Glucose 6 phosphatase dehydrogenase (G6PD) and neurodegenerative disorders: Mapping diagnostic and therapeutic opportunities

OpenAIRE

Manju Tiwari

2017-01-01

Glucose 6 phosphate dehydrogenase (G6PD) is a key and rate limiting enzyme in the pentose phosphate pathway (PPP). The physiological significance of enzyme is providing reduced energy to specific cells like erythrocyte by maintaining co-enzyme nicotinamide adenine dinucleotide phosphate (NADPH). There are preponderance research findings that demonstrate the enzyme (G6PD) role in the energy balance, and it is associated with blood-related diseases and disorders, primarily the anemia resulted f...

Integrative proteomics and biochemical analyses define Ptc6p as the Saccharomyces cerevisiae pyruvate dehydrogenase phosphatase.

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Guo, Xiao; Niemi, Natalie M; Coon, Joshua J; Pagliarini, David J

2017-07-14

The pyruvate dehydrogenase complex (PDC) is the primary metabolic checkpoint connecting glycolysis and mitochondrial oxidative phosphorylation and is important for maintaining cellular and organismal glucose homeostasis. Phosphorylation of the PDC E1 subunit was identified as a key inhibitory modification in bovine tissue ∼50 years ago, and this regulatory process is now known to be conserved throughout evolution. Although Saccharomyces cerevisiae is a pervasive model organism for investigating cellular metabolism and its regulation by signaling processes, the phosphatase(s) responsible for activating the PDC in S. cerevisiae has not been conclusively defined. Here, using comparative mitochondrial phosphoproteomics, analyses of protein-protein interactions by affinity enrichment-mass spectrometry, and in vitro biochemistry, we define Ptc6p as the primary PDC phosphatase in S. cerevisiae Our analyses further suggest additional substrates for related S. cerevisiae phosphatases and describe the overall phosphoproteomic changes that accompany mitochondrial respiratory dysfunction. In summary, our quantitative proteomics and biochemical analyses have identified Ptc6p as the primary-and likely sole- S. cerevisiae PDC phosphatase, closing a key knowledge gap about the regulation of yeast mitochondrial metabolism. Our findings highlight the power of integrative omics and biochemical analyses for annotating the functions of poorly characterized signaling proteins. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Novel Glucose-1-Phosphatase with High Phytase Activity and Unusual Metal Ion Activation from Soil Bacterium Pantoea sp. Strain 3.5.1.

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Suleimanova, Aliya D; Beinhauer, Astrid; Valeeva, Liia R; Chastukhina, Inna B; Balaban, Nelly P; Shakirov, Eugene V; Greiner, Ralf; Sharipova, Margarita R

2015-10-01

Phosphorus is an important macronutrient, but its availability in soil is limited. Many soil microorganisms improve the bioavailability of phosphate by releasing it from various organic compounds, including phytate. To investigate the diversity of phytate-hydrolyzing bacteria in soil, we sampled soils of various ecological habitats, including forest, private homesteads, large agricultural complexes, and urban landscapes. Bacterial isolate Pantoea sp. strain 3.5.1 with the highest level of phytase activity was isolated from forest soil and investigated further. The Pantoea sp. 3.5.1 agpP gene encoding a novel glucose-1-phosphatase with high phytase activity was identified, and the corresponding protein was purified to apparent homogeneity, sequenced by mass spectroscopy, and biochemically characterized. The AgpP enzyme exhibits maximum activity and stability at pH 4.5 and at 37°C. The enzyme belongs to a group of histidine acid phosphatases and has the lowest Km values toward phytate, glucose-6-phosphate, and glucose-1-phosphate. Unexpectedly, stimulation of enzymatic activity by several divalent metal ions was observed for the AgpP enzyme. High-performance liquid chromatography (HPLC) and high-performance ion chromatography (HPIC) analyses of phytate hydrolysis products identify dl-myo-inositol 1,2,4,5,6-pentakisphosphate as the final product of the reaction, indicating that the Pantoea sp. AgpP glucose-1-phosphatase can be classified as a 3-phytase. The identification of the Pantoea sp. AgpP phytase and its unusual regulation by metal ions highlight the remarkable diversity of phosphorus metabolism regulation in soil bacteria. Furthermore, our data indicate that natural forest soils harbor rich reservoirs of novel phytate-hydrolyzing enzymes with unique biochemical features. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Phosphatase activity of Poa pratensis seeds. II. Purification and characterization of acid phosphatase Ia2 and Ia3

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I. Lorenc-Kubis

2015-01-01

Full Text Available Two acid phosphatases (Ia2, Ia3 have been isolated from Poa pratensis seeds and partially purified. Both enzymes showed maximal activity at pH 4,9. They exhibited high activity towards p-nitrophenyl phosphate, inorganic pyrophosphate and phenyl phosphate, much less activity towards glucose-6 phosphate, and mononucleotides. Phosphatases a2 and a3 differed in their activity towards ADP. Orthophosphate, fluoride and Zn2+ were effective inhibitors. EDTA, β-mercaptoethanol and Mg2+ activated phophatase a2 but had no effect on phosphatase a3. Zn2+ inhibited the activity of phosphatase a2 noncompetitively, whereas phosphatase a3 showed inhibition of mixed type. Trypsin, chymotrypsin and pronase had no effect on the enzyme activities of both molecular forms.

Glucose 6 phosphatase dehydrogenase (G6PD and neurodegenerative disorders: Mapping diagnostic and therapeutic opportunities

Directory of Open Access Journals (Sweden)

Manju Tiwari

2017-12-01

Full Text Available Glucose 6 phosphate dehydrogenase (G6PD is a key and rate limiting enzyme in the pentose phosphate pathway (PPP. The physiological significance of enzyme is providing reduced energy to specific cells like erythrocyte by maintaining co-enzyme nicotinamide adenine dinucleotide phosphate (NADPH. There are preponderance research findings that demonstrate the enzyme (G6PD role in the energy balance, and it is associated with blood-related diseases and disorders, primarily the anemia resulted from G6PD deficiency. The X-linked genetic deficiency of G6PD and associated non-immune hemolytic anemia have been studied widely across the globe. Recent advancement in biology, more precisely neuroscience has revealed that G6PD is centrally involved in many neurological and neurodegenerative disorders. The neuroprotective role of the enzyme (G6PD has also been established, as well as the potential of G6PD in oxidative damage and the Reactive Oxygen Species (ROS produced in cerebral ischemia. Though G6PD deficiency remains a global health issue, however, a paradigm shift in research focusing the potential of the enzyme in neurological and neurodegenerative disorders will surely open a new avenue in diagnostics and enzyme therapeutics. Here, in this study, more emphasis was made on exploring the role of G6PD in neurological and inflammatory disorders as well as non-immune hemolytic anemia, thus providing diagnostic and therapeutic opportunities.

Effect of rat whole-body irradiation on oxidase chain and glucose-6-phosphatase of liver microsome: influence of cysteamine

International Nuclear Information System (INIS)

Bernard, Pierre.

1979-11-01

Three enzymatic systems of the male rat liver endoplasmic reticulum were studied by biochemical methods. Two means of investigation were used: - whole-body irradiation of the animal, - administration of cysteamine. The results obtained are discussed, in view of the functioning of these enzymatic systems, from two viewpoints: - the study of enzymatic radiolesions in relation to the radiobiological effect on the animal, the organ and the sub-cellular organite, - the study of chemical radioprotection. After a 900 R whole-body gamma irradiation a severe drop was observed in the enzymatic activity of two essential elements of the microsome oxydase chain: NADPH cytochrome P450 reductase and ethylmorphine N-demethylation. Glucose 6 phosphatase is also impaired by irradiation. Here it seems that the microsomal protein fraction could be responsible for the change in the enzyme activity. The irradiation effect is therefore not specific to one enzyme. The changes in these enzymatic activities correspond to the different phases of the acute irradiation syndrome which also affects the weight of the experimental animal and of the organ studied. Cysteamine used under chemical radioprotection conditions was found to be especially useful as a means of investigation complementary to the study of enzymatic radiolesions. From the combined action of irradiation and of the radioprotector it was possible to obtain a partial idea of the mechanisms of these radiolesions [fr

Trehalose 6-phosphate phosphatases of Pseudomonas aeruginosa.

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Cross, Megan; Biberacher, Sonja; Park, Suk-Youl; Rajan, Siji; Korhonen, Pasi; Gasser, Robin B; Kim, Jeong-Sun; Coster, Mark J; Hofmann, Andreas

2018-04-24

The opportunistic bacterium Pseudomonas aeruginosa has been recognized as an important pathogen of clinical relevance and is a leading cause of hospital-acquired infections. The presence of a glycolytic enzyme in Pseudomonas, which is known to be inhibited by trehalose 6-phosphate (T6P) in other organisms, suggests that these bacteria may be vulnerable to the detrimental effects of intracellular T6P accumulation. In the present study, we explored the structural and functional properties of trehalose 6-phosphate phosphatase (TPP) in P. aeruginosa in support of future target-based drug discovery. A survey of genomes revealed the existence of 2 TPP genes with either chromosomal or extrachromosomal location. Both TPPs were produced as recombinant proteins, and characterization of their enzymatic properties confirmed specific, magnesium-dependent catalytic hydrolysis of T6P. The 3-dimensional crystal structure of the chromosomal TPP revealed a protein dimer arising through β-sheet expansion of the individual monomers, which possess the overall fold of halo-acid dehydrogenases.-Cross, M., Biberacher, S., Park, S.-Y., Rajan, S., Korhonen, P., Gasser, R. B., Kim, J.-S., Coster, M. J., Hofmann, A. Trehalose 6-phosphate phosphatases of Pseudomonas aeruginosa.

SLC37A1 and SLC37A2 are phosphate-linked, glucose-6-phosphate antiporters.

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Chi-Jiunn Pan

Full Text Available Blood glucose homeostasis between meals depends upon production of glucose within the endoplasmic reticulum (ER of the liver and kidney by hydrolysis of glucose-6-phosphate (G6P into glucose and phosphate (P(i. This reaction depends on coupling the G6P transporter (G6PT with glucose-6-phosphatase-α (G6Pase-α. Only one G6PT, also known as SLC37A4, has been characterized, and it acts as a P(i-linked G6P antiporter. The other three SLC37 family members, predicted to be sugar-phosphate:P(i exchangers, have not been characterized functionally. Using reconstituted proteoliposomes, we examine the antiporter activity of the other SLC37 members along with their ability to couple with G6Pase-α. G6PT- and mock-proteoliposomes are used as positive and negative controls, respectively. We show that SLC37A1 and SLC37A2 are ER-associated, P(i-linked antiporters, that can transport G6P. Unlike G6PT, neither is sensitive to chlorogenic acid, a competitive inhibitor of physiological ER G6P transport, and neither couples to G6Pase-α. We conclude that three of the four SLC37 family members are functional sugar-phosphate antiporters. However, only G6PT/SLC37A4 matches the characteristics of the physiological ER G6P transporter, suggesting the other SLC37 proteins have roles independent of blood glucose homeostasis.

Underestimation of glucose turnover measured with [6-3H]- and [6,6-2H]- but not [6-14C]glucose during hyperinsulinemia in humans

International Nuclear Information System (INIS)

McMahon, M.M.; Schwenk, W.F.; Haymond, M.W.; Rizza, R.A.

1989-01-01

Recent studies indicate that hydrogen-labeled glucose tracers underestimate glucose turnover in humans under conditions of high flux. The cause of this underestimation is unknown. To determine whether the error is time-, pool-, model-, or insulin-dependent, glucose turnover was measured simultaneously with [6-3H]-, [6,6-2H2]-, and [6-14C]glucose during a 7-h infusion of either insulin (1 mU.kg-1.min-1) or saline. During the insulin infusion, steady-state glucose turnover measured with both [6-3H]glucose (8.0 +/- 0.5 mg.kg-1.min-1) and [6,6-2H2]glucose (7.6 +/- 0.5 mg.kg-1.min-1) was lower (P less than .01) than either the glucose infusion rate required to maintain euglycemia (9.8 +/- 0.7 mg.kg-1.min-1) or glucose turnover determined with [6-14C]glucose and corrected for Cori cycle activity (9.8 +/- 0.7 mg.kg-1.min-1). Consequently negative glucose production rates (P less than .01) were obtained with either [6-3H]- or [6,6-2H2]- but not [6-14C]glucose. The difference between turnover estimated with [6-3H]glucose and actual glucose disposal (or 14C glucose flux) did not decrease with time and was not dependent on duration of isotope infusion. During saline infusion, estimates of glucose turnover were similar regardless of the glucose tracer used. High-performance liquid chromatography of the radioactive glucose tracer and plasma revealed the presence of a tritiated nonglucose contaminant. Although the contaminant represented only 1.5% of the radioactivity in the [6-3H]glucose infusate, its clearance was 10-fold less (P less than .001) than that of [6-3H]glucose. This resulted in accumulation in plasma, with the contaminant accounting for 16.6 +/- 2.09 and 10.8 +/- 0.9% of what customarily is assumed to be plasma glucose radioactivity during the insulin or saline infusion, respectively (P less than .01)

Phenotypic and gene expression changes between low (glucose-responsive) and High (glucose non-responsive) MIN-6 beta cells

DEFF Research Database (Denmark)

O´Driscoll, L.; Gammell, p.; McKierman, E.

2006-01-01

The long-term potential to routinely use replacement beta cells/islets as cell therapy for type 1 diabetes relies on our ability to culture such cells/islets, in vitro, while maintaining their functional status. Previous beta cell studies, by ourselves and other researchers, have indicated...... that the glucose-stimulated insulin secretion (GSIS) phenotype is relatively unstable, in long-term culture. This study aimed to investigate phenotypic and gene expression changes associated with this loss of GSIS, using the MIN-6 cell line as model. Phenotypic differences between MIN-6(L, low passage) and MIN-6(H......, high passage) were determined by ELISA (assessing GSIS and cellular (pro)insulin content), proliferation assays, phase contrast light microscopy and analysis of alkaline phosphatase expression. Differential mRNA expression was investigated using microarray, bioinformatics and real-time PCR technologies...

Dexamethasone increases glucose cycling, but not glucose production, in healthy subjects

International Nuclear Information System (INIS)

Wajngot, A.; Khan, A.; Giacca, A.; Vranic, M.; Efendic, S.

1990-01-01

We established that measurement of glucose fluxes through glucose-6-phosphatase (G-6-Pase; hepatic total glucose output, HTGO), glucose cycling (GC), and glucose production (HGP), reveals early diabetogenic changes in liver metabolism. To elucidate the mechanism of the diabetogenic effect of glucocorticoids, we treated eight healthy subjects with oral dexamethasone (DEX; 15 mg over 48 h) and measured HTGO with [2-3H]glucose and HGP with [6-3H]glucose postabsorptively and during a 2-h glucose infusion (11.1 mumol.kg-1.min-1). [2-3H]- minus [6-3H]glucose equals GC. DEX significantly increased plasma glucose, insulin, C peptide, and HTGO, while HGP was unchanged. In controls and DEX, glucose infusion suppressed HTGO (82 vs. 78%) and HGP (87 vs. 91%). DEX increased GC postabsorptively (three-fold) P less than 0.005 and during glucose infusion (P less than 0.05) but decreased metabolic clearance and glucose uptake (Rd), which eventually normalized, however. Because DEX increased HTGO (G-6-Pase) and not HGP (glycogenolysis + gluconeogenesis), we assume that DEX increases HTGO and GC in humans by activating G-6-Pase directly, rather than by expanding the glucose 6-phosphate pool. Hyperglycemia caused by peripheral effects of DEX can also contribute to an increase in GC by activating glucokinase. Therefore, measurement of glucose fluxes through G-6-Pase and GC revealed significant early effects of DEX on hepatic glucose metabolism, which are not yet reflected in HGP

Evolutionary history of glucose-6-phosphatase encoding genes in vertebrate lineages: towards a better understanding of the functions of multiple duplicates.

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Marandel, Lucie; Panserat, Stéphane; Plagnes-Juan, Elisabeth; Arbenoits, Eva; Soengas, José Luis; Bobe, Julien

2017-05-02

Glucose-6-phosphate (G6pc) is a key enzyme involved in the regulation of the glucose homeostasis. The present study aims at revisiting and clarifying the evolutionary history of g6pc genes in vertebrates. g6pc duplications happened by successive rounds of whole genome duplication that occurred during vertebrate evolution. g6pc duplicated before or around Osteichthyes/Chondrichthyes radiation, giving rise to g6pca and g6pcb as a consequence of the second vertebrate whole genome duplication. g6pca was lost after this duplication in Sarcopterygii whereas both g6pca and g6pcb then duplicated as a consequence of the teleost-specific whole genome duplication. One g6pca duplicate was lost after this duplication in teleosts. Similarly one g6pcb2 duplicate was lost at least in the ancestor of percomorpha. The analysis of the evolution of spatial expression patterns of g6pc genes in vertebrates showed that all g6pc were mainly expressed in intestine and liver whereas teleost-specific g6pcb2 genes were mainly and surprisingly expressed in brain and heart. g6pcb2b, one gene previously hypothesised to be involved in the glucose intolerant phenotype in trout, was unexpectedly up-regulated (as it was in liver) by carbohydrates in trout telencephalon without showing significant changes in other brain regions. This up-regulation is in striking contrast with expected glucosensing mechanisms suggesting that its positive response to glucose relates to specific unknown processes in this brain area. Our results suggested that the fixation and the divergence of g6pc duplicated genes during vertebrates' evolution may lead to adaptive novelty and probably to the emergence of novel phenotypes related to glucose homeostasis.

Zinc-ion-dependent acid phosphatase exhibits magnesium-ion-dependent myo-inositol-1-phosphatase activity.

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Fujimoto, S; Okano, I; Tanaka, Y; Sumida, Y; Tsuda, J; Kawakami, N; Shimohama, S

1996-06-01

We have purified bovine brain Zn(2+)-dependent acid phosphatase (Zn(2+)-APase), which requires Zn2+ ions to hydrolyze the substrate p-nitrophenyl phosphate (pNPP) in an acidic environment. The substrate specificity and metal requirement of Zn(2+)-APase at a physiological pH was also studied. The enzyme exhibited hydrolytic activity on myo-inositol-1- and -2-monophosphates, 2'-adenosine monophosphate, 2'-guanosine monophosphate, and the alpha- and beta-glycerophosphates, glucose-1-phosphate, and fructose-6-phosphate in 50 mM Tris-HCl buffer (pH 7.4) in the presence of Mg2+ ions, but not on pNPP and phosphotyrosine. Zn2+, Mn2+ and Co2+ ions were less effective for activation. Among the above substrates, myo-inositol-1-phosphate was the most susceptible to hydrolysis by the enzyme in the presence of 3 mM Mg2+ ions. The enzyme exhibited an optimum pH at around 8 for myo-inositol-1-phosphate in the presence of 3 mM Mg2+ ions. The Mg(2+)-dependent myo-inositol-1-phosphatase activity of the enzyme was significantly inhibited by Li+ ions. The Zn(2+)-dependent p-nitrophenyl phosphatase activity and Mg(2+)-dependent myo-inositol-1-phosphatase activity of the purified enzyme fraction exhibited similar behavior on Sephadex G-100 and Mono Q colomns. These findings suggest that Zn(2+)-APase also exhibits Mg(2+)-dependent myo-inositol-1-phosphatase activity under physiological conditions.

Purification of acidic phosphatase from mustard seedlings

OpenAIRE

sprotocols

2014-01-01

### INTRODUCTION Phosphate esters are widely distributed in any organism. Nucleic acids, metabolic intermediates like glucose-6-phosphate, energy-rich substrates (AMP, creatine phosphate) are some obvious examples. While many metabolic intermediates are activated through the transfer of phosphate groups (e.g., by kinases) it is equally important that phosphate esters can also be rapidly broken down. The hydrolytic removal of phosphate groups from phosphoesters is catalyzed by phosphatases...

Validation of 123I-6-deoxy-6-iodo-D-glucose (6-DIC) as tracer for the in-vivo glucose transport

International Nuclear Information System (INIS)

Perret, P.; Ghezzi, C.; Mathieu, J.P.; Morin, C.; Vidal, M.; Comet, M.; Fagret, D.

1997-01-01

The evaluation of the glucose transport is very important clinically because alterations of this transport were described in numerous pathologies, in neurology, oncology and endocrinology. A new analog of the 123 I-labelled has been synthesized: 123 I-6-deoxy-6-iodo-D-glucose (6-DIG). Its in-vitro biological behaviour is similar to that of 3-O-methyl-D-glucose (3-OMG), the reference tracer of glucose transport. The aim of the study was to determine if it is possible to make evident by 6-DIG a variations of in-vivo glucose transport. The studies were effected on a model of homozygote mice (db/db), genetically diabetic (NIDDM), presenting a severe insulin-resistance, characterized by deficient glucose transport in response to insulin. The studies of 6-DIG biodistribution (5 nmol/mouse) with (1.5 UI/Kg) or without exogenous insulin, were conducted in diabetic mice (db/db) and in non-diabetic (db/+) control mice. The results show that the capture of 6-DIG, as well as that of glucose, increases (by 30%) in response to insulin in most of insulin-sensitive tissues in control mice. In the insulin-resistant and hyperglycemic db/db mouse, the capture of 6-DIG is not modified, no matter whether the exogenous insulin is present. In conclusion, the 6-DIG is able to make evident a lack of glucose transport in heart, diaphragm and skeletal muscle in diabetic mouse and a physiological variation of this transport in response to insulin, in the control mouse. This result should be stressed because for the first time it is possible to evidence in-vivo variations into glucose transport with a iodated molecule

Glucose and fructose 6-phosphate cycle in humans

International Nuclear Information System (INIS)

Karlander, S.; Roovete, A.; Vranic, M.; Efendic, S.

1986-01-01

We have determined the rate of glucose cycling by comparing turnovers of [2- 3 H]- and [6- 3 H]glucose under basal conditions and during a glucose infusion. Moreover, the activity of the fructose 6-phosphate cycle was assessed by comparing [3- 3 H]- and [6- 3 H]glucose. The study included eight lean subjects with normal glucose tolerance. They participated in two randomly performed investigations. In one experiment [2- 3 H]- and [6- 3 H]glucose were given simultaneously, while in the other only [3- 3 H]glucose was given. The basal rate of glucose cycling was 0.32 +/- 0.08 mg X kg-1 X min-1 or 17% of basal glucose production (P less than 0.005). During glucose infusion the activity of endogenous glucose cycling did not change but since glucose production was suppressed it amounted to 130% of glucose production. The basal fructose 6-phosphate cycle could be detected only in three subjects and was suppressed during glucose infusion. In conclusion, the glucose cycle is active in healthy humans both in basal conditions and during moderate hyperglycemia. In some subjects, the fructose 6-phosphate cycle also appears to be active. Thus it is preferable to use [6- 3 H]glucose rather than [3- 3 H]glucose when measuring glucose production and particularly when assessing glucose cycle

Phosphatase activity of Poa pratensis seeds. I. Preliminary studies on acid phosphatase II

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I. Lorenc-Kubis

2015-01-01

Full Text Available Acid phosphatase (EC 3.1.3.2 was extracted with 0.1 M sodium acetate buffer pH 5.1 from Poa pratensis seeds, and separated into three fractions by chromatography on DEAE cellulose. The highest activity was found in fraction Il-b (acid phosphatase II. The activity of the enzyme was optimal at pH 4.9. It hydrolyzed p-nitrophenyl phosphate most readily among the various phosphomonoesters examined. Acid phosphatase II showed also a high activity toward β-naphtyl phosphate and phenyl phosphate, very low activity towards β-glycero phosphate, 5'-GMP and no activity with glucose-1 phosphate. The enzyme was inhibited by Ca2+ and fluoride, but activated by Mg2+. EDTA had no influence on the activity of the enzyme.

Phosphatase activity of Poa pratensis seeds. l. Preliminary studies on acid phosphatase II

Energy Technology Data Exchange (ETDEWEB)

Lorenc-Kubis, I.; Morawiecka, B.

1973-01-01

Acid phosphatase (EC 3.1.3.2) was extracted from 0.1 M sodium acetate buffer, pH 5.1 from Poa pratensis seeds, and separated into three fractions by chromatography on DEAE cellulose. The highest activity was found in fraction II-b (acid phosphatase II). The activity of the enzyme was optimal at pH 4.9. It hydrolyzed p-nitrophenyl phosphate most readily among the various phosphomonoesters examined. Acid phosphatase II showed also a high activity toward ..beta..-naphtyl phosphate and phenyl phosphate, very low activity towards ..beta..-glycero phosphate, 5'-GMP and no activity with glucose-1 phosphate. The enzyme was inhibited by Ca/sup 2 +/ and fluoride, but activated by Mg/sup 2 +/. EDTA had no influence on the activity of the enzyme. 12 references, 3 figures, 4 tables.

Increased ethanol accumulation from glucose via reduction of ATP level in a recombinant strain of Saccharomyces cerevisiae overexpressing alkaline phosphatase.

Science.gov (United States)

Semkiv, Marta V; Dmytruk, Kostyantyn V; Abbas, Charles A; Sibirny, Andriy A

2014-05-15

The production of ethyl alcohol by fermentation represents the largest scale application of Saccharomyces cerevisiae in industrial biotechnology. Increased worldwide demand for fuel bioethanol is anticipated over the next decade and will exceed 200 billion liters from further expansions. Our working hypothesis was that the drop in ATP level in S. cerevisiae cells during alcoholic fermentation should lead to an increase in ethanol production (yield and productivity) with a greater amount of the utilized glucose converted to ethanol. Our approach to achieve this goal is to decrease the intracellular ATP level via increasing the unspecific alkaline phosphatase activity. Intact and truncated versions of the S. cerevisiae PHO8 gene coding for vacuolar or cytosolic forms of alkaline phosphatase were fused with the alcohol dehydrogenase gene (ADH1) promoter. The constructed expression cassettes used for transformation vectors also contained the dominant selective marker kanMX4 and S. cerevisiae δ-sequence to facilitate multicopy integration to the genome. Laboratory and industrial ethanol producing strains BY4742 and AS400 overexpressing vacuolar form of alkaline phosphatase were characterized by a slightly lowered intracellular ATP level and biomass accumulation and by an increase in ethanol productivity (13% and 7%) when compared to the parental strains. The strains expressing truncated cytosolic form of alkaline phosphatase showed a prolonged lag-phase, reduced biomass accumulation and a strong defect in ethanol production. Overexpression of vacuolar alkaline phosphatase leads to an increased ethanol yield in S. cerevisiae.

Direct analysis of [6,6-(2)H2]glucose and [U-(13)C6]glucose dry blood spot enrichments by LC-MS/MS.

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Coelho, Margarida; Mendes, Vera M; Lima, Inês S; Martins, Fátima O; Fernandes, Ana B; Macedo, M Paula; Jones, John G; Manadas, Bruno

2016-06-01

A liquid chromatography tandem mass spectrometry (LC-MS/MS) using multiple reaction monitoring (MRM) in a triple-quadrupole scan mode was developed and comprehensively validated for the determination of [6,6-(2)H2]glucose and [U-(13)C6]glucose enrichments from dried blood spots (DBS) without prior derivatization. The method is demonstrated with dried blood spots obtained from rats administered with a primed-constant infusion of [U-(13)C6]glucose and an oral glucose load enriched with [6,6-(2)H2]glucose. The sensitivity is sufficient for analysis of the equivalent to blood and the overall method was accurate and precise for the determination of DBS isotopic enrichments. Copyright © 2016 Elsevier B.V. All rights reserved.

Underestimation of glucose turnover corrected with high-performance liquid chromatography purification of [6-3H]glucose

International Nuclear Information System (INIS)

Schwenk, W.F.; Butler, P.C.; Haymond, M.W.; Rizza, R.A.

1990-01-01

We have recently reported that during infusion of commercially available [6-3H]glucose, a radioactive nonglucose contaminant may accumulate in plasma causing errors in the measurement of glucose turnover. To determine whether purification of this tracer by HPLC (high-performance liquid chromatography) before infusion would eliminate the contaminant in plasma and remove the underestimation of glucose turnover reported during hyperinsulinemia, four normal subjects each underwent two 5-h euglycemic clamps during infusion of insulin (1 mU.kg-1.min-1). Glucose turnover was measured with either commercially available [6-3H]glucose or with HPLC-purified [6-3H]glucose. HPLC analysis of samples from the clamps done with commercially available [6-3H]glucose showed that 9.7% of the infused tracer and 26% of the plasma glucose 3H radioactivity were contaminants. In contrast, no contaminant was observed in the plasma during infusion of HPLC-purified [6-3H]glucose. During the last hour of the clamp, mean glucose turnover using commercially available [6-3H]glucose was less (P less than 0.01) than the mean glucose infusion rate (7.6 +/- 0.3 vs. 10.5 +/- 0.3 mg.kg-1.min-1) yielding apparent negative (P less than 0.001) hepatic glucose release. In contrast, when HPLC-purified [6-3H]glucose was employed, glucose turnover equaled the glucose infusion rate (10.4 +/- 0.9 vs. 10.2 +/- 0.9 mg.kg-1.min-1) and hepatic glucose release was no longer negative. We conclude that removal of a tritiated nonglucose contaminant in [6-3H]glucose by HPLC yields correct estimations of glucose turnover at steady state

and alanine (EC. 2.6.1.2) transaminases, and alkaline phosphatase

African Journals Online (AJOL)

The activities of aspartate (E.C. 2.6.1.1) and alanine (E.C. 2.6.1.2) transaminases (AST and ALT, respectively), and alkaline phosphatase (ALP) (E.C. 3.1.3.1) were determined in erythrocytes obtained from 20 HbAA, 15 HbAS and 12 HbSS human subjects. The results showed that the three enzymes had different levels of ...

Influence of acid phosphatase activity on the saccharification of potato maltodextrins by Aspergillus niger glucoamylase

Energy Technology Data Exchange (ETDEWEB)

Zyla, K. (Akademia Rolnicza, Cracow (Poland). Dept. of Biotechnology)

1990-01-01

A preparation of Aspergillus niger acid phosphatase, which had the temperature optimum 60deg C, pH optimum 1.8-3.0; good stability at pH 4-5, the ability to hydrolyze glucose-6-phosphate at a high rate, and substantial lack of glucogenic activities, was used simultaneously with a glucoamylase in order to learn its influence on the saccharification of potato maltodextrins. The addition of the acid phosphatase activity in amounts that gave the 50 fold increase, as compared to phosphatase activity which naturally occurs in the gluocoamylase (GA) preparation 'AMG-200', was found to influence on the DE level, mainly at the high substrate concentration (40% d.s.) and low glucoamylase dosage (60-100 GAU/kg d.s.). It may also be possible, when using the acid phosphatase addition, to shorten the saccharification time. (orig.).

Regulation of cortical contractility and spindle positioning by the protein phosphatase 6 PPH-6 in one-cell stage C. elegans embryos

Science.gov (United States)

Afshar, Katayoun; Werner, Michael E.; Tse, Yu Chung; Glotzer, Michael; Gönczy, Pierre

2010-01-01

Modulation of the microtubule and the actin cytoskeleton is crucial for proper cell division. Protein phosphorylation is known to be an important regulatory mechanism modulating these cytoskeletal networks. By contrast, there is a relative paucity of information regarding how protein phosphatases contribute to such modulation. Here, we characterize the requirements for protein phosphatase PPH-6 and its associated subunit SAPS-1 in one-cell stage C. elegans embryos. We establish that the complex of PPH-6 and SAPS-1 (PPH-6/SAPS-1) is required for contractility of the actomyosin network and proper spindle positioning. Our analysis demonstrates that PPH-6/SAPS-1 regulates the organization of cortical non-muscle myosin II (NMY-2). Accordingly, we uncover that PPH-6/SAPS-1 contributes to cytokinesis by stimulating actomyosin contractility. Furthermore, we demonstrate that PPH-6/SAPS-1 is required for the proper generation of pulling forces on spindle poles during anaphase. Our results indicate that this requirement is distinct from the role in organizing the cortical actomyosin network. Instead, we uncover that PPH-6/SAPS-1 contributes to the cortical localization of two positive regulators of pulling forces, GPR-1/2 and LIN-5. Our findings provide the first insights into the role of a member of the PP6 family of phosphatases in metazoan development. PMID:20040490

Acute interleukin-6 administration does not impair muscle glucose uptake or whole-body glucose disposal in healthy humans

DEFF Research Database (Denmark)

Steensberg, Adam; Fischer, Christian P; Sacchetti, Massimo

2003-01-01

adrenaline (epinephrine). IL-6 infusion, irrespective of dose, did not result in any changes to endogenous glucose production, whole-body glucose disposal or leg- glucose uptake. These data demonstrate that acute IL-6 administration does not impair whole-body glucose disposal, net leg-glucose uptake......The cytokine interleukin (IL)-6 has recently been linked with type 2 diabetes mellitus and has been suggested to affect glucose metabolism. To determine whether acute IL-6 administration affects whole-body glucose kinetics or muscle glucose uptake, 18 healthy young men were assigned to one of three...... the cessation of infusion (recovery) to determine endogenous glucose production and whole-body glucose disposal. Infusion with HiIL-6 and LoIL-6 resulted in a marked (P

Genetics Home Reference: glucose-6-phosphate dehydrogenase deficiency

Science.gov (United States)

... deficiency Encyclopedia: Glucose-6-phosphate dehydrogenase test Encyclopedia: Hemolytic anemia Encyclopedia: Newborn jaundice Health Topic: Anemia Health Topic: G6PD Deficiency Health Topic: Newborn Screening Genetic and Rare Diseases Information Center (1 link) Glucose-6-phosphate dehydrogenase ...

Radiosynthesis of 6-[C-11]-D-glucose

International Nuclear Information System (INIS)

Grierson, J.R.; Biskupiak, J.E.; Link, J.M.; Krohn, K.A.

1993-01-01

Availability of 6-[C-11]-D-glucose will permit positron emission tomography (PET) investigations of glucose utilization derived from the pentose shunt which supports biosynthesis in tissues. The first radiosynthesis of 6-[C-11]-D-glucose is described. As much as 1 mCi of 6-[C-11]-D-glucose, sufficient for animal studies, is obtained from [C-11]CO 2 after 100 min with a 16% radiochemical yield (EOB). The radiosynthesis has many attractive features. The method uses [C-11]CH 3 I and combines a Wittig reaction and a stereoselective OsO 4 catalyzed alkene hydroxylation. The OsO 4 hydroxylation of the [C-11]-labeled alkene (9) is accomplished in less than 10 min with high stereoselectivity (94:6) in favor of the 6-[C-11]-D-gluco-isomer. HPLC purification (C-18) of the protected labeled sugar removes the undesired 6-[C-11]-L-ido-sugar at an early stage and avoids the use of an expensive low-capacity ion-exchange HPLC column. OsO 4 , a highly toxic reagent, is removed in the process by adsorption and inactivation on polymer-bound triphenylphosphine. (Author)

Prevalence of glucose-6-phosphate dehydrogenase deficiency in ...

African Journals Online (AJOL)

Background: Glucose-6-phosphate dehydrogenase (G6PD) is a house keeping enzyme which catalyzes the first step in the hexose monophosphate pathway of glucose metabolism. G6PD deficiency is the commonest hemolytic X-linked genetic disease, which affects approximately 400 million people worldwide.

Estimation of liver glucose metabolism after refeeding

International Nuclear Information System (INIS)

Rognstad, R.

1987-01-01

Refeeding or infusing glucose to rats fasted for 24 hr or more causes rapid liver glycogen synthesis, the carbon source now considered to be largely from gluconeogenesis. While substrate cycling between plasma glucose and liver glucose-6P is known to occur, this cycling has apparently been ignored when calculations are made of % contribution of direct and indirect pathways to liver glycogen synthesis, or when hepatic glucose output is calculated from glucose turnover minus the glucose infusion rate. They show that, isotopically, an estimate of the fluxes of liver glucokinase and glucose-6-phosphatase is required to quantitate sources of carbon for liver glycogen synthesis, and to measure hepatic glucose output (or uptake). They propose a method to estimate these fluxes, involving a short infusion of a 14 C labelled gluconeogenic precursor plus (6T)glucose, with determination of isotopic yields in liver glycogen and total glucose. Given also the rate of liver glycogen synthesis, this procedure permits the estimation of net gluconeogenesis and hepatic glucose output or uptake. Also, in vitro evidence against the notion of a drastic zonation of liver carbohydrate metabolism is presented, e.g. raising the glucose concentration from 10 to 25 mM increases the 14 C yield from H 14 CO 3 - in lactate, with the increased pyruvate kinase flux and decreased gluconeogenesis occurring in the same cell type, not opposing pathways in different hepatocyte types (as has been postulated by some to occur in vivo after refeeding

Whole body glucose kinetics in type I diabetes studied with [6,6-2H] and [U-13C]-glucose and the artificial B-cell

International Nuclear Information System (INIS)

Darmaun, D.; Cirillo, D.; Koziet, J.; Chauvet, D.; Young, V.R.; Robert, J.J.

1988-01-01

Dynamic aspects of whole body glucose metabolism were assessed in ten young adult insulin-dependent (type I) diabetic men. Using a primed, continuous intravenous infusion of [6,6- 2 H]glucose and [U- 13 C]glucose, endogenous production, tissue uptake, carbon recycling, and oxidation of glucose were measured in the postabsorptive state. These studies were undertaken after blood glucose had been maintained overnight at 5.9 +/- 0.4 mmol/L (n = 10), and on another night at 10.5 +/- 0.4 mmol/L (n = 4) or 15.2 +/- 0.6 mmol/L (n = 6). In the normoglycemic state, endogenous glucose production averaged 2.15 +/- 0.13 mg x kg-1 x min-1. This value, as well as the rate of glucose carbon recycling (0.16 +/- 0.04 mg x kg-1 x min-1) and glucose oxidation (1.52 +/- 0.16 mg x kg-1 x min-1) are comparable to those found in nondiabetic controls. In the hyperglycemic states at 10 or 15 mmol/L, endogenous glucose production was increased by 11% (P less than .01) and 60% (P less than .01) compared to the normoglycemic states, respectively. Glucose carbon recycling contributed only a small percentage to this variation in glucose production (15% at the 15 mmol/L glucose level). This suggests that if gluconeogenesis participates in the increased glucose output, it is not dependent on a greater systemic supply of three-carbon precursors. The increased rate of glucose production in the hyperglycemic state was quantitatively offset by a rise in urinary glucose excretion. Glucose tissue uptake, as well as glucose oxidation, did not vary between normoglycemic and hyperglycemic states

Fluorometric determination of free glucose and glucose 6-phosphate in cows' milk and other opaque matrices

DEFF Research Database (Denmark)

Larsen, Torben

2015-01-01

Analyses of free glucose and glucose 6-phosphate in milk have until now been dependent upon several time consuming and troublesome procedures. This has limited investigations in the area. The present article presents a new, reliable, analytical procedure, based on enzymatic degradation and fluoro......Analyses of free glucose and glucose 6-phosphate in milk have until now been dependent upon several time consuming and troublesome procedures. This has limited investigations in the area. The present article presents a new, reliable, analytical procedure, based on enzymatic degradation...... and fluorometric detection. Standards and control materials were based on milk that was stripped of intrinsic glucose and glucose 6-phosphate in order to obtain standards and samples based on the same matrix. The analysis works without pre-treatment of the samples, e.g. without centrifugation and precipitation...

Estimation of glucose carbon recycling in children with glycogen storage disease: A 13C NMR study using [U-13C]glucose

International Nuclear Information System (INIS)

Kalderon, B.; Korman, S.H.; Gutman, A.; Lapidot, A.

1989-01-01

A stable isotope procedure to estimate hepatic glucose carbon recycling and thereby elucidate the mechanism by which glucose is produced in patients lacking glucose 6-phosphatase is described. A total of 10 studies was performed in children with glycogen storage disease type I (GSD-I) and type III (GSD-III) and control subjects. A primed dose-constant nasogastric infusion of D-[U- 13 C]glucose or an infusion diluted with nonlabeled glucose solution was administered following different periods of fasting. Hepatic glucose carbon recycling was estimated from 13 C NMR spectra. The values obtained for GSD-I patients coincided with the standard [U- 13 C]glucose dilution curve. These results indicate that the plasma glucose of GSD-I subjects comprises only a mixture of 99% 13 C-enriched D-[U- 13 C]glucose and unlabeled glucose but lacks any recycled glucose. Significantly different glucose carbon recycling values were obtained for two GSD-III patients in comparison to GSD-I patients. The results eliminate a mechanism for glucose production in GSD-I children involving gluconeogenesis. However, glucose release by amylo-1,6-glucosidase activity would result in endogenous glucose production of non- 13 C-labeled and nonrecycled glucose carbon, as was found in this study. In GSD-III patients gluconeogenesis is suggested as the major route for endogenous glucose synthesis. The contribution of the triose-phosphate pathway in these patients has been determined

Adipocyte-specific protein tyrosine phosphatase 1B deletion increases lipogenesis, adipocyte cell size and is a minor regulator of glucose homeostasis.

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Carl Owen

Full Text Available Protein tyrosine phosphatase 1B (PTP1B, a key negative regulator of leptin and insulin signaling, is positively correlated with adiposity and contributes to insulin resistance. Global PTP1B deletion improves diet-induced obesity and glucose homeostasis via enhanced leptin signaling in the brain and increased insulin signaling in liver and muscle. However, the role of PTP1B in adipocytes is unclear, with studies demonstrating beneficial, detrimental or no effect(s of adipose-PTP1B-deficiency on body mass and insulin resistance. To definitively establish the role of adipocyte-PTP1B in body mass regulation and glucose homeostasis, adipocyte-specific-PTP1B knockout mice (adip-crePTP1B(-/- were generated using the adiponectin-promoter to drive Cre-recombinase expression. Chow-fed adip-crePTP1B(-/- mice display enlarged adipocytes, despite having similar body weight/adiposity and glucose homeostasis compared to controls. High-fat diet (HFD-fed adip-crePTP1B(-/- mice display no differences in body weight/adiposity but exhibit larger adipocytes, increased circulating glucose and leptin levels, reduced leptin sensitivity and increased basal lipogenesis compared to controls. This is associated with decreased insulin receptor (IR and Akt/PKB phosphorylation, increased lipogenic gene expression and increased hypoxia-induced factor-1-alpha (Hif-1α expression. Adipocyte-specific PTP1B deletion does not beneficially manipulate signaling pathways regulating glucose homeostasis, lipid metabolism or adipokine secretion in adipocytes. Moreover, PTP1B does not appear to be the major negative regulator of the IR in adipocytes.

Glucose-6-Phosphate Dehydrogenase (G6PD) deficiency in patients ...

African Journals Online (AJOL)

This is a study of Glucose-6-phosphate dehydrogenase(G6PD) deficiency in sickle cell anaemia patients attending the haematology clinic of the Jos University Teaching Hospital (JUTH), Jos- Nigeria. The prevalence of G6PD deficiency among the 130 sickle cell anaemia patients studied was found to be 18.5%. G6PD ...

Glucose Regulates the Expression of the Apolipoprotein A5 Gene

Energy Technology Data Exchange (ETDEWEB)

Fruchart, Jamila; Nowak, Maxime; Helleboid-Chapman, Audrey; Jakel, Heidelinde; Moitrot, Emmanuelle; Rommens, Corinne; Pennacchio, Len A.; Fruchart-Najib, Jamila; Fruchart, Jean-Charles

2008-04-07

The apolipoprotein A5 gene (APOA5) is a key player in determining triglyceride concentrations in humans and mice. Since diabetes is often associated with hypertriglyceridemia, this study explores whether APOA5 gene expression is regulated by alteration in glucose homeostasis and the related pathways. D-glucose activates APOA5 gene expression in a time- and dose-dependent manner in hepatocytes, and the glycolytic pathway involved was determined using D-glucose analogs and metabolites. Together, transient transfections, electrophoretic mobility shift assays and chromatin immunoprecipitation assays show that this regulation occurs at the transcriptional level through an increase of USF1/2 binding to an E-box in the APOA5 promoter. We show that this phenomenon is not due to an increase of mRNA or protein expression levels of USF. Using protein phosphatases 1 and 2A inhibitor, we demonstrate that D-glucose regulates APOA5 gene via a dephosphorylation mechanism, thereby resulting in an enhanced USF1/2-promoter binding. Last, subsequent suppressions of USF1/2 and phosphatases mRNA through siRNA gene silencing abolished the regulation. We demonstrate that APOA5 gene is up regulated by D-glucose and USF through phosphatase activation. These findings may provide a new cross talk between glucose and lipid metabolism.

The chemopreventive properties of chlorogenic acid reveal a potential new role for the microsomal glucose-6-phosphate translocase in brain tumor progression

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Desgagnés Julie

2006-03-01

Full Text Available Abstract Background Chlorogenic acid (CHL, the most potent functional inhibitor of the microsomal glucose-6-phosphate translocase (G6PT, is thought to possess cancer chemopreventive properties. It is not known, however, whether any G6PT functions are involved in tumorigenesis. We investigated the effects of CHL and the potential role of G6PT in regulating the invasive phenotype of brain tumor-derived glioma cells. Results RT-PCR was used to show that, among the adult and pediatric brain tumor-derived cells tested, U-87 glioma cells expressed the highest levels of G6PT mRNA. U-87 cells lacked the microsomal catalytic subunit glucose-6-phosphatase (G6Pase-α but expressed G6Pase-β which, when coupled to G6PT, allows G6P hydrolysis into glucose to occur in non-glyconeogenic tissues such as brain. CHL inhibited U-87 cell migration and matrix metalloproteinase (MMP-2 secretion, two prerequisites for tumor cell invasion. Moreover, CHL also inhibited cell migration induced by sphingosine-1-phosphate (S1P, a potent mitogen for glioblastoma multiform cells, as well as the rapid, S1P-induced extracellular signal-regulated protein kinase phosphorylation potentially mediated through intracellular calcium mobilization, suggesting that G6PT may also perform crucial functions in regulating intracellular signalling. Overexpression of the recombinant G6PT protein induced U-87 glioma cell migration that was, in turn, antagonized by CHL. MMP-2 secretion was also inhibited by the adenosine triphosphate (ATP-depleting agents 2-deoxyglucose and 5-thioglucose, a mechanism that may inhibit ATP-mediated calcium sequestration by G6PT. Conclusion We illustrate a new G6PT function in glioma cells that could regulate the intracellular signalling and invasive phenotype of brain tumor cells, and that can be targeted by the anticancer properties of CHL.

Murine remote preconditioning increases glucose uptake and suppresses gluconeogenesis in hepatocytes via a brain-liver neurocircuit, leading to counteracting glucose intolerance.

Science.gov (United States)

Kurabayashi, Atsushi; Tanaka, Chiharu; Matsumoto, Waka; Naganuma, Seiji; Furihata, Mutsuo; Inoue, Keiji; Kakinuma, Yoshihiko

2018-05-01

Our previous study revealed that cyclic hindlimb ischaemia-reperfusion (IR) activates cardiac acetylcholine (ACh) synthesis through the cholinergic nervous system and cell-derived ACh accelerates glucose uptake. However, the mechanisms regulating glucose metabolism in vivo remain unknown. We investigated the effects and mechanisms of IR in mice under pathophysiological conditions. Using IR-subjected male C57BL/6J mice, the effects of IR on blood sugar (BS), glucose uptake, central parasympathetic nervous system (PNS) activity, hepatic gluconeogenic enzyme expression and those of ACh on hepatocellular glucose uptake were assessed. IR decreased BS levels by 20% and increased c-fos immunoreactivity in the center of the PNS (the solitary tract and the dorsal motor vagal nucleus). IR specifically downregulated hepatic gluconeogenic enzyme expression and activities (glucose-6-phosphatase and phosphoenolpyruvate carboxykinase) and accelerated hepatic glucose uptake. Transection of a hepatic vagus nerve branch decreased this uptake and reversed BS decrease. Suppressed gluconeogenic enzyme expression was reversed by intra-cerebroventricular administration of a choline acetyltransferase inhibitor. Moreover, IR significantly attenuated hyperglycaemia in murine model of type I and II diabetes mellitus. IR provides another insight into a therapeutic modality for diabetes mellitus due to regulating gluconeogenesis and glucose-uptake and advocates an adjunctive mode rectifying disturbed glucose metabolism. Copyright © 2018 Elsevier B.V. All rights reserved.

Assessment of insulin resistance in fructose-fed rats with 125I-6-deoxy-6-iodo-D-glucose, a new tracer of glucose transport

International Nuclear Information System (INIS)

Perret, Pascale; Slimani, Lotfi; Briat, Arnaud; Villemain, Daniele; Fagret, Daniel; Ghezzi, Catherine; Halimi, Serge; Demongeot, Jacques

2007-01-01

Insulin resistance, characterised by an insulin-stimulated glucose transport defect, is an important feature of the pre-diabetic state that has been observed in numerous pathological disorders. The purpose of this study was to assess variations in glucose transport in rats using 125 I-6-deoxy-6-iodo-D-glucose (6DIG), a new tracer of glucose transport proposed as an imaging tool to assess insulin resistance in vivo. Two protocols were performed, a hyperinsulinaemic-euglycaemic clamp and a normoinsulinaemic-normoglycaemic protocol, in awake control and insulin-resistant fructose-fed rats. The tracer was injected at steady state, and activity in 11 tissues and the blood was assessed ex vivo at several time points. A multicompartmental mathematical model was developed to obtain fractional transfer coefficients of 6DIG from the blood to the organs. Insulin sensitivity of fructose-fed rats, estimated by the glucose infusion rate, was reduced by 40% compared with control rats. At steady state, 6DIG uptake was significantly stimulated by insulin in insulin-sensitive tissues of control rats (basal versus insulin: diaphragm, p < 0.01; muscle, p < 0.05; heart, p < 0.001), whereas insulin did not stimulate 6DIG uptake in insulin-resistant fructose-fed rats. Moreover, in these tissues, the fractional transfer coefficients of entrance were significantly increased with insulin in control rats (basal vs insulin: diaphragm, p < 0.001; muscle, p < 0.001; heart, p < 0.01) whereas no significant changes were observed in fructose-fed rats. This study sets the stage for the future use of 6DIG as a non-invasive means for the evaluation of insulin resistance by nuclear imaging. (orig.)

Assessment of insulin resistance in fructose-fed rats with 125I-6-deoxy-6-iodo-D-glucose, a new tracer of glucose transport

Science.gov (United States)

Perret, Pascale; Slimani, Lotfi; Briat, Arnaud; Villemain, Danièle; Halimi, Serge; Demongeot, Jacques; Fagret, Daniel; Ghezzi, Catherine

2007-01-01

Purpose Insulin resistance, characterised by an insulin-stimulated glucose transport defect, is an important feature of the pre-diabetic state and it has been observed in numerous pathological disorders. The purpose of this study was to assess variations in glucose transport in rats with 125I-6-Deoxy-6-Iodo-D-glucose (6DIG), a new tracer of glucose transport proposed as an imaging tool to assess insulin resistance in vivo. Methods Two protocols were performed, a hyperinsulinaemic-euglycaemic clamp and a normoinsulinaemic normoglycaemic protocol, in awake control and insulin-resistant fructose-fed rats. The tracer was injected at steady state, and activity in 11 tissues and the blood were assessed ex vivo at several time points. A multicompartmental mathematical model was developed to obtain fractional transfer coefficients of 6DIG from the blood to the organs. Results Insulin sensitivity of fructose-fed rats, estimated by the glucose infusion rate, was reduced by 40% compared with control rats. At steady-state, 6DIG uptake was significantly stimulated by insulin in insulin-sensitive tissues of control rats (basal versus insulin: diaphragm, p<0.01; muscle, p<0.05; heart, p<0.001), whereas insulin did not stimulate 6DIG uptake in insulin-resistant fructose-fed rats. Moreover, in these tissues, the fractional transfer coefficients of entrance were significantly increased with insulin in control rats (basal vs insulin: diaphragm, p<0.001; muscle, p<0.001; heart, p<0.01) and whereas no significant changes were observed in fructose-fed rats. Conclusion This study sets the stage for the future use of 6DIG as a non-invasive means for the evaluation of insulin resistance by nuclear imaging. PMID:17171359

Direct determination of phosphatase activity from physiological substrates in cells.

Directory of Open Access Journals (Sweden)

Zhongyuan Ren

Full Text Available A direct and continuous approach to determine simultaneously protein and phosphate concentrations in cells and kinetics of phosphate release from physiological substrates by cells without any labeling has been developed. Among the enzymes having a phosphatase activity, tissue non-specific alkaline phosphatase (TNAP performs indispensable, multiple functions in humans. It is expressed in numerous tissues with high levels detected in bones, liver and neurons. It is absolutely required for bone mineralization and also necessary for neurotransmitter synthesis. We provided the proof of concept that infrared spectroscopy is a reliable assay to determine a phosphatase activity in the osteoblasts. For the first time, an overall specific phosphatase activity in cells was determined in a single step by measuring simultaneously protein and substrate concentrations. We found specific activities in osteoblast like cells amounting to 116 ± 13 nmol min(-1 mg(-1 for PPi, to 56 ± 11 nmol min(-1 mg(-1 for AMP, to 79 ± 23 nmol min(-1 mg(-1 for beta-glycerophosphate and to 73 ± 15 nmol min(-1 mg(-1 for 1-alpha-D glucose phosphate. The assay was also effective to monitor phosphatase activity in primary osteoblasts and in matrix vesicles. The use of levamisole--a TNAP inhibitor--served to demonstrate that a part of the phosphatase activity originated from this enzyme. An IC50 value of 1.16 ± 0.03 mM was obtained for the inhibition of phosphatase activity of levamisole in osteoblast like cells. The infrared assay could be extended to determine any type of phosphatase activity in other cells. It may serve as a metabolomic tool to monitor an overall phosphatase activity including acid phosphatases or other related enzymes.

Phytopharmacological evaluation of Byesukar for hypoglycaemic activity and its effect on lipid profile and hepatic enzymes of glucose metabolism in diabetic rats.

Science.gov (United States)

Guruvayoorappan, C; Sudha, G

2008-01-01

Many anti-diabetic herbal preparations have been recommended in alternative systems of medicine for the treatment of diabetes. No systematic study has been done on the anti-diabetic efficacy of Byesukar, a polyherbal formulation to treat diabetes. The anti-diabetic efficacy of byesukar ethanol extract was evaluated in an animal model of diabetes induced by alloxan. Male Wistar rats were divided in to four groups. Group 1 was normal control group; group 2 and 3 received alloxan. After inducing experimental diabetes group 2 served as diabetic control; group 3 received byesukar (500 mg/kg body weight) orally for 30 consecutive days. Group 4 were normal rats which received byesukar extract alone. The effect of byesukar on glucose level in diabetic rats was studied and the level of glucose metabolizing enzymes (Hexokinase, glucose-6-phosphatase and fructose 1, 6-bisphosphatase) in the liver and kidney were estimated. The effect of byesukar on the serum and tissue lipid profile (Cholesterol, triglycerides, phospholipids and free fatty acids) were also estimated in diabetic rats. Our results indicate that treatment with byesukar resulted in significant reduction of blood glucose, tissue glucose-6-phosphatase and fructose 1, 6- bisphosphatase activity. The decreased tissue hexokinase activity in diabetes state was found to be significantly increased by byesukar treatment. Also the byesukar treated diabetic rats showed a significant decrease in the tissue lipid profile compared to the diabetic rats. In conclusion the decreased blood glucose accompanied with decreased lipid profile and changes in the activities of the glucose metabolizing enzymes shows the antidiabetic effect of byesukar.

Central regulation of metabolism by protein tyrosine phosphatases

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Ryan eTsou

2013-01-01

Full Text Available Protein tyrosine phosphatases (PTPs are important regulators of intracellular signaling pathways via the dephosphorylation of phosphotyrosyl residues on various receptor and non-receptor substrates. The phosphorylation state of central nervous system (CNS signaling components underlies the molecular mechanisms of a variety of physiological functions including the control of energy balance and glucose homeostasis. In this review, we summarize the current evidence implicating PTPs as central regulators of metabolism, specifically highlighting their interactions with the neuronal leptin and insulin signaling pathways. We discuss the role of a number of PTPs (PTP1B, SHP2, TCPTP, RPTPe, and PTEN, reviewing the findings from genetic mouse models and in vitro studies which highlight these phosphatases as key central regulators of energy homeostasis.

Purification and characterization of a polyisoprenyl phosphate phosphatase from pig brain. Possible dual specificity.

Science.gov (United States)

Frank, D W; Waechter, C J

1998-05-08

Microsomal fractions from pig and calf brain catalyze the enzymatic dephosphorylation of endogenous and exogenous dolichyl monophosphate (Dol-P) (Sumbilla, C. A., and Waechter, C. J. (1985) Methods Enzymol. 111, 471-482). The Dol-P phosphatase (EC 3.1.3.51) has been solubilized by extracting pig brain microsomes with the nonionic detergent Nonidet P-40 and purified approximately 1,107-fold by a combination of anion exchange chromatography, polyethylene glycol fractionation, dye-ligand chromatography, and wheat germ agglutinin affinity chromatography. Treatment of the enzyme with neuraminidase prevented binding to wheat germ agglutinin-Sepharose, indicating the presence of one or more N-acetylneuraminyl residues per molecule of enzyme. When the highly purified polyisoprenyl phosphate phosphatase was analyzed by SDS-polyacrylamide gel electrophoresis, a major 33-kDa polypeptide was observed. Enzymatic dephosphorylation of Dol-P by the purified phosphatase was 1) optimal at pH 7; 2) potently inhibited by F-, orthovanadate, and Zn2+ > Co2+ > Mn2+ but unaffected by Mg2+; 3) exhibited an approximate Km for C95-Dol-P of 45 microM; and 4) was sensitive to N-ethylmaleimide, phenylglyoxal, and diethylpyrocarbonate. The pig brain phosphatase did not dephosphorylate glucose 6-phosphate, mannose 6-phosphate, 5'-AMP, or p-nitrophenylphosphate, but it dephosphorylated dioleoyl-phosphatidic acid at initial rates similar to those determined for Dol-P. Based on the virtually identical sensitivity of Dol-P and phosphatidic acid dephosphorylation by the highly purified enzyme to N-ethylmaleimide, F-, phenylglyoxal, and diethylpyrocarbonate, both substrates appear to be hydrolyzed by a single enzyme with an apparent dual specificity. This is the first report of the purification of a neutral Dol-P phosphatase from mammalian tissues. Although the enzyme is Mg2+-independent and capable of dephosphorylating Dol-P and PA, several enzymological properties distinguish this lipid

The Effect of Phloroglucinol, A Component of Ecklonia cava Extract, on Hepatic Glucose Production

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Ji-Young Yoon

2017-04-01

Full Text Available Phloroglucinol is a phenolic compound that is one of the major compounds in Ecklonia cava (brown alga. It has many pharmacological activities, but its anti-diabetic effect is not yet fully explored. In this study, we investigated the effect of phloroglucinol on the control of blood glucose levels and the regulation of hepatic glucose production. Phloroglucinol significantly improved glucose tolerance in male C57BL/6J mice fed a high fat diet (HFD and inhibited glucose production in mouse primary hepatocytes. The expression of phosphoenol pyruvate carboxykinase (PEPCK and glucose-6-phosphatase mRNA and protein (G6Pase, enzymes involved in gluconeogenesis, were inhibited in liver tissue from phloroglucinol-treated mice and in phloroglucinol-treated HepG2 cells. In addition, phloroglucinol treatment increased phosphorylated AMP-activated protein kinase (AMPKα in HepG2 cells. Treatment with compound C, an AMPKα inhibitor, inhibited the increase of phosphorylated AMPKα and the decrease of PEPCK and G6Pase expression caused by phloroglucinol treatment. We conclude that phloroglucinol may inhibit hepatic gluconeogenesis via modulating the AMPKα signaling pathway, and thus lower blood glucose levels.

