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Sample records for hepatic glycogen formation

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

    SciTech Connect

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

    1989-06-01

    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-(/sup 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 /sup 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.

  2. Glucocorticoids and hepatic glycogen metabolism.

    PubMed

    Stalmans, W; Laloux, M

    1979-01-01

    The steady accumulation of glycogen in fetal rat liver during the last fifth of gestation is elicited by a transient rise in the level of circulating corticosterone. One effect of glucocorticoids is to induce glycogen synthase. The actual deposition of glycogen, however, depends on the appearance of a small amount of glycogen synthase in the active, dephosphorylated form. Induction of glycogen synthase phosphatase by glucocorticoids may explain the latter crucial process. Insulin enhances further the rate of glycogen deposition. The effect of insulin requires a previous exposure of the fetal liver to glucocorticoids. It is exerted on the enzyme interconversion system and appears not to involve new protein synthesis. Administration of glucocorticoids to adult fed or fasted animals causes within 3 h an intensive deposition of glycogen in the liver. This phenomenon is ultimately explained by both an activation of glycogen synthase and an inactivation of glycogen phosphorylase. The latter process may be due to an enhanced activity of phosphorylase phosphatase, or possibly of phosphorylase kinase phosphatase. The activation of glycogen synthase is explained by an enhanced activity of glycogen synthase phosphatase. The latter enzyme is normally profoundly inhibited by phosphorylase a; glucocorticoids cause the appearance in the liver of a protein factor that decreases and eventually cancels this inhibitory effect of phosphorylase a. It remains to be established whether or not some part of the glucocorticoid effect on adult liver is mediated by insulin.

  3. Ethanolic Extract of Butea monosperma Leaves Elevate Blood Insulin Level in Type 2 Diabetic Rats, Stimulate Insulin Secretion in Isolated Rat Islets, and Enhance Hepatic Glycogen Formation

    PubMed Central

    Samad, Mehdi Bin; Kabir, Ashraf Ul; Ahmed, Arif; Jahan, Mohammad Rajib; Hannan, J. M. A.

    2014-01-01

    We measured a vast range of parameters, in an attempt to further elucidate previously claimed antihyperglycemic activity of Butea monosperma. Our study clearly negates the possibility of antidiabetic activity by inhibited gastrointestinal enzyme action or by reduced glucose absorption. Reduction of fasting and postprandial glucose level was reconfirmed (P < 0.05). Improved serum lipid profile via reduced low density lipoprotein (LDL), cholesterol, triglycerides (TG), and increased high density lipoprotein (HDL) was also reestablished (P < 0.05). Significant insulin secretagogue activity of B. monosperma was found in serum insulin assay of B. monosperma treated type 2 diabetic rats (P < 0.01). This was further ascertained by our study on insulin secretion on isolated rat islets (P < 0.05). Improved sensitivity of glucose was shown by the significant increase in hepatic glycogen deposition (P < 0.05). Hence, we concluded that antihyperglycemic activity of B. monosperma was mediated by enhanced insulin secretion and enhanced glycogen formation in the liver. PMID:24860609

  4. Minimal hepatic glucose-6-phosphatase-α activity required to sustain survival and prevent hepatocellular adenoma formation in murine glycogen storage disease type Ia.

    PubMed

    Lee, Young Mok; Kim, Goo-Young; Pan, Chi-Jiunn; Mansfield, Brian C; Chou, Janice Y

    2015-06-01

    Glycogen storage disease type Ia (GSD-Ia), characterized by impaired glucose homeostasis and chronic risk of hepatocellular adenoma (HCA), is caused by a deficiency in glucose-6-phosphatase-α (G6Pase-α or G6PC) activity. In a previous 70-90 week-study, we showed that a recombinant adeno-associated virus (rAAV) vector-mediated gene transfer that restores more than 3% of wild-type hepatic G6Pase-α activity in G6pc (-/-) mice corrects hepatic G6Pase-α deficiency with no evidence of HCA. We now examine the minimal hepatic G6Pase-α activity required to confer therapeutic efficacy. We show that rAAV-treated G6pc (-/-) mice expressing 0.2% of wild-type hepatic G6Pase-α activity suffered from frequent hypoglycemic seizures at age 63-65 weeks but mice expressing 0.5-1.3% of wild-type hepatic G6Pase-α activity (AAV-LL mice) sustain 4-6 h of fast and grow normally to age 75-90 weeks. Despite marked increases in hepatic glycogen accumulation, the AAV-LL mice display no evidence of hepatic abnormalities, hepatic steatosis, or HCA. Interprandial glucose homeostasis is maintained by the G6Pase-α/glucose-6-phosphate transporter (G6PT) complex, and G6PT-mediated microsomal G6P uptake is the rate-limiting step in endogenous glucose production. We show that hepatic G6PT activity is increased in AAV-LL mice. These findings are encouraging for clinical studies of G6Pase-α gene-based therapy for GSD-Ia.

  5. Shared control of hepatic glycogen synthesis by glycogen synthase and glucokinase.

    PubMed Central

    Gomis, R R; Ferrer, J C; Guinovart, J J

    2000-01-01

    We have used recombinant adenoviruses (AdCMV-RLGS and AdCMV-GK) to overexpress the liver isoforms of glycogen synthase (GS) and glucokinase (GK) in primary cultured rat hepatocytes. Glucose activated overexpressed GS in a dose-dependent manner and caused the accumulation of larger amounts of glycogen in the AdCMV-RLGS-treated hepatocytes. The concentration of intermediate metabolites of the glycogenic pathway, such as glucose 6-phosphate (Glc-6-P) and UDP-glucose, were not significantly altered. GK overexpression also conferred on the hepatocyte an enhanced capacity to synthesize glycogen in response to glucose, as described previously [Seoane, Gómez-Foix, O'Doherty, Gómez-Ara, Newgard and Guinovart (1996) J. Biol. Chem. 271, 23756-23760], although, in this case, they accumulated Glc-6-P. When GS and GK were simultaneously overexpressed, the accumulation of glycogen was enhanced in comparison with cells overexpressing either GS or GK. Our results are consistent with the hypothesis that liver GS catalyses the rate-limiting step of hepatic glycogen synthesis. However, hepatic glycogen deposition from glucose is submitted to a system of shared control in which the 'controller', GS, is, in turn, controlled by GK. This control is indirectly exerted through Glc-6-P, which 'switches on' GS dephosphorylation and activation. PMID:11042138

  6. Hepatic glycogen can regulate hypoglycemic counterregulation via a liver-brain axis

    PubMed Central

    Kraft, Guillaume; Williams, Phillip; Hajizadeh, Ian A.; Kamal, Maahum Z.; Smith, Marta; Farmer, Ben; Scott, Melanie; Neal, Doss; Donahue, E. Patrick; Allen, Eric; Cherrington, Alan D.

    2016-01-01

    Liver glycogen is important for the counterregulation of hypoglycemia and is reduced in individuals with type 1 diabetes (T1D). Here, we examined the effect of varying hepatic glycogen content on the counterregulatory response to low blood sugar in dogs. During the first 4 hours of each study, hepatic glycogen was increased by augmenting hepatic glucose uptake using hyperglycemia and a low-dose intraportal fructose infusion. After hepatic glycogen levels were increased, animals underwent a 2-hour control period with no fructose infusion followed by a 2-hour hyperinsulinemic/hypoglycemic clamp. Compared with control treatment, fructose infusion caused a large increase in liver glycogen that markedly elevated the response of epinephrine and glucagon to a given hypoglycemia and increased net hepatic glucose output (NHGO). Moreover, prior denervation of the liver abolished the improved counterregulatory responses that resulted from increased liver glycogen content. When hepatic glycogen content was lowered, glucagon and NHGO responses to insulin-induced hypoglycemia were reduced. We conclude that there is a liver-brain counterregulatory axis that is responsive to liver glycogen content. It remains to be determined whether the risk of iatrogenic hypoglycemia in T1D humans could be lessened by targeting metabolic pathway(s) associated with hepatic glycogen repletion. PMID:27140398

  7. Hepatic mitochondrial dysfunction is a feature of Glycogen Storage Disease Type Ia (GSDIa).

    PubMed

    Farah, Benjamin L; Sinha, Rohit A; Wu, Yajun; Singh, Brijesh K; Lim, Andrea; Hirayama, Masahiro; Landau, Dustin J; Bay, Boon Huat; Koeberl, Dwight D; Yen, Paul M

    2017-03-20

    Glycogen storage disease type Ia (GSDIa, von Gierke disease) is the most common glycogen storage disorder. It is caused by the deficiency of glucose-6-phosphatase, an enzyme which catalyses the final step of gluconeogenesis and glycogenolysis. Clinically, GSDIa is characterized by fasting hypoglycaemia and hepatic glycogen and triglyceride overaccumulation. The latter leads to steatohepatitis, cirrhosis, and the formation of hepatic adenomas and carcinomas. Currently, little is known about the function of various organelles and their impact on metabolism in GSDIa. Accordingly, we investigated mitochondrial function in cell culture and mouse models of GSDIa. We found impairments in oxidative phosphorylation and changes in TCA cycle metabolites, as well as decreased mitochondrial membrane potential and deranged mitochondrial ultra-structure in these model systems. Mitochondrial content also was decreased, likely secondary to decreased mitochondrial biogenesis. These deleterious effects culminated in the activation of the mitochondrial apoptosis pathway. Taken together, our results demonstrate a role for mitochondrial dysfunction in the pathogenesis of GSDIa, and identify a new potential target for the treatment of this disease. They also provide new insight into the role of carbohydrate overload on mitochondrial function in other hepatic diseases, such as non-alcoholic fatty liver disease.

  8. Hepatic mitochondrial dysfunction is a feature of Glycogen Storage Disease Type Ia (GSDIa)

    PubMed Central

    Farah, Benjamin L.; Sinha, Rohit A.; Wu, Yajun; Singh, Brijesh K.; Lim, Andrea; Hirayama, Masahiro; Landau, Dustin J.; Bay, Boon Huat; Koeberl, Dwight D.; Yen, Paul M.

    2017-01-01

    Glycogen storage disease type Ia (GSDIa, von Gierke disease) is the most common glycogen storage disorder. It is caused by the deficiency of glucose-6-phosphatase, an enzyme which catalyses the final step of gluconeogenesis and glycogenolysis. Clinically, GSDIa is characterized by fasting hypoglycaemia and hepatic glycogen and triglyceride overaccumulation. The latter leads to steatohepatitis, cirrhosis, and the formation of hepatic adenomas and carcinomas. Currently, little is known about the function of various organelles and their impact on metabolism in GSDIa. Accordingly, we investigated mitochondrial function in cell culture and mouse models of GSDIa. We found impairments in oxidative phosphorylation and changes in TCA cycle metabolites, as well as decreased mitochondrial membrane potential and deranged mitochondrial ultra-structure in these model systems. Mitochondrial content also was decreased, likely secondary to decreased mitochondrial biogenesis. These deleterious effects culminated in the activation of the mitochondrial apoptosis pathway. Taken together, our results demonstrate a role for mitochondrial dysfunction in the pathogenesis of GSDIa, and identify a new potential target for the treatment of this disease. They also provide new insight into the role of carbohydrate overload on mitochondrial function in other hepatic diseases, such as non-alcoholic fatty liver disease. PMID:28317891

  9. Chronic ethanol consumption disrupts diurnal rhythms of hepatic glycogen metabolism in mice

    PubMed Central

    Udoh, Uduak S.; Swain, Telisha M.; Filiano, Ashley N.; Gamble, Karen L.; Young, Martin E.

    2015-01-01

    Chronic ethanol consumption has been shown to significantly decrease hepatic glycogen content; however, the mechanisms responsible for this adverse metabolic effect are unknown. In this study, we examined the impact chronic ethanol consumption has on time-of-day-dependent oscillations (rhythms) in glycogen metabolism processes in the liver. For this, male C57BL/6J mice were fed either a control or ethanol-containing liquid diet for 5 wk, and livers were collected every 4 h for 24 h and analyzed for changes in various genes and proteins involved in hepatic glycogen metabolism. Glycogen displayed a robust diurnal rhythm in the livers of mice fed the control diet, with the peak occurring during the active (dark) period of the day. The diurnal glycogen rhythm was significantly altered in livers of ethanol-fed mice, with the glycogen peak shifted into the inactive (light) period and the overall content of glycogen decreased compared with controls. Chronic ethanol consumption further disrupted diurnal rhythms in gene expression (glycogen synthase 1 and 2, glycogenin, glucokinase, protein targeting to glycogen, and pyruvate kinase), total and phosphorylated glycogen synthase protein, and enzyme activities of glycogen synthase and glycogen phosphorylase, the rate-limiting enzymes of glycogen metabolism. In summary, these results show for the first time that chronic ethanol consumption disrupts diurnal rhythms in hepatic glycogen metabolism at the gene and protein level. Chronic ethanol-induced disruption in these daily rhythms likely contributes to glycogen depletion and disruption of hepatic energy homeostasis, a recognized risk factor in the etiology of alcoholic liver disease. PMID:25857999

  10. FGF19 as a postprandial, insulin-independent activator of hepatic protein and glycogen synthesis.

    PubMed

    Kir, Serkan; Beddow, Sara A; Samuel, Varman T; Miller, Paul; Previs, Stephen F; Suino-Powell, Kelly; Xu, H Eric; Shulman, Gerald I; Kliewer, Steven A; Mangelsdorf, David J

    2011-03-25

    Fibroblast growth factor (FGF) 19 is an enterokine synthesized and released when bile acids are taken up into the ileum. We show that FGF19 stimulates hepatic protein and glycogen synthesis but does not induce lipogenesis. The effects of FGF19 are independent of the activity of either insulin or the protein kinase Akt and, instead, are mediated through a mitogen-activated protein kinase signaling pathway that activates components of the protein translation machinery and stimulates glycogen synthase activity. Mice lacking FGF15 (the mouse FGF19 ortholog) fail to properly maintain blood concentrations of glucose and normal postprandial amounts of liver glycogen. FGF19 treatment restored the loss of glycogen in diabetic animals lacking insulin. Thus, FGF19 activates a physiologically important, insulin-independent endocrine pathway that regulates hepatic protein and glycogen metabolism.

  11. Investigation and management of the hepatic glycogen storage diseases.

    PubMed

    Bhattacharya, Kaustuv

    2015-07-01

    The glycogen storage diseases (GSD) comprise a group of disorders that involve the disruption of metabolism of glycogen. Glycogen is stored in various organs including skeletal muscle, the kidneys and liver. The liver stores glycogen to supply the rest of the body with glucose when required. Therefore, disruption of this process can lead to hypoglycaemia. If glycogen is not broken down effectively, this can lead to hepatomegaly. Glycogen synthase deficiency leads to impaired glycogen synthesis and consequently the liver is small. Glycogen brancher deficiency can lead to abnormal glycogen being stored in the liver leading to a quite different disorder of progressive liver dysfunction. Understanding the physiology of GSD I, III, VI and IX guides dietary treatments and the provision of appropriate amounts and types of carbohydrates. There has been recent re-emergence in the literature of the use of ketones in therapy, either in the form of the salt D,L-3-hydroxybutyrate or medium chain triglyceride (MCT). High protein diets have also been advocated. Alternative waxy maize based starches seem to show promising early data of efficacy. There are many complications of each of these disorders and they need to be prospectively surveyed and managed. Liver and kidney transplantation is still indicated in severe refractory disease.

  12. Investigation and management of the hepatic glycogen storage diseases

    PubMed Central

    2015-01-01

    The glycogen storage diseases (GSD) comprise a group of disorders that involve the disruption of metabolism of glycogen. Glycogen is stored in various organs including skeletal muscle, the kidneys and liver. The liver stores glycogen to supply the rest of the body with glucose when required. Therefore, disruption of this process can lead to hypoglycaemia. If glycogen is not broken down effectively, this can lead to hepatomegaly. Glycogen synthase deficiency leads to impaired glycogen synthesis and consequently the liver is small. Glycogen brancher deficiency can lead to abnormal glycogen being stored in the liver leading to a quite different disorder of progressive liver dysfunction. Understanding the physiology of GSD I, III, VI and IX guides dietary treatments and the provision of appropriate amounts and types of carbohydrates. There has been recent re-emergence in the literature of the use of ketones in therapy, either in the form of the salt D,L-3-hydroxybutyrate or medium chain triglyceride (MCT). High protein diets have also been advocated. Alternative waxy maize based starches seem to show promising early data of efficacy. There are many complications of each of these disorders and they need to be prospectively surveyed and managed. Liver and kidney transplantation is still indicated in severe refractory disease. PMID:26835382

  13. Hormonal control of hepatic glycogen metabolism in food-deprived, continuously swimming coho salmon Oncorhynchus kisutch

    USGS Publications Warehouse

    Vijayan, M.M.; Maule, A.G.; Schreck, C.B.; Moon, T.W.

    1993-01-01

    The plasma cortisol concentration and liver cytosolic glucocorticoid receptor activities of continuously swimming, food-deprived coho salmon (Oncorhynchus kisutch) did not differ from those of resting, fed fish. Plasma glucose concentration was significantly higher in the exercising, starved fish, but there were no significant differences in either hepatic glycogen concentration or hepatic activities of glycogen phosphorylase, glycogen synthase, pyruvate kinase, or lactate dehydrogenase between the two groups. Total glucose production by hepatocytes did not differ significantly between the two groups; glycogen breakdown accounted for all the glucose produced in the resting, fed fish whereas it explained only 59% of the glucose production in the exercised animals. Epinephrine and glucagon stimulation of glucose production by hepatocytes was decreased in the exercised fish without significantly affecting hepatocyte glycogen breakdown in either group. Insulin prevented glycogen breakdown and enhanced glycogen deposition in exercised fish. The results indicate that food-deprived, continuously swimming coho salmon conserve glycogen by decreasing the responsiveness of hepatocytes to catabolic hormones and by increasing the responsiveness to insulin (anabolic hormone).

  14. Hepatic overexpression of a constitutively active form of liver glycogen synthase improves glucose homeostasis.

    PubMed

    Ros, Susana; Zafra, Delia; Valles-Ortega, Jordi; García-Rocha, Mar; Forrow, Stephen; Domínguez, Jorge; Calbó, Joaquim; Guinovart, Joan J

    2010-11-26

    In this study, we tested the efficacy of increasing liver glycogen synthase to improve blood glucose homeostasis. The overexpression of wild-type liver glycogen synthase in rats had no effect on blood glucose homeostasis in either the fed or the fasted state. In contrast, the expression of a constitutively active mutant form of the enzyme caused a significant lowering of blood glucose in the former but not the latter state. Moreover, it markedly enhanced the clearance of blood glucose when fasted rats were challenged with a glucose load. Hepatic glycogen stores in rats overexpressing the activated mutant form of liver glycogen synthase were enhanced in the fed state and in response to an oral glucose load but showed a net decline during fasting. In order to test whether these effects were maintained during long term activation of liver glycogen synthase, we generated liver-specific transgenic mice expressing the constitutively active LGS form. These mice also showed an enhanced capacity to store glycogen in the fed state and an improved glucose tolerance when challenged with a glucose load. Thus, we conclude that the activation of liver glycogen synthase improves glucose tolerance in the fed state without compromising glycogenolysis in the postabsorptive state. On the basis of these findings, we propose that the activation of liver glycogen synthase may provide a potential strategy for improvement of glucose tolerance in the postprandial state.

  15. Direct vs. indirect pathway of hepatic glycogen synthesis as a function of glucose infusion rate

    SciTech Connect

    Bagby, G.J.; Lang, C.H.; Johnson, J.L.; Blakesly, H.L.; Spitzer, J.J.

    1986-03-05

    This study was initiated to determine the influence of the rate of exogenous glucose administration on liver glycogen synthesis by the direct (glucose uptake and incorporation into glycogen) vs the indirect pathway (glucose degradation to 3-carbon intermediates, e.g., lactate, prior to incorporation into glycogen). Catheterized rats were fasted 2 days prior to receiving a 3 hr infusion of glucose at rates of 0 to 230 ..mu..mol/min/kg containing tracer (6-/sup 3/H)- and (U-/sup 14/C)-glucose. Plasma glucose (r = 0.80), insulin (r = 0.90) and lactate (r = 0.84) were correlated with glucose infusion rate. The rate of liver glycogen deposition (0.46 +/- 0.03 ..mu..mol/min/g) did not differ between a glucose infusion rate of 20 and 230 ..mu..mol/min/kg. At the lowest and highest glucose infusion rates hepatic glycogenesis accounted for 87 +/- 6 and 9 +/- 1% of the total glucose load, respectively. The percent contribution of the direct pathways to glycogen deposition ((/sup 3/H) specific activity in hepatic glycogen/(/sup 3/H) specific activity in plasma glucose) increased from 16 +/- 3 to 83 +/- 5% from lowest to highest glucose infusion rates (prevailing plasma glucose concentrations: 9 +/- 1 and 21 +/- 2 mM, respectively). The results indicate that the relative contribution of the direct and indirect pathways of glucogen synthesis are dependent upon the glucose load or plasma glucose concentration.

  16. Anti-insulin effects of amylin and calcitonin-gene-related peptide on hepatic glycogen metabolism.

    PubMed Central

    Gómez-Foix, A M; Rodriguez-Gil, J E; Guinovart, J J

    1991-01-01

    To evaluate the effects of amylin and calcitonin-gene-related peptide (CGRP) as anti-insulin agents in hepatic tissue, we have studied whether these two agents counteracted the action of insulin on glycogen metabolism in isolated rat hepatocytes. In this system insulin stimulates [14C]glucose incorporation into glycogen and activates glycogen synthase. Incubation of the cells with insulin in the presence of amylin or CGRP markedly blocked the insulin stimulation of these two parameters, whereas amylin or CGRP acting alone did not induce any effect. We also examined the ability of amylin and CGRP to modify the anti-glucagon effects of insulin. In the presence of 100 nM-amylin or -CGRP, 10 nM-insulin was almost unable to counteract the inactivation of glycogen synthase and the activation of phosphorylase induced by glucagon. In contrast, neither amylin nor CGRP modified the effect of glucagon on these two enzymes. Our results indicate that amylin and CGRP are able to impair the action of insulin on hepatic glycogen metabolism. PMID:1905922

  17. The glucose-galactose paradox in neonatal murine hepatic glycogen synthesis

    SciTech Connect

    Kunst, C.; Kliegman, R.; Trindade, C. )

    1989-11-01

    In adults glucose incorporation to glycogen is indirect after recycling from lactate. In neonates galactose entry to glycogen exceeds that for glucose, but the pathway is unknown. The pathway of hexose incorporation to glycogen was studied in 5-7-day-old rats and 6-h-old rats injected intraperitoneally (IP) with either double-labeled (6-3H)glucose (nonrecycling), (U-14C)glucose (recycling), or (6-3H)glucose and (U-14C)galactose in saline. In another group of pups, 1 g/kg of glucose or galactose was administered in addition to tracers to determine glycemia and net glycogen synthesis between 15 and 180 min after injection. Blood glucose increased from 3.4 +/- 0.4 to 8.5 +/- 1.5 mM in 5-7-day-old pups in response to IP glucose; there was no glycemic response to galactose, although galactose levels increased from 0.5 to 6.3 mM at 15 min. Hepatic glycogen increased after IP glucose from 14 +/- 2 at 15 min to 30 +/- 3 at 120 min (P less than 0.01), whereas after IP galactose glycogen was 44 +/- 6 mumol/g at 120 min (P less than 0.05). After IP glucose, 3H and 14C disintegration per minute in glycogen increased slowly with 14C exceeding 3H at 120 and 180 min. In contrast IP (14C)galactose resulted in a much greater peak of 14C incorporation into glycogen. The ratio of 3H to 14C in glycogen relative to the injectate after IP glucose decreased from 0.69 +/- 0.12 to 0.36 +/- 0.03 (P less than 0.01) between 15 to 180 min, whereas the ratio after galactose was 0.20 +/- 0.007 to 0.15 +/- 0.02 at these times. The 6-h-old pups also demonstrated augmented incorporation of (14C)galactose in glycogen relative to (3H-14C)glucose. In contrast to 5-7-day-old pups there was no evidence of glucose recycling in 6-h-old pups. In conclusion galactose entry into glycogen exceeds that for glucose and is not dependent on recycling.

  18. The effect of antenatal administration of solcoseryl on hepatic glycogen synthesis in rat fetuses with intrauterine growth retardation.

    PubMed

    Takahashi, H; Cheng, K M; Araki, T

    1993-06-01

    The effect of antenatal solcoseryl administration on hepatic glycogen synthesis and storage was studied in normal developing and intrauterine growth-retarded (IUGR) rat fetuses using biochemical analyses. The maximal effect of solcoseryl occurred 2 hours after administration. The glycogen content of the liver showed a significant increase in normal and IUGR fetuses with antenatal solcoseryl administration compared to their non-solcoseryl counterparts (p < 0.05). The activities of glycogen synthase enzymes, total and active forms, showed significant increases, at p < 0.05 and p < 0.005, respectively, in IUGR fetuses with antenatal solcoseryl administration. Active synthase also increased in normal fetuses with antenatal solcoseryl administration (p < 0.05). There were no significant changes in the activities of glycogen phosphorylase enzyme. These findings suggest that antenatal solcoseryl administration stimulates hepatic glycogen synthesis and storage in IUGR rat fetuses, and thus might favorably influence the development of neonatal hypoglycemia.

  19. ²H enrichment distribution of hepatic glycogen from ²H₂O reveals the contribution of dietary fructose to glycogen synthesis.

    PubMed

    Delgado, Teresa C; Martins, Fátima O; Carvalho, Filipa; Gonçalves, Ana; Scott, Donald K; O'Doherty, Robert; Macedo, M Paula; Jones, John G

    2013-02-15

    Dietary fructose can benefit or hinder glycemic control, depending on the quantity consumed, and these contrasting effects are reflected by alterations in postprandial hepatic glycogen synthesis. Recently, we showed that ²H enrichment of glycogen positions 5 and 2 from deuterated water (²H₂O) informs direct and indirect pathway contributions to glycogenesis in naturally feeding rats. Inclusion of position 6(S) ²H enrichment data allows indirect pathway sources to be further resolved into triose phosphate and Krebs cycle precursors. This analysis was applied to six rats that had fed on standard chow (SC) and six rats that had fed on SC plus 35% sucrose in their drinking water (HS). After 2 wk, hepatic glycogenesis sources during overnight feeding were determined by ²H₂O administration and postmortem analysis of glycogen ²H enrichment at the conclusion of the dark period. Net overnight hepatic glycogenesis was similar between SC and HS rodents. Whereas direct pathway contributions were similar (403 ± 71 μmol/g dry wt HS vs. 578 ± 76 μmol/g dry wt SC), triose phosphate contributions were significantly higher for HS compared with SC (382 ± 61 vs. 87 ± 24 μmol/g dry wt, P < 0.01) and Krebs cycle inputs lower for HS compared with SC (110 ± 9 vs. 197 ± 32 μmol/g dry wt, P < 0.05). Analysis of plasma glucose ²H enrichments at the end of the feeding period also revealed a significantly higher fractional contribution of triose phosphate to plasma glucose levels in HS vs. SC. Hence, the ²H enrichment distributions of hepatic glycogen and glucose from ²H₂O inform the contribution of dietary fructose to hepatic glycogen and glucose synthesis.

  20. Lipids in hepatic glycogen storage diseases: pathophysiology, monitoring of dietary management and future directions.

    PubMed

    Derks, Terry G J; van Rijn, Margreet

    2015-05-01

    Hepatic glycogen storage diseases (GSD) underscore the intimate relationship between carbohydrate and lipid metabolism. The hyperlipidemias in hepatic GSD reflect perturbed intracellular metabolism, providing biomarkers in blood to monitor dietary management. In different types of GSD, hyperlipidemias are of a different origin. Hypertriglyceridemia is most prominent in GSD type Ia and associated with long-term outcome morbidity, like pancreatitis and hepatic adenomas. In the ketotic subtypes of GSD, hypertriglyceridemia reflects the age-dependent fasting intolerance, secondary lipolysis and increased mitochondrial fatty acid oxidation. The role of high protein diets is established for ketotic types of GSD, but non-traditional dietary interventions (like medium-chain triglycerides and the ketogenic diet) in hepatic GSD are still controversial and necessitate further studies. Patients with these rare inherited disorders of carbohydrate metabolism meet several criteria of the metabolic syndrome, therefore close monitoring for cardiovascular diseases in ageing GSD patients may be justified.

  1. Effect of Repeated Glucagon Doses on Hepatic Glycogen in Type 1 Diabetes: Implications for a Bihormonal Closed-Loop System

    PubMed Central

    El Youssef, Joseph; Bakhtiani, Parkash A.; Cai, Yu; Stobbe, Jade M.; Branigan, Deborah; Ramsey, Katrina; Jacobs, Peter; Reddy, Ravi; Woods, Mark; Ward, W. Kenneth

    2015-01-01

    OBJECTIVE To evaluate subjects with type 1 diabetes for hepatic glycogen depletion after repeated doses of glucagon, simulating delivery in a bihormonal closed-loop system. RESEARCH DESIGN AND METHODS Eleven adult subjects with type 1 diabetes participated. Subjects underwent estimation of hepatic glycogen using 13C MRS. MRS was performed at the following four time points: fasting and after a meal at baseline, and fasting and after a meal after eight doses of subcutaneously administered glucagon at a dose of 2 µg/kg, for a total mean dose of 1,126 µg over 16 h. The primary and secondary end points were, respectively, estimated hepatic glycogen by MRS and incremental area under the glucose curve for a 90-min interval after glucagon administration. RESULTS In the eight subjects with complete data sets, estimated glycogen stores were similar at baseline and after repeated glucagon doses. In the fasting state, glycogen averaged 21 ± 3 g/L before glucagon administration and 25 ± 4 g/L after glucagon administration (mean ± SEM) (P = NS). In the fed state, glycogen averaged 40 ± 2 g/L before glucagon administration and 34 ± 4 g/L after glucagon administration (P = NS). With the use of an insulin action model, the rise in glucose after the last dose of glucagon was comparable to the rise after the first dose, as measured by the 90-min incremental area under the glucose curve. CONCLUSIONS In adult subjects with well-controlled type 1 diabetes (mean A1C 7.2%), glycogen stores and the hyperglycemic response to glucagon administration are maintained even after receiving multiple doses of glucagon. This finding supports the safety of repeated glucagon delivery in the setting of a bihormonal closed-loop system. PMID:26341131

  2. Brain glucagon-like peptide–1 increases insulin secretion and muscle insulin resistance to favor hepatic glycogen storage

    PubMed Central

    Knauf, Claude; Cani, Patrice D.; Perrin, Christophe; Iglesias, Miguel A.; Maury, Jean François; Bernard, Elodie; Benhamed, Fadilha; Grémeaux, Thierry; Drucker, Daniel J.; Kahn, C. Ronald; Girard, Jean; Tanti, Jean François; Delzenne, Nathalie M.; Postic, Catherine; Burcelin, Rémy

    2005-01-01

    Intestinal glucagon-like peptide–1 (GLP-1) is a hormone released into the hepatoportal circulation that stimulates pancreatic insulin secretion. GLP-1 also acts as a neuropeptide to control food intake and cardiovascular functions, but its neural role in glucose homeostasis is unknown. We show that brain GLP-1 controlled whole-body glucose fate during hyperglycemic conditions. In mice undergoing a hyperglycemic hyperinsulinemic clamp, icv administration of the specific GLP-1 receptor antagonist exendin 9–39 (Ex9) increased muscle glucose utilization and glycogen content. This effect did not require muscle insulin action, as it also occurred in muscle insulin receptor KO mice. Conversely, icv infusion of the GLP-1 receptor agonist exendin 4 (Ex4) reduced insulin-stimulated muscle glucose utilization. In hyperglycemia achieved by i.v. infusion of glucose, icv Ex4, but not Ex9, caused a 4-fold increase in insulin secretion and enhanced liver glycogen storage. However, when glucose was infused intragastrically, icv Ex9 infusion lowered insulin secretion and hepatic glycogen levels, whereas no effects of icv Ex4 were observed. In diabetic mice fed a high-fat diet, a 1-month chronic i.p. Ex9 treatment improved glucose tolerance and fasting glycemia. Our data show that during hyperglycemia, brain GLP-1 inhibited muscle glucose utilization and increased insulin secretion to favor hepatic glycogen stores, preparing efficiently for the next fasting state. PMID:16322793

  3. Brain glucagon-like peptide-1 increases insulin secretion and muscle insulin resistance to favor hepatic glycogen storage.

    PubMed

    Knauf, Claude; Cani, Patrice D; Perrin, Christophe; Iglesias, Miguel A; Maury, Jean François; Bernard, Elodie; Benhamed, Fadilha; Grémeaux, Thierry; Drucker, Daniel J; Kahn, C Ronald; Girard, Jean; Tanti, Jean François; Delzenne, Nathalie M; Postic, Catherine; Burcelin, Rémy

    2005-12-01

    Intestinal glucagon-like peptide-1 (GLP-1) is a hormone released into the hepatoportal circulation that stimulates pancreatic insulin secretion. GLP-1 also acts as a neuropeptide to control food intake and cardiovascular functions, but its neural role in glucose homeostasis is unknown. We show that brain GLP-1 controlled whole-body glucose fate during hyperglycemic conditions. In mice undergoing a hyperglycemic hyperinsulinemic clamp, icv administration of the specific GLP-1 receptor antagonist exendin 9-39 (Ex9) increased muscle glucose utilization and glycogen content. This effect did not require muscle insulin action, as it also occurred in muscle insulin receptor KO mice. Conversely, icv infusion of the GLP-1 receptor agonist exendin 4 (Ex4) reduced insulin-stimulated muscle glucose utilization. In hyperglycemia achieved by i.v. infusion of glucose, icv Ex4, but not Ex9, caused a 4-fold increase in insulin secretion and enhanced liver glycogen storage. However, when glucose was infused intragastrically, icv Ex9 infusion lowered insulin secretion and hepatic glycogen levels, whereas no effects of icv Ex4 were observed. In diabetic mice fed a high-fat diet, a 1-month chronic i.p. Ex9 treatment improved glucose tolerance and fasting glycemia. Our data show that during hyperglycemia, brain GLP-1 inhibited muscle glucose utilization and increased insulin secretion to favor hepatic glycogen stores, preparing efficiently for the next fasting state.

  4. Melatonin ameliorates high fat diet-induced diabetes and stimulates glycogen synthesis via a PKCzeta-Akt-GSK3beta pathway in hepatic cells.

    PubMed

    Shieh, Jiunn-Min; Wu, Hung-Tsung; Cheng, Kai-Chun; Cheng, Juei-Tang

    2009-11-01

    Low levels of melatonin in circulation had been reported to be related to the development of diabetes. Melatonin administration in animals increases hepatic glycogen content to lower blood glucose. However, the signaling pathway for these effects is still unclear. The present study shows that intraperitoneal injection of 10 mg/kg melatonin ameliorated glucose utilization and insulin sensitivity in high fat diet-induced diabetic mice with an increase in hepatic glycogen and improvement in liver steatosis. We used HepG2 cells to investigate the signaling pathways for the melatonin-stimulated hepatic glycogen increment. Treatment of HepG2 cells with 1 nm melatonin markedly increased glycogen synthesis which was blocked by the melatonin receptor antagonist luzindole. In addition, melatonin increased the phosphorylation of subcellular signals at the level of protein kinase C zeta (PKCzeta), Akt, and glycogen synthase kinase 3beta (GSK3beta) while the increase in glycogen synthesis induced by melatonin was inhibited by PKCzeta pseudo-peptide. However, 3',5'-cyclic adenosine monophosphate-activated protein kinase (AMPK) was not influenced by melatonin treatment. Taken together, melatonin improves glucose intolerance and insulin resistance in high fat diet-induced diabetic mice and stimulates glycogen synthesis via a PKCzeta-Akt-GSK3beta pathway in HepG2 cells.

  5. Glycogenic hepatopathy, an underdiagnosed cause of relapsing hepatitis in uncontrolled type 1 diabetes mellitus

    PubMed Central

    Sarkhy, Ahmed A. Al; Zaidi, Zafar A.; Babiker, Amir M.

    2017-01-01

    Glycogenic hepatopathy is a rare condition that causes significant hepatomegaly and elevated liver enzyme levels in uncontrolled type 1 diabetic patients. It develops due to excessive accumulation of glycogen in the hepatocytes. It is typically reversible with good glycemic control and rarely progresses to mild fibrosis, but not cirrhosis. PMID:28042636

  6. [History case of multiple hepatic adenomas in adolescent with severe course of glycogen storage disease type lb].

    PubMed

    Surkov, A N; Namazova-Baranova, L S; Potapov, A S; Savost'yanov, K V; Pushkov, A A; Nikitin, A G; Polyakova, S I; Ryazanov, M V; Kustova, O V; Barskii, V I; Stepanyan, M Yu

    2014-01-01

    We represented a case history of multiple hepatic adenomas in an adolescent with severe clinical course of glycogen storage disease type lb (compound heterozygous mutations c.1042_1043delCT and c.817G>A in the SLC37A4). The patient was prescribed a raw cornstarch and hepatoprotectors therapy, but he and his parents had low compliance to treatment. At the age of 13,5 years ultrasound investigation and computed tomography revealed multiple adenomas. Due to the severe condition of the patient it was impossible to perform focal hepatic biopsy. At present time the patient receives treatment focused on correction of metabolic disturbances, thereafter an applicability of exploratory puncture will be settled for the further patient surveillance. The modern data on causes and risk factors of hepatic adenomas in such patients, the possibility of their malignization, the algorithm of the follow-up and the methods of treatment are presented in the discussion.

  7. Hepatic lentiviral gene transfer prevents the long-term onset of hepatic tumours of glycogen storage disease type 1a in mice.

    PubMed

    Clar, Julie; Mutel, Elodie; Gri, Blandine; Creneguy, Alison; Stefanutti, Anne; Gaillard, Sophie; Ferry, Nicolas; Beuf, Olivier; Mithieux, Gilles; Nguyen, Tuan Huy; Rajas, Fabienne

    2015-04-15

    Glycogen storage disease type 1a (GSD1a) is a rare disease due to the deficiency in the glucose-6-phosphatase (G6Pase) catalytic subunit (encoded by G6pc), which is essential for endogenous glucose production. Despite strict diet control to maintain blood glucose, patients with GSD1a develop hepatomegaly, steatosis and then hepatocellular adenomas (HCA), which can undergo malignant transformation. Recently, gene therapy has attracted attention as a potential treatment for GSD1a. In order to maintain long-term transgene expression, we developed an HIV-based vector, which allowed us to specifically express the human G6PC cDNA in the liver. We analysed the efficiency of this lentiviral vector in the prevention of the development of the hepatic disease in an original GSD1a mouse model, which exhibits G6Pase deficiency exclusively in the liver (L-G6pc(-/-) mice). Recombinant lentivirus were injected in B6.G6pc(ex3lox/ex3lox). SA(creERT2/w) neonates and G6pc deletion was induced by tamoxifen treatment at weaning. Magnetic resonance imaging was then performed to follow up the development of hepatic tumours. Lentiviral gene therapy restored glucose-6 phosphatase activity sufficient to correct fasting hypoglycaemia during 9 months. Moreover, lentivirus-treated L-G6pc(-/-) mice presented normal hepatic triglyceride levels, whereas untreated mice developed steatosis. Glycogen stores were also decreased although liver weight remained high. Interestingly, lentivirus-treated L-G6pc(-/-) mice were protected against the development of hepatic tumours after 9 months of gene therapy while most of untreated L-G6pc(-/-) mice developed millimetric HCA. Thus the treatment of newborns by recombinant lentivirus appears as an attractive approach to protect the liver from the development of steatosis and hepatic tumours associated to GSD1a pathology.

  8. Current status of hepatic glycogen storage disease in Japan: clinical manifestations, treatments and long-term outcomes.

    PubMed

    Kido, Jun; Nakamura, Kimitoshi; Matsumoto, Shirou; Mitsubuchi, Hiroshi; Ohura, Toshihiro; Shigematsu, Yosuke; Yorifuji, Tohru; Kasahara, Mureo; Horikawa, Reiko; Endo, Fumio

    2013-05-01

    Many reports have been published on the long-term outcome and treatment of hepatic glycogen storage diseases (GSDs) overseas; however, none have been published from Japan. We investigated the clinical manifestations, treatment, and prognosis of 127 hepatic GSD patients who were evaluated and treated between January 1999 and December 2009. A characteristic genetic pattern was noted in the Japanese GSD patients: most GSD Ia patients had the g727t mutation, and many GSD Ib patients had the W118R mutation. Forty-one percent (14/34) of GSD Ia patients and 18% (2/11) of GSD Ib patients of ages 13 years 4 months had liver adenoma. Among subjects aged 10 years, 19% (7/36) of the GSD Ia patients and none of the GSD Ib patients had renal dysfunction. The mean height of male GSD Ia patients aged 18 years was 160.8±10.6 cm (n=14), and that of their female counterparts was 147.8±3.80 cm (n=9). Patients with hepatic GSDs develop a variety of symptoms but can survive in the long term by diet therapy, corn starch treatment and supportive care. Liver transplantation for hepatic GSDs is an important treatment strategy and can help improve the patients'quality of life.

