OBJECTIVETo investigate whether circulating levels of fibroblast growth factor 21 (FGF21), which previously has been shown to be elevated in obesity, could predict the development of type 2 diabetes in a 5.4-year, population-based, prospective study.RESEARCH DESIGN AND METHODSBaseline plasma FGF21 levels were measured using an enzyme-linked immunosorbent assay in 1,900 subjects from the Hong Kong Cardiovascular Risk Factor Prevalence Study (CRISPS). The prospective association of FGF21 with diabetes development over 5.4 years was analyzed using multiple logistic regression.RESULTSAt baseline, plasma levels of FGF21 increased progressively with worsening dysglycemia from normal glucose tolerance, through prediabetes, to diabetes (global trend, P < 0.001). Of 1,292 subjects without diabetes at baseline, a high baseline FGF21 level was a strong independent predictor for diabetes development (odds ratio 1.792; P < 0.01), together with waist circumference and fasting plasma glucose levels.CONCLUSIONSPlasma FGF21 levels were significantly increased in subjects with prediabetes and diabetes and predicted the development of diabetes in humans.

During meiosis, the Msh4-Msh5 complex is thought to stabilize single-end invasion intermediates that form during early stages of recombination and subsequently bind to Holliday junctions to facilitate crossover formation. To analyze Msh4-Msh5 function, we mutagenized 57 residues in Saccharomyces cerevisiae Msh4 and Msh5 that are either conserved across all Msh4/5 family members or are specific to Msh4 and Msh5. The Msh5 subunit appeared more sensitive to mutagenesis. We identified msh4 and msh5 threshold (msh4/5-t) mutants that showed wild-type spore viability and crossover interference but displayed, compared to wild-type, up to a two-fold decrease in crossing over on large and medium sized chromosomes (XV, VII, VIII). Crossing over on a small chromosome, however, approached wild-type levels. The msh4/5-t mutants also displayed synaptonemal complex assembly defects. A triple mutant containing a msh4/5-t allele and mutations that decreased meiotic double-strand break levels (spo11-HA) and crossover interference (pch2Δ) showed synergistic defects in spore viability. Together these results indicate that the baker's yeast meiotic cell does not require the ∼90 crossovers maintained by crossover homeostasis to form viable spores. They also show that Pch2-mediated crossover interference is important to maintain meiotic viability when crossovers become limiting.

Hypertension is a major risk factor of cardiovascular disease in China, and yet little is known about health-related quality of life (HRQOL) and its associations with demographic and social-economic characteristics in middle-aged patients with hypertension. A cross-sectional survey was undertaken in Chongqing, China, using a multistage stratified random sampling methodology. Data was collected on 1,224 eligible adults, aged between 45 and 53 years, including the Medical Outcomes Survey Short Form-36 to measure HRQOL. Hypertension was associated with poor state of physical functioning, role-physical, bodily pain, general health, vitality, and social function (p < 0.05 for all). In multivariable analyses, education level, job conditions, average monthly income, smoking status, sleep quality, perception of relationship with family, childhood breastfeeding history, and body mass index were associated with domains of SF36 among those with hypertension (p < 0.05 for all). Hypertensive respondents with high education, marital status, breastfeeding, higher incomes, good quality of sleep, positive relationship with family, and higher body mass index have better HRQOL in middle-aged people with hypertension. Those unemployed had a better state of general health and had a poorer state of social function. Nonsmokers had a poorer state of bodily pain than smokers. This study provides detailed information of the implications for health care providers to gain a more complete picture of their hypertension patients' health.

