25 research outputs found
Air pollution monitoring system in semi enclosed building for agricultural sector
This paper describes the development of an optical sensor system to monitor ammonia emission in the agricultural sector. At initial stage, an open path optical technique where a cylindrical chamber is used to detect low ammonia concentration within the Ultraviolet region. The methodology describing the operation of the sensor with wavelengths combination technique to optimize the measurement is presented. The results show the sensor is best measuring ammonia concentration at combination wavelengths (around 212 nm) with the Lower Detection Limit of 2.25 ppm and 1 s response time is achieved. Then the system is tested to monitor ammonia pollution in the cattle barn in Tipperary, Ireland. It shows that the developed system is able to detect and measure very low ammonia concentration which is less than 2 ppm
Molecular network analysis of phosphotyrosine and lipid metabolism in hepatic PTP1b deletion mice
Metabolic syndrome describes a set of obesity-related disorders that increase diabetes, cardiovascular, and mortality risk. Studies of liver-specific protein-tyrosine phosphatase 1b (PTP1b) deletion mice (L-PTP1b[superscript −/−]) suggest that hepatic PTP1b inhibition would mitigate metabolic-syndrome through amelioration of hepatic insulin resistance, endoplasmic-reticulum stress, and whole-body lipid metabolism. However, the altered molecular-network states underlying these phenotypes are poorly understood. We used mass spectrometry to quantify protein-phosphotyrosine network changes in L-PTP1b[superscript −/−] mouse livers relative to control mice on normal and high-fat diets. We applied a phosphosite-set-enrichment analysis to identify known and novel pathways exhibiting PTP1b- and diet-dependent phosphotyrosine regulation. Detection of a PTP1b-dependent, but functionally uncharacterized, set of phosphosites on lipid-metabolic proteins motivated global lipidomic analyses that revealed altered polyunsaturated-fatty-acid (PUFA) and triglyceride metabolism in L-PTP1b[superscript −/−] mice. To connect phosphosites and lipid measurements in a unified model, we developed a multivariate-regression framework, which accounts for measurement noise and systematically missing proteomics data. This analysis resulted in quantitative models that predict roles for phosphoproteins involved in oxidation–reduction in altered PUFA and triglyceride metabolism.Pfizer Inc. (grant)National Institutes of Health (U.S.) (grant 5R24DK090963)National Institutes of Health (U.S.) (grant U54-CA112967)National Institutes of Health (U.S.) (grant CA49152 R37)National Institutes of Health (U.S.) (grant R01-DK080756)National Mouse Metabolic Phenotyping Center at UMASS (Grant (U24-DK093000))National Science Foundation (U.S.) (Graduate Research Fellowship
Phosphoglycerate dehydrogenase diverts glycolytic flux and contributes to oncogenesis
Most tumors exhibit increased glucose metabolism to lactate, however, the extent to which glucose-derived metabolic fluxes are used for alternative processes is poorly understood [1, 2]. Using a metabolomics approach with isotope labeling, we found that in some cancer cells a relatively large amount of glycolytic carbon is diverted into serine and glycine metabolism through phosphoglycerate dehydrogenase (PHGDH). An analysis of human cancers showed that PHGDH is recurrently amplified in a genomic region of focal copy number gain most commonly found in melanoma. Decreasing PHGDH expression impaired proliferation in amplified cell lines. Increased expression was also associated with breast cancer subtypes, and ectopic expression of PHGDH in mammary epithelial cells disrupted acinar morphogenesis and induced other phenotypic alterations that may predispose cells to transformation. Our findings show that the diversion of glycolytic flux into a specific alternate pathway can be selected during tumor development and may contribute to the pathogenesis of human cancer.National Institutes of Health (U.S.)National Cancer Institute (U.S.)Smith Family FoundationDamon Runyon Cancer Research FoundationBurroughs Wellcome Fun