Screening of Glucose-6-Phosphate Dehydrogenase Deficiency in Cord Blood

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Can Acipayam

2014-02-01

Aim: Glucose-6-phosphate dehydrogenase deficiency is an important factor in etiology of pathologic neonatal jaundice. The aim of this study was to indicate the significance of screening glucose-6-phosphate dehydrogenase deficiency in the cord blood of neonates and the frequency of this deficiency in the etiology of neonatal hyperbilirubinemia. Material and Method: The study was performed consecutive 1015 neonates were included. Five hundred fifty six (54.8% of them were male and 459 (45.2% were female. The following parameters were recorded: Gender, birth weight, birth height, head circumference and gestational age. The glucose-6-phosphate dehydrogenase level of neonates were measured with quantitative method in cord blood. Also, hemoglobine, hematocrite, red blood cell count and blood group were measured. The following parameters were recorded in cases with jaundice: exchange transfusion, phototherapy, physiologic and pathologic jaundice, peak bilirubin day, maximum bilirubin level, total bilirubin level at the first day of jaundice, beginning time of jaundice. Results: Enzyme deficiency was detected in 133 (13.1% of neonates and 76 (57% of them were male, 57 (43% were female. Significant difference was detected in low glucose-6-phosphate dehydrogenase enzyme level with jaundice group for total bilirubin level at the first day of jaundice, maximum total bilirubin level and pathologic jaundice (p<0.05. Discussion: The ratio of glucose-6-phosphate dehydrogenase deficiency was found in Edirne in this study and this ratio was higher than other studies conducted in our country. For this reason, glucose-6-phosphate dehydrogenase enzyme level in cord blood of neonates should be measured routinely and high risk neonates should be followed up for hyperbilirubinemia and parents should be informed in our region.

Assessment of insulin resistance in fructose-fed rats with {sup 125}I-6-deoxy-6-iodo-D-glucose, a new tracer of glucose transport

Energy Technology Data Exchange (ETDEWEB)

Perret, Pascale; Slimani, Lotfi; Briat, Arnaud; Villemain, Daniele; Fagret, Daniel; Ghezzi, Catherine [INSERM, E340, 38000 Grenoble, (France); Univ Grenoble, 38000 Grenoble, (France); Halimi, Serge [CHRU Grenoble, Hopital Michallon, Service de Diabetologie, 38000 Grenoble, (France); Demongeot, Jacques [Univ Grenoble, 38000 Grenoble, (France); CNRS, UMR 5525, 38000 Grenoble, (France)

2007-05-15

Insulin resistance, characterised by an insulin-stimulated glucose transport defect, is an important feature of the pre-diabetic state that has been observed in numerous pathological disorders. The purpose of this study was to assess variations in glucose transport in rats using {sup 125}I-6-deoxy-6-iodo-D-glucose (6DIG), a new tracer of glucose transport proposed as an imaging tool to assess insulin resistance in vivo. Two protocols were performed, a hyperinsulinaemic-euglycaemic clamp and a normoinsulinaemic-normoglycaemic protocol, in awake control and insulin-resistant fructose-fed rats. The tracer was injected at steady state, and activity in 11 tissues and the blood was assessed ex vivo at several time points. A multicompartmental mathematical model was developed to obtain fractional transfer coefficients of 6DIG from the blood to the organs. Insulin sensitivity of fructose-fed rats, estimated by the glucose infusion rate, was reduced by 40% compared with control rats. At steady state, 6DIG uptake was significantly stimulated by insulin in insulin-sensitive tissues of control rats (basal versus insulin: diaphragm, p < 0.01; muscle, p < 0.05; heart, p < 0.001), whereas insulin did not stimulate 6DIG uptake in insulin-resistant fructose-fed rats. Moreover, in these tissues, the fractional transfer coefficients of entrance were significantly increased with insulin in control rats (basal vs insulin: diaphragm, p < 0.001; muscle, p < 0.001; heart, p < 0.01) whereas no significant changes were observed in fructose-fed rats. This study sets the stage for the future use of 6DIG as a non-invasive means for the evaluation of insulin resistance by nuclear imaging. (orig.)

Interleukin 6 stimulates hepatic glucose release from prelabeled glycogen pools

International Nuclear Information System (INIS)

Ritchie, D.G.

1990-01-01

Cytokines, derived from a wide variety of cell types, are now believed to initiate many of the physiological responses accompanying the inflammatory phase that follows either Gram-negative septicemia or thermal injury. Because hypoglycemia (after endotoxic challenge) and hyperglycemia (after thermal injury) represent well-characterized responses to these injuries, we sought to determine whether hepatic glycogen metabolism could be altered by specific cytokines. Cultured adult rat hepatocytes were prelabeled with [ 14 C]glucose for 24 h, a procedure that resulted in the labeling of hepatic glycogen pools that subsequently could be depleted (with concomitant [ 14 C]glucose release) by either glucagon or norepinephrine. After the addition of a highly concentrated human monocyte-conditioned medium (MCM) or various cytokines to these prelabeled cells, [ 14 C]glucose release was stimulated by MCM and recombinant human interleukin 6 (IL-6) but was not stimulated by other cytokines tested. Furthermore, only antisera to IL-6 were capable of reducing the glucose-releasing factor activity found in MCM. These data therefore suggest a novel glucoregulatory role for IL-6

Inhibition of the gut enzyme intestinal alkaline phosphatase may explain how aspartame promotes glucose intolerance and obesity in mice.

Science.gov (United States)

Gul, Sarah S; Hamilton, A Rebecca L; Munoz, Alexander R; Phupitakphol, Tanit; Liu, Wei; Hyoju, Sanjiv K; Economopoulos, Konstantinos P; Morrison, Sara; Hu, Dong; Zhang, Weifeng; Gharedaghi, Mohammad Hadi; Huo, Haizhong; Hamarneh, Sulaiman R; Hodin, Richard A

2017-01-01

Diet soda consumption has not been associated with tangible weight loss. Aspartame (ASP) commonly substitutes sugar and one of its breakdown products is phenylalanine (PHE), a known inhibitor of intestinal alkaline phosphatase (IAP), a gut enzyme shown to prevent metabolic syndrome in mice. We hypothesized that ASP consumption might contribute to the development of metabolic syndrome based on PHE's inhibition of endogenous IAP. The design of the study was such that for the in vitro model, IAP was added to diet and regular soda, and IAP activity was measured. For the acute model, a closed bowel loop was created in mice. ASP or water was instilled into it and IAP activity was measured. For the chronic model, mice were fed chow or high-fat diet (HFD) with/without ASP in the drinking water for 18 weeks. The results were that for the in vitro study, IAP activity was lower (p < 0.05) in solutions containing ASP compared with controls. For the acute model, endogenous IAP activity was reduced by 50% in the ASP group compared with controls (0.2 ± 0.03 vs 0.4 ± 0.24) (p = 0.02). For the chronic model, mice in the HFD + ASP group gained more weight compared with the HFD + water group (48.1 ± 1.6 vs 42.4 ± 3.1, p = 0.0001). Significant difference in glucose intolerance between the HFD ± ASP groups (53 913 ± 4000.58 (mg·min)/dL vs 42 003.75 ± 5331.61 (mg·min)/dL, respectively, p = 0.02). Fasting glucose and serum tumor necrosis factor-alpha levels were significantly higher in the HFD + ASP group (1.23- and 0.87-fold increases, respectively, p = 0.006 and p = 0.01). In conclusion, endogenous IAP's protective effects in regard to the metabolic syndrome may be inhibited by PHE, a metabolite of ASP, perhaps explaining the lack of expected weight loss and metabolic improvements associated with diet drinks.

CREBH Maintains Circadian Glucose Homeostasis by Regulating Hepatic Glycogenolysis and Gluconeogenesis.

Science.gov (United States)

Kim, Hyunbae; Zheng, Ze; Walker, Paul D; Kapatos, Gregory; Zhang, Kezhong

2017-07-15

Cyclic AMP-responsive element binding protein, hepatocyte specific (CREBH), is a liver-enriched, endoplasmic reticulum-tethered transcription factor known to regulate the hepatic acute-phase response and lipid homeostasis. In this study, we demonstrate that CREBH functions as a circadian transcriptional regulator that plays major roles in maintaining glucose homeostasis. The proteolytic cleavage and posttranslational acetylation modification of CREBH are regulated by the circadian clock. Functionally, CREBH is required in order to maintain circadian homeostasis of hepatic glycogen storage and blood glucose levels. CREBH regulates the rhythmic expression of the genes encoding the rate-limiting enzymes for glycogenolysis and gluconeogenesis, including liver glycogen phosphorylase (PYGL), phosphoenolpyruvate carboxykinase 1 (PCK1), and the glucose-6-phosphatase catalytic subunit (G6PC). CREBH interacts with peroxisome proliferator-activated receptor α (PPARα) to synergize its transcriptional activities in hepatic gluconeogenesis. The acetylation of CREBH at lysine residue 294 controls CREBH-PPARα interaction and synergy in regulating hepatic glucose metabolism in mice. CREBH deficiency leads to reduced blood glucose levels but increases hepatic glycogen levels during the daytime or upon fasting. In summary, our studies revealed that CREBH functions as a key metabolic regulator that controls glucose homeostasis across the circadian cycle or under metabolic stress. Copyright © 2017 American Society for Microbiology.

Glucose-6-phosphate reduces calcium accumulation in rat brain endoplasmic reticulum

Directory of Open Access Journals (Sweden)

Jeffrey Thomas Cole

2012-04-01

Full Text Available Brain cells expend large amounts of energy sequestering calcium (Ca2+, while loss of Ca2+ compartmentalization leads to cell damage or death. Upon cell entry, glucose is converted to glucose-6-phosphate (G6P, a parent substrate to several metabolic major pathways, including glycolysis. In several tissues, G6P alters the ability of the endoplasmic reticulum to sequester Ca2+. This led to the hypothesis that G6P regulates Ca2+ accumulation by acting as an endogenous ligand for sarco-endoplasmic reticulum calcium ATPase (SERCA. Whole brain ER microsomes were pooled from adult male Sprague-Dawley rats. Using radio-isotopic assays, 45Ca2+ accumulation was quantified following incubation with increasing amounts of G6P, in the presence or absence of thapsigargin, a potent SERCA inhibitor. To qualitatively assess SERCA activity, the simultaneous release of inorganic phosphate (Pi coupled with Ca2+ accumulation was quantified. Addition of G6P significantly and decreased Ca2+ accumulation in a dose-dependent fashion (1-10 mM. The reduction in Ca2+ accumulation was not significantly different that seen with addition of thapsigargin. Addition of glucose-1-phosphate or fructose-6-phosphate, or other glucose metabolic pathway intermediates, had no effect on Ca2+ accumulation. Further, the release of Pi was markedly decreased, indicating G6P-mediated SERCA inhibition as the responsible mechanism for reduced Ca2+ uptake. Simultaneous addition of thapsigargin and G6P did decrease inorganic phosphate in comparison to either treatment alone, which suggests that the two treatments have different mechanisms of action. Therefore, G6P may be a novel, endogenous regulator of SERCA activity. Additionally, pathological conditions observed during disease states that disrupt glucose homeostasis, may be attributable to Ca2+ dystasis caused by altered G6P regulation of SERCA activity

Identification of glucose 6 phosphate dehydrogenase mutations by ...

African Journals Online (AJOL)

Identification of glucose 6 phosphate dehydrogenase mutations by single strand conformation polymorphism and gene sequencing analysis. ... Subject: Six DNA samples from Turkish males confirmed to have G-6-PD deficiency where available for the study. Results: One subject was found to have an abnormal mobility shift ...

[The limitation of glucose catabolism as a factor in protection during hypoxia].

Science.gov (United States)

Burbello, A T; Vishvtseva, V V; Denisenko, P P; Safonova, A F; Dobrokhotova, E G

1995-01-01

Violuric acid was first shown to have antihypoxic and antioxidative properties, to exert protective action in sodium nitrite-induced hemic hypoxia. Hepatic glucose and glucogen levels increased, the activity of glucose-6- phosphodihydrogenase enhanced, while that of lactate dehydrogenase and alkaline phosphatase decreased, the content of cAMP restored, whereas cGMP and 2,3-diphosphoglycerate levels decreased to a greater extent. The action of violuric acid was especially evident at the ultrastructural level-the ultrastructure of brush receptor elements in anoxia in the presence of violuric acid's action retained all the features characteristic for intact animals, which was accompanied by a significant accumulation of glycogen in the neuroplasm.

Adaptation of HepG2 cells to a steady-state reduction in the content of protein phosphatase 6 (PP6) catalytic subunit

Energy Technology Data Exchange (ETDEWEB)

Boylan, Joan M. [Department of Pediatrics, Brown University and Rhode Island Hospital, Providence, RI (United States); Salomon, Arthur R. [Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, RI (United States); Department of Chemistry, Brown University, Providence, RI (United States); Tantravahi, Umadevi [Division of Genetics, Department of Pathology, Brown University and Women and Infants Hospital, Providence, RI (United States); Gruppuso, Philip A., E-mail: philip_gruppuso@brown.edu [Department of Pediatrics, Brown University and Rhode Island Hospital, Providence, RI (United States); Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, RI (United States)

2015-07-15

Protein phosphatase 6 (PP6) is a ubiquitous Ser/Thr phosphatase involved in an array of cellular processes. To assess the potential of PP6 as a therapeutic target in liver disorders, we attenuated expression of the PP6 catalytic subunit in HepG2 cells using lentiviral-transduced shRNA. Two PP6 knock-down (PP6KD) cell lines (90% reduction of PP6-C protein content) were studied in depth. Both proliferated at a rate similar to control cells. However, flow cytometry indicated G2/M cell cycle arrest that was accounted for by a shift of the cells from a diploid to tetraploid state. PP6KD cells did not show an increase in apoptosis, nor did they exhibit reduced viability in the presence of bleomycin or taxol. Gene expression analysis by microarray showed attenuated anti-inflammatory signaling. Genes associated with DNA replication were downregulated. Mass spectrometry-based phosphoproteomic analysis yielded 80 phosphopeptides representing 56 proteins that were significantly affected by a stable reduction in PP6-C. Proteins involved in DNA replication, DNA damage repair and pre-mRNA splicing were overrepresented among these. PP6KD cells showed intact mTOR signaling. Our studies demonstrated involvement of PP6 in a diverse set of biological pathways and an adaptive response that may limit the effectiveness of targeting PP6 in liver disorders. - Highlights: • Lentiviral-transduced shRNA was used to generate a stable knockdown of PP6 in HepG2 cells. • Cells adapted to reduced PP6; cell proliferation was unaffected, and cell survival was normal. • However, PP6 knockdown was associated with a transition to a tetraploid state. • Genomic profiling showed downregulated anti-inflammatory signaling and DNA replication. • Phosphoproteomic profiling showed changes in proteins associated with DNA replication and repair.

Adaptation of HepG2 cells to a steady-state reduction in the content of protein phosphatase 6 (PP6) catalytic subunit

International Nuclear Information System (INIS)

Boylan, Joan M.; Salomon, Arthur R.; Tantravahi, Umadevi; Gruppuso, Philip A.

2015-01-01

Protein phosphatase 6 (PP6) is a ubiquitous Ser/Thr phosphatase involved in an array of cellular processes. To assess the potential of PP6 as a therapeutic target in liver disorders, we attenuated expression of the PP6 catalytic subunit in HepG2 cells using lentiviral-transduced shRNA. Two PP6 knock-down (PP6KD) cell lines (90% reduction of PP6-C protein content) were studied in depth. Both proliferated at a rate similar to control cells. However, flow cytometry indicated G2/M cell cycle arrest that was accounted for by a shift of the cells from a diploid to tetraploid state. PP6KD cells did not show an increase in apoptosis, nor did they exhibit reduced viability in the presence of bleomycin or taxol. Gene expression analysis by microarray showed attenuated anti-inflammatory signaling. Genes associated with DNA replication were downregulated. Mass spectrometry-based phosphoproteomic analysis yielded 80 phosphopeptides representing 56 proteins that were significantly affected by a stable reduction in PP6-C. Proteins involved in DNA replication, DNA damage repair and pre-mRNA splicing were overrepresented among these. PP6KD cells showed intact mTOR signaling. Our studies demonstrated involvement of PP6 in a diverse set of biological pathways and an adaptive response that may limit the effectiveness of targeting PP6 in liver disorders. - Highlights: • Lentiviral-transduced shRNA was used to generate a stable knockdown of PP6 in HepG2 cells. • Cells adapted to reduced PP6; cell proliferation was unaffected, and cell survival was normal. • However, PP6 knockdown was associated with a transition to a tetraploid state. • Genomic profiling showed downregulated anti-inflammatory signaling and DNA replication. • Phosphoproteomic profiling showed changes in proteins associated with DNA replication and repair

Correlation between high blood IL-6 level, hyperglycemia, and glucose control in septic patients.

Science.gov (United States)

Nakamura, Masataka; Oda, Shigeto; Sadahiro, Tomohito; Watanabe, Eizo; Abe, Ryuzo; Nakada, Taka-Aki; Morita, Yasumasa; Hirasawa, Hiroyuki

2012-12-12

The aim of the present study was to investigate the relationship between the blood IL-6 level, the blood glucose level, and glucose control in septic patients. This retrospective observational study in a general ICU of a university hospital included a total of 153 patients with sepsis, severe sepsis, or septic shock who were admitted to the ICU between 2005 and 2010, stayed in the ICU for 7 days or longer, and did not receive steroid therapy prior to or after ICU admission. The severity of stress hyperglycemia, status of glucose control, and correlation between those two factors in these patients were investigated using the blood IL-6 level as an index of hypercytokinemia. A significant positive correlation between blood IL-6 level and blood glucose level on ICU admission was observed in the overall study population (n = 153; r = 0.24, P = 0.01), and was stronger in the nondiabetic subgroup (n = 112; r = 0.42, P glucose control (blood glucose level blood IL-6 level on ICU admission (P blood IL-6 level after ICU admission remained significantly higher and the 60-day survival rate was significantly lower in the failed glucose control group than in the successful glucose control group (P blood IL-6 level was correlated with hyperglycemia and with difficulties in glucose control in septic patients. These results suggest the possibility that hypercytokinemia might be involved in the development of hyperglycemia in sepsis, and thereby might affect the success of glucose control.

Glucose-6-phosphate dehydrogenase deficiency; the single most ...

African Journals Online (AJOL)

Introduction: Glucose- 6-phosphate dehydrogenase deficiency is the most common enzymatic disorder of the red cell and an important risk factor for neonatal jaundice. Methodology: The aim of the study was to determine the incidence of G-6-PD deficiency among jaundiced neonates, and describe the associated morbidity ...

Glucose-6-Phosphatase Catalytic Subunit 3 (G6PC3 Deficiency Associated With Autoinflammatory Complications

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Anoop Mistry

2017-11-01

Full Text Available G6PC3 deficiency typically causes severe congenital neutropenia, associated with susceptibility to infections, cardiac and urogenital abnormalities. However, here we describe two boys of Pakistani origin who were found to have G6PC3 deficiency due to c.130 C>T mutation, but who have clinical phenotypes that are typical for a systemic autoinflammatory syndrome. The index case presented with combination of unexplained fevers, severe mucosal ulcers, abdominal symptoms, and inflammatory arthritis. He eventually fully responded to anti-TNF therapy. In this study, we show that compared with healthy controls, neutrophils and monocytes from patients have reduced glycolytic reserve. Considering that healthy myeloid cells have been shown to switch their metabolic pathways to glycolysis in response to inflammatory cues, we studied what impact this might have on production of the inflammatory cytokines. We have demonstrated that patients’ monocytes, in response to lipopolysaccharide, show significantly increased production of IL-1β and IL-18, which is NLRP3 inflammasome dependent. Furthermore, additional whole blood assays have also shown an enhanced production of IL-6 and TNF from the patients’ cells. These cases provide further proof that autoinflammatory complications are also seen within the spectrum of primary immune deficiencies, and resulting from a wider dysregulation of the immune responses.

Glucose-6-Phosphatase Catalytic Subunit 3 (G6PC3) Deficiency Associated With Autoinflammatory Complications.

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Mistry, Anoop; Scambler, Thomas; Parry, David; Wood, Mark; Barcenas-Morales, Gabriela; Carter, Clive; Doffinger, Rainer; Savic, Sinisa

2017-01-01

G6PC3 deficiency typically causes severe congenital neutropenia, associated with susceptibility to infections, cardiac and urogenital abnormalities. However, here we describe two boys of Pakistani origin who were found to have G6PC3 deficiency due to c.130 C>T mutation, but who have clinical phenotypes that are typical for a systemic autoinflammatory syndrome. The index case presented with combination of unexplained fevers, severe mucosal ulcers, abdominal symptoms, and inflammatory arthritis. He eventually fully responded to anti-TNF therapy. In this study, we show that compared with healthy controls, neutrophils and monocytes from patients have reduced glycolytic reserve. Considering that healthy myeloid cells have been shown to switch their metabolic pathways to glycolysis in response to inflammatory cues, we studied what impact this might have on production of the inflammatory cytokines. We have demonstrated that patients' monocytes, in response to lipopolysaccharide, show significantly increased production of IL-1β and IL-18, which is NLRP3 inflammasome dependent. Furthermore, additional whole blood assays have also shown an enhanced production of IL-6 and TNF from the patients' cells. These cases provide further proof that autoinflammatory complications are also seen within the spectrum of primary immune deficiencies, and resulting from a wider dysregulation of the immune responses.

Forkhead Box O6 (FoxO6) Depletion Attenuates Hepatic Gluconeogenesis and Protects against Fat-induced Glucose Disorder in Mice*

Science.gov (United States)

Calabuig-Navarro, Virtu; Yamauchi, Jun; Lee, Sojin; Zhang, Ting; Liu, Yun-Zi; Sadlek, Kelsey; Coudriet, Gina M.; Piganelli, Jon D.; Jiang, Chun-Lei; Miller, Rita; Lowe, Mark; Harashima, Hideyoshi; Dong, H. Henry

2015-01-01

Excessive endogenous glucose production contributes to fasting hyperglycemia in diabetes. FoxO6 is a distinct member of the FoxO subfamily. To elucidate the role of FoxO6 in hepatic gluconeogenesis and assess its contribution to the pathogenesis of fasting hyperglycemia in diabetes, we generated FoxO6 knock-out (FoxO6-KO) mice followed by determining the effect of FoxO6 loss-of-function on hepatic gluconeogenesis under physiological and pathological conditions. FoxO6 depletion attenuated hepatic gluconeogenesis and lowered fasting glycemia in FoxO6-KO mice. FoxO6-deficient primary hepatocytes were associated with reduced capacities to produce glucose in response to glucagon. When fed a high fat diet, FoxO6-KO mice exhibited significantly enhanced glucose tolerance and reduced blood glucose levels accompanied by improved insulin sensitivity. These effects correlated with attenuated hepatic gluconeogenesis in FoxO6-KO mice. In contrast, wild-type littermates developed fat-induced glucose intolerance with a concomitant induction of fasting hyperinsulinemia and hyperglycemia. Furthermore, FoxO6-KO mice displayed significantly diminished macrophage infiltration into liver and adipose tissues, correlating with the reduction of macrophage expression of C-C chemokine receptor 2 (CCR2), a factor that is critical for regulating macrophage recruitment in peripheral tissues. Our data indicate that FoxO6 depletion protected against diet-induced glucose intolerance and insulin resistance by attenuating hepatic gluconeogenesis and curbing macrophage infiltration in liver and adipose tissues in mice. PMID:25944898

High passage MIN6 cells have impaired insulin secretion with impaired glucose and lipid oxidation.

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Kim Cheng

Full Text Available Type 2 diabetes is a metabolic disorder characterized by the inability of beta-cells to secrete enough insulin to maintain glucose homeostasis. MIN6 cells secrete insulin in response to glucose and other secretagogues, but high passage (HP MIN6 cells lose their ability to secrete insulin in response to glucose. We hypothesized that metabolism of glucose and lipids were defective in HP MIN6 cells causing impaired glucose stimulated insulin secretion (GSIS. HP MIN6 cells had no first phase and impaired second phase GSIS indicative of global functional impairment. This was coupled with a markedly reduced ATP content at basal and glucose stimulated states. Glucose uptake and oxidation were higher at basal glucose but ATP content failed to increase with glucose. HP MIN6 cells had decreased basal lipid oxidation. This was accompanied by reduced expressions of Glut1, Gck, Pfk, Srebp1c, Ucp2, Sirt3, Nampt. MIN6 cells represent an important model of beta cells which, as passage numbers increased lost first phase but retained partial second phase GSIS, similar to patients early in type 2 diabetes onset. We believe a number of gene expression changes occurred to produce this defect, with emphasis on Sirt3 and Nampt, two genes that have been implicated in maintenance of glucose homeostasis.

Forkhead Box O6 (FoxO6) Depletion Attenuates Hepatic Gluconeogenesis and Protects against Fat-induced Glucose Disorder in Mice.

Science.gov (United States)

Calabuig-Navarro, Virtu; Yamauchi, Jun; Lee, Sojin; Zhang, Ting; Liu, Yun-Zi; Sadlek, Kelsey; Coudriet, Gina M; Piganelli, Jon D; Jiang, Chun-Lei; Miller, Rita; Lowe, Mark; Harashima, Hideyoshi; Dong, H Henry

2015-06-19

Excessive endogenous glucose production contributes to fasting hyperglycemia in diabetes. FoxO6 is a distinct member of the FoxO subfamily. To elucidate the role of FoxO6 in hepatic gluconeogenesis and assess its contribution to the pathogenesis of fasting hyperglycemia in diabetes, we generated FoxO6 knock-out (FoxO6-KO) mice followed by determining the effect of FoxO6 loss-of-function on hepatic gluconeogenesis under physiological and pathological conditions. FoxO6 depletion attenuated hepatic gluconeogenesis and lowered fasting glycemia in FoxO6-KO mice. FoxO6-deficient primary hepatocytes were associated with reduced capacities to produce glucose in response to glucagon. When fed a high fat diet, FoxO6-KO mice exhibited significantly enhanced glucose tolerance and reduced blood glucose levels accompanied by improved insulin sensitivity. These effects correlated with attenuated hepatic gluconeogenesis in FoxO6-KO mice. In contrast, wild-type littermates developed fat-induced glucose intolerance with a concomitant induction of fasting hyperinsulinemia and hyperglycemia. Furthermore, FoxO6-KO mice displayed significantly diminished macrophage infiltration into liver and adipose tissues, correlating with the reduction of macrophage expression of C-C chemokine receptor 2 (CCR2), a factor that is critical for regulating macrophage recruitment in peripheral tissues. Our data indicate that FoxO6 depletion protected against diet-induced glucose intolerance and insulin resistance by attenuating hepatic gluconeogenesis and curbing macrophage infiltration in liver and adipose tissues in mice. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

Neonatal jaundice and glucose-6-phosphate dehydrogenase

OpenAIRE

Leite, Amauri Antiquera [UNESP

2010-01-01

A deficiência de glicose-6-fosfato desidrogenase em neonatos pode ser a responsável pela icterícia neonatal. Este comentário científico é decorrente do relato sobre o tema publicado neste fascículo e que preocupa diversos autores de outros países em relação às complicações em neonatos de hiperbilirrubinemia, existindo inclusive proposições de alguns autores em incluir o teste para identificar a deficiência de glicose-6-fosfato desidrogenase nos recém-nascidos.Glucose-6-phosphate dehydrogenase...

Analysis of metabolism of 6FDG: a PET glucose transport tracer

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Muzic, Raymond F., E-mail: raymond.muzic@case.edu [Department of Radiology, Case Western Reserve University, Cleveland, OH 44106 (United States); Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106 (United States); Chandramouli, Visvanathan [Department of Radiology, Case Western Reserve University, Cleveland, OH 44106 (United States); Huang, Hsuan-Ming [Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106 (United States); Wu Chunying; Wang Yanming [Department of Radiology, Case Western Reserve University, Cleveland, OH 44106 (United States); Ismail-Beigi, Faramarz [Department of Medicine, Case Western Reserve University, Cleveland, OH 44106 (United States)

2011-07-15

Introduction: We are developing {sup 18}F-labeled 6-fluoro-6-deoxy-D-glucose ([{sup 18}F]6FDG) as a tracer of glucose transport. As part of this process it is important to characterize and quantify putative metabolites. In contrast to the ubiquitous positron emission tomography (PET) tracer {sup 18}F-labeled 2-fluoro-2-deoxy-D-glucose ([{sup 18}F]2FDG) which is phosphorylated and trapped intracellularly, the substitution of fluorine for a hydroxyl group at carbon-6 in [{sup 18}F]6FDG should prevent its phosphorylation. Consequently, [{sup 18}F]6FDG has the potential to trace the transport step of glucose metabolism without the confounding effects of phosphorylation and subsequent steps of metabolism. Herein the focus is to determine whether, and the degree to which, [{sup 18}F]6FDG remains unchanged following intravenous injection. Methods: Biodistribution studies were performed using 6FDG labeled with {sup 18}F or with the longer-lived radionuclides {sup 3}H and {sup 14}C. Tissues were harvested at 1, 6, and 24 h following intravenous administration and radioactivity was extracted from the tissues and analyzed using a combination of ion exchange columns, high-performance liquid chromatography, and chemical reactivity. Results: At the 1 h time-point, the vast majority of radioactivity in the liver, brain, heart, skeletal muscle, and blood was identified as 6FDG. At the 6-h and 24-h time points, there was evidence of a minor amount of radioactive material that appeared to be 6-fluoro-6-deoxy-D-sorbitol and possibly 6-fluoro-6-deoxy-D-gluconic acid. Conclusion: On the time scale typical of PET imaging studies radioactive metabolites of [{sup 18}F]6FDG are negligible.

6-Paradol and 6-Shogaol, the Pungent Compounds of Ginger, Promote Glucose Utilization in Adipocytes and Myotubes, and 6-Paradol Reduces Blood Glucose in High-Fat Diet-Fed Mice

Directory of Open Access Journals (Sweden)

Chien-Kei Wei

2017-01-01

Full Text Available The anti-diabetic activity of ginger powder (Zingiber officinale has been recently promoted, with the recommendation to be included as one of the dietary supplements for diabetic patients. However, previous studies presented different results, which may be caused by degradation and metabolic changes of ginger components, gingerols, shogaols and paradols. Therefore, we prepared 10 ginger active components, namely 6-, 8-, 10-paradols, 6-, 8-, 10-shogaols, 6-, 8-, 10-gingerols and zingerone, and evaluated their anti-hyperglycemic activity. Among the tested compounds, 6-paradol and 6-shogaol showed potent activity in stimulating glucose utilization by 3T3-L1 adipocytes and C2C12 myotubes. The effects were attributed to the increase in 5′ adenosine monophosphate-activated protein kinase (AMPK phosphorylation in 3T3-L1 adipocytes. 6-Paradol, the major metabolite of 6-shogaol, was utilized in an in vivo assay and significantly reduced blood glucose, cholesterol and body weight in high-fat diet-fed mice.

Effects of hyperglycemia on glucose production and utilization in humans. Measurement with [3H]-2-, [3H]-3-, and [14C]-6-glucose

International Nuclear Information System (INIS)

Bell, P.M.; Firth, R.G.; Rizza, R.A.

1986-01-01

Studies with tritiated isotopes of glucose have demonstrated that hyperglycemia per se stimulates glucose utilization and suppresses glucose production in humans. These conclusions rely on the assumption that tritiated glucose provides an accurate measure of glucose turnover. However, if in the presence of hyperglycemia the isotope either loses its label during futile cycling or retains its label during cycling through glycogen, then this assumption is not valid. To examine this question, glucose utilization and glucose production rates were measured in nine normal subjects with a simultaneous infusion of [ 3 H]-2-glucose, an isotope that may undergo futile cycling but does not cycle through glycogen; [ 14 C]-6-glucose, an isotope that may cycle through glycogen but does not futile cycle; and [ 3 H]-3-glucose, an isotope that can both undergo futile cycling and cycle through glycogen. In the postabsorptive state at plasma glucose concentration of 95 mg X dl-1, glucose turnover determined with [ 14 C]-6-glucose (2.3 +/- 0.1 mg X kg-1 X min-1) was greater than that determined with [3 3 H]glucose (2.1 +/- 0.1 mg X kg-1 X min-1, P = 0.002) and slightly less than that determined with [ 3 H]-2-glucose (2.7 +/- 0.2 mg X kg-1 X min-1, P = 0.08). Plasma glucose was then raised from 95 to 135 to 175 mg X dl-1 while insulin secretion was inhibited, and circulating insulin, glucagon, and growth hormone concentrations were maintained constant by infusion of these hormones and somatostatin. Glucose production and utilization rates determined with [ 14 C]-6-glucose continued to be less than those determined with [ 3 H]-2-glucose and greater than those seen with [ 3 H]-3-glucose

Prevalence of Sickle Cell Trait and Glucose 6 Phosphate ...

African Journals Online (AJOL)

Blood donation from sickle cell trait (SCT) and glucose-6-phosphate dehydrogenase (G6PD)-deficient donors might alter the quality of the donated blood during processing, storage or in the recipients' circulatory system. The aim of this study was to determine the prevalence of SCT and G6PD deficiency among blood ...

The early alterations in some enzymatic activity, blood glucose and liver glycogen levels induced by atropine injection and whole

International Nuclear Information System (INIS)

Abdel-Fattah, K.I.; El-Sayed, N.M.; Abou-Safi, H.M.; Hussain, A.H.

1999-01-01

Detecting the early physiological and biochemical changes in the biological material after exposure to gamma irradiation is very helpful in the techniques of protection against radiation. The present work was designed for detecting the early changes in plasma phosphatases, transaminases, glucose and liver glycogen levels after irradiation and the role of atropine injected before irradiation on these parameters. Rats were divided into four groups: control. injected (i. m.) with atropine (0.5 mg/100 g B.Wt), irradiated at 6 Gy, and injected with atropine before irradiation. Plasma was collected at 1.3 and 5 hr after radiation exposure. Results showed that atropine exerted some amelioration during the first three hours, mainly, on acid phosphatase and GPT activities and on glucose and liver glycogen one hour only post irradiation. Generally, the limited radioprotective role of atropine is related, to its physiological mechanism in the body

Changes phosphorus associated to phosphatase activity because of application of carbon, nitrogen and manure

Science.gov (United States)

Paredes, Cecilia; Gianfreda, Liliana; Mora, María de la Luz

2015-04-01

The Chilean Andisols are of great importance in the economy of southern Chile supporting the bulk of agricultural production. The major characteristics of Chilean volcanic soils are the high adsorption capacity of P with a concomitant low P availability to plants. Studies preliminary using dairy cattle dung suggest that we can improve P availability using organic P sources within the soil because of microorganism. Phosphorous solubilization by microorganisms is a complex phenomenon, which depends on many factors such as nutritional, physiological and growth condition of the culture. The principal mechanism for mineral phosphate solubilization is the production of organic acids where the enzyme phosphatases play a major role in the mineralization of organic phosphorous in soil. The objective of this study was to evaluate changes in soil phosphorus fractions due to application the cattle dung, glucose, nitrogen (N) and phosphorus (P). In this experiment we incubated soil samples with 300 g of cattle dung, 30 mg kg-1 of N and P and 1000 mg glucose kg-1. The soil samples were moistened to field capacity and incubated in plastic bags to room temperature by different time. The changes in P forms in soil were monitored through the Hedley fractionation procedure and phosphatase activity. Our preliminary results indicated that the application of cattle dung, glucose nitrogen and phosphorus, caused the increased phosphatase activity until to 7 days and then apparently return to normal values. Interestingly, we observed a rise in the inorganic P fraction extracted by NaHCO3 in the same period. In summary, the increase biological activity by carbon and nitrogen increase P availability. Acknowledgements: The authors thank Fondecyt 1141247 Project.

Quantitative phosphoproteomics reveals new roles for the protein phosphatase PP6 in mitotic cells.

Science.gov (United States)

Rusin, Scott F; Schlosser, Kate A; Adamo, Mark E; Kettenbach, Arminja N

2015-10-13

Protein phosphorylation is an important regulatory mechanism controlling mitotic progression. Protein phosphatase 6 (PP6) is an essential enzyme with conserved roles in chromosome segregation and spindle assembly from yeast to humans. We applied a baculovirus-mediated gene silencing approach to deplete HeLa cells of the catalytic subunit of PP6 (PP6c) and analyzed changes in the phosphoproteome and proteome in mitotic cells by quantitative mass spectrometry-based proteomics. We identified 408 phosphopeptides on 272 proteins that increased and 298 phosphopeptides on 220 proteins that decreased in phosphorylation upon PP6c depletion in mitotic cells. Motif analysis of the phosphorylated sites combined with bioinformatics pathway analysis revealed previously unknown PP6c-dependent regulatory pathways. Biochemical assays demonstrated that PP6c opposed casein kinase 2-dependent phosphorylation of the condensin I subunit NCAP-G, and cellular analysis showed that depletion of PP6c resulted in defects in chromosome condensation and segregation in anaphase, consistent with dysregulation of condensin I function in the absence of PP6 activity. Copyright © 2015, American Association for the Advancement of Science.

Effect of blood glucose level on acute stress response of grass carp Ctenopharyngodon idella.

Science.gov (United States)

Jiang, Danli; Wu, Yubo; Huang, Di; Ren, Xing; Wang, Yan

2017-10-01

Stress has a considerable impact on welfare and productivity of fish, and blood glucose level of fish may be a factor modulating stress response. This study evaluated the effect of blood glucose level and handling on acute stress response of grass carp Ctenopharyngodon idella. Fish were intraperitoneally injected with glucose at 0, 0.2, 0.5, and 1.0 mg g -1 body mass (BM) and then were exposed to handling for 5 min. Glucose injection resulted in increase of plasma glucose level and liver glycogen content and decrease of plasma lactate level. Handling resulted in increase of plasma levels of cortisol, glucose, and lactate and plasma lactic dehydrogenase (LDH) activity and decrease of liver glycogen content. At 1 h post-stress, the plasma cortisol level was lower in the stressed fish injected with glucose at 0.5 mg g -1 BM than the stressed fish injected with glucose at 0, 0.2, and 1.0 mg g -1 BM. No significant differences were found in the activities of phosphoenolpyruvate carboxykinase (PEPCK) and pyruvate kinase (PK) in the liver between the stressed and unstressed fish, regardless of the dose of glucose injection. At 1 h post-stress, the liver glucose-6-phosphatase (G6Pase) activity was higher in the fish without glucose injection than in the fish injected with glucose. This study reveals that blood glucose level can affect stress response of grass carp by modulating cortisol release and glucose homeostasis through glycogen metabolism and gluconeogenesis in the liver.

Scoparia dulcis (SDF7) endowed with glucose uptake properties on L6 myotubes compared insulin.

Science.gov (United States)

Beh, Joo Ee; Latip, Jalifah; Abdullah, Mohd Puad; Ismail, Amin; Hamid, Muhajir

2010-05-04

Insulin stimulates glucose uptake and promotes the translocation of glucose transporter 4 (Glut 4) to the plasma membrane on L6 myotubes. The aim of this study is to investigate affect of Scoparia dulcis Linn water extracts on glucose uptake activity and the Glut 4 translocation components (i.e., IRS-1, PI 3-kinase, PKB/Akt2, PKC and TC 10) in L6 myotubes compared to insulin. Extract from TLC fraction-7 (SDF7) was used in this study. The L6 myotubes were treated by various concentrations of SDF7 (1 to 50 microg/ml) and insulin (1 to 100 nM). The glucose uptake activities of L6 myotubes were evaluated using 2-Deoxy-D-glucose uptake assay in with or without fatty acid-induced medium. The Glut 4 translocation components in SDF7-treated L6 myotubes were detected using immunoblotting and quantified by densitometry compared to insulin. Plasma membrane lawn assay and glycogen colorimetry assay were carried out in SDF7- and insulin-treated L6 myotubes in this study. Here, our data clearly shows that SDF7 possesses glucose uptake properties on L6 myotubes that are dose-dependent, time-dependent and plasma membrane Glut 4 expression-dependent. SDF7 successfully stimulates glucose uptake activity as potent as insulin at a maximum concentration of 50 microg/ml at 480 min on L6 myotubes. Furthermore, SDF7 stimulates increased Glut 4 expression and translocation to plasma membranes at equivalent times. Even in the insulin resistance stage (free fatty acids-induced), SDF7-treated L6 myotubes were found to be more capable at glucose transport than insulin treatment. Thus, we suggested that Scoparia dulcis has the potential to be categorized as a hypoglycemic medicinal plant based on its good glucose transport properties. (c) 2010 Elsevier Ireland Ltd. All rights reserved.

Assessment of insulin action in insulin-dependent diabetes mellitus using [6(14)C]glucose, [3(3)H]glucose, and [2(3)H]glucose. Differences in the apparent pattern of insulin resistance depending on the isotope used

International Nuclear Information System (INIS)

Bell, P.M.; Firth, R.G.; Rizza, R.A.

1986-01-01

To determine whether [2(3)H], [3(3)H], and [6(14)C]glucose provide an equivalent assessment of glucose turnover in insulin-dependent diabetes mellitus (IDDM) and nondiabetic man, glucose utilization rates were measured using a simultaneous infusion of these isotopes before and during hyperinsulinemic euglycemic clamps. In the nondiabetic subjects, glucose turnover rates determined with [6(14)C]glucose during insulin infusion were lower (P less than 0.02) than those determined with [2(3)H]glucose and higher (P less than 0.01) than those determined with [3(3)H]glucose. In IDDM, glucose turnover rates measured with [6(14)C]glucose during insulin infusion were lower (P less than 0.05) than those determined with [2(3)H]glucose, but were not different from those determined with [3(3)H]glucose. All three isotopes indicated the presence of insulin resistance. However, using [3(3)H]glucose led to the erroneous conclusion that glucose utilization was not significantly decreased at high insulin concentrations in the diabetic patients. [6(14)C] and [3(3)H]glucose but not [2(3)H]glucose indicated impairment in insulin-induced suppression of glucose production. These results indicate that tritiated isotopes do not necessarily equally reflect the pattern of glucose metabolism in diabetic and nondiabetic man

Purification and characterization of an alkaline phosphatase induced by phosphorus starvation in common bean (Phaseolus vulgaris L.) roots

International Nuclear Information System (INIS)

Morales, L.; Gutierrez, N.; Maya, V.; Parra, C.; Martinez B, E.; Coello, P.

2012-01-01

Two phosphatase isoforms from roots of the common bean (Phaseolus vulgaris L.) showed an increase in activity in response to phosphate deficiency. One of them (APIII) was chosen for further purification through ionic exchange chromatography and preparative electrophoresis. The estimated molecular mass of APIII was 35 kDa by both SDS-Page and gel filtration analyses, suggesting a monomeric form of the active enzyme. The phosphatase was classified as an alkaline phosphatase based on the requirement of ph 8 for optimum catalysis. It not only exhibited broad substrate specificity, with the most activity against pyrophosphate, but also effectively catalyzed the hydrolysis of polyphosphate, glucose-1-phosphate and phospho enol-pyruvate. Activity was completely inhibited by molybdate, vanadate and phosphate but was only partially inhibited by fluoride. Although divalent cations were not essential for the pyro phosphatase activity of this enzyme, the hydrolysis of pyro phosphatase increased substantially in the presence of Mg 2+ .

Purification and characterization of an alkaline phosphatase induced by phosphorus starvation in common bean (Phaseolus vulgaris L.) roots

Energy Technology Data Exchange (ETDEWEB)

Morales, L.; Gutierrez, N.; Maya, V.; Parra, C.; Martinez B, E.; Coello, P., E-mail: pcoello@servidor.unam.mx [UNAM, Facultad de Quimica, Departamento de Bioquimica, Ciudad Universitaria, 04510 Mexico D. F. (Mexico)

2012-07-01

Two phosphatase isoforms from roots of the common bean (Phaseolus vulgaris L.) showed an increase in activity in response to phosphate deficiency. One of them (APIII) was chosen for further purification through ionic exchange chromatography and preparative electrophoresis. The estimated molecular mass of APIII was 35 kDa by both SDS-Page and gel filtration analyses, suggesting a monomeric form of the active enzyme. The phosphatase was classified as an alkaline phosphatase based on the requirement of ph 8 for optimum catalysis. It not only exhibited broad substrate specificity, with the most activity against pyrophosphate, but also effectively catalyzed the hydrolysis of polyphosphate, glucose-1-phosphate and phospho enol-pyruvate. Activity was completely inhibited by molybdate, vanadate and phosphate but was only partially inhibited by fluoride. Although divalent cations were not essential for the pyro phosphatase activity of this enzyme, the hydrolysis of pyro phosphatase increased substantially in the presence of Mg{sup 2+}.

Non-Classical Gluconeogenesis-Dependent Glucose Metabolism in Rhipicephalus microplus Embryonic Cell Line BME26

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Renato Martins da Silva

2015-01-01

Full Text Available In this work we evaluated several genes involved in gluconeogenesis, glycolysis and glycogen metabolism, the major pathways for carbohydrate catabolism and anabolism, in the BME26 Rhipicephalus microplus embryonic cell line. Genetic and catalytic control of the genes and enzymes associated with these pathways are modulated by alterations in energy resource availability (primarily glucose. BME26 cells in media were investigated using three different glucose concentrations, and changes in the transcription levels of target genes in response to carbohydrate utilization were assessed. The results indicate that several genes, such as glycogen synthase (GS, glycogen synthase kinase 3 (GSK3, phosphoenolpyruvate carboxykinase (PEPCK, and glucose-6 phosphatase (GP displayed mutual regulation in response to glucose treatment. Surprisingly, the transcription of gluconeogenic enzymes was found to increase alongside that of glycolytic enzymes, especially pyruvate kinase, with high glucose treatment. In addition, RNAi data from this study revealed that the transcription of gluconeogenic genes in BME26 cells is controlled by GSK-3. Collectively, these results improve our understanding of how glucose metabolism is regulated at the genetic level in tick cells.

Roles of Protein Arginine Methyltransferases in the Control of Glucose Metabolism

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Hye-Sook Han

2014-12-01

Full Text Available Glucose homeostasis is tightly controlled by the regulation of glucose production in the liver and glucose uptake into peripheral tissues, such as skeletal muscle and adipose tissue. Under prolonged fasting, hepatic gluconeogenesis is mainly responsible for glucose production in the liver, which is essential for tissues, organs, and cells, such as skeletal muscle, the brain, and red blood cells. Hepatic gluconeogenesis is controlled in part by the concerted actions of transcriptional regulators. Fasting signals are relayed by various intracellular enzymes, such as kinases, phosphatases, acetyltransferases, and deacetylases, which affect the transcriptional activity of transcription factors and transcriptional coactivators for gluconeogenic genes. Protein arginine methyltransferases (PRMTs were recently added to the list of enzymes that are critical for regulating transcription in hepatic gluconeogenesis. In this review, we briefly discuss general aspects of PRMTs in the control of transcription. More specifically, we summarize the roles of four PRMTs: PRMT1, PRMT 4, PRMT 5, and PRMT 6, in the control of hepatic gluconeogenesis through specific regulation of FoxO1- and CREB-dependent transcriptional events.

Effects of 45Ca on murine skeletal muscle. 2

International Nuclear Information System (INIS)

Asotra, K.; Katoch, S.S.; Krishan, K.; Malhotra, R.K.

1983-01-01

Swiss albino mice were injected intraperitoneally with 3.7x10 4 Bq and 7.4x10 4 Bq 45 Ca/g body weight. 45 Ca-treated mice were sacrificed on days 1, 3, 5, 7, 14 and 28 and activities of acid phosphatase, alkaline phosphatase and glucose 6-phosphatase bioassayed in diaphragm and gastrocnemius. Activities of acid and alkaline phosphatases decreased after the 1st day of 45 Ca treatment in both the muscles compared with the normal controls. These two enzymes apparently do not contribute to myofiber necrosis in irradiated skeletal muscle. Glucose 6-phosphatase levels increased in the two irradiated muscles and with 7.4x10 4 Bq 45 Ca dose as much as 20-fold and 7-fold elevations are recorded in diaphragm and gastrocnemius, respectively, indicating a radiation-induced stimulation of inhibition of glucose 6-phosphatase channelization for energy generation. The possible role of elevated glucose 6-phosphatase levels in glycogen accumulation on account of radiations in skeletal muscle has been discussed. (author)

Biological and Clinical Study of 6-Deoxy-6-Iodo-D-Glucose: a iodinated tracer of glucose transport and of insulin-resistance in human

International Nuclear Information System (INIS)

Barone-Rochette, Gilles

2013-01-01

Insulin resistance (IR), characterized by a depressed cellular sensitivity to insulin in insulin-sensitive organs, is a central feature to obesity, the metabolic syndrome, and diabetes mellitus and leads to increase cardiovascular diseases, particularly heart failure. All these events are today serious public health problems. But actually, there is no simple tool to measure insulin resistance. The gold standard technique remains the hyperinsulinemic euglycemic clamp. However, the complexity and length of this technique render it unsuitable for routine clinical use. Many methods or index have been proposed to assess insulin resistance in human, but none have shown enough relevance to be used in clinical use. The U1039 INSERM unit previously has validated a new tracer of glucose transport, radiolabelled with 123 iodine and has developed a fast and simple imaging protocol with a small animal gamma camera, which allows the obtaining of an IR index for each organ, showing more discriminating for the heart. The project of my thesis was the human transfer of this measurement technique, perfectly validated in animal. The first part of this thesis evaluated to tolerance, in vivo kinetics, distribution and dosimetry of novel tracer of glucose transport, the [ 123 I]-6DIG. The safeties of new tracer and measurement technique were adequate. There were no adverse effects with excellent tolerance of the whole protocol. 6DIG eliminating was fast, primarily in the urine and complete within 72 h. The effective whole-body absorbed dose for a complete scan with injection of 92.5 * 2 MBq was between 3 to 4 mSv. The second part of this thesis evaluated in human feasibility and reproducibility of the measurement technique validated in animal. The third part showed techniques used to allow human transfer of this method. The study protocol was applied on 12 subjects (healthy volunteers (n=6) and type 2 diabetic patients (n=6)). With a method adapted to measure in humans, we determined an

PP2A contributes to endothelial death in high glucose: inhibition by benfotiamine.

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Du, Y; Kowluru, A; Kern, T S

2010-12-01

Endothelial death is critical in diabetic vascular diseases, but regulating factors have been only partially elucidated. Phosphatases play important regulatory roles in cell metabolism, but have not previously been implicated in hyperglycemia-induced cell death. We investigated the role of the phosphatase, type 2A protein phosphatase (PP2A), in hyperglycemia-induced changes in signaling and death in bovine aortic endothelial cells (BAEC). We explored also the influence of benfotiamine on this phosphatase. Activation of PP2A was assessed in BAEC by the extent of methylation and measurement of activity, and the enzyme was inhibited using selective pharmacological (okadaic acid, sodium fostriecin) and molecular (small interfering RNA) approaches. BAECs cultured in 30 mM glucose significantly increased PP2A methylation and activity, and PP2A inhibitors blocked these abnormalities. PP2A activity was increased also in aorta and retina from diabetic rats. NF-κB activity and cell death in BAEC were significantly increased in 30 mM glucose and inhibited by PP2A inhibition. NF-κB played a role in the hyperglycemia-induced death of BAEC, since blocking its translocation with SN50 also inhibited cell death. Inhibition of PP2A blocked the hyperglycemia-induced dephosphorylation of NF-κB and Bad, thus favoring cell survival. Incubation of benfotiamine with BAEC inhibited the high glucose-induced activation of PP2A and NF-κB and cell death, as well as several other metabolic defects, which likewise were inhibited by inhibitors of PP2A. Activation of PP2A contributes to endothelial cell death in high glucose, and beneficial actions of benfotiamine are due, at least in part, to inhibition of PP2A activation.

Berberine improves glucose metabolism in diabetic rats by inhibition of hepatic gluconeogenesis.

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Xuan Xia

2011-02-01

Full Text Available Berberine (BBR is a compound originally identified in a Chinese herbal medicine Huanglian (Coptis chinensis French. It improves glucose metabolism in type 2 diabetic patients. The mechanisms involve in activation of adenosine monophosphate activated protein kinase (AMPK and improvement of insulin sensitivity. However, it is not clear if BBR reduces blood glucose through other mechanism. In this study, we addressed this issue by examining liver response to BBR in diabetic rats, in which hyperglycemia was induced in Sprague-Dawley rats by high fat diet. We observed that BBR decreased fasting glucose significantly. Gluconeogenic genes, Phosphoenolpyruvate carboxykinase (PEPCK and Glucose-6-phosphatase (G6Pase, were decreased in liver by BBR. Hepatic steatosis was also reduced by BBR and expression of fatty acid synthase (FAS was inhibited in liver. Activities of transcription factors including Forkhead transcription factor O1 (FoxO1, sterol regulatory element-binding protein 1c (SREBP1 and carbohydrate responsive element-binding protein (ChREBP were decreased. Insulin signaling pathway was not altered in the liver. In cultured hepatocytes, BBR inhibited oxygen consumption and reduced intracellular adenosine triphosphate (ATP level. The data suggest that BBR improves fasting blood glucose by direct inhibition of gluconeogenesis in liver. This activity is not dependent on insulin action. The gluconeogenic inhibition is likely a result of mitochondria inhibition by BBR. The observation supports that BBR improves glucose metabolism through an insulin-independent pathway.

Setting sail for glucose homeostasis with the AKAP150-PP2B-anchor.

Science.gov (United States)

Teo, Adrian Kee Keong; Kulkarni, Rohit N

2012-10-17

Glucose-stimulated insulin secretion, controlled by multiple protein phosphorylation events, is critical for the regulation of glucose homeostasis. Protein kinase A (PKA) is known to play a role in β cell physiology, but the role of its anchoring protein is not fully understood. Hinke et al (2012) illustrate the significance of A-kinase anchoring protein 150 in tethering protein phosphatase 2B to mediate nutrient-stimulated insulin secretion and thus modulate glucose homeostasis.

Glucose 6-phosphate dehydrogenase variants in Japan.

Science.gov (United States)

Miwa, S

1980-01-01

Fifty-four cases of glucose 6-phosphate dehydrogenase (G6PD) deficiency have so far been reported in Japan. Among them, 21 G6PD variants have been characterized. Nineteen out of the 21 variants were characterized in our laboratory and G6PD Heian and "Kyoto" by others. G6PD Tokyo, Tokushima, Ogikubo, Kurume, Fukushima, Yokohama, Yamaguchi, Wakayama, Akita, Heian and "Kyoto" were classified as Class 1, because all these cases showed chronic hemolytic anemia and severe enzyme deficiency. All these variants showed thermal instability. G6PD Mediterranean-like, Ogori, Gifu and Fukuoka were classified as Class 2, whereas G6PD Hofu, B(-) Chinese, Ube, Konan, Kamiube and Kiwa belonged to Class 3. All the 6 Class 3 variants were found as the results of the screening tests. The incidence of the deficiency in Japanese seems to be 0.1-0.5% but that of the cases which may slow drug-induced hemolysis would be much less. G6PD Ube and Konan appear to be relatively common in Japan.

Alantolactone Improves Prolonged Exposure of Interleukin-6-Induced Skeletal Muscle Inflammation Associated Glucose Intolerance and Insulin Resistance

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Minjee Kim

2017-06-01

Full Text Available The pro-inflammatory cytokine, Interleukin-6 (IL-6, has been proposed to be one of the mediators that link chronic inflammation to glucose intolerance and insulin resistance. Many studies have demonstrated the effects of IL-6 on insulin action in the skeletal muscle. However, few studies have investigated the effect of long-term treatment of IL-6, leading to glucose intolerance and insulin resistance. In the present study, we observed protective effects of alantolactone, a sesquiterpene lactone isolated from Inula helenium against glucose intolerance and insulin resistance induced by prolonged exposure of IL-6. Alantolactone has been reported to have anti-inflammatory and anti-cancer effects through IL-6-induced signal transducer and activator of transcription 3 (STAT3 signaling pathway. The relationship between IL-6 exposure and expression of toll-like receptor 4 (TLR4, involved in inflammation in the skeletal muscle, and the underlying mechanisms were investigated. We observed maximum dysregulation of glucose uptake after 40 ng/ml IL-6 induction for 24 h in L6 myotubes. Prolonged IL-6 exposure suppressed glucose uptake regulating alpha serine/threonine-protein kinase (AKT phosphorylation; however, pretreatment with alantolactone activated AKT phosphorylation and improved glucose uptake. Alantolactone also attenuated IL-6-stimulated STAT3 phosphorylation, followed by an increase in expression of negative regulator suppressor of cytokine signaling 3 (SOCS3. Furthermore, IL-6-induced expression of pathogen recognition receptor, TLR4, was also suppressed by alantolactone pretreatment. Post-silencing of STAT3 using siRNA approach, IL-6-stimulated siRNA-STAT3 improved glucose uptake and suppressed TLR4 gene expression. Taken together, we propose that, as a STAT3 inhibitor, alantolactone, improves glucose regulation in the skeletal muscle by inhibiting IL-6-induced STAT3-SOCS3 signaling followed by inhibition of the TLR4 gene expression. Therefore

The Action of Antidiabetic Plants of the Canadian James Bay Cree Traditional Pharmacopeia on Key Enzymes of Hepatic Glucose Homeostasis

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Abir Nachar

2013-01-01

Full Text Available We determined the capacity of putative antidiabetic plants used by the Eastern James Bay Cree (Canada to modulate key enzymes of gluconeogenesis and glycogen synthesis and key regulating kinases. Glucose-6-phosphatase (G6Pase and glycogen synthase (GS activities were assessed in cultured hepatocytes treated with crude extracts of seventeen plant species. Phosphorylation of AMP-dependent protein kinase (AMPK, Akt, and Glycogen synthase kinase-3 (GSK-3 were probed by Western blot. Seven of the seventeen plant extracts significantly decreased G6Pase activity, Abies balsamea and Picea glauca, exerting an effect similar to insulin. This action involved both Akt and AMPK phosphorylation. On the other hand, several plant extracts activated GS, Larix laricina and A. balsamea, far exceeding the action of insulin. We also found a significant correlation between GS stimulation and GSK-3 phosphorylation induced by plant extract treatments. In summary, three Cree plants stand out for marked effects on hepatic glucose homeostasis. P. glauca affects glucose production whereas L. laricina rather acts on glucose storage. However, A. balsamea has the most promising profile, simultaneously and powerfully reducing G6Pase and stimulating GS. Our studies thus confirm that the reduction of hepatic glucose production likely contributes to the therapeutic potential of several antidiabetic Cree traditional medicines.