  9. Labeling of hepatic glycogen after short- and long-term stimulation of glycogen synthesis in rats injected with 3H-galactose

    SciTech Connect

    Michaels, J.E.; Garfield, S.A.; Hung, J.T.; Cardell, R.R. Jr. )

    1990-08-01

    The effects of short- and long-term stimulation of glycogen synthesis elicited by dexamethasone were studied by light (LM) and electron (EM) microscopic radioautography (RAG) and biochemical analysis. Adrenalectomized rats were fasted overnight and pretreated for short- (3 hr) or long-term (14 hr) periods with dexamethasone prior to intravenous injection of tracer doses of 3H-galactose. Analysis of LM-RAGs from short-term rats revealed that about equal percentages (44%) of hepatocytes became heavily or lightly labeled 1 hr after labeling. The percentage of heavily labeled cells increased slightly 6 hr after labeling, and unlabeled glycogen became apparent in some hepatocytes. The percentage of heavily labeled cells had decreased somewhat 12 hr after labeling, and more unlabeled glycogen was evident. In the long-term rats 1 hr after labeling, a higher percentage of heavily labeled cells (76%) was observed compared to short-term rats, and most glycogen was labeled. In spite of the high amount of labeling seen initially, the percentage of heavily labeled hepatocytes had decreased considerably to 55% by 12 hr after injection; and sparsely labeled and unlabeled glycogen was prevalent. The EM-RAGs of both short- and long-term rats were similar. Silver grains were associated with glycogen patches 1 hr after labeling; 12 hr after labeling, the glycogen patches had enlarged; and label, where present, was dispersed over the enlarged glycogen clumps. Analysis of DPM/mg tissue corroborated the observed decrease in label 12 hr after administration in the long-term animals. The loss of label observed 12 hr after injection in the long-term pretreated rats suggests that turnover of glycogen occurred during this interval despite the net accumulation of glycogen that was visible morphologically and evident from biochemical measurement.

  10. [Glycogen storage of the liver: a determining factor of initial function of the hepatic graft].

    PubMed

    Boudjema, K; Cinqualbre, J; Barguil, Y; Pattou, F; Kerr, J A; Wolf, P; Southard, J H; Jaeck, D

    1991-01-01

    In this study we have investigated the effects of hepatocytes glycogen storage on the quality of livers for transplantation. Rats were fed or fasted for 24 h and hepatocytes isolated and cold stored in UW solution for 24 and 48 hours. Viability of the cells was analyzed by LDH release after 2 hours incubation in L15 with O2. Also, rabbits were fed, fasted (48 h) or glucose fed (48 h) and livers cold stored for 6, 24 and 48 h in UW solution. Functions of the livers were analyzed by isolated perfusion for 2 hours. Hepatocytes from fasted rats released significantly more LDH than hepatocytes from fed rats after 24 and 48 h cold storage. In rabbit livers, fasting depleted glycogen by 85% but had no effect on ATP or glutathione concentration. Livers from fasted rabbits produced similar amount of bile, released similar concentrations of lactate dehydrogenase and aspartate transaminase into the perfusate, maintained similar concentrations of glutathione after 24 hours preservation when compared to fed animals. After 48 h preservation livers from fasted animals were less viable than livers from fed animals and the decrease of liver functions in livers from fasted animals preserved for 48 hours was prevented by feeding glucose. This study shows that liver glycogen storage in hepatocyte is an important metabolite for successful liver preservation. Glycogen may be a source for ATP and antioxydant synthesis during the early period of reperfusion.

  11. Comparison of /sup 3/H-galactose and /sup 3/H-glucose as precursors of hepatic glycogen in control-fed rats

    SciTech Connect

    Michaels, J.E.; Garfield, S.A.; Hung, J.T.; Cardell, R.R. Jr.

    1989-05-01

    Labeling of hepatic glycogen derived from 3H-galactose and 3H-glucose was compared shortly after intravenous injection in control-fed rats. The rats were allowed to accumulate 5-8% glycogen prior to receiving label. Fifteen minutes to 2 hours after labeling, liver was excised and processed for routine light (LM) and electron microscopic (EM) radioautography (RAG) or biochemical analysis. After injection of 3H-galactose, LM-RAGs revealed that the percentage of heavily labeled hepatocytes increased from 37% after 15 minutes to 68% after 1 hour but showed no further increase after 2 hours. alpha-Amylase treatment removed most glycogen and incorporated label; thus few silver grains were observed, indicating little incorporation of label except into glycogen. EM-RAGs demonstrated that most label occurred where glycogen was located. Biochemical analysis showed initially a high blood level of label that rapidly plateaued at a reduced level by 5 minutes. Concomitantly, glycogen labeling determined by liquid scintillation counting reflected the increases observed in the RAGs. After injection of 3H-glucose, LM-RAGs revealed that only 12% of the hepatocytes were heavily labeled at 1 hour and 20% at 2 hours. In tissue treated with alpha-amylase, glycogen was depleted and label was close to background level at each interval observed. EM-RAGs showed most grains associated with glycogen deposits. Biochemically, blood levels of label persisted at a high level for 30 minutes and tissue levels increased slowly over the 2-hour period. This study shows that incorporation from 3H-galactose was more rapid than incorporation of 3H-glucose; however, label derived from both carbohydrates appeared to be incorporated mainly into glycogen.

  12. A Txnrd1-dependent metabolic switch alters hepatic lipogenesis, glycogen storage, and detoxification.

    PubMed

    Iverson, Sonya V; Eriksson, Sofi; Xu, Jianqiang; Prigge, Justin R; Talago, Emily A; Meade, Tesia A; Meade, Erin S; Capecchi, Mario R; Arnér, Elias S J; Schmidt, Edward E

    2013-10-01

    Besides helping to maintain a reducing intracellular environment, the thioredoxin (Trx) system impacts bioenergetics and drug metabolism. We show that hepatocyte-specific disruption of Txnrd1, encoding Trx reductase-1 (TrxR1), causes a metabolic switch in which lipogenic genes are repressed and periportal hepatocytes become engorged with glycogen. These livers also overexpress machinery for biosynthesis of glutathione and conversion of glycogen into UDP-glucuronate; they stockpile glutathione-S-transferases and UDP-glucuronyl-transferases; and they overexpress xenobiotic exporters. This realigned metabolic profile suggested that the mutant hepatocytes might be preconditioned to more effectively detoxify certain xenobiotic challenges. Hepatocytes convert the pro-toxin acetaminophen (APAP, paracetamol) into cytotoxic N-acetyl-p-benzoquinone imine (NAPQI). APAP defenses include glucuronidation of APAP or glutathionylation of NAPQI, allowing removal by xenobiotic exporters. We found that NAPQI directly inactivates TrxR1, yet Txnrd1-null livers were resistant to APAP-induced hepatotoxicity. Txnrd1-null livers did not have more effective gene expression responses to APAP challenge; however, their constitutive metabolic state supported more robust GSH biosynthesis, glutathionylation, and glucuronidation systems. Following APAP challenge, this effectively sustained the GSH system and attenuated damage.

  13. Irisin inhibits hepatic gluconeogenesis and increases glycogen synthesis via the PI3K/Akt pathway in type 2 diabetic mice and hepatocytes.

    PubMed

    Liu, Tong-Yan; Shi, Chang-Xiang; Gao, Run; Sun, Hai-Jian; Xiong, Xiao-Qing; Ding, Lei; Chen, Qi; Li, Yue-Hua; Wang, Jue-Jin; Kang, Yu-Ming; Zhu, Guo-Qing

    2015-11-01

    Increased glucose production and reduced hepatic glycogen storage contribute to metabolic abnormalities in diabetes. Irisin, a newly identified myokine, induces the browning of white adipose tissue, but its effects on gluconeogenesis and glycogenesis are unknown. In the present study, we investigated the effects and underlying mechanisms of irisin on gluconeogenesis and glycogenesis in hepatocytes with insulin resistance, and its therapeutic role in type 2 diabetic mice. Insulin resistance was induced by glucosamine (GlcN) or palmitate in human hepatocellular carcinoma (HepG2) cells and mouse primary hepatocytes. Type 2 diabetes was induced by streptozotocin/high-fat diet (STZ/HFD) in mice. In HepG2 cells, irisin ameliorated the GlcN-induced increases in glucose production, phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6Pase) expression, and glycogen synthase (GS) phosphorylation; it prevented GlcN-induced decreases in glycogen content and the phosphoinositide 3-kinase (PI3K) p110α subunit level, and the phosphorylation of Akt/protein kinase B, forkhead box transcription factor O1 (FOXO1) and glycogen synthase kinase-3 (GSK3). These effects of irisin were abolished by the inhibition of PI3K or Akt. The effects of irisin were confirmed in mouse primary hepatocytes with GlcN-induced insulin resistance and in human HepG2 cells with palmitate-induced insulin resistance. In diabetic mice, persistent subcutaneous perfusion of irisin improved the insulin sensitivity, reduced fasting blood glucose, increased GSK3 and Akt phosphorylation, glycogen content and irisin level, and suppressed GS phosphorylation and PEPCK and G6Pase expression in the liver. Irisin improves glucose homoeostasis by reducing gluconeogenesis via PI3K/Akt/FOXO1-mediated PEPCK and G6Pase down-regulation and increasing glycogenesis via PI3K/Akt/GSK3-mediated GS activation. Irisin may be regarded as a novel therapeutic strategy for insulin resistance and type 2 diabetes.

  14. Nuclear assembly with lambda DNA in fractionated Xenopus egg extracts: an unexpected role for glycogen in formation of a higher order chromatin intermediate

    PubMed Central

    1994-01-01

    Crude extracts of Xenopus eggs are capable of nuclear assembly around chromatin templates or even around protein-free, naked DNA templates. Here the requirements for nuclear assembly around a naked DNA template were investigated. Extracts were separated by ultracentrifugation into cytosol, membrane, and gelatinous pellet fractions. It was found that, in addition to the cytosolic and membrane fractions, a component of the gelatinous pellet fraction was required for the assembly of functional nuclei around a naked DNA template. In the absence of this component, membrane-bound but functionally inert spheres of lambda DNA were formed. Purification of the active pellet factor unexpectedly demonstrated the component to be glycogen. The assembly of functionally active nuclei, as assayed by DNA replication and nuclear transport, required that glycogen be pre-incubated with the lambda DNA and cytosol during the period of chromatin and higher order intermediate formation, before the addition of membranes. Hydrolysis of glycogen with alpha- amylase in the extract blocked nuclear formation. Upon analysis, chromatin formed in the presence of cytosol and glycogen alone appeared highly condensed, reminiscent of the nuclear assembly intermediate described by Newport in crude extracts (Newport, J. 1987. Cell. 48:205- 217). In contrast, chromatin formed from phage lambda DNA in cytosol lacking glycogen formed "fluffy chromatin-like" structures. Using sucrose gradient centrifugation, the highly condensed intermediates formed in the presence of glycogen could be isolated and were now able to serve as nuclear assembly templates in extracts lacking glycogen, arguing that the requirement for glycogen is temporally restricted to the time of intermediate formation and function. Glycogen does not act simply by inducing condensation of the chromatin, since similarly isolated mitotically condensed chromatin intermediates do not form functional nuclei. However, both mitotic and fluffy

  15. History of Hepatic Bile Formation: Old Problems, New Approaches

    ERIC Educational Resources Information Center

    Javitt, Norman B.

    2014-01-01

    Studies of hepatic bile formation reported in 1958 established that it was an osmotically generated water flow. Intravenous infusion of sodium taurocholate established a high correlation between hepatic bile flow and bile acid excretion. Secretin, a hormone that stimulates bicarbonate secretion, was also found to increase hepatic bile flow. The…

  16. Prior Exercise Training Prevent Hyperglycemia in STZ Mice by Increasing Hepatic Glycogen and Mitochondrial Function on Skeletal Muscle.

    PubMed

    de Carvalho, Afonso Kopczynski; da Silva, Sabrina; Serafini, Edenir; de Souza, Daniela Roxo; Farias, Hemelin Resende; de Bem Silveira, Gustavo; Silveira, Paulo Cesar Lock; de Souza, Claudio Teodoro; Portela, Luis Valmor; Muller, Alexandre Pastoris

    2017-04-01

    Diabetes mellitus is a metabolic disorder characterized by hyperglycemia. We investigated the effect of a prior 30 days voluntary exercise protocol on STZ-diabetic CF1 mice. Glycemia, and the liver and skeletal muscle glycogen, mitochondrial function, and redox status were analyzed up to 5 days after STZ injection. Animals were engaged in the following groups: Sedentary vehicle (Sed Veh), Sedentary STZ (Sed STZ), Exercise Vehicle (Ex Veh), and Exercise STZ (Ex STZ). Exercise prevented fasting hyperglycemia in the Ex STZ group. In the liver, there was decreased on glycogen level in Sed STZ group but not in EX STZ group. STZ groups showed decreased mitochondrial oxygen consumption compared to vehicle groups, whereas mitochondrial H2 O2 production was not different between groups. Addition of ADP to the medium did not decrease H2 O2 production in Sed STZ mice. Exercise increased GSH level. Sed STZ group increased nitrite levels compared to other groups. In quadriceps muscle, glycogen level was similar between groups. The Sed STZ group displayed decreased O2 consumption, and exercise prevented this reduction. The H2 O2 production was higher in Ex STZ when compared to other groups. Also, GSH level decreased whereas nitrite levels increased in the Sed STZ compared to other groups. The PGC1 α levels increased in Sed STZ, Ex Veh, and Ex STZ groups. In summary, prior exercise training prevents hyperglycemia in STZ-mice diabetic associated with increased liver glycogen storage, and oxygen consumption by the mitochondria of skeletal muscle implying in increased oxidative/biogenesis capacity, and improved redox status of both tissues. J. Cell. Biochem. 118: 678-685, 2017. © 2016 Wiley Periodicals, Inc.

  17. Biomarker for Glycogen Storage Diseases

    ClinicalTrials.gov

    2016-08-25

    Fructose Metabolism, Inborn Errors; Glycogen Storage Disease; Glycogen Storage Disease Type I; Glycogen Storage Disease Type II; Glycogen Storage Disease Type III; Glycogen Storage Disease Type IV; Glycogen Storage Disease Type V; Glycogen Storage Disease Type VI; Glycogen Storage Disease Type VII; Glycogen Storage Disease Type VIII

  18. [Antibody formation in type A viral hepatitis].

    PubMed

    Teokharova, M P; Losev, B B; Andonov, A P; Draganov, P I; Mineva, E G

    1978-01-01

    Immune response to hepatitis type A antigen (HAAg) was measured by the passive hemagglutination test (PHA) and by the immune adherence test (IAHA). Specific antibodies found by PHA are of the IgM class which indicates a recent exposure to hepatitis A virus. The antibodies found by IAHA reflect the level of postinfectious immune status. The antibody curve is highest in the age group of 30--49 years (95%). The above-mentioned serological tests were carried out with purified by gel filtration in Sepharose 6B Botevgrad faecal morphologically consisting of 27 nm particles with the buoyant density in CcCl of 1.40 g/ml. The same particles were aggregated with sera positive for antibody to hepatitis type A antigen in immune electron microscopy (IEM).

  19. Effect of Entodinium caudatum on starch intake and glycogen formation by Eudiplodinium maggii in the rumen and reticulum.

    PubMed

    Bełżecki, Grzegorz; McEwan, Neil R; Kowalik, Barbara; Michałowski, Tadeusz; Miltko, Renata

    2017-02-01

    This study aimed to quantify the engulfed starch and reserve α-glucans (glycogen) in the cells of the ciliates Eudiplodinium maggii, as well the α-glucans in defaunated and selectively faunated sheep. The content of starch inside the cell of ciliates varied from 21 to 183mg/g protozoal DM relative to the rumen fauna composition whereas, the glycogen fluctuated between 17 and 126mg/g dry matter (DM) of this ciliate species. Establishment of the population Entodinium caudatum in the rumen of sheep already faunated with E. maggii caused a drop in both types of quantified carbohydrates. The content of α-glucans in the rumen of defaunated sheep varied from 4.4 to 19.9mg/g DM and increased to 7.4-29.9 or 11.8-33.9mg/g DM of rumen contents in the presence of only E. maggii or E. maggii and E. caudatum, respectively. The lowest content of the carbohydrates was always found just before feeding and the highest at 4h thereafter. The α-glucans in the reticulum varied 7.5-40.1, 14.3-76.8 or 21.9-106.1mg/g DM of reticulum content for defaunated, monofaunated or bifaunated sheep, respectively. The results indicated that both ciliate species engulf starch granules and convert the digestion products to the glycogen, diminishing the pool of starch available for amylolytic bacteria.

  20. Glycogen storage diseases: New perspectives

    PubMed Central

    Özen, Hasan

    2007-01-01

    Glycogen storage diseases (GSD) are inherited metabolic disorders of glycogen metabolism. Different hormones, including insulin, glucagon, and cortisol regulate the relationship of glycolysis, gluconeogenesis and glycogen synthesis. The overall GSD incidence is estimated 1 case per 20000-43000 live births. There are over 12 types and they are classified based on the enzyme deficiency and the affected tissue. Disorders of glycogen degradation may affect primarily the liver, the muscle, or both. Type Ia involves the liver, kidney and intestine (and Ib also leukocytes), and the clinical manifestations are hepatomegaly, failure to thrive, hypoglycemia, hyperlactatemia, hyperuricemia and hyperlipidemia. Type IIIa involves both the liver and muscle, and IIIb solely the liver. The liver symptoms generally improve with age. Type IV usually presents in the first year of life, with hepatomegaly and growth retardation. The disease in general is progressive to cirrhosis. Type VI and IX are a heterogeneous group of diseases caused by a deficiency of the liver phosphorylase and phosphorylase kinase system. There is no hyperuricemia or hyperlactatemia. Type XI is characterized by hepatic glycogenosis and renal Fanconi syndrome. Type II is a prototype of inborn lysosomal storage diseases and involves many organs but primarily the muscle. Types V and VII involve only the muscle. PMID:17552001

  1. The 3T3-L1 adipocyte glycogen proteome

    PubMed Central

    2013-01-01

    Background Glycogen is a branched polysaccharide of glucose residues, consisting of α-1-4 glycosidic linkages with α-1-6 branches that together form multi-layered particles ranging in size from 30 nm to 300 nm. Glycogen spatial conformation and intracellular organization are highly regulated processes. Glycogen particles interact with their metabolizing enzymes and are associated with a variety of proteins that intervene in its biology, controlling its structure, particle size and sub-cellular distribution. The function of glycogen in adipose tissue is not well understood but appears to have a pivotal role as a regulatory mechanism informing the cells on substrate availability for triacylglycerol synthesis. To provide new molecular insights into the role of adipocyte glycogen we analyzed the glycogen-associated proteome from differentiated 3T3-L1-adipocytes. Results Glycogen particles from 3T3-L1-adipocytes were purified using a series of centrifugation steps followed by specific elution of glycogen bound proteins using α-1,4 glucose oligosaccharides, or maltodextrins, and tandem mass spectrometry. We identified regulatory proteins, 14-3-3 proteins, RACK1 and protein phosphatase 1 glycogen targeting subunit 3D. Evidence was also obtained for a regulated subcellular distribution of the glycogen particle: metabolic and mitochondrial proteins were abundant. Unlike the recently analyzed hepatic glycogen proteome, no endoplasmic proteins were detected, along with the recently described starch-binding domain protein 1. Other regulatory proteins which have previously been described as glycogen-associated proteins were not detected, including laforin, the AMPK beta-subunit and protein targeting to glycogen (PTG). Conclusions These data provide new molecular insights into the regulation of glycogen-bound proteins that are associated with the maintenance, organization and localization of the adipocyte glycogen particle. PMID:23521774

  2. Precursors to glycogen in ovine fetuses

    SciTech Connect

    Levitsky, L.L.; Paton, J.B.; Fisher, D.E. )

    1988-11-01

    Postprandial hepatic glycogenesis in the adult animal is now felt to proceed largely through gluconeogenic pathways rather than directly from glucose. The ovine fetus, like the mature sheep, lacks specific hepatic glucokinase. Therefore, the authors examined the role of lactate as a fetal glycogenic precursor in seven chronically catheterized 125-day sheep fetuses. Fetuses were infused with L-(U-{sup 14}C)lactate and D-(3-{sup 3}H)glucose, while maternal glucose was maintained at 50 mg/dl. Mean fetal hepatic glycogen specific activity ({mu}Ci/mg {times} 10{sup 3}) was 0.82 {plus minus} 0.08 for {sup 14}C and 2.6 {plus minus} 0.4 for {sup 3}H, whereas fetal renal glycogen specific activity was 0.46 {plus minus} 0.22 for {sup 14}C and 0.78 {plus minus} 0.16 for {sup 3}H. In contrast, ({sup 14}C)glucose specific activity was undetectable in blood and mean ({sup 3}H)glucose specific activity was 8.9 {plus minus} 1.3 {mu}Ci/mg {times} 10{sup 3}. The least detectable specific activity of ({sup 14}C)glucose did not differ significantly from the ({sup 14}C)glycogen enrichment in liver, whereas ({sup 3}H)glucose specific activity was significantly greater than ({sup 3}H)glycogen enrichment. The authors conclude that glycogenesis from glucose is partly through the indirect gluconeogenic route and that lactate may be a glycogenic precursor in the ovine fetus.

  3. Human stem cell osteoblastogenesis mediated by novel glycogen synthase kinase 3 inhibitors induces bone formation and a unique bone turnover biomarker profile in rats

    SciTech Connect

    Gilmour, Peter S.; O'Shea, Patrick J.; Fagura, Malbinder; Pilling, James E.; Sanganee, Hitesh; Wada, Hiroki; Courtney, Paul F.; Kavanagh, Stefan; Hall, Peter A.; Escott, K. Jane

    2013-10-15

    Wnt activation by inhibiting glycogen synthase kinase 3 (GSK-3) causes bone anabolism in rodents making GSK-3 a potential therapeutic target for osteoporotic and osteolytic metastatic bone disease. To understand the wnt pathway related to human disease translation, the ability of 3 potent inhibitors of GSK-3 (AZD2858, AR79, AZ13282107) to 1) drive osteoblast differentiation and mineralisation using human adipose-derived stem cells (hADSC) in vitro; and 2) stimulate rat bone formation in vivo was investigated. Bone anabolism/resorption was determined using clinically relevant serum biomarkers as indicators of bone turnover and bone formation assessed in femurs by histopathology and pQCT/μCT imaging. GSK-3 inhibitors caused β-catenin stabilisation in human and rat mesenchymal stem cells, stimulated hADSC commitment towards osteoblasts and osteogenic mineralisation in vitro. AZD2858 produced time-dependent changes in serum bone turnover biomarkers and increased bone mass over 28 days exposure in rats. After 7 days, AZD2858, AR79 or AZ13282107 exposure increased the bone formation biomarker P1NP, and reduced the resorption biomarker TRAcP-5b, indicating increased bone anabolism and reduced resorption in rats. This biomarker profile was differentiated from anabolic agent PTH{sub 1–34} or the anti-resorptive Alendronate-induced changes. Increased bone formation in cortical and cancellous bone as assessed by femur histopathology supported biomarker changes. 14 day AR79 treatment increased bone mineral density and trabecular thickness, and decreased trabecular number and connectivity assessed by pQCT/μCT. GSK-3 inhibition caused hADSC osteoblastogenesis and mineralisation in vitro. Increased femur bone mass associated with changes in bone turnover biomarkers confirmed in vivo bone formation and indicated uncoupling of bone formation and resorption. - Highlights: • Wnt modulation with 3 novel GSK-3 inhibitors alters bone growth. • Human stem cell osteoblastogenesis

  4. Hepatitis

    MedlinePlus

    ... Loss Surgery? A Week of Healthy Breakfasts Shyness Hepatitis KidsHealth > For Teens > Hepatitis Print A A A ... to a liver condition called hepatitis . What Is Hepatitis? The liver is one of the body's powerhouses. ...

  5. Hepatitis

    MedlinePlus

    ... de los dientes Video: Getting an X-ray Hepatitis KidsHealth > For Kids > Hepatitis Print A A A ... an important digestive liquid called bile . What Is Hepatitis? Hepatitis is an inflammation (say: in-fluh-MAY- ...

  6. PER2 promotes glucose storage to liver glycogen during feeding and acute fasting by inducing Gys2 PTG and G L expression.

    PubMed

    Zani, Fabio; Breasson, Ludovic; Becattini, Barbara; Vukolic, Ana; Montani, Jean-Pierre; Albrecht, Urs; Provenzani, Alessandro; Ripperger, Juergen A; Solinas, Giovanni

    2013-01-01

    The interplay between hepatic glycogen metabolism and blood glucose levels is a paradigm of the rhythmic nature of metabolic homeostasis. Here we show that mice lacking a functional PER2 protein (Per2 (Brdm1) ) display reduced fasting glycemia, altered rhythms of hepatic glycogen accumulation, and altered rhythms of food intake. Per2 (Brdm1) mice show reduced hepatic glycogen content and altered circadian expression during controlled fasting and refeeding. Livers from Per2 (Brdm1) mice display reduced glycogen synthase protein levels during refeeding, and increased glycogen phosphorylase activity during fasting. The latter is explained by PER2 action on the expression of the adapter proteins PTG and GL, which target the protein phosphatase-1 to glycogen to decrease glycogen phosphorylase activity. Finally, PER2 interacts with genomic regions of Gys2, PTG, and G L . These results indicate an important role for PER2 in the hepatic transcriptional response to feeding and acute fasting that promotes glucose storage to liver glycogen.

  7. Role of Maltose Enzymes in Glycogen Synthesis by Escherichia coli▿

    PubMed Central

    Park, Jong-Tae; Shim, Jae-Hoon; Tran, Phuong Lan; Hong, In-Hee; Yong, Hwan-Ung; Oktavina, Ershita Fitria; Nguyen, Hai Dang; Kim, Jung-Wan; Lee, Tae Soo; Park, Sung-Hoon; Boos, Winfried; Park, Kwan-Hwa

    2011-01-01

    Mutants with deletion mutations in the glg and mal gene clusters of Escherichia coli MC4100 were used to gain insight into glycogen and maltodextrin metabolism. Glycogen content, molecular mass, and branch chain distribution were analyzed in the wild type and in ΔmalP (encoding maltodextrin phosphorylase), ΔmalQ (encoding amylomaltase), ΔglgA (encoding glycogen synthase), and ΔglgA ΔmalP derivatives. The wild type showed increasing amounts of glycogen when grown on glucose, maltose, or maltodextrin. When strains were grown on maltose, the glycogen content was 20 times higher in the ΔmalP strain (0.97 mg/mg protein) than in the wild type (0.05 mg/mg protein). When strains were grown on glucose, the ΔmalP strain and the wild type had similar glycogen contents (0.04 mg/mg and 0.03 mg/mg protein, respectively). The ΔmalQ mutant did not grow on maltose but showed wild-type amounts of glycogen when grown on glucose, demonstrating the exclusive function of GlgA for glycogen synthesis in the absence of maltose metabolism. No glycogen was found in the ΔglgA and ΔglgA ΔmalP strains grown on glucose, but substantial amounts (0.18 and 1.0 mg/mg protein, respectively) were found when they were grown on maltodextrin. This demonstrates that the action of MalQ on maltose or maltodextrin can lead to the formation of glycogen and that MalP controls (inhibits) this pathway. In vitro, MalQ in the presence of GlgB (a branching enzyme) was able to form glycogen from maltose or linear maltodextrins. We propose a model of maltodextrin utilization for the formation of glycogen in the absence of glycogen synthase. PMID:21421758

  8. Role of maltose enzymes in glycogen synthesis by Escherichia coli.

    PubMed

    Park, Jong-Tae; Shim, Jae-Hoon; Tran, Phuong Lan; Hong, In-Hee; Yong, Hwan-Ung; Oktavina, Ershita Fitria; Nguyen, Hai Dang; Kim, Jung-Wan; Lee, Tae Soo; Park, Sung-Hoon; Boos, Winfried; Park, Kwan-Hwa

    2011-05-01

    Mutants with deletion mutations in the glg and mal gene clusters of Escherichia coli MC4100 were used to gain insight into glycogen and maltodextrin metabolism. Glycogen content, molecular mass, and branch chain distribution were analyzed in the wild type and in ΔmalP (encoding maltodextrin phosphorylase), ΔmalQ (encoding amylomaltase), ΔglgA (encoding glycogen synthase), and ΔglgA ΔmalP derivatives. The wild type showed increasing amounts of glycogen when grown on glucose, maltose, or maltodextrin. When strains were grown on maltose, the glycogen content was 20 times higher in the ΔmalP strain (0.97 mg/mg protein) than in the wild type (0.05 mg/mg protein). When strains were grown on glucose, the ΔmalP strain and the wild type had similar glycogen contents (0.04 mg/mg and 0.03 mg/mg protein, respectively). The ΔmalQ mutant did not grow on maltose but showed wild-type amounts of glycogen when grown on glucose, demonstrating the exclusive function of GlgA for glycogen synthesis in the absence of maltose metabolism. No glycogen was found in the ΔglgA and ΔglgA ΔmalP strains grown on glucose, but substantial amounts (0.18 and 1.0 mg/mg protein, respectively) were found when they were grown on maltodextrin. This demonstrates that the action of MalQ on maltose or maltodextrin can lead to the formation of glycogen and that MalP controls (inhibits) this pathway. In vitro, MalQ in the presence of GlgB (a branching enzyme) was able to form glycogen from maltose or linear maltodextrins. We propose a model of maltodextrin utilization for the formation of glycogen in the absence of glycogen synthase.

  9. Campylobacter jejuni CsrA complements an Escherichia coli csrA mutation for the regulation of biofilm formation, motility and cellular morphology but not glycogen accumulation

    PubMed Central

    2012-01-01

    Background Although Campylobacter jejuni is consistently ranked as one of the leading causes of bacterial diarrhea worldwide, the mechanisms by which C. jejuni causes disease and how they are regulated have yet to be clearly defined. The global regulator, CsrA, has been well characterized in several bacterial genera and is known to regulate a number of independent pathways via a post transcriptional mechanism, but remains relatively uncharacterized in the genus Campylobacter. Previously, we reported data illustrating the requirement for CsrA in several virulence related phenotypes of C. jejuni strain 81–176, indicating that the Csr pathway is important for Campylobacter pathogenesis. Results We compared the Escherichia coli and C. jejuni orthologs of CsrA and characterized the ability of the C. jejuni CsrA protein to functionally complement an E. coli csrA mutant. Phylogenetic comparison of E. coli CsrA to orthologs from several pathogenic bacteria demonstrated variability in C. jejuni CsrA relative to the known RNA binding domains of E. coli CsrA and in several amino acids reported to be involved in E. coli CsrA-mediated gene regulation. When expressed in an E. coli csrA mutant, C. jejuni CsrA succeeded in recovering defects in motility, biofilm formation, and cellular morphology; however, it failed to return excess glycogen accumulation to wild type levels. Conclusions These findings suggest that C. jejuni CsrA is capable of efficiently binding some E. coli CsrA binding sites, but not others, and provide insight into the biochemistry of C. jejuni CsrA. PMID:23051923

  10. Hepatitis

    MedlinePlus

    ... clotting problems or chronic liver disease. previous continue Hepatitis B and Hepatitis C Although hep A is a ... does — through direct contact with infected body fluids. Hepatitis B and C are even more easily passed in ...

  11. Hepatitis

    MedlinePlus

    ... A if they've been vaccinated against it. Hepatitis B Hepatitis B is a more serious infection. It may lead ... of which cause severe illness and even death. Hepatitis B virus (HBV) is transmitted from person to person ...

  12. Hepatitis

    MedlinePlus

    ... Issues Listen Español Text Size Email Print Share Hepatitis Page Content Article Body Hepatitis means “inflammation of ... it has been associated with drinking contaminated water. Hepatitis Viruses Type Transmission Prognosis A Fecal-oral (stool ...

  13. Ameliorating effect of betanin, a natural chromoalkaloid by modulating hepatic carbohydrate metabolic enzyme activities and glycogen content in streptozotocin - nicotinamide induced experimental rats.

    PubMed

    Dhananjayan, Indumathi; Kathiroli, Sujithra; Subramani, Srinivasan; Veerasamy, Vinothkumar

    2017-04-01

    Betanin, a chromoalkaloid of beetroot, has shown significant biological effects of antioxidants, anti-inflammatory and anticarcinogenic activities. So, we attempted to determine whether betanin (a natural pigment) would be protective against hyperglycemia in streptozotocin (STZ) - nicotinamide (NA) induced diabetic rats. Rats were injected with STZ (40mg/kgb.w.) 15 mins after the administration of NA (110mg/kgb.w.) by intraperitonially (i.p.) 30days for the induction of experimental diabetes mellitus. After 72h diabetic rats were treated with betanin orally at a doses of 10, 20 and 40mg/kg b.w., respectively in a dose dependent manner and glibenclamide (600μg/kgb.w.). The promising character of betanin against diabetic rats was evaluated by performing the various biochemical parameters and histomorphological changes in liver and pancreas. Among the three doses, 20mg/kgb.w. of betanin was able to positively regulate plasma glucose, insulin, glycosylated hemoglobin (HbA1c) and hemoglobin (Hb) levels by significantly increasing the activity of glycolytic enzyme (glucokinase and pyruvate kinase), glucose-6-phosphate dehydrogenase and significantly decreasing the activity of gluconeogenic enzymes (glucose-6-phosphatase and fructose-1,6-bisphosphatase) thereby increasing the glycogen content in the liver. We put forward that betanin could significantly restore the levels of carbohydrate metabolic key enzymes to near normal in diabetic rat. Immunohistochemical observation of pancreas revealed that betanin treated diabetic rats showed increased insulin immunoreactive β-cells, which confirmed the biochemical findings. Taken together, present study suggests that betanin modulates the carbohydrate metabolism and has beneficial effects in glucose homeostasis.

  14. [Effect of metformin on the formation of hepatic fibrosis in type 2 diabetic rats].

    PubMed

    Qiang, Gui-Fen; Zhang, Li; Xuan, Qi; Yang, Xiu-Ying; Shi, Li-Li; Zhang, Heng-Ai; Chen, Bai-Nian; Du, Guan-Hua

    2010-06-01

    The aim of this study is to investigate the effects of the metformin on the formation of hepatic fibrosis in type 2 diabetic rats and discuss its mechanism of liver-protecting activity. After SD rats were fed with high-fat and high-sucrose diet for four weeks, low-dose streptozotocin (STZ) was injected intraperitoneally to make the animal mode of type 2 diabetes. Then, all diabetic rats was fed with the high-fat diet and metformin (ig, 100 mg x kg(-1)) was given orally to metformin group for four months. After the last administration, fasting blood glucose was determined. The livers were removed to calculate the hepatic coefficient and to make HE and Picro acid-Sirius red staining, immunohistochemistry (alpha-SMA and TGFbeta1) and TUNEL staining in order to evaluate the effect of metformin on the hepatic fibrosis. The animal model of type 2 diabetes with hepatic fibrosis was successfully made. Metformin can significantly alleviate the lesions of hepatic steatosis and fibrosis, markedly reduce the expressions of alpha-SMA and TGFbeta1 in liver tissue of type 2 diabetic rats. However, TUNEL staining result suggested that metformin could not reduce apoptosis of hepatocytes. The results suggest that metformin can inhibit the formation of hepatic fibrosis in type 2 diabetes.

  15. Metabolic crosstalk: molecular links between glycogen and lipid metabolism in obesity.

    PubMed

    Lu, Binbin; Bridges, Dave; Yang, Yemen; Fisher, Kaleigh; Cheng, Alan; Chang, Louise; Meng, Zhuo-Xian; Lin, Jiandie D; Downes, Michael; Yu, Ruth T; Liddle, Christopher; Evans, Ronald M; Saltiel, Alan R

    2014-09-01

    Glycogen and lipids are major storage forms of energy that are tightly regulated by hormones and metabolic signals. We demonstrate that feeding mice a high-fat diet (HFD) increases hepatic glycogen due to increased expression of the glycogenic scaffolding protein PTG/R5. PTG promoter activity was increased and glycogen levels were augmented in mice and cells after activation of the mechanistic target of rapamycin complex 1 (mTORC1) and its downstream target SREBP1. Deletion of the PTG gene in mice prevented HFD-induced hepatic glycogen accumulation. Of note, PTG deletion also blocked hepatic steatosis in HFD-fed mice and reduced the expression of numerous lipogenic genes. Additionally, PTG deletion reduced fasting glucose and insulin levels in obese mice while improving insulin sensitivity, a result of reduced hepatic glucose output. This metabolic crosstalk was due to decreased mTORC1 and SREBP activity in PTG knockout mice or knockdown cells, suggesting a positive feedback loop in which once accumulated, glycogen stimulates the mTORC1/SREBP1 pathway to shift energy storage to lipogenesis. Together, these data reveal a previously unappreciated broad role for glycogen in the control of energy homeostasis.

  16. The formation, disposition, and hepatic metabolism of dimethylnitrosamine in the pig.

    PubMed

    Harrington, G W; Magee, P N; Pylypiw, H M; Kozeniauskas, R; Bevill, R F; Nelson, D R; Thurmon, J C

    1990-01-01

    The disposition, metabolism, and endogenous formation of N-nitrosodimethylamine (NDMA) from nitrosatable precursors was studied in the intact pig and in animals with cannulated hepatic and portal veins and catheterized bile ducts. Rates of disappearance of NDMA from peripheral venous and arterial blood after iv injections were virtually identical and the compound appeared in bile after a lag time of about 1 hr, with a subsequent decline in biliary concentration at about the same rate as in circulating blood. Measurements of NDMA in portal and hepatic vein blood after oral doses of 10, 1.0 and 0.1 mg/kg, respectively, showed progressively greater hepatic extraction with levels in the hepatic vein approaching the limits of detection after the lowest dose. Both halothane and ethanol virtually abolished the hepatic extraction of NDMA, presumably due to their known inhibitory action on its metabolism in the liver. Endogenous formation of NDMA and N-nitrosomorpholine after oral doses of the amines plus nitrite was demonstrated by their detection and measurement in the portal vein blood. Morpholine was nitrosated more effectively than dimethylamine and inhibited the nitrosation of the latter when the two amines were given together. NDMA was found in the portal blood after sequential oral administration of aminopyrine and nitrite, the concentration being considerably greater after fasting for 24 hr than after a 2-hr fast when much food was present in the stomach.

  17. Natural Progression of Canine Glycogen Storage Disease Type IIIa

    PubMed Central

    Brooks, Elizabeth D; Yi, Haiqing; Austin, Stephanie L; Thurberg, Beth L; Young, Sarah P; Fyfe, John C; Kishnani, Priya S; Sun, Baodong

    2016-01-01

    Glycogen storage disease type IIIa (GSD IIIa) is caused by a deficiency of glycogen debranching enzyme activity. Hepatomegaly, muscle degeneration, and hypoglycemia occur in human patients at an early age. Long-term complications include liver cirrhosis, hepatic adenomas, and generalized myopathy. A naturally occurring canine model of GSD IIIa that mimics the human disease has been described, with progressive liver disease and skeletal muscle damage likely due to excess glycogen deposition. In the current study, long-term follow-up of previously described GSD IIIa dogs until 32 mo of age (n = 4) and of family-owned GSD IIIa dogs until 11 to 12 y of age (n = 2) revealed that elevated concentrations of liver and muscle enzyme (AST, ALT, ALP, and creatine phosphokinase) decreased over time, consistent with hepatic cirrhosis and muscle fibrosis. Glycogen deposition in many skeletal muscles; the tongue, diaphragm, and heart; and the phrenic and sciatic nerves occurred also. Furthermore, the urinary biomarker Glc4, which has been described in many types of GSD, was first elevated and then decreased later in life. This urinary biomarker demonstrated a similar trend as AST and ALT in GSD IIIa dogs, indicating that Glc4 might be a less invasive biomarker of hepatocellular disease. Finally, the current study further demonstrates that the canine GSD IIIa model adheres to the clinical course in human patients with this disorder and is an appropriate model for developing novel therapies. PMID:26884409

  18. Experimental galactosamine-induced hepatitis. Effect of anticoagulant and antifibrinolytic agents on microclot formation.

    PubMed Central

    Müller-Berghaus, G.; Reuter, C.; Bleyl, U.

    1976-01-01

    An experimental hepatitis was induced in rabbits by intravenous infusion of 1 g galactosamine per kilogram of body weight. Galactosamine administration caused microclot formation in kidneys, liver, lungs, and spleen in a low percentage. If, however, animals were infused with the fibrinolysis inhibitor epsilon-aminocaproic acid in addition to galactosamine, microclots were generated in a high percentage. The microclots exhibited typical staining characteristics like those observed in the generalized Shwartzman reaction. Some animals developed bilateral renal cortical necrosis. Heparin treatment prevented the occurrence of microclot fromation after galactosamine administration, but it neither prolonged the survival time of the animals nor prevented or reduced liver cell damage. Increases in serum GPT and bilirubin levels were similar in heparin-treated and untreated rabbits. The experiments indicate that disseminated intravascular coagulation is involved in galactosamine-induced hepatitis but does not contribute to the severity of the liver injury. Images Figure 1 Figure 2 Figure 3 PMID:1251892

  19. Herniation of Duodenum into the Right Ventral Hepatic Peritoneal Cavity with Groove Formation at the Ventral Hepatic Surface in a 2-Week-Old Chicken

    PubMed Central

    HARIDY, Mohie; SASAKI, Jun; GORYO, Masanobu

    2013-01-01

    ABSTRACT Internal hernia in avian species is very rare. A necropsy of a 2-week-old SPF White Leghorn chicken revealed that a loop of the duodenum and part of the pancreas (4 × 2 × 1 cm) was protruding through the abnormal foramen (2.5 cm in diameter) in the right posthepatic septum into the right ventral hepatic peritoneal cavity. The herniated loop was located underneath the ventral hepatic surface, leaving a groove on the right hepatic lobe (2 × 1.5 × 0.4 cm). The part of the pancreas involved in the hernia was grossly enlarged. Microscopically, a zone of pressure atrophy of hepatic tissue was characterized by crowdedness of hepatocytes with pyknotic nuclei and faint eosinophilic cytoplasm and indistinct narrow sinusoids. The pancreas revealed hypertrophy of the acinar cells with an increase in the secretory granules and basophilic cytoplasm. This is the first report of duodenum herniation into the right ventral hepatic peritoneal cavity resulting in groove formation on the ventral hepatic surface in a 2-week-old chicken. PMID:23759688

  20. Assignment of the gene encoding glycogen synthase (GYS) to human chromosome 19, band q13,3

    SciTech Connect

    Lehto, M. Helsinki Univ. ); Stoffel, M.; Espinosa, R. III; Beau, M.M. le; Bell, G.I. ); Groop, L. )

    1993-02-01

    The enzyme glycogen synthase (UDP glocose:glycogen 4-[alpha]-D-glucosyltransferase, EC 2.4.1.11) catalyzes the formation of glycogen from uridine diphosphate glucose (UPDG). Impaired activation of muscle glycogen synthase by insulin has been noted in patients with genetic risk of developing non-insulin-dependent diabets mellitus (NIDDM) and this may represent an early defect in the pathogenesis of this disorder. As such, glycogen synthase represents a candidate gene for contributing to genetic susceptibility. As a first step in studying the role of glycogen synthase in the genetics of NIDDM, we have isolated a cosmid encoding the human glycogen synthase gene (gene symbol GYS) and determined its chromosomal localization by fluorescence in situ hybridization. 4 refs., 1 fig.

