Pathways of hepatic glycogen formation in humans following ingestion of a glucose load in the fed state

International Nuclear Information System (INIS)

Magnusson, I.; Chandramouli, V.; Schumann, W.C.; Kumaran, K.; Wahren, J.; Landau, B.R.

1989-01-01

The relative contributions of the direct and the indirect pathways to hepatic glycogen formation following a glucose load given to humans four hours after a substantial breakfast have been examined. Glucose loads labeled with [6-( 14 )C]glucose were given to six healthy volunteers along with diflunisal (1 g) or acetaminophen (1.5 g), drugs excreted in urine as glucuronides. Distribution of 14 C in the glucose unit of the glucuronide was taken as a measure of the extent to which glucose was deposited directly in liver glycogen (ie, glucose----glucose-6-phosphate----glycogen) rather than indirectly (ie, glucose----C3-compound----glucose-6-phosphate----glycogen). The maximum contribution to glycogen formation by the direct pathway was estimated to be 77% +/- 4%, which is somewhat higher than previous estimates in humans fasted overnight (65% +/- 1%, P less than 0.05). Thus, the indirect pathway of liver glycogen formation following a glucose load is operative in both the overnight fasted and the fed state, although its contribution may be somewhat less in the fed state

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

Directory of Open Access Journals (Sweden)

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.

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

Directory of Open Access Journals (Sweden)

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.

Astroglial Pentose Phosphate Pathway Rates in Response to High-Glucose Environments

Directory of Open Access Journals (Sweden)

Shinichi Takahashi

2012-02-01

Full Text Available ROS (reactive oxygen species play an essential role in the pathophysiology of diabetes, stroke and neurodegenerative disorders. Hyperglycaemia associated with diabetes enhances ROS production and causes oxidative stress in vascular endothelial cells, but adverse effects of either acute or chronic high-glucose environments on brain parenchymal cells remain unclear. The PPP (pentose phosphate pathway and GSH participate in a major defence mechanism against ROS in brain, and we explored the role and regulation of the astroglial PPP in response to acute and chronic high-glucose environments. PPP activity was measured in cultured neurons and astroglia by determining the difference in rate of 14CO2 production from [1-14C]glucose and [6-14C]glucose. ROS production, mainly H2O2, and GSH were also assessed. Acutely elevated glucose concentrations in the culture media increased PPP activity and GSH level in astroglia, decreasing ROS production. Chronically elevated glucose environments also induced PPP activation. Immunohistochemical analyses revealed that chronic high-glucose environments induced ER (endoplasmic reticulum stress (presumably through increased hexosamine biosynthetic pathway flux. Nuclear translocation of Nrf2 (nuclear factor-erythroid 2 p45 subunit-related factor 2, which regulates G6PDH (glyceraldehyde-6-phosphate dehydrogenase by enhancing transcription, was also observed in association with BiP (immunoglobulin heavy-chain-binding protein expression. Acute and chronic high-glucose environments activated the PPP in astroglia, preventing ROS elevation. Therefore a rapid decrease in glucose level seems to enhance ROS toxicity, perhaps contributing to neural damage when insulin levels given to diabetic patients are not properly calibrated and plasma glucose levels are not adequately maintained. These findings may also explain the lack of evidence for clinical benefits from strict glycaemic control during the acute phase of stroke.

Astroglial pentose phosphate pathway rates in response to high-glucose environments

Science.gov (United States)

Takahashi, Shinichi; Izawa, Yoshikane; Suzuki, Norihiro

2012-01-01

ROS (reactive oxygen species) play an essential role in the pathophysiology of diabetes, stroke and neurodegenerative disorders. Hyperglycaemia associated with diabetes enhances ROS production and causes oxidative stress in vascular endothelial cells, but adverse effects of either acute or chronic high-glucose environments on brain parenchymal cells remain unclear. The PPP (pentose phosphate pathway) and GSH participate in a major defence mechanism against ROS in brain, and we explored the role and regulation of the astroglial PPP in response to acute and chronic high-glucose environments. PPP activity was measured in cultured neurons and astroglia by determining the difference in rate of 14CO2 production from [1-14C]glucose and [6-14C]glucose. ROS production, mainly H2O2, and GSH were also assessed. Acutely elevated glucose concentrations in the culture media increased PPP activity and GSH level in astroglia, decreasing ROS production. Chronically elevated glucose environments also induced PPP activation. Immunohistochemical analyses revealed that chronic high-glucose environments induced ER (endoplasmic reticulum) stress (presumably through increased hexosamine biosynthetic pathway flux). Nuclear translocation of Nrf2 (nuclear factor-erythroid 2 p45 subunit-related factor 2), which regulates G6PDH (glyceraldehyde-6-phosphate dehydrogenase) by enhancing transcription, was also observed in association with BiP (immunoglobulin heavy-chain-binding protein) expression. Acute and chronic high-glucose environments activated the PPP in astroglia, preventing ROS elevation. Therefore a rapid decrease in glucose level seems to enhance ROS toxicity, perhaps contributing to neural damage when insulin levels given to diabetic patients are not properly calibrated and plasma glucose levels are not adequately maintained. These findings may also explain the lack of evidence for clinical benefits from strict glycaemic control during the acute phase of stroke. PMID:22300409

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

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 ...

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

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 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

2017-01-20

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

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...

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).

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 ...

Peroxyl radical- and photo-oxidation of glucose 6- phosphate dehydrogenase generates cross-links and functional changes via oxidation of tyrosine and tryptophan residues

DEFF Research Database (Denmark)

Leinisch, Fabian; Mariotti, Michele; Rykær, Martin

2017-01-01

indicate that pathophysiological processes and multiple human diseases are associated with the accumulation of damaged proteins. In this study we investigated the mechanisms and consequences of exposure of the key metabolic enzyme glucose-6-phosphate dehydrogenase (G6PDH) to peroxyl radicals (ROO...

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

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

Covalently bound phosphate residues in bovine milk xanthine oxidase and in glucose oxidase from Aspergillus niger: A reevaluation

Energy Technology Data Exchange (ETDEWEB)

Johnson, J.L.; Rajagopalan, K.V. (Duke Univ. Medical Center, Durham, NC (USA)); London, R.E. (National Institute of Environmental Health Science, Research Triangle Park, NC (USA))

1989-09-01

The reported presence of covalently bound phosphate residues in flavoproteins has significant implications with regard to the catalytic mechanisms and structural stability of the specific enzymes themselves and in terms of general cellular metabolic regulation. These considerations have led to a reevaluation of the presence of covalently bound phosphorus in the flavoproteins xanthine oxidase and glucose oxidase. Milk xanthine oxidase purified by a procedure that includes anion-exchange chromatography is shown to contain three phosphate residues. All three are noncovalently associated with the protein, two with the FAD cofactor, and one with the molybdenum cofactor. Results of chemical analysis and {sup 31}P NMR spectroscopy indicate that enzyme purified by this method contains no phosphoserine residues. Xanthine oxidase preparations purified by chromatography on calcium phosphate gel in place of DEAE-Sephadex yielded higher phosphate-to-protein ratios, which could be reduced to the expected values by additional purification on a folate affinity column. Highly active, highly purified preparations of glucose oxidase are shown to contain only the two phosphate residues of the FAD cofactor. The covalently bound bridging phosphate reported by others may arise in aged or degraded preparations of the enzyme but appears not to be a constituent of functional glucose oxidase. These results suggest that the presence of covalent phosphate residues in other flavoproteins should be rigorously reevaluated as well.

Covalently bound phosphate residues in bovine milk xanthine oxidase and in glucose oxidase from Aspergillus niger: A reevaluation

International Nuclear Information System (INIS)

Johnson, J.L.; Rajagopalan, K.V.; London, R.E.

1989-01-01

The reported presence of covalently bound phosphate residues in flavoproteins has significant implications with regard to the catalytic mechanisms and structural stability of the specific enzymes themselves and in terms of general cellular metabolic regulation. These considerations have led to a reevaluation of the presence of covalently bound phosphorus in the flavoproteins xanthine oxidase and glucose oxidase. Milk xanthine oxidase purified by a procedure that includes anion-exchange chromatography is shown to contain three phosphate residues. All three are noncovalently associated with the protein, two with the FAD cofactor, and one with the molybdenum cofactor. Results of chemical analysis and 31 P NMR spectroscopy indicate that enzyme purified by this method contains no phosphoserine residues. Xanthine oxidase preparations purified by chromatography on calcium phosphate gel in place of DEAE-Sephadex yielded higher phosphate-to-protein ratios, which could be reduced to the expected values by additional purification on a folate affinity column. Highly active, highly purified preparations of glucose oxidase are shown to contain only the two phosphate residues of the FAD cofactor. The covalently bound bridging phosphate reported by others may arise in aged or degraded preparations of the enzyme but appears not to be a constituent of functional glucose oxidase. These results suggest that the presence of covalent phosphate residues in other flavoproteins should be rigorously reevaluated as well

Glucose and phosphate modulation of intracellular 45Ca incorporated into pancreatic islets during culture in the absence and presence of serum

International Nuclear Information System (INIS)

Bergsten, P.

1985-01-01

The effects of glucose and phosphate on the intracellular 45 Ca content were measured in β cell-rich pancreatic islets cultured in media containing or lacking serum. Irrespective of the glucose and serum concentrations there were no or very small increments of 45 Ca contents when phosphate was raised from 0.8 to 5.8 mM during culture for 1 day. However, after 7 days of culture in serum-free medium there was a massive accumulation of 45 Ca in the islets in response to the higher phosphate concentration. Glucose markedly reduced, and serum eliminated, the extensive accumulation probably due to increased cell viability. In the cells cultured in the presence of serum, raising the glucose concentration from 1.0 to 5.5 mM resulted in an increased incorporation of 45 Ca. This effect was particularly pronounced after culture for 7 days in 5.8 mM phosphate. A further increase of glucose to 20 mM reduced the 45 Ca content. The results are consistent with the concept that glucose both stimulates 45 Ca uptake into different β-cell pools and degranulates the cell with associated loss of intracellular calcium from the granular calcium pool. (author)

AMP-activated protein kinase-mediated glucose transport as a novel target of tributyltin in human embryonic carcinoma cells.

Science.gov (United States)

Yamada, Shigeru; Kotake, Yaichiro; Sekino, Yuko; Kanda, Yasunari

2013-05-01

Organotin compounds such as tributyltin (TBT) are known to cause various forms of cytotoxicity, including developmental toxicity and neurotoxicity. However, the molecular target of the toxicity induced by nanomolar levels of TBT has not been identified. In the present study, we found that exposure to 100 nM TBT induced growth arrest in human pluripotent embryonic carcinoma cell line NT2/D1. Since glucose provides metabolic energy, we focused on the glycolytic system. We found that exposure to TBT reduced the levels of both glucose-6-phosphate and fructose-6-phosphate. To investigate the effect of TBT exposure on glycolysis, we examined glucose transporter (GLUT) activity. TBT exposure inhibited glucose uptake via a decrease in the level of cell surface-bound GLUT1. Furthermore, we examined the effect of AMP-activated protein kinase (AMPK), which is known to regulate glucose transport by facilitating GLUT translocation. Treatment with the potent AMPK activator, AICAR, restored the TBT-induced reduction in cell surface-bound GLUT1 and glucose uptake. In conclusion, these results suggest that exposure to nanomolar levels of TBT causes growth arrest by targeting glycolytic systems in human embryonic carcinoma cells. Thus, understanding the energy metabolism may provide new insights into the mechanisms of metal-induced cytotoxicity.

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)

Glycolysis and the pentose phosphate pathway after human traumatic brain injury: microdialysis studies using 1,2-13C2 glucose

Science.gov (United States)

Jalloh, Ibrahim; Carpenter, Keri L H; Grice, Peter; Howe, Duncan J; Mason, Andrew; Gallagher, Clare N; Helmy, Adel; Murphy, Michael P; Menon, David K; Carpenter, T Adrian; Pickard, John D; Hutchinson, Peter J

2015-01-01

Increased ‘anaerobic' glucose metabolism is observed after traumatic brain injury (TBI) attributed to increased glycolysis. An alternative route is the pentose phosphate pathway (PPP), which generates putatively protective and reparative molecules. To compare pathways we employed microdialysis to perfuse 1,2-13C2 glucose into the brains of 15 TBI patients and macroscopically normal brain in six patients undergoing surgery for benign tumors, and to simultaneously collect products for nuclear magnetic resonance (NMR) analysis. 13C enrichment for glycolytic 2,3-13C2 lactate was the median 5.4% (interquartile range (IQR) 4.6–7.5%) in TBI brain and 4.2% (2.4–4.4%) in ‘normal' brain (Pbrain and 6.7% (6.3–8.9%) in ‘normal' brain. An inverse relationship was seen for PPP-glycolytic lactate ratio versus PbtO2 (r=−0.5, P=0.04) in TBI brain. Thus, glycolytic lactate production was significantly greater in TBI than ‘normal' brain. Several TBI patients exhibited PPP–lactate elevation above the ‘normal' range. There was proportionally greater PPP-derived lactate production with decreasing PbtO2. The study raises questions about the roles of the PPP and glycolysis after TBI, and whether they can be manipulated to achieve a better outcome. This study is the first direct comparison of glycolysis and PPP in human brain. PMID:25335801

Structure of the Bacillus anthracis dTDP- L -rhamnose-biosynthetic enzyme glucose-1-phosphate thymidylyltransferase (RfbA)

Energy Technology Data Exchange (ETDEWEB)

Baumgartner, Jackson; Lee, Jesi; Halavaty, Andrei S.; Minasov, George; Anderson, Wayne F.; Kuhn, Misty L. (NWU); (SFSU)

2017-10-30

L-Rhamnose is a ubiquitous bacterial cell-wall component. The biosynthetic pathway for its precursor dTDP-L-rhamnose is not present in humans, which makes the enzymes of the pathway potential drug targets. In this study, the three-dimensional structure of the first protein of this pathway, glucose-1-phosphate thymidylyltransferase (RfbA), fromBacillus anthraciswas determined. In other organisms this enzyme is referred to as RmlA. RfbA was co-crystallized with the products of the enzymatic reaction, dTDP-α-D-glucose and pyrophosphate, and its structure was determined at 2.3 Å resolution. This is the first reported thymidylyltransferase structure from a Gram-positive bacterium. RfbA shares overall structural characteristics with known RmlA homologs. However, RfbA exhibits a shorter sequence at its C-terminus, which results in the absence of three α-helices involved in allosteric site formation. Consequently, RfbA was observed to exhibit a quaternary structure that is unique among currently reported glucose-1-phosphate thymidylyltransferase bacterial homologs. These structural analyses suggest that RfbA may not be allosterically regulated in some organisms and is structurally distinct from other RmlA homologs.

The effects of chemical and radioactive properties of Tl-201 on human erythrocyte glucose 6-phosphate dehydrogenase activity

International Nuclear Information System (INIS)

Sahin, Ali; Senturk, Murat; Ciftci, Mehmet; Varoglu, Erhan; Kufrevioglu, Omer Irfan

2010-01-01

Aim: The inhibitory effects of thallium-201 ( 201 Tl) solution on human erythrocyte glucose 6-phosphate dehydrogenase (G6PD) activity were investigated. Methods: For this purpose, erythrocyte G6PD was initially purified 835-fold at a yield of 41.7% using 2',5'-Adenosine diphosphate sepharose 4B affinity gel chromatography. The purification was monitored by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, which showed a single band for the final enzyme preparation. The in vitro and in vivo effects of the 201 Tl solution including Tl + , Fe +3 and Cu +2 metals and the in vitro effects of the radiation effect of the 201 Tl solution and non-radioactive Tl + , Fe +3 and Cu +2 metals on human erythrocyte G6PD enzyme were studied. Enzyme activity was determined with the Beutler method at 340 nm using a spectrophotometer. All purification procedures were carried out at +4 deg. C. Results: 201 Tl solution and radiation exposure had inhibitory effects on the enzyme activity. IC 50 value of 201 Tl solution was 36.86 μl ([Tl + ]: 0.0036 μM, [Cu +2 ]: 0.0116 μM, [Fe +3 ]: 0.0132 μM), of human erythrocytes G6PD. Seven human patients were also used for in vivo studies of 201 Tl solution. Furthermore, non-radioactive Tl + , Fe +3 and Cu +2 were found not to have influenced the enzyme in vitro. Conclusion: Human erythrocyte G6PD activity was inhibited by exposure for up to 10 minutes to 0.057 mCi/kg 201 Tl solution. It was detected in in vitro and in vivo studies that the human erythrocyte G6PD enzyme is inhibited due to the radiation effect of 201 Tl solution.

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.

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

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

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

Glucose metabolism via the pentose phosphate pathway, glycolysis and Krebs cycle in an orthotopic mouse model of human brain tumors.

Science.gov (United States)

Marin-Valencia, Isaac; Cho, Steve K; Rakheja, Dinesh; Hatanpaa, Kimmo J; Kapur, Payal; Mashimo, Tomoyuki; Jindal, Ashish; Vemireddy, Vamsidhara; Good, Levi B; Raisanen, Jack; Sun, Xiankai; Mickey, Bruce; Choi, Changho; Takahashi, Masaya; Togao, Osamu; Pascual, Juan M; Deberardinis, Ralph J; Maher, Elizabeth A; Malloy, Craig R; Bachoo, Robert M

2012-10-01

It has been hypothesized that increased flux through the pentose phosphate pathway (PPP) is required to support the metabolic demands of rapid malignant cell growth. Using orthotopic mouse models of human glioblastoma (GBM) and renal cell carcinoma metastatic to brain, we estimated the activity of the PPP relative to glycolysis by infusing [1,2-(13) C(2) ]glucose. The [3-(13) C]lactate/[2,3-(13) C(2) ]lactate ratio was similar for both the GBM and brain metastasis and their respective surrounding brains (GBM, 0.197 ± 0.011 and 0.195 ± 0.033, respectively (p = 1); metastasis: 0.126 and 0.119 ± 0.033, respectively). This suggests that the rate of glycolysis is significantly greater than the PPP flux in these tumors, and that the PPP flux into the lactate pool is similar in both tumors. Remarkably, (13) C-(13) C coupling was observed in molecules derived from Krebs cycle intermediates in both tumor types, denoting glucose oxidation. In the renal cell carcinoma, in contrast with GBM, (13) C multiplets of γ-aminobutyric acid (GABA) differed from its precursor glutamate, suggesting that GABA did not derive from a common glutamate precursor pool. In addition, the orthotopic renal tumor, the patient's primary renal mass and brain metastasis were all strongly immunopositive for the 67-kDa isoform of glutamate decarboxylase, as were 84% of tumors on a renal cell carcinoma tissue microarray of the same histology, suggesting that GABA synthesis is cell autonomous in at least a subset of renal cell carcinomas. Taken together, these data demonstrate that (13) C-labeled glucose can be used in orthotopic mouse models to study tumor metabolism in vivo and to ascertain new metabolic targets for cancer diagnosis and therapy. Copyright © 2012 John Wiley & Sons, Ltd.

Boosting the pentose phosphate pathway restores cardiac progenitor cell availability in diabetes.

Science.gov (United States)

Katare, Rajesh; Oikawa, Atsuhiko; Cesselli, Daniela; Beltrami, Antonio P; Avolio, Elisa; Muthukrishnan, Deepti; Munasinghe, Pujika Emani; Angelini, Gianni; Emanueli, Costanza; Madeddu, Paolo

2013-01-01

Diabetes impinges upon mechanisms of cardiovascular repair. However, the biochemical adaptation of cardiac stem cells to sustained hyperglycaemia remains largely unknown. Here, we investigate the molecular targets of high glucose-induced damage in cardiac progenitor cells (CPCs) from murine and human hearts and attempt safeguarding CPC viability and function through reactivation of the pentose phosphate pathway. Type-1 diabetes was induced by streptozotocin. CPC abundance was determined by flow cytometry. Proliferating CPCs were identified in situ by immunostaining for the proliferation marker Ki67. Diabetic hearts showed marked reduction in CPC abundance and proliferation when compared with controls. Moreover, Sca-1(pos) CPCs isolated from hearts of diabetic mice displayed reduced activity of key enzymes of the pentose phosphate pathway, glucose-6-phosphate dehydrogenase (G6PD), and transketolase, increased levels of superoxide and advanced glucose end-products (AGE), and inhibition of the Akt/Pim-1/Bcl-2 signalling pathway. Similarly, culture of murine CPCs or human CD105(pos) progenitor cells in high glucose inhibits the pentose phosphate and pro-survival signalling pathways, leading to the activation of apoptosis. In vivo and in vitro supplementation with benfotiamine reactivates the pentose phosphate pathway and rescues CPC availability and function. This benefit is abrogated by either G6PD silencing by small interfering RNA (siRNA) or Akt inhibition by dominant-negative Akt. We provide new evidence of the negative impact of diabetes and high glucose on mechanisms controlling CPC redox state and survival. Boosting the pentose phosphate pathway might represent a novel mechanistic target for protection of CPC integrity.

Functional and Biochemical Characterization of Three Recombinant Human Glucose-6-Phosphate Dehydrogenase Mutants: Zacatecas, Vanua-Lava and Viangchan

Science.gov (United States)

Gómez-Manzo, Saúl; Marcial-Quino, Jaime; Vanoye-Carlo, America; Serrano-Posada, Hugo; González-Valdez, Abigail; Martínez-Rosas, Víctor; Hernández-Ochoa, Beatriz; Sierra-Palacios, Edgar; Castillo-Rodríguez, Rosa Angélica; Cuevas-Cruz, Miguel; Rodríguez-Bustamante, Eduardo; Arreguin-Espinosa, Roberto

2016-01-01

Glucose-6-phosphate dehydrogenase (G6PD) deficiency in humans causes severe disease, varying from mostly asymptomatic individuals to patients showing neonatal jaundice, acute hemolysis episodes or chronic nonspherocytic hemolytic anemia. In order to understand the effect of the mutations in G6PD gene function and its relation with G6PD deficiency severity, we report the construction, cloning and expression as well as the detailed kinetic and stability characterization of three purified clinical variants of G6PD that present in the Mexican population: G6PD Zacatecas (Class I), Vanua-Lava (Class II) and Viangchan (Class II). For all the G6PD mutants, we obtained low purification yield and altered kinetic parameters compared with Wild Type (WT). Our results show that the mutations, regardless of the distance from the active site where they are located, affect the catalytic properties and structural parameters and that these changes could be associated with the clinical presentation of the deficiency. Specifically, the structural characterization of the G6PD Zacatecas mutant suggests that the R257L mutation have a strong effect on the global stability of G6PD favoring an unstable active site. Using computational analysis, we offer a molecular explanation of the effects of these mutations on the active site. PMID:27213370

Phosphate-a poison for humans?

Science.gov (United States)

Komaba, Hirotaka; Fukagawa, Masafumi

2016-10-01

Maintenance of phosphate balance is essential for life, and mammals have developed a sophisticated system to regulate phosphate homeostasis over the course of evolution. However, due to the dependence of phosphate elimination on the kidney, humans with decreased kidney function are likely to be in a positive phosphate balance. Phosphate excess has been well recognized as a critical factor in the pathogenesis of mineral and bone disorders associated with chronic kidney disease, but recent investigations have also uncovered toxic effects of phosphate on the cardiovascular system and the aging process. Compelling evidence also suggests that increased fibroblastic growth factor 23 and parathyroid hormone levels in response to a positive phosphate balance contribute to adverse clinical outcomes. These insights support the current practice of managing serum phosphate in patients with advanced chronic kidney disease, although definitive evidence of these effects is lacking. Given the potential toxicity of excess phosphate, the general population may also be viewed as a target for phosphate management. However, the widespread implementation of dietary phosphate intervention in the general population may not be warranted due to the limited impact of increased phosphate intake on mineral metabolism and clinical outcomes. Nonetheless, the increasing incidence of kidney disease or injury in our aging society emphasizes the potential importance of this issue. Further work is needed to more completely characterize phosphate toxicity and to establish the optimal therapeutic strategy for managing phosphate in patients with chronic kidney disease and in the general population. Copyright © 2016 International Society of Nephrology. Published by Elsevier Inc. All rights reserved.

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

Discovery of a novel glucose metabolism in cancer: The role of endoplasmic reticulum beyond glycolysis and pentose phosphate shunt

Science.gov (United States)

Marini, Cecilia; Ravera, Silvia; Buschiazzo, Ambra; Bianchi, Giovanna; Orengo, Anna Maria; Bruno, Silvia; Bottoni, Gianluca; Emionite, Laura; Pastorino, Fabio; Monteverde, Elena; Garaboldi, Lucia; Martella, Roberto; Salani, Barbara; Maggi, Davide; Ponzoni, Mirco; Fais, Franco; Raffaghello, Lizzia; Sambuceti, Gianmario

2016-01-01

Cancer metabolism is characterized by an accelerated glycolytic rate facing reduced activity of oxidative phosphorylation. This “Warburg effect” represents a standard to diagnose and monitor tumor aggressiveness with 18F-fluorodeoxyglucose whose uptake is currently regarded as an accurate index of total glucose consumption. Studying cancer metabolic response to respiratory chain inhibition by metformin, we repeatedly observed a reduction of tracer uptake facing a marked increase in glucose consumption. This puzzling discordance brought us to discover that 18F-fluorodeoxyglucose preferentially accumulates within endoplasmic reticulum by exploiting the catalytic function of hexose-6-phosphate-dehydrogenase. Silencing enzyme expression and activity decreased both tracer uptake and glucose consumption, caused severe energy depletion and decreased NADPH content without altering mitochondrial function. These data document the existence of an unknown glucose metabolism triggered by hexose-6-phosphate-dehydrogenase within endoplasmic reticulum of cancer cells. Besides its basic relevance, this finding can improve clinical cancer diagnosis and might represent potential target for therapy. PMID:27121192

What is the role of the second "structural" NADP+-binding site in human glucose 6-phosphate dehydrogenase?

Science.gov (United States)

Wang, Xiao-Tao; Chan, Ting Fai; Lam, Veronica M S; Engel, Paul C

2008-08-01

Human glucose 6-phosphate dehydrogenase, purified after overexpression in E. coli, was shown to contain one molecule/subunit of acid-extractable "structural" NADP+ and no NADPH. This tightly bound NADP+ was reduced by G6P, presumably following migration to the catalytic site. Gel-filtration yielded apoenzyme, devoid of bound NADP+ but, surprisingly, still fully active. Mr of the main component of "stripped" enzyme by gel filtration was approximately 100,000, suggesting a dimeric apoenzyme (subunit Mr = 59,000). Holoenzyme also contained tetramer molecules and, at high protein concentration, a dynamic equilibrium gave an apparent intermediate Mr of 150 kDa. Fluorescence titration of the stripped enzyme gave the K d for structural NADP+ as 37 nM, 200-fold lower than for "catalytic" NADP+. Structural NADP+ quenches 91% of protein fluorescence. At 37 degrees C, stripped enzyme, much less stable than holoenzyme, inactivated irreversibly within 2 d. Inactivation at 4 degrees C was partially reversed at room temperature, especially with added NADP+. Apoenzyme was immediately active, without any visible lag, in rapid-reaction studies. Human G6PD thus forms active dimer without structural NADP+. Apparently, the true role of the second, tightly bound NADP+ is to secure long-term stability. This fits the clinical pattern, G6PD deficiency affecting the long-lived non-nucleate erythrocyte. The Kd values for two class I mutants, G488S and G488V, were 273 nM and 480 nM, respectively (seven- and 13-fold elevated), matching the structural prediction of weakened structural NADP+ binding, which would explain decreased stability and consequent disease. Preparation of native apoenzyme and measurement of Kd constant for structural NADP+ will now allow quantitative assessment of this defect in clinical G6PD mutations.

IGF-II receptors and IGF-II-stimulated glucose transport in human fat cells

International Nuclear Information System (INIS)

Sinha, M.K.; Buchanan, C.; Raineri-Maldonado, C.; Khazanie, P.; Atkinson, S.; DiMarchi, R.; Caro, J.F.

1990-01-01

Insulin-like growth factor II (IGF-II) receptors have been described in rat but not in human adipocytes. In both species, IGF-II has been reported to stimulate glucose transport by interacting with the insulin receptor. In this study, we have unequivocally demonstrated the presence of IGF-II receptors in human adipocytes. 125I-labeled IGF-II specifically binds to intact adipocytes, membranes, and lectin-purified detergent solubilized extracts. Through the use of 0.5 mM disuccinimidyl suberate, 125I-IGF-II is cross-linked to a 260-kDa protein that is identified as the IGF-II receptor by displacement experiments with unlabeled IGF-II, IGF-I, and insulin and either by immunoprecipitation or by Western blot analysis with mannose 6-phosphate receptor antibodies. The concentrations of IGF-II required for half-maximal and maximal stimulation of glucose transport in human adipocytes are 35 and 100 times more than that of insulin. The possibility of IGF-II stimulating glucose transport by interacting predominantly with the insulin receptor is suggested by the following: (1) the concentration of IGF-II that inhibits half of insulin binding is only 20 times more than that of insulin; (2) the lack of an additive effect of IGF-II and insulin for maximal stimulation of glucose transport; (3) the ability of monoclonal insulin receptor antibodies to decrease glucose transport stimulated by submaximal concentrations of both IGF-II and insulin; and (4) the ability of IGF-II to stimulate insulin receptor autophosphorylation albeit at a reduced potency when compared with insulin

Increasing synthetic serum substitute (SSS) concentrations in P1 glucose/phosphate-free medium improves implantation rate: a comparative study.

Science.gov (United States)

Ben-Yosef, D; Yovel, I; Schwartz, T; Azem, F; Lessing, J B; Amit, A

2001-11-01

To assess the comparative efficacy of IVF medium (MediCult, with 5.2 mM glucose) and a glucose/phosphate-free medium, P1 (Irvine Scientific), and to investigate the influence of increasing the serum supplementation (synthetic serum substitute; SSS; Irvine Scientific) to P1 on embryo development and implantation. Patients were randomly assigned to IVF medium (Group 1, cycles n = 172) or P1 supplemented with 10% SSS (Group 2, cycles n = 229) according to the medium scheduled for use on the day of oocyte retrieval. Another 555 IVF consequent cycles (Group 3) were performed using increased SSS concentrations (20%) in P1 medium. In this large series of IVF cycles, we herein demonstrate that significantly higher pregnancy and implantation rates were found when embryos were cultured in glucose/phosphate-free medium P1 supplemented with 20% SSS compared to supplementation with the lower SSS concentration and with IVF medium.

Cannabidiol attenuates OGD/R-induced damage by enhancing mitochondrial bioenergetics and modulating glucose metabolism via pentose-phosphate pathway in hippocampal neurons

Directory of Open Access Journals (Sweden)

Shanshan Sun

2017-04-01

Full Text Available Deficient bioenergetics and diminished redox conservation have been implicated in the development of cerebral ischemia/reperfusion injury. In this study, the mechanisms underlying the neuroprotective effects of cannabidiol (CBD, a nonpsychotropic compound derived from Cannabis sativa with FDA-approved antiepilepsy properties, were studied in vitro using an oxygen–glucose-deprivation/reperfusion (OGD/R model in a mouse hippocampal neuronal cell line. CBD supplementation during reperfusion rescued OGD/R-induced cell death, attenuated intracellular ROS generation and lipid peroxidation, and simultaneously reversed the abnormal changes in antioxidant biomarkers. Using the Seahorse XFe24 Extracellular Flux Analyzer, we found that CBD significantly improved basal respiration, ATP-linked oxygen consumption rate, and the spare respiratory capacity, and augmented glucose consumption in OGD/R-injured neurons. The activation of glucose 6-phosphate dehydrogenase and the preservation of the NADPH/NADP+ ratio implies that the pentose-phosphate pathway is stimulated by CBD, thus protecting hippocampal neurons from OGD/R injury. This study is the first to document the neuroprotective effects of CBD against OGD/R insult, which depend in part on attenuating oxidative stress, enhancing mitochondrial bioenergetics, and modulating glucose metabolism via the pentose-phosphate pathway, thus preserving both energy and the redox balance.

Cannabidiol attenuates OGD/R-induced damage by enhancing mitochondrial bioenergetics and modulating glucose metabolism via pentose-phosphate pathway in hippocampal neurons.

Science.gov (United States)

Sun, Shanshan; Hu, Fangyuan; Wu, Jihong; Zhang, Shenghai

2017-04-01

Deficient bioenergetics and diminished redox conservation have been implicated in the development of cerebral ischemia/reperfusion injury. In this study, the mechanisms underlying the neuroprotective effects of cannabidiol (CBD), a nonpsychotropic compound derived from Cannabis sativa with FDA-approved antiepilepsy properties, were studied in vitro using an oxygen-glucose-deprivation/reperfusion (OGD/R) model in a mouse hippocampal neuronal cell line. CBD supplementation during reperfusion rescued OGD/R-induced cell death, attenuated intracellular ROS generation and lipid peroxidation, and simultaneously reversed the abnormal changes in antioxidant biomarkers. Using the Seahorse XF e 24 Extracellular Flux Analyzer, we found that CBD significantly improved basal respiration, ATP-linked oxygen consumption rate, and the spare respiratory capacity, and augmented glucose consumption in OGD/R-injured neurons. The activation of glucose 6-phosphate dehydrogenase and the preservation of the NADPH/NADP + ratio implies that the pentose-phosphate pathway is stimulated by CBD, thus protecting hippocampal neurons from OGD/R injury. This study is the first to document the neuroprotective effects of CBD against OGD/R insult, which depend in part on attenuating oxidative stress, enhancing mitochondrial bioenergetics, and modulating glucose metabolism via the pentose-phosphate pathway, thus preserving both energy and the redox balance. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

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.

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.

High glucose impairs superoxide production from isolated blood neutrophils

DEFF Research Database (Denmark)

Perner, A; Nielsen, S E; Rask-Madsen, J

2003-01-01

Superoxide (O(2)(-)), a key antimicrobial agent in phagocytes, is produced by the activity of NADPH oxidase. High glucose concentrations may, however, impair the production of O(2)(-) through inhibition of glucose-6-phosphate dehydrogenase (G6PD), which catalyzes the formation of NADPH. This study...... measured the acute effects of high glucose or the G6PD inhibitor dehydroepiandrosterone (DHEA) on the production of O(2)(-) from isolated human neutrophils....

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

(13)C metabolic flux analysis in neurons utilizing a model that accounts for hexose phosphate recycling within the pentose phosphate pathway.

Science.gov (United States)

Gebril, Hoda M; Avula, Bharathi; Wang, Yan-Hong; Khan, Ikhlas A; Jekabsons, Mika B

2016-02-01

Glycolysis, mitochondrial substrate oxidation, and the pentose phosphate pathway (PPP) are critical for neuronal bioenergetics and oxidation-reduction homeostasis, but quantitating their fluxes remains challenging, especially when processes such as hexose phosphate (i.e., glucose/fructose-6-phosphate) recycling in the PPP are considered. A hexose phosphate recycling model was developed which exploited the rates of glucose consumption, lactate production, and mitochondrial respiration to infer fluxes through the major glucose consuming pathways of adherent cerebellar granule neurons by replicating [(13)C]lactate labeling from metabolism of [1,2-(13)C2]glucose. Flux calculations were predicated on a steady-state system with reactions having known stoichiometries and carbon atom transitions. Non-oxidative PPP activity and consequent hexose phosphate recycling, as well as pyruvate production by cytoplasmic malic enzyme, were optimized by the model and found to account for 28 ± 2% and 7.7 ± 0.2% of hexose phosphate and pyruvate labeling, respectively. From the resulting fluxes, 52 ± 6% of glucose was metabolized by glycolysis, compared to 19 ± 2% by the combined oxidative/non-oxidative pentose cycle that allows for hexose phosphate recycling, and 29 ± 8% by the combined oxidative PPP/de novo nucleotide synthesis reactions. By extension, 62 ± 6% of glucose was converted to pyruvate, the metabolism of which resulted in 16 ± 1% of glucose oxidized by mitochondria and 46 ± 6% exported as lactate. The results indicate a surprisingly high proportion of glucose utilized by the pentose cycle and the reactions synthesizing nucleotides, and exported as lactate. While the in vitro conditions to which the neurons were exposed (high glucose, no lactate or other exogenous substrates) limit extrapolating these results to the in vivo state, the approach provides a means of assessing a number of metabolic fluxes within the context of hexose phosphate recycling in the PPP from a

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...

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

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...

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

Directory of Open Access Journals (Sweden)

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.

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.)

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

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

Synthesis and modifications of heterocyclic derivatives of D-arabinose: potential inhibitors of glucose-6-phosphate isomerase and glucosamine-6-phosphate synthase

International Nuclear Information System (INIS)

Viana, Renato Marcio Ribeiro; Prado, Maria Auxiliadora Fontes; Alves, Ricardo Jose

2008-01-01

The synthesis of -5-(D-arabino-1,2,3,4-tetrahydroxybutyl)tetrazole and -2-(d-arabino-1,2,3,4-tetra-acetoxybutyl)-5-methyl-1,3,4-oxadiazole from d-arabinose is described. Attempts at removing the protecting groups of the oxadiazole derivative were unsuccessful, leading to products resulting from the opening of the oxadiazole ring. The unprotected tetrazole derivative was selectively phosphorylated at the primary hydroxyl group with diethyl phosphoryl chloride. The resulting 5-[d-arabino-4-(diethylphosphoryloxy)-1,2,3-trihydroxybutyl]tetrazole is a protected form of a potential inhibitor of the enzymes glucose-6-phosphate isomerase and glucosamine synthase. (author)

Amperometric, screen-printed, glucose biosensor for analysis of human plasma samples using a biocomposite water-based carbon ink incorporating glucose oxidase.

Science.gov (United States)

Crouch, Eric; Cowell, David C; Hoskins, Stephen; Pittson, Robin W; Hart, John P

2005-12-01

This paper describes the optimisation of a screen-printing water-based carbon ink containing cobalt phthalocyanine (CoPC) and glucose oxidase (GOD) for the fabrication of a glucose biosensor. To optimise the performance of the biosensor, the loadings of the electrocatalyst (CoPC) and enzyme (GOD) were varied. It was found that the maximum linear range was achieved with a CoPC loading of 20% (m/m, relative to the mass of carbon) and a GOD loading of 628 U per gram of carbon. In our studies we chose to employ chronoamperometry, as this technique is commonly used for commercial devices. The optimum operating applied potential was found to be +0.5 V, following an incubation period of 60 s. The optimum supporting electrolyte was found to be 0.05 M phosphate buffer at pH 8.0, which resulted in a linear range of 0.2-5 mM, the former represents the detection limit. The sensitivity was 1.12 microA mM(-1). The effect of temperature was also investigated, and it was found that 40 degrees C gave optimal performance. The resulting amperometric biosensors were evaluated by measuring the glucose concentrations for 10 different human plasma samples containing endogenous glucose and also added glucose. The same samples were analysed by a standard spectrophotometric method, and the results obtained by the two different methods were compared. A good correlation coefficient (R(2) = 0.95) and slope (0.98) were calculated from the experimental data, indicating that the new devices hold promise for biomedical studies.

TXNIP regulates peripheral glucose metabolism in humans

DEFF Research Database (Denmark)

Parikh, Hemang; Carlsson, Emma; Chutkow, William A

2007-01-01

combined human insulin/glucose clamp physiological studies with genome-wide expression profiling to identify thioredoxin interacting protein (TXNIP) as a gene whose expression is powerfully suppressed by insulin yet stimulated by glucose. In healthy individuals, its expression was inversely correlated...... expression is consistently elevated in the muscle of prediabetics and diabetics, although in a panel of 4,450 Scandinavian individuals, we found no evidence for association between common genetic variation in the TXNIP gene and T2DM. CONCLUSIONS: TXNIP regulates both insulin-dependent and insulin......-independent pathways of glucose uptake in human skeletal muscle. Combined with recent studies that have implicated TXNIP in pancreatic beta-cell glucose toxicity, our data suggest that TXNIP might play a key role in defective glucose homeostasis preceding overt T2DM....

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)

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...

Vanadate influence on metabolism of sugar phosphates in fungus Phycomyces blakesleeanus.

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Milan Žižić

Full Text Available The biological and chemical basis of vanadium action in fungi is relatively poorly understood. In the present study, we investigate the influence of vanadate (V5+ on phosphate metabolism of Phycomyces blakesleeanus. Addition of V5+ caused increase of sugar phosphates signal intensities in 31P NMR spectra in vivo. HPLC analysis of mycelial phosphate extracts demonstrated increased concentrations of glucose 6 phosphate, fructose 6 phosphate, fructose 1, 6 phosphate and glucose 1 phosphate after V5+ treatment. Influence of V5+ on the levels of fructose 2, 6 phosphate, glucosamine 6 phosphate and glucose 1, 6 phosphate (HPLC, and polyphosphates, UDPG and ATP (31P NMR was also established. Increase of sugar phosphates content was not observed after addition of vanadyl (V4+, indicating that only vanadate influences its metabolism. Obtained results from in vivo experiments indicate catalytic/inhibitory vanadate action on enzymes involved in reactions of glycolysis and glycogenesis i.e., phosphoglucomutase, phosphofructokinase and glycogen phosphorylase in filamentous fungi.

Data mining and pathway analysis of glucose-6-phosphate dehydrogenase with natural language processing

Science.gov (United States)

Chen, Long; Zhang, Chunhua; Wang, Yanling; Li, Yuqian; Han, Qiaoqiao; Yang, Huixin; Zhu, Yuechun

2017-01-01

Human glucose-6-phosphate dehydrogenase (G6PD) is a crucial enzyme in the pentose phosphate pathway, and serves an important role in biosynthesis and the redox balance. G6PD deficiency is a major cause of neonatal jaundice and acute hemolyticanemia, and recently, G6PD has been associated with diseases including inflammation and cancer. The aim of the present study was to conduct a search of the National Center for Biotechnology Information PubMed library for articles discussing G6PD. Genes that were identified to be associated with G6PD were recorded, and the frequency at which each gene appeared was calculated. Gene ontology (GO), pathway and network analyses were then performed. A total of 98 G6PD-associated genes and 33 microRNAs (miRNAs) that potentially regulate G6PD were identified. The 98 G6PD-associated genes were then sub-classified into three functional groups by GO analysis, followed by analysis of function, pathway, network, and disease association. Out of the 47 signaling pathways identified, seven were significantly correlated with G6PD-associated genes. At least two out of four independent programs identified the 33 miRNAs that were predicted to target G6PD. miR-1207-5P, miR-1 and miR-125a-5p were predicted by all four software programs to target G6PD. The results of the present study revealed that dysregulation of G6PD was associated with cancer, autoimmune diseases, and oxidative stress-induced disorders. These results revealed the potential roles of G6PD-regulated signaling and metabolic pathways in the etiology of these diseases. PMID:28627690

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.

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

Modelling glucose and water dynamics in human skin

NARCIS (Netherlands)

Groenendaal, W.; Schmidt, K.H.; Basum, von G.; Riel, van N.A.W.; Hilbers, P.A.J.

2008-01-01

Background: Glucose is heterogeneously distributed in the different physiological compartments in the human skin. Therefore, for the development of a noninvasive measurement method, both a good quantification of the different compartments of human skin and an understanding of glucose transport

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...

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

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.

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

Directory of Open Access Journals (Sweden)

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.

Glucose production during exercise in humans

DEFF Research Database (Denmark)

Bergeron, R; Kjaer, M; Simonsen, L

1999-01-01

at 50.4 +/- 1.5(SE)% maximal O(2) consumption, followed by 30 min at 69.0 +/- 2.2% maximal O(2) consumption. The splanchnic blood flow was estimated by continuous infusion of indocyanine green, and net splanchnic glucose output was calculated as the product of splanchnic blood flow and a-hv blood...... glucose concentration differences. Glucose appearance rate was determined by a primed, continuous infusion of [3-(3)H]glucose and was calculated by using formulas for a modified single compartment in non-steady state. Glucose production was similar whether determined by the a-hv balance technique......The present study compared the arteriohepatic venous (a-hv) balance technique and the tracer-dilution method for estimation of hepatic glucose production during both moderate and heavy exercise in humans. Eight healthy young men (aged 25 yr; range, 23-30 yr) performed semisupine cycling for 40 min...

Complex formation between uranium(VI) and α-D-glucose 1-phosphate

International Nuclear Information System (INIS)

Koban, A.; Geipel, G.; Bernhard, G.

2003-01-01

The complex formation of uranium(VI) with α-D-glucose 1-phosphate (C 6 H 11 O 6 PO 3 2- , G1P) was determined by time-resolved laser-induced fluorescence spectroscopy (TRLFS) at pH 4 and potentiometric titration in the pH range from 3 to 10. Both measurements show the formation of a 1 : 1 complex at lower pH values. The formation constant of UO 2 (C 6 H 11 O 6 PO 3 ) was calculated from TRLFS measurements to be log β 11 = 5.72±0.12, and from potentiometric titration log β 11 = 5.40±0.25, respectively. It was found by potentiometric titration that at higher pH values the complexation changes to a 1 : 2 complex. The stability constant for this complex was calculated to be log β 12 = 8.96±0.18. (orig.)

Quantitative aspects of the cytochemical demonstration of glucose-6-phosphate dehydrogenase with tetranitro BT studied in a model system of polyacrylamide films

NARCIS (Netherlands)

van Noorden, C. J.; Tas, J.

1980-01-01

The cytochemical determination of the activity of glucose-6-phosphate dehydrogenase (G6PDH) with tetranitro blue tetrazolium (TNBT) was studied with model films of polyacrylamide gel incorporating purified enzyme. This model system enabled a quantitative study to be made of different parameters

Isotope inequilibrium of glucose metabolites in intact cells and particlefree supernatants of Ehrlich ascites tumor

International Nuclear Information System (INIS)

Daehnfeldt, J.L.; Winge, P.

1975-01-01

With an enzyme degradative technique, isotope inequilibrium of glucose metabolites was demonstrated in intact cells and particle-free supernatants of Ehrlich ascites tumor using I- 14 C-glucose as tracer. Inequilibrium was found between glucose and glucose-6-phosphate, glucose and fructose-6-phosphate, glucose and 6-phosphogluconate, while glucose-6-phosphate and fructose-6-phosphate were found to be in near equilibrium within the incubation time investigated. Glucose and lactate were found to be in near equilibrium after 8 min in intact cells. Calculations based on the equilibrium levels found, showed that these inequilibria could not be explained by the effects of the pentose cycle. (U.S.)

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)

The dipeptidyl peptidase-4 (DPP-4) inhibitor teneligliptin functions as antioxidant on human endothelial cells exposed to chronic hyperglycemia and metabolic high-glucose memory.

Science.gov (United States)

Pujadas, Gemma; De Nigris, Valeria; Prattichizzo, Francesco; La Sala, Lucia; Testa, Roberto; Ceriello, Antonio

2017-06-01

Dipeptidyl peptidase-4 inhibitors are widely used in type 2 diabetes. Endothelium plays a crucial role maintaining vascular integrity and function. Chronic exposure to high glucose drives to endothelial dysfunction generating oxidative stress. Teneligliptin is a novel dipeptidyl peptidase-4 inhibitor with antioxidant properties. This study is aimed to verify a potential protective action of teneligliptin in endothelial cells exposed to high glucose. Human umbilical vein endothelial cells were cultured under normal (5 mmol/L) or high glucose (25 mmol/L) during 21 days, or at high glucose during 14 days followed by 7 days at normal glucose, to reproduce the high-metabolic memory state. During this period, different concentrations of teneligliptin (0.1, 1.0 and 3.0 µmol/L) or sitagliptin (0.5 µmol/L) were added to cells. Ribonucleic acid and protein expression were assessed for antioxidant response, proliferation, apoptosis and endoplasmic reticulum stress markers. Teneligliptin promotes the antioxidant response in human umbilical vein endothelial cells, reducing ROS levels and inducing Nrf2-target genes messenger ribonucleic acid expression. Teneligliptin, but not sitagliptin, reduces the expression of the nicotine amide adenine dinucleotide phosphate oxidase regulatory subunit P22 -phox , however, both blunt the high glucose-induced increase of TXNIP. Teneligliptin improves proliferation rates in human umbilical vein endothelial cells exposed to high glucose, regulating the expression of cell-cycle inhibitors markers (P53, P21 and P27), and reducing proapoptotic genes (BAX and CASP3), while promotes BCL2 expression. Teneligliptin ameliorates high glucose-induced endoplasmic reticulum stress reducing the expression of several markers (BIP, PERK, ATF4, CHOP, IRE1a and ATF6). Teneligliptin has antioxidant properties, ameliorates oxidative stress and apoptotic phenotype and it can overcome the metabolic memory effect, induced by chronic exposure to high

Lithium iron phosphate with high-rate capability synthesized through hydrothermal reaction in glucose solution

Energy Technology Data Exchange (ETDEWEB)

Liang, Guangchuan; Wang, Li; Ou, Xiuqin; Zhao, Xia; Xu, Shengzhao [Institute of Power Source and Ecomaterials Science, Box 1055, Hebei University of Technology, 300130 Tianjin (China)

2008-10-01

Carbon-coated lithium iron phosphate (LiFePO{sub 4}/C) was hydrothermally synthesized from commercial LiOH, FeSO{sub 4} and H{sub 3}PO{sub 4} as raw materials and glucose as carbon precursor in aqueous solution at 180 C for 6 h followed by being fired at 750 C for 6 h. The samples were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and constant current charge-discharge cycling test. The results show that the synthesized powders are in situ coated with carbon precursor produced from glucose. At ambient temperature (25{+-}2 C), the specific discharge capacities are 154 mAh g{sup -1} at 0.2C and 136 mAh g{sup -1} at 5 C rate, and the cycling capacity retention rate reaches 98% over 90 cycles. The excellent electrochemical performance can be correlated with the in situ formation of carbon precursor/carbon, thus leading to the even distribution of carbon and the enhancement of conductibility of individual grains. (author)

Zinc dosing and glucose tolerance in humans

International Nuclear Information System (INIS)

Greenley, S.; Taylor, M.

1986-01-01

Animal data suggest the existence of a physiologic relationship between glucoregulatory hormones and zinc metabolism. In order to investigate this proposed relationship in humans, they examined the effect of moderately elevated plasma zinc levels on blood glucose clearance. Eight women (24-37 yrs) served as subjects for the study. Fasted volunteers were tested under two experimental conditions (a) ingestion of 50 g D-glucose (b) ingestion of 25 mg zinc followed 60 min later by ingestion of 50 g D-glucose. Five ml venous blood was drawn into trace-metal-free, fluoride-containing vacutainer tubes prior to and 15, 30, 45, 60, 90, and 120 min after glucose ingestion. Plasma was analyzed for glucose and zinc; glycemic responses were quantified by computing areas under the curves and times to peak concentration. Their human data indicate varied glycemic responses to the acute elevation of plasma zinc: 4 subjects showed little apparent effect; 3 subjects marginally increased either the area under the curve or time to peak and 1 subject (classified as suspect diabetic in the non-zinc condition) showed marked improvement in glycemic response following zinc ingestion. Their preliminary results suggest that blood glucose clearance may be affected in some individuals by the acute elevation of plasma zinc

Glucose enhancement of human memory: a comprehensive research review of the glucose memory facilitation effect.

Science.gov (United States)

Smith, Michael A; Riby, Leigh M; Eekelen, J Anke M van; Foster, Jonathan K

2011-01-01

The brain relies upon glucose as its primary fuel. In recent years, a rich literature has developed from both human and animal studies indicating that increases in circulating blood glucose can facilitate cognitive functioning. This phenomenon has been termed the 'glucose memory facilitation effect'. The purpose of this review is to discuss a number of salient studies which have investigated the influence of glucose ingestion on neurocognitive performance in individuals with (a) compromised neurocognitive capacity, as well as (b) normally functioning individuals (with a focus on research conducted with human participants). The proposed neurocognitive mechanisms purported to underlie the modulatory effect of glucose on neurocognitive performance will also be considered. Many theories have focussed upon the hippocampus, given that this brain region is heavily implicated in learning and memory. Further, it will be suggested that glucose is a possible mechanism underlying the phenomenon that enhanced memory performance is typically observed for emotionally laden stimuli. Copyright © 2010 Elsevier Ltd. All rights reserved.

Quantitative aspects of the cytochemical demonstration of glucose-6-phosphate dehydrogenase with tetrazolium salts studied in a model system of polyacrylamide films

NARCIS (Netherlands)

van Noorden, C. J.; Tas, J.; Sanders, J. A.

1981-01-01

The enzyme cytochemical demonstration of glucose-6-phosphate dehydrogenase (G6PDH) with several tetrazolium salts has been studied with an artificial model of polyacrylamide films in corporated with the enzyme, which enabled teh correlation of cytochemical and biochemical data. In the model films no

[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.

The effect of serum from obese and normal weight men on glucose metabolism in leucocytes

International Nuclear Information System (INIS)

Myking, O.; Kjoesen, B.; Bassoee, H.H.

1980-01-01

The influence of pooled serum from either obese or normal weight males on glucose metabolism in human leucocytes has been studied. Leucocytes from normal weight males were incubated with 10-90% pooled serum and either [U- 14 C], or [1- 14 C]glucose. Compared to serum from the normal weight males, serum from the obese group had a more stimulating effect on the 14 CO 2 and [ 14 C]lactate production from [U- 14 C]glucose and on the 14 CO 2 production from [1- 14 C]glucose. The two serum pools had the same stimulating effect on the Embden-Meyerhof pathway as indicated by the formation of [ 14 C]lactate from [l- 14 C]glucose. Calculations revealed that the activity in the pentose phosphate pathway was stimulated more by serum from obese, than from normal weight males. It is a possibility that increased stimulation of the pentose phosphate pathway may contribute to the development of overweight. (author)

Glucose-6-phosphate dehydrogenase deficiency in Nigerian children.

Directory of Open Access Journals (Sweden)

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 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

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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

Phosphatidylinositol 3-phosphate 5-kinase (PIKfyve) is an AMPK target participating in contraction-stimulated glucose uptake in skeletal muscle.