Kernicterus by glucose-6-phosphate dehydrogenase deficiency: a case report and review of the literature

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Cossio de Gurrola Gladys

2008-05-01

Full Text Available Abstract Introduction Glucose-6-phosphate dehydrogenase deficiency is an X-linked recessive disease that causes acute or chronic hemolytic anemia and potentially leads to severe jaundice in response to oxidative agents. This deficiency is the most common human innate error of metabolism, affecting more than 400 million people worldwide. Case presentation Here, we present the first documented case of kernicterus in Panama, in a glucose-6-phosphate dehydrogenase-deficient newborn clothed in naphthalene-impregnated garments, resulting in reduced psychomotor development, neurosensory hypoacousia, absence of speech and poor reflex of the pupil to light. Conclusion Mutational analysis revealed the glucose-6-phosphate dehydrogenase Mediterranean polymorphic variant, which explained the development of kernicterus after exposition of naphthalene. As the use of naphthalene in stored clothes is a common practice, glucose-6-phosphate dehydrogenase testing in neonatal screening could prevent severe clinical consequences.

Hepatic protein phosphatase 1 regulatory subunit 3B (Ppp1r3b) promotes hepatic glycogen synthesis and thereby regulates fasting energy homeostasis.

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Mehta, Minal B; Shewale, Swapnil V; Sequeira, Raymond N; Millar, John S; Hand, Nicholas J; Rader, Daniel J

2017-06-23

Maintenance of whole-body glucose homeostasis is critical to glycemic function. Genetic variants mapping to chromosome 8p23.1 in genome-wide association studies have been linked to glycemic traits in humans. The gene of known function closest to the mapped region, PPP1R3B (protein phosphatase 1 regulatory subunit 3B), encodes a protein (G L ) that regulates glycogen metabolism in the liver. We therefore sought to test the hypothesis that hepatic PPP1R3B is associated with glycemic traits. We generated mice with either liver-specific deletion ( Ppp1r3b Δ hep ) or liver-specific overexpression of Ppp1r3b The Ppp1r3b deletion significantly reduced glycogen synthase protein abundance, and the remaining protein was predominantly phosphorylated and inactive. As a consequence, glucose incorporation into hepatic glycogen was significantly impaired, total hepatic glycogen content was substantially decreased, and mice lacking hepatic Ppp1r3b had lower fasting plasma glucose than controls. The concomitant loss of liver glycogen impaired whole-body glucose homeostasis and increased hepatic expression of glycolytic enzymes in Ppp1r3b Δ hep mice relative to controls in the postprandial state. Eight hours of fasting significantly increased the expression of two critical gluconeogenic enzymes, phosphoenolpyruvate carboxykinase and glucose-6-phosphatase, above the levels in control livers. Conversely, the liver-specific overexpression of Ppp1r3b enhanced hepatic glycogen storage above that of controls and, as a result, delayed the onset of fasting-induced hypoglycemia. Moreover, mice overexpressing hepatic Ppp1r3b upon long-term fasting (12-36 h) were protected from blood ketone-body accumulation, unlike control and Ppp1r3b Δ hep mice. These findings indicate a major role for Ppp1r3b in regulating hepatic glycogen stores and whole-body glucose/energy homeostasis. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Real-time continuous glucose monitoring shows high accuracy within 6 hours after sensor calibration: a prospective study.

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Xiao-Yan Yue

Full Text Available Accurate and timely glucose monitoring is essential in intensive care units. Real-time continuous glucose monitoring system (CGMS has been advocated for many years to improve glycemic management in critically ill patients. In order to determine the effect of calibration time on the accuracy of CGMS, real-time subcutaneous CGMS was used in 18 critically ill patients. CGMS sensor was calibrated with blood glucose measurements by blood gas/glucose analyzer every 12 hours. Venous blood was sampled every 2 to 4 hours, and glucose concentration was measured by standard central laboratory device (CLD and by blood gas/glucose analyzer. With CLD measurement as reference, relative absolute difference (mean±SD in CGMS and blood gas/glucose analyzer were 14.4%±12.2% and 6.5%±6.2%, respectively. The percentage of matched points in Clarke error grid zone A was 74.8% in CGMS, and 98.4% in blood gas/glucose analyzer. The relative absolute difference of CGMS obtained within 6 hours after sensor calibration (8.8%±7.2% was significantly less than that between 6 to 12 hours after calibration (20.1%±13.5%, p<0.0001. The percentage of matched points in Clarke error grid zone A was also significantly higher in data sets within 6 hours after calibration (92.4% versus 57.1%, p<0.0001. In conclusion, real-time subcutaneous CGMS is accurate in glucose monitoring in critically ill patients. CGMS sensor should be calibrated less than 6 hours, no matter what time interval recommended by manufacturer.

Sensitive detection of alkaline phosphatase by switching on gold nanoclusters fluorescence quenched by pyridoxal phosphate.

Science.gov (United States)

Halawa, Mohamed Ibrahim; Gao, Wenyue; Saqib, Muhammad; Kitte, Shimeles Addisu; Wu, Fengxia; Xu, Guobao

2017-09-15

In this work, we designed highly sensitive and selective luminescent detection method for alkaline phosphatase using bovine serum albumin functionalized gold nanoclusters (BSA-AuNCs) as the nanosensor probe and pyridoxal phosphate as the substrate of alkaline phosphatase. We found that pyridoxal phosphate can quench the fluorescence of BSA-AuNCs and pyridoxal has little effect on the fluorescence of BSA-AuNCs. The proposed mechanism of fluorescence quenching by PLP was explored on the basis of data obtained from high-resolution transmission electron microscopy (HRTEM), dynamic light scattering (DLS), UV-vis spectrophotometry, fluorescence spectroscopy, fluorescence decay time measurements and circular dichroism (CD) spectroscopy. Alkaline phosphatase catalyzes the hydrolysis of pyridoxal phosphate to generate pyridoxal, restoring the fluorescence of BSA-AuNCs. Therefore, a recovery type approach has been developed for the sensitive detection of alkaline phosphatase in the range of 1.0-200.0U/L (R 2 =0.995) with a detection limit of 0.05U/L. The proposed sensor exhibit excellent selectivity among various enzymes, such as glucose oxidase, lysozyme, trypsin, papain, and pepsin. The present switch-on fluorescence sensing strategy for alkaline phosphatase was successfully applied in human serum plasma with good recoveries (100.60-104.46%), revealing that this nanosensor probe is a promising tool for ALP detection. Copyright © 2017 Elsevier B.V. All rights reserved.

Effects of subacute and chronic lead treatment on glucose homestasis and renal cyclic AMP metabolism in rats

Energy Technology Data Exchange (ETDEWEB)

Stevenson, A; Merali, Z; Kacew, S; Singhal, R L

1976-01-01

The effects of chronic oral ingestion of lead in doses ranging from 20 to 80 ppM were compared with those seen after the subacute exposure of rats to a 10 mg/kg daily dose of the heavy metal for 7 days. Irrespective of the treatment regimen used, lead treatment significantly increased the activities of renal pyruvate carboxylase, phosphoenolpyruvate carboxykinase, fructose 1,6-diphosphatase and glucose 6-phosphatase. The observed enhancement of kidney gluconeogenic enzymes in chronically treated animals was associated with a stimulation of the adenylate cyclase-cyclic AMP system, a rise in blood glucose and urea as well as a depression in hepatic glycogen and serum immunoreactive insulin (IRI) levels. In contrast, subacute exposure to lead failed to significantly alter cyclic AMP metabolism and the concentrations of liver glycogen, blood glucose, serum urea or IRI. Whereas the insulinogenic index (the ratio of serum IRI to blood glucose concentration) was markedly suppressed in chronically treated rats, this ratio remained within normal limits following subacute exposure to the heavy metal. However, a marked decrease in the insulinogenic index was observed in subacutely treated rats 15 min after the administration of a glucose load. The data provide evidence to show that increased glucose synthesis as well as suppressed pancreatic function may be responsible for lead-induced disturbances in glucose homeostasis.

Proanthocyanidins Prevent High Glucose-Induced Eye Malformation by Restoring Pax6 Expression in Chick Embryo

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Rui-Rong Tan

2015-08-01

Full Text Available Gestational diabetes mellitus (GDM is one of the leading causes of offspring malformations, in which eye malformation is an important disease. It has raised demand for therapy to improve fetal outcomes. In this study, we used chick embryo to establish a GDM model to study the protective effects of proanthocyanidins on eye development. Chick embryos were exposed to high glucose (0.2 mmol/egg on embryo development day (EDD 1. Proanthocyanidins (1 and 10 nmol/egg were injected into the air sac on EDD 0. Results showed that both dosages of proanthocyanidins could prevent the eye malformation and rescue the high glucose-induced oxidative stress significantly, which the similar effects were showed in edaravone. However, proanthocyanidins could not decrease the glucose concentration of embryo eye. Moreover, the key genes regulating eye development, Pax6, was down-regulated by high glucose. Proanthocyanidins could restore the suppressed expression of Pax6. These results indicated proanthocyanidins might be a promising natural agent to prevent high glucose-induced eye malformation by restoring Pax6 expression.

Posttranslational regulation of glucose-6-phosphate dehydrogenase activity in tongue epithelium

NARCIS (Netherlands)

Biagiotti, E.; Bosch, K. S.; Ninfali, P.; Frederiks, W. M.; van Noorden, C. J.

2000-01-01

Expression of glucose-6-phosphate dehydrogenase (G6PD) activity is high in tongue epithelium, but its exact function is still unknown, it may be related;either to the high proliferation rate of this tissue or to protection against oxidative stress. To elucidate its exact role, we localized

Intravenous immunoglobulin to treat hyperbilirubinemia in neonates with isolated Glucose-6-Phosphate dehydrogenase deficiency

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Wadah Khriesat

2017-04-01

Full Text Available Background Glucose-6-phosphate dehydrogenase deficiency alone or concomitant with ABO isoimmunisation is a widespread indication for neonatal exchange transfusion. Aims To evaluate the effectiveness of Intravenous Immunoglobulin in the treatment of neonatal hyperbilirubinemia due to glucose-6-phosphate dehydrogenase deficiency. Methods A retrospective cohort study was conducted between 2006 and 2014 at the Jordan University of Science and technology. The medical records of 43 infants admitted to the neonatal intensive care unit for isolated glucose-6- phosphate dehydrogenase deficiency hemolytic disease of the newborns were reviewed. Patients were divided into two groups. Group I, a historical cohort, included newborns born between 2006 and 2010, Treatment included phototherapy and exchange transfusion. Group II included newborns born between 2011 and 2014, where, in addition to phototherapy, intravenous immunoglobulin was administered. The duration of phototherapy and number of exchange transfusions were evaluated. Results Of 412 newborns that were admitted with neonatal hyperbilirubinemia, Glucose-6-phosphate dehydrogenase deficiency was present in 43. Of these, 22, did not receive intravenous immunoglobulin and served as a control group. The other 21 newborns received intravenous immunoglobulin. There was no difference in the demographic characteristics between the two groups. Infants in the control group were significantly more likely to receive exchange blood transfusion than infants in the immunoglobulin treatment group, but were significantly less likely to need phototherapy. Conclusion Intravenous immunoglobulin is an effective alternative to exchange transfusion in infants with glucose-6-phosphate dehydrogenase deficiency hemolytic disease of the newborn. It is suggested that intravenous immunoglobulin may be beneficial as a prophylaxis for infants with hyperbilirubinemia.

Cytophotometry of glucose-6-phosphate dehydrogenase activity in individual cells

NARCIS (Netherlands)

van Noorden, C. J.; Tas, J.; Vogels, I. M.

1983-01-01

With the aid of thin films of polyacrylamide gel containing purified glucose-6-phosphate dehydrogenase subjected to cytochemical procedures for the enzyme using tetranitro blue tetrazolium, arbitrary units of integrated absorbance obtained with a Barr & Stroud GN5 cytophotometer were converted into

Glucose-6-phosphate dehydrogenase deficiency in Singapore.

Science.gov (United States)

Quak, S H; Saha, N; Tay, J S

1996-01-01

Glucose-6-phosphate dehydrogenase (G6PD) in man is an X-linked enzyme. The deficiency of this enzyme is one of the most common inherited metabolic disorders in man. In Singapore, three clinical syndromes associated with G6PD deficiency had been described: severe haemolysis in neonates with kernicterus, haemoglobinuria and "viral hepatitis"-like syndrome. The human G6PD monomer consists of 515 amino acids. Only the tetrameric or dimeric forms composed of a single type subunit are catylitically active. The complete amino acid sequence of G6PD had been elucidated in man and various other animals. The region of high homology among the enzymes of various animals is presumably functionally active. Among the Chinese in Singapore, three common molecular variants had been identified: Canton (nt 1376 G --> T), Kaiping (nt 1388 G --> A) and Mediterranean (nt 563 C --> T) in frequencies of 24%, 21% and 10% respectively. In addition, two common mutants (Gaozhou, nt 95 A --> G and Chinese 5, nt 1024 C --> T) have been detected in Singapore Chinese in low frequencies. In Malays, 6 different deficient variants are known in Singapore (3 new, 1 Mahidol, 1 Indonesian and 1 Mediterranean).

A variant in the G6PC2/ABCB11 locus is associated with increased fasting plasma glucose, increased basal hepatic glucose production and increased insulin release after oral and intravenous glucose loads

DEFF Research Database (Denmark)

Rose, C S; Grarup, N; Krarup, N T

2009-01-01

An association between elevated fasting plasma glucose and the common rs560887 G allele in the G6PC2/ABCB11 locus has been reported. In Danes we aimed to examine rs560887 in relation to plasma glucose and serum insulin responses following oral and i.v. glucose loads and in relation to hepatic...... glucose production during a hyperinsulinaemic-euglycaemic clamp. Furthermore, we examined rs560887 for association with impaired fasting glycaemia (IFG), impaired glucose tolerance (IGT), type 2 diabetes and components of the metabolic syndrome....

Intestinal gluconeogenesis is crucial to maintain a physiological fasting glycemia in the absence of hepatic glucose production in mice.

Science.gov (United States)

Penhoat, Armelle; Fayard, Laetitia; Stefanutti, Anne; Mithieux, Gilles; Rajas, Fabienne

2014-01-01

Similar to the liver and kidneys, the intestine has been strongly suggested to be a gluconeogenic organ. However, the precise contribution of the intestine to endogenous glucose production (EGP) remains to be determined. To define the quantitative role of intestinal gluconeogenesis during long-term fasting, we compared changes in blood glucose during prolonged fasting in mice with a liver-deletion of the glucose-6 phosphatase catalytic (G6PC) subunit (LKO) and in mice with a combined deletion of G6PC in both the liver and the intestine (ILKO). The LKO and ILKO mice were studied after 6h and 40 h of fasting by measuring metabolic and hormonal plasmatic parameters, as well as the expression of gluconeogenic enzymes in the liver, kidneys and intestine. After a transient hypoglycemic episode (approximately 60 mg/dL) because of their incapacity to mobilize liver glycogen, the LKO mice progressively re-increased their plasma glucose to reach a glycemia comparable to that of wild-type mice (90 mg/dL) from 30 h of fasting. This increase was associated with a rapid induction of renal and intestinal gluconeogenic gene expression, driven by glucagon, glucocorticoids and acidosis. The ILKO mice exhibited a similar induction of renal gluconeogenesis. However, these mice failed to re-increase their glycemia and maintained a plasma glucose level of only 60 mg/dL throughout the 48 h-fasting period. These data indicate that intestinal glucose production is essential to maintain glucose homeostasis in the absence of hepatic glucose production during fasting. These data provide a definitive quantitative estimate of the capacity of intestinal gluconeogenesis to sustain EGP during long-term fasting. © 2013.

Elevated Serum Level of Human Alkaline Phosphatase in Obesity

International Nuclear Information System (INIS)

Khan, A. R.; Awan, F. R.; Najam, S. S.; Islam, M.; Siddique, T.; Zain, M.

2015-01-01

Objective: To investigate a correlation between serum alkaline phosphatase level and body mass index in human subjects. Methods: The comparative cross-sectional study was carried out at the National Institute for Biotechnology and Genetic Engineering, Faisalabad, Pakistan, from April 2012 to June 2013. Blood serum alkaline phosphatase levels were estimated and the subjects were divided into three sub-groups on the basis of their body mass index: normal weight (<25kg/m2), overweight (25-27kg/m2) and obese (>27kg/m2) subjects. The serum samples were used for the estimation of clinically important biochemical parameters, using commercial kits on clinical chemistry analyser. Results: Of the 197 subjects, 97(49 percent) were obese and 100(51 percent) were non-obese. The serum alkaline phosphatase level increased in obese (214±6.4 IU/L) compared to the non-obese subjects (184.5±5 IU/L). Furthermore, a significant linear relationship (r=0.3;p-0.0001) was found between serum alkaline phosphatase and body mass index. Other biochemical variables were not correlated to the body mass index. Conclusion: Over activity and higher amounts of alkaline phosphatase were linked to the development of obesity. (author)

Alkaline and Acid Phosphatase Activity in Blood Plasma of Chickens Irradiated by Low dose Gamma Radiation

International Nuclear Information System (INIS)

Petar, K.; Marinko, V.; Saveta, M.; Miljenko, S.

2004-01-01

In our previous paper (Kraljevic et, al, 2000; Kraljevic et al 2002) we showed that the growth of the chickens hatched from eggs irradiated with 0.15 Gy gamma-rays before incubation was significantly higher than in controls during the fattening period (1-42 days). The concentration of total protein, glucose and cholesterol in the blood plasma of the same chickens was also significantly changed. In this paper an attempt was made to determine the effect of irradiation of eggs by low dose ionizing radiation before incubation upon activity of alkaline and acid phosphatase in the blood plasma of chickens hatched from irradiated eggs. The eggs of heavy breeding chickens were irradiated by dose of 0.15 Gy gamma radiation (60 Co) before incubation. Along with the chickens which were hatched from irradiated eggs, there was a control group of chickens hatched from nonirradiated eggs. All other conditions were the same for both groups. After hatching, blood samples were taken from the wing vein on days 1, 3, 5, 6, 10, 20, 30 and 42. The activity of both enzymes was determined spectrophotometrically by using Boehring Mannheim GmbH optimized kits. the activity of alkaline phosphatase in blood plasma was decreased on days 42, and the activity of acid phosphatase in the blood plasma of the same chickens was increased on day 42. Obtained results confirm our early obtained results that low dose of gamma radiation has effects upon metabolic processes in the chickens hatched from eggs irradiated before incubation. (Author)

D-glucose-6-phosphate dehydrogenase (Entner-Doudoroff enzyme) from Pseudomonas fluorescens

International Nuclear Information System (INIS)

Lessmann, D.; Schimz, K.L.; Kurz, G.

1975-01-01

The existence of two different D-glucose-6-phosphate dehydrogenases in Pseudomonas fluorescens has been demonstrated. Based on their different specificity and their different metabolic regulation one enzyme is appointed to the Entner-Doudoroff pathway and the other to the hexose monophosphate pathway. A procedure is described for the isolation of that D-glucose-6-phosphate dehydrogenase which forms part of the Entner-Doudoroff pathway (Entner-Doudoroff enzyme). A 950-fold purification was achieved with an overall yield of 44%. The final preparation, having a specific activity of about 300μmol NADH formed per min per mg protein, was shown to be homogeneous. The molecular weight of the Entner-Doudoroff enzyme has been determined to be 220,000 by gel permeation chromatography, and that of the other enzyme (Zwischenferment) has been shown to be 265,000. The pI of the Entner-Doudoroff enzyme has been shown to be 5.24 and that of the Zwischenferment 4.27. The Entner-Doudoroff enzyme is stable in the range of pH 6 to 10.5 and shows its maximal acivity at pH 8.9. The Entner-Doudoroff enzyme showed specificity for NAD + as well as for NADP + and exhibited homotropic effects for D-glucose 6-phosphate. It is inhibited by ATP which acts as a negative allosteric effector. Other nucleoside triphosphates as well as ADP are also inhibitory. The enzyme catalyzes the transfer of the axial hydrogen at carbon-1 of β-D-glucopyranose 6-phosphate to the si face of carbon-4 of the nicotinamide ring and must be classified as B-side stereospecific dehydrogenase. (orig.) [de

Trehalose-6-Phosphate-Mediated Toxicity Determines Essentiality of OtsB2 in Mycobacterium tuberculosis In Vitro and in Mice.

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Jan Korte

2016-12-01

Full Text Available Trehalose biosynthesis is considered an attractive target for the development of antimicrobials against fungal, helminthic and bacterial pathogens including Mycobacterium tuberculosis. The most common biosynthetic route involves trehalose-6-phosphate (T6P synthase OtsA and T6P phosphatase OtsB that generate trehalose from ADP/UDP-glucose and glucose-6-phosphate. In order to assess the drug target potential of T6P phosphatase, we generated a conditional mutant of M. tuberculosis allowing the regulated gene silencing of the T6P phosphatase gene otsB2. We found that otsB2 is essential for growth of M. tuberculosis in vitro as well as for the acute infection phase in mice following aerosol infection. By contrast, otsB2 is not essential for the chronic infection phase in mice, highlighting the substantial remodelling of trehalose metabolism during infection by M. tuberculosis. Blocking OtsB2 resulted in the accumulation of its substrate T6P, which appears to be toxic, leading to the self-poisoning of cells. Accordingly, blocking T6P production in a ΔotsA mutant abrogated otsB2 essentiality. T6P accumulation elicited a global upregulation of more than 800 genes, which might result from an increase in RNA stability implied by the enhanced neutralization of toxins exhibiting ribonuclease activity. Surprisingly, overlap with the stress response caused by the accumulation of another toxic sugar phosphate molecule, maltose-1-phosphate, was minimal. A genome-wide screen for synthetic lethal interactions with otsA identified numerous genes, revealing additional potential drug targets synergistic with OtsB2 suitable for combination therapies that would minimize the emergence of resistance to OtsB2 inhibitors.

21 CFR 864.7360 - Erythrocytic glucose-6-phosphate dehydrogenase assay.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Erythrocytic glucose-6-phosphate dehydrogenase assay. 864.7360 Section 864.7360 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Hematology Kits and Packages...

Identification and characterization of a pyridoxal 5'-phosphate phosphatase in the silkworm (Bombyx mori).

Science.gov (United States)

Huang, ShuoHao; Han, CaiYun; Ma, ZhenQiao; Zhou, Jie; Zhang, JianYun; Huang, LongQuan

2017-03-01

Vitamin B 6 comprises six interconvertible pyridine compounds, among which pyridoxal 5'-phosphate (PLP) is a coenzyme for over 140 enzymes. PLP is also a very reactive aldehyde. The most well established mechanism for maintaining low levels of free PLP is its dephosphorylation by phosphatases. A human PLP-specific phosphatase has been identified and characterized. However, very little is known about the phosphatase in other living organisms. In this study, a cDNA clone of putative PLP phosphatase was identified from B. mori and characterized. The cDNA encodes a polypeptide of 343 amino acid residues, and the recombinant enzyme purified from E. coli exhibited properties similar to that of human PLP phosphatase. B. mori has a single copy of the PLPP gene, which is located on 11th chromosome, spans a 5.7kb region and contains five exons and four introns. PLP phosphatase transcript was detected in every larva tissue except hemolymph, and was most highly represented in Malpighian tube. We further down-regulated the gene expression of the PLP phosphatase in 5th instar larvae with the RNA interference. However, no significant changes in the gene expression of PLP biosynthetic enzymes and composition of B 6 vitamers were detected as compared with the control. Copyright © 2017 Elsevier Inc. All rights reserved.

High glucose modifies transient receptor potential canonical type 6 channels via increased oxidative stress and syndecan-4 in human podocytes

DEFF Research Database (Denmark)

Thilo, Florian; Lee, Marlene; Xia, Shengqiang

2014-01-01

oxidative stress and syndecan-4 (SDC-4) in human podocytes. Human podocytes were exposed to control conditions (5.6 mmol/L D-glucose), high glucose (30 mmol/L D-glucose or L-glucose), 100 μmol/L peroxynitrite, or high glucose and the superoxide dismutase mimetic tempol (100 μmol/L). TRPC6 and SDC-4...... transcripts and protein expression were measured using RT-PCR and in-cell Western assay. Intracellular reactive oxygen species (ROS) and cytosolic calcium were measured using fluorescent dye techniques. High D-glucose increased TRPC6 transcripts to 8.66±4.08 (p....44±0.07 (poxidative stress using peroxynitrite significantly increased TRPC6 transcripts to 4.29±1.26 (p

Trehalose-6-Phosphate: connecting plant metabolism and development

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Jathish ePonnu

2011-11-01

Full Text Available Beyond their metabolic roles, sugars can also act as messengers in signal transduction. Trehalose, a sugar found in many species of plants and animals, is a non-reducing disaccharide composed of two glucose moieties. Its synthesis in plants is a two-step process, involving the production of trehalose-6-phosphate (T6P catalyzed by TREHALOSE-6-PHOSPHATE SYNTHASE (TPS and its consecutive dephosphorylation to trehalose, catalyzed by TREHALOSE-6-PHOSPHATE PHOSPHATASE (TPP. T6P has recently emerged as an important signaling metabolite, regulating carbon assimilation and sugar status in plants. In addition, T6P has also been demonstrated to play an essential role in plant development. This review recapitulates the recent advances in our understanding the role of T6P in coordinating diverse metabolic and developmental processes.

In vitro silencing of Brugia malayi trehalose-6-phosphate phosphatase impairs embryogenesis and in vivo development of infective larvae in jirds.

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Susheela Kushwaha

Full Text Available The trehalose metabolic enzymes have been considered as potential targets for drug or vaccine in several organisms such as Mycobacterium, plant nematodes, insects and fungi due to crucial role of sugar trehalose in embryogenesis, glucose uptake and protection from stress. Trehalose-6-phosphate phosphatase (TPP is one of the enzymes of trehalose biosynthesis that has not been reported in mammals. Silencing of tpp gene in Caenorhabditis elegans revealed an indispensable functional role of TPP in nematodes.In the present study, functional role of B. malayi tpp gene was investigated by siRNA mediated silencing which further validated this enzyme to be a putative antifilarial drug target. The silencing of tpp gene in adult female B. malayi brought about severe phenotypic deformities in the intrauterine stages such as distortion and embryonic development arrest. The motility of the parasites was significantly reduced and the microfilarial production as well as their in vitro release from the female worms was also drastically abridged. A majority of the microfilariae released in to the culture medium were found dead. B. malayi infective larvae which underwent tpp gene silencing showed 84.9% reduced adult worm establishment after inoculation into the peritoneal cavity of naïve jirds.The present findings suggest that B. malayi TPP plays an important role in the female worm embryogenesis, infectivity of the larvae and parasite viability. TPP enzyme of B. malayi therefore has the potential to be exploited as an antifilarial drug target.

Glucose-6-phosphate dehydrogenase protects Escherichia coli from tellurite-mediated oxidative stress.

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Juan M Sandoval

Full Text Available The tellurium oxyanion tellurite induces oxidative stress in most microorganisms. In Escherichia coli, tellurite exposure results in high levels of oxidized proteins and membrane lipid peroxides, inactivation of oxidation-sensitive enzymes and reduced glutathione content. In this work, we show that tellurite-exposed E. coli exhibits transcriptional activation of the zwf gene, encoding glucose 6-phosphate dehydrogenase (G6PDH, which in turn results in augmented synthesis of reduced nicotinamide adenine dinucleotide phosphate (NADPH. Increased zwf transcription under tellurite stress results mainly from reactive oxygen species (ROS generation and not from a depletion of cellular glutathione. In addition, the observed increase of G6PDH activity was paralleled by accumulation of glucose-6-phosphate (G6P, suggesting a metabolic flux shift toward the pentose phosphate shunt. Upon zwf overexpression, bacterial cells also show increased levels of antioxidant molecules (NADPH, GSH, better-protected oxidation-sensitive enzymes and decreased amounts of oxidized proteins and membrane lipids. These results suggest that by increasing NADPH content, G6PDH plays an important role in E. coli survival under tellurite stress.

Glucose 6 phosphate dehydrogenase deficiency in adults

International Nuclear Information System (INIS)

Khan, M.

2004-01-01

Objective: To determine the frequency of glucose-6-phosphate dehydrogenase (G6PD) deficiency in adults presented with anemia. Subjects and Methods: Eighteen months admission data was reviewed for G6PD deficiency as a cause of anemia. Anemia was defined by world health organization (WHO) criteria as haemoglobin less than 11.3 gm%. G6PD activity was measured by Sigma dye decolorisation method. All patients were screened for complications of hemolysis and its possible cause. Patients with more than 13 years of age were included in the study. Results: Out of 3600 patients admitted, 1440 were found anaemic and 49 as G6PD deficient. So the frequency of G6PD deficiency in anaemic patients was 3.4% and the overall frequency is 1.36%. G6PD deficiency among males and females was three and six percent respectively. Antimalarials and antibiotics containing sulphonamide group were the most common precipitating factors for hemolysis. Anemia and jaundice were the most common presentations while malaria was the most common associated disease. Acute renal failure was the most severe complication occurring in five patients with two deaths. Conclusion: G6PD deficiency is a fairly common cause of anemia with medicine as common precipitating factor for hemolysis. Such complications can be avoided with early recognition of the disease and avoiding indiscriminate use of medicine. (author)

Reagent-less amperometric glucose biosensor based on a graphite rod electrode layer-by-layer modified with 1,10-phenanthroline-5,6-dione and glucose oxidase.

Science.gov (United States)

Kausaite-Minkstimiene, Asta; Simanaityte, Ruta; Ramanaviciene, Almira; Glumbokaite, Laura; Ramanavicius, Arunas

2017-08-15

A reagent-less amperometric glucose biosensor operating in not-stirred sample solution was developed. A working electrode of the designed biosensor was based on a graphite rod (GR) electrode, which was modified with 1,10-phenanthroline-5,6-dione (PD) and glucose oxidase (GOx). The PD and the GOx were layer-by-layer adsorbed on the GR electrode surface with subsequent drying followed by chemical cross-linking of the adsorbed GOx with glutaraldehyde (GA). Optimal preparation conditions of the working electrode (GR/PD/GOx) were achieved with 12.6μg and 0.24mg loading amount of PD and GOx, respectively and 25min lasting cross-linking of the GOx with GA. A current response to glucose of the GR/PD/GOx electrode was measured at +200mV potential vs Ag/AgCl reference electrode. Maximum current response was registered when the pH of the buffer solution was 6.0. The registered current response to glucose was linear in the concentration range of 0.1-76mmolL -1 (R 2 =0.9985) and a detection limit was 0.025mmolL -1 . The GR/PD/GOx electrode demonstrated good reproducibility and repeatability with the relative standard deviation of 6.2% and 1.8% (at 4.0mmolL -1 of glucose), respectively, high anti-interference ability to uric and ascorbic acids. It was highly selective to glucose and demonstrated good accuracy in the analysis of human serum samples. Copyright © 2017 Elsevier B.V. All rights reserved.

Biochemical and cytochemical evaluation of heterozygote individuals with glucose-6-phosphate dehydrogenase deficiency

NARCIS (Netherlands)

Gurbuz, Nilgun; Aksu, Tevfik Aslan; van Noorden, Cornelis J. F.

2005-01-01

The aim of this study was to diagnose heterozygous glucose-6-phosphate dehydrogenase (G6PD) deficient females by an inexpensive cytochemical G6PD staining method that is easy to perform, allowing diagnosis of G6PD deficiency without cumbersome genetic analysis. Three subject groups were included in

Phosphate solubilization and acid phosphatase activity of Serratia sp. isolated from mangrove soil of Mahanadi river delta, Odisha, India

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B.C. Behera

2017-06-01

Full Text Available Phosphorus is an essential element for all life forms. Phosphate solubilizing bacteria are capable of converting phosphate into a bioavailable form through solubilization and mineralization processes. Hence in the present study a phosphate solubilizing bacterium, PSB-37, was isolated from mangrove soil of the Mahanadi river delta using NBRIP-agar and NBRIP-BPB broth containing tricalcium phosphate as the phosphate source. Based on phenotypic and molecular characterization, the strain was identified as Serratia sp. The maximum phosphate solubilizing activity of the strain was determined to be 44.84 μg/ml, accompanied by a decrease in pH of the growth medium from 7.0 to 3.15. During phosphate solubilization, various organic acids, such as malic acid (237 mg/l, lactic acid (599.5 mg/l and acetic acid (5.0 mg/l were also detected in the broth culture through HPLC analysis. Acid phosphatase activity was determined by performing p-nitrophenyl phosphate assay (pNPP of the bacterial broth culture. Optimum acid phosphatase activity was observed at 48 h of incubation (76.808 U/ml, temperature of 45 °C (77.87 U/ml, an agitation rate of 100 rpm (80.40 U/ml, pH 5.0 (80.66 U/ml and with glucose as a original carbon source (80.6 U/ml and ammonium sulphate as a original nitrogen source (80.92 U/ml. Characterization of the partially purified acid phosphatase showed maximum activity at pH 5.0 (85.6 U/ml, temperature of 45 °C (97.87 U/ml and substrate concentration of 2.5 mg/ml (92.7 U/ml. Hence the present phosphate solubilizing and acid phosphatase production activity of the bacterium may have probable use for future industrial, agricultural and biotechnological application.

Labelling of the pineal gland with 99mTc-glucose-6-phosphate

International Nuclear Information System (INIS)

Ribeiro, M.J.; Santos, A.C.; De Lima, J.J.P.

1998-01-01

Lately, the pineal body has been the subject of a large variety of studies. Only recently it has been understood the role played by this endocrine gland to maintain the balance of the human body and also in animal models. Although small in dimensions, the pineal body is a very active organ, able to transmit precise temporal information. It probably participates in the synchronization of several organic functions. The present work aims to study a possible use of 99m Tc-glucose-6-P as a tracer for the pineal gland. Histoautoradiographic studies have been performed in Wistar rats. Tomoscintigraphic studies were acquired in patients and in albine rabbits (oryctolagus cuniculus hyplus). The labelling efficiency and the radiochemical purity of the labelled products have always been tested. Animal and human SPECT exams, show an activity focus projected over the area corresponding to the pineal body localization. Autoradiographic studies using [1- 14 C]-glucose-6-P did not reveal a more relevant activity at the pineal level, probably due to its hepatic conversion to 14 C-glucose. (author)

Characterization and site-directed mutagenesis of Wzb, an O-phosphatase from Lactobacillus rhamnosus

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Gilbert Christophe

2008-04-01

Full Text Available Abstract Background Reversible phosphorylation events within a polymerisation complex have been proposed to modulate capsular polysaccharide synthesis in Streptococcus pneumoniae. Similar phosphatase and kinase genes are present in the exopolysaccharide (EPS biosynthesis loci of numerous lactic acid bacteria genomes. Results The protein sequence deduced from the wzb gene in Lactobacillus rhamnosus ATCC 9595 reveals four motifs of the polymerase and histidinol phosphatase (PHP superfamily of prokaryotic O-phosphatases. Native and modified His-tag fusion Wzb proteins were purified from Escherichia coli cultures. Extracts showed phosphatase activity towards tyrosine-containing peptides. The purified fusion protein Wzb was active on p-nitrophenyl-phosphate (pNPP, with an optimal activity in presence of bovine serum albumin (BSA 1% at pH 7.3 and a temperature of 75°C. At 50°C, residual activity decreased to 10 %. Copper ions were essential for phosphatase activity, which was significantly increased by addition of cobalt. Mutated fusion Wzb proteins exhibited reduced phosphatase activity on p-nitrophenyl-phosphate. However, one variant (C6S showed close to 20% increase in phosphatase activity. Conclusion These characteristics reveal significant differences with the manganese-dependent CpsB protein tyrosine phosphatase described for Streptococcus pneumoniae as well as with the polysaccharide-related phosphatases of Gram negative bacteria.

Glucose-6-phosphate dehydrogenase activity decreases during storage of leukoreduced red blood cells

NARCIS (Netherlands)

Peters, Anna L.; van Bruggen, Robin; de Korte, Dirk; van Noorden, Cornelis J. F.; Vlaar, Alexander P. J.

2016-01-01

During storage, the activity of the red blood cell (RBC) antioxidant system decreases. Glucose-6-phosphate dehydrogenase (G6PD) is essential for protection against oxidative stress by producing NADPH. G6PD function of RBC transfusion products is reported to remain stable during storage, but activity

The Effects of Fenarimol and Methyl Parathion on Glucose 6-Phosphate Dehydrogenase Enzyme Activity in Rats

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Ferda ARI

2017-10-01

Full Text Available Fenarimol and methyl parathion are pesticides that have been used in agriculture for several years. These pesticides have significant effects on environmental and human health. Therefore, we investigated the effects of methyl parathion and fenarimol on glucose 6-phosphate dehydrogenase (EC 1.1.1.49 enzyme activity in rats. The glucose 6- phosphate dehydrogenase is the first enzyme of the pentose phosphate pathway and it is important in detoxifying reactions by NADPH generated. In this study, wistar albino rats administrated with methyl parathion (7 mg kg–1 and fenarimol (200 mg kg−1 by intraperitoneally for different periods (2, 4, 8, 16, 32, 64, and 72 h. The glucose 6-phosphate dehydrogenase enzyme activity was assayed in liver, kidney, brain, and small intestine in male and female rats. The exposure of fenarimol and methyl parathion caused increase of glucose 6-phosphate dehydrogenase enzyme activity in rat tissues, especially at last periods. We suggest that this increment of enzyme activity may be the reason of toxic effects of fenarimol and methyl parathion.

40 CFR 721.2076 - D-Glucuronic acid, polymer with 6-deoxy-L-mannose and D-glucose, acetate, calcium magnesium...

Science.gov (United States)

2010-07-01

...-deoxy-L-mannose and D-glucose, acetate, calcium magnesium potassium sodium salt. 721.2076 Section 721...-Glucuronic acid, polymer with 6-deoxy-L-mannose and D-glucose, acetate, calcium magnesium potassium sodium... identified as D-Glucuronic acid, polymer with 6-deoxy-L-mannose and D-glucose, acetate, calcium magnesium...

Changes in enzyme activity and functional diversity in soil induced by Cd and glucose addition

Science.gov (United States)

Gilmullina, A. R.; Galitskaya, P. Yu; Selivanovskaya, S. Yu

2018-01-01

Toxic heavy metal (HM) contamination is a major global issue as it may have an indirect effect on the health of soil, plants, animals and, consequently, on human health. Agricultural soils’ fertilization is one of the reported sources of HM pollution in the world. In this case simultaneous input of stimulating and inhibiting agents into soil takes place, and effects of the combined influence of these agents is hardly predictable. In this study, a simultaneous inhibiting and stimulating effect of Cd and glucose on soil microbes was studied in a model experiment. Enzyme activities (phosphatase, β-glucosidase and cellobiohydrolase) and functional diversity (BIOLOG®EcoPlates ™) were assessed as a test functions. Cd (300 μg Cd g-1 ) amendment had a negative effect only on phosphatase activity. Glucose (3 mg C g-1) addition inhibited β-glucosidase activity and stimulated functional diversity. In joint addition of Cd and Glucose the leading effect belonged to that agent which had the greatest effect in case when it was added separately.

Icterícia neonatal e deficiência de glicose-6-fosfato desidrogenase Neonatal jaundice and glucose-6-phosphate dehydrogenase

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Amauri Antiquera Leite

2010-01-01

Full Text Available A deficiência de glicose-6-fosfato desidrogenase em neonatos pode ser a responsável pela icterícia neonatal. Este comentário científico é decorrente do relato sobre o tema publicado neste fascículo e que preocupa diversos autores de outros países em relação às complicações em neonatos de hiperbilirrubinemia, existindo inclusive proposições de alguns autores em incluir o teste para identificar a deficiência de glicose-6-fosfato desidrogenase nos recém-nascidos.Glucose-6-phosphate dehydrogenase in newborn babies may be responsible for neonatal jaundice. There is a concern of many authors from other countries in respect to complications in neonates with hyperbilirubinemia; some authors even propose screening for glucose-6-phosphate dehydrogenase deficiency in newborn babies. A scientific report on this subject is published in this issue.

Increased response to insulin of glucose metabolism in the 6-day unloaded rat soleus muscle

Science.gov (United States)

Henriksen, Erik J.; Tischler, Marc E.; Johnson, David G.

1986-01-01

Hind leg muscles of female rats were unloaded by tail cast suspension for 6 days. In the fresh-frozen unloaded soleus, the significantly greater concentration of glycogen correlated with a lower activity ratio of glycogen phosphorylase (p less than 0.02). The activity ratio of glycogen synthase also was lower (p less than 0.001), possibly due to the higher concentration of glycogen. In isolated unloaded soleus, insulin (0.1 milliunit/ml) increased the oxidation of D(U-C-14) glucose, release of lactate and pyruvate, incorporation of D-(U-C-14) glucose into glycogen, and the concentration of glucose 6-phosphate more (p less than 0.05) than in the weight-bearing soleus. At physiological doses of insulin, the percent of maximal uptake of 2-deoxy-D-(1,2-H-3) glucose/muscle also was greater in the unloaded soleus. Unloading of the soleus increased, by 50 percent the concentration of insuling receptors, due to no decrease in total receptor number during muscle atrophy. This increase may account for the greater response of glucose metabolism to insulin in this muscle. The extensor digitorum longus, which generally shows little response to unloading, displayed no differential response of glucose metabolism to insulin.

Phosphatases in Cancer : Shifting the balance

NARCIS (Netherlands)

E. Hoekstra (Elmer)

2015-01-01

markdownabstractAbstract The role of phosphatases in cancer is an ignored research field, mostly based on the dogma that phosphatases function as tumor suppressor genes. However, in our opinion dephosphorylation events by phosphatases can also enhance signaling in cancer. The current research

Erythrocyte glucose-6-phosphate dehydrogenase from Brazilian opossum Didelphis marsupialis

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Barretto O.C. de O.

2006-01-01

Full Text Available In a comparative study of erythrocyte metabolism of vertebrates, the specific activity of glucose-6-phosphate dehydrogenase (G6PD of the Brazilian opossum Didelphis marsupialis in a hemolysate was shown to be high, 207 ± 38 IU g-1 Hb-1 min-1 at 37ºC, compared to the human erythrocyte activity of 12 ± 2 IU g-1 Hb-1 min-1 at 37ºC. The apparent high specific activity of the mixture led us to investigate the physicochemical properties of the opossum enzyme. We report that reduced glutathione (GSH in the erythrocytes was only 50% higher than in human erythrocytes, a value lower than expected from the high G6PD activity since GSH is maintained in a reduced state by G6PD activity. The molecular mass, determined by G-200 Sephadex column chromatography at pH 8.0, was 265 kDa, which is essentially the same as that of human G6PD (260 kDa. The Michaelis-Menten constants (Km: 55 µM for glucose-6-phosphate and nicotinamide adenine dinucleotide phosphate (Km: 3.3 µM were similar to those of the human enzyme (Km: 50-70 and Km: 2.9-4.4, respectively. A 450-fold purification of the opossum enzyme was achieved and the specific activity of the purified enzyme, 90 IU/mg protein, was actually lower than the 150 IU/mg protein observed for human G6PD. We conclude that G6PD after purification from the hemolysate of D. marsupialis does not have a high specific activity. Thus, it is quite probable that the red cell hyperactivity reported may be explained by increased synthesis of G6PD molecules per unit of hemoglobin or to reduced inactivation in the RBC hemolysate.

Detection of endogenous alkaline phosphatase activity in intact cells by flow cytometry using the fluorogenic ELF-97 phosphatase substrate

Science.gov (United States)

Telford, W. G.; Cox, W. G.; Stiner, D.; Singer, V. L.; Doty, S. B.

1999-01-01

BACKGROUND: The alkaline phosphatase (AP) substrate 2-(5'-chloro-2'-phosphoryloxyphenyl)-6-chloro-4-(3H)-quinazolinone (ELF((R))-97 for enzyme-labeled fluorescence) has been found useful for the histochemical detection of endogenous AP activity and AP-tagged proteins and oligonucleotide probes. In this study, we evaluated its effectiveness at detecting endogenous AP activity by flow cytometry. METHODS: The ELF-97 phosphatase substrate was used to detect endogenous AP activity in UMR-106 rat osteosarcoma cells and primary cultures of chick chondrocytes. Cells were labeled with the ELF-97 reagent and analyzed by flow cytometry using an argon ultraviolet (UV) laser. For comparison purposes, cells were also assayed for AP using a Fast Red Violet LB azo dye assay previously described for use in detecting AP activity by flow cytometry. RESULTS: The ELF-97 phosphatase substrate effectively detected endogenous AP activity in UMR-106 cells, with over 95% of the resulting fluorescent signal resulting from AP-specific activity (as determined by levamisole inhibition of AP activity). In contrast, less than 70% of the fluorescent signal from the Fast Red Violet LB (FRV) assay was AP-dependent, reflecting the high intrinsic fluorescence of the unreacted components. The ELF-97 phosphatase assay was also able to detect very low AP activity in chick chondrocytes that was undetectable by the azo dye method. CONCLUSIONS: The ELF-97 phosphatase assay was able to detect endogenous AP activity in fixed mammalian and avian cells by flow cytometry with superior sensitivity to previously described assays. This work also shows the applicability of ELF-97 to flow cytometry, supplementing its previously demonstrated histochemical applications. Copyright 1999 Wiley-Liss, Inc.

Evidence for a role of proline and hypothalamic astrocytes in the regulation of glucose metabolism in rats.

Science.gov (United States)

Arrieta-Cruz, Isabel; Su, Ya; Knight, Colette M; Lam, Tony K T; Gutiérrez-Juárez, Roger

2013-04-01

The metabolism of lactate to pyruvate in the mediobasal hypothalamus (MBH) regulates hepatic glucose production. Because astrocytes and neurons are functionally linked by metabolic coupling through lactate transfer via the astrocyte-neuron lactate shuttle (ANLS), we reasoned that astrocytes might be involved in the hypothalamic regulation of glucose metabolism. To examine this possibility, we used the gluconeogenic amino acid proline, which is metabolized to pyruvate in astrocytes. Our results showed that increasing the availability of proline in rats either centrally (MBH) or systemically acutely lowered blood glucose. Pancreatic clamp studies revealed that this hypoglycemic effect was due to a decrease of hepatic glucose production secondary to an inhibition of glycogenolysis, gluconeogenesis, and glucose-6-phosphatase flux. The effect of proline was mimicked by glutamate, an intermediary of proline metabolism. Interestingly, proline's action was markedly blunted by pharmacological inhibition of hypothalamic lactate dehydrogenase (LDH) suggesting that metabolic flux through LDH was required. Furthermore, short hairpin RNA-mediated knockdown of hypothalamic LDH-A, an astrocytic component of the ANLS, also blunted the glucoregulatory action of proline. Thus our studies suggest not only a new role for proline in the regulation of hepatic glucose production but also indicate that hypothalamic astrocytes are involved in the regulatory mechanism as well.

Detection of phosphatase activity in aquatic and terrestrial cyanobacterial strains

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Babić Olivera B.

2013-01-01

Full Text Available Cyanobacteria, as highly adaptable microorganisms, are characterized by an ability to survive in different environmental conditions, in which a significant role belongs to their enzymes. Phosphatases are enzymes produced by algae in relatively large quantities in response to a low orthophosphate concentration and their activity is significantly correlated with their primary production. The activity of these enzymes was investigated in 11 cyanobacterial strains in order to determine enzyme synthesis depending on taxonomic and ecological group of cyanobacteria. The study was conducted with 4 terrestrial cyanobacterial strains, which belong to Nostoc and Anabaena genera, and 7 filamentous water cyanobacteria of Nostoc, Oscillatoria, Phormidium and Microcystis genera. The obtained results showed that the activity of acid and alkaline phosphatases strongly depended on cyanobacterial strain and the environment from which the strain originated. Higher activity of alkaline phosphatases, ranging from 3.64 to 85.14 μmolpNP/s/dm3, was recorded in terrestrial strains compared to the studied water strains (1.11-5.96 μmolpNP/s/dm3. The activity of acid phosphatases was higher in most tested water strains (1.67-6.28 μmolpNP/s/dm3 compared to the activity of alkaline phosphatases (1.11-5.96 μmolpNP/s/dm3. Comparing enzyme activity of nitrogen fixing and non-nitrogen fixing cyanobacteria, it was found that most nitrogen fixing strains had a higher activity of alkaline phosphatases. The data obtained in this work indicate that activity of phosphatases is a strain specific property. The results further suggest that synthesis and activity of phosphatases depended on eco-physiological characteristics of the examined cyanobacterial strains. This can be of great importance for the further study of enzymes and mechanisms of their activity as a part of cyanobacterial survival strategy in environments with extreme conditions. [Projekat Ministarstva nauke Republike

Association of Genetic Loci With Glucose Levels in Childhood and Adolescence A Meta-Analysis of Over 6,000 Children

DEFF Research Database (Denmark)

Barker, A.; Sharp, S. J.; Timpson, N. J.

2011-01-01

with fasting glucose were genotyped in six studies of children and adolescents of European origin, including over 6,000 boys and girls aged 9-16 years. We performed meta-analyses to test associations of individual SNPs and a weighted risk score of the 16 loci with fasting glucose. RESULTS-Nine loci were...... glucose loci. Children and adolescents carrying glucose-raising alleles of G6PC2, MTNR1B, GCK, and GLIS3 also showed reduced p-cell function, as indicated by homeostasis model assessment of beta-cell function. Analysis using a weighted risk score showed an increase [beta (95% CI)] in fasting glucose level....... In nondiabetic adults, fasting glucose changes little over time, and our results suggest that age-independent effects of fasting glucose loci contribute to long-term interindividual differences in glucose levels from childhood onwards. Diabetes 60:1805-1812, 2011...

A high-performance liquid chromatography-based radiometric assay for sucrose-phosphate synthase and other UDP-glucose requiring enzymes

International Nuclear Information System (INIS)

Salvucci, M.E.; Crafts-Brandner, S.J.

1991-01-01

A method for product analysis that eliminates a problematic step in the radiometric sucrose-phosphate synthase assay is described. The method uses chromatography on a boronate-derivatized high-performance liquid chromatography column to separate the labeled product, [14C]sucrose phosphate, from unreacted uridine 5'-diphosphate-[14C]glucose (UDP-Glc). Direct separation of these compounds eliminates the need for treatment of the reaction mixtures with alkaline phosphatase, thereby avoiding the problem of high background caused by contaminating phosphodiesterase activity in alkaline phosphatase preparations. The method presented in this paper can be applied to many UDP-Glc requiring enzymes; here the authors show its use for determining the activities of sucrose-phosphate synthase, sucrose synthase, and uridine diphosphate-glucose pyrophosphorylase in plant extracts

Continuous glucose monitoring, oral glucose tolerance, and insulin - glucose parameters in adolescents with simple obesity.

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El Awwa, A; Soliman, A; Al-Ali, M; Yassin, M; De Sanctis, V

2012-09-01

In obese adolescents pancreatic beta-cells may not be able to cope with insulin resistance leading to hyperglycemia and type2 diabetes (T2DM To assess oral glucose tolerance, 72-h continuous blood glucose concentrations (CGM) and calculate homeostatic model assessment (HOMA), and the quantitative insulin sensitivity check index (QUICKI) in 13 adolescents with simple obesity (BMI SDS=4 ± 1.06). OGTT performed in 13 obese adolescents (13.47 ± 3 years) revealed 3 cases (23%) with impaired fasting glucose (IFG: fasting glucose >5.6 mmol/L), 4 cases (30%) with impaired glucose tolerance (IGT: 2h blood glucose >7.8 continuous glucose monitoring system ( CGMS), IFG was detected in 4 cases, the maximum serum blood glucose (BG : 2h or more after meal) was >7.8 and 11.1 mmol/L (diabetes) in one case (7.6%). Five cases had a minimum BG recorded of 2.6 and QUICKI values obese adolescents, CGMS is superior to OGTT and HbA1C in detecting glycemic abnormalities, which appears to be secondary to insulin resistance.

Glycogen storage disease type Ia: linkage of glucose, glycogen, lactic acid, triglyceride, and uric acid metabolism.

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Sever, Sakine; Weinstein, David A; Wolfsdorf, Joseph I; Gedik, Reyhan; Schaefer, Ernst J

2012-01-01

A female presented in infancy with hypotonia, undetectable serum glucose, lactic acidosis, and triglycerides >5000 mg/dL. The diagnosis of type 1A glycogen storage disease was made via the result of a liver biopsy, which showed increased glycogen and absent glucose-6-phosphatase enzyme activity. The patient was treated with dextrose administered orally, which was replaced by frequent feedings of cornstarch, which resulted in an improvement of her metabolic parameters. At age 18 years of age, she had marked hypertriglyceridemia (3860 mg/dL) and eruptive xanthomas and was treated with fenofibrate, atorvastatin, and fish oil. At age 29 years she was noted to have multiple liver adenomas, severe anemia, and hyperuricemia. Aggressive cornstarch therapy was commenced with a goal of maintaining her blood glucose levels >75 mg/dL and lactate levels triglycerides 179, high-density lipoprotein cholesterol 32, and calculated low-density lipoprotein cholesterol 154. Her weight was stable with a body mass index of 24.8 kg/m(2). Her liver adenomas had decreased in size, and her anemia and hyperuricemia had improved. She was homozygous for the R83C missense mutation in G6PC. Our data indicate that optimized metabolic control to maintain blood glucose levels >75 mg/dL is critical in the management of this disease. Copyright © 2012. Published by Elsevier Inc.

Adsorption and possible dissociation of glucose by the [BN fullerene-B6]- magnetic nanocomposite. In silico studies

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Anota, E. Chigo; Villanueva, M. Salazar; Shakerzadeh, E.; Castro, M.

2018-02-01

The adsorption, activation and possible dissociation of the glucose molecule on the magnetic [BN fullerene-B6]- system is performed by means of density functional theory calculations. Three models of magnetic nanocomposites were inspected: i) pristine BN fullerene, BN fullerene functionalized with a magnetic B6 cluster which generates two structures: ii) pyramidal (P) and iii) triangular (T). Chemical interactions of glucose appear for all these cases; however, for the BNF:B6(T)—glucose system, the interaction generates an effect of dissociation on glucose, due to the magnetic effects, since it has high spin multiplicity. The latter nanocomposite shows electronic behavior like-conductor and like-semi-conductor for the P and T geometries, respectively. Intrinsic magnetism associated to values of 1.0 magneton bohr (µB) for the pyramidal and 5.0 µB for the triangular structure, high polarity, and low-chemical reactivity are found for these systems. These interesting properties make these functionalized fullerenes a good option for being used as nano-vehicles for drug delivery. These quantum descriptors remain invariant when the [BN]-fullerene and [BNF:B6 (P) or (T)]- nanocomposites are interacting with the glucose molecule. According to the determined adsorption energy, chemisorption regimes occur in both the phases: gas and aqueous medium.

Glucose metabolite glyoxal induces senescence in telomerase-immortalized human mesenchymal stem cells

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Larsen, Simon Asbjørn; Kassem, Moustapha; Rattan, Suresh

2012-01-01

). Furthermore, the in vitro differentiation potential of hMSC-TERT to become functional osteoblasts was highly reduced in GO-treated stem cells, as determined by alkaline phosphatase (ALP) activity and mineralized matrix (MM) formation. Conclusions The results of our study imply that an imbalanced glucose...... physiological metabolite produced by the auto-oxidation of glucose, and can form covalent adducts known as advanced glycation endproducts (AGE). We have previously reported that GO accelerates ageing and causes premature senescence in normal human skin fibroblasts. Results Using a bone marrow-derived telomerase...

HD-PTP is a catalytically inactive tyrosine phosphatase due to a conserved divergence in its phosphatase domain.

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Marie-Claude Gingras

Full Text Available The HD-PTP protein has been described as a tumor suppressor candidate and based on its amino acid sequence, categorized as a classical non-transmembrane protein tyrosine phosphatase (PTP. To date, no HD-PTP phosphorylated substrate has been identified and controversial results concerning its catalytic activity have been recently reported.Here we report a rigorous enzymatic analysis demonstrating that the HD-PTP protein does not harbor tyrosine phosphatase or lipid phosphatase activity using the highly sensitive DiFMUP substrate and a panel of different phosphatidylinositol phosphates. We found that HD-PTP tyrosine phosphatase inactivity is caused by an evolutionary conserved amino acid divergence of a key residue located in the HD-PTP phosphatase domain since its back mutation is sufficient to restore the HD-PTP tyrosine phosphatase activity. Moreover, in agreement with a tumor suppressor activity, HD-PTP expression leads to colony growth reduction in human cancer cell lines, independently of its catalytic PTP activity status.In summary, we demonstrate that HD-PTP is a catalytically inactive protein tyrosine phosphatase. As such, we identify one residue involved in its inactivation and show that its colony growth reduction activity is independent of its PTP activity status in human cancer cell lines.

Measuring brain glucose phosphorylation with labeled glucose

International Nuclear Information System (INIS)

Brondsted, H.E.; Gjedde, A.

1988-01-01

This study tested whether glucose labeled at the C-6 position generates metabolites that leave brain so rapidly that C-6-labeled glucose cannot be used to measure brain glucose phosphorylation (CMRGlc). In pentobarbital-anesthetized rats, the parietal cortex uptake of [ 14 C]glucose labeled in the C-6 position was followed for times ranging from 10 s to 60 min. We subtracted the observed radioactivity from the radioactivity expected with no loss of labeled metabolites from brain by extrapolation of glucose uptake in an initial period when loss was negligible. The observed radioactivity was a monoexponentially declining function of the total radioactivity expected in the absence of metabolite loss. The constant of decline was 0.0077.min-1 for parietal cortex. Metabolites were lost from the beginning of the experiment. However, with correction for the loss of labeled metabolites, it was possible to determine an average CMRGlc between 4 and 60 min of circulation of 64 +/- 4 (SE; n = 49) mumol.hg-1.min-1

Triiodothyronine Acutely Stimulates Glucose Transport into L6 Muscle Cells Without Increasing Surface GLUT4, GLUT1, or GLUT3

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Teixeira, Silvania Silva; Tamrakar, Akhilesh K.; Goulart-Silva, Francemilson; Serrano-Nascimento, Caroline; Klip, Amira

2012-01-01

Background Thyroid hormones (THs) act genomically to stimulate glucose transport by elevating glucose transporter (Slc2a) expression and glucose utilization by cells. However, nongenomic effects of THs are now emerging. Here, we assess how triiodothyronine (T3) acutely affects glucose transport and the content of GLUT4, GLUT1, and GLUT3 at the surface of muscle cells, and possible interactions between T3 and insulin action. Methods Differentiated L6 myotubes transfected with myc-tagged Slc2a4 (L6-GLUT4myc) or Slc2a1 (L6-GLUT1myc) and wild-type L6 myotubes were studied in the following conditions: control, hypothyroid (Tx), Tx plus T3, Tx plus insulin, and Tx plus insulin and T3. Results Glucose uptake and GLUT4 content at the cell surface decreased in the Tx group relative to controls. T3 treatment for 30 minutes increased glucose transport into L6-GLUT4myc cells without altering surface GLUT4 content, which increased only thereafter. The total amount of GLUT4 protein remained unchanged among the groups studied. The surface GLUT1 content of L6-GLUT1myc cells also remained unaltered after T3 treatment; however, in these cells glucose transport was not stimulated by T3. In wild-type L6 cells, although T3 treatment increased the total amount of GLUT3, it did not change the surface GLUT3 content. Moreover, within 30 minutes, T3 stimulation of glucose uptake was additive to that of insulin in L6-GLUT4myc cells. As expected, insulin elevated surface GLUT4 content and glucose uptake. However, interestingly, surface GLUT4 content remained unchanged or even dropped with T3 plus insulin. Conclusions These data reveal that T3 rapidly increases glucose uptake in L6-GLUT4myc cells, which, at least for 30 minutes, did not depend on an increment in GLUT4 at the cell surface yet potentiates insulin action. We propose that this rapid T3 effect involves activation of GLUT4 transporters at the cell surface, but cannot discount the involvement of an unknown GLUT. PMID:22663547

Development of hepatocellular adenomas and carcinomas in mice with liver-specific G6Pase-α deficiency

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Roberta Resaz

2014-09-01

Full Text Available Glycogen storage disease type 1a (GSD-1a is caused by a deficiency in glucose-6-phosphatase-α (G6Pase-α, and is characterized by impaired glucose homeostasis and a high risk of developing hepatocellular adenomas (HCAs. A globally G6Pase-α-deficient (G6pc−/− mouse model that shows pathological features similar to those of humans with GSD-1a has been developed. These mice show a very severe phenotype of disturbed glucose homeostasis and rarely live beyond weaning. We generated liver-specific G6Pase-α-deficient (LS‑G6pc−/− mice as an alternative animal model for studying the long-term pathophysiology of the liver and the potential treatment strategies, such as cell therapy. LS‑G6pc−/− mice were viable and exhibited normal glucose profiles in the fed state, but showed significantly lower blood glucose levels than their control littermates after 6 hours of fasting. LS‑G6pc−/− mice developed hepatomegaly with glycogen accumulation and hepatic steatosis, and progressive hepatic degeneration. Ninety percent of the mice analyzed developed amyloidosis by 12 months of age. Finally, 25% of the mice sacrificed at age 10–20 months showed the presence of multiple HCAs and in one case late development of hepatocellular carcinoma (HCC. In conclusion, LS‑G6pc−/− mice manifest hepatic symptoms similar to those of human GSD-1a and, therefore, represent a valid model to evaluate long-term liver pathogenesis of GSD-1a.

