Aims/hypothesis
We determined the contribution to insulin resistance of the PH domain leucine-rich repeat protein phosphatase (PHLPP), which dephosphorylates Akt at Ser473, inhibiting its activity. ...We measured the abundance of PHLPP in fat and skeletal muscle from obese participants. To study the effect of PHLPP on insulin signalling,
PHLPP
(also known as
PHLPP1
) was overexpressed in HepG2 and L6 cells.
Methods
Subcutaneous fat samples were obtained from 82 morbidly obese and ten non-obese participants. Skeletal muscle samples were obtained from 12 obese and eight non-obese participants. Quantification of PHLPP-1 in human tissues was performed by immunoblotting. The functional consequences of recombinant
PHLPP1
overexpression in hepatoma HepG2 cells and L6 myoblasts were investigated.
Results
Of the 82 obese participants, 31 had normal fasting glucose, 33 impaired fasting glucose and 18 type 2 diabetes. PHLPP-1 abundance was twofold higher in the three obese groups than in non-obese participants (
p
= 0.004). No differences were observed between obese participants with normal fasting glucose, impaired fasting glucose or type 2 diabetes. PHLPP-1 abundance was correlated with basal Akt Ser473 phosphorylation (
r
= −0.48;
p
= 0.001), BMI (
r
= 0.44;
p
< 0.0001), insulin (
r
= 0.35;
p
< 0.0001) and HOMA (
r
= 0.38;
p
< 0.0001). PHLPP-1 abundance was twofold higher in the skeletal muscle of 12 obese participants than in that of eight non-obese participants (
p
< 0.0001). Insulin treatment of HepG2 cells resulted in a dose- and time-dependent upregulation of PHLPP-1. Overexpression of
PHLPP1
in HepG2 cells and L6 myoblasts resulted in impaired insulin signalling involving Akt/glycogen synthase kinase 3, glycogen synthesis and glucose transport.
Conclusions/interpretation
Increased abundance of PHLPP-1, production of which is regulated by insulin, may represent a new molecular defect in insulin-resistant states such as obesity.
Irisin, a novel myokine, was proposed to be able to regulate glucose homeostasis and obesity in mice. Whether irisin levels are associated with cardio-metabolic variables, insulin sensitivity, and ...vascular atherosclerosis in humans remain unsettled. To determine the associations between circulating irisin levels, cardio-metabolic variables, insulin sensitivity, and common carotid intima-media thickness (IMT), an indicator of vascular atherosclerosis, a cross-sectional evaluation of circulating irisin levels and cardio-metabolic variables in 192 White adults was conducted. Insulin sensitivity and insulin clearance were assessed by euglycemic–hyperinsulinemic clamp. Common carotid IMT was measured by ultrasound. After adjusting for age and gender, irisin levels were positively correlated with body fat mass (
r
= 0.12,
P
< 0.05), fasting (
r
= 0.17,
P
< 0.01), 2 h post-load insulin (
r
= 0.15,
P
< 0.02) levels, and IMT (
r
= 0.29,
P
< 0.0001) and were negatively correlated with insulin-stimulated glucose disposal (
r
= −0.18,
P
= 0.007), Matsuda index (
r
= −0.13,
P
< 0.04), disposition index (
r
= −0.278,
P
< 0.0001), and insulin clearance (
r
= −0.26,
P
< 0.0001). After adjusting for age, gender, and BMI, individuals in the highest tertile of irisin levels exhibited higher body fat mass (
P
< 0.01), fasting (
P
< 0.05), 2 h post-load (
P
< 0.01) insulin levels, carotid IMT (
P
< 0.001), lower insulin-stimulated glucose disposal (
P
< 0.001), Matsuda index (
P
< 0.01), disposition index (
P
< 0.01), and insulin clearance (
P
< 0.001) as compared with subjects in the lowest tertile of circulating irisin levels. Irisin is inversely associated with insulin sensitivity and positively associated with carotid IMT in humans, suggesting either increased release by adipose/muscle tissue in response to deterioration of insulin sensitivity or a compensatory increase in irisin to overcome an underlying irisin resistance.