Science.gov (United States)

Liu, Yang; Lai, Yu-Chiang; Hill, Elaine V; Tyteca, Donatienne; Carpentier, Sarah; Ingvaldsen, Ada; Vertommen, Didier; Lantier, Louise; Foretz, Marc; Dequiedt, Franck; Courtoy, Pierre J; Erneux, Christophe; Viollet, Benoît; Shepherd, Peter R; Tavaré, Jeremy M; Jensen, Jørgen; Rider, Mark H

2013-10-15

PIKfyve (FYVE domain-containing phosphatidylinositol 3-phosphate 5-kinase), the lipid kinase that phosphorylates PtdIns3P to PtdIns(3,5)P2, has been implicated in insulin-stimulated glucose uptake. We investigated whether PIKfyve could also be involved in contraction/AMPK (AMP-activated protein kinase)-stimulated glucose uptake in skeletal muscle. Incubation of rat epitrochlearis muscles with YM201636, a selective PIKfyve inhibitor, reduced contraction- and AICAriboside (5-amino-4-imidazolecarboxamide riboside)-stimulated glucose uptake. Consistently, PIKfyve knockdown in C2C12 myotubes reduced AICAriboside-stimulated glucose transport. Furthermore, muscle contraction increased PtdIns(3,5)P2 levels and PIKfyve phosphorylation. AMPK phosphorylated PIKfyve at Ser307 both in vitro and in intact cells. Following subcellular fractionation, PIKfyve recovery in a crude intracellular membrane fraction was increased in contracting versus resting muscles. Also in opossum kidney cells, wild-type, but not S307A mutant, PIKfyve was recruited to endosomal vesicles in response to AMPK activation. We propose that PIKfyve activity is required for the stimulation of skeletal muscle glucose uptake by contraction/AMPK activation. PIKfyve is a new AMPK substrate whose phosphorylation at Ser307 could promote PIKfyve translocation to endosomes for PtdIns(3,5)P2 synthesis to facilitate GLUT4 (glucose transporter 4) translocation.

Quantitative cytochemical analysis of glucose-6-phosphate dehydrogenase activity in living isolated hepatocytes of European flounder for rapid analysis of xenobiotic effects

NARCIS (Netherlands)

Winzer, K.; van Noorden, C. J.; Köhler, A.

2001-01-01

There is a great need for rapid but reliable assays to determine quantitatively effects of xenobiotics on biological systems in environmental research. Hepatocytes of European flounder are sensitive to low-dose toxic stress. Glucose-6-phosphate dehydrogenase (G6PDH) is the major source of NADPH in

Fatty acid and amino acid modulation of glucose cycling in isolated rat hepatocytes

NARCIS (Netherlands)

Gustafson, LA; Neeft, M; Reijngoud, DJ; Kuipers, F; Sauerwein, HP; Romijn, JA; Herling, AW; Burger, HJ; Meijer, AJ

2001-01-01

We studied the influence of glucose/glucose 6-phosphate cycling on glycogen deposition from glucose in fasted-rat hepatocytes using S4048 and CP320626, specific inhibitors of glucose-6-phosphate translocase and glycogen phosphorylase respectively. The effect of amino acids and oleate was also

Glucose transporter of the human brain and blood-brain barrier

International Nuclear Information System (INIS)

Kalaria, R.N.; Gravina, S.A.; Schmidley, J.W.; Perry, G.; Harik, S.I.

1988-01-01

We identified and characterized the glucose transporter in the human cerebral cortex, cerebral microvessels, and choroid plexus by specific D-glucose-displaceable [3H]cytochalasin B binding. The binding was saturable, with a dissociation constant less than 1 microM. Maximal binding capacity was approximately 7 pmol/mg protein in the cerebral cortex, approximately 42 pmol/mg protein in brain microvessels, and approximately 27 pmol/mg protein in the choroid plexus. Several hexoses displaced specific [3H]cytochalasin B binding to microvessels in a rank-order that correlated well with their known ability to cross the blood-brain barrier; the only exception was 2-deoxy-D-glucose, which had much higher affinity for the glucose transporter than the natural substrate, D-glucose. Irreversible photoaffinity labeling of the glucose transporter of microvessels with [3H]cytochalasin B, followed by solubilization and polyacrylamide gel electrophoresis, labeled a protein band with an average molecular weight of approximately 55,000. Monoclonal and polyclonal antibodies specific to the human erythrocyte glucose transporter immunocytochemically stained brain blood vessels and the few trapped erythrocytes in situ, with minimal staining of the neuropil. In the choroid plexus, blood vessels did not stain, but the epithelium reacted positively. We conclude that human brain microvessels are richly endowed with a glucose transport moiety similar in molecular weight and antigenic characteristics to that of human erythrocytes and brain microvessels of other mammalian species

Kinetic and thermodynamic study of the reaction catalyzed by glucose-6-phosphate dehydrogenase with nicotinamide adenine dinucleotide

International Nuclear Information System (INIS)

Martin del Campo, Julia S.; Patino, Rodrigo

2011-01-01

Research highlights: → The reaction catalyzed by one enzyme of the pentose phosphate pathway was studied. → A spectrophotometric method is proposed for kinetic and thermodynamic analysis. → The pH and the temperature influences are reported on physical chemical properties. → Relative concentrations of substrates are also important in the catalytic process. - Abstract: The enzyme glucose-6-phosphate dehydrogenase (G6PD, EC 1.1.1.49) from Leuconostoc mesenteroides has a dual coenzyme specificity with oxidized nicotinamide adenine dinucleotide (NAD ox ) and oxidized nicotinamide adenine dinucleotide phosphate as electron acceptors. The G6PD coenzyme selection is determined by the metabolic cellular prevailing conditions. In this study a kinetic and thermodynamic analysis is presented for the reaction catalyzed by G6PD from L. mesenteroides with NAD ox as coenzyme in phosphate buffer. For this work, an in situ spectrophotometric technique was employed based on the detection of one product of the reaction. Substrate and coenzyme concentrations as well as temperature and pH effects were evaluated. The apparent equilibrium constant, the Michaelis constant, and the turnover number were determined as a function of each experimental condition. The standard transformed Gibbs energy of reaction was determined from equilibrium constants at different initial conditions. For the product 6-phospho-D-glucono-1,5-lactone, a value of the standard Gibbs energy of formation is proposed, Δ f G o = -1784 ± 5 kJ mol -1 .

Kinetic and thermodynamic study of the reaction catalyzed by glucose-6-phosphate dehydrogenase with nicotinamide adenine dinucleotide

Energy Technology Data Exchange (ETDEWEB)

Martin del Campo, Julia S. [Departamento de Fisica Aplicada, Centro de Investigacion y de Estudios Avanzados - Unidad Merida, Carretera antigua a Progreso Km. 6, A.P. 73 Cordemex, 97310, Merida, Yucatan (Mexico); Patino, Rodrigo, E-mail: rtarkus@mda.cinvestav.mx [Departamento de Fisica Aplicada, Centro de Investigacion y de Estudios Avanzados - Unidad Merida, Carretera antigua a Progreso Km. 6, A.P. 73 Cordemex, 97310, Merida, Yucatan (Mexico)

2011-04-20

Research highlights: {yields} The reaction catalyzed by one enzyme of the pentose phosphate pathway was studied. {yields} A spectrophotometric method is proposed for kinetic and thermodynamic analysis. {yields} The pH and the temperature influences are reported on physical chemical properties. {yields} Relative concentrations of substrates are also important in the catalytic process. - Abstract: The enzyme glucose-6-phosphate dehydrogenase (G6PD, EC 1.1.1.49) from Leuconostoc mesenteroides has a dual coenzyme specificity with oxidized nicotinamide adenine dinucleotide (NAD{sub ox}) and oxidized nicotinamide adenine dinucleotide phosphate as electron acceptors. The G6PD coenzyme selection is determined by the metabolic cellular prevailing conditions. In this study a kinetic and thermodynamic analysis is presented for the reaction catalyzed by G6PD from L. mesenteroides with NAD{sub ox} as coenzyme in phosphate buffer. For this work, an in situ spectrophotometric technique was employed based on the detection of one product of the reaction. Substrate and coenzyme concentrations as well as temperature and pH effects were evaluated. The apparent equilibrium constant, the Michaelis constant, and the turnover number were determined as a function of each experimental condition. The standard transformed Gibbs energy of reaction was determined from equilibrium constants at different initial conditions. For the product 6-phospho-D-glucono-1,5-lactone, a value of the standard Gibbs energy of formation is proposed, {Delta}{sub f}G{sup o} = -1784 {+-} 5 kJ mol{sup -1}.

Dephosphorylation of 2-deoxyglucose 6-phosphate and 2-deoxyglucose export from cultured astrocytes.

Science.gov (United States)

Forsyth, R J; Bartlett, K; Eyre, J

1996-03-01

Neurotransmitter-stimulated mobilization of astrocyte glycogen has been proposed as a basis for local energy homeostasis in brain. However, uncertainty remains over the fate of astrocyte glycogen. Upon transfer of cultured astrocytes pre-loaded with [2-3H]2-deoxyglucose 6-phosphate at non-tracer concentrations to a glucose-free, 2-deoxyglucose-free medium, rapid dephosphorylation of a proportion of the intracellular 2-deoxyglucose 6-phosphate pool and export of 2-deoxyglucose to the extracellular fluid occurs. Astrocytes show very low, basal rates of gluconeogenesis from pyruvate (approx. 1 nmol mg protein-1 h-1). Astrocytes in vivo may be capable of physiologically significant glucose export from glucose-6-phosphate. The low gluconeogenic activity in astrocytes suggests that the most likely source of glucose-6-phosphate may be glycogen. These findings support the hypothesis that export, as glucose, to adjacent neurons may be one of the possible fate(s) of astrocytic glycogen. Such export of glycogen as glucose occurring in response to increases in neuronal activity could contribute to energy homeostasis on a paracrine scale within brain.

Molecular Characterization of Cosenza Mutation among Patients with Glucose-6-Phosphate Dehydrogenase Deficiency in huzestan Province, Southwest Iran

Science.gov (United States)

Kazemi Nezhad, Seyed Reza; Fahmi, Fatemeh; Khatami, Saeid Reza; Musaviun, Mohsen

2011-01-01

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is one of the most common hereditary enzymatic disorders in human, increases the vulnerability of erythrocytes to oxidative stress. It is also characterized by remarkable molecular and biochemical heterogeneity. According to previous investigations, G6PD Cosenza (G1376C) is a common G6PD mutation in some parts of . Therefore in the present study we have characterized mutation among G6PD deficient individuals in Khuzestan province. In order to identify G6PD Cosenza, we analyzed the G6PD gene in 64 samples out of 231 deficient individuals who had not G6PD Mediterranean mutation, using PCR- restriction fragment length polymorphism (RFLP) method. G6PD Cosenza mutation was found in 6 males of 231 samples, resulting in the relative rate of 2.6% and allele frequency of 0.023 among Khuzestanian G6PD deficient subjects. A comparison of these results with previous findings in some parts of suggests that G6PD Cosenza is a common mutation in Khuzestanian G6PD deficient individuals. PMID:23365477

Regulation of intracellular glucose and polyol pathway by thiamine and benfotiamine in vascular cells cultured in high glucose.

Science.gov (United States)

Berrone, Elena; Beltramo, Elena; Solimine, Carmela; Ape, Alessandro Ubertalli; Porta, Massimo

2006-04-07

Hyperglycemia is a causal factor in the development of the vascular complications of diabetes. One of the biochemical mechanisms activated by excess glucose is the polyol pathway, the key enzyme of which, aldose reductase, transforms d-glucose into d-sorbitol, leading to imbalances of intracellular homeostasis. We aimed at verifying the effects of thiamine and benfotiamine on the polyol pathway, transketolase activity, and intracellular glucose in endothelial cells and pericytes under high ambient glucose. Human umbilical vein endothelial cells and bovine retinal pericytes were cultured in normal (5.6 mmol/liter) or high (28 mmol/liter) glucose, with or without thiamine or benfotiamine 50 or 100 mumol/liter. Transketolase and aldose reductase mRNA expression was determined by reverse transcription-PCR, and their activity was measured spectrophotometrically; sorbitol concentrations were quantified by gas chromatography-mass spectrometry and intracellular glucose concentrations by fluorescent enzyme-linked immunosorbent assay method. Thiamine and benfotiamine reduce aldose reductase mRNA expression, activity, sorbitol concentrations, and intracellular glucose while increasing the expression and activity of transketolase, for which it is a coenzyme, in human endothelial cells and bovine retinal pericytes cultured in high glucose. Thiamine and benfotiamine correct polyol pathway activation induced by high glucose in vascular cells. Activation of transketolase may shift excess glycolytic metabolites into the pentose phosphate cycle, accelerate the glycolytic flux, and reduce intracellular free glucose, thereby preventing its conversion to sorbitol. This effect on the polyol pathway, together with other beneficial effects reported for thiamine in high glucose, could justify testing thiamine as a potential approach to the prevention and/or treatment of diabetic complications.

Inhibition by nucleosides of glucose-transport activity in human erythrocytes.

OpenAIRE

Jarvis, S M

1988-01-01

The interaction of nucleosides with the glucose carrier of human erythrocytes was examined by studying the effect of nucleosides on reversible cytochalasin B-binding activity and glucose transport. Adenosine, inosine and thymidine were more potent inhibitors of cytochalasin B binding to human erythrocyte membranes than was D-glucose [IC50 (concentration causing 50% inhibition) values of 10, 24, 28 and 38 mM respectively]. Moreover, low concentrations of thymidine and adenosine inhibited D-glu...

Data on how several physiological parameters of stored red blood cells are similar in glucose 6-phosphate dehydrogenase deficient and sufficient donors

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Vassilis L. Tzounakas

2016-09-01

Full Text Available This article contains data on the variation in several physiological parameters of red blood cells (RBCs donated by eligible glucose-6-phosphate dehydrogenase (G6PD deficient donors during storage in standard blood bank conditions compared to control, G6PD sufficient (G6PD+ cells. Intracellular reactive oxygen species (ROS generation, cell fragility and membrane exovesiculation were measured in RBCs throughout the storage period, with or without stimulation by oxidants, supplementation of N-acetylcysteine and energy depletion, following incubation of stored cells for 24 h at 37 °C. Apart from cell characteristics, the total or uric acid-dependent antioxidant capacity of the supernatant in addition to extracellular potassium concentration was determined in RBC units. Finally, procoagulant activity and protein carbonylation levels were measured in the microparticles population. Further information can be found in “Glucose 6-phosphate dehydrogenase deficient subjects may be better “storers” than donors of red blood cells” [1]. Keywords: G6PD deficiency, Red blood cell storage lesion, Oxidative stress, Cell fragility, Microparticles

Glucose-6-phosphate dehydrogenase in rat lung alveolar epithelial cells. An ultrastructural enzyme-cytochemical study

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S Matsubara

2010-01-01

Full Text Available Glucose-6-phosphate dehydrogenase (G6PD is the key enzyme of the pentose phosphate pathway in carbohydrate metabolism, and it plays an important role in cell proliferation and antioxidant regulation within cells in various organs. Although marked cell proliferation and oxidant/antioxidant metabolism occur in lung alveolar epithelial cells, definite data has been lacking as to whether cytochemically detectable G6PD is present in alveolar epithelial cells. The distribution pattern of G6PD within these cells, if it is present, is also unknown. The purpose of the present study was to investigate the subcellular localization of G6PD in alveolar cells in the rat lung using a newly- developed enzyme-cytochemistry (copper-ferrocyanide method. Type I cells and stromal endothelia and fibroblasts showed no activities. Electron-dense precipitates indicating G6PD activity were clearly visible in the cytoplasm and on the cytosolic side of the endoplasmic reticulum of type II alveolar epithelial cells. The cytochemical controls ensured specific detection of enzyme activity. This enzyme may play a role in airway defense by delivering substances for cell proliferation and antioxidant forces, thus maintaining the airway architecture.

Simultaneous measurement of glucose transport and utilization in the human brain

Science.gov (United States)

Shestov, Alexander A.; Emir, Uzay E.; Kumar, Anjali; Henry, Pierre-Gilles; Seaquist, Elizabeth R.

2011-01-01

Glucose is the primary fuel for brain function, and determining the kinetics of cerebral glucose transport and utilization is critical for quantifying cerebral energy metabolism. The kinetic parameters of cerebral glucose transport, KMt and Vmaxt, in humans have so far been obtained by measuring steady-state brain glucose levels by proton (1H) NMR as a function of plasma glucose levels and fitting steady-state models to these data. Extraction of the kinetic parameters for cerebral glucose transport necessitated assuming a constant cerebral metabolic rate of glucose (CMRglc) obtained from other tracer studies, such as 13C NMR. Here we present new methodology to simultaneously obtain kinetic parameters for glucose transport and utilization in the human brain by fitting both dynamic and steady-state 1H NMR data with a reversible, non-steady-state Michaelis-Menten model. Dynamic data were obtained by measuring brain and plasma glucose time courses during glucose infusions to raise and maintain plasma concentration at ∼17 mmol/l for ∼2 h in five healthy volunteers. Steady-state brain vs. plasma glucose concentrations were taken from literature and the steady-state portions of data from the five volunteers. In addition to providing simultaneous measurements of glucose transport and utilization and obviating assumptions for constant CMRglc, this methodology does not necessitate infusions of expensive or radioactive tracers. Using this new methodology, we found that the maximum transport capacity for glucose through the blood-brain barrier was nearly twofold higher than maximum cerebral glucose utilization. The glucose transport and utilization parameters were consistent with previously published values for human brain. PMID:21791622

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

Glucose-6-Phosphate Dehydrogenase Enhances Antiviral Response through Downregulation of NADPH Sensor HSCARG and Upregulation of NF-κB Signaling

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Yi-Hsuan Wu

2015-12-01

Full Text Available Glucose-6-phosphate dehydrogenase (G6PD-deficient cells are highly susceptible to viral infection. This study examined the mechanism underlying this phenomenon by measuring the expression of antiviral genes—tumor necrosis factor alpha (TNF-α and GTPase myxovirus resistance 1 (MX1—in G6PD-knockdown cells upon human coronavirus 229E (HCoV-229E and enterovirus 71 (EV71 infection. Molecular analysis revealed that the promoter activities of TNF-α and MX1 were downregulated in G6PD-knockdown cells, and that the IκB degradation and DNA binding activity of NF-κB were decreased. The HSCARG protein, a nicotinamide adenine dinucleotide phosphate (NADPH sensor and negative regulator of NF-κB, was upregulated in G6PD-knockdown cells with decreased NADPH/NADP+ ratio. Treatment of G6PD-knockdown cells with siRNA against HSCARG enhanced the DNA binding activity of NF-κB and the expression of TNF-α and MX1, but suppressed the expression of viral genes; however, the overexpression of HSCARG inhibited the antiviral response. Exogenous G6PD or IDH1 expression inhibited the expression of HSCARG, resulting in increased expression of TNF-α and MX1 and reduced viral gene expression upon virus infection. Our findings suggest that the increased susceptibility of the G6PD-knockdown cells to viral infection was due to impaired NF-κB signaling and antiviral response mediated by HSCARG.

Effect of tamoxifen pre-treatment on the retention of tritiated oestradiol and 5. cap alpha. -dihydrotestosterone and on glucose metabolism in human breast carcinomas

Energy Technology Data Exchange (ETDEWEB)

Deshpande, N; Mitchell, I [Imperial Cancer Research Fund, London (UK). Labs.; Hughes, D

1978-05-01

The effect of pre-treatment with tamoxifen on glucose metabolism and retention of injected oestradiol-17B and 5..cap alpha..-dihydrotestosterone by human breast carcinomas were studied in patients undergoing mastectomy. The following effects were observed: the pretreatment reduced retention of oestradiol-17B whereas a small but statistically significant rise in 5..cap alpha..-dihydrotestosterone accumulation was observed. There was an increase in both phosphofructokinase (PFK) and glucose-6-phosphate dehydrogenase (G6PDH) activities in tumours from treated patients whereas ..cap alpha..-glycerolphosphate dehydrogenase (..cap alpha..-GPDH) activity was significantly reduced in the same tumours. The significance of these findings is discussed and it is argued that these changes in carbohydrate metabolism may not be due to the blocking of hormone receptors.

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

Physiological role of glucose-6-phosphate dehydrogenase in cold acclimation of strawberry (Fragaria × ananassa)

Science.gov (United States)

Zhang, Yong; Yu, Dingqun; Luo, Ya; Wang, Xiaorong; Chen, Qing; Sun, Bo; Wang, Yan; Liu, Zejing; Tang, Haoru

2018-04-01

In recent years, there has been an increasing interest in study of new resistance mechanism in fruit trees. All these regard the climate change and subsequent fruit production. Glucose-6-phosphate dehydrogenase (G6PDH) catalyzes the first and rate-limiting step of the oxidative pentose phosphate pathway (OPPP), and the expression of this enzyme is related to different biotic and abiotic stresses. Under accumulation of low temperature stress, the significant increase in G6PDH activity was found to be closely correlated to the levels of antioxidant enzymes, malondialdehyde (MDA) contents, sugar contents as well as changes of superoxide (O2•-). It is suggested that the enhancement of cold resistance of strawberry, which induced by cold acclimation, related to the significant increase in G6PDH activity. On one hand, G6PDH activates NADPH oxidase to generate reactive oxygen species (ROS); on the other hand, it may be involved in the activation of antioxidant enzymes, and accelerates many other important NADPH-dependent enzymatic reactions. Then further result in the elevation of membrane stability and cold resistance of strawberry. Interestingly, even though the plants were placed again under a temperature of 25°C for 1 d, the higher cold resistance, enzyme activities and soluble sugar content acquired.

Glucose-6-phosphate dehydrogenase deficiency does not increase the susceptibility of sperm to oxidative stress induced by H2O2.

Science.gov (United States)

Roshankhah, Shiva; Rostami-Far, Zahra; Shaveisi-Zadeh, Farhad; Movafagh, Abolfazl; Bakhtiari, Mitra; Shaveisi-Zadeh, Jila

2016-12-01

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is the most common human enzyme defect. G6PD plays a key role in the pentose phosphate pathway, which is a major source of nicotinamide adenine dinucleotide phosphate (NADPH). NADPH provides the reducing equivalents for oxidation-reduction reductions involved in protecting against the toxicity of reactive oxygen species such as H 2 O 2 . We hypothesized that G6PD deficiency may reduce the amount of NADPH in sperms, thereby inhibiting the detoxification of H 2 O 2 , which could potentially affect their motility and viability, resulting in an increased susceptibility to infertility. Semen samples were obtained from four males with G6PD deficiency and eight healthy males as a control. In both groups, motile sperms were isolated from the seminal fluid and incubated with 0, 10, 20, 40, 60, 80, and 120 µM concentrations of H 2 O 2 . After 1 hour incubation at 37℃, sperms were evaluated for motility and viability. Incubation of sperms with 10 and 20 µM H 2 O 2 led to very little decrease in motility and viability, but motility decreased notably in both groups in 40, 60, and 80 µM H 2 O 2 , and viability decreased in both groups in 40, 60, 80, and 120 µM H 2 O 2 . However, no statistically significant differences were found between the G6PD-deficient group and controls. G6PD deficiency does not increase the susceptibility of sperm to oxidative stress induced by H 2 O 2 , and the reducing equivalents necessary for protection against H 2 O 2 are most likely produced by other pathways. Therefore, G6PD deficiency cannot be considered as major risk factor for male infertility.

Enhanced neuronal glucose transporter expression reveals metabolic choice in a HD Drosophila model.

Science.gov (United States)

Besson, Marie Thérèse; Alegría, Karin; Garrido-Gerter, Pamela; Barros, Luis Felipe; Liévens, Jean-Charles

2015-01-01

Huntington's disease is a neurodegenerative disorder caused by toxic insertions of polyglutamine residues in the Huntingtin protein and characterized by progressive deterioration of cognitive and motor functions. Altered brain glucose metabolism has long been suggested and a possible link has been proposed in HD. However, the precise function of glucose transporters was not yet determined. Here, we report the effects of the specifically-neuronal human glucose transporter expression in neurons of a Drosophila model carrying the exon 1 of the human huntingtin gene with 93 glutamine repeats (HQ93). We demonstrated that overexpression of the human glucose transporter in neurons ameliorated significantly the status of HD flies by increasing their lifespan, reducing their locomotor deficits and rescuing eye neurodegeneration. Then, we investigated whether increasing the major pathways of glucose catabolism, glycolysis and pentose-phosphate pathway (PPP) impacts HD. To mimic increased glycolytic flux, we overexpressed phosphofructokinase (PFK) which catalyzes an irreversible step in glycolysis. Overexpression of PFK did not affect HQ93 fly survival, but protected from photoreceptor loss. Overexpression of glucose-6-phosphate dehydrogenase (G6PD), the key enzyme of the PPP, extended significantly the lifespan of HD flies and rescued eye neurodegeneration. Since G6PD is able to synthesize NADPH involved in cell survival by maintenance of the redox state, we showed that tolerance to experimental oxidative stress was enhanced in flies co-expressing HQ93 and G6PD. Additionally overexpressions of hGluT3, G6PD or PFK were able to circumvent mitochondrial deficits induced by specific silencing of genes necessary for mitochondrial homeostasis. Our study confirms the involvement of bioenergetic deficits in HD course; they can be rescued by specific expression of a glucose transporter in neurons. Finally, the PPP and, to a lesser extent, the glycolysis seem to mediate the hGluT3

Enhanced neuronal glucose transporter expression reveals metabolic choice in a HD Drosophila model.

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Marie Thérèse Besson

Full Text Available Huntington's disease is a neurodegenerative disorder caused by toxic insertions of polyglutamine residues in the Huntingtin protein and characterized by progressive deterioration of cognitive and motor functions. Altered brain glucose metabolism has long been suggested and a possible link has been proposed in HD. However, the precise function of glucose transporters was not yet determined. Here, we report the effects of the specifically-neuronal human glucose transporter expression in neurons of a Drosophila model carrying the exon 1 of the human huntingtin gene with 93 glutamine repeats (HQ93. We demonstrated that overexpression of the human glucose transporter in neurons ameliorated significantly the status of HD flies by increasing their lifespan, reducing their locomotor deficits and rescuing eye neurodegeneration. Then, we investigated whether increasing the major pathways of glucose catabolism, glycolysis and pentose-phosphate pathway (PPP impacts HD. To mimic increased glycolytic flux, we overexpressed phosphofructokinase (PFK which catalyzes an irreversible step in glycolysis. Overexpression of PFK did not affect HQ93 fly survival, but protected from photoreceptor loss. Overexpression of glucose-6-phosphate dehydrogenase (G6PD, the key enzyme of the PPP, extended significantly the lifespan of HD flies and rescued eye neurodegeneration. Since G6PD is able to synthesize NADPH involved in cell survival by maintenance of the redox state, we showed that tolerance to experimental oxidative stress was enhanced in flies co-expressing HQ93 and G6PD. Additionally overexpressions of hGluT3, G6PD or PFK were able to circumvent mitochondrial deficits induced by specific silencing of genes necessary for mitochondrial homeostasis. Our study confirms the involvement of bioenergetic deficits in HD course; they can be rescued by specific expression of a glucose transporter in neurons. Finally, the PPP and, to a lesser extent, the glycolysis seem to

Radiation target analyses of free and immobilized glucose 6-phosphate dehydrogenase

International Nuclear Information System (INIS)

Kempner, E.S.; Miller, J.H.

2010-01-01

The sensitivity of the enzyme glucose 6-phosphate dehydrogenase to ionizing radiation was examined under several conditions, including the presence of several free-radical scavengers. The enzyme was also irradiated when covalently bound to polyacrylamide beads whose structure is very similar to the polypeptide backbone of proteins. All the enzyme forms were irradiated in the frozen state with high-energy electrons from a linear accelerator. Surviving enzyme activity and surviving monomers were determined; the data were analyzed by target theory. Free-radical scavengers reduced the radiation target size of both the activity and monomers of the free enzyme, but not that of the immobilized enzyme activity. The target size of the activity of the free enzyme was that of a dimer mass, but in the case of the immobilized enzyme it was equal to the smaller mass of the monomer. Free-radical scavengers reduce the target size by modifying radiation energy transfer. The target size of the polyacrylamide-bound enzyme activity was expected to be very large since the connection between polyacrylamide and protein is a peptide bond which permits transfer of radiation-deposited energy. Several explanations concerning energy transfer are suggested for this result.

Molecular Characterization of Cosenza Mutation among Patients with Glucose-6-Phosphate Dehydrogenase Deficiency in Khuzestan Province, Southwest Iran

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Seyed Reza Kazemi Nezhad

2011-03-01

Full Text Available Glucose-6-phosphate dehydrogenase (G6PD deficiency is one of the most common hereditary enzymatic disorders in human, increases the vulnerability of erythrocytes to oxidative stress. It is also characterized by remarkable molecular and biochemical heterogeneity. According to previous investigations, G6PD Cosenza (G1376C is a common G6PD mutation in some parts of Iran. Therefore in the present study we have characterized Cosenza mutation among G6PD deficient individuals in Khuzestan province. In order to identify G6PD Cosenza, we analyzed the G6PD gene in 64 samples out of 231 deficient individuals who had not G6PD Mediterranean mutation, using PCR- restriction fragment length polymorphism (RFLP method. G6PD Cosenza mutation was found in 6 males of 231 samples, resulting in the relative rate of 2.6% and allele frequency of 0.023 among Khuzestanian G6PD deficient subjects. A comparison of these results with previous findings in some parts of Iran suggests that G6PD Cosenza is a common mutation in Khuzestanian G6PD deficient individuals

Nuclear magnetic resonance studies of the regulation of the pentose phosphate pathway

International Nuclear Information System (INIS)

Bolo, N.R.

1991-11-01

The goal of this work is to investigate the potential for and limitations of in vivo nuclear magnetic resonance (NMR) spectroscopy for quantitation of glucose flux through the pentose phosphate pathway (shunt). Interest in the shunt is motivated by the possibility that its activity may be greatly increased in cancer and in the pathological states of cardiac and cerebral ischemia. The ability to dynamically monitor flux through the pentose shunt can give new knowledge about metabolism in pathological states. 13 C NMR spectroscopy was used to monitor shunt activity by determination of the ratios of [ 13 C-4] to [ 13 C-5]-glutamate, [ 13 C-3] to [ 13 C-2]-alanine or [ 13 C-3] to [ 13 C-2]-lactate produced when [ 13 C-2]-glucose is infused. These methods provide measures of the effect of oxidative stresses on shunt activity in systems ranging from cell free enzyme-substrate preparations to cell suspensions and whole animals. In anaerobic cell free preparations, the fraction of glucose flux through the shunt was monitored with a time resolution of 3 minutes. This work predicts the potential for in vivo human studies of pentose phosphate pathway activity based on the mathematical simulation of the 13 C fractional enrichments of C4 and C5-glutamate as a function of shunt activity and on the signal-to- noise ratio acquired in 13 C NMR human studies from the current literature

Nuclear magnetic resonance studies of the regulation of the pentose phosphate pathway

Energy Technology Data Exchange (ETDEWEB)

Bolo, N.R.

1991-11-01

The goal of this work is to investigate the potential for and limitations of in vivo nuclear magnetic resonance (NMR) spectroscopy for quantitation of glucose flux through the pentose phosphate pathway (shunt). Interest in the shunt is motivated by the possibility that its activity may be greatly increased in cancer and in the pathological states of cardiac and cerebral ischemia. The ability to dynamically monitor flux through the pentose shunt can give new knowledge about metabolism in pathological states. {sup 13}C NMR spectroscopy was used to monitor shunt activity by determination of the ratios of ({sup 13}C-4) to ({sup 13}C-5)-glutamate, ({sup 13}C-3) to ({sup 13}C-2)-alanine or ({sup 13}C-3) to ({sup 13}C-2)-lactate produced when ({sup 13}C-2)-glucose is infused. These methods provide measures of the effect of oxidative stresses on shunt activity in systems ranging from cell free enzyme-substrate preparations to cell suspensions and whole animals. In anaerobic cell free preparations, the fraction of glucose flux through the shunt was monitored with a time resolution of 3 minutes. This work predicts the potential for in vivo human studies of pentose phosphate pathway activity based on the mathematical simulation of the {sup 13}C fractional enrichments of C4 and C5-glutamate as a function of shunt activity and on the signal-to- noise ratio acquired in {sup 13}C NMR human studies from the current literature.

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.

Simultaneous measurement of glucose transport and utilization in the human brain

OpenAIRE

Shestov, Alexander A.; Emir, Uzay E.; Kumar, Anjali; Henry, Pierre-Gilles; Seaquist, Elizabeth R.; Öz, Gülin

2011-01-01

Glucose is the primary fuel for brain function, and determining the kinetics of cerebral glucose transport and utilization is critical for quantifying cerebral energy metabolism. The kinetic parameters of cerebral glucose transport, KMt and Vmaxt, in humans have so far been obtained by measuring steady-state brain glucose levels by proton (1H) NMR as a function of plasma glucose levels and fitting steady-state models to these data. Extraction of the kinetic parameters for cerebral glucose tra...

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

Science.gov (United States)

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.

Mapping glucose-mediated gut-to-brain signalling pathways in humans.

Science.gov (United States)

Little, Tanya J; McKie, Shane; Jones, Richard B; D'Amato, Massimo; Smith, Craig; Kiss, Orsolya; Thompson, David G; McLaughlin, John T

2014-08-01

Previous fMRI studies have demonstrated that glucose decreases the hypothalamic BOLD response in humans. However, the mechanisms underlying the CNS response to glucose have not been defined. We recently demonstrated that the slowing of gastric emptying by glucose is dependent on activation of the gut peptide cholecystokinin (CCK1) receptor. Using physiological functional magnetic resonance imaging this study aimed to determine the whole brain response to glucose, and whether CCK plays a central role. Changes in blood oxygenation level-dependent (BOLD) signal were monitored using fMRI in 12 healthy subjects following intragastric infusion (250ml) of: 1M glucose+predosing with dexloxiglumide (CCK1 receptor antagonist), 1M glucose+placebo, or 0.9% saline (control)+placebo, in a single-blind, randomised fashion. Gallbladder volume, blood glucose, insulin, and GLP-1 and CCK concentrations were determined. Hunger, fullness and nausea scores were also recorded. Intragastric glucose elevated plasma glucose, insulin, and GLP-1, and reduced gall bladder volume (an in vivo assay for CCK secretion). Glucose decreased BOLD signal, relative to saline, in the brainstem and hypothalamus as well as the cerebellum, right occipital cortex, putamen and thalamus. The timing of the BOLD signal decrease was negatively correlated with the rise in blood glucose and insulin levels. The glucose+dex arm highlighted a CCK1-receptor dependent increase in BOLD signal only in the motor cortex. Glucose induces site-specific differences in BOLD response in the human brain; the brainstem and hypothalamus show a CCK1 receptor-independent reduction which is likely to be mediated by a circulatory effect of glucose and insulin, whereas the motor cortex shows an early dexloxiglumide-reversible increase in signal, suggesting a CCK1 receptor-dependent neural pathway. Copyright © 2014. Published by Elsevier Inc.

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

Identification of four amino acid substitutions in hexokinase II and studies of relationships to NIDDM, glucose effectiveness, and insulin sensitivity

DEFF Research Database (Denmark)

Echwald, Søren Morgenthaler; Bjørbaek, C; Hansen, Torben

1995-01-01

not predict any change in amino acid composition of the protein. One homozygous and nine heterozygous carriers of the codon 142 mutation were found among the NIDDM patients. The mutations at codons 148, 497, and 844 were each found in one diabetic subject and only on one allele. There were no carriers......Human hexokinase (HK) II, a glucose phosphorylating enzyme in muscle tissue, plays a central role in glucose metabolism. Since reduced insulin-stimulated glucose uptake and reduced glucose-6-phosphate content in muscle have been demonstrated in pre-non-insulin-dependent diabetes mellitus (pre...

A novel GDP-D-glucose phosphorylase involved in quality control of the nucleoside diphosphate sugar pool in Caenorhabditis elegans and mammals.

Science.gov (United States)

Adler, Lital N; Gomez, Tara A; Clarke, Steven G; Linster, Carole L

2011-06-17

The plant VTC2 gene encodes GDP-L-galactose phosphorylase, a rate-limiting enzyme in plant vitamin C biosynthesis. Genes encoding apparent orthologs of VTC2 exist in both mammals, which produce vitamin C by a distinct metabolic pathway, and in the nematode worm Caenorhabditis elegans where vitamin C biosynthesis has not been demonstrated. We have now expressed cDNAs of the human and worm VTC2 homolog genes (C15orf58 and C10F3.4, respectively) and found that the purified proteins also display GDP-hexose phosphorylase activity. However, as opposed to the plant enzyme, the major reaction catalyzed by these enzymes is the phosphorolysis of GDP-D-glucose to GDP and D-glucose 1-phosphate. We detected activities with similar substrate specificity in worm and mouse tissue extracts. The highest expression of GDP-D-glucose phosphorylase was found in the nervous and male reproductive systems. A C. elegans C10F3.4 deletion strain was found to totally lack GDP-D-glucose phosphorylase activity; this activity was also found to be decreased in human HEK293T cells transfected with siRNAs against the human C15orf58 gene. These observations confirm the identification of the worm C10F3.4 and the human C15orf58 gene expression products as the GDP-D-glucose phosphorylases of these organisms. Significantly, we found an accumulation of GDP-D-glucose in the C10F3.4 mutant worms, suggesting that the GDP-D-glucose phosphorylase may function to remove GDP-D-glucose formed by GDP-D-mannose pyrophosphorylase, an enzyme that has previously been shown to lack specificity for its physiological D-mannose 1-phosphate substrate. We propose that such removal may prevent the misincorporation of glucosyl residues for mannosyl residues into the glycoconjugates of worms and mammals.

A Novel GDP-d-glucose Phosphorylase Involved in Quality Control of the Nucleoside Diphosphate Sugar Pool in Caenorhabditis elegans and Mammals*

Science.gov (United States)

Adler, Lital N.; Gomez, Tara A.; Clarke, Steven G.; Linster, Carole L.

2011-01-01

The plant VTC2 gene encodes GDP-l-galactose phosphorylase, a rate-limiting enzyme in plant vitamin C biosynthesis. Genes encoding apparent orthologs of VTC2 exist in both mammals, which produce vitamin C by a distinct metabolic pathway, and in the nematode worm Caenorhabditis elegans where vitamin C biosynthesis has not been demonstrated. We have now expressed cDNAs of the human and worm VTC2 homolog genes (C15orf58 and C10F3.4, respectively) and found that the purified proteins also display GDP-hexose phosphorylase activity. However, as opposed to the plant enzyme, the major reaction catalyzed by these enzymes is the phosphorolysis of GDP-d-glucose to GDP and d-glucose 1-phosphate. We detected activities with similar substrate specificity in worm and mouse tissue extracts. The highest expression of GDP-d-glucose phosphorylase was found in the nervous and male reproductive systems. A C. elegans C10F3.4 deletion strain was found to totally lack GDP-d-glucose phosphorylase activity; this activity was also found to be decreased in human HEK293T cells transfected with siRNAs against the human C15orf58 gene. These observations confirm the identification of the worm C10F3.4 and the human C15orf58 gene expression products as the GDP-d-glucose phosphorylases of these organisms. Significantly, we found an accumulation of GDP-d-glucose in the C10F3.4 mutant worms, suggesting that the GDP-d-glucose phosphorylase may function to remove GDP-d-glucose formed by GDP-d-mannose pyrophosphorylase, an enzyme that has previously been shown to lack specificity for its physiological d-mannose 1-phosphate substrate. We propose that such removal may prevent the misincorporation of glucosyl residues for mannosyl residues into the glycoconjugates of worms and mammals. PMID:21507950

Negative Effects of High Glucose Exposure in Human Gonadotropin-Releasing Hormone Neurons

Directory of Open Access Journals (Sweden)

Annamaria Morelli

2013-01-01

Full Text Available Metabolic disorders are often associated with male hypogonadotropic hypogonadism, suggesting that hypothalamic defects involving GnRH neurons may impair the reproductive function. Among metabolic factors hyperglycemia has been implicated in the control of the reproductive axis at central level, both in humans and in animal models. To date, little is known about the direct effects of pathological high glucose concentrations on human GnRH neurons. In this study, we investigated the high glucose effects in the human GnRH-secreting FNC-B4 cells. Gene expression profiling by qRT-PCR, confirmed that FNC-B4 cells express GnRH and several genes relevant for GnRH neuron function (KISS1R, KISS1, sex steroid and leptin receptors, FGFR1, neuropilin 2, and semaphorins, along with glucose transporters (GLUT1, GLUT3, and GLUT4. High glucose exposure (22 mM; 40 mM significantly reduced gene and protein expression of GnRH, KISS1R, KISS1, and leptin receptor, as compared to normal glucose (5 mM. Consistent with previous studies, leptin treatment significantly induced GnRH mRNA expression at 5 mM glucose, but not in the presence of high glucose concentrations. In conclusion, our findings demonstrate a deleterious direct contribution of high glucose on human GnRH neurons, thus providing new insights into pathogenic mechanisms linking metabolic disorders to reproductive dysfunctions.

F-19 MR imaging of glucose metabolism in the rat and rabbit

International Nuclear Information System (INIS)

Nakada, T.; Kwee, I.L.; Card, P.J.; Matwiyoff, N.A.; Griffey, B.V.; Griffey, R.H.

1987-01-01

MR imaging reflecting regional pathway specific glucose metabolism was performed utilizing F-19 as the MR signal probe and two fluorinated glucose analogues, 2-fluoro-2-deoxy-D-glucose (2-FDG) and 3-fluoro-3-deoxy-D-glucose (3-FDG) as the metabolic probe. 2-FDG-6-phosphate images provides regional quantitative information regarding glycolytic activities, while 2-FDG-6-phosphoglyconate images provide information on the pentose monophosphate shunt activities. 3-FDG-sorbitol and 3-FDG-fructose indicate regional aldose reductase and sorbitol dehydrogenase activities of the aldose reductase sorbitol pathway, respectively. The potential toxicity of 2-FDG in high doses precludes the immediate application of the 2-FDG MR imaging method to humans. The extremely low toxicity of 3-FDG, however, indicates promise for clinical application of 3-FDG MR imaging

13C NMR for the assessment of human brain glucose metabolism in vivo

International Nuclear Information System (INIS)

Beckman, N.; Seelig, J.; Turkalj, I.; Keller, U.

1991-01-01

Proton-decoupled 13 C NMR spectra of the human head were obtained during hyperglycemic glucose clamping using intravenous infusions of [1- 13 C]glucose in normal volunteers. In addition to 13 C signals of mobile lipids, a variety of new metabolite resonances could be resolved for the first time in the human brain. At an enrichment level of 20% [1- 13 C]glucose, the signals of α- and β-glucose at 92.7 and 96.6 ppm, respectively, could be detected in the human brain after only an infusion period of 15 minutes. The spatial localization of the different regions of interest was confirmed by 13 C NMR spectroscopic imaging with a time resolution of 9 minutes. Increasing the enrichment level to 99% [1- 13 C]glucose not only improved the time resolution but allowed the detection of metabolic breakdown products of [1- 13 C]glucose. The time course of 13 C label incorporation into the C 2 , C 3 , and C 4 resonances of glutamate/glutamine and into lactate could be recorded in the human brain. These results suggest the possibility of obtaining time-resolved, spatially selective, and chemically specific information on the human body

Radioactivity contents in dicalcium phosphate and the potential radiological risk to human populations

International Nuclear Information System (INIS)

Casacuberta, N.; Masque, P.; Garcia-Orellana, J.; Bruach, J.M.; Anguita, M.; Gasa, J.; Villa, M.; Hurtado, S.; Garcia-Tenorio, R.

2009-01-01

Potentially harmful phosphate-based products derived from the wet acid digestion of phosphate rock represent one of the most serious problems facing the phosphate industry. This is particularly true for dicalcium phosphate (DCP), a food additive produced from either sulphuric acid or hydrochloric acid digestion of raw rock material. This study determined the natural occurring radionuclide concentrations of 12 DCP samples and 4 tricalcium phosphate (TCP) samples used for animal and human consumption, respectively. Metal concentrations (Al, Fe, Zn, Cd, Cr, As, Hg, Pb and Mg) were also determined. Samples were grouped into three different clusters (A, B, C) based on their radionuclide content. Whereas group A is characterized by high activities of 238 U, 234 U (∼10 3 Bq kg -1 ), 210 Pb (2 x 10 3 Bq kg -1 ) and 210 Po (∼800 Bq kg -1 ); group B presents high activities of 238 U, 234 U and 230 Th (∼10 3 Bq kg -1 ). Group C was characterized by very low activities of all radionuclides ( -1 ). Differences between the two groups of DCP samples for animal consumption (groups A and B) were related to the wet acid digestion method used, with group A samples produced from hydrochloric acid digestion, and group B samples produced using sulphuric acid. Group C includes more purified samples required for human consumption. High radionuclide concentrations in some DCP samples (reaching 2 x 10 3 and 10 3 Bq kg -1 of 210 Pb and 210 Po, respectively) may be of concern due to direct or indirect radiological exposure via ingestion. Our experimental results based on 210 Pb and 210 Po within poultry consumed by humans, suggest that the maximum radiological doses are 11 ± 2 μSv y -1 . While these results suggest that human health risks are small, additional testing should be conducted.

Glucose metabolism in cultured trophoblasts from human placenta

International Nuclear Information System (INIS)

Moe, A.J.; Farmer, D.R.; Nelson, D.M.; Smith, C.H.

1990-01-01

The development of appropriate placental trophoblast isolation and culture techniques enables the study of pathways of glucose utilization by this important cell layer in vitro. Trophoblasts from normal term placentas were isolated and cultured 24 hours and 72 hours in uncoated polystyrene culture tubes or tubes previously coated with a fibrin matrix. Trophoblasts cultured on fibrin are morphologically distinct from those cultured on plastic or other matrices and generally resemble in vivo syncytium. Cells were incubated up to 3 hours with 14 C-labeled glucose and reactions were stopped by addition of perchloric acid. 14 CO 2 production by trophoblasts increased linearly with time however the largest accumulation of label was in organic acids. Trophoblasts cultured in absence of fibrin utilized more glucose and accumulated more 14 C in metabolic products compared to cells cultured on fibrin. Glucose oxidation to CO 2 by the phosphogluconate (PG) pathway was estimated from specific yields of 14 CO 2 from [1- 14 C]-D-glucose and [6- 14 C]-D-glucose. Approximately 6% of glucose oxidation was by the PG pathway when cells were cultured on fibrin compared to approximately 1% by cells cultured in the absence of fibrin. The presence of a fibrin growth matrix appears to modulate the metabolism of glucose by trophoblast from human placenta in vitro

Discovery of ebselen as an inhibitor of Cryptosporidium parvum glucose-6-phosphate isomerase (CpGPI by high-throughput screening of existing drugs

Directory of Open Access Journals (Sweden)

Rana Eltahan

2018-04-01

Full Text Available Cryptosporidium parvum is a water-borne and food-borne apicomplexan pathogen. It is one of the top four diarrheal-causing pathogens in children under the age of five in developing countries, and an opportunistic pathogen in immunocompromised individuals. Unlike other apicomplexans, C. parvum lacks Kreb's cycle and cytochrome-based respiration, thus relying mainly on glycolysis to produce ATP. In this study, we characterized the primary biochemical features of the C. parvum glucose-6-phosphate isomerase (CpGPI and determined its Michaelis constant towards fructose-6-phosphate (Km = 0.309 mM, Vmax = 31.72 nmol/μg/min. We also discovered that ebselen, an organoselenium drug, was a selective inhibitor of CpGPI by high-throughput screening of 1200 known drugs. Ebselen acted on CpGPI as an allosteric noncompetitive inhibitor (IC50 = 8.33 μM; Ki = 36.33 μM, while complete inhibition of CpGPI activity was not achieved. Ebselen could also inhibit the growth of C. parvum in vitro (EC50 = 165 μM at concentrations nontoxic to host cells, albeit with a relatively small in vitro safety window of 4.2 (cytotoxicity TC50 on HCT-8 cells = 700 μM. Additionally, ebselen might also target other enzymes in the parasite, leading to the parasite growth reduction. Therefore, although ebselen is useful in studying the inhibition of CpGPI enzyme activity, further proof is needed to chemically and/or genetically validate CpGPI as a drug target. Keywords: Apicomplexan, Cryptosporidium parvum, Glucose-6-phosphate isomerase (GPI, Ebselen

Glucose modulates food-related salience coding of midbrain neurons in humans.

Science.gov (United States)

Ulrich, Martin; Endres, Felix; Kölle, Markus; Adolph, Oliver; Widenhorn-Müller, Katharina; Grön, Georg

2016-12-01

Although early rat studies demonstrated that administration of glucose diminishes dopaminergic midbrain activity, evidence in humans has been lacking so far. In the present functional magnetic resonance imaging study, glucose was intravenously infused in healthy human male participants while seeing images depicting low-caloric food (LC), high-caloric food (HC), and non-food (NF) during a food/NF discrimination task. Analysis of brain activation focused on the ventral tegmental area (VTA) as the origin of the mesolimbic system involved in salience coding. Under unmodulated fasting baseline conditions, VTA activation was greater during HC compared with LC food cues. Subsequent to infusion of glucose, this difference in VTA activation as a function of caloric load leveled off and even reversed. In a control group not receiving glucose, VTA activation during HC relative to LC cues remained stable throughout the course of the experiment. Similar treatment-specific patterns of brain activation were observed for the hypothalamus. The present findings show for the first time in humans that glucose infusion modulates salience coding mediated by the VTA. Hum Brain Mapp 37:4376-4384, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

2-O-α-D-glucosylglycerol phosphorylase from Bacillus selenitireducens MLS10 possessing hydrolytic activity on β-D-glucose 1-phosphate.

Directory of Open Access Journals (Sweden)

Takanori Nihira

Full Text Available The glycoside hydrolase family (GH 65 is a family of inverting phosphorylases that act on α-glucosides. A GH65 protein (Bsel_2816 from Bacillus selenitireducens MLS10 exhibited inorganic phosphate (Pi-dependent hydrolysis of kojibiose at the rate of 0.43 s(-1. No carbohydrate acted as acceptor for the reverse phosphorolysis using β-D-glucose 1-phosphate (βGlc1P as donor. During the search for a suitable acceptor, we found that Bsel_2816 possessed hydrolytic activity on βGlc1P with a k cat of 2.8 s(-1; moreover, such significant hydrolytic activity on sugar 1-phosphate had not been reported for any inverting phosphorylase. The H2 (18O incorporation experiment and the anomeric analysis during the hydrolysis of βGlc1P revealed that the hydrolysis was due to the glucosyl-transferring reaction to a water molecule and not a phosphatase-type reaction. Glycerol was found to be the best acceptor to generate 2-O-α-D-glucosylglycerol (GG at the rate of 180 s(-1. Bsel_2816 phosphorolyzed GG through sequential Bi-Bi mechanism with a k cat of 95 s(-1. We propose 2-O-α-D-glucopyranosylglycerol: phosphate β-D-glucosyltransferase as the systematic name and 2-O-α-D-glucosylglycerol phosphorylase as the short name for Bsel_2816. This is the first report describing a phosphorylase that utilizes polyols, and not carbohydrates, as suitable acceptor substrates.

In vivo 31P nuclear magnetic resonance saturation transfer measurements of phosphate exchange reactions in the yeast Saccharomyces cerevisiae

International Nuclear Information System (INIS)

Campbell, S.L.; Jones, K.A.; Schulman, R.G.

1985-01-01

31 P saturation transfer techniques have been used to measure phosphate kinetics in the yeast Saccharomyces cerevisiae. The phosphate comsumption rate observed in acetate grown mid-log cells was combined with measurements of O 2 consumption to yield P/O ratios of 2.2 and 2.9, for cells respiring on glucose and ethanol, respectively. However, no phosphate consumption activity was observed in saturation transfer experiments on anaerobic glucose fed cells. The phosphate consumption rates measured by saturation transfer in cells respiring on glucose and ethanol was attributed to the unidirectional rates of mitochondrial ATP synthesis. (Auth.)

Nuclear magnetic resonance studies of the regulation of the pentose phosphate pathway

Energy Technology Data Exchange (ETDEWEB)

Bolo, Nicolas Robin [Univ. of California, Berkeley, CA (United States)

1991-11-01

The goal of this work is to investigate the potential for and limitations of in vivo nuclear magnetic resonance (NMR) spectroscopy for quantitation of glucose flux through the pentose phosphate pathway (shunt). Interest in the shunt is motivated by the possibility that its activity may be greatly increased in cancer and in the pathological states of cardiac and cerebral ischemia. The ability to dynamically monitor flux through the pentose shunt can give new knowledge about metabolism in pathological states. ¹³C NMR spectroscopy was used to monitor shunt activity by determination of the ratios of [¹³C-4] to [¹³C-5]-glutamate, [¹³C-3] to [¹³C-2]-alanine or [¹³C-3] to [¹³C-2]-lactate produced when [¹³C-2]-glucose is infused. These methods provide measures of the effect of oxidative stresses on shunt activity in systems ranging from cell free enzyme-substrate preparations to cell suspensions and whole animals. In anaerobic cell free preparations, the fraction of glucose flux through the shunt was monitored with a time resolution of 3 minutes. This work predicts the potential for in vivo human studies of pentose phosphate pathway activity based on the mathematical simulation of the ¹³C fractional enrichments of C4 and C5-glutamate as a function of shunt activity and on the signal-to- noise ratio acquired in ¹³C NMR human studies from the current literature.

21 CFR 137.175 - Phosphated flour.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 2 2010-04-01 2010-04-01 false Phosphated flour. 137.175 Section 137.175 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN... Related Products § 137.175 Phosphated flour. Phosphated flour, phosphated white flour, and phosphated...

Bio-treatment of phosphate from synthetic wastewater using ...

African Journals Online (AJOL)

Michael Horsfall

effect of carbon sources (glucose, starch, sucrose and lactose) at 0.5% on the ... to be maximum of 68 % in synthetic phosphate wastewater with glucose carbon ... possible entry of this ion into aquatic environment is ... Therefore it is essential to control the emission of ... Mumbai, India) was prepared and selected bacterial.

Steady-state cerebral glucose concentrations and transport in the human brain

OpenAIRE

Gruetter, R.; Ugurbil, K.; Seaquist, E. R.

1998-01-01

Understanding the mechanism of brain glucose transport across the blood- brain barrier is of importance to understanding brain energy metabolism. The specific kinetics of glucose transport nave been generally described using standard Michaelis-Menten kinetics. These models predict that the steady- state glucose concentration approaches an upper limit in the human brain when the plasma glucose level is well above the Michaelis-Menten constant for half-maximal transport, K(t). In experiments wh...

Molecular association of glucose-6-phosphate isomerase and pyruvate kinase M2 with glyceraldehyde-3-phosphate dehydrogenase in cancer cells

International Nuclear Information System (INIS)

Das, Mahua R.; Bag, Arup K.; Saha, Shekhar; Ghosh, Alok; Dey, Sumit K.; Das, Provas; Mandal, Chitra; Ray, Subhankar; Chakrabarti, Saikat; Ray, Manju; Jana, Siddhartha S.