Genetic interaction network of the Saccharomyces cerevisiae type 1 phosphatase Glc7

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Neszt Michael

2008-07-01

Full Text Available Abstract Background Protein kinases and phosphatases regulate protein phosphorylation, a critical means of modulating protein function, stability and localization. The identification of functional networks for protein phosphatases has been slow due to their redundant nature and the lack of large-scale analyses. We hypothesized that a genome-scale analysis of genetic interactions using the Synthetic Genetic Array could reveal protein phosphatase functional networks. We apply this approach to the conserved type 1 protein phosphatase Glc7, which regulates numerous cellular processes in budding yeast. Results We created a novel glc7 catalytic mutant (glc7-E101Q. Phenotypic analysis indicates that this novel allele exhibits slow growth and defects in glucose metabolism but normal cell cycle progression and chromosome segregation. This suggests that glc7-E101Q is a hypomorphic glc7 mutant. Synthetic Genetic Array analysis of glc7-E101Q revealed a broad network of 245 synthetic sick/lethal interactions reflecting that many processes are required when Glc7 function is compromised such as histone modification, chromosome segregation and cytokinesis, nutrient sensing and DNA damage. In addition, mitochondrial activity and inheritance and lipid metabolism were identified as new processes involved in buffering Glc7 function. An interaction network among 95 genes genetically interacting with GLC7 was constructed by integration of genetic and physical interaction data. The obtained network has a modular architecture, and the interconnection among the modules reflects the cooperation of the processes buffering Glc7 function. Conclusion We found 245 genes required for the normal growth of the glc7-E101Q mutant. Functional grouping of these genes and analysis of their physical and genetic interaction patterns bring new information on Glc7-regulated processes.

Probing protein phosphatase substrate binding

DEFF Research Database (Denmark)

Højlys-Larsen, Kim B.; Sørensen, Kasper Kildegaard; Jensen, Knud Jørgen

2012-01-01

Proteomics and high throughput analysis for systems biology can benefit significantly from solid-phase chemical tools for affinity pull-down of proteins from complex mixtures. Here we report the application of solid-phase synthesis of phosphopeptides for pull-down and analysis of the affinity...... profile of the integrin-linked kinase associated phosphatase (ILKAP), a member of the protein phosphatase 2C (PP2C) family. Phosphatases can potentially dephosphorylate these phosphopeptide substrates but, interestingly, performing the binding studies at 4 °C allowed efficient binding to phosphopeptides......, without the need for phosphopeptide mimics or phosphatase inhibitors. As no proven ILKAP substrates were available, we selected phosphopeptide substrates among known PP2Cδ substrates including the protein kinases: p38, ATM, Chk1, Chk2 and RSK2 and synthesized directly on PEGA solid supports through a BAL...

The Production and Utilization of GDP-glucose in the Biosynthesis of Trehalose 6-Phosphate by Streptomyces venezuelae.

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Asención Diez, Matías D; Miah, Farzana; Stevenson, Clare E M; Lawson, David M; Iglesias, Alberto A; Bornemann, Stephen

2017-01-20

Trehalose-6-phosphate synthase OtsA from streptomycetes is unusual in that it uses GDP-glucose as the donor substrate rather than the more commonly used UDP-glucose. We now confirm that OtsA from Streptomyces venezuelae has such a preference for GDP-glucose and can utilize ADP-glucose to some extent too. A crystal structure of the enzyme shows that it shares twin Rossmann-like domains with the UDP-glucose-specific OtsA from Escherichia coli However, it is structurally more similar to Streptomyces hygroscopicus VldE, a GDP-valienol-dependent pseudoglycosyltransferase enzyme. Comparison of the donor binding sites reveals that the amino acids associated with the binding of diphosphoribose are almost all identical in these three enzymes. By contrast, the amino acids associated with binding guanine in VldE (Asn, Thr, and Val) are similar in S. venezuelae OtsA (Asp, Ser, and Phe, respectively) but not conserved in E. coli OtsA (His, Leu, and Asp, respectively), providing a rationale for the purine base specificity of S. venezuelae OtsA. To establish which donor is used in vivo, we generated an otsA null mutant in S. venezuelae The mutant had a cell density-dependent growth phenotype and accumulated galactose 1-phosphate, glucose 1-phosphate, and GDP-glucose when grown on galactose. To determine how the GDP-glucose is generated, we characterized three candidate GDP-glucose pyrophosphorylases. SVEN_3027 is a UDP-glucose pyrophosphorylase, SVEN_3972 is an unusual ITP-mannose pyrophosphorylase, and SVEN_2781 is a pyrophosphorylase that is capable of generating GDP-glucose as well as GDP-mannose. We have therefore established how S. venezuelae can make and utilize GDP-glucose in the biosynthesis of trehalose 6-phosphate. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

The Production and Utilization of GDP-glucose in the Biosynthesis of Trehalose 6-Phosphate by Streptomyces venezuelae*

Science.gov (United States)

Asención Diez, Matías D.; Miah, Farzana; Stevenson, Clare E. M.; Lawson, David M.; Iglesias, Alberto A.; Bornemann, Stephen

2017-01-01

Trehalose-6-phosphate synthase OtsA from streptomycetes is unusual in that it uses GDP-glucose as the donor substrate rather than the more commonly used UDP-glucose. We now confirm that OtsA from Streptomyces venezuelae has such a preference for GDP-glucose and can utilize ADP-glucose to some extent too. A crystal structure of the enzyme shows that it shares twin Rossmann-like domains with the UDP-glucose-specific OtsA from Escherichia coli. However, it is structurally more similar to Streptomyces hygroscopicus VldE, a GDP-valienol-dependent pseudoglycosyltransferase enzyme. Comparison of the donor binding sites reveals that the amino acids associated with the binding of diphosphoribose are almost all identical in these three enzymes. By contrast, the amino acids associated with binding guanine in VldE (Asn, Thr, and Val) are similar in S. venezuelae OtsA (Asp, Ser, and Phe, respectively) but not conserved in E. coli OtsA (His, Leu, and Asp, respectively), providing a rationale for the purine base specificity of S. venezuelae OtsA. To establish which donor is used in vivo, we generated an otsA null mutant in S. venezuelae. The mutant had a cell density-dependent growth phenotype and accumulated galactose 1-phosphate, glucose 1-phosphate, and GDP-glucose when grown on galactose. To determine how the GDP-glucose is generated, we characterized three candidate GDP-glucose pyrophosphorylases. SVEN_3027 is a UDP-glucose pyrophosphorylase, SVEN_3972 is an unusual ITP-mannose pyrophosphorylase, and SVEN_2781 is a pyrophosphorylase that is capable of generating GDP-glucose as well as GDP-mannose. We have therefore established how S. venezuelae can make and utilize GDP-glucose in the biosynthesis of trehalose 6-phosphate. PMID:27903647

Method of preparing uridine-diphospho-/sup 14/C-D-glucose of high molar activity and radiochemical purity by enzyme synthesis

Energy Technology Data Exchange (ETDEWEB)

Farkas, V; Biely, P; Koelbl, J

1980-06-15

A new method is described of enzyme synthesis of uridine-diphospho-/sup 14/C-D-glucose of high molar activity. After conversion of the initial /sup 14/C-D-glucose, the accompanying sugar phosphates and nucleoside-5'-phosphates are selectively hydrolyzed by the action of alkaline phosphatase in the presence of phenolphthalein as an indicator. Uridine-diphospho-/sup 14/C-D-glucose is separated by paper chromatography from the reaction mixture thus modified. Synthesis yields range within 75% and 85% relative to the starting /sup 14/C-D-glucose.

Lack of skeletal muscle IL-6 influences hepatic glucose metabolism in mice during prolonged exercise

DEFF Research Database (Denmark)

Bertholdt, Lærke; Gudiksen, Anders; Schwartz, Camilla Lindgren

2017-01-01

The liver is essential in maintaining and regulating glucose homeostasis during prolonged exercise. IL-6 has been shown to be secreted from skeletal muscle during exercise and has been suggested to signal to the liver. Therefore, the aim of this study was to investigate the role of skeletal muscle...... IL-6 on hepatic glucose regulation and substrate choice during prolonged exercise. Skeletal muscle-specific IL-6 knockout (IL-6 MKO) mice (age, 12-14 wk) and littermate lox/lox (Control) mice were either rested (Rest) or completed a single bout of exercise for 10, 60, or 120 min, and the liver....... Furthermore, IL-6 MKO mice had higher hepatic pyruvate dehydrogenase (PDH)Ser232 and PDHSer300 phosphorylation than control mice at rest. In conclusion, hepatic gluconeogenic capacity in mice is increased during prolonged exercise independent of muscle IL-6. Furthermore, Skeletal muscle IL-6 influences...

Voltage-sensing phosphatase: its molecular relationship with PTEN.

Science.gov (United States)

Okamura, Yasushi; Dixon, Jack E

2011-02-01

Voltage-sensing phosphoinositide phosphatase (VSP) contains voltage sensor and cytoplasmic phosphatase domains. A unique feature of this protein is that depolarization-induced motions of the voltage sensor activate PtdIns(3,4,5)P(3) and PtdIns(4,5)P(2) phosphatase activities. VSP exhibits remarkable structural similarities with PTEN, the phosphatase and tensin homolog deleted on chromosome 10. These similarities include the cytoplasmic phosphatase region, the phosphoinositide binding region, and the putative membrane interacting C2 domain.

Phosphate-solubility and phosphatase activity in Gangetic alluvial soil as influenced by organophosphate insecticide residues.

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Majumder, Shyam Prasad; Das, Amal Chandra

2016-04-01

An experiment was conducted under laboratory conditions to investigate the effect of four organophosphate insecticides, viz. monocrotophos, profenophos, quinalphos and triazophos at their field application rates (0.75, 1.0, 0.5 and 0.6 kg a.i.ha(-1), respectively), on the growth and activities of phosphate solubilizing microorganisms in relation to availability of insoluble phosphates in the Gangetic alluvial soil of West Bengal, India. The proliferation of phosphate solubilizing microorganisms was highly induced with profenophos (38.3%), while monocrotophos exerted maximum stimulation (20.8%) towards the solubility of insoluble phosphates in soil. The phosphatase activities of the soil (both acid phosphatase and alkaline phosphatase) were significantly increased due to the incorporation of the insecticides in general, and the augmentation was more pronounced with quinalphos (43.1%) followed by profenophos (27.6%) for acid phosphatase, and with monocrotophos (25.2%) followed by profenophos (16.1%) for alkaline phosphatase activity in soil. The total phosphorus was highly retained by triazophos (19.9%) followed by monocrotophos (16.5%), while incorporation of triazophos and quinalphos manifested greater availability of water soluble phosphorus in soil. Copyright © 2015 Elsevier Inc. All rights reserved.

Electrochemical biosensor based on glucose oxidase encapsulated within enzymatically synthesized poly(1,10-phenanthroline-5,6-dione).

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Ciftci, Hakan; Oztekin, Yasemin; Tamer, Ugur; Ramanaviciene, Almira; Ramanavicius, Arunas

2014-11-01

This study is focused on the investigation of electrocatalytic effect of glucose oxidase (GOx) immobilized on the graphite rod (GR) electrode. The enzyme modified electrode was prepared by encapsulation of immobilized GOx within enzymatically formed poly(1,10-phenanthroline-5,6-dione) (pPD) film. The electrochemical responses of such enzymatic electrode (pPD/GOx/GR) vs. different glucose concentrations were examined chronoamperometrically in acetate-phosphate buffer solution (A-PBS), pH 6.0, under aerobic or anaerobic conditions. Amperometric signals of the pPD/GOx/GR electrode exhibited well-defined hyperbolic dependence upon glucose concentration. Amperometric signals at 100mM of glucose were 41.17 and 32.27 μA under aerobic and anaerobic conditions, respectively. Amperometric signals of the pPD/GOx/GR electrode decreased by 6% within seven days. The pPD/GOx/GR electrode showed excellent selectivity in the presence of dopamine and uric acid. Furthermore it had a good reproducibility and repeatability with standard deviation of 9.4% and 8.0%, respectively. Copyright © 2014 Elsevier B.V. All rights reserved.

An extract of Urtica dioica L. mitigates obesity induced insulin resistance in mice skeletal muscle via protein phosphatase 2A (PP2A).

Science.gov (United States)

Obanda, Diana N; Ribnicky, David; Yu, Yongmei; Stephens, Jacqueline; Cefalu, William T

2016-02-26

The leaf extract of Urtica dioica L. (UT) has been reported to improve glucose homeostasis in vivo, but definitive studies on efficacy and mechanism of action are lacking. We investigated the effects of UT on obesity- induced insulin resistance in skeletal muscle. Male C57BL/6J mice were divided into three groups: low-fat diet (LFD), high-fat diet (HFD) and HFD supplemented with UT. Body weight, body composition, plasma glucose and plasma insulin were monitored. Skeletal muscle (gastrocnemius) was analyzed for insulin sensitivity, ceramide accumulation and the post translational modification and activity of protein phosphatase 2A (PP2A). PP2A is activated by ceramides and dephosphorylates Akt. C2C12 myotubes exposed to excess free fatty acids with or without UT were also evaluated for insulin signaling and modulation of PP2A. The HFD induced insulin resistance, increased fasting plasma glucose, enhanced ceramide accumulation and PP2A activity in skeletal muscle. Supplementation with UT improved plasma glucose homeostasis and enhanced skeletal muscle insulin sensitivity without affecting body weight and body composition. In myotubes, UT attenuated the ability of FFAs to induce insulin resistance and PP2A hyperactivity without affecting ceramide accumulation and PP2A expression. UT decreased PP2A activity through posttranslational modification that was accompanied by a reduction in Akt dephosphorylation.

GABA dramatically improves glucose tolerance in streptozotocin-induced diabetic rats fed with high-fat diet.

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Sohrabipour, Shahla; Sharifi, Mohammad Reza; Talebi, Ardeshir; Sharifi, Mohammadreza; Soltani, Nepton

2018-05-05

Skeletal muscle, hepatic insulin resistance, and beta cell dysfunction are the characteristic pathophysiological features of type 2 diabetes mellitus. GABA has an important role in pancreatic islet cells. The present study attempted to clarify the possible mechanism of GABA to improve glucose tolerance in a model of type 2 diabetes mellitus in rats. Fifty Wistar rats were divided into five groups: NDC that was fed the normal diet, CD which received a high-fat diet with streptozotocin, CD-GABA animals that received GABA via intraperitoneal injection, plus CD-Ins1 and CD-Ins2 groups which were treated with low and high doses of insulin, respectively. Body weight and blood glucose were measured weekly. Intraperitoneal glucose tolerance test (IPGTT), insulin tolerance test (ITT), urine volume, amount of water drinking, and food intake assessments were performed monthly. The hyperinsulinemic euglycemic clamp was done for assessing insulin resistance. Plasma insulin and glucagon were measured. Abdominal fat was measured. Glucagon receptor, Glucose 6 phosphatase, Phosphoenolpyruvate carboxykinase genes expression were evaluated in liver and Glucose transporter 4 (GLUT4) genes expression and protein translocation were evaluated in the muscle. GABA or insulin therapy improved blood glucose, insulin level, IPGTT, ITT, gluconeogenesis pathway, Glucagon receptor, body weight and body fat in diabetic rats. GLUT4 gene and protein expression increased. GABA whose beneficial effect was comparable to that of insulin, also increased glucose infusion rate during an euglycemic clamp. GABA could improve insulin resistance via rising GLUT4 and also decreasing the gluconeogenesis pathway and Glucagon receptor gene expression. Copyright © 2018. Published by Elsevier B.V.

Identification of Mutation of Glucose-6-Phosphate Dehy-drogenase (G6PD) in Iran: Meta- analysis Study.

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Moosazadeh, Mahmood; Nekoei-Moghadam, Mahmood; Aliram-Zany, Maryam; Amiresmaili, Mohammadreza

2013-09-01

Glucose-6-phosphate dehydrogenase is one of the most common genetic deficiencies, which approximately 400 million people in the world suffer from. According to authors' initial search, numerous studies have been carried out in Iran regarding molecular variants of this enzyme. Thus, this meta-analysis presented a reliable estimation about prevalence of different types of molecular mutations of G6PD Enzyme in Iran. Keywords "glucose 6 phosphate dehydrogenase or G6PD, Mediterranean or Chatham or Cosenza and mutation, Iran or Iranian and their Persian equivalents" were searched in different databases. Moreover, reference list of the published studies were examined to increase sensitivity and to select more studies. After studying titles and abstracts of retrieved articles, excluding the repeated and unrelated ones, and evaluating quality of articles, documents were selected. Data was analyzed using STATA. After performing systematic review, 22 papers were entered this meta-analysis and 1698 subjects were examined concerning G6PD molecular mutation. In this meta-analysis, prevalence of Mediterranean mutation, Chatham mutation and Cosenza mutation in Iran was estimated 78.2%, 9.1% and 0.5% respectively. This meta-analysis showed that in spite of prevalence of different types of G6PD molecular mutations in center, north, north-west and west of Iran, the most common molecular mutations in people with G6PD deficiency in Iran, like other Mediterranean countries and countries around Persian Gulf, were Mediterranean mutation, Chatham mutation and Cosenza mutation. It is also recommended that future studies may focus on races and regions which haven't been taken into consideration up to now.

CAST/EiJ and C57BL/6J Mice Differ in Their Oral and Postoral Attraction to Glucose and Fructose.

Science.gov (United States)

Sclafani, Anthony; Vural, Austin S; Ackroff, Karen

2017-03-01

A recent study indicated that CAST/EiJ and C57BL/6J mice differ in their taste preferences for maltodextrin but display similar sucrose preferences. The present study revealed strain differences in preferences for the constituent sugars of sucrose. Whereas B6 mice preferred 8% glucose to 8% fructose in 2-day tests, the CAST mice preferred fructose to glucose. These preferences emerged with repeated testing which suggested post-oral influences. In a second experiment, 2-day choice tests were conducted with the sugars versus a sucralose + saccharin (SS) mixture which is highly preferred in brief access tests. B6 mice strongly preferred glucose but not fructose to the non-nutritive SS whereas CAST mice preferred SS to both glucose and fructose even when food restricted. This implied that CAST mice are insensitive to the postoral appetite stimulating actions of the 2 sugars. A third experiment revealed, however, that intragastric glucose and fructose infusions conditioned significant but mild flavor preferences in CAST mice, whereas in B6 mice glucose conditioned a robust preference but fructose was ineffective. Thus, unlike other mouse strains and rats, glucose is not more reinforcing than fructose in CAST mice. Their oral preference for fructose over glucose may be related to a subsensitive maltodextrin receptor or glucose-specific receptor which is stimulated by glucose but not fructose. The failure of CAST mice to prefer glucose to a non-nutritive sweetener distinguishes this strain from other mouse strains and rats. © The Author 2017. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Dual-specificity phosphatase 6 (Dusp6), a negative regulator of FGF2/ERK1/2 signaling, enhances 17β-estradiol-induced cell growth in endometrial adenocarcinoma cell.

Science.gov (United States)

Zhang, Hui; Guo, Qiufen; Wang, Chong; Yan, Lei; Fu, Yibing; Fan, Mingjun; Zhao, Xingbo; Li, Mingjiang

2013-08-25

Dual-specificity phosphatase 6 (Dusp6) is a negative feedback mechanism of fibroblast growth factors (FGFs)/mitogen-activated protein kinase (MAPK)/ERK1/2 signaling. The aim of this study was to explore the expression of Dusp6 in human endometrial adenocarcinomas and the role of Dusp6 expression in the growth regulation of endometrial adenocarcinoma cell. We found that Dusp6 was over-expressed in human endometrial adenocarcinomas. In Ishikawa cells, plasmid-driven Dusp6 expression efficiently blocked the activity of FGF2-induced MAPK/ERK1/2 signaling. Unexpectedly, Dusp6 expression significantly enhanced the growth of Ishikawa cells. In Dusp6 forced-expression cells, 17β-estradiol stimulation increased the cell growth by all most threefolds. In addition, progesterone treatment reduced the cell growth to about half both in Ishikawa cells with and without forced-Dusp6-expression. Dusp6 over-expression is involved in the pathogenesis and development of human endometrial adenocarcinomas. Dusp6 functions as a negative regulator of FGF2/ERK1/2 signaling but enhances the growth and 17β-estradiol-induced cell growth in endometrial adenocarcinoma cell. Copyright © 2013. Published by Elsevier Ireland Ltd.

3' Phosphatase activity toward phosphatidylinositol 3,4-bisphosphate [PI(3,4)P2] by voltage-sensing phosphatase (VSP).

Science.gov (United States)

Kurokawa, Tatsuki; Takasuga, Shunsuke; Sakata, Souhei; Yamaguchi, Shinji; Horie, Shigeo; Homma, Koichi J; Sasaki, Takehiko; Okamura, Yasushi

2012-06-19

Voltage-sensing phosphatases (VSPs) consist of a voltage-sensor domain and a cytoplasmic region with remarkable sequence similarity to phosphatase and tensin homolog deleted on chromosome 10 (PTEN), a tumor suppressor phosphatase. VSPs dephosphorylate the 5' position of the inositol ring of both phosphatidylinositol 3,4,5-trisphosphate [PI(3,4,5)P(3)] and phosphatidylinositol 4,5-bisphosphate [PI(4,5)P(2)] upon voltage depolarization. However, it is unclear whether VSPs also have 3' phosphatase activity. To gain insights into this question, we performed in vitro assays of phosphatase activities of Ciona intestinalis VSP (Ci-VSP) and transmembrane phosphatase with tensin homology (TPTE) and PTEN homologous inositol lipid phosphatase (TPIP; one human ortholog of VSP) with radiolabeled PI(3,4,5)P(3). TLC assay showed that the 3' phosphate of PI(3,4,5)P(3) was not dephosphorylated, whereas that of phosphatidylinositol 3,4-bisphosphate [PI(3,4)P(2)] was removed by VSPs. Monitoring of PI(3,4)P(2) levels with the pleckstrin homology (PH) domain from tandem PH domain-containing protein (TAPP1) fused with GFP (PH(TAPP1)-GFP) by confocal microscopy in amphibian oocytes showed an increase of fluorescence intensity during depolarization to 0 mV, consistent with 5' phosphatase activity of VSP toward PI(3,4,5)P(3). However, depolarization to 60 mV showed a transient increase of GFP fluorescence followed by a decrease, indicating that, after PI(3,4,5)P(3) is dephosphorylated at the 5' position, PI(3,4)P(2) is then dephosphorylated at the 3' position. These results suggest that substrate specificity of the VSP changes with membrane potential.

Variations in the G6PC2/ABCB11 genomic region are associated with fasting glucose levels

DEFF Research Database (Denmark)

Chen, Wei-Min; Erdos, Michael R; Jackson, Anne U

2008-01-01

Identifying the genetic variants that regulate fasting glucose concentrations may further our understanding of the pathogenesis of diabetes. We therefore investigated the association of fasting glucose levels with SNPs in 2 genome-wide scans including a total of 5,088 nondiabetic individuals from...... Finland and Sardinia. We found a significant association between the SNP rs563694 and fasting glucose concentrations (P = 3.5 x 10(-7)). This association was further investigated in an additional 18,436 nondiabetic individuals of mixed European descent from 7 different studies. The combined P value...... for association in these follow-up samples was 6.9 x 10(-26), and combining results from all studies resulted in an overall P value for association of 6.4 x 10(-33). Across these studies, fasting glucose concentrations increased 0.01-0.16 mM with each copy of the major allele, accounting for approximately 1...

Effects of lethal dose of γ-irradiation on intestinal enzymes of the pigeons Columba livia intermedia Strickland

International Nuclear Information System (INIS)

Gadhia, P.K.

1979-01-01

Effect of γ-irradiation with lethal dose (1000 rads) on alkaline phosphatase and glucose-6-phosphatase have been studied in two different regions (duodenum and ileum) of small intestine of pigeons. The enzymes were studied at different intervals like 2, 4, 6 and 8 days after irradiation. The sp. activities of enzyme increased significantly both in duodenum and ileum. However, significant increase in alkaline phosphatase and glucose-6-phosphatase were observed at the 2nd and the 4th days post-irradiation respectively. The increase in enzyme activities may present de novo synthesis of these enzymes after lethal dose of irradiation. The histologic picture revealed that after the 4th day of irradiation, the number of goblet cells increased and after the 6th day crypt-villus system was destroyed completely as compared to sham-irradiated pigeons. (author)

Effects of lethal dose of. gamma. -irradiation on intestinal enzymes of the pigeons Columba livia intermedia Strickland

Energy Technology Data Exchange (ETDEWEB)

Gadhia, P.K. (South Gujarat Univ., Surat (India). Dept. of Biosciences); Shah, V.C. (Gujarat Univ. School of Sciences, Ahmedabad (India))

1979-09-01

Effect of ..gamma..-irradiation with lethal dose (1000 rads) on alkaline phosphatase and glucose-6-phosphatase have been studied in two different regions (duodenum and ileum) of small intestine of pigeons. The enzymes were studied at different intervals like 2, 4, 6 and 8 days after irradiation. The sp. activities of enzyme increased significantly both in duodenum and ileum. However, significant increase in alkaline phosphatase and glucose-6-phosphatase were observed at the 2nd and the 4th days post-irradiation respectively. The increase in enzyme activities may present de novo synthesis of these enzymes after lethal dose of irradiation. The histologic picture revealed that after the 4th day of irradiation, the number of goblet cells increased and after the 6th day crypt-villus system was destroyed completely as compared to sham-irradiated pigeons.

Ribosomal S6K1 in POMC and AgRP Neurons Regulates Glucose Homeostasis but Not Feeding Behavior in Mice

Directory of Open Access Journals (Sweden)

Mark A. Smith

2015-04-01

Full Text Available Hypothalamic ribosomal S6K1 has been suggested as a point of convergence for hormonal and nutrient signals in the regulation of feeding behavior, bodyweight, and glucose metabolism. However, the long-term effects of manipulating hypothalamic S6K1 signaling on energy homeostasis and the cellular mechanisms underlying these roles are unclear. We therefore inactivated S6K1 in pro-opiomelanocortin (POMC and agouti-related protein (AgRP neurons, key regulators of energy homeostasis, but in contrast to the current view, we found no evidence that S6K1 regulates food intake and bodyweight. In contrast, S6K1 signaling in POMC neurons regulated hepatic glucose production and peripheral lipid metabolism and modulated neuronal excitability. S6K1 signaling in AgRP neurons regulated skeletal muscle insulin sensitivity and was required for glucose sensing by these neurons. Our findings suggest that S6K1 signaling is not a general integrator of energy homeostasis in the mediobasal hypothalamus but has distinct roles in the regulation of glucose homeostasis by POMC and AgRP neurons.

Down-regulation of lipoprotein lipase increases glucose uptake in L6 muscle cells

Energy Technology Data Exchange (ETDEWEB)

Lopez, Veronica; Saraff, Kumuda [Department of Chemistry and Biochemistry, California State University Northridge, Northridge, CA 91330-8262 (United States); Medh, Jheem D., E-mail: jheem.medh@csun.edu [Department of Chemistry and Biochemistry, California State University Northridge, Northridge, CA 91330-8262 (United States)

2009-11-06

Thiazolidinediones (TZDs) are synthetic hypoglycemic agents used to treat type 2 diabetes. TZDs target the peroxisome proliferator activated receptor-gamma (PPAR-{gamma}) and improve systemic insulin sensitivity. The contributions of specific tissues to TZD action, or the downstream effects of PPAR-{gamma} activation, are not very clear. We have used a rat skeletal muscle cell line (L6 cells) to demonstrate that TZDs directly target PPAR-{gamma} in muscle cells. TZD treatment resulted in a significant repression of lipoprotein lipase (LPL) expression in L6 cells. This repression correlated with an increase in glucose uptake. Down-regulation of LPL message and protein levels using siRNA resulted in a similar increase in insulin-dependent glucose uptake. Thus, LPL down-regulation improved insulin sensitivity independent of TZDs. This finding provides a novel method for the management of insulin resistance.

Gold electrode modified with a self-assembled glucose oxidase and 2,6-pyridinedicarboxylic acid as novel glucose bioanode for biofuel cells

NARCIS (Netherlands)

Ammam, Malika; Fransaer, Jan

2014-01-01

In this study, we have constructed a gold electrode modified with (3-aminopropyl)trimethoxysilane/2,6-pyridinedicarboxylic acid/glucose oxidase (abbreviated as, Au/ATS/PDA/GOx) by sequential chemical adsorption. Au/ATS/PDA/GOx electrode was characterized by Fourier Transform Infrared Spectroscopy

Role of vitamin D on the expression of glucose transporters in L6 myotubes

Directory of Open Access Journals (Sweden)

Bubblu Tamilselvan

2013-01-01

Full Text Available Altered expression of glucose transporters is a major characteristic of diabetes. Vitamin D has evolved widespread interest in the pathogenesis and prevention of diabetes. The present study was designed to investigate the effect of vitamin D in the overall regulation of muscle cell glucose transporter expression. L6 cells were exposed to type 1 and type 2 diabetic conditions and the effect of calcitriol (1,25, dihydroxy cholicalciferol on the expression of glucose transporters was studied by real time polymerase chain reaction (RT-PCR. There was a significant decrease in glucose transporter type 1 (GLUT1, GLUT4, vitamin D receptor (VDR, and IR expression in type 1 and 2 diabetic model compared to control group. Treatment of myoblasts with 10-7 M calcitriol for 24 h showed a significant increase in GLUT1, GLUT4, VDR, and insulin receptor (IR expression. The results indicate a potential antidiabetic function of vitamin D on GLUT1, GLUT4, VDR, and IR by improving receptor gene expression suggesting a role for vitamin D in regulation of expression of the glucose transporters in muscle cells.

Glucose metabolism ontogenesis in rainbow trout (Oncorhynchus mykiss) in the light of the recently sequenced genome: new tools for intermediary metabolism programming.

Science.gov (United States)

Marandel, Lucie; Véron, Vincent; Surget, Anne; Plagnes-Juan, Élisabeth; Panserat, Stéphane

2016-03-01

The rainbow trout (Oncorhynchus mykiss), a carnivorous fish species, displays a 'glucose-intolerant' phenotype when fed a high-carbohydrate diet. The importance of carbohydrate metabolism during embryogenesis and the timing of establishing this later phenotype are currently unclear. In addition, the mechanisms underlying the poor ability of carnivorous fish to use dietary carbohydrates as a major energy substrate are not well understood. It has recently been shown in trout that duplicated genes involved in glucose metabolism may participate in establishing the glucose-intolerant phenotype. The aim of this study was therefore to provide new understanding of glucose metabolism during ontogenesis and nutritional transition, taking into consideration the complexity of the trout genome. Trout were sampled at several stages of development from fertilization to hatching, and alevins were then fed a non-carbohydrate or a high-carbohydrate diet during first feeding. mRNA levels of all glucose metabolism-related genes increased in embryos during the setting up of the primitive liver. After the first meal, genes rapidly displayed expression patterns equivalent to those observed in the livers of juveniles. g6pcb2.a (a glucose 6-phosphatase-encoding gene) was up-regulated in alevins fed a high-carbohydrate diet, mimicking the expression pattern of gck genes. The g6pcb2.a gene may contribute to the non-inhibition of the last step of gluconeogenesis and thus to establishing the glucose-intolerant phenotype in trout fed a high-carbohydrate diet as early as first feeding. This information is crucial for nutritional programming investigations as it suggests that first feeding would be too late to programme glucose metabolism in the long term. © 2016. Published by The Company of Biologists Ltd.

Intermittent Hypoxia Impairs Glucose Homeostasis in C57BL6/J Mice: Partial Improvement with Cessation of the Exposure

Science.gov (United States)

Polak, Jan; Shimoda, Larissa A.; Drager, Luciano F.; Undem, Clark; McHugh, Holly; Polotsky, Vsevolod Y.; Punjabi, Naresh M.

2013-01-01

Objectives: Obstructive sleep apnea is associated with insulin resistance, glucose intolerance, and type 2 diabetes mellitus. Although several studies have suggested that intermittent hypoxia in obstructive sleep apnea may induce abnormalities in glucose homeostasis, it remains to be determined whether these abnormalities improve after discontinuation of the exposure. The objective of this study was to delineate the effects of intermittent hypoxia on glucose homeostasis, beta cell function, and liver glucose metabolism and to investigate whether the impairments improve after the hypoxic exposure is discontinued. Interventions: C57BL6/J mice were exposed to 14 days of intermittent hypoxia, 14 days of intermittent air, or 7 days of intermittent hypoxia followed by 7 days of intermittent air (recovery paradigm). Glucose and insulin tolerance tests were performed to estimate whole-body insulin sensitivity and calculate measures of beta cell function. Oxidative stress in pancreatic tissue and glucose output from isolated hepatocytes were also assessed. Results: Intermittent hypoxia increased fasting glucose levels and worsened glucose tolerance by 67% and 27%, respectively. Furthermore, intermittent hypoxia exposure was associated with impairments in insulin sensitivity and beta cell function, an increase in liver glycogen, higher hepatocyte glucose output, and an increase in oxidative stress in the pancreas. While fasting glucose levels and hepatic glucose output normalized after discontinuation of the hypoxic exposure, glucose intolerance, insulin resistance, and impairments in beta cell function persisted. Conclusions: Intermittent hypoxia induces insulin resistance, impairs beta cell function, enhances hepatocyte glucose output, and increases oxidative stress in the pancreas. Cessation of the hypoxic exposure does not fully reverse the observed changes in glucose metabolism. Citation: Polak J; Shimoda LA; Drager LF; Undem C; McHugh H; Polotsky VY; Punjabi NM

Influence of triethyl phosphate on phosphatase activity in shooting range soil: Isolation of a zinc-resistant bacterium with an acid phosphatase.

Science.gov (United States)

Story, Sandra; Brigmon, Robin L

2017-03-01

Phosphatase-mediated hydrolysis of organic phosphate may be a viable means of stabilizing heavy metals via precipitation as a metal phosphate in bioremediation applications. We investigated the effect of triethyl phosphate (TEP) on soil microbial-phosphatase activity in a heavy-metal contaminated soil. Gaseous TEP has been used at subsurface sites for bioremediation of organic contaminants but not applied in heavy-metal contaminated areas. Little is known about how TEP affects microbial activity in soils and it is postulated that TEP can serve as a phosphate source in nutrient-poor groundwater and soil/sediments. Over a 3-week period, TEP amendment to microcosms containing heavy-metal contaminated soil resulted in increased activity of soil acid-phosphatase and repression of alkaline phosphatase, indicating a stimulatory effect on the microbial population. A soil-free enrichment of microorganisms adapted to heavy-metal and acidic conditions was derived from the TEP-amended soil microcosms using TEP as the sole phosphate source and the selected microbial consortium maintained a high acid-phosphatase activity with repression of alkaline phosphatase. Addition of 5mM zinc to soil-free microcosms had little effect on acid phosphatase but inhibited alkaline phosphatase. One bacterial member from the consortium, identified as Burkholderia cepacia sp., expressed an acid-phosphatase activity uninhibited by high concentrations of zinc and produced a soluble, indigo pigment under phosphate limitation. The pigment was produced in a phosphate-free medium and was not produced in the presence of TEP or phosphate ion, indicative of purple acid-phosphatase types that are pressed by bioavailable phosphate. These results demonstrate that TEP amendment was bioavailable and increased overall phosphatase activity in both soil and soil-free microcosms supporting the possibility of positive outcomes in bioremediation applications. Copyright © 2016. Published by Elsevier Inc.

[High gene conversion frequency between genes encoding 2-deoxyglucose-6-phosphate phosphatase in 3 Saccharomyces species].

Science.gov (United States)

Piscopo, Sara-Pier; Drouin, Guy

2014-05-01

Gene conversions are nonreciprocal sequence exchanges between genes. They are relatively common in Saccharomyces cerevisiae, but few studies have investigated the evolutionary fate of gene conversions or their functional impacts. Here, we analyze the evolution and impact of gene conversions between the two genes encoding 2-deoxyglucose-6-phosphate phosphatase in S. cerevisiae, Saccharomyces paradoxus and Saccharomyces mikatae. Our results demonstrate that the last half of these genes are subject to gene conversions among these three species. The greater similarity and the greater percentage of GC nucleotides in the converted regions, as well as the absence of long regions of adjacent common converted sites, suggest that these gene conversions are frequent and occur independently in all three species. The high frequency of these conversions probably result from the fact that they have little impact on the protein sequences encoded by these genes.

IL-6 Improves Energy and Glucose Homeostasis in Obesity via Enhanced Central IL-6 trans-Signaling.

Science.gov (United States)

Timper, Katharina; Denson, Jesse Lee; Steculorum, Sophie Marie; Heilinger, Christian; Engström-Ruud, Linda; Wunderlich, Claudia Maria; Rose-John, Stefan; Wunderlich, F Thomas; Brüning, Jens Claus

2017-04-11

Interleukin (IL)-6 engages similar signaling mechanisms to leptin. Here, we find that central application of IL-6 in mice suppresses feeding and improves glucose tolerance. In contrast to leptin, whose action is attenuated in obesity, the ability of IL-6 to suppress feeding is enhanced in obese mice. IL-6 suppresses feeding in the absence of neuronal IL-6-receptor (IL-6R) expression in hypothalamic or all forebrain neurons of mice. Conversely, obese mice exhibit increased soluble IL-6R levels in the cerebrospinal fluid. Blocking IL-6 trans-signaling in the CNS abrogates the ability of IL-6 to suppress feeding. Furthermore, gp130 expression is enhanced in the paraventricular nucleus of the hypothalamus (PVH) of obese mice, and deletion of gp130 in the PVH attenuates the beneficial central IL-6 effects on metabolism. Collectively, these experiments indicate that IL-6 trans-signaling is enhanced in the CNS of obese mice, allowing IL-6 to exert its beneficial metabolic effects even under conditions of leptin resistance. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

IL-6 Improves Energy and Glucose Homeostasis in Obesity via Enhanced Central IL-6 trans-Signaling

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Katharina Timper

2017-04-01

Full Text Available Interleukin (IL-6 engages similar signaling mechanisms to leptin. Here, we find that central application of IL-6 in mice suppresses feeding and improves glucose tolerance. In contrast to leptin, whose action is attenuated in obesity, the ability of IL-6 to suppress feeding is enhanced in obese mice. IL-6 suppresses feeding in the absence of neuronal IL-6-receptor (IL-6R expression in hypothalamic or all forebrain neurons of mice. Conversely, obese mice exhibit increased soluble IL-6R levels in the cerebrospinal fluid. Blocking IL-6 trans-signaling in the CNS abrogates the ability of IL-6 to suppress feeding. Furthermore, gp130 expression is enhanced in the paraventricular nucleus of the hypothalamus (PVH of obese mice, and deletion of gp130 in the PVH attenuates the beneficial central IL-6 effects on metabolism. Collectively, these experiments indicate that IL-6 trans-signaling is enhanced in the CNS of obese mice, allowing IL-6 to exert its beneficial metabolic effects even under conditions of leptin resistance.

A review of metabolism of labeled glucoses for use in measuring glucose recycling

International Nuclear Information System (INIS)

Russell, R.W.; Young, J.W.

1990-01-01

The fate of tritium from each carbon of D-glucose and the metabolism of L-glucose and 2-deoxy-D-glucose are known. Differences in metabolism of labeled glucoses can be used to quantify physical and chemical recycling of glucose. Only physical recycling is measured by [1- 3 H]-L-glucose, whereas [U- 14 C]-D-glucose measures total recycling. The difference between [1- 3 H]-L-glucose and [U- 14 C]-D-glucose, therefore, is chemical recycling. Recycling from extracellular binding sites and hepatic glucose 6-phosphate can be measured by difference between [1,2- 3 H]-2-deoxy-D-glucose and [1- 3 H]-L-glucose, and the difference in irreversible loss of the two will measure extrahepatic uptake of D-glucose. Recycling via Cori-alanine cycle plus CO 2 is the difference in irreversible loss measured by using [6- 3 H]-glucose and [U- 14 C]-D-glucose. Recycling via the hexose monophosphate pathway can be determined by difference in irreversible loss between [1- 3 H]-D-glucose and [6- 3 H]-D-glucose. Recycling via CO 2 and glycerol must be measured directly with [U- 14 C]glucose, bicarbonate, and glycerol. Recycling via hepatic glycogen can be estimated by subtracting all other measured chemical recycling from total chemical recycling. This review describes means to quantify glucose recycling in vivo, enabling studies of mechanisms for conservation and utilization of glucose. 54 references

A histochemical study of rat salivary gland acid phosphatase.

Science.gov (United States)

Isacsson, G

1986-01-01

Male Sprague-Dawley rats received 4 mg pilocarpine/100 g body wt intraperitoneally or physiological saline as control and were killed at various intervals. Acid phosphatase was reacted on frozen sections from soft palate, parotid and submandibular glands using sodium-alpha-naphthyl acid phosphate as substrate. Various inhibitors were added to the incubation medium. The strongest acid phosphatase activity was in the parotid gland acinar and proximal secretory duct cells; the mucous minor glands of the palate were completely negative. Activity was found in the acinar cells, proximal secretory duct cells, granular and striated duct and excretory duct cells. Pilocarpine injection slightly reduced the activity up to 6 h after injection. Cupric chloride added to the incubation medium lowered the overall activity. Fluoride and molybdate inhibited the acid phosphatase reaction in all structures. Tartrate inhibited the reaction in all structures except the submandibular striated duct cells. The tartrate-resistant activity may be a Na+K+-dependent ATPase involved in re-absorbing water and electrolytes from the primary saliva.

Acid phosphatases in seeds and developing of squash (Cucurbita ficifolia

Directory of Open Access Journals (Sweden)

Irena Lorenc-Kubis

2014-01-01

Full Text Available Changes in protein content and acid phosphatase activity were followed during germination (imbition through seedlings development in extracts from cotyledons of squash (Cucurbita ficifolia. It has been shown that the activity of acid phosphatase was initially low and than increased to a maximum after 6 days of imbition. Acid phosphates were isolated from cotyledons of seeds and from 6-, 10- and 22-days old seedlings by extraction the proteins with 0.1 M acetate buffer pH 5.1, precipitation with ethanol and by affinity chromatography on con A-Sepharose. Two glycoprotein enzymes AcPase Ba and AcPase Bb which differ in their affinity to immobilized con A were obtained. Both acid phosphatates retained the enzyme activity after binding to free con A. Rocket affinity electrophoresis of AcPase Ba and AcPase Bb, isolated from cotyledons of seeds and seedlings, revealed differences in their ability to bind to con A during seeds germination and seedling develop-ment indicating changes in their sugar component. Con A was found to activate both enzymes. The enzymes cross-reacted with monospecific antibodies raised against grass seed acid phosphatate Ba indicating an antigenic relationship between squash and grass acid phosphatases.

Posttranslational heterogeneity of bone alkaline phosphatase in metabolic bone disease.

Science.gov (United States)

Langlois, M R; Delanghe, J R; Kaufman, J M; De Buyzere, M L; Van Hoecke, M J; Leroux-Roels, G G

1994-09-01

Bone alkaline phosphatase is a marker of osteoblast activity. In order to study the posttranscriptional modification (glycosylation) of bone alkaline phosphatase in bone disease, we investigated the relationship between mass and catalytic activity of bone alkaline phosphatase in patients with osteoporosis and hyperthyroidism. Serum bone alkaline phosphatase activity was measured after lectin precipitation using the Iso-ALP test kit. Mass concentration of bone alkaline phosphatase was determined with an immunoradiometric assay (Tandem-R Ostase). In general, serum bone alkaline phosphatase mass and activity concentration correlated well. The activity : mass ratio of bone alkaline phosphatase was low in hyperthyroidism. Activation energy of the reaction catalysed by bone alkaline phosphatase was high in osteoporosis and in hyperthyroidism. Experiments with neuraminidase digestion further demonstrated that the thermodynamic heterogeneity of bone alkaline phosphatase can be explained by a different glycosylation of the enzyme.

Effects of ozone on adult and aged lung oxygen consumption, glucose metabolism and G6PDH activity

International Nuclear Information System (INIS)

Raska-Emery, P.; Balis, J.U.; Montgomery, M.R.

1991-01-01

Fischer-344 male adult (4-6 mo) and aged (24-26 mo) rats were exposed to 0-3.0 ppm O 3 for 8h, sacrificed immediately, and O 2 consumption, 1 C 14 -glucose metabolism and G6PDH activity were determined. For O 2 consumption, the exp to 0.5 ppm O 3 produced a stimulation in both age groups. Decrements in O 2 consumption were only evident in aged rats after 1.5 and 3.0 ppm. Glucose metabolism showed a marked difference rats were 40% adult rats. Control values in aged rats were 40% of adults. Exp to 0.5 ppm was stimulatory in adults and aged, while 1.5 and 3.0 pp, decreased glucose metabolism in both groups. No age-related difference in G6PDH activity between control and exposed was seen. However, in both age groups, 0.5 ppm O 3 resulted in a significant increase in activity (33-41%)l 1.5 and 3.0 ppm were without effect. The combined results show a biphasic response of adult and aged lung to severe, acute O 3 exp. One-half ppm O 3 for 8h is stimulatory for all three parameters examined in both age groups. Three ppm O 3 inhibits O 2 consumption and glucose metabolism in both age groups but is ineffective on G6PDH activity

Ribosomal S6K1 in POMC and AgRP Neurons Regulates Glucose Homeostasis but Not Feeding Behavior in Mice.

Science.gov (United States)

Smith, Mark A; Katsouri, Loukia; Irvine, Elaine E; Hankir, Mohammed K; Pedroni, Silvia M A; Voshol, Peter J; Gordon, Matthew W; Choudhury, Agharul I; Woods, Angela; Vidal-Puig, Antonio; Carling, David; Withers, Dominic J

2015-04-21

Hypothalamic ribosomal S6K1 has been suggested as a point of convergence for hormonal and nutrient signals in the regulation of feeding behavior, bodyweight, and glucose metabolism. However, the long-term effects of manipulating hypothalamic S6K1 signaling on energy homeostasis and the cellular mechanisms underlying these roles are unclear. We therefore inactivated S6K1 in pro-opiomelanocortin (POMC) and agouti-related protein (AgRP) neurons, key regulators of energy homeostasis, but in contrast to the current view, we found no evidence that S6K1 regulates food intake and bodyweight. In contrast, S6K1 signaling in POMC neurons regulated hepatic glucose production and peripheral lipid metabolism and modulated neuronal excitability. S6K1 signaling in AgRP neurons regulated skeletal muscle insulin sensitivity and was required for glucose sensing by these neurons. Our findings suggest that S6K1 signaling is not a general integrator of energy homeostasis in the mediobasal hypothalamus but has distinct roles in the regulation of glucose homeostasis by POMC and AgRP neurons. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

The rate of lactate production from glucose in hearts is not altered by per-deuteration of glucose

Science.gov (United States)

Funk, Alexander M.; Anderson, Brian L.; Wen, Xiaodong; Hever, Thomas; Khemtong, Chalermchai; Kovacs, Zoltan; Sherry, A. Dean; Malloy, Craig R.

2017-11-01

This study was designed to determine whether perdeuterated glucose experiences a kinetic isotope effect (KIE) as glucose passes through glycolysis and is further oxidized in the tricarboxylic acid (TCA) cycle. Metabolism of deuterated glucose was investigated in two groups of perfused rat hearts. The control group was supplied with a 1:1 mixture of [U-13C6]glucose and [1,6-13C2]glucose, while the experimental group received [U-13C6,U-2H7]glucose and [1,6-13C2]glucose. Tissue extracts were analyzed by 1H, 2H and proton-decoupled 13C NMR spectroscopy. Extensive 2H-13C scalar coupling plus chemical shift isotope effects were observed in the proton-decoupled 13C NMR spectra of lactate, alanine and glutamate. A small but measureable (∼8%) difference in the rate of conversion of [U-13C6]glucose vs. [1,6-13C2]glucose to lactate, likely reflecting rates of Csbnd C bond breakage in the aldolase reaction, but conversion of [U-13C6]glucose versus [U-13C6,U-2H7]glucose to lactate did not differ. This shows that the presence of deuterium in glucose does not alter glycolytic flux. However, there were two distinct effects of deuteration on metabolism of glucose to alanine and oxidation of glucose in the TCA. First, alanine undergoes extensive exchange of methyl deuterons with solvent protons in the alanine amino transferase reaction. Second, there is a substantial kinetic isotope effect in metabolism of [U-13C6,U-2H7]glucose to alanine and glutamate. In the presence of [U-13C6,U-2H7]glucose, alanine and lactate are not in rapid exchange with the same pool of pyruvate. These studies indicate that the appearance of hyperpolarized 13C-lactate from hyperpolarized [U-13C6,U-2H7]glucose is not substantially influenced by a deuterium kinetic isotope effect.

Elevated serum tartrate-resistant acid phosphatase isoform 5a levels in metabolic syndrome.

Science.gov (United States)

Huang, Yi-Jhih; Huang, Tsai-Wang; Chao, Tsu-Yi; Sun, Yu-Shan; Chen, Shyi-Jou; Chu, Der-Ming; Chen, Wei-Liang; Wu, Li-Wei

2017-09-29

Tartrate-resistant phosphatase isoform 5a is expressed in tumor-associated macrophages and is a biomarker of chronic inflammation. Herein, we correlated serum tartrate-resistant phosphatase isoform 5a levels with metabolic syndrome status and made comparisons with traditional markers of inflammation, including c-reactive protein and interleukin-6. One hundred healthy volunteers were randomly selected, and cut-off points for metabolic syndrome related inflammatory biomarkers were determined using receiver operating characteristic curves. Linear and logistic regression models were subsequently used to correlate inflammatory markers with the risk of metabolic syndrome. Twenty-two participants met the criteria for metabolic syndrome, and serum tartrate-resistant phosphatase isoform 5a levels of >5.8 μg/L were associated with metabolic syndrome (c-statistics, 0.730; p = 0.001; 95% confidence interval, 0.618-0.842). In addition, 1 μg/L increases in tartrate-resistant phosphatase isoform 5a levels were indicative of a 1.860 fold increase in the risk of metabolic syndrome (p = 0.012). Elevated serum tartrate-resistant phosphatase isoform 5a levels are associated with the risk of metabolic syndrome, with a cut-off level of 5.8 μg/L.

Bisphenol A impairs hepatic glucose sensing in C57BL/6 male mice.

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Leigh Perreault

Full Text Available AIMS/HYPOTHESIS: Glucose sensing (eg. glucokinase activity becomes impaired in the development of type 2 diabetes, the etiology of which is unclear. Estrogen can stimulate glucokinase activity, whereas the pervasive environmental pollutant bisphenol A (BPA can inhibit estrogen action, hence we aimed to determine the effect of BPA on glucokinase activity directly. METHODS: To evaluate a potential acute effect on hepatic glucokinase activity, BPA in water (n = 5 vs. water alone (n = 5 was administered at the EPA's purported "safe dose" (50 µg/kg by gavage to lean 6-month old male C57BL/6 mice. Two hours later, animals were euthanized and hepatic glucokinase activity measured over glucose levels from 1-20 mmol/l in liver homogenate. To determine the effect of chronic BPA exposure on hepatic glucokinase activity, lean 6-month old male C57BL/6 mice were provided with water (n = 15 or water with 1.75 mM BPA (∼50 µg/kg/day; n = 14 for 2 weeks. Following the 2-week exposure, animals were euthanized and glucokinase activity measured as above. RESULTS: Hepatic glucokinase activity was signficantly suppressed after 2 hours in animals given an oral BPA bolus compared to those who received only water (p = 0.002-0.029 at glucose 5-20 mmol/l; overall treatment effect p<0.001. Exposure to BPA over 2 weeks also suppressed hepatic glucokinase activity in exposed vs. unexposed mice (overall treatment effect, p = 0.003. In both experiments, the Hill coefficient was higher and Vmax lower in mice treated with BPA. CONCLUSIONS/INTERPRETATION: Both acute and chronic exposure to BPA significantly impair hepatic glucokinase activity and function. These findings identify a potential mechanism for how BPA may increase risk for diabetes.

Post-irradiation repairing processes of glucose-6-phosphate dehydrogenase and catalase from Hansenula Polymorpha yeast

International Nuclear Information System (INIS)

Postolache, Carmen; Postolache, Cristian; Dinu, Diana; Dinischiotu, Anca; Sahini, Victor Emanuel

2002-01-01

The post-irradiation repairing mechanisms of two Hansenula Polymorpha yeast enzymes, glucose-6-phosphate dehydrogenase and catalase, were studied. The kinetic parameters of the selected enzymes were investigated over one month since the moment of γ-irradiation with different doses in the presence of oxygen. Dose dependent decrease of initial reaction rates was noticed for both enzymes. Small variation of initial reaction rate was recorded for glucose-6-phosphate dehydrogenase over one month, with a decreasing tendency. No significant electrophoretic changes of molecular forms of this enzyme were observed after irradiation. Continuous strong decrease of catalase activity was evident for the first 20 days after irradiation. Partial recovery process of the catalytic activity was revealed by this study. (authors)

Glucose oxidase-functionalized fluorescent gold nanoclusters as probes for glucose

International Nuclear Information System (INIS)

Xia, Xiaodong; Long, Yunfei; Wang, Jianxiu

2013-01-01

Highlights: ► A glucose oxidase/gold nanocluster conjugates formed by etching chemistry. ► Integration of the bioactivities and fluorescence properties within a single unit. ► These conjugates serve as novel fluorescent probe for glucose. -- Abstract: Creation and application of noble metal nanoclusters have received continuous attention. By integrating enzyme activity and fluorescence for potential applications, enzyme-capped metal clusters are more desirable. This work demonstrated a glucose oxidase (an enzyme for glucose)-functionalized gold cluster as probe for glucose. Under physiological conditions, such bioconjugate was successfully prepared by an etching reaction, where tetrakis (hydroxylmethyl) phosphonium-protected gold nanoparticle and thioctic acid-modified glucose oxidase were used as precursor and etchant, respectively. These bioconjugates showed unique fluorescence spectra (λ em max = 650 nm, λ ex max = 507 nm) with an acceptable quantum yield (ca. 7%). Moreover, the conjugated glucose oxidase remained active and catalyzed reaction of glucose and dissolved O 2 to produce H 2 O 2 , which quenched quantitatively the fluorescence of gold clusters and laid a foundation of glucose detection. A linear range of 2.0 × 10 −6 –140 × 10 −6 M and a detection limit of 0.7 × 10 −6 M (S/N = 3) were obtained. Also, another horseradish peroxidase/gold cluster bioconjugate was produced by such general synthesis method. Such enzyme/metal cluster bioconjugates represented a promising class of biosensors for biologically important targets in organelles or cells

Effects of GCK, GCKR, G6PC2 and MTNR1B variants on glucose metabolism and insulin secretion.

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Cheng Hu

Full Text Available BACKGROUND: Single nucleotide polymorphisms (SNPs from GCK, GCKR, G6PC2 and MTNR1B were found to modulate the fasting glucose levels. The current study aimed to replicate this association in the Chinese population and further analyze their effects on biphasic insulin secretion. METHODS/PRINCIPAL FINDINGS: SNPs from GCK, GCKR, G6PC2 and MTNR1B were genotyped in the Shanghai Chinese, including 3,410 type 2 diabetes patients and 3,412 controls. The controls were extensively phenotyped for the traits related to glucose metabolism and insulin secretion. We replicated the association between GCK rs1799884, G6PC2 rs16856187 and MTNR1B rs10830963 and fasting glucose in our samples (p = 0.0003-2.0x10(-8. GCK rs1799884 and G6PC2 rs16856187 showed association to HOMA-beta, insulinogenic index and both first- and second-phases insulin secretion (p = 0.0030-0.0396. MTNR1B rs10830963 was associated to HOMA-beta, insulinogenic index and first-phase insulin secretion (p = 0.0102-0.0426, but not second-phase insulin secretion (p = 0.9933. Combined effect analyses showed individuals carrying more risk allele for high fasting glucose tended to have a higher glucose levels at both fasting and 2 h during OGTTs (p = 1.7x10(-13 and 0.0009, respectively, as well as lower HOMA-beta, insulinogenic index and both first- and second-phases insulin secretion (p = 0.0321-1.1x10(-7. CONCLUSIONS/SIGNIFICANCE: We showed that SNPs from GCK, G6PC2 and MTNR1B modulated the fasting glucose levels in the normoglycaemic population while SNPs from G6PC2 and GCKR was associated with type 2 diabetes. Moreover, we found GCK and G6PC2 genetic variants were associated to both first- and second-phases insulin secretion while MTNR1B genetic variant was associated with first-phase insulin secretion, but not second-phase insulin secretion.

Use of anesthesia dramatically alters the oral glucose tolerance and insulin secretion in C57Bl/6 mice

DEFF Research Database (Denmark)

Windeløv, Johanne A; Pedersen, Jens; Holst, Jens J

2016-01-01

Evaluation of the impact of anesthesia on oral glucose tolerance in mice. Anesthesia is often used when performing OGTT in mice to avoid the stress of gavage and blood sampling, although anesthesia may influence gastrointestinal motility, blood glucose, and plasma insulin dynamics. C57Bl/6 mice...... in the time frame -15 to +150 min. Plasma insulin concentration was measured at time 0 and 20 min. All four anesthetic regimens resulted in impaired glucose tolerance compared to saline/no anesthesia. (1) hypnorm/midazolam increased insulin concentrations and caused an altered glucose tolerance; (2) ketamine...... regimens altered the oral glucose tolerance, and we conclude that anesthesia should not be used when performing metabolic studies in mice....

B-Cell-Specific Diversion of Glucose Carbon Utilization Reveals a Unique Vulnerability in B Cell Malignancies.