Phosphorylation of insulin receptor substrate 1 by glycogen synthase kinase 3 impairs insulin action
Sharfi H, Eldar-Finkelman H. Sequential phosphorylation of insulin receptor substrate-2 by glycogen synthase kinase-3 and c-Jun NH2-terminal kinase plays a role in hepatic insulin signaling. Am J Physiol Endocrinol Metab 294: E307-E315, 2008. First published November 20, 2007 doi:10.1152/ajpendo.00534.2007.-Serine phosphorylation of insulin receptor substrate (IRS) proteins is a potential inhibitory mechanism in insulin signaling. Here we show that IRS-2 is phosphorylated by glycogen synthase kinase (GSK)-3. Phosphorylation by GSK-3 requires prior phosphorylation of its substrates, prompting us to identify the "priming kinase." It was found that the stress activator anisomycin enhanced the ability of GSK-3 to phosphorylate IRS-2. Use of a selective c-Jun NH2-terminal kinase (JNK) inhibitor and cells overexpressing JNK implicated JNK as the priming kinase. This allowed us to narrow down the number of potential GSK-3 phosphorylation sites within IRS-2 to four regions that follow the motif SXXXSP. IRS-2 deletion mutants enabled us to localize the GSK-3 and JNK phosphorylation sites to serines 484 and 488, respectively. Mutation at serine 488 reduced JNK phosphorylation of IRS-2, and mutation of each site separately abolished GSK-3 phosphorylation of IRS-2. Treatment of H4IIE liver cells with anisomycin inhibited insulin-induced tyrosine phosphorylation of IRS-2; inhibition was reversed by pretreatment with the JNK and GSK-3 inhibitors. Moreover, overexpression of JNK and GSK-3 in H4IIE cells reduced insulin-induced tyrosine phosphorylation of IRS-2 and its association with the p85 regulatory subunit of phosphatidylinositol 3-kinase. Finally, both GSK-3 and JNK are abnormally upregulated in the diabetic livers of ob/obmice. Together, our data indicate that IRS-2 is sequentially phosphorylated by JNK and GSK-3 at serines 484/488 and provide evidence for their inhibitory role in hepatic insulin signaling. liver cells; insulin resistance THE INSULIN RECEPTOR SUBSTRATE (IRS) proteins are cytoplasmic adaptor proteins that mediate most, if not all, insulin signaling pathways. Of the six different IRS proteins identified, IRS-1 and IRS-2 participate in insulin-mediating mitogenic growth and nutrient homeostasis (66). IRS-1/2 proteins become tyrosyl-phosphorylated by the insulin receptor (IR) tyrosine kinase and simultaneously initiate multiple signaling cascades via the recruitment of SH2-containing proteins, including the p85 regulatory subunit of phosphatidylinositol 3-kinase (PI3-kinase), Grb-2, SHP2, Nck, and Crk (37, 65). These signaling molecules activate downstream effectors that mediate the metabolic and growth stimulatory effects of insulin Increasing evidence now suggests that serine/threonine phosphorylation of IRS-1 is a key player in negative-feedback regulation of insulin signaling. Studies detected enhanced in vivo serine phosphorylation of IRS-1 in diabetic tissue
Safety and efficacy of transcatheter closure of atrial septal defect type II under transthoracic echocardiographic guidance: A case control study
Background: Transcatheter closure of secundum atrial septal defect is routinely performed under general anesthesia and transesophageal echocardiography guidance. If patients have good echo windows, the procedure could be performed under transthoracic echo guidance. Aim of study: To evaluate safety and efficacy of the intervention using fluoroscopy and echo guidance. Methods: In a case control study design, 180 patients underwent atrial septal defect closure between January 2010 and December 2016. In 32 patients, the intervention was performed under fluoroscopy and transthoracic echo guidance. Our study group consisted of 22 out of 32 patients (<13 years old). For the other 10 patients, we could not find a matching pair. The data of the study group were compared with an age, weight, and height matched group (controls), who underwent the procedure under transesophageal echocardiography guidance. Results: The diameter