2016-01-01

For a long time cancer cells are known for increased uptake of glucose and its metabolization through glycolysis. Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is a key regulatory enzyme of this pathway and can produce ATP through oxidative level of phosphorylation. Previously, we reported that GAPDH purified from a variety of malignant tissues, but not from normal tissues, was strongly inactivated by a normal metabolite, methylglyoxal (MG). Molecular mechanism behind MG mediated GAPDH inhibition in cancer cells is not well understood. GAPDH was purified from Ehrlich ascites carcinoma (EAC) cells based on its enzymatic activity. GAPDH associated proteins in EAC cells and 3-methylcholanthrene (3MC) induced mouse tumor tissue were detected by mass spectrometry analysis and immunoprecipitation (IP) experiment, respectively. Interacting domains of GAPDH and its associated proteins were assessed by in silico molecular docking analysis. Mechanism of MG mediated GAPDH inactivation in cancer cells was evaluated by measuring enzyme activity, Circular dichroism (CD) spectroscopy, IP and mass spectrometry analyses. Here, we report that GAPDH is associated with glucose-6-phosphate isomerase (GPI) and pyruvate kinase M2 (PKM2) in Ehrlich ascites carcinoma (EAC) cells and also in 3-methylcholanthrene (3MC) induced mouse tumor tissue. Molecular docking analyses suggest C-terminal domain preference for the interaction between GAPDH and GPI. However, both C and N termini of PKM2 might be interacting with the C terminal domain of GAPDH. Expression of both PKM2 and GPI is increased in 3MC induced tumor compared with the normal tissue. In presence of 1 mM MG, association of GAPDH with PKM2 or GPI is not perturbed, but the enzymatic activity of GAPDH is reduced to 26.8 ± 5 % in 3MC induced tumor and 57.8 ± 2.3 % in EAC cells. Treatment of MG to purified GAPDH complex leads to glycation at R399 residue of PKM2 only, and changes the secondary structure of the protein complex. PKM2

Chemical modification of human muscle aldose reductase by pyridoxal 5'-phosphate

International Nuclear Information System (INIS)

Morjana, N.A.; Lyons, C.; Flynn, T.G.

1987-01-01

Aldose reductase (ALR2) is a monomeric oxidoreductase (Mr, 37,000). This enzyme catalyzes the reduction of a wide variety of aliphatic and aromatic aldehydes to their corresponding alcohols. The ability to reduce D-glucose and utilize NADH distinguishes ALR2 from aldehyde reductase (ALR1) which is exclusively NADPH-dependent. As part of a study to determine active site residues critical for binding and catalysis they have investigated the behavior of ALR2 with pyridoxal phosphate (PLP). In contrast to ALR1, which is inactivated by PLP, the reaction of ALR2 with PLP results in a 2-3 fold activation with the incorporation of 1 mol of PLP/mol enzyme. However, despite a 3-fold increase in k/sub cat/, there is also a 13-14 fold increase in the Km for both coenzyme and substrate and catalytic efficiency (k/sub cat//Km) is actually decreased. Reaction of ALR2 with 3 [H] PLP followed by digestion with endoproteinase Lys-C enabled the separation and purification by HPLC of a peptide containing a single pyridoxyllysine residue. The sequence of this 32 residue peptide is highly homologous with a peptide similarly obtained from pig and human ALR1 and is identical with one from pig ALR2. In all four enzymes, pig ALR1, ALR2; human ALR1, ALR2, a tetrapeptide containing the pyridoxylated lysine (I-P-K-S) shows absolute identity. Thus, despite differences in substrate and coenzyme specificity, the active site in both ALR1 and ALR2 is relatively conserved

An alpha-glucose-1-phosphate phosphodiesterase is present in rat liver cytosol

International Nuclear Information System (INIS)

Srisomsap, C.; Richardson, K.L.; Jay, J.C.; Marchase, R.B.

1989-01-01

UDP-glucose:glycoprotein glucose-1-phosphotransferase (Glc-phosphotransferase) catalyzes the transfer of alpha-Glc-1-P from UDP-Glc to mannose residues on acceptor glycoproteins. The predominant acceptor for this transfer in both mammalian cells and Paramecium is a cytoplasmic glycoprotein of 62-63 kDa. When cytoplasmic proteins from rat liver were fractionated by preparative isoelectric focusing following incubation of a liver homogenate with the 35S-labeled phosphorothioate analogue of UDP-Glc ([beta-35S]UDP-Glc), the acceptor was found to have a pI of about 6.0. This fraction, when not labeled prior to the focusing, became very heavily labeled when mixed with [beta-35S]. UDP-Glc and intact liver microsomes, a rich source of the Glc-phosphotransferase. In addition, it was observed that the isoelectric fractions of the cytosol having pI values of 2-3.2 contained a degradative activity, alpha-Glc-1-P phosphodiesterase, that was capable of removing alpha-Glc-1-P, monitored through radioactive labeling both in the sugar and the phosphate, as an intact unit from the 62-kDa acceptor. Identification of the product of this cleavage was substantiated by its partial transformation to UDP-Glc in the presence of UTP and UDP-Glc pyrophosphorylase. The alpha-Glc-1-P phosphodiesterase had a pH optimum of 7.5 and was not effectively inhibited by any of the potential biochemical inhibitors that were tested. Specificity for the Glc-alpha-1-P-6-Man diester was suggested by the diesterase's inability to degrade UDP-Glc or glucosylphosphoryldolichol. This enzyme may be important in the regulation of secretion since the alpha-Glc-1-P present on the 62-kDa phosphoglycoprotein appears to be removed and then rapidly replaced in response to secretagogue

Cloning and functional expression of a human pancreatic islet glucose-transporter cDNA

International Nuclear Information System (INIS)

Permutt, M.A.; Koranyi, L.; Keller, K.; Lacy, P.E.; Scharp, D.W.; Mueckler, M.

1989-01-01

Previous studies have suggested that pancreatic islet glucose transport is mediated by a high-K m , low-affinity facilitated transporter similar to that expressed in liver. To determine the relationship between islet and liver glucose transporters, liver-type glucose-transporter cDNA clones were isolated from a human liver cDNA library. The liver-type glucose-transporter cDNA clone hybridized to mRNA transcripts of the same size in human liver and pancreatic islet RNA. A cDNA library was prepared from purified human pancreatic islet tissue and screened with human liver-type glucose-transporter cDNA. The authors isolated two overlapping cDNA clones encompassing 2600 base pairs, which encode a pancreatic islet protein identical in sequence to that of the putative liver-type glucose-transporter protein. Xenopus oocytes injected with synthetic mRNA transcribed from a full-length cDNA construct exhibited increased uptake of 2-deoxyglucose, confirming the functional identity of the clone. These cDNA clones can now be used to study regulation of expression of the gene and to assess the role of inherited defects in this gene as a candidate for inherited susceptibility to non-insulin-dependent diabetes mellitus

Modulation of nuclear T3 binding by T3 in a human hepatocyte cell-line (Chang-liver) - T3 stimulation of cell growth but not of malic enzyme, glucose-6-phosphatdehydrogenase or 6-phosphogluconate-dehydrogenase

DEFF Research Database (Denmark)

Matzen, L E; Kristensen, S R; Kvetny, J

1991-01-01

The T3 modulation of nuclear T3 binding (NBT3), the T3 effect on cell growth, and the T3 and insulin effects on malic enzyme (ME), glucose-6-phosphat-dehydrogenase (G6PD) and 6-phosphogluconat-dehydrogenase (G6PD) were studied in a human hepatocyte cell-line (Chang-liver). T3 was bound to a high ...

Sustained high plasma mannose less sensitive to fluctuating blood glucose in glycogen storage disease type Ia children

NARCIS (Netherlands)

Nagasaka, Hironori; Yorifuji, Tohru; Bandsma, Robert H. J.; Takatani, Tomozumi; Asano, Hisaki; Mochizuki, Hiroshi; Takuwa, Mayuko; Tsukahara, Hirokazu; Inui, Ayano; Tsunoda, Tomoyuki; Komatsu, Haruki; Hiejima, Eitaro; Fujisawa, Tomoo; Hirano, Ken-ichi; Miida, Takashi; Ohtake, Akira; Taguchi, Tadao; Miwa, Ichitomo

Plasma mannose is suggested to be largely generated from liver glycogen-oriented glucose-6-phosphate. This study examined plasma mannose in glycogen storage disease type Ia (GSD Ia) lacking conversion of glucose-6-phosphate to glucose in the liver. We initially examined fasting-and postprandial 2

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...

Probing the metabolic network in bloodstream-form Trypanosoma brucei using untargeted metabolomics with stable isotope labelled glucose.

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Darren J Creek

2015-03-01

Full Text Available Metabolomics coupled with heavy-atom isotope-labelled glucose has been used to probe the metabolic pathways active in cultured bloodstream form trypomastigotes of Trypanosoma brucei, a parasite responsible for human African trypanosomiasis. Glucose enters many branches of metabolism beyond glycolysis, which has been widely held to be the sole route of glucose metabolism. Whilst pyruvate is the major end-product of glucose catabolism, its transamination product, alanine, is also produced in significant quantities. The oxidative branch of the pentose phosphate pathway is operative, although the non-oxidative branch is not. Ribose 5-phosphate generated through this pathway distributes widely into nucleotide synthesis and other branches of metabolism. Acetate, derived from glucose, is found associated with a range of acetylated amino acids and, to a lesser extent, fatty acids; while labelled glycerol is found in many glycerophospholipids. Glucose also enters inositol and several sugar nucleotides that serve as precursors to macromolecule biosynthesis. Although a Krebs cycle is not operative, malate, fumarate and succinate, primarily labelled in three carbons, were present, indicating an origin from phosphoenolpyruvate via oxaloacetate. Interestingly, the enzyme responsible for conversion of phosphoenolpyruvate to oxaloacetate, phosphoenolpyruvate carboxykinase, was shown to be essential to the bloodstream form trypanosomes, as demonstrated by the lethal phenotype induced by RNAi-mediated downregulation of its expression. In addition, glucose derivatives enter pyrimidine biosynthesis via oxaloacetate as a precursor to aspartate and orotate.

High Glucose-Induced Oxidative Stress Increases the Copy Number of Mitochondrial DNA in Human Mesangial Cells

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Ghada Al-Kafaji

2013-01-01

Full Text Available Oxidative damage to mitochondrial DNA (mtDNA has been linked to the pathogenicity of diabetic nephropathy. We tested the hypothesis that mtDNA copy number may be increased in human mesangial cells in response to high glucose-induced reactive oxygen species (ROS to compensate for damaged mtDNA. The effect of manganese superoxide dismutase mimetic (MnTBAP on glucose-induced mtDNA copy number was also examined. The copy number of mtDNA was determined by real-time PCR in human mesangial cells cultured in 5 mM glucose, 25 mM glucose, and mannitol (osmotic control, as well as in cells cultured in 25 mM glucose in the presence and absence of 200 μM MnTBAP. Intracellular ROS was assessed by confocal microscopy and flow cytometry in human mesangial cells. The copy number of mtDNA was significantly increased when human mesangial cells were incubated with 25 mM glucose compared to 5 mM glucose and mannitol. In addition, 25 mM glucose rapidly generated ROS in the cells, which was not detected in 5 mM glucose. Furthermore, mtDNA copy number was significantly decreased and maintained to normal following treatment of cells with 25 mM glucose and MnTBAP compared to 25 mM glucose alone. Inclusion of MnTBAP during 25 mM glucose incubation inhibited mitochondrial superoxide in human mesangial cells. Increased mtDNA copy number in human mesangial cells by high glucose could contribute to increased mitochondrial superoxide, and prevention of mtDNA copy number could have potential in retarding the development of diabetic nephropathy.

Noninvasive measurement of glucose concentration on human fingertip by optical coherence tomography

Science.gov (United States)

Chen, Tseng-Lin; Lo, Yu-Lung; Liao, Chia-Chi; Phan, Quoc-Hung

2018-04-01

A method is proposed for determining the glucose concentration on the human fingertip by extracting two optical parameters, namely the optical rotation angle and the depolarization index, using a Mueller optical coherence tomography technique and a genetic algorithm. The feasibility of the proposed method is demonstrated by measuring the optical rotation angle and depolarization index of aqueous glucose solutions with low and high scattering, respectively. It is shown that for both solutions, the optical rotation angle and depolarization index vary approximately linearly with the glucose concentration. As a result, the ability of the proposed method to obtain the glucose concentration by means of just two optical parameters is confirmed. The practical applicability of the proposed technique is demonstrated by measuring the optical rotation angle and depolarization index on the human fingertip of healthy volunteers under various glucose conditions.

Pentose pathway in human liver

International Nuclear Information System (INIS)

Magnusson, I.; Chandramouli, V.; Schumann, W.C.; Kumaran, K.; Wahren, J.; Landau, B.R.

1988-01-01

[1- 14 C]Ribose and [1- 14 C]glucose were given to normal subjects along with glucose loads (1 g per kg of body weight) after administration of diflunisal and acetaminophen, drugs that are excreted in urine as glucuronides. Distributions of 14 C were determined in the carbons of the excreted glucoronides and in the glucose from blood samples drawn from hepatic veins before and after glucagon administration. Eighty percent or more of the 14 C from [1- 14 C]ribose incorporated into the glucuronic acid moiety of the glucuronides was in carbons 1 and 3, with less than 8% in carbon 2. In glucuronic acid from glucuronide excreted when [2- 14 C]glucose was given, 3.5-8.1% of the 14 C was in carbon 1, 2.5-4.3% in carbon 3, and more than 70% in carbon 2. These distributions are in accord with the glucuronides sampling the glucose unit of the glucose 6-phosphate pool that is a component of the pentose pathway and is intermediate in glycogen formation. It is concluded that the glucuronic acid conjugates of the drugs can serve as a noninvasive means of sampling hepatic glucose 6-phosphate. In human liver, as in animal liver, the classical pentose pathway functions, not the L-type pathway, and only a small percentage of the glucose is metabolized via the pathway

Incorporation of phosphate into glycogen by glycogen synthase.

Science.gov (United States)

Contreras, Christopher J; Segvich, Dyann M; Mahalingan, Krishna; Chikwana, Vimbai M; Kirley, Terence L; Hurley, Thomas D; DePaoli-Roach, Anna A; Roach, Peter J

2016-05-01

The storage polymer glycogen normally contains small amounts of covalently attached phosphate as phosphomonoesters at C2, C3 and C6 atoms of glucose residues. In the absence of the laforin phosphatase, as in the rare childhood epilepsy Lafora disease, the phosphorylation level is elevated and is associated with abnormal glycogen structure that contributes to the pathology. Laforin therefore likely functions in vivo as a glycogen phosphatase. The mechanism of glycogen phosphorylation is less well-understood. We have reported that glycogen synthase incorporates phosphate into glycogen via a rare side reaction in which glucose-phosphate rather than glucose is transferred to a growing polyglucose chain (Tagliabracci et al. (2011) Cell Metab13, 274-282). We proposed a mechanism to account for phosphorylation at C2 and possibly at C3. Our results have since been challenged (Nitschke et al. (2013) Cell Metab17, 756-767). Here we extend the evidence supporting our conclusion, validating the assay used for the detection of glycogen phosphorylation, measurement of the transfer of (32)P from [β-(32)P]UDP-glucose to glycogen by glycogen synthase. The (32)P associated with the glycogen fraction was stable to ethanol precipitation, SDS-PAGE and gel filtration on Sephadex G50. The (32)P-signal was not affected by inclusion of excess unlabeled UDP before analysis or by treatment with a UDPase, arguing against the signal being due to contaminating [β-(32)P]UDP generated in the reaction. Furthermore, [(32)P]UDP did not bind non-covalently to glycogen. The (32)P associated with glycogen was released by laforin treatment, suggesting that it was present as a phosphomonoester. The conclusion is that glycogen synthase can mediate the introduction of phosphate into glycogen, thereby providing a possible mechanism for C2, and perhaps C3, phosphorylation. Copyright © 2016 Elsevier Inc. All rights reserved.

Glucose metabolism and recycling by hepatocytes of OB/OB and ob/ob mice

International Nuclear Information System (INIS)

Lahtela, J.T.; Wals, P.A.; Katz, J.

1990-01-01

Hepatocytes were prepared from livers of ob/ob (obese diabetic) mice and their lean (OB/OB) siblings that had been fasted for 24 h. The hepatocytes were incubated with [U-14C, 2-3H]-, [U-14C, 3-3H]-, and [U-14C, 6-3H]glucose at concentrations from 20 to 120 mM. 14C was recovered mainly in CO2, glycogen, and lactate. Tritium was recovered in water and glycogen. The yield in labeled products from [2-3H]glucose ranged from two to three times that from [U-14C]glucose. The yields from [3-3H]- and [6-3H]glucose were similar, and 1.3-1.7 times that from [U-14C]glucose. At 40 mM, total utilization of glucose by obese mice was about twice that for lean mice, but there was little difference at 120 mM. The rate of recycling between glucose and glucose 6-phosphate was calculated. An equation to calculate the rate of recycling of glucose from the 2-3H/U-14C ratio in glycogen is derived in the APPENDIX. Our results show that (1) the utilization of glucose by hepatocytes from obese diabetic mice exceeds that of their lean controls, (2) the rate of glucose phosphorylation in both groups greatly exceeds glucose uptake and the rate of glycogen synthesis, (3) glucose phosphorylation represents a difference between a high glucokinase rate and hydrolysis of glucose 6-phosphate, and (4) recycling of glucose carbon between glucose 6-phosphate and pyruvate occurs within mouse hepatocytes

EFFECTS OF PARTIAL HEPATECTOMY, PHENOBARBITAL AND 3-METHYLCHOLANTHRENE ON KINETIC-PARAMETERS OF GLUCOSE-6-PHOSPHATE AND PHOSPHOGLUCONATE DEHYDROGENASE IN-SITU IN PERIPORTAL, INTERMEDIATE AND PERICENTRAL ZONES OF RAT-LIVER LOBULES

NARCIS (Netherlands)

Jonges, G. N.; Vogels, I. M. C.; van Noorden, C. J. F.

1995-01-01

Glucose-6-phosphate dehydrogenase (G6PDH) and phosphogluconate dehydrogenase (PGDH) are heterogeneously distributed in liver lobules of female rats. The maximum activity of both enzymes is approximately twice higher in intermediate and pericentral zones than in periportal zones. Enzyme activities

Isotope effects in the non enzymic glucation of hemoglobin catalyzed by phosphate

International Nuclear Information System (INIS)

Gil, H.; Mata-Segreda, J.; Schowen, R.

1991-01-01

The reaction of hemoglobin, mainly at the N-terminal valine, with glucose exhibits identical rates in protium and deuterium oxides, both for the buffer-independent rate and for the first-order rate in phosphate buffer. Under the conditions employed, imine formation is relatively rapid and events in the course of the Amadori rearrangement must limit the rate. A very-slow, phosphate-induced reorganization of hemoglobin-glucose imine may be the most likely candidate for the rate-limiting step. (author)

Hypoxia-induced glucose-6-phosphate dehydrogenase overexpression and -activation in pulmonary artery smooth muscle cells: implication in pulmonary hypertension

Science.gov (United States)

Chettimada, Sukrutha; Gupte, Rakhee; Rawat, Dhwajbahadur; Gebb, Sarah A.; McMurtry, Ivan F.

2014-01-01

Severe pulmonary hypertension is a debilitating disease with an alarmingly low 5-yr life expectancy. Hypoxia, one of the causes of pulmonary hypertension, elicits constriction and remodeling of the pulmonary arteries. We now know that pulmonary arterial remodeling is a consequence of hyperplasia and hypertrophy of pulmonary artery smooth muscle (PASM), endothelial, myofibroblast, and stem cells. However, our knowledge about the mechanisms that cause these cells to proliferate and hypertrophy in response to hypoxic stimuli is still incomplete, and, hence, the treatment for severe pulmonary arterial hypertension is inadequate. Here we demonstrate that the activity and expression of glucose-6-phosphate dehydrogenase (G6PD), the rate-limiting enzyme of the pentose phosphate pathway, are increased in hypoxic PASM cells and in lungs of chronic hypoxic rats. G6PD overexpression and -activation is stimulated by H2O2. Increased G6PD activity contributes to PASM cell proliferation by increasing Sp1 and hypoxia-inducible factor 1α (HIF-1α), which directs the cells to synthesize less contractile (myocardin and SM22α) and more proliferative (cyclin A and phospho-histone H3) proteins. G6PD inhibition with dehydroepiandrosterone increased myocardin expression in remodeled pulmonary arteries of moderate and severe pulmonary hypertensive rats. These observations suggest that altered glucose metabolism and G6PD overactivation play a key role in switching the PASM cells from the contractile to synthetic phenotype by increasing Sp1 and HIF-1α, which suppresses myocardin, a key cofactor that maintains smooth muscle cell in contractile state, and increasing hypoxia-induced PASM cell growth, and hence contribute to pulmonary arterial remodeling and pathogenesis of pulmonary hypertension. PMID:25480333

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.

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.

Peculiarities of glucose and glycerol metabolism in Nocardia vaccinii IMB B-7405

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T. P. Pirog

2015-04-01

Full Text Available It has been established that in cells of Nocardia vaccinii IMB B-7405 (surfactant producer glucose catabolism is performed through pentose phosphate cycle as well as through gluconate (activi­ty of NAD+-dependent glucose-6- phosphate dehydrogenase and FAD+-dependent glucose dehydrogenase 835 ± 41 and 698 ± 35 nmol∙min-1∙mg-1 of protein respectively. 6-Phosphogluconate formed in the gluconokinase reaction is involved in the pentose phosphate cycle (activity of constitutive NADP+-dependent 6-phosphogluconate dehydrogenase 357 ± 17 nmol∙min-1∙mg-1 of protein. Glyce­rol catabolism to dihydroxyacetonephosphate (the intermediate of glycolysis may be performed in two ways: through glycerol-3-phosphate (glycerol kinase activity 244 ± 12 nmol∙min-1∙mg-1 of protein and through dihydroxyacetone. Replenishment of the C4-dicarboxylic acids pool in N. vaccinii IMV B-7405 grown on glucose and glycerol occurs in the phosphoenolpyruvate(PEPcarboxylase reaction (714–803 nmol∙min-1∙mg-1 of protein. 2-Oxoglutara­te was involved in tricarboxylic acid cycle by alternate pathway with the participation of 2-oxoglutarate synthase. The observed activity of both key enzymes of gluconeogenesis (PEP- carboxykinase and PEP-synthase, trehalose phosphate synthase and NADP+-dependent glutamate dehydrogenase confirmed the ability of IMV B-7405 strain to the synthesis of surface active glyco- and aminolipids, respectively.

Gibbs Free-Energy Gradient along the Path of Glucose Transport through Human Glucose Transporter 3.

Science.gov (United States)

Liang, Huiyun; Bourdon, Allen K; Chen, Liao Y; Phelix, Clyde F; Perry, George

2018-06-11

Fourteen glucose transporters (GLUTs) play essential roles in human physiology by facilitating glucose diffusion across the cell membrane. Due to its central role in the energy metabolism of the central nervous system, GLUT3 has been thoroughly investigated. However, the Gibbs free-energy gradient (what drives the facilitated diffusion of glucose) has not been mapped out along the transport path. Some fundamental questions remain. Here we present a molecular dynamics study of GLUT3 embedded in a lipid bilayer to quantify the free-energy profile along the entire transport path of attracting a β-d-glucose from the interstitium to the inside of GLUT3 and, from there, releasing it to the cytoplasm by Arrhenius thermal activation. From the free-energy profile, we elucidate the unique Michaelis-Menten characteristics of GLUT3, low K M and high V MAX , specifically suitable for neurons' high and constant demand of energy from their low-glucose environments. We compute GLUT3's binding free energy for β-d-glucose to be -4.6 kcal/mol in agreement with the experimental value of -4.4 kcal/mol ( K M = 1.4 mM). We also compute the hydration energy of β-d-glucose, -18.0 kcal/mol vs the experimental data, -17.8 kcal/mol. In this, we establish a dynamics-based connection from GLUT3's crystal structure to its cellular thermodynamics with quantitative accuracy. We predict equal Arrhenius barriers for glucose uptake and efflux through GLUT3 to be tested in future experiments.

Detection of transketolase in bone marrow-derived insulin-producing cells: benfotiamine enhances insulin synthesis and glucose metabolism.

Science.gov (United States)

Oh, Seh-Hoon; Witek, Rafal P; Bae, Si-Hyun; Darwiche, Houda; Jung, Youngmi; Pi, Liya; Brown, Alicia; Petersen, Bryon E

2009-01-01

Adult bone marrow (BM)-derived insulin-producing cells (IPCs) are capable of regulating blood glucose levels in chemically induced hyperglycemic mice. Using cell transplantation therapy, fully functional BM-derived IPCs help to mediate treatment of diabetes mellitus. Here, we demonstrate the detection of the pentose phosphate pathway enzyme, transketolase (TK), in BM-derived IPCs cultured under high-glucose conditions. Benfotiamine, a known activator of TK, was not shown to affect the proliferation of insulinoma cell line, INS-1; however, when INS-1 cells were cultured with oxythiamine, an inhibitor of TK, cell proliferation was suppressed. Treatment with benfotiamine activated glucose metabolism in INS-1 cells in high-glucose culture conditions, and appeared to maximize the BM-derived IPCs ability to synthesize insulin. Benfotiamine was not shown to induce the glucose receptor Glut-2, however it was shown to activate glucokinase, the enzyme responsible for conversion of glucose to glucose-6-phosphate. Furthermore, benfotiamine-treated groups showed upregulation of the downstream glycolytic enzyme, glyceraldehyde phosphate dehydrogenase (GAPDH). However, in cells where the pentose phosphate pathway was blocked by oxythiamine treatment, there was a clear downregulation of Glut-2, glucokinase, insulin, and GAPDH. When benfotiamine was used to treat mice transplanted with BM-derived IPCs transplanted, their glucose level was brought to a normal range. The glucose challenge of normal mice treated with benfotiamine lead to rapidly normalized blood glucose levels. These results indicate that benfotiamine activates glucose metabolism and insulin synthesis to prevent glucose toxicity caused by high concentrations of blood glucose in diabetes mellitus.

Detection of Transketolase in Bone Marrow—Derived Insulin-Producing Cells: Benfotiamine Enhances Insulin Synthesis and Glucose Metabolism

Science.gov (United States)

Witek, Rafal P.; Bae, Si-Hyun; Darwiche, Houda; Jung, Youngmi; Pi, Liya; Brown, Alicia; Petersen, Bryon E.

2009-01-01

Adult bone marrow (BM)-derived insulin-producing cells (IPCs) are capable of regulating blood glucose levels in chemically induced hyperglycemic mice. Using cell transplantation therapy, fully functional BM-derived IPCs help to mediate treatment of diabetes mellitus. Here, we demonstrate the detection of the pentose phosphate pathway enzyme, transketolase (TK), in BM-derived IPCs cultured under high-glucose conditions. Benfotiamine, a known activator of TK, was not shown to affect the proliferation of insulinoma cell line, INS-1; however, when INS-1 cells were cultured with oxythiamine, an inhibitor of TK, cell proliferation was suppressed. Treatment with benfotiamine activated glucose metabolism in INS-1 cells in high-glucose culture conditions, and appeared to maximize the BM-derived IPCs ability to synthesize insulin. Benfotiamine was not shown to induce the glucose receptor Glut-2, however it was shown to activate glucokinase, the enzyme responsible for conversion of glucose to glucose-6-phosphate. Furthermore, benfotiamine-treated groups showed upregulation of the downstream glycolytic enzyme, glyceraldehyde phosphate dehydrogenase (GAPDH). However, in cells where the pentose phosphate pathway was blocked by oxythiamine treatment, there was a clear downregulation of Glut-2, glucokinase, insulin, and GAPDH. When benfotiamine was used to treat mice transplanted with BM-derived IPCs transplanted, their glucose level was brought to a normal range. The glucose challenge of normal mice treated with benfotiamine lead to rapidly normalized blood glucose levels. These results indicate that benfotiamine activates glucose metabolism and insulin synthesis to prevent glucose toxicity caused by high concentrations of blood glucose in diabetes mellitus. PMID:18393672

Brain glucose metabolism in an animal model of depression.

Science.gov (United States)

Detka, J; Kurek, A; Kucharczyk, M; Głombik, K; Basta-Kaim, A; Kubera, M; Lasoń, W; Budziszewska, B

2015-06-04

An increasing number of data support the involvement of disturbances in glucose metabolism in the pathogenesis of depression. We previously reported that glucose and glycogen concentrations in brain structures important for depression are higher in a prenatal stress model of depression when compared with control animals. A marked rise in the concentrations of these carbohydrates and glucose transporters were evident in prenatally stressed animals subjected to acute stress and glucose loading in adulthood. To determine whether elevated levels of brain glucose are associated with a change in its metabolism in this model, we assessed key glycolytic enzymes (hexokinase, phosphofructokinase and pyruvate kinase), products of glycolysis, i.e., pyruvate and lactate, and two selected enzymes of the tricarboxylic acid cycle (pyruvate dehydrogenase and α-ketoglutarate dehydrogenase) in the hippocampus and frontal cortex. Additionally, we assessed glucose-6-phosphate dehydrogenase activity, a key enzyme in the pentose phosphate pathway (PPP). Prenatal stress increased the levels of phosphofructokinase, an important glycolytic enzyme, in the hippocampus and frontal cortex. However, prenatal stress had no effect on hexokinase or pyruvate kinase levels. The lactate concentration was elevated in prenatally stressed rats in the frontal cortex, and pyruvate levels remained unchanged. Among the tricarboxylic acid cycle enzymes, prenatal stress decreased the level of pyruvate dehydrogenase in the hippocampus, but it had no effect on α-ketoglutarate dehydrogenase. Like in the case of glucose and its transporters, also in the present study, differences in markers of glucose metabolism between control animals and those subjected to prenatal stress were not observed under basal conditions but in rats subjected to acute stress and glucose load in adulthood. Glucose-6-phosphate dehydrogenase activity was not reduced by prenatal stress but was found to be even higher in animals exposed to

Lipolytic response to glucose infusion in human subjects

International Nuclear Information System (INIS)

Wolfe, R.R.; Peters, E.J.

1987-01-01

The authors have determined the effect of various rates of glucose infusion on the rates of release of glycerol (R/sub a/ glycerol), free fatty acids (R/sub a/ FFA), and on energy metabolism in normal human volunteers. Plasma kinetics were determined with use of the stable isotopic tracers D-5-glycerol and [1- 13 C]palmitate, and energy metabolism was determined by indirect calorimetry. The effect of glucose infusion on R/sub a/ glycerol and R/sub a/ FFA was dose-dependent. At 4 mg x kg -1 x min -1 , both R/sub a/ glycerol and R/sub a/ FFA were suppressed; at 8 mg x kg -1 x min -1 , R/sub a/ FFA was even more depressed, but R/sub a/ glycerol was similar to the value during the 4 mg x kg -1 x min -1 infusion. At all infusion rates tested, the amount of potential energy available from the sum of the glucose infusion and endogenously mobilized fat was always greater than when no glucose was infused. Glucose decreased fat mobilization by both inhibiting lipolysis and stimulating reesterification, thus causing a significant increase in triglyceride-fatty acid substrate cycling within the adipose tissue. Plasma insulin was determined by radioimmunoassay

Red blood cell aging markers during storage in citrate-phosphate-dextrose-saline-adenine-glucose-mannitol.

Science.gov (United States)

Antonelou, Marianna H; Kriebardis, Anastasios G; Stamoulis, Konstantinos E; Economou-Petersen, Effrosini; Margaritis, Lukas H; Papassideri, Issidora S

2010-02-01

It has been suggested that red blood cell (RBC) senescence is accelerated under blood bank conditions, although neither protein profile of RBC aging nor the impact of additive solutions on it have been studied in detail. RBCs and vesicles derived from RBCs in both citrate-phosphate-dextrose (CPD)-saline-adenine-glucose-mannitol (SAGM) and citrate-phosphate-dextrose-adenine (CPDA) were evaluated for the expression of cell senescence markers (vesiculation, protein aggregation, degradation, activation, oxidation, and topology) through immunoblotting technique and immunofluorescence or immunoelectron microscopy study. A group of cellular stress proteins exhibited storage time- and storage medium-related changes in their membrane association and exocytosis. The extent, the rate, and the expression of protein oxidation, Fas oligomerization, caspase activation, and protein modifications in Band 3, hemoglobin, and immunoglobulin G were less conspicuous and/or exhibited significant time retardation under storage in CPD-SAGM, compared to the CPDA storage. There was evidence for the localization of activated caspases near to the membrane of both cells and vesicles. We provide circumstantial evidence for a lower protein oxidative damage in CPD-SAGM-stored RBCs compared to the CPDA-stored cells. The different expression patterns of the senescence markers in the RBCs seem to be accordingly related to the oxidative stress management of the cells. We suggest that the storage of RBCs in CPD-SAGM might be more alike the in vivo RBC aging process, compared to storage in CPDA, since it is characterized by a slower stimulation of the recognition signaling pathways that are already known to trigger the erythrophagocytosis of senescent RBCs.

Neonatal screening for sickle cell disease, Glucose-6-PhosphateDehydrogenase deficiency and Alpha-Thalassemia in Qatif and Al-Hasa

International Nuclear Information System (INIS)

Nasserullah, Z.; Srair, Hussain Abu; Al-Jame, A.; Mokhtar, M.; Al-Qatari, G.; Al-Naim, S.; Al-Aqib, A.

1998-01-01

Screening programs to determine the frequency of sickle cell,glucose-6-phosphate dehydrogenase deficiency and alpha-thalassemia gene areavailable in Saudi Arabia, although not used frequently. Greater use of theseprograms will decrease the morbidity and mortality of Saudi children affectedby these disorders. Neonatal hemoglobin electrophoresis andglucose-6-dehydrogenase fluorescent spot tests were performed on new bornbabies delivered between December 1992 and December 1993 at the Qatif CentralHospital and at the King Fahd Hospital in Al-Hasa. Cord blood samples werecollected from babies born in these two hospitals. Babies born in otherhospitals had blood collected in their first visit to Qatif primary carecenters at the time of vaccination. All specimens were sent to Dammam CentralLaboratory. The diagnosis of sickle cell and alpha-thalassemia was based oncellulose acetate electrophoresis and confirmed by agar gel electrophoresisand glucose-6-phosphate dehydrgenase was confirmed by fluorescent spot test.A total of 12,220 infants, including 11,313 Saudis (92.6%), were screenedover a 12-month period. The common phenotype detected in these infantsincluded AF, SFA, SFA Bart's, FS and FS Bart's. In Saudi infants, homozygoussickle cell disease was detected in 2.35% and 1.08% in Qatif and Al-Hasa,respectively. The frequencies of sickle cell gene were 0.1545% and 0.1109% inQatif and Al-Hasa. Alpha-thalassemia genes based on an elevated level of HbBart's were 28% and 16.3% in Qatif and Al-Hasa. The screening for G6PDdeficiency revealed a high prevalence of 30.6% and 14.7% in Qatif andAl-Hasa. In the non-Saudi infants the frequencies were low. The outcome ofthis study indicates that the Saudi populations in Qatif and Al-Hasa are atrisk for hemoglobinopathies and G6PD. Neonatal screening programs areessential and cost effective and should be maintained as a routine practice.(author)

Effect of various parameters on the efficiency of zinc phosphate ...

African Journals Online (AJOL)

... and CMG852 showed enhanced solubilization in presence of 1% sodium chloride. 1% glucose is required for the solubilization of zinc phosphate and no solubilization was appeared in presence of 0.1% glucose. CMG851 (A. lwoffi), CMG 860 (pseudomonas aeruginosa) CMG 857 (Bacillus thuringiensis) were found to be ...

Human monoclonal antibodies against glucagon receptor improve glucose homeostasis by suppression of hepatic glucose output in diet-induced obese mice.

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Wook-Dong Kim

Full Text Available AIM: Glucagon is an essential regulator of hepatic glucose production (HGP, which provides an alternative therapeutic target for managing type 2 diabetes with glucagon antagonists. We studied the effect of a novel human monoclonal antibody against glucagon receptor (GCGR, NPB112, on glucose homeostasis in diet-induced obese (DIO mice. METHODS: The glucose-lowering efficacy and safety of NPB112 were investigated in DIO mice with human GCGR for 11 weeks, and a hyperinsulinemic-euglycemic clamp study was conducted to measure HGP. RESULTS: Single intraperitoneal injection of NPB112 with 5 mg/kg effectively decreased blood glucose levels in DIO mice for 5 days. A significant reduction in blood glucose was observed in DIO mice treated with NPB112 at a dose ≥5 mg/kg for 6 weeks, and its glucose-lowering effect was dose-dependent. Long-term administration of NPB112 also caused a mild 29% elevation in glucagon level, which was returned to the normal range after discontinuation of treatment. The clamp study showed that DIO mice injected with NPB112 at 5 mg/kg were more insulin sensitive than control mice, indicating amelioration of insulin resistance by treatment with NPB112. DIO mice treated with NPB112 showed a significant improvement in the ability of insulin to suppress HGP, showing a 33% suppression (from 8.3 mg/kg/min to 5.6 mg/kg/min compared to the 2% suppression (from 9.8 mg/kg/min to 9.6 mg/kg/min in control mice. In addition, no hypoglycemia or adverse effect was observed during the treatment. CONCLUSIONS: A novel human monoclonal GCGR antibody, NPB112, effectively lowered the glucose level in diabetic animal models with mild and reversible hyperglucagonemia. Suppression of excess HGP with NPB112 may be a promising therapeutic modality for the treatment of type 2 diabetes.

Molecular Dynamics Simulations of the Human Glucose Transporter GLUT1.

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Min-Sun Park

Full Text Available Glucose transporters (GLUTs provide a pathway for glucose transport across membranes. Human GLUTs are implicated in devastating diseases such as heart disease, hyper- and hypo-glycemia, type 2 diabetes and cancer. The human GLUT1 has been recently crystalized in the inward-facing open conformation. However, there is no other structural information for other conformations. The X-ray structures of E. coli Xylose permease (XylE, a glucose transporter homolog, are available in multiple conformations with and without the substrates D-xylose and D-glucose. XylE has high sequence homology to human GLUT1 and key residues in the sugar-binding pocket are conserved. Here we construct a homology model for human GLUT1 based on the available XylE crystal structure in the partially occluded outward-facing conformation. A long unbiased all atom molecular dynamics simulation starting from the model can capture a new fully opened outward-facing conformation. Our investigation of molecular interactions at the interface between the transmembrane (TM domains and the intracellular helices (ICH domain in the outward- and inward-facing conformation supports that the ICH domain likely stabilizes the outward-facing conformation in GLUT1. Furthermore, inducing a conformational transition, our simulations manifest a global asymmetric rocker switch motion and detailed molecular interactions between the substrate and residues through the water-filled selective pore along a pathway from the extracellular to the intracellular side. The results presented here are consistent with previously published biochemical, mutagenesis and functional studies. Together, this study shed light on the structure and functional relationships of GLUT1 in multiple conformational states.

Calculation of the pentose phosphate and Embden-Myerhoff pathways from a single incubation with [U-14C]- and [5-3H]glucose

International Nuclear Information System (INIS)

O'Fallon, J.V.; Wright, R.W. Jr.

1987-01-01

A method that simultaneously determines Embden-Myerhoff pathway and pentose phosphate pathway (PPP) activities from an incubation with [U- 14 C]- and [5- 3 H]glucose is presented. The method relies on the use of unlabeled pyruvate and lactate to dilute out radiolabel entering the tricarboxylic acid cycle. Gluconeogenesis from pyruvate is prevented by the use of an incubation chamber that maintains a CO 2 (and bicarbonate) free environment. The method, which includes the contribution by the recycling steps of the PPP, is especially useful when biological material is limited or developmental timing is critical

Effect of buspirone: An anxiolytic drug on blood glucose in humans

OpenAIRE

Ojha, S. K.; Nandave, M.; Sharma, C.

2006-01-01

The present study investigated the effect of an antianxiety drug, buspirone on blood glucose and plasma insulin level concerning the role of 5-HT1A receptors in blood glucose regulation in healthy humans. Twelve healthy male volunteers were administered single oral doses of buspirone (10 mg) or placebo, in a randomized, crossover way, followed by oral glucose load (75 gm in 200 ml) at reported Tmax i.e. the time of peak plasma concentration of the respective administered drug. The blood sampl...

Radiometric assays for glycerol, glucose, and glycogen

International Nuclear Information System (INIS)

Bradley, D.C.; Kaslow, H.R.

1989-01-01

We have developed radiometric assays for small quantities of glycerol, glucose and glycogen, based on a technique described by Thorner and Paulus for the measurement of glycerokinase activity. In the glycerol assay, glycerol is phosphorylated with [32P]ATP and glycerokinase, residual [32P]ATP is hydrolyzed by heating in acid, and free [32P]phosphate is removed by precipitation with ammonium molybdate and triethylamine. Standard dose-response curves were linear from 50 to 3000 pmol glycerol with less than 3% SD in triplicate measurements. Of the substances tested for interference, only dihydroxyacetone gave a slight false positive signal at high concentration. When used to measure glycerol concentrations in serum and in media from incubated adipose tissue, the radiometric glycerol assay correlated well with a commonly used spectrophotometric assay. The radiometric glucose assay is similar to the glycerol assay, except that glucokinase is used instead of glycerokinase. Dose response was linear from 5 to 3000 pmol glucose with less than 3% SD in triplicate measurements. Glucosamine and N-acetylglucosamine gave false positive signals when equimolar to glucose. When glucose concentrations in serum were measured, the radiometric glucose assay agreed well with hexokinase/glucose-6-phosphate dehydrogenase (H/GDH)-based and glucose oxidase/H2O2-based glucose assays. The radiometric method for glycogen measurement incorporates previously described isolation and digestion techniques, followed by the radiometric assay of free glucose. When used to measure glycogen in mouse epididymal fat pads, the radiometric glycogen assay correlated well with the H/GDH-based glycogen assay. All three radiometric assays offer several practical advantages over spectral assays

Negative Effects of High Glucose Exposure in Human Gonadotropin-Releasing Hormone Neurons

OpenAIRE

Morelli, Annamaria; Comeglio, Paolo; Sarchielli, Erica; Cellai, Ilaria; Vignozzi, Linda; Vannelli, Gabriella B.; Maggi, Mario

2013-01-01

Metabolic disorders are often associated with male hypogonadotropic hypogonadism, suggesting that hypothalamic defects involving GnRH neurons may impair the reproductive function. Among metabolic factors hyperglycemia has been implicated in the control of the reproductive axis at central level, both in humans and in animal models. To date, little is known about the direct effects of pathological high glucose concentrations on human GnRH neurons. In this study, we investigated the high glucose...

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

Uptake and release of glucose by the human kidney. Postabsorptive rates and responses to epinephrine.

Science.gov (United States)

Stumvoll, M; Chintalapudi, U; Perriello, G; Welle, S; Gutierrez, O; Gerich, J

1995-11-01

Despite ample evidence that the kidney can both produce and use appreciable amounts of glucose, the human kidney is generally regarded as playing a minor role in glucose homeostasis. This view is based on measurements of arteriorenal vein glucose concentrations indicating little or no net release of glucose. However, inferences from net balance measurements do not take into consideration the simultaneous release and uptake of glucose by the kidney. Therefore, to assess the contribution of release and uptake of glucose by the human kidney to overall entry and removal of plasma glucose, we used a combination of balance and isotope techniques to measure renal glucose net balance, fractional extraction, uptake and release as well as overall plasma glucose appearance and disposal in 10 normal volunteers under basal postabsorptive conditions and during a 3-h epinephrine infusion. In the basal postabsorptive state, there was small but significant net output of glucose by the kidney (66 +/- 22 mumol.min-1, P = 0.016). However, since renal glucose fractional extraction averaged 2.9 +/- 0.3%, there was considerable renal glucose uptake (2.3 +/- 0.2 mumol.kg-1.min-1) which accounted for 20.2 +/- 1.7% of systemic glucose disposal (11.4 +/- 0.5 mumol.kg-1.min-1). Renal glucose release (3.2 +/- 0.2 mumol.kg-1.min-1) accounted for 27.8 +/- 2.1% of systemic glucose appearance (11.4 +/- 0.5 mumol.kg-1.min-1). Epinephrine infusion, which increased plasma epinephrine to levels observed during hypoglycemia (3722 +/- 453 pmol/liter) increased renal glucose release nearly twofold (5.2 +/- 0.5 vs 2.8 +/- 0.1 mol.kg-1.min-1, P = 0.01) so that at the end of the infusion, renal glucose release accounted for 40.3 +/- 5.5% of systemic glucose appearance and essentially all of the increase in systemic glucose appearance. These observations suggest an important role for the human kidney in glucose homeostasis.

Direct effects of FGF21 on glucose uptake in human skeletal muscle

DEFF Research Database (Denmark)

Mashili, Fredirick L; Austin, Reginald L; Deshmukh, Atul S

2011-01-01

21 were determined in normal glucose tolerant (n = 40) and type 2 diabetic (T2D; n = 40) subjects. We determined whether FGF21 has direct effects on glucose metabolism in cultured myotubes (n = 8) and extensor digitorum longus skeletal muscle. RESULTS: Serum FGF21 levels increased 20% in T2D versus...... normal glucose tolerant subjects (p muscle mRNA expression was unaltered. Fasting insulin, homeostatic model assessment of insulin resistance (HOMA-IR), waist circumference, and body mass index (BMI) significantly correlated with serum FGF21 levels in T2D (p ... and insulin-stimulated glucose uptake in human myotubes, coincident with increased glucose transporter 1 mRNA, and enhanced glucose transporter 1 abundance at the plasma membrane. In isolated extensor digitorum longus muscle, FGF21 potentiated insulin-stimulated glucose transport, without altering...

Urinary loss of glucose, phosphate, and protein by diffusion into proximal straight tubules injured by D-serine and maleic acid

International Nuclear Information System (INIS)

Carone, F.A.; Nakamura, S.; Goldman, B.

1985-01-01

In several models of acute renal failure leakage of glomerular filtrate out of the tubule is an important pathogenetic mechanism; however, bidirectional diffusion of solute to account for certain pathophysiologic features of acute renal failure has received meager attention. Using micropuncture and clearance methods, the authors assessed sequentially leakage of solutes and inulin across proximal straight tubules (PST) injured by two nephrotoxins. In d-serine-treated rats with extensive necrosis of PST, the basis for glucosuria and tubular leakage of inulin was studied. Glucose absorption by the proximal convoluted tubule and glucose delivery to the PST were normal, but glucose delivery to the distal tubule was increased nearly 8-fold, indicating diffusion of glucose from interstitial to tubular luminal fluid across the necrotic PST. Total kidney inulin clearance was greatly reduced, but single nephron glomerular filtration rate, based on proximal convoluted tubule samples, was normal, indicating tubular loss of inulin. Urinary recovery of [ 14 C]inulin infused into tubular lumina revealed that proximal convoluted tubule and distal tubule were impermeable to inulin and that inulin diffused out of the necrotic PST. The progressive return over 6 days of tubular impermeability for inulin correlated with relining of PST with new cells. In maleic acid-treated rats the site and extent of tubular necrosis and the nature of urinary loss of solutes were studied. Microdissection revealed that maleic acid caused limited necrosis of PST which averaged 7.4% of total proximal tubular length. Increased urinary excretion of protein, phosphate, and glucose and increased tubular permeability to microinfused [ 14 C]inulin occurred with the onset of PST necrosis, and return of these abnormalities to normal correlated with the degree of cellular repair of the PST

Glucose metabolism and astrocyte-neuron interactions in the neonatal brain.

Science.gov (United States)

Brekke, Eva; Morken, Tora Sund; Sonnewald, Ursula

2015-03-01

Glucose is essentially the sole fuel for the adult brain and the mapping of its metabolism has been extensive in the adult but not in the neonatal brain, which is believed to rely mainly on ketone bodies for energy supply. However, glucose is absolutely indispensable for normal development and recent studies have shed light on glycolysis, the pentose phosphate pathway and metabolic interactions between astrocytes and neurons in the 7-day-old rat brain. Appropriately (13)C labeled glucose was used to distinguish between glycolysis and the pentose phosphate pathway during development. Experiments using (13)C labeled acetate provided insight into the GABA-glutamate-glutamine cycle between astrocytes and neurons. It could be shown that in the neonatal brain the part of this cycle that transfers glutamine from astrocytes to neurons is operating efficiently while, in contrast, little glutamate is shuttled from neurons to astrocytes. This lack of glutamate for glutamine synthesis is compensated for by anaplerosis via increased pyruvate carboxylation relative to that in the adult brain. Furthermore, compared to adults, relatively more glucose is prioritized to the pentose phosphate pathway than glycolysis and pyruvate dehydrogenase activity. The reported developmental differences in glucose metabolism and neurotransmitter synthesis may determine the ability of the brain at various ages to resist excitotoxic insults such as hypoxia-ischemia. Copyright © 2015 Elsevier Ltd. All rights reserved.

Research and engineering assessment of biological solubilization of phosphate

Energy Technology Data Exchange (ETDEWEB)

Rogers, R.D.; McIlwain, M.E.; Losinski, S.J.; Taylor, D.D.

1993-03-01

This research and engineering assessment examined a microbial phosphate solubilization process as a method of recovering phosphate from phosphorus containing ore compared to the existing wet acid and electric arc methods. A total of 860 microbial isolates, collected from a range of natural environments were tested for their ability to solubilize phosphate from rock phosphate. A bacterium (Pseudomonas cepacia) was selected for extensive characterization and evaluation of the mechanism of phosphate solubilization and of process engineering parameters necessary to recover phosphate from rock phosphate. These studies found that concentration of hydrogen ion and production of organic acids arising from oxidation of the carbon source facilitated microbial solubilization of both pure chemical insoluble phosphate compounds and phosphate rock. Genetic studies found that phosphate solubilization was linked to an enzyme system (glucose dehydrogenase). Process-related studies found that a critical solids density of 1% by weight (ore to liquid) was necessary for optimal solubilization. An engineering analysis evaluated the cost and energy requirements for a 2 million ton per year sized plant, whose size was selected to be comparable to existing wet acid plants.

Inhibition of the pentose phosphate shunt by 2,3-diphosphoglycerate in erythrocyte pyruvate kinase deficiency.

Science.gov (United States)

Tomoda, A; Lachant, N A; Noble, N A; Tanaka, K R

1983-07-01

Pentose phosphate shunt activity was studied by the release of 14CO2 from 14C-1-glucose and 14C-2-glucose in the red cells of five patients with pyruvate kinase deficiency and found to be significantly decreased after new methylene blue stimulation when compared to high reticulocyte controls. Incubated Heinz body formation was increased and the ascorbate cyanide test was positive in blood from these patients. The activity of glucose-6-phosphate dehydrogenase (G6PD) as well as that of 6-phosphogluconate dehydrogenase (6PGD) was inhibited to 20% of baseline in normal red cell haemolysate by 4 mM 2,3-diphosphoglycerate at pH 7.1. 2,3-Diphosphoglycerate was a competitive inhibitor with 6-phosphogluconate (Ki=1.05 mM) and a noncompetitive inhibitor with NADP (Ki=3.3 mM) for 6PGD. Since the intracellular concentrations of glucose-6-phosphate, 6-phosphogluconate and NADP are below their Kms for G6PD and 6PGD, the kinetic data suggest that increased concentrations of 2,3-diphosphoglycerate in pyruvate kinase deficient red cells are sufficiently high to suppress pentose phosphate shunt activity. This suppression may be an additional factor contributing to the haemolytic anaemia of pyruvate kinase deficiency, particularly during periods of infection or metabolic stress.

Benfotiamine increases glucose oxidation and downregulates NADPH oxidase 4 expression in cultured human myotubes exposed to both normal and high glucose concentrations

OpenAIRE

Fraser, D. A.; Hessvik, N. P.; Nikolić, N.; Aas, V.; Hanssen, K. F.; Bøhn, S. K.; Thoresen, G. H.; Rustan, A. C.

2011-01-01

The aim of the present work was to study the effects of benfotiamine (S-benzoylthiamine O-monophosphate) on glucose and lipid metabolism and gene expression in differentiated human skeletal muscle cells (myotubes) incubated for 4 days under normal (5.5 mM glucose) and hyperglycemic (20 mM glucose) conditions. Myotubes established from lean, healthy volunteers were treated with benfotiamine for 4 days. Glucose and lipid metabolism were studied with labeled precursors. Gene expression was measu...

Human-Phosphate-Binding-Protein inhibits HIV-1 gene transcription and replication

Directory of Open Access Journals (Sweden)

Candolfi Ermanno

2011-07-01

Full Text Available Abstract The Human Phosphate-Binding protein (HPBP is a serendipitously discovered lipoprotein that binds phosphate with high affinity. HPBP belongs to the DING protein family, involved in various biological processes like cell cycle regulation. We report that HPBP inhibits HIV-1 gene transcription and replication in T cell line, primary peripherical blood lymphocytes and primary macrophages. We show that HPBP is efficient in naïve and HIV-1 AZT-resistant strains. Our results revealed HPBP as a new and potent anti HIV molecule that inhibits transcription of the virus, which has not yet been targeted by HAART and therefore opens new strategies in the treatment of HIV infection.

Fine print in isotope effects: the glucose anomeric equilibrium and binding of glucose to human brain hexokinase

International Nuclear Information System (INIS)

Lewis, B.E; Schramm, V.L.

2002-01-01

Binding isotope effects are a sensitive measure of changes in molecular vibrational character that occur during ligand-receptor binding. In this study, we have measured isotope effects on the binding of glucose to human brain hexokinase using the ultrafiltration method, with the following results: 0.991±0.001, 0.908±0.003, 1.010±0.001, 0.974±0.002, 1.022±0.002 for [ 14 C]-glucose mixed with [1- 3 H]-, [2- 3 H]-, [3- 3 H]-, [5- 3 H]-, [6,6- 3 H]-glucose, respectively. Comparing the observed data with isotope effects on the anomeric equilibrium in glucose reported previously proves the existence of binding isotope effects in this system. Preliminary computational results are presented to explain the observed binding isotope effects in terms of hydrogen bond patterns and molecular crowding found in the binary complex of sugar and enzyme. (author)

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.

The relationship between gluconeogenic substrate supply and glucose production in humans

International Nuclear Information System (INIS)

Jahoor, F.; Peters, E.J.; Wolfe, R.R.

