Publications

Abstract Glucocorticoids play central roles in the regulation of energy metabolism by shifting it toward catabolism, whereas AMP-activated protein kinase (AMPK) is the master regulator of energy homeostasis, sensing energy depletion and stimulating pathways of increasing fuel uptake and saving on peripheral supplies. We showed here that AMPK regulates glucocorticoid actions on carbohydrate metabolism by targeting the glucocorticoid receptor (GR) and modifying transcription of glucocorticoid-responsive genes in a tissue- and promoter-specific fashion. Activation of AMPK in rats reversed glucocorticoid-induced hepatic steatosis and suppressed glucocorticoid-mediated stimulation of glucose metabolism. Transcriptomic analysis in the liver suggested marked overlaps between the AMPK and glucocorticoid signaling pathways directed mostly from AMPK to glucocorticoid actions. AMPK accomplishes this by phosphorylating serine 211 of the human GR indirectly through phosphorylation and consequent activation of p38 MAPK and by altering attraction of transcriptional coregulators to DNA-bound GR. In human peripheral mononuclear cells, AMPK mRNA expression positively correlated with that of glucocorticoid-responsive glucocorticoid-inducible leucine zipper protein, which correlated also positively with the body mass index of subjects. These results indicate that the AMPK-mediated energy control system modulates glucocorticoid action at target tissues. Because increased action of glucocorticoids is associated with the development of metabolic disorders, activation of AMPK could be a promising target for developing pharmacological interventions to these pathologies.

The immediate effect of Boston brace removal on plasma levels of atrial natriuretic peptide and arginine vasopressin was studied in 10 patients with idiopathic scoliosis ranging in age from 12 to 16 years. Blood samples were drawn via the antecubital vein in the supine position with the brace on and 10 min after brace removal. ANP and AVP plasma levels were measured by radioimmunoassay. Although no differences were found in the plasma concentrations of arginine vasopressin while on and after removal of the brace, atrial natriuretic peptide levels showed an approximately 80 percent increase 10 min after brace removal, presumably due to central volume redistribution. The changes of atrial natriuretic peptide plasma levels observed may be related to previously reported changes of the glomerular filtration rate and urinary sodium excretion following brace removal.

Previous studies on the effects of altered thyroid function on the secretion and metabolism of adrenocortical hormones suggest a degree of adrenocortical hyperactivity in hyperthyroidism. We have previously shown that experimentally-induced hyperthyroidism is associated with significant alterations in pituitary-adrenal responsiveness to synthetic ovine corticotropin-releasing hormone (oCRH) that are contingent upon the duration of the altered thyroid function. The purpose of this study was to assess the time-dependent effects of hyperthyroidism on the functional integrity of the hypothalamic-pituitary-adrenal (HPA) axis by in vivo stimulation of the hypothalamic CRH neuron and adrenal cortex.The functional integrity of the HPA axis was examined in vivo in sham-thyroidectomized male Sprague-Dawley rats given placebo or in thyroidectomized rats given 50 mug of thyroxine every day for 7 or 60 days. Responses to insulin-induced hypoglycemia and IL-1alpha stimulation were used to assess the hypothalamic CRH neuron. Adrenocortical reserve was assessed in response to low-dose adrenocorticotropic hormone (ACTH), following suppression of the HPA axis with dexamethasone. Adrenal and thymus tissue weight, in addition to basal plasma ACTH, corticosterone and thyroid indices were also determined.Basal plasma corticosterone and corticosterone binding globulin (CBG) concentrations were significantly increased in short- and long-term hyperthyroid rats, and by 60 days, cerebrospinal fluid (CSF) corticosterone levels were significantly increased. Basal plasma ACTH levels were similar to controls. Although plasma ACTH responses to hypoglycemic stress and IL-1alpha administration in both short- and long-term hyperthyroidism were normal, corticosterone responses to the ACTH release during the administration of these stimuli were significantly increased. The adrenal reserve was significantly elevated in short-term hyperthyroidsim. Long-term hyperthyroidism, however, was associated with a significant reduction in adrenocortical reserve. A significant increase in adrenal weights and a decrease in thymus weights were observed in both short- and long-term hyperthyroidism.The available data confirms that hyperthyroidism is associated with hypercorticosteronemia, although the locus that is principally affected still remains unclear. Despite the sustained hyperactivity of the HPA axis, long-term experimentally-induced hyperthyroidism is associated with diminished adrenal functional reserve. The alterations in HPA function in states of disturbed thyroid function were found to be somewhat more pronounced as the duration of thyroid dysfunction increased.