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Xiao, Gang; Chan, Lai N; Klemm, Lars; Braas, Daniel; Chen, Zhengshan; Geng, Huimin; Zhang, Qiuyi Chen; Aghajanirefah, Ali; Cosgun, Kadriye Nehir; Sadras, Teresa; Lee, Jaewoong; Mirzapoiazova, Tamara; Salgia, Ravi; Ernst, Thomas; Hochhaus, Andreas; Jumaa, Hassan; Jiang, Xiaoyan; Weinstock, David M; Graeber, Thomas G; Müschen, Markus

2018-04-05

B cell activation during normal immune responses and oncogenic transformation impose increased metabolic demands on B cells and their ability to retain redox homeostasis. While the serine/threonine-protein phosphatase 2A (PP2A) was identified as a tumor suppressor in multiple types of cancer, our genetic studies revealed an essential role of PP2A in B cell tumors. Thereby, PP2A redirects glucose carbon utilization from glycolysis to the pentose phosphate pathway (PPP) to salvage oxidative stress. This unique vulnerability reflects constitutively low PPP activity in B cells and transcriptional repression of G6PD and other key PPP enzymes by the B cell transcription factors PAX5 and IKZF1. Reflecting B-cell-specific transcriptional PPP-repression, glucose carbon utilization in B cells is heavily skewed in favor of glycolysis resulting in lack of PPP-dependent antioxidant protection. These findings reveal a gatekeeper function of the PPP in a broad range of B cell malignancies that can be efficiently targeted by small molecule inhibition of PP2A and G6PD. Copyright © 2018 Elsevier Inc. All rights reserved.

Liver-Specific Deletion of Protein-Tyrosine Phosphatase 1B (PTP1B) Improves Metabolic Syndrome and Attenuates Diet-Induced Endoplasmic Reticulum Stress

Science.gov (United States)

Delibegovic, Mirela; Zimmer, Derek; Kauffman, Caitlin; Rak, Kimberly; Hong, Eun-Gyoung; Cho, You-Ree; Kim, Jason K.; Kahn, Barbara B.; Neel, Benjamin G.; Bence, Kendra K.

2009-01-01

OBJECTIVE—The protein tyrosine phosphatase PTP1B is a negative regulator of insulin signaling; consequently, mice deficient in PTP1B are hypersensitive to insulin. Because PTP1B−/− mice have diminished fat stores, the extent to which PTP1B directly regulates glucose homeostasis is unclear. Previously, we showed that brain-specific PTP1B−/− mice are protected against high-fat diet–induced obesity and glucose intolerance, whereas muscle-specific PTP1B−/− mice have increased insulin sensitivity independent of changes in adiposity. Here we studied the role of liver PTP1B in glucose homeostasis and lipid metabolism. RESEARCH DESIGN AND METHODS—We analyzed body mass/adiposity, insulin sensitivity, glucose tolerance, and lipid metabolism in liver-specific PTP1B−/− and PTP1Bfl/fl control mice, fed a chow or high-fat diet. RESULTS—Compared with normal littermates, liver-specific PTP1B−/− mice exhibit improved glucose homeostasis and lipid profiles, independent of changes in adiposity. Liver-specific PTP1B−/− mice have increased hepatic insulin signaling, decreased expression of gluconeogenic genes PEPCK and G-6-Pase, enhanced insulin-induced suppression of hepatic glucose production, and improved glucose tolerance. Liver-specific PTP1B−/− mice exhibit decreased triglyceride and cholesterol levels and diminished expression of lipogenic genes SREBPs, FAS, and ACC. Liver-specific PTP1B deletion also protects against high-fat diet–induced endoplasmic reticulum stress response in vivo, as evidenced by decreased phosphorylation of p38MAPK, JNK, PERK, and eIF2α and lower expression of the transcription factors C/EBP homologous protein and spliced X box-binding protein 1. CONCLUSIONS—Liver PTP1B plays an important role in glucose and lipid metabolism, independent of alterations in adiposity. Inhibition of PTP1B in peripheral tissues may be useful for the treatment of metabolic syndrome and reduction of cardiovascular risk in addition to

Protein phosphatases decrease their activity during capacitation: a new requirement for this event.

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Janetti R Signorelli

Full Text Available There are few reports on the role of protein phosphatases during capacitation. Here, we report on the role of PP2B, PP1, and PP2A during human sperm capacitation. Motile sperm were resuspended in non-capacitating medium (NCM, Tyrode's medium, albumin- and bicarbonate-free or in reconstituted medium (RCM, NCM plus 2.6% albumin/25 mM bicarbonate. The presence of the phosphatases was evaluated by western blotting and the subcellular localization by indirect immunofluorescence. The function of these phosphatases was analyzed by incubating the sperm with specific inhibitors: okadaic acid, I2, endothall, and deltamethrin. Different aliquots were incubated in the following media: 1 NCM; 2 NCM plus inhibitors; 3 RCM; and 4 RCM plus inhibitors. The percent capacitated sperm and phosphatase activities were evaluated using the chlortetracycline assay and a phosphatase assay kit, respectively. The results confirm the presence of PP2B and PP1 in human sperm. We also report the presence of PP2A, specifically, the catalytic subunit and the regulatory subunits PR65 and B. PP2B and PP2A were present in the tail, neck, and postacrosomal region, and PP1 was present in the postacrosomal region, neck, middle, and principal piece of human sperm. Treatment with phosphatase inhibitors rapidly (≤1 min increased the percent of sperm depicting the pattern B, reaching a maximum of ∼40% that was maintained throughout incubation; after 3 h, the percent of capacitated sperm was similar to that of the control. The enzymatic activity of the phosphatases decreased during capacitation without changes in their expression. The pattern of phosphorylation on threonine residues showed a sharp increase upon treatment with the inhibitors. In conclusion, human sperm express PP1, PP2B, and PP2A, and the activity of these phosphatases decreases during capacitation. This decline in phosphatase activities and the subsequent increase in threonine phosphorylation may be an important

TLQP-21 protects human umbilical vein endothelial cells against high-glucose-induced apoptosis by increasing G6PD expression.

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Wei Zhang

Full Text Available Hyperglycemia causes oxidative stress that could damage vascular endothelial cells, leading to cardiovascular complications. The Vgf gene was identified as a nerve growth factor-responsive gene, and its protein product, VGF, is characterized by the presence of partially cleaved products. One of the VGF-derived peptides is TLQP-21, which is composed of 21 amino acids (residues 556-576. Past studies have reported that TLQP-21 could stimulate insulin secretion in pancreatic cells and protect these cells from apoptosis, which suggests that TLQP-21 has a potential function in diabetes therapy. Here, we explore the protective role of TLQP-21 against the high glucose-mediated injury of vascular endothelial cells. Using human umbilical vascular endothelial cells (HUVECs, we demonstrated that TLQP-21 (10 or 50 nM dose-dependently prevented apoptosis under high-glucose (30 mmol/L conditions (the normal glucose concentration is 5.6 mmol/L. TLQP-21 enhanced the expression of NAPDH, resulting in upregulation of glutathione (GSH and a reduction in the levels of reactive oxygen species (ROS. TLQP-21 also upregulated the expression of glucose-6-phosphate dehydrogenase (G6PD, which is known as the main source of NADPH. Knockdown of G6PD almost completely blocked the increase of NADPH induced by TLQP-21, indicating that TLQP-21 functions mainly through G6PD to promote NADPH generation. In conclusion, TLQP-21 could increase G6PD expression, which in turn may increase the synthesis of NADPH and GSH, thereby partially restoring the redox status of vascular endothelial cells under high glucose injury. We propose that TLQP-21 is a promising drug for diabetes therapy.

Glucose oxidase-functionalized fluorescent gold nanoclusters as probes for glucose

Energy Technology Data Exchange (ETDEWEB)

Xia, Xiaodong [College of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China); School of Chemistry and Chemical Engineering, Hunan University of Science and Technology, Xiangtan 411201 (China); Long, Yunfei, E-mail: l_yunfei927@163.com [School of Chemistry and Chemical Engineering, Hunan University of Science and Technology, Xiangtan 411201 (China); Wang, Jianxiu, E-mail: jxiuwang@csu.edu.cn [College of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China)

2013-04-15

Highlights: ► A glucose oxidase/gold nanocluster conjugates formed by etching chemistry. ► Integration of the bioactivities and fluorescence properties within a single unit. ► These conjugates serve as novel fluorescent probe for glucose. -- Abstract: Creation and application of noble metal nanoclusters have received continuous attention. By integrating enzyme activity and fluorescence for potential applications, enzyme-capped metal clusters are more desirable. This work demonstrated a glucose oxidase (an enzyme for glucose)-functionalized gold cluster as probe for glucose. Under physiological conditions, such bioconjugate was successfully prepared by an etching reaction, where tetrakis (hydroxylmethyl) phosphonium-protected gold nanoparticle and thioctic acid-modified glucose oxidase were used as precursor and etchant, respectively. These bioconjugates showed unique fluorescence spectra (λ{sub em} {sub max} = 650 nm, λ{sub ex} {sub max} = 507 nm) with an acceptable quantum yield (ca. 7%). Moreover, the conjugated glucose oxidase remained active and catalyzed reaction of glucose and dissolved O{sub 2} to produce H{sub 2}O{sub 2}, which quenched quantitatively the fluorescence of gold clusters and laid a foundation of glucose detection. A linear range of 2.0 × 10{sup −6}–140 × 10{sup −6} M and a detection limit of 0.7 × 10{sup −6} M (S/N = 3) were obtained. Also, another horseradish peroxidase/gold cluster bioconjugate was produced by such general synthesis method. Such enzyme/metal cluster bioconjugates represented a promising class of biosensors for biologically important targets in organelles or cells.

Increased liver alkaline phosphatase and aminotransferase ...

African Journals Online (AJOL)

The effect of daily, oral administration of ethanolic extract of Khaya senegalensis stem bark (2mg/kg body weight) for 18days on the alkaline phosphatase, aspartate and alanine aminotransferase activities of rat liver and serum were investigated. Compared with the control, the activities of liver alkaline phosphatase (ALP), ...

Hexachlorobenzene impairs glucose metabolism in a rat model of porphyria cutanea tarda: a mechanistic approach

Energy Technology Data Exchange (ETDEWEB)

Mazzetti, Marta Blanca; Taira, Maria Cristina; Lelli, Sandra Marcela; Viale, Leonor Carmen San Martin de [Departamento de Quimica Biologica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, C1428BGA, Ciudad Autonoma Buenos Aires (Argentina); Dascal, Eduardo; Basabe, Juan Carlos [Centro de Investigaciones Endocrinologicas (CEDIE). Hospital de Ninos, Dr. Ricardo Gutierrez, C1425EDF, Ciudad Autonoma Buenos Aires (Argentina)

2004-01-01

Hexachlobenzene (HCB), one of the most persistent environmental pollutants, induces porphyria cutanea tarda (PCT). The aim of this work was to analyze the effect of HCB on some aspects of glucose metabolism, particularly those related to its neosynthesis in vivo. For this purpose, a time-course study on gluconeogenic enzymes, pyruvate carboxylase (PC), phosphoenolpyruvate carboxykinase (PEPCK), glucose-6-phosphatase (G-6-Pase) and on pyruvate kinase (PK), a glycolytic enzyme, was carried out. Plasma glucose and insulin levels, hepatic glycogen, tryptophan contents, and the pancreatic insulin secretion pattern stimulated by glucose were investigated. Oxidative stress and heme pathway parameters were also evaluated. HCB treatment decreased PC, PEPCK, and G-6-Pase activities. The effect was observed at an early time point and grew as the treatment progressed. Loss of 60, 56, and 37%, respectively, was noted at the end of the treatment when a considerable amount of porphyrins had accumulated in the liver as a result of drastic blockage of uroporphyrinogen decarboxylase (URO-D) (95% inhibition). The plasma glucose level was reduced (one-third loss), while storage of hepatic glucose was stimulated in a time-dependent way by HCB treatment. A decay in the normal plasma insulin level was observed as fungicide intoxication progressed (twice to four times lower). However, normal insulin secretion of perifused pancreatic Langerhans islets stimulated by glucose during the 3rd and 6th weeks of treatment did not prove to be significantly affected. HCB promoted a time-dependent increase in urinary chemiluminiscence (fourfold) and hepatic malondialdehide (MDA) content (fivefold), while the liver tryptophan level was only raised at the longest intoxication times. These results would suggest that HCB treatment does not cause a primary alteration in the mechanism of pancreatic insulin secretion and that the changes induced by the fungicide on insulin levels would be an adaptative

Glycogen storage disease type III. A case report.

Science.gov (United States)

de Waal, A; Röhm, G F; Hoek, B B; Potgieter, G M; Oosthuysen, W T

1984-01-07

A 5-year-old Black boy presented with massive hepatomegaly and muscle weakness. Liver biopsy revealed the presence of glycogen pools in the cytoplasm and nuclei of hepatocytes. Erythrocyte glycogen levels, identified as limit dextrin, were grossly increased. The galactose tolerance test as well as the two-stage glucagon stimulation test suggested a decrease in activity of both amylo-1,6-glucosidase and glucose-6-phosphatase enzymes. This was confirmed by direct assays performed on liver tissue and erythrocytes. The decrease in glucose-6-phosphatase activity was attributed to a secondary effect of limit dextrin.

Dephosphorylation of microtubule-binding sites at the neurofilament-H tail domain by alkaline, acid, and protein phosphatases.

Science.gov (United States)

Hisanaga, S; Yasugawa, S; Yamakawa, T; Miyamoto, E; Ikebe, M; Uchiyama, M; Kishimoto, T

1993-06-01

The dephosphorylation-induced interaction of neurofilaments (NFs) with microtubules (MTs) was investigated by using several phosphatases. Escherichia coli alkaline and wheat germ acid phosphatases increased the electrophoretic mobility of NF-H and NF-M by dephosphorylation, and induced the binding of NF-H to MTs. The binding of NFs to MTs was observed only after the electrophoretic mobility of NF-H approached the exhaustively dephosphorylated level when alkaline phosphatase was used. The number of phosphate remaining when NF-H began to bind to MTs was estimated by measuring phosphate bound to NF-H. NF-H did not bind to MTs even when about 40 phosphates from the total of 51 had been removed by alkaline phosphatase. The removal of 6 further phosphates finally resulted in the association of NF-H with MTs. A similar finding, that the restricted phosphorylation sites in the NF-H tail domain, but not the total amount of phosphates, were important for binding to MTs, was also obtained with acid phosphatases. In contrast to alkaline and acid phosphatases, four classes of protein phosphatases (protein phosphatases 1, 2A, 2B, and 2C) were ineffective for shifting the electrophoretic mobility of NF proteins and for inducing the association of NFs to MTs.

Dietary patterns in men and women are simultaneously determinants of altered glucose metabolism and bone metabolism.

Science.gov (United States)

Langsetmo, Lisa; Barr, Susan I; Dasgupta, Kaberi; Berger, Claudie; Kovacs, Christopher S; Josse, Robert G; Adachi, Jonathan D; Hanley, David A; Prior, Jerilynn C; Brown, Jacques P; Morin, Suzanne N; Davison, Kenneth S; Goltzman, David; Kreiger, Nancy

2016-04-01

We hypothesized that diet would have direct effects on glucose metabolism with direct and indirect effects on bone metabolism in a cohort of Canadian adults. We assessed dietary patterns (Prudent [fruit, vegetables, whole grains, fish, and legumes] and Western [soft drinks, potato chips, French fries, meats, and desserts]) from a semiquantitative food frequency questionnaire. We used fasting blood samples to measure glucose, insulin, homeostatic model assessment insulin resistance (HOMA-IR), 25-hydroxyvitamin D (25OHD), parathyroid hormone, bone-specific alkaline phosphatase (a bone formation marker), and serum C-terminal telopeptide (CTX; a bone resorption marker). We used multivariate regression models adjusted for confounders and including/excluding body mass index. In a secondary analysis, we examined relationships through structural equations models. The Prudent diet was associated with favorable effects on glucose metabolism (lower insulin and HOMA-IR) and bone metabolism (lower CTX in women; higher 25OHD and lower parathyroid hormone in men). The Western diet was associated with deleterious effects on glucose metabolism (higher glucose, insulin, and HOMA-IR) and bone metabolism (higher bone-specific alkaline phosphatase and lower 25OHD in women; higher CTX in men). Body mass index adjustment moved point estimates toward the null, indicating partial mediation. The structural equation model confirmed the hypothesized linkage with strong effects of Prudent and Western diet on metabolic risk, and both direct and indirect effects of a Prudent diet on bone turnover. In summary, a Prudent diet was associated with lower metabolic risk with both primary and mediated effects on bone turnover, suggesting that it is a potential target for reducing fracture risk. Copyright © 2016 Elsevier Inc. All rights reserved.

Muscle insulin sensitivity and glucose metabolism are controlled by the intrinsic muscle clock★

Science.gov (United States)

Dyar, Kenneth A.; Ciciliot, Stefano; Wright, Lauren E.; Biensø, Rasmus S.; Tagliazucchi, Guidantonio M.; Patel, Vishal R.; Forcato, Mattia; Paz, Marcia I.P.; Gudiksen, Anders; Solagna, Francesca; Albiero, Mattia; Moretti, Irene; Eckel-Mahan, Kristin L.; Baldi, Pierre; Sassone-Corsi, Paolo; Rizzuto, Rosario; Bicciato, Silvio; Pilegaard, Henriette; Blaauw, Bert; Schiaffino, Stefano

2013-01-01

Circadian rhythms control metabolism and energy homeostasis, but the role of the skeletal muscle clock has never been explored. We generated conditional and inducible mouse lines with muscle-specific ablation of the core clock gene Bmal1. Skeletal muscles from these mice showed impaired insulin-stimulated glucose uptake with reduced protein levels of GLUT4, the insulin-dependent glucose transporter, and TBC1D1, a Rab-GTPase involved in GLUT4 translocation. Pyruvate dehydrogenase (PDH) activity was also reduced due to altered expression of circadian genes Pdk4 and Pdp1, coding for PDH kinase and phosphatase, respectively. PDH inhibition leads to reduced glucose oxidation and diversion of glycolytic intermediates to alternative metabolic pathways, as revealed by metabolome analysis. The impaired glucose metabolism induced by muscle-specific Bmal1 knockout suggests that a major physiological role of the muscle clock is to prepare for the transition from the rest/fasting phase to the active/feeding phase, when glucose becomes the predominant fuel for skeletal muscle. PMID:24567902

Glucose-6-phosphate dehydrogenase deficiency in Nigerian children.

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Olatundun Williams

Full Text Available Glucose-6-phosphate dehydrogenase (G6PD deficiency is the most common human enzymopathy and in Sub-Saharan Africa, is a significant cause of infection- and drug-induced hemolysis and neonatal jaundice. Our goals were to determine the prevalence of G6PD deficiency among Nigerian children of different ethnic backgrounds and to identify predictors of G6PD deficiency by analyzing vital signs and hematocrit and by asking screening questions about symptoms of hemolysis. We studied 1,122 children (561 males and 561 females aged 1 month to 15 years. The mean age was 7.4 ± 3.2 years. Children of Yoruba ethnicity made up the largest group (77.5% followed by those Igbo descent (10.6% and those of Igede (10.2% and Tiv (1.8% ethnicity. G6PD status was determined using the fluorescent spot method. We found that the overall prevalence of G6PD deficiency was 15.3% (24.1% in males, 6.6% in females. Yoruba children had a higher prevalence (16.9% than Igede (10.5%, Igbo (10.1% and Tiv (5.0% children. The odds of G6PD deficiency were 0.38 times as high in Igbo children compared to Yoruba children (p=0.0500. The odds for Igede and Tiv children were not significantly different from Yoruba children (p=0.7528 and 0.9789 respectively. Mean oxygen saturation, heart rate and hematocrit were not significantly different in G6PD deficient and G6PD sufficient children. The odds of being G6PD deficient were 2.1 times higher in children with scleral icterus than those without (p=0.0351. In conclusion, we determined the prevalence of G6PD deficiency in Nigerian sub-populations. The odds of G6PD deficiency were decreased in Igbo children compared to Yoruba children. There was no association between vital parameters or hematocrit and G6PD deficiency. We found that a history of scleral icterus may increase the odds of G6PD deficiency, but we did not exclude other common causes of icterus such as sickle cell disease or malarial infection.

[Glucose-6-phosphate dehydrogenase deficiency in children: a case report].

Science.gov (United States)

Verdugo L, Patricia; Calvanese T, Marlene; Rodríguez V, Diego; Cárcamo C, Cassandra

2014-02-01

Glucose-6-phosphate dehydrogenase deficiency (G6PD deficiency) is the most common red blood cell (RBC) enzyme disorder. The decrease as well as the absence of the enzyme increase RBC vulnerability to oxidative stress caused by exposure to certain medications or intake of fava beans. Among the most common clinical manifestations of this condition, acute hemolysis, chronic hemolysis, neonatal hyperbilirubinemia, and an asymptomatic form are observed. To analyze the case of a child who presented hemolytic crisis due to favism. A 2 year and 7 month old boy with a history of hyperbilirubinemia during the newborn period with no apparent cause, no family history of hemolytic anemia or parental consanguinity. He presented a prolonged neonatal jaundice and severe anemia requiring RBC transfusion. An intake of fava beans 48 h prior to onset of symptoms was reported. G6PD qualitative determination was compatible with this enzyme deficiency. G6PD deficiency can be highly variable in its clinical presentation, so it is necessary to keep it in mind during the diagnosis of hemolytic anemia at any age.

Pedigree analysis of glucose-6 phosphate dehydrogenase (G6PD deficiency of a Javanese Chinese family in Indonesia

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IDG Ugrasena

2017-02-01

Full Text Available The molecular and pedigree analyses in a Javanese Chinese family were carried oul on glucose-6-phosphate dehydrogenase deficiencies. By method of  MPTP scanning without the sequencing steps, those variants could be confirmed. Two out of three sons were clinically jaundiced at birth due to G6PD deficiency and identified to have a G to T nucleotide change al 1376th nucleotide 01 the G6PD gene (GI376T, corresponding to G6PD Canton. Another son was also identified to have a C to T nucleotide change at 1311st nucleotide 01 the G6PD gene (CI311T, corresponding to a Silent mutation. Their father was normal, but their mother obsorved to have the heleromutation 01 G1376T (G6PD Canton and C1311T (a Silent mutation.

Amla as an antihyperglycemic and hepato-renal protective agent in fluoride induced toxicity

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Rupal A Vasant

2012-01-01

Full Text Available Purpose of the study was to examine the antihyperglycemic and hepato-renal protective effects of Emblica officinalis (Eo fruit as a food supplement in fluoride induced toxicity. Eo fruit powder was incorporated into the diet (2.5, 5 and 10 gm % of fluoride exposed animals for a duration of 30 days. Fluoride exposure caused significant elevation in plasma glucose, serum glutamate oxaloacetate transaminase (SGOT, serum glutamate pyruvate transaminase (SGPT, acid phosphatase (ACP, alkaline phosphatase (ALP activities, hepatic glucose-6-phosphatase (G-6-Pase and decreased hepatic glycogen content, hexokinase activity and antioxidant profiles (hepatic and renal. An inclusion of Eo fruit powder significantly reduced plasma glucose levels, SGOT, SGPT, ACP and ALP activities, hepatic G-6-Pase activity and increased hepatic glycogen content and hexokinase activity. Hepatic and renal antioxidant status of fluoride exposed animals improved upon feeding Eo fruit powder. We, therefore, conclude that E. officinalis fruit could be useful in regulating hyperglycemia and enhances antioxidant status of fluoride exposed animals.

Time course of radiolabeled 2-deoxy-D-glucose 6-phosphate turnover in cerebral cortex of goats

International Nuclear Information System (INIS)

Pelligrino, D.A.; Miletich, D.J.; Albrecht, R.F.

1987-01-01

The vivo dephosphorylation rate of 2-deoxy-D-glucose 6-phosphate (DGP) in the cerebral cortex of goats injected intravenously with radiolabeled 2-deoxy-D-glucose (DG) was investigated. Serial rapidly frozen samples of parietal cortical gray tissue were obtained at regular intervals over time periods from 45 min to 3 h in awake goats or in paralyzed and artificially ventilated goats maintained under 70% N 2 O or pentobarbital sodium anesthesia. The samples were analyzed for glucose content and separate DG and DGP activities. The rate parameters for phosphorylation (k/sup */ 4 ) and dephosphorylation (k/sup */ 4 ) were estimated in each animal. The glucose phosphorylation rate (PR) was calculated over the intervals 3-5 (or 6), 3-10, 3-20, 3-30, and 3-45 min, assuming k/sup */ 4 = O. As the evaluation period was extended beyond 10 min, the calculated PR became increasingly less when compared with that calculated over the 3- to 5- (or 6) min interval (PR/sub i/). Furthermore, as metabolic activity decreased, the magnitude of the error increased such that at 45 min pentobarbital-anesthetize goats underestimated the PR/sub i/ by 46.5% compared with only 23.1 in N 2 O-anesthetized goats. This was also reflected in the >twofold higher k/sup */ 4 /k/sup */ 3 ratio in the pentobarbital vs. N 2 O-anesthetized group. It is concluded that when using the DG method in the goat, DGP dephosphorylation cannot be ignored when employing >10-min evaluation periods

Antidiabetic and Antihyperlipidemic Effects of Clitocybe nuda on Glucose Transporter 4 and AMP-Activated Protein Kinase Phosphorylation in High-Fat-Fed Mice

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Mei-Hsing Chen

2014-01-01

Full Text Available The objective of this study was to evaluate the antihyperlipidemic and antihyperglycemic effects and mechanism of the extract of Clitocybe nuda (CNE, in high-fat- (HF- fed mice. C57BL/6J was randomly divided into two groups: the control (CON group was fed with a low-fat diet, whereas the experimental group was fed with a HF diet for 8 weeks. Then, the HF group was subdivided into five groups and was given orally CNE (including C1: 0.2, C2: 0.5, and C3: 1.0 g/kg/day extracts or rosiglitazone (Rosi or vehicle for 4 weeks. CNE effectively prevented HF-diet-induced increases in the levels of blood glucose, triglyceride, insulin (P<0.001, P<0.01, P<0.05, resp. and attenuated insulin resistance. By treatment with CNE, body weight gain, weights of white adipose tissue (WAT and hepatic triacylglycerol content were reduced; moreover, adipocytes in the visceral depots showed a reduction in size. By treatment with CNE, the protein contents of glucose transporter 4 (GLUT4 were significantly increased in C3-treated group in the skeletal muscle. Furthermore, CNE reduces the hepatic expression of glucose-6-phosphatase (G6Pase and glucose production. CNE significantly increases protein contents of phospho-AMP-activated protein kinase (AMPK in the skeletal muscle and adipose and liver tissues. Therefore, it is possible that the activation of AMPK by CNE leads to diminished gluconeogenesis in the liver and enhanced glucose uptake in skeletal muscle. It is shown that CNE exhibits hypolipidemic effect in HF-fed mice by increasing ATGL expression, which is known to help triglyceride to hydrolyze. Moreover, antidiabetic properties of CNE occurred as a result of decreased hepatic glucose production via G6Pase downregulation and improved insulin sensitization. Thus, amelioration of diabetic and dyslipidemic states by CNE in HF-fed mice occurred by regulation of GLUT4, G6Pase, ATGL, and AMPK phosphorylation.

Polo-like kinase 1 (PLK1) and protein phosphatase 6 (PP6) regulate DNA-dependent protein kinase catalytic subunit (DNA-PKcs) phosphorylation in mitosis.

Science.gov (United States)

Douglas, Pauline; Ye, Ruiqiong; Trinkle-Mulcahy, Laura; Neal, Jessica A; De Wever, Veerle; Morrice, Nick A; Meek, Katheryn; Lees-Miller, Susan P

2014-06-25

The protein kinase activity of the DNA-PKcs (DNA-dependent protein kinase catalytic subunit) and its autophosphorylation are critical for DBS (DNA double-strand break) repair via NHEJ (non-homologous end-joining). Recent studies have shown that depletion or inactivation of DNA-PKcs kinase activity also results in mitotic defects. DNA-PKcs is autophosphorylated on Ser2056, Thr2647 and Thr2609 in mitosis and phosphorylated DNA-PKcs localize to centrosomes, mitotic spindles and the midbody. DNA-PKcs also interacts with PP6 (protein phosphatase 6), and PP6 has been shown to dephosphorylate Aurora A kinase in mitosis. Here we report that DNA-PKcs is phosphorylated on Ser3205 and Thr3950 in mitosis. Phosphorylation of Thr3950 is DNA-PK-dependent, whereas phosphorylation of Ser3205 requires PLK1 (polo-like kinase 1). Moreover, PLK1 phosphorylates DNA-PKcs on Ser3205 in vitro and interacts with DNA-PKcs in mitosis. In addition, PP6 dephosphorylates DNA-PKcs at Ser3205 in mitosis and after IR (ionizing radiation). DNA-PKcs also phosphorylates Chk2 on Thr68 in mitosis and both phosphorylation of Chk2 and autophosphorylation of DNA-PKcs in mitosis occur in the apparent absence of Ku and DNA damage. Our findings provide mechanistic insight into the roles of DNA-PKcs and PP6 in mitosis and suggest that DNA-PKcs' role in mitosis may be mechanistically distinct from its well-established role in NHEJ.

WIP1 phosphatase as pharmacological target in cancer therapy

Czech Academy of Sciences Publication Activity Database

Pecháčková, Soňa; Burdová, Kamila; Macůrek, Libor

2017-01-01

Roč. 95, č. 6 (2017), s. 589-599 ISSN 0946-2716 R&D Projects: GA MŠk 7F14061; GA MŠk LO1220 Institutional support: RVO:68378050 Keywords : Cancer * Phosphatase * Checkpoint * DNA damage response * Inhibitor * p53 Subject RIV: EB - Genetics ; Molecular Biology OBOR OECD: Medicinal chemistry Impact factor: 4.686, year: 2016

Phosphatase activity in Antarctica soil samples as a biosignature of extant life

Science.gov (United States)

Sato, Shuji; Itoh, Yuki; Takano, Yoshinori; Fukui, Manabu; Kaneko, Takeo; Kobayashi, Kensei

Microbial activities have been detected in such extreme terrestrial environments as deep lithosphere, a submarine hydrothermal systems, stratosphere, and Antarctica. Microorganisms have adapted to such harsh environments by evolving their biomolecules. Some of these biomolecules such as enzymes might have different characteristics from those of organisms in ordinary environments. Many biosignatures (or biomarkers) have been proposed to detect microbial activities in such extreme environments. A number of techniques are proposed to evaluate biological activities in extreme environments including cultivation methods, assay of metabolism, and analysis of bioorganic compounds like amino acids and DNA. Enzyme activities are useful signature of extant life in extreme environments. Among many enzymes, phosphatase could be a good indicator of biological activities, since phosphate esters are essential for all the living terrestrial organisms. In addition, alkaline phosphatase is known as a typical zinc-containing metalloenzyme and quite stable in environments. We analyzed phosphatase activities in Antarctica soil samples to see whether they can be used as biosignatures for extant life. In addition, we characterized phosphatases extracted from the Antarctica soil samples, and compared with those obtained from other types of environments. Antarctica surface environments are quite severe environments for life since it is extremely cold and dry and exposed to strong UV and cosmic rays. We tried to evaluate biological activities in Antarctica by measuring phosphatase activities. Surface soil samples are obtained at the Sites 1-8 near Showa Base in Antarctica during the 47th Japan Antarctic exploration mission in 2005-6. Activities of acid phosphatase (ACP) and alkaline phosphatase (ALP) are measured spectrophotometrically after mixing the powdered sample and p-nitrophenyl phosphate solution (pH 6.5 for ACP, pH 8.0 for ALP). ALP was characterized after extraction from soils with

Chloroquine Increases Glucose Uptake via Enhancing GLUT4 Translocation and Fusion with the Plasma Membrane in L6 Cells

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Qi Zhou

2016-05-01

Full Text Available Background/Aims: Chloroquine can induce an increase in the cellular uptake of glucose; however, the underlying mechanism is unclear. Methods: In this study, translocation of GLUT4 and intracellular Ca2+ changes were simultaneously observed by confocal microscope in L6 cells stably over-expressing IRAP-mOrange. The GLUT4 fusion with the plasma membrane (PM was traced using HA-GLUT4-GFP. Glucose uptake was measured using a cell-based glucose uptake assay. GLUT4 protein was detected by Western blotting and mRNA level was detected by RT-PCR. Results: We found that chloroquine induced significant increases in glucose uptake, glucose transporter GLUT4 translocation to the plasma membrane (GTPM, GLUT4 fusion with the PM, and intracellular Ca2+ in L6 muscle cells. Chloroquine-induced increases of GTPM and intracellular Ca2+ were inhibited by Gallein (Gβγ inhibitor and U73122 (PLC inhibitor. However, 2-APB (IP3R blocker only blocked the increase in intracellular Ca2+ but did not inhibit GTPM increase. These results indicate that chloroquine, via the Gβγ-PLC-IP3-IP3R pathway, induces elevation of Ca2+, and this Ca2+ increase does not play a role in chloroqui-ne-evoked GTPM increase. However, GLUT4 fusion with the PM and glucose uptake were significantly inhibited with BAPTA-AM. This suggests that Ca2+ enhances GLUT4 fusion with the PM resulting in glucose uptake increase. Conclusion: Our data indicate that chloroquine via Gβγ-PLC-IP3-IP3R induces Ca2+ elevation, which in turn promotes GLUT4 fusion with the PM. Moreover, chloroquine can enhance GLUT4 trafficking to the PM. These mechanisms eventually result in glucose uptake increase in control and insulin-resistant L6 cells. These findings suggest that chloroquine might be a potential drug for improving insulin tolerance in diabetic patients.

Deletion of the Glucose-6-Phosphate Dehydrogenase Gene KlZWF1 Affects both Fermentative and Respiratory Metabolism in Kluyveromyces lactis▿

Science.gov (United States)

Saliola, Michele; Scappucci, Gina; De Maria, Ilaria; Lodi, Tiziana; Mancini, Patrizia; Falcone, Claudio

2007-01-01

In Kluyveromyces lactis, the pentose phosphate pathway is an alternative route for the dissimilation of glucose. The first enzyme of the pathway is the glucose-6-phosphate dehydrogenase (G6PDH), encoded by KlZWF1. We isolated this gene and examined its role. Like ZWF1 of Saccharomyces cerevisiae, KlZWF1 was constitutively expressed, and its deletion led to increased sensitivity to hydrogen peroxide on glucose, but unlike the case for S. cerevisiae, the Klzwf1Δ strain had a reduced biomass yield on fermentative carbon sources as well as on lactate and glycerol. In addition, the reduced yield on glucose was associated with low ethanol production and decreased oxygen consumption, indicating that this gene is required for both fermentation and respiration. On ethanol, however, the mutant showed an increased biomass yield. Moreover, on this substrate, wild-type cells showed an additional band of activity that might correspond to a dimeric form of G6PDH. The partial dimerization of the G6PDH tetramer on ethanol suggested the production of an NADPH excess that was negative for biomass yield. PMID:17085636

Src inhibitor herbimycin A prevents 132.7 kDa tyrosine phosphatase activity in Ramos Burkitt's lymphoma B cell line

International Nuclear Information System (INIS)

Hristov, K.; Mitev, V.; Knox, K.

2006-01-01

Reversible tyrosine phosphorylation, regulation of expression and proteolytic cleavage control tyrosine phosphatase contribution for the signalling pathways of B-cell antigen receptor (BCR), and CD40 during B cell selection. We used Ramos-BL B cell line to determine whether BCR and CD40 stimulation, or inhibition of the Src - tyrosine kinase, tyrosine phosphatase and caspase activity have an effect on the tyrosine phosphatase activities determined on in-gel phosphatase assay. The tyrosine phosphatase activities present in whole cell lysates of Ramos-BL B cells following treatment with 20 μg/ml anti-IgM, 1 μg/ml anti-CD40, 10 μM herbimycin A, 178 μM vanadate,100 μM phenylarsine oxide and 10 μM zVAD-fmk were detected with an in-gel phosphatase assay. Seven major tyrosine phosphatase activities with approximate molecular weight of 132.7, 63.9, 60.3, 54.2, 49.7, 44.6, and 39 kDa are present in whole cell lysates of Ramos-BL B cells. Treatment with Src-PTK inhibitor herbimycin A prevents 132.7 kDa tyrosine phosphatase activity. We conclude that the catalytic activity of Src-PTK in Ramos-BL B cells is critical for the presence of this 132.7 kDa tyrosine phosphatase activity. (authors)

2,3-diphosphoglycerate phosphatase activity of phosphoglycerate mutase: stimulation by vanadate and phosphate

International Nuclear Information System (INIS)

Stankiewicz, P.J.; Gresser, M.J.; Tracey, A.S.; Hass, L.F.

1987-01-01

The binding of inorganic vanadate (V/sub i/) to rabbit muscle phosphoglycerate mutase (PGM), studied by using 51 V nuclear magnetic resonance spectroscopy, shows a sigmoidal dependence on vanadate concentration with a stoichiometry of four vanadium atoms per PGM molecule at saturating [V/sub i/]. The data are consistent with binding of one divanadate ion to each of the two subunits of PGM in a noncooperative manner with an intrinsic dissociation constant of 4 x 10 -6 M. The relevance of this result to other studies which have shown that the V/sub i/-stimulated 2,3-diphosphoglycerate (2,3-DPG) phosphatase activity of PGM has a sigmoidal dependence on [V/sub i/] with a Hill coefficient of 2.0 is discussed. At pH 7.0, inorganic phosphate has little effect on the 2,3-DPG phosphatase activity of PGM, even at concentrations as high as 50 mM. Similarly, 25 μM V/sub i/ has little effect on the phosphatase activity. However, in the presence of 25 μM V/sub i/, a phosphate concentration of 20 mM increases the phosphatase activity by more than 3-fold. This behavior is rationalized in terms of activation of the phosphatase activity by a phosphate/vanadate mixed anhydride. This interpretation is supported by the observation of strong activation of the phosphatase activity by inorganic pyrophosphate. A molecular mechanism for the observed effects of vanadate is proposed, and the relevance of this study to the possible use of vanadate as a therapeutic agent for the treatment of sickle cell anemia is discussed

Biochemical relationships between bone turnover markers and blood glucose in patients with type 2 diabetes mellitus.

Science.gov (United States)

Hussein, Rasha M

2017-11-01

Patients with type 2 diabetes mellitus develop many complications including osteopenia, which is associated with high fracture risk. Osteocalcin is a non collagenous protein derived from the osteoblasts. Recently, it was found that osteocalcin enhances the pancreatic beta cell proliferation, insulin secretion and protection against type 2 diabetes. Investigation of the association of serum osteocalcin and other bone turnover markers with blood glucose level and diabetes mellitus duration in type 2 diabetic patients. Twenty diagnosed type 2 diabetic patients together with 20 healthy controls were enrolled in this study. Serum osteocalcin, alkaline phosphatase activity and calcium concentrations were measured by commercial ELISA kits. The results showed that type 2 diabetic patients exhibited a significantly lower serum osteocalcin and calcium (p=0.0001 and 0.002 respectively) and a higher alkaline phosphatase (p=0.008) compared to the controls. Multiple linear regression analysis revealed that serum osteocalcin was inversely associated with fasting blood glucose and Diabetes Mellitus duration (β=- 0.018; p=0.007 and β=- 0.085; p=0.014 respectively) in Type 2 diabetic patients. In addition, alkaline phosphatase was positively associated (β=0.828; p=0.015) while serum calcium was negatively associated (β=- 0.046; p=0.048) with Diabetes Mellitus duration. These results refer to the strong association between diabetes and bone turnover markers and call for monitoring of diabetes-associated osteopenia in type 2 diabetic patients. Copyright © 2017 Diabetes India. Published by Elsevier Ltd. All rights reserved.

Bridging the Gap Between Protein Carboxyl Methylation and Phospholipid Methylation to Understand Glucose-Stimulated Insulin Secretion From the Pancreatic β Cell

OpenAIRE

Kowluru, Anjaneyulu

2007-01-01

Recent findings have implicated post-translational modifications at C-terminal cysteines [e.g., methylation] of specific proteins [e.g., G-proteins] in glucose-stimulated insulin secretion [GSIS]. Furthermore, methylation at the C-terminal leucine of the catalytic subunit of protein phosphatase 2A [PP2Ac] has also been shown to be relevant for GSIS. In addition to these two classes of protein methyl transferases, a novel class of glucose-activated phospholipid methyl transferases have also be...

Preparative resolution of D,L-threonine catalyzed by immobilized phosphatase.

Science.gov (United States)

Scollar, M P; Sigal, G; Klibanov, A M

1985-03-01

Hydrolysis of L- and D-O-phosphothreonines catalyzed by four different phosphatases, alkaline phosphatases from calf intestine and E. coli and acid phosphatases from wheat germ and potato, has been kinetically studied. Alkaline phosphatases were found to have comparable reactivities towards the optical isomers. On the other hand, both acid phosphatases displayed a marked stereoselectivity, hydrolyzing the L-ester much faster than its D counterpart. Wheat germ acid phosphatase was the most stereoselective enzyme: V(L)/V(D) = 24 and K(m,L)/K(m,D) = 0.17. This enzyme was immobilized (in k-carrageenan gel, followed by crosslinking with glutaraldehyde) and used for the preparative resolution of D,L-threonine: the latter was first chemically O-phosphorylated and then asymmetrically hydrolyzed by the immobilized phosphatase. As a result, gram quantities of L-threonine of high optical purity and O-phospho-D-threonine were prepared. Immobilized wheat germ phosphatase has been tested for the resolution of other racemic alcohols: serine, 2-amino-1-butanol, 1-amino-2-propanol, 2-octanol, and menthol. In all those cases, the enzyme was either not sufficiently stereoselective or too slow for preparative resolutions.

Purification and investigation of some kinetic properties of glucose-6-phosphate dehydrogenase from parsley (Petroselinum hortense) leaves.

Science.gov (United States)

Coban, T Abdül Kadir; Ciftçi, Mehmet; Küfrevioğlu, O Irfan

2002-05-01

In this study, glucose-6-phosphate dehydrogenase (D-glucose-6-phosphate: NADP+ oxidoreductase, EC 1.1.1.49; G6PD) was purified from parsley (Petroselinum hortense) leaves, and analysis of the kinetic behavior and some properties of the enzyme were investigated. The purification consisted of three steps: preparation of homogenate, ammonium sulfate fractionation, and DEAE-Sephadex A50 ion exchange chromatography. The enzyme was obtained with a yield of 8.79% and had a specific activity of 2.146 U (mg protein)(-1). The overall purification was about 58-fold. Temperature of +4 degrees C was maintained during the purification process. Enzyme activity was spectrophotometrically measured according to the Beutler method, at 340 nm. In order to control the purification of enzyme, SDS-polyacrylamide gel electrophoresis was carried out in 4% and 10% acrylamide for stacking and running gel, respectively. SDS-polyacrylamide gel electrophoresis showed a single band for enzyme. The molecular weight was found to be 77.6 kDa by Sephadex G-150 gel filtration chromatography. A protein band corresponding to a molecular weight of 79.3 kDa was obtained on SDS-polyacrylamide gel electrophoresis. For the enzymes, the stable pH, optimum pH, and optimum temperature were found to be 6.0, 8.0, and 60 degrees C, respectively. Moreover, KM and Vmax values for NADP+ and G6-P at optimum pH and 25 degrees C were determined by means of Lineweaver-Burk graphs. Additionally, effects of streptomycin sulfate and tetracycline antibiotics were investigated for the enzyme activity of glucose-6-phosphate dehydrogenase in vitro.

Characterization of a unique class C acid phosphatase from Clostridium perfringens.

Science.gov (United States)

Reilly, Thomas J; Chance, Deborah L; Calcutt, Michael J; Tanner, John J; Felts, Richard L; Waller, Stephen C; Henzl, Michael T; Mawhinney, Thomas P; Ganjam, Irene K; Fales, William H

2009-06-01

Clostridium perfringens is a gram-positive anaerobe and a pathogen of medical importance. The detection of acid phosphatase activity is a powerful diagnostic indicator of the presence of C. perfringens among anaerobic isolates; however, characterization of the enzyme has not previously been reported. Provided here are details of the characterization of a soluble recombinant form of this cell-associated enzyme. The denatured enzyme was approximately 31 kDa and a homodimer in solution. It catalyzed the hydrolysis of several substrates, including para-nitrophenyl phosphate, 4-methylumbelliferyl phosphate, and 3' and 5' nucleoside monophosphates at pH 6. Calculated K(m)s ranged from 0.2 to 0.6 mM with maximum velocity ranging from 0.8 to 1.6 micromol of P(i)/s/mg. Activity was enhanced in the presence of some divalent cations but diminished in the presence of others. Wild-type enzyme was detected in all clinical C. perfringens isolates tested and found to be cell associated. The described enzyme belongs to nonspecific acid phosphatase class C but is devoid of lipid modification commonly attributed to this class.

Genetic variation in GIPR influences the glucose and insulin responses to an oral glucose challenge

DEFF Research Database (Denmark)

Saxena, Richa; Hivert, Marie-France; Langenberg, Claudia

2010-01-01

Glucose levels 2 h after an oral glucose challenge are a clinical measure of glucose tolerance used in the diagnosis of type 2 diabetes. We report a meta-analysis of nine genome-wide association studies (n = 15,234 nondiabetic individuals) and a follow-up of 29 independent loci (n = 6,958-30,620)......Glucose levels 2 h after an oral glucose challenge are a clinical measure of glucose tolerance used in the diagnosis of type 2 diabetes. We report a meta-analysis of nine genome-wide association studies (n = 15,234 nondiabetic individuals) and a follow-up of 29 independent loci (n = 6...

iTRAQ-based proteomic profile analysis of ISKNV-infected CPB cells with emphasizing on glucose metabolism, apoptosis and autophagy pathways.

Science.gov (United States)

Wu, Shiwei; Yu, Lujun; Fu, Xiaozhe; Yan, Xi; Lin, Qiang; Liu, Lihui; Liang, Hongru; Li, Ningqiu

2018-05-04

Infectious spleen and kidney necrosis virus (ISKNV) has caused significant losses in the cultured mandarin fish (Siniperca chuatsi) industry. The molecular mechanisms that underlie interaction between ISKNV and hosts are not fully understood. In this study, the proteomic profile of CPB cells at progressive time points after ISKNV infection was analyzed by isobaric tags for relative and absolute quantitation (iTRAQ). A total of 2731 proteins corresponding to 6363 novel peptides (false discovery rate analysis of several proteins as G6PDH, β-tubulin and RPL11 were done to validate iTRAQ data. Among those differentially expressed proteins, several glucose metabolism-related enzymes, including glucose-6-phosphate dehydrogenase (G6PDH), pyruvate dehydrogenase phosphatase (PDP) and fumarate hydratase (FH), were up-regulated, while pyruvate dehydrogenase kinase (PDK) and enolase (ENO) were down-regulated at 24 h poi, suggesting that ISKNV enhanced glucose metabolism in CPB cells in early-stage infection. Simultaneously, expression of apoptosis-related proteins including Caspase 8, phosphoinositide 3-kinases (PI3Ks), and regulatory-associated protein of mTOR-like isoform X3 changed upon ISKNV infection, indicating that ISKNV induced apoptosis of CPB cells. Autophagy-related proteins including LC3 and PI3Ks were up-regulated at 24 h poi, indicating that ISKNV induced autophagy of CPB cells in early-stage infection. These findings may improve the understanding of ISKNV and host interaction and help clarify its pathogenesis mechanisms. Copyright © 2018. Published by Elsevier Ltd.

Rasburicase-induced Hemolytic Anemia in an Adolescent With Unknown Glucose-6-Phosphate Dehydrogenase Deficiency.

Science.gov (United States)

Akande, Manzilat; Audino, Anthony N; Tobias, Joseph D

2017-01-01

Rasburicase, used in the prevention and treatment of tumor lysis syndrome (TLS), may cause hemolytic anemia and methemoglobinemia in patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency. Although routine screening for G6PD deficiency has been recommended, given the turnaround time for test results and the urgency to treat TLS, such screening may not be feasible. We report a case of rasburicase-induced hemolytic anemia without methemoglobinemia in an adolescent with T-cell lymphoblastic lymphoma, TLS, and previously unrecognized G6PD deficiency. Previous reports of hemolytic anemia with rasburicase are reviewed, mechanisms discussed, and preventative strategies presented.

The Glucose-Insulin Control System

DEFF Research Database (Denmark)

Hallgreen, Christine Erikstrup; Korsgaard, Thomas Vagn; Hansen, RenéNormann N.

2008-01-01

This chapter reviews the glucose-insulin control system. First, classic control theory is described briefly and compared with biological control. The following analysis of the control system falls into two parts: a glucose-sensing part and a glucose-controlling part. The complex metabolic pathways...... are divided into smaller pieces and analyzed via several small biosimulation models that describe events in beta cells, liver, muscle and adipose tissue etc. In the glucose-sensing part, the beta cell are shown to have some characteristics of a classic PID controller, but with nonlinear properties...... control, the analysis shows that the system has many more facets than just keeping the glucose concentration within narrow limits. After glucose enters the cell and is phosphorylated to glucose-6-phosphate, the handling of glucose-6-phosphate is critical for glucose regulation. Also, this handling...

Intermittent hypoxia impairs glucose homeostasis in C57BL6/J mice: partial improvement with cessation of the exposure.

Science.gov (United States)

Polak, Jan; Shimoda, Larissa A; Drager, Luciano F; Undem, Clark; McHugh, Holly; Polotsky, Vsevolod Y; Punjabi, Naresh M

2013-10-01

Obstructive sleep apnea is associated with insulin resistance, glucose intolerance, and type 2 diabetes mellitus. Although several studies have suggested that intermittent hypoxia in obstructive sleep apnea may induce abnormalities in glucose homeostasis, it remains to be determined whether these abnormalities improve after discontinuation of the exposure. The objective of this study was to delineate the effects of intermittent hypoxia on glucose homeostasis, beta cell function, and liver glucose metabolism and to investigate whether the impairments improve after the hypoxic exposure is discontinued. C57BL6/J mice were exposed to 14 days of intermittent hypoxia, 14 days of intermittent air, or 7 days of intermittent hypoxia followed by 7 days of intermittent air (recovery paradigm). Glucose and insulin tolerance tests were performed to estimate whole-body insulin sensitivity and calculate measures of beta cell function. Oxidative stress in pancreatic tissue and glucose output from isolated hepatocytes were also assessed. Intermittent hypoxia increased fasting glucose levels and worsened glucose tolerance by 67% and 27%, respectively. Furthermore, intermittent hypoxia exposure was associated with impairments in insulin sensitivity and beta cell function, an increase in liver glycogen, higher hepatocyte glucose output, and an increase in oxidative stress in the pancreas. While fasting glucose levels and hepatic glucose output normalized after discontinuation of the hypoxic exposure, glucose intolerance, insulin resistance, and impairments in beta cell function persisted. Intermittent hypoxia induces insulin resistance, impairs beta cell function, enhances hepatocyte glucose output, and increases oxidative stress in the pancreas. Cessation of the hypoxic exposure does not fully reverse the observed changes in glucose metabolism.

Phosphatase activity of Poa pratensis seeds. III. Effect of fluoride, citrate, urea and other substances on the activity of acid phosphatase Ia2 and Ia3

Directory of Open Access Journals (Sweden)

Irena Lorenc-Kubis

2015-01-01

Full Text Available Effects of fluoride, citrate, urea and other substances on the activity of acid phosphatase a2 and a3 toward p-nitrophenylphosphate and phenylphosphate were investigated. Both enzymes were inhibited by fluoride, p-chloromercuribenzoate and oxalate. Fluoride inhibited acid phosphatase a2 noncorapetitively with p-mitrophenylphosphate, whereas acid phosphatase a3 showed inhibition of mixed type. Hydrolysis of phenylphosphate by both acid phosphatases was activated by citrate. Cytosine and uridine inhibited the activity of phosphatase a2 toward p-nitrophenylphosphate and phenylphosphate, but no effect was observed in case of acid phosphatase a3. After 30 min. incubation with 4 M urea both enzymes lost about 30% of activity.

Are free glucose and glucose-6-phosphate in milk indicators of specific physiological states in the cow?

DEFF Research Database (Denmark)

Larsen, Torben; Moyes, Kasey M

2015-01-01

that they are not hydrolysis product from lactose post secretion, but rather reflecting the energy status of the mammary epithelial cells pre-secretion. Wide variation in range of these metabolites, that is, from 90 to 630 μM and 5 to 324 μM, for glucose and G6P, respectively, was observed. During the first 21 weeks in milk....... In addition, lactose, protein, fat, citrate and β-hydroxybutyrate were determined and comparisons between these variables were made. Data were analysed using GLM model for the effect of parity, breed, time from last milking and stage of lactation on variations in parameters in milk. Pearson’s correlations...

The upstream enhancer elements of the G6PC promoter are critical for optimal G6PC expression in murine glycogen storage disease type Ia.

Science.gov (United States)

Lee, Young Mok; Pan, Chi-Jiunn; Koeberl, Dwight D; Mansfield, Brian C; Chou, Janice Y

2013-11-01

Glycogen storage disease type-Ia (GSD-Ia) patients deficient in glucose-6-phosphatase-α (G6Pase-α or G6PC) manifest impaired glucose homeostasis characterized by fasting hypoglycemia, growth retardation, hepatomegaly, nephromegaly, hyperlipidemia, hyperuricemia, and lactic acidemia. Two efficacious recombinant adeno-associated virus pseudotype 2/8 (rAAV8) vectors expressing human G6Pase-α have been independently developed. One is a single-stranded vector containing a 2864-bp of the G6PC promoter/enhancer (rAAV8-GPE) and the other is a double-stranded vector containing a shorter 382-bp minimal G6PC promoter/enhancer (rAAV8-miGPE). To identify the best construct, a direct comparison of the rAAV8-GPE and the rAAV8-miGPE vectors was initiated to determine the best vector to take forward into clinical trials. We show that the rAAV8-GPE vector directed significantly higher levels of hepatic G6Pase-α expression, achieved greater reduction in hepatic glycogen accumulation, and led to a better toleration of fasting in GSD-Ia mice than the rAAV8-miGPE vector. Our results indicated that additional control elements in the rAAV8-GPE vector outweigh the gains from the double-stranded rAAV8-miGPE transduction efficiency, and that the rAAV8-GPE vector is the current choice for clinical translation in human GSD-Ia. © 2013.

Incorporation of 14C glucose into glycogen and glucose-6-phosphate dehydrogenase activity in rat brain following carbon monoxide intoxication

International Nuclear Information System (INIS)

Sikorska, M.; Gorzkowski, B.; Szumanska, G.; Smialek, M.

1975-01-01

Incorporation of 14 C glucose into glycogen and glucose-6-phosphate dehydrogenase activity in rat brain following carbon monoxide intoxication was studied. In brains of rats tested on the 20, 30 and 60th minute of exposure to CO and immediately after removal from the chamber the enzyme activity showed no essential deviation from the control level. In the group of rats tested 1 hour after taking them out from the chamber increase of the enzyme activity was noticed, amounting to about 33% of the control value. The brains tested 24 hours after exposure showed the largest increase of the enzyme activity by about 94%. In the next time periods, 48 and 72 hours after intoxication, the enzyme activity was decreasing. The glycogen content in brains of control animals increased 3 hours after CO intoxication by about 69%. The increase of glycogen synthesis was expressed by increase of the total radioactivity, which amounted to 160% of the control value. (Z.M.)

Nuclear factor erythroid 2-related factor 2 deletion impairs glucose tolerance and exacerbates hyperglycemia in type 1 diabetic mice.

Science.gov (United States)

Aleksunes, Lauren M; Reisman, Scott A; Yeager, Ronnie L; Goedken, Michael J; Klaassen, Curtis D

2010-04-01

The transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) induces a battery of cytoprotective genes after oxidative stress. Nrf2 aids in liver regeneration by altering insulin signaling; however, whether Nrf2 participates in hepatic glucose homeostasis is unknown. Compared with wild-type mice, mice lacking Nrf2 (Nrf2-null) have lower basal serum insulin and prolonged hyperglycemia in response to an intraperitoneal glucose challenge. In the present study, blood glucose, serum insulin, urine flow rate, and hepatic expression of glucose-related genes were quantified in male diabetic wild-type and Nrf2-null mice. Type 1 diabetes was induced with a single intraperitoneal dose (200 mg/kg) of streptozotocin (STZ). Histopathology and serum insulin levels confirmed depleted pancreatic beta-cells in STZ-treated mice of both genotypes. Five days after STZ, Nrf2-null mice had higher blood glucose levels than wild-type mice. Nine days after STZ, polyuria occurred in both genotypes with more urine output from Nrf2-null mice (11-fold) than wild-type mice (7-fold). Moreover, STZ-treated Nrf2-null mice had higher levels of serum beta-hydroxybutyrate, triglycerides, and fatty acids 10 days after STZ compared with wild-type mice. STZ reduced hepatic glycogen in both genotypes, with less observed in Nrf2-null mice. Increased urine output and blood glucose in STZ-treated Nrf2-null mice corresponded with enhanced gluconeogenesis (glucose-6-phosphatase and phosphoenolpyruvate carboxykinase)- and reduced glycolysis (pyruvate kinase)-related mRNA expression in their livers. Furthermore, the Nrf2 activator oltipraz lowered blood glucose in wild-type but not Nrf2-null mice administered STZ. Collectively, these data indicate that the absence of Nrf2 worsens hyperglycemia in type I diabetic mice and Nrf2 may represent a therapeutic target for reducing circulating glucose levels.

Correlation of viral RNA biosynthesis with glucose-6-phosphate dehydrogenase activity and host resistance

Czech Academy of Sciences Publication Activity Database

Šindelář, Luděk; Šindelářová, Milada

2002-01-01

Roč. 215, - (2002), s. 862-869 ISSN 0032-0935 R&D Projects: GA ČR GA522/99/1264 Institutional research plan: CEZ:AV0Z5038910 Keywords : Glucose 6 phosphate dehydrogenase * Nicotiana (viral infection) * Plant viruses Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 2.960, year: 2002

Triglyceride synthesis in epididymal adipose tissue: contribution of glucose and non-glucose carbon sources.

Science.gov (United States)

Bederman, Ilya R; Foy, Steven; Chandramouli, Visvanathan; Alexander, James C; Previs, Stephen F

2009-03-06

The obesity epidemic has generated interest in determining the contribution of various pathways to triglyceride synthesis, including an elucidation of the origin of triglyceride fatty acids and triglyceride glycerol. We hypothesized that a dietary intervention would demonstrate the importance of using glucose versus non-glucose carbon sources to synthesize triglycerides in white adipose tissue. C57BL/6J mice were fed either a low fat, high carbohydrate (HC) diet or a high fat, carbohydrate-free (CF) diet and maintained on 2H2O (to determine total triglyceride dynamics) or infused with [6,6-(2)H]glucose (to quantify the contribution of glucose to triglyceride glycerol). The 2H2O labeling data demonstrate that although de novo lipogenesis contributed approximately 80% versus approximately 5% to the pool of triglyceride palmitate in HC- versus CF-fed mice, the epididymal adipose tissue synthesized approximately 1.5-fold more triglyceride in CF- versus HC-fed mice, i.e. 37+/-5 versus 25+/-3 micromolxday(-1). The [6,6-(2)H]glucose labeling data demonstrate that approximately 69 and approximately 28% of triglyceride glycerol is synthesized from glucose in HC- versus CF-fed mice, respectively. Although these data are consistent with the notion that non-glucose carbon sources (e.g. glyceroneogenesis) can make substantial contributions to the synthesis of triglyceride glycerol (i.e. the absolute synthesis of triglyceride glycerol from non-glucose substrates increased from approximately 8 to approximately 26 micromolxday(-1) in HC- versus CF-fed mice), these observations suggest (i) the importance of nutritional status in affecting flux rates and (ii) the operation of a glycerol-glucose cycle.