1990-01-01

The relationship between gluconeogenic precursor supply and glucose production has been investigated in 14-h and 86-h fasted humans. In protocols 1 and 2 [6,6-2H]glucose and [15N2]urea were infused to measure glucose and urea production rates (Ra) in response to infusions of glycerol and alanine. In protocol 3 first [15N]alanine, [3-13C]lactate, and [6,6-2H]glucose were infused before and during administration of dichloroacetate (DCA) to determine the response of glucose Ra to decreased fluxes of pyruvate, alanine, and lactate, then alanine was infused with DCA and glucose Ra measured. After a 14-h fast, neither alanine nor glycerol increased glucose Ra. Basal glucose Ra decreased by one-third after 86 h of fasting, yet glycerol and alanine infusions had no effect on glucose Ra. Glycerol always reduced urea Ra (P less than 0.05), suggesting that glycerol competitively inhibited gluconeogenesis from amino acids. DCA decreased the fluxes of pyruvate, alanine (P less than 0.01), and glucose Ra (P less than 0.01), which was prevented by alanine infusion. These findings suggest that (1) the reduction in glucose Ra after an 86-h fast is not because of a shortage of gluconeogenic substrate; (2) nonetheless, the importance of precursor supply to maintain basal glucose Ra is confirmed by the response to DCA; (3) an excess of one gluconeogenic substrate inhibits gluconeogenesis from others

Fabrication of Amperometric Glucose Sensor Using Glucose Oxidase-Cellulose Nanofiber Aqueous Solution.

Science.gov (United States)

Yasuzawa, Mikito; Omura, Yuya; Hiura, Kentaro; Li, Jiang; Fuchiwaki, Yusuke; Tanaka, Masato

2015-01-01

Cellulose nanofiber aqueous solution, which remained virtually transparent for more than one week, was prepared by using the clear upper layer of diluted cellulose nanofiber solution produced by wet jet milling. Glucose oxidase (GOx) was easily dissolved in this solution and GOx-immobilized electrode was easily fabricated by simple repetitious drops of GOx-cellulose solution on the surface of a platinum-iridium electrode. Glucose sensor properties of the obtained electrodes were examined in phosphate buffer solution of pH 7.4 at 40°C. The obtained electrode provided a glucose sensor response with significantly high response speed and good linear relationship between glucose concentration and response current. After an initial decrease of response sensitivity for a few days, relatively constant sensitivity was obtained for about 20 days. Nevertheless, the influence of electroactive compounds such as ascorbic acid, uric acid and acetoaminophen were not negletable.

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.

Second trimester amniotic fluid glucose, uric acid, phosphate, potassium, and sodium concentrations in relation to maternal pre-pregnancy BMI and birth weight centiles.

Science.gov (United States)

Fotiou, Maria; Michaelidou, Alexandra Maria; Athanasiadis, Apostolos P; Menexes, Georgios; Symeonidou, Maria; Koulourida, Vasiliki; Ganidou, Maria; Theodoridis, Theodoros D; Tarlatzis, Basil C

2015-05-01

To study the evolution profile of amniotic fluid (AF) glucose, uric acid, phosphate, potassium, and sodium, in the second trimester of pregnancy, and explore the possible relations between the concentration of these components and maternal, as well as neonatal characteristics. AF of 52 pregnant women was analyzed using an automatic multichannel analyzer. Maternal age, pre-pregnancy Body Mass Index (BMI), inter-pregnancy intervals, and smoking status were derived from questionnaires. Information on pregnancy and delivery was collected from medical records. Uric acid increased (r = 0.423, p pregnancy (r = -0.590, p pregnancy BMI was significantly correlated with AF uric acid concentration (r = 0.460, p sodium (r = 0.254, p = 0.070) levels. Multiple linear regression indicated that mid-trimester AF uric acid and phosphate levels were significantly related to birth weight centiles (R(2)( )= 0.345, p pregnancy BMI is significantly correlated with AF uric acid concentration, and (c) in appropriate for gestational age infants, AF phosphate and uric acid levels may serve as potential biomarkers of birth weight centiles. Further studies on AF composition may help to unravel the biochemical pathways underlying fetal development and could offer insight on the potential impact of maternal nutritional management on fetal growth regulation.

The effect of calcium phosphate nanoparticles on hormone production and apoptosis in human granulosa cells

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Gao Li

2010-04-01

Full Text Available Abstract Objectives Although many nanomaterials are being used in academia, industry and daily life, there is little understanding about the effects of nanoparticles on the reproductive health of vertebral animals, including human beings. An experimental study was therefore performed here to explore the effect of calcium phosphate nanoparticles on both steroid hormone production and apoptosis in human ovarian granulosa cells. Methods Calcium phosphate nanoparticles uptaking was evaluated by transmission electron microscopy (TEM. The cell cycle was assessed with propidium iodide-stained cells (distribution of cells in G0/G1, S, and G2/M phases by flow cytometry. The pattern of cell death (necrosis and apoptosis was analyzed by flow cytometry with annexin V-FITC/PI staining. The expression of mRNAs encoding P450scc, P450arom and StAR were determined by RT-PCR. Progesterone and estradiol levels were measured by radioimmunoassay. Results TEM results confirmed that calcium phosphate nanoparticles could enter into granulosa cells, and distributed in the membranate compartments, including lysosome and mitochondria and intracellular vesicles. The increased percentage of cells in S phase when cultured with nanoparticles indicated that there was an arrest at the checkpoint from phase S-to-G2/M (from 6.28 +/- 1.55% to 11.18 +/- 1.73%, p Conclusion Calcium phosphate nanoparticles interfered with cell cycle of cultured human ovarian granulosa cells thus increasing cell apoptosis. This pilot study suggested that effects of nanoparticles on ovarian function should be extensively investigated.

Zinc oxide nano-rods based glucose biosensor devices fabrication

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Wahab, H. A.; Salama, A. A.; El Saeid, A. A.; Willander, M.; Nur, O.; Battisha, I. K.

2018-06-01

ZnO is distinguished multifunctional material that has wide applications in biochemical sensor devices. For extracellular measurements, Zinc oxide nano-rods will be deposited on conducting plastic substrate with annealing temperature 150 °C (ZNRP150) and silver wire with annealing temperature 250 °C (ZNRW250), for the extracellular glucose concentration determination with functionalized ZNR-coated biosensors. It was performed in phosphate buffer saline (PBS) over the range from 1 μM to 10 mM and on human blood plasma. The prepared samples crystal structure and surface morphologies were characterized by XRD and field emission scanning electron microscope FESEM respectively.

Decreased glucose uptake by hyperglycemia is regulated by different mechanisms in human cancer cells and monocytes

International Nuclear Information System (INIS)

Kim, Chae Kyun; Chung, June Key; Lee, Yong Jin; Hong, Mee Kyoung; Jeong, Jae Min; Lee, Dong Soo; Lee, Myung Chul

2002-01-01

To clarify the difference in glucose uptake between human cancer cells and monocytes, we studied ( 18 F) fluorodeoxyglucose (FDG) uptake in three human colon cancer cell lines (SNU-C2A, SNU-C4, SNU-C5), one human lung cancer cell line (NCI-H522), and human peripheral blood monocytes. The FDG uptake of both cancer cells and monocytes was increased in glucose-free medium, but decreased in the medium containing 16.7 mM glucose (hyperglycemic). The level of Glut1 mRNA decreased in human colon cancer cells and NCI-H522 under hyperglycemic condition. Glut1 protein expression was also decreased in the four human cancer cell lines under hyperglycemic condition, whereas it was consistently undetectable in monocytes. SNU-C2A, SNU-C4 and NCI-H522 showed a similar level of hexokinase activity (7.5-10.8 mU/mg), while SNU-C5 and moncytes showed lower range of hexokinase activity (4.3-6.5 mU/mg). These data suggest that glucose uptake is regulated by different mechanisms in human cancer cells and monocytes

Glucose phosphorylation is not rate limiting for accumulation of glycogen from glucose in perfused livers from fasted rats

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Youn, J.H.; Ader, M.; Bergman, R.N.

1989-01-01

Incorporation of Glc and Fru into glycogen was measured in perfused livers from 24-h fasted rats using [6-3H]Glc and [U-14C]Fru. For the initial 20 min, livers were perfused with low Glc (2 mM) to deplete hepatic glycogen and were perfused for the following 30 min with various combinations of Glc and Fru. With constant Fru (2 mM), increasing perfusate Glc increased the relative contribution of Glc carbons to glycogen (7.2 +/- 0.4, 34.9 +/- 2.8, and 59.1 +/- 2.7% at 2, 10, and 20 mM Glc, respectively; n = 5 for each). During perfusion with substrate levels seen during refeeding (10 mM Glc, 1.8 mumol/g/min gluconeogenic flux from 2 mM Fru), Fru provided 54.7 +/- 2.7% of the carbons for glycogen, while Glc provided only 34.9 +/- 2.8%, consistent with in vivo estimations. However, the estimated rate of Glc phosphorylation was at least 1.10 +/- 0.11 mumol/g/min, which exceeded by at least 4-fold the glycogen accumulation rate (0.28 +/- 0.04 mumol of glucose/g/min). The total rate of glucose 6-phosphate supply via Glc phosphorylation and gluconeogenesis (2.9 mumol/g/min) exceeded reported in vivo rates of glycogen accumulation during refeeding. Thus, in perfused livers of 24-h fasted rats there is an apparent redundancy in glucose 6-phosphate supply. These results suggest that the rate-limiting step for hepatic glycogen accumulation during refeeding is located between glucose 6-phosphate and glycogen, rather than at the step of Glc phosphorylation or in the gluconeogenic pathway

Glucose metabolism in pigs expressing human genes under an insulin promoter.

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Wijkstrom, Martin; Bottino, Rita; Iwase, Hayoto; Hara, Hidetaka; Ekser, Burcin; van der Windt, Dirk; Long, Cassandra; Toledo, Frederico G S; Phelps, Carol J; Trucco, Massimo; Cooper, David K C; Ayares, David

2015-01-01

Xenotransplantation of porcine islets can reverse diabetes in non-human primates. The remaining hurdles for clinical application include safe and effective T-cell-directed immunosuppression, but protection against the innate immune system and coagulation dysfunction may be more difficult to achieve. Islet-targeted genetic manipulation of islet-source pigs represents a powerful tool to protect against graft loss. However, whether these genetic alterations would impair islet function is unknown. On a background of α1,3-galactosyltransferase gene-knockout (GTKO)/human (h)CD46, additional genes (hCD39, human tissue factor pathway inhibitor, porcine CTLA4-Ig) were inserted in different combinations under an insulin promoter to promote expression in islets (confirmed by immunofluorescence). Seven pigs were tested for baseline and glucose/arginine-challenged levels of glucose, insulin, C-peptide, and glucagon. This preliminary study did not show definite evidence of β-cell deficiencies, even when three transgenes were expressed under the insulin promoter. Of seven animals, all were normoglycemic at fasting, and five of seven had normal glucose disposal rates after challenge. All animals exhibited insulin, C-peptide, and glucagon responses to both glucose and arginine challenge; however, significant interindividual variation was observed. Multiple islet-targeted transgenic expression was not associated with an overtly detrimental effect on islet function, suggesting that complex genetic constructs designed for islet protection warrants further testing in islet xenotransplantation models. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Linking neuronal brain activity to the glucose metabolism.

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Göbel, Britta; Oltmanns, Kerstin M; Chung, Matthias

2013-08-29

Energy homeostasis ensures the functionality of the entire organism. The human brain as a missing link in the global regulation of the complex whole body energy metabolism is subject to recent investigation. The goal of this study is to gain insight into the influence of neuronal brain activity on cerebral and peripheral energy metabolism. In particular, the tight link between brain energy supply and metabolic responses of the organism is of interest. We aim to identifying regulatory elements of the human brain in the whole body energy homeostasis. First, we introduce a general mathematical model describing the human whole body energy metabolism. It takes into account the two central roles of the brain in terms of energy metabolism. The brain is considered as energy consumer as well as regulatory instance. Secondly, we validate our mathematical model by experimental data. Cerebral high-energy phosphate content and peripheral glucose metabolism are measured in healthy men upon neuronal activation induced by transcranial direct current stimulation versus sham stimulation. By parameter estimation we identify model parameters that provide insight into underlying neurophysiological processes. Identified parameters reveal effects of neuronal activity on regulatory mechanisms of systemic glucose metabolism. Our examinations support the view that the brain increases its glucose supply upon neuronal activation. The results indicate that the brain supplies itself with energy according to its needs, and preeminence of cerebral energy supply is reflected. This mechanism ensures balanced cerebral energy homeostasis. The hypothesis of the central role of the brain in whole body energy homeostasis as active controller is supported.

Is Insulin Action in the Brain Relevant in Regulating Blood Glucose in Humans?

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Dash, Satya; Xiao, Changting; Morgantini, Cecilia; Koulajian, Khajag; Lewis, Gary F

2015-07-01

In addition to its direct action on the liver to lower hepatic glucose production, insulin action in the central nervous system (CNS) also lowers hepatic glucose production in rodents after 4 hours. Although CNS insulin action (CNSIA) modulates hepatic glycogen synthesis in dogs, it has no net effect on hepatic glucose output over a 4-hour period. The role of CNSIA in regulating plasma glucose has recently been examined in humans and is the focus of this review. Intransal insulin (INI) administration increases CNS insulin concentration. Hence, INI can address whether CNSIA regulates plasma glucose concentration in humans. We and three other groups have sought to answer this question, with differing conclusions. Here we will review the critical aspects of each study, including its design, which may explain these discordant conclusions. The early glucose-lowering effect of INI is likely due to spillover of insulin into the systemic circulation. In the presence of simultaneous portal and CNS hyperinsulinemia, portal insulin action is dominant. INI administration does lower plasma glucose independent of peripheral insulin concentration (between ∼3 and 6 h after administration), suggesting that CNSIA may play a role in glucose homeostasis in the late postprandial period when its action is likely greatest and portal insulin concentration is at baseline. The potential physiological role and purpose of this pathway are discussed in this review. Because the effects of INI are attenuated in patients with type 2 diabetes and obesity, this is unlikely to be of therapeutic utility.

Analysis of phosphate esters in plant material. Extraction and purification.

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Isherwood, F A; Barrett, F C

1967-09-01

1. A critical study was made of the quantitative extraction of nucleotide and sugar phosphates from plant tissue by either boiling aqueous ethanol or cold trichloroacetic acid. The effect of the extraction technique on the inactivation of the enzymes in the plant tissue and the possibility of adsorption of the phosphate esters on the cell wall were especially considered. 2. In the recommended method the plant tissue was frozen in liquid nitrogen, ground to a powder and then blended with cold aqueous trichloroacetic acid containing 8-hydroxyquinoline to prevent adsorption. 3. The extract contained large amounts of trichloroacetic acid, cations, chloride, sugars, amino acids, hydroxy organic acids, phytic acid, orthophosphoric acid and high-molecular-weight material including some phosphorus-containing compounds. All of these were removed as they were liable to interfere with the chromatographic or enzymic assay of the individual nucleotide or sugar phosphates. 4. The procedure was as follows: the last traces of trichloroacetic acid were extracted with ether after the solution had been passed through a column of Dowex AG 50 in the hydrogen form to remove all cations. High-molecular-weight compounds were removed by ultrafiltration and low-molecular-weight solutes by a two-stage chromatography on cellulose columns with organic solvents. In the first stage, sugars, amino acids, chloride and phytic acid were separated by using a basic solvent (propan-1-ol-water-aqueous ammonia) and, in the second stage, the organic acids and orthophosphoric acid were separated by using an acidic solvent (di-isopropyl ether-formic acid-2-methylpropan-2-ol-water). The final solution of nucleotide and sugar phosphates was substantially free from other solutes and was suitable for the detection of individual phosphate esters by either chromatography or enzymic assay. 5. The recovery of d-glucose 6-phosphate or adenosine 5'-triphosphate added to a trichloroacetic acid extract simulating that

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.

Effect of thoracic x-irradiation on glucose-6-phosphate dehydrogenase activity of the pectoral muscle of guinea pig

International Nuclear Information System (INIS)

Bhatavdekar, J.M.; Shah, V.C.

1981-01-01

The histochemical distribution of glucose-6-phosphate dehydrogenase (G6PD) was observed in the major pectoral muscle of a guinea pig that had received 240 R thoracic X-irradiation. The irradiation effects were studied at 24, 48 and 72 hrs after X-irradiation. Type I fibres of the pectoral muscle were deeply stained showing high activity whereas type II fibres demonstrated minimum enzyme activity. The intermediate fibres had medium levels of G6PD activity. Type II fibres showed more staining at 24 and 48 hrs as compared with control muscle. However, at 72 hrs all three fibre types showed a marked inhibition of G6PD activity. The significance of these changes suggests that muscle G6PD metabolism generally altered after irradiation, but the specific nature of these changes and their causes still remain unclear. (author)

Effect of Punica granatum fruit peel on glucose-6-phosphate dehydrogenase and malate dehydrogenase in amphistome Gastrothylax indicus.

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Aggarwal, Rama; Bagai, Upma

2017-03-01

Increasing anthelmintic resistance and the impact of conventional anthelmintics on the environment, it is important to look for alternative strategies against helminth parasite in sheep. Important lipogenic enzymes like glucose-6-phosphate dehydrogenase (G-6-PDH) and malate dehydrogenase (MDH) show subcellular distribution pattern. Activity of G-6-PDH was largely restricted to cytosolic fraction while MDH was found in both cytosolic and mitochondrial fraction in Gastrothylax indicus. Following in vitro treatment with ethanolic and aqueous extracts of Punica granatum fruit peel and commercial anthelmintic, albendazole G-6-PDH activity was decreased by 19-32 %, whereas MDH was suppressed by 24-41 %, compared to the respective control. Albendazole was quite effective when compared with negative control and both the extracts. The results indicate that phytochemicals of plant may act as potential vermifuge or vermicide.

Generation of glucose-responsive, insulin-producing cells from human umbilical cord blood-derived mesenchymal stem cells.

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Prabakar, Kamalaveni R; Domínguez-Bendala, Juan; Molano, R Damaris; Pileggi, Antonello; Villate, Susana; Ricordi, Camillo; Inverardi, Luca

2012-01-01

We sought to assess the potential of human cord blood-derived mesenchymal stem cells (CB-MSCs) to derive insulin-producing, glucose-responsive cells. We show here that differentiation protocols based on stepwise culture conditions initially described for human embryonic stem cells (hESCs) lead to differentiation of cord blood-derived precursors towards a pancreatic endocrine phenotype, as assessed by marker expression and in vitro glucose-regulated insulin secretion. Transplantation of these cells in immune-deficient animals shows human C-peptide production in response to a glucose challenge. These data suggest that human cord blood may be a promising source for regenerative medicine approaches for the treatment of diabetes mellitus.

Structural Analysis of ADP-Glucose Pyrophosphorylase From the Bacterium Agrobacterium Tumefaciens

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Cupp-Vickery, J.R.; Igarashi, R.Y.; Perez, M.; Poland, M.; Meyer, C.R.

2009-05-14

ADP-glucose pyrophosphorylase (ADPGlc PPase) catalyzes the conversion of glucose 1-phosphate and ATP to ADP-glucose and pyrophosphate. As a key step in glucan synthesis, the ADPGlc PPases are highly regulated by allosteric activators and inhibitors in accord with the carbon metabolism pathways of the organism. Crystals of Agrobacterium tumefaciens ADPGlc PPase were obtained using lithium sulfate as a precipitant. A complete anomalous selenomethionyl derivative X-ray diffraction data set was collected with unit cell dimensions a = 85.38 {angstrom}, b = 93.79 {angstrom}, and c = 140.29 {angstrom} ({alpha} = {beta} = {gamma} = 90{sup o}) and space group I{sub 222}. The A. tumefaciens ADPGlc PPase model was refined to 2.1 {angstrom} with an R{sub factor} = 22% and R{sub free} = 26.6%. The model consists of two domains: an N-terminal {alpha}{beta}{alpha} sandwich and a C-terminal parallel {beta}-helix. ATP and glucose 1-phosphate were successfully modeled in the proposed active site, and site-directed mutagenesis of conserved glycines in this region (G20, G21, and G23) resulted in substantial loss of activity. The interface between the N- and the C-terminal domains harbors a strong sulfate-binding site, and kinetic studies revealed that sulfate is a competitive inhibitor for the allosteric activator fructose 6-phosphate. These results suggest that the interface between the N- and C-terminal domains binds the allosteric regulator, and fructose 6-phosphate was modeled into this region. The A. tumefaciens ADPGlc PPase/fructose 6-phosphate structural model along with sequence alignment analysis was used to design mutagenesis experiments to expand the activator specificity to include fructose 1,6-bisphosphate. The H379R and H379K enzymes were found to be activated by fructose 1,6-bisphosphate.

The overexpressed human 46-kDa mannose 6-phosphate receptor mediates endocytosis and sorting of β-glucuronidase

International Nuclear Information System (INIS)

Watanabe, H.; Grubb, J.H.; Sly, W.S.

1990-01-01

The authors studied the function of the human small (46-kDa) mannose 6-phosphate receptor (SMPR) in transfected mouse L cells that do not express the larger insulin-like growth factor II/mannose 6-phosphate receptor. Cells overexpressing human SMPR were studied for enzyme binding to cell surface receptors, for binding to intracellular receptors in permeabilized cells, and for receptor-mediated endocytosis of recombinant human β-glucuronidase. Specific binding to human SMPR in permeabilized cells showed a pH optimum between pH 6.0 and pH 6.5. Binding was significant in the present of EDTA but was enhanced by added divalent cations. Up to 2.3% of the total functional receptor could be detected on the cell surface by enzyme binding. They present experiments showing that at very high levels of overexpression, and at pH 6.5, human SMPR mediated the endocytosis of β-glucuronidase. At pH 7.5, the rate of endocytosis was only 14% the rate seen at pH 6.5. Cells overexpressing human SMPR also showed reduced secretion of newly synthesized β-glucuronidase when compared to cells transfected with vector only, suggesting that overexpressed human SMPR can participate in sorting of newly synthesized β-glucuronidase and partially correct the sorting defect in mouse L cells that do not express the insulin-like growth factor II/mannose 6-phosphate receptor

Glucose metabolic alterations in hippocampus of diabetes mellitus rats and the regulation of aerobic exercise.

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Li, Jingjing; Liu, Beibei; Cai, Ming; Lin, Xiaojing; Lou, Shujie

2017-11-04

Diabetes could negatively affect the structures and functions of the brain, especially could cause the hippocampal dysfunction, however, the potential metabolic mechanism is unclear. The aim of this study was to investigate the changes of glucose metabolism in hippocampus of diabetes mellitus rats and the regulation of aerobic exercise, and to analyze the possible mechanisms. A rat model of type 2 diabetes mellitus was established by high-fat diet feeding in combination with STZ intraperitoneal injection, then 4 weeks of aerobic exercise was conducted. The glucose metabolites and key enzymes involved in glucose metabolism in hippocampus were respectively detected by GC/MS based metabolomics and western blot. Metabolomics results showed that compared with control rats, the level of citric acid was significantly decreased, while the levels of lactic acid, ribose 5-phosphate, xylulose 5-phosphate and glucitol were significantly increased in the diabetic rat. Compared with diabetic rats, the level of citric acid was significantly increased, while the lactic acid, ribose 5-phosphate and xylulose 5-phosphate were significantly decreased in the diabetic exercise rats. Western blot results showed that lower level of citrate synthase and oxoglutarate dehydrogenase, higher level of aldose reductase and glucose 6-phosphatedehydrogenase were found in the diabetic rats when compared to control rats. After 4 weeks of aerobic exercise, citrate synthase was upregulated and glucose 6-phosphatedehydrogenase was downregulated in the diabetic rats. These results suggest that diabetes could cause abnormal glucose metabolism, and aerobic exercise plays an important role in regulating diabetes-induced disorder of glucose metabolism in the hippocampus. Copyright © 2017 Elsevier B.V. All rights reserved.

Immunocytochemical detection of the microsomal glucose-6-phosphatase in human brain astrocytes.

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Bell, J E; Hume, R; Busuttil, A; Burchell, A

1993-10-01

Using an antibody raised against the catalytic subunit of glucose-6-phosphatase, this enzyme was immunolocalized in many astrocytes in 20 normal human brains. Double immunofluorescence studies showed co-localization of glial fibrillary acidic protein (GFAP) with glucose-6-phosphatase in astrocytes. However, not all GFAP-positive cells were also glucose-6-phosphatase positive, indicating that some astrocytes do not contain demonstrable expression of this enzyme. Reactive astrocytes in a variety of abnormal brains were strongly glucose-6-phosphatase positive, but neoplastic astrocytes were often only weakly positive. Expression of the enzyme could not be demonstrated in radial glia, neurons or oligodendroglia. Astrocytes normally contain glycogen and the demonstration that some astrocytes also contain glucose-6-phosphatase indicates that they are competent for both glycogenolysis and gluconeogenesis, which may be critical for neuronal welfare.

Insulin resistance in human subjects having impaired glucose regulation

International Nuclear Information System (INIS)

Khan, S.H.; Khan, F.A.; Ijaz, A.

2007-01-01

To determine insulin resistance in human subjects having impaired glucose regulation (IGR) by Homeostasis Model Assessment for Insulin Resistance (HOMA-IR). A total of 100 subjects with impaired glucose regulation were selected for evaluation of metabolic syndrome as per the criteria of National Cholesterol Education Program, Adult Treatment Panel III (NCEP, ATP III), along with 47 healthy age and gender-matched controls. Physical examination to determine blood pressure and waist circumference was carried out and so was sampling for plasma glucose, serum triglycerides, HDL-cholesterol and insulin. Insulin resistance was calculated by the HOMA-IR. Finally, subjects with and without metabolic syndrome were compared with controls (n=47), using one-way ANOVA for studying insulin resistance between groups, with Tukey's post-hoc comparison. The frequency of finding metabolic syndrome in cases of IGR remained 47%. The insulin resistance demonstrated stepwise worsening from control population (mean=1.54, 95 % CI: 1.77 - 2.37) to subjects suffering from only IGR (mean=2.07, 95 % CI: 1.77- 2.37) to metabolic syndrome (mean=2.67, 95 %, CI: 2.34 - 3.00) (p < 0.001). Patients with impaired glucose regulation may have significant insulin resistance. It is, thus, recommended that a vigorous search be made to measure insulin resistance in all cases diagnosed to have impaired glucose regulation. (author)

Decreased glucose uptake by hyperglycemia is regulated by different mechanisms in human cancer cells and monocytes

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Kim, Chae Kyun; Chung, June Key; Lee, Yong Jin; Hong, Mee Kyoung; Jeong, Jae Min; Lee, Dong Soo; Lee, Myung Chul [College of Medicine, Seoul National Univ., Seoul (Korea, Republic of)

2002-04-01

To clarify the difference in glucose uptake between human cancer cells and monocytes, we studied ({sup 18}F) fluorodeoxyglucose (FDG) uptake in three human colon cancer cell lines (SNU-C2A, SNU-C4, SNU-C5), one human lung cancer cell line (NCI-H522), and human peripheral blood monocytes. The FDG uptake of both cancer cells and monocytes was increased in glucose-free medium, but decreased in the medium containing 16.7 mM glucose (hyperglycemic). The level of Glut1 mRNA decreased in human colon cancer cells and NCI-H522 under hyperglycemic condition. Glut1 protein expression was also decreased in the four human cancer cell lines under hyperglycemic condition, whereas it was consistently undetectable in monocytes. SNU-C2A, SNU-C4 and NCI-H522 showed a similar level of hexokinase activity (7.5-10.8 mU/mg), while SNU-C5 and moncytes showed lower range of hexokinase activity (4.3-6.5 mU/mg). These data suggest that glucose uptake is regulated by different mechanisms in human cancer cells and monocytes.

Glucose consumption and rate constants for 18F-fluorodeoxyglucose in human gliomas

International Nuclear Information System (INIS)

Ishikawa, Masatsune; Kikuchi, Haruhiko; Nagata, Izumi; Yamagata, Sen; Taki, Waro; Yonekura, Yoshiharu; Nishizawa, Sadahiko; Iwasaki, Yasushi; Mukai, Takao

1990-01-01

To investigate the value of direct measurement of the rate constants by performing 18 F-labeled fluorodeoxyglucose (FDG) studies of glucose consumption in human gliomas in vivo, a kinetic method with 3- and 4-parameter rate constant models for FDG uptake was used to analyze data from dynamic scans obtained by positron emission tomography after injection of FDG into 14 patients with glioma. The results were compared with those obtained by the autoradiographic method using 3- and 4-parameter rate constant models. There were no significant differences in the glucose consumption calculated by the four different methods both in the gliomas and in the contralateral intact cortex. It was found that the rate constant k4 could be neglected in calculation of glucose consumption in gliomas as well as in the contralateral intact cortex. The rate constant k3, an index of hexokinase function, was higher in malignant gliomas than in benign gliomas and was close to that in the contralateral cortex. This study indicates that the 3-parameter autoradiographic method, which is the most common one used in clinical practice, is reliable for the calculation of glucose consumption in human gliomas. Furthermore, direct measurement of the regional rate constants for FDG by the kinetic method was found to be useful for evaluation of the biochemical and physiological characteristics of human gliomas in vivo. (author)

Glucose buffer is suitable for blood group conversion with α-N acetylgalactosaminidase and α-galactosidase.

Science.gov (United States)

Gao, Hong-Wei; Li, Su-Bo; Bao, Guo-Qiang; Zhang, Xue; Li, Hui; Wang, Ying-Li; Tan, Ying-Xia; Ji, Shou-Ping; Gong, Feng

2014-01-01

It is well known that the buffer plays a key role in the enzymatic reaction involved in blood group conversion. In previous study, we showed that a glycine buffer is suitable for A to O or B to O blood group conversion. In this study, we investigated the use of 5% glucose and other buffers for A to O or B to O blood group conversion by α-N-acetylgalactosaminidase or α-galactosidase. We compared the binding ability of α-N-acetylgalactosaminidase/α-galactosidase with red blood cells (RBC) in different reaction buffers, such as normal saline, phosphate-buffered saline (PBS), a disodium hydrogen phosphate-based buffer (PCS), and 5% commercial glucose solution. The doses of enzymes necessary for the A/B to O conversion in different reaction buffers were determined and compared. The enzymes' ability to bind to RBC was evaluated by western blotting, and routine blood typing and fluorescence activated cell sorting was used to evaluate B/A to O conversion efficiency. The A to O conversion efficiency in glucose buffer was similar to that in glycine buffer with the same dose (>0.06 mg/mL pRBC). B to O conversion efficiency in glucose buffer was also similar to that in glycine buffer with the same dose (>0.005 mg/mL pRBC). Most enzymes could bind with RBC in glycine or glucose buffer, but few enzymes could bind with RBC in PBS, PCS, or normal saline. These results indicate that 5% glucose solution provides a suitable condition for enzymolysis, especially for enzymes combining with RBC. Meanwhile, the conversion efficiency of A/B to O was similar in glucose buffer and glycine buffer. Moreover, 5% glucose solution has been used for years in venous transfusion, it is safe for humans and its cost is lower. Our results do, therefore, suggest that 5% glucose solution could become a novel suitable buffer for A/B to O blood group conversion.

Demonstration of glucose-6-phosphate dehydrogenase in rat Kupffer cells by a newly-developed ultrastructural enzyme-cytochemistry

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S Matsubara

2009-06-01

Full Text Available Although various tissue macrophages possess high glucose- 6-phosphate dehydrogenase (G6PD activity, which is reported to be closely associated with their phagocytotic/bactericidal function, the fine subcellular localization of this enzyme in liver resident macrophages (Kupffer cells has not been determined.We have investigated the subcellular localization of G6PD in Kupffer cells in rat liver, using a newly developed enzyme-cytochemical (copper-ferrocyanide method. Electron-dense precipitates indicating G6PD activity were clearly visible in the cytoplasm and on the cytosolic side of the endoplasmic reticulum of Kupffer cells. Cytochemical controls ensured specific detection of the enzymatic activity. Rat Kupffer cells abundantly possessed enzyme-cytochemically detectable G6PD activity. Kupffer cell G6PD may play a role in liver defense by delivering NADPH to NADPH-dependent enzymes. G6PD enzyme-cytochemistry may be a useful tool for the study of Kupffer cell functions.

In vitro biotransformation of tris(2-butoxyethyl) phosphate (TBOEP) in human liver and serum

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Van den Eede, Nele, E-mail: nele.vandeneede@uantwerpen.be [Toxicological Center, Department of Pharmaceutical Sciences, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk, Antwerp (Belgium); Erratico, Claudio [Toxicological Center, Department of Pharmaceutical Sciences, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk, Antwerp (Belgium); Exarchou, Vassiliki [Natural Products & Food Research and Analysis (NatuRA), Department of Pharmaceutical Sciences, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk, Antwerp (Belgium); Maho, Walid; Neels, Hugo [Toxicological Center, Department of Pharmaceutical Sciences, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk, Antwerp (Belgium); Covaci, Adrian, E-mail: adrian.covaci@uantwerpen.be [Toxicological Center, Department of Pharmaceutical Sciences, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk, Antwerp (Belgium)

2015-04-15

Tris(2-butoxyethyl) phosphate (TBOEP) is a plasticizer present in indoor dust, reaching levels of several micrograms per gram. Such levels could lead to significant daily exposure of adults and children. Currently, no toxicokinetic data are available to estimate TBOEP clearance in humans after uptake and therefore, one objective of this study was to investigate intrinsic clearance of TBOEP by human liver microsome (HLM) and serum enzymes. Another objective was to generate information to identify and prioritize several metabolites of TBOEP for investigation of human exposure by biomonitoring. 1D and 2D-NMR methodologies were successfully applied on a mixture of the metabolites to confirm the structure of 3-HO-TBOEP (bis(2-butoxyethyl) 3-hydroxyl-2-butoxyethyl phosphate) and to tentatively assign structures to 1-HO-TBOEP and 2-HO-TBOEP. HO-TBOEP isomers and bis(2-butoxyethyl) phosphate (BBOEP), bis(2-butoxyethyl) hydroxyethyl phosphate (BBOEHEP) were further monitored by liquid chromatography–tandem mass spectrometry. Rates of formation of BBOEHEP and HO-TBOEP metabolites by liver enzymes were best described by the Michaelis–Menten model. Apparent K{sub m} values for BBOEHEP, 3-HO-TBOEP, and sum of 1- and 2-HO-TBOEP isomer formation were 152, 197 and 148 μM, respectively. Apparent V{sub max} values for the formation of BBOEHEP, 3-HO-TBOEP, and the sum of 1- and 2-HO-TBOEP isomers were 2560, 643, and 254 pmol/min/mg protein, respectively. No detectable formation of BBOEP occurred with liver or serum enzymes. Our findings indicate that intrinsic clearance of TBOEP is mainly catalyzed by oxidative enzymes in the liver and that its major in vitro metabolite is BBOEHEP. These findings can be applied in human biomonitoring studies and risk assessment. - Highlights: • First steps in the elucidation of TBOEP toxicokinetics • Quantification of TBOEP metabolites in human serum and liver microsomes • No detectable formation of BBOEP occurred with liver or serum

High-energy phosphate transfer in human muscle: diffusion of phosphocreatine.

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Gabr, Refaat E; El-Sharkawy, Abdel-Monem M; Schär, Michael; Weiss, Robert G; Bottomley, Paul A

2011-07-01

The creatine kinase (CK) reaction is central to muscle energetics, buffering ATP levels during periods of intense activity via consumption of phosphocreatine (PCr). PCr is believed to serve as a spatial shuttle of high-energy phosphate between sites of energy production in the mitochondria and sites of energy utilization in the myofibrils via diffusion. Knowledge of the diffusion coefficient of PCr (D(PCr)) is thus critical for modeling and understanding energy transport in the myocyte, but D(PCr) has not been measured in humans. Using localized phosphorus magnetic resonance spectroscopy, we measured D(PCr) in the calf muscle of 11 adults as a function of direction and diffusion time. The results show that the diffusion of PCr is anisotropic, with significantly higher diffusion along the muscle fibers, and that the diffusion of PCr is restricted to a ∼28-μm pathlength assuming a cylindrical model, with an unbounded diffusion coefficient of ∼0.69 × 10(-3) mm(2)/s. This distance is comparable in size to the myofiber radius. On the basis of prior measures of CK reaction kinetics in human muscle, the expected diffusion distance of PCr during its half-life in the CK reaction is ∼66 μm. This distance is much greater than the average distances between mitochondria and myofibrils. Thus these first measurements of PCr diffusion in human muscle in vivo support the view that PCr diffusion is not a factor limiting high-energy phosphate transport between the mitochondria and the myofibrils in healthy resting myocytes.

A Cuprous Oxide Thin Film Non-Enzymatic Glucose Sensor Using Differential Pulse Voltammetry and Other Voltammetry Methods and a Comparison to Different Thin Film Electrodes on the Detection of Glucose in an Alkaline Solution

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Yifan Dai

2018-01-01

Full Text Available A cuprous oxide (Cu2O thin layer served as the base for a non-enzymatic glucose sensor in an alkaline medium, 0.1 NaOH solution, with a linear range of 50–200 mg/dL using differential pulse voltammetry (DPV measurement. An X-ray photoelectron spectroscopy (XPS study confirmed the formation of the cuprous oxide layer on the thin gold film sensor prototype. Quantitative detection of glucose in both phosphate-buffered saline (PBS and undiluted human serum was carried out. Neither ascorbic acid nor uric acid, even at a relatively high concentration level (100 mg/dL in serum, interfered with the glucose detection, demonstrating the excellent selectivity of this non-enzymatic cuprous oxide thin layer-based glucose sensor. Chronoamperometry and single potential amperometric voltammetry were used to verify the measurements obtained by DPV, and the positive results validated that the detection of glucose in a 0.1 M NaOH alkaline medium by DPV measurement was effective. Nickel, platinum, and copper are commonly used metals for non-enzymatic glucose detection. The performance of these metal-based sensors for glucose detection using DPV were also evaluated. The cuprous oxide (Cu2O thin layer-based sensor showed the best sensitivity for glucose detection among the sensors evaluated.

Triiodothyronine (T3)-associated upregulation and downregulation of nuclear T3 binding in the human fibroblast cell (MRC-5)--stimulation of malic enzyme, glucose-6-phosphate-dehydrogenase, and 6-phosphogluconate-dehydrogenase by insulin, but not by T3

DEFF Research Database (Denmark)

Matzen, L E; Kristensen, S R; Kvetny, J

1991-01-01

The specific nuclear binding of triiodothyronine (T3) (NBT3) and the activity of malic enzyme (ME), glucose-6-phosphate-dehydrogenase (G6PD), and 6-phosphogluconate-dehydrogenase (6PGD) were studied in the human fibroblast cell (MRC-5). The overall apparent binding affinity (Ka) was 2.7 x 10(9) L.......mol-1 estimated from kinetic studies of nuclear T3 binding, and 2.5 x 10(9) L.mol-1 estimated from equilibrium studies. The scatchard plots were curvilinear and composed of a high-affinity binding site with Ka1 3.4 +/- 0.7 x 10(9) L.mol-1 and maximal binding capacity (MBC) MBC1 57.0 +/- 11.9 fmol/mg DNA...... and a low-affinity binding site with Ka2 2.9 +/- 1.1 x 10(8) L.mol-1 and MBC2 124.7 +/- 22.1 fmol/mg DNA (n = 6). Incubation of cells with 6 nmol/L T3 for 20 hours reduced NBT3 to 62.2% +/- 15.7% (P less than .01, n = 11). The Ka estimated from kinetic studies was reduced to 6.7 x 10(7) L.mol-1...

Brown adipose tissue improves whole-body glucose homeostasis and insulin sensitivity in humans

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Brown adipose tissue (BAT) has attracted scientific interest as an antidiabetic tissue owing to its ability to dissipate energy as heat. Despite a plethora of data concerning the role of BAT in glucose metabolism in rodents, the role of BAT (if any) in glucose metabolism in humans remains unclear. T...

Alterations of hippocampal glucose metabolism by even versus uneven medium chain triglycerides

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McDonald, Tanya S; Tan, Kah Ni; Hodson, Mark P; Borges, Karin

2014-01-01

Medium chain triglycerides (MCTs) are used to treat neurologic disorders with metabolic impairments, including childhood epilepsy and early Alzheimer's disease. However, the metabolic effects of MCTs in the brain are still unclear. Here, we studied the effects of feeding even and uneven MCTs on brain glucose metabolism in the mouse. Adult mice were fed 35% (calories) of trioctanoin or triheptanoin (the triglycerides of octanoate or heptanoate, respectively) or a matching control diet for 3 weeks. Enzymatic assays and targeted metabolomics by liquid chromatography tandem mass spectrometry were used to quantify metabolites in extracts from the hippocampal formations (HFs). Both oils increased the levels of β-hydroxybutyrate, but no other significant metabolic alterations were observed after triheptanoin feeding. The levels of glucose 6-phosphate and fructose 6-phosphate were increased in the HF of mice fed trioctanoin, whereas levels of metabolites further downstream in the glycolytic pathway and the pentose phosphate pathway were reduced. This indicates that trioctanoin reduces glucose utilization because of a decrease in phosphofructokinase activity. Trioctanoin and triheptanoin showed similar anticonvulsant effects in the 6 Hz seizure model, but it remains unknown to what extent the anticonvulsant mechanism(s) are shared. In conclusion, triheptanoin unlike trioctanoin appears to not alter glucose metabolism in the healthy brain. PMID:24169853

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.

[Phosphate solubilization of Aureobasidium pullulan F4 and its mechanism].

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Wang, Dan; Zhan, Jing; Sun, Qing-Ye

2014-07-01

The Aureobasidium pullulans F4 was isolated from the rhizosphere of Hippochaete ramosissimum in Tongguanshan mine wasteland in Tongling City, Anhui Province. Liquid culture was conducted with four kinds of phosphorus sources, calcium phosphate, aluminum phosphate, ferric phosphate and rock phosphate to determine the pH, dissolved phosphorus, phosphorus in the bacteria and organic acid in the solution. The results showed that the phosphate solubilization by A. pullulans F4 varied with phosphorus sources, which decreased in order of aluminum phosphate > ferric phosphate, calcium phosphate > rock phosphate. The amounts of dissolved phosphorus in the different treatments were all higher than 200 mg x L(-1). The pH of the medium dropped immediately in 48 h, and the aluminum phosphate and ferric phosphate treatments showed a greater decrease in pH than the calcium phosphate and rock phosphate treatments. The organic acid synthesized by A. pullulans F4 included oxalic acid, citric acid and tartaric acid, and oxalic acid, among which oxalic acid was the dominated component. The phosphate dissolving capacity of A. pullulans F4 showed no significant correlation with organic acid, but significantly correlated with the pH. The available phosphorus was significantly improved with the combined application of A. pullulans F4 and glucose, suggesting A. pullulans F4 was a potent candidate for remediation of copper mine wastelands.

Detection of glucose in the human brain with 1 H MRS at 7 Tesla.

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Kaiser, Lana G; Hirokazu, Kawaguchi; Fukunaga, Masaki; B Matson, Gerald

2016-12-01

A new method is proposed for noninvasive detection of glucose in vivo using proton MR spectroscopy at 7 Tesla. The proposed method utilizes J-difference editing to uncover the resonance of beta-glucose (β-glc) at 3.23 ppm, which is strongly overlapped with choline. Calculations using the density matrix formalism are used to maximize the signal-to-noise ratio of the β-glc resonance at 3.23 ppm. The calculations are verified using phantom and in vivo data collected at 7 Tesla. The proposed method allows observation of the glucose signal at 3.23 ppm in the human brain spectrum. Additional co-edited resonances of N-acetylaspartylglutamatate and glutathione are also detected in the same experiment. The proposed method does not require carbon ( 13 C)- labeled glucose injections and 13 C hardware; as such, it has a potential to provide valuable information on intrinsic glucose concentration in the human brain in vivo. Magn Reson Med 76:1653-1660, 2016. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

Calcium phosphate thin films enhance the response of human mesenchymal stem cells to nanostructured titanium surfaces

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Mura M McCafferty

2014-05-01

Full Text Available The development of biomaterial surfaces possessing the topographical cues that can promote mesenchymal stem cell recruitment and, in particular, those capable of subsequently directing osteogenic differentiation is of increasing importance for the advancement of tissue engineering. While it is accepted that it is the interaction with specific nanoscale topography that induces mesenchymal stem cell differentiation, the potential for an attendant bioactive chemistry working in tandem with such nanoscale features to enhance this effect has not been considered to any great extent. This article presents a study of mesenchymal stem cell response to conformal bioactive calcium phosphate thin films sputter deposited onto a polycrystalline titanium nanostructured surface with proven capability to directly induce osteogenic differentiation in human bone marrow–derived mesenchymal stem cells. The sputter deposited surfaces supported high levels of human bone marrow–derived mesenchymal stem cell adherence and proliferation, as determined by DNA quantification. Furthermore, they were also found to be capable of directly promoting significant levels of osteogenic differentiation. Specifically, alkaline phosphatase activity, gene expression and immunocytochemical localisation of key osteogenic markers revealed that the nanostructured titanium surfaces and the bioactive calcium phosphate coatings could direct the differentiation towards an osteogenic lineage. Moreover, the addition of the calcium phosphate chemistry to the topographical profile of the titanium was found to induce increased human bone marrow–derived mesenchymal stem cell differentiation compared to that observed for either the titanium or calcium phosphate coating without an underlying nanostructure. Hence, the results presented here highlight that a clear benefit can be achieved from a surface engineering strategy that combines a defined surface topography with an attendant, conformal

Electrochemical quartz crystal impedance study on immobilization of glucose oxidase in a polymer grown from dopamine oxidation at an Au electrode for glucose sensing

International Nuclear Information System (INIS)

Li Mingrui; Deng Chunyan; Xie Qingji; Yang Yang; Yao Shouzhuo

2006-01-01

Glucose oxidase (GOD) was codeposited into a polymer grown from oxidation of dopamine (DA) at an Au electrode in a neutral phosphate aqueous solution for the first time. The electrochemical quartz crystal impedance analysis (EQCIA) method was used to monitor the GOD-immobilization process. Effects of concentrations of phosphate buffer, DA and GOD were investigated, and the optimal concentrations were found to be 20.0mM phosphate buffer (pH 7.0), 30.0mM DA and 5.00mgml -1 GOD. A glucose biosensor was thus constructed, and effects of various experimental parameters on the sensor performance, including applied potential, solution pH and electroactive interferents, were examined. At an optimal potential of 0.6V versus the KCl-saturated calomel electrode (SCE), the current response of the biosensor in the selected phosphate buffer (pH 7.0) was linear with the concentration of glucose from 0.05 to 9mM, with a lower detection limit of 3μM (S/N=3), short response time (within 15s) and good anti-interferent ability. The Michaelis constant (K m app ) was estimated to be 9.6mM. The biosensor exhibited good storage stability, i.e. 96% of its initial response was retained after 7-day storage in the selected phosphate buffer at 4deg. C, and even after another 3 weeks the biosensor retained 86% of its initial response. In addition, the enzymatic specific activity and enzymatic relative activity of the GOD immobilized in the polymer from dopamine oxidation (PFDO) were estimated from the EQCIA method to be 1.43kUg -1 and 3.7%, respectively, which were larger than the relevant values obtained experimentally using poly(o-aminophenol) and poly(N-methylpyrrole) matrices, suggesting that the PFDO is a better matrix to immobilize GOD

Combined Effect of L-Cysteine and Vitamin E Injected Pre-Irradiation on Glucose-6-Phosphate Dehydrogenase Activity and Certain products of Glycolysis in Blood of Female Rats

International Nuclear Information System (INIS)

Abdel-Fattah, K.I.; Abou-Safi, H.M.; Kafafy, Y.A.; Ashry, O.M.

1999-01-01

The present work aims to evaluate the protective limits of L-cysteine and vitamin E combination against deleterious effects of gamma radiation on glucose-6-phosphate dehydrogenase activity, liver glycogen, blood glucose, pyruvic and lactic acids and their correlations in adult female rats. Mature female white rats were divided into four groups: 1- Control group. 2- Whole body gamma irradiated group at a dose level two Gy. 3-Group injected with 120 mg/100 g b.wt. L-cysteine+10 mg/100 g b.wt. vitamin E. 4- Group injected with cysteine+ vitamin E one hour before irradiation at 2 Gy dose level. Results revealed that combined administration of cysteine and vitamin E before gamma-irradiation have accelerated the radiation injury on liver glycogen, plasma glucose and G 6 Pd activity, while they showed a protective effect on lactic and pyruvic acids. This could be due to different mechanisms or a biphasic mechanism related to hormonal (like E 2 , T 3 and insulin), enzymatic or metabolic (e.g. oxidation/reduction, catabolic, anabolic factors) control

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

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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.

Isolation of phosphatase-producing phosphate solubilizing bacteria from Loriya hot spring: Investigation of phosphate solubilizing in the presence of different parameters

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Maryam Parhamfar

2014-04-01

Full Text Available Introduction: Biofertilizers are the microorganisms that can convert useless nutrient to usable compounds. Unlike fertilizer, cost of biofertilizer production is low and doesn’t produce ecosystem pollution. Phosphate fertilizers can be replaced by phosphate biofertilizer to produce improvement. So, it is necessary to screen the climate-compatible phosphate solubilizing bacteria. Materials and methods: In this project samples were picked up from Loriya hot spring, which are located in Jiroft. Samples were incubated in PKV medium for 3 days. Screening of phosphate solubilizing bacteria was performed on the specific media, based on clear area diameter. The best bacterium was identified based on 16s rDNA gene. Phosphate solubilizing activity of this strain was considered in different carbon, nitrogen, phosphate and pH sources. Results: Sequence alignment and phylogenetic tree results show that B. sp. LOR033 is closely related to Bacillus licheniformis, with 97% homology. In addition, results show that maximum enzyme production was performed after 2 days that incubation pH was decreased simultaneously when the time was increased. Carbon sources investigation show that glucose is the most appropriate in enzyme production and phosphate releasing. Furthermore, results show that the optimum initial pH for phytase production was pH5.0. Different phosphate sources show that tricalcium phosphate has the suitable effect on enzyme activity in three days of incubation. Discussion and conclusion: Phosphatase enzyme production capacity, growth in acidic pH and phosphate solubilizing potential in different salt and phosphate sources show that this strain has considerable importance as biofertilizers.

Glucose consumption and rate constants for sup 18 F-fluorodeoxyglucose in human gliomas

Energy Technology Data Exchange (ETDEWEB)

Ishikawa, Masatsune; Kikuchi, Haruhiko; Nagata, Izumi; Yamagata, Sen; Taki, Waro; Yonekura, Yoshiharu; Nishizawa, Sadahiko; Iwasaki, Yasushi; Mukai, Takao [Kyoto Univ. (Japan). Faculty of Medicine

1990-06-01

To investigate the value of direct measurement of the rate constants by performing {sup 18}F-labeled fluorodeoxyglucose (FDG) studies of glucose consumption in human gliomas in vivo, a kinetic method with 3- and 4-parameter rate constant models for FDG uptake was used to analyze data from dynamic scans obtained by positron emission tomography after injection of FDG into 14 patients with glioma. The results were compared with those obtained by the autoradiographic method using 3- and 4-parameter rate constant models. There were no significant differences in the glucose consumption calculated by the four different methods both in the gliomas and in the contralateral intact cortex. It was found that the rate constant k4 could be neglected in calculation of glucose consumption in gliomas as well as in the contralateral intact cortex. The rate constant k3, an index of hexokinase function, was higher in malignant gliomas than in benign gliomas and was close to that in the contralateral cortex. This study indicates that the 3-parameter autoradiographic method, which is the most common one used in clinical practice, is reliable for the calculation of glucose consumption in human gliomas. Furthermore, direct measurement of the regional rate constants for FDG by the kinetic method was found to be useful for evaluation of the biochemical and physiological characteristics of human gliomas in vivo. (author).

Different apoptotic responses of human and bovine pericytes to fluctuating glucose levels and protective role of thiamine.

Science.gov (United States)

Beltramo, Elena; Berrone, Elena; Tarallo, Sonia; Porta, Massimo

2009-09-01

Vascular cells in diabetes are subjected to daily fluctuations from high to low glucose. We aimed at investigating whether pulsed exposure to different glucose concentrations influences apoptosis in human retinal pericytes (HRP) versus bovine retinal pericytes (BRP), with consequences on the onset of diabetic retinopathy, and the possible protective role of thiamine. BRP and HRP (wild-type and immortalized) were grown in physiological/high glucose for 7 days, and then returned to physiological glucose for another 24, 48 or 72 h. Cells were also kept intermittently at 48-h intervals in high/normal glucose for 8 days, with/without thiamine/benfotiamine. Apoptosis was determined through ELISA, TUNEL, Bcl-2, Bax and p53 expression/concentration. Continuous exposure to high glucose increased apoptosis in BRP, but not HRP. BRP apoptosis normalized within 24 h of physiological glucose re-entry, while HRP apoptosis increased within 24-48 h of re-entry. Intermittent exposure to high glucose increased apoptosis in HRP and BRP. Bcl-2/Bax results were consistent with DNA fragmentation, while p53 was unchanged. Thiamine and benfotiamine countered intermittent high glucose-induced apoptosis. Human pericytes are less prone to apoptosis induced by persistently high glucose than bovine cells. However, while BRP recover after returning to physiological levels, HRP are more vulnerable to both downwardly fluctuating glucose levels and intermittent exposure. These findings reinforce the hypotheses that (1) glycaemic fluctuations play a role in the development of diabetic retinopathy and (2) species-specific models are needed. Thiamine and benfotiamine prevent human pericyte apoptosis, indicating this vitamin as an inexpensive approach to the prevention and/or treatment of diabetic complications.

In Vitro Effects of Imidacloprid and Lambda-cyhalothrin on Capoeta capoeta umbla Kidney Glucose 6-Phosphate Dehydrogenase Enzyme

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Mahinur KIRICI

2015-03-01

Full Text Available Pesticide toxicity causes oxidative damage such as DNA damage, enhanced lipid peroxidation, the oxidation of protein sulfydryl groups and enzyme inactivation in the metabolism. In this study, we investigated the in vitro effects on glucose 6-phosphate dehydrogenase (E.C.1.1.49; G6PD from Capoeta capoeta umbla kidney of imidacloprid and lambda-cyhalothrin. For this purpose, the enzymewas purified from kidney of C. c. umbla with a specific activity of 11.26 EU mg-1 proteins and 22.7% yield using hemolysate preparation, ammonium sulfate precipitation and 2',5'-ADP Sepharose 4B affinity gel chromatography methods. In order to control the enzyme purification sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE was done. SDS-PAGE showed a single band for the enzyme. The results of this study suggested that imidacloprid and lambda-cyhalothrin have significant inhibition effect on the activity of G6PD in in vitro. In conclusion, lambda-cyhalothrin inhibits the enzyme activity more than imidacloprid.

