The Journal of Clinical Endocrinology & Metabolism

Garnero, P; Arden, N K; Griffiths, G; Delmas, P D; Spector, T D

doi: 10.1210/jcem.81.1.8550741pmid: 8550741

AbstractPostmenopausal bone mass is determined by both peak bone mass and subsequent bone loss. Previous studies have shown that peak bone mass is under genetic influence mediated partly by factors affecting bone formation. The rate of bone loss increases markedly after the menopause, but is highly variable from subject to subject. The aims of this study were to determine whether postmenopausal bone turnover was under genetic control, which should be linked to the genetic influence on the rate of postmenopausal bone loss. A classical twin study was performed that compared the intraclass correlations in monozygotic (MZ) twins with those in dizygotic (DZ) twins, with any difference assumed to be due to genetic factors. Markers of bone formation and resorption were measured in 240 untreated postmenopausal twins, aged 45-69 yr, on the average 12.3 yr (SD, 6.0) postmenopause, including 61 MZ pairs and 59 DZ pairs. The intraclass correlation coefficient of MZ twin pairs, rMZ (95% confidence interval), for 2 specific markers of bone formation, serum osteocalcin and bone-specific alkaline phosphatase, were higher than the corresponding rDZ [0.67 (range, 0.59-0.75) vs. 0.48 (range, 0.35-0.61; P = 0.06) for osteocalcin and 0.53 (range, 0.41-0.65) vs. 0.21 (range, 0.01-0.41; P = 0.02) for bone-specific alkaline phosphatase]. For serum propeptide of type I collagen, a type I collagen synthesis marker that exhibits only a slight increase after menopause, a high proportion of its variance was explained by genetic factors [rMZ = 0.82 (0.77-0.87), rDZ = 0.33 (0.16-0.50); P < 0.001]. The correlations for bone resorption measured by three distinct urinary markers, total deoxypyridinoline and two cross-linked type I collagen peptides (CrossLaps and NTX), that increase markedly after menopause were higher in MZ than in DZ pairs, but the difference reached significance only for NTX (P = 0.03). For urinary free dexoypyridinoline, a marker reflecting bone collagen degradation that increases moderately after menopause, the proportion of the variance explained by genetic factors was highly significant (P = 0.002). In conclusion, our data indicate that a proportion of the variance in postmenopausal levels of both bone formation and resorption markers are explained by genetic factors, but this contribution was clearly significant only for markers that do not change markedly at the menopause. These data suggest that the contribution of genetic factors to overall postmenopausal bone turnover and possibly bone loss is likely to be small.

Holt, R I; Jones, J S; Stone, N M; Baker, A J; Miell, J P

doi: 10.1210/jcem.81.1.8550746pmid: 8550746

AbstractPediatric end-stage liver disease (ESLD) leads to poor linear growth and wasting. After orthotopic liver transplantation (OLT), catch-up growth occurs unpredictably and with a delay. The bulk of circulating insulin-like growth factor I (IGF-I) and its major circulating binding protein, IGF-binding protein-3 (IGFBP-3), is derived from the liver. We hypothesized that growth failure in ESLD, both before and after OLT, may result from abnormalities in the IGF-IGFBP axis. Serum IGF-I, IGFBP-1, and insulin were measured by RIA, and IGFBP-3 was determined by immunoradiometric assay in 26 children with ESLD (mean of 3.7 samples pre-OLT and 4.2 samples post-OLT per patient) and 30 age-matched controls. In addition, serum IGFBPs were visualized by Western ligand blotting. IGFBP-3 and IGFBP-2 were also observed by immunoblotting with specific antisera. IGFBP-3 protease activity was determined by protease gels using recombinant human IGFBP-3 label as substrate. Anthropometric measurements were performed according to standard techniques. Pre-OLT, IGF-I (32.7 +/- 4.8 micrograms/L), and IGFBP-3 (1.11 +/- 0.10 mg/L) were significantly lower than control values [IGF-I, 168.3 +/- 16.5 micrograms/L (P = 0.0001); IGFBP-3, 2.57 +/- 0.17 mg/L (P = 0.0001)]. Post-OLT, IGF-I (179.2 +/- 19.7 micrograms/L; P = NS) rose to control levels, whereas IGFBP-3 (3.49 +/- 0.14 mg/L; P = 0.002) became significantly greater than the control value. IGFBP-1 was significantly higher pre-OLT (78.9 +/- 9.6 micrograms/L; P = 0.0001) than post-OLT (45.7 +/- 6.9 micrograms/L), and both were significantly higher than control values (18.5 +/- 2.5 micrograms/L; P = 0.0001 vs. pre-OLT and P = 0.0002 vs. post-OLT). There was a trend toward higher insulin levels both pre-OLT (15.5 +/- 1.8 mU/L) and post-OLT (12.5 +/- 1.4 mU/L) compared with control values (9.7 +/- 1.1 mU/L; P = 0.06 vs. pre-OLT). IGFBP-1 was negatively correlated with serum insulin post-OLT (P = 0.008), but there was no correlation pre-OLT. Western ligand blotting confirmed the changes in IGFBP-3 pre- and post-OLT. Immunoblotting demonstrated a reduction in all mol wt forms of IGFVBP-3 pre-OLT. Protease assays demonstrated the appearance of IGFBP-3 proteolysis only at a time coincidental with the operative stress of OLT; overall, there was no difference in protease activity pre- and post-OLT. IGFBP-2 was unchanged post-OLT compared with pre-OLT, although levels were higher than control values. Mid-upper arm circumference and triceps skin fold thickness SD score 3 months post-OLT and weight SD score 1 yr post-OLT were significantly higher than those at OLT. In conclusion, IGF-I and IGFBP-3 are reduced, and IGFBP-1 and IGFBP-2 are increased in children with ESLD. After OLT, IGF-I levels return to normal, but marked abnormalities in IGFBPs remain. These changes may help to explain at least in part the growth failure seen in pediatric ESLD both before and after successful OLT.

