Associations between serum 25-hydroxyvitamin D, body mass index and body fat composition among Emirati population: Results from the UAE healthy future study.

Introduction: Vitamin D deficiency and insufficiency are highly prevalent among several populations across the globe. Numerous studies have shown a significant correlation between body-mass-index (BMI) and Vitamin D status, however, some results differed according to ethnicity. Despite the abundance of sunshine throughout the year, vitamin D deficiency is prominent in the United Arab Emirates (UAE). In this study, we analyzed the UAE Healthy Future Study (UAEHFS) pilot data to investigate the association between serum 25-hydroxyvitamin D (25(OH)D) and % body fat (BF) composition as well as BMI. Material and methods: Data from a total of 399 Emirati men and women aged ≥ 18 years were analyzed. Serum 25(OH)D and standard measures of weight and height were included in the analyses. Vitamin D deficiency was defined as serum 25(OH)D concentration<20 ng/ml. Multivariate quantile regression models were performed to explore the relationship between serum 25(OH)D levels and % BF composition and BMI correspondingly. Results: There were 281 (70.4%) males and 118 (29.6%) females included in this study. More than half of the study participants had vitamin D insufficiency (52.4%), and nearly a third had vitamin D deficiency (30.3%); while only 17.3% had optimal levels. A statistically significant negative association between serum 25(OH) D levels and % BF composition was observed at intermediate percentiles while a statistically significant negative association between serum 25(OH)D and BMI was only observed at the median (50th percentile). Conclusion: The study findings support the association between low serum 25(OH) D levels (low vitamin D status) and high % BF composition and high BMI among adult Emiratis. Further longitudinal data from the prospective UAEHFS could better elucidate the relationship between serum 25(OH) D levels, % BF composition, and BMI in the context of various health outcomes among this population.

The UAE healthy future study: a pilot for a prospective cohort study of 20,000 United Arab Emirates nationals.

BACKGROUND: The United Arab Emirates (UAE) is faced with a rapidly increasing burden of non-communicable diseases including obesity, diabetes, and cardiovascular disease. The UAE Healthy Future study is a prospective cohort designed to identify associations between risk factors and these diseases amongst Emiratis. The study will enroll 20,000 UAE nationals aged ≥18 years. Environmental and genetic risk factors will be characterized and participants will be followed for future disease events. As this was the first time a prospective cohort study was being planned in the UAE, a pilot study was conducted in 2015 with the primary aim of establishing the feasibility of conducting the study. Other objectives were to evaluate the implementation of the main study protocols, and to build adequate capacity to conduct advanced clinical laboratory analyses. METHODS: Seven hundred sixty nine UAE nationals aged ≥18 years were invited to participate voluntarily in the pilot study. Participants signed an informed consent, completed a detailed questionnaire, provided random blood, urine, and mouthwash samples and were assessed for a series of clinical measures. All specimens were transported to the New York University Abu Dhabi laboratories where samples were processed and analyzed for routine chemistry and hematology. Plasma, serum, and a small whole blood sample for DNA extraction were aliquoted and stored at -80 °C for future analyses. RESULTS: Overall, 517 Emirati men and women agreed to participate (68% response rate). Of the total participants, 495 (95.0%), 430 (82.2%), and 492 (94.4%), completed the questionnaire, physical measurements, and provided biological samples, respectively. CONCLUSIONS: The pilot study demonstrated the feasibility of recruitment and completion of the study protocols for the first large-scale cohort study designed to identify emerging risk factors for the major non-communicable diseases in the region.

The AGE-RAGE axis in an Arab population: The United Arab Emirates Healthy Futures (UAEHFS) pilot study.

AIMS: The transformation of the United Arab Emirates (UAE) from a semi-nomadic to a high income society has been accompanied by increasing rates of obesity and Type 2 diabetes mellitus. We examined if the AGE-RAGE (receptor for advanced glycation endproducts) axis is associated with obesity and diabetes mellitus in the pilot phase of the UAE Healthy Futures Study (UAEHFS). METHODS: 517 Emirati subjects were enrolled and plasma/serum levels of AGE, carboxy methyl lysine (CML)-AGE, soluble (s)RAGE and endogenous secretory (es)RAGE were measured along with weight, height, waist and hip circumference (WC/HC), blood pressure, HbA1c, Vitamin D levels and routine chemistries. The relationship between the AGE-RAGE axis and obesity and diabetes mellitus was tested using proportional odds models and linear regression. RESULTS: After covariate adjustment, AGE levels were significantly associated with diabetes status. Levels of sRAGE and esRAGE were associated with BMI and levels of sRAGE were associated with WC/HC. CONCLUSIONS: The AGE-RAGE axis is associated with diabetes status and obesity in this Arab population. Prospective serial analysis of this axis may identify predictive biomarkers of obesity and cardiometabolic dysfunction in the UAEHFS.

Playing the "Harp": evolution of our understanding of hrp/hrc genes.

With the advent of recombinant DNA techniques, the field of molecular plant pathology witnessed dramatic shifts in the 1970s and 1980s. The new and conventional methodologies of bacterial molecular genetics put bacteria center stage. The discovery in the mid-1980s of the hrp/hrc gene cluster and the subsequent demonstration that it encodes a type III secretion system (T3SS) common to Gram negative bacterial phytopathogens, animal pathogens, and plant symbionts was a landmark in molecular plant pathology. Today, T3SS has earned a central role in our understanding of many fundamental aspects of bacterium-plant interactions and has contributed the important concept of interkingdom transfer of effector proteins determining race-cultivar specificity in plant-bacterium pathosystems. Recent developments in genomics, proteomics, and structural biology enable detailed and comprehensive insights into the functional architecture, evolutionary origin, and distribution of T3SS among bacterial pathogens and support current research efforts to discover novel antivirulence drugs.