Differential Mueller matrix polarimetry technique for non-invasive measurement of glucose concentration on human fingertip.

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Phan, Quoc-Hung; Lo, Yu-Lung

2017-06-26

A differential Mueller matrix polarimetry technique is proposed for obtaining non-invasive (NI) measurements of the glucose concentration on the human fingertip. The feasibility of the proposed method is demonstrated by detecting the optical rotation angle and depolarization index of tissue phantom samples containing de-ionized water (DI), glucose solutions with concentrations ranging from 0~500 mg/dL and 2% lipofundin. The results show that the extracted optical rotation angle increases linearly with an increasing glucose concentration, while the depolarization index decreases. The practical applicability of the proposed method is demonstrated by measuring the optical rotation angle and depolarization index properties of the human fingertips of healthy volunteers.

RXR agonists inhibit high glucose-induced upregulation of inflammation by suppressing activation of the NADPH oxidase-nuclear factor-κB pathway in human endothelial cells.

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Ning, R B; Zhu, J; Chai, D J; Xu, C S; Xie, H; Lin, X Y; Zeng, J Z; Lin, J X

2013-12-13

An inflammatory response induced by high glucose is a cause of endothelial dysfunction in diabetes and is an important contributing link to atherosclerosis. Diabetes is an independent risk factor of atherosclerosis and activation of retinoid X receptor (RXR) has been shown to exert anti-atherogenic effects. In the present study, we examined the effects of the RXR ligands 9-cis-retinoic acid (9-cis-RA) and SR11237 on high glucose-induced inflammation in human umbilical endothelial vein endothelial cells (HUVECs) and explored the potential mechanism. Our results showed that the inflammation induced by high-glucose in HUVECs was mainly mediated by the activation of nuclear factor-B (NF- κB). High glucose-induced expression of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) were in comparison, significantly decreased by treatment with RXR. The effect of RXR agonists was mainly due to the inhibition of NF-κB activation. Using pharmacological inhibitors and siRNA, we confirmed that nicotinamide adenine dinucleotide phosphate (NADPH) oxidase was an upstream activator of NF-κB. Furthermore, RXR agonists significantly inhibited high glucose-induced activation of NADPH oxidase and significantly decreased the production of reactive oxygen species (ROS). To explore whether the rapid inhibitory effects of RXR agonists were in fact mediated by RXR, we examined the effect of RXR downregulation by RXR siRNA. Our results showed that RXR siRNA largely abrogated the effects of RXR agonists, suggesting the requirement of RXR expression. Therefore, we have shown that RXR is involved in the regulation of NADPH oxidase- NF-κB signal pathway, as the RXR ligands antagonized the inflammatory response in HUVECs induced by high glucose.

The human hepatocyte cell lines IHH and HepaRG: models to study glucose, lipid and lipoprotein metabolism.

Science.gov (United States)

Samanez, Carolina Huaman; Caron, Sandrine; Briand, Olivier; Dehondt, Hélène; Duplan, Isabelle; Kuipers, Folkert; Hennuyer, Nathalie; Clavey, Véronique; Staels, Bart

2012-07-01

Metabolic diseases reach epidemic proportions. A better knowledge of the associated alterations in the metabolic pathways in the liver is necessary. These studies need in vitro human cell models. Several human hepatoma models are used, but the response of many metabolic pathways to physiological stimuli is often lost. Here, we characterize two human hepatocyte cell lines, IHH and HepaRG, by analysing the expression and regulation of genes involved in glucose and lipid metabolism. Our results show that the glycolysis pathway is activated by glucose and insulin in both lines. Gluconeogenesis gene expression is induced by forskolin in IHH cells and inhibited by insulin in both cell lines. The lipogenic pathway is regulated by insulin in IHH cells. Finally, both cell lines secrete apolipoprotein B-containing lipoproteins, an effect promoted by increasing glucose concentrations. These two human cell lines are thus interesting models to study the regulation of glucose and lipid metabolism.

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.

Generalized decrease in brain glucose metabolism during fasting in humans studied by PET

International Nuclear Information System (INIS)

Redies, C.; Hoffer, L.J.; Beil, C.

1989-01-01

In prolonged fasting, the brain derives a large portion of its oxidative energy from the ketone bodies, beta-hydroxybutyrate and acetoacetate, thereby reducing whole body glucose consumption. Energy substrate utilization differs regionally in the brain of fasting rat, but comparable information has hitherto been unavailable in humans. We used positron emission tomography (PET) to study regional brain glucose and oxygen metabolism, blood flow, and blood volume in four obese subjects before and after a 3-wk total fast. Whole brain glucose utilization fell to 54% of control (postabsorptive) values (P less than 0.002). The whole brain rate constant for glucose tracer phosphorylation fell to 51% of control values (P less than 0.002). Both parameters decreased uniformly throughout the brain. The 2-fluoro-2-deoxy-D-glucose lumped constant decreased from a control value of 0.57 to 0.43 (P less than 0.01). Regional blood-brain barrier transfer coefficients for glucose tracer, regional oxygen utilization, blood flow, and blood volume were unchanged

Glucose dynamics and mechanistic implications of SGLT2 inhibitors in animals and humans.

Science.gov (United States)

List, James F; Whaley, Jean M

2011-03-01

Glucose is freely filtered in the glomeruli before being almost entirely reabsorbed into circulation from the proximal renal tubules. The sodium-glucose cotransporter 2 (SGLT2), present in the S1 segment of the proximal tubule, is responsible for the majority of glucose reabsorption. SGLT2 inhibitors reduce glucose reabsorption and increase urinary glucose excretion. In animal models and humans with type 2 diabetes, this effect is associated with reduced fasting and postprandial blood glucose levels, and reduced hemoglobin A1c. Animal studies suggest that reduction of hyperglycemia with SGLT2 inhibitors may also improve insulin sensitivity and preserve β-cell function. Urinary excretion of excess calories with SGLT2 inhibitors is also associated with reduction in body weight. Modest reductions in blood pressure have been noted with SGLT2 inhibitors, consistent with a mild diuretic action. Some C-glucoside SGLT2 inhibitors, such as dapagliflozin, have pharmacokinetic properties that make them amenable to once-daily dosing.

Benfotiamine increases glucose oxidation and downregulates NADPH oxidase 4 expression in cultured human myotubes exposed to both normal and high glucose concentrations.

Science.gov (United States)

Fraser, D A; Hessvik, N P; Nikolić, N; Aas, V; Hanssen, K F; Bøhn, S K; Thoresen, G H; Rustan, A C

2012-07-01

The aim of the present work was to study the effects of benfotiamine (S-benzoylthiamine O-monophosphate) on glucose and lipid metabolism and gene expression in differentiated human skeletal muscle cells (myotubes) incubated for 4 days under normal (5.5 mM glucose) and hyperglycemic (20 mM glucose) conditions. Myotubes established from lean, healthy volunteers were treated with benfotiamine for 4 days. Glucose and lipid metabolism were studied with labeled precursors. Gene expression was measured using real-time polymerase chain reaction (qPCR) and microarray technology. Benfotiamine significantly increased glucose oxidation under normoglycemic (35 and 49% increase at 100 and 200 μM benfotiamine, respectively) as well as hyperglycemic conditions (70% increase at 200 μM benfotiamine). Benfotiamine also increased glucose uptake. In comparison, thiamine (200 μM) increased overall glucose metabolism but did not change glucose oxidation. In contrast to glucose, mitochondrial lipid oxidation and overall lipid metabolism were unchanged by benfotiamine. The expression of NADPH oxidase 4 (NOX4) was significantly downregulated by benfotiamine treatment under both normo- and hyperglycemic conditions. Gene set enrichment analysis (GSEA) showed that befotiamine increased peroxisomal lipid oxidation and organelle (mitochondrial) membrane function. In conclusion, benfotiamine increases mitochondrial glucose oxidation in myotubes and downregulates NOX4 expression. These findings may be of relevance to type 2 diabetes where reversal of reduced glucose oxidation and mitochondrial capacity is a desirable goal.

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

Hepatic glycogen in humans. II. Gluconeogenetic formation after oral and intravenous glucose

International Nuclear Information System (INIS)

Radziuk, J.

1989-01-01

The amount of glycogen that is formed by gluconeogenetic pathways during glucose loading was quantitated in human subjects. Oral glucose loading was compared with its intravenous administration. Overnight-fasted subjects received a constant infusion or [3- 3 H]glucose and a marker for gluconeogenesis, [U- 14 C]lactate or sodium [ 14 C]bicarbonate [ 14 C]bicarbonate. An unlabeled glucose load was then administered. Postabsorptively, or after glucose infusion was terminated, a third tracer ([6- 3 H]glucose) infusion was initiated along with a three-step glucagon infusion. Without correcting for background stimulation of [ 14 C]glucose production or for dilution of 14 C with citric acid cycle carbon in the oxaloacetate pool, the amount of glycogen mobilized by the glucagon infusion that was produced by gluconeogenesis during oral glucose loading was 2.9 +/- 0.7 g calculated from [U- 14 C]-lactate incorporation and 7.4 +/- 1.3 g calculated using [ 14 C]bicarbonate as a gluconeogenetic marker. During intravenous glucose administration the latter measurement also yielded 7.2 +/- 1.1 g. When the two corrections above are applied, the respective quantities became 5.3 +/- 1.7 g for [U- 14 C]lactate as tracer and 14.7 +/- 4.3 and 13.9 +/- 3.6 g for oral and intravenous glucose with [ 14 C]bicarbonate as tracer (P less than 0.05, vs. [ 14 C]-lactate as tracer). When [2- 14 C]acetate was infused, the same amount of label was incorporated into mobilized glycogen regardless of which route of glucose administration was used. Comparison with previous data also suggests that 14 CO 2 is a potentially useful marker for the gluconeogenetic process in vivo

Volume I. Glycogen: A historical overview, an adjunct to thesis. Volume II. Non-glucose components of glycogen

International Nuclear Information System (INIS)

Kirkman, B.R.

1988-01-01

Investigations have been carried out on three non-glucose components of native glycogen: protein, glucosamine, and phosphate. The protein, glycogenin, appears to serve as the primer upon which new molecules of glycogen are synthesized. When cell extracts are incubated with ( 14 C)UDPG, ( 14 C)glucose becomes transferred onto pre-existing chains of alpha-1,4 linked glucose associated with free glycogenin. The transferase and glycogenin remain associated during various purification steps. Liver glycogen appears to contain less than 0.02% protein which may correspond to the presence of one molecule of glycogenin (37 kDa) per alpha particle of liver glycogen. The core beta particle within each alpha particle may be synthesized upon glycogenin, while the remaining 20-40 beta particles may arise from each other. The author has demonstrated the natural occurrence of glucosamine in liver glycogen (but not muscle glycogen) from various species in an amount of about one molecule per molecule of glycogen. The glucosamine is underivatized, appears to be randomly scattered in the glycogen, and may be derived from dietary galactosamine. Similar to Fontana (1980), the author observed that native liver glycogen could be fractionated on DEAE-cellulose apparently on the basis of phosphate content. The more strongly bound glycogen possessed a greater molecular weight and content of glucosamine and phosphate. Possible explanations for these subfractions are considered. The phosphate appears to be concentrated near the center of the glycogen molecules. About 30% appears to be associated with glucose-6P and the remainder with an unidentified phosphodiester. The phosphate may stimulate glycogen synthesis. How the phosphate becomes incorporated is unknown

Kinetics of formation of acrylamide and Schiff base intermediates from asparagine and glucose

DEFF Research Database (Denmark)

Hedegaard, Rikke Susanne Vingborg; Frandsen, Henrik; Skibsted, Leif H.

2008-01-01

From the concentration of glucose and asparagine as reactants and of acrylamide as product each determined by LC-MS during reaction in an acetonitrile/water (68:32) model system at pH 7.6 (0.04 M phosphate buffer) and from the relative concentration of the Schiff base intermediate, the decarboxyl......From the concentration of glucose and asparagine as reactants and of acrylamide as product each determined by LC-MS during reaction in an acetonitrile/water (68:32) model system at pH 7.6 (0.04 M phosphate buffer) and from the relative concentration of the Schiff base intermediate...

Oral antibodies to human intestinal alkaline phosphatase reduce dietary phytate phosphate bioavailability in the presence of dietary 1α-hydroxycholecalciferol.

Science.gov (United States)

Bobeck, Elizabeth A; Hellestad, Erica M; Helvig, Christian F; Petkovich, P Martin; Cook, Mark E

2016-03-01

While it is well established that active vitamin D treatment increases dietary phytate phosphate utilization, the mechanism by which intestinal alkaline phosphatase (IAP) participates in phytate phosphate use is less clear. The ability of human IAP (hIAP) oral antibodies to prevent dietary phytate phosphate utilization in the presence of 1α-hydroxycholecalciferol (1α-(OH) D3) in a chick model was investigated. hIAP specific chicken immunoglobulin Y (IgY) antibodies were generated by inoculating laying hens with 17 synthetic peptides derived from the human IAP amino acid sequence and harvesting egg yolk. Western blot analysis showed all antibodies recognized hIAP and 6 of the 8 antibodies selected showed modest inhibition of hIAP activity in vitro (6 to 33% inhibition). In chicks where dietary phosphate was primarily in the form of phytate, 4 selected hIAP antibodies inhibited 1α-(OH) D3-induced increases in blood phosphate, one of which, generated against selected peptide (MFPMGTPD), was as effective as sevelamer hydrochloride in preventing the 1α-(OH) D3-induced increase in blood phosphate, but ineffective in preventing an increase in body weight gain and bone ash induced by 1α-(OH) D3. These studies demonstrated that orally-delivered antibodies to IAP limit dietary phytate-phosphate utilization in chicks treated with 1α-(OH) D3, and implicate IAP as an important host enzyme in increasing phytate phosphate bioavailability in 1α-(OH) D3 fed chicks. © 2015 Poultry Science Association Inc.

ONLINE MONITORING OF EXTRACELLULAR BRAIN GLUCOSE USING MICRODIALYSIS AND A NADPH-LINKED ENZYMATIC ASSAY

NARCIS (Netherlands)

VANDERKUIL, JHF; KORF, J

A method to monitor extracellular glucose in freely moving rats, based on intracerebral microdialysis coupled to an enzyme reactor is described. The dialysate is continuously mixed with a solution containing the enzymes hexokinase and glucose-6-phosphate dehydrogenase, and the fluorescence of NADPH

Inhibition of catalase by aminotriazole in vivo results in reduction of glucose-6-phosphate dehydrogenase activity in Saccharomyces cerevisiae cells.

Science.gov (United States)

Bayliak, M; Gospodaryov, D; Semchyshyn, H; Lushchak, V

2008-04-01

The inhibitor of catalase 3-amino-1,2,4-triazole (AMT) was used to study the physiological role of catalase in the yeast Saccharomyces cerevisiae under starvation. It was shown that AMT at the concentration of 10 mM did not affect the growth of the yeast. In vivo and in vitro the degree of catalase inhibition by AMT was concentration- and time-dependent. Peroxisomal catalase in bakers' yeast was more sensitive to AMT than the cytosolic one. In vivo inhibition of catalase by AMT in S. cerevisiae caused a simultaneous decrease in glucose-6-phosphate dehydrogenase activity and an increase in glutathione reductase activity. At the same time, the level of protein carbonyls, a marker of oxidative modification, was not affected. Possible mechanisms compensating the negative effects caused by AMT inhibition of catalase are discussed.

The influence of SrO and CaO in silicate and phosphate bioactive glasses on human gingival fibroblasts.

Science.gov (United States)

Massera, J; Kokkari, A; Närhi, T; Hupa, L

2015-06-01

In this paper, we investigate the effect of substituting SrO for CaO in silicate and phosphate bioactive glasses on the human gingival fibroblast activity. In both materials the presence of SrO led to the formation of a CaP layer with partial Sr substitution for Ca. The layer at the surface of the silicate glass consisted of HAP whereas at the phosphate glasses it was close to the DCPD composition. In silicate glasses, SrO gave a faster initial dissolution and a thinner reaction layer probably allowing for a continuous ion release into the solution. In phosphate glasses, SrO decreased the dissolution process and gave a more strongly bonded reaction layer. Overall, the SrO-containing silicate glass led to a slight enhancement in the activity of the gingival fibroblasts cells when compared to the SrO-free reference glass, S53P4. The cell activity decreased up to 3 days of culturing for all phosphate glasses containing SrO. Whereas culturing together with the SrO-free phosphate glass led to complete cell death at 7 days. The glasses containing SrO showed rapid cell proliferation and growth between 7 and 14 days, reaching similar activity than glass S53P4. The addition of SrO in both silicate and phosphate glasses was assumed beneficial for proliferation and growth of human gingival fibroblasts due to Sr incorporation in the reaction layer at the glass surface and released in the cell culture medium.

Calcium-Phosphate-Osteopontin Particles Reduce Biofilm Formation and pH Drops in in situ Grown Dental Biofilms.

Science.gov (United States)

Schlafer, Sebastian; Ibsen, Casper J S; Birkedal, Henrik; Nyvad, Bente

2017-01-01

This 2-period crossover study investigated the effect of calcium-phosphate-osteopontin particles on biofilm formation and pH in 48-h biofilms grown in situ. Bovine milk osteopontin is a highly phosphorylated glycoprotein that has been shown to interfere with bacterial adhesion to salivary-coated surfaces. Calcium-phosphate-osteopontin particles have been shown to reduce biofilm formation and pH drops in a 5-species laboratory model of dental biofilm without affecting bacterial viability. Here, smooth surface biofilms from 10 individuals were treated ex vivo 6 times/day for 30 min with either calcium-phosphate-osteopontin particles or sterile saline. After growth, the amount of biofilm formed was determined by confocal microscopy, and pH drops upon exposure to glucose were monitored using confocal-microscopy-based pH ratiometry. A total of 160 biofilms were analysed. No adverse effects of repeated ex vivo treatment with calcium-phosphate-osteopontin particles were observed. Particle treatment resulted in a 32% lower amount of biofilm formed (p Biofilm pH was significantly higher upon particle treatment, both shortly after the addition of glucose and after 30 min of incubation with glucose (p biofilms as well as the remineralizing potential of the particles. © 2016 S. Karger AG, Basel.

The effect of caffeine on glucose kinetics in humans - influence of adrenaline

DEFF Research Database (Denmark)

Battram, Danielle S.; Graham, Terry E.; Richter, Erik

2005-01-01

While caffeine impedes insulin-mediated glucose disposal in humans, its effect on endo-genous glucose production (EGP) remains unknown. In addition, the mechanism involved in these effects is unclear, but may be due to the accompanying increase in adrenaline concentration. We studied the effect...... of caffeine on EGP and glucose infusion rates (GIR), and whether or not adrenaline can account for all of caffeine's effects. Subjects completed three isoglycaemic-hyperinsulinaemic clamps (with 3-[3H]glucose infusion) 30 min after ingesting: (1) placebo capsules (n= 12); (2) caffeine capsules (5 mg kg-1) (n......= 12); and either (3) placebo plus a high-dose adrenaline infusion (HAdr; adrenaline concentration, 1.2 nM; n= 8) or (4) placebo plus a low-dose adrenaline infusion (LAdr; adrenaline concentration, 0.75 nM; n= 6). With caffeine, adrenaline increased to 0.6 nM but no effect on EGP was observed. While...

Prevalence of thalassaemia, iron-deficiency anaemia and glucose-6-phosphate dehydrogenase deficiency among Arab migrating nomad children, southern Islamic Republic of Iran.

Science.gov (United States)

Pasalar, M; Mehrabani, D; Afrasiabi, A; Mehravar, Z; Reyhani, I; Hamidi, R; Karimi, M

2014-12-17

This study investigated the prevalence of iron-deficiency anaemia, glucose-6-phosphate dehydrogenase (G6PD) deficiency and β-thalassaemia trait among Arab migrating nomad children in southern Islamic Republic of Iran. Blood samples were analysed from 134 schoolchildren aged child had G6PD deficiency. A total of 9.7% of children had HbA2 ≥ 3.5 g/dL, indicating β-thalassaemia trait (10.8% in females and 7.8% in males). Mean serum iron, serum ferritin and total iron binding capacity were similar in males and females. Serum ferritin index was as accurate as Hb index in the diagnosis of iron-deficiency anaemia. A high prevalence of β-thalassaemia trait was the major potential risk factor in this population.

A new human NHERF1 mutation decreases renal phosphate transporter NPT2a expression by a PTH-independent mechanism.

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Marie Courbebaisse

Full Text Available BACKGROUND: The sodium-hydrogen exchanger regulatory factor 1 (NHERF1 binds to the main renal phosphate transporter NPT2a and to the parathyroid hormone (PTH receptor. We have recently identified mutations in NHERF1 that decrease renal phosphate reabsorption by increasing PTH-induced cAMP production in the renal proximal tubule. METHODS: We compared relevant parameters of phosphate homeostasis in a patient with a previously undescribed mutation in NHERF1 and in control subjects. We expressed the mutant NHERF1 protein in Xenopus Oocytes and in cultured cells to study its effects on phosphate transport and PTH-induced cAMP production. RESULTS: We identified in a patient with inappropriate renal phosphate reabsorption a previously unidentified mutation (E68A located in the PDZ1 domain of NHERF1.We report the consequences of this mutation on NHERF1 function. E68A mutation did not modify cAMP production in the patient. PTH-induced cAMP synthesis and PKC activity were not altered by E68A mutation in renal cells in culture. In contrast to wild-type NHERF1, expression of the E68A mutant in Xenopus oocytes and in human cells failed to increase phosphate transport. Pull down experiments showed that E68A mutant did not interact with NPT2a, which robustly interacted with wild type NHERF1 and previously identified mutants. Biotinylation studies revealed that E68A mutant was unable to increase cell surface expression of NPT2a. CONCLUSIONS: Our results indicate that the PDZ1 domain is critical for NHERF1-NPT2a interaction in humans and for the control of NPT2a expression at the plasma membrane. Thus we have identified a new mechanism of renal phosphate loss and shown that different mutations in NHERF1 can alter renal phosphate reabsorption via distinct mechanisms.

Effects of dehydroepiandrosterone (DHEA) on glucose metabolism in isolated hepatocytes from Zucker rats

International Nuclear Information System (INIS)

Finan, A.; Cleary, M.P.

1986-01-01

DHEA has been shown to competitively inhibit the pentose phosphate shunt (PPS) enzyme glucose-6-phosphate dehydrogenase (G6PD) when added in vitro to supernatants or homogenates prepared from mammalian tissues. However, no consistent effect on G6PD activity has been determined in tissue removed from DHEA-treated rats. To explore the effects of DHEA on PPS, glucose utilization was measured in hepatocytes from lean and obese male Zucker rats (8 wks of age) following 1 wk of DHEA treatment (0.6% in diet). Incubation of isolated hepatocytes from treated lean Zucker rats with either [1- 14 C] glucose or [6- 14 C] glucose resulted in significant decreases in CO 2 production and total glucose utilization. DHEA-lean rats also had lowered fat pad weights. In obese rats, there was no effect of 1 wk of treatment on either glucose metabolism or fat pad weight. The calculated percent contribution of the PPS to glucose metabolism in hepatocytes was not changed for either DHEA-lean or obese rats when compared to control rats. In conclusion, 1 wk of DHEA treatment lowered overall glucose metabolism in hepatocytes of lean Zucker rats, but did not selectively affect the PPS. The lack of an effect of short-term treatment in obese rats may be due to differences in their metabolism or storage/release of DHEA in tissues in comparison to lean rats

Thermal decomposition of specifically phosphorylated D-glucoses and their role in the control of the Maillard reaction.

Science.gov (United States)

Yaylayan, Varoujan A; Machiels, David; Istasse, Louis

2003-05-21

One of the main shortcomings of the information available on the Maillard reaction is the lack of knowledge to control the different pathways, especially when it is desired to direct the reaction away from the formation of carcinogenic and other toxic substances to more aroma and color generation. The use of specifically phosphorylated sugars may impart some elements of control over the aroma profile generated by the Maillard reaction. Thermal decomposition of 1- and 6-phosphorylated glucoses was studied in the presence and absence of ammonia and selected amino acids through pyrolysis/gas chromatography/mass spectrometry using nonpolar PLOT and medium polar DB-1 columns. The analysis of the data has indicated that glucose-1-phosphate relative to glucose undergoes more extensive phosphate-catalyzed ring opening followed by formation of sugar-derived reactive intermediates as was indicated by a 9-fold increase in the amount of trimethylpyrazine and a 5-fold increase in the amount of 2,3-dimethylpyrazine, when pyrolyzed in the presence of glycine. In addition, glucose-1-phosphate alone generated a 6-fold excess of acetol as compared to glucose. On the other hand, glucose-6-phosphate enhanced retro-aldol reactions initiated from a C-6 hydroxyl group and increased the subsequent formation of furfural and 4-cyclopentene-1,3-dione. Furthermore, it also stabilized 1- and 3-deoxyglucosone intermediates and enhanced the formation of six carbon atom-containing Maillard products derived directly from them through elimination reactions such as 1,6-dimethyl-2,4-dihydroxy-3-(2H)-furanone (acetylformoin), 2-acetylpyrrole, 5-methylfurfural, 5-hydroxymethylfurfural, and 4-hydroxy-2,5-dimethyl-3-(2H)-furanone (Furaneol), due to the enhanced leaving group ability of the phosphate moiety at the C-6 carbon. However, Maillard products generated through the nucleophilic action of the C-6 hydroxyl group such as 2-acetylfuran and 2,3-dihydro-3,5-dihydroxy-4H-pyran-4-one were retarded, due

21 CFR 582.1781 - Sodium aluminum phosphate.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Sodium aluminum phosphate. 582.1781 Section 582.1781 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... Additives § 582.1781 Sodium aluminum phosphate. (a) Product. Sodium aluminum phosphate. (b) Conditions of...

21 CFR 182.1781 - Sodium aluminum phosphate.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Sodium aluminum phosphate. 182.1781 Section 182.1781 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... Food Substances § 182.1781 Sodium aluminum phosphate. (a) Product. Sodium aluminum phosphate. (b...

Humans Can Taste Glucose Oligomers Independent of the hT1R2/hT1R3 Sweet Taste Receptor.

Science.gov (United States)

Lapis, Trina J; Penner, Michael H; Lim, Juyun

2016-08-23

It is widely accepted that humans can taste mono- and disaccharides as sweet substances, but they cannot taste longer chain oligo- and polysaccharides. From the evolutionary standpoint, the ability to taste starch or its oligomeric hydrolysis products would be highly adaptive, given their nutritional value. Here, we report that humans can taste glucose oligomer preparations (average degree of polymerization 7 and 14) without any other sensorial cues. The same human subjects could not taste the corresponding glucose polymer preparation (average degree of polymerization 44). When the sweet taste receptor was blocked by lactisole, a known sweet inhibitor, subjects could not detect sweet substances (glucose, maltose, and sucralose), but they could still detect the glucose oligomers. This suggests that glucose oligomer detection is independent of the hT1R2/hT1R3 sweet taste receptor. Human subjects described the taste of glucose oligomers as "starchy," while they describe sugars as "sweet." The dose-response function of glucose oligomer was also found to be indistinguishable from that of glucose on a molar basis. © The Author 2016. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

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,

Differential Responses of Plasma Adropin Concentrations To Dietary Glucose or Fructose Consumption In Humans.

Science.gov (United States)

Butler, Andrew A; St-Onge, Marie-Pierre; Siebert, Emily A; Medici, Valentina; Stanhope, Kimber L; Havel, Peter J

2015-10-05

Adropin is a peptide hormone encoded by the Energy Homeostasis Associated (ENHO) gene whose physiological role in humans remains incompletely defined. Here we investigated the impact of dietary interventions that affect systemic glucose and lipid metabolism on plasma adropin concentrations in humans. Consumption of glucose or fructose as 25% of daily energy requirements (E) differentially affected plasma adropin concentrations (P Glucose consumption reduced plasma adropin from 3.55 ± 0.26 to 3.28 ± 0.23 ng/ml (N = 42). Fructose consumption increased plasma adropin from 3.63 ± 0.29 to 3.93 ± 0.34 ng/ml (N = 45). Consumption of high fructose corn syrup (HFCS) as 25% E had no effect (3.43 ± 0.32 versus 3.39 ± 0.24 ng/ml, N = 26). Overall, the effect of glucose, HFCS and fructose on circulating adropin concentrations were similar to those observed on postprandial plasma triglyceride concentrations. Furthermore, increases in plasma adropin levels with fructose intake were most robust in individuals exhibiting hypertriglyceridemia. Individuals with low plasma adropin concentrations also exhibited rapid increases in plasma levels following consumption of breakfasts supplemented with lipids. These are the first results linking plasma adropin levels with dietary sugar intake in humans, with the impact of fructose consumption linked to systemic triglyceride metabolism. In addition, dietary fat intake may also increase circulating adropin concentrations.

Modulation of low dose radiation effect on pentose phosphate pathway enzymes by B-multivitamin deficiency

International Nuclear Information System (INIS)

Zimatkina, T.I.; Lashak, L.K.; Moiseenok, A.G.

1997-01-01

Blood, liver, thymus and spleen of albino rats injected subcutaneously with antivitamins (othythiamine and methotrexate) and subjected to prolonger γ-irradiation in the overall dose of 0.75 Gy were assayed for transketolase and glucose-6-phosphate dehydrogenase after 12h, 1, 2, 5 and 40 days from the last radiation dose. High transketolase sensitivity was found both to radiation (activation) and the combined effects of vitamin deficiency and radiation (potentiation of antivitamin inhibitory action) in all the tissues studied. The activity of glucose-6-phosphate dehydrogenase was little changed under the given experimental manipulations, but the combined effect of the factors considerably inhibited the enzyme activities in the organs of the immune system. Consequently, in B-multivitamin deficiency the effect of low radiation doses was subjected to a considerable modulation resulting in profound inhibition of the oxidation and nonoxidative branches of the pentose phosphate pathway. (author). 9 refs, 2 tabs

Hyperpolarized [U-(2) H, U-(13) C]Glucose reports on glycolytic and pentose phosphate pathway activity in EL4 tumors and glycolytic activity in yeast cells.

Science.gov (United States)

Timm, Kerstin N; Hartl, Johannes; Keller, Markus A; Hu, De-En; Kettunen, Mikko I; Rodrigues, Tiago B; Ralser, Markus; Brindle, Kevin M

2015-12-01

A resonance at ∼181 ppm in the (13) C spectra of tumors injected with hyperpolarized [U-(2) H, U-(13) C]glucose was assigned to 6-phosphogluconate (6PG), as in previous studies in yeast, whereas in breast cancer cells in vitro this resonance was assigned to 3-phosphoglycerate (3PG). These peak assignments were investigated here using measurements of 6PG and 3PG (13) C-labeling using liquid chromatography tandem mass spectrometry (LC-MS/MS) METHODS: Tumor-bearing mice were injected with (13) C6 glucose and the (13) C-labeled and total 6PG and 3PG concentrations measured. (13) C MR spectra of glucose-6-phosphate dehydrogenase deficient (zwf1Δ) and wild-type yeast were acquired following addition of hyperpolarized [U-(2) H, U-(13) C]glucose and again (13) C-labeled and total 6PG and 3PG were measured by LC-MS/MS RESULTS: Tumor (13) C-6PG was more abundant than (13) C-2PG/3PG and the resonance at ∼181 ppm matched more closely that of 6PG. (13) C MR spectra of wild-type and zwf1Δ yeast cells showed a resonance at ∼181 ppm after labeling with hyperpolarized [U-(2) H, U-(13) C]glucose, however, there was no 6PG in zwf1Δ cells. In the wild-type cells 3PG was approximately four-fold more abundant than 6PG CONCLUSION: The resonance at ∼181 ppm in (13) C MR spectra following injection of hyperpolarized [U-(2) H, U-(13) C]glucose originates predominantly from 6PG in EL4 tumors and 3PG in yeast cells. © 2014 Wiley Periodicals, Inc.

Physiologically Based Simulations of Deuterated Glucose for Quantifying Cell Turnover in Humans

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Christoph Niederalt

2017-04-01

Full Text Available In vivo [6,6-2H2]-glucose labeling is a state-of-the-art technique for quantifying cell proliferation and cell disappearance in humans. However, there are discrepancies between estimates of T cell proliferation reported in short (1-day versus long (7-day 2H2-glucose studies and very-long (9-week 2H2O studies. It has been suggested that these discrepancies arise from underestimation of true glucose exposure from intermittent blood sampling in the 1-day study. Label availability in glucose studies is normally approximated by a “square pulse” (Sq pulse. Since the body glucose pool is small and turns over rapidly, the availability of labeled glucose can be subject to large fluctuations and the Sq pulse approximation may be very inaccurate. Here, we model the pharmacokinetics of exogenous labeled glucose using a physiologically based pharmacokinetic (PBPK model to assess the impact of a more complete description of label availability as a function of time on estimates of CD4+ and CD8+ T cell proliferation and disappearance. The model enabled us to predict the exposure to labeled glucose during the fasting and de-labeling phases, to capture the fluctuations of labeled glucose availability caused by the intake of food or high-glucose beverages, and to recalculate the proliferation and death rates of immune cells. The PBPK model was used to reanalyze experimental data from three previously published studies using different labeling protocols. Although using the PBPK enrichment profile decreased the 1-day proliferation estimates by about 4 and 7% for CD4 and CD8+ T cells, respectively, differences with the 7-day and 9-week studies remained significant. We conclude that the approximations underlying the “square pulse” approach—recently suggested as the most plausible hypothesis—only explain a component of the discrepancy in published T cell proliferation rate estimates.

Why Do SGLT2 inhibitors inhibit only 30-50% of renal glucose reabsorption in humans?

Science.gov (United States)

Liu, Jiwen Jim; Lee, TaeWeon; DeFronzo, Ralph A

2012-09-01

Sodium glucose cotransporter 2 (SGLT2) inhibition is a novel and promising treatment for diabetes under late-stage clinical development. It generally is accepted that SGLT2 mediates 90% of renal glucose reabsorption. However, SGLT2 inhibitors in clinical development inhibit only 30-50% of the filtered glucose load. Why are they unable to inhibit 90% of glucose reabsorption in humans? We will try to provide an explanation to this puzzle in this perspective analysis of the unique pharmacokinetic and pharmacodynamic profiles of SGLT2 inhibitors in clinical trials and examine possible mechanisms and molecular properties that may be responsible.

Glucose transporter expression in human skeletal muscle fibers

DEFF Research Database (Denmark)

Gaster, M; Handberg, A; Beck-Nielsen, H

2000-01-01

, but its expression is markedly reduced around birth and is further reduced to undetectable levels within the first year of life; 2) GLUT-3 protein expression appears at 18 wk of gestation and disappears after birth; and 3) GLUT-4 protein is diffusely expressed in muscle cells throughout gestation, whereas...... after birth, the characteristic subcellular localization is as seen in adult muscle fibers. Our results show that GLUT-1, GLUT-3, and GLUT-4 seem to be of importance during muscle fiber growth and development. GLUT-5 protein was undetectable in fetal and adult skeletal muscle fibers. In adult muscle...... amplification (TSA) technique to detect the localization of glucose transporter expression in human skeletal muscle. We found expression of GLUT-1, GLUT-3, and GLUT-4 in developing human muscle fibers showing a distinct expression pattern. 1) GLUT-1 is expressed in human skeletal muscle cells during gestation...

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.

Sequence analysis and molecular characterization of Clonorchis sinensis hexokinase, an unusual trimeric 50-kDa glucose-6-phosphate-sensitive allosteric enzyme.

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Tingjin Chen

Full Text Available Clonorchiasis, which is induced by the infection of Clonorchis sinensis (C. sinensis, is highly associated with cholangiocarcinoma. Because the available examination, treatment and interrupting transmission provide limited opportunities to prevent infection, it is urgent to develop integrated strategies to prevent and control clonorchiasis. Glycolytic enzymes are crucial molecules for trematode survival and have been targeted for drug development. Hexokinase of C. sinensis (CsHK, the first key regulatory enzyme of the glycolytic pathway, was characterized in this study. The calculated molecular mass (Mr of CsHK was 50.0 kDa. The obtained recombinant CsHK (rCsHK was a homotrimer with an Mr of approximately 164 kDa, as determined using native PAGE and gel filtration. The highest activity was obtained with 50 mM glycine-NaOH at pH 10 and 100 mM Tris-HCl at pH 8.5 and 10. The kinetics of rCsHK has a moderate thermal stability. Compared to that of the corresponding negative control, the enzymatic activity was significantly inhibited by praziquantel (PZQ and anti-rCsHK serum. rCsHK was homotropically and allosterically activated by its substrates, including glucose, mannose, fructose, and ATP. ADP exhibited mixed allosteric effect on rCsHK with respect to ATP, while inorganic pyrophosphate (PPi displayed net allosteric activation with various allosteric systems. Fructose behaved as a dose-dependent V activator with the substrate glucose. Glucose-6-phosphate (G6P displayed net allosteric inhibition on rCsHK with respect to ATP or glucose with various allosteric systems in a dose-independent manner. There were differences in both mRNA and protein levels of CsHK among the life stages of adult worm, metacercaria, excysted metacercaria and egg of C. sinensis, suggesting different energy requirements during different development stages. Our study furthers the understanding of the biological functions of CsHK and supports the need to screen for small

Sequence Analysis and Molecular Characterization of Clonorchis sinensis Hexokinase, an Unusual Trimeric 50-kDa Glucose-6-Phosphate-Sensitive Allosteric Enzyme

Science.gov (United States)

Chen, Tingjin; Ning, Dan; Sun, Hengchang; Li, Ran; Shang, Mei; Li, Xuerong; Wang, Xiaoyun; Chen, Wenjun; Liang, Chi; Li, Wenfang; Mao, Qiang; Li, Ye; Deng, Chuanhuan; Wang, Lexun; Wu, Zhongdao; Huang, Yan; Xu, Jin; Yu, Xinbing

2014-01-01

Clonorchiasis, which is induced by the infection of Clonorchis sinensis (C. sinensis), is highly associated with cholangiocarcinoma. Because the available examination, treatment and interrupting transmission provide limited opportunities to prevent infection, it is urgent to develop integrated strategies to prevent and control clonorchiasis. Glycolytic enzymes are crucial molecules for trematode survival and have been targeted for drug development. Hexokinase of C. sinensis (CsHK), the first key regulatory enzyme of the glycolytic pathway, was characterized in this study. The calculated molecular mass (Mr) of CsHK was 50.0 kDa. The obtained recombinant CsHK (rCsHK) was a homotrimer with an Mr of approximately 164 kDa, as determined using native PAGE and gel filtration. The highest activity was obtained with 50 mM glycine-NaOH at pH 10 and 100 mM Tris-HCl at pH 8.5 and 10. The kinetics of rCsHK has a moderate thermal stability. Compared to that of the corresponding negative control, the enzymatic activity was significantly inhibited by praziquantel (PZQ) and anti-rCsHK serum. rCsHK was homotropically and allosterically activated by its substrates, including glucose, mannose, fructose, and ATP. ADP exhibited mixed allosteric effect on rCsHK with respect to ATP, while inorganic pyrophosphate (PPi) displayed net allosteric activation with various allosteric systems. Fructose behaved as a dose-dependent V activator with the substrate glucose. Glucose-6-phosphate (G6P) displayed net allosteric inhibition on rCsHK with respect to ATP or glucose with various allosteric systems in a dose-independent manner. There were differences in both mRNA and protein levels of CsHK among the life stages of adult worm, metacercaria, excysted metacercaria and egg of C. sinensis, suggesting different energy requirements during different development stages. Our study furthers the understanding of the biological functions of CsHK and supports the need to screen for small molecule inhibitors

A CuNi/C Nanosheet Array Based on a Metal-Organic Framework Derivate as a Supersensitive Non-Enzymatic Glucose Sensor

Science.gov (United States)

Zhang, Li; Ye, Chen; Li, Xu; Ding, Yaru; Liang, Hongbo; Zhao, Guangyu; Wang, Yan

2018-06-01

Bimetal catalysts are good alternatives for non-enzymatic glucose sensors owing to their low cost, high activity, good conductivity, and ease of fabrication. In the present study, a self-supported CuNi/C electrode prepared by electrodepositing Cu nanoparticles on a Ni-based metal-organic framework (MOF) derivate was used as a non-enzymatic glucose sensor. The porous construction and carbon scaffold inherited from the Ni-MOF guarantee good kinetics of the electrode process in electrochemical glucose detection. Furthermore, Cu nanoparticles disturb the array structure of MOF derived films and evidently enhance their electrochemical performances in glucose detection. Electrochemical measurements indicate that the CuNi/C electrode possesses a high sensitivity of 17.12 mA mM-1 cm-2, a low detection limit of 66.67 nM, and a wider linearity range from 0.20 to 2.72 mM. Additionally, the electrode exhibits good reusability, reproducibility, and stability, thereby catering to the practical use of glucose sensors. Similar values of glucose concentrations in human blood serum samples are detected with our electrode and with the method involving glucose-6-phosphate dehydrogenase; the results further demonstrate the practical feasibility of our electrode.

21 CFR 582.5697 - Riboflavin-5-phosphate.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Riboflavin-5-phosphate. 582.5697 Section 582.5697 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Supplements 1 § 582.5697 Riboflavin-5-phosphate. (a) Product. Riboflavin-5-phosphate. (b) Conditions of use...

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

Isoniazid acetylating phenotype in patients with paracoccidioidomycosis and its relationship with serum sulfadoxin levels, glucose-6-phosphate dehydrogenase and glutathione reductase activities

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Benedito Barraviera

1991-06-01

Full Text Available The authors evaluated the isoniazid acetylating phenotype and measured hematocrit, hemoglobin, glucose-6-phosphate dehydrogenase and glutathione reductase activities plus serum sulfadoxin levels in 39 patients with paracoccidioidomycosis (33 males and 6 females aged 17 to 58 years. Twenty one (53.84% of the patients presented a slow acetylatingphenotype and 18(46.16% a fast acetylating phenotype. Glucose-6-phosphate- dehydrogenase (G6PD acti vity was decreased in 5(23.80% slow acetylators and in 4(22.22% fast acetylators. Glutathione reductase activity was decreased in 14 (66.66% slow acetylators and in 12 (66.66% fast acetylators. Serum levels of free and total sulfadoxin Were higher in slow acetylator (p Os autores avaliaram o fenótipo acetilador da isoniazida, hematócrito, hemoglobina, atividade da glicose-6- fosfato desidrogenase, glutationa redutase e os níveis séricos de sulfadoxina de 39 doentes com paracoccidíoidomicose, senão 33 do sexo masculino e 6 do feminino, com idades compreendidas entre 17 e 58 anos. Vinte e um (53,84% doentes apresentaram fenótipo acetilador lento e 18 (46,16% rápido. A atividade da glicose-6-fosfato desidrogenase (G6PD esteve diminuída em 5 (23,80% acetiladores lentos e 4 (22,22% rápidos. A atividade da glutationa redutase esteve diminuída em 14 (66,66% acetiladores lentos e 12 (66,66% rápidos. Os níveis séricos de sulfadoxina livre e total foram maiores nos acetiladores lentos (p < 0,02. A análise dos resultados permite concluir que os níveis séricos de sulfadoxina relaciona-se com o fenótipo acetilador. Além disso, os níveis estiveram sempre acima de 50 µg/ml, níveis estes considerados terapêuticos. Por outro lado, a deficiência de glutationa redutase pode estar relacionada com a má absorção intestinal de nutrientes, entre eles riboflavina, vitamina precursora de FAD.

High prevalence of Dapsone-induced oxidant hemolysis in North American SCT recipients without glucose-6-phosphate-dehydrogenase deficiency.

Science.gov (United States)

Olteanu, H; Harrington, A M; George, B; Hari, P N; Bredeson, C; Kroft, S H

2012-03-01

Dapsone (4-4'-diaminodiphenylsulfone) is commonly used for Pneumocystis jirovecii pneumonia (PCP) prophylaxis in immunocompromised patients. Oxidant hemolysis is a known complication of dapsone, but its frequency in adult patients who have undergone a SCT for hematological malignancies is not well established. We studied the presence of oxidant hemolysis, by combining examination of RBC morphology and laboratory data, in 30 patients who underwent a SCT and received dapsone for PCP prophylaxis, and compared this group with 26 patients who underwent a SCT and received trimethoprim-sulfamethoxazole (TMP-SMX) for PCP prophylaxis. All patients had normal glucose-6-phosphate dehydrogenase (G6PDH) enzymatic activity. In SCT patients, dapsone compared with TMP-SMX for PCP prophylaxis was associated with a high incidence of oxidant hemolysis (87 vs 0%, PSCT patients is 20-fold higher than the reported rate in the population of HIV-infected patients, and thus much higher than the prevalence of G6PDH variants in the general population. In our patients, it manifested clinically as a lower Hb that was not significant enough to result in increased packed RBC transfusions.

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)

Simultaneous demonstration of acid phosphatase and glucose-6-phosphate dehydrogenase in mouse hepatocytes. A novel electron-microscopic dual staining enzyme-cytochemistry

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S Matsubara

2010-01-01

Full Text Available Acid phosphatase (ACPase and glucose-6-phosphate dehydrogenase (G6PD play important roles in cell biology/disease pathophysiology in various organs including the liver. The purpose of the present report is to introduce a new enzymecytochemical method to simultaneously demonstrate the subcellular localization of ACPase and G6PD within the same hepatocyte in the mouse liver. The ultrastructural localization of ACPase and G6PD were demonstrated, with concomitant use of the cerium method and the copper-ferrocyanide method, respectively. ACPase labelings were localized in the lysosomes, and G6PD labelings were visible in the cytoplasm and on the cytosolic side of the endoplasmic reticulum of the hepatocyte. This novel double staining procedure may be a useful histochemical tool for the study of liver functions in both physiological and pathological conditions.

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

DEFF Research Database (Denmark)

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...

Therapeutic targeting of Neu1 sialidase with oseltamivir phosphate (Tamiflu® disables cancer cell survival in human pancreatic cancer with acquired chemoresistance

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O’Shea LK

2014-01-01

Full Text Available Leah K O'Shea,1 Samar Abdulkhalek,1 Stephanie Allison,2 Ronald J Neufeld,2 Myron R Szewczuk11Department of Biomedical and Molecular Sciences, 2Department of Chemical Engineering, Queen's University, Kingston, ON, CanadaBackground: Resistance to drug therapy, along with high rates of metastasis, contributes to the low survival rate in patients diagnosed with pancreatic cancer. An alternate treatment for human pancreatic cancer involving targeting of Neu1 sialidase with oseltamivir phosphate (Tamiflu® was investigated in human pancreatic cancer (PANC1 cells with acquired resistance to cisplatin and gemcitabine. Its efficacy in overcoming the intrinsic resistance of the cell to chemotherapeutics and metastasis was evaluated.Methods: Microscopic imaging, immunocytochemistry, immunohistochemistry, and WST-1 cell viability assays were used to evaluate cell survival, morphologic changes, and expression levels of E-cadherin, N-cadherin, and VE-cadherin before and after treatment with oseltamivir phosphate in PANC1 cells with established resistance to cisplatin, gemcitabine, or a combination of the two agents, and in archived paraffin-embedded PANC1 tumors grown in RAGxCγ double mutant mice.Results: Oseltamivir phosphate overcame the chemoresistance of PANC1 to cisplatin and gemcitabine alone or in combination in a dose-dependent manner, and disabled the cancer cell survival mechanism(s. Oseltamivir phosphate also reversed the epithelial-mesenchymal transition characteristic of the phenotypic E-cadherin to N-cadherin changes associated with resistance to drug therapy. Low-dose oseltamivir phosphate alone or in combination with gemcitabine in heterotopic xenografts of PANC1 tumors growing in RAGxCγ double mutant mice did not prevent metastatic spread to the liver and lung.Conclusion: Therapeutic targeting of Neu1 sialidase with oseltamivir phosphate at the growth factor receptor level disables the intrinsic signaling platform for cancer cell survival

Tritiated 2-deoxy-D-glucose as a probe for cell membrane permeability studies

International Nuclear Information System (INIS)

Walum, E.; Peterson, A.

1982-01-01

Tritiated 2-deoxy-D-glucose was taken up and phosphorylated by cultured cells of neuronal (NIE 115), glial (138 MG), muscle (L 6) and liver (BRL 123) origin. Upon perfusion the cells slowly released 2-deoxy-D-glucose 6-phosphate. The following values for rate constants, half-lives, and activation energies for the efflux were obtained: NIE 115: 0.0048 min -1 , 143 min, and 72 kJ mol -1 ; 138 MG: 0.0013 min -1 , 547 min, and 85 kJ mol -1 ; L 6: 0.0022 min -1 , 311 min, and 60 kJ mol -1 ; and BRL 123: 0.0013 min -1 , 528 min and 63 kJ mol -1 . When the cultures were perfused with buffer containing Triton X-100 a time- and concentration-dependent increase in the rate of efflux of 2-deoxy-D-glucose 6-phosphate was obtained. It is suggested that 2-deoxy-D-[ 3 H]glucose can be used as a probe in studies of general cell membrane permeability changes

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)

Clonal evolution following chemotherapy-induced stem cell depletion in cats heterozygous for glucose-6-phosphate dehydrogenase

International Nuclear Information System (INIS)

Abkowitz, J.L.; Ott, R.M.; Holly, R.D.; Adamson, J.W.

1988-01-01

The number of hematopoietic stem cells necessary to support normal hematopoiesis is not known but may be small. If so, the depletion or damage of such cells could result in apparent clonal dominance. To test this hypothesis, dimethylbusulfan [2 to 4 mg/kg intravenously (IV) x 3] was given to cats heterozygous for the X-linked enzyme glucose-6-phosphate dehydrogenase (G-6-PD). These cats were the daughters of domestic X Geoffroy parents. After the initial drug-induced cytopenias (2 to 4 weeks), peripheral blood counts and the numbers of marrow progenitors detected in culture remained normal, although the percentages of erythroid burst-forming cells (BFU-E) and granulocyte/macrophage colony-forming cells (CFU-GM) in DNA synthesis increased, as determined by the tritiated thymidine suicide technique. In three of six cats treated, a dominance of Geoffroy-type G-6-PD emerged among the progenitor cells, granulocytes, and RBCs. These skewed ratios of domestic to Geoffroy-type G-6-PD have persisted greater than 3 years. No changes in cell cycle kinetics or G-6-PD phenotypes were noted in similar studies in six control cats. These data suggest that clonal evolution may reflect the depletion or damage of normal stem cells and not only the preferential growth and dominance of neoplastic cells

Effect of selective blockade of oxygen consumption, glucose transport, and Ca2+ influx on thyroxine action in human mononuclear cells

DEFF Research Database (Denmark)

Kvetny, J; Matzen, L E

1990-01-01

The effect of selective blockade of cellular glucose transporters, Ca2+ influx, and mitochondrial oxygen consumption on thyroxine (T4)-stimulated oxygen consumption and glucose uptake was examined in human mononuclear blood cells. Blockade of glucose transporters by cytochalasin B (1 x 10(-5) mol....../L) and of Ca2+ influx by alprenolol (1 x 10(-5) mol/L) and verapamil (4 x 10(-4) mol/L) inhibited T4-activated glucose uptaken and reduced T4-stimulated oxygen consumption by 20%. Uncoupling of mitochondrial oxygen consumption by azide (1 x 10(-3) mol/L) inhibited T4-stimulated oxygen consumption, but had...... no effect on glucose uptake. We conclude that T4-stimulated glucose uptake in human mononuclear blood cells is dependent on intact glucose transporters and Ca2+ influx, but not on mitochondrial oxygen consumption. However, oxygen consumption is, in part, dependent on intact glucose uptake....

Mechanistic Insights on Human Phosphoglucomutase Revealed by Transition Path Sampling and Molecular Dynamics Calculations.

Science.gov (United States)

Brás, Natércia F; Fernandes, Pedro A; Ramos, Maria J; Schwartz, Steven D

2018-02-06

Human α-phosphoglucomutase 1 (α-PGM) catalyzes the isomerization of glucose-1-phosphate into glucose-6-phosphate (G6P) through two sequential phosphoryl transfer steps with a glucose-1,6-bisphosphate (G16P) intermediate. Given that the release of G6P in the gluconeogenesis raises the glucose output levels, α-PGM represents a tempting pharmacological target for type 2 diabetes. Here, we provide the first theoretical study of the catalytic mechanism of human α-PGM. We performed transition-path sampling simulations to unveil the atomic details of the two catalytic chemical steps, which could be key for developing transition state (TS) analogue molecules with inhibitory properties. Our calculations revealed that both steps proceed through a concerted S N 2-like mechanism, with a loose metaphosphate-like TS. Even though experimental data suggests that the two steps are identical, we observed noticeable differences: 1) the transition state ensemble has a well-defined TS region and a late TS for the second step, and 2) larger coordinated protein motions are required to reach the TS of the second step. We have identified key residues (Arg23, Ser117, His118, Lys389), and the Mg 2+ ion that contribute in different ways to the reaction coordinate. Accelerated molecular dynamics simulations suggest that the G16P intermediate may reorient without leaving the enzymatic binding pocket, through significant conformational rearrangements of the G16P and of specific loop regions of the human α-PGM. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fructose Alters Intermediary Metabolism of Glucose in Human Adipocytes and Diverts Glucose to Serine Oxidation in the One–Carbon Cycle Energy Producing Pathway

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Vijayalakshmi Varma

2015-06-01

Full Text Available Increased consumption of sugar and fructose as sweeteners has resulted in the utilization of fructose as an alternative metabolic fuel that may compete with glucose and alter its metabolism. To explore this, human Simpson-Golabi-Behmel Syndrome (SGBS preadipocytes were differentiated to adipocytes in the presence of 0, 1, 2.5, 5 or 10 mM of fructose added to a medium containing 5 mM of glucose representing the normal blood glucose concentration. Targeted tracer [1,2-13C2]-d-glucose fate association approach was employed to examine the influence of fructose on the intermediary metabolism of glucose. Increasing concentrations of fructose robustly increased the oxidation of [1,2-13C2]-d-glucose to 13CO2 (p < 0.000001. However, glucose-derived 13CO2 negatively correlated with 13C labeled glutamate, 13C palmitate, and M+1 labeled lactate. These are strong markers of limited tricarboxylic acid (TCA cycle, fatty acid synthesis, pentose cycle fluxes, substrate turnover and NAD+/NADP+ or ATP production from glucose via complete oxidation, indicating diminished mitochondrial energy metabolism. Contrarily, a positive correlation was observed between glucose-derived 13CO2 formed and 13C oleate and doses of fructose which indicate the elongation and desaturation of palmitate to oleate for storage. Collectively, these results suggest that fructose preferentially drives glucose through serine oxidation glycine cleavage (SOGC pathway one-carbon cycle for NAD+/NADP+ production that is utilized in fructose-induced lipogenesis and storage in adipocytes.

