1,640 research outputs found
The Spanish used oils market: A vector error correction model
The Spanish Used Oils Management Act (Royal Decree 679 of June 2, 2006), which mandated extended producer responsibility in the management of waste oils, set the recovery rate of used oils at 95% in 2006 and the refining rates of used oils at 55% and 65% in 2007 and 2008, respectively. This study examines the dynamic responses of the amount of used oils intended for re-refining and the price of base lubricant oils to the environmental objectives as fixed by the royal decree by estimating a vector error correction model. The results suggest that the quantity variable increases, but the effect is the opposite from the third period and beyond. The price variable increases, but the effect decreases at 2 years and beyond. In addition, the variable quantity causes the variation in the price variable
Fragment-based discovery of a regulatory site in thioredoxin glutathione reductase acting as "doorstop" for NADPH entry
Members of the FAD/NAD-linked reductase family are recognized as crucial targets in drug development for cancers, inflammatory disorders, and infectious diseases. However, individual FAD/NAD reductases are difficult to inhibit in a selective manner with off target inhibition reducing usefulness of identified compounds. Thioredoxin glutathione reductase (TGR), a high molecular weight thioredoxin reductase-like enzyme, has emerged as a promising drug target for the treatment of schistosomiasis, a parasitosis afflicting more than 200 million people. Taking advantage of small molecules selected from a high-throughput screen and using X-ray crystallography, functional assays, and docking studies, we identify a critical secondary site of the enzyme. Compounds binding at this site interfere with well-known and conserved conformational changes associated with NADPH reduction, acting as a doorstop for cofactor entry. They selectivity inhibit TGR from Schistosoma mansoni and are active against parasites in culture. Since many members of the FAD/NAD-linked reductase family have similar catalytic mechanisms the unique mechanism of inhibition identified in this study for TGR broadly opens new routes to selectively inhibit homologous enzymes of central importance in numerous diseases
Genome-wide association study of adipocyte lipolysis in the GENetics of Adipocyte Lipolysis (GENiAL) cohort
Objectives:
Lipolysis, hydrolysis of triglycerides to fatty acids in adipocytes, is tightly regulated, poorly understood, and, if perturbed, can lead to metabolic diseases including obesity and type 2 diabetes. The goal of this study was to identify the genetic regulators of lipolysis and elucidate their molecular mechanisms.
Methods:
Adipocytes from abdominal subcutaneous adipose tissue biopsies were isolated and were incubated without (spontaneous lipolysis) or with a catecholamine (stimulated lipolysis) to analyze lipolysis. DNA was extracted and genome-wide genotyping and imputation conducted. After quality control, 939 samples with genetic and lipolysis data were available. Genome-wide association studies of spontaneous and stimulated lipolysis were conducted. Subsequent in vitro gene expression analyses were used to identify candidate genes and explore their regulation of adipose tissue biology.
Results:
One locus on chromosome 19 demonstrated genome-wide significance with spontaneous lipolysis. 60 loci showed suggestive associations with spontaneous or stimulated lipolysis, of which many influenced both traits. In the chromosome 19 locus, only HIF3A was expressed in the adipocytes and displayed genotype-dependent gene expression. HIF3A knockdown in vitro increased lipolysis and the expression of key lipolysis-regulating genes.
Conclusions:
In conclusion, we identified a genetic regulator of spontaneous lipolysis and provided evidence of HIF3A as a novel key regulator of lipolysis in subcutaneous adipocytes as the mechanism through which the locus influences adipose tissue biology
Free fatty acids link metabolism and regulation of the insulin-sensitizing fibroblast growth factor-21
OBJECTIVE—Fibroblast growth factor (FGF)-21 improves insulin
sensitivity and lipid metabolism in obese or diabetic animal
models, while human studies revealed increased FGF-21 levels in obesity and type 2 diabetes. Given that FGF-21 has been suggested to be a peroxisome proliferator–activator receptor (PPAR) –dependent regulator of fasting metabolism, we hypothesized that free fatty acids (FFAs), natural agonists of PPAR, might modify FGF-21 levels.
RESEARCH DESIGN AND METHODS—The effect of fatty
acids on FGF-21 was investigated in vitro in HepG2 cells. Within a randomized controlled trial, the effects of elevated FFAs were studied in 21 healthy subjects (13 women and 8 men). Within a clinical trial including 17 individuals, the effect of insulin was analyzed using an hyperinsulinemic-euglycemic clamp and the effect of PPAR activation was studied subsequently in a rosiglitazone
treatment trial over 8 weeks.
RESULTS—Oleate and linoleate increased FGF-21 expression
and secretion in a PPAR-dependent fashion, as demonstrated
by small-interfering RNA–induced PPAR knockdown, while
palmitate had no effect. In vivo, lipid infusion induced an
increase of circulating FGF-21 in humans, and a strong correlation between the change in FGF-21 levels and the change in FFAs was observed. An artificial hyperinsulinemia, which was induced to delineate the potential interaction between elevated FFAs and
hyperinsulinemia, revealed that hyperinsulinemia also increased FGF-21 levels in vivo, while rosiglitazone treatment had no effect.