Laflamme, N; Leblanc, J F; Mailloux, J; Faure, N; Labrie, F; Simard, J

doi: 10.1210/jcem.81.1.8550762pmid: 8550762

AbstractCongenital adrenal hyperplasia (CAH) is the most frequent cause of adrenal insufficiency and ambiguous genitalia in newborn children. In contrast to CAH caused by 21 alpha-hydroxylase and 11 beta-hydroxylase deficiencies, which impairs steroid formation in the adrenal exclusively, 17 alpha-hydroxylase/17,20-lyase deficiency impairs steroid biosynthesis in the adrenals and gonads. The sequence of CYP17 gene was determined by direct sequencing of asymmetric PCR products in two French-Canadian 46,XY pseudohermaphrodite siblings suffering from combined 17 alpha-hydroxylase/17,20-lyase deficiency. The two patients are homozygous for the novel missense mutation R96W caused by a C to T transition converting codon Arg96 (CGG) into a Trp (TGG) in exon 1. The both parents are heterozygous for this missense mutation. We assessed the effect of the R96W mutation on 17 alpha-hydroxylase/17,20-lyase activity by analysis of mutant enzyme, generated by site-directed mutagenesis, expressed in COS-1 cells. The presence of R96W substitution almost completely abolished the activity of the mutant protein. The present findings provide a molecular explanation for the signs and symptoms of combined 17 alpha-hydroxylase/17,20-lyase deficiency in these two patients and provide useful information on the structure-activity relationships of the P450c17, enzyme.

Willis, D; Mason, H; Gilling-Smith, C; Franks, S

doi: 10.1210/jcem.81.1.8550768pmid: 8550768

AbstractAnovulation in polycystic ovary syndrome (PCOS) is associated with hyperinsulinemia and insulin resistance, but it has been unclear whether the ovary is insulin resistant in women with PCOS. The aims of this study were, firstly, to determine whether human granulosa cells respond to physiological concentrations of insulin and, secondly, to investigate insulin and gonadotropin interactions in vitro in granulosa cells obtained from normal (N) and polycystic ovaries (PCO). Granulosa cells were incubated with insulin with or without gonadotropins for 48 h. Insulin augmented not only basal production of estradiol and progesterone, but also LH-stimulated steroid accumulation in granulosa cell cultures from N and PCO. Insulin enhanced FSH-stimulated progesterone production by granulosa cells from N and PCO, but the effect on FSH-stimulated estradiol production was variable, ranging from no effect for granulosa cells from N to synergistic for granulosa cells from PCO of anovulatory subjects. Preincubation with insulin for 48 h increased subsequent basal and LH-induced, but not FSH-stimulated, steroid production. These data demonstrate that granulosa cells from PCO respond to insulin despite the association, in vivo, of PCOS with peripheral insulin resistance. Insulin preincubation enhances the subsequent response of human granulosa cells to LH. We propose that in anovulatory women with PCOS, elevated levels of insulin interacting with LH may contribute to the mechanism of anovulation.

Yoshida, T; Shimatsu, A; Sakane, N; Hizuka, N; Horikawa, R; Tanaka, T

doi: 10.1210/jcem.81.1.8550769pmid: 8550769

AbstractWe describe a case of pituitary gigantism with low levels of growth hormone (GH), elevated insulin-like growth factor-I (IGF-I), and IGF-binding protein-3 (IGF-BP-3). The patient had characteristic clinical features of gigantism and acromegaly. The basal serum GH levels ranged from 1.2-1.9 micrograms/L, which were considered to be within normal limits. Serum GH response to either insulin-induced hypoglycemia or GH-releasing hormone was blunted. Frequent blood samplings during daytime and at night showed nonpulsatile GH secretion. Serum prolactin, IGF-I and IGF-binding protein-3 levels were elevated. After unsuccessful surgery, bromocryptine treatment normalized serum prolactin without affecting serum GH and IGF-I levels. Combined administration of octreotide and bromocryptine reduced serum GH and IGF-I levels. GH bioactivity as measured by Nb2 cell proliferation assay was within reference range. In the present case, nonpulsatile GH secretion and enhanced tissue sensitivity to GH may induce hypersecretion of IGF-I and IGF-BP-3 and cause clinical acromegalic gigantism.