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...

Impaired glucose-induced thermogenesis and arterial norepinephrine response persist after weight reduction in obese humans

DEFF Research Database (Denmark)

Astrup, A; Andersen, T; Christensen, N J

1990-01-01

A reduced thermic response and an impaired activation of the sympathetic nervous system (SNS) has been reported after oral glucose in human obesity. It is, however, not known whether the reduced SNS activity returns to normal along with weight reduction. The thermic effect of glucose was lower...... in eight obese patients than in matched control subjects (1.7% vs 9.2%, p less than 0.002). The increase in arterial norepinephrine after glucose was also blunted in the obese patients. After a 30-kg weight loss their glucose and lipid profiles were markedly improved but the thermic effect of glucose...... was still lower than that of the control subjects (4.2%, p less than 0.001). The glucose-induced arterial norepinephrine response remained diminished in the reduced obese patients whereas the changes in plasma epinephrine were similar in all three groups. The results suggest that a defective SNS may...

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

Quantitative importance of the pentose phosphate pathway determined by incorporation of 13C from [2-13C]- and [3-13C]glucose into TCA cycle intermediates and neurotransmitter amino acids in functionally intact neurons.

Science.gov (United States)

Brekke, Eva M F; Walls, Anne B; Schousboe, Arne; Waagepetersen, Helle S; Sonnewald, Ursula

2012-09-01

The brain is highly susceptible to oxidative injury, and the pentose phosphate pathway (PPP) has been shown to be affected by pathological conditions, such as Alzheimer's disease and traumatic brain injury. While this pathway has been investigated in the intact brain and in astrocytes, little is known about the PPP in neurons. The activity of the PPP was quantified in cultured cerebral cortical and cerebellar neurons after incubation in the presence of [2-(13)C]glucose or [3-(13)C]glucose. The activity of the PPP was several fold lower than glycolysis in both types of neurons. While metabolism of (13)C-labeled glucose via the PPP does not appear to contribute to the production of releasable lactate, it contributes to labeling of tricarboxylic acid (TCA) cycle intermediates and related amino acids. Based on glutamate isotopomers, it was calculated that PPP activity accounts for ~6% of glucose metabolism in cortical neurons and ~4% in cerebellar neurons. This is the first demonstration that pyruvate generated from glucose via the PPP contributes to the synthesis of acetyl CoA for oxidation in the TCA cycle. Moreover, the fact that (13)C labeling from glucose is incorporated into glutamate proves that both the oxidative and the nonoxidative stages of the PPP are active in neurons.

Proteomic and biochemical basis for enhanced growth yield of Enterobacter sp. LCR1 on insoluble phosphate medium.

Science.gov (United States)

Kumar, Arvind; Rai, Lal Chand

2015-01-01

Proteomics and biochemical analyses were used to unravel the basis for higher growth yield of Enterobacter sp. LCR1 on insoluble phosphate medium compared to soluble. Proteomic analysis using 2-DE, MALDI-TOF/MS and LC-MS revealed the involvement of nine proteins. Down-regulation of fructose bisphosphate aldolase with decreased concentrations of glucose-6-phosphate and fructose-6-phosphate indicated diminished glycolysis. However, up-regulation of phosphoglycerate mutase, increase in the activities of 6-phosphogluconate dehydratase, 2-keto-3-deoxy-6-phosphogluconate aldolase and 6-phosphogluconate dehydrogenase suggested induction of Entner-Doudoroff and pentose phosphate pathways. These pathways generate sufficient energy from gluconic acid, which is also used for biosynthesis as indicated by up-regulation of elongation factor Tu, elongation factor G and protein disulfide isomerase. Increased reactive oxygen species (ROS) formation resulting from organic acid oxidation leads to overexpressed manganese superoxide dismutase and increased activities of catalase and ascorbate peroxidase. Thus the organism uses gluconate instead of glucose for energy, while alleviating extra ROS formation by oxidative defense enzymes. Copyright © 2014 Elsevier GmbH. All rights reserved.

Perturbation of human coronary artery endothelial cell redox state and NADPH generation by methylglyoxal.

Directory of Open Access Journals (Sweden)

Philip E Morgan

Full Text Available Diabetes is associated with elevated plasma glucose, increased reactive aldehyde formation, oxidative damage, and glycation/glycoxidation of biomolecules. Cellular detoxification of, or protection against, such modifications commonly requires NADPH-dependent reducing equivalents (e.g. GSH. We hypothesised that reactive aldehydes may modulate cellular redox status via the inhibition of NADPH-generating enzymes, resulting in decreased thiol and NADPH levels. Primary human coronary artery endothelial cells (HCAEC were incubated with high glucose (25 mM, 24 h, 37°C, or methylglyoxal (MGO, glyoxal, or glycolaldehyde (100-500 µM, 1 h, 37°C, before quantification of intracellular thiols and NADPH-generating enzyme activities. Exposure to MGO, but not the other species examined, significantly (P<0.05 decreased total thiols (∼35%, further experiments with MGO showed significant losses of GSH (∼40% and NADPH (∼10%; these changes did not result in an immediate loss of cell viability. Significantly decreased (∼10% NADPH-producing enzyme activity was observed for HCAEC when glucose-6-phosphate or 2-deoxyglucose-6-phosphate were used as substrates. Cell lysate experiments showed significant MGO-dose dependent inhibition of glucose-6-phosphate-dependent enzymes and isocitrate dehydrogenase, but not malic enzyme. Analysis of intact cell or lysate proteins showed that arginine-derived hydroimidazolones were the predominant advanced glycation end-product (AGE formed; lower levels of N(ε-(carboxyethyllysine (CEL and N(ε-(carboxymethyllysine (CML were also detected. These data support a novel mechanism by which MGO exposure results in changes in redox status in human coronary artery endothelial cells, via inhibition of NADPH-generating enzymes, with resultant changes in reduced protein thiol and GSH levels. These changes may contribute to the endothelial cell dysfunction observed in diabetes-associated atherosclerosis.

Splanchnic blood flow and hepatic glucose production in exercising humans

DEFF Research Database (Denmark)

Bergeron, R; Kjaer, M; Simonsen, L

2001-01-01

The study examined the implication of the renin-angiotensin system (RAS) in regulation of splanchnic blood flow and glucose production in exercising humans. Subjects cycled for 40 min at 50% maximal O(2) consumption (VO(2 max)) followed by 30 min at 70% VO(2 max) either with [angiotensin-converti......The study examined the implication of the renin-angiotensin system (RAS) in regulation of splanchnic blood flow and glucose production in exercising humans. Subjects cycled for 40 min at 50% maximal O(2) consumption (VO(2 max)) followed by 30 min at 70% VO(2 max) either with [angiotensin......-converting enzyme (ACE) blockade] or without (control) administration of the ACE inhibitor enalapril (10 mg iv). Splanchnic blood flow was estimated by indocyanine green, and splanchnic substrate exchange was determined by the arteriohepatic venous difference. Exercise led to an approximately 20-fold increase (P ...-blockade group vs. the control group, hormones, metabolites, VO(2), and RER followed the same pattern of changes in ACE-blockade and control groups during exercise. Splanchnic blood flow (at rest: 1.67 +/- 0.12, ACE blockade; 1.59 +/- 0.18 l/min, control) decreased during moderate exercise (0.78 +/- 0.07, ACE...

Carbon balance studies of glucose metabolism in rat cerebral cortical synaptosomes

Energy Technology Data Exchange (ETDEWEB)

Bauer, U; Brand, K

1982-07-01

Synaptosomes were isolated from rat cerebral cortex and incubated with (U-/sup 14/C)-, (1-/sup 14/C)- or (6-/sup 14/C)glucose. Glucose utilization and the metabolic partitioning of glucose carbon in products were determined by isotopic methods. From the data obtained a carbon balance was constructed, showing lactate to be the main product of glucose metabolism, followed by CO/sup 2/, amino acids and pyruvate. Measuring the release of /sup 14/CO/sup 2/ from glucose labelled in three different positions allowed the construction of a flow diagram of glucose carbon atoms in synaptosomes, which provides information about the contribution of the various pathways of glucose metabolism. Some 2% of glucose utilized was calculated to be degraded via the pentose phosphate pathway. Addition of chlorpromazine, imipramine or haloperidol at concentrations of 10(-5) M reduced glucose utilisation by 30% without changing the distribution pattern of radioactivity in the various products.

Silencing of the pentose phosphate pathway genes influences DNA replication in human fibroblasts.

Science.gov (United States)

Fornalewicz, Karolina; Wieczorek, Aneta; Węgrzyn, Grzegorz; Łyżeń, Robert

2017-11-30

Previous reports and our recently published data indicated that some enzymes of glycolysis and the tricarboxylic acid cycle can affect the genome replication process by changing either the efficiency or timing of DNA synthesis in human normal cells. Both these pathways are connected with the pentose phosphate pathway (PPP pathway). The PPP pathway supports cell growth by generating energy and precursors for nucleotides and amino acids. Therefore, we asked if silencing of genes coding for enzymes involved in the pentose phosphate pathway may also affect the control of DNA replication in human fibroblasts. Particular genes coding for PPP pathway enzymes were partially silenced with specific siRNAs. Such cells remained viable. We found that silencing of the H6PD, PRPS1, RPE genes caused less efficient enterance to the S phase and decrease in efficiency of DNA synthesis. On the other hand, in cells treated with siRNA against G6PD, RBKS and TALDO genes, the fraction of cells entering the S phase was increased. However, only in the case of G6PD and TALDO, the ratio of BrdU incorporation to DNA was significantly changed. The presented results together with our previously published studies illustrate the complexity of the influence of genes coding for central carbon metabolism on the control of DNA replication in human fibroblasts, and indicate which of them are especially important in this process. Copyright © 2017 Elsevier B.V. All rights reserved.

Two new glucose 6-phosphate dehydrogenase variants associated with congenital nonspherocytic hemolytic anemia found in Japan: GD(-) Tokushima and GD(-) Tokyo.

Science.gov (United States)

Miwa, S; Ono, J; Nakashima, K; Abe, S; Kageoka, T

1976-01-01

Two new variants of glucose 6-phosphate dehydrogenase (G6PD) deficiency associated with chronic nonspherocytic hemolytic anemia were discovered in Japan. Gd(-) Tokushima was found in a 17-years-old male whose erythrocytes contained 4.4% of normal enzyme activity. Partially purified enzyme revealed a main band of normal electrophoretic mobility with additional two minor bands of different mobility; normal Km G6P, and Km NADP five-to sixfold higher than normal; normal utilization of 2-deoxy-G6P, galactose-6P, and deamino-NADP; marked thermal instability; a normal pH curve; and normal Ki NADPH. The hemolytic anemia was moderate to severe. Gd(-) Tokyo was characterized from a 15-year-old male who had chronic nonspherocytic hemolytic anemia of mild degree. The erythrocytes contained 3% of normal enzyme activity, and partially purified enzyme revealed slow electrophoretic mobility (90% of normal for both a tris-hydrochloride buffer system and a tris-EDTA-borate buffer system, and 70% of normal for a phosphate buffer system); normal Km G6P and Km NADP; normal utilization of 2-deoxy-G6P, galactose-6P, and deamino-NADP; greatly increased thermal instability; a normal pH curve; and normal Ki NADPH. These two variants are clearly different from hitherto described G6PD variants, including the Japanese variants Gd(-) Heian and Gd(-) Kyoto. The mothers of both Gd(-) Tokushima and Gd(-) Tokoyo were found to be heterozygote by an ascorbate-cyanide test.

Why Do SGLT2 Inhibitors Inhibit Only 30–50% of Renal Glucose Reabsorption in Humans?

Science.gov (United States)

Liu, Jiwen (Jim); Lee, TaeWeon; DeFronzo, Ralph A.

2012-01-01

Sodium glucose cotransporter 2 (SGLT2) inhibition is a novel and promising treatment for diabetes under late-stage clinical development. It generally is accepted that SGLT2 mediates 90% of renal glucose reabsorption. However, SGLT2 inhibitors in clinical development inhibit only 30–50% of the filtered glucose load. Why are they unable to inhibit 90% of glucose reabsorption in humans? We will try to provide an explanation to this puzzle in this perspective analysis of the unique pharmacokinetic and pharmacodynamic profiles of SGLT2 inhibitors in clinical trials and examine possible mechanisms and molecular properties that may be responsible. PMID:22923645

7,8-Dihydroxyflavone ameliorates high-glucose induced diabetic apoptosis in human retinal pigment epithelial cells by activating TrkB.

Science.gov (United States)

Yu, Xiaoyi; Liu, Qiuhong; Wang, Xiaochuan; Liu, Hong; Wang, Yan

2018-01-01

In diabetic retinopathy, prolonged high-level blood glucose induced significant impairments among various retinal tissues, including retinal pigment epithelial (RPE) cells. In an in vitro model of human RPE cells, we evaluated whether 7,8-Dihydroxyflavone (DHF) may effectively prevent high glucose-induced diabetic apoptosis among human RPE cells. ARPE-19 cells, a Human RPE cell line, were treated with d-glucose (50 mM) to induce apoptosis in vitro. Prior to glucose, ARPE-19 cells were pre-incubated with various concentrations of DHF. The effect of DHF on d-glucose-induced apoptosis was examined by TUNEL assay, in a concentration-dependent manner. The biological effects of DHF on Caspase-9 (Casp-9) and TrkB signaling pathways in d-glucose-injured ARPE-19 cells were evaluated by qRT-PCR and western blot (WB) assays. A TrkB antagonist, K252a, was also applied in DHF and d-glucose treated ARPE-19 cells. Possible effect of K252a blocking TrkB signaling pathway, thus reversing DHF-modulated apoptosis prevention was also examined by TUNEL and WB assays. DHF ameliorated d-glucose-induced diabetic apoptosis in ARPE-19 cells. Apoptotic factor Casp-9, at both mRNA and protein levels, were drastically inhibited by DHF in d-glucose-injured ARPE-19 cells. Also, DHF activated TrkB signaling pathway through phosphorylation. K252a dramatically reversed the preventive effect of DHF on d-glucose-induced apoptosis in ARPE-19 cells. Further investigation showed that K252a functioned through de-activating or de-phosphorylating TrkB signaling pathway. This work demonstrates that DHF, through activation of TrkB signaling pathway, has a preventive function in d-glucose-induced apoptosis in PRE cells in diabetic retinopathy. Copyright © 2017. Published by Elsevier Inc.

INFLUENCE OF pH, TEMPERATURE AND DISSOLVED OXYGEN CONCENTRATION ON THE PRODUCTION OF GLUCOSE 6-PHOSPHATE DEHYDROGENASE AND INVERTASE BY Saccharomyces cerevisiae

Directory of Open Access Journals (Sweden)

J. Abrahão-Neto

1997-03-01

Full Text Available The effect of pH (from 4.0 to 5.0, temperature (T (from 30 oC to 40 oC and dissolved oxygen concentration (DO (from 0.2 to 6.0 mg O2/L on glucose 6-phosphate dehydrogenase (G6PDH (EC 1.1.1.49 and Invertase (EC 3.2.1.26 formation by S. cerevisiae were studied. The best culture conditions for G6PDH and Invertase formation were: 2.55 L culture medium (yeast extract, 3.0 g/L; 5peptone, 5.0 g/L; glucose, 2.0 g/L; sucrose, 15.0 g/L; Na2HPO4.12 H2O, 2.4 g/L; (NH42SO4, 5.1 g/L and MgSO4. 7H2O, 0.075 g/L; 0.45 L inoculum (0.70 g dry cell/L; pH = 4.5; T = 35 oC and DO = 4.0 mg/L. G6PDH was highly sensitive to pH, T and DO variation. The increase in G6PDH production was about three times when the DO ranged from 0.2 to 4.0 mg O2/L. Moreover, by shifting pH from 5.0 to 4.5 and temperature from 30 oC to 35 oC, G6PDH formation increased by 57% and 70%, respectively. Invertase activity (IA of whole cells decreased at least 50% at extremes values of DO (2.0 and 6.0 mg O2/L and pH (4.0 and 5.0. Furthermore, IA oscillated during the fermentation due to the glucose repression/derepression mechanism

Buddleja officinalis inhibits high glucose-induced matrix metalloproteinase activity in human umbilical vein endothelial cells.

Science.gov (United States)

Lee, Yun Jung; Kang, Dae Gill; Kim, Jin Sook; Lee, Ho Sub

2008-12-01

The aim of the present investigation was to investigate whether an aqueous extract of Buddleja officinalis (ABO), a traditional Korean herbal medicine, suppresses the endothelial extracellular matrix degradation under high glucose condition. The incubation with high concentration of glucose (25 mM) increased significantly matrix metalloproteinase (MMP)-2/-9 expressions and activities in primary cultured human umbilical vein endothelial cells (HUVEC). Pretreatment with ABO decreased high glucose-induced increase of MMP-2/-9 activities in a dose-dependent manner. Real time qRT-PCR revealed that high glucose-induced MMP-2/-9 mRNA expression levels were attenuated by pretreatment with ABO. High glucose-induced MCP-1 and IL-8 mRNA expression levels also decreased by ABO. ABO decreased high glucose-induced hydrogen peroxide production, oxidative stress marker. These results provide new insights into the pathophysiological mechanisms for anti-inflammatory properties of ABO in vascular diseases associated with diabetes mellitus. (c) 2008 John Wiley & Sons, Ltd.

Temporal metabolomic responses of cultured HepG2 liver cells to high fructose and high glucose exposures.

Science.gov (United States)

Meissen, John K; Hirahatake, Kristin M; Adams, Sean H; Fiehn, Oliver

2015-06-01

High fructose consumption has been implicated with deleterious effects on human health, including hyperlipidemia elicited through de novo lipogenesis. However, more global effects of fructose on cellular metabolism have not been elucidated. In order to explore the metabolic impact of fructose-containing nutrients, we applied both GC-TOF and HILIC-QTOF mass spectrometry metabolomic strategies using extracts from cultured HepG2 cells exposed to fructose, glucose, or fructose + glucose. Cellular responses were analyzed in a time-dependent manner, incubated in media containing 5.5 mM glucose + 5.0 mM fructose in comparison to controls incubated in media containing either 5.5 mM glucose or 10.5 mM glucose. Mass spectrometry identified 156 unique known metabolites and a large number of unknown compounds, which revealed metabolite changes due to both utilization of fructose and high-carbohydrate loads independent of hexose structure. Fructose was shown to be partially converted to sorbitol, and generated higher levels of fructose-1-phosphate as a precursor for glycolytic intermediates. Differentially regulated ratios of 3-phosphoglycerate to serine pathway intermediates in high fructose media indicated a diversion of carbon backbones away from energy metabolism. Additionally, high fructose conditions changed levels of complex lipids toward phosphatidylethanolamines. Patterns of acylcarnitines in response to high hexose exposure (10.5 mM glucose or glucose/fructose combination) suggested a reduction in mitochondrial beta-oxidation.

Piracetam and TRH analogues antagonise inhibition by barbiturates, diazepam, melatonin and galanin of human erythrocyte D-glucose transport

Science.gov (United States)

Naftalin, Richard J; Cunningham, Philip; Afzal-Ahmed, Iram

2004-01-01

Nootropic drugs increase glucose uptake into anaesthetised brain and into Alzheimer's diseased brain. Thyrotropin-releasing hormone, TRH, which has a chemical structure similar to nootropics increases cerebellar uptake of glucose in murine rolling ataxia. This paper shows that nootropic drugs like piracetam (2-oxo 1 pyrrolidine acetamide) and levetiracetam and neuropeptides like TRH antagonise the inhibition of glucose transport by barbiturates, diazepam, melatonin and endogenous neuropeptide galanin in human erythrocytes in vitro. The potencies of nootropic drugs in opposing scopolamine-induced memory loss correlate with their potencies in antagonising pentobarbital inhibition of erythrocyte glucose transport in vitro (Pnootropics, D-levetiracetam and D-pyroglutamate, have higher antagonist Ki's against pentobarbital inhibition of glucose transport than more potent L-stereoisomers (Pnootropics, like aniracetam and levetiracetam, while antagonising pentobarbital action, also inhibit glucose transport. Analeptics like bemigride and methamphetamine are more potent inhibitors of glucose transport than antagonists of hypnotic action on glucose transport. There are similarities between amino-acid sequences in human glucose transport protein isoform 1 (GLUT1) and the benzodiazepine-binding domains of GABAA (gamma amino butyric acid) receptor subunits. Mapped on a 3D template of GLUT1, these homologies suggest that the site of diazepam and piracetam interaction is a pocket outside the central hydrophilic pore region. Nootropic pyrrolidone antagonism of hypnotic drug inhibition of glucose transport in vitro may be an analogue of TRH antagonism of galanin-induced narcosis. PMID:15148255

The effect of gold nanoparticles modified electrode on the glucose sensing performance

Science.gov (United States)

Zulkifli, Zulfa Aiza; Ridhuan, Nur Syafinaz; Nor, Noorhashimah Mohamad; Zakaria, Nor Dyana; Razak, Khairunisak Abdul

2017-07-01

In this work, 20 nm, 30 nm, 40 nm, 50 nm and 60 nm colloidal gold nanoparticles (AuNPs) were synthesized using the seeding growth method. AuNPs produced had spherical shape with uniform size. The AuNPs also are well dispersed in colloidal form that was proven by low polydispersity index. The produced AuNPs were used to modify electrode for glucose sensor. The produced AuNPs were deposited on indium tin oxide substrate (ITO), followed by immobilization of glucose oxidase (GOx) on it. After that, Nafion was deposited on the GOx/AuNPs/ITO. Electrooxidation of glucose with AuNPs-modified electrode was examined by cyclic voltammeter (CV) in 15 mM glucose mixed with 0.01 M PBS. The optimum size of AuNPs was 30 nm with optical density 3.0. AuNPs were successfully immobilized with glucose oxidase (GOx) and proved to work well as a glucose sensor. Based on the high electrocatalytic activity of Nafion/GOx/AuNPs/ITO, the sensitivity of the glucose sensors was further examined by varying the concentration of glucose solution from 2 mM to 20 mM in 0.01 M phosphate buffer solution (PBS) solution. Good linear relationship was observed between the catalytic current and glucose concentration in the range of 2 mM to 20 mM. The sensitivity of the Nafion/GOx/AuNPs/ITO electrode calculated from the slope of linear square calibration was 0.909 µA mM-1 cm-2 that is comparable with other published work. The linear fitting to the experimental data gives R-square of 0.991 at 0.9 V and a detection limit of 2.03 mM. This detection range is sufficient to be medically useful in monitoring human blood glucose level in which the normal blood glucose level is in the range of 4.4 to 6.6 mM and diabetic blood glucose level is above 7 mM.

L-Myo-inositol 1-phosphate synthase in the aquatic fern Azolla filiculoides.

Science.gov (United States)

Benaroya, Rony Oren; Zamski, Eli; Tel-Or, Elisha

2004-02-01

L-Myo-inositol 1-phosphate synthase (INPS EC 5.5.1.4) catalyzes the conversion of D-glucose 6-phosphate to L-myo-inositol 1-phosphate. INPS is a key enzyme involved in the biosynthesis of phytate which is a common form of stored phosphates in higher plants. The present study monitored the increase of INPS expression in Azolla filiculoides resulting from exposure to inorganic phosphates, metals and salt stress. The expression of INPS was significantly higher in Azolla plants that were grown in rich mineral growth medium than those maintained on nutritional growth medium. The expression of INPS protein and corresponding mRNA increased in plants cultured in minimal nutritional growth medium when phosphate or Zn2+, Cd2+ and NaCl were added to the growth medium. When employing rich mineral growth medium, INPS protein content increased with the addition of Zn2+, but decreased in the presence of Cd2+ and NaCl. These results indicated that accumulation of phytate in Azolla is a result of the intensified expression of INPS protein and mRNA, and its regulation may be primarily derived by the uptake of inorganic phosphate, and Zn2+, Cd2+ or NaCl.

Human TP53 polymorphism (rs1042522) modelled in mouse does not affect glucose metabolism and body composition.

Science.gov (United States)

Reiling, Erwin; Speksnijder, Ewoud N; Pronk, Amanda C M; van den Berg, Sjoerd A A; Neggers, Silvia J W; Rietbroek, Ilma; van Steeg, Harry; Dollé, Martijn E T

2014-02-13

Variation in TP53 has been associated with cancer. The pro-allele of a TP53 polymorphism in codon 72 (rs1042522) has been associated with longevity. Recently, we showed that the same allele might be involved in preservation of glucose metabolism, body composition and blood pressure during ageing. Here, we assessed glucose tolerance and body composition in mice carrying the human polymorphism. Our data do not support the previous findings in humans, suggesting that this polymorphism does not play a major role in development of glucose metabolism and body composition during ageing. Alternatively, the mouse model may not be suitable to validate these rs1042522-associated traits up to the age tested.

Glycolysis-induced discordance between glucose metabolic rates measured with radiolabeled fluorodeoxyglucose and glucose

International Nuclear Information System (INIS)

Ackermann, R.F.; Lear, J.L.

1989-01-01

We have developed an autoradiographic method for estimating the oxidative and glycolytic components of local CMRglc (LCMRglc), using sequentially administered [ 18 F]fluorodeoxyglucose (FDG) and [ 14 C]-6-glucose (GLC). FDG-6-phosphate accumulation is proportional to the rate of glucose phosphorylation, which occurs before the divergence of glycolytic (GMg) and oxidative (GMo) glucose metabolism and is therefore related to total cerebral glucose metabolism GMt: GMg + GMo = GMt. With oxidative metabolism, the 14 C label of GLC is temporarily retained in Krebs cycle-related substrate pools. We hypothesize that with glycolytic metabolism, however, a significant fraction of the 14 C label is lost from the brain via lactate production and efflux from the brain. Thus, cerebral GLC metabolite concentration may be more closely related to GMo than to GMt. If true, the glycolytic metabolic rate will be related to the difference between FDG- and GLC-derived LCMRglc. Thus far, we have studied normal awake rats, rats with limbic activation induced by kainic acid (KA), and rats visually stimulated with 16-Hz flashes. In KA-treated rats, significant discordance between FDG and GLC accumulation, which we attribute to glycolysis, occurred only in activated limbic structures. In visually stimulated rats, significant discordance occurred only in the optic tectum

A fine pointed glucose oxidase immobilized electrode for low-invasive amperometric glucose monitoring.

Science.gov (United States)

Li, Jiang; Koinkar, Pankaj; Fuchiwaki, Yusuke; Yasuzawa, Mikito

2016-12-15

A low invasive type glucose sensor, which has a sensing region at the tip of a fine pointed electrode, was developed for continuous glucose monitoring. Platinum-iridium alloy electrode with a surface area of 0.045mm(2) was settled at the middle of pointed PEEK (Polyetheretherketone) tubing and was employed as sensing electrode. Electrodeposition of glucose oxidase in the presence of surfactant, Triton X-100, was performed for high-density enzyme immobilization followed by the electropolymerization of o-phenylenediamine for the formation of functional entrapping and permselective polymer membrane. Ag/AgCl film was coated on the surface of PEEK tubing as reference electrode. Amperometric responses of the prepared sensors to glucose were measured at a potential of 0.60V (vs. Ag/AgCl). The prepared electrode showed the sensitivity of 2.55μA/cm(2) mM with high linearity of 0.9986, within the glucose concentration range up to 21mM. The detection limit (S/N=3) was determined to be 0.11mM. The glucose sensor properties were evaluated in phosphate buffer solution and in vivo monitoring by the implantation of the sensors in rabbit, while conventional needle type sensors as a reference were used. The results showed that change in output current of the proposed sensor fluctuated similar with one in output current of the conventional needle type sensors, which was also in similar accordance with actual blood sugar level measured by commercially glucose meter. One-point calibration method was used to calibrate the sensor output current. Copyright © 2016 Elsevier B.V. All rights reserved.

The human Na+-glucose cotransporter is a molecular water pump

DEFF Research Database (Denmark)

Meinild, A; Klaerke, D A; Loo, D D

1998-01-01

1. The human Na+-glucose cotransporter (hSGLT1) was expressed in Xenopus laevis oocytes. The transport activity, given by the Na+ current, was monitored as a clamp current and the concomitant flux of water followed optically as the change in oocyte volume. 2. When glucose was added to the bathing...... solution there was an abrupt increase in clamp current and an immediate swelling of the oocyte. The transmembrane transport of two Na+ ions and one sugar molecule was coupled, within the protein itself, to the influx of 210 water molecules. 3. This stoichiometry was constant and independent of the external...... parameters: Na+ concentrations, sugar concentrations, transmembrane voltages, temperature and osmotic gradients. 4. The cotransport of water occurred in the presence of adverse osmotic gradients. In accordance with the Gibbs equation, energy was transferred within the protein from the downhill fluxes of Na...

Photoassist-phosphorylated TiO2 as a catalyst for direct formation of 5-(hydroxymethyl)furfural from glucose.

Science.gov (United States)

Hattori, Masashi; Kamata, Keigo; Hara, Michikazu

2017-02-01

Photo-assisted phosphorylation of an anatase TiO 2 catalyst was examined to improve its catalytic performance for the direct production of 5-(hydroxymethyl)furfural (HMF), a versatile chemical platform, from glucose. In phosphorylation based on simple esterification between phosphoric acid and surface OH groups on anatase TiO 2 with water-tolerant Lewis acid sites, the density of phosphates immobilized on TiO 2 is limited to 2 phosphates nm -2 , which limits selective HMF production. Phosphorylation of the TiO 2 surface under fluorescent light irradiation increases the surface phosphate density to 50%, which is higher than the conventional limit, thus preventing the adsorption of hydrophilic glucose molecules on TiO 2 and resulting in a more selective HMF production over photoassist-phosphorylated TiO 2 .

Glucose 6-phosphate compartmentation and the control of glycogen synthesis

NARCIS (Netherlands)

Meijer, Alfred

2002-01-01

Using adenovirus-mediated gene transfer into FTO-2B cells, a rat hepatoma cell line, we have overexpressed hexokinase I, (HK I), glucokinase (GK), liver glycogen synthase (LGS), muscle glycogen synthase (MGS), and combinations of each of the two glucose phosphorylating enzymes with each one of the

Glucose metabolism in gamma-irradiated rice seeds

International Nuclear Information System (INIS)

Inoue, M.; Hasegawa, H.; Hori, S.

1980-01-01

Gamma-irradiation of 30 kR in rice seeds caused marked inhibition in seedling growth, and prevented the release of reduced sugar during the period of 25 to 76hr after soaking. The C 6 /C 1 ratio following irradiation continued to decrease up to the 76th hour of soaking; the control's ratio tended to increase with comparable soaking time. The percentage recovery of 14 C in carbon dioxide from glucose -1- 14 C was lower in irradiated than in control seeds. These results indicate that gamma-irradiation reduces the participation of the pentose phosphate pathway in glucose catabolism during an early period of germination. (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

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.

Plasma sphingosine-1-phosphate is elevated in obesity.

Directory of Open Access Journals (Sweden)

Greg M Kowalski

Full Text Available BACKGROUND: Dysfunctional lipid metabolism is a hallmark of obesity and insulin resistance and a risk factor for various cardiovascular and metabolic complications. In addition to the well known increase in plasma triglycerides and free fatty acids, recent work in humans and rodents has shown that obesity is associated with elevations in the bioactive class of sphingolipids known as ceramides. However, in obesity little is known about the plasma concentrations of sphinogsine-1-phosphate (S1P, the breakdown product of ceramide, which is an important signaling molecule in mammalian biology. Therefore, the purpose of this study was to examine the impact of obesity on circulating S1P concentration and its relationship with markers of glucose metabolism and insulin sensitivity. METHODOLOGY/PRINCIPAL FINDINGS: Plasma S1P levels were determined in high-fat diet (HFD-induced and genetically obese (ob/ob mice along with obese humans. Circulating S1P was elevated in both obese mouse models and in obese humans compared with lean healthy controls. Furthermore, in humans, plasma S1P positively correlated with total body fat percentage, body mass index (BMI, waist circumference, fasting insulin, HOMA-IR, HbA1c (%, total and LDL cholesterol. In addition, fasting increased plasma S1P levels in lean healthy mice. CONCLUSION: We show that elevations in plasma S1P are a feature of both human and rodent obesity and correlate with metabolic abnormalities such as adiposity and insulin resistance.

Impaired Phosphate Tolerance Revealed With an Acute Oral Challenge.

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Turner, Mandy E; White, Christine A; Hopman, Wilma M; Ward, Emilie C; Jeronimo, Paul S; Adams, Michael A; Holden, Rachel M

2018-01-01

Elevated serum phosphate is consistently linked with cardiovascular disease (CVD) events and mortality in the setting of normal and impaired kidney function. However, serum phosphate does not often exceed the upper limit of normal until glomerular filtration rate (GFR) falls below 30 mL/min/m 2 . It was hypothesized that the response to an oral, bioavailable phosphate load will unmask impaired phosphate tolerance, a maladaptation not revealed by baseline serum phosphate concentrations. In this study, rats with varying kidney function as well as normo-phosphatemic human subjects, with inulin-measured GFR (13.2 to 128.3mL/min), received an oral phosphate load. Hormonal and urinary responses were evaluated over 2 hours. Results revealed that the more rapid elevation of serum phosphate was associated with subjects and rats with higher levels of kidney function, greater responsiveness to acute changes in parathyroid hormone (PTH), and significantly more urinary phosphate at 2 hours. In humans, increases in urinary phosphate to creatinine ratio did not correlate with baseline serum phosphate concentrations but did correlate strongly to early increase of serum phosphate. The blunted rise in serum phosphate in rats with CKD was not the result of altered absorption. This result suggests acute tissue deposition may be altered in the setting of kidney function impairment. Early recognition of impaired phosphate tolerance could translate to important interventions, such as dietary phosphate restriction or phosphate binders, being initiated at much higher levels of kidney function than is current practice. © 2017 American Society for Bone and Mineral Research. © 2017 American Society for Bone and Mineral Research.

Quantitation of dialkyl phosphate metabolites of organophosphate pesticides in human urine using GC-MS-MS with isotopic internal standards.

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Bravo, Roberto; Driskell, William J; Whitehead, Ralph D; Needham, Larry L; Barr, Dana B

2002-01-01

Human exposure to organophosphate pesticides can be estimated from the presence of urinary metabolites. An isotope-dilution gas chromatography-tandem mass spectrometry (GC-MS-MS) method was developed for quantitating the six dialkyl phosphate urinary metabolites of at least 29 organophosphate pesticides. Urine samples were spiked with stable isotope analogues of the dialkyl phosphates, evaporated using azeotropic distillation, followed by chemical derivatization of the metabolites to their respective chloropropyl phosphate esters. The chloropropyl phosphate esters were concentrated and then analyzed using GC-MS-MS. The limits of detection (LODs) of the method were in the low-to-mid picogram-per-milliliter range (parts per trillion) with coefficients of variation of less than 20%. The use of stable isotope analogues as internal standards for each of these metabolites allows for the highest degree of accuracy and precision. Additionally, the low LODs allow the use of this method in general population studies.

Cloning, expression and characterization of a mammalian Nudix hydrolase-like enzyme that cleaves the pyrophosphate bond of UDP-glucose.

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Yagi, Toshihiro; Baroja-Fernández, Edurne; Yamamoto, Ryuji; Muñoz, Francisco José; Akazawa, Takashi; Hong, Kyoung Su; Pozueta-Romero, Javier

2003-03-01

A distinct UDP-glucose (UDPG) pyrophosphatase (UGPPase, EC 3.6.1.45) has been characterized using pig kidney ( Sus scrofa ). This enzyme hydrolyses UDPG, the precursor molecule of numerous glycosylation reactions in animals, to produce glucose 1-phosphate (G1P) and UMP. Sequence analyses of the purified enzyme revealed that, similar to the case of a nucleotide-sugar hydrolase controlling the intracellular levels of ADP-glucose linked to glycogen biosynthesis in Escherichia coli [Moreno-Bruna, Baroja-Fernández, Muñoz, Bastarrica-Berasategui, Zandueta-Criado, Rodri;guez-López, Lasa, Akazawa and Pozueta-Romero (2001) Proc. Natl. Acad. Sci. U.S.A. 98, 8128-8132], UGPPase appears to be a member of the ubiquitously distributed group of nucleotide pyrophosphatases designated Nudix hydrolases. A complete cDNA of the UGPPase-encoding gene, designated UGPP, was isolated from a human thyroid cDNA library and expressed in E. coli. The resulting cells accumulated a protein that showed kinetic properties identical to those of pig UGPPase.

Earthing the human body influences physiologic processes.

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Sokal, Karol; Sokal, Pawel

2011-04-01

This study was designed to answer the question: Does the contact of the human organism with the Earth via a copper conductor affect physiologic processes? Subjects and experiments: Five (5) experiments are presented: experiment 1-effect of earthing on calcium-phosphate homeostasis and serum concentrations of iron (N = 84 participants); experiment 2-effect of earthing on serum concentrations of electrolytes (N = 28); experiment 3-effect of earthing on thyroid function (N = 12); experiment 4-effect of earthing on glucose concentration (N = 12); experiment 5-effect of earthing on immune response to vaccine (N = 32). Subjects were divided into two groups. One (1) group of people was earthed, while the second group remained without contact with the Earth. Blood and urine samples were examined. Earthing of an electrically insulated human organism during night rest causes lowering of serum concentrations of iron, ionized calcium, inorganic phosphorus, and reduction of renal excretion of calcium and phosphorus. Earthing during night rest decreases free tri-iodothyronine and increases free thyroxine and thyroid-stimulating hormone. The continuous earthing of the human body decreases blood glucose in patients with diabetes. Earthing decreases sodium, potassium, magnesium, iron, total protein, and albumin concentrations while the levels of transferrin, ferritin, and globulins α1, α2, β, and γ increase. These results are statistically significant. Earthing the human body influences human physiologic processes. This influence is observed during night relaxation and during physical activity. Effect of the earthing on calcium-phosphate homeostasis is the opposite of that which occurs in states of weightlessness. It also increases the activity of catabolic processes. It may be the primary factor regulating endocrine and nervous systems.

Subcellular Characterization of Porcine Oocytes with Different Glucose-6-phosphate Dehydrogenase Activities

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Bo Fu

2015-12-01

Full Text Available The in vitro maturation (IVM efficiency of porcine embryos is still low because of poor oocyte quality. Although brilliant cresyl blue positive (BCB+ oocytes with low glucose-6-phosphate dehydrogenase (G6PDH activity have shown superior quality than BCB negative (− oocytes with high G6PDH activity, the use of a BCB staining test before IVM is still controversial. This study aimed to shed more light on the subcellular characteristics of porcine oocytes after selection using BCB staining. We assessed germinal vesicle chromatin configuration, cortical granule (CG migration, mitochondrial distribution, the levels of acetylated lysine 9 of histone H3 (AcH3K9 and nuclear apoptosis features to investigate the correlation between G6PDH activity and these developmentally related features. A pattern of chromatin surrounding the nucleoli was seen in 53.0% of BCB+ oocytes and 77.6% of BCB+ oocytes showed peripherally distributed CGs. After IVM, 48.7% of BCB+ oocytes had a diffused mitochondrial distribution pattern. However, there were no significant differences in the levels of AcH3K9 in the nuclei of blastocysts derived from BCB+ and BCB− oocytes; at the same time, we observed a similar incidence of apoptosis in the BCB+ and control groups. Although this study indicated that G6PDH activity in porcine oocytes was correlated with several subcellular characteristics such as germinal vesicle chromatin configuration, CG migration and mitochondrial distribution, other features such as AcH3K9 level and nuclear apoptotic features were not associated with G6PDH activity and did not validate the BCB staining test. In using this test for selecting porcine oocytes, subcellular characteristics such as the AcH3K9 level and apoptotic nuclear features should also be considered. Adding histone deacetylase inhibitors or apoptosis inhibitors into the culture medium used might improve the efficiency of IVM of BCB+ oocytes.

Glucose balance and muscle glycogen during TPN in the early post-operative phase

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Henneberg, S; Stjernström, H; Essén-Gustavsson, B

1985-01-01

In order to study how muscle glycogen is influenced by different nutritional regimens in the early post-operative period we took muscle biopsies from 20 patients preoperatively and on the fourth post-operative day after abdominal aortic surgery. Ten patients received 93% of non-protein energy......-production) were performed and from these data glucose balance was calculated as the difference between glucose intake and glucose expenditure. Muscle biopsies were analysed for glycogen, adenosine triphosphate, glucose-6-phosphate, lactate and citrate. We found that it was possible to maintain muscle...... glycogen stores at pre-operative levels with a glucose-insulin regimen. With the fat regimen there was a 31% decrease in muscle glycogen and two patients had a negative glucose balance despite the fact that 150 g of glucose were given. Average glucose balance throughout the study correlated positively...

Protective effects of antioxidants on high Glucose-induced malfunctions in human glomerular mesangial cells

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Hosseini R

2000-08-01

Full Text Available Altered functions of mesangial cells induced by high glucose concentrations are thought to play an important role in the pathogenesis of diabetic nephropathy. We therefore investigated the effect of high glucose (39.2 mM alone and in combination with taurine (500 µM or vitamin E (100 µM in serum free medium (RPMI 1640 on the proliferative growth response and turnover of type IV collagen by human glomerular mesangial cells (GMC. The results showed that the high glucose level decreases the proliferation of the GMC which is reversed by taurine and vitamin E. In order to control the osmotic effects of high glucose, the GMC were also cultured in the presence of manitol. Manitol had no effect on the proliferation of GMC. Furthermore, the results showed that addition of vitamin E or taurine to media containing high glucose could reverse and normalize the collagen turn-over by the cultured mesangial cells. These results suggest that taurie and vitamin E may function as endogenous agents in the kidney to limit the development of glomerulosclerosis in diabetic renal disease.

Metabolic engineering of Corynebacterium glutamicum to produce GDP-L-fucose from glucose and mannose.

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Chin, Young-Wook; Park, Jin-Byung; Park, Yong-Cheol; Kim, Kyoung Heon; Seo, Jin-Ho

2013-06-01

Wild-type Corynebacterium glutamicum was metabolically engineered to convert glucose and mannose into guanosine 5'-diphosphate (GDP)-L-fucose, a precursor of fucosyl-oligosaccharides, which are involved in various biological and pathological functions. This was done by introducing the gmd and wcaG genes of Escherichia coli encoding GDP-D-mannose-4,6-dehydratase and GDP-4-keto-6-deoxy-D-mannose-3,5-epimerase-4-reductase, respectively, which are known as key enzymes in the production of GDP-L-fucose from GDP-D-mannose. Coexpression of the genes allowed the recombinant C. glutamicum cells to produce GDP-L-fucose in a minimal medium containing glucose and mannose as carbon sources. The specific product formation rate was much higher during growth on mannose than on glucose. In addition, the specific product formation rate was further increased by coexpressing the endogenous phosphomanno-mutase gene (manB) and GTP-mannose-1-phosphate guanylyl-transferase gene (manC), which are involved in the conversion of mannose-6-phosphate into GDP-D-mannose. However, the overexpression of manA encoding mannose-6-phosphate isomerase, catalyzing interconversion of mannose-6-phosphate and fructose-6-phosphate showed a negative effect on formation of the target product. Overall, coexpression of gmd, wcaG, manB and manC in C. glutamicum enabled production of GDP-L-fucose at the specific rate of 0.11 mg g cell(-1) h(-1). The specific GDP-L-fucose content reached 5.5 mg g cell(-1), which is a 2.4-fold higher than that of the recombinant E. coli overexpressing gmd, wcaG, manB and manC under comparable conditions. Well-established metabolic engineering tools may permit optimization of the carbon and cofactor metabolisms of C. glutamicum to further improve their production capacity.

Glucose-6-phosphate dehydrogenase deficiency in people living in malaria endemic districts of Nepal.

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Ghimire, Prakash; Singh, Nihal; Ortega, Leonard; Rijal, Komal Raj; Adhikari, Bipin; Thakur, Garib Das; Marasini, Baburam

2017-05-23

Glucose-6-phosphate dehydrogenase (G6PD) is a rate limiting enzyme of the pentose phosphate pathway and is closely associated with the haemolytic disorders among patients receiving anti-malarial drugs, such as primaquine. G6PD deficiency (G6PDd) is an impending factor for radical treatment of malaria which affects the clearance of gametocytes from the blood and subsequent delay in the achievement of malaria elimination. The main objective of this study was to assess the prevalence of G6PD deficiency in six malaria endemic districts in Southern Nepal. A cross-sectional population based prevalence survey was conducted in six malaria endemic districts of Nepal, during April-Dec 2013. A total of 1341 blood samples were tested for G6PDd using two different rapid diagnostic test kits (Binax-Now ® and Care Start™). Equal proportions of participants from each district (n ≥ 200) were enrolled considering ethnic and demographic representation of the population groups. Out of total 1341 blood specimens collected from six districts, the overall prevalence of G6PDd was 97/1341; 7.23% on Binax Now and 81/1341; 6.0% on Care Start test. Higher prevalence was observed in male than females [Binax Now: male 10.2%; 53/521 versus female 5.4%; 44/820 (p = 0.003) and Care Start: male 8.4%; 44/521 versus female 4.5%; 37/820 (p = 0.003)]. G6PDd was higher in ethnic groups Rajbanshi (11.7%; 19/162) and Tharu (5.6%; 56/1005) (p = 0.006), major inhabitant of the endemic districts. Higher prevalence of G6PDd was found in Jhapa (22/224; 9.8%) and Morang districts (18/225; 8%) (p = 0.031). In a multivariate analysis, male were found at more risk for G6PDd than females, on Binax test (aOR = 1.97; CI 1.28-3.03; p = 0.002) and Care Start test (aOR = 1.86; CI 1.16-2.97; p = 0.009). The higher prevalence of G6PDd in certain ethnic group, gender and geographical region clearly demonstrates clustering of the cases and ascertained the risk groups within the population. This is the

Sphingosine-1-Phosphate Signaling Regulates Myogenic Responsiveness in Human Resistance Arteries.

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Sonya Hui

Full Text Available We recently identified sphingosine-1-phosphate (S1P signaling and the cystic fibrosis transmembrane conductance regulator (CFTR as prominent regulators of myogenic responsiveness in rodent resistance arteries. However, since rodent models frequently exhibit limitations with respect to human applicability, translation is necessary to validate the relevance of this signaling network for clinical application. We therefore investigated the significance of these regulatory elements in human mesenteric and skeletal muscle resistance arteries. Mesenteric and skeletal muscle resistance arteries were isolated from patient tissue specimens collected during colonic or cardiac bypass surgery. Pressure myography assessments confirmed endothelial integrity, as well as stable phenylephrine and myogenic responses. Both human mesenteric and skeletal muscle resistance arteries (i express critical S1P signaling elements, (ii constrict in response to S1P and (iii lose myogenic responsiveness following S1P receptor antagonism (JTE013. However, while human mesenteric arteries express CFTR, human skeletal muscle resistance arteries do not express detectable levels of CFTR protein. Consequently, modulating CFTR activity enhances myogenic responsiveness only in human mesenteric resistance arteries. We conclude that human mesenteric and skeletal muscle resistance arteries are a reliable and consistent model for translational studies. We demonstrate that the core elements of an S1P-dependent signaling network translate to human mesenteric resistance arteries. Clear species and vascular bed variations are evident, reinforcing the critical need for further translational study.

Use of osmolytes during solubilization and reconstitution of phosphate: sugar phosphate antiport from bacteria

International Nuclear Information System (INIS)

Ambudkar, S.V.; Sonna, L.A.; Maloney, P.C.

1986-01-01

Phosphate:2-deoxyglucose 6-phosphate (Pi:2DG6P) antiport was extracted from Streptococcus lactis or Staphylococcus aureus with 1.1% octylglucoside in the presence of 0.37% E. coli lipid and reconstituted by detergent dilution. Because previous work suggested inactivation at an early stage, the authors introduced protein stabilants during solubilization. When 20% glycerol was used, proteoliposomes showed a 20-fold increase in 32 Pi transport. This enhanced recovery required phospholipid plus glycerol, and was found only when both were added together with the detergent. Glycerol protection yielded proteoliposomes in which antiporters retained their normal kinetic properties, and Pi exchange by the streptococcal example gave a maximal rate (200-400 nmol/min per mg protein) and a turnover number (30-50/s) which suggested that inactivation had been avoided. Further study showed that 20% glycerol could be replaced by equally high concentrations of compounds classified as osmolytes polyols (erythritol, xylitol, sorbitol), sugars (glucose, trehalose) and certain amino acids (glycine, proline, but not valine). The authors suggest that osmolytes may be used to fully stabilize chemiosmotic transporters during reconstitution

Sucrose Phosphate Synthase and Sucrose Accumulation at Low Temperature 1

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Guy, Charles L.; Huber, Joan L. A.; Huber, Steven C.

1992-01-01

The influence of growth temperature on the free sugar and sucrose phosphate synthase content and activity of spinach (Spinacia oleracea) leaf tissue was studied. When plants were grown at 25°C for 3 weeks and then transferred to a constant 5°C, sucrose, glucose, and fructose accumulated to high levels during a 14-d period. Predawn sugar levels increased from 14- to 20-fold over the levels present at the outset of the low-temperature treatment. Sucrose was the most abundant free sugar before, during, and after exposure to 5°C. Leaf sucrose phosphate synthase activity was significantly increased by the low-temperature treatment, whereas sucrose synthase and invertases were not. Synthesis of the sucrose phosphate synthase subunit was increased during and after low-temperature exposure and paralleled an increase in the steady-state level of the subunit. The increases in sucrose and its primary biosynthetic enzyme, sucrose phosphate synthase, are discussed in relation to adjustment of metabolism to low nonfreezing temperature and freezing stress tolerance. Images Figure 1 Figure 2 Figure 3 PMID:16652990

Rock phosphate solubilizing and cellulolytic actinomycete isolates of earthworm casts

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Mba, Caroline C.

1994-03-01

Four microbial isolates, OP2, OP3, OP6, and OP7, of earthworm casts of Pontoscolex corethrurus were found to be acid tolerant actinomycetes and efficient rock phosphate (RP) solubilizers that could grow fast on NH4Cl-enriched or N-free carboxymethyl cellulose or glucose as sole carbon source. CMC (carboxymethyl cellulose) induced production of extracellular cellulase enzyme and the production of reducing sugar in all the isolates. RP solubilizing power was observed to be inversely related to glucose consumption. The most efficient RP solubilizer was found to consume the least glucose. Growth was faster on cellulose than on glucose media. N-free CMC induced greater glucose production than NH4Cl-enriched CMC medium. Both CMC and glucose media were acidified by all the isolates, however, RP solubilizing power decreased with acidification. Solubilization power was greatest with isolate OP7, which also produced the greatest amount of reducing sugar per gram CMC. Both RP solubilizing power and the cellulolytic efficiency varied among isolates. A minimum of 631 µg P/0.1 g RP and a maximum of 951.4 µg P/0.1 g RP was recorded.

Differential subnetwork of chemokines/cytokines in human, mouse, and rat brain cells after oxygen-glucose deprivation.

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Du, Yang; Deng, Wenjun; Wang, Zixing; Ning, MingMing; Zhang, Wei; Zhou, Yiming; Lo, Eng H; Xing, Changhong

2017-04-01

Mice and rats are the most commonly used animals for preclinical stroke studies, but it is unclear whether targets and mechanisms are always the same across different species. Here, we mapped the baseline expression of a chemokine/cytokine subnetwork and compared responses after oxygen-glucose deprivation in primary neurons, astrocytes, and microglia from mouse, rat, and human. Baseline profiles of chemokines (CX3CL1, CXCL12, CCL2, CCL3, and CXCL10) and cytokines (IL-1α, IL-1β, IL-6, IL-10, and TNFα) showed significant differences between human and rodents. The response of chemokines/cytokines to oxygen-glucose deprivation was also significantly different between species. After 4 h oxygen-glucose deprivation and 4 h reoxygenation, human and rat neurons showed similar changes with a downregulation in many chemokines, whereas mouse neurons showed a mixed response with up- and down-regulated genes. For astrocytes, subnetwork response patterns were more similar in rats and mice compared to humans. For microglia, rat cells showed an upregulation in all chemokines/cytokines, mouse cells had many down-regulated genes, and human cells showed a mixed response with up- and down-regulated genes. This study provides proof-of-concept that species differences exist in chemokine/cytokine subnetworks in brain cells that may be relevant to stroke pathophysiology. Further investigation of differential gene pathways across species is warranted.

Glucose Synthesis in a Protein-Based Artificial Photosynthesis System.

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Lu, Hao; Yuan, Wenqiao; Zhou, Jack; Chong, Parkson Lee-Gau

2015-09-01

The objective of this study was to understand glucose synthesis of a protein-based artificial photosynthesis system affected by operating conditions, including the concentrations of reactants, reaction temperature, and illumination. Results from non-vesicle-based glyceraldehyde-3-phosphate (GAP) and glucose synthesis showed that the initial concentrations of ribulose-1,5-bisphosphate (RuBP) and adenosine triphosphate (ATP), lighting source, and temperature significantly affected glucose synthesis. Higher initial concentrations of RuBP and ATP significantly enhanced GAP synthesis, which was linearly correlated to glucose synthesis, confirming the proper functions of all catalyzing enzymes in the system. White fluorescent light inhibited artificial photosynthesis and reduced glucose synthesis by 79.2 % compared to in the dark. The reaction temperature of 40 °C was optimum, whereas lower or higher temperature reduced glucose synthesis. Glucose synthesis in the vesicle-based artificial photosynthesis system reconstituted with bacteriorhodopsin, F 0 F 1 ATP synthase, and polydimethylsiloxane-methyloxazoline-polydimethylsiloxane triblock copolymer was successfully demonstrated. This system efficiently utilized light-induced ATP to drive glucose synthesis, and 5.2 μg ml(-1) glucose was synthesized in 0.78-ml reaction buffer in 7 h. Light-dependent reactions were found to be the bottleneck of the studied artificial photosynthesis system.

Prevalence of anemia, iron deficiency, thalassemia and glucose-6-phosphate dehydrogenase deficiency among hill-tribe school children in Omkoi District, Chiang Mai Province, Thailand.