CONCLUSIONS—The results presented here offer a mechanism
explaining the induction of the metabolic regulator FGF-21 in the fasting situation but also in type 2 diabetes and obesity
Genome-wide association study of adipocyte lipolysis in the GENetics of adipocyte lipolysis (GENiAL) cohort.
OBJECTIVES:Lipolysis, hydrolysis of triglycerides to fatty acids in adipocytes, is tightly regulated, poorly understood, and, if perturbed, can lead to metabolic diseases including obesity and type 2 diabetes. The goal of this study was to identify the genetic regulators of lipolysis and elucidate their molecular mechanisms. METHODS:Adipocytes from abdominal subcutaneous adipose tissue biopsies were isolated and were incubated without (spontaneous lipolysis) or with a catecholamine (stimulated lipolysis) to analyze lipolysis. DNA was extracted and genome-wide genotyping and imputation conducted. After quality control, 939 samples with genetic and lipolysis data were available. Genome-wide association studies of spontaneous and stimulated lipolysis were conducted. Subsequent in vitro gene expression analyses were used to identify candidate genes and explore their regulation of adipose tissue biology. RESULTS:One locus on chromosome 19 demonstrated genome-wide significance with spontaneous lipolysis. 60 loci showed suggestive associations with spontaneous or stimulated lipolysis, of which many influenced both traits. In the chromosome 19 locus, only HIF3A was expressed in the adipocytes and displayed genotype-dependent gene expression. HIF3A knockdown in vitro increased lipolysis and the expression of key lipolysis-regulating genes. CONCLUSIONS:In conclusion, we identified a genetic regulator of spontaneous lipolysis and provided evidence of HIF3A as a novel key regulator of lipolysis in subcutaneous adipocytes as the mechanism through which the locus influences adipose tissue biology
Role of Active Contraction and Tropomodulins in Regulating Actin Filament Length and Sarcomere Structure in Developing Zebrafish Skeletal Muscle
LM was supported by a studentship from Queen Mary, University of London. Work in collaboration with Professor Arner and Dr. Li supported by The Physiological Society and EuFishBioMed. Research at KI was supported by the Swedish Research Council (2013–3003) and French Muscular Dystrophy Association (AFM
TcSNP: a database of genetic variation in Trypanosoma cruzi
The TcSNP database (http://snps.tcruzi.org) integrates information on genetic variation (polymorphisms and mutations) for different stocks, strains and isolates of Trypanosoma cruzi, the causative agent of Chagas disease. The database incorporates sequences (genes from the T. cruzi reference genome, mRNAs, ESTs and genomic sequences); multiple sequence alignments obtained from these sequences; and single-nucleotide polymorphisms and small indels identified by scanning these multiple sequence alignments. Information in TcSNP can be readily interrogated to arrive at gene sets, or SNP sets of interest based on a number of attributes. Sequence similarity searches using BLAST are also supported. This first release of TcSNP contains nearly 170 000 high-confidence candidate SNPs, derived from the analysis of annotated coding sequences. As new sequence data become available, TcSNP will incorporate these data, mapping new candidate SNPs onto the reference genome sequences
Circulating Fibroblast Growth Factor-21 Is Elevated in Impaired Glucose Tolerance and Type 2 Diabetes and Correlates With Muscle and Hepatic Insulin Resistance
OBJECTIVE — Fibroblast growth factor (FGF)-21 is highly expressed in the liver and regulates hepatic glucose production and lipid metabolism in rodents. However, its role in the pathogenesis of type 2 diabetes in humans remains to be defined. The aim of this study was to quantitate circulating plasma FGF-21 levels and examine their relationship with insulin sensitivity in subjects with varying degrees of obesity and glucose tolerance. RESEARCH DESIGN AND METHODS — Forty-one subjects (8 lean with normal glucose tolerance [NGT], 9 obese with NGT, 12 with impaired fasting glucose [IFG]/impaired glucose tolerance [IGT], and 12 type 2 diabetic subjects) received an oral glucose tolerance test (OGTT) and a hyperinsulinemic-euglycemic clamp (80 mU/m 2 per min) combined with 3- [ 3 H] glucose infusion. RESULTS — Subjects with type 2 diabetes, subjects with IGT, and obese subjects with NGT were insulin resistant compared with lean subjects with NGT. Plasma FGF-21 levels progressively increased from 3.9 � 0.3 ng/ml in lean subjects with NGT to 4.9 � 0.2 in obese subjects with NGT to 5.2 � 0.2 in subjects with IGT and to 5.3 � 0.2 in type 2 diabetic subjects. FGF-21 levels correlated inversely with whole-body (primarily reflects muscle) insulin sensitivity (r ��0.421, P � 0.007
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