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Almuraikhy S.,Anti Doping Laboratory Qatar | Almuraikhy S.,University of Bristol | Kafienah W.,University of Bristol | Bashah M.,Hamad Medical Corporation | And 8 more authors.
Diabetologia | Year: 2016

Aims/hypothesis: A subset of obese individuals remains insulin sensitive by mechanisms as yet unclear. The hypothesis that maintenance of normal subcutaneous (SC) adipogenesis accounts, at least partially, for this protective phenotype and whether it can be abrogated by chronic exposure to IL-6 was investigated. Methods: Adipose tissue biopsies were collected from insulin-sensitive (IS) and insulin-resistant (IR) individuals undergoing weight-reduction surgery. Adipocyte size, pre-adipocyte proportion of stromal vascular fraction (SVF)-derived cells, adipogenic capacity and gene expression profiles of isolated pre-adipocytes were determined, along with local in vitro IL-6 secretion. Adipogenic capacity was further assessed in response to exogenous IL-6 application. Results: Despite being equally obese, IR individuals had significantly lower plasma leptin and adiponectin levels and higher IL-6 levels compared with age-matched IS counterparts. Elevated systemic IL-6 in IR individuals was associated with hyperplasia of adipose tissue-derived SVF cells, despite higher frequency of hypertrophied adipocytes. SC pre-adipocytes from these tissues exhibited lower adipogenic capacity accompanied by downregulation of PPARγ (also known as PPARG) and CEBPα (also known as CEBPA) and upregulation of GATA3 expression. Impaired adipogenesis in IR individuals was further associated with increased adipose secretion of IL-6. Treatment of IS-derived SC pre-adipocytes with IL-6 reduced their adipogenic capacity to levels of the IR group. Conclusions/interpretation: Obesity-associated insulin resistance is marked by impaired SC adipogenesis, mediated, at least in a subset of individuals, by elevated local levels of IL-6. Understanding the molecular mechanisms underlying reduced adipogenic capacity in IR individuals could help target appropriate therapeutic strategies aimed at those at greatest risk of insulin resistance and type 2 diabetes mellitus. © 2016 The Author(s)

Kalogeropoulos N.,Weill Cornell Medicine Qatar
International Journal of Geometric Methods in Modern Physics | Year: 2016

We present aspects of the moduli of curve families on a metric measure space which may prove useful in calculating, or in providing bounds to, non-additive entropies having a power-law functional form. We use as paradigmatic cases the calculations of the moduli of curve families for a cylinder and for an annulus in Rn. The underlying motivation for these studies is that the definitions and some properties of the modulus of a curve family resembles those of the Tsallis entropy, when the latter is seen from a micro-canonical viewpoint. We comment on the origin of the conjectured invariance of the Tsallis entropy under Möbius transformations of the non-extensive (entropic) parameter. Needing techniques applicable to both locally Euclidean and fractal classes of spaces, we examine the behavior of the Tsallis functional, via the modulus, under quasi-conformal maps. We comment on properties of such maps and their possible significance for the dynamical foundations of power-law entropies. © 2016 World Scientific Publishing Company.

Hammoudeh S.,Weill Cornell Medicine Qatar | Abdelrahman M.H.,Hamad Medical Corporation | Chandra P.,Hamad Medical Corporation | Hammoudeh M.,Hamad Medical Corporation
Qatar Medical Journal | Year: 2015

Osteoporosis is a disease that affects the bones. It leads to increased risk of fractures as a result of decreased bone mineral density. The goal of this study was to assess the general perception of osteoporosis as well as knowledge of lifestyle, risk factors, and preventive measures among patients in Qatar. The study was conducted between September 2013 and September 2014. The study subjects (n = 93) were patients diagnosed with osteoporosis who attended the Outpatient Rheumatology Clinic at Hamad General Hospital in Doha, Qatar. The results showed that those with a university or graduate degree had a significantly higher level of knowledge about osteoporosis (p = 0.009) than those with less education. Among those in our study, knowledge related to osteoporosis was principally obtained through media sources such as television and radio (39%). In conclusion, osteoporosis patients in Qatar need a better understanding of the disease. Identifying thought patterns related to the perception of osteoporosis and treatment might assist in building a foundation for management modalities and effective preventive strategies for the disease in Qatar. © 2015 Hammoudeh, Abdelrahman, Chandra, Hammoudeh, licensee Bloomsbury Qatar Foundation Journals.

Mamtani R.,Weill Cornell Medicine Qatar | Cheema S.,Weill Cornell Medicine Qatar | Sheikh J.,Deans Office | Al Mulla A.,Hamad Medical Corporation | And 2 more authors.
International Journal of Public Health | Year: 2016

Objectives: To quantify by meta-analysis the relationship between waterpipe smoking and cancer, including cancer of the head and neck, esophagus, stomach, lung and bladder. Methods: We performed a systematic literature search to identify relevant studies, scored their quality, used fixed and random-effect models to estimate summary relative risks (SRR), evaluated heterogeneity and publication bias. Results: We retrieved information from 28 published reports. Considering only highquality studies, waterpipe smoking was associated with increased risk of head and neck cancer (SRR 2.97; 95 % CI 2.26–3.90), esophageal cancer (1.84; 1.42–2.38) and lung cancer (2.22; 1.24–3.97), with no evidence of heterogeneity or publication bias. Increased risk was also observed for stomach and bladder cancer but based mainly on poor-quality studies. For colorectum, liver and for all sites combined risk estimates were elevated, but there were insufficient reports to perform a meta-analysis. Conclusions: Contrary to the perception of the relative safety of waterpipe smoking, this meta-analysis provides quantitative estimates of its association with cancers of the head and neck, esophagus and lung. The scarcity and limited quality of available reports point out the need for larger carefully designed studies in well-defined populations. © 2016 The Author(s)

Schaefer-Ramadan S.,Foundation Medicine | Bendriss G.,Weill Cornell Medicine Qatar | Hubrack S.,Foundation Medicine | Al-Abdulmalek A.,Weill Cornell Medicine Qatar | Machaca K.,Foundation Medicine
Protein Expression and Purification | Year: 2016

The Cdc25 family encodes dual specificity protein phosphatases that play critical roles in cell cycle progression. Activation of the Cdc25C represents a primary driver for meiosis progression in Xenopus oocytes. Given its central role in meiosis the Xenopus Cdc25C has been studied extensively, however purification of the recombinant protein is difficult thus preventing better characterization of its function. Here we describe methods to overcome these difficulties resulting in the production of high purity and yield recombinant Xenopus Cdc25C. We use a synthetic Xenopus Cdc25C gene that was codon optimized for expression in E. coli. We further combine an N-terminal His-tag with a C-terminal Strep-tag II, to isolate extremely pure full-length Cdc25C protein. The recombinant Xenopus Cdc25C is active both in vitro using a phosphatase assay and in vivo when injected into Xenopus oocytes. This new approach should be applicable to the purification of other members of the Cdc25 gene family. © 2015 Elsevier Inc. All rights reserved.

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