Abstract Background Carotid Intima-Media Thickness (C-IMT) is a reliable predictor of cardiovascular events. We examined if increased C-IMT was associated with defects in glucose metabolism in ...non-diabetic subjects independently of age. Methods In 366 Caucasian non-diabetic subjects of the CARAMERIS study, we measured glucose response during a 75 g-Oral Glucose Tolerance Test (OGTT), insulin sensitivity index (ISI, by Matsuda Index), Liver Insulin Resistance Index (Liver-IR), insulin secretion by ΔAUC Ins0-120 /Glu0-120 (ΔI/ΔG) and beta cell function (Disposition Index, DI). Results Subjects were divided in two groups according to the median age (AGE1 ≤ 45 y; AGE2 > 45 y). Only 5 subjects in AGE1 and 32 in AGE2 had C-IMT > 0.9 mm. Compared to AGE1, AGE2 had a worse cardio-metabolic profile, increased cholesterol, glucose and insulin concentrations, blood pressure and C-IMT. Both ΔI/ΔG ratio and DI were significantly reduced in AGE2. By considering tertiles of C-IMT in each AGE group (G1-G3, where G3 comprised the highest C-IMT), we found that G3 showed increased OGTT glucose profiles and Liver IR, decreased ISI and DI, compared to G1 in each AGE group. Conclusions Increased C-IMT, but within normal ranges, is associated independently of age with altered postprandial glucose profile, increased peripheral and hepatic insulin resistance, decreased b-cell function. C-IMT measurement should become a routine analysis even in younger subjects to predict the risk of cardio-metabolic disease.
We present the results from combining machine learning with the profile likelihood fit procedure, using data from the Large Underground Xenon (LUX) dark matter experiment. This approach demonstrates ...reduction in computation time by a factor of 30 when compared with the previous approach, without loss of performance on real data. We establish its flexibility to capture non-linear correlations between variables (such as smearing in light and charge signals due to position variation) by achieving equal performance using pulse areas with and without position-corrections applied. Its efficiency and scalability furthermore enables searching for dark matter using additional variables without significant computational burden. We demonstrate this by including a light signal pulse shape variable alongside more traditional inputs such as light and charge signal strengths. Furthermore, this technique can be exploited by future dark matter experiments to make use of additional information, reduce computational resources needed for signal searches and simulations, and make inclusion of physical nuisance parameters in fits tractable.
The Large Underground Xenon (LUX) dark matter search was a 250-kg active mass dual-phase time projection chamber that operated by detecting light and ionization signals from particles incident on a ...xenon target. In December 2015, LUX reported a minimum 90% upper C.L. of 6 × 10−46 cm2 on the spin-independent WIMP-nucleon elastic scattering cross section based on a 1.4 × 104 kg·day exposure in its first science run. Tension between experiments and the absence of a definitive positive detection suggest it would be prudent to search for WIMPs outside the standard spin-independent/spin-dependent paradigm. Recent theoretical work has identified a complete basis of 14 independent effective field theory (EFT) operators to describe WIMP-nucleon interactions. In addition to spin-independent and spin-dependent nuclear responses, these operators can produce novel responses such as angular-momentum-dependent and spin-orbit couplings. Here we report on a search for all 14 of these EFT couplings with data from LUX's first science run. Limits are placed on each coupling as a function of WIMP mass.
A link between increased blood viscosity and type 2 diabetes has been previously reported. Herein, we investigated the association of blood viscosity with prediabetes, identified by glycated ...hemoglobin A1c (HbA1c) according to the new American Diabetes Association criteria, and subclinical atherosclerosis.
The study cohort includes 1136 non-diabetic adults submitted to anthropometrical evaluation, an oral glucose tolerance test and ultrasound measurement of carotid intima-media thickness (IMT). Whole blood viscosity was estimated using a validated formula based on hematocrit and total plasma proteins.
