Adipose tissue biomarkers and type 2 diabetes incidence in normoglycemic participants in the MESArthritis Ancillary Study: A cohort study

BackgroundGiven the central role of skeletal muscles in glucose homeostasis, deposition of adipose depots beneath the fascia of muscles (versus subcutaneous adipose tissue [SAT]) may precede insulin resistance and type 2 diabetes (T2D) incidence. This study was aimed to investigate the associations between computed tomography (CT)–derived biomarkers for adipose tissue and T2D incidence in normoglycemic adults.Methods and findingsThis study was a population-based multiethnic retrospective cohort of 1,744 participants in the Multi-Ethnic Study of Atherosclerosis (MESA) with normoglycemia (baseline fasting plasma glucose [FPG] less than 100 mg/dL) from 6 United States of America communities. Participants were followed from April 2010 and January 2012 to December 2017, for a median of 7 years. The intermuscular adipose tissue (IMAT) and SAT areas were measured in baseline chest CT exams and were corrected by height squared (SAT and IMAT indices) using a predefined measurement protocol. T2D incidence, as the main outcome, was based on follow-up FPG, review of hospital records, or self-reported physician diagnoses.Participants’ mean age was 69 ± 9 years at baseline, and 977 (56.0%) were women. Over a median of 7 years, 103 (5.9%) participants were diagnosed with T2D, and 147 (8.4%) participants died. The IMAT index (hazard ratio [HR]: 1.27 [95% confidence interval [CI]: 1.15–1.41] per 1-standard deviation [SD] increment) and the SAT index (HR: 1.43 [95% CI: 1.16–1.77] per 1-SD increment) at baseline were associated with T2D incidence over the follow-up. The associations of the IMAT and SAT indices with T2D incidence were attenuated after adjustment for body mass index (BMI) and waist circumference, with HRs of 1.23 (95% CI: 1.09–1.38) and 1.29 (95% CI: 0.96–1.74) per 1-SD increment, respectively. The limitations of this study include unmeasured residual confounders and one-time measurement of adipose tissue biomarkers.ConclusionsIn this study, we observed an association between IMAT at baseline and T2D incidence over the follow-up. This study suggests the potential role of intermuscular adipose depots in the pathophysiology of T2D.Trial registrationClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT00005487","term_id":"NCT00005487"}}NCT00005487

In a cohort study, Shadpour Demehri and colleagues investigate the association between adipose tissue biomarkers and type 2 diabetes incidence in normoglycemic participants in US.     

Sub-chronic administration of stable GIP analog in mice decreases serum LPL activity and body weight

GIP receptor knockout mice were shown to be protected from the development of obesity on a high fat diet, suggesting a role of GIP in the development of obesity. In our study we aimed to test the hypothesis if excess of GIP could accelerate development of obesity and to identify GIP gene targets in adipose tissue. Therefore, mice were kept on a chow or a high fat diet and during the last 2 weeks D-Ala²-GIP or PBS injections were performed. Afterwards, serum LPL activity and several biochemical parameters (TG, FFA, cholesterol, glucose, insulin, resistin, IL-6, IL-1β, TNFα, GIP) were measured. Fat tissue was isolated and QPCR was performed for a set of genes involved in energy metabolism and inflammation. A DNA-microarray was used to identify GIP gene targets in adipose tissue of the chow diet group. We found that the D-Ala²-GIP injections caused a significant decrease in both body weight and LPL activity compared to controls. Serum biochemical parameters were not affected by D-Ala²-GIP, with an exception for resistin and insulin. The set of inflammatory genes were significantly decreased in adipose tissue in the D-Ala²-GIP injected animals on a chow diet. A DNA-microarray revealed that APO-genes and CYP-genes were affected by D-Ala²-GIP treatment in adipose tissue. These results suggest that the body weight-reducing effect of D-Ala²-GIP may be explained by lower LPL activity and insulin serum level. Moreover, the identified GIP candidate gene targets in adipose tissue link GIP action to lipid metabolism exerted by APO and CYP genes.     