Sifuvirtide, a novel fusion inhibitor against human immunodeficiency virus type I (HIV-1), which is more potent than enfuvirtide (T20) in cell culture, is currently under clinical investigation for the treatment of HIV-1 infection. We now report that in vitro selection of HIV-1 variants resistant to sifuvirtide in the presence of increasing concentrations of sifuvirtide has led to several specific mutations in the gp41 region that had not been previously reported. Many of these substitutions were confined to the N-terminal heptad repeat region at positions 37, 38, 41, and 43, either singly or in combination. A downstream substitution at position 126 (N126K) in the Cterminal heptad repeat region was also found. Site-directed mutagenesis studies have further identified the critical amino acid substitutions and combinations thereof in conferring the resistant genotypes. Furthermore, the mutant viruses demonstrated variable degrees of cross-resistance to enfuvirtide, some of which are preferentially more resistant to sifuvirtide. Impaired infectivity was also found for many of the mutant viruses. Biophysical and structural analyses of the key substitutions have revealed several potential novel mechanisms against sifuvirtide. Our results may help to predict potential resistant patterns in vivo and facilitate the further clinical development and therapeutic utility of sifuvirtide.The envelope glycoprotein (Env) of HIV-1 is critical in mediating viral entry into the target cells, and it represents a major target for the development of novel antiretroviral therapeutics. The entry process starts with the binding of gp120 to a cellular receptor, CD4, and subsequently with a chemokine receptor, CCR5 or CXCR4, on the surface of the target cells (1). These interactions trigger a cascade of conformational changes that lead to the formation of a prehairpin intermediate of gp41 in which the hydrophobic N-terminal heptad repeat (NHR) 2 is exposed and allows the fusion peptides to insert into the target cell membrane (1, 2). This transient gp41 intermediate then refolds into a stabilized trimer of hairpins, also called the six-helix bundle (6-HB) structure, which brings the viral envelope and the target cell membrane into close proximity, thus facilitating the completion of the fusion process (1-4). Structure and function studies indicate that the 6-HB core consists of a parallel trimeric coiled-coil of NHR with the C-terminal heptad repeat (CHR) wrapped on the outside in an antiparallel fashion (5-7). Similar features have been found in the fusion-mediating subunits of other viruses with class I membrane fusion proteins (8 -17).Inhibitors capable of disrupting the entry process hold great promise for improved efficacy of clinical antiviral therapeutics. Several entry inhibitors have been developed, and two of these have been approved for clinical use, such as a peptide-based inhibitor enfuvirtide (T20) and a small molecule inhibitor Maraviroc against HIV-1 co-receptor CCR5 (18 -20). In addition, several other entry inhibitors ar...

The potential for infection by coronaviruses (CoVs) has become a serious concern with the recent emergence of Middle East respiratory syndrome and severe acute respiratory syndrome (SARS) in the human population. CoVs encode two large polyproteins, which are then processed into 15-16 nonstructural proteins (nsps) that make significant contributions to viral replication and transcription by assembling the RNA replicase complex. Among them, nsp9 plays an essential role in viral replication by forming a homodimer that binds single-stranded RNA. Thus, disrupting nsp9 dimerization is a potential anti-CoV therapy. However, different nsp9 dimer forms have been reported for alpha- and beta-CoVs, and no structural information is available for gamma-CoVs. Here we determined the crystal structure of nsp9 from the avian infectious bronchitis virus (IBV), a representative gamma-CoV that affects the economy of the poultry industry because it can infect domestic fowl. IBV nsp9 forms a homodimer via interactions across a hydrophobic interface, which consists of two parallel alpha helices near the carboxy terminus of the protein. The IBV nsp9 dimer resembles that of SARS-CoV nsp9, indicating that this type of dimerization is conserved among all CoVs. This makes disruption of the dimeric interface an excellent strategy for developing anti-CoV therapies. To facilitate this effort, we characterized the roles of six conserved residues on this interface using site-directed mutagenesis and a multitude of biochemical and biophysical methods. We found that three residues are critical for nsp9 dimerization and its abitlity to bind RNA.