Okuda, Y; Adrogue, H J; Field, J B; Nohara, H; Yamashita, K

doi: 10.1210/jcem.81.1.8550770pmid: 8550770

AbstractAlthough a growing body of evidence supports that alkali therapy in diabetic ketoacidosis (DKA) might be counterproductive, our knowledge about the consequences of this treatment on ketone metabolism is limited. Consequently, we performed clinical and animal studies to further examine this topic. The clinical studies assessed seven patients with DKA treated with continuous insulin infusion at a low dosage. Three of them also received sodium bicarbonate (NaHCO3), whereas the remaining four acted as controls. The group receiving NaHCO3 showed a 6-h delay in the improvement of ketosis as compared with controls. In addition, there was an increase in acetoacetate (AcAc) levels during alkali administration, followed by an increase in 3-hydroxybutyrate (3-OHB) level after its completion. Significant differences were not found between groups in the response of plasma glucose to the overall therapy. The animal study examined the effects of a NaHCO3-rich perfusate on the hepatic production of ketones with the in situ rat-liver preparation. Alkali loading resulted in an immediate increase in the AcAc level followed by increases in both the 3-OHB level and the 3-OHB/AcAc ratio after its completion. Hepatic ketogenesis increased even further, to about twice the basal level, after termination of the NaHCO3 loading. This investigation confirms that alkali administration augments ketone production and unravels an effect of bicarbonate infusion that promotes a selective build up of AcAc in body fluids. The data support that alkali therapy in DKA has nonsaltuary effects in the metabolism and plasma levels of ketones.

Johnston, L B; Carroll, M J; Britton, K E; Lowe, D G; Shand, W; Besser, G M; Grossman, A B

doi: 10.1210/jcem.81.1.8550776pmid: 8550776

AbstractPrimary hyperparathyroidism is a common condition due to either a parathyroid adenoma or, less commonly, parathyroid hyperplasia, whose treatment is essentially surgical. We have, therefore, assessed the accuracy of Tc-99m pertechnetate/Tc-99m sestamibi (methoxy-isobutyl isonitrile) imaging in the localization of adenomas and hyperplastic parathyroids. The clinical records of all patients who had Tc-99m pertechnetate/Tc-99m sestamibi imaging and parathyroid surgery at this hospital were reviewed. The technique used involves standard subtraction methodology with the addition of a novel change detection algorithm to optimize localization. Of 46 patients scanned in 48 patient episodes, 36 patients had adenomas; 28 (78%) were accurately localized to the correct quadrant, and 4 were correctly lateralized. Two patients with parathyroid carcinomas had their metastases correctly localized. Thus, in 34 of 38 (89.5%) of the scans, adenomas or carcinomas were able to be anatomically localized. Six patients presented with hyperplasia; 5 were diagnosed by sestamibi scans, and 3 of these accurately localized all hyperplastic glands. Four additional patients had known hyperplasia, of which 2 were rendered normocalcemic after removal of their sestamibi-positive glands; the other 2 had small second glands detected only at surgery. In patients with unknown pathology, imaging suggested that 6 patients had hyperplasia; this was correct in 5 cases (83%). Nine of the 12 scans in patients who had had previous parathyroid surgery accurately localized the tumors, 7 in the neck and 2 outside. We suggest that sestamibi imaging can help to distinguish hyperplasia from adenomatous disease; when imaging is required, we recommend it as the imaging modality of choice in all patients with primary hyperparathyroidism, especially in reoperated patients.

Kimura, N; Ishikawa, T; Sasaki, Y; Sasano, N; Onodera, K; Shimizu, Y; Kimura, I; Steiner, D F; Nagura, H

doi: 10.1210/jcem.81.1.8550783pmid: 8550783

AbstractAn autopsy case of ACTH-producing thymic carcinoid with Cushing's syndrome is reported. The patient was a 63-yr-old man with multiple bone metastases from an undetermined primary site. Hyperpigmentation was observed at the terminal stage. The plasma levels of ACTH, cortisol, chromogranin A, and urinary 17-hydroxy-corticosteroids were extremely high, and ectopic ACTH-producing neuroendocrine tumor was diagnosed. In addition, plasma CRH was high. Autopsy revealed that the patient had primary thymic carcinoid with extensive metastases. Remarkable hyperplasia of the adrenal cortexes and Crooke's hyaline degeneration of the pituitary gland were consistent with Cushing's syndrome by ectopic ACTH production. There were multiple CRH-producing cells without degenerative changes in the hypothalamus. The tumor cells were immunoreactive to ACTH, CRH, and the cleavage enzyme PC2. POMC messenger ribonucleic acid and PC2 messenger ribonucleic acid were detected in the tumor cells by an in situ hybridization method. Expression of PC2 was considered to induce hyperpigmentation by producing alpha MSH. Despite hypercortisolism and ectopic production of CRH by the tumor cells, hypothalamic CRH cells were not atrophic. This case is a good example to demonstrate the correlation between CRH and the hypothalamo-pituitary-adrenal axis as well as hyperpigmentation in Cushing's syndrome.