagnosis of fully developed Wolfram syndrome was confirmed in seven individuals. The series consisted of five male and two female patients with a mean age of 17.5 ±7.34 years. Two subjects had consanguinity and none had any other family member affected. Optic atrophy was present in all, sensorineural hearing loss in 4/7, central diabetes insipidus in 4/7 and nephrogenic diabetes insipidus in 2/7 subjects. The new associations found were: spastic myoclonus, short stature with pancreatic malabsorption, nephrogenic diabetes insipidus, cyanotic heart disease and choledocholithiasis with cholangitis. Genetic analysis revealed mutation in exon 8 of the WFS1 gene in all the cases studied. CONCLUSIONS: The present clinical series of Wolfram syndrome reveals a varied clinical presentation of the syndrome and some new associations.

Association of subclinical hypothyroidism and phenotype, insulin resistance, and lipid parameters in young women with polycystic ovary syndrome.

OBJECTIVE: To determine whether subclinical hypothyroidism (SCH) alters the phenotype, insulin resistance, or lipid parameters in young women with polycystic ovary syndrome (PCOS). DESIGN: Prospective case-control study. SETTING: Tertiary care setting. PATIENT(S): Sixty-two young women with PCOS and SCH (group I) and 291 euthyroid women with PCOS (group II). INTERVENTION(S): Recording of clinical, biochemical, hormonal profile, and parameters of insulin resistance. MAIN OUTCOME MEASURE(S): Whether SCH has any association with clinical parameters like hirsutism, menstrual disturbances, lipid profile, and parameters of insulin sensitivity. RESULT(S): Mean (±SD) TSH was 7.13±1.28 IU/L in group I and 2.51±1.21 IU/L in group II, with comparable free triiodothyronine and free thyroxine. The two groups were comparable in age, weight, and body mass index. Parameters like blood pressure, menstrual pattern, and degree and duration of hirsutism did not differ between the two groups. Serum concentrations of triglycerides were significantly higher in the SCH group compared with controls. Plasma glucose concentrations both in fasting and after oral glucose tolerance test were similar between the two groups. Fasting insulin and other parameters of insulin resistance were not altered by SCH. CONCLUSION(S): Mild TSH elevation in the face of normal serum free triiodothyronine and free thyroxine results in a mild increase in serum lipids. Subclinical hypothyroidism is not associated with alteration in phenotypic expression and insulin resistance in young women with PCOS.

Spatial and seasonal distribution of nitrate-N in groundwater beneath the rice-wheat cropping system of India: a geospatial analysis.

Increased use of nitrogenous fertilizers in the intensively cultivated rice (Oryza sativa)-wheat (Triticum aestivum) cropping system (covers a 13.5-ha m area in South Asia) has led to the concentration of nitrates (NO(3)-N) in the groundwater (GW) in Haryana State of India. Six districts from the freshwater zone were selected to identify factors affecting NO(3)-N enrichment in GW. Water and soil samples were collected from 1,580 locations and analyzed for their chemical properties. About 3% (26,796, and 10,588 ha) of the area was estimated to be under moderately high (7.5-10 mg l( -1)) and high (>10 mg l( -1)) risk categories, respectively. The results revealed that NO(3)-N was 10-50% higher during the pre-monsoon season than in the monsoon season. Nitrate-N decreased with the increase in aquifer depth (r (2) = 0.99). Spatial and proximity analyses using ArcGIS (9.2) revealed that (1) clay material in surface and sub-surface texture restricts N leaching, (2) piedmont and rolling plains act as an N sink, and (3) perennial rivers bring a dilution effect whereas seasonal rivers provide favorable conditions for NO(3) (-) enrichment. The study concludes that chemical N fertilizers applied in agro-ecosystems are not the sole factor determining the NO(3) in groundwater; rather, it is an integrated process governed by several other factors including physical and chemical properties of soils, proximity and type of river, and geomorphologic and geographical aspects. Therefore, future studies should adopt larger area (at least watershed scale) to understand the mechanistic pathways of NO(3) enrichment in groundwater and interactive role of the natural drainage system and surrounding physical features. In addition, the study also presents a conceptual framework to describe the process of nitrate formation and leaching in piedmont plains and its transportation to the mid-plain zone.

Phenotype, hormonal profile and genotype of subjects with partial androgen insensitivity syndrome: report of a family with four adult males and one child with disorder of sexual differentiation.