Glycerol Production from Glucose and Fructose by 3T3-L1 Cells: A Mechanism of Adipocyte Defense from Excess Substrate.

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María del Mar Romero

Full Text Available Cultured adipocytes (3T3-L1 produce large amounts of 3C fragments; largely lactate, depending on medium glucose levels. Increased glycolysis has been observed also in vivo in different sites of rat white adipose tissue. We investigated whether fructose can substitute glucose as source of lactate, and, especially whether the glycerol released to the medium was of lipolytic or glycolytic origin. Fructose conversion to lactate and glycerol was lower than that of glucose. The fast exhaustion of medium glucose was unrelated to significant changes in lipid storage. Fructose inhibited to a higher degree than glucose the expression of lipogenic enzymes. When both hexoses were present, the effects of fructose on gene expression prevailed over those of glucose. Adipocytes expressed fructokinase, but not aldolase b. Substantive release of glycerol accompanied lactate when fructose was the substrate. The mass of cell triacylglycerol (and its lack of change could not justify the comparatively higher amount of glycerol released. Consequently, most of this glycerol should be derived from the glycolytic pathway, since its lipolytic origin could not be (quantitatively sustained. Proportionally (with respect to lactate plus glycerol, more glycerol was produced from fructose than from glucose, which suggests that part of fructose was catabolized by the alternate (hepatic fructose pathway. Earlier described adipose glycerophophatase activity may help explain the glycolytic origin of most of the glycerol. However, no gene is known for this enzyme in mammals, which suggests that this function may be carried out by one of the known phosphatases in the tissue. Break up of glycerol-3P to yield glycerol, may be a limiting factor for the synthesis of triacylglycerols through control of glycerol-3P availability. A phosphatase pathway such as that described may have a potential regulatory function, and explain the production of glycerol by adipocytes in the absence of

Novel glucose biosensor based on a glassy carbon electrode modified with hollow gold nanoparticles and glucose oxidase

International Nuclear Information System (INIS)

Wang, W.; Ying, S.; Zhang, Z.; Huang, S.

2011-01-01

A novel glucose biosensor is presented as that based on a glassy carbon electrode modified with hollow gold nanoparticles (HGNs) and glucose oxidase. The sensor exhibits a better differential pulse voltammetric response towards glucose than the one based on conventional gold nanoparticles of the same size. This is attributed to the good biological conductivity and biocompatibility of HGNs. Under the optimal conditions, the sensor displays a linear range from 2.0 x 10 -6 to 4.6 x 10 -5 M of glucose, with a detection limit of 1.6 x 10 -6 M (S/N = 3). Good reproducibility, stability and no interference make this biosensor applicable to the determination of glucose in samples such as sports drinks. (author)

Prevalence of glucose-6-phosphate dehydrogenase deficiency and diagnostic challenges in 1500 immigrants in Denmark examined for haemoglobinopathies

DEFF Research Database (Denmark)

Warny, Marie; Klausen, Tobias Wirenfeldt; Petersen, Jesper

2015-01-01

Similar to the thalassaemia syndromes, glucose-6-phosphate dehydrogenase (G6PD) deficiency is highly prevalent in areas historically exposed to malaria. In the present study, we used quantitative and molecular methods to determine the prevalence of G6PD deficiency in a population of 1508 immigran...

Domain-to-domain coupling in voltage-sensing phosphatase.

Science.gov (United States)

Sakata, Souhei; Matsuda, Makoto; Kawanabe, Akira; Okamura, Yasushi

2017-01-01

Voltage-sensing phosphatase (VSP) consists of a transmembrane voltage sensor and a cytoplasmic enzyme region. The enzyme region contains the phosphatase and C2 domains, is structurally similar to the tumor suppressor phosphatase PTEN, and catalyzes the dephosphorylation of phosphoinositides. The transmembrane voltage sensor is connected to the phosphatase through a short linker region, and phosphatase activity is induced upon membrane depolarization. Although the detailed molecular characteristics of the voltage sensor domain and the enzyme region have been revealed, little is known how these two regions are coupled. In addition, it is important to know whether mechanism for coupling between the voltage sensor domain and downstream effector function is shared among other voltage sensor domain-containing proteins. Recent studies in which specific amino acid sites were genetically labeled using a fluorescent unnatural amino acid have enabled detection of the local structural changes in the cytoplasmic region of Ciona intestinalis VSP that occur with a change in membrane potential. The results of those studies provide novel insight into how the enzyme activity of the cytoplasmic region of VSP is regulated by the voltage sensor domain.

Glucose-6-Phosphate Dehydrogenase Deficiency A− Variant in Febrile Patients in Haiti

Science.gov (United States)

Carter, Tamar E.; Maloy, Halley; von Fricken, Michael; St. Victor, Yves; Romain, Jean R.; Okech, Bernard A.; Mulligan, Connie J.

2014-01-01

Haiti is one of two remaining malaria-endemic countries in the Caribbean. To decrease malaria transmission in Haiti, primaquine was recently added to the malaria treatment public health policy. One limitation of primaquine is that, at certain doses, primaquine can cause hemolytic anemia in individuals with glucose-6-phosphate dehydrogenase (G6PD) deficiency (G6PDd). In this study, we genotyped two mutations (A376G and G202A), which confer the most common G6PDd variant in West African populations, G6PDd A−. We estimated the frequency of G6PDd A− in a sample of febrile patients enrolled in an on-going malaria study who represent a potential target population for a primaquine mass drug administration. We found that 33 of 168 individuals carried the G6PDd A− allele (includes A− hemizygous males, A− homozygous or heterozygous females) and could experience toxicity if treated with primaquine. These data inform discussions on safe and effective primaquine dosing and future malaria elimination strategies for Haiti. PMID:24891465

Gluconeogenesis during starvation and refeeding phase is affected by previous dietary carbohydrates levels and a glucose stimuli during early life in Siberian sturgeon (Acipenser baerii

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Xiaofang Liang

2017-09-01

of glucose-6-phosphatase (G6Pase, except in GL group. Siberian sturgeon has a full compensatory ability on growth, but this ability would be obstructed by early glucose stimuli when refeeding the low carbohydrate diet after S21.

Cdc14 phosphatase

DEFF Research Database (Denmark)

Machín, Félix; Quevedo Rodriguez, Oliver; Ramos-Pérez, Cristina

2016-01-01

and cancer cells uncontrollably divide, much attention has been put into knocking down CDK activity. However, much less is known on the consequences of interfering with the phosphatases that put an end to the cell cycle. We have addressed in recent years the consequences of transiently inactivating the only...

Glucose-6-Phosphate Dehydrogenase Deficiency and Adrenal Hemorrhage in a Filipino Neonate with Hyperbilirubinemia

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Akira Ohishi

2013-05-01

Full Text Available We report on a Filipino neonate with early onset and prolonged hyperbilirubinemia who was delivered by a vacuum extraction due to a prolonged labor. Subsequent studies revealed adrenal hemorrhage and glucose-6-phosphate dehydrogenase (G6PD deficiency. It is likely that asphyxia and resultant hypoxia underlie the occurrence of adrenal hemorrhage and the clinical manifestation of G6PD deficiency and that the presence of the two events explains the early onset and prolonged hyperbilirubinemia of this neonate. Our results represent the importance of examining possible underlying factors for the development of severe, early onset, or prolonged hyperbilirubinemia.

Subcellular localization of alkaline phosphatase in Bacillus licheniformis 749/C by immunoelectron microscopy with colloidal gold

International Nuclear Information System (INIS)

Tinglu, G.; Ghosh, A.; Ghosh, B.K.

1984-01-01

Subcellular distribution of the alkaline phosphatase of Bacillus licheniformis 749/C was determined by an immunoelectron microscopy method. Anti-alkaline phosphatase antibody labeled with 15- to 18-nm colloidal gold particles (gold-immunoglobulin G [IgG] complex) were used for the study. Both the plasma membrane and cytoplasmic material were labeled with the gold-IgG particles. These particles formed clusters in association with the plasma membrane; in contrast, in the cytoplasm the particles were largely dispersed, and only a few clusters were found. The gold-IgG binding was quantitatively estimated by stereological analysis of labeled, frozen thin sections. This estimation of a variety of control samples showed that the labeling was specific for the alkaline phosphatase. Cluster formation of the gold -IgG particles in association with the plasma membrane suggests that existence of specific alkaline phosphatase binding sites (receptors) in the plasma membrane of B. licheniformis 749/C. 27 references, 6 figures, 1 table

The TriTryp Phosphatome: analysis of the protein phosphatase catalytic domains

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Huxley-Jones Julie

2007-11-01

Full Text Available Abstract Background The genomes of the three parasitic protozoa Trypanosoma cruzi, Trypanosoma brucei and Leishmania major are the main subject of this study. These parasites are responsible for devastating human diseases known as Chagas disease, African sleeping sickness and cutaneous Leishmaniasis, respectively, that affect millions of people in the developing world. The prevalence of these neglected diseases results from a combination of poverty, inadequate prevention and difficult treatment. Protein phosphorylation is an important mechanism of controlling the development of these kinetoplastids. With the aim to further our knowledge of the biology of these organisms we present a characterisation of the phosphatase complement (phosphatome of the three parasites. Results An ontology-based scan of the three genomes was used to identify 86 phosphatase catalytic domains in T. cruzi, 78 in T. brucei, and 88 in L. major. We found interesting differences with other eukaryotic genomes, such as the low proportion of tyrosine phosphatases and the expansion of the serine/threonine phosphatase family. Additionally, a large number of atypical protein phosphatases were identified in these species, representing more than one third of the total phosphatase complement. Most of the atypical phosphatases belong to the dual-specificity phosphatase (DSP family and show considerable divergence from classic DSPs in both the domain organisation and sequence features. Conclusion The analysis of the phosphatome of the three kinetoplastids indicates that they possess orthologues to many of the phosphatases reported in other eukaryotes, including humans. However, novel domain architectures and unusual combinations of accessory domains, suggest distinct functional roles for several of the kinetoplastid phosphatases, which await further experimental exploration. These distinct traits may be exploited in the selection of suitable new targets for drug development to prevent

Acid phosphatase patterns in microfilariae of Onchocerca volvulus s.l. from the Upper Orinoco Basin, Venezuela.

Science.gov (United States)

Yarzàbal, L; Petralanda, I; Arango, M; Lobo, L; Botto, C

1983-06-01

The patterns of acid phosphatase in strains of Onchocerca volvulus s.l. which parasitize an Amerindian population (Yanomami) in Venezuela's Upper Orinoco Basin were examined by using the naphthol AS-TR phosphate method. The study sample consisted of 40 Yanomami inhabiting a savannah area at 950 m above sea level and 21 Yanomami residents of a tropical rainforest area at an altitude of 250 m. Stained intrauterine microfilariae, still within the egg case, exhibited a diffuse distribution of the enzyme in the early stages of embryonic development and a negative reaction at a more developed stage. Four of the five enzyme staining patterns described by Omar (1978) were found in the 3157 microfilariae examined from skin snips. Their distribution was: Type I--17.2%, Type III--0.5%, Type IV--75.6% and Type V--6.6%. No examples of Type II were observed. The results indicate that acid phosphatase patterns of the Upper Orinoco Onchocerca strain most resemble those of strains from Guatemala and Yemen, and are different from the African strains found in Upper Volta and Liberia. The relative frequency of acid phosphatase patterns was modified by cryopreservation of microfilariae.

Overexpression of Human Bone Alkaline Phosphatase in Pichia Pastoris

Science.gov (United States)

Karr, Laurel; Malone, Christine, C.; Rose, M. Franklin (Technical Monitor)

2000-01-01

The Pichiapastoris expression system was utilized to produce functionally active human bone alkaline phosphatase in gram quantities. Bone alkaline phosphatase is a key enzyme in bone formation and biomineralization, yet important questions about its structural chemistry and interactions with other cellular enzymes in mineralizing tissues remain unanswered. A soluble form of human bone alkaline phosphatase was constructed by deletion of the 25 amino acid hydrophobic C-terminal region of the encoding cDNA and inserted into the X-33 Pichiapastoris strain. An overexpression system was developed in shake flasks and converted to large-scale fermentation. Alkaline phosphatase was secreted into the medium to a level of 32mgAL when cultured in shake flasks. Enzyme activity was 12U/mg measured by a spectrophotometric assay. Fermentation yielded 880mgAL with enzymatic activity of 968U/mg. Gel electrophoresis analysis indicates that greater than 50% of the total protein in the fermentation is alkaline phosphatase. A purification scheme has been developed using ammonium sulfate precipitation followed by hydrophobic interaction chromatography. We are currently screening crystallization conditions of the purified recombinant protein for subsequent X-ray diffraction analyses. Structural data should provide additional information on the role of alkaline phosphatase in normal bone mineralization and in certain bone mineralization anomalies.

Incorporation of /sup 14/C glucose into glycogen and glucose-6-phosphate dehydrogenase activity in rat brain following carbon monoxide intoxication

Energy Technology Data Exchange (ETDEWEB)

Sikorska, M; Gorzkowski, B; Szumanska, G; Smialek, M [Polska Akademia Nauk, Warsaw. Centrum Medycyny Doswiadczalnej i Klinicznej; Panstwowy Zaklad Higieny, Warsaw (Poland))

1975-01-01

Incorporation of /sup 14/C glucose into glycogen and glucose-6-phosphate dehydrogenase activity in rat brain following carbon monoxide intoxication was studied. In brains of rats tested on the 20, 30 and 60th minute of exposure to CO and immediately after removal from the chamber the enzyme activity showed no essential deviation from the control level. In the group of rats tested 1 hour after taking them out from the chamber increase of the enzyme activity was noticed, amounting to about 33% of the control value. The brains tested 24 hours after exposure showed the largest increase of the enzyme activity by about 94%. In the next time periods, 48 and 72 hours after intoxication, the enzyme activity was decreasing. The glycogen content in brains of control animals increased 3 hours after CO intoxication by about 69%. The increase of glycogen synthesis was expressed by increase of the total radioactivity, which amounted to 160% of the control value.

Voltage sensitive phosphatases: emerging kinship to protein tyrosine phosphatases from structure-function research

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Kirstin eHobiger

2015-02-01

Full Text Available The transmembrane protein Ci-VSP from the ascidian Ciona intestinalis was described as first member of a fascinating family of enzymes, the voltage sensitive phosphatases (VSPs. Ci-VSP and its voltage-activated homologs from other species are stimulated by positive membrane potentials and dephosphorylate the head groups of negatively charged phosphoinositide phosphates (PIPs. In doing so, VSPs act as control centers at the cytosolic membrane surface, because they intervene in signaling cascades that are mediated by PIP lipids. The characteristic motif CX5RT/S in the active site classifies VSPs as members of the huge family of cysteine-based protein tyrosine phosphatases (PTPs. Although PTPs have already been well characterized regarding both, structure and function, their relationship to VSPs has drawn only limited attention so far. Therefore, the intention of this review is to give a short overview about the extensive knowledge about PTPs in relation to the facts known about VSPs. Here, we concentrate on the structural features of the catalytic domain which are similar between both classes of phosphatases and their consequences for the enzymatic function. By discussing results obtained from crystal structures, molecular dynamics simulations, and mutagenesis studies, a possible mechanism for the catalytic cycle of VSPs is presented based on that one proposed for PTPs. In this way, we want to link the knowledge about the catalytic activity of VSPs and PTPs.

Characterization of a Unique Class C Acid Phosphatase from Clostridium perfringens▿

Science.gov (United States)

Reilly, Thomas J.; Chance, Deborah L.; Calcutt, Michael J.; Tanner, John J.; Felts, Richard L.; Waller, Stephen C.; Henzl, Michael T.; Mawhinney, Thomas P.; Ganjam, Irene K.; Fales, William H.

2009-01-01

Clostridium perfringens is a gram-positive anaerobe and a pathogen of medical importance. The detection of acid phosphatase activity is a powerful diagnostic indicator of the presence of C. perfringens among anaerobic isolates; however, characterization of the enzyme has not previously been reported. Provided here are details of the characterization of a soluble recombinant form of this cell-associated enzyme. The denatured enzyme was ∼31 kDa and a homodimer in solution. It catalyzed the hydrolysis of several substrates, including para-nitrophenyl phosphate, 4-methylumbelliferyl phosphate, and 3′ and 5′ nucleoside monophosphates at pH 6. Calculated Kms ranged from 0.2 to 0.6 mM with maximum velocity ranging from 0.8 to 1.6 μmol of Pi/s/mg. Activity was enhanced in the presence of some divalent cations but diminished in the presence of others. Wild-type enzyme was detected in all clinical C. perfringens isolates tested and found to be cell associated. The described enzyme belongs to nonspecific acid phosphatase class C but is devoid of lipid modification commonly attributed to this class. PMID:19363079

Protein kinase and phosphatase activities of thylakoid membranes

International Nuclear Information System (INIS)

Michel, H.; Shaw, E.K.; Bennett, J.

1987-01-01

Dephosphorylation of the 25 and 27 kDa light-harvesting Chl a/b proteins (LHCII) of the thylakoid membranes is catalyzed by a phosphatase which differs from previously reported thylakoid-bound phosphatases in having an alkaline pH optimum (9.0) and a requirement for Mg 2+ ions. Dephosphorylation of the 8.3 kDa psb H gene product requires a Mg 2+ ion concentration more than 200 fold higher than that for dephosphorylation of LHC II. The 8.3 kDa and 27 kDa proteins appear to be phosphorylated by two distinct kinases, which differ in substrate specificity and sensitivity to inhibitors. The plastoquinone antagonist 2,5-dibromo-3-methyl-6-isopropyl-benzoquinone (DBMIB) inhibits phosphorylation of the 27 kDa LHC II much more readily than phosphorylation of the 8.3 kDa protein. A similar pattern of inhibition is seen for two synthetic oligopeptides (MRKSATTKKAVC and ATQTLESSSRC) which are analogs of the phosphorylation sites of the two proteins. Possible modes of action of DBMIB are discussed. 45 refs., 7 figs., 3 tabs

TCPTP Regulates Insulin Signalling in AgRP Neurons to Coordinate Glucose Metabolism with Feeding.

Science.gov (United States)

Dodd, Garron T; Lee-Young, Robert S; Brüning, Jens C; Tiganis, Tony

2018-04-30

Insulin regulates glucose metabolism by eliciting effects on peripheral tissues as well as the brain. Insulin receptor (IR) signalling inhibits AgRP-expressing neurons in the hypothalamus to contribute to the suppression of hepatic glucose production (HGP) by insulin, whereas AgRP neuronal activation attenuates brown adipose tissue (BAT) glucose uptake. The tyrosine phosphatase TCPTP suppresses IR signalling in AgRP neurons. Hypothalamic TCPTP is induced by fasting and degraded after feeding. Here we assessed the influence of TCPTP in AgRP neurons in the control of glucose metabolism. TCPTP deletion in AgRP neurons ( Agrp -Cre; Ptpn2 fl/fl ) enhanced insulin sensitivity as assessed by the increased glucose infusion rates and reduced HGP during hyperinsulinemic-euglycemic clamps, accompanied by increased [ 14 C]-2-deoxy-D-glucose uptake in BAT and browned white adipose tissue. TCPTP deficiency in AgRP neurons promoted the intracerebroventricular insulin-induced repression of hepatic gluconeogenesis in otherwise unresponsive food-restricted mice yet had no effect in fed/satiated mice where hypothalamic TCPTP levels are reduced. The improvement in glucose homeostasis in Agrp -Cre; Ptpn2 fl/fl mice was corrected by IR heterozygosity ( Agrp -Cre; Ptpn2 fl/fl ; Insr fl/+ ), causally linking the effects on glucose metabolism with the IR signalling in AgRP neurons. Our findings demonstrate that TCPTP controls IR signalling in AgRP neurons to coordinate HGP and brown/beige adipocyte glucose uptake in response to feeding/fasting. © 2018 by the American Diabetes Association.

Glucose-6-phosphate dehydrogenase deficiency and Alzheimer's disease: Partners in crime? The hypothesis.

Science.gov (United States)

Ulusu, N Nuray

2015-08-01

Alzheimer's disease is a multifaceted brain disorder which involves various coupled irreversible, progressive biochemical reactions that significantly reduce quality of life as well as the actual life expectancy. Aging, genetic predispositions, head trauma, diabetes, cardiovascular disease, deficiencies in insulin signaling, dysfunction of mitochondria-associated membranes, cerebrovascular changes, high cholesterol level, increased oxidative stress and free radical formation, DNA damage, disturbed energy metabolism, and synaptic dysfunction, high blood pressure, obesity, dietary habits, exercise, social engagement, and mental stress are noted among the risk factors of this disease. In this hypothesis review I would like to draw the attention on glucose-6-phosphate dehydrogenase deficiency and its relationship with Alzheimer's disease. This enzymopathy is the most common human congenital defect of metabolism and defined by decrease in NADPH+H(+) and reduced form of glutathione concentration and that might in turn, amplify oxidative stress due to essentiality of the enzyme. This most common enzymopathy may manifest itself in severe forms, however most of the individuals with this deficiency are not essentially symptomatic. To understand the sporadic Alzheimer's disease, the writer of this paper thinks that, looking into a crystal ball might not yield much of a benefit but glucose-6-phosphate dehydrogenase deficiency could effortlessly give some clues. Copyright © 2015 Elsevier Ltd. All rights reserved.

The rate of intestinal glucose absorption is correlated with plasma glucose-dependent insulinotropic polypeptide concentrations in healthy men

DEFF Research Database (Denmark)

Wachters-Hagedoorn, Renate E; Priebe, Marion G; Heimweg, Janneke A J

2006-01-01

and slowly available glucose. In a crossover study, glucose, insulin, GLP-1, and GIP concentrations were monitored for 6 h after consumption of glucose, uncooked cornstarch (UCCS) or corn pasta in 7 healthy men. All test meals were naturally labeled with 13C. Using a primed, continuous D-[6,6-2H2]glucose...... in the early postprandial phase (15-90 min) occurred after consumption of glucose. There was a strong positive within-subject correlation between RaEx and GIP concentrations (r = 0.73, P meals. Rapidly and slowly digestible carbohydrates differ considerably in their ability to stimulate...

Glucose-6-phosphate dehydrogenase deficiency: an unusual cause of acute jaundice after paracetamol overdose.

Science.gov (United States)

Phillpotts, Simon; Tash, Elliot; Sen, Sambit

2014-11-01

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is the commonest human enzyme defect causing haemolytic anaemia after exposure to specific triggers. Paracetamol-induced haemolysis in G6PD deficiency is a rare complication and mostly reported in children. We report the first case (to the best of our knowledge) of acute jaundice without overt clinical features of a haemolytic crisis, in an otherwise healthy adult female following paracetamol overdose, due to previously undiagnosed G6PD deficiency. It is important that clinicians consider this condition when a patient presents following a paracetamol overdose with significant and disproportionate jaundice, without transaminitis or coagulopathy. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Biochanin A improves hepatic steatosis and insulin resistance by regulating the hepatic lipid and glucose metabolic pathways in diet-induced obese mice.

Science.gov (United States)

Park, Hee-Sook; Hur, Haeng Jeon; Kim, Soon-Hee; Park, Su-Jin; Hong, Moon Ju; Sung, Mi Jeong; Kwon, Dae Young; Kim, Myung-Sunny

2016-09-01

Natural compounds that regulate peroxisome proliferator-activated receptor alpha (PPARα) have been reported to have beneficial effects in obesity-mediated metabolic disorders. In this study, we demonstrated that biochanin A (BA), an agonist of PPAR-α, improved hepatic steatosis and insulin resistance by regulating hepatic lipid and glucose metabolism. C57BL/6 mice were fed a normal chow diet, a high-fat diet (HFD), and an HFD supplemented with 0.05% BA for 12 weeks. Histological and biochemical examinations indicated that BA prevented obesity-induced hepatic steatosis and insulin resistance in HFD-fed mice. BA stimulated the transcriptional activation of PPAR-α in vitro and increased the expression of PPAR-α and its regulatory proteins in the liver. CE-TOF/MS analyses indicated that BA administration promoted the recovery of metabolites involved in phosphatidylcholine synthesis, lipogenesis, and beta-oxidation in the livers of obese mice. BA also suppressed the levels of gluconeogenesis-related metabolites and the expression of the associated enzymes, glucose 6-phosphatase and pyruvate kinase. Taken together, these results showed that BA ameliorated metabolic disorders such as hepatic steatosis and insulin resistance by modulating lipid and glucose metabolism in diet-induced obesity. Thus, BA may be a potential therapeutic agent for the prevention of obesity-mediated hepatic steatosis and insulin resistance. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Metabolism of tritiated D-glucose in rat erythrocytes

International Nuclear Information System (INIS)

Manuel y Keenoy, B.; Malaisse-Lagae, F.; Malaisse, W.J.

1991-01-01

The metabolism of D-[U-14C]glucose, D-[1-14C]glucose, D-[6-14C]glucose, D-[1-3H]glucose, D-[2-3H]glucose, D-[3-3H]glucose, D-[3,4-3H]glucose, D-[5-3H]glucose, and D-[6-3H]glucose was examined in rat erythrocytes. There was a fair agreement between the rate of 3HOH production from either D-[3-3H]glucose and D-[5-3H]glucose, the decrease in the 2,3-diphosphoglycerate pool, its fractional turnover rate, the production of 14C-labeled lactate from D-[U-14C]glucose, and the total lactate output. The generation of both 3HOH and tritiated acidic metabolites from D-[3,4-3H]glucose indicated incomplete detritiation of the C4 during interconversion of fructose-1,6-bisphosphate and triose phosphates. Erythrocytes unexpectedly generated 3HOH from D-[6-3H]glucose, a phenomenon possibly attributable to the detritiation of [3-3H]pyruvate in the reaction catalyzed by glutamate pyruvate transaminase. The production of 3HOH from D-[2-3H]glucose was lower than that from D-[5-3H]glucose, suggesting enzyme-to-enzyme tunneling of glycolytic intermediates in the hexokinase/phosphoglucoisomerase/phosphofructokinase sequence. The production of 3HOH from D-[1-3H]glucose largely exceeded that of 14CO2 from D-[1-14C]glucose, a situation tentatively ascribed to the generation of 3HOH in the phosphomannoisomerase reaction. It is further speculated that the adjustment in specific radioactivity of D-[1-3H]glucose-6-phosphate cannot simultaneously match the vastly different degrees of isotopic discrimination in velocity at the levels of the reactions catalyzed by either glucose-6-phosphate dehydrogenase or phosphoglucoisomerase. The interpretation of the present findings thus raises a number of questions, which are proposed as a scope for further investigations

The Mycobacterium tuberculosis Complex has a Pathway for the Biosynthesis of 4-Formamido-4,6-Dideoxy-d-Glucose.

Science.gov (United States)

Brown, Haley A; Vinogradov, Evgeny; Gilbert, Michel; Holden, Hazel M

2018-05-15

Recent studies have demonstrated that the O-antigens of some pathogenic bacteria such as Brucella abortus, Francisella tularensis, and Campylobacter jejuni contain quite unusual N-formylated sugars (3-formamido-3,6-dideoxy-d-glucose or 4-formamido-4,6-dideoxy-d-glucose). Typically, four enzymes are required for the formation of such sugars: a thymidylyltransferase, a 4,6-dehydratase, a pyridoxal 5'-phosphate or PLP-dependent aminotransferase, and an N-formyltransferase. To date, there have been no published reports of N-formylated sugars associated with Mycobacterium tuberculosis. A recent investigation from our laboratories, however, has demonstrated that one gene product from M. tuberculosis, Rv3404c, functions as a sugar N-formyltransferase. Given that M. tuberculosis produces l-rhamnose, both a thymidylyltransferase (Rv0334) and a 4,6-dehydratase (Rv3464) required for its formation have been identified. Thus, there is one remaining enzyme needed for the production of an N-formylated sugar in M. tuberculosis, namely a PLP-dependent aminotransferase. Here we demonstrate that the M. tuberculosis rv3402c gene encodes such an enzyme. Our data prove that M. tuberculosis contains all of the enzymatic activities required for the formation of dTDP-4-formamido-4,6-dideoxy-d-glucose. Indeed, the rv3402c gene product likely contributes to virulence or persistence during infection, though its temporal expression and location remain to be determined. This article is protected by copyright. All rights reserved. © 2018 The Protein Society.

The tillage effect on the soil acid and alkaline phosphatase activity

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Lacramioara Oprica

2011-12-01

Full Text Available Phosphatases (acid and alkaline are important in soils because these extracellular enzymes catalyze the hydrolysis of organic phosphate esters to orthophosphate; thus they form an important link between biologically unavailable and mineral phosphorous. Phosphatase activity is sensitive to environmental perturbations such as organic amendments, tillage, waterlogging, compaction, fertilizer additions and thus it is often used as an environmental indicator of soil quality in riparian ecosystems. The aim of the study was to assess the effect of tillage systems on phosphatases activity in a field experiment carried out in Ezăreni farm. The phosphatase activitiy were determined at two depths (7-10 cm and 15-25cm layers of a chernozem soil submitted to conventional tillage (CT in a fertilised and unfertilised experiment. Monitoring soil alkaline phosphatase activity showed, generally, the same in fertilized soil profiles collected from both depths; the values being extremely close. In unfertilized soils, alkaline phosphatase activity is different only in soils that were exposed to unconventional work using disc harrows and 30cm tillage. Both works type (no tillage and conventional tillage cause an intense alkaline phosphatase activity in 7-10 cm soil profile. Acid phosphatase activity is highly fluctuating in both fertilized as well unfertilized soil, this enzyme being influenced by the performed works.

Membrane-bound 2,3-diphosphoglycerate phosphatase of human erythrocytes.

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Schröter, W; Neuvians, M

1970-12-01

Gradual osmotic hemolysis of human erythrocytes reduces the cell content of whole protein, hemoglobin, 2,3-diphosphoglycerate and triosephosphate isomerase extensively, but not that of membrane protein and 2,3-diphosphoglycerate phosphatase. After the refilling of the ghosts with 2,3-diphosphoglycerate and reconstitution of the membrane, the 2,3-diphosphoglycerate phosphatase activity equals that of intact red cells. The membrane-bound 2,3-diphosphoglycerate phosphatase can be activated by sodium hyposulfite. The enzyme system of ghosts seems to differ from that of intact red cells with regard to the optima of pH and temperature. It remains to be elucidated if the membrane binding of the 2,3-diphosphoglycerate phosphatase is related to the transfer of inorganic phosphate across the red cell membrane.

Improved glycemic control, pancreas protective and hepatoprotective effect by traditional poly-herbal formulation “Qurs Tabasheer” in streptozotocin induced diabetic rats

Science.gov (United States)

2013-01-01

Background The present study was undertaken to evaluate the antihyperglycemic, antihyperlipidemic and hepatoprotective effect of a traditional unani formulation “Qurs Tabasheer” in streptozotocin (STZ) induced diabetic wistar rats. Up till now no study was undertaken to appraise the efficacy of “Qurs Tabasheer” in the diabetic rats. Qurs Tabasheer is a unani formulation restraining preparations from five various herbs namely Tukhme Khurfa (Portulaca oleracea seed), Gule Surkh (Rosa damascena flower), Gulnar (Punica granatum flower), Tabasheer (Bambusa arundinasia dried exudate on node), Tukhme Kahu (Lactuca sativa Linn seed). Methods Effect of Qurs Tabasheer was assessed in STZ (60 mg/kg, i.p single shot) induced diabetic wistar rats. STZ produced a marked increase in the serum glucose, Total Cholesterol, LDL cholesterol, VLDL Cholesterol, Triglycerides and trim down the HDL level. We have weighed up the effect of Qurs Tabasheer on hepatic activity through estimating levels of various liver enzymes viz. Hexokinase, Glucose-6-Phosphatase and Fructose-1-6-biphosphatase in STZ diabetic wistar rats. Results In STZ-induced diabetic wistar rats level of Hexokinase, and Glucose-6-Phosphatase was decreased to a significant level while the level of fructose-1-6-biphophatase was augmented. Therapy with Qurs Tabasheer for 28 days to STZ-induced diabetic rats significantly reduces the level of serum glucose, total cholesterol, triglycerides, glucose-6-phosphatase and fructose-1-6-biphosphatase, while magnitude of HDL cholesterol and hexokinase was amplified. Conclusion Antihyperglycemic, antihyperlipidemic activity of Qurs Tabasheer extract in STZ- induced wistar rats was found to be more effective than standard oral hypoglycemic drug Glimepiride. PMID:23305114

Subcellular localisation and properties of histone phosphate phosphatase in human polymorphonuclear leukocytes: alterations in pregnancy and chronic granulocytic leukaemia and relationship to alkaline phosphatase

International Nuclear Information System (INIS)

Smith, G.P.; Peters, T.J.

1981-01-01

Using [ 32 P]histone as substrate, an assay for histone phosphate phosphatase was optimised for human polymorphonuclear leukocytes. Kinetic studies showed that the activity was optimal at pH 6.8, was stimulated by Mn 2+ and Co 2+ , and inhibited by sodium sulphite and zinc chloride. The apparent Ksub(m) of the enzyme for histone phosphate was 0.89 μmol/l. (Auth.)

Glucose-6-phosphate dehydrogenase deficiency in neonatal hyperbilirubinaemia: Hacettepe experıence.

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Celik, H Tolga; Günbey, Ceren; Unal, Sule; Gümrük, Fatma; Yurdakök, Murat

2013-05-01

The aim of this study was to investigate the prevalence of glucose-6-phospate dehydrogenase (G6PD) deficiency in newborn infants with neonatal hyperbilirubinaemia and to compare the clinical features of G6PD-deficient and G6PD-normal newborn infants. A total of 4906 term and preterm neonates with indirect hyperbilirubinaemia were retrospectively evaluated according to demographic, neonatal features, bilirubin levels, erythrocyte G6PD levels, other risk factors and treatments. Among 4906 newborn infants with indirect hyperbilirubinaemia, 55 (1.12%) neonates were G6PD-deficient. In our study, no statistically significant difference was detected between G6PD-deficient and G6PD-normal infants in relation to the time of onset of jaundice, bilirubin levels and duration of phototherapy. However, the incidence of exchange transfusion in G6PD-deficient infants was 16.4% while it was only 3.3% in G6PD normal infants (P G6PD must be ordered to all newborns who are receiving phototherapy and especially to those who are coming from the high incident geographical regions and less responsive to phototherapy. © 2013 The Authors. Journal of Paediatrics and Child Health © 2013 Paediatrics and Child Health Division (Royal Australasian College of Physicians).

Characterization of Human Bone Alkaline Phosphatase in Pichia Pastoris

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Malone, Christine C.; Ciszak, Eva; Karr, Laurel J.

1999-01-01

A soluble form of human bone alkaline phosphatase has been expressed in a recombinant strain of the methylotrophic yeast Pichia pastoris. We constructed a plasmid containing cDNA encoding for human bone alkaline phosphatase, with the hydrophobic carboxyl terminal portion deleted. Alkaline phosphatase was secreted into the medium to a level of 32mg/L when cultured in shake flasks, and enzyme activity was 12U/mg, as measured by a spectrophotometric assay. By conversion to a fermentation system, a yield of 880mg/L has been achieved with an enzyme activity of 968U/mg. By gel electrophoresis analysis, it appears that greater than 50% of the total protein in the fermentation media is alkaline phosphatase. Although purification procedures are not yet completely optimized, they are expected to include filtration, ion exchange and affinity chromatography. Our presentation will focus on the purification and crystallization results up to the time of the conference. Structural data should provide additional information on the role of alkaline phosphatase in normal bone mineralization and in certain bone mineralization anomalies.

[Serum calcium and phosphorus concentration and alkaline phosphatase activity in healthy children during growth and development].

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Savić, Ljiljana; Savić, Dejan

2008-01-01

Many changes happen during growth and development in an organism as a result of important hormon changes, especially biohumoral ones. These changes make a problem when interpreting biochemical results in pediatric population. The most important changes are intensive calcium and phosphorus metabolic turnover in bone tissue with changes in alkaline phosphatase activity as a result of osteoblast activity. The aim of this study was to follow the serum calcium and phosphorus concentration and alkaline phosphatase activity in children 1-15 years old in different growth and development period and of different sexes and to fortify the influence of growth and development dynamics on biohumoral status in healthy male and female children. We evaluated 117 healthy children of both sexes from 1-15 years of age and divided them into three age groups: 1-5, 6-10 and 11-15 years. We followed the serum calcium and phosphorus concentration and alkaline phosphatase activity in different groups and in different sexes. Our investigation found significantly higher values of serum calcium in boys than in girls with no important changes between the age groups and significantly higher values of serum phosphorus in the youngest age group in all children and in different sexes with no important sex differences. Alkaline phosphatase activity followed the growth spurt and was the biggest in 6-10 years group in girls and in 11-15 years group in boys.

Glucose 6P binds and activates HlyIIR to repress Bacillus cereus haemolysin hlyII gene expression.

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Elisabeth Guillemet

Full Text Available Bacillus cereus is a Gram-positive spore-forming bacterium causing food poisoning and serious opportunistic infections. These infections are characterized by bacterial accumulation despite the recruitment of phagocytic cells. We have previously shown that B. cereus Haemolysin II (HlyII induces macrophage cell death by apoptosis. In this work, we investigated the regulation of the hlyII gene. We show that HlyIIR, the negative regulator of hlyII expression in B. cereus, is especially active during the early bacterial growth phase. We demonstrate that glucose 6P directly binds to HlyIIR and enhances its activity at a post-transcriptional level. Glucose 6P activates HlyIIR, increasing its capacity to bind to its DNA-box located upstream of the hlyII gene, inhibiting its expression. Thus, hlyII expression is modulated by the availability of glucose. As HlyII induces haemocyte and macrophage death, two cell types that play a role in the sequestration of nutrients upon infection, HlyII may induce host cell death to allow the bacteria to gain access to carbon sources that are essential components for bacterial growth.

Glucose consumption by various tissues in pregnant rats : effects of a 6-day euglycaemic hyperinsulinaemic clamp

NARCIS (Netherlands)

Nieuwenhuizen, AG; Schuiling, GA; Bonen, A; Paans, AMJ; Vaalburg, W; Koiter, TR

In the course of pregnancy maternal tissues become increasingly more insensitive to insulin. As 6 days of euglycaemic hyperinsulinaemic clamping, from day 8 until 14 of gestation, ameliorates total glucose consumption, we analysed the contribution of individual tissues in this phenomenon. We

Metabolic impact of an NADH-producing glucose-6-phosphate dehydrogenase in Escherichia coli

DEFF Research Database (Denmark)

Olavarria, K.; De Ingeniis, J.; Zielinski, D. C.

2014-01-01

In Escherichia coli, the oxidative branch of the pentose phosphate pathway (oxPPP) is one of the major sources of NADPH when glucose is the sole carbon nutrient. However, unbalanced NADPH production causes growth impairment as observed in a strain lacking phosphoglucoisomerase (Δpgi). In this work......PDH(R46E,Q47E). Through homologous recombination, the zwf loci (encoding G6PDH) in the chromosomes of WT and Δpgi E. coli strains were replaced by DNA encoding LmG6PDH(R46E,Q47E). Contrary to some predictions performed with flux balance analysis, the replacements caused a substantial effect...

Indomethacin treatment prevents high fat diet-induced obesity and insulin resistance but not glucose intolerance in C57BL/6J Mice

DEFF Research Database (Denmark)

Fjære, Even; Aune, Ulrike Liisberg; Røen, Kristin

2014-01-01

Chronic low grade inflammation is closely linked to obesity-associated insulin resistance. To examine how administration of the anti-inflammatory compound indomethacin, a general cyclooxygenase inhibitor, affected obesity development and insulin sensitivity, we fed obesity-prone male C57BL/6J mice...... a high fat/high sucrose (HF/HS) diet or a regular diet supplemented or not with indomethacin (±INDO) for 7 weeks. Development of obesity, insulin resistance, and glucose intolerance was monitored, and the effect of indomethacin on glucose-stimulated insulin secretion (GSIS) was measured in vivo...... and in vitro using MIN6 β-cells. We found that supplementation with indomethacin prevented HF/HS-induced obesity and diet-induced changes in systemic insulin sensitivity. Thus, HF/HS+INDO-fed mice remained insulin-sensitive. However, mice fed HF/HS+INDO exhibited pronounced glucose intolerance. Hepatic glucose...

Osteocalcin and bone-specific alkaline phosphatase in Sickle cell ...

African Journals Online (AJOL)

specific alkaline phosphatase (b-AP) total protein levels were evaluated as indicators of bone turnover in twenty patients with sickle cell haemoglobinopathies and in twenty normal healthy individuals. The serum bonespecific alkaline phosphatase ...

Enhanced glucose cycling and suppressed de novo synthesis of glucose-6-phosphate result in a net unchanged hepatic glucose output in ob/ob mice

NARCIS (Netherlands)

Bandsma, RHJ; Grefhorst, A; van Dijk, TH; van der Sluijs, FH; Hammer, A; Reijngoud, DJ; Kuipers, F

2004-01-01

Aims/hypothesis. Leptin-deficient ob/ob mice are hyperinsulinaemic and hyperglycaemic; however, the cause of hyperglycaemia remains largely unknown. Methods. Glucose metabolism in vivo in 9-h fasted ob/ob mice and lean littermates was studied by infusing [U-C-13]-glucose, [2-C-13]-glycerol,

The interaction between AMPKβ2 and the PP1-targeting subunit R6 is dynamically regulated by intracellular glycogen content.

Science.gov (United States)

Oligschlaeger, Yvonne; Miglianico, Marie; Dahlmans, Vivian; Rubio-Villena, Carla; Chanda, Dipanjan; Garcia-Gimeno, Maria Adelaida; Coumans, Will A; Liu, Yilin; Voncken, J Willem; Luiken, Joost J F P; Glatz, Jan F C; Sanz, Pascual; Neumann, Dietbert

2016-04-01

AMP-activated protein kinase (AMPK) is a metabolic stress-sensing kinase. We previously showed that glucose deprivation induces autophosphorylation of AMPKβ at Thr-148, which prevents the binding of AMPK to glycogen. Furthermore, in MIN6 cells, AMPKβ1 binds to R6 (PPP1R3D), a glycogen-targeting subunit of protein phosphatase type 1 (PP1), thereby regulating the glucose-induced inactivation of AMPK. In the present study, we further investigated the interaction of R6 with AMPKβ and the possible dependency on Thr-148 phosphorylation status. Yeast two-hybrid (Y2H) analyses and co-immunoprecipitation (IP) of the overexpressed proteins in human embryonic kidney (HEK) 293T) cells revealed that both AMPKβ1 and AMPK-β2 wild-type (WT) isoforms bind to R6. The AMPKβ-R6 interaction was stronger with the muscle-specific AMPKβ2-WT and required association with the substrate-binding motif of R6. When HEK293T cells or C2C12 myotubes were cultured in high-glucose medium, AMPKβ2-WT and R6 weakly interacted. In contrast, glycogen depletion significantly enhanced this protein interaction. Mutation of AMPKβ2 Thr-148 prevented the interaction with R6 irrespective of the intracellular glycogen content. Treatment with the AMPK activator oligomycin enhanced the AMPKβ2-R6 interaction in conjunction with increased Thr-148 phosphorylation in cells grown in low-glucose medium. These data are in accordance with R6 binding directly to AMPKβ2 when both proteins detach from the diminishing glycogen particle, which is simultaneous with increased AMPKβ2 Thr-148 autophosphorylation. Such a model points to a possible control of AMPK by PP1-R6 upon glycogen depletion in muscle. © 2016 Authors; published by Portland Press Limited.

Purification and characterization of a phosphotyrosyl-protein phosphatase from wheat seedlings.

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Cheng, H F; Tao, M

1989-10-19

A neutral phosphatase which catalyzes the hydrolysis of p-nitrophenylphosphate has been purified to homogeneity from wheat seedlings. The enzyme is a monomeric glycoprotein exhibiting a molecular weight of 35,000, frictional ratio of 1.22, Stokes' radius of 260 nm, and sedimentation coefficient of 3.2 S. That the enzyme is a glycoprotein is surmised from its chromatographic property on Concanavalin A-Sepharose column. An examination of the substrate specificity indicates that the enzyme exhibits a preference for phosphotyrosine over a number of phosphocompounds, including p-nitrophenylphosphate and several glycolytic intermediates. Both phosphoserine and phosphothreonine are not hydrolyzed by the enzyme. The phosphatase activity is not affected by high concentrations of chelating agents and does not require metal ions. Molybdate, orthovanadate, Zn2+, and Hg2+ are all potent inhibitors of the phosphatase activity. The ability of the phosphatase to dephosphorylate protein phosphotyrosine has been investigated. [32P-Tyr]poly(Glu,Tyr)n, [32P-Tyr]alkylated bovine serum albumin, [32P-Tyr]angiotensin-I, and [32P-Tyr]band 3 (from human erythrocyte) are all substrates of the phosphatase. On the other hand, the enzyme has no activity toward protein phosphoserine and phosphothreonine. Our result further indicates that the neutral phosphatase is distinct from the wheat germ acid phosphatase. The latter enzyme is found to dephosphorylate phosphotyrosyl as well as phosphoseryl and phosphothreonyl groups in proteins. In light of the many similarities in properties to phosphotyrosyl protein phosphatases isolated from several sources, it is suggested that the wheat seedling phosphatase may participate in cellular regulation involving protein tyrosine phosphorylation.

Research on Phosphatases of Belladona Leaves and Their Purification

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M. Khorsand

1957-01-01

Full Text Available Through experimentation with several leaves it has been possible for us to point out the existance of two different acid phosphatases. We have studied in more detail the phosphatases of belldon a leaves (Atropa Belladona L. Solanacees. The great part of the phosphatase activity is water extractable. We have compared the activity of the soluble fraction with that not directly extractable by means of water. The insoluble fraction could not be solubilized in a satisfaetC'fY m.anner.The digestion by papaine produced a slight solubilizing effect; on the other hand salt solutions, neutral or alkaline, or water glycerol mixtures had no solubilizing effect on the enzyme, It has been possible to demonstrate the existence of two different phosphatases in the insoluble fraction: the first of the type II,

Defining Starch Binding by Glucan Phosphatases

DEFF Research Database (Denmark)

Auger, Kyle; Raththagala, Madushi; Wilkens, Casper

2015-01-01

Starch is a vital energy molecule in plants that has a wide variety of uses in industry, such as feedstock for biomaterial processing and biofuel production. Plants employ a three enzyme cyclic process utilizing kinases, amylases, and phosphatases to degrade starch in a diurnal manner. Starch...... is comprised of the branched glucan amylopectin and the more linear glucan amylose. Our lab has determined the first structures of these glucan phosphatases and we have defined their enzymatic action. Despite this progress, we lacked a means to quickly and efficiently quantify starch binding to glucan...

Glucose 6-phosphate dehydrogenase: isoenzymatic pattern in Oesophagostomum venulosum, Trichuris ovis and T. suis.

Science.gov (United States)

Rodriguez, B; Cutillas, C; German, P; Guevara, D

1991-12-01

In the present communication we have studied the isoenzymatic pattern activity of the glucose 6-phosphate dehydrogenase (G6PD) in Oesophagostomum venulosum, Trichuris ovis and T. suis, parasites of Capra hircus (goat), Ovis aries (sheep) and Sus scrofa domestica (pig) respectively, by polyacrylamide gel electrophoresis. Different phenotypes have been observed in the G6PD isoenzymatic pattern activity in males and females of Oesophagostomum venulosum. Furthermore, G6PD activity has been assayed in Trichuris ovis collected from Ovis aries and Capra hircus. No differences have been observed in the isoenzymatic patterns attending to the different hosts. All the individuals exhibited one single band or two bands; this suggests a monomeric condition for G6PD in T. ovis. In T. suis the enzyme G6PD appeared as a single electrophoretic band in about 85.7% of the individuals.

Gestational Protein Restriction Impairs Glucose Disposal in the Gastrocnemius Muscles of Female Rats

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Blesson, Chellakkan S.; Chinnathambi, Vijayakumar; Kumar, Sathish

2017-01-01

Gestational low-protein (LP) diet causes hyperglycemia and insulin resistance in adult offspring, but the mechanism is not clearly understood. In this study, we explored the role of insulin signaling in gastrocnemius muscles of gestational LP-exposed female offspring. Pregnant rats were fed a control (20% protein) or an isocaloric LP (6%) diet from gestational day 4 until delivery. Normal diet was given to mothers after delivery and to pups after weaning until necropsy. Offspring were euthanized at 4 months, and gastrocnemius muscles were treated with insulin ex vivo for 30 minutes. Messenger RNA and protein levels of molecules involved in insulin signaling were assessed at 4 months. LP females were smaller at birth but showed rapid catchup growth by 4 weeks. Glucose tolerance test in LP offspring at 3 months showed elevated serum glucose levels (P insulin levels. In gastrocnemius muscles, LP rats showed reduced tyrosine phosphorylation of insulin receptor substrate 1 upon insulin stimulation due to the overexpression of tyrosine phosphatase SHP-2, but serine phosphorylation was unaffected. Furthermore, insulin-induced phosphorylation of Akt, glycogen synthase kinase (GSK)–3α, and GSK-3β was diminished in LP rats, and they displayed an increased basal phosphorylation (inactive form) of glycogen synthase. Our study shows that gestational protein restriction causes peripheral insulin resistance by a series of phosphorylation defects in skeletal muscle in a mechanism involving insulin receptor substrate 1, SHP-2, Akt, GSK-3, and glycogen synthase causing dysfunctional GSK-3 signaling and increased stored glycogen, leading to distorted glucose homeostasis. PMID:28324067

Serum alkaline phosphatase screening for vitamin D deficiency states

International Nuclear Information System (INIS)

Shaheen, S.; Barrakzai, Q.

2012-01-01

Objective: To determine whether serum vitamin D levels are correlated with serum levels of alkaline phosphatase or not. Study Design: Cross-sectional, observational study. Place and Duration of Study: Multi-centre study, conducted at Liaquat National Hospital and Medical College, National Medical Centre and Medicare Hospital, Karachi, from January to October 2009. Methodology: Patients attending the Orthopaedic OPDs with complaints of pain in different body regions and serum vitamin D/sub 3/ levels of greater or equal to 30 ng/ml were included in the study. Patients with vitamin D deficiency were further categorized into mild deficiency or insufficiency (vit. D/sub 3/ = 20-29 ng/ml), moderate deficiency (vit. D/sub 3/ = 5 - 19 ng/ml) and severe deficiency forms (vit. D/sub 3/ < 5 ng/ml). Pearson correlation was applied to test the correlation of serum alkaline phosphatase levels with serum vitamin D/sub 3/ levels. P-value < 0.05 was considered to be significant. Results: Out of 110 samples, 26 had mild (23%), 61 had moderate (55%) and 21 had severe (19.1%) vitamin D deficiencies. All of the patients in the three groups had alkaline phosphatase with in normal limits and the total mean value of the enzyme was 135.97 +- 68.14I U/L. The inter group comparison showed highest values of alkaline phosphatase in the moderate vitamin D deficiency group. The correlation coefficient of alkaline phosphatase and serum vitamin D/sub 3/ levels was r =0.05 (p =0.593). Conclusion: Serum vitamin D/sub 3/ levels may not be correlated with increased serum alkaline phosphatase levels. Therefore, alkaline phosphatase may not be used as a screening test to rule out vitamin D deficiency. (author)

Glucose turnover, gluconeogenesis from glycerol, and estimation of net glucose cycling in cancer patients

International Nuclear Information System (INIS)

Lundholm, K.; Edstroem, S.; Karlberg, I.; Ekman, L.; Schersten, T.

1982-01-01

A double isotope method was used in patients with progressive malignancy and in control patients to measure: glucose turnover, conversion rate of carbon skeleton of glycerol into glucose, and the interorgan cycling of glucose carbons (Cori-cycle plus alanine-glucose cycle). [U- 14 C]glycerol and [6- 3 H]glucose were given intravenously as a single dose injection. The time course of the specific radioactivities of [6- 3 H] and [U- 14 C]glucose was followed in blood. The pool size and the turnover rate of glucose were increased in the cancer group as compared with the control patients. The net recycling of glucose carbons was not increased in the cancer group, despite the increased turnover of glucose. The alterations in the metabolism of glucose did not correlate with the plasma levels of insulin or thyroid hormones (T4, T3, rT3) neither in the entire cancer group nor in those cancer patients who were repeatedly investigated at different intervals of time. The turnover rate of glucose in the cancer patients correlated inversely to their body weight index. The gluconeogenesis rate, given as the fractional conversion rate of the injected radioactive dose of [ 14 C]glycerol, or as mol glucose . kg body weight-1 . day-1, was increased in the cancer group, but still contributed only 3% of the glucose turnover rate in both cancer and control patients. We conclude that an increased gluconeogenesis from glycerol is not significant in terms of energy expenditure in patients with progressive malignancy, as has previously been concluded for the gluconeogenesis from alanine. It seems that increased turnover of glucose may contribute to inappropriately high energy expenditure in cancer patients

PTP1B antisense oligonucleotide lowers PTP1B protein, normalizes blood glucose, and improves insulin sensitivity in diabetic mice

Science.gov (United States)

Zinker, Bradley A.; Rondinone, Cristina M.; Trevillyan, James M.; Gum, Rebecca J.; Clampit, Jill E.; Waring, Jeffrey F.; Xie, Nancy; Wilcox, Denise; Jacobson, Peer; Frost, Leigh; Kroeger, Paul E.; Reilly, Regina M.; Koterski, Sandra; Opgenorth, Terry J.; Ulrich, Roger G.; Crosby, Seth; Butler, Madeline; Murray, Susan F.; McKay, Robert A.; Bhanot, Sanjay; Monia, Brett P.; Jirousek, Michael R.

2002-01-01

The role of protein-tyrosine phosphatase 1B (PTP1B) in diabetes was investigated using an antisense oligonucleotide in ob/ob and db/db mice. PTP1B antisense oligonucleotide treatment normalized plasma glucose levels, postprandial glucose excursion, and HbA1C. Hyperinsulinemia was also reduced with improved insulin sensitivity. PTP1B protein and mRNA were reduced in liver and fat with no effect in skeletal muscle. Insulin signaling proteins, insulin receptor substrate 2 and phosphatidylinositol 3 (PI3)-kinase regulatory subunit p50α, were increased and PI3-kinase p85α expression was decreased in liver and fat. These changes in protein expression correlated with increased insulin-stimulated protein kinase B phosphorylation. The expression of liver gluconeogenic enzymes, phosphoenolpyruvate carboxykinase, and fructose-1,6-bisphosphatase was also down-regulated. These findings suggest that PTP1B modulates insulin signaling in liver and fat, and that therapeutic modalities targeting PTP1B inhibition may have clinical benefit in type 2 diabetes. PMID:12169659

Antihyperglycemic activity of Piper betle leaf on streptozotocin-induced diabetic rats.

Science.gov (United States)

Santhakumari, P; Prakasam, A; Pugalendi, K V

2006-01-01

Piper betle, an indigenous medicinal plant, has a folk (Siddha and Ayurvedha) reputation in the rural southern India. The present study was carried out to evaluate the effect of P. betle on glucose metabolism since it is consumed as betel-quid after meals. Plasma levels of glucose and glycosylated hemoglobin and activities of liver hexokinase and gluconeogenic enzymes such as glucose-6-phosphatase and fructose-1,6-bisphosphatase in control and streptozotocin (STZ) diabetic rats were assayed. Oral administration of leaf suspension of P. betle (75 and 150 mg/kg of body weight) for 30 days resulted in significant reduction in blood glucose (from 205.00 +/- 10.80 mg/dL to 151.30 +/- 6.53 mg/dL) and glycosylated hemoglobin and decreased activities of liver glucose-6-phosphatase and fructose-1,6-bisphosphatase, while liver hexokinase increased (P betle at a dose of 75 mg/kg of body weight exhibited better sugar reduction than 150 mg/kg of body weight. In addition, protection against body weight loss of diabetic animals was also observed. The effects produced by P. betle were compared with the standard drug glibenclamide. Thus, the present study clearly shows that P. betle intake influences glucose metabolism beneficially.

Coupling between the voltage-sensing and phosphatase domains of Ci-VSP.

Science.gov (United States)

Villalba-Galea, Carlos A; Miceli, Francesco; Taglialatela, Maurizio; Bezanilla, Francisco

2009-07-01

The Ciona intestinalis voltage sensor-containing phosphatase (Ci-VSP) shares high homology with the phosphatidylinositol phosphatase enzyme known as PTEN (phosphatase and tensin homologue deleted on chromosome 10). We have taken advantage of the similarity between these proteins to inquire about the coupling between the voltage sensing and the phosphatase domains in Ci-VSP. Recently, it was shown that four basic residues (R11, K13, R14, and R15) in PTEN are critical for its binding onto the membrane, required for its catalytic activity. Ci-VSP has three of the basic residues of PTEN. Here, we show that when R253 and R254 (which are the homologues of R14 and R15 in PTEN) are mutated to alanines in Ci-VSP, phosphatase activity is disrupted, as revealed by a lack of effect on the ionic currents of KCNQ2/3, where current decrease is a measure of phosphatase activity. The enzymatic activity was not rescued by the introduction of lysines, indicating that the binding is an arginine-specific interaction between the phosphatase binding domain and the membrane, presumably through the phosphate groups of the phospholipids. We also found that the kinetics and steady-state voltage dependence of the S4 segment movement are affected when the arginines are not present, indicating that the interaction of R253 and R254 with the membrane, required for the catalytic action of the phosphatase, restricts the movement of the voltage sensor.

Exogenous glucagon-like peptide-1 attenuates glucose absorption and reduces blood glucose concentration after small intestinal glucose delivery in critical illness.

Science.gov (United States)

Miller, Asaf; Deane, Adam M; Plummer, Mark P; Cousins, Caroline E; Chapple, Lee-Anne S; Horowitz, Michael; Chapman, Marianne J

2017-03-01

To evaluate the effect of exogenous glucagonlike peptide-1 (GLP-1) on small intestinal glucose absorption and blood glucose concentrations during critical illness. A prospective, blinded, placebo-controlled, cross-over, randomised trial in a mixed medical-surgical adult intensive care unit, with 12 mechanically ventilated critically ill patients, who were suitable for receiving small intestinal nutrient. On consecutive days, in a randomised order, participants received intravenous GLP-1 (1.2 pmol/ kg/min) or placebo (0.9% saline) as a continuous infusion over 270 minutes. After 6 hours of fasting, intravenous infusions of GLP-1 or placebo began at T = -30 min (in which T = time), with the infusion maintained at a constant rate until study completion at T = 240 min. At T = 0 min, a 100 mL bolus of mixed liquid nutrient meal (1 kcal/mL) containing 3 g of 3-O-methyl-D-gluco-pyranose (3-OMG), a marker of glucose absorption, was administered directly into the small intestine, via a post-pyloric catheter, over 6 minutes. Blood samples were taken at regular intervals for the measurement of plasma glucose and 3-OMG concentrations. Intravenous GLP-1 attenuated initial small intestinal glucose absorption (mean area under the curve [AUC] 0-30 for 3-OMG: GLP-1 group, 4.4 mmol/L/min [SEM, 0.9 mmol/L/min] v placebo group, 6.5 mmol/L/min [SEM, 1.0 mmol/L/min]; P = 0.01), overall small intestinal glucose absorption (mean AUC 0-240 for 3-OMG: GLP-1, 68.2 mmol/L/ min [SEM, 4.7 mmol/L/min] v placebo, 77.7 mmol/L/min [SEM, 4.4 mmol/lLmin]; P = 0.02), small intestinal glucose absorption and overall blood glucose concentration (mean AUC 0-240 for blood glucose: GLP-1, 2062 mmol/L/min [SEM, 111 mmol/L/min] v placebo 2328 mmol/L/min [SEM, 145 mmol/L/min]; P = 0.005). Short-term administration of exogenous GLP-1 reduces small intestinal glucose absorption for up to 4 hours during critical illness. This is likely to be an additional mechanism for the glucose-lowering effect of this agent.