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Yanola, Jintana; Kongpan, Chatpat; Pornprasert, Sakorn

2014-07-01

The prevalaence of anemia, iron deficiency, thalassemia and glucose-6-phosphate dehydrogenase (G-6-PD) deficiency were examined among 265 hill-tribe school children, 8-14 years of age, from Omkoi District, Chiang Mai Province, Thailand. Anemia was observed in 20 school children, of whom 3 had iron deficiency anemia. The prevalence of G-6-PD deficiency and β-thalassemia trait [codon 17 (A>T), IVSI-nt1 (G>T) and codons 71/72 (+A) mutations] was 4% and 8%, respectively. There was one Hb E trait, and no α-thalassemia-1 SEA or Thai type deletion. Furthermore, anemia was found to be associated with β-thalassemia trait in 11 children. These data can be useful for providing appropriate prevention and control of anemia in this region of Thailand.

Glycogenolysis in astrocytes supports blood-borne glucose channeling not glycogen-derived lactate shuttling to neurons: evidence from mathematical modeling.

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DiNuzzo, Mauro; Mangia, Silvia; Maraviglia, Bruno; Giove, Federico

2010-12-01

In this article, we examined theoretically the role of human cerebral glycogen in buffering the metabolic requirement of a 360-second brain stimulation, expanding our previous modeling study of neurometabolic coupling. We found that glycogen synthesis and degradation affects the relative amount of glucose taken up by neurons versus astrocytes. Under conditions of 175:115 mmol/L (∼1.5:1) neuronal versus astrocytic activation-induced Na(+) influx ratio, ∼12% of astrocytic glycogen is mobilized. This results in the rapid increase of intracellular glucose-6-phosphate level on stimulation and nearly 40% mean decrease of glucose flow through hexokinase (HK) in astrocytes via product inhibition. The suppression of astrocytic glucose phosphorylation, in turn, favors the channeling of glucose from interstitium to nearby activated neurons, without a critical effect on the concurrent intercellular lactate trafficking. Under conditions of increased neuronal versus astrocytic activation-induced Na(+) influx ratio to 190:65 mmol/L (∼3:1), glycogen is not significantly degraded and blood glucose is primarily taken up by neurons. These results support a role for astrocytic glycogen in preserving extracellular glucose for neuronal utilization, rather than providing lactate to neurons as is commonly accepted by the current 'thinking paradigm'. This might be critical in subcellular domains during functional conditions associated with fast energetic demands.

Experimentally Induced Bleaching in the Sea Anemone Exaiptasia Supports Glucose as a Main Metabolite Associated with Its Symbiosis

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Víctor Hugo Molina

2017-01-01

Full Text Available Our current understanding of carbon exchange between partners in the Symbiodinium-cnidarian symbioses is still limited, even though studies employing carbon isotopes have made us aware of the metabolic complexity of this exchange. We examined glycerol and glucose metabolism to better understand how photosynthates are exchanged between host and symbiont. The levels of these metabolites were compared between symbiotic and bleached Exaiptasia pallida anemones, assaying enzymes directly involved in their metabolism. We measured a significant decrease of glucose levels in bleached animals but a significant increase in glycerol and G3P pools, suggesting that bleached animals degrade lipids to compensate for the loss of symbionts and seem to rely on symbiotic glucose. The lower glycerol 3-phosphate dehydrogenase but higher glucose 6-phosphate dehydrogenase specific activities measured in bleached animals agree with a metabolic deficit mainly due to the loss of glucose from the ruptured symbiosis. These results corroborate previous observations on carbon translocation from symbiont to host in the sea anemone Exaiptasia, where glucose was proposed as a main translocated metabolite. To better understand photosynthate translocation and its regulation, additional research with other symbiotic cnidarians is needed, in particular, those with calcium carbonate skeletons.

A 96-well automated method to study inhibitors of human sodium-dependent D-glucose transport.

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Castaneda, Francisco; Kinne, Rolf K-H

2005-12-01

The sodium-dependent D-glucose transporter (SGLT) family is involved in glucose uptake via intestinal absorption (SGLT1) or renal reabsorption (SGLT1 and SGLT2). Current methods for the screening of inhibitors of SGLT transporters are complex, expensive and very labor intensive, and have not been applied to human SGLT transporters. The purpose of the present study was to develop an alternative 96-well automated method to study the activity of human SGLT1 and SGLT2. Chinese hamster ovary (CHO) Flp-In cells were stably transfected with pcDNA5-SGLT1 or pcDNA5-SGLT2 plasmid and maintained in hygromycin-selection Ham's F12 culture medium until hygromycin-resistant clones were developed. SGLT1 and SGLT2 gene expression was evaluated by relative real-time reverse transcription-polymerase chain reaction (RT-PCR) quantification, Western blotting, and immunocytochemical analysis. The clones with higher expression of SGLT1 and SGLT2 were used for transport studies using [14C]-methyl-alpha-D-glucopyranoside ([14C]AMG). The advantage of using the 96-well format is the low amount of radioactive compounds and inhibitory substances required, and its ability to establish reproducibility because repetition into the assay. This method represents an initial approach in the development of transport-based high-throughput screening in the search for inhibitors of glucose transport. The proposed method can easily be performed to yield quantitative data regarding key aspects of glucose membrane transport and kinetic studies of potential inhibitors of human SGLT1 and SGLT2.

Analysis of trehalose-6-phosphate control over carbon allocation and growth in plants

NARCIS (Netherlands)

Aghdasi, M.

2007-01-01

Trehalose is the non-reducing alpha-alpha-1, 1-linked glucose disaccharide. The biosynthesic precursor of trehalose, trehalose-6-phosphate (T6P), is essential for plant development, growth, carbon utilization and alters photosynthetic capacity but its mode of action is not underestood. This thesis

Perspective use of direct human blood as an energy source in air-breathing hybrid microfluidic fuel cells

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Dector, A.; Escalona-Villalpando, R. A.; Dector, D.; Vallejo-Becerra, V.; Chávez-Ramírez, A. U.; Arriaga, L. G.; Ledesma-García, J.

2015-08-01

This work presents a flexible and light air-breathing hybrid microfluidic fuel cell (HμFC) operated under biological conditions. A mixture of glucose oxidase, glutaraldehyde, multi-walled carbon nanotubes and vulcan carbon (GOx/VC-MWCNT-GA) was used as the bioanode. Meanwhile, integrating an air-exposed electrode (Pt/C) as the cathode enabled direct oxygen delivery from air. The microfluidic fuel cell performance was evaluated using glucose obtained from three different sources as the fuel: 5 mM glucose in phosphate buffer, human serum and human blood. For the last fuel, an open circuit voltage and maximum power density of 0.52 V and 0.20 mW cm-2 (at 0.38 V) were obtained respectively; meanwhile the maximum current density was 1.1 mA cm-2. Furthermore, the stability of the device was measured in terms of recovery after several polarization curves, showing excellent results. Although this air-breathing HμFC requires technological improvements before being tested in a biomedical device, it represents the best performance to date for a microfluidic fuel cell using human blood as glucose source.

Seizure is a rare presentation for acute hemolysis due to G6PD deficiency. We report a previously healthy boy who presented initially with seizure and cyanosis and subsequently acute hemolysis, due to glucose-6-phosphate dehydrogenase deficiency (G6PD) an

OpenAIRE

Afshin FAYYAZI; Ali KHAJEH; Hosein ESFAHANI

2012-01-01

Seizure is a rare presentation for acute hemolysis due to G6PD deficiency. We report a previously healthy boy who presented initially with seizure and cyanosis and subsequently acute hemolysis, due to glucose-6-phosphate dehydrogenase deficiency (G6PD) and probably secondary methemoglobinemia, following the ingestion of fava beans.

Exercise-induced increase in glucose transport, GLUT-4, and VAMP-2 in plasma membrane from human muscle

DEFF Research Database (Denmark)

Kristiansen, S; Hargreaves, Mark; Richter, Erik

1996-01-01

contractions may induce trafficking of GLUT-4-containing vesicles via a mechanism similar to neurotransmitter release. Our results demonstrate for the first time exercise-induced translocation of GLUT-4 and VAMP-2 to the plasma membrane of human muscle and increased sarcolemmal glucose transport.......A major effect of muscle contractions is an increase in sarcolemmal glucose transport. We have used a recently developed technique to produce sarcolemmal giant vesicles from human muscle biopsy samples obtained before and after exercise. Six men exercised for 10 min at 50% maximal O2 uptake (Vo2max...

A glucose biosensor based on direct electron transfer of glucose oxidase immobilized onto glassy carbon electrode modified with nitrophenyl diazonium salt

International Nuclear Information System (INIS)

Nasri, Zahra; Shams, Esmaeil

2013-01-01

Graphical abstract: - Abstract: This study reports a novel, simple and fast approach for construction of a highly stable glucose biosensor based on the immobilization of glucose oxidase (GOx) onto a glassy carbon electrode (GCE) electrografted with 4-aminophenyl (AP) by diazonium chemistry. Aminophenyl was used as cross-linker for covalent attachment of glucose oxidase to the electrode surface. Cyclic voltammograms of the GOx-modified GCE in phosphate buffer solution exhibited a pair of well-defined redox peaks, attesting the direct electron transfer (DET) of GOx with the underlying electrode. The proposed biosensor could be used to detect glucose based on the consumption of O 2 with the oxidation of glucose catalyzed by GOx and exhibited a wide linear range of glucose from 0.05 mM to 4.5 mM and low detection limit of 10 μM. The surface coverage of active GOx, heterogeneous electron transfer rate constant (k s ) and Michaelis–Menten constant (K M ) of immobilized GOx were 1.23 × 10 −12 mol cm −2 , 4.25 s −1 and 2.95 mM, respectively. The great stability of this biosensor, technically simple and possibility of preparation at short period of time make this method suitable for fabrication of low-cost glucose biosensors

Determination of the energetics of the UDP-glucose pyrophosphorylase reaction by positional isotope exchange inhibition

International Nuclear Information System (INIS)

Hester, L.S.; Raushel, F.M.

1987-01-01

A method has been developed for obtaining qualitative information about enzyme-catalyzed reactions by measuring the inhibitory effects of added substrates on positional isotope exchange rates. It has been demonstrated for ordered kinetic mechanisms that an increase in the concentration of the second substrate to add to the enzyme will result in a linear increase in the ratio of the chemical and positional isotope exchange rates. The slopes and intercepts from these plots can be used to determine the partitioning ratios of binary and ternary enzyme complexes. The method has been applied to the reaction catalyzed by UDP-glucose pyrophosphorylase. A positional isotope exchange reaction was measured within oxygen-18-labeled UTP as a function of variable glucose 1-phosphate concentration in the forward reaction. In the reverse reaction, a positional isotope exchange reaction was measured within oxygen-18-labeled UDP-glucose as a function of increasing pyrophosphate concentration. The results have been interpreted to indicate that the interconversion of the ternary central complexes is fast relative to product dissociation in either direction. In the forward direction, the release of UDP-glucose is slower than the release of pyrophosphate. The release of glucose 1-phosphate is slower than the release of UTP in the reverse reaction

Gluconic acid production and phosphate solubilization by the plant growth-promoting bacterium Azospirillum spp.

Science.gov (United States)

Rodriguez, Hilda; Gonzalez, Tania; Goire, Isabel; Bashan, Yoav

2004-11-01

In vitro gluconic acid formation and phosphate solubilization from sparingly soluble phosphorus sources by two strains of the plant growth-promoting bacteria A. brasilense (Cd and 8-I) and one strain of A. lipoferum JA4 were studied. Strains of A. brasilense were capable of producing gluconic acid when grown in sparingly soluble calcium phosphate medium when their usual fructose carbon source is amended with glucose. At the same time, there is a reduction in pH of the medium and release of soluble phosphate. To a greater extent, gluconic acid production and pH reduction were observed for A. lipoferum JA4. For the three strains, clearing halos were detected on solid medium plates with calcium phosphate. This is the first report of in vitro gluconic acid production and direct phosphate solubilization by A. brasilense and the first report of P solubilization by A. lipoferum. This adds to the very broad spectrum of plant growth-promoting abilities of this genus.

31P NMR saturation-transfer measurements in Saccharomyces cerevisiae: characterization of phosphate exchange reactions by iodoacetate and antimycin A inhibition

International Nuclear Information System (INIS)

Campbell-Burk, S.L.; Jones, K.A.; Shulman, R.G.

1987-01-01

31 P nuclear magnetic resonance (NMR) saturation-transfer (ST) techniques have been used to measure steady-state flows through phosphate-adenosine 5'-triphosphate (ATP) exchange reactions in glucose-grown derepressed yeast. The results have revealed that the reactions catalyzed by glyceraldehyde-3-phosphate dehydrogenase/phosphoglycerate kinase (GAPDH/PGK) and by the mitochondrial ATPase contribute to the observed ST. Contributions from these reactions were evaluated by performing ST studies under various metabolic conditions in the presence and absence of either iodoacetate, a specific inhibitor of GAPDH, or the respiratory chain inhibitor antimycin A. Intracellular phosphate (P/sub i/) longitudinal relaxation times were determined by performing inversion recovery experiments during steady-state ATP/sub λ/ saturation and were used in combination with ST data to determine P/sub i/ consumption rates. 13 C NMR and O 2 electrode measurements were also conducted to monitor changes in rates of glucose consumption and O 2 consumption, respectively, under the various metabolic conditions examined. The results suggest that GAPDH/PGK-catalyzed P/sub i/-ATP exchange is responsible for antimycin-resistant saturation transfer observed in anaerobic and aerobic glucose-fed yeast. Kinetics through GAPDH/PGK were found to depend on metabolic conditions. The coupled system appears to operate in a unidirectional manner during anaerobic glucose metabolism and bidirectionally when the cells are respiring on exogenously supplied ethanol. Additionally, mitochondrial ATPase activity appears to be responsible for the transfer observed in iodoacetate-treated aerobic cells supplied with either glucose or ethanol, with synthesis of ATP occurring unidirectionally

Study on the mechanism of human blood glucose concentration measuring using mid-infrared spectral analysis technology

Science.gov (United States)

Li, Xiang

2016-10-01

All forms of diabetes increase the risk of long-term complications. Blood glucose monitoring is of great importance for controlling diabetes procedure, preventing the complications and improving the patient's life quality. At present, the clinical blood glucose concentration measurement is invasive and could be replaced by noninvasive spectroscopy analytical techniques. The mid-infrared spectral region contains strong characteristic and well-defined absorption bands. Therefore, mid-infrared provides an opportunity for monitoring blood glucose invasively with only a few discrete bonds. Although the blood glucose concentration measurement using mid-infrared spectroscopy has a lot of advantages, the disadvantage is also obvious. The absorption in this infrared region is fundamental molecular group vibration. Absorption intensity is very strong, especially for biological molecules. In this paper, it figures out that the osmosis rate of glucose has a certain relationship with the blood glucose concentration. Therefore, blood glucose concentration could be measured indirectly by measuring the glucose exudate in epidermis layer. Human oral glucose tolerance tests were carried out to verify the correlation of glucose exudation in shallow layer of epidermis layer and blood glucose concentration. As it has been explained above, the mid-infrared spectral region contains well-defined absorption bands, the intensity of absorption peak around 1123 cm-1 was selected to measure the glucose and that around 1170 cm-1 was selected as reference. Ratio of absorption peak intensity was recorded for each set of measurement. The effect and importance of the cleaning the finger to be measured before spectrum measuring are discussed and also verified by experiment.

[Intensity of pentose phosphate metabolism of carbohydrates in various brain areas in normal and starved animals].

Science.gov (United States)

Kerimov, B F

2002-01-01

The activities of key enzymes of pentose phosphate pathway, glucose-6-phosphate dehydrogenase (G-6 PD) and 6-phosphogluconate dehydrogenase (6-PGD), were studied in cytoplasmatic fractions of brain cortical (limbic, orbital, sensorimotor cortex) and subcortical (myelencefalon, mesencefalon, hypothalamus) structures of rats subjected to starvation for 1, 2, 3, 5 and 7 days. Short-term starvation (1-3 days) caused activation of 6-GPD and 6-PGD both in cortical and subcortical structures. Long-term starvation for 5-7 days caused a decrease of activities of the pentose phosphate pathway enzymes in all studied structures. It is suggested that enzymes of pentose phosphate pathway in nervous tissues are functionally and metabolically related to glutathione system and during starvation they indirectly participate in the regulation lipid peroxidation processes.

Control analysis of the role of triosephosphate isomerase in glucose metabolism in Lactococcus lactis

DEFF Research Database (Denmark)

Solem, Christian; Købmann, Brian Jensen; Jensen, Peter Ruhdal

2008-01-01

Triosephosphate isomerase (TPI), which catalyses the conversion of dihydroxyacetone phosphate (DHAP) to glyceraldehyde-3-phosphate (G3P), was studied for its control on glycolysis and mixed acid production in L. lactis subspecies lactis IL1403 and L. lactis subspecies cremoris MG1363. Strains...... metabolites glucose-6-phosphate, fructose-1,6-bisphosphate and DHAP in the IL1403 derivatives were essentially unchanged for TPI activities from 26% to 225%. At a TPI activity of 3%, the level of DHAP increased four times. The finding that an increased level of DHAP coincides with an increase in formate...

Oral glucose ingestion attenuates exercise-induced activation of 5'-AMP-activated protein kinase in human skeletal muscle

DEFF Research Database (Denmark)

Åkerström, Thorbjörn; Birk, Jesper Bratz; Klein, Ditte Kjærsgaard

2006-01-01

5'-AMP-activated protein kinase (AMPK) has been suggested to be a 'metabolic master switch' regulating various aspects of muscle glucose and fat metabolism. In isolated rat skeletal muscle, glucose suppresses the activity of AMPK and in human muscle glycogen loading decreases exercise-induced AMPK...... activation. We hypothesized that oral glucose ingestion during exercise would attenuate muscle AMPK activation. Nine male subjects performed two bouts of one-legged knee-extensor exercise at 60% of maximal workload. The subjects were randomly assigned to either consume a glucose containing drink or a placebo...... drink during the two trials. Muscle biopsies were taken from the vastus lateralis before and after 2 h of exercise. Plasma glucose was higher (6.0 +/- 0.2 vs. 4.9 +/- 0.1 mmol L-1, P

Basic calcium phosphate crystal-induced Egr-1 expression stimulates mitogenesis in human fibroblasts

International Nuclear Information System (INIS)

Zeng, Xiao R.; Sun Yubo; Wenger, Leonor; Cheung, Herman S.

2005-01-01

Previously, we have reported that basic calcium phosphate (BCP) crystals stimulate mitogenesis and synthesis of matrix metalloproteinases in cultured human foreskin and synovial fibroblasts. However, the detailed mechanisms involved are still unclear. In the present study, using RT-PCR and Egr-1 promoter analysis we showed that BCP crystals could stimulate early growth response gene Egr-1 transcription through a PKCα-dependent p44/p42 MAPK pathway. Using a retrovirus gene expression system (Clontech) to overexpress Egr-1 in human fibroblast BJ-1 cells resulted in promotion of mitogenesis measured either by MTT cell proliferation analysis or by direct cell counting. The results demonstrate that Egr-1 may play a key role in mediating BCP crystal-induced synovial fibroblast mitogenesis

Effect of Buddleja officinalis on high-glucose-induced vascular inflammation in human umbilical vein endothelial cells.

Science.gov (United States)

Lee, Yun Jung; Kang, Dae Gill; Kim, Jin Sook; Lee, Ho Sub

2008-06-01

In this study, we aimed to investigate whether an aqueous extract of Buddleja officinalis (ABO) suppresses high-glucose-induced vascular inflammatory processes in the primary cultured human umbilical vein endothelial cells (HUVEC). The high-glucose-induced increase in expression of cell adhesion molecules (CAMs) such as intracellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and endothelial-selectin (E-selectin) was significantly attenuated by pretreatment with ABO in a dose-dependent manner. Enhanced cell adhesion caused by high glucose in co-cultured U937 and HUVEC was also blocked by pretreatment with ABO. Pretreatment with ABO also blocked formation of high-glucose-induced reactive oxygen species (ROS). In addition, ABO suppressed the transcriptional activity of NF-kappaB and IkappaB phosphorylation under high-glucose conditions. Pretreatment with N(G)-nitro-l-arginine methyl ester (L-NAME), an endothelial nitric oxide (NO) synthase inhibitor, attenuated the protective action of ABO on high-glucose-induced CAM expression, suggesting a potential role of NO signaling. The present data suggest that ABO could suppress high-glucose-induced vascular inflammatory processes, and ABO may be closely related with the inhibition of ROS and NF-kappaB activation in HUVEC.

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.

Activation of Wnt Signaling in Cortical Neurons Enhances Glucose Utilization through Glycolysis.

Science.gov (United States)

Cisternas, Pedro; Salazar, Paulina; Silva-Álvarez, Carmen; Barros, L Felipe; Inestrosa, Nibaldo C

2016-12-09

The Wnt signaling pathway is critical for a number of functions in the central nervous system, including regulation of the synaptic cleft structure and neuroprotection against injury. Deregulation of Wnt signaling has been associated with several brain pathologies, including Alzheimer's disease. In recent years, it has been suggested that the Wnt pathway might act as a central integrator of metabolic signals from peripheral organs to the brain, which would represent a new role for Wnt signaling in cell metabolism. Energy metabolism is critical for normal neuronal function, which mainly depends on glucose utilization. Brain energy metabolism is important in almost all neurological disorders, to which a decrease in the capacity of the brain to utilize glucose has been linked. However, little is known about the relationship between Wnt signaling and neuronal glucose metabolism in the cellular context. In the present study, we found that acute treatment with the Wnt3a ligand induced a large increase in glucose uptake, without changes in the expression or localization of glucose transporter type 3. In addition, we observed that Wnt3a treatment increased the activation of the metabolic sensor Akt. Moreover, we observed an increase in the activity of hexokinase and in the glycolytic rate, and both processes were dependent on activation of the Akt pathway. Furthermore, we did not observe changes in the activity of glucose-6-phosphate dehydrogenase or in the pentose phosphate pathway. The effect of Wnt3a was independent of both the transcription of Wnt target genes and synaptic effects of Wnt3a. Together, our results suggest that Wnt signaling stimulates glucose utilization in cortical neurons through glycolysis to satisfy the high energy demand of these cells. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

UDP-glucose pyrophosphorylase from tubers of Jerusalem artichoke (Helianthus tuberosus L.)

International Nuclear Information System (INIS)

Otozai, Kiyotaka; Taniguchi, Hajime; Nakamura, Michinori

1973-01-01

UDP-glucose pyrophosphorylase of Jerusalem artichoke tubers was purified 90-fold over the crude extract. The purified enzyme preparation absolutely required magnesium ions for activity. Cobalt ions were 60% as effective as magnesium ions; other divalent cations including manganese showed little or no effect. This enzyme had a pH optimum of 8.5 and a temperature optimum of 40 deg C. ATP and UDP inhibited the activity of this enzyme in both forward and backward directions. Km values for UDP-glucose, inorganic pyrophosphate, glucose-1-phosphate - 14 C and UTP were determined to be 4.45 x 10 -4 , 2.33 x 10 -4 , 9.38 x 10 -4 and 2.98 x 10 -4 M, respectively. These results are discussed in comparison with those of UDP-glucose pyrophosphorylases isolated from other plants. (author)

Earthing the Human Body Influences Physiologic Processes

Science.gov (United States)

Sokal, Karol

2011-01-01

Abstract Objectives This study was designed to answer the question: Does the contact of the human organism with the Earth via a copper conductor affect physiologic processes? Subjects and experiments Five (5) experiments are presented: experiment 1—effect of earthing on calcium–phosphate homeostasis and serum concentrations of iron (N = 84 participants); experiment 2—effect of earthing on serum concentrations of electrolytes (N = 28); experiment 3—effect of earthing on thyroid function (N = 12); experiment 4—effect of earthing on glucose concentration (N = 12); experiment 5—effect of earthing on immune response to vaccine (N = 32). Subjects were divided into two groups. One (1) group of people was earthed, while the second group remained without contact with the Earth. Blood and urine samples were examined. Results Earthing of an electrically insulated human organism during night rest causes lowering of serum concentrations of iron, ionized calcium, inorganic phosphorus, and reduction of renal excretion of calcium and phosphorus. Earthing during night rest decreases free tri-iodothyronine and increases free thyroxine and thyroid-stimulating hormone. The continuous earthing of the human body decreases blood glucose in patients with diabetes. Earthing decreases sodium, potassium, magnesium, iron, total protein, and albumin concentrations while the levels of transferrin, ferritin, and globulins α1, α2, β, and γ increase. These results are statistically significant. Conclusions Earthing the human body influences human physiologic processes. This influence is observed during night relaxation and during physical activity. Effect of the earthing on calcium–phosphate homeostasis is the opposite of that which occurs in states of weightlessness. It also increases the activity of catabolic processes. It may be the primary factor regulating endocrine and nervous systems. PMID:21469913

Striking differences in glucose and lactate levels between brain extracellular fluid and plasma in conscious human subjects: effects of hyperglycemia and hypoglycemia.

Science.gov (United States)

Abi-Saab, Walid M; Maggs, David G; Jones, Tim; Jacob, Ralph; Srihari, Vinod; Thompson, James; Kerr, David; Leone, Paola; Krystal, John H; Spencer, Dennis D; During, Matthew J; Sherwin, Robert S

2002-03-01

Brain levels of glucose and lactate in the extracellular fluid (ECF), which reflects the environment to which neurons are exposed, have never been studied in humans under conditions of varying glycemia. The authors used intracerebral microdialysis in conscious human subjects undergoing electrophysiologic evaluation for medically intractable epilepsy and measured ECF levels of glucose and lactate under basal conditions and during a hyperglycemia-hypoglycemia clamp study. Only measurements from nonepileptogenic areas were included. Under basal conditions, the authors found the metabolic milieu in the brain to be strikingly different from that in the circulation. In contrast to plasma, lactate levels in brain ECF were threefold higher than glucose. Results from complementary studies in rats were consistent with the human data. During the hyperglycemia-hypoglycemia clamp study the relationship between plasma and brain ECF levels of glucose remained similar, but changes in brain ECF glucose lagged approximately 30 minutes behind changes in plasma. The data demonstrate that the brain is exposed to substantially lower levels of glucose and higher levels of lactate than those in plasma; moreover, the brain appears to be a site of significant anaerobic glycolysis, raising the possibility that glucose-derived lactate is an important fuel for the brain.

Engineering potato starch with a higher phosphate content

NARCIS (Netherlands)

Xu, Xuan; Huang, Xing Feng; Visser, Richard G.F.; Trindade, Luisa M.

2017-01-01

Phosphate esters are responsible for valuable and unique functionalities of starch for industrial applications. Also in the cell phosphate esters play a role in starch metabolism, which so far has not been well characterized in storage starch. Laforin, a human enzyme composed of a

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

Zinc stimulates glucose oxidation and glycemic control by modulating the insulin signaling pathway in human and mouse skeletal muscle cell lines.

Science.gov (United States)

Norouzi, Shaghayegh; Adulcikas, John; Sohal, Sukhwinder Singh; Myers, Stephen

2018-01-01

Zinc is a metal ion that is an essential cell signaling molecule. Highlighting this, zinc is an insulin mimetic, activating cellular pathways that regulate cellular homeostasis and physiological responses. Previous studies have linked dysfunctional zinc signaling with several disease states including cancer, obesity, cardiovascular disease and type 2 diabetes. The present study evaluated the insulin-like effects of zinc on cell signaling molecules including tyrosine, PRSA40, Akt, ERK1/2, SHP-2, GSK-3β and p38, and glucose oxidation in human and mouse skeletal muscle cells. Insulin and zinc independently led to the phosphorylation of these proteins over a 60-minute time course in both mouse and human skeletal muscle cells. Similarly, utilizing a protein array we identified that zinc could active the phosphorylation of p38, ERK1/2 and GSK-3B in human and ERK1/2 and GSK-3B in mouse skeletal muscle cells. Glucose oxidation assays were performed on skeletal muscle cells treated with insulin, zinc, or a combination of both and resulted in a significant induction of glucose consumption in mouse (pzinc alone. Insulin, as expected, increased glucose oxidation in mouse (pzinc and insulin did not augment glucose consumption in these cells. Zinc acts as an insulin mimetic, activating key molecules implicated in cell signaling to maintain glucose homeostasis in mouse and human skeletal muscle cells. Zinc is an important metal ion implicated in several biological processes. The role of zinc as an insulin memetic in activating key signaling molecules involved in glucose homeostasis could provide opportunities to utilize this ion therapeutically in treating disorders associated with dysfunctional zinc signaling.

Regional characterization of energy metabolism in the brain of normal and MPTP-intoxicated mice using new markers of glucose and phosphate transport

Directory of Open Access Journals (Sweden)

Touhami Jawida

2010-12-01

Full Text Available Abstract The gibbon ape leukemia virus (GALV, the amphotropic murine leukemia virus (AMLV and the human T-cell leukemia virus (HTLV are retroviruses that specifically bind nutrient transporters with their envelope glycoproteins (Env when entering host cells. Here, we used tagged ligands derived from GALV, AMLV, and HTLV Env to monitor the distribution of their cognate receptors, the inorganic phosphate transporters PiT1 and PiT2, and the glucose transporter GLUT1, respectively, in basal conditions and after acute energy deficiency. For this purpose, we monitored changes in the distribution of PiT1, PiT2 and GLUT1 in the cerebellum, the frontal cortex, the corpus callosum, the striatum and the substantia nigra (SN of C57/BL6 mice after administration of 1-methyl-4-phenyl-1,2,3,6 tetrahydropyridinium (MPTP, a mitochondrial complex I inhibitor which induces neuronal degeneration in the striato-nigral network. The PiT1 ligand stained oligodendrocytes in the corpus callosum and showed a reticular pattern in the SN. The PiT2 ligand stained particularly the cerebellar Purkinje cells, while GLUT1 labelling was mainly observed throughout the cortex, basal ganglia and cerebellar gray matter. Interestingly, unlike GLUT1 and PiT2 distributions which did not appear to be modified by MPTP intoxication, PiT1 immunostaining seemed to be more extended in the SN. The plausible reasons for this change following acute energy stress are discussed. These new ligands therefore constitute new metabolic markers which should help to unravel cellular adaptations to a wide variety of normal and pathologic conditions and to determine the role of specific nutrient transporters in tissue homeostasis.

Heterologous expression of pyrroloquinoline quinone (pqq) gene cluster confers mineral phosphate solubilization ability to Herbaspirillum seropedicae Z67.

Science.gov (United States)

Wagh, Jitendra; Shah, Sonal; Bhandari, Praveena; Archana, G; Kumar, G Naresh

2014-06-01

Gluconic acid secretion mediated by the direct oxidation of glucose by pyrroloquinoline quinone (PQQ)-dependent glucose dehydrogenase (GDH) is responsible for mineral phosphate solubilization in Gram-negative bacteria. Herbaspirillum seropedicae Z67 (ATCC 35892) genome encodes GDH apoprotein but lacks genes for the biosynthesis of its cofactor PQQ. In this study, pqqE of Erwinia herbicola (in plasmid pJNK1) and pqq gene clusters of Pseudomonas fluorescens B16 (pOK53) and Acinetobacter calcoaceticus (pSS2) were over-expressed in H. seropedicae Z67. Transformants Hs (pSS2) and Hs (pOK53) secreted micromolar levels of PQQ and attained high GDH activity leading to secretion of 33.46 mM gluconic acid when grown on 50 mM glucose while Hs (pJNK1) was ineffective. Hs (pJNK1) failed to solubilize rock phosphate, while Hs (pSS2) and Hs (pOK53) liberated 125.47 μM and 168.07 μM P, respectively, in minimal medium containing 50 mM glucose under aerobic conditions. Moreover, under N-free minimal medium, Hs (pSS2) and Hs (pOK53) not only released significant P but also showed enhanced growth, biofilm formation, and exopolysaccharide (EPS) secretion. However, indole acetic acid (IAA) production was suppressed. Thus, the addition of the pqq gene cluster, but not pqqE alone, is sufficient for engineering phosphate solubilization in H. seropedicae Z67 without compromising growth under nitrogen-fixing conditions.

Differences in glucose-stimulated insulin secretion in vitro of islets from human, nonhuman primate, and porcine origin.

Science.gov (United States)

Mueller, Kate R; Balamurugan, A N; Cline, Gary W; Pongratz, Rebecca L; Hooper, Rebecca L; Weegman, Bradley P; Kitzmann, Jennifer P; Taylor, Michael J; Graham, Melanie L; Schuurman, Henk-Jan; Papas, Klearchos K

2013-01-01

Porcine islet xenotransplantation is considered a potential cell-based therapy for type 1 diabetes. It is currently being evaluated in diabetic nonhuman primates (NHP) to assess safety and efficacy of the islet product. However, due to a variety of distinct differences between the respective species, including the insulin secretory characteristics of islets, the suitability and predictive value of the preclinical model in the extrapolation to the clinical setting remain a critical issue. Islets isolated from human (n = 3), NHP (n = 2), adult pig (AP, n = 3), and juvenile pig (JP, n = 4) pancreata were perifused with medium at basal glucose (2.5 mm) followed by high glucose (16.7 mm) concentrations. The total glucose-stimulated insulin secretion (GSIS) was calculated from generated insulin secretion profiles. Nonhuman primate islets exhibited GSIS 3-fold higher than AP islets, while AP and JP islets exhibited GSIS 1/3 and 1/30 of human islets, respectively. The insulin content of NHP and AP islets was similar to that of human islets, whereas that of JP islets was 1/5 of human islets. Despite the fact that human, NHP, and AP islets contain similar amounts of insulin, the much higher GSIS for NHP islets than for AP and JP islets suggests the need for increased dosing of islets from JP and AP in pig-to-NHP transplantation. Porcine islet xenotransplantation to humans may require significantly higher dosing given the lower GSIS of AP islets compared to human islets. © 2013 John Wiley & Sons A/S.

Stretchable glucose biofuel cell with wirings made of multiwall carbon nanotubes

International Nuclear Information System (INIS)

Fujimagari, Yusuke; Nishioka, Yasushiro

2015-01-01

In this study, we fabricated a flexible and stretchable glucose-biofuel cell with wirings made of multi wall carbon nanotube (MWCNTs) on a polydimethylsiloxane substrate. The biofuel cell investigated consists of a porous carbon anode (area of 30 mm 2 ) modified by glucose oxidase and ferrocene, and a cathode (area of 30 mm 2 ) modified by bilirubin oxidase. The anode and the cathode were connected with the MWCNT wirings. The maximum power of 0.31 μW at 76.6 mV, which corresponds to a power density of 1.04 μW/cm 2 , was realized by immersing the biofuel cell in a phosphate buffer solution with a glucose concentration of 100 mM, at room temperature. (paper)

Effects of extracellular modulation through hypoxia on the glucose metabolism of human breast cancer stem cells

Science.gov (United States)

Yustisia, I.; Jusman, S. W. A.; Wanandi, S. I.

2017-08-01

Cancer stem cells have been reported to maintain stemness under certain extracellular changes. This study aimed to analyze the effect of extracellular O2 level modulation on the glucose metabolism of human CD24-/CD44+ breast cancer stem cells (BCSCs). The primary BCSCs (CD24-/CD44+ cells) were cultured under hypoxia (1% O2) for 0.5, 4, 6, 24 and 48 hours. After each incubation period, HIF1α, GLUT1 and CA9 expressions, as well as glucose metabolism status, including glucose consumption, lactate production, O2 consumption and extracellular pH (pHe) were analyzed using qRT-PCR, colorimetry, fluorometry, and enzymatic reactions, respectively. Hypoxia caused an increase in HIF1α mRNA expressions and protein levels and shifted the metabolic states to anaerobic glycolysis, as demonstrated by increased glucose consumption and lactate production, as well as decreased O2 consumption and pHe. Furthermore, we demonstrated that GLUT1 and CA9 mRNA expressions simultaneously increased, in line with HIF1α expression. In conclusion, modulation of the extracellular environment of human BCSCs through hypoxia shifedt the metabolic state of BCSCs to anaerobic glycolysis, which might be associated with GLUT1 and CA9 expressions regulated by HIFlα transcription factor.

Low doses of alcohol substantially decrease glucose metabolism in the human brain.

Science.gov (United States)

Volkow, Nora D; Wang, Gene-Jack; Franceschi, Dinko; Fowler, Joanna S; Thanos, Panayotis Peter K; Maynard, Laurence; Gatley, S John; Wong, Christopher; Veech, Richard L; Kunos, George; Kai Li, Ting

2006-01-01

Moderate doses of alcohol decrease glucose metabolism in the human brain, which has been interpreted to reflect alcohol-induced decreases in brain activity. Here, we measure the effects of two relatively low doses of alcohol (0.25 g/kg and 0.5 g/kg, or 5 to 10 mM in total body H2O) on glucose metabolism in the human brain. Twenty healthy control subjects were tested using positron emission tomography (PET) and FDG after placebo and after acute oral administration of either 0.25 g/kg, or 0.5 g/kg of alcohol, administered over 40 min. Both doses of alcohol significantly decreased whole-brain glucose metabolism (10% and 23% respectively). The responses differed between doses; whereas the 0.25 g/kg dose predominantly reduced metabolism in cortical regions, the 0.5 g/kg dose reduced metabolism in cortical as well as subcortical regions (i.e. cerebellum, mesencephalon, basal ganglia and thalamus). These doses of alcohol did not significantly change the scores in cognitive performance, which contrasts with our previous results showing that a 13% reduction in brain metabolism by lorazepam was associated with significant impairment in performance on the same battery of cognitive tests. This seemingly paradoxical finding raises the possibility that the large brain metabolic decrements during alcohol intoxication could reflect a shift in the substrate for energy utilization, particularly in light of new evidence that blood-borne acetate, which is markedly increased during intoxication, is a substrate for energy production by the brain.

Actions of prolonged ghrelin infusion on gastrointestinal transit and glucose homeostasis in humans

DEFF Research Database (Denmark)

Falkén, Y; Hellström, P M; Sanger, G J

2010-01-01

Ghrelin is produced by enteroendocrine cells in the gastric mucosa and stimulates gastric emptying in healthy volunteers and patients with gastroparesis in short-term studies. The aim of this study was to evaluate effects of intravenous ghrelin on gastrointestinal motility and glucose homeostasis...... during a 6-h infusion in humans....

Klotho down-regulates Egr-1 by inhibiting TGF-β1/Smad3 signaling in high glucose treated human mesangial cells

International Nuclear Information System (INIS)

Li, Yang; Hu, Fang; Xue, Meng; Jia, Yi-Jie; Zheng, Zong-Ji; Wang, Ling; Guan, Mei-Ping; Xue, Yao-Ming

2017-01-01

Diabetic kidney disease (DKD) has become the leading cause of end-stage renal disease worldwide and is associated with glomerular mesangial cell (MC) proliferation and excessive extracellular matrix (ECM) production. Klotho can attenuate renal fibrosis in part by inhibiting TGF-β1/Smad3 signaling in DKD. Early growth response factor 1 (Egr-1) has been shown to play a key role in renal fibrosis in part by facilitating the formation of a positive feedback loop involving TGF-β1. However, whether Klotho down-regulates Egr-1 by inhibiting TGF-β1/Smad3 signaling in DKD is unclear. In the present study, we assessed human MCs that were incubated under high-glucose conditions to mimic diabetes. Then, we transfected the cells with Klotho plasmid or siRNA to overexpress or knock down Klotho gene and protein expression. Klotho, Egr-1, fibronectin (FN), collagen type I (Col I), Smad3 and phosphorylated Smad3 (p-Smad3) gene and protein expression levels were determined by RT-qPCR and western blotting respectively. High glucose time-dependently down-regulated Klotho mRNA and protein expression in cultured human MCs. pcDNA3.1-Klotho transfection-mediated Klotho overexpression down-regulated Egr-1, FN and Col I expression and the p-Smad3/Smad3 ratio in human MCs. Conversely, siRNA-mediated Klotho silencing up-regulated Egr-1, FN, and Col I expression and the p-Smad3/Smad3 ratio. Moreover, the effects of si-Klotho on Egr-1 expression were abolished by the TGF-β1 inhibitor SB-431542. Klotho overexpression can prevent mesangial ECM production in high-glucose-treated human MCs, an effect that has been partially attributed to Egr-1 down-regulation facilitated by TGF-β1/Smad3 signaling inhibition. - Highlights: • High glucose time-dependently down-regulated Klotho mRNA and protein expression in cultured human MCs. • Klotho overexpression down-regulated Egr-1 and prevented mesangial ECM production in high-glucose-treated human MCs. • Klotho down-regulated Egr-1 by inhibiting

Effects of flaxseed oil on anti-oxidative system and membrane deformation of human peripheral blood erythrocytes in high glucose level.

Science.gov (United States)

Yang, Wei; Fu, Juan; Yu, Miao; Huang, Qingde; Wang, Di; Xu, Jiqu; Deng, Qianchun; Yao, Ping; Huang, Fenghong; Liu, Liegang

2012-07-08

The erythrocyte membrane lesion is a serious diabetic complication. A number of studies suggested that n-3 fatty acid could reduce lipid peroxidation and elevate α- or γ-tocopherol contents in membrane of erythrocytes. However, evidence regarding the protective effects of flaxseed oil, a natural product rich in n-3 fatty acid, on lipid peroxidation, antioxidative capacity and membrane deformation of erythrocytes exposed to high glucose is limited. Human peripheral blood erythrocytes were isolated and treated with 50 mM glucose to mimic hyperglycemia in the absence or presence of three different doses of flaxseed oil (50, 100 or 200 μM) in the culture medium for 24 h. The malondialdehyde (MDA) and L-glutathione (GSH) were measured by HPLC and LC/MS respectively. The phospholipids symmetry and membrane fatty acid composition of human erythrocytes were detected by flow cytometry and gas chromatograph (GC). The morphology of human erythrocyte was illuminated by ultra scanning electron microscopy. Flaxseed oil attenuated hyperglycemia-induced increase of MDA and decrease of GSH in human erythrocytes. Human erythrocytes treated with flaxseed oil contained higher C22:5 and C22:6 than those in the 50 mM glucose control group, indicating that flaxseed oil could reduce lipid asymmetric distribution and membrane perturbation. The ultra scanning electron microscopy and flow cytometer have also indicated that flaxseed oil could protect the membrane of human erythrocytes from deformation at high glucose level. The flaxseed oil supplementation may prevent lipid peroxidation and membrane dysfunction of human erythrocytes in hyperglycemia.

Lethal effect of glucose load on malignant cells

International Nuclear Information System (INIS)

Shmakova, N.L.; Yarmonenko, S.P.; Kozubek, S.

1987-01-01

Ehrlich ascites tumor (EAT) cells were treated with glucose load under anoxic conditions (for 15 or 60 min) and/or with γ radiation (20 Gy). The efficiency of the treatment was judged from the tumorigenic activity of EAT cell inocula. The markedly increased efficiency of the combined treatment of EAT cells using glucose load in anoxia and γ radiation is due to the additive action of both agents. The glucose load in anoxia leads to extensive desintegration of tumor cells. Further, the lethal effect of various pH values on EAT cells was investigated. Different pH values were obtained by means of both glucose load and phosphate buffers. The effect was investigated by determining the tumorigenic activity of EAT cells tested in vivo in mice and by determining the radiosensitivity of treated EAT cells. The results allowed us to conclude that the same values of pH lead to the same effect on EAT cells independently of the way by which the given pH value was reached. (author). 5 figs., 2 tabs., 12 refs

Transcriptome profiling of brown adipose tissue during cold exposure reveals extensive regulation of glucose metabolism

DEFF Research Database (Denmark)

Hao, Qin; Yadav, Rachita; Basse, Astrid L.

2015-01-01

We applied digital gene expression profiling to determine the transcriptome of brown and white adipose tissues (BAT and WAT, respectively) during cold exposure. Male C57BL/6J mice were exposed to cold for 2 or 4 days. A notable induction of genes related to glucose uptake, glycolysis, glycogen...... exposure, we propose a model for the intermediary glucose metabolism in activated BAT: 1) fluxes through glycolysis and the pentose phosphate pathway are induced, the latter providing reducing equivalents for de novo fatty acid synthesis; 2) glycerol synthesis from glucose is increased, facilitating...

Synthesis and characterization of microparticles based on poly-methacrylic acid with glucose oxidase for biosensor applications.

Science.gov (United States)

Hervás Pérez, J P; López-Ruiz, B; López-Cabarcos, E

2016-01-01

In the line of the applicability of biocompatible monomers pH and temperature dependent, we assayed poly-methacrylic acid (p-MAA) microparticles as immobilization system in the design of enzymatic biosensors. Glucose oxidase was used as enzyme model for the study of microparticles as immobilization matrices and as biological material in the performance of glucose biosensors. The enzyme immobilization method was optimized by investigating the influence of monomer concentration and cross-linker content (N',N'-methylenebisacrylamide), used in the preparation of the microparticles in the response of the biosensors. The kinetics of the polymerization and the effects of the temperature were studied, also the conversion of the polymerization was determinates by a weight method. The structure of the obtained p-MAA microparticles were studied through scanning electron microscopy (SEM) and differential scanning microscopy (DSC). The particle size measurements were performed with a Galai-Cis 1 particle analyzer system. Furthermore, the influence of the swelling behavior of hydrogel matrix as a function of pH and temperature were studied. Analytical properties such as sensitivity, linear range, response time and detection limit were studied for the glucose biosensors. The sensitivity for glucose detection obtained with poly-methacrylic acid (p-MAA) microparticles was 11.98mAM(-1)cm(-2) and 10μM of detection limit. A Nafion® layer was used to eliminate common interferents of the human serum such as uric and ascorbic acids. The biosensors were used to determine glucose in human serum samples with satisfactory results. When stored in a frozen phosphate buffer solution (pH 6.0) at -4°C, the useful lifetime of all biosensors was at least 550 days. Copyright © 2015 Elsevier B.V. All rights reserved.

Nonenzymatic glycosylation of human hemoglobin at multiple sites

International Nuclear Information System (INIS)

Shapiro, R.; McManus, M.; Garrick, L.; McDonald, M.J.; Bunn, H.F.

1979-01-01

The most abundant minor hemoglobin component of human hemolysate is Hb A1c, which has glucose bound to the N-terminus of the beta chain by a ketoamine linkage. Hb A1c is formed slowly and continuously throughout the 120 day lifespan of the red cell. It can be synthesized in vitro by incubating purified hemoglobin with 14C-glucose. Other minor components, Hb A1a1 and Hb A1a2 are adducts of sugar phosphates at the N-terminus of the beta chain. Hb A1b contains an unidentified nonphosphorylated sugar at the beta N-terminus. In addition, a significant portion of the major hemoglobin component (Hb Ao) is also glycosylated by a glucose ketoamine linkage at other sites on the molecule, including the N-terminus of the alpha chain and the epsilon-amino group of several lysine residues on both the alpha and the beta chains. The results indicate that the interaction of glucose and hemoglobin is rather nonspecific and suggests that other proteins are modified in a similar fashion

Evaluation of pink-pigmented facultative methylotrophic bacteria for phosphate solubilization.

Science.gov (United States)

Jayashree, Shanmugam; Vadivukkarasi, Ponnusamy; Anand, Kirupanithi; Kato, Yuko; Seshadri, Sundaram

2011-08-01

Thirteen pink-pigmented facultative methylotrophic (PPFM) strains isolated from Adyar and Cooum rivers in Chennai and forest soil samples in Tamil Nadu, India, along with Methylobacterium extorquens, M. organophilum, M. gregans, and M. komagatae were screened for phosphate solubilization in plates. P-solubilization index of the PPFMs grown on NBRIP-BPB plates for 7 days ranged from 1.1 to 2.7. The growth of PPFMs in tricalcium phosphate amended media was found directly proportional to the glucose concentration. Higher phosphate solubilization was observed in four strains MSF 32 (415 mg l(-l)), MDW 80 (301 mg l(-l)), M. komagatae (279 mg l(-l)), and MSF 34 (202 mg l(-l)), after 7 days of incubation. A drop in the media pH from 6.6 to 3.4 was associated with an increase in titratable acidity. Acid phosphatase activity was more pronounced in the culture filtrate than alkaline phosphatase activity. Adherence of phosphate to densely grown bacterial surface was observed under scanning electron microscope after 7-day-old cultures. Biochemical characterization and screening for methanol dehydrogenase gene (mxaF) confirmed the strains as methylotrophs. The mxaF gene sequence from MSF 32 clustered towards M. lusitanum sp. with 99% similarity. This study forms the first detailed report on phosphate solubilization by the PPFMs.

Neuron-astrocyte interactions, pyruvate carboxylation and the pentose phosphate pathway in the neonatal rat brain

OpenAIRE

Morken, Tora Sund; Brekke, Eva Mari Førland; Håberg, Asta; Widerøe, Marius; Brubakk, Ann-Mari; Sonnewald, Ursula

2014-01-01

Glucose and acetate metabolism and the synthesis of amino acid neurotransmitters, anaplerosis, glutamate-glutamine cycling and the pentose phosphate pathway (PPP) have been extensively investigated in the adult, but not the neonatal rat brain. To do this, 7 day postnatal (P7) rats were injected with [1-(13)C]glucose and [1,2-(13)C]acetate and sacrificed 5, 10, 15, 30 and 45 min later. Adult rats were injected and sacrificed after 15 min. To analyse pyruvate carboxylation and PPP activity duri...

Specific proliferation rates of human osteoblasts on calcium phosphate surfaces with variable concentrations of α-TCP

International Nuclear Information System (INIS)

Santos, Euler A. dos; Farina, Marcos; Soares, Gloria A.

2007-01-01

Ideally, ceramics used in the repair of bone defects need to be resorbed and replaced by newly formed bone in vivo. Tricalcium phosphate (TCP) has been widely used in association with hydroxyapatite (HA) due to its higher resorption kinetics when compared with HA alone. The aim of our study was to quantitatively investigate the effect of α-tricalcium phosphate (α-TCP) on human osteoblasts' adhesion and proliferation. Ceramic samples with variable concentrations of α-TCP and HA were produced by the calcination of calcium-deficient and stoichiometric HA. Human osteoblasts were cultured on the materials in three distinct experiments with different concentrations of cells. Numerical evaluation of cellular growth along time in culture was performed for each condition. The quantity of cells seeded onto the ceramics seems to influence the osteoblast behavior once proliferation was lower when more cells were seeded onto the samples. However, a smaller content of α-TCP in relation to that of HA did not significantly modify the specific proliferation rates of the osteoblasts. Only after a long time in culture, the increasing of the α-TCP content seems to change the cells' behavior

The transcriptional regulator NtrC controls glucose-6-phosphate dehydrogenase expression and polyhydroxybutyrate synthesis through NADPH availability in Herbaspirillum seropedicae.

Science.gov (United States)

Sacomboio, Euclides Nenga Manuel; Kim, Edson Yu Sin; Correa, Henrique Leonardo Ruchaud; Bonato, Paloma; Pedrosa, Fabio de Oliveira; de Souza, Emanuel Maltempi; Chubatsu, Leda Satie; Müller-Santos, Marcelo

2017-10-19

The NTR system is the major regulator of nitrogen metabolism in Bacteria. Despite its broad and well-known role in the assimilation, biosynthesis and recycling of nitrogenous molecules, little is known about its role in carbon metabolism. In this work, we present a new facet of the NTR system in the control of NADPH concentration and the biosynthesis of molecules dependent on reduced coenzyme in Herbaspirillum seropedicae SmR1. We demonstrated that a ntrC mutant strain accumulated high levels of polyhydroxybutyrate (PHB), reaching levels up to 2-fold higher than the parental strain. In the absence of NtrC, the activity of glucose-6-phosphate dehydrogenase (encoded by zwf) increased by 2.8-fold, consequently leading to a 2.1-fold increase in the NADPH/NADP + ratio. A GFP fusion showed that expression of zwf is likewise controlled by NtrC. The increase in NADPH availability stimulated the production of polyhydroxybutyrate regardless the C/N ratio in the medium. The mutant ntrC was more resistant to H 2 O 2 exposure and controlled the propagation of ROS when facing the oxidative condition, a phenotype associated with the increase in PHB content.

Myeloperoxidase amplified high glucose-induced endothelial dysfunction in vasculature: Role of NADPH oxidase and hypochlorous acid.

Science.gov (United States)

Tian, Rong; Ding, Yun; Peng, Yi-Yuan; Lu, Naihao

2017-03-11

Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase-derived reactive oxygen species (ROS) such as superoxide and hydrogen peroxide (H 2 O 2 ), have emerged as important molecules in the pathogenesis of diabetic endothelial dysfunction. Additionally, neutrophils-derived myeloperoxidase (MPO) and MPO-catalyzed hypochlorous acid (HOCl) play important roles in the vascular injury. However, it is unknown whether MPO can use vascular-derived ROS to induce diabetic endothelial dysfunction. In the present study, we demonstrated that NADPH oxidase was the main source of ROS formation in high glucose-cultured human umbilical vein endothelial cells (HUVECs), and played a critical role in high glucose-induced endothelial dysfunction such as cell apoptosis, loss of cell viability and reduction of nitric oxide (NO). However, the addition of MPO could amplify the high glucose-induced endothelial dysfunction which was inhibited by the presence of apocynin (NADPH oxidase inhibitor), catalase (H 2 O 2 scavenger), or methionine (HOCl scavenger), demonstrating the contribution of NADPH oxidase-H 2 O 2 -MPO-HOCl pathway in the MPO/high glucose-induced vascular injury. In high glucose-incubated rat aortas, MPO also exacerbated the NADPH oxidase-induced impairment of endothelium-dependent relaxation. Consistent with these in vitro data, in diabetic rat aortas, both MPO expresion and NADPH oxidase activity were increased while the endothelial function was simultaneously impaired. The results suggested that vascular-bound MPO could amplify high glucose-induced vascular injury in diabetes. MPO-NADPH oxidase-HOCl may represent an important pathogenic pathway in diabetic vascular diseases. Copyright © 2017 Elsevier Inc. All rights reserved.

GLP-1 increases microvascular recruitment but not glucose uptake in human and rat skeletal muscle

DEFF Research Database (Denmark)

Sjøberg, Kim Anker; Holst, Jens Juul; Rattigan, Stephen

2014-01-01

The insulinotropic gut hormone, glucagon-like-peptide-1 (GLP-1) has been proposed to have effects on vascular function and glucose disposal. However, whether GLP-1 is able to increase microvascular recruitment (MVR) in humans has not been investigated. GLP-1 was infused in the femoral artery...... in overnight fasted healthy young men. Microvascular recruitment was measured with real time contrast-enhanced ultrasound and leg glucose uptake by the leg balance technique with and without inhibition of the insulinotropic response of GLP-1 by co-infusion of octreotide. As a positive control, MVR and leg...