There is little information on the molecular basis of intrafamilial and inter-familial phenotypic heterogeneity with the same androgen receptor (AR) mutation in patients with partial androgen insensitivity syndrome. A genetic analysis was performed in a large kindred with ambiguous genitalia and the genotype-phenotype correlations were analysed. The index case was brought for sex assignment. Family history revealed four other affected members who had hypospadias and varying degrees of virilisation. All the affected males had hemizygous mutations in the third exon of the AR gene (A596T). One was also found to have a heterozygous mutation in the fourth exon of the 5 alpha reductase type 2 gene (G196S). This affected male with double mutations was better virilised compared with the other affected members with a single mutation. The degree of virilisation correlated with serum testosterone levels. Gynaecomastia was not present in any of these subjects. It is concluded that the subject with dual gene defects also had higher levels of testosterone and pubertal virilsation. Testosterone levels possibly govern the degree of pubertal virilisation in subjects with A596T gene defects. It is not clear whether the better pubertal virilsation and higher testosterone are in any way causally related to the SRD5A2 gene defect.

Vitamin D nutritional status of exclusively breast fed infants and their mothers.

BACKGROUND: Vitamin D nutrition has a profound effect on the development of an infant. Vitamin D status of mothers and their infants are closely correlated. While hypovitaminosis D has emerged as a significant public health problem across all age groups, there is limited information of this condition in lactating mothers and their breast fed infants. AIM: To evaluate the vitamin D status of lactating mothers and their breast fed infants. SUBJECTS AND METHODS: 180 healthy lactating mothers and exclusively breast fed infants, 2-24 weeks old, were recruited for the study. The mother-infant pairs underwent concurrent clinical, biochemical and hormonal evaluation for calcium-vitamin D-PTH axis. RESULTS: The mean serum 25(OH)D values in lactating mothers was 27.2 +/- 14.6 nmol/l (10.9 +/- 5.8 ng/ml), while that of their infants was 28.9 +/- 20.8 nmol/l (11.6 +/- 8.3 ng/ml). Serum 25(OH)D levels <25 nmol/l (10 ng/ml) were found in 47.8% of the mothers and 43.2% of the infants. Among these, elevated PTH levels (>54 pg/ml) were seen in 59.3% of the mothers and 69.6% of the infants. A highly significant negative correlation was found between serum 25(OH)D and PTH in mothers (r = -0.480, p = 0.01) and their infants (r = -0.431, p = 0.01). A strong positive correlation was seen of 25(OH)D levels in mother-infant pairs (r = 0.324, p = 0.001). CONCLUSIONS: A high prevalence of vitamin D deficiency was found in lactating mothers and their exclusively breast fed infants. Infants born to mothers with hypovitaminosis D had 3.8 times higher risk of developing hypovitaminosis D as compared to those born to mothers with normal vitamin D levels.

Gender identity of children and young adults with 5alpha-reductase deficiency.

Male pseudohermaphroditism (46,XY DSD) due to 5alpha-reductase deficiency has been recognized for the last few decades. There is scant literature on this entity in India. We compiled data on five patients with this disorder. Four of our five patients were reared as females. Our assessment of these children reveals that they had male gender identity from childhood. Three of the four reared as females chose to change gender role at adolescence, while the fourth is still prepubertal. We conclude that all these patients had male gender identity from early childhood. The parents took note of this only after the appearance of male secondary sexual characteristics at puberty, thereby giving an impression of change in gender identity and gender role.

Comparison of efficacy of spironolactone with metformin in the management of polycystic ovary syndrome: an open-labeled study.

We compared the efficacy of spironolactone (50 mg/d) with metformin (1000 mg/d) after random allocation in 82 adolescent and young women with polycystic ovary syndrome (PCOS) on body mass index (BMI), waist-to-hip ratio, blood pressure, menstrual cyclicity, hirsutism, hormonal levels, glycemia, and insulin sensitivity at baseline and at the 3rd and 6th months of treatment. Sixty-nine women who completed the follow-up had a mean age of 22.6 +/- 5.0 yr and mean BMI of 26.8 +/- 4.0 kg/m2. The number of menstrual cycles in the spironolactone and metformin groups increased from 6.6 +/- 2.1 and 5.7 +/- 2.3 at baseline to 9.0 +/- 1.9 and 7.4 +/- 2.6 at 3rd month and to 10.2 +/- 1.9 and 9.1 +/- 2.0/ year at the 6th month (P = 0.0037), respectively. The hirsutism score decreased from 12.9 +/- 3.2 and 12.5 +/- 4.9 at baseline to 10.1 +/- 3.1 and 11.4 +/- 4.1 at the 3rd month and to 8.7 +/- 1.9 and 10.0 +/- 3.3 at the 6th month, respectively. Both groups showed improvement in glucose tolerance and insulin sensitivity, although the metformin effect was significant in the latter. Serum LH/FSH and testosterone decreased in both groups. BMI, waist-to-hip ratio, and blood pressure did not change with either drug. We conclude that both drugs are effective in the management of PCOS. Spironolactone appears better than metformin in the treatment of hirsutism, menstrual cycle frequency, and hormonal derangements and is associated with fewer adverse events.