The growth hormone receptor (GHR) is expressed as one active, full-sequence isoform and one truncated, inactive one that lacks the intracellular signaling domain. The aim of this study was to investigate the variation in the tissue expression of the full and truncated mRNA and protein. Epstein-Barr virus-transformed human B lymphocyte lines were established from 9 normal individuals with a height standard deviation score (SDS) of - 0.1 +/- 1.1 (mean +/- SD). Tissues were also collected from 3 Rhesus monkeys, whose GHR has 94.1 % homology with the human molecule. mRNA quantitation was determined by Real Time Quantitative PCR. Growth hormone receptor expression in transformed lymphocytes was also studied by fluorescence-activated cell sorter analysis. Both isoforms were expressed in transformed lymphocytes, but individual variation in the relative mRNA expression was small (truncated isoform percentage of total receptor mRNA: 17.1 +/- 4.4, mean +/- SD). There was no correlation between donors' height SDS and the expression of either isoform or the ratio between them. Protein expression by FACS analysis showed wider variation among the subjects; however, the relative ratio was similar in all the subjects. In monkey tissues, the truncated receptor showed a tissue-specific distribution. In conclusion, the expression of both isoforms in transformed lymphocytes from normal subjects shows small differences at the RNA or protein levels, and does not correlate with height SDS. Growth hormone splice isoforms show tissue specificity, suggesting local regulation of splicing. Tissues with relatively high expression of the truncated isoform are likely to be more resistant to the effects of GH due to the dominant negative effect of this isoform. In addition, the differential tissue expression might influence the levels of growth hormone binding protein in the immediate milieu of each tissue.

The question of the contribution of <i>CYP21A2</i> heterozygosity to the development of polycystic ovary syndrome (PCOS) has repeatedly been raised in the literature. The available data, however, do not offer a satisfactory answer. The discrepancy must be attributed, primarily, to the small number of subjects in the various studies, the type of selected phenotype, and the number of searched mutations. The aim of the study was to define the contribution of <i>CYP21A2</i> heterozygous mutations to the pathogenesis of PCOS. We searched for 14 molecular defects of the <i>CYP21A2</i> gene in 197 PCOS women, employing allele specific PCR. Androgen levels were determined at baseline by appropriate methodology in the follicular phase. PCOS women with 17-hydroxyprogesterone (17OHP) basal values >2 ng/ml and/or post-ACTH >10 ng/ml were excluded. Appropriate controls were included. The frequency of the <i>CYP21A2</i> heterozygous mutations in PCOS women and in controls was 7.6% and 5.9%, respectively [p-value (PCOS vs. controls): 0.663]. Homozygosity for <i>CYP21A2</i> gene defects was not detected. In conclusion, the contribution of <i>CYP21A2</i> heterozygous mutations to the pathogenesis of PCOS is not substantiated by our data. Moreover, 17-hydroxyprogesterone values of < 10 ng/ml post-ACTH exclude homozygosity of <i>CYP21A2</i> mutations.

