102,857 research outputs found
Glucocorticoid receptor isoforms alpha and beta: potential physiologic and pathologic importance
No full text
Circulating leukocyte telomere length is highly heritable among families of Arab descent
No full textBackground
Telomere length, an indicator of ageing and longevity, has been correlated with several biomarkers of cardiometabolic disease in both Arab children and adults. It is not known, however, whether or not telomere length is a highly conserved inheritable trait in this homogeneous cohort, where age-related diseases are highly prevalent. As such, the aim of this study was to address the inheritability of telomere length in Saudi families and the impact of cardiometabolic disease biomarkers on telomere length.
Methods
A total of 119 randomly selected Saudi families (123 adults and 131 children) were included in this cross-sectional study. Anthropometrics were obtained and fasting blood samples were taken for routine analyses of fasting glucose and lipid profile. Leukocyte telomere length was determined using quantitative real time PCR.
Results
Telomere length was highly heritable as assessed by a parent-offspring regression [h2 = 0.64 (p = 0.0006)]. Telomere length was modestly associated with BMI (R2 0.07; p-value 0.0087), total cholesterol (R2 0.08; p-value 0.0033), and LDL-cholesterol (R2 0.15; p-value 3 x 10-5) after adjustments for gender, age and age within generation.
Conclusion
The high heritability of telomere length in Arab families, and the associations of telomere length with various cardiometabolic parameters suggest heritable genetic fetal and/or epigenetic influences on the early predisposition of Arab children to age-related diseases and accelerated ageing
A novel mutation of the hGR gene causing Chrousos syndrome
No full textBackground Natural mutations in the human glucocorticoid receptor (hGR, NR3C1) gene cause Chrousos syndrome, a rare condition characterized by generalized, partial, target-tissue insensitivity to glucocorticoids. Objective To present a new case of Chrousos syndrome caused by a novel mutation in the hGR gene, and to elucidate the molecular mechanisms through which the natural mutant receptor affects glucocorticoid signal transduction. Design and Results The index case presented with hirsutism, acne, alopecia, anxiety, fatigue and irregular menstrual cycles, but no clinical manifestations suggestive of Cushing’s syndrome. Endocrinologic evaluation revealed elevated 08:00h plasma adrenocorticotropic hormone, serum cortisol and androstenedione concentrations and increased urinary free cortisol excretion. The patient harbored a novel A>G transition at nucleotide position 2177, which resulted in histidine (H) to arginine (R) substitution at amino acid position 726 of the receptor (c.2177A>G, p.H726R). Compared with the wild-type receptor, the mutant receptor hGRH726R demonstrated decreased ability to transactivate glucocorticoid-responsive genes and to transrepress the nuclear factor-B signalling pathway, displayed 55% lower affinity for the ligand and a four-fold delay in nuclear translocation, and interacted with the glucocorticoid receptor-interacting protein 1 coactivator mostly through its activation function-1 domain. Finally, a 3-dimensional molecular modelling study of the H726R mutation revealed a significant structural shift in the rigidity of helix 10 of the receptor, which resulted in reduced flexibility and decreased affinity of the mutant receptor for binding to the ligand. Conclusions The natural mutant receptor hGRH726R impairs multiple steps of glucocorticoid signal transduction, thereby decreasing tissue sensitivity to glucocorticoids
Functional characterization of the hGR alpha T556I causing Chrousos syndrome
No full textBackground Chrousos syndrome is a rare pathologic condition characterized by generalized, partial resistance of target tissues to glucocorticoids and caused by inactivating mutations of the human glucocorticoid receptor (hGR) gene. A novel case of Chrousos syndrome has been reported in a patient with adrenal incidentaloma, who harboured a heterozygous point mutation in the hGR gene, which resulted in threonine (T) to isoleucine (I) substitution at amino acid position 556 in the ligand-binding domain of the receptor. Objective To delineate the molecular mechanisms through which the mutant receptor hGR alpha T556I causes Chrousos syndrome. Design and Results Compared with the wild-type receptor, the mutant receptor hGRaT556I demonstrated 50% reduction in its ability to transactivate glucocorticoid-responsive genes and in the affinity for the ligand, 30% increase in the ability to transrepress the nuclear factor-kappa B-target genes and a 3,4-fold delay in the cytoplasmic-to-nuclear translocation. The mutant receptor hGR alpha T556I did not exert a dominant negative effect upon the hGR-mediated transcriptional activity; it preserved its ability to bind to DNA and interacted with the glucocorticoid receptor-interacting protein 1 coactivator mostly through its activation function-1 domain. Structural biology studies revealed that the T556I mutation caused disruption of the hydrogen bond formed by the T556 with the = O group of P637 backbone, which resulted in a significant relocation of the P637-bearing loop. This conformational alteration affected the local 3D arrangement of the receptor and hence the electrostatic surface of the region. Conclusions The hGR alpha T556I causes Chrousos syndrome by impairing multiple steps of the glucocorticoid signal transduction pathway
A novel mutation of the hGR gene causing Chrousos syndrome