Negative correlation between negative symptoms of schizophrenia and testosterone levels.

We conducted a pilot study in 10 adult male schizophrenics, 5 with predominantly positive symptoms (group I) and 5 with predominantly negative symptoms (group II), and 10 healthy matched controls. No significant differences in serum levels of testosterone (T), dehydroepiandrosterone sulfate (DHEAS), estradiol, and cortisol were found between patients as a whole and controls, using radioimmunoassay. However, serum T and DHEAS levels were lower (P <0.05) in group II patients than in group I. Body hair and aggression scores also were lower (P <0.05) in group II. In a much larger sample, Shirayama and colleagues also showed that "moderate negative symptoms, but not low negative symptoms" correlated negatively with T (P <0.05), but positively with ACTH (P <0.05) and cortisol (P <0.01) levels in plasma. Neuroactive steroids, such as DHEAS, and other sex hormones, including their synthetic derivatives, may have an adjunctive role in reversing or slowing the progression of negative symptoms. Indeed, "DHEA augmentation" improved "negative (P <0.01), depressive (P <0.05), and anxiety (P <0.01) symptoms."

Effect of PTU treatment on histone acetylation pattern in the developing rat brain.

The effect of hypothyroidism induced m female rats on histone acetylation pattern m the neonatal rat brain was studied. It is likely that thyroid hormone regulates the acetylation of histones and thereby influence their interaction with DNA and modulates transcription. Propylthiouracil (PTU), administered to induce hypothyroidism, resulted in a significant reduction m the thyroid and brain weight of neonatal rats. The circulating thyroxine levels were undetectable in both 14 and 21 day old pups. The hypothyroid condition was further confirmed by low levels of T4 (94.31 ng/g brain tissue vs 1811.29 ng/g in controls and 144.67 ng/g vs 1087.72 ng/g in controls at 14 and 21 days, respectively) and T3 (42.19 ng/g brain tissue vs 879.97 ng/g in controls and 60.62 ng/g vs 766.68 ng/g in controls at 14 and 21 days, respectively) in the neonatal rat brain. Histone acetylation pattern was similar in treated and control groups m the 14 day old rats. PTU treatment, however, resulted in significant (p<0.01) reduction in acetylation in the H3 fraction at 21 days whereas no such changes were recorded in other histone fractions. Lower histone acetylation in the 21 day old pups suggest a reduction m the transcriptional activity due to fewer initiation sites for RNA polymerase. It may be concluded that thyroid hormone may stimulate transcription of specific genes by increasing the acetylation of nucleosomal histones.

Late onset adrenal hyperplasia due to 3 beta-hydroxy-delta 5-steroid dehydrogenase deficiency in north Indian hirsute women.

The presence of late onset 3 beta-hydroxy steroid dehydrogenase (3 beta-HSD) type of congenital adrenal hyperplasia was studied in 58 north Indian hirsute women. The age range of these patients was 15 to 42 yr. Fifty two per cent of these patients had body mass index > 25. Basal serum testosterone, luteinizing hormone, follicle stimulating hormone, dehydroepiandrosterone sulphate (DHEAS), and 17 hydroxy progesterone (17 OHP) were estimated. All the patients underwent adrenocorticotropin (ACTH) stimulation test after an overnight dexamethasone suppression for the estimation of DHEAS, 17 OHP, and 17 hydroxy pregnenolone (delta 5-17p). Five (8.6%) hirsute women showed an exaggerated 17 OHP response to ACTH indicating 21-hydroxylase deficiency. Eight (13.8%) hirsute women had elevated basal DHEAS and ACTH-stimulated DHEAS as well as delta 5-17P responses indicative of 3 beta-HSD deficiency. In one patient hirsutism was the presenting manifestation of tumoural hyperandrogenism. Our findings indicate the presence of both 21-hydroxylase and 3 beta-HSD deficiency in north Indian hirsute women, with, 3 beta-HSD deficiency being the major cause of hirsutism in this population.