Novel C-terminal motif within Sec7 domain of guanine nucleotide exchange factors regulates ADP-ribosylation factor (ARF) binding and activation

ADP-ribosylation factors (ARFs) and their activating guanine nucleotide exchange factors (GEFs) play key roles in membrane traffic and signaling. All ARF GEFs share a ～200-residue Sec7 domain (Sec7d) that alone catalyzes the GDP to GTP exchange that activates ARF. We determined the crystal structure of human BIG2 Sec7d. A C-terminal loop immediately following helix J (loop>J) was predicted to form contacts with helix H and the switch I region of the cognate ARF, suggesting that loop>J may participate in the catalytic reaction. Indeed, we identified multiple alanine substitutions within loop>J of the full length and/or Sec7d of two large brefeldin A-sensitive GEFs (GBF1 and BIG2) and one small brefeldin A-resistant GEF (ARNO) that abrogated binding of ARF and a single alanine substitution that allowed ARF binding but inhibited GDP to GTP exchange. Loop>J sequences are highly conserved, suggesting that loop>J plays a crucial role in the catalytic activity of all ARF GEFs. Using GEF mutants unable to bind ARF, we showed that GEFs associate with membranes independently of ARF and catalyze ARF activation in vivo only when membrane-associated. Our structural, cell biological, and biochemical findings identify loop>J as a key regulatory motif essential for ARF binding and GDP to GTP exchange by GEFs and provide evidence for the requirement of membrane association during GEF activity.     

Predictive Value of Proteinuria in Adult Dengue Severity

Background

Dengue is an important viral infection with different presentations. Predicting disease severity is important in triaging patients requiring hospital care. We aim to study the value of proteinuria in predicting the development of dengue hemorrhagic fever (DHF), utility of urine dipstick test as a rapid prognostic tool.

Methodology and principal findings

Adult patients with undifferentiated fever (n = 293) were prospectively enrolled at the Infectious Disease Research Clinic at Tan Tock Seng Hospital, Singapore from January to August 2012. Dengue infection was confirmed in 168 (57%) by dengue RT-PCR or NS1 antigen detection. Dengue cases had median fever duration of 6 days at enrolment. DHF was diagnosed in 34 cases according to the WHO 1997 guideline. Dengue fever (DF) patients were predominantly younger and were mostly seen in the outpatient setting with higher platelet level. Compared to DF, DHF cases had significantly higher peak urine protein creatinine ratio (UPCR) during clinical course (26 vs. 40 mg/mmol; p<0.001). We obtained a UPCR cut-off value of 29 mg/mmol based on maximum AUC in ROC curves of peak UPCR for DF versus DHF, corresponding to 76% sensitivity and 60% specificity. Multivariate analysis with other readily available clinical and laboratory variables increased the AUC to 0.91 with 92% sensitivity and 80% specificity. Neither urine dipstick at initial presentation nor peak urine dipstick value during the entire illness was able to discriminate between DF and DHF.

Conclusions

Proteinuria measured by a laboratory-based UPCR test may be sensitive and specific in prognosticating adult dengue patients.     

Identifying causal variants by fine mapping across multiple studies

Increasingly large Genome-Wide Association Studies (GWAS) have yielded numerous variants associated with many complex traits, motivating the development of “fine mapping” methods to identify which of the associated variants are causal. Additionally, GWAS of the same trait for different populations are increasingly available, raising the possibility of refining fine mapping results further by leveraging different linkage disequilibrium (LD) structures across studies. Here, we introduce multiple study causal variants identification in associated regions (MsCAVIAR), a method that extends the popular CAVIAR fine mapping framework to a multiple study setting using a random effects model. MsCAVIAR only requires summary statistics and LD as input, accounts for uncertainty in association statistics using a multivariate normal model, allows for multiple causal variants at a locus, and explicitly models the possibility of different SNP effect sizes in different populations. We demonstrate the efficacy of MsCAVIAR in both a simulation study and a trans-ethnic, trans-biobank fine mapping analysis of High Density Lipoprotein (HDL).     

Impact of Parameter Variation in Fabrication of Nanostructure by Atomic Force Microscopy Nanolithography

In this letter, we investigate the fabrication of Silicon nanostructure patterned on lightly doped (10¹⁵ cm⁻³) p-type silicon-on-insulator by atomic force microscope nanolithography technique. The local anodic oxidation followed by two wet etching steps, potassium hydroxide etching for silicon removal and hydrofluoric etching for oxide removal, are implemented to reach the structures. The impact of contributing parameters in oxidation such as tip materials, applying voltage on the tip, relative humidity and exposure time are studied. The effect of the etchant concentration (10% to 30% wt) of potassium hydroxide and its mixture with isopropyl alcohol (10%vol. IPA ) at different temperatures on silicon surface are expressed. For different KOH concentrations, the effect of etching with the IPA admixture and the effect of the immersing time in the etching process on the structure are investigated. The etching processes are accurately optimized by 30%wt. KOH +10%vol. IPA in appropriate time, temperature, and humidity.     

Hydrodynamic performance of a single-use aerated stirred bioreactor in animal cell culture: applications of tomography,dynamic gas disengagement (DGD), and CFD

Bioprocess and Biosystems Engineering - The hydrodynamics of gas–liquid two-phase flow in a single-use bioreactor were investigated in detail both experimentally and numerically. Electrical...