  1. Dichloroacetate Stimulates Glycogen Accumulation in Primary Hepatocytes through an Insulin-Independent Mechanism

    SciTech Connect

    Lingohr, Melissa K.; Bull, Richard J.; Kato-Weinstein, Junko; Thrall, Brian D. )

    2002-01-01

    Dichloroacetate (DCA), a by-product of water chlorination, causes liver cancer in B6C3F1 mice. A hallmark response observed in mice exposed to carcinogenic doses of DCA is an accumulation of hepatic glycogen content. To distinguish whether the in vivo glycogenic effect of DCA was dependent on insulin and insulin signaling proteins, experiments were conducted in isolated hepatocytes where insulin concentrations could be controlled. In hepatocytes isolated from male B6C3F1 mice, DCA increased glycogen levels in a dose-related manner, independently of insulin. The accumulation of hepatocellular glycogen induced by DCA was not the result of decreased glycogenolysis, since DCA had no effect on the rate of glucagon-stimulated glycogen breakdown. Glycogen accumulation caused by DCA treatment was not hindered by inhibitors of extracellular-regulated protein kinase kinase (Erk1/2 kinase or MEK) or p70 kDa S6 protein kinase (p70(S6K)), but was completely blocked by the phosphatidylinositol 3-kinase (PI3K) inhibitors, LY294002 and wortmannin. Similarly, insulin-stimulated glycogen deposition was not influenced by the Erk1/2 kinase inhibitor, PD098509, or the p70(S6K) inhibitor, rapamycin. Unlike DCA-stimulated glycogen deposition, PI3K-inhibition only partially blocked the glycogenic effect of insulin. DCA did not cause phosphorylation of the downstream PI3K target protein, protein kinase B (PKB/Akt). The phosphorylation of PKB/Akt did not correlate to insulin-stimulated glycogenesis either. Similar to insulin, DCA in the medium decreased IR expression in isolated hepatocytes. The results indicate DCA increases hepatocellular glycogen accumulation through a PI3K-dependent mechanism that does not involve PKB/Akt and is, at least in part, different from the classical insulin-stimulated glycogenesis pathway. Somewhat surprisingly, insulin-stimulated glycogenesis also appears not to involve PKB/Akt in isolated murine hepatocytes.

  2. [Glycogen content in gerbil's liver following the spacecraft Foton-M3 mission].

    PubMed

    Atiakshin, D A; Bykov, E G; Il'in, E A; Pashkov, A N

    2009-01-01

    Glycogen cytochemistry and distribution in hepatocytes of the classic liver lobules were studied in three groups of gerbils Meriones unguiculatus: vivarium, synchronous control and flown in the 12-d Foton-M3 mission. The control animals were shown to have the central glycogen distribution with a large pool of polysaccharides found in hepatocytes of the pericentral and intermediate lobules and a small pool in the periportal area. Glycogen in hepatocyte plasm was within the physiological norm in the alpha- and beta-granules, typically localized on the cell periphery. Exposure to the spaceflight conditions decreased significantly glycogen concentrations in each functional region of the hepatic lobules and reduced the gradient of polysaccharide distribution from the portal triads toward the central vein. In parallel, high glycogen heterogeneity formed in adjacent hepatocytes and loci. The presence of glycosomes evidenced disturbance of carbohydrates metabolism. In addition, intracellular topography of glycogen granules in cytoplasm was altered. Trends of glycogen in gerbils of the synchronous control were similar to the space flown animals but much less pronounced.

  3. The experimental type 2 diabetes therapy glycogen phosphorylase inhibition can impair aerobic muscle function during prolonged contraction.

    PubMed

    Baker, David J; Greenhaff, Paul L; MacInnes, Alan; Timmons, James A

    2006-06-01

    Glycogen phosphorylase inhibition represents a promising strategy to suppress inappropriate hepatic glucose output, while muscle glycogen is a major source of fuel during contraction. Glycogen phosphorylase inhibitors (GPi) currently being investigated for the treatment of type 2 diabetes do not demonstrate hepatic versus muscle glycogen phosphorylase isoform selectivity and may therefore impair patient aerobic exercise capabilities. Skeletal muscle energy metabolism and function are not impaired by GPi during high-intensity contraction in rat skeletal muscle; however, it is unknown whether glycogen phosphorylase inhibitors would impair function during prolonged lower-intensity contraction. Utilizing a novel red cell-perfused rodent gastrocnemius-plantaris-soleus system, muscle was pretreated for 60 min with either 3 micromol/l free drug GPi (n=8) or vehicle control (n=7). During 60 min of aerobic contraction, GPi treatment resulted in approximately 35% greater fatigue. Muscle glycogen phosphorylase a form (P<0.01) and maximal activity (P<0.01) were reduced in the GPi group, and postcontraction glycogen (121.8 +/- 16.1 vs. 168.3 +/- 8.5 mmol/kg dry muscle, P<0.05) was greater. Furthermore, lower muscle lactate efflux and glucose uptake (P<0.01), yet higher muscle Vo(2), support the conclusion that carbohydrate utilization was impaired during contraction. Our data provide new confirmation that muscle glycogen plays an essential role during submaximal contraction. Given the critical role of exercise prescription in the treatment of type 2 diabetes, it will be important to monitor endurance capacity during the clinical evaluation of nonselective GPi. Alternatively, greater effort should be devoted toward the discovery of hepatic-selective GPi, hepatic-specific drug delivery strategies, and/or alternative strategies for controlling excess hepatic glucose production in type 2 diabetes.

  4. Effect of a hepatitis B virus inhibitor, NZ-4, on capsid formation.

    PubMed

    Yang, Li; Wang, Ya-Juan; Chen, Hai-Jun; Shi, Li-Ping; Tong, Xian-Kun; Zhang, Yang-Ming; Wang, Gui-Feng; Wang, Wen-Long; Feng, Chun-Lan; He, Pei-Lan; Xu, Yi-Bin; Lu, Meng-Ji; Tang, Wei; Nan, Fa-Jun; Zuo, Jian-Ping

    2016-01-01

    During the hepatitis B virus (HBV) life cycle, nucleocapsid assembly is essential for HBV replication. Both RNA reverse transcription and DNA replication occur within the HBV nucleocapsid. HBV nucleocapsid is consisted of core protein (HBcAg), whose carboxy-terminal domain (CTD) contains an Arg-rich domain (ARD). The ARD of HBcAg does contribute to the encapsidation of pregenomic RNA (pgRNA). Previously, we reported a small-molecule, NZ-4, which dramatically reduced the HBV DNA level in an in vitro cell setting. Here, we explore the possible mechanisms by which NZ-4 inhibits HBV function. As an HBV inhibitor, NZ-4 leads to the formation of genome-free capsids, including a new population of capsid that runs faster on agarose gels. NZ-4's activity was dependent on the presence of the ARD I, containing at least one positively charged amino acid. NZ-4 might provide a new option for further development of HBV therapeutics for the treatment of chronic hepatitis B.

  5. Liver glycogen bodies: ground-glass hepatocytes in transplanted patients.

    PubMed

    Bejarano, Pablo A; Garcia, Monica T; Rodriguez, Maria M; Ruiz, Phillip; Tzakis, Andreas G

    2006-11-01

    Ground-glass hepatocytes have been described in Lafora's disease, fibrinogen deposition, hepatitis B, type IV glycogenosis, and alcohol aversion (cyanamide) therapy. We encountered ground-glass hepatocytes with intracytoplasmic inclusions in four liver biopsies from three transplanted patients who had none of the above-mentioned underlying diseases. One patient was a 4-year-old boy who had a kidney transplant for severe ureterovesical reflux. Patient 2 was a 52-year-old man who had two liver transplants because of hepatitis C. The third patient was a 7-month-old girl who underwent a multivisceral transplant because of necrotizing enterocolitis and liver failure induced by total parenteral nutrition. The patients developed liver abnormalities from 45 days to 4 years after their transplants. The livers showed conspicuous ground-glass hepatocytes in 90% of the children's samples and 30% of the adult liver cells. The cytoplasmic bodies stained strongly for Gomori methenamine-silver; they were positive for periodic acid-Schiff without diastase, but negative after diastase digestion. They were negative for colloidal iron and hepatitis B core and surface antigens. Electron microscopy revealed non-membrane bound aggregates of glycogen. Idiopathic ground-glass hepatocytes occur in transplanted patients and represent accumulation of altered glycogen. However, their clinical significance and cause are not entirely elucidated.

  6. Hexokinase 2, Glycogen Synthase and Phosphorylase Play a Key Role in Muscle Glycogen Supercompensation

    PubMed Central

    Irimia, José M.; Rovira, Jordi; Nielsen, Jakob N.; Guerrero, Mario; Wojtaszewski, Jørgen F. P.; Cussó, Roser

    2012-01-01

    Background Glycogen-depleting exercise can lead to supercompensation of muscle glycogen stores, but the biochemical mechanisms of this phenomenon are still not completely understood. Methods Using chronic low-frequency stimulation (CLFS) as an exercise model, the tibialis anterior muscle of rabbits was stimulated for either 1 or 24 hours, inducing a reduction in glycogen of 90% and 50% respectively. Glycogen recovery was subsequently monitored during 24 hours of rest. Results In muscles stimulated for 1 hour, glycogen recovered basal levels during the rest period. However, in those stimulated for 24 hours, glycogen was supercompensated and its levels remained 50% higher than basal levels after 6 hours of rest, although the newly synthesized glycogen had fewer branches. This increase in glycogen correlated with an increase in hexokinase-2 expression and activity, a reduction in the glycogen phosphorylase activity ratio and an increase in the glycogen synthase activity ratio, due to dephosphorylation of site 3a, even in the presence of elevated glycogen stores. During supercompensation there was also an increase in 5′-AMP-activated protein kinase phosphorylation, correlating with a stable reduction in ATP and total purine nucleotide levels. Conclusions Glycogen supercompensation requires a coordinated chain of events at two levels in the context of decreased cell energy balance: First, an increase in the glucose phosphorylation capacity of the muscle and secondly, control of the enzymes directly involved in the synthesis and degradation of the glycogen molecule. However, supercompensated glycogen has fewer branches. PMID:22860128

  7. Multiple Glycogen-binding Sites in Eukaryotic Glycogen Synthase Are Required for High Catalytic Efficiency toward Glycogen

    SciTech Connect

    Baskaran, Sulochanadevi; Chikwana, Vimbai M.; Contreras, Christopher J.; Davis, Keri D.; Wilson, Wayne A.; DePaoli-Roach, Anna A.; Roach, Peter J.; Hurley, Thomas D.

    2012-12-10

    Glycogen synthase is a rate-limiting enzyme in the biosynthesis of glycogen and has an essential role in glucose homeostasis. The three-dimensional structures of yeast glycogen synthase (Gsy2p) complexed with maltooctaose identified four conserved maltodextrin-binding sites distributed across the surface of the enzyme. Site-1 is positioned on the N-terminal domain, site-2 and site-3 are present on the C-terminal domain, and site-4 is located in an interdomain cleft adjacent to the active site. Mutation of these surface sites decreased glycogen binding and catalytic efficiency toward glycogen. Mutations within site-1 and site-2 reduced the V{sub max}/S{sub 0.5} for glycogen by 40- and 70-fold, respectively. Combined mutation of site-1 and site-2 decreased the V{sub max}/S{sub 0.5} for glycogen by >3000-fold. Consistent with the in vitro data, glycogen accumulation in glycogen synthase-deficient yeast cells ({Delta}gsy1-gsy2) transformed with the site-1, site-2, combined site-1/site-2, or site-4 mutant form of Gsy2p was decreased by up to 40-fold. In contrast to the glycogen results, the ability to utilize maltooctaose as an in vitro substrate was unaffected in the site-2 mutant, moderately affected in the site-1 mutant, and almost completely abolished in the site-4 mutant. These data show that the ability to utilize maltooctaose as a substrate can be independent of the ability to utilize glycogen. Our data support the hypothesis that site-1 and site-2 provide a 'toehold mechanism,' keeping glycogen synthase tightly associated with the glycogen particle, whereas site-4 is more closely associated with positioning of the nonreducing end during catalysis.

  8. FGF2 mediates hepatic progenitor cell formation during human pluripotent stem cell differentiation by inducing the WNT antagonist NKD1

    PubMed Central

    Twaroski, Kirk; Mallanna, Sunil K.; Jing, Ran; DiFurio, Francesca; Urick, Amanda; Duncan, Stephen A.

    2015-01-01

    Fibroblast growth factors (FGFs) are required to specify hepatic fate within the definitive endoderm through activation of the FGF receptors (FGFRs). While the signaling pathways involved in hepatic specification are well understood, the mechanisms through which FGFs induce hepatic character within the endoderm are ill defined. Here we report the identification of genes whose expression is directly regulated by FGFR activity during the transition from endoderm to hepatic progenitor cell. The FGFR immediate early genes that were identified include those encoding transcription factors, growth factors, and signaling molecules. One of these immediate early genes encodes naked cuticle homolog 1 (NKD1), which is a repressor of canonical WNT (wingless-type MMTV integration site) signaling. We show that loss of NKD1 suppresses the formation of hepatic progenitor cells from human induced pluripotent stem cells and that this phenotype can be rescued by using a pharmacological antagonist of canonical WNT signaling. We conclude that FGF specifies hepatic fate at least in large part by inducing expression of NKD1 to transiently suppress the canonical WNT pathway. PMID:26637527

  9. Emerging Roles for Glycogen in the CNS

    PubMed Central

    Waitt, Alice E.; Reed, Liam; Ransom, Bruce R.; Brown, Angus M.

    2017-01-01

    The ability of glycogen, the depot into which excess glucose is stored in mammals, to act as a source of rapidly available energy substrate, has been exploited by several organs for both general and local advantage. The liver, expressing the highest concentration of glycogen maintains systemic normoglycemia ensuring the brain receives a supply of glucose in excess of demand. However the brain also contains glycogen, although its role is more specialized. Brain glycogen is located exclusively in astrocytes in the adult, with the exception of pathological conditions, thus in order to benefit neurons, and energy conduit (lactate) is trafficked inter-cellularly. Such a complex scheme requires cell type specific expression of a variety of metabolic enzymes and transporters. Glycogen supports neural elements during withdrawal of glucose, but once the limited buffer of glycogen is exhausted neural function fails and irreversible injury ensues. Under physiological conditions glycogen acts to provide supplemental substrates when ambient glucose is unable to support function during increased energy demand. Glycogen also supports learning and memory where it provides lactate to neurons during the conditioning phase of in vitro long-term potentiation (LTP), an experimental correlate of learning. Inhibiting the breakdown of glycogen or intercellular transport of lactate in in vivo rat models inhibits the retention of memory. Our current understanding of the importance of brain glycogen is expanding to encompass roles that are fundamental to higher brain function. PMID:28360839

  10. REVISITING GLYCOGEN CONTENT IN THE HUMAN BRAIN

    PubMed Central

    Öz, Gülin; DiNuzzo, Mauro; Kumar, Anjali; Moheet, Amir; Seaquist, Elizabeth R.

    2015-01-01

    Glycogen provides an important glucose reservoir in the brain since the concentration of glucosyl units stored in glycogen is several fold higher than free glucose available in brain tissue. We have previously reported 3–4 µmol/g brain glycogen content using in vivo 13C magnetic resonance spectroscopy (MRS) in conjunction with [1-13C]glucose administration in healthy humans, while higher levels were reported in the rodent brain. Due to the slow turnover of bulk brain glycogen in humans, complete turnover of the glycogen pool, estimated to take 3–5 days, was not observed in these prior studies. In an attempt to reach complete turnover and thereby steady state 13C labeling in glycogen, here we administered [1-13C]glucose to healthy volunteers for 80 hours. To eliminate any net glycogen synthesis during this period and thereby achieve an accurate estimate of glycogen concentration, volunteers were maintained at euglycemic blood glucose levels during [1-13C]glucose administration and 13C-glycogen levels in the occipital lobe were measured by 13C MRS approximately every 12 hours. Finally, we fitted the data with a biophysical model that was recently developed to take into account the tiered structure of the glycogen molecule and additionally incorporated blood glucose levels and isotopic enrichments as input function in the model. We obtained excellent fits of the model to the 13C-glycogen data, and glycogen content in the healthy human brain tissue was found to be 7.8 ± 0.3 µmol/g, a value substantially higher than previous estimates of glycogen content in the human brain. PMID:26202425

  11. Spheroid Formation and Evaluation of Hepatic Cells in a Three-Dimensional Culture Device.

    PubMed

    Miyamoto, Yoshitaka; Ikeuchi, Masashi; Noguchi, Hirofumi; Yagi, Tohru; Hayashi, Shuji

    2015-12-17

    In drug discovery, it is very important to evaluate liver cells within an organism. Compared to 2D culture methods, the development of 3D culture techniques for liver cells has been successful in maintaining long-term liver functionality with the formation of a hepatic-specific structure. The key to performing drug testing is the establishment of a stable in vitro evaluation system. In this article, we report a Tapered Stencil for Cluster Culture (TASCL) device developed to create liver spheroids in vitro. The TASCL device will be applied as a toxicity evaluation system for drug discovery. The TASCL device was created with an overall size of 10 mm × 10 mm, containing 400 microwells with a top aperture (500 µm × 500 µm) and a bottom aperture (300 µm diameter circular) per microwell. We evaluated the formation, recovery, and size of HepG2 spheroids in the TASCL device. The formation and recovery were both nearly 100%, and the size of the HepG2 spheroids increased with an increase in the initial cell seeding density. There were no significant differences in the sizes of the spheroids among the microwells. In addition, the HepG2 spheroids obtained using the TASCL device were alive and produced albumin. The morphology of the HepG2 spheroids was investigated using FE-SEM. The spheroids in the microwells exhibited perfectly spherical aggregation. In this report, by adjusting the size of the microwells of the TASCL device, uniform HepG2 spheroids were created, and the device facilitated more precise measurements of the liver function per HepG2 spheroid. Our TASCL device will be useful for application as a toxicity evaluation system for drug testing.

  12. Human Cathelicidin Compensates for the Role of Apolipoproteins in Hepatitis C Virus Infectious Particle Formation

    PubMed Central

    Puig-Basagoiti, Francesc; Fukuhara, Takasuke; Tamura, Tomokazu; Ono, Chikako; Uemura, Kentaro; Kawachi, Yukako; Yamamoto, Satomi; Mori, Hiroyuki; Kurihara, Takeshi; Okamoto, Toru; Aizaki, Hideki

    2016-01-01

    ABSTRACT Exchangeable apolipoproteins (ApoA, -C, and -E) have been shown to redundantly participate in the formation of infectious hepatitis C virus (HCV) particles during the assembly process, although their precise role in the viral life cycle is not well understood. Recently, it was shown that the exogenous expression of only short sequences containing amphipathic α-helices from various apolipoproteins is sufficient to restore the formation of infectious HCV particles in ApoB and ApoE double-gene-knockout Huh7 (BE-KO) cells. In this study, through the expression of a small library of human secretory proteins containing amphipathic α-helix structures, we identified the human cathelicidin antimicrobial peptide (CAMP), the only known member of the cathelicidin family of antimicrobial peptides (AMPs) in humans and expressed mainly in bone marrow and leukocytes. We showed that CAMP is able to rescue HCV infectious particle formation in BE-KO cells. In addition, we revealed that the LL-37 domain in CAMP containing amphipathic α-helices is crucial for the compensation of infectivity in BE-KO cells, and the expression of CAMP in nonhepatic 293T cells expressing claudin 1 and microRNA miR-122 confers complete propagation of HCV. These results suggest the possibility of extrahepatic propagation of HCV in cells with low-level or no expression of apolipoproteins but expressing secretory proteins containing amphipathic α-helices such as CAMP. IMPORTANCE Various exchangeable apolipoproteins play a pivotal role in the formation of infectious HCV during the assembly of viral particles, and amphipathic α-helix motifs in the apolipoproteins have been shown to be a key factor. To the best of our knowledge, we have identified for the first time the human cathelicidin CAMP as a cellular protein that can compensate for the role of apolipoproteins in the life cycle of HCV. We have also identified the domain in CAMP that contains amphipathic α-helices crucial for compensation and

  13. The Clinical Course of Glycogen Disease

    PubMed Central

    van Creveld, Simon

    1963-01-01

    The various types of glycogen disease, of which the author gave the first clinical description in 1928, that can at present be distinguished, are described in terms of the differing clinical and biochemical findings and the enzyme deficiencies more or less characteristic for each type. The clinical course of the author's first two patients with glycogen disease, at present 42 and 38 years old, is given in detail; they have type III of the disease. Some cases of glycogen disease cannot be fitted into the clinical classification of the different types, and for some no definite enzymatic defect to account for the glycogen accumulation has been found. The therapy of glycogen disease is discussed briefly. ImagesFig. 1aFig. 1bFig. 2Fig. 8 PMID:14023832

  14. Brain glycogen supercompensation following exhaustive exercise.

    PubMed

    Matsui, Takashi; Ishikawa, Taro; Ito, Hitoshi; Okamoto, Masahiro; Inoue, Koshiro; Lee, Min-Chul; Fujikawa, Takahiko; Ichitani, Yukio; Kawanaka, Kentaro; Soya, Hideaki

    2012-02-01

    Brain glycogen localized in astrocytes, a critical energy source for neurons, decreases during prolonged exhaustive exercise with hypoglycaemia. However, it is uncertain whether exhaustive exercise induces glycogen supercompensation in the brain as in skeletal muscle. To explore this question, we exercised adult male rats to exhaustion at moderate intensity (20 m min(-1)) by treadmill, and quantified glycogen levels in several brain loci and skeletal muscles using a high-power (10 kW) microwave irradiation method as a gold standard. Skeletal muscle glycogen was depleted by 82-90% with exhaustive exercise, and supercompensated by 43-46% at 24 h after exercise. Brain glycogen levels decreased by 50-64% with exhaustive exercise, and supercompensated by 29-63% (whole brain 46%, cortex 60%, hippocampus 33%, hypothalamus 29%, cerebellum 63% and brainstem 49%) at 6 h after exercise. The brain glycogen supercompensation rates after exercise positively correlated with their decrease rates during exercise. We also observed that cortical and hippocampal glycogen supercompensation were sustained until 24 h after exercise (long-lasting supercompensation), and their basal glycogen levels increased with 4 weeks of exercise training (60 min day(-1) at 20 m min(-1)). These results support the hypothesis that, like the effect in skeletal muscles, glycogen supercompensation also occurs in the brain following exhaustive exercise, and the extent of supercompensation is dependent on that of glycogen decrease during exercise across brain regions. However, supercompensation in the brain preceded that of skeletal muscles. Further, the long-lasting supercompensation of the cortex and hippocampus is probably a prerequisite for their training adaptation (increased basal levels), probably to meet the increased energy demands of the brain in exercising animals.

  15. Rat skeletal muscle glycogen degradation pathways reveal differential association of glycogen-related proteins with glycogen granules.

    PubMed

    Xu, Hongyang; Stapleton, David; Murphy, Robyn M

    2015-06-01

    Glycogenin, glycogen-debranching enzyme (GDE) and glycogen phosphorylase (GP) are important enzymes that contribute to glycogen particle metabolism. In Long-Evans Hooded rat whole muscle homogenates prepared from extensor digitorum longus (EDL, fast-twitch) and soleus (SOL, oxidative, predominantly slow twitch), it was necessary to include α-amylase, which releases glucosyl units from glycogen, to detect glycogenin but not GDE or GP. Up to ∼12 % of intramuscular glycogen pool was broken down using either in vitro electrical stimulation or leaving muscle at room temperature >3 h (delayed, post-mortem). Electrical stimulation did not reveal glycogenin unless α-amylase was added, although in post-mortem muscle ∼50 and ∼30 % of glycogenin in EDL and SOL muscles, respectively, was detected compared to the amount detected with α-amylase treatment. Single muscle fibres were dissected from fresh or post-mortem EDL muscles, mechanically skinned to remove surface membrane and the presence of glycogenin, GDE and GP as freely diffusible proteins (i.e. cytoplasmic localization) compared by Western blotting. Diffusibility of glycogenin (∼20 %) and GP (∼60 %) was not different between muscles, although GDE increased from ∼15 % diffusible in fresh muscle to ∼60 % in post-mortem muscle. Under physiologically relevant circumstances, in rat muscle and within detection limits: (1) The total cellular pool of glycogenin is always associated with glycogen granules, (2) GDE is associated with glycogen granules with over half the total pool associated with the outer tiers of glycogen, (3) GP is only ever weakly associated with glycogen granules and (4) addition of α-amylase is necessary in order to detect glycogenin, but not GDE or GP.

  16. Glycogen metabolism in the rat retina.

    PubMed

    Coffe, Víctor; Carbajal, Raymundo C; Salceda, Rocío

    2004-02-01

    It has been reported that glycogen levels in retina vary with retinal vascularization. However, the electrical activity of isolated retina depends on glucose supply, suggesting that it does not contain energetic reserves. We determined glycogen levels and pyruvate and lactate production under various conditions in isolated retina. Ex vivo retinas from light- and dark-adapted rats showed values of 44 +/- 0.3 and 19.5 +/- 0.4 nmol glucosyl residues/mg protein, respectively. The glycogen content of retinas from light-adapted animals was reduced by 50% when they were transferred to darkness. Glycogen levels were low in retinas incubated in glucose-free media and increased in the presence of glucose. The highest glycogen values were found in media containing 20 mm of glucose. A rapid increase in lactate production was observed in the presence of glucose. Surprisingly, glycogen levels were the lowest and lactate production was also very low in the presence of 30 mm glucose. Our results suggest that glycogen can be used as an immediate accessible energy reserve in retina. We speculate on the possibility that gluconeogenesis may play a protective role by removal of lactic acid.

  17. CHARACTERIZATION OF HYDROQUINONE AND CATECHOL FORMATION USING HEPATIC MICROSOMES FROM THREE SPECIES OF FISH

    EPA Science Inventory

    The in vitro metabolism of phenol at 11 degrees C has been studied using juvenile and immature adult rainbow (Orcorhynchus mykiss), immature adult brook (Salvelinus fontinalis), and immature adult lake trout (Salvelinus namacush) hepatic microsomal preparations.

  18. Glucose-induced glycogenesis in the liver involves the glucose-6-phosphate-dependent dephosphorylation of glycogen synthase.

    PubMed Central

    Cadefau, J; Bollen, M; Stalmans, W

    1997-01-01

    Non-metabolized glucose derivatives may cause inactivation of phosphorylase but, unlike glucose, they are unable to elicit activation of glycogen synthase in isolated hepatocytes. We report here that, after the previous inactivation of phosphorylase by one of these glucose derivatives (2-deoxy-2-fluoro-alpha-glucosyl fluoride), glycogen synthase was progressively activated by addition of increasing concentrations of glucose. Under these conditions, the degree of activation of glycogen synthase was linearly correlated with the intracellular glucose-6-phosphate (Glc-6-P) concentration. Addition of glucosamine, an inhibitor of glucokinase, decreased both parameters in parallel. Further experiments using an inhibitor of either protein kinases (5-iodotubercidin) or protein phosphatases (microcystin) in isolated hepatocytes indicated that Glc-6-P does not affect glycogen-synthase kinase activity but enhances the glycogen-synthase phosphatase reaction. Experiments in vitro showed that the synthase phosphatase activity of glycogen-bound type-1 protein phosphatase was increased by physiological concentrations of Glc-6-P (0.1-0.5 mM), but not by 2.5 mM fructose-6-P, fructose-1-P or glucose-1-P. At physiological ionic strength, the glycogen-associated synthase phosphatase activity was nearly entirely Glc-6-P-dependent, but Glc-6-P did not relieve the strong inhibitory effect of phosphorylase a. The large stimulatory effects of 2.5 mM Glc-6-P, with glycogen synthase b and phosphorylase a as substrates, appeared to be mostly substrate-directed, while the modest effects observed with casein and histone IIA pointed to an additional stimulation of glycogen-bound protein phosphatase-1 by Glc-6-P. We conclude that glucose elicits hepatic synthase phosphatase activity both by removal of the inhibitor, phosphorylase a, and by generation of the stimulator, Glc-6-P. PMID:9148744

  19. Glucose-induced glycogenesis in the liver involves the glucose-6-phosphate-dependent dephosphorylation of glycogen synthase.

    PubMed

    Cadefau, J; Bollen, M; Stalmans, W

    1997-03-15

    Non-metabolized glucose derivatives may cause inactivation of phosphorylase but, unlike glucose, they are unable to elicit activation of glycogen synthase in isolated hepatocytes. We report here that, after the previous inactivation of phosphorylase by one of these glucose derivatives (2-deoxy-2-fluoro-alpha-glucosyl fluoride), glycogen synthase was progressively activated by addition of increasing concentrations of glucose. Under these conditions, the degree of activation of glycogen synthase was linearly correlated with the intracellular glucose-6-phosphate (Glc-6-P) concentration. Addition of glucosamine, an inhibitor of glucokinase, decreased both parameters in parallel. Further experiments using an inhibitor of either protein kinases (5-iodotubercidin) or protein phosphatases (microcystin) in isolated hepatocytes indicated that Glc-6-P does not affect glycogen-synthase kinase activity but enhances the glycogen-synthase phosphatase reaction. Experiments in vitro showed that the synthase phosphatase activity of glycogen-bound type-1 protein phosphatase was increased by physiological concentrations of Glc-6-P (0.1-0.5 mM), but not by 2.5 mM fructose-6-P, fructose-1-P or glucose-1-P. At physiological ionic strength, the glycogen-associated synthase phosphatase activity was nearly entirely Glc-6-P-dependent, but Glc-6-P did not relieve the strong inhibitory effect of phosphorylase a. The large stimulatory effects of 2.5 mM Glc-6-P, with glycogen synthase b and phosphorylase a as substrates, appeared to be mostly substrate-directed, while the modest effects observed with casein and histone IIA pointed to an additional stimulation of glycogen-bound protein phosphatase-1 by Glc-6-P. We conclude that glucose elicits hepatic synthase phosphatase activity both by removal of the inhibitor, phosphorylase a, and by generation of the stimulator, Glc-6-P.

  20. Activation of glycolysis and apoptosis in glycogen storage disease type Ia.

    PubMed

    Sun, Baodong; Li, Songtao; Yang, Liu; Damodaran, Tirupapuliyur; Desai, Dev; Diehl, Anna Mae; Alzate, Oscar; Koeberl, Dwight D

    2009-08-01

    The deficiency of glucose-6-phosphatase (G6Pase) underlies glycogen storage disease type Ia (GSD-Ia, von Gierke disease; MIM 232200), an autosomal recessive disorder of metabolism associated with life-threatening hypoglycemia, growth retardation, renal failure, hepatic adenomas, and hepatocellular carcinoma. Liver involvement includes the massive accumulation of glycogen and lipids due to accumulated glucose-6-phosphate and glycolytic intermediates. Proteomic analysis revealed elevations in glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and other enzymes involved in glycolysis. GAPDH was markedly increased in murine G6Pase-deficient hepatocytes. The moonlighting role of GAPDH includes increasing apoptosis, which was demonstrated by increased TUNEL assay positivity and caspase 3 activation in the murine GSD-Ia liver. These analyses of hepatic involvement in GSD-Ia mice have implicated the induction of apoptosis in the pathobiology of GSD-Ia.

  1. Role of the direct and indirect pathways for glycogen synthesis in rat liver in the postprandial state

    SciTech Connect

    Huang, M.T.; Veech, R.L.

    1988-03-01

    The pathway for hepatic glycogen synthesis in the postprandial state was studied in meal-fed rats chronically cannulated in the portal vein. Plasma glucose concentration in the portal vein was found to be 4.50 +/- 1.01 mM (mean +/- SE; n = 3) before a meal and 11.54 +/- 0.70 mM (mean +/- SE; n = 4) after a meal in rats meal-fed a diet consisting of 100% commercial rat chow for 7 d. The hepatic-portal difference of plasma glucose concentration showed that liver released glucose in the fasted state and either extracted or released glucose after feeding depending on plasma glucose concentration in the portal vein. The concentration of portal vein glucose at which liver changes from glucose releasing to glucose uptake was 8 mM, the Km of glucokinase. The rate of glycogen synthesis in liver during meal-feeding was found to be approximately 1 mumol glucosyl U/g wet wt/min in rats meal-fed a 50% glucose supplemented chow diet. The relative importance of the direct vs. indirect pathway for the replenishment of hepatic glycogen was determined by the incorporation of (3-/sup 3/H,U-/sup 14/C)glucose into liver glycogen. Labeled glucose was injected into the portal vein at the end of meal-feeding. The ratio of /sup 3/H//sup 14/C in the glucosyl units of glycogen was found to be 83-92% of the ratio in liver free glucose six minutes after the injection, indicating that the majority of exogenous glucose incorporated into glycogen did not go through glycolysis. The percent contribution of the direct versus indirect pathway was quantitated from the difference in the relative specific activity (RSA) of (/sup 3/H) and (/sup 14/C)-glycogen in rats infused with (3-/sup 3/H,U-/sup 14/C)glucose. No significant difference was found between the RSA of (/sup 3/H)glycogen and (/sup 14/C)glycogen, indicating further that the pathway for glycogen synthesis in liver from exogenous glucose is from the direct pathway.

  2. Roles of poly-3-hydroxybutyrate (PHB) and glycogen in symbiosis of Sinorhizobium meliloti with Medicago sp.

    PubMed

    Wang, Chunxia; Saldanha, Marsha; Sheng, Xiaoyan; Shelswell, Kristopher J; Walsh, Keith T; Sobral, Bruno W S; Charles, Trevor C

    2007-02-01

    Poly-3-hydroxybutyrate (PHB) and glycogen are major carbon storage compounds in Sinorhizobium meliloti. The roles of PHB and glycogen in rhizobia-legume symbiosis are not fully understood. Glycogen synthase mutations were constructed by in-frame deletion (glgA1) or insertion (glgA2). These mutations were combined with a phbC mutation to make all combinations of double and triple mutants. PHB was not detectable in any of the mutants containing the phbC mutation; glycogen was not detectable in any of the mutants containing the glgA1 mutation. PHB levels were significantly lower in the glgA1 mutant, while glycogen levels were increased in the phbC mutant. Exopolysaccharide (EPS) was not detected in any of the phbC mutants, while the glgA1 and glgA2 mutants produced levels of EPS similar to the wild-type. Symbiotic properties of these strains were investigated on Medicago truncatula and Medicago sativa. The results indicated that the strains unable to synthesize PHB, or glycogen, were still able to form nodules and fix nitrogen. However, phbC mutations caused greater nodule formation delay on M. truncatula than on M. sativa. Time-course studies showed that (1) the ability to synthesize PHB is important for N(2) fixation in M. truncatula nodules and younger M. sativa nodules, and (2) the blocking of glycogen synthesis resulted in lower levels of N(2) fixation on M. truncatula and older nodules on M. sativa. These data have important implications for understanding how PHB and glycogen function in the interactions of S. meliloti with Medicago spp.

  3. Hypoxia Promotes Glycogen Accumulation through Hypoxia Inducible Factor (HIF)-Mediated Induction of Glycogen Synthase 1

    PubMed Central

    Pescador, Nuria; Garcia-Rocha, Mar; Ortiz-Barahona, Amaya; Vazquez, Silvia; Ordoñez, Angel; Cuevas, Yolanda; Saez-Morales, David; Garcia-Bermejo, Maria Laura; Landazuri, Manuel O.; Guinovart, Joan; del Peso, Luis

    2010-01-01

    When oxygen becomes limiting, cells reduce mitochondrial respiration and increase ATP production through anaerobic fermentation of glucose. The Hypoxia Inducible Factors (HIFs) play a key role in this metabolic shift by regulating the transcription of key enzymes of glucose metabolism. Here we show that oxygen regulates the expression of the muscle glycogen synthase (GYS1). Hypoxic GYS1 induction requires HIF activity and a Hypoxia Response Element within its promoter. GYS1 gene induction correlated with a significant increase in glycogen synthase activity and glycogen accumulation in cells exposed to hypoxia. Significantly, knockdown of either HIF1α or GYS1 attenuated hypoxia-induced glycogen accumulation, while GYS1 overexpression was sufficient to mimic this effect. Altogether, these results indicate that GYS1 regulation by HIF plays a central role in the hypoxic accumulation of glycogen. Importantly, we found that hypoxia also upregulates the expression of UTP:glucose-1-phosphate urydylyltransferase (UGP2) and 1,4-α glucan branching enzyme (GBE1), two enzymes involved in the biosynthesis of glycogen. Therefore, hypoxia regulates almost all the enzymes involved in glycogen metabolism in a coordinated fashion, leading to its accumulation. Finally, we demonstrated that abrogation of glycogen synthesis, by knock-down of GYS1 expression, impairs hypoxic preconditioning, suggesting a physiological role for the glycogen accumulated during chronic hypoxia. In summary, our results uncover a novel effect of hypoxia on glucose metabolism, further supporting the central importance of metabolic reprogramming in the cellular adaptation to hypoxia. PMID:20300197

  4. High liver glycogen in hereditary fructose intolerance.

    PubMed

    Cain, A R; Ryman, B E

    1971-11-01

    A case of hereditary fructose intolerance is reported in a girl aged 2 years at the time of her death. She had apparently progressed normally until the age of 14 months. At 19 months she was admitted to hospital with failure to thrive, hepatomegaly, and superficial infections. Investigations revealed hypoglycaemia, persistent acidosis, aminoaciduria, and a high liver glycogen level which suggested that she had glycogen storage disease. There was also some evidence of malabsorption. At necropsy the liver enzyme estimations showed that fructose 1-phosphate aldolase activity was absent and that fructose 1,6-diphosphate aldolase activity was reduced. Hereditary fructose intolerance and glycogen storage disease have been confused in the past on clinical grounds, but a high liver glycogen level has not previously been reported in hereditary fructose intolerance.

  5. Alglucosidase alfa treatment alleviates liver disease in a mouse model of glycogen storage disease type IV.

    PubMed

    Yi, Haiqing; Gao, Fengqin; Austin, Stephanie; Kishnani, Priya S; Sun, Baodong

    2016-12-01

    Patients with progressive hepatic form of GSD IV often die of liver failure in early childhood. We tested the feasibility of using recombinant human acid-α glucosidase (rhGAA) for treating GSD IV. Weekly intravenously injection of rhGAA at 40 mg/kg for 4 weeks significantly reduced hepatic glycogen accumulation, lowered liver/body weight ratio, and reduced plasma ALP and ALT activities in GSD IV mice. Our data suggests that rhGAA is a potential therapy for GSD IV.

  6. Impairment of Liver Glycogen Storage in the db/db Animal Model of Type 2 Diabetes: A Potential Target for Future Therapeutics?

    PubMed

    Sullivan, Mitchell A; Harcourt, Brooke E; Xu, Ping; Forbes, Josephine M; Gilbert, Robert G

    2015-01-01

    After the discovery of the db gene in 1966, it was determined that a blood-borne satiety factor was produced excessively, but was not responded to, in db/db mice. This model for type 2 diabetes is widely used since it phenocopies human disease and its co-morbidities including obesity, progressive deterioration in glucose tolerance, hypertension and hyperlipidaemia. Db/db mice, unlike their non-diabetic controls, have consistently elevated levels of liver glycogen, most likely due to hyperphagia. In transmission electron micrographs, liver glycogen usually shows a composite cauliflower-like morphology of large "α particles" (with a wide range of sizes) made up of smaller "β particles" bound together. New studies have explored the size distribution of liver glycogen molecules and found that α particles in db/db mice are more chemically fragile than those in healthy mice, and can readily break apart to smaller β particles. There is evidence that smaller glycogen particles have a higher association with glycogen phosphorylase, a key enzyme involved in glycogen degradation, as well as being degraded more rapidly in vitro; therefore the inability to form stable large glycogen α particles is predicted to result in a faster, less controlled degradation into glucose. The implications of this for glycaemic control remain to be fully elucidated. However, "rescuing" the more fragile diabetic glycogen to decrease hepatic glucose output in type 2 diabetes, may provide a potential therapeutic target which is the subject of this review.

  7. Oligosaccharide Binding in Escherichia coli Glycogen Synthase

    SciTech Connect

    Sheng, Fang; Yep, Alejandra; Feng, Lei; Preiss, Jack; Geiger, James H.

