Receptors of Thyroid Hormones
Ana Aranda, Elvira Alonso-Merino MD and Alberto Zambrano MD
The important physiological actions of the thyroid hormones are mediated by binding to nuclear thyroid hormone receptors (TRs), encoded by two genes TRα and TRβ. These receptors act as hormonedependent transcription factors by binding to DNA motifs located in the regulatory regions of target genes and recruiting coregulators (coactivators and corepresors), which alter chromatin structure. Novel thyromimetics have been developed that bind preferentially TRβ could be used for treatment of hyperlipidemia and obesity. TRβ gene mutations cause resistance to thyroid hormones (RTH), characterized by inappropriately high thyroidstimulating hormone (TSH) levels due to lack of feedback inhibition of thyroid hormones on the hypothalamus and pituitary gland, and to reduced sensitivity of other TRβ target tissues to thyroid hormones. Very recently, patients heterozygous for TRα mutations have been identified. These patients exhibit clinical symptoms of hypothyroidism in TRα target tissues such as intestine or hearth and near normal circulating TSH and thyroid hormone levels.
Ref: Ped Endocrinol. Rev. 2013:11(1): 2-13
Key Words: thyroid receptors, thyroid hormones
Circulating Non-coding RNAs as Biomarkers of Beta Cell Death in Diabetes
1Ryan J. Farr, 1Mugdha V. Joglekar, 2Caroline J Taylor, 1Anandwardhan A. Hardikar
Death of pancreatic islet β cells is a common feature of type 1 and 2 diabetes and often follows islet cell transplantation. Measurement of blood glucose is currently the only blunt instrument available to diagnose diabetes mellitus, and we lack tools to quantify islet cell loss or protection thereof. A class of RNA molecules (called microRNAs/miRNAs/miRs) that regulate endogenous gene expression via mRNA cleavage or translational arrest have been identified to be critical for birth, maintenance and regeneration of pancreatic β cells. Recent demonstration that microRNAs can potentially be utilised as biomarkers due to their serum stability, has triggered increasing interest in understanding their role as regulators or biomarkers of disease. This review aims to delve into the potential of miRNA biomarkers, and whether miRNA profiles are indicators or effector of disease pathology. Furthermore, an outline for identifying and confirming islet-specific miRNA biomarkers is discussed.
Ref: Ped Endocrinol. Rev. 2013:11(1): 14-20
Keywords: microRNA, diabetes mellitus, beta-cells, cell death, biomarkers
Anorexia Nervosa, Obesity and Bone Metabolism
1,2Madhusmita Misra, MD, MPH, and 1Anne Klibanski, MD, 1Neuroendocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114; 2Pediatric Endocrine Unit, Massachusetts General Hospital for Children and Harvard Medical School, Boston, MA 02114
Anorexia nervosa and obesity are conditions at the extreme ends of the nutritional spectrum, associated with marked reductions versus increases respectively in body fat content. Both conditions are also associated with an increased risk for fractures. In anorexia nervosa, body composition and hormones secreted or regulated by body fat content are important determinants of low bone density, impaired bone structure and reduced bone strength. In addition, anorexia nervosa is characterized by increases in marrow adiposity and decreases in cold activated brown adipose tissue, both of which are related to low bone density. In obese individuals, greater visceral adiposity is associated with greater marrow fat, lower bone density and impaired bone structure. In this review, we discuss bone metabolism in anorexia nervosa and obesity in relation to adipose tissue distribution and hormones secreted or regulated by body fat content.
Ref: Ped Endocrinol. Rev. 2013:11(1): 21-33
Keywords: Anorexia nervosa, obesity, overweight, adolescents, bone density, bone microarchitecture, bone structure, finite element analysis
Adiponectin Levels in South Indian Children with Type 1 Diabetes Mellitus and Nondiabetic Children and its Correlation with Anthropometry and Glycemic Control
1Dr. J. Ritchie Sharon Solomon MBBS, DCH, MD, Institute of Obstetrics and Gynaecology, Madras Medical College, Chennai – 600008 India. 2Dr. V. Poovazhagi Varadarajan MBBS, DCH, MD, Institute of Child Health, Madras Medical College, Chennai- 600008 India
Studies have reported high adiponectin levels in children with type1 diabetes mellitus (T1DM). Adiponectin has been found to have a n t i - a t h e r o g e n i c a c t i o n a n d o t h e r p r o t e c t i v e functions. We wanted to estimate adiponectin level in south Indian T1DM children and compare i t w i t h t h a t o f n o n - d i a b e t i c c h i l d r e n a n d study its correlation with anthropometry and glycemic status. Sixty children with T1DM and forty non-diabetic children of age less than 15 years were analysed. Mean adiponectin level was higher in T1DM group than in non diabetic group (p<0.001) irrespective of the age group or sex. Negative correlation was observed between SFTtriceps and adiponectin in diabetic and control group. Multiple regression coefficient analysis of various parameters showed SFT- triceps as a statistically significant predictor of adiponectin level (p=0.001). We conclude that, children with T1DM had higher adiponectin level than n o n - diabetic children. Low SFT- triceps measurement may be a predictor of higher adiponectin level. Abbreviations: T1DM: type 1 diabetes mellitus SFT: skin fold thickness BMI: body mass index GDM: Gestational diabetes mellitus FPG: Fasting plasma glucose PPPG: Post prandial plasma glucose HbA1c: glycosylated haemoglobin MAC: mid arm circumference ANOVA: analysis of variance s.adiponectin: serum adiponectin T2DM: type 2 diabetes mellitus
Ref: Ped Endocrinol. Rev. 2013:11(1): 34-43
Keywords: Type 1diabetes mellitus, adiponectin, children
Klinefelter Syndrome and Cancer: From Childhood to Adulthood
1Vincenzo De Sanctis MD, 2Bernadette Fiscina MD, MPH, 3Ashraf Soliman MD, PhD, FRCP, 4Michela Giovannini MD, 5Mohamed Yassin MBBS, CABM, M Sc, FACP
The c l a s s i c c l i n i c a l ma n i f e s t a t i o n s o f Klinefelter syndrome ( KS) are expressions of the primary hypogonadism that causes severe alteration s o f the reproductive and endocrine functions of the testis. It is a syndrome that causes infertility, and in addition leads to multiple disorders that involve a variety of tissues and organs. Important medical conditions associated with KS are categorized as: 1) motor, c o g n i t i v e , and behav i o r a l d y s func t i o n ; 2 ) tumors; 3) vascular disease and 4) endocrine/ metabolic and autoimmune diseases. The overall incidence of cancer in men with this syndrome is similar to that of the general population, but some malignancies show a significantly higher prevalence in these patients. It is possible that the increased risk of developing certain cancers can be attributed to a d i r e c t e f fect of the chromosomal abnormality (the supernumerary X chromosome), or the combined action of the abnormal chromosomes and hormonal imbalances. Although data in the literature on cancer and K S a r e a b u n d a n t , m o s t o f them are individual case reports. Only three epidemiological studies with relatively large cohorts provide data with greater reliability, although each has inherent limitations related to study design.This review paper summarizes the current knowledge about cancer r i s k f rom ch ildhood to adul thood in patients with KS.
Ref: Ped Endocrinol. Rev. 2013:11(1): 44-50
Key words: Klinefelter Syndrome, extragonadal g e r m - c e l l t u m o r s , h e m a t o l o g i c malignancies, breast cancer