Human prostatic acid phosphatase: purification, characterization, and optimization of conditions for radioimmunoassay

International Nuclear Information System (INIS)

McCarthy, R.C.; Jakubowski, H.V.; Markowitz, H.

1983-01-01

Prostatic acid phosphatase was isolated from benign hypertrophic prostate tissue by ammonium sulfate precipitation and affinity chromatography procedures. The purified enzyme was characterized by two-dimensional gel electrophoresis and shown to have a cluster of protein spots with an apparent molecular weight of 48000 at pI 5.9 to 6.3 in 9 mol/l urea. The specific activity of the purified enzyme was 723 and 659 U/mg protein with α-naphthyl phosphate at 30 0 C and para-nitrophenyl phosphate at 37 0 C respectively. An antibody to the purified enzyme was raised in rabbits and used in a radioimmunoassay (RIA). The use of a phosphate buffer, pH 6.6, and iodination of prostatic acid phosphatase (PAP) by the Bolton-Hunter procedure improved the precision of the assay when compared to RIA's using a phosphate buffer, pH 7.0 or 7.3, or PAP iodinated by a chloramine-T procedure. The former RIA displaced 50% of the tracer at 2 μg of enzyme per liter of serum. The between-run coefficient of variation for 11 assays ranged from 3.9-7.7% with serum at 1.3 to 5.6 μg PAP/l. (Auth.)

A generally applicable sequential alkaline phosphatase immunohistochemical double staining

NARCIS (Netherlands)

van der Loos, Chris M.; Teeling, Peter

2008-01-01

A universal type of sequential double alkaline phosphatase immunohistochemical staining is described that can be used for formalin-fixed, paraffin-embedded and cryostat tissue sections from human and mouse origin. It consists of two alkaline phosphatase detection systems including enzymatic

Pterocarpans with inhibitory effects on protein tyrosine phosphatase 1B from Erythrina lysistemon Hutch

DEFF Research Database (Denmark)

Dao, Trong Tuan; Nguyen, Phi Hung; Thuong, Phuong Thien

2009-01-01

',5':3,4]-2'',2''-dimethyldihydropyrano[6'',5'':9,10]pterocarpan (1), furano[5',4':3,4]-9-hydroxy-10-prenylpterocarpan (2), and 8-formyl-3,9-dihydroxy-4,10-diprenylpterocarpan (3), based on spectroscopic analyses. All the isolates, with the exception of 3, 6, and 11, strongly inhibited protein tyrosine phosphatase 1B (PTP1B) activity...

COMPARISON OF METHODS FOR ALKALINE PHOSPHATASE AND PEROXIDASE DETECTION IN MILK

Directory of Open Access Journals (Sweden)

felipe Nael Seixas

2014-02-01

Full Text Available This study evaluated the performance of strips for colorimetric detection of alkaline phosphatase and peroxidase in milk, comparing them with a kit of reagents for alkaline phosphatase and the official methodology for peroxidase. The samples were analyzed at the Laboratory Inspection of Products of Animal Origin, State University of Londrina. For the comparison tests for the detection of alkaline phosphatase four treatments were made by adding different percentages of raw milk (1%, 2%, 5% and 10% in the pasteurized milk, plus two control treatments. Thirty-eight samples triplicate for each treatment were analyzed. To compare the performance of tests for peroxidase 80 pasteurized milk samples were evaluated simultaneously by official methodology and by colorimetric strips. The performance of the alkaline phosphatase were different for the treatments with 1% and 2% of raw milk which had all the strips change color as the reagent kit showed the presence of phosphatase in just 2.63% and 5.26% the cases, respectively for each treatment. The colorimetric strips for alkaline phosphatase are more sensitive for the identification of small quantities compared to the reagent kit. The performance of tests for peroxidase showed no difference. The strips for the detection of peroxidase or alkaline phosphatase were effective and can replace traditional methods.

Two apparent glucose-6-phosphate dehydrogenase variants in normal XY males: G6PD Alabama.

Science.gov (United States)

Prchal, J T; Hall, K; Csepreghy, M; Lilly, M; Berkow, R; Scott, C W

1988-03-01

A six-year-old black boy who had transient hemolysis after a viral infection was found to have mildly decreased red cell glucose-6-phosphate dehydrogenase (G6PD) activity (1.25 IU/g hemoglobin). Two G6PD bands, both slightly faster than normal G6PD B, were seen on electrophoresis in both the propositus as well as in his maternal grandfather. This is an unexpected finding, since the G6PD gene is located on the long arm of the X chromosome that is subject to X-chromosome inactivation, and available evidence indicates that it is present as a single functional copy in the human genome. The obvious possibility of duplication of the X chromosome was eliminated by cytogenetic analysis with G-banding. G6PD duplication is unlikely, since peripheral blood granulocytes, platelets, and lymphocytes; cultured skin and bone marrow fibroblasts; and Epstein-Barr virus-stimulated lymphocytes yielded only a single electrophoretic band with mobility identical to the slower band seen in crude red blood cell hemolysate. Study of partially purified red blood cell hemolysate G6PD also yielded a single band with identical mobility. Kinetic studies of the enzyme in the propositus and in three generations of his family identified a unique, previously unpublished G6PD mutant that is herein designated G6PD Alabama. Red blood cells were separated by density gradient into a reticulocyte-enriched, an intermediate, and a dense, older portion. Two distinct enzyme bands were identified on electrophoresis of hemolysate from the reticulocyte-enriched portion, but not from the other two portions. It is postulated that two transcriptional products of the mutant G6PD gene exist; one with a short half-life and detectable only in young red blood cells, and another with a longer half-life present in all cells. The existence of two distinct mutant genes in the genome or a unique post-translational form of the mutant G6PD detected only in reticulocytes cannot be excluded.

Glucose-6-phosphate dehydrogenase and glutathione reductase activity in methemoglobin reduction by methylene blue and cyst amine: study on glucose-6-phosphate dehydrogenase-deficient individuals, on normal subjects and on riboflavin-treated subjects

Directory of Open Access Journals (Sweden)

Benedito Barraviera

1988-10-01

Full Text Available The authors have standardized methods for evaluation of the activity of the glucose-6-phosphate dehydrogenase and of glutathione reductase. The general principle of the first method was based on methemoglobin formation by sodium nitrite followed by stimulation of the glucose-6-phosphate dehydrogenase with methylene blue. Forty six adults (23 males and 23 females were studied. Subjects were not G6PD deficient and were aged 20 to 30 years. The results showed that methemoglobin reduction by methylene blue was 154.40 and 139.90 mg/min (p<0.05 for males and females, respectively, in whole blood, and 221.10 and 207.85 mg/min (n.s., respectively, in washed red cells. These data showed that using washed red cells and 0.7g% sodium nitrite concentration produced no differences between sexes and also shortened reading time for the residual amount of methemoglobin to 90 minutes. Glutathione reductase activity was evaluated on the basis of the fact that cystamine (a thiol agent binds to the SH groups of hemoglobin, forming complexes. These complexes are reversed by the action of glutathione reductase, with methemoglobin reduction occurring simultaneously with this reaction. Thirty two adults (16 males and 16 females were studied. Subjects were not G6PD deficient and were aged 20 to 30 years. Methemoglobin reduction by cystamine was 81.27 and 91.13 mg/min (p<0.01 for males and females, respectively. These data showed that using washed red cells and 0.1 M cystamine concentration permits a reading of the residual amount of methemoglobin at 180 minutes of incubation. Glutathione reductase activity was evaluated by methemoglobin reduction by cystamine in 14 females before and after treatment with 10 mg riboflavin per day for 8 days. The results were 73.69 and 94.26 jug/min (p<0.01 before and after treatment, showing that riboflavin treatment increase glutathione reductase activity even in normal individuals. Three Black G6PD-deficient individuals (2 males and 1

Dietary fructose and glucose differentially affect lipid and glucose homeostasis.

Science.gov (United States)

Schaefer, Ernst J; Gleason, Joi A; Dansinger, Michael L

2009-06-01

Absorbed glucose and fructose differ in that glucose largely escapes first-pass removal by the liver, whereas fructose does not, resulting in different metabolic effects of these 2 monosaccharides. In short-term controlled feeding studies, dietary fructose significantly increases postprandial triglyceride (TG) levels and has little effect on serum glucose concentrations, whereas dietary glucose has the opposite effects. When dietary glucose and fructose have been directly compared at approximately 20-25% of energy over a 4- to 6-wk period, dietary fructose caused significant increases in fasting TG and LDL cholesterol concentrations, whereas dietary glucose did not, but dietary glucose did increase serum glucose and insulin concentrations in the postprandial state whereas dietary fructose did not. When fructose at 30-60 g ( approximately 4-12% of energy) was added to the diet in the free-living state, there were no significant effects on lipid or glucose biomarkers. Sucrose and high-fructose corn syrup (HFCS) contain approximately equal amounts of fructose and glucose and no metabolic differences between them have been noted. Controlled feeding studies at more physiologic dietary intakes of fructose and glucose need to be conducted. In our view, to decrease the current high prevalence of obesity, dyslipidemia, insulin resistance, and diabetes, the focus should be on restricting the intake of excess energy, sucrose, HFCS, and animal and trans fats and increasing exercise and the intake of vegetables, vegetable oils, fish, fruit, whole grains, and fiber.

Vanadate monomers and dimers both inhibit the human prostatic acid phosphatase.

Science.gov (United States)

Crans, D C; Simone, C M; Saha, A K; Glew, R H

1989-11-30

A combination of enzyme kinetics and 51V NMR spectroscopy was used to identify the species of vanadate that inhibits acid phosphatases. Monomeric vanadate was shown to inhibit wheat germ and potato acid phosphatases. At pH 5.5, the vanadate dimer inhibits the human prostatic acid phosphatase whereas at pH 7.0 it is the vanadate monomer that inhibits this enzyme. The pH-dependent shift in the affinity of the prostatic phosphatase for vanadate is presumably due to deprotonation of an amino acid side chain in or near the binding site resulting in a conformational change in the protein. pH may be a subtle effector of the insulin-like vanadate activity in biological systems and may explain some of the differences in selectivity observed with the protein phosphatases.

Hepatic glucose output in humans measured with labeled glucose to reduce negative errors

International Nuclear Information System (INIS)

Levy, J.C.; Brown, G.; Matthews, D.R.; Turner, R.C.

1989-01-01

Steele and others have suggested that minimizing changes in glucose specific activity when estimating hepatic glucose output (HGO) during glucose infusions could reduce non-steady-state errors. This approach was assessed in nondiabetic and type II diabetic subjects during constant low dose [27 mumol.kg ideal body wt (IBW)-1.min-1] glucose infusion followed by a 12 mmol/l hyperglycemic clamp. Eight subjects had paired tests with and without labeled infusions. Labeled infusion was used to compare HGO in 11 nondiabetic and 15 diabetic subjects. Whereas unlabeled infusions produced negative values for endogenous glucose output, labeled infusions largely eliminated this error and reduced the dependence of the Steele model on the pool fraction in the paired tests. By use of labeled infusions, 11 nondiabetic subjects suppressed HGO from 10.2 +/- 0.6 (SE) fasting to 0.8 +/- 0.9 mumol.kg IBW-1.min-1 after 90 min of glucose infusion and to -1.9 +/- 0.5 mumol.kg IBW-1.min-1 after 90 min of a 12 mmol/l glucose clamp, but 15 diabetic subjects suppressed only partially from 13.0 +/- 0.9 fasting to 5.7 +/- 1.2 at the end of the glucose infusion and 5.6 +/- 1.0 mumol.kg IBW-1.min-1 in the clamp (P = 0.02, 0.002, and less than 0.001, respectively)

Effect of High-Dose Vitamin C Infusion in a Glucose-6-Phosphate Dehydrogenase-Deficient Patient

Science.gov (United States)

Gerber, Bryan; Kenyon, Katharine; Muthukanagaraj, Purushothaman

2017-01-01

Vitamin C supplementation is generally regarded as benign. There has been a resurgence of interest in the general medical community regarding the use of vitamin C most notably in the care of sepsis. Nonetheless, caution must be taken if supraphysiologic vitamin C supplementation is being administered as it should be considered a medication just like any other. We present a case of hemolysis in a glucose-6-phosphate dehydrogenase- (G6PD-) deficient patient receiving high-dose vitamin C infusions for his rheumatoid arthritis. PMID:29317868

Low molecular weight protein tyrosine phosphatases control antibiotic production in Streptomyces coelicolor A3(2)

DEFF Research Database (Denmark)

Sohoni, Sujata Vijay; Lieder, Sarah; Bapat, Prashant Madhusudhan

2014-01-01

3700 was established usingpara-nitrophenyl phosphate and the tyrosine-phosphorylated protein PtkA from Bacillus subtilis as substrates. Theoptimum pH for the Sco3700 phosphatase activity was 6.8, and KM for pNPP was 14.3 mM compared to pH 6.0and KM0.75 mM for PtpA. The potential of Sco3700...... of ACT in the ptpA over expression strain. Furthermore, a significantly earlier onset of ACT productionwas observed when ptpA was over expressed. Sco3700 overexpression had a pleiotropic effect on the cell, and thestrain exhibited lower productivities and final concentrations of antibiotics. We conclude...... that Sco3700 is indeed atyrosine phosphatase, and it contributes to regulation of antibiotic production in S. coelicolor affecting the timing ofonset of the antibiotic production...

The impact of phosphatases on proliferative and survival signaling in cancer.

Science.gov (United States)

Narla, Goutham; Sangodkar, Jaya; Ryder, Christopher B

2018-05-03

The dynamic and stringent coordination of kinase and phosphatase activity controls a myriad of physiologic processes. Aberrations that disrupt the balance of this interplay represent the basis of numerous diseases. For a variety of reasons, early work in this area portrayed kinases as the dominant actors in these signaling events with phosphatases playing a secondary role. In oncology, these efforts led to breakthroughs that have dramatically altered the course of certain diseases and directed vast resources toward the development of additional kinase-targeted therapies. Yet, more recent scientific efforts have demonstrated a prominent and sometimes driving role for phosphatases across numerous malignancies. This maturation of the phosphatase field has brought with it the promise of further therapeutic advances in the field of oncology. In this review, we discuss the role of phosphatases in the regulation of cellular proliferation and survival signaling using the examples of the MAPK and PI3K/AKT pathways, c-Myc and the apoptosis machinery. Emphasis is placed on instances where these signaling networks are perturbed by dysregulation of specific phosphatases to favor growth and persistence of human cancer.

Incorporation of glucose carbons into rat lung lipids after exposure to 0.6 ppm ozone

International Nuclear Information System (INIS)

Bassett, D.J.; Rabinowitz, J.L.

1985-01-01

Continuous exposure to low concentrations of ozone has previously been associated with proliferation of lung alveolar type II epithelial cells. In this study, 14 C incorporation into tissue lipids was determined in isolated rat lungs by perfusion with [U- 14 C]glucose, at a time of maximal hyperplasia brought about by 3 days continuous exposure to 0.6 ppm ozone. Ozone exposed lungs exhibited increased rates of glycolytic energy production, indicated by an 89% increase in 3 H 2 O generation on perfusion with [5-3H]glucose. Ozone exposure resulted in enhanced 14 C incorporations into glyceride-glycerol and fatty acid moieties of lung lipids of 95 and 180%, respectively, with a greater proportion of label being recovered in shorter chain fatty acids. Although increased labeling was observed in both neutral and phospholipids, the pattern of 14 C recovery suggested a relative increased glucose carbon incorporation into lung free fatty acids, phosphatidic acid, and such membrane associated lipids as phosphatidylinositol and those containing sphingosine. These results are consistent with the needs of a dividing cell population for enhanced energy production and synthesis of new lipids

Pharmacokinetic and toxicological evaluation of multi-functional thiol-6-fluoro-6-deoxy-d-glucose gold nanoparticles in vivo

Science.gov (United States)

Roa, Wilson; Xiong, Yeping; Chen, Jie; Yang, Xiaoyan; Song, Kun; Yang, Xiaohong; Kong, Beihua; Wilson, John; Xing, James Z.

2012-09-01

We synthesized a novel, multi-functional, radiosensitizing agent by covalently linking 6-fluoro-6-deoxy-d-glucose (6-FDG) to gold nanoparticles (6-FDG-GNPs) via a thiol functional group. We then assessed the bio-distribution and pharmacokinetic properties of 6-FDG-GNPs in vivo using a murine model. At 2 h, following intravenous injection of 6-FDG-GNPs into the murine model, approximately 30% of the 6-FDG-GNPs were distributed to three major organs: the liver, the spleen and the kidney. PEGylation of the 6-FDG-GNPs was found to significantly improve the bio-distribution of 6-FDG-GNPs by avoiding unintentional uptake into these organs, while simultaneously doubling the cellular uptake of GNPs in implanted breast MCF-7 adenocarcinoma. When combined with radiation, PEG-6-FDG-GNPs were found to increase the apoptosis of the MCF-7 breast adenocarinoma cells by radiation both in vitro and in vivo. Pharmacokinetic data indicate that GNPs reach their maximal concentrations at a time window of two to four hours post-injection, during which optimal radiation efficiency can be achieved. PEG-6-FDG-GNPs are thus novel nanoparticles that preferentially accumulate in targeted cancer cells where they act as potent radiosensitizing agents. Future research will aim to substitute the 18F atom into the 6-FDG molecule so that the PEG-6-FDG-GNPs can also function as radiotracers for use in positron emission tomography scanning to aid cancer diagnosis and image guided radiation therapy planning.

Riluzole increases the rate of glucose transport in L6 myotubes and NSC-34 motor neuron-like cells via AMPK pathway activation.

Science.gov (United States)

Daniel, Bareket; Green, Omer; Viskind, Olga; Gruzman, Arie

2013-09-01

Riluzole is the only approved ALS drug. Riluzole influences several cellular pathways, but its exact mechanism of action remains unclear. Our goal was to study the drug's influence on the glucose transport rate in two ALS relevant cell types, neurons and myotubes. Stably transfected wild-type or mutant G93A human SOD1 NSC-34 motor neuron-like cells and rat L6 myotubes were exposed to riluzole. The rate of glucose uptake, translocation of glucose transporters to the cell's plasma membrane and the main glucose transport regulatory proteins' phosphorylation levels were measured. We found that riluzole increases the glucose transport rate and up-regulates the translocation of glucose transporters to plasma membrane in both types of cells. Riluzole leads to AMPK phosphorylation and to the phosphorylation of its downstream target, AS-160. In conclusion, increasing the glucose transport rate in ALS affected cells might be one of the mechanisms of riluzole's therapeutic effect. These findings can be used to rationally design and synthesize novel anti-ALS drugs that modulate glucose transport in neurons and skeletal muscles.

Modeling error and apparent isotope discrimination confound estimation of endogenous glucose production during euglycemic glucose clamps

International Nuclear Information System (INIS)

Finegood, D.T.; Bergman, R.N.; Vranic, M.

1988-01-01

We previously demonstrated that conventional tracer methods applied to euglycemic-hyperinsulinemic glucose clamps result in substantially negative estimates for the rate of endogenous glucose production, particularly during the first half of 180-min clamps. We also showed that addition of tracer to the exogenous glucose infusate resulted in nonnegative endogenous glucose production (Ra) estimates. In this study, we investigated the underlying cause of negative estimates of Ra from conventional clamp/tracer methods and the reason for the difference in estimates when tracer is added to the exogenous glucose infusate. We performed euglycemic-hyperinsulinemic (300-microU/ml) clamps in normal dogs without (cold GINF protocol, n = 6) or with (hot GINF protocol, n = 6) tracer (D-[3-3H]glucose) added to the exogenous glucose infusate. In the hot GINF protocol, sufficient tracer was added to the exogenous glucose infusate such that arterial plasma specific activity (SAa) did not change from basal through the clamp period (P greater than .05). In the cold GINF studies, plasma SAa fell 81 +/- 2% from the basal level by the 3rd h of clamping. We observed a significant, transient, positive venous-arterial difference in specific activity (SAv-SAa difference) during the cold GINF studies. The SAv-SAa difference reached a peak of 27 +/- 6% at 30 min and diminished to a plateau of 7 +/- 1% between 70 and 180 min. We also observed a positive but constant SAv-SAa difference (4.6 +/- 0.2% between 10 and 180 min) during the hot GINF studies

Glucose-6-phosphate dehydrogenase: the key to sex-related xenobiotic toxicity in hepatocytes of European flounder (Platichthys flesus L.)?

NARCIS (Netherlands)

Winzer, Katja; van Noorden, Cornelis J. F.; Köhler, Angela

2002-01-01

The role of glucose-6-phosphate dehydrogenase (G6PDH) in oxidative stress responses was investigated in isolated intact living hepatocytes of immature female and male European flounder (Platichthys flesus L.) because it is the major provider of NADPH needed as reducing power for various

Glycogen metabolism in the liver of Indian desert gerbils (Meriones hurrianae, Jerdon) exposed to internal beta irradiation

International Nuclear Information System (INIS)

Gupta, N.K.

1996-01-01

Glycogen content and the activities of phosphorylase, glycogen synthetase, phosphohexose isomerase, glucose-6-phosphatase, succinate dehydrogenase, alanine and aspartate aminotransferases have been biochemically determined in the liver of Indian desert gerbils following radiocalcium internal irradiation. Decline in glycogen, phosphohexose isomerase, with a concomitant increase in phosphorylase, succinate dehydrogenase reveals a switch over from glycolytic to oxidative metabolism in liver. Activities of aminotransferases indicate the utilization of transamination products of alanine and aspartate in oxidative pathway during early periods. Transiently increased glucose-6-phosphatase seems to restrict glycogenolytic and glycolytic metabolism and thereby pave way for the acceleration of oxidative metabolism. (author). 52 refs., 2 tabs

The immediate effects of a single bout of aerobic exercise on oral glucose tolerance across the glucose tolerance continuum

DEFF Research Database (Denmark)

Knudsen, Sine H; Karstoft, Kristian; Pedersen, Bente K

2014-01-01

We investigated glucose tolerance and postprandial glucose fluxes immediately after a single bout of aerobic exercise in subjects representing the entire glucose tolerance continuum. Twenty-four men with normal glucose tolerance (NGT), impaired glucose tolerance (IGT), or type 2 diabetes (T2D; age......: 56 ± 1 years; body mass index: 27.8 ± 0.7 kg/m(2), P > 0.05) underwent a 180-min oral glucose tolerance test (OGTT) combined with constant intravenous infusion of [6,6-(2)H2]glucose and ingestion of [U-(13)C]glucose, following 1 h of exercise (50% of peak aerobic power) or rest. In both trials......OGTT, and Rd (all P value in NGT subjects when compared to IGT and T2D subjects. Accordingly, following exercise, the plasma glucose concentration during the OGTT was increased in NGT subjects (P

Prevalence of glucose-6-phosphate dehydrogenase (G6PD) deficiency among malaria patients in Upper Myanmar.

Science.gov (United States)

Lee, Jinyoung; Kim, Tae Im; Kang, Jung-Mi; Jun, Hojong; Lê, Hương Giang; Thái, Thị Lam; Sohn, Woon-Mok; Myint, Moe Kyaw; Lin, Khin; Kim, Tong-Soo; Na, Byoung-Kuk

2018-03-16

Glucose-6-phosphate dehydrogenase (G6PD; EC 1.1.1.49) deficiency is one of the most common X-linked recessive hereditary disorders in the world. Primaquine (PQ) has been used for radical cure of P. vivax to prevent relapse. Recently, it is also used to reduce P. falciparum gametocyte carriage to block transmission. However, PQ metabolites oxidize hemoglobin and generate excessive reactive oxygen species which can trigger acute hemolytic anemia in malaria patients with inherited G6PD deficiency. A total of 252 blood samples collected from malaria patients in Myanmar were used in this study. G6PD variant was analysed by a multiplex allele specific PCR kit, DiaPlexC™ G6PD Genotyping Kit [Asian type]. The accuracy of the multiplex allele specific PCR was confirmed by sequencing analysis. Prevalence and distribution of G6PD variants in 252 malaria patients in Myanmar were analysed. Six different types of G6PD allelic variants were identified in 50 (7 females and 43 males) malaria patients. The predominant variant was Mahidol (68%, 34/50), of which 91.2% (31/34) and 8.8% (3/34) were males and females, respectively. Other G6PD variants including Kaiping (18%, 9/50), Viangchan (6%, 3/50), Mediterranean (4%, 2/50), Union (2%, 1/50) and Canton (2%, 1/50) were also observed. Results of this study suggest that more concern for proper and safe use of PQ as a radical cure of malaria in Myanmar is needed by combining G6PD deficiency test before PQ prescription. Establishment of a follow-up system to monitor potential PQ toxicity in malaria patients who are given PQ is also required.

Opposite lipemic response of Wistar rats and C57BL/6 mice to dietary glucose or fructose supplementation

Directory of Open Access Journals (Sweden)

C.R. Barbosa

2007-03-01

Full Text Available The metabolic effects of carbohydrate supplementation in mice have not been extensively studied. In rats, glucose- and fructose-rich diets induce hypertriacylglycerolemia. In the present study, we compared the metabolic responses to two monosaccharide supplementations in two murine models. Adult male Wistar rats (N = 80 and C57BL/6 mice (N = 60, after 3 weeks on a standardized diet, were submitted to dietary supplementation by gavage with glucose (G or fructose (F solutions (500 g/L, 8 g/kg body weight for 21 days. Glycemia was significantly higher in rats after fructose treatment (F: 7.9 vs 9.3 mM and in mice (G: 6.5 vs 10 and F: 6.6 vs 8.9 mM after both carbohydrate treatments. Triacylglycerolemia increased significantly 1.5 times in rats after G or F supplementation. Total cholesterol did not change with G treatment in rats, but did decrease after F supplementation (1.5 vs 1.4 mM, P < 0.05. Both supplementations in rats induced insulin resistance, as suggested by the higher Homeostasis Model Assessment Index. In contrast, mice showed significant decreases in triacylglycerol (G: 1.8 vs 1.4 and F: 1.9 vs 1.4 mM, P < 0.01 and total cholesterol levels (G and F: 2.7 vs 2.5 mM, P < 0.05 after both monosaccharide supplementations. Wistar rats and C57BL/6 mice, although belonging to the same family (Muridae, presented opposite responses to glucose and fructose supplementation regarding serum triacylglycerol, free fatty acids, and insulin levels after monosaccharide treatment. Thus, while Wistar rats developed features of plurimetabolic syndrome, C57BL/6 mice presented changes in serum biochemical profile considered to be healthier for the cardiovascular system.

The effects of drought stress on the activity of acid phosphatase and ...

African Journals Online (AJOL)

A model of drought was created on pigweed and the effects of drought stress on the activity of acid phosphatase and its protective enzymes were examined. The pot-cultured pigweeds were divided into 4 groups (ten plants per group) when they reached 6 leaves. (1) In the control group, the culture media contained 70 ...

Protein tyrosine phosphatases: regulatory mechanisms.

NARCIS (Netherlands)

den Hertog, J.; Ostman, A.; Bohmer, F.D.

2008-01-01

Protein-tyrosine phosphatases are tightly controlled by various mechanisms, ranging from differential expression in specific cell types to restricted subcellular localization, limited proteolysis, post-translational modifications affecting intrinsic catalytic activity, ligand binding and

A new family of phosphoinositide phosphatases in microorganisms: identification and biochemical analysis

Directory of Open Access Journals (Sweden)

Bennett Hayley J

2010-08-01

Full Text Available Abstract Background Phosphoinositide metabolism is essential to membrane dynamics and impinges on many cellular processes, including phagocytosis. Modulation of phosphoinositide metabolism is important for pathogenicity and virulence of many human pathogens, allowing them to survive and replicate in the host cells. Phosphoinositide phosphatases from bacterial pathogens are therefore key players in this modulation and constitute attractive targets for chemotherapy. MptpB, a virulence factor from Mycobacterium tuberculosis, has phosphoinositide phosphatase activity and a distinct active site P-loop signature HCXXGKDR that shares characteristics with eukaryotic lipid phosphatases and protein tyrosine phosphatases. We used this P-loop signature as a "diagnostic motif" to identify related putative phosphatases with phosphoinositide activity in other organisms. Results We found more than 200 uncharacterised putative phosphatase sequences with the conserved signature in bacteria, with some related examples in fungi and protozoa. Many of the sequences identified belong to recognised human pathogens. Interestingly, no homologues were found in any other organisms including Archaea, plants, or animals. Phylogenetic analysis revealed that these proteins are unrelated to classic eukaryotic lipid phosphatases. However, biochemical characterisation of those from Listeria monocytogenes and Leishmania major, demonstrated that, like MptpB, they have phosphatase activity towards phosphoinositides. Mutagenesis studies established that the conserved Asp and Lys in the P-loop signature (HCXXGKDR are important in catalysis and substrate binding respectively. Furthermore, we provide experimental evidence that the number of basic residues in the P-loop is critical in determining activity towards poly-phosphoinositides. Conclusion This new family of enzymes in microorganisms shows distinct sequence and biochemical characteristics to classic eukaryotic lipid phosphatases

A new family of phosphoinositide phosphatases in microorganisms: identification and biochemical analysis.

Science.gov (United States)

Beresford, Nicola J; Saville, Charis; Bennett, Hayley J; Roberts, Ian S; Tabernero, Lydia

2010-08-02

Phosphoinositide metabolism is essential to membrane dynamics and impinges on many cellular processes, including phagocytosis. Modulation of phosphoinositide metabolism is important for pathogenicity and virulence of many human pathogens, allowing them to survive and replicate in the host cells. Phosphoinositide phosphatases from bacterial pathogens are therefore key players in this modulation and constitute attractive targets for chemotherapy. MptpB, a virulence factor from Mycobacterium tuberculosis, has phosphoinositide phosphatase activity and a distinct active site P-loop signature HCXXGKDR that shares characteristics with eukaryotic lipid phosphatases and protein tyrosine phosphatases. We used this P-loop signature as a "diagnostic motif" to identify related putative phosphatases with phosphoinositide activity in other organisms. We found more than 200 uncharacterised putative phosphatase sequences with the conserved signature in bacteria, with some related examples in fungi and protozoa. Many of the sequences identified belong to recognised human pathogens. Interestingly, no homologues were found in any other organisms including Archaea, plants, or animals. Phylogenetic analysis revealed that these proteins are unrelated to classic eukaryotic lipid phosphatases. However, biochemical characterisation of those from Listeria monocytogenes and Leishmania major, demonstrated that, like MptpB, they have phosphatase activity towards phosphoinositides. Mutagenesis studies established that the conserved Asp and Lys in the P-loop signature (HCXXGKDR) are important in catalysis and substrate binding respectively. Furthermore, we provide experimental evidence that the number of basic residues in the P-loop is critical in determining activity towards poly-phosphoinositides. This new family of enzymes in microorganisms shows distinct sequence and biochemical characteristics to classic eukaryotic lipid phosphatases and they have no homologues in humans. This study provides

Inhibition of protein tyrosine phosphatase (PTP1B) and α-glucosidase by geranylated flavonoids from Paulownia tomentosa.

Science.gov (United States)

Song, Yeong Hun; Uddin, Zia; Jin, Young Min; Li, Zuopeng; Curtis-Long, Marcus John; Kim, Kwang Dong; Cho, Jung Keun; Park, Ki Hun

2017-12-01

Protein tyrosine phosphatase 1B (PTP1B) and α-glucosidase are important targets to treat obesity and diabetes, due to their deep correlation with insulin and leptin signalling, and glucose regulation. The methanol extract of Paulownia tomentosa fruits showed potent inhibition against both enzymes. Purification of this extract led to eight geranylated flavonoids (1-8) displaying dual inhibition of PTP1B and α-glucosidase. The isolated compounds were identified as flavanones (1-5) and dihydroflavonols (6-8). Inhibitory potencies of these compounds varied accordingly, but most of the compounds were highly effective against PTP1B (IC 50  = 1.9-8.2 μM) than α-glucosidase (IC 50  = 2.2-78.9 μM). Mimulone (1) was the most effective against PTP1B with IC 50  = 1.9 μM, whereas 6-geranyl-3,3',5,5',7-pentahydroxy-4'-methoxyflavane (8) displayed potent inhibition against α-glucosidase (IC 50  = 2.2 μM). All inhibitors showed mixed type Ι inhibition toward PTP1B, and were noncompetitive inhibitors of α-glucosidase. This mixed type behavior against PTP1B was fully demonstrated by showing a decrease in V max , an increase of K m , and K ik /K iv ratio ranging between 2.66 and 3.69.

Glucose de-repression by yeast AMP-activated protein kinase SNF1 is controlled via at least two independent steps.

Science.gov (United States)

García-Salcedo, Raúl; Lubitz, Timo; Beltran, Gemma; Elbing, Karin; Tian, Ye; Frey, Simone; Wolkenhauer, Olaf; Krantz, Marcus; Klipp, Edda; Hohmann, Stefan

2014-04-01

The AMP-activated protein kinase, AMPK, controls energy homeostasis in eukaryotic cells but little is known about the mechanisms governing the dynamics of its activation/deactivation. The yeast AMPK, SNF1, is activated in response to glucose depletion and mediates glucose de-repression by inactivating the transcriptional repressor Mig1. Here we show that overexpression of the Snf1-activating kinase Sak1 results, in the presence of glucose, in constitutive Snf1 activation without alleviating glucose repression. Co-overexpression of the regulatory subunit Reg1 of the Glc-Reg1 phosphatase complex partly restores glucose regulation of Snf1. We generated a set of 24 kinetic mathematical models based on dynamic data of Snf1 pathway activation and deactivation. The models that reproduced our experimental observations best featured (a) glucose regulation of both Snf1 phosphorylation and dephosphorylation, (b) determination of the Mig1 phosphorylation status in the absence of glucose by Snf1 activity only and (c) a regulatory step directing active Snf1 to Mig1 under glucose limitation. Hence it appears that glucose de-repression via Snf1-Mig1 is regulated by glucose via at least two independent steps: the control of activation of the Snf1 kinase and directing active Snf1 to inactivating its target Mig1. © 2014 FEBS.

[A comparison of post-surgical plasma glucose levels in patients on fluids with different glucose concentrations].

Science.gov (United States)

Martínez Carapeto, Isabel; López Castilla, José Domingo; Fresneda Gutiérrez, Reyes

2017-11-11

To compare plasma glucose levels and incidence of hyperglycaemia in the post-operative period after general surgery using fluids with different glucose. A randomised, open-label, non-blind, clinical trial was conducted on patients admitted to Paediatric Intensive Care Unit after elective surgery. The inclusion criteria were from 6 months to 14 years of age, with a weight greater than 6kg, onset glucose level >60mg/dL, and a signed informed consent, with no oral intake and maintenance intravenous fluid therapy using fluids with 3.3% or 5% glucose. Plasma glucose levels were measured before surgery, on admission, and 8, 24, and 48h, with the mean glucose levels and incidence of hyperglycaemia (glucose level >150mg/dL) in both groups being compared. A total of 60 patients received glucose/saline 1/3 (51mEq/L sodium and 33g/L glucose), and 70 glucose/saline 5/0.9% (154mEq/L sodium and 50g/L glucose). Mean glucose levels were higher in the group receiving glucose 5%, with no statistical difference. There was no significant difference in the incidence of hyperglycaemia; 8h: 26% in the 3.3% group vs. 21.3% in the 5% group (P=.63); 24h: 20% vs. 22.7% (P=.8); and 48h: 19% vs. 23.1% (P=.78). The use of fluids with 3.3% glucose in the post-operative period of general surgery maintains mean glucose levels in a similar range to that of patients receiving fluids with 5% glucose, with no difference in the incidence of hyperglycaemia. Copyright © 2017. Publicado por Elsevier España, S.L.U.

Postprandial interleukin-6 release from skeletal muscle in men with impaired glucose tolerance can be reduced by weight loss

NARCIS (Netherlands)

Corpeleijn, E.; Saris, W.H.; Jansen, E.H.; Roekaerts, P.M.; Feskens, E.J.M.; Blaak, E.E.

2005-01-01

Context: Obesity and type 2 diabetes mellitus are associated with increased levels of IL-6, a marker of inflammation. Objective: This study addressed the question of whether IL-6 was released from skeletal muscle after a high-fat meal in men with impaired glucose tolerance (IGT), a prediabetic

Hypolipidemic and hypoglycemic activities of a oleanolic acid derivative from Malva parviflora on streptozotocin-induced diabetic mice.

Science.gov (United States)

Gutiérrez, Rosa Martha Pérez

2017-05-01

One new oleanolic acid derivative, 2α,3β,23α,29α tetrahydroxyolean-12(13)-en-28-oic acid (1) was isolated from the aerial parts of Malva parviflora. Their structure was characterized by spectroscopic methods. The hypolipidemic and hypoglycemic activities of 1 was analyzed in in streptozotocin (STZ)-nicotinamide-induced type 2 diabetes in mice (MD) and type 1 diabetes in streptozotocin-induced diabetic mice (SD). Triterpene was administered orally at doses of 20 mg/kg for 4 weeks. Organ weight, body weight, glucose, fasting insulin, cholesterol-related lipid profile parameters, glutamate oxaloacetate transaminase (SGOT), glutamate pyruvate transaminase (SGPT), serum alkaline phosphatase (SALP), glucokinase, hexokinase, glucose-6-phosphatase activities and glycogen in liver were measured after 4 weeks of treatment. The results indicated that 1 regulate glucose metabolism, lipid profile, lipid peroxidation, increased body weight, glucokinase and hexokinase activities inhibited triglycerides, total cholesterol, low density lipoproteins level, SGOT, SGPT, SALP, glycogen in liver and glucose-6-phosphatase. In addition, improvement of insulin resistance and protective effect for pancreatic β-cells, also 1 may changes the expression of pro-inflammatory cytokine (IL-6 and TNF-α levels) and enzymes (PAL2, COX-2, and LOX). The results suggest that 1 has hypolipidemic and hypoglycemic, anti-inflammatory, activities, improve insulin resistance and hepatic enzymes in streptozotocin-induced diabetic mice.

Dephosphorylation of chicken cardiac myofibril C-protein by protein phosphatases 1 and 2A

International Nuclear Information System (INIS)

Thysseril, T.J.; Hegazy, M.G.; Schlender, K.K.

1987-01-01

C-Protein, which is a regulatory component of cardiac muscle myofibrils, is phosphorylated in response to β-adrenergic agonists by a cAMP-dependent mechanism and dephosphorylated in response to cholinergic agonists. It is believed that the cAMP-dependent phosphorylation is due to cAMP-dependent protein kinase. The protein phosphatase(s) involved in the dephosphorylation of C-protein has not been determined. In this study, chicken cardiac C-protein was phosphorylated with the cAMP-dependent protein kinase to about 3 mol phosphate/mol C-protein. Incubation of [ 32 P]C-protein with the catalytic subunit of protein phosphatase 1 or 2A rapidly removed 30-40% of 32 [P]. Phosphopeptide maps and phosphoamino acid analysis revealed that the major site(s) dephosphorylated by either phosphatase was a phosphothreonine residue(s) located on the same tryptic peptide and on the same CNBr fragment. Increasing the incubation period or the phosphatase concentration did not result in any further dephosphorylation of C-protein by phosphatase 1, but phosphatase 2A completely dephosphorylated C-protein. Preliminary studies showed that the major protein phosphatase associated with the myofibril was phosphatase 2A. These results indicate the phosphatase 2A may be important in the regulation of the phosphorylation state of C-protein

Serum creatinine and alkaline phosphatase levels are associated with severe chronic periodontitis.

Science.gov (United States)

Caúla, A L; Lira-Junior, R; Tinoco, E M B; Fischer, R G

2015-12-01

Periodontitis may alter systemic homeostasis and influence creatinine and alkaline phosphatase levels. Therefore, the aim of this study was to evaluate the relationship between severe chronic periodontitis and serum creatinine and alkaline phosphatase levels. One hundred patients were evaluated, 66 with severe chronic periodontitis (test group) and 34 periodontally healthy controls (control group). Medical, demographic and periodontal parameters were registered. Blood sample was collected after an overnight fast and serum creatinine and alkaline phosphatase levels were determined. There were significant differences between test and control groups in ethnicity, gender and educational level (p creatinine level (p creatinine and alkaline phosphatase levels. Severe chronic periodontitis was associated to lower creatinine and higher alkaline phosphatase levels. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Glucose-responsive neurons in the subfornical organ of the rat--a novel site for direct CNS monitoring of circulating glucose.

Science.gov (United States)

Medeiros, N; Dai, L; Ferguson, A V

2012-01-10

Glucose-sensitive neurons have been identified in a number of CNS regions including metabolic control centers of the hypothalamus. The location of these regions behind the blood-brain barrier restricts them to sensing central, but not circulating glucose concentrations. In this study, we have used patch-clamp electrophysiology to examine whether neurons in a specialized region lacking the blood-brain barrier, the subfornical organ (SFO), are also glucose sensitive. In dissociated SFO neurons, altering the bath concentration of glucose (1 mM, 5 mM, 10 mM) influenced the excitability of 49% of neurons tested (n=67). Glucose-inhibited (GI) neurons depolarized in response to decreased glucose (n=10; mean, 4.6±1.0 mV) or hyperpolarized in response to increased glucose (n=8; mean,-4.4±0.8 mV). In contrast, glucose-excited (GE) neurons depolarized in response to increased glucose (n=9; mean, 6.4±0.4 mV) or hyperpolarized in response to decreased glucose (n=6; mean,-4.8±0.6 mV). Using voltage-clamp recordings, we also identified GI (outward current to increased glucose) and GE (inward current to increased glucose) SFO neurons. The mean glucose-induced inward current had a reversal potential of -24±12 mV (n=5), while GE responses were maintained during sodium-dependent glucose transporter inhibition, supporting the conclusion that GE properties result from the activation of a nonselective cation conductance (NSCC). The glucose-induced outward current had a mean reversal potential of -78±1.2 mV (n=5), while GI responses were not observed in the presence of glibenclamide, suggesting that these properties result from the modulation of K(ATP) channels. These data demonstrate that SFO neurons are glucose responsive, further emphasizing the potential roles of this circumventricular organ as an important sensor and integrator of circulating signals of energy status. Copyright © 2011 IBRO. Published by Elsevier Ltd. All rights reserved.

Acid phosphatase turnover during repressed and derepressed cultivation of Aspergillus niger

International Nuclear Information System (INIS)

Komano, Teruya

1975-01-01

Enhancement of the activity of acid phosphatase (EC 3.1.3.2) by phosphate starvation in growing Aspergillus niger mycelia was prevented by cycloheximide. This indicates that the enhancement was due to de novo protein synthesis caused by derepression. Radioactive acid phosphatase extracted from mycelia labeled with 14 C-amino acid was separated into at least four fractions. Experiments on pulse labeling and the chasing of the four acid phosphatases revealed the synthesis and degradation of each fraction occurred at different rates; showing a different rate of turnover of the enzyme molecules. The results of similar experiments performed during culture in the presence of phosphate (partially repressed condition) suggested that the marked change in the activity ratios of the four acid phosphatases during cultivation was the result of the active turnover of enzyme molecules. In contrast, the slight changes in the ratios observed during derepressed cultivation seemed to be the result of similar of synthesis and degradation of each phosphatase fraction. (auth.)

Cloning and expression of a widely expressed receptor tyrosine phosphatase

DEFF Research Database (Denmark)

Sap, J; D'Eustachio, P; Givol, D

1990-01-01

We describe the identification of a widely expressed receptor-type (transmembrane) protein tyrosine phosphatase (PTPase; EC 3.1.3.48). Screening of a mouse brain cDNA library under low-stringency conditions with a probe encompassing the intracellular (phosphatase) domain of the CD45 lymphocyte...... antigen yielded cDNA clones coding for a 794-amino acid transmembrane protein [hereafter referred to as receptor protein tyrosine phosphatase alpha (R-PTP-alpha)] with an intracellular domain displaying clear homology to the catalytic domains of CD45 and LAR (45% and 53%, respectively). The 142-amino acid...

Perfluorooctanoic acid exposure for 28 days affects glucose homeostasis and induces insulin hypersensitivity in mice

Science.gov (United States)

Yan, Shengmin; Zhang, Hongxia; Zheng, Fei; Sheng, Nan; Guo, Xuejiang; Dai, Jiayin

2015-06-01

Perfluoroalkyl acids (PFAAs) are widely used in many applications due to their unique physical and chemical characteristics. Because of the increasing prevalence of metabolic syndromes, including obesity, dyslipidemia and insulin resistance, concern has arisen about the roles of environmental pollutants in such diseases. Earlier epidemiologic studies showed a potential association between perfluorooctanoic acid (PFOA) and glucose metabolism, but how PFOA influences glucose homeostasis is still unknown. Here, we report on the modulation of the phosphatidylinositol 3-kinase-serine/threonine protein kinase (PI3K-AKT) signaling pathway in the livers of mice after 28 d of exposure to PFOA. Compared with normal mice, PFOA exposure significantly decreased the expression of the phosphatase and tensin homologue (PTEN) protein and affected the PI3K-AKT signaling pathway in the liver. Tolerance tests further indicated that PFOA exposure induced higher insulin sensitivity and glucose tolerance in mice. Biochemical analysis revealed that PFOA exposure reduced hepatic glycogen synthesis, which might be attributed to gluconeogenesis inhibition. The levels of several circulating proteins were altered after PFOA exposure, including proteins potentially related to diabetes and liver disease. Our results suggest that PFOA affected glucose metabolism and induced insulin hypersensitivity in mice.

Loss of peroxisomes causes oxygen insensitivity of the histochemical assay of glucose-6-phosphate dehydrogenase activity to detect cancer cells

NARCIS (Netherlands)

Frederiks, Wilma M.; Vreeling-Sindelárová, Heleen; van Noorden, Cornelis J. F.

2007-01-01

Oxygen insensitivity of carcinoma cells and oxygen sensitivity of non-cancer cells in the histochemical assay of glucose-6-phosphate dehydrogenase (G6PD) enables detection of carcinoma cells in unfixed cell smears or cryostat sections of biopsies. The metabolic background of oxygen insensitivity is

Dynamic Changes in Yeast Phosphatase Families Allow for Specialization in Phosphate and Thiamine Starvation.

Science.gov (United States)

Nahas, John V; Iosue, Christine L; Shaik, Noor F; Selhorst, Kathleen; He, Bin Z; Wykoff, Dennis D

2018-05-10

Convergent evolution is often due to selective pressures generating a similar phenotype. We observe relatively recent duplications in a spectrum of Saccharomycetaceae yeast species resulting in multiple phosphatases that are regulated by different nutrient conditions - thiamine and phosphate starvation. This specialization is both transcriptional and at the level of phosphatase substrate specificity. In Candida glabrata , loss of the ancestral phosphatase family was compensated by the co-option of a different histidine phosphatase family with three paralogs. Using RNA-seq and functional assays, we identify one of these paralogs, CgPMU3 , as a thiamine phosphatase. We further determine that the 81% identical paralog CgPMU2 does not encode thiamine phosphatase activity; however, both are capable of cleaving the phosphatase substrate, 1-napthyl-phosphate. We functionally demonstrate that members of this family evolved novel enzymatic functions for phosphate and thiamine starvation, and are regulated transcriptionally by either nutrient condition, and observe similar trends in other yeast species. This independent, parallel evolution involving two different families of histidine phosphatases suggests that there were likely similar selective pressures on multiple yeast species to recycle thiamine and phosphate. In this work, we focused on duplication and specialization, but there is also repeated loss of phosphatases, indicating that the expansion and contraction of the phosphatase family is dynamic in many Ascomycetes. The dynamic evolution of the phosphatase gene families is perhaps just one example of how gene duplication, co-option, and transcriptional and functional specialization together allow species to adapt to their environment with existing genetic resources. Copyright © 2018, G3: Genes, Genomes, Genetics.

Glucose-6-Phosphate Dehydrogenase: Update and Analysis of New Mutations around the World

Science.gov (United States)

Gómez-Manzo, Saúl; Marcial-Quino, Jaime; Vanoye-Carlo, America; Serrano-Posada, Hugo; Ortega-Cuellar, Daniel; González-Valdez, Abigail; Castillo-Rodríguez, Rosa Angélica; Hernández-Ochoa, Beatriz; Sierra-Palacios, Edgar; Rodríguez-Bustamante, Eduardo; Arreguin-Espinosa, Roberto

2016-01-01

Glucose-6-phosphate dehydrogenase (G6PD) is a key regulatory enzyme in the pentose phosphate pathway which produces nicotinamide adenine dinucleotide phosphate (NADPH) to maintain an adequate reducing environment in the cells and is especially important in red blood cells (RBC). Given its central role in the regulation of redox state, it is understandable that mutations in the gene encoding G6PD can cause deficiency of the protein activity leading to clinical manifestations such as neonatal jaundice and acute hemolytic anemia. Recently, an extensive review has been published about variants in the g6pd gene; recognizing 186 mutations. In this work, we review the state of the art in G6PD deficiency, describing 217 mutations in the g6pd gene; we also compile information about 31 new mutations, 16 that were not recognized and 15 more that have recently been reported. In order to get a better picture of the effects of new described mutations in g6pd gene, we locate the point mutations in the solved three-dimensional structure of the human G6PD protein. We found that class I mutations have the most deleterious effects on the structure and stability of the protein. PMID:27941691

Effect of vanadium compounds on acid phosphatase activity

OpenAIRE

Vescina, Cecilia M.; Sálice, Viviana C.; Cortizo, Ana María; Etcheverry, Susana B.

1996-01-01

The direct effect of different vanadium compounds on acid phosphatase (ACP) activity was investigated. Vanadate and vanadyl but not pervanadate inhibited the wheat germ ACP activity. These vanadium derivatives did not alter the fibroblast Swiss 3T3 soluble fraction ACP activity. Using inhibitors of tyrosine phosphatases (PTPases), the wheat germ ACP was partially characterized as a PTPase. This study suggests that the inhibitory ability of different vanadium derivatives to modulate ACP activi...

A family of metal-dependent phosphatases implicated in metabolite damage-control

Energy Technology Data Exchange (ETDEWEB)

Huang, Lili; Khusnutdinova, Anna; Nocek, Boguslaw; Brown, Greg; Xu, Xiaohui; Cui, Hong; Petit, Pierre; Flick, Robert; Zallot, Rémi; Balmant, Kelly; Ziemak, Michael J.; Shanklin, John; de Crécy-Lagard, Valérie; Fiehn, Oliver; Gregory, Jesse F.; Joachimiak, Andrzej; Savchenko, Alexei; Yakunin, Alexander F.; Hanson, Andrew D.

2016-06-20

DUF89 family proteins occur widely in both prokaryotes and eukaryotes, but their functions are unknown. Here we define three DUF89 subfamilies (I, II, and III), with subfamily II being split into stand-alone proteins and proteins fused to pantothenate kinase (PanK). We demonstrated that DUF89 proteins have metal-dependent phosphatase activity against reactive phosphoesters or their damaged forms, notably sugar phosphates (subfamilies II and III), phosphopantetheine and its S-sulfonate or sulfonate (subfamily II-PanK fusions), and nucleotides (subfamily I). Genetic and comparative genomic data strongly associated DUF89 genes with phosphoester metabolism. The crystal structure of the yeast (Saccharomyces cerevisiae) subfamily III protein YMR027W revealed a novel phosphatase active site with fructose 6-phosphate and Mg2+ bound near conserved signature residues Asp254 and Asn255 that are critical for activity. These findings indicate that DUF89 proteins are previously unrecognized hydrolases whose characteristic in vivo function is to limit potentially harmful buildups of normal or damaged phosphometabolites.

Sorbitol increases muscle glucose uptake ex vivo and inhibits intestinal glucose absorption ex vivo and in normal and type 2 diabetic rats.

Science.gov (United States)

Chukwuma, Chika Ifeanyi; Islam, Md Shahidul

2017-04-01

Previous studies have suggested that sorbitol, a known polyol sweetener, possesses glycemic control potentials. However, the effect of sorbitol on intestinal glucose absorption and muscle glucose uptake still remains elusive. The present study investigated the effects of sorbitol on intestinal glucose absorption and muscle glucose uptake as possible anti-hyperglycemic or glycemic control potentials using ex vivo and in vivo experimental models. Sorbitol (2.5% to 20%) inhibited glucose absorption in isolated rat jejuna (IC 50 = 14.6% ± 4.6%) and increased glucose uptake in isolated rat psoas muscle with (GU 50 = 3.5% ± 1.6%) or without insulin (GU 50 = 7.0% ± 0.5%) in a concentration-dependent manner. Furthermore, sorbitol significantly delayed gastric emptying, accelerated digesta transit, inhibited intestinal glucose absorption, and reduced blood glucose increase in both normoglycemic and type 2 diabetic rats after 1 h of coingestion with glucose. Data of this study suggest that sorbitol exhibited anti-hyperglycemic potentials, possibly via increasing muscle glucose uptake ex vivo and reducing intestinal glucose absorption in normal and type 2 diabetic rats. Hence, sorbitol may be further investigated as a possible anti-hyperglycemic sweetener.

Phosphoglycolate phosphatase and 2,3-diphosphoglycerate in red cells of normal and anemic subjects.

Science.gov (United States)

Somoza, R; Beutler, E

1983-10-01

Red cell phosphoglycolate phosphatase (PGP) and 2,3-diphosphoglycerate (2,3-DPG) were investigated in normal and anemic patients and rabbits. In hemolytic anemia and blood-loss anemia, characterized by a young red cell population, there was an increase in both phosphoglycolate phosphatase activity and 2,3-diphosphoglycerate levels. In aplastic anemia, the phosphoglycolate phosphatase activity was normal, but the 2,3-diphosphoglycerate values were nonetheless increased. Thus, no relationship was found between phosphoglycolate phosphatase activity and 2,3-diphosphoglycerate levels. The lack of correlation between the activity of phosphoglycolate phosphatase and 2,3-DPG levels suggests that modulation of phosphoglycolate phosphatase activity does not control the level of 2,3-DPG in erythrocytes.

Polimorfisme Enzim Glucose-6-Phosphate Isomerase pada Tiga Populasi Tuna Sirip Kuning (Thunnus albacares)

OpenAIRE

Permana, Gusti Ngurah; Hutapea, Jhon H.; Moria, Sari Budi; Haryanti, Haryanti

2006-01-01

Samples of yellowfin tuna (Thunnus albacares) were taken from three locations Bali, North Sulawesi and North Maluku. The glucose-6-phosphate isomerase (GPI) was analyzed from liver using allozyme electrophoresis method. Polymorphism of GPI enzyme was observed and four alleles (A, B ,C, D) were found in Bali population, three alleles (A,B,C) were found in North Maluku and North Sulawesi populations. Heterozygosity values, from Bali, North Maluku and North Sulawesi were 0.419; 0.417; 0.143 resp...

Glucose-Dependent Insulinotropic Polypeptide Mitigates 6-OHDA-Induced Behavioral Impairments in Parkinsonian Rats

Science.gov (United States)

Yu, Yu-Wen; Hsueh, Shih-Chang; Lai, Jing-Huei; Chen, Yen-Hua; Kang, Shuo-Jhen; Hsieh, Tsung-Hsun; Hoffer, Barry J.; Li, Yazhou; Greig, Nigel H.; Chiang, Yung-Hsiao

2018-01-01

In the present study, the effectiveness of glucose-dependent insulinotropic polypeptide (GIP) was evaluated by behavioral tests in 6-hydroxydopamine (6-OHDA) hemi-parkinsonian (PD) rats. Pharmacokinetic measurements of GIP were carried out at the same dose studied behaviorally, as well as at a lower dose used previously. GIP was delivered by subcutaneous administration (s.c.) using implanted ALZET micro-osmotic pumps. After two days of pre-treatment, male Sprague Dawley rats received a single unilateral injection of 6-OHDA into the medial forebrain bundle (MFB). The neuroprotective effects of GIP were evaluated by apomorphine-induced contralateral rotations, as well as by locomotor and anxiety-like behaviors in open-field tests. Concentrations of human active and total GIP were measured in plasma during a five-day treatment period by ELISA and were found to be within a clinically translatable range. GIP pretreatment reduced behavioral abnormalities induced by the unilateral nigrostriatal dopamine (DA) lesion produced by 6-OHDA, and thus may be a novel target for PD therapeutic development. PMID:29641447

Glucose-Dependent Insulinotropic Polypeptide Mitigates 6-OHDA-Induced Behavioral Impairments in Parkinsonian Rats

Directory of Open Access Journals (Sweden)

Yu-Wen Yu

2018-04-01

Full Text Available In the present study, the effectiveness of glucose-dependent insulinotropic polypeptide (GIP was evaluated by behavioral tests in 6-hydroxydopamine (6-OHDA hemi-parkinsonian (PD rats. Pharmacokinetic measurements of GIP were carried out at the same dose studied behaviorally, as well as at a lower dose used previously. GIP was delivered by subcutaneous administration (s.c. using implanted ALZET micro-osmotic pumps. After two days of pre-treatment, male Sprague Dawley rats received a single unilateral injection of 6-OHDA into the medial forebrain bundle (MFB. The neuroprotective effects of GIP were evaluated by apomorphine-induced contralateral rotations, as well as by locomotor and anxiety-like behaviors in open-field tests. Concentrations of human active and total GIP were measured in plasma during a five-day treatment period by ELISA and were found to be within a clinically translatable range. GIP pretreatment reduced behavioral abnormalities induced by the unilateral nigrostriatal dopamine (DA lesion produced by 6-OHDA, and thus may be a novel target for PD therapeutic development.

Importance of glucose-6-phosphate dehydrogenase (G6PDH) for vanillin tolerance in Saccharomyces cerevisiae.

Science.gov (United States)

Nguyen, Trinh Thi My; Kitajima, Sakihito; Izawa, Shingo

2014-09-01

Vanillin is derived from lignocellulosic biomass and, as one of the major biomass conversion inhibitors, inhibits yeast growth and fermentation. Vanillin was recently shown to induce the mitochondrial fragmentation and formation of mRNP granules such as processing bodies and stress granules in Saccharomyces cerevisiae. Furfural, another major biomass conversion inhibitor, also induces oxidative stress and is reduced in an NAD(P)H-dependent manner to its less toxic alcohol derivative. Therefore, the pentose phosphate pathway (PPP), through which most NADPH is generated, plays a role in tolerance to furfural. Although vanillin also induces oxidative stress and is reduced to vanillyl alcohol in a NADPH-dependent manner, the relationship between vanillin and PPP has not yet been investigated. In the present study, we examined the importance of glucose-6-phosphate dehydrogenase (G6PDH), which catalyzes the rate-limiting NADPH-producing step in PPP, for yeast tolerance to vanillin. The growth of the null mutant of G6PDH gene (zwf1Δ) was delayed in the presence of vanillin, and vanillin was efficiently reduced in the culture of wild-type cells but not in the culture of zwf1Δ cells. Furthermore, zwf1Δ cells easily induced the activation of Yap1, an oxidative stress responsive transcription factor, mitochondrial fragmentation, and P-body formation with the vanillin treatment, which indicated that zwf1Δ cells were more susceptible to vanillin than wild type cells. These findings suggest the importance of G6PDH and PPP in the response of yeast to vanillin. Copyright © 2014 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Mitogen activated protein kinase 6 and MAP kinase phosphatase 1 are involved in the response of Arabidopsis roots to L-glutamate.