After adjusting for age, and gender, individuals with HbA1c-defined prediabetes (HbA1c 5.7–6.4% 39–47 mmol/mol) exhibited significantly higher values of hematocrit, and predicted blood viscosity as compared with controls. Increased levels of IMT were observed in subjects with HbA1c-defined prediabetes in comparison to controls. Predicted blood viscosity was positively correlated with age, waist circumference, blood pressure, cholesterol, triglycerides, fibrinogen, white blood cell, HbA1c, fasting and 2-h post-load glucose levels, fasting insulin, IMT and inversely correlated with HDL and Matsuda index of insulin sensitivity. Of the three glycemic parameters, i.e. HbA1c, fasting and 2-h post-load glucose, only HbA1c showed a significant correlation with predicted blood viscosity (β = 0.054, P = 0.04) in a multivariate regression analysis model including multiple atherosclerosis risk factors.
The study shows that individuals with HbA1c-defined prediabetes have increased predicted blood viscosity and IMT. The HbA1c criterion may be helpful to capture individuals with an increased risk of diabetes and cardiovascular disease who may benefit from an intensive lifestyle intervention.
•Subjects with HbA1c-defined prediabetes have increased blood viscosity and hematocrit.•HbA1c is an independent contributor of blood viscosity and hematocrit.•Blood viscosity and hematocrit are associated with carotid intima-media thickness.•Carotid intima-media thickness is increased in subjects with HbA1c-defined prediabetes.•A HbA1c value of 5.7–6.4% may identify subjects with increased cardio-metabolic risk.
To investigate the role of IRS1 locus on failure to oral antidiabetes drugs (OADs) we genotyped single-nucleotide polymorphisms (SNPs), rs2943641, rs7578326 (tagging all SNPs genome-wide associated ...with type 2 diabetes (T2D) and related traits at this locus) and rs1801278 (that is, the loss-of-function IRS1 G972R amino acid substitution) in 2662 patients with T2D. Although no association with OAD failure was observed for rs2943641 and rs7578326 SNPs (odds ratio (OR): 1.04, 95% confidence interval (CI): 0.93-1.16 and OR: 0.97, 95% CI: 0.87-1.09 respectively), a significant association was observed for rs1801278 (OR: 1.34, 95% CI: 1.08-1.66). When meta-analyzed with previous published data, an allelic OR of 1.41 (1.15-1.72; P=0.001) was obtained, so that homozygous R972R individuals have >80% higher risk of failing to OADs as compared with their G972G counterparts. In all, though further studies are needed for confirming this finding, our present data point to IRS1 rs1801278 as a potential biomarker for pursuing the goal of stratified medicine in the field of antihyperglycemic treatment in T2D.
The LUX-ZEPLIN dark matter search aims to achieve a sensitivity to the WIMP-nucleon spin-independent cross-section down to (1–2)×10−12 pb at a WIMP mass of 40 GeV/c2. This paper describes the ...simulations framework that, along with radioactivity measurements, was used to support this projection, and also to provide mock data for validating reconstruction and analysis software. Of particular note are the event generators, which allow us to model the background radiation, and the detector response physics used in the production of raw signals, which can be converted into digitized waveforms similar to data from the operational detector. Inclusion of the detector response allows us to process simulated data using the same analysis routines as developed to process the experimental data.
We present the results from combining machine learning with the profile likelihood fit procedure, using data from the Large Underground Xenon (LUX) dark matter experiment. This approach demonstrates ...reduction in computation time by a factor of 30 when compared with the previous approach, without loss of performance on real data. We establish its flexibility to capture non-linear correlations between variables (such as smearing in light and charge signals due to position variation) by achieving equal performance using pulse areas with and without position-corrections applied. Its efficiency and scalability furthermore enables searching for dark matter using additional variables without significant computational burden. We demonstrate this by including a light signal pulse shape variable alongside more traditional inputs such as light and charge signal strengths. Furthermore, this technique can be exploited by future dark matter experiments to make use of additional information, reduce computational resources needed for signal searches and simulations, and make inclusion of physical nuisance parameters in fits tractable.
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