Glucose-induced metabolic memory in Schwann cells: prevention by PPAR agonists.

Science.gov (United States)

Kim, Esther S; Isoda, Fumiko; Kurland, Irwin; Mobbs, Charles V

2013-09-01

A major barrier in reversing diabetic complications is that molecular and pathologic effects of elevated glucose persist despite normalization of glucose, a phenomenon referred to as metabolic memory. In the present studies we have investigated the effects of elevated glucose on Schwann cells, which are implicated in diabetic neuropathy. Using quantitative PCR arrays for glucose and fatty acid metabolism, we have found that chronic (>8 wk) 25 mM high glucose induces a persistent increase in genes that promote glycolysis, while inhibiting those that oppose glycolysis and alternate metabolic pathways such as fatty acid metabolism, the pentose phosphate pathway, and trichloroacetic acid cycle. These sustained effects were associated with decreased peroxisome proliferator-activated receptor (PPAR)γ binding and persistently increased reactive oxygen species, cellular NADH, and altered DNA methylation. Agonists of PPARγ and PPARα prevented select effects of glucose-induced gene expression. These observations suggest that Schwann cells exhibit features of metabolic memory that may be regulated at the transcriptional level. Furthermore, targeting PPAR may prevent metabolic memory and the development of diabetic complications.

Subversion of Schwann Cell Glucose Metabolism by Mycobacterium leprae*

Science.gov (United States)

Medeiros, Rychelle Clayde Affonso; Girardi, Karina do Carmo de Vasconcelos; Cardoso, Fernanda Karlla Luz; Mietto, Bruno de Siqueira; Pinto, Thiago Gomes de Toledo; Gomez, Lilian Sales; Rodrigues, Luciana Silva; Gandini, Mariana; Amaral, Julio Jablonski; Antunes, Sérgio Luiz Gomes; Corte-Real, Suzana; Rosa, Patricia Sammarco; Pessolani, Maria Cristina Vidal; Nery, José Augusto da Costa; Sarno, Euzenir Nunes; Batista-Silva, Leonardo Ribeiro; Sola-Penna, Mauro; Oliveira, Marcus Fernandes; Moraes, Milton Ozório; Lara, Flavio Alves

2016-01-01

Mycobacterium leprae, the intracellular etiological agent of leprosy, infects Schwann promoting irreversible physical disabilities and deformities. These cells are responsible for myelination and maintenance of axonal energy metabolism through export of metabolites, such as lactate and pyruvate. In the present work, we observed that infected Schwann cells increase glucose uptake with a concomitant increase in glucose-6-phosphate dehydrogenase (G6PDH) activity, the key enzyme of the oxidative pentose pathway. We also observed a mitochondria shutdown in infected cells and mitochondrial swelling in pure neural leprosy nerves. The classic Warburg effect described in macrophages infected by Mycobacterium avium was not observed in our model, which presented a drastic reduction in lactate generation and release by infected Schwann cells. This effect was followed by a decrease in lactate dehydrogenase isoform M (LDH-M) activity and an increase in cellular protection against hydrogen peroxide insult in a pentose phosphate pathway and GSH-dependent manner. M. leprae infection success was also dependent of the glutathione antioxidant system and its main reducing power source, the pentose pathway, as demonstrated by a 50 and 70% drop in intracellular viability after treatment with the GSH synthesis inhibitor buthionine sulfoximine, and aminonicotinamide (6-ANAM), an inhibitor of G6PDH 6-ANAM, respectively. We concluded that M. leprae could modulate host cell glucose metabolism to increase the cellular reducing power generation, facilitating glutathione regeneration and consequently free-radical control. The impact of this regulation in leprosy neuropathy is discussed. PMID:27555322

Induction of bone formation by smart biphasic hydroxyapatite tricalcium phosphate biomimetic matrices in the non-human primate Papio ursinus

CSIR Research Space (South Africa)

Ripamonti, U

2008-01-01

Full Text Available Long-term studies in the non-human primate Chacma baboon Papio ursinus were set to investigate the induction of bone formation by biphasic hydroxyapatite/β-tricalcium phosphate (HA/β-TCP) biomimetic matrices. HA/β-TCP biomimetic matrices in a pre...

Prevalence of glucose-6-phosphate dehydrogenase deficiency and sickle cell trait among blood donors in Riyadh

Directory of Open Access Journals (Sweden)

Alabdulaali Mohammed

2010-01-01

Full Text Available Background and Aims: Blood donation from glucose-6-phosphate dehydrogenase (G6PD-deficient and sickle cell trait (SCT donors might alter the quality of the donated blood during processing, storage or in the recipient′s circulatory system. The aim of this study was to determine the prevalence of G6PD deficiency and SCT among blood donors coming to King Khalid University Hospital (KKUH in Riyadh. It was also reviewed the benefits and risks of transfusing blood from these blood donors. Materials and Methods: This cross-sectional study was conducted on 1150 blood samples obtained from blood donors that presented to KKUH blood bank during the period April 2006 to May 2006. All samples were tested for Hb-S by solubility test, alkaline gel electrophoresis; and for G6PD deficiency, by fluorescent spot test. Results: Out of the 1150 donors, 23 (2% were diagnosed for SCT, 9 (0.78% for G6PD deficiency and 4 (0.35% for both conditions. Our prevalence of SCT and G6PD deficiency is higher than that of the general population of Riyadh. Conclusion: We recommend to screen all units for G6PD deficiency and sickle cell trait and to defer donations from donors with either of these conditions, unless if needed for special blood group compatibility, platelet apheresis or if these are likely to affect the blood bank inventory. If such blood is to be used, special precautions need to be undertaken to avoid complications in high-risk recipients.

Effect of training on insulin sensitivity of glucose uptake and lipolysis in human adipose tissue

DEFF Research Database (Denmark)

Stallknecht, B; Larsen, J J; Mikines, K J

2000-01-01

Training increases insulin sensitivity of both whole body and muscle in humans. To investigate whether training also increases insulin sensitivity of adipose tissue, we performed a three-step hyperinsulinemic, euglycemic clamp in eight endurance-trained (T) and eight sedentary (S) young men...... (glucose only). Adipose tissue blood flow was measured by (133)Xe washout. In the basal state, adipose tissue blood flow tended to be higher in T compared with S subjects, and in both groups blood flow was constant during the clamp. The change from basal in arterial-interstitial glucose concentration......-time: T, 44 +/- 9 min (n = 7); S, 102 +/- 23 min (n = 5); P training enhances insulin sensitivity of glucose uptake in subcutaneous adipose tissue and in skeletal muscle. Furthermore, interstitial glycerol data suggest that training also increases insulin sensitivity of lipolysis...

Radon Progeny In Underground Phosphate Mines and Their Activity Distributions In Human Lung

International Nuclear Information System (INIS)

Abd El-Hady, M.; Mohammed, A.; El-Hussein, A.; Ali, A.E.; Ahmed, A.A.

2001-01-01

In addition to workers in uranium mines, the staff of other underground mines, such as worker in underground phosphate mines, Can be exposed to 222 Rn and its progeny. In this study the individual radon progeny concentrations were measured in three Egyptian underground phosphate mines to estimate the occupational exposure to the workers in those sites. Active techniques are employed to fulfill the objective of measuring individual radon progeny concentrations (C RaA , C RaB and C RaC ). The mean reported values of radon progeny concentrations exceed the action levels recommended by ICRP 65 (1993). Based on the physical properties of attached radon progeny aerosol and physiological parameters for heavy work activity which recommended by ICRP 66 (1994). the deposition fraction for each airway generation was calculated. From the measured individual radon progeny concentrations in these mines and the calculated values of deposition fractions, the surface activity distribution per generation were calculated in human respiratory system (BB and regions). The maximum values of these activities were found in the upper bronchial airway generations. According to the obtained results, some of the corrective actions were recommended in this study

Oral peptide specific egg antibody to intestinal sodium-dependent phosphate co-transporter-2b is effective at altering phosphate transport in vitro and in vivo.

Science.gov (United States)

Bobeck, Elizabeth A; Hellestad, Erica M; Sand, Jordan M; Piccione, Michelle L; Bishop, Jeff W; Helvig, Christian; Petkovich, Martin; Cook, Mark E

2015-06-01

Hyperimmunized hens are an effective means of generating large quantities of antigen specific egg antibodies that have use as oral supplements. In this study, we attempted to create a peptide specific antibody that produced outcomes similar to those of the human pharmaceutical, sevelamer HCl, used in the treatment of hyperphosphatemia (a sequela of chronic renal disease). Egg antibodies were generated against 8 different human intestinal sodium-dependent phosphate cotransporter 2b (NaPi2b) peptides, and hNaPi2b peptide egg antibodies were screened for their ability to inhibit phosphate transport in human intestinal Caco-2 cell line. Antibody produced against human peptide sequence TSPSLCWT (anti-h16) was specific for its peptide sequence, and significantly reduced phosphate transport in human Caco-2 cells to 25.3±11.5% of control nonspecific antibody, when compared to nicotinamide, a known inhibitor of phosphate transport (P≤0.05). Antibody was then produced against the mouse-specific peptide h16 counterpart (mouse sequence TSPSYCWT, anti-m16) for further analysis in a murine model. When anti-m16 was fed to mice (1% of diet as dried egg yolk powder), egg yolk immunoglobulin (IgY) was detected using immunohistochemical staining in mouse ileum, and egg anti-m16 IgY colocalized with a commercial goat anti-NaPi2b antibody. The effectiveness of anti-m16 egg antibody in reducing serum phosphate, when compared to sevelamer HCl, was determined in a mouse feeding study. Serum phosphate was reduced 18% (Pegg yolk powder) and 30% (Pegg immunoglobulin. The methods described and the findings reported show that oral egg antibodies are useful and easy to prepare reagents for the study and possible treatment of select diseases. © 2015 Poultry Science Association Inc.

Evaluation of intestinal phosphate binding to improve the safety profile of oral sodium phosphate bowel cleansing.

Directory of Open Access Journals (Sweden)

Stef Robijn

Full Text Available Prior to colonoscopy, bowel cleansing is performed for which frequently oral sodium phosphate (OSP is used. OSP results in significant hyperphosphatemia and cases of acute kidney injury (AKI referred to as acute phosphate nephropathy (APN; characterized by nephrocalcinosis are reported after OSP use, which led to a US-FDA warning. To improve the safety profile of OSP, it was evaluated whether the side-effects of OSP could be prevented with intestinal phosphate binders. Hereto a Wistar rat model of APN was developed. OSP administration (2 times 1.2 g phosphate by gavage with a 12h time interval induced bowel cleansing (severe diarrhea and significant hyperphosphatemia (21.79 ± 5.07 mg/dl 6h after the second OSP dose versus 8.44 ± 0.97 mg/dl at baseline. Concomitantly, serum PTH levels increased fivefold and FGF-23 levels showed a threefold increase, while serum calcium levels significantly decreased from 11.29 ± 0.53 mg/dl at baseline to 8.68 ± 0.79 mg/dl after OSP. OSP administration induced weaker NaPi-2a staining along the apical proximal tubular membrane. APN was induced: serum creatinine increased (1.5 times baseline and nephrocalcinosis developed (increased renal calcium and phosphate content and calcium phosphate deposits on Von Kossa stained kidney sections. Intestinal phosphate binding (lanthanum carbonate or aluminum hydroxide was not able to attenuate the OSP induced side-effects. In conclusion, a clinically relevant rat model of APN was developed. Animals showed increased serum phosphate levels similar to those reported in humans and developed APN. No evidence was found for an improved safety profile of OSP by using intestinal phosphate binders.

Serum deprivation induces glucose response and intercellular coupling in human pancreatic adenocarcinoma PANC-1 cells.

Science.gov (United States)

Hiram-Bab, Sahar; Shapira, Yuval; Gershengorn, Marvin C; Oron, Yoram

2012-03-01

This study aimed to investigate whether the previously described differentiating islet-like aggregates of human pancreatic adenocarcinoma cells (PANC-1) develop glucose response and exhibit intercellular communication. Fura 2-loaded PANC-1 cells in serum-free medium were assayed for changes in cytosolic free calcium ([Ca]i) induced by depolarization, tolbutamide inhibition of K(ATP) channels, or glucose. Dye transfer, assayed by confocal microscopy or by FACS, was used to detect intercellular communication. Changes in messenger RNA (mRNA) expression of genes of interest were assessed by quantitative real-time polymerase chain reaction. Proliferation was assayed by the MTT method. Serum-deprived PANC-1 cell aggregates developed [Ca]i response to KCl, tolbutamide, or glucose. These responses were accompanied by 5-fold increase in glucokinase mRNA level and, to a lesser extent, of mRNAs for K(ATP) and L-type calcium channels, as well as increase in mRNA levels of glucagon and somatostatin. Trypsin, a proteinase-activated receptor 2 agonist previously shown to enhance aggregation, modestly improved [Ca]i response to glucose. Glucose-induced coordinated [Ca]i oscillations and dye transfer demonstrated the emergence of intercellular communication. These findings suggest that PANC-1 cells, a pancreatic adenocarcinoma cell line, can be induced to express a differentiated phenotype in which cells exhibit response to glucose and form a functional syncytium similar to those observed in pancreatic islets.

Use systems pharmacology modeling to elucidate the operating characteristics of SGLT1 and SGLT2 in renal glucose reabsorption in humans

Directory of Open Access Journals (Sweden)

Yasong eLu

2014-12-01

Full Text Available In the kidney, glucose in glomerular filtrate is reabsorbed primarily by sodium-glucose cotransporters 1 (SGLT1 and 2 (SGLT2 along the proximal tubules. SGLT2 has been characterized as a high capacity, low affinity pathway responsible for reabsorption of the majority of filtered glucose in the early part of proximal tubules, and SGLT1 reabsorbs the residual glucose in the distal part. Inhibition of SGLT2 is a viable mechanism for removing glucose from the body and improving glycemic control in patients with diabetes. Despite demonstrating high levels (in excess of 80% of inhibition of glucose transport by SGLT2 in vitro, potent SGLT2 inhibitors, e.g., dapagliflozin and canagliflozin, inhibit renal glucose reabsorption by only 30-50% in clinical studies. Hypotheses for this apparent paradox are mostly focused on the compensatory effect of SGLT1. The paradox has been explained and the role of SGLT1 demonstrated in the mouse, but direct data in humans are lacking. To further explore the roles of SGLT1/2 in renal glucose reabsorption in humans, we developed a systems pharmacology model with emphasis on SGLT1/2 mediated glucose reabsorption and the effects of SGLT2 inhibition. The model was calibrated using robust clinical data in the absence or presence of dapagliflozin (DeFronzo et al. data (2013, and evaluated against clinical data from the literature (Mogensen, 1971;Wolf et al., 2009;Polidori et al., 2013. The model adequately described all four data sets. Simulations using the model clarified the operating characteristics of SGLT1/2 in humans in the healthy and diabetic state with or without SGLT2 inhibition. The modeling and simulations support our proposition that the apparent moderate, 30-50% inhibition of renal glucose reabsorption observed with potent SGLT2 inhibitors is a combined result of two physiological determinants: SGLT1 compensation and residual SGLT2 activity. This model will enable in silico inferences and predictions related to

Reducing of internal resistance lithium ion battery using glucose addition

Science.gov (United States)

Salim, Andri Pratama; Hafidlullah, Noor; Purwanto, Agus

2016-02-01

There are two indicators of battery performance, i.e : capacity and the internal resistance of battery. In this research, the affect of glucose addition to decrease the internal resistance of lithium battery was investigated. The ratio of glucose addition were varied at weight ratio 1%, 3%, and 5% and one mixtures without glucose addition. Lithium ferri phosphate (LiFePO4), polyvinylidene fluoride (PVDF), acetylene black (AB) and glucose were materials that used in this study. Both of mixtures were mixed in the vacuum mixer until became homogeneous. The slurry was coated on an aluminium foil sheet and the coated thickness was 200 µm. The performance of battery lithium was examined by Eight Channel Battery Analyzer and the Internal resistance was examined by Internal Resistance of Battery Meter. The result from all analyzer were showed that the internal resistance reduced as well as the battery capacity. The best internal resistance value is owned by mixtures with 3wt% ratio glucose addition. It has an internal resistance value about 64 miliohm.

Reducing of internal resistance lithium ion battery using glucose addition

International Nuclear Information System (INIS)

Salim, Andri Pratama; Hafidlullah, Noor; Purwanto, Agus

2016-01-01

There are two indicators of battery performance, i.e : capacity and the internal resistance of battery. In this research, the affect of glucose addition to decrease the internal resistance of lithium battery was investigated. The ratio of glucose addition were varied at weight ratio 1%, 3%, and 5% and one mixtures without glucose addition. Lithium ferri phosphate (LiFePO 4 ), polyvinylidene fluoride (PVDF), acetylene black (AB) and glucose were materials that used in this study. Both of mixtures were mixed in the vacuum mixer until became homogeneous. The slurry was coated on an aluminium foil sheet and the coated thickness was 200 µm. The performance of battery lithium was examined by Eight Channel Battery Analyzer and the Internal resistance was examined by Internal Resistance of Battery Meter. The result from all analyzer were showed that the internal resistance reduced as well as the battery capacity. The best internal resistance value is owned by mixtures with 3wt% ratio glucose addition. It has an internal resistance value about 64 miliohm

Reducing of internal resistance lithium ion battery using glucose addition

Energy Technology Data Exchange (ETDEWEB)

Salim, Andri Pratama; Hafidlullah, Noor; Purwanto, Agus, E-mail: aguspurw@gmail.com [Research Group of Battery & Advanced Material, Department of Chemical Engineering, Sebelas Maret University, Jl. Ir. Sutami 36 A Kentingan, Surakarta Indonesia 57126 (Indonesia)

2016-02-08

There are two indicators of battery performance, i.e : capacity and the internal resistance of battery. In this research, the affect of glucose addition to decrease the internal resistance of lithium battery was investigated. The ratio of glucose addition were varied at weight ratio 1%, 3%, and 5% and one mixtures without glucose addition. Lithium ferri phosphate (LiFePO{sub 4}), polyvinylidene fluoride (PVDF), acetylene black (AB) and glucose were materials that used in this study. Both of mixtures were mixed in the vacuum mixer until became homogeneous. The slurry was coated on an aluminium foil sheet and the coated thickness was 200 µm. The performance of battery lithium was examined by Eight Channel Battery Analyzer and the Internal resistance was examined by Internal Resistance of Battery Meter. The result from all analyzer were showed that the internal resistance reduced as well as the battery capacity. The best internal resistance value is owned by mixtures with 3wt% ratio glucose addition. It has an internal resistance value about 64 miliohm.

Discovery of ebselen as an inhibitor of Cryptosporidium parvum glucose-6-phosphate isomerase (CpGPI) by high-throughput screening of existing drugs.

Science.gov (United States)

Eltahan, Rana; Guo, Fengguang; Zhang, Haili; Xiang, Lixin; Zhu, Guan

2018-04-01

Cryptosporidium parvum is a water-borne and food-borne apicomplexan pathogen. It is one of the top four diarrheal-causing pathogens in children under the age of five in developing countries, and an opportunistic pathogen in immunocompromised individuals. Unlike other apicomplexans, C. parvum lacks Kreb's cycle and cytochrome-based respiration, thus relying mainly on glycolysis to produce ATP. In this study, we characterized the primary biochemical features of the C. parvum glucose-6-phosphate isomerase (CpGPI) and determined its Michaelis constant towards fructose-6-phosphate (K m  = 0.309 mM, V max  = 31.72 nmol/μg/min). We also discovered that ebselen, an organoselenium drug, was a selective inhibitor of CpGPI by high-throughput screening of 1200 known drugs. Ebselen acted on CpGPI as an allosteric noncompetitive inhibitor (IC 50  = 8.33 μM; K i  = 36.33 μM), while complete inhibition of CpGPI activity was not achieved. Ebselen could also inhibit the growth of C. parvum in vitro (EC 50  = 165 μM) at concentrations nontoxic to host cells, albeit with a relatively small in vitro safety window of 4.2 (cytotoxicity TC 50 on HCT-8 cells = 700 μM). Additionally, ebselen might also target other enzymes in the parasite, leading to the parasite growth reduction. Therefore, although ebselen is useful in studying the inhibition of CpGPI enzyme activity, further proof is needed to chemically and/or genetically validate CpGPI as a drug target. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

Distinct generation, pharmacology, and distribution of sphingosine 1-phosphate and dihydro-sphingosine 1-phosphate in human neural progenitor cells

Science.gov (United States)

In-vivo and in-vitro studies suggest a crucial role for Sphingosine 1-phosphate (S1P) and its receptors in the development of the nervous system. Dihydrosphingosine 1-phosphate (dhS1P), a reduced form of S1P, is an active ligand at S1P receptors, but the pharmacology and physiology of dhS1P has not...

Fibronectin-calcium phosphate composite layer on hydroxyapatite to enhance adhesion, cell spread and osteogenic differentiation of human mesenchymal stem cells in vitro

International Nuclear Information System (INIS)

Sogo, Yu; Ito, Atsuo; Matsuno, Tomonori; Oyane, Ayako; Tamazawa, Gaku; Satoh, Tazuko; Yamazaki, Atsushi; Uchimura, Eiji; Ohno, Tadao

2007-01-01

Fibronectin (Fn) and type I collagen (Col) were immobilized on a surface of a hydroxyapatite (HAP) ceramic by coprecipitation with calcium phosphate in a supersaturated calcium phosphate solution prepared by mixing clinically approved infusion fluids. These proteins and the calcium phosphate precipitate formed a composite surface layer. As a result, the proteins were immobilized firmly as not to be released completely for 3 d in a physiological salt solution. When human mesenchymal stem cells (hMSCs) were cultured on a HAP ceramic in a differentiation medium supplemented with dexamethasone, β-glycerophosphate and ascorbic acid, hMSCs spread well within 1 h. The alkaline phosphatase (ALP) activity of hMSCs cultured on the Fn-calcium phosphate composite layer significantly increased compared with that of hMSCs cultured on the untreated HAP ceramic. On the other hand, Col did not increase the ALP activity of hMSCs and no synergy between Fn and Col was observed. Therefore, the Fn-calcium phosphate composite layer formed on the HAP is useful for the enhancement of the spreading and osteogenic differentiation of hMSCs in vitro

Overexpression of Genes Encoding Glycolytic Enzymes in Corynebacterium glutamicum Enhances Glucose Metabolism and Alanine Production under Oxygen Deprivation Conditions

Science.gov (United States)

Yamamoto, Shogo; Gunji, Wataru; Suzuki, Hiroaki; Toda, Hiroshi; Suda, Masako; Jojima, Toru; Inui, Masayuki

2012-01-01

We previously reported that Corynebacterium glutamicum strain ΔldhAΔppc+alaD+gapA, overexpressing glyceraldehyde-3-phosphate dehydrogenase-encoding gapA, shows significantly improved glucose consumption and alanine formation under oxygen deprivation conditions (T. Jojima, M. Fujii, E. Mori, M. Inui, and H. Yukawa, Appl. Microbiol. Biotechnol. 87:159–165, 2010). In this study, we employ stepwise overexpression and chromosomal integration of a total of four genes encoding glycolytic enzymes (herein referred to as glycolytic genes) to demonstrate further successive improvements in C. glutamicum glucose metabolism under oxygen deprivation. In addition to gapA, overexpressing pyruvate kinase-encoding pyk and phosphofructokinase-encoding pfk enabled strain GLY2/pCRD500 to realize respective 13% and 20% improved rates of glucose consumption and alanine formation compared to GLY1/pCRD500. Subsequent overexpression of glucose-6-phosphate isomerase-encoding gpi in strain GLY3/pCRD500 further improved its glucose metabolism. Notably, both alanine productivity and yield increased after each overexpression step. After 48 h of incubation, GLY3/pCRD500 produced 2,430 mM alanine at a yield of 91.8%. This was 6.4-fold higher productivity than that of the wild-type strain. Intracellular metabolite analysis showed that gapA overexpression led to a decreased concentration of metabolites upstream of glyceraldehyde-3-phosphate dehydrogenase, suggesting that the overexpression resolved a bottleneck in glycolysis. Changing ratios of the extracellular metabolites by overexpression of glycolytic genes resulted in reduction of the intracellular NADH/NAD+ ratio, which also plays an important role on the improvement of glucose consumption. Enhanced alanine dehydrogenase activity using a high-copy-number plasmid further accelerated the overall alanine productivity. Increase in glycolytic enzyme activities is a promising approach to make drastic progress in growth-arrested bioprocesses. PMID

Effect of Casein Phosphopeptide-Amorphous Calcium Phosphate and Three Calcium Phosphate on Enamel Microhardness.

Science.gov (United States)

Haghgou, En Hr; Haghgoo, Roza; Roholahi, Mohamad R; Ghorbani, Zahra

2017-07-01

This study aims to investigate the effect of casein phos-phopeptide-amorphous calcium phosphate and three calcium phosphate (CPP-ACP and TCP) on increasing the microhardness of human enamel after induction of erosion. A total of 26 healthy human-impacted third molar teeth were chosen, and their hardness measured using a microhardness testing machine. The samples were immersed in Coca Cola (pH = 4.7) for 8 minutes. Then, micro-hardness was measured again, and these samples were randomly divided into four groups (two control groups and two experimental groups). (1) Negative control group: Artificial saliva was used for 10 minutes, (2) positive control group: Fluoride gel was used for 10 minutes, (3) β-TCP group: TCP was used for 10 minutes, (4) CCP-ACP group: CCP-ACP was used for 10 minutes. The final microhardness of those samples was measured, and the changes in microhardness of teeth within group and between groups were analyzed using the paired and analysis of variance tests respectively. Results were considered statistically significant at a level of p < 0.05. No significant difference was observed in microhard-ness between CPP-ACP group and TCP group (p = 0.368) during the time microhardness significantly dropped after soaking in soda. Casein phosphopeptide-amorphous calcium phosphate and TCP increased the microhardness of teeth. The increase in hardness in the TCP group was higher than in the CPP-ACP group, but this difference was not significant (p = 0.36). Casein phosphopeptide-amorphous calcium phosphate and TCP can affect the remineralization of erosive lesions.

Phosphate Recovery from Human Waste via the Formation of Hydroxyapatite during Electrochemical Wastewater Treatment.

Science.gov (United States)

Cid, Clément A; Jasper, Justin T; Hoffmann, Michael R

2018-03-05

Electrolysis of toilet wastewater with TiO 2 -coated semiconductor anodes and stainless steel cathodes is a potentially viable onsite sanitation solution in parts of the world without infrastructure for centralized wastewater treatment. In addition to treating toilet wastewater, pilot-scale and bench-scale experiments demonstrated that electrolysis can remove phosphate by cathodic precipitation as hydroxyapatite at no additional energy cost. Phosphate removal could be predicted based on initial phosphate and calcium concentrations, and up to 80% total phosphate removal was achieved. While calcium was critical for phosphate removal, magnesium and bicarbonate had only minor impacts on phosphate removal rates at concentrations typical of toilet wastewater. Optimal conditions for phosphate removal were 3 to 4 h treatment at about 5 mA cm -2 (∼3.4 V), with greater than 20 m 2 m -3 electrode surface area to reactor volume ratios. Pilot-scale systems are currently operated under similar conditions, suggesting that phosphate removal can be viewed as an ancillary benefit of electrochemical wastewater treatment, adding utility to the process without requiring additional energy inputs. Further value may be provided by designing reactors to recover precipitated hydroxyapatite for use as a low solubility phosphorus-rich fertilizer.

RBS and XPS analyses of the composite calcium phosphate coatings for biomedical applications

International Nuclear Information System (INIS)

Ide-Ektessabi, Ari; Yamaguchi, Tetsuro; Tanaka, Yoshikazu

2005-01-01

The calcium phosphate coatings on metallic implants are widely used for biomedical applications. The calcium phosphate coatings require mechanical strength, strong adhesion to the metallic implants, chemical stability and low dissolution into the human body fluid for stable functioning in the corrosive environment of the human body. In this study, a novel approach for improving the calcium phosphate coatings is utilized by adding trace metallic element into the coatings. We focused on teeth enamel, which is the hardest calcium phosphate tissue in the human body. Zn concentration increases exponentially from the interior to the surface of the enamel. As the Zn concentration increases, so the local hardness increases. Our previous studies suggest that Zn has influence on the hardness and other properties of enamel, calcium phosphate tissue. Calcium phosphate coatings doped with Zn was fabricated and characterized. The atomic composition and chemical state were investigated by using Rutherford backscattering spectroscopy (RBS) and X-ray photoelectron spectrometer (XPS), respectively. Scratch test was also carried out for measuring the adhesion of the coatings

Human Subcutaneous Tissue Response to Glucose Sensors: Macrophages Accumulation Impact on Sensor Accuracy.

Science.gov (United States)

Rigla, Mercedes; Pons, Belén; Rebasa, Pere; Luna, Alexis; Pozo, Francisco Javier; Caixàs, Assumpta; Villaplana, Maria; Subías, David; Bella, Maria Rosa; Combalia, Neus

2018-04-01

Subcutaneous (s.c.) glucose sensors have become a key component in type 1 diabetes management. However, their usability is limited by the impact of foreign body response (FBR) on their duration, reliability, and accuracy. Our study gives the first description of human acute and subacute s.c. response to glucose sensors, showing the changes observed in the sensor surface, the inflammatory cells involved in the FBR and their relationship with sensor performance. Twelve obese patients (seven type 2 diabetes) underwent two abdominal biopsies comprising the surrounding area where they had worn two glucose sensors: the first one inserted 7 days before and the second one 24 h before biopsy procedure. Samples were processed and studied to describe tissue changes by two independent pathologists (blind regarding sensor duration). Macrophages quantification was studied by immunohistochemistry methods in the area surrounding the sensor (CD68, CD163). Sensor surface changes were studied by scanning electron microscopy. Seven-day continuous glucose monitoring records were considered inaccurate when mean absolute relative difference was higher than 10%. Pathologists were able to correctly classify all the biopsies regarding sensor duration. Acute response (24 h) was characterized by the presence of neutrophils while macrophages were the main cell involved in subacute inflammation. The number of macrophages around the insertion hole was higher for less accurate sensors compared with those performing more accurately (32.6 ± 14 vs. 10.6 ± 1 cells/0.01 mm 2 ; P sensor-tissue interface is related with decrease in accuracy of the glucose measure.

My Sweetheart Is Broken: Role of Glucose in Diabetic Cardiomyopathy

Directory of Open Access Journals (Sweden)

Manoja K. Brahma

2017-01-01

Full Text Available Despite overall reductions in heart disease prevalence, the risk of developing heart failure has remained 2-fold greater among people with diabetes. Growing evidence has supported that fluctuations in glucose level and uptake contribute to cardiovascular disease (CVD by modifying proteins, DNA, and gene expression. In the case of glucose, clinical studies have shown that increased dietary sugars for healthy individuals or poor glycemic control in diabetic patients further increased CVD risk. Furthermore, even after decades of maintaining tight glycemic control, susceptibility to disease progression can persist following a period of poor glycemic control through a process termed "glycemic memory." In response to chronically elevated glucose levels, a number of studies have identified molecular targets of the glucose-mediated protein posttranslational modification by the addition of an O-linked N-acetylglucosamine to impair contractility, calcium sensitivity, and mitochondrial protein function. Additionally, elevated glucose contributes to dysfunction in coupling glycolysis to glucose oxidation, pentose phosphate pathway, and polyol pathway. Therefore, in the "sweetened" environment associated with hyperglycemia, there are a number of pathways contributing to increased susceptibly to "breaking" the heart of diabetics. In this review we will discuss the unique contribution of glucose to heart disease and recent advances in defining mechanisms of action.

Characterization of human cytochrome P450s involved in the bioactivation of tri-Ortho-Cresyl phosphate (ToCP)

NARCIS (Netherlands)

Reinen, Jelle; Nematollahi, Leyla; Fidder, Alex; Vermeulen, Nico P E; Noort, Daan; Commandeur, Jan N M

2015-01-01

Tri-ortho-cresyl phosphate (ToCP) is a multipurpose organophosphorus compound that is neurotoxic and suspected to be involved in aerotoxic syndrome in humans. It has been reported that not ToCP itself but a metabolite of ToCP, namely, 2-(ortho-cresyl)-4H-1,2,3-benzodioxaphosphoran-2-one (CBDP), may

Salinity stress effects on [14C-1]- and [14C-6]-glucose metabolism of a salt-tolerant and salt-susceptible variety of wheat

International Nuclear Information System (INIS)

Krishnaraj, S.; Thorpe, T.A.

1996-01-01

The effect of salt (sodium sulfate) on carbohydrate metabolism was studied in a salt-tolerant (Kharchia-65) variety and a salt-susceptible (Fielder) variety of wheat (Triticum aestivum L.) by comparing their responses under control and stress conditions. Leaf segments of Kharchia-65 showed increased activity through both the pentose phosphate pathway (PPP) and the glycolytic pathway of glucose oxidation, with the former being comparatively more active in response to salt. In Fielder, there was an increase in PPP activity at the expense of glycolytic pathway activity. Label from glucose was found in the lipid, neutral sugar, amino acid, organic acid, and phosphate ester fractions in all treatments. On the basis of the label distribution patterns, it appears that Fielder leaves incubated with [ 14 C-6]-glucose were not able to utilize glucose efficiently under saline conditions. This finding was further supported by decreased label incorporation into all the fractions, especially the amino acid and organic acid fractions. Adenosine phosphate and reduced pyridine nucleotide concentrations were consistent with these observations. We conclude therefore that the salt-tolerant variety had an enhanced metabolic activity compared with the salt-susceptible variety, which contributed to its ability to overcome the adverse effects of salt. (author)

Achieving direct electrochemistry of glucose oxidase by one step electrochemical reduction of graphene oxide and its use in glucose sensing

International Nuclear Information System (INIS)

Shamsipur, Mojtaba; Amouzadeh Tabrizi, Mahmoud

2014-01-01

In this paper, the direct electrochemistry of glucose oxidase (GOD) was accomplished at a glassy carbon electrode modified with electrochemically reduced graphene oxide/sodium dodecyl sulfate (GCE/ERGO/SDS). A pair of reversible peaks is exhibited on GCE/ERGO/SDS/GOD by cyclic voltammetry. The peak-to-peak potential separation of immobilized GOD is 28 mV in 0.1 M phosphate buffer solution (pH 7.0) with a scan rate of 50 mV/s. The average surface coverage is 2.62 × 10 −10 mol cm −2 . The resulting biosensor exhibited a good response to glucose with linear range from 1 to 8 mM (R 2 = 0.9878), good reproducibility and detection limit of 40.8 μM. The results from the biosensor were similar (± 5%) to those obtained from the clinical analyzer. - Highlights: • A direct electron transfer reaction of glucose oxidase was observed on GCE/ERGO/SDS. • This composite film was successfully applied in preparation of glucose biosensor. • The detection limit of the biosensor was estimated to be 40.8 μM. • The results from the sensor were similar to those obtained from the clinical analyzer

High glucose suppresses human islet insulin biosynthesis by inducing miR-133a leading to decreased polypyrimidine tract binding protein-expression.

Directory of Open Access Journals (Sweden)

Rikard G Fred

Full Text Available BACKGROUND: Prolonged periods of high glucose exposure results in human islet dysfunction in vitro. The underlying mechanisms behind this effect of high glucose are, however, unknown. The polypyrimidine tract binding protein (PTB is required for stabilization of insulin mRNA and the PTB mRNA 3'-UTR contains binding sites for the microRNA molecules miR-133a, miR-124a and miR-146. The aim of this study was therefore to investigate whether high glucose increased the levels of these three miRNAs in association with lower PTB levels and lower insulin biosynthesis rates. METHODOLOGY/PRINCIPAL FINDINGS: Human islets were cultured for 24 hours in the presence of low (5.6 mM or high glucose (20 mM. Islets were also exposed to sodium palmitate or the proinflammatory cytokines IL-1beta and IFN-gamma, since saturated free fatty acids and cytokines also cause islet dysfunction. RNA was then isolated for real-time RT-PCR analysis of miR-133a, miR-124a, miR-146, insulin mRNA and PTB mRNA contents. Insulin biosynthesis rates were determined by radioactive labeling and immunoprecipitation. Synthetic miR-133a precursor and inhibitor were delivered to dispersed islet cells by lipofection, and PTB was analyzed by immunoblotting following culture at low or high glucose. Culture in high glucose resulted in increased islet contents of miR-133a and reduced contents of miR-146. Cytokines increased the contents of miR-146. The insulin and PTB mRNA contents were unaffected by high glucose. However, both PTB protein levels and insulin biosynthesis rates were decreased in response to high glucose. The miR-133a inhibitor prevented the high glucose-induced decrease in PTB and insulin biosynthesis, and the miR-133a precursor decreased PTB levels and insulin biosynthesis similarly to high glucose. CONCLUSION: Prolonged high-glucose exposure down-regulates PTB levels and insulin biosynthesis rates in human islets by increasing miR-133a levels. We propose that this mechanism

Effects of glucose metabolism pathways on sperm motility and oxidative status during long-term liquid storage of goat semen.

Science.gov (United States)

Qiu, Jian-Hua; Li, You-Wei; Xie, Hong-Li; Li, Qing; Dong, Hai-Bo; Sun, Ming-Ju; Gao, Wei-Qiang; Tan, Jing-He

2016-08-01

Although great efforts were made to prolong the fertility of liquid-stored semen, limited improvements have been achieved in different species. Although it is expected that energy supply and the redox potential will play an essential role in sperm function, there are few reports on the impact of specific energy substrates on spermatozoa during liquid semen storage. Furthermore, although it is accepted that glucose metabolism through glycolysis provides energy, roles of pentose phosphate pathway (PPP) and tricarboxylic acid cycle remain to be unequivocally found in spermatozoa. We have studied the pathways by which spermatozoa metabolize glucose during long-term liquid storage of goat semen. The results indicated that among the substrates tested, glucose and pyruvate were better than lactate in maintaining goat sperm motility. Although both glycolysis and PPP were essential, PPP was more important than glycolysis to maintain sperm motility. Pentose phosphate pathway reduced oxidative stress and provided glycolysis with more intermediate products such as fructose-6-phosphate. Pyruvate entered goat spermatozoa through monocarboxylate transporters and was oxidized by the tricarboxylic acid cycle and electron transfer to sustain sperm motility. Long-term liquid semen storage can be used as a good model to study sperm glucose metabolism. The data are important for an optimal control of sperm survival during semen handling and preservation not only in the goat but also in other species. Copyright © 2016 Elsevier Inc. All rights reserved.

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.)

Final Report for research on The Glucose 6-Phosphate Shunt Around the Calvin-Benson Cycle

Energy Technology Data Exchange (ETDEWEB)

Sharkey, Thomas D. [Michigan State Univ., East Lansing, MI (United States)

2017-10-30

In this research, photosynthetic carbon metabolism was studied to identify mechanisms by which plants store energy from sunlight as carbon compounds, especially sugars. Conditions were identified in which carbon appeared to flow backwards from outside the photosynthetic compartment (chloroplast) back into it. A specific gene product was manipulated to make the flow bigger or smaller. Preventing the flow (by eliminating the gene) had little effect on plant growth but increasing the flow, by overexpressing the gene, caused the plants to become extremely sensitive to changes in light. Plants with the gene overexpressed had high rates of cyclic electron flow, the photosynthetic electron transport pathway that occurs when plants need more of the energy molecule ATP. These and other observations led us to conclude that a metabolic pathway that is normally turned off because it is counter-productive during photosynthesis, in fact occurs at about 10% of the rate of normal photosynthesis. This creates an inefficiency but may stabilize photosynthesis allowing it to cope with the very large and rapid changes that leaves experience such as the hundred-fold changes in light intensity that can occur in seconds on a partly cloudy day. We also concluded that the back flow of carbon into chloroplasts could be important at high rates of photosynthesis allowing increased rates of starch synthesis. Starch synthesis allows plants to store sugars during the day for use at night. At high rates of photosynthesis starch synthesis becomes very important to protect against end-product inhibition of photosynthesis. This research identified two metabolic pathways that extend the primary carbon fixation pathway called the Calvin-Benson cycle. These pathway extensions are now called the cytosolic bypass and the glucose 6-phosphate shunt. This improvement in our understanding of carbon metabolism of photosynthesis will guide efforts to increase photosynthesis to increase production of food, fuel

Cloning, expression and characterization of a mammalian Nudix hydrolase-like enzyme that cleaves the pyrophosphate bond of UDP-glucose.

OpenAIRE

Yagi, Toshihiro; Baroja-Fernández, Edurne; Yamamoto, Ryuji; Muñoz, Francisco José; Akazawa, Takashi; Hong, Kyoung Su; Pozueta-Romero, Javier

2003-01-01

A distinct UDP-glucose (UDPG) pyrophosphatase (UGPPase, EC 3.6.1.45) has been characterized using pig kidney ( Sus scrofa ). This enzyme hydrolyses UDPG, the precursor molecule of numerous glycosylation reactions in animals, to produce glucose 1-phosphate (G1P) and UMP. Sequence analyses of the purified enzyme revealed that, similar to the case of a nucleotide-sugar hydrolase controlling the intracellular levels of ADP-glucose linked to glycogen biosynthesis in Escherichia coli [Moreno-Bruna,...

Effect of different calcium phosphate scaffold ratios on odontogenic differentiation of human dental pulp cells

International Nuclear Information System (INIS)

AbdulQader, Sarah Talib; Kannan, Thirumulu Ponnuraj; Rahman, Ismail Ab; Ismail, Hanafi; Mahmood, Zuliani

2015-01-01

Calcium phosphate (CaP) scaffolds have been widely and successfully used with osteoblast cells for bone tissue regeneration. However, it is necessary to investigate the effects of these scaffolds on odontoblast cells' proliferation and differentiation for dentin tissue regeneration. In this study, three different hydroxyapatite (HA) to beta tricalcium phosphate (β-TCP) ratios of biphasic calcium phosphate (BCP) scaffolds, BCP20, BCP50, and BCP80, with a mean pore size of 300 μm and 65% porosity were prepared from phosphoric acid (H 2 PO 4 ) and calcium carbonate (CaCO 3 ) sintered at 1000 °C for 2 h. The extracts of these scaffolds were assessed with regard to cell viability and differentiation of odontoblasts. The high alkalinity, more calcium, and phosphate ions released that were exhibited by BCP20 decreased the viability of human dental pulp cells (HDPCs) as compared to BCP50 and BCP80. However, the cells cultured with BCP20 extract expressed high alkaline phosphatase activity and high expression level of bone sialoprotein (BSP), dental matrix protein-1 (DMP-1), and dentin sialophosphoprotein (DSPP) genes as compared to that cultured with BCP50 and BCP80 extracts. The results highlighted the effect of different scaffold ratios on the cell microenvironment and demonstrated that BCP20 scaffold can support HDPC differentiation for dentin tissue regeneration. - Highlights: • BCPs of different HA/β-TCP ratios influence cell microenvironment. • BCP20 decreases cell viability of HDPCs as compared to BCP50 and BCP80. • HDPCs cultured with BCP20 express highest ALP activity. • HDPCs cultured with BCP20 up-regulate BSP, DMP-1 and DSPP gene expressions. • BCP20 can support HDPC differentiation for dentin tissue regeneration

Effect of different calcium phosphate scaffold ratios on odontogenic differentiation of human dental pulp cells

Energy Technology Data Exchange (ETDEWEB)

AbdulQader, Sarah Talib [School of Dental Sciences, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan (Malaysia); Department of Pedodontic and Preventive Dentistry, College of Dentistry, University of Baghdad, Baghdad (Iraq); Kannan, Thirumulu Ponnuraj, E-mail: kannan@usm.my [School of Dental Sciences, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan (Malaysia); Human Genome Centre, School of Medical Sciences, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan (Malaysia); Rahman, Ismail Ab [School of Dental Sciences, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan (Malaysia); Ismail, Hanafi [School of Materials and Minerals Resource Engineering, Universiti Sains Malaysia, 14300 Penang (Malaysia); Mahmood, Zuliani [School of Dental Sciences, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan (Malaysia)

2015-04-01

Calcium phosphate (CaP) scaffolds have been widely and successfully used with osteoblast cells for bone tissue regeneration. However, it is necessary to investigate the effects of these scaffolds on odontoblast cells' proliferation and differentiation for dentin tissue regeneration. In this study, three different hydroxyapatite (HA) to beta tricalcium phosphate (β-TCP) ratios of biphasic calcium phosphate (BCP) scaffolds, BCP20, BCP50, and BCP80, with a mean pore size of 300 μm and 65% porosity were prepared from phosphoric acid (H{sub 2}PO{sub 4}) and calcium carbonate (CaCO{sub 3}) sintered at 1000 °C for 2 h. The extracts of these scaffolds were assessed with regard to cell viability and differentiation of odontoblasts. The high alkalinity, more calcium, and phosphate ions released that were exhibited by BCP20 decreased the viability of human dental pulp cells (HDPCs) as compared to BCP50 and BCP80. However, the cells cultured with BCP20 extract expressed high alkaline phosphatase activity and high expression level of bone sialoprotein (BSP), dental matrix protein-1 (DMP-1), and dentin sialophosphoprotein (DSPP) genes as compared to that cultured with BCP50 and BCP80 extracts. The results highlighted the effect of different scaffold ratios on the cell microenvironment and demonstrated that BCP20 scaffold can support HDPC differentiation for dentin tissue regeneration. - Highlights: • BCPs of different HA/β-TCP ratios influence cell microenvironment. • BCP20 decreases cell viability of HDPCs as compared to BCP50 and BCP80. • HDPCs cultured with BCP20 express highest ALP activity. • HDPCs cultured with BCP20 up-regulate BSP, DMP-1 and DSPP gene expressions. • BCP20 can support HDPC differentiation for dentin tissue regeneration.

Glucagon-like peptide-1 inhibits blood-brain glucose transfer in humans

DEFF Research Database (Denmark)

Lerche, Susanne; Brock, Birgitte; Rungby, Jørgen

2008-01-01

OBJECTIVE: Glucagon-like peptide-1 (GLP-1) has many effects on glucose homeostasis, and GLP-1 receptors are broadly represented in many tissues including the brain. Recent research in rodents suggests a protective effect of GLP-1 on brain tissue. The mechanism is unknown. We therefore tested......-independent effect of GLP-1 on unidirectional glucose transport into the brain during a pituitary-pancreatic normoglycemic (plasma glucose approximately 4.5 mmol/l) clamp with 18-fluoro-deoxy-glucose as tracer. RESULTS: On average, GLP-1 reduced cerebral glucose transport by 27% in total cerebral gray matter (P = 0...... that a hormone involved in postprandial glucose regulation also limits glucose delivery to brain tissue and hence provides a possible regulatory mechanism for the link between plasma glucose and brain glucose. Because GLP-1 reduces glucose uptake across the intact blood-brain barrier at normal glycemia, GLP-1...

Human bone marrow stem cell-encapsulating calcium phosphate scaffolds for bone repair

Science.gov (United States)

Weir, Michael D.; Xu, Hockin H.K.

2010-01-01

Due to its injectability and excellent osteoconductivity, calcium phosphate cement (CPC) is highly promising for orthopedic applications. However, a literature search revealed no report on human bone marrow mesenchymal stem cell (hBMSC) encapsulation in CPC for bone tissue engineering. The aim of this study was to encapsulate hBMSCs in alginate hydrogel beads and then incorporate them into CPC, CPC–chitosan and CPC–chitosan–fiber scaffolds. Chitosan and degradable fibers were used to mechanically reinforce the scaffolds. After 21 days, that the percentage of live cells and the cell density of hBMSCs inside CPC-based constructs matched those in alginate without CPC, indicating that the CPC setting reaction did not harm the hBMSCs. Alkaline phosphate activity increased by 8-fold after 14 days. Mineral staining, scanning electron microscopy and X-ray diffraction confirmed that apatitic mineral was deposited by the cells. The amount of hBMSC-synthesized mineral in CPC–chitosan–fiber matched that in CPC without chitosan and fibers. Hence, adding chitosan and fibers, which reinforced the CPC, did not compromise hBMSC osteodifferentiation and mineral synthesis. In conclusion, hBMSCs were encapsulated in CPC and CPC–chitosan–fiber scaffolds for the first time. The encapsulated cells remained viable, osteodifferentiated and synthesized bone minerals. These self-setting, hBMSC-encapsulating CPC-based constructs may be promising for bone tissue engineering applications. PMID:20451676

Direct electrochemistry of glucose oxidase immobilized on nanostructured gold thin films and its application to bioelectrochemical glucose sensor

International Nuclear Information System (INIS)

Qiu Cuicui; Wang Xia; Liu Xueying; Hou Shifeng; Ma Houyi

2012-01-01

Highlights: ► Au thin films are formed by electrodeposition and galvanic replacement technology. ► Glucose oxidase is stably immobilized via a simple physical adsorption method. ► The direct electrochemical behavior is obtained on the immobilized glucose oxidase. ► An amperometric sensor of glucose with an excellent sensing capability is achieved. - Abstract: Glucose oxidase (GOx) was stably immobilized via a simple physical adsorption method onto the nanostructured Au thin films fabricated by using electrodeposition and galvanic replacement technology, which provides a facile method to prepare morphology-controllable Au films and also facilitates the preparation and application of enzyme modified electrodes. An obvious advantage of the as-prepared enzyme electrode (denoted as GOx/Au/GCE) is that the nano-Au films provide a favorable microenvironment for GOx and facilitate the electron transfer between the active center of GOx and electrodes. Cyclic voltammetry (CV) results indicate that the immobilized GOx displayed a direct, reversible and surface-confined redox reaction in the phosphate buffer solution. Furthermore, the enzyme modified electrode was used as a glucose bioelectrochemical sensor, exhibiting a linear relationship in the concentration ranges of 2.5–32.5 μmol L −1 and 60–130 μmol L −1 with a detection limit of 0.32 μmol L −1 (S/N = 3) at an applied potential of −0.55 V. Due to the excellent stability, sensitivity and anti-interference ability, the Au thin films are hopeful in the construction of glucose biosensors.

Palladium nanoparticles deposited on graphene and its electrochemical performance for glucose sensing

Science.gov (United States)

Mijowska, Ewa; Onyszko, Magdalena; Urbas, Karolina; Aleksandrzak, Malgorzata; Shi, Xiaoze; Moszyński, Dariusz; Penkala, Krzysztof; Podolski, Jacek; El Fray, Mirosława

2015-11-01

This paper reports on the fabrication and characterization of glucose oxidase (GOx) immobilized onto a glassy carbon electrode (GCE) modified with reduced graphene oxide/palladium nanocomposite (RGO-Pd). Characterization tools showed well dispersed uniform Pd nanoparticles on a partly reduced graphene oxide surface. Cyclic voltammetry demonstrated successful immobilization of GOx on RGO-Pd modified GCE (GCE-RGO-Pd) using covalent bonding of GOx with RGO-Pd (RGO-Pd-GOx). Therefore, it was used as an electrochemical biosensor of glucose. RGO-Pd-GOx exhibited good electrocatalysis toward glucose in different glucose concentrations (from 2 to 10 mM, which includes the blood glucose levels of both normal and diabetic persons) with O2 saturated phosphate buffer solution (PBS) at pH 7.4. The system showed a linear increase in current at potential -0.085 V in the concentration range examined, with a correlation coefficient of 0.996. The sensitivity of the biosensor was 41.3 μA cm-2 mM-1, suggesting that RGO-Pd-GOx-modified GCE could be a potential candidate as a glucose sensor.

Co-immobilization of cyclohexanone monooxygenase and glucose-6-phosphate dehydrogenase onto polyethylenimine-porous agarose polymeric composite using γ irradiation to use in biotechnological processes

International Nuclear Information System (INIS)

Atia, K.S.

2005-01-01

The co-immobilization of cyclohexanone monooxygenase (CHMO) and glucose-6-phosphate dehydrogenase (G6PDH) was optimized by completely coating, via covalent immobilization, the surface aldehyde groups of porous agarose (glyoxyl-agarose) with amine groups of polyethylenimine (PEI). The highest immobilization efficiency (∼87%) (activity of enzyme per amount of immobilized enzyme) was obtained with a CHMO/G6PDH ratio 2:1. The effects of different ratios of the support to the amount of enzymes (CHMO:G6PDH=2:1), the optimum incubation pH and the incubation time on the enzymatic activity of the enzymes were determined and found to be 5:1, 8.5 and 30 min, respectively. Subjecting the co-immobilized enzymes to doses of γ-radiation (5-100 kGy) resulted in complete loss in the activity of the free enzymes at a dose of 40 kGy, while the co-immobilized ones showed relatively high resistance to γ-radiation up to a dose of 50 kGy

Hepatic glycogen in humans. I. Direct formation after oral and intravenous glucose or after a 24-h fast

International Nuclear Information System (INIS)

Radziuk, J.

1989-01-01

The formation of hepatic glycogen by the direct pathway is assessed in humans after a 12-h fast and oral loading (100 g) or intravenous infusion (90 g) and after a 24-h fast and the same oral glucose load. The methodology used is based on the double tracer method. [3- 3 H]glucose is infused at a constant rate for the determination of the metabolic clearance of glucose. [1- 14 C]glucose is administered with the glucose load. One hour after absorption or the intravenous glucose infusion is terminated, a glucagon infusion is initiated to mobilize the glycogen labeled with [1- 14 C]glucose and formed during the absorptive period. At this time a third tracer, [6- 3 H]glucose, is administered to measure glucose clearance. It was found that after the 12-h fast and oral glucose loading 7.2 +/- 1.1 g of hepatic glycogen appears to be formed directly from glucose compared with 8.4 +/- 1.0 g after the same load and a 24-h fast and 8.5 +/- 0.4 g after a 12-h fast and an equivalent intravenous glucose infusion. When the amount of label ([ 14 C]glucose) mobilized that was not corrected for metabolic recycling was calculated, the data suggested that the amount of glycogen formed by gluconeogenic pathways was probably at least equal to that formed by direct uptake. It was also approximately 60% greater after a 24-h fast. It can be concluded that the amount of hepatic glycogen formed directly from glucose during glucose loading is not significantly altered by the route of entry or the extension of the fasting period to 24 h. The data suggest, however, that gluconeogenetic formation of glycogen increases with fasting

Use of systems pharmacology modeling to elucidate the operating characteristics of SGLT1 and SGLT2 in renal glucose reabsorption in humans

Science.gov (United States)