PLXNB1 mutations in the etiology of idiopathic hypogonadotropic hypogonadism

Idiopathic hypogonadotropic hypogonadism (IHH) comprises a group of rare genetic disorders characterized by pubertal failure caused by gonadotropin-releasing hormone (GnRH) deficiency. Genetic factors involved in semaphorin/plexin signaling have been identified in patients with IHH. PlexinB1, a member of the plexin family receptors, serves as the receptor for semaphorin 4D (Sema4D). In mice, perturbations in Sema4D/PlexinB1 signaling leads to improper GnRH development, highlighting the importance of investigating PlexinB1 mutations in IHH families. In total, 336 IHH patients (normosmic IHH, n = 293 and Kallmann syndrome, n = 43) from 290 independent families were included in the present study. Six PLXNB1 rare sequence variants (p.N361S, p.V608A, p.R636C, p.V672A, p.R1031H, and p.C1318R) are described in eight normosmic IHH patients from seven independent families. These variants were examined using bioinformatic modeling and compared to mutants reported in PLXNA1. Based on these analyses, the variant p.R1031H was assayed for alterations in cell morphology, PlexinB1 expression, and migration using a GnRH cell line and Boyden chambers. Experiments showed reduced membrane expression and impaired migration in cells expressing this variant compared to the wild-type. Our results provide clinical, genetic, molecular/cellular, and modeling evidence to implicate variants in PLXNB1 in the etiology of IHH

Ultrasensitive Detection And Quantification Of Acidic Disaccharides Using Capillary Electrophoresis And Quantum Dot-Based Fluorescence Resonance Energy Transfer

Rapid and highly sensitive detection of the carbohydrate components of glycoconjugates is critical for advancing glycobiology. Fluorescence (or Forster) resonance energy transfer (FRET) is commonly used in detection of DNA, in protein structural biology, and in protease assays but is less frequently applied to glycan analysis due to difficulties in inserting two fluorescent tags into small glycan structures. We report an ultrasensitive method for the detection and quantification of a chondroitin sulfate disaccharide based on FRET, involving a CdSe-ZnS core-shell nanocrystal quantum dot (QD) streptavidin conjugate donor and a Cy5 acceptor. The disaccharide was doubly labeled with biotin and Cy5. QDs then served to concentrate the target disaccharide, enhancing the overall energy transfer efficiency, with unlinked QDs and Cy5 hydrazide producing nearly zero background signal in capillary electrophoresis using laser-induced fluorescence detection with two different band-pass filters. This method is generally applicable to the ultrasensitive analysis of acidic glycans and offers promise for the high-throughput disaccharide analysis of glycosaminoglycans.Wo

Characteristics of Turkish children with Type 2 diabetes at onset: a multicentre, cross-sectional study

Aims To describe the baseline clinical and laboratory findings and treatment modalities of 367 children and adolescents diagnosed with Type 2 diabetes in various paediatric endocrinology centres in Turkey. Methods A standard questionnaire regarding clinical and laboratory characteristics at onset was uploaded to an online national database system. Data for 367 children (aged 6-18 years) newly diagnosed with Type 2 diabetes at 37 different paediatric endocrinology centres were analysed. Results After exclusion of the children with a BMI Z-score 50% of the children were asymptomatic at diagnosis. The other important result of our study was the high rate of exclusion from the initial registration (38%), suggesting that accurate diagnosis of Type 2 diabetes in youth is still problematic, even for paediatric endocrinologists

Capillary Electrophoresis For Total Glycosaminoglycan Analysis

A capillary zone electrophoresis-laser-induced fluorescence detection (CZE-LIF) method was developed for the simultaneous analysis of disaccharides derived from heparan sulfate, chondroitin sulfate/dermatan sulfate, hyaluronan, and keratan sulfate. Glycosaminoglycans (GAGs) were first depolymerized with the mixture of GAG lyases (heparinase I, II, III and chondroitinase ABC and chondroitinase AC II) and GAG endohydrolase (keratinase II) and the resulting disaccharides were derivatized by reductive amination with 2-aminoacridone. Nineteen fluorescently labeled disaccharides were separated using 50 mM phosphate buffer (pH 3.3) under reversed polarity at 25 kV. Using these conditions, all the disaccharides examined were baseline separated in less then 25 min. This CZE-LIF method gave good reproducibility for both migration time (a parts per thousand currency sign1.03 % for intraday and a parts per thousand currency sign4.4 % for interday) and the peak area values (a parts per thousand currency sign5.6 % for intra- and a parts per thousand currency sign8.69 % for interday). This CZE-LIF method was used for profiling and quantification of GAG derivative disaccharides in bovine cornea. The results show that the current CZE-LIF method offers fast, simple, sensitive, reproducible determination of disaccharides derived from total GAGs in a single run.Wo

Characteristics of Turkish children with Type 2 diabetes at onset: a multicentre, cross-sectional study

Aims To describe the baseline clinical and laboratory findings and treatment modalities of 367 children and adolescents diagnosed with Type 2 diabetes in various paediatric endocrinology centres in Turkey. Methods A standard questionnaire regarding clinical and laboratory characteristics at onset was uploaded to an online national database system. Data for 367 children (aged 6-18 years) newly diagnosed with Type 2 diabetes at 37 different paediatric endocrinology centres were analysed. Results After exclusion of the children with a BMI Z-score < 1 SD, those with genetic syndromes associated with Type 2 diabetes, and those whose C-peptide and/or insulin levels were not available, 227 cases were included in the study. Mean age was 13.8 +/- 2.2 (range 6.5-17.8) years, with female preponderance (68\%). Family history of Type 2 diabetes was positive in 86\% of the children. The mean BMI was 31.3 +/- 6.5 kg/m(2) (range 18.7-61) and BMI Z-score was 2.4 +/- 0.8 (range 1-5). More than half (57\%) of the children were identified by an opportunistic diabetes screening due to existing risk markers without typical symptoms of diabetes. Only 13\% (n = 29) were treated solely by lifestyle modification, while 40.5\% (n = 92) were treated with metformin, 13\% (n = 30) were treated with insulin, and 33.5\% (n = 76) were treated with a combination of insulin and metformin initially. Mean HbA(1C) levels of the insulin and combination of insulin and metformin groups were 98 (11.1\%) and 102 mmol/mol (11.5\%), respectively, and also were significantly higher than the lifestyle modification only and metformin groups mean HbA(1C) levels (70(8.6\%) and 67 mmol/mol (8.3\%), respectively). Conclusions An opportunistic screening of children who are at high risk of Type 2 diabetes is essential, as our data showed that > 50\% of the children were asymptomatic at diagnosis. The other important result of our study was the high rate of exclusion from the initial registration (38\%), suggesting that accurate diagnosis of Type 2 diabetes in youth is still problematic, even for paediatric endocrinologists