Introduction: Thalassemia Major (TM) is a hereditary disease caused by defective globin synthesis. Although, it is considered a disease which is well understood both from the clinical as well as the biological aspect, it is a complex phenomenon and still remains under thorough investigation. One of the recent findings, include the fact the due to the significant increase in life expectancy, TM patients suffer from various secondary health conditions, including endocrinopathies and low bone mineral density. Aim: The aim of the present study was to analyze biochemical factors, collected from TM patients, with the application of regression analysis in order to find probable causative relations for TM-induced osteoporosis. Methods: Sixty-four patients with TM (32 men and 32 women) participated in a cross-sectional study design. The patients were recruited from “Aghia Sofia” Children’s Hospital and evaluated using dual-energy X-ray absorptiometry (DXA) of the lumbar spine and femoral neck and with markers of bone remodeling including receptor activator of nuclear factor kappa-Β ligand (RANKL), osteoprotegerin (OPG), C-terminal telopeptide (CTX), and sclerostin. Results: Regression analysis, manifested significant relations in TM patients with respect to calcium, phosphorus, testosterone, luteinizing hormone, follicle stimulating hormone and DXA. Conclusions: In TM patients, several factors appeared to be linearly correlated, which indicates that these factors play an important role in TM-induced osteoporosis.

Steroids exert their actions by binding to the glucocorticoid, mineralocorticoid, androgen, estrogen and progesterone classes of receptors. Despite an exponential increase in our knowledge of steroid receptors, their interactions with other molecules, subcellular location and functions still need further elucidation. To unravel the mechanism(s) of action of the steroid hormones, as well as the function of their cognate nuclear receptors, an interaction network was created (henceforth referred to as "R1 Interactome")- illustrating that robust interactions have been preserved in rodents, frog, zebra fish and drosophila. The generated interactome of the retrieved orthologs across species revealed: a. interactions among surface-cytosol-nuclear receptors, and/or orphan receptors and genes, and b. nuclear corepressor 1 (NCOR1) as a major "hub", through which most steroid receptors interact. These mechanisms (i) integrate social behavior and environmental stimuli with intrinsic cellular functions, (ii) provide an explanatory mechanism of the major Public Health problem of "non-ionizing" radiation impact, surpassing the existing conflict over the "thermal"/ "non- thermal" consequences of radiation, linking all the so far proposed mechanisms, and addressing all reported effects in humans, rodents and insects, and (iii) reveal biologically or clinically important pathways and/or regulatory networks.

Abstract Background Irisin, a novel myokine, has been shown to increase following vigorous exercise, with studies suggesting that it mediates some of the beneficial effects of exercise. Irisin might play a role in ‘browning’ of white adipocytes, thus increasing energy expenditure. The role of irisin in exercise and energy expenditure in subjects with diabetes mellitus type 2 ( DMT 2) remains largely unknown. We aimed to investigate the association between circulating irisin and habitual physical activity in subjects with and without DMT 2. Material and methods In this cross‐sectional study, 164 Saudi adults: 81 non‐ DMT 2 controls [age: (mean ± SD ) 51·6 ± 10·9; BMI : 29·6 ± 4·3 kg/m 2 ] and 83 DMT 2 subjects [age: 54·3 ± 10·3 year; BMI : 29·4 ± 4·7 kg/m 2 ] were studied. Anthropometric and fasting serum biochemical data were collected. Circulating irisin was measured using an enzyme‐linked immunosorbent assay ( ELISA ). Frequency intensity time ( FIT ) index was used to assess the level of habitual physical activity. Results We observed significantly higher levels of irisin in DMT 2 subjects than in controls ( P &lt; 0·001). FIT index was positively associated ( r = 0·20, P = 0·03) with circulating irisin in controls only. Additionally, irisin levels were significantly higher in tertile 3 (0·75 ± 0·07 μg/mL) than tertile 1 (0·49 ± 0·06 μg/mL) of the FIT index in healthy controls, whilst no such relation with physical activity was observed in DMT 2 subjects. Conclusion This cross‐sectional study has shown a weak association of irisin with physical activity levels in healthy controls but not in DMT 2 subjects, suggesting the possibility of discordant regulation in the condition of DMT 2.