    2010-11-17

    Glycogen/starch synthase elongates glucan chains and is the key enzyme in the synthesis of glycogen in bacteria and starch in plants. Cocrystallization of Escherichia coli wild-type glycogen synthase (GS) with substrate ADPGlc and the glucan acceptor mimic HEPPSO produced a closed form of GS and suggests that domain-domain closure accompanies glycogen synthesis. Cocrystallization of the inactive GS mutant E377A with substrate ADPGlc and oligosaccharide results in the first oligosaccharide-bound glycogen synthase structure. Four bound oligosaccharides are observed, one in the interdomain cleft (G6a) and three on the N-terminal domain surface (G6b, G6c, and G6d). Extending from the center of the enzyme to the interdomain cleft opening, G6a mostly interacts with the highly conserved N-terminal domain residues lining the cleft of GS. The surface-bound oligosaccharides G6c and G6d have less interaction with enzyme and exhibit a more curled, helixlike structural arrangement. The observation that oligosaccharides bind only to the N-terminal domain of GS suggests that glycogen in vivo probably binds to only one side of the enzyme to ensure unencumbered interdomain movement, which is required for efficient, continuous glucan-chain synthesis.

  8. Characterization of the highly branched glycogen from the thermoacidophilic red microalga Galdieria sulphuraria and comparison with other glycogens.

    PubMed

    Martinez-Garcia, Marta; Stuart, Marc C A; van der Maarel, Marc J E C

    2016-08-01

    The thermoacidophilic red microalga Galdieria sulphuraria synthesizes glycogen when growing under heterotrophic conditions. Structural characterization revealed that G. sulphuraria glycogen is the most highly branched glycogen described to date, with 18% of α-(1→6) linkages. Moreover, it differs from other glycogens because it is composed of short chains only and has a substantially smaller molecular weight and particle size. The physiological role of this highly branched glycogen in G. sulphuraria is discussed.

  9. Polyprotein-Driven Formation of Two Interdependent Sets of Complexes Supporting Hepatitis C Virus Genome Replication

    PubMed Central

    Gomes, Rafael G. B.; Isken, Olaf; Tautz, Norbert; McLauchlan, John

    2015-01-01

    ABSTRACT Hepatitis C virus (HCV) requires proteins from the NS3-NS5B polyprotein to create a replicase unit for replication of its genome. The replicase proteins form membranous compartments in cells to facilitate replication, but little is known about their functional organization within these structures. We recently reported on intragenomic replicons, bicistronic viral transcripts expressing an authentic replicase from open reading frame 2 (ORF2) and a second duplicate nonstructural (NS) polyprotein from ORF1. Using these constructs and other methods, we have assessed the polyprotein requirements for rescue of different lethal point mutations across NS3-5B. Mutations readily tractable to rescue broadly fell into two groupings: those requiring expression of a minimum NS3-5A and those requiring expression of a minimum NS3-5B polyprotein. A cis-acting mutation that blocked NS3 helicase activity, T1299A, was tolerated when introduced into either ORF within the intragenomic replicon, but unlike many other mutations required the other ORF to express a functional NS3-5B. Three mutations were identified as more refractile to rescue: one that blocked cleavage of the NS4B5A boundary (S1977P), another in the NS3 helicase (K1240N), and a third in NS4A (V1665G). Introduced into ORF1, these exhibited a dominant negative phenotype, but with K1240N inhibiting replication as a minimum NS3-5A polyprotein whereas V1665G and S1977P only impaired replication as a NS3-5B polyprotein. Furthermore, an S1977P-mutated NS3-5A polyprotein complemented other defects shown to be dependent on NS3-5A for rescue. Overall, our findings suggest the existence of two interdependent sets of protein complexes supporting RNA replication, distinguishable by the minimum polyprotein requirement needed for their formation. IMPORTANCE Positive-strand RNA viruses reshape the intracellular membranes of cells to form a compartment within which to replicate their genome, but little is known about the functional

  10. Epithelial-mesenchymal transition delayed by E-cad to promote tissue formation in hepatic differentiation of mouse embryonic stem cells in vitro.

    PubMed

    Hu, Anbin; Shang, Changzhen; Li, Qiang; Sun, Nianfeng; Wu, Linwei; Ma, Yi; Jiao, Xingyuan; Min, Jun; Zeng, Gucheng; He, Xiaoshun

    2014-04-15

    Hepatic differentiation of embryonic stem cells (ESCs) usually results in a single cell lineage, and the formation of liver tissues remains difficult. Here, we examine the role of epithelial-mesenchymal transition (EMT) that is regulated by epithelial cadherin (E-cad) expression in hepatic tissue formation from ESCs. E-cad was transfected into mouse ESCs to enable a stable expression of E-cad. Hepatic differentiation of ESCs was then induced by hepatic growth factors. Wnt/β-catenin signaling and EMT speed were examined to determine the differentiation process. Hepatic and angiogenesis markers, as well as differentiated cell-adhesive force were also examined to identify the hepatic tissue differentiation. In our results, E-cad expression gradually decreased in normal ESC (N-ESC) differentiation, but remained stable in the E-cad transfected ESC (EC-ESC) group. In EC-ESC differentiation, expressions of cytoplastic β-catenin and EMT were much lower and significantly prolonged. Angiogenesis markers vascular endothelial growth factor receptor-1 (VEGFR-1) and CD31/PECAM-1 were expressed only on day 5-13 in N-ESC differentiation, whereas VEGFR-1 and CD31/PECAM-1 were expressed prolonged on day 5-17 in the EC-ESC group and were coincident with the expression of hepatic markers. Finally, EC-ESC differentiation maintained multilayer-growth patterns, and abundant vascular network structures appeared and migrated in albumin-positive cell areas. The cellular adhesion forces between embryonic body cells in EC-ESC differentiation during day 13-17 were similar to those of mouse liver tissue. In conclusion, accelerated EMT due to the decreased E-cad expression may partially contribute to the failure of hepatic tissue formation in N-ESC differentiation. E-cad can act in synergy with hepatic growth factors and facilitate the early-stage formation of hepatic tissues through down-regulating Wnt/β-catenin signaling and delaying EMT. This work provides a new insight into hepatic tissue

  11. The antidiabetic agent sodium tungstate activates glycogen synthesis through an insulin receptor-independent pathway.

    PubMed

    Domínguez, Jorge E; Muñoz, M Carmen; Zafra, Delia; Sanchez-Perez, Isabel; Baqué, Susanna; Caron, Martine; Mercurio, Ciro; Barberà, Albert; Perona, Rosario; Gomis, Ramon; Guinovart, Joan J

    2003-10-31

    Sodium tungstate is a powerful antidiabetic agent when administered orally. In primary cultured hepatocytes, tungstate showed insulin-like actions, which led to an increase in glycogen synthesis and accumulation. However, this compound did not significantly alter the insulin receptor activation state or dephosphorylation rate in cultured cells (CHO-R) or in primary hepatocytes, in either short or long term treatments. In contrast, at low concentrations, tungstate induced a transient strong activation of extracellular signal-regulated kinases 1 and 2 (ERK1/2) after 5-10 min of treatment, in a similar way to insulin. Moreover, this compound did not significantly delay or inhibit the dephosphorylation of ERK1/2. ERK1/2 activation triggered a cascade of downstream events, which included the phosphorylation of p90rsk and glycogen synthase-kinase 3beta. Experiments with a specific inhibitor of ERK1/2 activation and kinase assays indicate that these proteins were directly involved in the stimulation of glycogen synthase and glycogen synthesis induced by tungstate without a direct involvement of protein kinase B (PKB/Akt). These results show a direct involvement of ERK1/2 in the mechanism of action of tungstate at the hepatic level.

  12. [Glycogen metabolism in the cranial cervical ganglion of the cat sympathetic trunk during decentralization and reparative regeneration].

    PubMed

    Greten, A G; Sokolova, G A

    1982-07-01

    The character of glycogen metabolism disorders has been studied in the cranial cervical ganglion of the cat sympathetic trunk after the latter has been cut 1.5 cm caudally the ganglion. As the innervational connections are establishing, the glycogen metabolism is normalizing, but even after 2 months the initial level is not restored. Glycogen is proved to be one of the most sensitive tests to the lesion. In various time after cutting, the glycogen metabolism has certain specific peculiarities both in the neural cell bodies, and in the synapses. The wavy character of the glycogen-synthesizing process in the neural elements is demonstrated, with anaerobic glycolysis taking a large part in it. Certain connections with the higher centers are necessary not only for glycogen metabolism as energy resources, but to ensure a regular synthesis, particularly that of enzymes, in the neurons and synapses. The peculiarities of glycogen-synthesizing properties in the synaptic formations, after the connection with the center is broken, are closely connected with the notion on autonomity in the synaptic structures activity.

  13. Variation in glycogen concentrations within mantle and foot tissue in Amblema plicata plicata: Implications for tissue biopsy sampling

    USGS Publications Warehouse

    Naimo, T.J.; Monroe, E.M.

    1999-01-01

    With the development of techniques to non-lethally biopsy tissue from unionids, a new method is available to measure changes in biochemical, contaminant, and genetic constituents in this imperiled faunal group. However, before its widespread application, information on the variability of biochemical components within and among tissues needs to be evaluated. We measured glycogen concentrations in foot and mantle tissue in Amblema plicata plicata (Say, 1817) to determine if glycogen was evenly distributed within and between tissues and to determine which tissue might be more responsive to the stress associated with relocating mussels. Glycogen was measured in two groups of mussels: those sampled from their native environment (undisturbed mussels) and quickly frozen for analysis and those relocated into an artificial pond (relocated mussels) for 24 months before analysis. In both undisturbed and relocated mussels, glycogen concentrations were evenly distributed within foot, but not within mantle tissue. In mantle tissue, concentrations of glycogen varied about 2-fold among sections. In addition, glycogen varied significantly between tissues in undisturbed mussels, but not in relocated mussels. Twenty-four months after relocation, glycogen concentrations had declined by 80% in mantle tissue and by 56% in foot tissue relative to the undisturbed mussels. These data indicate that representative biopsy samples can be obtained from foot tissue, but not mantle tissue. We hypothesize that mantle tissue could be more responsive to the stress of relocation due to its high metabolic activity associated with shell formation.

  14. Hepatitis B virus HBx protein activates Ras-GTP complex formation and establishes a Ras, Raf, MAP kinase signaling cascade.

    PubMed Central

    Benn, J; Schneider, R J

    1994-01-01

    Hepatitis B virus produces a small (154-amino acid) transcriptional transactivating protein, HBx, which is required for viral infection and has been implicated in virus-mediated liver oncogenesis. However, the molecular mechanism for HBx activity and its possible influence on cell proliferation have remained obscure. A number of studies suggest that HBx may stimulate transcription by indirectly activating transcription factors, possibly by influencing cell signaling pathways. We now present biochemical evidence that HBx activates Ras and rapidly induces a cytoplasmic signaling cascade linking Ras, Raf, and mitogen-activated protein kinase (MAP kinase), leading to transcriptional transactivation. HBx strongly elevates levels of GTP-bound Ras, activated and phosphorylated Raf, and tyrosine-phosphorylated and activated MAP kinase. Transactivation of transcription factor AP-1 by HBx is blocked by inhibition of Ras or Raf activities but not by inhibition of Ca(2+)- and diacylglycerol-dependent protein kinase C. HBx was also found to stimulate DNA synthesis in serum-starved cells. The hepatitis B virus HBx protein therefore stimulates Ras-GTP complex formation and promotes downstream signaling through Raf and MAP kinases, and may influence cell proliferation. Images PMID:7937954

  15. Cell Fusion Reprogramming Leads to a Specific Hepatic Expression Pattern during Mouse Bone Marrow Derived Hepatocyte Formation In Vivo

    PubMed Central

    Arza, Elvira; Alvarez-Barrientos, Alberto; Fabregat, Isabel; Garcia-Bravo, Maria; Meza, Nestor W.; Segovia, Jose C.

    2012-01-01

    The fusion of bone marrow (BM) hematopoietic cells with hepatocytes to generate BM derived hepatocytes (BMDH) is a natural process, which is enhanced in damaged tissues. However, the reprogramming needed to generate BMDH and the identity of the resultant cells is essentially unknown. In a mouse model of chronic liver damage, here we identify a modification in the chromatin structure of the hematopoietic nucleus during BMDH formation, accompanied by the loss of the key hematopoietic transcription factor PU.1/Sfpi1 (SFFV proviral integration 1) and gain of the key hepatic transcriptional regulator HNF-1A homeobox A (HNF-1A/Hnf1a). Through genome-wide expression analysis of laser captured BMDH, a differential gene expression pattern was detected and the chromatin changes observed were confirmed at the level of chromatin regulator genes. Similarly, Tranforming Growth Factor-β1 (TGF-β1) and neurotransmitter (e.g. Prostaglandin E Receptor 4 [Ptger4]) pathway genes were over-expressed. In summary, in vivo BMDH generation is a process in which the hematopoietic cell nucleus changes its identity and acquires hepatic features. These BMDHs have their own cell identity characterized by an expression pattern different from hematopoietic cells or hepatocytes. The role of these BMDHs in the liver requires further investigation. PMID:22457803

  16. Effect of diabetes on glycogen metabolism in rat retina.

    PubMed

    Sánchez-Chávez, Gustavo; Hernández-Berrones, Jethro; Luna-Ulloa, Luis Bernardo; Coffe, Víctor; Salceda, Rocío

    2008-07-01

    Glucose is the main fuel for energy metabolism in retina. The regulatory mechanisms that maintain glucose homeostasis in retina could include hormonal action. Retinopathy is one of the chemical manifestations of long-standing diabetes mellitus. In order to better understand the effect of hyperglycemia in retina, we studied glycogen content as well as glycogen synthase and phosphorylase activities in both normal and streptozotocin-induced diabetic rat retina and compared them with other tissues. Glycogen levels in normal rat retina are low (46 +/- 4.0 nmol glucosyl residues/mg protein). However, high specific activity of glycogen synthase was found in retina, indicating a substantial capacity for glycogen synthesis. In diabetic rats, glycogen synthase activity increased between 50% and 100% in retina, brain cortex and liver of diabetic rats, but only retina exhibited an increase in glycogen content. Although, total and phosphorylated glycogen synthase levels were similar in normal and diabetic retina, activation of glycogen synthase by glucose-6-P was remarkable increased. Glycogen phosphorylase activity decreased 50% in the liver of diabetic animals; it was not modified in the other tissues examined. We conclude that the increase in glycogen levels in diabetic retina was due to alterations in glycogen synthase regulation.

  17. Genetics Home Reference: glycogen storage disease type VI

    MedlinePlus

    ... a result, liver cells cannot use glycogen for energy. Since glycogen cannot be broken down, it accumulates within liver cells, causing these cells to become enlarged and dysfunctional. Learn more about the gene associated with glycogen storage disease type VI PYGL Related Information What is ...

  18. Fructose effect to enhance liver glycogen deposition is due to inhibition of glycogenolysis

    SciTech Connect

    Youn, J.; Kaslow, H.; Bergman, R.

    1987-05-01

    The effect of fructose on glycogen degradation was examined by measuring flux of (/sup 14/C) from prelabeled glycogen in perfused rat livers. During 2 h refeeding of fasted rats hepatic glycogen was labeled by injection of (U /sup 14/C) galactose (0.1 mg and 0.02 ..mu..Ci/g of body weight). Refed livers were perfused for 30 min with glucose only (10 mM) and for 60 min with glucose (10 mM) without (n=5) or with fructose (1, 2, 10 mM; n=5 for each). With fructose, label production immediately declined and remained suppressed through the end of perfusion (P < 0.05). Suppression was dose-dependent: steady state label production was suppressed 45, 64, and 72% by 1, 2, and 10 mM fructose (P < 0.0001), without significant changes in glycogen synthase or phosphorylase. These results suggest the existence of allosteric inhibition of phosphorylase in the presence of fructose. Fructose 1-phosphate (F1P) accumulated in proportion to fructose (0.11 +/- 0.01 without fructose, 0.86 +/- 0.03, 1.81 +/- 0.18, and 8.23 +/- 0.6 ..mu..moles/g of liver with 1, 2, and 10 mM fructose. Maximum inhibition of phosphorylase was 82%; FIP concentration for half inhibition was 0.57 ..mu..moles/g of liver, well within the concentration of F1P attained in refeeding. Fructose enhances net glycogen synthesis in liver by suppressing glycogenolysis and the suppression is presumably caused by allosteric inhibition of phosphorylase by F1P.

  19. Hepatic microvascular regulatory mechanisms. X. Effects of alpha-one or -two adrenoceptor blockade on glucoregulation in normotensive endotoxic rats with optimal perfusion and flowrates.

    PubMed

    Reilly, F D; McCafferty, R E; Cilento, E V

    1988-08-01

    Circulating-blood glucose, hepatic glycogen distribution, and the glycogen contents of liver and skeletal muscle, were determined for 60 min in 31 fed and anesthetized Sprague-Dawley rats. These rats received an endoportal infusion of 15 mg per kg b.w. E. coli endotoxin (026:B6) or of sterile saline solution as a control. Either substance was given intravenously at 9:30 a.m. following an intraperitoneal injection at 9:00 a.m. of 0.1 mg per kg b.w. prazosin or 0.3 mg per kg b.w. yohimbine or of the carrier, distilled water. Infused endotoxin elevated blood glucose without affecting hepatic glycogen distribution and total glycogen contents of liver and skeletal muscle when compared to control. Prazosin inhibited endotoxin-induced hyperglycemia, and prazosin plus endotoxin provoked centrilobular glycogen depletion and decreased total hepatic glycogen content. However, no significant alteration in the glycogen content of skeletal muscle accompanied blockade of glucogenesis. Prazosin administered by itself produced no changes in hepatic and muscle glycogen. Although yohimbine blocked endotoxin-induced hyperglycemia, yohimbine, or yohimbine plus endotoxin, produced no significant change in the glycogen contents of liver and skeletal muscle. Blockade in the latter case was associated with some depletion of glycogen in hepatocytes dispersed randomly throughout the unit lobule and in cells located centrivenously. These results suggested that endotoxin-induced hyperglycemia is evoked by activation of alpha-1 and -2 adrenergic receptors. Since no detectible change in hepatic glycogen distribution and in the contents of liver and muscle glycogen accompanied glucogenesis, glycogen catabolism and deposition are postulated to proceed simultaneously and at equivalent rates by 60 min following the experimental induction of endotoxemia. Blockade of alpha (one or two) adrenoceptors is hypothesized to inhibit endotoxin-induced hyperglycemia by facilitating glucose utilization and not

  20. Amylin impairment of insulin effects on glycogen synthesis and phosphoenolpyruvate carboxykinase gene expression in rat primary cultured hepatocytes.

    PubMed Central

    Baqué, S; Guinovart, J J; Gómez-Foix, A M

    1994-01-01

    The ability of amylin to impair hepatic insulin action is controversial. We have found that the effect of amylin in primary cultured hepatocytes is strongly dependent on the culture conditions. Only in hepatocytes preincubated in the presence of fetal serum did amylin, at concentrations ranging from 1 to 100 nM, reduce insulin-stimulated glycogen synthesis rate and glycogen accumulation without showing direct effects. Neither basal glycogen synthase nor glycogen phosphorylase activity was modified by amylin treatment. Nevertheless, amylin (100 nM) blocked the activation of glycogen synthase by insulin. Amylin also proved capable of opposing the reduction in the expression of the phosphoenolpyruvate carboxykinase (PEPCK) gene induced by insulin, whereas the basal mRNA level of PEPCK was unaffected by amylin treatment. Thus, these results show that, in cultured rat hepatocytes, amylin is indeed able to interfere with insulin regulation of glycogenesis and PEPCK gene expression, favouring the hypothesis that amylin may modulate liver sensitivity to insulin. Images Figure 3 PMID:7998979

  1. In vivo regulation of muscle glycogen synthase and the control of glycogen synthesis.

    PubMed Central

    Shulman, R G; Bloch, G; Rothman, D L

    1995-01-01

    The activity of glycogen synthase (GSase; EC 2.4.1.11) is regulated by covalent phosphorylation. Because of this regulation, GSase has generally been considered to control the rate of glycogen synthesis. This hypothesis is examined in light of recent in vivo NMR experiments on rat and human muscle and is found to be quantitatively inconsistent with the data under conditions of glycogen synthesis. Our first experiments showed that muscle glycogen synthesis was slower in non-insulin-dependent diabetics compared to normals and that their defect was in the glucose transporter/hexokinase (GT/HK) part of the pathway. From these and other in vivo NMR results a quantitative model is proposed in which the GT/HK steps control the rate of glycogen synthesis in normal humans and rat muscle. The flux through GSase is regulated to match the proximal steps by "feed forward" to glucose 6-phosphate, which is a positive allosteric effector of all forms of GSase. Recent in vivo NMR experiments specifically designed to test the model are analyzed by metabolic control theory and it is shown quantitatively that the GT/HK step controls the rate of glycogen synthesis. Preliminary evidence favors the transporter step. Several conclusions are significant: (i) glucose transport/hexokinase controls the glycogen synthesis flux; (ii) the role of covalent phosphorylation of GSase is to adapt the activity of the enzyme to the flux and to control the metabolite levels not the flux; (iii) the quantitative data needed for inferring and testing the present model of flux control depended upon advances of in vivo NMR methods that accurately measured the concentration of glucose 6-phosphate and the rate of glycogen synthesis. Images Fig. 1 PMID:7567971

  2. The VP4 Peptide of Hepatitis A Virus Ruptures Membranes through Formation of Discrete Pores

    PubMed Central

    Shukla, Ashutosh; Padhi, Aditya K.; Gomes, James

    2014-01-01

    ABSTRACT Membrane-active peptides, components of capsid structural proteins, assist viruses in overcoming the host membrane barrier in the initial stages of infection. Several such peptides have been identified, and their roles in membrane fusion or disruption have been characterized through biophysical studies. In several members of the Picornaviridae family, the role of the VP4 structural peptide in cellular-membrane penetration is well established. However, there is not much information on the membrane-penetrating capsid components of hepatitis A virus (HAV), an unusual member of this family. The VP4 peptide of HAV differs from its analogues in other picornaviruses in being significantly shorter in length and in lacking a signal for myristoylation, thought to be a critical requisite for VP4-mediated membrane penetration. Here we report, for the first time, that the atypical VP4 in HAV contains significant membrane-penetrating activity. Using a combination of biophysical assays and molecular dynamics simulation studies, we show that VP4 integrates into membrane vesicles through its N-terminal region to finally form discrete pores of 5- to 9-nm diameter, which induces leakage in the vesicles without altering their overall size or shape. We further demonstrate that the membrane activity of VP4 is specific toward vesicles mimicking the lipid content of late endosomes at acidic pH. Taken together, our data indicate that VP4 might be essential for the penetration of host endosomal membranes and release of the viral genome during HAV entry. IMPORTANCE Hepatitis A virus causes acute hepatitis in humans through the fecal-oral route and is particularly prevalent in underdeveloped regions with poor hygienic conditions. Although a vaccine for HAV exists, its high cost makes it unsuitable for universal application in developing countries. Studies on host-virus interaction for HAV have been hampered due to a lack of starting material, since the virus is extremely slow growing

  3. Hepatic microvascular regulatory mechanisms. VIII. Glucogenic responses and morphologic changes following serotonin-induced low flow.

    PubMed

    Reilly, F D; McCafferty, R E; McCuskey, P A; Dimlich, R V

    1986-01-01

    Changes in blood glucose, hepatic glycogen content and distribution, the number of hepatic mast cells, and hepatic morphology were assessed over 30 min in non-fasted and anesthetized Sprague-Dawley rats receiving endoportal or femoral intravenous injections of selected doses of serotonin and/or phentolamine, lodoxamide, or of Ringer's solution (control). Endoportal administration of low-flow producing doses of serotonin (1.0, 10.0, 20.0 micrograms per 100 g b.w.) elevated circulating blood glucose without decreasing hepatic glycogen content when compared to control in unit dry or wet weights. Hyperglycemia was accompanied by centrilobular glycogen depletion and apparent Kupffer cell activation. However, no change in hepatocyte or endothelial cell morphology or in the number of hepatic mast cells was observed following serotonin-induced low flow. The glucotropic response to a nonhypotensive dose of serotonin (1.0 microgram per 100 g b.w.) was modified by phentolamine (100 micrograms per 100 g b.w.) but not lodoxamide (0.1 microgram per 100 g b.w.). These blockers, when given alone, stimulated centrilobular glycogen depletion without producing a net change in blood glucose or hepatic glycogen content. By contrast, injection of serotonin (10.0 micrograms per 100 g b.w.) and/or phentolamine (100 micrograms per 100 g b.w.) into the femoral vein provoked no glucogenesis or systemic hypotension. Given these results, serotonin is suggested to stimulate hyperglycemia by activating alpha-adrenergic receptors. Since centrilobular glycogen depletion proceeds with no detectable change in total hepatic glycogen content, it is postulated that hepatic glycogen catabolism and deposition occur simultaneously and at equivalent rates during conditions of serotonin-induced hyperglycemia and low flow.

  4. Leaf Extract from Lithocarpus polystachyus Rehd. Promote Glycogen Synthesis in T2DM Mice

    PubMed Central

    Chen, Yingying; Vanegas, Diana; McLamore, Eric Scott; Shen, Yingbai

    2016-01-01

    The purpose of this study was to investigate the effects of leaf extract from Lithocarpus polystachyus Rehd. on type II diabetes mellitus (T2DM) and the active ingredients of this effect. In addition, this study determined, for the first time, the underlying molecular and pharmacological mechanisms of the extracts on hyperglycemia using long-term double high diet-fed and streptozotocin (STZ) induced type II diabetic mice. In the present study, leaf extract, phloridzin and trilobatin were assessed in vivo (gavage) and in vitro (non-invasive micro-test technique, NMT) in experimental T2DM mice. The biochemical parameters were measured including blood glucose and blood lipid level, liver biochemical indexes, and hepatic glycogen. The relative expression of glycometabolism-related genes was detected. The effect of leaf extracts on physiological glucose flux in liver tissue from control and T2DM mice was also investigated. Body weight of experimental T2DM mice increased significantly after the first week, but stabilized over the subsequent three weeks; body weight of all other groups did not change during the four weeks’ study. After four weeks, all treatment groups decreased blood glucose, and treatment with leaf extract had numerous positive effects: a) promoted in glucose uptake in liver, b) increased synthesis of liver glycogen, c) reduced oxidative stress, d) up-regulation of glucokinase (GK), glucose transporter 2 (GLUT2), insulin receptor (IR) and insulin receptor substrate (IRS) expression in liver, e) down-regulation of glucose-6-phosphatase (G-6-P) expression, and f) ameliorated blood lipid levels. Both treatment with trilobatin or phloridzin accelerated liver glycogen synthesis, decreased oxidative stress and increased expression of GK. IRS and phosphoenolpyruvate carboxykinase (PEPCK) were both up-regulated after treatment with trilobatin. Expression of GLUT2, PEPCK and G-6-P were also increased in liver tissue after treatment with phloridzin. Our data

  5. Hepatitis B

    MedlinePlus

    ... Home » Hepatitis B » Hepatitis B Entire Lesson Viral Hepatitis Menu Menu Viral Hepatitis Viral Hepatitis Home For ... Enter ZIP code here Enter ZIP code here Hepatitis B Entire Lesson for Veterans and the Public ...

  6. Glycogen and its metabolism: some new developments and old themes

    PubMed Central

    Roach, Peter J.; Depaoli-Roach, Anna A.; Hurley, Thomas D.; Tagliabracci, Vincent S.

    2016-01-01

    Glycogen is a branched polymer of glucose that acts as a store of energy in times of nutritional sufficiency for utilization in times of need. Its metabolism has been the subject of extensive investigation and much is known about its regulation by hormones such as insulin, glucagon and adrenaline (epinephrine). There has been debate over the relative importance of allosteric compared with covalent control of the key biosynthetic enzyme, glycogen synthase, as well as the relative importance of glucose entry into cells compared with glycogen synthase regulation in determining glycogen accumulation. Significant new developments in eukaryotic glycogen metabolism over the last decade or so include: (i) three-dimensional structures of the biosynthetic enzymes glycogenin and glycogen synthase, with associated implications for mechanism and control; (ii) analyses of several genetically engineered mice with altered glycogen metabolism that shed light on the mechanism of control; (iii) greater appreciation of the spatial aspects of glycogen metabolism, including more focus on the lysosomal degradation of glycogen; and (iv) glycogen phosphorylation and advances in the study of Lafora disease, which is emerging as a glycogen storage disease. PMID:22248338

  7. DNA Polymerase κ Is a Key Cellular Factor for the Formation of Covalently Closed Circular DNA of Hepatitis B Virus

    PubMed Central

    Qi, Yonghe; Gao, Zhenchao; Peng, Bo; Yan, Huan; Tang, Dingbin; Song, Zilin; He, Wenhui; Sun, Yinyan; Guo, Ju-Tao; Li, Wenhui

    2016-01-01

    Hepatitis B virus (HBV) infection of hepatocytes begins by binding to its cellular receptor sodium taurocholate cotransporting polypeptide (NTCP), followed by the internalization of viral nucleocapsid into the cytoplasm. The viral relaxed circular (rc) DNA genome in nucleocapsid is transported into the nucleus and converted into covalently closed circular (ccc) DNA to serve as a viral persistence reservoir that is refractory to current antiviral therapies. Host DNA repair enzymes have been speculated to catalyze the conversion of rcDNA to cccDNA, however, the DNA polymerase(s) that fills the gap in the plus strand of rcDNA remains to be determined. Here we conducted targeted genetic screening in combination with chemical inhibition to identify the cellular DNA polymerase(s) responsible for cccDNA formation, and exploited recombinant HBV with capsid coding deficiency which infects HepG2-NTCP cells with similar efficiency of wild-type HBV to assure cccDNA synthesis is exclusively from de novo HBV infection. We found that DNA polymerase κ (POLK), a Y-family DNA polymerase with maximum activity in non-dividing cells, substantially contributes to cccDNA formation during de novo HBV infection. Depleting gene expression of POLK in HepG2-NTCP cells by either siRNA knockdown or CRISPR/Cas9 knockout inhibited the conversion of rcDNA into cccDNA, while the diminished cccDNA formation in, and hence the viral infection of, the knockout cells could be effectively rescued by ectopic expression of POLK. These studies revealed that POLK is a crucial host factor required for cccDNA formation during a de novo HBV infection and suggest that POLK may be a potential target for developing antivirals against HBV. PMID:27783675

  8. The laforin-malin complex negatively regulates glycogen synthesis by modulating cellular glucose uptake via glucose transporters.

    PubMed

    Singh, Pankaj Kumar; Singh, Sweta; Ganesh, Subramaniam

    2012-02-01

    Lafora disease (LD), an inherited and fatal neurodegenerative disorder, is characterized by increased cellular glycogen content and the formation of abnormally branched glycogen inclusions, called Lafora bodies, in the affected tissues, including neurons. Therefore, laforin phosphatase and malin ubiquitin E3 ligase, the two proteins that are defective in LD, are thought to regulate glycogen synthesis through an unknown mechanism, the defects in which are likely to underlie some of the symptoms of LD. We show here that laforin's subcellular localization is dependent on the cellular glycogen content and that the stability of laforin is determined by the cellular ATP level, the activity of 5'-AMP-activated protein kinase, and the affinity of malin toward laforin. By using cell and animal models, we further show that the laforin-malin complex regulates cellular glucose uptake by modulating the subcellular localization of glucose transporters; loss of malin or laforin resulted in an increased abundance of glucose transporters in the plasma membrane and therefore excessive glucose uptake. Loss of laforin or malin, however, did not affect glycogen catabolism. Thus, the excessive cellular glucose level appears to be the primary trigger for the abnormally higher levels of cellular glycogen seen in LD.

  9. Glycogen stability and glycogen phosphorylase activities in isolated skeletal muscles from rat and toad.

    PubMed

    Goodman, C A; Stephenson, G M

    2000-01-01

    There is increasing evidence that endogenous glycogen depletion may affect excitation-contraction (E-C) coupling events in vertebrate skeletal muscle. One approach employed in physiological investigations of E-C coupling involves the use of mechanically skinned, single fibre preparations obtained from tissues stored under paraffin oil, at room temperature (RT: 20-24 degrees C) and 4 degrees C for several hours. In the present study, we examined the effect of these storage conditions on the glycogen content in three muscles frequently used in research on E-C coupling: rat extensor digitorum longus (EDL) and soleus (SOL) and toad iliofibularis (IF). Glycogen content was determined fluorometrically in homogenates prepared from whole muscles, stored under paraffin oil for up to 6 h at RT or 4 degrees C. Control muscles and muscles stored for 0.5 and 6 h were also analysed for total phosphorylase (Phos(total)) and phosphorylase a (Phos a) activities. No significant change was observed in the glycogen content of EDL and SOL muscles stored at RT for 0.5 h. In rat muscles stored at RT for longer than 0.5 h, the glycogen content decreased to 67.6% (EDL) and 78.7% (SOL) of controls after 3 h and 25.3% (EDL) and 37.4% (SOL) after 6 h. Rat muscles stored at 4 degrees C retained 79.0% (EDL) and 92.5% (SOL) of glycogen after 3 h and 75.2% (EDL) and 61.1% (SOL) after 6 h. The glycogen content of IF muscles stored at RT or 4 degrees C for 6 h was not significantly different from controls. Phos(total) was unchanged in all muscles over the 6 h period, at both temperatures. Phos a was also unchanged in the toad IF muscles, but in rat muscles it decreased rapidly, particularly in EDL (4.1-fold after 0.5 h at RT). Taken together these results indicate that storage under paraffin oil for up to 6 h at RT or 4 degrees C is accompanied by minimal glycogen loss in toad IF muscles and by a time- and temperature-dependent glycogen loss in EDL and SOL muscles of the rat.

  10. Complete and Incomplete Hepatitis B Virus Particles: Formation, Function, and Application

    PubMed Central

    Hu, Jianming; Liu, Kuancheng

    2017-01-01

    Hepatitis B virus (HBV) is a para-retrovirus or retroid virus that contains a double-stranded DNA genome and replicates this DNA via reverse transcription of a RNA pregenome. Viral reverse transcription takes place within a capsid upon packaging of the RNA and the viral reverse transcriptase. A major characteristic of HBV replication is the selection of capsids containing the double-stranded DNA, but not those containing the RNA or the single-stranded DNA replication intermediate, for envelopment during virion secretion. The complete HBV virion particles thus contain an outer envelope, studded with viral envelope proteins, that encloses the capsid, which, in turn, encapsidates the double-stranded DNA genome. Furthermore, HBV morphogenesis is characterized by the release of subviral particles that are several orders of magnitude more abundant than the complete virions. One class of subviral particles are the classical surface antigen particles (Australian antigen) that contain only the viral envelope proteins, whereas the more recently discovered genome-free (empty) virions contain both the envelope and capsid but no genome. In addition, recent evidence suggests that low levels of RNA-containing particles may be released, after all. We will summarize what is currently known about how the complete and incomplete HBV particles are assembled. We will discuss briefly the functions of the subviral particles, which remain largely unknown. Finally, we will explore the utility of the subviral particles, particularly, the potential of empty virions and putative RNA virions as diagnostic markers and the potential of empty virons as a vaccine candidate. PMID:28335554

  11. Glutamate Cysteine Ligase—Modulatory Subunit Knockout Mouse Shows Normal Insulin Sensitivity but Reduced Liver Glycogen Storage

    PubMed Central

    Lavoie, Suzie; Steullet, Pascal; Kulak, Anita; Preitner, Frederic; Do, Kim Q.; Magistretti, Pierre J.

    2016-01-01

    Glutathione (GSH) deficits have been observed in several mental or degenerative illness, and so has the metabolic syndrome. The impact of a decreased glucose metabolism on the GSH system is well-known, but the effect of decreased GSH levels on the energy metabolism is unclear. The aim of the present study was to investigate the sensitivity to insulin in the mouse knockout (KO) for the modulatory subunit of the glutamate cysteine ligase (GCLM), the rate-limiting enzyme of GSH synthesis. Compared to wildtype (WT) mice, GCLM-KO mice presented with reduced basal plasma glucose and insulin levels. During an insulin tolerance test, GCLM-KO mice showed a normal fall in glycemia, indicating normal insulin secretion. However, during the recovery phase, plasma glucose levels remained lower for longer in KO mice despite normal plasma glucagon levels. This is consistent with a normal counterregulatory hormonal response but impaired mobilization of glucose from endogenous stores. Following a resident-intruder stress, during which stress hormones mobilize glucose from hepatic glycogen stores, KO mice showed a lower hyperglycemic level despite higher plasma cortisol levels when compared to WT mice. The lower hepatic glycogen levels observed in GCLM-KO mice could explain the impaired glycogen mobilization following induced hypoglycemia. Altogether, our results indicate that reduced liver glycogen availability, as observed in GCLM-KO mice, could be at the origin of their lower basal and challenged glycemia. Further studies will be necessary to understand how a GSH deficit, typically observed in GCLM-KO mice, leads to a deficit in liver glycogen storage. PMID:27148080

  12. Keratin 8/18 regulation of glucose metabolism in normal versus cancerous hepatic cells through differential modulation of hexokinase status and insulin signaling

    SciTech Connect

    Mathew, Jasmin; Loranger, Anne; Gilbert, Stéphane; Faure, Robert; Marceau, Normand

    2013-02-15

    As differentiated cells, hepatocytes primarily metabolize glucose for ATP production through oxidative phosphorylation of glycolytic pyruvate, whereas proliferative hepatocellular carcinoma (HCC) cells undergo a metabolic shift to aerobic glycolysis despite oxygen availability. Keratins, the intermediate filament (IF) proteins of epithelial cells, are expressed as pairs in a lineage/differentiation manner. Hepatocyte and HCC (hepatoma) cell IFs are made solely of keratins 8/18 (K8/K18), thus providing models of choice to address K8/K18 IF functions in normal and cancerous epithelial cells. Here, we demonstrate distinctive increases in glucose uptake, glucose-6-phosphate formation, lactate release, and glycogen formation in K8/K18 IF-lacking hepatocytes and/or hepatoma cells versus their respective IF-containing counterparts. We also show that the K8/K18-dependent glucose uptake/G6P formation is linked to alterations in hexokinase I/II/IV content and localization at mitochondria, with little effect on GLUT1 status. In addition, we find that the insulin-stimulated glycogen formation in normal hepatocytes involves the main PI-3 kinase-dependent signaling pathway and that the K8/K18 IF loss makes them more efficient glycogen producers. In comparison, the higher insulin-dependent glycogen formation in K8/K18 IF-lacking hepatoma cells is associated with a signaling occurring through a mTOR-dependent pathway, along with an augmentation in cell proliferative activity. Together, the results uncover a key K8/K18 regulation of glucose metabolism in normal and cancerous hepatic cells through differential modulations of mitochondrial HK status and insulin-mediated signaling.

  13. Hepatic and cerebral energy metabolism after neonatal canine alimentation.

    PubMed

    Kliegman, R M; Miettinen, E L; Morton, S K

    1983-04-01

    Intrahepatic and intracerebral metabolic responses to neonatal fasting or enteric carbohydrate alimentation were investigated among newborn dogs. Pups were either fasted or given an intravenous glucose infusion (alimented) before an enteric feeding of physiologic quantities of either glucose or galactose. These pups were also compared to another group which was completely starved throughout the study period. Gastrointestinal carbohydrate feeding resulted in enhanced hepatic glycogen content among pups after a prior state of fasting. Though there were no differences of glycogen content between glucose or galactose feeding in this previously fasted group, combined intravenous glucose and enteric galactose administration produced the greatest effect on hepatic glycogen synthesis. Intrahepatic fructose 1, 6-diphosphate and phosphoenolpyruvate levels were increased among previously fasted pups fed enteric monosaccharides compared to completely starved control pups, whereas intrahepatic phosphoenolpyruvate and pyruvate levels were elevated after combined intravenous and enteric carbohydrate administration. Of greater interest was the observation that hepatic levels of ATP were significantly elevated among all groups given exogenous carbohydrates compared to the completely starved control group. In contrast to the augmented hepatic glycogen and ATP levels, there were no alterations of cerebral glycogen or ATP after alimentation. Nevertheless, cerebral pyruvate and/or phosphoenolpyruvate concentrations were elevated after enteric or combined intravenous and enteric alimentation compared to the totally starved control pups.

  14. Phosphorylation of NS5A Serine-235 is essential to hepatitis C virus RNA replication and normal replication compartment formation

    SciTech Connect

    Eyre, Nicholas S.; Hampton-Smith, Rachel J.; Aloia, Amanda L.; Eddes, James S.; Simpson, Kaylene J.; Hoffmann, Peter; Beard, Michael R.

    2016-04-15

    Hepatitis C virus (HCV) NS5A protein is essential for HCV RNA replication and virus assembly. Here we report the identification of NS5A phosphorylation sites Ser-222, Ser-235 and Thr-348 during an infectious HCV replication cycle and demonstrate that Ser-235 phosphorylation is essential for HCV RNA replication. Confocal microscopy revealed that both phosphoablatant (S235A) and phosphomimetic (S235D) mutants redistribute NS5A to large juxta-nuclear foci that display altered colocalization with known replication complex components. Using electron microscopy (EM) we found that S235D alters virus-induced membrane rearrangements while EM using ‘APEX2’-tagged viruses demonstrated S235D-mediated enrichment of NS5A in irregular membranous foci. Finally, using a customized siRNA screen of candidate NS5A kinases and subsequent analysis using a phospho-specific antibody, we show that phosphatidylinositol-4 kinase III alpha (PI4KIIIα) is important for Ser-235 phosphorylation. We conclude that Ser-235 phosphorylation of NS5A is essential for HCV RNA replication and normal replication complex formation and is regulated by PI4KIIIα. - Highlights: • NS5A residues Ser-222, Ser-235 and Thr-348 are phosphorylated during HCV infection. • Phosphorylation of Ser-235 is essential to HCV RNA replication. • Mutation of Ser-235 alters replication compartment localization and morphology. • Phosphatidylinositol-4 kinase III alpha is important for Ser-235 phosphorylation.