No full textBackground Natural mutations in the human glucocorticoid receptor (hGR, NR3C1) gene cause Chrousos syndrome, a rare condition characterized by generalized, partial, target-tissue insensitivity to glucocorticoids. Objective To present a new case of Chrousos syndrome caused by a novel mutation in the hGR gene, and to elucidate the molecular mechanisms through which the natural mutant receptor affects glucocorticoid signal transduction. Design and Results The index case presented with hirsutism, acne, alopecia, anxiety, fatigue and irregular menstrual cycles, but no clinical manifestations suggestive of Cushing's syndrome. Endocrinologic evaluation revealed elevated 08:00h plasma adrenocorticotropic hormone, serum cortisol and androstenedione concentrations and increased urinary free cortisol excretion. The patient harbored a novel A>G transition at nucleotide position 2177, which resulted in histidine (H) to arginine (R) substitution at amino acid position 726 of the receptor (c.2177A>G, p.H726R). Compared with the wild-type receptor, the mutant receptor hGRH726R demonstrated decreased ability to transactivate glucocorticoid-responsive genes and to transrepress the nuclear factor-B signalling pathway, displayed 55% lower affinity for the ligand and a four-fold delay in nuclear translocation, and interacted with the glucocorticoid receptor-interacting protein 1 coactivator mostly through its activation function-1 domain. Finally, a 3-dimensional molecular modelling study of the H726R mutation revealed a significant structural shift in the rigidity of helix 10 of the receptor, which resulted in reduced flexibility and decreased affinity of the mutant receptor for binding to the ligand. Conclusions The natural mutant receptor hGRH726R impairs multiple steps of glucocorticoid signal transduction, thereby decreasing tissue sensitivity to glucocorticoids
Familial autosomal dominant pseudohypoaldosteronism (PHA): alteration in the expression of the glucocorticoid receptor
No full textVitamin D supplementation in patients with diabetes mellitus type 2 on different therapeutic regimens : a one-year prospective study
No full textBackground
Little or no research has determined the effect of vitamin D3 supplementation in conjunction with pharmacological and non-pharmacological approaches in the diabetes mellitus type 2 (DMT2) patients. The objective of this study was to determine the effect of vitamin D3 supplementation in a cohort of Saudi DMT2 population on diet, insulin and/or different oral hypoglycemic agents and compare them with a non-DMT2 control cohort.
Methods
A total of 499 randomly selected Saudi subjects divided into 8 groups [Non-DMT2 Control = 151; Rosiglitazone alone = 49; Diet = 15; Insulin alone = 55; Insulin + Orals = 12; Metformin alone = 121; Oral agents combination = 37; Sulphonylurea alone = 59] were included in this 12-month interventional study. All DMT2 patients were given 2000 IU vitamin D3 daily, while the control group received none but were advised to increase sun exposure. Anthropometrics, glucose, lipid profile and 25-hydroxyvitamin D (25-OHVitD) were measured at baseline, 6 and 12 months.
Results
Circulating 25-OHVitD concentrations improved in all patient groups. The metformin group showed the highest change in circulating vitamin D levels both at 6 months (62.6%) and 12 months (50.6%) as compared to baseline (p < 0.001). No significant changes were observed in the BMI and glucose in any of the DMT2 groups. In contrast, the insulin + oral agents group showed more significant improvements in the metabolic profile, which included triglycerides and total cholesterol, as well as systolic blood pressure and HDL-cholesterol in males. Also, significant decreases in triglycerides were observed in the rosiglitazone and insulin + oral hypoglycemic agent groups both at 6 and 12 months of supplementation (both p-values <0.001).
Conclusion
While in all DMT2 groups circulating levels of 25-OHVitD increased after supplementation, in DMT2 patients on insulin in combination with other drugs benefitted the most in improving cardiovascular risk. Metformin improves 25-hydroxyvitamin D levels but did not seem to confer other added cardiometabolic benefits.
Keywords: Vitamin D; Vitamin D supplementation; Diabetes mellitus; Anti-diabetes therapie
Impairment of adrenocortical function associated with increased plasma tumor necrosis factor-alpha and interleukin 6 concentrations in African trypanosomiasis
No full textAfrican sleeping sickness (SS) is a severe, potentially lethal parasitic disease. The treatments of choice are the antiparasitic agents suramin, which is adrenotoxic, and/or melarsoprol. We evaluated the functional integrity of the hypothalamic-pituitary-adrenal (HPA) axis of patients with SS before, during, and after therapy with suramin and/or melarsoprol, in two sequential stages. First, we employed the standard adrenocorticotropic hormone (ACTH) 1-24 stimulation test (250 micrograms i.v.) to assess the maximal adrenocortical responsiveness of 69 patients with SS and 38 normal controls. We demonstrated paradoxically subnormal cortisol responses before suramin therapy [net cortisol response 60 min after stimulation: 10.5 +/- 2.9 (mean +/- SE) vs. 17.5 +/- 1.0 micrograms/dl for controls, p = 0.004], with 27% of the patients falling within the adrenal insufficiency range (stimulated cortisol concentration < 20 micrograms/dl). These responses subsequently and unexpectedly improved with suramin and/or melarsoprol therapy. Second, we performed a human corticotropin-releasing hormone (hCRH) test (100 micrograms i.v.) in 68 additional patients with SS and 14 control subjects to examine whether the glucocorticoid deficiency observed was primary and/or secondary. Compared to controls, the ACTH and cortisol responses to hCRH were blunted (ACTH after 60 min: 29 +/- 7 vs. 58 +/- 8 pg/ml in controls, p = 0.014; cortisol: 15.2 +/- 1.5 vs. 19.6 +/- 0.7 micrograms/dl, p = 0.018), suggesting the presence of secondary adrenal insufficiency. There was improvement of both ACTH and cortisol responsiveness to hCRH with therapy, with cortisol recovery occurring before ACTH, suggesting an additional primary component of adrenal dysfunction in these patients.(ABSTRACT TRUNCATED AT 250 WORDS)</p
- …