Atrial natriuretic peptide inhibits the phosphoinositide hydrolysis in murine Leydig tumor cells.

The ability of ANP to inhibit the hydrolysis of phosphoinositides was examined in [3H] myoinositol-labeled intact murine Leydig tumor (MA-10) cells. Arginine vasopressin (AVP) stimulated the formation of inositol monophosphate (IP1), inositol bisphosphate (IP2), and inositol trisphosphate (IP3) both in a time-and dose-dependent manner in MA-10 cells. ANP inhibited the AVP-induced formation of IP1, IP2, and IP3 in these cells. The inhibitory effect of ANP on the AVP-stimulated formation of IP1, IP2, and IP3 accounted for 30%, 38% and 42%, respectively, which was observed at the varying concentrations of AVP. ANP caused a dose-dependent attenuation in AVP-stimulated production of IP1, IP2 and IP3 with maximum inhibition at 100 nM concentration of ANP. The production of inositol phosphates was inhibited in the presence of 8-bromo cGMP in a dose-dependent manner, whereas dibutyryl-cAMP had no effect on the generation of these metabolites. The LY 83583, an inhibitor of guanylyl cyclase and cGMP production, abolished the inhibitory effect of ANP on the AVP-stimulated production of inositol phosphates. Furthermore, 10 microM LY 83583 also inhibited the ANP-stimulated guanylyl cyclase activity and the intracellular accumulation of cGMP by more than 65-70%. The inhibition of cGMP-dependent protein kinase by H-8, significantly restored the levels of AVP-stimulated inositol phosphates in the presence of either ANP or exogenous 8-bromo cGMP. The results of this study suggest that ANP exerts an inhibitory effect on the production of inositol phosphates in murine Leydig tumor (MA-10) cells by mechanisms involving cGMP and cGMP-dependent protein kinase.

Catalytic activation of guanylate cyclase/atrial natriuretic factor receptor by combined effects of ANF and GTP gamma S in plasma membranes of Leydig tumor cells: involvement of G-proteins.

Guanosine 5'-(gamma-thio)triphosphate (GTP gamma S) exhibited a modulatory role in the catalytic activation of guanylate cyclase-A/atrial natriuretic factor receptor (GC-A/ANF-R) in the plasma membrane preparations of murine Leydig tumor (MA-10) cells. Both atrial natriuretic factor (ANF) and GTP gamma S synergistically stimulated the guanylate cyclase (GC) activity of GC-A/ANF-R in a dose- and time-related manner. Other nucleotides and their analogs such as ATP, adenosine 5'-(gamma-thio)triphosphate, adenosine 5'-(beta,gamma-imino)triphosphate, GDP, and guanosine 5'-(2-O-thiodiphosphate) (100 microM each) did not show any discernible effect on GC catalytic activity of GC-A/ANF-R. A significant stimulation of GC activity was observed in the presence of mastoparan, AlF4-, and benzalkonium chloride. The saturation binding assay of [35S]GTP gamma S showed the dissociation constant (Kd) of 2.3 x 10(-9) M and the binding capacity (Bmax) of 76 pmol/mg protein in the plasma membrane preparations of MA-10 cells. ANF increased the [35S]GTP gamma S-binding capacity, however, without affecting its affinity constant. Pretreatment of plasma membranes with antibodies against Gs alpha subunit attenuates the GTP gamma S-stimulated GC activity, whereas antibodies against Gi alpha subunit enhanced the stimulatory effect of GTP gamma S on GC catalytic activity of GC-A/ANF-R. However, the antibodies against Go alpha subunit did not show any effect on GC activity. These results provide the evidence that both Gs and Gi subunits of G-proteins seem to be involved in the regulation of GC catalytic activity of GC-A/ANF-R in the plasma membranes of MA-10 cells.

Modulation of guanylate cyclase-coupled atrial natriuretic factor receptor activity by mastoparan and ANF in murine Leydig tumor cells: role of G-proteins.