  15. Mutations within potential glycosylation sites in the capsid protein of hepatitis E virus prevent the formation of infectious virus particles.

    PubMed

    Graff, Judith; Zhou, Yi-Hua; Torian, Udana; Nguyen, Hanh; St Claire, Marisa; Yu, Claro; Purcell, Robert H; Emerson, Suzanne U

    2008-02-01

    Hepatitis E virus is a nonenveloped RNA virus. However, the single capsid protein resembles a typical glycoprotein in that it contains a signal sequence and potential glycosylation sites that are utilized when recombinant capsid protein is overexpressed in cell culture. In order to determine whether these unexpected observations were biologically relevant or were artifacts of overexpression, we analyzed capsid protein produced during a normal viral replication cycle. In vitro transcripts from an infectious cDNA clone mutated to eliminate potential glycosylation sites were transfected into cultured Huh-7 cells and into the livers of rhesus macaques. The mutations did not detectably affect genome replication or capsid protein synthesis in cell culture. However, none of the mutants infected rhesus macaques. Velocity sedimentation analyses of transfected cell lysates revealed that mutation of the first two glycosylation sites prevented virion assembly, whereas mutation of the third site permitted particle formation and RNA encapsidation, but the particles were not infectious. However, conservative mutations that did not destroy glycosylation motifs also prevented infection. Overall, the data suggested that the mutations were lethal because they perturbed protein structure rather than because they eliminated glycosylation.

  16. Expression and characterization of thermostable glycogen branching enzyme from Geobacillus mahadia Geo-05

    PubMed Central

    Mohtar, Nur Syazwani; Raja Abd Rahman, Raja Noor Zaliha; Leow, Thean Chor; Salleh, Abu Bakar; Mat Isa, Mohd Noor

    2016-01-01

    The glycogen branching enzyme (EC 2.4.1.18), which catalyses the formation of α-1,6-glycosidic branch points in glycogen structure, is often used to enhance the nutritional value and quality of food and beverages. In order to be applicable in industries, enzymes that are stable and active at high temperature are much desired. Using genome mining, the nucleotide sequence of the branching enzyme gene (glgB) was extracted from the Geobacillus mahadia Geo-05 genome sequence provided by the Malaysia Genome Institute. The size of the gene is 2013 bp, and the theoretical molecular weight of the protein is 78.43 kDa. The gene sequence was then used to predict the thermostability, function and the three dimensional structure of the enzyme. The gene was cloned and overexpressed in E. coli to verify the predicted result experimentally. The purified enzyme was used to study the effect of temperature and pH on enzyme activity and stability, and the inhibitory effect by metal ion on enzyme activity. This thermostable glycogen branching enzyme was found to be most active at 55 °C, and the half-life at 60 °C and 70 °C was 24 h and 5 h, respectively. From this research, a thermostable glycogen branching enzyme was successfully isolated from Geobacillus mahadia Geo-05 by genome mining together with molecular biology technique. PMID:27957389

  17. Inactivation of the phosphoglucomutase gene pgm in Corynebacterium glutamicum affects cell shape and glycogen metabolism

    PubMed Central

    Seibold, Gerd M.; Eikmanns, Bernhard J.

    2013-01-01

    In Corynebacterium glutamicum formation of glc-1-P (α-glucose-1-phosphate) from glc-6-P (glucose-6-phosphate) by α-Pgm (phosphoglucomutase) is supposed to be crucial for synthesis of glycogen and the cell wall precursors trehalose and rhamnose. Furthermore, Pgm is probably necessary for glycogen degradation and maltose utilization as glucan phosphorylases of both pathways form glc-1-P. We here show that C. glutamicum possesses at least two Pgm isoenzymes, the cg2800 (pgm) encoded enzyme contributing most to total Pgm activity. By inactivation of pgm we created C. glutamicum IMpgm showing only about 12% Pgm activity when compared to the parental strain. We characterized both strains during cultivation with either glucose or maltose as substrate and observed that (i) the glc-1-P content in the WT (wild-type) and the mutant remained constant independent of the carbon source used, (ii) the glycogen levels in the pgm mutant were lower during growth on glucose and higher during growth on maltose, and (iii) the morphology of the mutant was altered with maltose as a substrate. We conclude that C. glutamicum employs glycogen as carbon capacitor to perform glc-1-P homeostasis in the exponential growth phase and is therefore able to counteract limited Pgm activity for both anabolic and catabolic metabolic pathways. PMID:23863124

  18. Effects of commonly used cryoprotectants on glycogen phosphorylase activity and structure.

    PubMed Central

    Tsitsanou, K. E.; Oikonomakos, N. G.; Zographos, S. E.; Skamnaki, V. T.; Gregoriou, M.; Watson, K. A.; Johnson, L. N.; Fleet, G. W.

    1999-01-01

    The effects of a number of cryoprotectants on the kinetic and structural properties of glycogen phosphorylase b have been investigated. Kinetic studies showed that glycerol, one of the most commonly used cryoprotectants in X-ray crystallographic studies, is a competitive inhibitor with respect to substrate glucose-1-P with an apparent Ki value of 3.8% (v/v). Cryogenic experiments, with the enzyme, have shown that glycerol binds at the catalytic site and competes with glucose analogues that bind at the catalytic site, thus preventing the formation of complexes. This necessitated a change in the conditions for cryoprotection in crystallographic binding experiments with glycogen phosphorylase. It was found that 2-methyl-2,4-pentanediol (MPD), polyethylene glycols (PEGs) of various molecular weights, and dimethyl sulfoxide (DMSO) activated glycogen phosphorylase b to different extents, by stabilizing its most active conformation, while sucrose acted as a noncompetitive inhibitor and ethylene glycol as an uncompetitive inhibitor with respect to glucose-1-P. A parallel experimental investigation by X-ray crystallography showed that, at 100 K, both MPD and DMSO do not bind at the catalytic site, do not induce any significant conformational change on the enzyme molecule, and hence, are more suitable cryoprotectants than glycerol for binding studies with glycogen phosphorylase. PMID:10211820

  19. Partial Purification and Characterization of Glycogen Phosphorylase from Dictyostelium discoideum1

    PubMed Central

    Jones, Theodore H. D.; Wright, Barbara E.

    1970-01-01

    Glycogen phosphorylase was isolated from cells of Dictyostelium discoideum in the culmination stage of development and purified 35-fold. The enzyme had a pH optimum of 6.9 and contained sulfhydryl groups essential for activity. The Km values for phosphate and glycogen were 3 mm and 0.06% (w/v), respectively. No dependence on, or stimulation by, any nucleotide was observed and a wide variety of nucleotides and glycolytic intermediates did not inhibit the enzyme. Nucleotide sugars competitively inhibited the enzyme. Guanosine diphosphoglucose and adenosine diphosphoglucose were the most effective, and uridine diphosphoglucose was the least effective of the nucleotide sugars tested. The specific activity of glycogen phosphorylase increased from about 0.004 unit per mg of protein in aggregating cells to about 0.024 unit per mg in culminating cells, and then decreased during sorocarp formation. This increase in enzyme specific activity during the starvation and aging of the system can account for the increased rate of glycogen degradation during this period of development. Amylase specific activity, measured at pH 4.8 and 6.9, varied between 0.005 and 0.013 unit per mg of protein during all stages of development. PMID:5530813

  20. Hepatitis A

    MedlinePlus

    Hepatitis A Hepatitis A Hepatitis A is a contagious viral infection that can easily affect children and adults. It is one of the most common types of hepatitis virus. Often when you hear about hepatitis A ...

  1. Dysfunctional Muscle and Liver Glycogen Metabolism in mdx Dystrophic Mice

    PubMed Central

    Stapleton, David I.; Lau, Xianzhong; Flores, Marcelo; Trieu, Jennifer; Gehrig, Stefan M.; Chee, Annabel; Naim, Timur; Lynch, Gordon S.; Koopman, René

    2014-01-01

    Background Duchenne muscular dystrophy (DMD) is a severe, genetic muscle wasting disorder characterised by progressive muscle weakness. DMD is caused by mutations in the dystrophin (dmd) gene resulting in very low levels or a complete absence of the dystrophin protein, a key structural element of muscle fibres which is responsible for the proper transmission of force. In the absence of dystrophin, muscle fibres become damaged easily during contraction resulting in their degeneration. DMD patients and mdx mice (an animal model of DMD) exhibit altered metabolic disturbances that cannot be attributed to the loss of dystrophin directly. We tested the hypothesis that glycogen metabolism is defective in mdx dystrophic mice. Results Dystrophic mdx mice had increased skeletal muscle glycogen (79%, (P<0.01)). Skeletal muscle glycogen synthesis is initiated by glycogenin, the expression of which was increased by 50% in mdx mice (P<0.0001). Glycogen synthase activity was 12% higher (P<0.05) but glycogen branching enzyme activity was 70% lower (P<0.01) in mdx compared with wild-type mice. The rate-limiting enzyme for glycogen breakdown, glycogen phosphorylase, had 62% lower activity (P<0.01) in mdx mice resulting from a 24% reduction in PKA activity (P<0.01). In mdx mice glycogen debranching enzyme expression was 50% higher (P<0.001) together with starch-binding domain protein 1 (219% higher; P<0.01). In addition, mdx mice were glucose intolerant (P<0.01) and had 30% less liver glycogen (P<0.05) compared with control mice. Subsequent analysis of the enzymes dysregulated in skeletal muscle glycogen metabolism in mdx mice identified reduced glycogenin protein expression (46% less; P<0.05) as a possible cause of this phenotype. Conclusion We identified that mdx mice were glucose intolerant, and had increased skeletal muscle glycogen but reduced amounts of liver glycogen. PMID:24626262

  2. Kinetic mechanism of rabbit muscle glycogen synthase I.

    PubMed

    Gold, A M

    1980-08-05

    The kinetic mechanism of rabbit muscle glycogen synthase I was investigated by determining isotope-exchange rates at chemical equilibrium between uridine diphosphoglucose (UDPG) and glycogen and between UDPG and uridine 5'-diphosphate (UDP). The rates were followed simultaneously by use of UDPG labeled with 14C in the glucose moiety and with 3H in the uracil group. They were found to be independent of the concentrations of glycogen and the UDPG-UDP pair, averaging 6 X 10(-9) mol min-1 mg-1, with a ratio of UDPG-glycogen exchange to UDPG-UDP exchange of 0.85-0.95. The conclusion is that glycogen synthase has a rapid equilibrium random bi bi mechanism. The previously reported slow activation of glycogen-free synthase in the presence of glycogen was examined kinetically. The activation rate appears to be independent of glycogen concentration over a wide range, while the maximum activation is related to the third or fourth root of the glycogen concentration. This suggest that the slow bimolecular reaction mechanism proposed for human polymorphonuclear leucocyte glycogen synthase I [Sølling, H., & Esmann, V. (1977) Eur. J. Biochem. 81, 129] does not apply to rabbit muscle synthase I. The rate of exchange of glycogen molecules in the complex between glycogen and rabbit muscle synthase I under conditions where the enzyme is catalytically active was estimated by a novel method. The enzyme-glycogen complex was treated with [glucose-14C]UDPG and glycogen of different molecular weight. The distribution of isotope between the two forms of glycogen was determined after their separation by agarose gel chromatography. A rate constant of 0.3 min-1 was estimated for the exchange. It can be calculated, on the basis of the specific activity of the enzyme (20 mumol min-1 mg-1) and its action pattern, that hundreds of individual chains in the glycogen molecule must be available to the enzyme during the average lifetime of the complex. A mechanism is proposed for this process.

  3. Glycogen storage disease type 1 and diabetes: learning by comparing and contrasting the two disorders.

    PubMed

    Rajas, F; Labrune, P; Mithieux, G

    2013-10-01

    Glycogen storage disease type 1 (GSD1) and diabetes may look at first like totally opposite disorders, as diabetes is characterized by uncontrolled hyperglycaemia, whereas GSD1 is characterized by severe fasting hypoglycaemia. Diabetes is due to a failure to suppress endogenous glucose production (EGP) in the postprandial state because of either a lack of insulin or insulin resistance. In contrast, GSD1 is characterized by a lack of EGP. However, both diseases share remarkably similar patterns in terms of pathophysiology such as the long-term progression of renal dysfunction and hepatic steatosis leading to renal failure and the development of hepatic tumours, respectively. Thus, much may be learned from considering the similarities between GSD1 and diabetes, especially in the metabolic pathways underlying nephropathy and fatty liver, and perhaps even more from their differences. In this review, the differences between diabetes and GSD1 are first highlighted, as both are characterized by alterations in EGP. The molecular pathways involved in liver pathologies, including steatosis, hepatomegaly (glycogenic hepatopathy) and the development of liver tumours are also compared. These pathologies are mainly due to the accumulation of lipids and/or glycogen in hepatocytes. Finally, the similar pathways leading to nephropathy in both diabetic and GSD1 patients are described. In conclusion, comparisons of these pathologies should lead to a better understanding of the crucial role of EGP in the control of glucose and energy homoeostasis. Moreover, it may highlight similar therapeutic targets for the two disorders. Thus, this review suggests that the treatment of adult patients with either GSD1 or diabetes could be carried out by the same specialists-diabetologists.

  4. Attenuation of Helicteres isora L. bark extracts on streptozotocin-induced alterations in glycogen and carbohydrate metabolism in albino rats.

    PubMed

    Kumar, G; Sharmila Banu, G; Murugesan, A G

    2009-11-01

    The present study was undertaken to assess the effect of Helicteres isora L. on four important enzymes of carbohydrate metabolism (glucokinase [GK], hexokinase [HK] phosphofructokinase [PFK] and fructose-1, 6-bisphosphatase [FBP]) along with glycogen content of insulin-dependent (skeletal muscle and liver) and insulin-independent tissues (kidneys and brain) in streptozotocin (STZ; 60 mg/kg)-induced model of diabetes for 30 days. Administration of bark extracts (100, 200 mg/kg) for 30 days led to decrease in plasma glucose levels by approximately 9.60% and 22.04% and 19.18% and 33.93% on 15th and 30th day, respectively, of the experiment. Liver and two-kidney weight expressed as percentage of body weight significantly increased in diabetics (P < 0.05) versus normal controls. Renal glycogen content increased by 10 folds while hepatic and skeletal muscle glycogen content decreased by 75% and 68% in diabetic controls versus controls. H. isora did not affect glycogen content in any tissue. The decreased activities of PFK, GK, FBP and HK in diabetic controls were 40%, 50%, 50% and 60% and bark extract of H. isora partially corrected this alteration. The efficacy of the bark extract was comparable with Tolbutamide, a well-known hypoglycemic drug.

  5. Glycogen Synthase Kinase-3 is involved in glycogen metabolism control and embryogenesis of Rhodnius prolixus.

    PubMed

    Mury, Flávia B; Lugon, Magda D; DA Fonseca, Rodrigo Nunes; Silva, Jose R; Berni, Mateus; Araujo, Helena M; Fontenele, Marcio Ribeiro; Abreu, Leonardo Araujo DE; Dansa, Marílvia; Braz, Glória; Masuda, Hatisaburo; Logullo, Carlos

    2016-10-01

    Rhodnius prolixus is a blood-feeding insect that transmits Trypanosoma cruzi and Trypanosoma rangeli to vertebrate hosts. Rhodnius prolixus is also a classical model in insect physiology, and the recent availability of R. prolixus genome has opened new avenues on triatomine research. Glycogen synthase kinase 3 (GSK-3) is classically described as a key enzyme involved in glycogen metabolism, also acting as a downstream component of the Wnt pathway during embryogenesis. GSK-3 has been shown to be highly conserved among several organisms, mainly in the catalytic domain region. Meanwhile, the role of GSK-3 during R. prolixus embryogenesis or glycogen metabolism has not been investigated. Here we show that chemical inhibition of GSK-3 by alsterpaullone, an ATP-competitive inhibitor of GSK3, does not affect adult survival rate, though it alters oviposition and egg hatching. Specific GSK-3 gene silencing by dsRNA injection in adult females showed a similar phenotype. Furthermore, bright field and 4'-6-diamidino-2-phenylindole (DAPI) staining analysis revealed that ovaries and eggs from dsGSK-3 injected females exhibited specific morphological defects. We also demonstrate that glycogen content was inversely related to activity and transcription levels of GSK-3 during embryogenesis. Lastly, after GSK-3 knockdown, we observed changes in the expression of the Wingless (Wnt) downstream target β-catenin as well as in members of other pathways such as the receptor Notch. Taken together, our results show that GSK-3 regulation is essential for R. prolixus oogenesis and embryogenesis.

  6. Biotin deficiency in a glycogen storage disease type 1b girl fed only with glycogen storage disease-related formula.

    PubMed

    Ihara, Kenji; Abe, Kiyomi; Hayakawa, Kou; Makimura, Mika; Kojima-Ishii, Kanako; Hara, Toshiro

    2011-01-01

    Glycogen storage disease type I is an autosomal recessive disorder caused by the defect in the glucose-6-phosphate enzyme system. Frequent intake of glucose-containing glycogen storage disease formula, uncooked cornstarch, or both, are usually needed to maintain normal blood glucose level. We report a glycogen storage disease type 1b girl with biotin deficiency caused by an exclusive glucose-containing glycogen storage disease formula for years, presenting with the appearance of severe skin lesions, and diagnosed by urinary organic acid analysis by gas chromato-spectrometry, and blood acylcarnitine analysis by tandem mass-spectrometry.

  7. Relationship between single nucleotide polymorphism of glycogen synthase gene of Pacific oyster Crassostrea gigas and its glycogen content

    NASA Astrophysics Data System (ADS)

    Liu, Siwei; Li, Qi; Yu, Hong; Kong, Lingfeng

    2017-02-01

    Glycogen is important not only for the energy supplementary of oysters, but also for human consumption. High glycogen content can improve the stress survival of oyster. A key enzyme in glycogenesis is glycogen synthase that is encoded by glycogen synthase gene GYS. In this study, the relationship between single nucleotide polymorphisms (SNPs) in coding regions of Crassostrea gigas GYS (Cg-GYS) and individual glycogen content was investigated with 321 individuals from five full-sib families. Single-strand conformation polymorphism (SSCP) procedure was combined with sequencing to confirm individual SNP genotypes of Cg-GYS. Least-square analysis of variance was performed to assess the relationship of variation in glycogen content of C. gigas with single SNP genotype and SNP haplotype. As a consequence, six SNPs were found in coding regions to be significantly associated with glycogen content ( P < 0.01), from which we constructed four main haplotypes due to linkage disequilibrium. Furthermore, the most effective haplotype H2 (GAGGAT) had extremely significant relationship with high glycogen content ( P < 0.0001). These findings revealed the potential influence of Cg-GYS polymorphism on the glycogen content and provided molecular biological information for the selective breeding of good quality traits of C. gigas.

  8. 13C and 1H Nuclear Magnetic Resonance Study of Glycogen Futile Cycling in Strains of the Genus Fibrobacter

    PubMed Central

    Matheron, Christelle; Delort, Anne-Marie; Gaudet, Geneviève; Forano, Evelyne; Liptaj, Tibor

    1998-01-01

    We investigated the carbon metabolism of three strains of Fibrobacter succinogenes and one strain of Fibrobacter intestinalis. The four strains produced the same amounts of the metabolites succinate, acetate, and formate in approximately the same ratio (3.7/1/0.3). The four strains similarly stored glycogen during all growth phases, and the glycogen-to-protein ratio was close to 0.6 during the exponential growth phase. 13C nuclear magnetic resonance (NMR) analysis of [1-13C]glucose utilization by resting cells of the four strains revealed a reversal of glycolysis at the triose phosphate level and the same metabolic pathways. Glycogen futile cycling was demonstrated by 13C NMR by following the simultaneous metabolism of labeled [13C]glycogen and exogenous unlabeled glucose. The isotopic dilutions of the CH2 of succinate and the CH3 of acetate when the resting cells were metabolizing [1-13C]glucose and unlabeled glycogen were precisely quantified by using 13C-filtered spin-echo difference 1H NMR spectroscopy. The measured isotopic dilutions were not the same for succinate and acetate; in the case of succinate, the dilutions reflected only the contribution of glycogen futile cycling, while in the case of acetate, another mechanism was also involved. Results obtained in complementary experiments are consistent with reversal of the succinate synthesis pathway. Our results indicated that for all of the strains, from 12 to 16% of the glucose entering the metabolic pathway originated from prestored glycogen. Although genetically diverse, the four Fibrobacter strains studied had very similar carbon metabolism characteristics. PMID:12033219

  9. Hepatitis C

    MedlinePlus

    ... Châu và vùng Thái Bình Dương Hepatitis C Hepatitis C What is hepatitis C? Hepatitis C is a viral infection that ... can cure most cases of hepatitis C. Acute hepatitis C Acute hepatitis C is a short-term ...

  10. Hepatitis A

    MedlinePlus

    ... Châu và vùng Thái Bình Dương Hepatitis C Hepatitis A What is hepatitis A? Hepatitis A is a viral infection that ... spreading hepatitis A to others . How common is hepatitis A? In the United States, hepatitis A has ...

  11. Hepatitis B

    MedlinePlus

    ... Châu và vùng Thái Bình Dương Hepatitis C Hepatitis B What is hepatitis B? Hepatitis B is a viral infection that ... to prevent spreading hepatitis B to others . Acute hepatitis B Acute hepatitis B is a short-term ...

  12. Hepatitis C Virus (HCV) Induces Formation of Stress Granules Whose Proteins Regulate HCV RNA Replication and Virus Assembly and Egress

    PubMed Central

    Heim, Markus H.; Boyd, Bryan; Wieland, Stefan

    2012-01-01

    Stress granules (SGs) are cytoplasmic structures that are induced in response to environmental stress, including viral infections. Here we report that hepatitis C virus (HCV) triggers the appearance of SGs in a PKR- and interferon (IFN)-dependent manner. Moreover, we show an inverse correlation between the presence of stress granules and the induction of IFN-stimulated proteins, i.e., MxA and USP18, in HCV-infected cells despite high-level expression of the corresponding MxA and USP18 mRNAs, suggesting that interferon-stimulated gene translation is inhibited in stress granule-containing HCV-infected cells. Finally, in short hairpin RNA (shRNA) knockdown experiments, we found that the stress granule proteins T-cell-restricted intracellular antigen 1 (TIA-1), TIA1-related protein (TIAR), and RasGAP-SH3 domain binding protein 1 (G3BP1) are required for efficient HCV RNA and protein accumulation at early time points in the infection and that G3BP1 and TIA-1 are required for intracellular and extracellular infectious virus production late in the infection, suggesting that they are required for virus assembly. In contrast, TIAR downregulation decreases extracellular infectious virus titers with little effect on intracellular RNA content or infectivity late in the infection, suggesting that it is required for infectious particle release. Collectively, these results illustrate that HCV exploits the stress granule machinery at least two ways: by inducing the formation of SGs by triggering PKR phosphorylation, thereby downregulating the translation of antiviral interferon-stimulated genes, and by co-opting SG proteins for its replication, assembly, and egress. PMID:22855484

  13. Hepatitis C virus (HCV) induces formation of stress granules whose proteins regulate HCV RNA replication and virus assembly and egress.

    PubMed

    Garaigorta, Urtzi; Heim, Markus H; Boyd, Bryan; Wieland, Stefan; Chisari, Francis V

    2012-10-01

    Stress granules (SGs) are cytoplasmic structures that are induced in response to environmental stress, including viral infections. Here we report that hepatitis C virus (HCV) triggers the appearance of SGs in a PKR- and interferon (IFN)-dependent manner. Moreover, we show an inverse correlation between the presence of stress granules and the induction of IFN-stimulated proteins, i.e., MxA and USP18, in HCV-infected cells despite high-level expression of the corresponding MxA and USP18 mRNAs, suggesting that interferon-stimulated gene translation is inhibited in stress granule-containing HCV-infected cells. Finally, in short hairpin RNA (shRNA) knockdown experiments, we found that the stress granule proteins T-cell-restricted intracellular antigen 1 (TIA-1), TIA1-related protein (TIAR), and RasGAP-SH3 domain binding protein 1 (G3BP1) are required for efficient HCV RNA and protein accumulation at early time points in the infection and that G3BP1 and TIA-1 are required for intracellular and extracellular infectious virus production late in the infection, suggesting that they are required for virus assembly. In contrast, TIAR downregulation decreases extracellular infectious virus titers with little effect on intracellular RNA content or infectivity late in the infection, suggesting that it is required for infectious particle release. Collectively, these results illustrate that HCV exploits the stress granule machinery at least two ways: by inducing the formation of SGs by triggering PKR phosphorylation, thereby downregulating the translation of antiviral interferon-stimulated genes, and by co-opting SG proteins for its replication, assembly, and egress.

  14. Single fiber analyses of glycogen-related proteins reveal their differential association with glycogen in rat skeletal muscle.

    PubMed

    Murphy, Robyn M; Xu, Hongyang; Latchman, Heidy; Larkins, Noni T; Gooley, Paul R; Stapleton, David I

    2012-12-01

    To understand how glycogen affects skeletal muscle physiology, we examined enzymes essential for muscle glycogen synthesis and degradation using single fibers from quiescent and stimulated rat skeletal muscle. Presenting a shift in paradigm, we show these proteins are differentially associated with glycogen granules. Protein diffusibility and/or abundance of glycogenin, glycogen branching enzyme (GBE), debranching enzyme (GDE), phosphorylase (GP), and synthase (GS) were examined in fibers isolated from rat fast-twitch extensor digitorum longus (EDL) and slow-twitch soleus (SOL) muscle. GDE and GP proteins were more abundant (~10- to 100-fold) in fibers from EDL compared with SOL muscle. GS and glycogenin proteins were similar between muscles while GBE had an approximately fourfold greater abundance in SOL muscle. Mechanically skinned fibers exposed to physiological buffer for 10 min showed ~70% total pools of GBE and GP were diffusible (nonbound), whereas GDE and GS were considerably less diffusible. Intense in vitro stimulation, sufficient to elicit a ~50% decrease in intracellular glycogen, increased diffusibility of GDE, GP, and GS (~15-60%) and decreased GBE diffusibility (~20%). Amylase treatment, which breaks α-1,4 linkages of glycogen, indicated differential diffusibilities and hence glycogen associations of GDE and GS. Membrane solubilization (1% Triton-X-100) allowed a small additional amount of GDE and GS to diffuse from fibers, suggesting the majority of nonglycogen-associated GDE/GS is associated with myofibrillar/contractile network of muscle rather than membranes. Given differences in enzymes required for glycogen metabolism, the current findings suggest glycogen particles have fiber-type-dependent structures. The greater catabolic potential of glycogen breakdown in fast-twitch fibers may account for different contraction induced rates of glycogen utilization.

  15. Glycogen synthesis from lactate in a chronically active muscle

    SciTech Connect

    Talmadge, R.J.; Scheide, J.I.; Silverman, H.

    1989-05-01

    In response to neural overactivity (pseudomyotonia), gastrocnemius muscle fibers from C57Bl/6Jdy2J/dy2J mice have different metabolic profiles compared with normal mice. A population of fibers in the fast-twitch superficial region of the dy2J gastrocnemius stores unusually high amounts of glycogen, leading to an increased glycogen storage in the whole muscle. The dy2J muscle also contains twice as much lactate as normal muscle. A (/sup 14/C)lactate intraperitoneal injection leads to preferential /sup 14/C incorporation into glycogen in the dy2J muscle compared with normal muscle. To determine whether skeletal muscles were incorporating lactate into glycogen without body organ (liver, kidney) input, gastrocnemius muscles were bathed in 10 mM (/sup 14/C)lactate with intact neural and arterial supply but with impeded venous return. The contralateral gastrocnemius serves as a control for body organ input. By using this in situ procedure, we demonstrate that under conditions of high lactate both normal and dy2J muscle can directly synthesize glycogen from lactate. In this case, normal whole muscle incorporates (14C) lactate into glycogen at a higher rate than dy2J whole muscle. Autoradiography, however, suggests that the high-glycogen-containing muscle fibers in the dy2J muscle incorporate lactate into glycogen at nearly four times the rate of normal or surrounding muscle fibers.

  16. Glycogen and glucose metabolism are essential for early embryonic development of the red flour beetle Tribolium castaneum.

    PubMed

    Fraga, Amanda; Ribeiro, Lupis; Lobato, Mariana; Santos, Vitória; Silva, José Roberto; Gomes, Helga; da Cunha Moraes, Jorge Luiz; de Souza Menezes, Jackson; de Oliveira, Carlos Jorge Logullo; Campos, Eldo; da Fonseca, Rodrigo Nunes

    2013-01-01

    Control of energy metabolism is an essential process for life. In insects, egg formation (oogenesis) and embryogenesis is dependent on stored molecules deposited by the mother or transcribed later by the zygote. In oviparous insects the egg becomes an isolated system after egg laying with all energy conversion taking place during embryogenesis. Previous studies in a few vector species showed a strong correlation of key morphogenetic events and changes in glucose metabolism. Here, we investigate glycogen and glucose metabolism in the red flour beetle Tribolium castaneum, an insect amenable to functional genomic studies. To examine the role of the key enzymes on glycogen and glucose regulation we cloned and analyzed the function of glycogen synthase kinase 3 (GSK-3) and hexokinase (HexA) genes during T. castaneum embryogenesis. Expression analysis via in situ hybridization shows that both genes are expressed only in the embryonic tissue, suggesting that embryonic and extra-embryonic cells display different metabolic activities. dsRNA adult female injection (parental RNAi) of both genes lead a reduction in egg laying and to embryonic lethality. Morphological analysis via DAPI stainings indicates that early development is impaired in Tc-GSK-3 and Tc-HexA1 RNAi embryos. Importantly, glycogen levels are upregulated after Tc-GSK-3 RNAi and glucose levels are upregulated after Tc-HexA1 RNAi, indicating that both genes control metabolism during embryogenesis and oogenesis, respectively. Altogether our results show that T. castaneum embryogenesis depends on the proper control of glucose and glycogen.

  17. Glycogen and Glucose Metabolism Are Essential for Early Embryonic Development of the Red Flour Beetle Tribolium castaneum

    PubMed Central

    Fraga, Amanda; Ribeiro, Lupis; Lobato, Mariana; Santos, Vitória; Silva, José Roberto; Gomes, Helga; da Cunha Moraes, Jorge Luiz; de Souza Menezes, Jackson

    2013-01-01

    Control of energy metabolism is an essential process for life. In insects, egg formation (oogenesis) and embryogenesis is dependent on stored molecules deposited by the mother or transcribed later by the zygote. In oviparous insects the egg becomes an isolated system after egg laying with all energy conversion taking place during embryogenesis. Previous studies in a few vector species showed a strong correlation of key morphogenetic events and changes in glucose metabolism. Here, we investigate glycogen and glucose metabolism in the red flour beetle Tribolium castaneum, an insect amenable to functional genomic studies. To examine the role of the key enzymes on glycogen and glucose regulation we cloned and analyzed the function of glycogen synthase kinase 3 (GSK-3) and hexokinase (HexA) genes during T. castaneum embryogenesis. Expression analysis via in situ hybridization shows that both genes are expressed only in the embryonic tissue, suggesting that embryonic and extra-embryonic cells display different metabolic activities. dsRNA adult female injection (parental RNAi) of both genes lead a reduction in egg laying and to embryonic lethality. Morphological analysis via DAPI stainings indicates that early development is impaired in Tc-GSK-3 and Tc-HexA1 RNAi embryos. Importantly, glycogen levels are upregulated after Tc-GSK-3 RNAi and glucose levels are upregulated after Tc-HexA1 RNAi, indicating that both genes control metabolism during embryogenesis and oogenesis, respectively. Altogether our results show that T. castaneum embryogenesis depends on the proper control of glucose and glycogen. PMID:23750237

  18. Viral Hepatitis

    MedlinePlus

    ... Public Home » For Veterans and the Public Viral Hepatitis Menu Menu Viral Hepatitis Viral Hepatitis Home For ... the Public Veterans and Public Home How is Hepatitis C Treated? Find the facts about the newest ...

  19. Autoimmune Hepatitis

    MedlinePlus

    ... Cholangitis Wilson Disease Liver Disease A-Z Autoimmune Hepatitis What is autoimmune hepatitis? Autoimmune hepatitis is a chronic—or long lasting— ... bacteria, viruses, toxins, and medications. What causes autoimmune hepatitis? A combination of autoimmunity, environmental triggers, and a ...

  20. Human Choline Kinase-α Promotes Hepatitis C Virus RNA Replication through Modulation of Membranous Viral Replication Complex Formation

    PubMed Central

    Wong, Mun-Teng

    2016-01-01

    ABSTRACT Hepatitis C virus (HCV) infection reorganizes cellular membranes to create an active viral replication site named the membranous web (MW). The role that human choline kinase-α (hCKα) plays in HCV replication remains elusive. Here, we first showed that hCKα activity, not the CDP-choline pathway, promoted viral RNA replication. Confocal microscopy and subcellular fractionation of HCV-infected cells revealed that a small fraction of hCKα colocalized with the viral replication complex (RC) on the endoplasmic reticulum (ER) and that HCV infection increased hCKα localization to the ER. In the pTM-NS3-NS5B model, NS3-NS5B expression increased the localization of the wild-type, not the inactive D288A mutant, hCKα on the ER, and hCKα activity was required for effective trafficking of hCKα and NS5A to the ER. Coimmunoprecipitation showed that hCKα was recruited onto the viral RC presumably through its binding to NS5A domain 1 (D1). hCKα silencing or treatment with CK37, an hCKα activity inhibitor, abolished HCV-induced MW formation. In addition, hCKα depletion hindered NS5A localization on the ER, interfered with NS5A and NS5B colocalization, and mitigated NS5A-NS5B interactions but had no apparent effect on NS5A-NS4B and NS4B-NS5B interactions. Nevertheless, hCKα activity was not essential for the binding of NS5A to hCKα or NS5B. These findings demonstrate that hCKα forms a complex with NS5A and that hCKα activity enhances the targeting of the complex to the ER, where hCKα protein, not activity, mediates NS5A binding to NS5B, thereby promoting functional membranous viral RC assembly and viral RNA replication. IMPORTANCE HCV infection reorganizes the cellular membrane to create an active viral replication site named the membranous web (MW). Here, we report that human choline kinase-α (hCKα) acts as an essential host factor for HCV RNA replication. A fraction of hCKα colocalizes with the viral replication complex (RC) on the endoplasmic reticulum

  1. Viral Hepatitis

    MedlinePlus

    ... with hepatitis? How does a pregnant woman pass hepatitis B virus to her baby? If I have hepatitis B, what does my baby need so that she ... Can I breastfeed my baby if I have hepatitis B? More information on viral hepatitis What is hepatitis? ...

  2. Improving size-exclusion chromatography separation for glycogen.

    PubMed

    Sullivan, Mitchell A; Powell, Prudence O; Witt, Torsten; Vilaplana, Francisco; Roura, Eugeni; Gilbert, Robert G

    2014-03-07

    Glycogen is a hyperbranched glucose polymer comprised of glycogen β particles, which can also form much larger composite α particles. The recent discovery using size-exclusion chromatography (SEC) that fewer, smaller, α particles are found in diabetic-mouse liver compared to healthy mice highlights the need to achieve greater accuracy in the size separation methods used to analyze α and β particles. While past studies have used dimethyl sulfoxide as the SEC eluent to analyze the molecular size and structure of native glycogen, an aqueous eluent has not been rigorously tested and compared with dimethyl sulfoxide. The conditions for SEC of pig-liver glycogen, phytoglycogen and oyster glycogen were optimized by comparing two different eluents, aqueous 50 mM NH₄NO₃/0.02% NaN₃ and dimethyl sulfoxide/0.5% LiBr, run through different column materials and pore sizes at various flow rates. The aqueous system gave distinct size separation of α- and β-particle peaks, allowing for a more detailed and quantitative analysis and comparison between liver glycogen samples. This greater resolution has also revealed key differences between the structure of liver glycogen and phytoglycogen.

  3. Regulation of glycogen metabolism in yeast and bacteria

    PubMed Central

    Wilson, Wayne A.; Roach, Peter J.; Montero, Manuel; Baroja-Fernández, Edurne; Muñoz, Francisco José; Eydallin, Gustavo; Viale, Alejandro M.; Pozueta-Romero, Javier

    2010-01-01

    Microorganisms have the capacity to utilize a variety of nutrients and adapt to continuously changing environmental conditions. Many microorganisms, including yeast and bacteria, accumulate carbon and energy reserves to cope with starvation conditions temporarily present in the environment. Glycogen biosynthesis is a main strategy for such metabolic storage and a variety of sensing and signaling mechanisms have evolved in evolutionarily distant species to guarantee the production of this homopolysaccharide. At the most fundamental level, the processes of glycogen synthesis and degradation in yeast and bacteria share certain broad similarities. However, the regulation of these processes is sometimes quite distinct, indicating that they have evolved separately to respond optimally to the habitat conditions of each species. This review aims to highlight the mechanisms, both at the transcriptional and post-transcriptional levels, which regulate glycogen metabolism in yeast and bacteria, focusing on selected areas where the greatest increase in knowledge has occurred during the last few years. In the yeast system, we focus particularly on the various signaling pathways that control the activity of the enzymes of glycogen storage. We also discuss our recent understanding of the important role played by the vacuole in glycogen metabolism. In the case of bacterial glycogen, especial emphasis is given to aspects related with genetic regulation of glycogen metabolism and its connection with other biological processes. PMID:20412306

  4. Changes in brain glycogen after sleep deprivation vary with genotype.

    PubMed

    Franken, Paul; Gip, Phung; Hagiwara, Grace; Ruby, Norman F; Heller, H Craig

    2003-08-01

    Sleep has been functionally implicated in brain energy homeostasis in that it could serve to replenish brain energy stores that become depleted while awake. Sleep deprivation (SD) should therefore lower brain glycogen content. We tested this hypothesis by sleep depriving mice of three inbred strains, i.e., AKR/J (AK), DBA/2J (D2), and C57BL/6J (B6), that differ greatly in their sleep regulation. After a 6-h SD, these mice and their controls were killed by microwave irradiation, and glycogen and glucose were quantified in the cerebral cortex, brain stem, and cerebellum. After SD, both measures significantly increased by approximately 40% in the cortex of B6 mice, while glycogen significantly decreased by 20-38% in brain stem and cerebellum of AK and D2 mice. In contrast, after SD, glucose content increased in all three structures in AK mice and did not change in D2 mice. The increase in glycogen after SD in B6 mice persisted under conditions of food deprivation that, by itself, lowered cortical glycogen. Furthermore, the strains that differ most in their compensatory response to sleep loss, i.e., AK and D2, did not differ in their glycogen response. Thus glycogen content per se is an unlikely end point of sleep's functional role in brain energy homeostasis.

  5. Cx3cr1 deficiency in mice attenuates hepatic granuloma formation during acute schistosomiasis by enhancing the M2-type polarization of macrophages.

    PubMed

    Ran, Lin; Yu, Qilin; Zhang, Shu; Xiong, Fei; Cheng, Jia; Yang, Ping; Xu, Jun-Fa; Nie, Hao; Zhong, Qin; Yang, Xueli; Yang, Fei; Gong, Quan; Kuczma, Michal; Kraj, Piotr; Gu, Weikuan; Ren, Bo-Xu; Wang, Cong-Yi

    2015-07-01

    Acute schistosomiasis is characterized by pro-inflammatory responses against tissue- or organ-trapped parasite eggs along with granuloma formation. Here, we describe studies in Cx3cr1(-/-) mice and demonstrate the role of Cx3cr1 in the pathoetiology of granuloma formation during acute schistosomiasis. Mice deficient in Cx3cr1 were protected from granuloma formation and hepatic injury induced by Schistosoma japonicum eggs, as manifested by reduced body weight loss and attenuated hepatomegaly along with preserved liver function. Notably, S. japonicum infection induced high levels of hepatic Cx3cr1 expression, which was predominantly expressed by infiltrating macrophages. Loss of Cx3cr1 rendered macrophages preferentially towards M2 polarization, which then led to a characteristic switch of the host immune defense from a conventional Th1 to a typical Th2 response during acute schistosomiasis. This immune switch caused by Cx3cr1 deficiency was probably associated with enhanced STAT6/PPAR-γ signaling and increased expression of indoleamine 2,3-dioxygenase (IDO), an enzyme that promotes M2 polarization of macrophages. Taken together, our data provide evidence suggesting that CX3CR1 could be a viable therapeutic target for treatment of acute schistosomiasis.

  6. Cx3cr1 deficiency in mice attenuates hepatic granuloma formation during acute schistosomiasis by enhancing the M2-type polarization of macrophages

    PubMed Central

    Ran, Lin; Yu, Qilin; Zhang, Shu; Xiong, Fei; Cheng, Jia; Yang, Ping; Xu, Jun-Fa; Nie, Hao; Zhong, Qin; Yang, Xueli; Yang, Fei; Gong, Quan; Kuczma, Michal; Kraj, Piotr; Gu, Weikuan; Ren, Bo-Xu; Wang, Cong-Yi

    2015-01-01

    ABSTRACT Acute schistosomiasis is characterized by pro-inflammatory responses against tissue- or organ-trapped parasite eggs along with granuloma formation. Here, we describe studies in Cx3cr1−/− mice and demonstrate the role of Cx3cr1 in the pathoetiology of granuloma formation during acute schistosomiasis. Mice deficient in Cx3cr1 were protected from granuloma formation and hepatic injury induced by Schistosoma japonicum eggs, as manifested by reduced body weight loss and attenuated hepatomegaly along with preserved liver function. Notably, S. japonicum infection induced high levels of hepatic Cx3cr1 expression, which was predominantly expressed by infiltrating macrophages. Loss of Cx3cr1 rendered macrophages preferentially towards M2 polarization, which then led to a characteristic switch of the host immune defense from a conventional Th1 to a typical Th2 response during acute schistosomiasis. This immune switch caused by Cx3cr1 deficiency was probably associated with enhanced STAT6/PPAR-γ signaling and increased expression of indoleamine 2,3-dioxygenase (IDO), an enzyme that promotes M2 polarization of macrophages. Taken together, our data provide evidence suggesting that CX3CR1 could be a viable therapeutic target for treatment of acute schistosomiasis. PMID:26035381

  7. Glycogen phosphorylase in Acanthamoeba spp.: determining the role of the enzyme during the encystment process using RNA interference.