Crossing over between homologous chromosomes occurs during the prophase of meiosis I and is critical for chromosome segregation. In baker’s yeast, two heterodimeric complexes, Msh4-Msh5 and Mlh1-Mlh3, act in meiosis to promote interference-dependent crossing over. Mlh1-Mlh3 also plays a role in DNA mismatch repair (MMR) by interacting with Msh2-Msh3 to repair insertion and deletion mutations. Mlh3 contains an ATP-binding domain that is highly conserved among MLH proteins. To explore roles for Mlh3 in meiosis and MMR, we performed a structure−function analysis of eight mlh3 ATPase mutants. In contrast to previous work, our data suggest that ATP hydrolysis by both Mlh1 and Mlh3 is important for both meiotic and MMR functions. In meiotic assays, these mutants showed a roughly linear relationship between spore viability and genetic map distance. To further understand the relationship between crossing over and meiotic viability, we analyzed crossing over on four chromosomes of varying lengths in mlh3Δ mms4Δ strains and observed strong decreases (6- to 17-fold) in crossing over in all intervals. Curiously, mlh3Δ mms4Δ double mutants displayed spore viability levels that were greater than observed in mms4Δ strains that show modest defects in crossing over. The viability in double mutants also appeared greater than would be expected for strains that show such severe defects in crossing over. Together, these observations provide insights for how Mlh1-Mlh3 acts in crossover resolution and MMR and for how chromosome segregation in Meiosis I can occur in the absence of crossing over.

The relationship of four potentially functional polymorphisms of the vitamin D receptor (VDR) gene, ApaI, BsmI, FokI and TaqI , with tuberculosis susceptibility were considered. The aim of this meta-analysis was to explore the association between the four polymorphisms and tuberculosis risk in different ethnic backgrounds. Eligible case-control studies that were catalogued before April 1st 2013 were enrolled, and the heterogeneity between the studies was evaluated using a χ2 based Q-test. Fixed and random effect models were built to evaluate the association of the four polymorphisms with the risk of tuberculosis, and the association between the four polymorphisms and tuberculosis was expressed as the odds ratio (OR) and 95% confidence interval (CI). Finally, twenty nine qualified studies were enrolled for this meta-analysis that included 6179 tuberculosis cases and 6585 healthy controls. The variant homozygote genotype of the FokI polymorphism was associated with a significantly increased risk of tuberculosis when compared to the heterozygote and wild type homozygote genotypes in the Chinese population (ff vs. Ff+FF: ORrecessive=1.97, 95%CI: 1.32-2.93, P bonferroni=0.0032; heterogeneity test: χ2=0.24, P=0.62). For European subjects, the homozygote and heterozygote genotypes of the BsmI polymorphism were associated with a significantly decreased risk of tuberculosis when compared to the wild type homozygote (bb+Bb vs. BB: ORdominant=0.41, 95%CI, 0.22-0.76, P bonferroni=0.02; heterogeneity test: χ2=2.59, P=0.11). Based on the above results, we conclude that variants of the VDR gene that are homozygous for the FokI polymorphism might be more susceptible to tuberculosis in Chinese. Furthermore, larger sample studies are warranted to confirm the protective effects of BsmI variants on tuberculosis in the Europeans.

The existence of Th17 cells and IL‐17 was recently shown in several types of infectious diseases, but their distribution and functions in cervical lesions with high‐risk human papillomavirus (HPV) infection have not been fully elucidated. In this study, the frequency of Th17 cells in peripheral blood samples obtained from 28 cervical squamous cell carcinoma patients, 26 CIN1 patients, 30 CIN2 patients, 29 CIN3 patients, 25 high‐risk HPV‐infected women with normal cervical cytology, and 30 healthy controls was determined by flow cytometry. Besides, the levels of IL‐17 in peripheral blood samples as well as in supernatant of cervical tissue homogenate were assessed by enzyme‐linked immunosorbent assay (ELISA) simultaneously. We found that during the disease progression of cervical lesions, the proportion of Th17 cells in the total CD4+ cells showed a gradually increased tendency compared with the controls (P < 0.05). Moreover, levels of IL‐17 in serum and supernatant of cervical tissue homogenate showed the same tendency as the proportion of Th17 cells (P < 0.05). When compared in pairs, the levels of IL‐17 in supernatant differed significantly among the study groups and the control group (P < 0.05), but no significant difference was observed in serum (P > 0.05). In conclusions, the results indicate that Th17 cells and IL‐17 may play a role of immune enhancement in the infection of high‐risk HPV especially in the cervical microenvironment, which contribute to the disease progression of its associated cervical lesions.