Mastoparan potently stimulated catalytic activity of guanylate cyclase-coupled atrial natriuretic factor receptor (GC-A/ANF-R), both in the plasma membranes and intact Leydig tumor (MA-10) cells. In plasma membrane preparations, a maximum of 5-fold GC catalytic activity was stimulated by 100 microM mastoparan and the half maximum stimulation (EC50) was achieved at 40 microM concentration. Mastoparan potentiated GC activity by more than 40%, above the level, stimulated by ANF. Mas 7, an active analog of mastoparan, stimulated the GC activity in a similar manner to mastoparan whereas Mas 17, an inactive analog, did not enhance GC activity. In membranes prepared from mastoparan-treated intact MA-10 cells, GC catalytic activity was enhanced by more than 4-fold as compared with untreated control cells. Pretreatment of membranes with either anti-Gs alpha or anti-Gi alpha antibodies had no effect on mastoparan-stimulated GC activity, however, anti-Go alpha antibodies inhibited the stimulatory effect of mastoparan by almost 50%. Agents known to modulate the effect of mastoparan such as EGTA (Ca2+ chelator), W7 (calmodulin inhibitor) and staurosporine (protein kinase C inhibitor) had no effect on the mastoparan-stimulated GC activity. Mastoparan enhanced the ANF-stimulated GC activity in detergent solubilized membrane preparations without a significant change in ANF-binding capacity. The data establish a role for mastoparan in the ANF-dependent stimulation of GC-A/ANF-R catalytic activity, both in the plasma membrane preparations and intact Leydig tumor (MA-10) cells. Furthermore, these findings provide new evidence that mastoparan (isolated from wasp venom) potently stimulates guanylate cyclase activity of GC-A/ANF-R by activating G-proteins.

Receptor-mediated stimulatory effect of atrial natriuretic factor, brain natriuretic peptide, and C-type natriuretic peptide on testosterone production in purified mouse Leydig cells: activation of cholesterol side-chain cleavage enzyme.

We have investigated the mechanism by which different natriuretic peptides stimulate steroidogenesis in purified mouse Leydig cells. In addition to atrial natriuretic factor (ANF), we show that brain natriuretic peptide (BNP) and C-type natriuretic peptide (CNP) also stimulate testosterone production in these cells. Testosterone production was increased dramatically to 14-fold with ANF (EC50 = 0.3 nM) and 15-fold with BNP (EC50 = 0.2 nM); however, the CNP-stimulated level of testosterone production was only 2.5-fold compared with controls. ANF and BNP enhanced the stimulatory effect of LH on testosterone production. The C-ANF(4-23) (a truncated form of ANF) had no effect on testosterone production in these cells. ANF, BNP, and CNP stimulated the production of intermediate precursors of testosterone biosynthesis, which included progesterone, 17 alpha-hydroxy progesterone, androstenedione, pregnenolone, 17 alpha-hydroxy pregnenolone, and dehydroepiandrosterone sulfate. The conversion of pregnenolone and progesterone to testosterone was also significantly enhanced after treatment of Leydig cells with these peptides. All three natriuretic peptides (ANF, BNP, and CNP) stimulated the activity of particulate guanylate cyclase by 8.4-, 8.5-, and 4.8-fold and the accumulation of intracellular cGMP by 52-, 58-, and 19-fold, respectively. The cGMP inhibitor LY83583 attenuated both the generation of cGMP as well as testosterone in response to these natriuretic peptides, suggesting the involvement of cGMP as a second messenger. Leydig cells were found to contain high affinity and low capacity binding sites for ANF [dissociation constant (Kd), 2.0 x 10(-10) M; maximum binding capacity (Bmax). 20 fmol/1 x 10(5) cells], BNP (Kd, 2.2 x 10(-10) M; Bmax, 19 fmol/1 x 10(5) cells), and CNP (Kd, 3.1 x 10(-10) M; Bmax, 8.6 fmol/1 x 10(5) cells). The results presented here document that a family of different natriuretic peptides stimulates Leydig cell steroidogenesis in receptor-mediated fashion, beginning at the cholesterol side-chain cleavage enzyme. The data also show that these peptide hormones induce testosterone production in mouse Leydig cells by involving both delta 4- and delta 5-pathways of steroidogenesis.

Computed tomography in untreated congenital adrenal hyperplasia.

Six children with untreated congenital adrenal hyperplasia (CAH) were examined by computed tomography (CT). Three cases demonstrated diffuse enlargement of both adrenal glands with preservation of normal configuration and two showed tumorous transformation in one of the enlarged glands. One had equivocal enlargement of the adrenal gland. Even the youngest in this group (age 2 years) also showed bilateral hyperplasia.