of the atrial septal defect, septal length, and most of the rims were comparable. The superior rim and inferior rims were longer in the study group. The devices chosen for the cases were larger than the control group. Procedure time and fluoroscopy times were shorter in the study group. Success rate was comparable. On follow-up, both groups had almost no or minimal incidence of residual shunt. Conclusion: We conclude that transcatheter closure of atrial septal defect under fluoroscopy and transthoracic echo guidance is safe and successful in selected patients who have single central atrial septal defect with adequate septal lengths and adequate septal rims, with high incidence of complete occlusion rate. Keywords: 2D echocardiography, Atrial septal defect, Case control study, Transcatheter closure, Transesophageal echocardiograph
Evidence for an Alternative Glycolytic Pathway in Rapidly Proliferating Cells
Proliferating cells, including cancer cells, require altered metabolism to efficiently incorporate nutrients such as glucose into biomass. The M2 isoform of pyruvate kinase (PKM2) promotes the metabolism of glucose by aerobic glycolysis and contributes to anabolic metabolism. Paradoxically, decreased pyruvate kinase enzyme activity accompanies the expression of PKM2 in rapidly dividing cancer cells and tissues. We demonstrate that phosphoenolpyruvate (PEP), the substrate for pyruvate kinase in cells, can act as a phosphate donor in mammalian cells because PEP participates in the phosphorylation of the glycolytic enzyme phosphoglycerate mutase (PGAM1) in PKM2-expressing cells. We used mass spectrometry to show that the phosphate from PEP is transferred to the catalytic histidine (His11) on human PGAM1. This reaction occurred at physiological concentrations of PEP and produced pyruvate in the absence of PKM2 activity. The presence of histidine-phosphorylated PGAM1 correlated with the expression of PKM2 in cancer cell lines and tumor tissues. Thus, decreased pyruvate kinase activity in PKM2-expressing cells allows PEP-dependent histidine phosphorylation of PGAM1 and may provide an alternate glycolytic pathway that decouples adenosine triphosphate production from PEP-mediated phosphotransfer, allowing for the high rate of glycolysis to support the anabolic metabolism observed in many proliferating cells.Damon Runyon Cancer Research FoundationBurroughs Wellcome FundAmerican Cancer SocietyDana-Farber/Harvard Cancer CenterNational Institutes of Health (U.S.) (NIH 1K08CA136983)National Institutes of Health (U.S.) (NIH 5P30CA006516-43)National Institutes of Health (U.S.) (NIH 5 T32 CA009361-28)National Institutes of Health (U.S.) (NIH R21/R33 DK070299)National Institutes of Health (U.S.) (NIH P01GM047467)National Institutes of Health (U.S.) (NIH R01 AI078063)National Institutes of Health (U.S.) (NIH R21 CA12862)National Institutes of Health (U.S.) (NIH R01-GM56302)United States. Public Health Service (NIH P01CA089021)National Institutes of Health (U.S.) (NIH 1P01CA120964-01A
Metabolic Regulation of Protein N-Alpha-Acetylation by Bcl-xL Promotes Cell Survival
Previous experiments suggest a connection between the N-alpha-acetylation of proteins and sensitivity of cells to apoptotic signals. Here, we describe a biochemical assay to detect the acetylation status of proteins and demonstrate that protein N-alpha-acetylation is regulated by the availability of acetyl-CoA. Because the antiapoptotic protein Bcl-xL is known to influence mitochondrial metabolism, we reasoned that Bcl-xL may provide a link between protein N-alpha-acetylation and apoptosis. Indeed, Bcl-xL overexpression leads to a reduction in levels of acetyl-CoA and N-alpha-acetylated proteins in the cell. This effect is independent of Bax and Bak, the known binding partners of Bcl-xL. Increasing cellular levels of acetyl-CoA by addition of acetate or citrate restores protein N-alpha-acetylation in Bcl-xL-expressing cells and confers sensitivity to apoptotic stimuli. We propose that acetyl-CoA serves as a signaling molecule that couples apoptotic sensitivity to metabolism by regulating protein N-alpha-acetylation