Science.gov (United States)

López-Bucio, Jesús Salvador; Raya-González, Javier; Ravelo-Ortega, Gustavo; Ruiz-Herrera, León Francisco; Ramos-Vega, Maricela; León, Patricia; López-Bucio, José; Guevara-García, Ángel Arturo

2018-03-01

The function and components of L-glutamate signaling pathways in plants have just begun to be elucidated. Here, using a combination of genetic and biochemical strategies, we demonstrated that a MAPK module is involved in the control of root developmental responses to this amino acid. Root system architecture plays an essential role in plant adaptation to biotic and abiotic factors via adjusting signal transduction and gene expression. L-Glutamate (L-Glu), an amino acid with neurotransmitter functions in animals, inhibits root growth, but the underlying genetic mechanisms are poorly understood. Through a combination of genetic analysis, in-gel kinase assays, detailed cell elongation and division measurements and confocal analysis of expression of auxin, quiescent center and stem cell niche related genes, the critical roles of L-Glu in primary root growth acting through the mitogen-activated protein kinase 6 (MPK6) and the dual specificity serine-threonine-tyrosine phosphatase MKP1 could be revealed. In-gel phosphorylation assays revealed a rapid and dose-dependent induction of MPK6 and MPK3 activities in wild-type Arabidopsis seedlings in response to L-Glu. Mutations in MPK6 or MKP1 reduced or increased root cell division and elongation in response to L-Glu, possibly modulating auxin transport and/or response, but in a PLETHORA1 and 2 independent manner. Our data highlight MPK6 and MKP1 as components of an L-Glu pathway linking the auxin response, and cell division for primary root growth.

Increased muscle glucose uptake after exercise

DEFF Research Database (Denmark)

Richter, Erik; Ploug, Thorkil; Galbo, Henrik

1985-01-01

responsiveness of glucose uptake was noted only in controls. Analysis of intracellular glucose-6-phosphate, glucose, glycogen synthesis, and glucose transport suggested that the exercise effect on responsiveness might be due to enhancement of glucose disposal. After electrical stimulation of diabetic...... of glucose. At maximal insulin concentrations, the enhancing effect of exercise on glucose uptake may involve enhancement of glucose disposal, an effect that is probably less in muscle from diabetic rats.(ABSTRACT TRUNCATED AT 250 WORDS)......It has recently been shown that insulin sensitivity of skeletal muscle glucose uptake and glycogen synthesis is increased after a single exercise session. The present study was designed to determine whether insulin is necessary during exercise for development of these changes found after exercise...

Evidence That Speciation of Oxovanadium Complexes Does Not Solely Account for Inhibition of Leishmania Acid Phosphatases

Science.gov (United States)

Dorsey, Benjamin M.; McLauchlan, Craig C.; Jones, Marjorie A.

2018-01-01

Leishmaniasis is an endemic disease affecting a diverse spectra of populations, with 1.6 million new cases reported each year. Current treatment options are costly and have harsh side effects. New therapeutic options that have been previously identified, but still underappreciated as potential pharmaceutical targets, are Leishmania secreted acid phosphatases (SAP). These acid phosphatases, which are reported to play a role in the survival of the parasite in the sand fly vector, and in homing to the host macrophage, are inhibited by orthovanadate and decavanadate. Here, we use L. tarentolae to further evaluate these inhibitors. Using enzyme assays, and UV-visible spectroscopy, we investigate which oxovanadium starting material (orthovanadate or decavanadate) is a better inhibitor of L. tarentolae secreted acid phosphatase activity in vitro at the same total moles of vanadium. Considering speciation and total vanadium concentration, decavanadate is a consistently better inhibitor of SAP in our conditions, especially at low substrate:inhibitor ratios. PMID:29707535

Evidence that Speciation of Oxovanadium Complexes does not Solely Account for Inhibition of Leishmania Acid Phosphatases

Science.gov (United States)

Dorsey, Benjamin M.; McLauchlan, Craig C.; Jones, Marjorie A.

2018-04-01

Leishmaniasis is an endemic disease affecting a diverse spectra of populations, with 1.6 million new cases reported each year. Current treatment options are costly and have harsh side effects. New therapeutic options that have been previously identified, but still underappreciated as potential pharmaceutical targets, are Leishmania secreted acid phosphatases (SAP). These acid phosphatases, which are reported to play a role in the survival of the parasite in the sand fly vector, and in homing to the host macrophage, are inhibited by orthovanadate and decavanadate. Here, we use L. tarentolae to further evaluate these inhibitors. Using enzyme assays, and UV-visible spectroscopy, we investigate which oxovanadium starting material (orthovanadate or decavanadate) is a better inhibitor of L. tarentolae secreted acid phosphatase activity in vitro at the same total moles of vanadium. Considering speciation and total vanadium concentration, decavanadate is a consistently better inhibitor of SAP in our conditions, especially at low substrate:inhibitor ratios.

MAPK phosphatase AP2C3 induces ectopic proliferation of epidermal cells leading to stomata development in Arabidopsis.

Directory of Open Access Journals (Sweden)

Julija Umbrasaite

2010-12-01

Full Text Available In plant post-embryonic epidermis mitogen-activated protein kinase (MAPK signaling promotes differentiation of pavement cells and inhibits initiation of stomata. Stomata are cells specialized to modulate gas exchange and water loss. Arabidopsis MAPKs MPK3 and MPK6 are at the core of the signaling cascade; however, it is not well understood how the activity of these pleiotropic MAPKs is constrained spatially so that pavement cell differentiation is promoted only outside the stomata lineage. Here we identified a PP2C-type phosphatase termed AP2C3 (Arabidopsis protein phosphatase 2C that is expressed distinctively during stomata development as well as interacts and inactivates MPK3, MPK4 and MPK6. AP2C3 co-localizes with MAPKs within the nucleus and this localization depends on its N-terminal extension. We show that other closely related phosphatases AP2C2 and AP2C4 are also MAPK phosphatases acting on MPK6, but have a distinct expression pattern from AP2C3. In accordance with this, only AP2C3 ectopic expression is able to stimulate cell proliferation leading to excess stomata development. This function of AP2C3 relies on the domains required for MAPK docking and intracellular localization. Concomitantly, the constitutive and inducible AP2C3 expression deregulates E2F-RB pathway, promotes the abundance and activity of CDKA, as well as changes of CDKB1;1 forms. We suggest that AP2C3 downregulates the MAPK signaling activity to help maintain the balance between differentiation of stomata and pavement cells.

Comparison of the effects on insulin resistance and glucose tolerance of 6-mo high-monounsaturated-fat, low-fat, and control diets

DEFF Research Database (Denmark)

Due, Anette; Larsen, Thomas M; Hermansen, Kjeld

2008-01-01

and after the 6-mo dietary intervention. All foods were provided by a purpose-built supermarket. RESULTS: After 6 mo, the MUFA diet reduced fasting glucose (-3.0%), insulin (-9.4%), and the homeostasis model assessment of insulin resistance score (-12.1%). Compared with the MUFA diet, the control diet......BACKGROUND: The effect of dietary fat and carbohydrate on glucose metabolism has been debated for decades. OBJECTIVE: The objective was to compare the effect of 3 ad libitum diets, different in type and amount of fat and carbohydrate, on insulin resistance and glucose tolerance subsequent to weight...... loss. DESIGN: Forty-six nondiabetic, obese [mean (+/-SEM) body mass index (in kg/m(2)): 31.2 +/- 0.3] men (n = 20) and premenopausal women (n = 26) aged 28.0 +/- 0.7 y were randomly assigned to 1 of 3 diets after > or = 8% weight loss: 1) MUFA diet (n = 16): moderate in fat (35-45% of energy) and high...

Short and long-term effects of internal irradiation on the murine hepatic glycogen and its metabolizing enzymes

International Nuclear Information System (INIS)

Gupta, N.K.

1990-01-01

Glycogen content and the activities of phosphorylase, phosphorhexose isomerase, glucose 6-phosphatase, glycogen synthesis' phosphorylase and succinate dehydrogenase have been biochemically determined in the liver of Swiss albino mice after radiocalcium internal irradiation up to 225 days posttreatment. Increase in the glycogen content and glycogen synthesis phosphorylase with a concomitant decrease in the activities of phosphorylase, glucose 6-phosphatase, phosphohexose isomerase and succinate dehydrogenase reveals inhibited glycolysis in the presence of normal glyogenesis and inhibited Kreb's cycle in the liver during early intervals. Decrease in the glycogen content at later stages along with decrease in the activities of all these enzymes is probably because of an inhibited glycogen biosynthesis and its catabolism through HMP shunt. (orig.)

Characterization of the intravenous glucose tolerance test and the combined glucose-insulin test in donkeys.

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Mendoza, F J; Aguilera-Aguilera, R; Gonzalez-De Cara, C A; Toribio, R E; Estepa, J C; Perez-Ecija, A

2015-12-01

Glucose-insulin dynamic challenges such as the intravenous glucose tolerance test (IVGTT) and combined glucose-insulin test (CGIT) have not been described in donkeys. The objectives of this study were (1) to characterize the IVGTT and CGIT in healthy adult donkeys, and (2) to establish normal glucose-insulin proxies. Sixteen donkeys were used and body morphometric variables obtained each. For the IVGTT, glucose (300 mg/kg) was given IV. For the CGIT, glucose (150 mg/kg) followed by recombinant insulin (0.1 IU/kg) were administered IV. Blood samples for glucose and insulin determinations were collected over 300 min. In the IVGTT the positive phase lasted 160.9 ± 13.3 min, glucose concentration peaked at 323.1 ± 9.2 mg/dL and declined at a rate of 1.28 ± 0.15 mg/dL/min. The glucose area under the curve (AUC) was 21.4 ± 1.9 × 10(3) mg/dL/min and the insulin AUC was 7.2 ± 0.9 × 10(3) µIU/mL/min. The positive phase of the CGIT curve lasted 44 ± 3 min, with a glucose clearance rate of 2.01 ± 0.18 mg/dL/min. The negative phase lasted 255.9 ± 3 min, decreasing glucose concentration at rate of -0.63 ± 0.06 mg/dL/min, and reaching a nadir (33.1 ± 3.6 mg/dL) at 118.3 ± 6.3 min. The glucose and insulin AUC values were 15.2 ± 0.9 × 10(3) mg/dL/min and 13.2 ± 0.9 × 10(3) µIU/mL/min. This is the first study characterizing CGIT and IVGTT, and glucose-insulin proxies in healthy adult donkeys. Distinct glucose dynamics, when compared with horses, support the use of species-specific protocols to assess endocrine function. Copyright © 2015 Elsevier Ltd. All rights reserved.

Molecular analysis of glycogen storage disease type Ia in Iranian ...

Indian Academy of Sciences (India)

Here, we examined GSD Ia caused by the defective glucose-6-phosphatase catalytic (G6PC) gene. .... M, male; F, female; FBS, fasting blood sugar; TG, serum triglycerides; NA, not available; .... consanguinity: the homozygosity index (HI).

Lysophosphatidic acids are new substrates for the phosphatase domain of soluble epoxide hydrolase.

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Oguro, Ami; Imaoka, Susumu

2012-03-01

Soluble epoxide hydrolase (sEH) is a bifunctional enzyme that has a C-terminus epoxide hydrolase domain and an N-terminus phosphatase domain. The endogenous substrates of epoxide hydrolase are known to be epoxyeicosatrienoic acids, but the endogenous substrates of the phosphatase activity are not well understood. In this study, to explore the substrates of sEH, we investigated the inhibition of the phosphatase activity of sEH toward 4-methylumbelliferyl phosphate by using lecithin and its hydrolyzed products. Although lecithin itself did not inhibit the phosphatase activity, the hydrolyzed lecithin significantly inhibited it, suggesting that lysophospholipid or fatty acid can inhibit it. Next, we investigated the inhibition of phosphatase activity by lysophosphatidyl choline, palmitoyl lysophosphatidic acid, monopalmitoyl glycerol, and palmitic acid. Palmitoyl lysophosphatidic acid and fatty acid efficiently inhibited phosphatase activity, suggesting that lysophosphatidic acids (LPAs) are substrates for the phosphatase activity of sEH. As expected, palmitoyl, stearoyl, oleoyl, and arachidonoyl LPAs were efficiently dephosphorylated by sEH (Km, 3-7 μM; Vmax, 150-193 nmol/min/mg). These results suggest that LPAs are substrates of sEH, which may regulate physiological functions of cells via their metabolism.

Hyperuricemia Is a Risk Factor for the Onset of Impaired Fasting Glucose in Men with a High Plasma Glucose Level: A Community-Based Study

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Miyake, Teruki; Kumagi, Teru; Furukawa, Shinya; Hirooka, Masashi; Kawasaki, Keitarou; Koizumi, Mitsuhito; Todo, Yasuhiko; Yamamoto, Shin; Abe, Masanori; Kitai, Kohichiro; Matsuura, Bunzo; Hiasa, Yoichi

2014-01-01

Background It is not clear whether elevated uric acid is a risk factor for the onset of impaired fasting glucose after stratifying by baseline fasting plasma glucose levels. We conducted a community-based retrospective longitudinal cohort study to clarify the relationship between uric acid levels and the onset of impaired fasting glucose, according to baseline fasting plasma glucose levels. Methods We enrolled 6,403 persons (3,194 men and 3,209 women), each of whom was 18–80 years old and had >2 annual check-ups during 2003–2010. After excluding persons who had fasting plasma glucose levels ≥6.11 mM and/or were currently taking anti-diabetic agents, the remaining 5,924 subjects were classified into quartiles according to baseline fasting plasma glucose levels. The onset of impaired fasting glucose was defined as fasting plasma glucose ≥6.11 mM during the observation period. Results In the quartile groups, 0.9%, 2.1%, 3.4%, and 20.2% of the men developed impaired fasting glucose, respectively, and 0.1%, 0.3%, 0.5%, and 5.6% of the women developed impaired fasting glucose, respectively (P trend fasting glucose in men with highest-quartile fasting plasma glucose levels (adjusted hazard ratio, 1.003; 95% confidence interval, 1.0001–1.005, P = 0.041). Conclusions Among men with high fasting plasma glucose, hyperuricemia may be independently associated with an elevated risk of developing impaired fasting glucose. PMID:25237894

Somatic cell count and alkaline phosphatase activity in milk for evaluation of mastitis in buffalo

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Patil, M. P.; Nagvekar, A. S.; Ingole, S. D.; Bharucha, S. V.; Palve, V. T.

2015-01-01

Background and Aim: Mastitis is a serious disease of dairy animals causing great economic losses due to a reduction in milk yield as well as lowering its nutritive value. The application of somatic cell count (SCC) and alkaline phosphatase activity in the milk for diagnosis of mastitis in buffalo is not well documented. Therefore, the present study was conducted to observe the SCC and alkaline phosphatase activity for evaluation of mastitis in buffalo. Materials and Methods: Milk samples of forty apparently healthy lactating buffaloes were selected and categorized into five different groups viz. normal buffaloes, buffaloes with subclinical mastitis with CMT positive milk samples (+1 Grade), (+2 Grade), (+3 Grade), and buffaloes with clinical mastitis with 8 animals in each group. The milk samples were analyzed for SCC and alkaline phosphatase activity. Results: The levels of SCC (×105 cells/ml) and alkaline phosphatase (U/L) in different groups were viz. normal (3.21±0.179, 16.48±1.432), subclinical mastitis with CMT positive milk samples with +1 Grade (4.21±0.138, 28.11±1.013), with +2 Grade (6.34±0.183, 34.50±1.034), with +3 Grade (7.96±0.213, 37.73±0.737) and buffaloes with clinical mastitis (10.21±0.220, 42.37±0.907) respectively, indicating an increasing trend in the values and the difference observed among various group was statistically significant. Conclusion: In conclusion, the results of the present study indicate that the concentration of milk SCC and alkaline phosphatase activity was higher in the milk of buffaloes with mastitis than in the milk of normal buffaloes. PMID:27047098

Oral glucose tolerance test and continuous glucose monitoring to assess diabetes development in cystic fibrosis patients.

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Clemente León, María; Bilbao Gassó, Laura; Moreno-Galdó, Antonio; Campos Martorrell, Ariadna; Gartner Tizzano, Silvia; Yeste Fernández, Diego; Carrascosa Lezcano, Antonio

2018-01-01

Patients with cystic fibrosis (CF) undergo a slow and progressive process toward diabetes. Oral glucose tolerance test (OGTT) is recommended to diagnose impaired glucose levels in these patients. Continuous glucose monitoring (CGM) measures glucose profiles under real-life conditions. To compare OGTT and CGM results in CF patients. Paired OGTT and 6-day CGM profiles (146.2±9.1h/patient) were performed in 30 CF patients aged 10-18 years. According to OGTT, 14 patients had normal glucose tolerance (NGT), 14 abnormal glucose tolerance (AGT), and two cystic fibrosis-related diabetes (CFRD). In 27 patients (13 NGT, 13 AGT, 1 CFRD), CGM showed glucose values ranging from 140 to 200mg/dL during similar monitoring times (2%-14% with NGT, 1%-16.9% with AGT, and 3% with CFRD). Glucose peak levels ≥200mg/dL were seen in seven patients (3 NGT, 3 AGT, 1 CFRD). According to CGM, two patients had all glucose values under 140mg/dL (1 NGT, 1 AGT). Seventeen patients had glucose levels ranging from 140 to 200mg/dL (10 NGT, 6 AGT, 1 CFRD). Ten patients (3 NGT, 7 AGT) had glucose values ≥200mg/dL for ≤1% of the monitoring time and one (CFRD) for >1% of the monitoring time. OGTT results did not agree with those of the CGM. CGM allows for diagnosis of glucose changes not detected by OGTT. Such changes may contribute to optimize pre-diabetes management in CF patients. Copyright © 2017 SEEN y SED. Publicado por Elsevier España, S.L.U. All rights reserved.

Effects of in ovo feeding of carbohydrates and arginine on hatchability, body weight, energy metabolism and perinatal growth in duck embryos and neonates.

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Tangara, M; Chen, W; Xu, J; Huang, F R; Peng, J

2010-10-01

1. The objective of this study was to test the hypothesis that in ovo feeding of carbohydrates and arginine into the duck amnion may improve the glycogen store and perinatal growth. At 23 d of incubation, fertile eggs were injected with 1·2 ml of sodium chloride (NaCl), sucrose + maltose (CHO), arginine (Arg) or sucrose + maltose + arginine (CHO + Arg), with controls not injected. Body weight, liver and muscle glycogen levels, and hepatic glucose-6-phosphatase activity were determined at 25 d of incubation, at hatch, and at 3 and 7 d posthatch. 2. At hatch and 7 d of age, the body weights were greater in the in ovo-feeding treatments than the controls. Arg and CHO + Arg significantly enhanced liver glycogen level at hatch compared with controls. CHO and CHO + Arg significantly increased muscle glycogen level at 25 d of incubation over controls. CHO and Arg decreased glucose-6-phosphatase at 25 d of incubation, whereas NaCl and CHO + Arg increased glucose-6-phosphatase at hatch relative to controls. 3. In ovo feeding of carbohydrates and arginine at 23 d of incubation may improve glycogen reserves, which may, in turn, provide the energy needed for perinatal growth.

Autophagy Signaling in Prostate Cancer: Identification of a Novel Phosphatase

Science.gov (United States)

2013-01-01

chloroquine treatment] and LC3 accumulation used as a measure of autophagic flux (Tanida et al., 2005). We found that both knockdown of PTPs and amino acid...6 Jeffrey P. MacKeigan,3 Kyle A. Furge,2 H. Eric Xu1,7†D ow nloaded The antimalaria drug chloroquine has been used as an anti-inflammatory agent for...verified and characterized for phosphatase activity in vitro (task 2). In addition to inserting these constructs into mammalian expression vectors, used

A study of the alkaline and acid phosphatase activities in acute uranium intoxication

International Nuclear Information System (INIS)

Bokova, N.; Pavlova, V.; Stancheva, Yu.; Khadzhirusev, S.; Kiradzhiev, G.

1975-01-01

Comparative study of the ability of the sodium salt of diethylbarbituric acid and acetazolamide to protect the kidneys is conducted under conditions of acute uranium intoxication in rats. The parameters studied are alkaline and acid phosphatase activities in the serum and urine and phosphatase activity in the kidneys (histochemically as described by Gomori) followed up until the 30th day after the total uranyl acetate dose was reached (2 or 7 mg per kg bodyweight). Either compound exerted only minor effect on serum alkaline phosphatase activity. Sodium diethylbarbiturate induced distinct fluctuations in urinary alkaline phosphatase activity throughout the entire study period, but the differences never reached statistical significance. Acetazolamide caused essential decrease in urinary alkaline phosphatase activity. In either case renal tissue protection from the action of the uranyl ion may be suggested. This assumption is supported by the histochemical analysis. The compounds appeared to have no effect on serum acid phosphatase activity which showed high variability both in control and in treated rats. (Ch.K.)

Characterization of the Functional Domains of a Mammalian Voltage-Sensitive Phosphatase.

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Rosasco, Mario G; Gordon, Sharona E; Bajjalieh, Sandra M

2015-12-15

Voltage-sensitive phosphatases (VSPs) are proteins that directly couple changes in membrane electrical potential to inositol lipid phosphatase activity. VSPs thus couple two signaling pathways that are critical for cellular functioning. Although a number of nonmammalian VSPs have been characterized biophysically, mammalian VSPs are less well understood at both the physiological and biophysical levels. In this study, we aimed to address this gap in knowledge by determining whether the VSP from mouse, Mm-VSP, is expressed in the brain and contains a functional voltage-sensing domain (VSD) and a phosphatase domain. We report that Mm-VSP is expressed in neurons and is developmentally regulated. To address whether the functions of the VSD and phosphatase domain are retained in Mm-VSP, we took advantage of the modular nature of these domains and expressed each independently as a chimeric protein in a heterologous expression system. We found that the Mm-VSP VSD, fused to a viral potassium channel, was able to drive voltage-dependent gating of the channel pore. The Mm-VSP phosphatase domain, fused to the VSD of a nonmammalian VSP, was also functional: activation resulted in PI(4,5)P2 depletion that was sufficient to inhibit the PI(4,5)P2-regulated KCNQ2/3 channels. While testing the functionality of the VSD and phosphatase domain, we observed slight differences between the activities of Mm-VSP-based chimeras and those of nonmammalian VSPs. Although the properties of VSP chimeras may not completely reflect the properties of native VSPs, the differences we observed in voltage-sensing and phosphatase activity provide a starting point for future experiments to investigate the function of Mm-VSP and other mammalian VSPs. In conclusion, our data reveal that both the VSD and the lipid phosphatase domain of Mm-VSP are functional, indicating that Mm-VSP likely plays an important role in mouse neurophysiology. Copyright © 2015 Biophysical Society. Published by Elsevier Inc. All

Progression from impaired glucose tolerance to type 2 diabetes in obese children and adolescents: a 3-6-year cohort study in southern Thailand.

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Jaruratanasirikul, Somchit; Thammaratchuchai, Sudarat; Puwanant, Maneerat; Mo-Suwan, Ladda; Sriplung, Hutcha

2016-11-01

Childhood obesity is associated with abnormal glucose metabolism and type 2 diabetes mellitus (T2DM). This study evaluated the prevalence of abnormal glucose metabolism in asymptomatic obese children and adolescents, and determined the percentage of T2DM development after 3-6 years of follow-up. During 2007-2013, 177 obese children and adolescents who had normal fasting plasma glucose (FPG100 mg/dL) were given an oral glucose tolerance test (OGTT). The participants were classified into four groups: normal glucose tolerance (NGT), NGT-hyperinsulinemia (NGT-HI), impaired glucose tolerance (IGT), and diabetes mellitus (DM). Blood chemistries, including FPG, glycated hemoglobin, and lipid profiles, and liver function test were performed every 6-12 months or when the patient developed any symptom or sign indicative of diabetes. Glucose metabolism alterations were detected in 81.4% of the participants: 63.8% with NGT-HI, 15.3% with IGT, and 2.3% with T2DM. The median levels of homeostasis model assessment-insulin resistance (HOMA-IR) in patients with IGT (8.63) were significantly greater than those in the patients with NGT (4.04) (p1). During the follow-up, 22 patients (14.4%) developed T2DM significantly more from the IGT group (nine of 33 cases, 27.3%) than the NGT-HI group (12 of 108 cases, 11.1%) (p=0.022). The predicting parameters for T2DM conversion were weight status, body mass index (BMI), FBG, fasting insulin, alanine transaminase (ALT) levels, and HOMA-IR. Glucose metabolism alteration was commonly found among obese adolescents. Factors associated with T2DM development were greater weight status and the severity of insulin resistance as shown by higher HOMA-IR levels.

Effect of the consumption of β-lactoglobulin and epigallocatechin-3-gallate with or without calcium on glucose tolerance in C57BL/6 mice.

Science.gov (United States)

Carnovale, Valérie; Pilon, Geneviève; Britten, Michel; Bazinet, Laurent; Couillard, Charles

2016-01-01

Interactions between β-lactoglobulin (β-lg) and epigallocatechin-3-gallate (EGCG) may modulate their health benefits. The objective of this study was therefore to investigate the synergistic effect of consuming β-lg and EGCG complexes on glucose tolerance of C57BL/6 male mice given an oral glucose tolerance test (OGTT) and randomized to one of the following treatments administered prior to the OGTT: 1) simulated milk ultrafiltrate (SMUF(-)), 2) SMUF(-) + EGCG, 3) SMUF(-) + β-lg, 4) SMUF(-) + EGCG + β-lg, 5) SMUF + calcium (SMUF(+)) and 6) SMUF(+) + EGCG + β-lg. We found no significant between-group difference in postprandial glucose response. However, when mice were separated in those who received β-lg from those who did not, we found that the latter displayed significantly higher postprandial glucose concentrations. Our results support the beneficial impact of β-lg on glycemic control and suggest that concomitant EGCG or calcium consumption does not improve this effect.

Functional diversity of voltage-sensing phosphatases in two urodele amphibians.

Science.gov (United States)

Mutua, Joshua; Jinno, Yuka; Sakata, Souhei; Okochi, Yoshifumi; Ueno, Shuichi; Tsutsui, Hidekazu; Kawai, Takafumi; Iwao, Yasuhiro; Okamura, Yasushi

2014-07-16

Voltage-sensing phosphatases (VSPs) share the molecular architecture of the voltage sensor domain (VSD) with voltage-gated ion channels and the phosphoinositide phosphatase region with the phosphatase and tensin homolog (PTEN), respectively. VSPs enzymatic activities are regulated by the motions of VSD upon depolarization. The physiological role of these proteins has remained elusive, and insights may be gained by investigating biological variations in different animal species. Urodele amphibians are vertebrates with potent activities of regeneration and also show diverse mechanisms of polyspermy prevention. We cloned cDNAs of VSPs from the testes of two urodeles; Hynobius nebulosus and Cynops pyrrhogaster, and compared their expression and voltage-dependent activation. Their molecular architecture is highly conserved in both Hynobius VSP (Hn-VSP) and Cynops VSP (Cp-VSP), including the positively-charged arginine residues in the S4 segment of the VSD and the enzymatic active site for substrate binding, yet the C-terminal C2 domain of Hn-VSP is significantly shorter than that of Cp-VSP and other VSP orthologs. RT-PCR analysis showed that gene expression pattern was distinct between two VSPs. The voltage sensor motions and voltage-dependent phosphatase activities were investigated electrophysiologically by expression in Xenopus oocytes. Both VSPs showed "sensing" currents, indicating that their voltage sensor domains are functional. The phosphatase activity of Cp-VSP was found to be voltage dependent, as shown by its ability to regulate the conductance of coexpressed GIRK2 channels, but Hn-VSP lacked such phosphatase activity due to the truncation of its C2 domain. © 2014 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of the American Physiological Society and The Physiological Society.

Exenatide Regulates Cerebral Glucose Metabolism in Brain Areas Associated With Glucose Homeostasis and Reward System.

Science.gov (United States)

Daniele, Giuseppe; Iozzo, Patricia; Molina-Carrion, Marjorie; Lancaster, Jack; Ciociaro, Demetrio; Cersosimo, Eugenio; Tripathy, Devjit; Triplitt, Curtis; Fox, Peter; Musi, Nicolas; DeFronzo, Ralph; Gastaldelli, Amalia

2015-10-01

Glucagon-like peptide 1 receptors (GLP-1Rs) have been found in the brain, but whether GLP-1R agonists (GLP-1RAs) influence brain glucose metabolism is currently unknown. The study aim was to evaluate the effects of a single injection of the GLP-1RA exenatide on cerebral and peripheral glucose metabolism in response to a glucose load. In 15 male subjects with HbA1c of 5.7 ± 0.1%, fasting glucose of 114 ± 3 mg/dL, and 2-h glucose of 177 ± 11 mg/dL, exenatide (5 μg) or placebo was injected in double-blind, randomized fashion subcutaneously 30 min before an oral glucose tolerance test (OGTT). The cerebral glucose metabolic rate (CMRglu) was measured by positron emission tomography after an injection of [(18)F]2-fluoro-2-deoxy-d-glucose before the OGTT, and the rate of glucose absorption (RaO) and disposal was assessed using stable isotope tracers. Exenatide reduced RaO0-60 min (4.6 ± 1.4 vs. 13.1 ± 1.7 μmol/min ⋅ kg) and decreased the rise in mean glucose0-60 min (107 ± 6 vs. 138 ± 8 mg/dL) and insulin0-60 min (17.3 ± 3.1 vs. 24.7 ± 3.8 mU/L). Exenatide increased CMRglu in areas of the brain related to glucose homeostasis, appetite, and food reward, despite lower plasma insulin concentrations, but reduced glucose uptake in the hypothalamus. Decreased RaO0-60 min after exenatide was inversely correlated to CMRglu. In conclusion, these results demonstrate, for the first time in man, a major effect of a GLP-1RA on regulation of brain glucose metabolism in the absorptive state. © 2015 by the American Diabetes Association. Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered.

Glucose oxidase probe as a surface-enhanced Raman scattering sensor for glucose.

Science.gov (United States)

Qi, Guohua; Wang, Yi; Zhang, Biying; Sun, Dan; Fu, Cuicui; Xu, Weiqing; Xu, Shuping

2016-10-01

Glucose oxidase (GOx) possessing a Raman-active chromophore (flavin adenine dinucleotide) is used as a signal reporter for constructing a highly specific "turn off" surface-enhanced Raman scattering (SERS) sensor for glucose. This sensing chip is made by the electrostatic assembly of GOx over silver nanoparticle (Ag NP)-functionalized SERS substrate through a positively charged polyelectrolyte linker under the pH of 6.86. To trace glucose in blood serum, owing to the reduced pH value caused by the production of gluconic acid in the GOx-catalyzed oxidation reaction, the bonding force between GOx and polyelectrolyte weakens, making GOx drop off from the sensing chip. As a result, the SERS intensity of GOx on the chip decreases along with the concentration of glucose. This glucose SERS sensor exhibits excellent selectivity based on the specific GOx/glucose catalysis reaction and high sensitivity to 1.0 μM. The linear sensing range is 2.0-14.0 mM, which also meets the requirement on the working range of the human blood glucose detection. Using GOx as a probe shows superiority over other organic probes because GOx almost has no toxicity to the biological system. This sensing mechanism can be applied for intracellular in vivo SERS monitoring of glucose in the future. Graphical abstract Glucose oxidase is used as a Raman signal reporter for constructing a highly specific glucose surface-enhanced Raman scattering (SERS) sensor.

Reaction rate studies of glucose-6-phosphate dehydrogenase activity in sections of rat liver using four tetrazolium salts

NARCIS (Netherlands)

Butcher, R. G.; van Noorden, C. J.

1985-01-01

The reaction rate of glucose-6-phosphate dehydrogenase activity in liver sections from fed and starved rats has been monitored by the continuous measurement at 37 degrees C of the reaction product as it is formed using scanning and integrating microdensitometry. Control media lacked either substrate

The genetics of feto-placental development: A study of acid phosphatase locus 1 and adenosine deaminase polymorphisms in a consecutive series of newborn infants

Directory of Open Access Journals (Sweden)

Bergamaschi Antonio

2008-09-01

Full Text Available Abstract Background Acid phosphatase locus 1 and adenosine deaminase locus 1 polymorphisms show cooperative effects on glucose metabolism and immunological functions. The recent observation of cooperation between the two systems on susceptibility to repeated spontaneous miscarriage prompted us to search for possible interactional effects between these genes and the correlation between birth weight and placental weight. Deviation from a balanced development of the feto-placental unit has been found to be associated with perinatal morbidity and mortality and with cardiovascular diseases in adulthood. Methods We examined 400 consecutive newborns from the Caucasian population of Rome. Birth weight, placental weight, and gestational length were registered. Acid phosphatase locus 1 and adenosine deaminase locus 1 phenotypes were determined by starch gel electrophoresis and correlation analysis was performed by SPSS programs. Informed verbal consent to participate in the study was obtained from the mothers. Results Highly significant differences in birth weight-placental weight correlations were observed among acid phosphatase locus 1 phenotypes (p = 0.005. The correlation between birth weight and placental weight was markedly elevated in subjects carrying acid phosphatase locus 1 phenotypes with medium-low F isoform concentration (A, CA and CB phenotypes compared to those carrying acid phosphatase locus 1 phenotypes with medium-high F isoform concentration (BA and B phenotypes (p = 0.002. Environmental and developmental variables were found to exert a significant effect on birth weight-placental weight correlation in subjects with medium-high F isoform concentrations, but only a marginal effect was observed in those with medium-low F isoform concentrations. The correlation between birth weight and placental weight is higher among carriers of the adenosine deaminase locus 1 allele*2, which is associated with low activity, than in homozygous adenosine

Dysregulation of glucose metabolism even in Chinese PCOS women with normal glucose tolerance.

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Li, Weiping; Li, Qifu

2012-01-01

To clarify the necessity of improving glucose metabolism in polycystic ovary syndrome (PCOS) women as early as possible, 111 PCOS women with normal glucose tolerance and 92 healthy age-matched controls were recruited to investigate glucose levels distribution, insulin sensitivity and β cell function. 91 PCOS women and 33 controls underwent hyperinsulinemic-euglycemic clamp to assess their insulin sensitivity, which was expressed as M value. β cell function was estimated by homeostatic model assessment (HOMA)-β index after adjusting insulin sensitivity (HOMA-βad index). Compared with lean controls, lean PCOS women had similar fasting plasma glucose (FPG), higher postprandial plasma glucose (PPG) (6.03±1.05 vs. 5.44±0.97 mmol/L, PPCOS women had higher levels of both FPG (5.24±0.58 vs. 4.90±0.39, PPCOS women separately, and the cutoff of BMI indicating impaired β cell function of PCOS women was 25.545kg/m². In conclusion, insulin resistance and dysregulation of glucose metabolism were common in Chinese PCOS women with normal glucose tolerance. BMI ≥ 25.545kg/m² indicated impaired β cell function in PCOS women with normal glucose tolerance.

Glucose biosensor based on glucose oxidase immobilized on unhybridized titanium dioxide nanotube arrays

International Nuclear Information System (INIS)

Wang, Wei; Xie, Yibing; Du, Hongxiu; Xia, Chi; Wang, Yong; Tian, Fang

2014-01-01

A glucose biosensor has been fabricated by immobilizing glucose oxidase (GOx) on unhybridized titanium dioxide nanotube arrays using an optimized cross-linking technique. The TiO 2 nanotube arrays were synthesized directly on a titanium substrate by anodic oxidation. The structure and morphology of electrode material were characterized by X-ray diffraction and scanning electron microscopy. The electrochemical performances of the glucose biosensor were conducted by cyclic voltammetry and chronoamperometry measurements. It gives a linear response to glucose in the 0.05 to 0.65 mM concentration range, with a correlation coefficient of 0.9981, a sensitivity of 199.6 μA mM −1 cm −2 , and a detection limit as low as 3.8 µM. This glucose biosensor exhibited high selectivity for glucose determination in the presence of ascorbic acid, sucrose and other common interfering substances. This glucose biosensor also performed good reproducibility and long-time storage stability. This optimized cross-linking technique could open a new avenue for other enzyme biosensors fabrication. (author)

Hematopoietic cell phosphatase is recruited to CD22 following B cell antigen receptor ligation

NARCIS (Netherlands)

Lankester, A. C.; van Schijndel, G. M.; van Lier, R. A.

1995-01-01

Hematopoietic cell phosphatase is a nonreceptor protein tyrosine phosphatase that is preferentially expressed in hematopoietic cell lineages. Motheaten mice, which are devoid of (functional) hematopoietic cell phosphatase, have severe disturbances in the regulation of B cell activation and

Phylogenetic characterization of phosphatase-expressing bacterial communities in Baltic Sea sediments

NARCIS (Netherlands)

Steenbergh, Anne; Bodelier, Paul; Hoogveld, H.L.; Slomp, C.P; Laanbroek, H.J.

2015-01-01

Phosphate release from sediments hampers the remediation of aquatic systems from a eutrophic state. Microbial phosphatases in sediments release phosphorus during organic matter degradation. Despite the important role of phosphatase-expressing bacteria, the identity of these bacteria in sediments is

Somatic cell count and alkaline phosphatase activity in milk for evaluation of mastitis in buffalo

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M. P. Patil

2015-03-01

Full Text Available Background and Aim: Mastitis is a serious disease of dairy animals causing great economic losses due to a reduction in milk yield as well as lowering its nutritive value. The application of somatic cell count (SCC and alkaline phosphatase activity in the milk for diagnosis of mastitis in buffalo is not well documented. Therefore, the present study was conducted to observe the SCC and alkaline phosphatase activity for evaluation of mastitis in buffalo. Materials and Methods: Milk samples of forty apparently healthy lactating buffaloes were selected and categorized into five different groups viz. normal buffaloes, buffaloes with subclinical mastitis with CMT positive milk samples (+1 Grade, (+2 Grade, (+3 Grade, and buffaloes with clinical mastitis with 8 animals in each group. The milk samples were analyzed for SCC and alkaline phosphatase activity. Results: The levels of SCC (×105 cells/ml and alkaline phosphatase (U/L in different groups were viz. normal (3.21±0.179, 16.48±1.432, subclinical mastitis with CMT positive milk samples with +1 Grade (4.21±0.138, 28.11±1.013, with +2 Grade (6.34±0.183, 34.50±1.034, with +3 Grade (7.96±0.213, 37.73±0.737 and buffaloes with clinical mastitis (10.21±0.220, 42.37±0.907 respectively, indicating an increasing trend in the values and the difference observed among various group was statistically significant. Conclusion: In conclusion, the results of the present study indicate that the concentration of milk SCC and alkaline phosphatase activity was higher in the milk of buffaloes with mastitis than in the milk of normal buffaloes.

Yeast Acid Phosphatases and Phytases: Production, Characterization and Commercial Prospects

Science.gov (United States)

Kaur, Parvinder; Satyanarayana, T.

The element phosphorus is critical to all life forms as it forms the basic component of nucleic acids and ATP and has a number of indispensable biochemical roles. Unlike C or N, the biogeochemical cycling of phosphorus is very slow, and thus making it the growth-limiting element in most soils and aquatic systems. Phosphohydrolases (e.g. acid phosphatases and phytases) are enzymes that break the C-O-P ester bonds and provide available inorganic phosphorus from various inassimilable organic forms of phosphorus like phytates. These enzymes are of significant value in effectively combating phosphorus pollution. Although phytases and acid phosphatases are produced by various plants, animals and micro organisms, microbial sources are more promising for the production on a commercial scale. Yeasts being the simplest eukaryotes are ideal candidates for phytase and phos-phatase research due to their mostly non-pathogenic and GRAS status. They have not, however, been utilized to their full potential. This chapter focuses attention on the present state of knowledge on the production, characterization and potential commercial prospects of yeast phytases and acid phosphatases.

Enhanced glucose tolerance in pancreatic-derived factor (PANDER knockout C57BL/6 mice

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Shari L. Moak

2014-11-01

Full Text Available Pancreatic-derived factor (PANDER; also known as FAM3B is a uniquely structured protein strongly expressed within and secreted from the endocrine pancreas. PANDER has been hypothesized to regulate fasting and fed glucose homeostasis, hepatic lipogenesis and insulin signaling, and to serve a potential role in the onset or progression of type 2 diabetes (T2D. Despite having potentially pivotal pleiotropic roles in glycemic regulation and T2D, there has been limited generation of stable animal models for the investigation of PANDER function, and there are no models on well-established genetic murine backgrounds for T2D. Our aim was to generate an enhanced murine model to further elucidate the biological function of PANDER. Therefore, a pure-bred PANDER knockout C57BL/6 (PANKO-C57 model was created and phenotypically characterized with respect to glycemic regulation and hepatic insulin signaling. The PANKO-C57 model exhibited an enhanced metabolic phenotype, particularly with regard to enhanced glucose tolerance. Male PANKO-C57 mice displayed decreased fasting plasma insulin and C-peptide levels, whereas leptin levels were increased as compared with matched C57BL/6J wild-type mice. Despite similar peripheral insulin sensitivity between both groups, hepatic insulin signaling was significantly increased during fasting conditions, as demonstrated by increased phosphorylation of hepatic PKB/Akt and AMPK, along with mature SREBP-1 expression. Insulin stimulation of PANKO-C57 mice resulted in increased hepatic triglyceride and glycogen content as compared with wild-type C57BL/6 mice. In summary, the PANKO-C57 mouse represents a suitable model for the investigation of PANDER in multiple metabolic states and provides an additional tool to elucidate the biological function and potential role in T2D.

Altered oxidative stress and carbohydrate metabolism in canine mammary tumors

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K. Jayasri

2016-12-01

Full Text Available Aim: Mammary tumors are the most prevalent type of neoplasms in canines. Even though cancer induced metabolic alterations are well established, the clinical data describing the metabolic profiles of animal tumors is not available. Hence, our present investigation was carried out with the aim of studying changes in carbohydrate metabolism along with the level of oxidative stress in canine mammary tumors. Materials and Methods: Fresh mammary tumor tissues along with the adjacent healthy tissues were collected from the college surgical ward. The levels of thiobarbituric acid reactive substances (TBARS, glutathione, protein, hexose, hexokinase, glucose-6-phosphatase, fructose-1, 6-bisphosphatase, and glucose-6-phosphate dehydrogenase (G6PD were analyzed in all the tissues. The results were analyzed statistically. Results: More than two-fold increase in TBARS and three-fold increase in glutathione levels were observed in neoplastic tissues. Hexokinase activity and hexose concentration (175% was found to be increased, whereas glucose-6-phosphatase (33%, fructose-1, 6-bisphosphatase (42%, and G6PD (5 fold activities were reduced in tumor mass compared to control. Conclusion: Finally, it was revealed that lipid peroxidation was increased with differentially altered carbohydrate metabolism in canine mammary tumors.

Coping with an exogenous glucose overload: glucose kinetics of rainbow trout during graded swimming.

Science.gov (United States)

Choi, Kevin; Weber, Jean-Michel

2016-03-15

This study examines how chronically hyperglycemic rainbow trout modulate glucose kinetics in response to graded exercise up to critical swimming speed (Ucrit), with or without exogenous glucose supply. Our goals were 1) to quantify the rates of hepatic glucose production (Ra glucose) and disposal (Rd glucose) during graded swimming, 2) to determine how exogenous glucose affects the changes in glucose fluxes caused by exercise, and 3) to establish whether exogenous glucose modifies Ucrit or the cost of transport. Results show that graded swimming causes no change in Ra and Rd glucose at speeds below 2.5 body lengths per second (BL/s), but that glucose fluxes may be stimulated at the highest speeds. Excellent glucoregulation is also achieved at all exercise intensities. When exogenous glucose is supplied during exercise, trout suppress hepatic production from 16.4 ± 1.6 to 4.1 ± 1.7 μmol·kg(-1)·min(-1) and boost glucose disposal to 40.1 ± 13 μmol·kg(-1)·min(-1). These responses limit the effects of exogenous glucose to a 2.5-fold increase in glycemia, whereas fish showing no modulation of fluxes would reach dangerous levels of 114 mM of blood glucose. Exogenous glucose reduces metabolic rate by 16% and, therefore, causes total cost of transport to decrease accordingly. High glucose availability does not improve Ucrit because the fish are unable to take advantage of this extra fuel during maximal exercise and rely on tissue glycogen instead. In conclusion, trout have a remarkable ability to adjust glucose fluxes that allows them to cope with the cumulative stresses of a glucose overload and graded exercise. Copyright © 2016 the American Physiological Society.

Evaluation of Glucose-6-Phosphate Dehydrogenase stability in stored blood samples.

Science.gov (United States)

Jalil, Norunaluwar; Azma, Raja Zahratul; Mohamed, Emida; Ithnin, Azlin; Alauddin, Hafiza; Baya, Siti Noor; Othman, Ainoon

2016-01-01

Glucose-6-Phosphate Dehydrogenase (G6PD) deficiency is the commonest cause of neonatal jaundice in Malaysia. Recently, OSMMR2000-D G6PD Assay Kit has been introduced to quantitate the level of G6PD activity in newborns delivered in Universiti Kebangsaan Malaysia Medical Centre (UKMMC). As duration of sample storage prior to analysis is one of the matters of concern, this study was conducted to identify the stability of G6PD enzyme during storage. A total of 188 cord blood samples from normal term newborns delivered at UKMMC were selected for this study. The cord bloods samples were collected in ethylene-diamine-tetra-acetic acid (EDTA) tubes and refrigerated at 2-8 °C. In addition, 32 out of 188 cord blood samples were spotted on chromatography paper, air-dried and stored at room temperature. G6PD enzyme activities were measured daily for 7 days using the OSMMR2000-D G6PD Assay Kit on both the EDTA blood and dried blood samples. The mean value for G6PD activity was compared between days of analysis using Student Paired T-Test. In this study, 172 out of 188 cord blood samples showed normal enzyme levels while 16 had levels corresponding to severe enzyme deficiency. The daily mean G6PD activity for EDTA blood samples of newborns with normal G6PD activity showed a significant drop on the fourth day of storage (p samples with severely deficient G6PD activity, significant drop was seen on third day of storage (p = 0.002). Analysis of dried cord blood showed a significant reduction in enzyme activity as early as the second day of storage (p = 0.001). It was also noted that mean G6PD activity for spotted blood samples were lower compared to those in EDTA tubes for all days (p = 0.001). Thus, EDTA blood samples stored at 2-8 °C appeared to have better stability in terms of their G6PD enzyme level as compared to dried blood samples on filter paper, giving a storage time of up to 3 days.

Changes in hepatic glucose and lipid metabolism-related parameters in domestic pigeon (Columba livia) during incubation and chick rearing.

Science.gov (United States)

Wan, X P; Xie, P; Bu, Z; Zou, X T

2018-04-01

This study aimed to evaluate the hepatic glucose and lipid metabolism-related parameters of adult male and female White King pigeons (Columba livia) during incubation and chick rearing. At day 4 (I4), 10 (I10) and 17 (I17) of incubation and day 1 (R1), 7 (R7), 15 (R15) and 25 (R25) of chick rearing, livers were sampled from six pigeons for each sex. Glycogen and fat contents, activities of glycolytic enzymes (hexokinase, HK; 6-phosphofructokinase, 6-PFK), and genes expressions of key enzymes involved in glycolysis (pyruvate kinase, PK; glucokinase, GK), gluconeogenesis (phosphoenolpyruvate carboxykinase cytosolic, PCK1; fructose-1,6-bisphosphatase, FBP1; glucose-6-phosphatase, G6Pase), fatty acid synthesis (fatty acid synthase, FAS; acetyl-CoA carboxylase, ACC) and fatty acid β-oxidation (carnitine palmitoyltransferase 1, CPT1; acyl-CoA 1, ACO) were measured. In male and female pigeon livers, glycogen content and HK activity dramatically increased after I17 and after R1, respectively; expressions of FBP1 and G6Pase genes were maximized at R15; activity of 6-PFK and expressions of PK and CPT1 genes were highest at R7; fat content and expressions of FAS and ACC genes steeply increased from I10 to R1. In females, hepatic expressions of GK and PCK1 genes were greatest at R7 and I17, respectively; however, in males, both of them were maximized at R15. Hepatic expression of ACO gene was significantly enhanced at R1 compared to I17 and R7 in males, whereas it was notably up-regulated at I17 and R7 in females. Furthermore, expressions of PCK1, GK, FAS and ACC genes were in significant relation to fat content in the livers of female pigeons, while fat content in male pigeons was highly correlated with expression of PCK1, ACC, CPT1 and ACO genes. In conclusion, regulations of glucose and lipid metabolic processes were enhanced in parent pigeon livers from terminal phases of incubation to mid phase of chick rearing with sexual effects. © 2017 Blackwell Verlag GmbH.

Reduced glutathione and glutathione disulfide in the blood of glucose-6-phosphate dehydrogenase-deficient newborns.

Science.gov (United States)

Gong, Zhen-Hua; Tian, Guo-Li; Huang, Qi-Wei; Wang, Yan-Min; Xu, Hong-Ping

2017-07-20

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is commonly detected during mass screening for neonatal disease. We developed a method to measure reduced glutathione (GSH) and glutathione disulfide (GSSG) using tandem mass spectrometry (MS/MS) for detecting G6PD deficiency. The concentration of GSH and the GSH/GSSG ratio in newborn dry-blood-spot (DBS) screening and in blood plus sodium citrate for test confirmation were examined by MS/MS using labeled glycine as an internal standard. G6PD-deficient newborns had a lower GSH content (242.9 ± 15.9 μmol/L)and GSH/GSSG ratio (14.9 ± 7.2) than neonatal controls (370.0 ± 53.2 μmol/L and 46.7 ± 19.6, respectively). Although the results showed a significance of P blood measured using MS/MS on the first day of sample preparation are consistent with G6PD activity and are helpful for diagnosing G6PD deficiency.

Gene Therapy Vector for the Treatment of Glycogen Storage Disease Type Ia (GSD-Ia) | NCI Technology Transfer Center | TTC

Science.gov (United States)

GSD-Ia is an inherited disorder of metabolism associated with life-threatening hypoglycemia, hepatic malignancy, and renal failure caused by the deficiency of glucose-6-phosphatase-alpha (G6Pase-alpha or G6PC). NICHD seeks parties to license this invention towards commercialization.

The glucose-galactose paradox in neonatal murine hepatic glycogen synthesis

International Nuclear Information System (INIS)

Kunst, C.; Kliegman, R.; Trindade, C.

1989-01-01

In adults glucose incorporation to glycogen is indirect after recycling from lactate. In neonates galactose entry to glycogen exceeds that for glucose, but the pathway is unknown. The pathway of hexose incorporation to glycogen was studied in 5-7-day-old rats and 6-h-old rats injected intraperitoneally (IP) with either double-labeled [6-3H]glucose (nonrecycling), [U-14C]glucose (recycling), or [6-3H]glucose and [U-14C]galactose in saline. In another group of pups, 1 g/kg of glucose or galactose was administered in addition to tracers to determine glycemia and net glycogen synthesis between 15 and 180 min after injection. Blood glucose increased from 3.4 +/- 0.4 to 8.5 +/- 1.5 mM in 5-7-day-old pups in response to IP glucose; there was no glycemic response to galactose, although galactose levels increased from 0.5 to 6.3 mM at 15 min. Hepatic glycogen increased after IP glucose from 14 +/- 2 at 15 min to 30 +/- 3 at 120 min (P less than 0.01), whereas after IP galactose glycogen was 44 +/- 6 mumol/g at 120 min (P less than 0.05). After IP glucose, 3H and 14C disintegration per minute in glycogen increased slowly with 14C exceeding 3H at 120 and 180 min. In contrast IP [14C]galactose resulted in a much greater peak of 14C incorporation into glycogen. The ratio of 3H to 14C in glycogen relative to the injectate after IP glucose decreased from 0.69 +/- 0.12 to 0.36 +/- 0.03 (P less than 0.01) between 15 to 180 min, whereas the ratio after galactose was 0.20 +/- 0.007 to 0.15 +/- 0.02 at these times. The 6-h-old pups also demonstrated augmented incorporation of [14C]galactose in glycogen relative to [3H-14C]glucose. In contrast to 5-7-day-old pups there was no evidence of glucose recycling in 6-h-old pups. In conclusion galactose entry into glycogen exceeds that for glucose and is not dependent on recycling

Wheat bran with enriched gamma-aminobutyric acid attenuates glucose intolerance and hyperinsulinemia induced by a high-fat diet.

Science.gov (United States)

Shang, Wenting; Si, Xu; Zhou, Zhongkai; Strappe, Padraig; Blanchard, Chris

2018-05-23

In this study, the level of gamma-aminobutyric acid (GABA) in wheat bran was increased to be six times higher through the action of endogenous glutamate decarboxylase compared with untreated bran. The process of GABA formation in wheat bran also led to an increased level of phenolic compounds with enhanced antioxidant capacity 2 times higher than the untreated status. The interventional effect of a diet containing GABA-enriched bran on hyperinsulinemia induced by a high-fat diet (HFD) was investigated in a rat model. The results showed that, when compared with animals fed with HFD-containing untreated bran (NB group), the consumption of HFD-containing GABA-enriched bran (GB group) demonstrated a greater improvement of insulin resistance/sensitivity as revealed by the changes in the homeostatic model assessment for insulin resistance index (HOMA-IR) and the quantitative insulin sensitivity check index (QUICKI). The expression of hepatic genes, cytochrome P450 family 7 subfamily A member 1 (Cyp7a1) and ubiquitin C (Ubc), which are involved in the adipogenesis-associated PPAR signalling pathway, was found to be significantly down-regulated in the GB group compared with the HFD group (P = 0.0055). Meanwhile, changes in the expression of a number of genes associated with lipid metabolism and gluconeogenesis were also noted in the GB group versus the HFD group, but not in the NB group, indicating different regulatory patterns between the two brans in a high-fat diet. More importantly, the analysis of key genes related to glucose metabolism further revealed that the expression of insulin-induced gene 1/2 (Insig-1/2) was increased following GB intervention with a corresponding reduction in phosphoenolpyruvate carboxykinase 1 (Pepck) and glucose-6-phosphatase, catalytic subunit (G6pc) expression, suggesting that glucose homeostasis is greatly improved through the intervention of GABA-enriched bran in the context of a high-fat diet.

Five novel glucose-6-phosphate dehydrogenase deficiency haplotypes correlating with disease severity

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Dallol Ashraf

2012-09-01

Full Text Available Abstract Background Glucose-6-phosphate dehydrogenase (G6PD, EC 1.1.1.49 deficiency is caused by one or more mutations in the G6PD gene on chromosome X. An association between enzyme levels and gene haplotypes remains to be established. Methods In this study, we determined G6PD enzyme levels and sequenced the coding region, including the intron-exon boundaries, in a group of individuals (163 males and 86 females who were referred to the clinic with suspected G6PD deficiency. The sequence data were analysed by physical linkage analysis and PHASE haplotype reconstruction. Results All previously reported G6PD missense changes, including the AURES, MEDITERRANEAN, A-, SIBARI, VIANGCHAN and ANANT, were identified in our cohort. The AURES mutation (p.Ile48Thr was the most common variant in the cohort (30% in males patients followed by the Mediterranean variant (p.Ser188Phe detectable in 17.79% in male patients. Variant forms of the A- mutation (p.Val68Met, p.Asn126Asp or a combination of both were detectable in 15.33% of the male patients. However, unique to this study, several of such mutations co-existed in the same patient as shown by physical linkage in males or PHASE haplotype reconstruction in females. Based on 6 non-synonymous variants of G6PD, 13 different haplotypes (13 in males, 8 in females were identified. Five of these were previously unreported (Jeddah A, B, C, D and E and were defined by previously unreported combinations of extant mutations where patients harbouring these haplotypes exhibited severe G6PD deficiency. Conclusions Our findings will help design a focused population screening approach and provide better management for G6PD deficiency patients.

[Effect of estradiol on food intake, glucose and fat metabolism in mice C57BL/6J with mutation yellow at the agouti locus].

Science.gov (United States)

Iakovleva, T V; Makarova, E N; Kazantseva, A Iu; Bazhan, N M

2012-05-01

Mutation yellow at the agouti locus in mice (A(y)/a-mice) causes the increase of food intake and development of obesity and type 2 diabetes. In A(y)/a-females the disturbances of glucose and fat metabolisms occur after puberty. We have assumed that the mutation yellow violates the regulatory effect of estradiol on glucose and fat metabolism in mice. We investigated the effects of ovariectomy and estradiol treatment on body weight, food intake, glucose tolerance, plasma levels of glucose, insulin and etherified fatty acids in A(y)/a-females. C57Bl/6J females, not carrying yellow mutation at the agouti locus (a/a-mice), were used as a control. The data suggest that the yellow mutation did not affect estradiol regulation of food intake and glucose blood levels after a night of fasting, but, apparently, prevented estradiol participation in the regulation of glucose and fat metabolisms in the muscle and fat tissues.

Mitochondria-associated endoplasmic reticulum membranes allow adaptation of mitochondrial metabolism to glucose availability in the liver.

Science.gov (United States)

Theurey, Pierre; Tubbs, Emily; Vial, Guillaume; Jacquemetton, Julien; Bendridi, Nadia; Chauvin, Marie-Agnès; Alam, Muhammad Rizwan; Le Romancer, Muriel; Vidal, Hubert; Rieusset, Jennifer

2016-04-01

Mitochondria-associated endoplasmic reticulum membranes (MAM) play a key role in mitochondrial dynamics and function and in hepatic insulin action. Whereas mitochondria are important regulators of energy metabolism, the nutritional regulation of MAM in the liver and its role in the adaptation of mitochondria physiology to nutrient availability are unknown. In this study, we found that the fasted to postprandial transition reduced the number of endoplasmic reticulum-mitochondria contact points in mouse liver. Screening of potential hormonal/metabolic signals revealed glucose as the main nutritional regulator of hepatic MAM integrity both in vitro and in vivo Glucose reduced organelle interactions through the pentose phosphate-protein phosphatase 2A (PP-PP2A) pathway, induced mitochondria fission, and impaired respiration. Blocking MAM reduction counteracted glucose-induced mitochondrial alterations. Furthermore, disruption of MAM integrity mimicked effects of glucose on mitochondria dynamics and function. This glucose-sensing system is deficient in the liver of insulin-resistant ob/ob and cyclophilin D-KO mice, both characterized by chronic disruption of MAM integrity, mitochondrial fission, and altered mitochondrial respiration. These data indicate that MAM contribute to the hepatic glucose-sensing system, allowing regulation of mitochondria dynamics and function during nutritional transition. Chronic disruption of MAM may participate in hepatic mitochondrial dysfunction associated with insulin resistance. © The Author (2016). Published by Oxford University Press on behalf of Journal of Molecular Cell Biology, IBCB, SIBS, CAS. All rights reserved.