    PubMed

    Lorenzo-Morales, Jacob; Kliescikova, Jarmila; Martinez-Carretero, Enrique; De Pablos, Luis Miguel; Profotova, Bronislava; Nohynkova, Eva; Osuna, Antonio; Valladares, Basilio

    2008-03-01

    Acanthamoeba infections are difficult to treat due to often late diagnosis and the lack of effective and specific therapeutic agents. The most important reason for unsuccessful therapy seems to be the existence of a double-wall cyst stage that is highly resistant to the available treatments, causing reinfections. The major components of the Acanthamoeba cyst wall are acid-resistant proteins and cellulose. The latter has been reported to be the major component of the inner cyst wall. It has been demonstrated previously that glycogen is the main source of free glucose for the synthesis of cellulose in Acanthamoeba, partly as glycogen levels fall during the encystment process. In other lower eukaryotes (e.g., Dictyostelium discoideum), glycogen phosphorylase has been reported to be the main tool used for glycogen breakdown in order to maintain the free glucose levels during the encystment process. Therefore, it was hypothesized that the regulation of the key processes involved in the Acanthamoeba encystment may be similar to the previously reported regulation mechanisms in other lower eukaryotes. The catalytic domain of the glycogen phosphorylase was silenced using RNA interference methods, and the effect of this phenomenon was assessed by light and electron microscopy analyses, calcofluor staining, expression zymogram assays, and Northern and Western blot analyses of both small interfering RNA-treated and control cells. The present report establishes the role of glycogen phosphorylase during the encystment process of Acanthamoeba. Moreover, the obtained results demonstrate that the enzyme is required for cyst wall assembly, mainly for the formation of the cell wall inner layer.

  8. A detailed characterization of the adult mouse model of glycogen storage disease Ia.

    PubMed

    Salganik, Susan V; Weinstein, David A; Shupe, Thomas D; Salganik, Max; Pintilie, Dana G; Petersen, Bryon E

    2009-09-01

    Glycogen storage disease type Ia (GSDIa) is caused by a genetic defect in the hepatic enzyme glucose-6-phosphatase (G6Pase-alpha), which manifests as life-threatening hypoglycemia with related metabolic complications. A G6Pase-alpha knockout (KO) mouse model was generated to study potential therapies for correcting this disorder. Since then, gene therapy studies have produced promising results, showing long-term improvement in liver histology and glycogen metabolism. Under existing protocols, however, untreated KO pups seldom survived weaning. Here, we present a thorough characterization of the G6Pase-alpha KO mouse, as well as the husbandry protocol for rearing this strain to adulthood. These mice were raised with only palliative care, and characterized from birth through 6 months of age. Once KO mice have survived the very frail weaning period, their size, agility, serum lipids and glycemic control improve dramatically, reaching levels approaching their wild-type littermates. In addition, our data reveal that adult mice lacking G6Pase-alpha are able to mate and produce viable offspring. However, liver histology and glycogen accumulation do not improve with age. Overall, the reliable production of mature KO mice could provide a critical tool for advancing the GSDIa field, as the availability of a robust enzyme-deficient adult offers a new spectrum of treatment avenues that would not be tolerated by the frail pups. Most importantly, our detailed characterization of the adult KO mouse provides a crucial baseline for accurately gauging the efficacy of experimental therapies in this important model.

  9. Castanospermine inhibits alpha-glucosidase activities and alters glycogen distribution in animals.

    PubMed

    Saul, R; Ghidoni, J J; Molyneux, R J; Elbein, A D

    1985-01-01

    Castanospermine, an inhibitor of alpha-glucosidase activity, was injected into rats to determine its effects in vivo. Daily injections of alkaloid, at levels of 0.5 mg/g of body weight, or higher, for 3 days decreased hepatic alpha-glucosidase to 40% of control values, whereas alpha-glucosidase in brain was reduced to 25% of control values and that in spleen and kidney was reduced to about 40%. In liver, both the neutral (pH 6.5) and the acidic (pH 4.5) alpha-glucosidase activities were inhibited, but the former was more susceptible. On the other hand, beta-N-acetylhexosaminidase activity was elevated in the livers of treated animals, whereas beta-galactosidase activity was unchanged and alpha-mannosidase activity was somewhat inhibited. Livers of treated animals were examined by light and electron microscopy and compared to control animals to determine whether changes in morphology had occurred. In treated animals fed normal rat chow, the hepatocytes were smaller in size and simplified in structure, whereas the high-glucose diet lessened these alterations. Furthermore, in those animals receiving castanospermine at 1.0 mg or higher per g of body weight for 3 days, there was a marked decrease in the amount of glycogen in the cytoplasm, while a large number of lysosomes were observed that were full of dense, granular material. That this dense material was indeed glycogen was shown by the fact that it disappeared when blocks of fixed tissue were pretreated with alpha-amylase. Glycogen levels in liver, as measured either colorimetrically or enzymatically, were somewhat depressed at the higher levels of castanospermine.

  10. 13C-nuclear magnetic resonance spectroscopy studies of hepatic glucose metabolism in normal subjects and subjects with insulin-dependent diabetes mellitus.

    PubMed Central

    Cline, G W; Rothman, D L; Magnusson, I; Katz, L D; Shulman, G I

    1994-01-01

    To determine the effect of insulin-dependent diabetes mellitus (IDDM) on rates and pathways of hepatic glycogen synthesis, as well as flux through hepatic pyruvate dehydrogenase, we used 13C-nuclear magnetic resonance spectroscopy to monitor the peak intensity of the C1 resonance of the glucosyl units of hepatic glycogen, in combination with acetaminophen to sample the hepatic UDP-glucose pool and phenylacetate to sample the hepatic glutamine pool, during a hyperglycemic-hyperinsulinemic clamp using [1-13C]-glucose. Five subjects with poorly controlled IDDM and six age-weight-matched control subjects were clamped at a mean plasma glucose concentration of approximately 9 mM and mean plasma insulin concentrations approximately 400 pM for 5 h. Rates of hepatic glycogen synthesis were similar in both groups (approximately 0.43 +/- 0.09 mumol/ml liver min). However, flux through the indirect pathway of glycogen synthesis (3 carbon units-->-->glycogen) was increased by approximately 50% (P < 0.05), whereas the relative contribution of pyruvate oxidation to TCA cycle flux was decreased by approximately 30% (P < 0.05) in the IDDM subjects compared to the control subjects. These studies demonstrate that patients with poorly controlled insulin-dependent diabetes mellitus have augmented hepatic gluconeogenesis and relative decreased rates of hepatic pyruvate oxidation. These abnormalities are not immediately reversed by normalizing intraportal concentrations of glucose, insulin, and glucagon and may contribute to postprandial hyperglycemia. PMID:7989593

  11. Ontogeny of the rat hepatic adrenoceptors

    SciTech Connect

    McMillian, M.K.

    1985-01-01

    Hepatic alpha-1, alpha-2, and beta-2 adrenoceptors were characterized during development of the rat through Scatchard analysis of (/sup 3/H)-prazosin, (/sup 3/H)-rauwolscine and (/sup 125/I)-pindolol binding to washed particle membrane preparations. Major changes in adrenoceptor number occur shortly before birth and at weaning. The fetal rat liver is characterized by a large number of alpha-2 adrenoceptors which falls 10-20 fold at birth. The number of hepatic beta adrenoceptors decreases 30-50% during the third week after birth increases slightly at weaning, then decreases gradually in the adult. Hepatic alpha-1 adrenoceptor number increases 3-5 fold at weaning to become the predominant adrenoceptor in the adult rat liver. The basis for the fall in alpha-2 number at birth remains unclear. The fall in beta receptor number at the end of the second week post-natally appears dependent on increased insulin and corticosterone secretion as well as increased NE release form nerve terminals. The basis for the increase in beta number at weaning and the sex-dependent loss of beta function but not receptor number in the adult rat remains unknown. The dramatic increases in alpha-1 number and function at weaning are dependent on increased adrenocortical secretion, adrenalectomy prevents the normal. This effect of adrenocorticoids might be mediated through glycogen, as glycogen depletion during fasting decreases alpha-1 receptor number and function at weaning are dependent on increased adrenocortical secretion, adrenalectomy prevents the normal. This effect of adrenocorticoids might be mediated through glycogen, as glycogen depletion during fasting decreases alpha-1 receptor number and function. These findings suggest that hepatic adrenoceptor number adapts from the low carbohydrate diet of the suckling rat to the high carbohydrate diet of the adult at weaning.

  12. The Phospholipid:Diacylglycerol Acyltransferase Lro1 Is Responsible for Hepatitis C Virus Core-Induced Lipid Droplet Formation in a Yeast Model System

    PubMed Central

    Wang, Chao-Wen; Cheng, Yun-Hsin; Irokawa, Hayato; Hwang, Gi-Wook; Naganuma, Akira; Kuge, Shusuke

    2016-01-01

    Chronic infection with the hepatitis C virus frequently induces steatosis, which is a significant risk factor for liver pathogenesis. Steatosis is characterized by the accumulation of lipid droplets in hepatocytes. The structural protein core of the virus induces lipid droplet formation and localizes on the surface of the lipid droplets. However, the precise molecular mechanisms for the core-induced formation of lipid droplets remain elusive. Recently, we showed that the expression of the core protein in yeast as a model system could induce lipid droplet formation. In this study, we probed the cellular factors responsible for the formation of core-induced lipid-droplets in yeast cells. We demonstrated that one of the enzymes responsible for triglyceride synthesis, a phospholipid:diacylglycerol acyltransferase (Lro1), is required for the core-induced lipid droplet formation. While core proteins inhibit Lro1 degradation and alter Lro1 localization, the characteristic localization of Lro1 adjacent to the lipid droplets appeared to be responsible for the core-induced lipid droplet formation. RNA virus genomes have evolved using high mutation rates to maintain their ability to replicate. Our observations suggest a functional relationship between the core protein with hepatocytes and yeast cells. The possible interactions between core proteins and the endoplasmic reticulum membrane affect the mobilization of specific proteins. PMID:27459103

  13. Glucose uptake and glycogen synthesis in muscles from immobilized limbs

    NASA Technical Reports Server (NTRS)

    Nicholson, W. F.; Watson, P. A.; Booth, F. W.

    1984-01-01

    Defects in glucose metabolism in muscles of immobilized limbs of mice were related to alterations in insulin binding, insulin responsiveness, glucose supply, and insulin activation of glycogen synthase. These were tested by in vitro methodology. A significant lessening in the insulin-induced maximal response of 2-deoxyglucose uptake into the mouse soleus muscle occurred between the 3rd and 8th h of limb immobilization, suggesting a decreased insulin responsiveness. Lack of change in the specific binding of insulin to muscles of 24-h immobilized limbs indicates that a change in insulin receptor number did not play a role in the failure of insulin to stimulate glucose metabolism. Its inability to stimulate glycogen synthesis in muscle from immobilized limbs is due, in part, to a lack of glucose supply to glycogen synthesis and also to the ineffectiveness of insulin to increase the percentage of glycogen synthase in its active form in muscles from 24-h immobilized limbs.

  14. Genetics Home Reference: glycogen storage disease type IX

    MedlinePlus

    ... Additional Information & Resources MedlinePlus (3 links) Health Topic: Carbohydrate Metabolism Disorders Health Topic: Liver Diseases Health Topic: ... kinase deficiency Merck Manual Consumer Version: Disorders of Carbohydrate Metabolism My46 Trait Profile Orphanet: Glycogen storage disease ...

  15. Quantifying the contribution of the liver to glucose homeostasis: a detailed kinetic model of human hepatic glucose metabolism.

    PubMed

    König, Matthias; Bulik, Sascha; Holzhütter, Hermann-Georg

    2012-01-01

    Despite the crucial role of the liver in glucose homeostasis, a detailed mathematical model of human hepatic glucose metabolism is lacking so far. Here we present a detailed kinetic model of glycolysis, gluconeogenesis and glycogen metabolism in human hepatocytes integrated with the hormonal control of these pathways by insulin, glucagon and epinephrine. Model simulations are in good agreement with experimental data on (i) the quantitative contributions of glycolysis, gluconeogenesis, and glycogen metabolism to hepatic glucose production and hepatic glucose utilization under varying physiological states. (ii) the time courses of postprandial glycogen storage as well as glycogen depletion in overnight fasting and short term fasting (iii) the switch from net hepatic glucose production under hypoglycemia to net hepatic glucose utilization under hyperglycemia essential for glucose homeostasis (iv) hormone perturbations of hepatic glucose metabolism. Response analysis reveals an extra high capacity of the liver to counteract changes of plasma glucose level below 5 mM (hypoglycemia) and above 7.5 mM (hyperglycemia). Our model may serve as an important module of a whole-body model of human glucose metabolism and as a valuable tool for understanding the role of the liver in glucose homeostasis under normal conditions and in diseases like diabetes or glycogen storage diseases.

  16. Hepatocellular Adenomas and Carcinoma in Asymptomatic, Non-Cirrhotic Type III Glycogen Storage Disease.

    PubMed

    Oterdoom, Leendert H; Verweij, K Evelyne; Biermann, Katharina; Langeveld, Mirjam; van Buuren, Henk R

    2015-12-01

    Glycogen storage diseases (GSDs) are a group of inherited metabolic disorders characterized by accumulation of abnormal glycogen in muscle or liver or both. Specific hepatic complications include liver adenomas and hepatocellular carcinoma (HCC). Hepatocellular carcinomas described in GSD type I are often due to the degeneration of liver adenomas. Hepatocellular carcinoma in GSD type III, however, is rare and is thought to be associated with underlying cirrhosis.We present the case of a 63-year old male who was admitted for assessment of suitability for liver transplantation because of development of recurrent HCC in the presence of multiple liver adenomas. A diagnosis of GSD type III was made in this patient without underlying cirrhosis or metabolic disturbances resembling GSD. This case report is the first documentation of HCC development in an asymptomatic, non-cirrhotic patient with GSD type III. This raises the possibility that in GSD type III, the adenoma - carcinoma sequence can occur as it is also seen in GSD type I. Physicians taking care of GSD patients should be aware of this and some form of surveillance for cirrhosis and HCC should be considered. Also male patients with adenomas should have a thorough workup to reveal any underlying disease such as GSD.

  17. Molecular Mechanisms of Allosteric Inhibition of Brain Glycogen Phosphorylase by Neurotoxic Dithiocarbamate Chemicals.

    PubMed

    Mathieu, Cécile; Bui, Linh-Chi; Petit, Emile; Haddad, Iman; Agbulut, Onnik; Vinh, Joelle; Dupret, Jean-Marie; Rodrigues-Lima, Fernando

    2017-02-03

    Dithiocarbamates (DTCs) are important industrial chemicals used extensively as pesticides and in a variety of therapeutic applications. However, they have also been associated with neurotoxic effects and in particular with the development of Parkinson-like neuropathy. Although different pathways and enzymes (such as ubiquitin ligases or the proteasome) have been identified as potential targets of DTCs in the brain, the molecular mechanisms underlying their neurotoxicity remain poorly understood. There is increasing evidence that alteration of glycogen metabolism in the brain contributes to neurodegenerative processes. Interestingly, recent studies with N,N-diethyldithiocarbamate suggest that brain glycogen phosphorylase (bGP) and glycogen metabolism could be altered by DTCs. Here, we provide molecular and mechanistic evidence that bGP is a target of DTCs. To examine this system, we first tested thiram, a DTC pesticide known to display neurotoxic effects, observing that it can react rapidly with bGP and readily inhibits its glycogenolytic activity (kinact = 1.4 × 10(5) m(-1) s(-1)). Using cysteine chemical labeling, mass spectrometry, and site-directed mutagenesis approaches, we show that thiram (and certain of its metabolites) alters the activity of bGP through the formation of an intramolecular disulfide bond (Cys(318)-Cys(326)), known to act as a redox switch that precludes the allosteric activation of bGP by AMP. Given the key role of glycogen metabolism in brain functions and neurodegeneration, impairment of the glycogenolytic activity of bGP by DTCs such as thiram may be a new mechanism by which certain DTCs exert their neurotoxic effects.

  18. Allosteric regulation of glycogen synthase in liver. A physiological dilemma.

    PubMed

    Nuttall, F Q; Gannon, M C

    1993-06-25

    Glycogen synthase catalyzes the transfer of the glucosyl moiety from UDP-glucose to the terminal branch of the glycogen molecule and is considered to be the rate-limiting enzyme for glycogen synthesis. However, under ideal assay conditions, i.e. 37 degrees C with saturating concentrations of UDP-glucose and the activator, glucose-6-P, the maximal catalytic activity of glycogen synthase was only 78% of the in vivo glycogen synthetic rate. Using concentrations of UDP-glucose and glucose-6-P likely to be present in vivo, the rate was only approximately 30%. This prompted us to reassess a possible role of allosteric effectors on synthase activity. Glycogen synthase was assayed at 37 degrees C using dilute, pH 7.0, buffered extracts, initial rate conditions, and UDP-glucose and glucose-6-P concentrations, which approximate those calculated to be present in total liver cell water. Several allosteric effectors were tested. Magnesium and AMP had little effect on activity. Pi, ADP, ATP, and UTP inhibited activity. When a combination of effectors were added at concentrations approximating those present in cell water, synthase activity could account for only 2% of the glycogen synthetic rate. Thus, although allosteric effectors are likely to be playing a major role in regulating synthase enzymic activity in liver cells, to date, a metabolite that can stimulate activity and/or overcome nucleotide inhibition has yet to be identified. If such a metabolite cannot be identified, an additional or alternative pathway for glycogen synthesis must be considered.

  19. A metabolic link between mitochondrial ATP synthesis and liver glycogen metabolism: NMR study in rats re-fed with butyrate and/or glucose

    PubMed Central

    2011-01-01

    Background Butyrate, end-product of intestinal fermentation, is known to impair oxidative phosphorylation in rat liver and could disturb glycogen synthesis depending on the ATP supplied by mitochondrial oxidative phosphorylation and cytosolic glycolysis. Methods In 48 hr-fasting rats, hepatic changes of glycogen and total ATP contents and unidirectional flux of mitochondrial ATP synthesis were evaluated by ex vivo 31P NMR immediately after perfusion and isolation of liver, from 0 to 10 hours after force-feeding with (butyrate 1.90 mg + glucose 14.0 mg.g-1 body weight) or isocaloric glucose (18.2 mg.g-1 bw); measurements reflected in vivo situation at each time of liver excision. The contribution of energetic metabolism to glycogen metabolism was estimated. Results A net linear flux of glycogen synthesis (~11.10 ± 0.60 μmol glucosyl units.h-1.g-1 liver wet weight) occurred until the 6th hr post-feeding in both groups, whereas butyrate delayed it until the 8th hr. A linear correlation between total ATP and glycogen contents was obtained (r2 = 0.99) only during net glycogen synthesis. Mitochondrial ATP turnover, calculated after specific inhibition of glycolysis, was stable (~0.70 ± 0.25 μmol.min-1.g-1 liver ww) during the first two hr whatever the force-feeding, and increased transiently about two-fold at the 3rd hr in glucose. Butyrate delayed the transient increase (1.80 ± 0.33 μmol.min-1.g-1 liver ww) to the 6th hr post-feeding. Net glycogenolysis always appeared after the 8th hr, whereas flux of mitochondrial ATP synthesis returned to near basal level (0.91 ± 0.19 μmol.min-1.g-1 liver ww). Conclusion In liver from 48 hr-starved rats, the energy need for net glycogen synthesis from exogenous glucose corresponds to ~50% of basal mitochondrial ATP turnover. The evidence of a late and transient increase in mitochondrial ATP turnover reflects an energetic need, probably linked to a glycogen cycling. Butyrate, known to reduce oxidative phosphorylation yield and

  20. Glycogen synthase kinase-3: cryoprotection and glycogen metabolism in the freeze-tolerant wood frog.

    PubMed

    Dieni, Christopher A; Bouffard, Melanie C; Storey, Kenneth B

    2012-02-01

    The terrestrial anuran Rana sylvatica tolerates extended periods of whole-body freezing during the winter. Freezing survival is facilitated by extensive glycogen hydrolysis and distribution of high concentrations of the cryoprotectant glucose into blood and all tissues. As glycogenesis is both an energy-expensive process and counter-productive to maintaining sustained high cryoprotectant levels, we proposed that glycogen synthase kinase-3 (GSK-3) would be activated when wood frogs froze and would phosphorylate its downstream substrates to inactivate glycogen synthesis. Western blot analysis determined that the amount of phosphorylated (inactive) GSK-3 decreased in all five tissues tested in 24 h frozen frogs compared with unfrozen controls. Total GSK-3 protein levels did not change, with the exception of heart GSK-3, indicating that post-translational modification was the primary regulatory mechanism for this kinase. Kinetic properties of skeletal muscle GSK-3 from control and frozen frogs displayed differential responses to a temperature change (22 versus 4°C) and high glucose. For example, when assayed at 4°C, the K(m) for the GSK-3 substrate peptide was ∼44% lower for frozen frogs than the corresponding value in control frogs, indicating greater GSK-3 affinity for its substrates in the frozen state. This indicates that at temperatures similar to the environment encountered by frogs, GSK-3 in frozen frogs will phosphorylate its downstream targets more readily than in unfrozen controls. GSK-3 from skeletal muscle of control frogs was also allosterically regulated. AMP and phosphoenolpyruvate activated GSK-3 whereas inhibitors included glucose, glucose 6-phosphate, pyruvate, ATP, glutamate, glutamine, glycerol, NH(4)Cl, NaCl and KCl. The combination of phosphorylation and allosteric control argues for a regulatory role of GSK-3 in inactivating glycogenesis to preserve high glucose cryoprotectant levels throughout each freezing bout.

  1. Structure and solution properties of enzymatically synthesized glycogen.

    PubMed

    Kajiura, Hideki; Takata, Hiroki; Kuriki, Takashi; Kitamura, Shinichi

    2010-04-19

    Recently, a new enzymatic process for glycogen production was developed. In this process, short-chain amylose is used as a substrate for branching enzymes (BE, EC 2.4.1.18). The molecular weight of the enzymatically synthesized glycogen (ESG) depends on the size and concentration of the substrate. Structural and physicochemical properties of ESG were compared to those of natural source glycogen (NSG). The average chain length, interior chain length, and exterior chain length of ESG were 8.2-11.6, 2.0-3.3, and 4.2-7.6, respectively. These values were within the range of variation of NSG. The appearances of both ESG and NSG in solution were opalescent (milky white and slightly bluish). Furthermore, transmission electron microscopy and atomic force microscopy showed that ESG molecules formed spherical particles, and that there were no differences between ESG and NSG. Viscometric analyses also showed the spherical nature of both glycogens. When ESG and NSG were treated with pullulanase, a glucan-hydrolyzing enzyme known to degrade glycogen only on its surface portion, both glycogens were similarly degraded. These analyses revealed that ESG shares similar molecular shapes and surface properties with NSG.

  2. Glycogen storage in fetuses of trained pregnant rats.

    PubMed

    Houghton, P E; Mottola, M F; Mezzapelli, J; Vandermolen, R; Christopher, P D

    1997-08-01

    The purpose was to determine if running 30 m/min on a 10 degrees incline, 60 min/day for 5 days/ week altered fetal glycogen storage in prepregnancy trained rats. Animals that exercised for 3 weeks prior to pregnancy either continued the same exercise program until Day 19 of gestation (pregnant running group [PR]), or ceased exercising at conception (pregnant controls [PC]). A separate set of animals did not exercise either before or during pregnancy (pregnant nonrunning control group [PNRC]). On Day 20 of gestation, fetal organs and placenta were weighted and analyzed for glycogen concentration. Glycogen concentrations were not different in either fetal liver, heart, or placenta of PR rats compared to PNRC animals. However, fetal liver glycogen concentration was significantly lower in the fetal heart and liver of PC animals compared to glycogen measured in both PNRC and PR animals (p < .05). These results suggest that exercise of this intensity does not compromise fetal glycogen storage in trained pregnant rats. However, chronic prepregnancy exercise and then abrupt cessation of exercise at conception may compromise fetal growth and development.

  3. Glycogen storage disease type Ia in canines: a model for human metabolic and genetic liver disease.

    PubMed

    Specht, Andrew; Fiske, Laurie; Erger, Kirsten; Cossette, Travis; Verstegen, John; Campbell-Thompson, Martha; Struck, Maggie B; Lee, Young Mok; Chou, Janice Y; Byrne, Barry J; Correia, Catherine E; Mah, Cathryn S; Weinstein, David A; Conlon, Thomas J

    2011-01-01

    A canine model of Glycogen storage disease type Ia (GSDIa) is described. Affected dogs are homozygous for a previously described M121I mutation resulting in a deficiency of glucose-6-phosphatase-α. Metabolic, clinicopathologic, pathologic, and clinical manifestations of GSDIa observed in this model are described and compared to those observed in humans. The canine model shows more complete recapitulation of the clinical manifestations seen in humans including "lactic acidosis", larger size, and longer lifespan compared to other animal models. Use of this model in preclinical trials of gene therapy is described and briefly compared to the murine model. Although the canine model offers a number of advantages for evaluating potential therapies for GSDIa, there are also some significant challenges involved in its use. Despite these challenges, the canine model of GSDIa should continue to provide valuable information about the potential for generating curative therapies for GSDIa as well as other genetic hepatic diseases.

  4. Inhibition of protein kinase C phosphorylation of hepatitis B virus capsids inhibits virion formation and causes intracellular capsid accumulation.

    PubMed

    Wittkop, Linda; Schwarz, Alexandra; Cassany, Aurelia; Grün-Bernhard, Stefanie; Delaleau, Mildred; Rabe, Birgit; Cazenave, Christian; Gerlich, Wolfram; Glebe, Dieter; Kann, Michael

    2010-07-01

    Capsids of hepatitis B virus and other hepadnaviruses contain a cellular protein kinase, which phosphorylates the capsid protein. Some phosphorylation sites are shown to be essential for distinct steps of viral replication as pregenome packaging or plus strand DNA synthesis. Although different protein kinases have been reported to phosphorylate the capsid protein, varying experimental approaches do not allow direct comparison. Furthermore, the activity of a specific protein kinase has not yet been correlated to steps in the hepadnaviral life cycle. In this study we show that capsids from various sources encapsidate active protein kinase Calpha, irrespective of hepatitis B virus genotype and host cell. Treatment of a virion expressing cell line with a pseudosubstrate inhibitor showed that inhibition of protein kinase C phosphorylation did not affect genome maturation but resulted in capsid accumulation and inhibited virion release to the medium. Our results imply that different protein kinases have distinct functions within the hepadnaviral life cycle.

  5. Transient Hepatic Overexpression of Insulin-Like Growth Factor 2 Induces Free Cholesterol and Lipid Droplet Formation

    PubMed Central

    Kessler, Sonja M.; Laggai, Stephan; Van Wonterghem, Elien; Gemperlein, Katja; Müller, Rolf; Haybaeck, Johannes; Vandenbroucke, Roosmarijn E.; Ogris, Manfred; Libert, Claude; Kiemer, Alexandra K.

    2016-01-01

    Although insulin-like growth factor 2 (IGF2) has been reported to be overexpressed in steatosis and steatohepatitis, a causal role of IGF2 in steatosis development remains elusive. Aim of our study was to decipher the role of IGF2 in steatosis development. Hydrodynamic gene delivery of an Igf2 plasmid used for transient Igf2 overexpression employing codon-optimized plasmid DNA resulted in a strong induction of hepatic Igf2 expression. The exogenously delivered Igf2 had no influence on endogenous Igf2 expression. The downstream kinase AKT was activated in Igf2 animals. Decreased ALT levels mirrored the cytoprotective effect of IGF2. Serum cholesterol was increased and sulfo-phospho-vanillin colorimetric assay confirmed lipid accumulation in Igf2-livers while no signs of inflammation were observed. Interestingly, hepatic cholesterol and phospholipids, determined by thin layer chromatography, and free cholesterol by filipin staining, were specifically increased. Lipid droplet (LD) size was not changed, but their number was significantly elevated. Furthermore, free cholesterol, which can be stored in LDs and has been reported to be critical for steatosis progression, was elevated in Igf2 overexpressing mice. Accordingly, Hmgcr/HmgCoAR was upregulated. To have a closer look at de novo lipid synthesis we investigated expression of the lipogenic transcription factor SREBF1 and its target genes. SREBF1 was induced and also SREBF1 target genes were slightly upregulated. Interestingly, the expression of Cpt1a, which is responsible for mitochondrial fatty acid oxidation, was induced. Hepatic IGF2 expression induces a fatty liver, characterized by increased cholesterol and phospholipids leading to accumulation of LDs. We therefore suggest a causal role for IGF2 in hepatic lipid accumulation. PMID:27199763

  6. Hepatitis C

    MedlinePlus

    ... your doctor may want you to get the hepatitis B vaccine (and maybe the hepatitis A vaccine, too), if you don't already have these viruses. If you have hepatitis C, you are more likely to catch hepatitis A or hepatitis B, which would cause more damage to your liver. ...

  7. Spatial and temporal transcriptomics of Schistosoma japonicum-induced hepatic granuloma formation reveals novel roles for neutrophils.

    PubMed

    Chuah, Candy; Jones, Malcolm K; Burke, Melissa L; Owen, Helen C; Anthony, Barrie J; McManus, Donald P; Ramm, Grant A; Gobert, Geoffrey N

    2013-08-01

    The severity of schistosome egg-induced hepatic granulomatous pathology depends markedly on the nature of the host immune responses. In this study, we used LMM and microarray analysis to compare gene expression profiles of histologically distinct zones within, and directly proximal to, hepatic granulomas that developed in C57BL/6 mice infected with Schistosoma japonicum. There was significant up-regulation of type-1, type-2, and type-17 immune-associated genes within the granuloma core (adjacent to eggs), followed by increased expression of type-2 and fibrotic genes at the outer zones of granulomas. Neutrophil-associated genes were also found to be expressed differentially in the core and at the peripheral zone of granulomas, present at 7 weeks p.i., demonstrating a significant role of neutrophils in S. japonicum granulomatous pathology. The release of NETs was observed microscopically in granulomas obtained from the livers of infected mice and when human neutrophils were incubated in vitro in the presence of S. japonicum eggs. These finding are the first to suggest a novel, dual role for neutrophils in the mediation of tissue damage and repair in S. japonicum egg-induced hepatic granulomatous lesions. Together, these results provide an overview of the local events occurring within the granuloma microenvironment.

  8. Expression and characterization of glycogen synthase kinase-3 mutants and their effect on glycogen synthase activity in intact cells.

    PubMed Central

    Eldar-Finkelman, H; Argast, G M; Foord, O; Fischer, E H; Krebs, E G

    1996-01-01

    In these studies we expressed and characterized wild-type (WT) GSK-3 (glycogen synthase kinase-3) and its mutants, and examined their physiological effect on glycogen synthase activity. The GSK-3 mutants included mutation at serine-9 either to alanine (S9A) or glutamic acid (S9E) and an inactive mutant, K85,86MA. Expression of WT and the various mutants in a cell-free system indicated that S9A and S9E exhibit increased kinase activity as compared with WT. Subsequently, 293 cells were transiently transfected with WT GSK-3 and mutants. Cells expressing the S9A mutant exhibited higher kinase activity (2.6-fold of control cells) as compared with cells expressing WT and S9E (1.8- and 2.0-fold, respectively, of control cells). Combined, these results suggest serine-9 as a key regulatory site of GSK-3 inactivation, and indicate that glutamic acid cannot mimic the function of the phosphorylated residue. The GSK-3-expressing cell system enabled us to examine whether GSK-3 can induce changes in the endogenous glycogen synthase activity. A decrease in glycogen synthase activity (50%) was observed in cells expressing the S9A mutant. Similarly, glycogen synthase activity was suppressed in cells expressing WT and the S9E mutant (20-30%, respectively). These studies indicate that activation of GSK-3 is sufficient to inhibit glycogen synthase in intact cells, and provide evidence supporting a physiological role for GSK-3 in regulating glycogen synthase and glycogen metabolism. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 PMID:8816781

  9. Focal hepatic glycogenosis associated with metastatic insulinoma presenting as mass lesions.

    PubMed

    Vyas, Monika; Zhang, Xuchen; Morrow, Jon S; Jain, Dhanpat; Salem, Ronald R; West, A Brian

    2016-01-01

    One of the important functions of the liver is glycogen storage. Most processes associated with increased hepatic glycogen, or glycogenoses, are metabolic and affect the entire liver leading to diffuse glycogenosis. We present a case in which the liver contained multiple small pale nodules that on initial assessment were recognized to be composed of glycogenated hepatocytes. Most of the known causes of hepatic glycogenosis were not pertinent to this case. After cutting many deeper levels and obtaining additional sections, small foci of insulinoma were revealed in the center of each of these lesions. The glycogenosis surrounding the foci of insulinoma can be best explained as a local effect of insulin on the hepatocytes, a phenomenon that has been previously described in primate models, but not in human subjects. Here, we report the first case of metastatic insulinoma causing local hepatic glycogenosis.

  10. Hepatic, gut, and renal substrate flux rates in patients with hepatic cirrhosis.

    PubMed Central

    Owen, O E; Reichle, F A; Mozzoli, M A; Kreulen, T; Patel, M S; Elfenbein, I B; Golsorkhi, M; Chang, K H; Rao, N S; Sue, H S; Boden, G

    1981-01-01

    The roles of liver, kidney, and gut in maintaining fuel homeostasis were studied in 28 patients with severe hepatic cirrhosis, 25 of whom had alcohol-induced cirrhosis. Hepatic, portal, and renal blood flow rates were measured and combined with substrate concentration differences across liver, gut, and kidney to calculate the net flux of free fatty acids, ketone bodies, triglycerides, and glucose with selected glucose precursors, including glycerol, lactate, pyruvate, and amino acids. Data from the catheterization studies were related to hepatic histology, glycogen content, and activities of gluconeogenic enzymes and compared with data obtained from control patients. The effects of food deprivation on net flux of fuels across the liver, gut, and kidney were assessed after overnight and after 3d of fasting. Activities of gluconeogenic enzymes were normal, but hepatic glycogen content was diminished in cirrhotic livers, probably as a consequence of extensive hepatic fibrosis. Extrahepatic splanchnic tissues (gut) had only a small influence on total splanchnic flux rates of carbohydrates, lipids and, amino acids. In cirrhotic patients, there was no mean renal glucose contribution to the bloodstream after an overnight or after a 3-d fast. After an overnight fast hepatic glucose production in patients with cirrhosis was diminished as a result of low-rate glycogenolysis. Hepatic gluconeogenesis and ketogenesis were increased. This pattern of hepatic metabolism mimics that seen in "normal" patients after more advanced stages of starvation. After 3 d of starvation, patients with hepatic cirrhosis have hepatic gluconeogenic and ketogenic profiles comparable to those of normal patients undergoing starvation of similar duration. Nevertheless, the total number of caloric equivalents derived from ketone bodies plus glucose corrected for recycled lactate and pyruvate added to the bloodstream by the cirrhotic livers that could be terminally oxidized by peripheral tissues was less

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

    PubMed

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

    2012-01-01

    A female presented in infancy with hypotonia, undetectable serum glucose, lactic acidosis, and triglycerides >5000 mg/dL. The diagnosis of type 1A glycogen storage disease was made via the result of a liver biopsy, which showed increased glycogen and absent glucose-6-phosphatase enzyme activity. The patient was treated with dextrose administered orally, which was replaced by frequent feedings of cornstarch, which resulted in an improvement of her metabolic parameters. At age 18 years of age, she had marked hypertriglyceridemia (3860 mg/dL) and eruptive xanthomas and was treated with fenofibrate, atorvastatin, and fish oil. At age 29 years she was noted to have multiple liver adenomas, severe anemia, and hyperuricemia. Aggressive cornstarch therapy was commenced with a goal of maintaining her blood glucose levels >75 mg/dL and lactate levels <2 mmol/L. After 15 months on this regimen, her lipids levels (measured in mg/dL) off all medications were as follows: total cholesterol 222, triglycerides 179, high-density lipoprotein cholesterol 32, and calculated low-density lipoprotein cholesterol 154. Her weight was stable with a body mass index of 24.8 kg/m(2). Her liver adenomas had decreased in size, and her anemia and hyperuricemia had improved. She was homozygous for the R83C missense mutation in G6PC. Our data indicate that optimized metabolic control to maintain blood glucose levels >75 mg/dL is critical in the management of this disease.

  12. Hepatitis C

    MedlinePlus

    Hepatitis C Overview By Mayo Clinic Staff Hepatitis C is a viral infection that causes liver inflammation, sometimes leading to serious liver damage. The hepatitis C virus (HCV) spreads through contaminated ...

  13. Toxic Hepatitis

    MedlinePlus

    Toxic hepatitis Overview By Mayo Clinic Staff Toxic hepatitis is an inflammation of your liver in reaction to certain substances to which you're exposed. Toxic hepatitis can be caused by alcohol, chemicals, drugs or ...

  14. Digestion of glycogen by a glucosidase released by Trichomonas vaginalis.

    PubMed

    Huffman, Ryan D; Nawrocki, Lauren D; Wilson, Wayne A; Brittingham, Andrew

    2015-12-01

    Trichomonas vaginalis is a protozoan parasite that is the causative agent of trichomoniasis, a widespread sexually transmitted disease. In vitro culture of T. vaginalis typically employs a medium supplemented with either maltose or glucose and carbohydrates are considered essential for growth. Although the nature of the carbohydrates utilized by T. vaginalis in vivo is undefined, the vaginal epithelium is rich in glycogen, which appears to provide a source of carbon for the vaginal microbiota. Here, we show that T. vaginalis grows equally well in growth media supplemented with simple sugars or with glycogen. Analysis of conditioned growth medium by thin layer chromatography indicates that growth on glycogen is accompanied by glycogen breakdown to a mixture of products including maltose, glucose, and oligosaccharides. Enzymatic assays with conditioned growth medium show that glycogen breakdown is accomplished via the release of a glucosidase activity having the properties of an α-amylase into the growth medium. Furthermore, we find that released glucosidase activity increases upon removal of carbohydrate from the growth medium, indicating regulation of synthesis and/or secretion in response to environmental cues. Lastly, we show that addition of T. vaginalis glucosidase activity to a growth medium containing glycogen generates sufficient simple sugar to support the growth of lactobacilli which, themselves, are unable to degrade glycogen. Thus, not only does the glucosidase activity likely play an important role in allowing T. vaginalis to secure simple sugars for its own use, it has the potential to impact the growth of other members of the vaginal microbiome.

  15. Lithium Induces Glycogen Accumulation in Salivary Glands of the Rat.

    PubMed

    Souza, D N; Mendes, F M; Nogueira, F N; Simões, A; Nicolau, J

    2016-02-01

    Lithium is administered for the treatment of mood and bipolar disorder. The aim of this study was to verify whether treatment with different concentrations of lithium may affect the glycogen metabolism in the salivary glands of the rats when compared with the liver. Mobilization of glycogen in salivary glands is important for the process of secretion. Two sets of experiments were carried out, that is, in the first, the rats received drinking water supplemented with LiCl (38,25 and 12 mM of LiCl for 15 days) and the second experiment was carried out by intraperitoneal injection of LiCl solution (12 mg/kg and 45 mg LiCl/kg body weight) for 3 days. The active form of glycogen phosphorylase was not affected by treatment with LiCl considering the two experiments. The active form of glycogen synthase presented higher activity in the submandibular glands of rats treated with 25 and 38 mM LiCl and in the liver, with 25 mM LiCl. Glycogen level was higher than that of control in the submandibular glands of rats receiving 38 and 12 mM LiCl, in the parotid of rats receiving 25 and 38 mM, and in the liver of rats receiving 12 mM LiCl. The absolute value of glycogen for the submandibular treated with 25 mM LiCl, and the liver treated with 38 mM LiCl, was higher than the control value, although not statistically significant for these tissues. No statistically significant difference was found in the submandibular and parotid salivary glands for protein concentration when comparing experimental and control groups. We concluded that LiCl administered to rats influences the metabolism of glycogen in salivary glands.

  16. Neurons have an active glycogen metabolism that contributes to tolerance to hypoxia

    PubMed Central

    Saez, Isabel; Duran, Jordi; Sinadinos, Christopher; Beltran, Antoni; Yanes, Oscar; Tevy, María F; Martínez-Pons, Carlos; Milán, Marco; Guinovart, Joan J

    2014-01-01

    Glycogen is present in the brain, where it has been found mainly in glial cells but not in neurons. Therefore, all physiologic roles of brain glycogen have been attributed exclusively to astrocytic glycogen. Working with primary cultured neurons, as well as with genetically modified mice and flies, here we report that—against general belief—neurons contain a low but measurable amount of glycogen. Moreover, we also show that these cells express the brain isoform of glycogen phosphorylase, allowing glycogen to be fully metabolized. Most importantly, we show an active neuronal glycogen metabolism that protects cultured neurons from hypoxia-induced death and flies from hypoxia-induced stupor. Our findings change the current view of the role of glycogen in the brain and reveal that endogenous neuronal glycogen metabolism participates in the neuronal tolerance to hypoxic stress. PMID:24569689

  17. Four cases of type 1 diabetes mellitus showing sharp serum transaminase increases and hepatomegaly due to glycogenic hepatopathy.