On the quaternary association of the type III secretion system HrcQB-C protein: experimental evidence differentiates among the various oligomerization models.

The HrcQB protein from the plant pathogen Pseudomonas syringae is a core component of the bacterial type III secretion apparatus. The core consists of nine proteins widely conserved among animal and plant pathogens which also share sequence and structural similarities with proteins from the bacterial flagellum. Previous studies of the carboxy-terminal domain of HrcQB (HrcQB-C) and its flagellar homologue, FliN-C, have revealed extensive sequence and structural homologies, similar subcellular localization, and participation in analogous protein-protein interaction networks. It is not clear however whether the similarities between the two proteins extend to the level of quaternary association which is essential for the formation of higher-order structures within the TTSS. Even though the crystal structure of the FliN is a dimer, more detailed studies support a tetrameric donut-like association. However, both models, dimer and donut-like tetramer, are quite different from the crystallographic elongated dimer of dimers of the HrcQB-C. To resolve this discrepancy we performed a multidisciplinary investigation of the quaternary association of the HrcQB-C, including mass-spectrometry, electrophoresis in non-reductive conditions, gel filtration, glutaraldehyde cross-linking and small angle X-ray scattering. Our experiments indicate that stable tetramers of elongated shape are assembled in solution, in agreement with the results of crystallographic studies. Circular dichroism data are consistent with a dimer-dimer interface analogous to the one established in the crystal structure. Finally, molecular dynamics simulations reveal the relative orientation of the dimers forming the tetramers and the possible differences from that of the crystal structure.

Evidence for a coiled-coil interaction mode of disordered proteins from bacterial type III secretion systems.

Gene clusters encoding various type III secretion system (T3SS) injectisomes, frequently code downstream of the conserved atpase gene for small hydrophilic proteins whose amino acid sequences display a propensity for intrinsic disorder and coiled-coil formation. These properties were confirmed experimentally for a member of this class, the HrpO protein from the T3SS of Pseudomonas syringae pv phaseolicola: HrpO exhibits high alpha-helical content with coiled-coil characteristics, strikingly low melting temperature, structural properties that are typical for disordered proteins, and a pronounced self-association propensity, most likely via coiled-coil interactions, resulting in heterogeneous populations of quaternary complexes. HrpO interacts in vivo with HrpE, a T3SS protein for which coiled-coil formation is also strongly predicted. Evidence from HrpO analogues from all T3SS families and the flagellum suggests that the extreme flexibility and propensity for coiled-coil interactions of this diverse class of small, intrinsically disordered proteins, whose structures may alter as they bind to their cognate folded protein targets, might be important elements in the establishment of protein-protein interaction networks required for T3SS function.

Structure of HrcQB-C, a conserved component of the bacterial type III secretion systems.

Type III secretion systems enable plant and animal bacterial pathogens to deliver virulence proteins into the cytosol of eukaryotic host cells, causing a broad spectrum of diseases including bacteremia, septicemia, typhoid fever, and bubonic plague in mammals, and localized lesions, systemic wilting, and blights in plants. In addition, type III secretion systems are also required for biogenesis of the bacterial flagellum. The HrcQ(B) protein, a component of the secretion apparatus of Pseudomonas syringae with homologues in all type III systems, has a variable N-terminal and a conserved C-terminal domain (HrcQ(B)-C). Here, we report the crystal structure of HrcQ(B)-C and show that this domain retains the ability of the full-length protein to interact with other type III components. A 3D analysis of sequence conservation patterns reveals two clusters of residues potentially involved in protein-protein interactions. Based on the analogies between HrcQ(B) and its flagellum homologues, we propose that HrcQ(B)-C participates in the formation of a C-ring-like assembly.

Molecular determinants required for the avirulence function of AvrPphB in bean and other plants.

The avirulence gene avrPphB from Pseudomonas syringae pv. phaseolicola determines incompatibility, manifested as a hypersensitive reaction (HR), on bean cultivars carrying the R3 resistance gene and also confers avirulence on other plants. The AvrPphB protein carries an embedded consensus myristoylation motif and is cleaved in bacteria and certain plants to yield fragments of about 6 and 28 kDa. We investigated plant recognition and type III translocation determinants in AvrPphB by constructing three N-terminally truncated and two site-directed mutants carrying substitutions in the conserved G63 residue of the myristoylation motif, which lies adjacent to the proteolytic cleavage site. The peptides were either delivered to plant cells by pseudomonads or were expressed transiently in planta via the Agrobacterium tumefaciens or Potato virus X. The 63 amino terminal residues were required for type III-mediated translocation from Pseudomonas strains to the plant, but were partially dispensable for effector recognition following in planta expression. Substitution of the G63 residue resulted in differential HR phenotypes in two different R3 cultivars of bean and abolished effector processing in Pseudomonas strains. Agrobacterium-mediated expression of the mutant proteins elicited HR in resistant bean hosts and in tomato but elicited no reaction in Nicotiana species.