    PubMed

    Ikarashi, Yuichi; Kogiso, Tomomi; Hashimoto, Etsuko; Yamamoto, Kuniko; Kodama, Kazuhisa; Taniai, Makiko; Torii, Nobuyuki; Takaike, Hiroko; Uchigata, Yasuko; Tokushige, Katsutoshi

    2017-03-01

    Poorly controlled diabetes mellitus (DM) patients sometimes show serum transaminase elevations due to steatohepatitis. However, we experienced four cases with type 1 DM with sharp elevations in serum transaminases that could not be explained by steatohepatitis alone and showed bright liver. They were diagnosed with glycogenic hepatopathy (GH) clinicopathologically. The four patients had a median age of 22.5 years (range, 19-29 years) and 12.5 (4-15)-year histories of type 1 DM and showed marked increases in serum transaminases (aspartate aminotransferase, 698 U/L [469-2763 U/L]; alanine transaminase, 255 U/L [216-956 U/L]). Diabetes mellitus control was poor and hemoglobin A1c was 12.7% (11-16.5%). Three cases had a past history of diabetic ketoacidosis. Hepatomegaly and hyperdense liver were seen on computed tomography scans. Magnetic resonance imaging showed low intensity in T2-weighted images. The pathological findings revealed pale and swollen hepatocytes and glycogenated nuclei. The architecture of the liver was preserved, and steatosis and fibrosis were mild. The cytoplasm of hepatocytes stained densely positive with periodic acid-Schiff, and the positive staining disappeared after diastase digestion, suggesting glycogen deposition. No other cause of hepatitis was evident, and the diagnosis was GH. Elevated transaminases improved within 1 month with good glycemic control. Transaminase elevations were observed several times in three cases with poor glycemic control. Glycogenic hepatopathy is rare, but extremely high serum elevations of transaminases are important to identify clinically. Despite showing a good clinical course in general, GH sometimes recurs and requires strict glycemic control. Clinicians should be aware of and recognize GH when dealing with uncontrolled DM patients.

  18. Hormetic modulation of hepatic insulin sensitivity by advanced glycation end products.

    PubMed

    Fabre, Nelly T; Thieme, Karina; Silva, Karolline S; Catanozi, Sérgio; Cavaleiro, Ana Mercedes; Pinto, Danilo A C; Okamoto, Maristela M; Morais, Mychel Raony P T; Falquetto, Bárbara; Zorn, Telma M; Machado, Ubiratan F; Passarelli, Marisa; Correa-Giannella, Maria Lúcia

    2017-05-15

    Because of the paucity of information regarding metabolic effects of advanced glycation end products (AGEs) on liver, we evaluated effects of AGEs chronic administration in (1) insulin sensitivity; (2) hepatic expression of genes involved in AGEs, glucose and fat metabolism, oxidative stress and inflammation and; (3) hepatic morphology and glycogen content. Rats received intraperitoneally albumin modified (AlbAGE) or not by advanced glycation for 12 weeks. AlbAGE induced whole-body insulin resistance concomitantly with increased hepatic insulin sensitivity, evidenced by activation of AKT, inactivation of GSK3, increased hepatic glycogen content, and decreased expression of gluconeogenesis genes. Additionally there was reduction in hepatic fat content, in expression of lipogenic, pro-inflamatory and pro-oxidative genes and increase in reactive oxygen species and in nuclear expression of NRF2, a transcription factor essential to cytoprotective response. Although considered toxic, AGEs become protective when administered chronically, stimulating AKT signaling, which is involved in cellular defense and insulin sensitivity.

  19. Estradiol stimulates glycogen synthesis whereas progesterone promotes glycogen catabolism in the uterus of the American mink (Neovison vison).

    PubMed

    Bowman, Kole; Rose, Jack

    2017-01-01

    Glycogen synthesis by mink uterine glandular and luminal epithelia (GE and LE) is stimulated by estradiol (E2 ) during estrus. Subsequently, the glycogen deposits are mobilized to near completion to meet the energy requirements of pre-embryonic development and implantation by as yet undetermined mechanisms. We hypothesized that progesterone (P4 ) was responsible for catabolism of uterine glycogen reserves as one of its actions to ensure reproductive success. Mink were treated with E2 , P4 or vehicle (controls) for 3 days and uteri collected 24 h (E2 , P4 and vehicle) and 96 h (E2 ) later. To evaluate E2 priming, mink were treated with E2 for 3 days, then P4 for an additional 3 days (E2 →P4 ) and uteri collected 24 h later. Percent glycogen content of uterine epithelia was greater at E2 + 96 h (GE = 5.71 ± 0.55; LE = 11.54 ± 2.32) than E2 +24 h (GE = 3.63 ± 0.71; LE = 2.82 ± 1.03), and both were higher than controls (GE = 0.27 ± 0.15; LE = 0.54 ± 0.30; P < 0.05). Treatment as E2 →P4 reduced glycogen content (GE = 0.61 ± 0.16; LE = 0.51 ± 0.13), to levels not different from controls, while concomitantly increasing catabolic enzyme (glycogen phosphorylase m and glucose-6-phosphatase) gene expression and amount of phospho-glycogen synthase protein (inactive) in uterine homogenates. Interestingly, E2 →P4 increased glycogen synthase 1 messenger RNA (mRNA) and hexokinase 1mRNA and protein. Our findings suggest to us that while E2 promotes glycogen accumulation by the mink uterus during estrus and pregnancy, it is P4 that induces uterine glycogen catabolism, releasing the glucose that is essential to support pre-embryonic survival and implantation.

  20. Insulin stimulation of glycogen synthase in cultured human diploid fibroblasts.

    PubMed

    Hidaka, H; Howard, B V; Kosmakos, F C; Fields, R M; Craig, J W; Bennett, P H; Larner, J

    1980-10-01

    The effect of insulin on glycogen synthase activity in human diploid fibroblasts has been studied. As little as 2 X 10(-10) M insulin increased the glycogen synthase / activity without changing the total activity. Stimulation occurred within 5 min and became maximal in 30 min. A half-maximal increase of / activity was achieved at 3 X 10(-9) M insulin. Glucose starvation increased the magnitude of response of glycogen synthase to insulin but did not change the insulin concentration necessary to give a half-maximal stimulation. Glucose increased the basal level of / activity in human diploid fibroblasts; the effect of insulin was additive. During in vitro senescence the total glycogen synthase activity declined, but the concentration of insulin that produced a half-maximal stimulation remained unchanged. These data indicate that regulation of glycogen synthase activity in human diploid fibroblasts is responsive to physiologic insulin levels and that the system provides a useful model for the in vitro study of insulin sensitivity.

  1. Mechanisms limiting glycogen storage in muscle during prolonged insulin stimulation

    SciTech Connect

    Richter, E.A.; Hansen, S.A.; Hansen, B.F. )

    1988-11-01

    The extent to which muscle glycogen concentrations can be increased during exposure to maximal insulin concentrations and abundant glucose was investigated in the isolated perfused rat hindquarter preparation. Perfusion for 7 h in the presence of 20,000 {mu}U/ml insulin and 11-13 mM glucose increased muscle glycogen concentrations to maximal values 2, 3, and 3.5 times above normal fed levels in fast-twitch white, slow-twitch red, and fast-twitch red fibers, respectively. Glucose uptake decreased from 34.9 {mu}mol{center dot}g{sup {minus}1}{center dot}h{sup {minus}1} at 0 h to 7.5 after 7 h of perfusion. During the perfusion muscle glycogen synthase activity decreased and free intracellular glucose and glucose 6-phosphate increased indicating that glucose disposal was impaired. However, glucose transport as measured by the uptake of 3-O-({sup 14}C)methyl-D-glucose was also markedly decreased after 5 and 7 h of perfusion compared with initial values. Total muscle water concentration decreased during glycogen loading of the muscles. Mechanisms limiting glycogen storage under maximal insulin stimulation include impaired insulin-stimulated membrane transport of glucose as well as impaired intracellular glucose disposal.

  2. Potential Contribution of Cytochrome P450 2B6 to Hepatic 4-Hydroxycyclophosphamide Formation In Vitro and In VivoS⃞

    PubMed Central

    Raccor, Brianne S.; Claessens, Adam J.; Dinh, Jean C.; Park, Julie R.; Hawkins, Douglas S.; Thomas, Sushma S.; Makar, Karen W.; McCune, Jeannine S.

    2012-01-01

    Results from retrospective studies on the relationship between cytochrome P450 (P450) 2B6 (CYP2B6) genotype and cyclophosphamide (CY) efficacy and toxicity in adult cancer patients have been conflicting. We evaluated this relationship in children, who have faster CY clearance and receive different CY-based regimens than adults. These factors may influence the P450s metabolizing CY to 4-hydroxycyclophosphamide (4HCY), the principal precursor to CY's cytotoxic metabolite. Therefore, we sought to characterize the in vitro and in vivo roles of hepatic CYP2B6 and its main allelic variants in 4HCY formation. CYP2B6 is the major isozyme responsible for 4HCY formation in recombinant P450 Supersomes. In human liver microsomes (HLM), 4HCY formation correlated with known phenotypic markers of CYP2B6 activity, specifically formation of (S)-2-ethyl-1,5-dimethyl-3,3-diphenyl pyrrolidine and hydroxybupropion. However, in HLM, CYP3A4/5 also contributes to 4HCY formation at the CY concentrations similar to plasma concentrations achieved in children (0.1 mM). 4HCY formation was not associated with CYP2B6 genotype at low (0.1 mM) or high (1 mM) CY concentrations potentially because CYP3A4/5 and other isozymes also form 4HCY. To remove this confounder, 4HCY formation was evaluated in recombinant CYP2B6 enzymes, which demonstrated that 4HCY formation was lower for CYP2B6.4 and CYP2B6.5 compared with CYP2B6.1. In vivo, CYP2B6 genotype was not directly related to CY clearance or ratio of 4HCY/CY areas under the curve in 51 children receiving CY-based regimens. Concomitant chemotherapy agents did not influence 4HCY formation in vitro. We conclude that CYP2B6 genotype is not consistently related to 4HCY formation in vitro or in vivo. PMID:21976622

  3. Time-dependent effect of ethanol force-feeding on glycogen repletion: NMR evidence of a link with ATP turnover in rat liver.

    PubMed

    Beauvieux, Marie-Christine; Gin, Henri; Roumes, Hélène; Kassem, Cendrella; Couzigou, Patrice; Gallis, Jean-Louis

    2015-09-01

    The purpose was to study the hepatic effects of low-dose ethanol on the links between ATP and glycogen production. Fasted male Wistar rats received a single force-feeding of glucose plus ethanol or isocaloric glucose. At different times after force-feeding (0-10 h), glycogen repletion and ATP characteristics (content, apparent catalytic time constant, mitochondrial turnover) were monitored by (13)C- or (31)P-nuclear magnetic resonance (NMR) in perfused and isolated liver. In vivo glycogen repletion after force-feeding was slower after glucose plus ethanol vs. glucose (12.04 ± 0.68 and 8.50 ± 0.86 μmol/h/g liver wet weight [ww], respectively), reaching a maximum at the 6th hour. From the 3rd to the 8th hour, glycogen content was lower after glucose plus ethanol vs. glucose. After glucose plus ethanol, the correlation between glycogen and ATP contents presented two linear steps: before and after the 3rd hour (30 and 102 μmol glycogen/g ww per μmol ATP/g ww, respectively, the latter being near the single step measured in glucose). After glucose plus ethanol, ATP turnover remained stable for 2 h, was 3-fold higher from the 3rd hour to the 8th hour, and was higher than after glucose (2.59 ± 0.45 and 1.39 ± 0.19 μmol/min/g ww, respectively). In the 1st hour, glucose plus ethanol induced a transient acidosis and an increase in the phosphomonoesters signal. In conclusion, after ethanol consumption, a large part of the ATP production was diverted to redox re-equilibrium during the first 2 h, thereby reducing the glycogen synthesis. Thereafter, the maintenance of a large oxidative phosphorylation allowed the stimulation of glycogen synthesis requiring ATP.

  4. Hepatitis B and HIV

    MedlinePlus

    ... Problems : Hepatitis B Subscribe Translate Text Size Print Hepatitis B What is Hepatitis? Hepatitis means inflammation of the liver. This condition ... our related pages, Hepatitis A and Hepatitis C . Hepatitis B and HIV About 10% of people living ...

  5. A functional glycogen biosynthesis pathway in Lactobacillus acidophilus: expression and analysis of the glg operon.

    PubMed

    Goh, Yong Jun; Klaenhammer, Todd R

    2013-09-01

    Glycogen metabolism contributes to energy storage and various physiological functions in some prokaryotes, including colonization persistence. A role for glycogen metabolism is proposed on the survival and fitness of Lactobacillus acidophilus, a probiotic microbe, in the human gastrointestinal environment. L. acidophilus NCFM possesses a glycogen metabolism (glg) operon consisting of glgBCDAP-amy-pgm genes. Expression of the glg operon and glycogen accumulation were carbon source- and growth phase-dependent, and were repressed by glucose. The highest intracellular glycogen content was observed in early log-phase cells grown on trehalose, which was followed by a drastic decrease of glycogen content prior to entering stationary phase. In raffinose-grown cells, however, glycogen accumulation gradually declined following early log phase and was maintained at stable levels throughout stationary phase. Raffinose also induced an overall higher temporal glg expression throughout growth compared with trehalose. Isogenic ΔglgA (glycogen synthase) and ΔglgB (glycogen-branching enzyme) mutants are glycogen-deficient and exhibited growth defects on raffinose. The latter observation suggests a reciprocal relationship between glycogen synthesis and raffinose metabolism. Deletion of glgB or glgP (glycogen phosphorylase) resulted in defective growth and increased bile sensitivity. The data indicate that glycogen metabolism is involved in growth maintenance, bile tolerance and complex carbohydrate utilization in L. acidophilus.

  6. Hepatitis A

    MedlinePlus

    ... transaminase enzyme levels Treatment There is no specific treatment for hepatitis A. You should rest when the symptoms are ... and have not had hepatitis A or the hepatitis A vaccine. Common reasons for getting one or both of these treatments include: You live with someone who has hepatitis ...

  7. Structural basis of AMPK regulation by adenine nucleotides and glycogen

    SciTech Connect

    Li, Xiaodan; Wang, Lili; Zhou, X. Edward; Ke, Jiyuan; de Waal, Parker W.; Gu, Xin; Tan, M. H. Eileen; Wang, Dongye; Wu, Donghai; Xu, H. Eric; Melcher, Karsten

    2014-11-21

    AMP-activated protein kinase (AMPK) is a central cellular energy sensor and regulator of energy homeostasis, and a promising drug target for the treatment of diabetes, obesity, and cancer. Here we present low-resolution crystal structures of the human α1β2γ1 holo-AMPK complex bound to its allosteric modulators AMP and the glycogen-mimic cyclodextrin, both in the phosphorylated (4.05 Å) and non-phosphorylated (4.60 Å) state. In addition, we have solved a 2.95 Å structure of the human kinase domain (KD) bound to the adjacent autoinhibitory domain (AID) and have performed extensive biochemical and mutational studies. Altogether, these studies illustrate an underlying mechanism of allosteric AMPK modulation by AMP and glycogen, whose binding changes the equilibria between alternate AID (AMP) and carbohydrate-binding module (glycogen) interactions.

  8. Structural basis of AMPK regulation by adenine nucleotides and glycogen

    DOE PAGES

    Li, Xiaodan; Wang, Lili; Zhou, X. Edward; ...

    2014-11-21

    AMP-activated protein kinase (AMPK) is a central cellular energy sensor and regulator of energy homeostasis, and a promising drug target for the treatment of diabetes, obesity, and cancer. Here we present low-resolution crystal structures of the human α1β2γ1 holo-AMPK complex bound to its allosteric modulators AMP and the glycogen-mimic cyclodextrin, both in the phosphorylated (4.05 Å) and non-phosphorylated (4.60 Å) state. In addition, we have solved a 2.95 Å structure of the human kinase domain (KD) bound to the adjacent autoinhibitory domain (AID) and have performed extensive biochemical and mutational studies. Altogether, these studies illustrate an underlying mechanism of allostericmore » AMPK modulation by AMP and glycogen, whose binding changes the equilibria between alternate AID (AMP) and carbohydrate-binding module (glycogen) interactions.« less

  9. Significant modulation of the hepatic proteome induced by exposure to low temperature in Xenopus laevis

    PubMed Central

    Nagasawa, Kazumichi; Tanizaki, Yuta; Okui, Takehito; Watarai, Atsuko; Ueda, Shinobu; Kato, Takashi

    2013-01-01

    Summary The African clawed frog, Xenopus laevis, is an ectothermic vertebrate that can survive at low environmental temperatures. To gain insight into the molecular events induced by low body temperature, liver proteins were evaluated at the standard laboratory rearing temperature (22°C, control) and a low environmental temperature (5°C, cold exposure). Using nano-flow liquid chromatography coupled with tandem mass spectrometry, we identified 58 proteins that differed in abundance. A subsequent Gene Ontology analysis revealed that the tyrosine and phenylalanine catabolic processes were modulated by cold exposure, which resulted in decreases in hepatic tyrosine and phenylalanine, respectively. Similarly, levels of pyruvate kinase and enolase, which are involved in glycolysis and glycogen synthesis, were also decreased, whereas levels of glycogen phosphorylase, which participates in glycogenolysis, were increased. Therefore, we measured metabolites in the respective pathways and found that levels of hepatic glycogen and glucose were decreased. Although the liver was under oxidative stress because of iron accumulation caused by hepatic erythrocyte destruction, the hepatic NADPH/NADP ratio was not changed. Thus, glycogen is probably utilized mainly for NADPH supply rather than for energy or glucose production. In conclusion, X. laevis responds to low body temperature by modulating its hepatic proteome, which results in altered carbohydrate metabolism. PMID:24167716

  10. Effect of local cold application on glycogen recovery.

    PubMed

    Tucker, T J; Slivka, D R; Cuddy, J S; Hailes, W S; Ruby, B C

    2012-04-01

    The purpose of this study was to investigate the effect of local cold application on muscle glycogen re-synthesis after exercise. Recreationally active male subjects (n=11) completed a 90-minute glycogen depleting ride, followed by 4 h of recovery. During recovery, ice was applied intermittently to one leg (IL) while the subjects other leg (CL) acted as a control. Intramuscular and rectal temperature was recorded continuously. A carbohydrate (1.8 g∙kg-1 bodyweight) beverage was supplied at 0 and 2 h post exercise. Muscle biopsies were taken immediately after exercise from the vastus lateralis and at 4 h post exercise for the analysis of muscle glycogen and muscle lactate. Leg circumference was measured 30, 60, 120, 180, and 240 minutes into recovery. The IL was colder than the CL from 15 minutes after initial ice application until the end recovery (P<0.05). Immediate post-exercise glycogen was similar between legs (55.3±7.4 vs. 56.1±7 mmol∙kg-1 wet weight for the iced vs. control, respectively). However, muscle glycogen was lower in the IL compared to the CL at 4 h post exercise (72±8.4 vs. 95±8.4 mmol∙kg-1 wet weight, respectively; P<0.05). Muscle lactate was lower in the IL after 4 h of recovery compared to the CL (1.6±.2 vs. 2.6±.2 mmol∙L-1, respectively; P<0.05). There was no difference in circumference between IL and CL. These data demonstrate a reduction in muscle glycogen re-synthesis with local cold application.

  11. Applications of mutant yeast strains with low glycogen storage capability

    NASA Technical Reports Server (NTRS)

    Petersen, G. R.; Schubert, W. W.; Stokes, B. O.

    1981-01-01

    Several strains of Hansenula polymorpha were selected for possible low glycogen storage characteristics based on a selective I2 staining procedure. The levels of storage carbohydrates in the mutant strains were found to be 44-70% of the levels in the parent strain for cultures harvested in stationary phase. Similar differences generally were not found for cells harvested in exponential phase. Yeast strains deficient in glycogen storage capability are valuable in increasing the relative protein value of microbial biomass and also may provide significant cost savings in substrate utilization in fermentative processes.

  12. Structural Mechanism of Laforin Function in Glycogen Dephosphorylation and Lafora Disease

    PubMed Central

    Raththagala, Madushi; Brewer, M. Kathryn; Parker, Matthew W.; Sherwood, Amanda R.; Wong, Brian K.; Hsu, Simon; Bridges, Travis M.; Paasch, Bradley C.; Hellman, Lance M.; Husodo, Satrio; Meekins, David A.; Taylor, Adam O.; Turner, Benjamin D.; Auger, Kyle D.; Dukhande, Vikas V.; Chakravarthy, Srinivas; Sanz, Pascual; Woods, Virgil V.; Li, Sheng; Vander Kooi, Craig W.; Gentry, Matthew S.

    2015-01-01

    SUMMARY Glycogen is the major mammalian glucose storage cache and is critical for energy homeostasis. Glycogen synthesis in neurons must be tightly controlled, due to neuronal sensitivity to perturbations in glycogen metabolism. Lafora disease (LD) is a fatal, congenital, neurodegenerative epilepsy. Mutations in the gene encoding the glycogen phosphatase laforin result in hyperphosphorylated glycogen that forms water-insoluble inclusions called Lafora bodies (LBs). LBs induce neuronal apoptosis and are the causative agent of LD. The mechanism of glycogen dephosphorylation by laforin and dysfunction in LD is unknown. We report the crystal structure of laforin bound to phosphoglucan product, revealing its unique integrated tertiary and quaternary structure. Structure-guided mutagenesis combined with biophysical and biochemical analyses reveal the basis for normal function of laforin in glycogen metabolism. Analyses of LD patient mutations define the mechanism by which subsets of mutations disrupt laforin function. These data provide fundamental insights connecting glycogen metabolism to neurodegenerative disease. PMID:25544560

  13. Adipose tissue glycogen accumulation is associated with obesity-linked inflammation in humans

    PubMed Central

    Ceperuelo-Mallafré, Victòria; Ejarque, Miriam; Serena, Carolina; Duran, Xavier; Montori-Grau, Marta; Rodríguez, Miguel Angel; Yanes, Oscar; Núñez-Roa, Catalina; Roche, Kelly; Puthanveetil, Prasanth; Garrido-Sánchez, Lourdes; Saez, Enrique; Tinahones, Francisco J.; Garcia-Roves, Pablo M.; Gómez-Foix, Anna Ma; Saltiel, Alan R.; Vendrell, Joan; Fernández-Veledo, Sonia

    2015-01-01

    Objective Glycogen metabolism has emerged as a mediator in the control of energy homeostasis and studies in murine models reveal that adipose tissue might contain glycogen stores. Here we investigated the physio(patho)logical role of glycogen in human adipose tissue in the context of obesity and insulin resistance. Methods We studied glucose metabolic flux of hypoxic human adipoctyes by nuclear magnetic resonance and mass spectrometry-based metabolic approaches. Glycogen synthesis and glycogen content in response to hypoxia was analyzed in human adipocytes and macrophages. To explore the metabolic effects of enforced glycogen deposition in adipocytes and macrophages, we overexpressed PTG, the only glycogen-associated regulatory subunit (PP1-GTS) reported in murine adipocytes. Adipose tissue gene expression analysis was performed on wild type and homozygous PTG KO male mice. Finally, glycogen metabolism gene expression and glycogen accumulation was analyzed in adipose tissue, mature adipocytes and resident macrophages from lean and obese subjects with different degrees of insulin resistance in 2 independent cohorts. Results We show that hypoxia modulates glucose metabolic flux in human adipocytes and macrophages and promotes glycogenesis. Enforced glycogen deposition by overexpression of PTG re-orients adipocyte secretion to a pro-inflammatory response linked to insulin resistance and monocyte/lymphocyte migration. Furthermore, glycogen accumulation is associated with inhibition of mTORC1 signaling and increased basal autophagy flux, correlating with greater leptin release in glycogen-loaded adipocytes. PTG-KO mice have reduced expression of key inflammatory genes in adipose tissue and PTG overexpression in M0 macrophages induces a pro-inflammatory and glycolytic M1 phenotype. Increased glycogen synthase expression correlates with glycogen deposition in subcutaneous adipose tissue of obese patients. Glycogen content in subcutaneous mature adipocytes is associated

  14. Insights into glycogen metabolism in Lactobacillus acidophilus: impact on carbohydrate metabolism, stress tolerance and gut retention.

    PubMed

    Goh, Yong Jun; Klaenhammer, Todd R

    2014-11-20

    In prokaryotic species equipped with glycogen metabolism machinery, the co-regulation of glycogen biosynthesis and degradation has been associated with the synthesis of energy storage compounds and various crucial physiological functions, including global cellular processes such as carbon and nitrogen metabolism, energy sensing and production, stress response and cell-cell communication. In addition, the glycogen metabolic pathway was proposed to serve as a carbon capacitor that regulates downstream carbon fluxes, and in some microorganisms the ability to synthesize intracellular glycogen has been implicated in host persistence. Among lactobacilli, complete glycogen metabolic pathway genes are present only in select species predominantly associated with mammalian hosts or natural environments. This observation highlights the potential involvement of glycogen biosynthesis in probiotic activities and persistence of intestinal lactobacilli in the human gastrointestinal tract. In this review, we summarize recent findings on (i) the presence and potential ecological distribution of glycogen metabolic pathways among lactobacilli, (ii) influence of carbon substrates and growth phases on glycogen metabolic gene expression and glycogen accumulation in L. acidophilus, and (iii) the involvement of glycogen metabolism on growth, sugar utilization and bile tolerance. Our present in vivo studies established the significance of glycogen biosynthesis on the competitive retention of L. acidophilus in the mouse intestinal tract, demonstrating for the first time that the ability to synthesize intracellular glycogen contributes to gut fitness and retention among probiotic microorganisms.

  15. Proline-serine-threonine phosphatase-interacting protein 2 (PSTPIP2), a host membrane-deforming protein, is critical for membranous web formation in hepatitis C virus replication.

    PubMed

    Chao, Ti-Chun; Su, Wen-Chi; Huang, Jing-Ying; Chen, Yung-Chia; Jeng, King-Song; Wang, Horng-Dar; Lai, Michael M C

    2012-02-01

    Hepatitis C virus (HCV) reorganizes intracellular membranes to establish sites of replication. How viral and cellular proteins target, bind, and rearrange specific membranes into the replication factory remains a mystery. We used a lentivirus-based RNA interference (RNAi) screening approach to identify the potential cellular factors that are involved in HCV replication. A protein with membrane-deforming activity, proline-serine-threonine phosphatase-interacting protein 2 (PSTPIP2), was identified as a potential factor. Knockdown of PSTPIP2 in HCV subgenomic replicon-harboring and HCV-infected cells was associated with the reduction of HCV protein and RNA expression. PSTPIP2 was localized predominantly in detergent-resistant membranes (DRMs), which contain the RNA replication complex. PSTPIP2 knockdown caused a significant reduction of the formation of HCV- and NS4B-induced membranous webs. A PSTPIP2 mutant defective in inducing membrane curvature failed to support HCV replication, confirming that the membrane-deforming ability of PSTPIP2 is essential for HCV replication. Taking these results together, we suggest that PSTPIP2 facilitates membrane alterations and is a key player in the formation of the membranous web, which is the site of the HCV replication complex.

  16. Role of the thymus in streptococcal cell wall-induced arthritis and hepatic granuloma formation. Comparative studies of pathology and cell wall distribution in athymic and euthymic rats.

    PubMed Central

    Allen, J B; Malone, D G; Wahl, S M; Calandra, G B; Wilder, R L

    1985-01-01

    Systemic administration of an aqueous suspension of group A streptococcal cell wall fragments to susceptible rats induces acute and chronic polyarthritis, as well as noncaseating hepatic granulomas. To gain insight into the role of the thymus in the pathogenesis of this experimental model, pathologic responses and cell wall tissue distribution were compared in congenitally athymic rats (rnu/rnu) and their euthymic littermates (NIH/rnu). Within 24 h, both rat strains developed acute arthritis, characterized by polymorphonuclear leukocytic exudate in the synovium and joint spaces. This acute process was maximal at day 3 and gradually subsided. Beginning 2-3 wk after injection, the euthymic, but not the athymic, rats developed the typical exacerbation of arthritis, characterized by synovial cell hyperplasia with villus formation and T helper/inducer lymphocyte-rich mononuclear cell infiltration. This process eventually resulted in marginal erosions and destruction of periarticular bone and cartilage. Parallel development of acute and chronic hepatic lesions was observed. Bacterial cell wall antigen distribution and persistence were similar in the athymic and euthymic rats. Cell wall antigens were demonstrated in the cytoplasm of cells within subchondral bone marrow, synovium, liver, and spleen, coincident with the development of the acute lesions, and persisted in these sites, although in decreasing amounts, for the duration of the experiment. Our findings provide evidence that the acute and chronic phases of the experimental model are mechanistically distinct. The thymus and functional thymus derived-lymphocytes appear not to be required for the development of the acute exudative disease but are essential for the development of chronic proliferative and erosive disease. Induction of disease is dependent upon cell wall dissemination to and persistence in the affected tissues. Images PMID:3876354

  17. Fluorescent primuline derivatives inhibit hepatitis C virus NS3-catalyzed RNA unwinding, peptide hydrolysis and viral replicase formation.

    PubMed

    Ndjomou, Jean; Kolli, Rajesh; Mukherjee, Sourav; Shadrick, William R; Hanson, Alicia M; Sweeney, Noreena L; Bartczak, Diana; Li, Kelin; Frankowski, Kevin J; Schoenen, Frank J; Frick, David N

    2012-11-01

    The hepatitis C virus (HCV) multifunctional nonstructural protein 3 (NS3) is a protease that cleaves viral and host proteins and a helicase that separates DNA and RNA structures in reactions fueled by ATP hydrolysis. Li et al. (2012) recently synthesized a series of new NS3 helicase inhibitors from the benzothiazole dimer component of the fluorescent yellow dye primuline. This study further characterizes a subset of these primuline derivatives with respect to their specificity, mechanism of action, and effect on cells harboring HCV subgenomic replicons. All compounds inhibited DNA and RNA unwinding catalyzed by NS3 from different HCV genotypes, but only some inhibited the NS3 protease function, and few had any effect on HCV NS3 catalyzed ATP hydrolysis. A different subset contained potent inhibitors of RNA stimulated ATP hydrolysis catalyzed by the related NS3 protein from Dengue virus. In assays monitoring intrinsic protein fluorescence in the absence of nucleic acids, the compounds cooperatively bound NS3 with K(d)s that reflect their potency in assays. The fluorescent properties of the primuline derivatives both in vitro and in cells are also described. The primuline derivative that was the most active against subgenomic replicons in cells caused a 14-fold drop in HCV RNA levels (IC(50)=5±2μM). In cells, the most effective primuline derivative did not inhibit the cellular activity of NS3 protease but disrupted HCV replicase structures.

  18. AAV vector-mediated reversal of hypoglycemia in canine and murine glycogen storage disease type Ia.

    PubMed

    Koeberl, Dwight D; Pinto, Carlos; Sun, Baodong; Li, Songtao; Kozink, Daniel M; Benjamin, Daniel K; Demaster, Amanda K; Kruse, Meghan A; Vaughn, Valerie; Hillman, Steven; Bird, Andrew; Jackson, Mark; Brown, Talmage; Kishnani, Priya S; Chen, Yuan-Tsong

    2008-04-01

    Glycogen storage disease type Ia (GSD-Ia) profoundly impairs glucose release by the liver due to glucose-6-phosphatase (G6Pase) deficiency. An adeno-associated virus (AAV) containing a small human G6Pase transgene was pseudotyped with AAV8 (AAV2/8) to optimize liver tropism. Survival was prolonged in 2-week-old G6Pase (-/-) mice by 600-fold fewer AAV2/8 vector particles (vp), in comparison to previous experiments involving this model (2 x 10(9) vp; 3 x 10(11) vp/kg). When the vector was pseudotyped with AAV1, survival was prolonged only at a higher dose (3 x 10(13) vp/kg). The AAV2/8 vector uniquely prevented hypoglycemia during fasting and fully corrected liver G6Pase deficiency in GSD-Ia mice and dogs. The AAV2/8 vector has prolonged survival in three GSD-Ia dogs to >11 months, which validated this strategy in the large animal model for GSD-Ia. Urinary biomarkers, including lactate and 3-hydroxybutyrate, were corrected by G6Pase expression solely in the liver. Glycogen accumulation in the liver was reduced almost to the normal level in vector-treated GSD-Ia mice and dogs, as was the hepatocyte growth factor (HGF) in GSD-Ia mice. These preclinical data demonstrated the efficacy of correcting hepatic G6Pase deficiency, and support the further preclinical development of AAV vector-mediated gene therapy for GSD-Ia.

  19. Regulation of glycogen content in rat pineal gland by norepinephrine.

    PubMed

    Eugenín, E A; Sáez, C G; Garcés, G; Sáez, J C

    1997-06-20

    In the rat pineal gland the glycogen stores were cytochemically localized in astrocytes and pinealocytes. Moreover, it was found that norepinephrine (NE) induced a time- and concentration-dependent reduction in pineal glycogen content and yielded lactic acid. The NE effect was prevented by blocking alpha1- but not alpha2 or beta-adrenoceptors. Activation of alpha2-adrenoceptors induced a small decrease in glycogen levels that could have pre- and postsynaptic components. Activation of beta-adrenoceptors with 10(-12)-10(-3) M isoproterenol (ISO) induced a bell shape concentration-response curve, presumably due to desensitization, since the response induced by 10(-4) M ISO was greater with shorter period of stimulation. On the other hand, activation of alpha1-adrenoceptors with 10(-12)-10(-3) M phenylephrine (PHN) induced a hyperbolic concentration-response curve with a maximum at concentrations above 10(-8) M. Moreover, treatment with ISO drastically reduced the response induced by PHN concentrations lower but not higher than 10(-6) M, favoring a concentration-dependent response between 10(-6) and 10(-4) M PHN, similar to that induced by equimolar NE concentrations. Thus, the NE-induced reduction in glycogen content of the rat pineal gland is mainly mediated by alpha1-adrenoceptors and modulated by intracellular mechanisms activated by beta-adrenoceptors.

  20. Nrf2-Mediated Regulation of Skeletal Muscle Glycogen Metabolism

    PubMed Central

    Yagishita, Yoko; Katsuoka, Fumiki; Kitajima, Yasuo; Nunomiya, Aki; Nagatomi, Ryoichi; Pi, Jingbo; Biswal, Shyam S.

    2016-01-01

    Nrf2 (NF-E2-related factor 2) contributes to the maintenance of glucose homeostasis in vivo. Nrf2 suppresses blood glucose levels by protecting pancreatic β cells from oxidative stress and improving peripheral tissue glucose utilization. To elucidate the molecular mechanisms by which Nrf2 contributes to the maintenance of glucose homeostasis, we generated skeletal muscle (SkM)-specific Keap1 knockout (Keap1MuKO) mice that express abundant Nrf2 in their SkM and then examined Nrf2 target gene expression in that tissue. In Keap1MuKO mice, blood glucose levels were significantly downregulated and the levels of the glycogen branching enzyme (Gbe1) and muscle-type PhKα subunit (Phka1) mRNAs, along with those of the glycogen branching enzyme (GBE) and the phosphorylase b kinase α subunit (PhKα) protein, were significantly upregulated in mouse SkM. Consistent with this result, chemical Nrf2 inducers promoted Gbe1 and Phka1 mRNA expression in both mouse SkM and C2C12 myotubes. Chromatin immunoprecipitation analysis demonstrated that Nrf2 binds the Gbe1 and Phka1 upstream promoter regions. In Keap1MuKO mice, muscle glycogen content was strongly reduced and forced GBE expression in C2C12 myotubes promoted glucose uptake. Therefore, our results demonstrate that Nrf2 induction in SkM increases GBE and PhKα expression and reduces muscle glycogen content, resulting in improved glucose tolerance. Our results also indicate that Nrf2 differentially regulates glycogen metabolism in SkM and the liver. PMID:27044864

  1. Chronic central leptin infusion modulates the glycemia response to insulin administration in male rats through regulation of hepatic glucose metabolism.

    PubMed

    Burgos-Ramos, Emma; Canelles, Sandra; Rodríguez, Amaia; Gómez-Ambrosi, Javier; Frago, Laura M; Chowen, Julie A; Frühbeck, Gema; Argente, Jesús; Barrios, Vicente

    2015-11-05

    Leptin and insulin use overlapping signaling mechanisms to modify hepatic glucose metabolism, which is critical in maintaining normal glycemia. We examined the effect of an increase in central leptin and insulin on hepatic glucose metabolism and its influence on serum glucose levels. Chronic leptin infusion increased serum leptin and reduced hepatic SH-phosphotyrosine phosphatase 1, the association of suppressor of cytokine signaling 3 to the insulin receptor in liver and the rise in glycemia induced by central insulin. Leptin also decreased hepatic phosphoenolpyruvate carboxykinase levels and increased insulin's ability to phosphorylate insulin receptor substrate-1, Akt and glycogen synthase kinase on Ser9 and to stimulate glucose transporter 2 and glycogen levels. Peripheral leptin treatment reproduced some of these changes, but to a lesser extent. Our data indicate that leptin increases the hepatic response to a rise in insulin, suggesting that pharmacological manipulation of leptin targets may be of interest for controlling glycemia.

  2. Hepatitis C: Treatment

    MedlinePlus

    ... Public Home » Hepatitis C » Hepatitis C Treatment Viral Hepatitis Menu Menu Viral Hepatitis Viral Hepatitis Home For ... Enter ZIP code here Enter ZIP code here Hepatitis C Treatment for Veterans and the Public Treatment ...

  3. Hepatitis A

    MedlinePlus

    ... an inflammation of the liver. One type, hepatitis A, is caused by the hepatitis A virus (HAV). The disease spreads through contact with ... washed in untreated water Putting into your mouth a finger or object that came into contact with ...

  4. Hepatitis B

    MedlinePlus

    ... commonly used with viral hepatitis and related conditions. Web Resources American Liver Foundation A national nonprofit organization ... other liver diseases through research, education, and advocacy. Web site features a database directory of hepatitis clinical ...

  5. Hepatitis B

    MedlinePlus

    ... this page: //medlineplus.gov/ency/article/000279.htm Hepatitis B To use the sharing features on this page, please enable JavaScript. Hepatitis B is irritation and swelling (inflammation) of the ...

  6. Autoimmune hepatitis

    MedlinePlus

    Lupoid hepatitis; Chronic acute liver disease ... This form of hepatitis is an autoimmune disease . The body's immune system cannot tell the difference between healthy body tissue and harmful, outside ...

  7. Hepatitis B

    MedlinePlus

    ... times more infectious than HIV. Which adults need hepatitis B vaccine? Any sexually active adult who is not in ... share needles, syringes, or other drug-injection equipment. Hepatitis B vaccine is available alone or in a combination with ...

  8. Direct pathway for hepatic glycogenesis predominates in meal-fed rats

    SciTech Connect

    Huang, M.T.; Veech, R.L.

    1987-05-01

    The pathway for hepatic glycogen synthesis in the postprandial state was studied in meal-fed rats chronically cannulated in the portal vein. The rate of glycogen synthesis in livers of rats meal-fed for seven days was found to be about 1 umol/g/min. Plasma glucose concentration in the portal vein was generally below 8 mM before meal-feeding and could reach up to 12 mM at the end of the meal-feeding. Studies on the hepatic-portal (H-P) difference of plasma glucose showed that liver released glucose in the fasted state and could either extract or release glucose after feeding, depending on plasma glucose concentration in the portal vein. The cross-over concentration for the transition was found to be 8 mM. The relative importance of the direct vs indirect pathway for the replenishment of hepatic glycogen was determined by injecting (3-/sup 3/H,U-/sup 14/C)-glucose into the portal vein at the end of meal-feeding. Six minutes after the injection, the ratio of /sup 3/H//sup 14/C in glycogen-glucose was found to be 83-92% of the ratio in liver free glucose. The H-P differences of glucose, lactate, pyruvate, and alanine during feeding were determined. It was found that the H-P difference of (glc) was about 9 times greater than the combined total of ..delta.. (lac), ..delta.. (pyr), and ..delta.. (ala) as early as 10 minutes after the onset of feeding. It is concluded that the direct pathway for the replenishment of hepatic glycogen is predominant and can account for more than 80% of the total glycogen synthesized in vivo in the postprandial state, in contrast to the result of < 30% reported previously by Newgard et al in acute traumatized rats.

  9. Mutations in the liver glycogen synthase gene in children with hypoglycemia due to glycogen storage disease type 0.

    PubMed Central

    Orho, M; Bosshard, N U; Buist, N R; Gitzelmann, R; Aynsley-Green, A; Blümel, P; Gannon, M C; Nuttall, F Q; Groop, L C

    1998-01-01

    Glycogen storage disease type 0 (GSD-0) is a rare form of fasting hypoglycemia presenting in infancy or early childhood and accompanied by high blood ketones and low alanine and lactate concentrations. Although feeding relieves symptoms, it often results in postprandial hyperglycemia and hyperlactatemia. The glycogen synthase (GS) activity has been low or immeasurable in liver biopsies, whereas the liver glycogen content has been only moderately decreased. To investigate whether mutations in the liver GS gene (GYS2) on chromosome 12p12.2 were involved in GSD-0, we determined the exon-intron structure of the GYS2 gene and examined nine affected children from five families for linkage of GSD-0 to the GYS2 gene. Mutation screening of the 16 GYS2 exons was done by single-strand conformational polymorphism (SSCP) and direct sequencing. Liver GS deficiency was diagnosed from liver biopsies (GS activity and glycogen content). GS activity in the liver of the affected children was extremely low or nil, resulting in subnormal glycogen content. After suggestive linkage to the GYS2 gene had been established (LOD score = 2.9; P < 0.01), mutation screening revealed several different mutations in these families, including a premature stop codon in exon 5 (Arg246X), a 5'-donor splice site mutation in intron 6 (G+1T--> CT), and missense mutations Asn39Ser, Ala339Pro, His446Asp, Pro479Gln, Ser483Pro, and Met491Arg. Seven of the affected children carried mutations on both alleles. The mutations could not be found in 200 healthy persons. Expression of the mutated enzymes in COS7 cells indicated severely impaired GS activity. In conclusion, the results demonstrate that GSD-0 is caused by different mutations in the GYS2 gene. PMID:9691087

  10. Physiological and drug-induced changes in the glycogen content of mouse brain

    PubMed Central

    Hutchins, D. A.; Rogers, K. J.

    1970-01-01

    1. The effect of the method of killing on the concentration of glycogen in mouse brain was determined. The cerebral glycogen content of mice killed by immersion in liquid nitrogen did not differe significantly from that of animals decapitated and the heads immediately frozen. A delay before freezing led to the rapid loss of brain glycogen, with a 17% fall at 10 s and an 82% loss after 5 min. 2. Hyperglycaemia, induced by the administration of D-glucose, resulted in an 8·3% loss of brain glycogen after 120 min. Insulin hypoglycaemia produced a 10·7% fall in glycogen at 60 min followed by an 11·2% increase at 120 min. 3. Exposure to either high (32° C) or low (10° C) ambient temperatures caused a depletion of brain glycogen. 4. A circadian rhythm of brain glycogen concentration was found, with a nadir which was coincident with the peak of locomotor activity and body temperature. 5. Drugs from several pharmacological classes were studied for their in vivo effect on the concentration of glycogen in mouse brain. 6. Brain glycogen was increased by all the depressant drugs tested, and by some drugs which had little effect on behaviour (diphenhydramine, phenytoin and propranolol), or which caused excitation (caffeine and nialamide). 7. Glycogen was depleted only by amphetamine-like compounds or by bemegride-induced convulsions. 8. The results are discussed with particular reference to the possible relation between catecholamines and glycogen metabolism in the brain. PMID:5420149

  11. Technical note: A method for isolating glycogen granules from ruminal protozoa for further characterization.

    PubMed

    Hall, Mary Beth

    2016-03-01

    Evaluation of physical, chemical, and enzymatic hydrolysis characteristics of protozoal glycogen is best performed on a pure substrate to avoid interference from other cell components. A method for isolating protozoal glycogen granules without use of detergents or other potentially contaminating chemicals was developed. Rumen inoculum was incubated anerobically in vitro with glucose. Glycogen-laden protozoa produced in the fermentation, primarily isotrichids, were allowed to sediment in a separatory funnel and were dispensed. The protozoa were processed through repeated centrifugations and sonication to isolate glycogen granules largely free of feed and cellular debris. The final water-insoluble lyophilized product analyzed as 98.3% α-glucan with very rare starch granules and 1.9% protein. Observed losses of glycogen granules during the clean-up process indicate that this procedure should not be used for quantitative assessment of protozoal glycogen from fermentations. Further optimization of this procedure to enhance the amount of glycogen obtained per fermentation may be possible.

  12. THE LOCALIZATION OF GLYCOGEN IN THE SPERMATOZOA OF VARIOUS INVERTEBRATE AND VERTEBRATE SPECIES

    PubMed Central

    Anderson, Winston A.; Personne, Paul

    1970-01-01

    With the periodic acid-thiosemicarbazide-silver proteinate procedure for the detection of polysaccharides in thin sections, glycogen is localized in the cavities of centrioles and basal bodies, within the axoneme (and surrounding it), in mitochondria, and in the "packing" cytoplasm of the middle piece of spermatozoa of several invertebrate and vertebrate species. The cytochemical localization of glycogen is verified by extraction with α-amylase solution. These findings establish the existence of stored glycogen in sperm. The polysaccharide presumably serves as an endogenous source of energy in the absence of extracellular metabolites, under either aerobic or anaerobic conditions. Other hypotheses on the physiological significance of intracellular glycogen stores in sperm are discussed. Sperm that store glycogen contain some enzymes of glycogen metabolism. In the presence of glucose-1-phosphate, ATP, and Mg++ ions, an amylophosphorylase catalyzes the in vivo synthesis of glycogen. The newly formed product resembles γ-particles, and is digestible with α-amylase. PMID:5409463

  13. Glycogen in the Nervous System. I; Methods for Light and Electron Microscopy

    NASA Technical Reports Server (NTRS)

    Estable, Rosita F. De; Estable-Puig, J. F.; Miquel, J.

    1964-01-01

    'l'he relative value of different methods for combined light and electron microscopical studies of glycogen in the nervous tissue was investigated. Picroalcoholic fixatives preserve glycogen in a considerable amount but give an inadequate morphological image of glycogen distribution and are unsuitable for ultrastructural studies. Fixation by perfusion, with Dalton's chromeosmic fluid seems adequate for ultrastructural cytochemistry of glycogen. Furthermore it permits routine paraffin embedding of brain slices adjacent to those used for electron microscopy. Dimedone blocking is a necessary step for a selective staining of glycogen with PAS after osmic fixation. Enzymatic removal of glycogen in osmic fixed nervous tissue can be done In paraffin-embedded tissue. It can also be performed in glycolmethacrylate-embedded tissue without removal of the embedding medium. Paraphenylenediamine stains glycogen following periodic acid oxidation.

  14. Hepatitis C

    MedlinePlus

    ... an inflammation of the liver. One type, hepatitis C, is caused by the hepatitis C virus (HCV). It usually spreads through contact with ... childbirth. Most people who are infected with hepatitis C don't have any symptoms for years. If ...

  15. Exercise training-induced adaptations associated with increases in skeletal muscle glycogen content.

    PubMed

    Manabe, Yasuko; Gollisch, Katja S C; Holton, Laura; Kim, Young-Bum; Brandauer, Josef; Fujii, Nobuharu L; Hirshman, Michael F; Goodyear, Laurie J

    2013-02-01

    Chronic exercise training results in numerous skeletal muscle adaptations, including increases in insulin sensitivity and glycogen content. To understand the mechanism leading to increased muscle glycogen, we studied the effects of exercise training on glycogen regulatory proteins in rat skeletal muscle. Female Sprague Dawley rats performed voluntary wheel running for 1, 4 or 7 weeks. After 7 weeks of training, insulin-stimulated glucose uptake was increased in epitrochlearis muscle. As compared with sedentary control rats, muscle glycogen did not change after 1 week of training, but increased significantly after 4 and 7 weeks. The increases in muscle glycogen were accompanied by elevated glycogen synthase activity and protein expression. To assess the regulation of glycogen synthase, we examined its major activator, protein phosphatase 1 (PP1), and its major deactivator, glycogen synthase kinase (GSK)-3. Consistent with glycogen synthase activity, PP1 activity was unchanged after 1 week of training but significantly increased after 4 and 7 weeks of training. Protein expression of R(GL)(G(M)), another regulatory PP1 subunit, significantly decreased after 4 and 7 weeks of training. Unlike PP1 activity, GSK-3 phosphorylation did not follow the pattern of glycogen synthase activity. The ~ 40% decrease in GSK-3α phosphorylation after 1 week of exercise training persisted until 7 weeks, and may function as a negative feedback mechanism in response to elevated glycogen. Our findings suggest that exercise training-induced increases in muscle glycogen content could be regulated by multiple mechanisms, including enhanced insulin sensitivity, glycogen synthase expression, allosteric activation of glycogen synthase, and PP1 activity.

  16. Body mass dependence of glycogen stores in the anoxia-tolerant crucian carp ( Carassius carassius L.)

    NASA Astrophysics Data System (ADS)

    Vornanen, Matti; Asikainen, Juha; Haverinen, Jaakko

    2011-03-01

    Glycogen is a vital energy substrate for anaerobic organisms, and the size of glycogen stores can be a limiting factor for anoxia tolerance of animals. To this end, glycogen stores in 12 different tissues of the crucian carp ( Carassius carassius L.), an anoxia-tolerant fish species, were examined. Glycogen content of different tissues was 2-10 times higher in winter (0.68-18.20% of tissue wet weight) than in summer (0.12-4.23%). In scale, bone and brain glycogen stores were strongly dependent on body mass (range between 0.6 and 785 g), small fish having significantly more glycogen than large fish ( p < 0.05). In fin and skin, size dependence was evident in winter, but not in summer, while in other tissues (ventricle, atrium, intestine, liver, muscle, and spleen), no size dependence was found. The liver was much bigger in small than large fish ( p < 0.001), and there was a prominent enlargement of the liver in winter irrespective of fish size. As a consequence, the whole body glycogen reserves, measured as a sum of glycogen from different tissues, varied from 6.1% of the body mass in the 1-g fish to 2.0% in the 800-g fish. Since anaerobic metabolic rate scales down with body size, the whole body glycogen reserves could provide energy for approximately 79 and 88 days of anoxia in small and large fish, respectively. There was, however, a drastic difference in tissue distribution of glycogen between large and small fish: in the small fish, the liver was the major glycogen store (68% of the stores), while in the large fish, the white myotomal muscle was the principal deposit of glycogen (57%). Since muscle glycogen is considered to be unavailable for blood glucose regulation, its usefulness in anoxia tolerance of the large crucian carp might be limited, although not excluded. Therefore, mobilization of muscle glycogen under anoxia needs to be rigorously tested.

  17. Early events in the generation of autophagosomes are required for the formation of membrane structures involved in hepatitis C virus genome replication.

    PubMed

    Mohl, Bjorn-Patrick; Bartlett, Christopher; Mankouri, Jamel; Harris, Mark

    2016-03-01

    Hepatitis C virus (HCV) infection has been shown to induce autophagy but the mechanisms underpinning this process remain to be elucidated. Induction of autophagy requires the class III phosphatidylinositol 3-kinase, Vps34, which produces phosphatidylinositol 3-phosphate (PI3P) within the endoplasmic reticulum (ER) membrane. This recruits proteins with PI3P binding domains such as the double-FYVE-containing protein 1 (DFCP1). DFCP1 generates cup-shaped protrusions from the ER membrane, termed omegasomes, which provide a platform for the production of autophagosomes. Here we present data demonstrating that both Vps34 and DFCP1 are required for HCV genome replication, in the context of both a subgenomic replicon and virus infection, but did not affect virus entry or initial translation. Using live cell fluorescence microscopy we demonstrated that early during HCV infection the nascent viral genome replication complexes (identified by using non-structural protein NS5A as a marker) transiently colocalize with DFCP1-positive punctae (omegasomes), before the two structures move apart from each other. This observation is reminiscent of the transient association of LC3 and DFCP1 during omegasome formation, and therefore we propose that omegasomes are utilized by HCV to generate the double-membrane vesicles which are the hallmark of HCV replication complexes.

  18. Novel Swelling-Resistant Sodium Alginate Membrane Branching Modified by Glycogen for Highly Aqueous Ethanol Solution Pervaporation.

    PubMed

    Ji, Chen-Hao; Xue, Shuang-Mei; Xu, Zhen-Liang

    2016-10-12

    A novel carbohydrate chain cross-linking method of sodium alginate (SA) is proposed in which glycogen with the branched-chain structure is utilized to cross-link with SA matrix by the bridging of glutaraldehyde (GA). The active layer of SA composite ceramic membrane modified by glycogen and GA for pervaporation (PV) demonstrates great advantages. The branched structure increases the chain density of the active layer, which compresses the free volume between the carbohydrate chains of SA. Large amounts of hydroxyl groups are consumed during the reaction with GA, which reduces the hydrogen bond formation between water molecules and the polysaccharide matrix. The two factors benefit the active layer with great improvement in swelling resistance, promoting the potential of the active layer for the dehydration of an ethanol-water solution containing high water content. Meanwhile, the modified active layer is loaded on the rigid α-Al2O3 ceramic membrane by dip-coating method with the enhancement of anti-deformation and controllable thickness of the active layer. Characterization techniques such as SEM, AFM, XRD, FTIR, XPS, and water contact angle are utilized to observe the composite structure and surface morphology of the composite membrane, to probe the free volume variation, and to determine the chemical composition and hydrophilicity difference of the active layer caused by the different glycogen additive amounts. The membrane containing 3% glycogen in the selective layer demonstrates the flux at 1250 g m(-2) h(-1) coupled with the separation factor of 187 in the 25 wt % water content feed solution at the operating temperature of 75 °C, reflecting superior pervaporation processing capacity compared with the general organic PV membranes in the same condition.

  19. Glycogen storage disease types I and II: Treatment updates

    PubMed Central

    Kishnani, P. S.; Chen, Y. T.

    2009-01-01

    Summary Prior to 2006 therapy for glycogen storage diseases consisted primarily of dietary interventions, which in the case of glycogen storage disease (GSD) type II (GSD II; Pompe disease) remained essentially palliative. Despite improved survival and growth, long-term complications of GSD type I (GSD I) have not responded to dietary therapy with uncooked cornstarch or continuous gastric feeding. The recognized significant risk of renal disease and liver malignancy in GSD I has prompted efforts towards curative therapy, including organ transplantation, in those deemed at risk. Results of clinical trials in infantile Pompe disease with alglucosidase alfa (Myozyme) showed prolonged survival reversal of cardiomyopathy, and motor gains. This resulted in broad label approval of Myozyme for Pompe disease in 2006. Furthermore, the development of experimental therapies, such as adeno-associated virus (AAV) vector-mediated gene therapy, holds promise for the availability of curative therapy in GSD I and GSD II/Pompe disease in the future. PMID:17308886

  20. Glycogen storage disease types I and II: treatment updates.

    PubMed

    Koeberl, D D; Kishnani, P S; Chen, Y T

    2007-04-01

    Prior to 2006 therapy for glycogen storage diseases consisted primarily of dietary interventions, which in the case of glycogen storage disease (GSD) type II (GSD II; Pompe disease) remained essentially palliative. Despite improved survival and growth, long-term complications of GSD type I (GSD I) have not responded to dietary therapy with uncooked cornstarch or continuous gastric feeding. The recognized significant risk of renal disease and liver malignancy in GSD I has prompted efforts towards curative therapy, including organ transplantation, in those deemed at risk. Results of clinical trials in infantile Pompe disease with alglucosidase alfa (Myozyme) showed prolonged survival reversal of cardiomyopathy, and motor gains. This resulted in broad label approval of Myozyme for Pompe disease in 2006. Furthermore, the development of experimental therapies, such as adeno-associated virus (AAV) vector-mediated gene therapy, holds promise for the availability of curative therapy in GSD I and GSD II/Pompe disease in the future.

  1. Acute myelogenous leukemia and glycogen storage disease 1b.

    PubMed

    Pinsk, Maury; Burzynski, Jeffrey; Yhap, Margaret; Fraser, Robert B; Cummings, Brian; Ste-Marie, Micheline

    2002-12-01

    Glycogen storage disease 1b (GSD 1b) is caused by a deficiency of glucose-6-phosphate translocase and the intracellular accumulation of glycogen. The disease presents with failure to thrive, hepatomegaly, hypoglycemia, lactic acidosis, as well as neutropenia causing increased susceptibility to pyogenic infections. We present a case of a young woman with GSD 1b who developed acute myelogenous leukemia while on long-term granulocyte colony-stimulating factor therapy. The presence of two rare diseases in a single patient raises suspicion that GSD 1b and acute myelogenous leukemia are linked. Surveillance for acute myelogenous leukemia should become part of the long-term follow-up for GSD 1b.

  2. Transition from glycogen to starch metabolism in Archaeplastida.

    PubMed

    Cenci, Ugo; Nitschke, Felix; Steup, Martin; Minassian, Berge A; Colleoni, Christophe; Ball, Steven G

    2014-01-01

    In this opinion article we propose a scenario detailing how two crucial components have evolved simultaneously to ensure the transition of glycogen to starch in the cytosol of the Archaeplastida last common ancestor: (i) the recruitment of an enzyme from intracellular Chlamydiae pathogens to facilitate crystallization of α-glucan chains; and (ii) the evolution of novel types of polysaccharide (de)phosphorylating enzymes from preexisting glycogen (de)phosphorylation host pathways to allow the turnover of such crystals. We speculate that the transition to starch benefitted Archaeplastida in three ways: more carbon could be packed into osmotically inert material; the host could resume control of carbon assimilation from the chlamydial pathogen that triggered plastid endosymbiosis; and cyanobacterial photosynthate export could be integrated in the emerging Archaeplastida.

  3. Dumping syndrome, a cause of acquired glycogenic hepatopathy.

    PubMed

    Resnick, Jeffrey M; Zador, Ivan; Fish, Daryl L

    2011-01-01

    A 2-year-old boy, having undergone fundoplication for gastroesophageal reflux disease and fed by gastrostomy, presented with recurrent emesis, syncope with hypoglycemia, and persistently elevated serum liver transaminase levels. Liver biopsy revealed hepatocellular glycogenosis by light and electron microscopy. Further evaluation showed no evidence of diabetes mellitus, glycogen storage disease, or corticosteroid use. Since the hyperglycemic-hyperinsulinemic state of dumping syndrome would provide a mechanism for hepatocellular glycogenosis, the biopsy findings prompted consideration of dumping syndrome. Metabolic evaluation confirmed the diagnosis of dumping syndrome, and appropriate dietary management led to sustained resolution of symptomatology and hypertransaminasemia. Dumping syndrome is proposed to be a cause of hepatocellular glycogenosis, the latter representing a form of acquired glycogenic hepatopathy.

  4. Pregnancy in women with glycogen storage disease Ia and Ib.

    PubMed

    Ferrecchia, Iris A; Guenette, Ginny; Potocik, Elizabeth A; Weinstein, David A

    2014-01-01

    Over the past 9 decades since glycogen storage disease (GSD) was described, an almost universally fatal disease has become one where women are living well into adulthood and choosing to bear children. This inborn error of metabolism associated with the creation and utilization of glycogen, when untreated, manifests with unrelenting hypoglycemia. The initiation of continuous feeds has improved outcomes, and later in 1982, the administration of intermittent doses of cornstarch in water provided a continuous supply of exogenous glucose. As metabolic control has improved, morbidity has decreased. Glycogen storage disease Ib has the same severity of hypoglycemia as GSD Ia, with associated immune disturbance. Prior to the introduction of granulocyte colony-stimulating factor (G-CSF), infections caused significant mortality in GSD Ib. Pregnancy in patients with GSD Ia and Ib poses unique challenges during gestation and delivery. Good metabolic control before conception and throughout pregnancy is directly related to successful outcomes. There is no nursing literature to date addressing perinatal and neonatal care in this population.

  5. A glycogene mutation map for discovery of diseases of glycosylation

    PubMed Central

    Hansen, Lars; Lind-Thomsen, Allan; Joshi, Hiren J; Pedersen, Nis Borbye; Have, Christian Theil; Kong, Yun; Wang, Shengjun; Sparso, Thomas; Grarup, Niels; Vester-Christensen, Malene Bech; Schjoldager, Katrine; Freeze, Hudson H; Hansen, Torben; Pedersen, Oluf; Henrissat, Bernard; Mandel, Ulla; Clausen, Henrik; Wandall, Hans H; Bennett, Eric P

    2015-01-01

    Glycosylation of proteins and lipids involves over 200 known glycosyltransferases (GTs), and deleterious defects in many of the genes encoding these enzymes cause disorders collectively classified as congenital disorders of glycosylation (CDGs). Most known CDGs are caused by defects in glycogenes that affect glycosylation globally. Many GTs are members of homologous isoenzyme families and deficiencies in individual isoenzymes may not affect glycosylation globally. In line with this, there appears to be an underrepresentation of disease-causing glycogenes among these larger isoenzyme homologous families. However, genome-wide association studies have identified such isoenzyme genes as candidates for different diseases, but validation is not straightforward without biomarkers. Large-scale whole-exome sequencing (WES) provides access to mutations in, for example, GT genes in populations, which can be used to predict and/or analyze functional deleterious mutations. Here, we constructed a draft of a functional mutational map of glycogenes, GlyMAP, from WES of a rather homogenous population of 2000 Danes. We cataloged all missense mutations and used prediction algorithms, manual inspection and in case of carbohydrate-active enzymes family GT27 experimental analysis of mutations to map deleterious mutations. GlyMAP (http://glymap.glycomics.ku.dk) provides a first global view of the genetic stability of the glycogenome and should serve as a tool for discovery of novel CDGs. PMID:25267602

  6. Structural basis for glucose-6-phosphate activation of glycogen synthase

    SciTech Connect

    Baskaran, Sulochanadevi; Roach, Peter J.; DePaoli-Roach, Anna A.; Hurley, Thomas D.

    2010-11-22

    Regulation of the storage of glycogen, one of the major energy reserves, is of utmost metabolic importance. In eukaryotes, this regulation is accomplished through glucose-6-phosphate levels and protein phosphorylation. Glycogen synthase homologs in bacteria and archaea lack regulation, while the eukaryotic enzymes are inhibited by protein kinase mediated phosphorylation and activated by protein phosphatases and glucose-6-phosphate binding. We determined the crystal structures corresponding to the basal activity state and glucose-6-phosphate activated state of yeast glycogen synthase-2. The enzyme is assembled into an unusual tetramer by an insertion unique to the eukaryotic enzymes, and this subunit interface is rearranged by the binding of glucose-6-phosphate, which frees the active site cleft and facilitates catalysis. Using both mutagenesis and intein-mediated phospho-peptide ligation experiments, we demonstrate that the enzyme's response to glucose-6-phosphate is controlled by Arg583 and Arg587, while four additional arginine residues present within the same regulatory helix regulate the response to phosphorylation.

  7. Technical and experimental features of Magnetic Resonance Spectroscopy of brain glycogen metabolism.

    PubMed

    Soares, Ana Francisca; Gruetter, Rolf; Lei, Hongxia

    2016-12-26

    In the brain, glycogen is a source of glucose not only in emergency situations but also during normal brain activity. Altered brain glycogen metabolism is associated with energetic dysregulation in pathological conditions, such as diabetes or epilepsy. Both in humans and animals, brain glycogen levels have been assessed non-invasively by Carbon-13 Magnetic Resonance Spectroscopy ((13)C-MRS) in vivo. With this approach, glycogen synthesis and degradation may be followed in real time, thereby providing valuable insights into brain glycogen dynamics. However, compared to the liver and muscle, where glycogen is abundant, the sensitivity for detection of brain glycogen by (13)C-MRS is inherently low. In this review we focus on strategies used to optimize the sensitivity for (13)C-MRS detection of glycogen. Namely, we explore several technical perspectives, such as magnetic field strength, field homogeneity, coil design, decoupling, and localization methods. Furthermore, we also address basic principles underlying the use of (13)C-labeled precursors to enhance the detectable glycogen signal, emphasizing specific experimental aspects relevant for obtaining kinetic information on brain glycogen.

  8. Enzymatic regulation of seasonal glycogen cycling in the freeze-tolerant wood frog, Rana sylvatica.

    PubMed

    do Amaral, M Clara F; Lee, Richard E; Costanzo, Jon P

    2016-12-01

    Liver glycogen is an important energy store in vertebrates, and in the freeze-tolerant wood frog, Rana sylvatica, this carbohydrate also serves as a major source of the cryoprotectant glucose. We investigated how variation in the levels of the catalytic subunit of protein kinase A (PKAc), glycogen phosphorylase (GP), and glycogen synthase (GS) relates to seasonal glycogen cycling in a temperate (Ohioan) and subarctic (Alaskan) populations of this species. In spring, Ohioan frogs had reduced potential for glycogen synthesis, as evidenced by low GS activity and high PKAc protein levels. In addition, glycogen levels in spring were the lowest of four seasonal samples, as energy input was likely directed towards metabolism and somatic growth during this period. Near-maximal glycogen levels were reached by mid-summer, and remained unchanged in fall and winter, suggesting that glycogenesis was curtailed during this period. Ohioan frogs had a high potential for glycogenolysis and glycogenesis in winter, as evidenced by large glycogen reserves, high levels of GP and GS proteins, and high GS activity, which likely allows for rapid mobilization of cryoprotectant during freezing and replenishing of glycogen reserves during thawing. Alaskan frogs also achieved a near-maximal liver glycogen concentration by summer and displayed high glycogenic and glycogenolytic potential in winter, but, unlike Ohioan frogs, started replenishing their energy reserves early in spring. We conclude that variation in levels of both glycogenolytic and glycogenic enzymes likely happens in response to seasonal changes in energetic strategies and demands, with winter survival being a key component to understanding the regulation of glycogen cycling in this species.

  9. Glycogen Repletion in Brown Adipose Tissue upon Refeeding Is Primarily Driven by Phosphorylation-Independent Mechanisms

    PubMed Central

    Carmean, Christopher M.; Huang, Y. Hanna; Brady, Matthew J.

    2016-01-01

    Glycogen storage in brown adipose tissue (BAT) is generally thought to take place through passive, substrate-driven activation of glycogenesis rather than programmatic shifts favoring or opposing the storage and/or retention of glycogen. This perception exists despite a growing body of evidence suggesting that BAT glycogen storage is actively regulated by covalent modification of key glycogen-metabolic enzymes, protein turnover, and endocrine hormone signaling. Members of one such class of covalent-modification regulators, glycogen-binding Phosphoprotein Phosphatase-1 (PP1)-regulatory subunits (PPP1Rs), targeting PP1 to glycogen-metabolic enzymes, were dynamically regulated in response to 24 hr of starvation and/or 24 hr of starvation followed by ad libitum refeeding. Over-expression of the PPP1R Protein Targeting to Glycogen (PTG), under the control of the aP2 promoter in mice, inactivated glycogen phosphorylase (GP) and enhanced basal- and starvation-state glycogen storage. Total interscapular BAT glycogen synthase and the constitutive activity of GS were conditionally affected. During starvation, glucose-6-phosphate (G-6-P) levels and the relative phosphorylation of Akt (p-Ser-473-Akt) were both increased in PTG-overexpressing (Tg) mice, suggesting that elevated glycogen storage during starvation modifies broader cellular metabolic pathways. During refeeding, Tg and WT mice reaccumulated glycogen similarly despite altered GS and GP activities. All observations during refeeding suggest that the phosphorylation states of GS and GP are not physiologically rate-controlling, despite there being a clear balance of endogenous kinase- and phosphatase activities. The studies presented here reveal IBAT glycogen storage to be a tightly-regulated process at all levels, with potential effects on nutrient sensing in vivo. PMID:27213961

  10. Hepatitis Vaccines

    PubMed Central

    Ogholikhan, Sina; Schwarz, Kathleen B.

    2016-01-01

    Viral hepatitis is a serious health problem all over the world. However, the reduction of the morbidity and mortality due to vaccinations against hepatitis A and hepatitis B has been a major component in the overall reduction in vaccine preventable diseases. We will discuss the epidemiology, vaccine development, and post-vaccination effects of the hepatitis A and B virus. In addition, we discuss attempts to provide hepatitis D vaccine for the 350 million individuals infected with hepatitis B globally. Given the lack of a hepatitis C vaccine, the many challenges facing the production of a hepatitis C vaccine will be shown, along with current and former vaccination trials. As there is no current FDA-approved hepatitis E vaccine, we will present vaccination data that is available in the rest of the world. Finally, we will discuss the existing challenges and questions facing future endeavors for each of the hepatitis viruses, with efforts continuing to focus on dramatically reducing the morbidity and mortality associated with these serious infections of the liver. PMID:26978406

  11. NMR studies of muscle glycogen synthesis in insulin-resistant offspring of parents with non-insulin-dependent diabetes mellitus immediately after glycogen-depleting exercise.

    PubMed Central

    Price, T B; Perseghin, G; Duleba, A; Chen, W; Chase, J; Rothman, D L; Shulman, R G; Shulman, G I

    1996-01-01

    To examine the impact of insulin resistance on the insulin-dependent and insulin-independent portions of muscle glycogen synthesis during recovery from exercise, we studied eight young, lean, normoglycemic insulin-resistant (IR) offspring of individuals with non-insulin-dependent diabetes mellitus and eight age-weight matched control (CON) subjects after plantar flexion exercise that lowered muscle glycogen to approximately 25% of resting concentration. After approximately 20 min of exercise, intramuscular glucose 6-phosphate and glycogen were simultaneously monitored with 31P and 13C NMR spectroscopies. The postexercise rate of glycogen resynthesis was nonlinear. Glycogen synthesis rates during the initial insulin independent portion (0-1 hr of recovery) were similar in the two groups (IR, 15.5 +/- 1.3 mM/hr and CON, 15.8 +/- 1.7 mM/hr); however, over the next 4 hr, insulin-dependent glycogen synthesis was significantly reduced in the IR group [IR, 0.1 +/- 0.5 mM/hr and CON, 2.9 +/- 0.2 mM/hr; (P < or = 0.001)]. After exercise there was an initial rise in glucose 6-phosphate concentrations that returned to baseline after the first hour of recovery in both groups. In summary, we found that following muscle glycogen-depleting exercise, IR offspring of parents with non-insulin-dependent diabetes mellitus had (i) normal rates of muscle glycogen synthesis during the insulin-independent phase of recovery from exercise and (ii) severely diminished rates of muscle glycogen synthesis during the subsequent recovery period (2-5 hr), which has previously been shown to be insulin-dependent in normal CON subjects. These data provide evidence that exercise and insulin stimulate muscle glycogen synthesis in humans by different mechanisms and that in the IR subjects the early response to stimulation by exercise is normal. PMID:8643574

  12. Last step in the conversion of trehalose to glycogen: a mycobacterial enzyme that transfers maltose from maltose 1-phosphate to glycogen.

    PubMed

    Elbein, Alan D; Pastuszak, Irena; Tackett, Alan J; Wilson, Tyler; Pan, Yuan T

    2010-03-26

    We show that Mycobacterium smegmatis has an enzyme catalyzing transfer of maltose from [(14)C]maltose 1-phosphate to glycogen. This enzyme was purified 90-fold from crude extracts and characterized. Maltose transfer required addition of an acceptor. Liver, oyster, or mycobacterial glycogens were the best acceptors, whereas amylopectin had good activity, but amylose was a poor acceptor. Maltosaccharides inhibited the transfer of maltose from [(14)C]maltose-1-P to glycogen because they were also acceptors of maltose, and they caused production of larger sized radioactive maltosaccharides. When maltotetraose was the acceptor, over 90% of the (14)C-labeled product was maltohexaose, and no radioactivity was in maltopentaose, demonstrating that maltose was transferred intact. Stoichiometry showed that 0.89 micromol of inorganic phosphate was produced for each micromole of maltose transferred to glycogen, and 56% of the added maltose-1-P was transferred to glycogen. This enzyme has been named alpha1,4-glucan:maltose-1-P maltosyltransferase (GMPMT). Transfer of maltose to glycogen was inhibited by micromolar amounts of inorganic phosphate or arsenate but was only slightly inhibited by millimolar concentrations of glucose-1-P, glucose-6-P, or inorganic pyrophosphate. GMPMT was compared with glycogen phosphorylase (GP). GMPMT catalyzed transfer of [(14)C]maltose-1-P, but not [(14)C]glucose-1-P, to glycogen, whereas GP transferred radioactivity from glucose-1-P but not maltose-1-P. GMPMT and GP were both inhibited by 1,4-dideoxy-1,4-imino-d-arabinitol, but only GP was inhibited by isofagomine. Because mycobacteria that contain trehalose synthase accumulate large amounts of glycogen when grown in high concentrations of trehalose, we propose that trehalose synthase, maltokinase, and GMPMT represent a new pathway of glycogen synthesis using trehalose as the source of glucose.

  13. Glycogen synthase kinase 3 alpha phosphorylates and regulates the osteogenic activity of Osterix.

    PubMed

    Li, Hongyan; Jeong, Hyung Min; Choi, You Hee; Lee, Sung Ho; Jeong, Hye Gwang; Jeong, Tae Cheon; Lee, Kwang Youl

    2013-05-10

    Osteoblast-specific transcription factor Osterix is a zinc-finger transcription factor that required for osteoblast differentiation and new bone formation. The function of Osterix can be modulated by post-translational modification. Glycogen synthase kinase 3 alpha (GSK3α) is a multifunctional serine/threonine protein kinase that plays a role in the Wnt signaling pathways and is implicated in the control of several regulatory proteins and transcription factors. In the present study, we investigated how GSK3α regulates Osterix during osteoblast differentiation. Wide type GSK3α up-regulated the protein level, protein stability and transcriptional activity of Osterix. These results suggest that GSK3α regulates osteogenic activity of Osterix.

  14. Evaluation of Improved Glycogen Synthase Kinase-3α Inhibitors in Models of Acute Myeloid Leukemia

    PubMed Central

    Neumann, Theresa; Benajiba, Lina; Göring, Stefan; Stegmaier, Kimberly; Schmidt, Boris

    2016-01-01

    The challenge for Glycogen Synthase Kinase-3 (GSK-3) inhibitor design lies in achieving high selectivity for one isoform over the other. The therapy of certain diseases, such as acute myeloid leukemia (AML) may require α-isoform specific targeting. The scorpion shaped GSK-3 inhibitors developed by our group achieved the highest GSK-3α selectivity reported so far, but suffered from insufficient aqueous solubility. This work presents the solubility-driven optimization of our isoform-selective inhibitors using a scorpion shaped lead. Among 15 novel compounds, compound 27 showed high activity against GSK-3α/β with the highest GSK-3α selectivity reported to date. Compound 27 was profiled for bioavailability and toxicity in a zebrafish embryo phenotype assay. Selective GSK-3α targeting in AML cell lines was achieved with compound 27, resulting in a strong differentiation phenotype and colony formation impairment, confirming the potential of GSK-3α inhibition in AML therapy. PMID:26496242

  15. Impact of Macrophage Inflammatory Protein-1α Deficiency on Atherosclerotic Lesion Formation, Hepatic Steatosis, and Adipose Tissue Expansion

    PubMed Central

    Gutierrez, Dario A.; Surmi, Bonnie K.; Orr, Jeb S.; Webb, Corey D.; Hasty, Alyssa H.

    2012-01-01

    Macrophage inflammatory protein-1α (CCL3) plays a well-known role in infectious and viral diseases; however, its contribution to atherosclerotic lesion formation and lipid metabolism has not been determined. Low density lipoprotein receptor deficient (LDLR−/−) mice were transplanted with bone marrow from CCL3−/− or C57BL/6 wild type donors. After 6 and 12 weeks on western diet (WD), recipients of CCL3−/− marrow demonstrated lower plasma cholesterol and triglyceride concentrations compared to recipients of C57BL/6 marrow. Atherosclerotic lesion area was significantly lower in female CCL3−/− recipients after 6 weeks and in male CCL3−/− recipients after 12 weeks of WD feeding (P<0.05). Surprisingly, male CCL3−/− recipients had a 50% decrease in adipose tissue mass after WD-feeding, and plasma insulin, and leptin levels were also significantly lower. These results were specific to CCL3, as LDLR−/− recipients of monocyte chemoattractant protein−/− (CCL2) marrow were not protected from the metabolic consequences of high fat feeding. Despite these improvements in LDLR−/− recipients of CCL3−/− marrow in the bone marrow transplantation (BMT) model, double knockout mice, globally deficient in both proteins, did not have decreased body weight, plasma lipids, or atherosclerosis compared with LDLR−/− controls. Finally, there were no differences in myeloid progenitors or leukocyte populations, indicating that changes in body weight and plasma lipids in CCL3−/− recipients was not due to differences in hematopoiesis. Taken together, these data implicate a role for CCL3 in lipid metabolism in hyperlipidemic mice following hematopoietic reconstitution. PMID:22359597

  16. Feature Hepatitis: Hepatitis Can Strike Anyone

    MedlinePlus

    ... Navigation Bar Home Current Issue Past Issues Feature Hepatitis Hepatitis Can Strike Anyone Past Issues / Spring 2009 Table ... from all walks of life are affected by hepatitis, especially hepatitis C, the most common form of ...

  17. Hepatitis A through E (Viral Hepatitis)

    MedlinePlus

    ... travelers How can hepatitis B be prevented? The hepatitis B vaccine offers the best protection. All infants and unvaccinated ... should receive hepatitis B immune globulin and the hepatitis B vaccine within 12 hours of birth to help prevent ...

  18. Adult Schistosoma mansoni worms positively modulate soluble egg antigen-induced inflammatory hepatic granuloma formation in vivo. Stereological analysis and immunophenotyping of extracellular matrix proteins, adhesion molecules, and chemokines.

    PubMed Central

    Jacobs, W.; Bogers, J.; Deelder, A.; Wéry, M.; Van Marck, E.

    1997-01-01

    Synchronized liver granulomas were induced by injecting Sepharose beads to which SEA soluble egg antigen (SEA) or the concanavalin A binding fraction of SEA had been coupled into a mesenteric vein in naive, single-sex (35 days) and bisexually (28 days) Schistosoma mansoni-infected and Plasmodium berghei-immunized mice. Stereological analysis revealed that peak granuloma formation was already reached 8 days after injection in single-sex infected mice compared with 16 days in naive animals. No difference in granuloma formation between naive and P. berghei-immunized animals and between unisexually and bisexually S. mansoni-infected mice was observed. This suggests that the positive immunomodulatory effect on the granulomogenesis is worm specific and not likely to be due to arousal of the immune system by unrelated factors, nor is it influenced by the gender or degree of maturation of female worms. At all stages in time, the concanavalin A binding-fraction-induced granulomas reached only 65 to 70% of the volume of SEA-induced granulomas. Immunophenotyping of extracellular matrix proteins around deposited heads revealed that fibronectin was the dominant extracellular matrix protein and that also type I and IV collagen and laminin were deposited. Temporal analysis of the expression of the adhesion molecules ICAM-1, LFA-1, VLA-4, and VLA-6 was performed. Morphological evidence is presented for the role of adhesion molecules in the initiation and maintenance of hepatic granuloma formation. The chemokine monocyte chemoattractant protein-1 was expressed in the granuloma and in hepatic artery branches. From these data, it is concluded that adult S. mansoni worms positively modulate schistosomal hepatic granuloma formation in vivo. Adhesion molecules and chemokines play important roles in schistosomal granuloma formation. Images Figure 1 Figure 2 Figure 3 PMID:9176396

  19. Crystal structure of glycogen debranching enzyme and insights into its catalysis and disease-causing mutations

    PubMed Central

    Zhai, Liting; Feng, Lingling; Xia, Lin; Yin, Huiyong; Xiang, Song

    2016-01-01

    Glycogen is a branched glucose polymer and serves as an important energy store. Its debranching is a critical step in its mobilization. In animals and fungi, the 170 kDa glycogen debranching enzyme (GDE) catalyses this reaction. GDE deficiencies in humans are associated with severe diseases collectively termed glycogen storage disease type III (GSDIII). We report crystal structures of GDE and its complex with oligosaccharides, and structure-guided mutagenesis and biochemical studies to assess the structural observations. These studies reveal that distinct domains in GDE catalyse sequential reactions in glycogen debranching, the mechanism of their catalysis and highly specific substrate recognition. The unique tertiary structure of GDE provides additional contacts to glycogen besides its active sites, and our biochemical experiments indicate that they mediate its recruitment to glycogen and regulate its activity. Combining the understanding of the GDE catalysis and functional characterizations of its disease-causing mutations provides molecular insights into GSDIII. PMID:27088557

  20. Effects of genetic and environmental factors on muscle glycogen content in Japanese Black cattle

    PubMed Central

    Komatsu, Tomohiko; Shoji, Noriaki; Saito, Kunihiko; Suzuki, Keiichi

    2014-01-01

    Monosaccharides such as glucose contribute to the development of meat flavor upon heating via the Maillard reaction; therefore, monosaccharide content is related to beef palatability. Here, we analyzed the effects of genetic and environmental factors on the content of glycogen, one of the precursors of monosaccharides, in the muscles of 958 fattened Japanese Black cattle from Yamagata Prefecture. Analysis of variance showed that muscle glycogen content was affected by the farm and postmortem periods, but not by sex, slaughter age, slaughter month or number of days detained at the slaughter yard. Additionally, consumption of digestible brown rice feed elevated muscle glycogen levels. Glycogen heritability was estimated to be 0.34, and genetic correlations between glycogen and carcass weight (CW) or beef marbling standard (BMS) were weak. The predicted breeding values varied among paternal lines. These results demonstrated that genetic factors might improve muscle glycogen content and therefore beef palatability, but do not influence CW or BMS. PMID:24716455

  1. Hepatitis C Test

    MedlinePlus

    ... Hepatitis C Antibody; Anti-HCV; HCV-PCR; HCV-RNA; Hepatitis C Viral Load Formal name: Viral Hepatitis C Antibody Screen; Viral Hepatitis C RNA by PCR; Hepatitis C Virus Genotype Related tests: ...

  2. Alcohol and Hepatitis

    MedlinePlus

    ... Home » Living with Hepatitis » Daily Living: Alcohol Viral Hepatitis Menu Menu Viral Hepatitis Viral Hepatitis Home For ... Alcohol for Veterans and the Public Alcohol and Hepatitis: Entire Lesson Overview Alcohol is one of the ...

  3. Hepatitis C: Clinical Trials

    MedlinePlus

    ... and Public Home » Hepatitis C » Treatment Decisions Viral Hepatitis Menu Menu Viral Hepatitis Viral Hepatitis Home For ... can I find out about participating in a hepatitis C clinical trial? Many trials are being conducted ...

  4. Hepatitis (For Parents)

    MedlinePlus

    ... Old Feeding Your 1- to 2-Year-Old Hepatitis KidsHealth > For Parents > Hepatitis Print A A A ... to Call the Doctor en español Hepatitis About Hepatitis The word hepatitis simply means an inflammation of ...

  5. Travelers' Health: Hepatitis B

    MedlinePlus

    ... Chapter 3 - Hepatitis A Chapter 3 - Hepatitis C Hepatitis B Francisco Averhoff INFECTIOUS AGENT Hepatitis B is ... their exposures. Map 3-04. Prevalence of chronic hepatitis B virus infection among adults PDF Version (printable) ...

  6. Possible mechanism for changes in glycogen metabolism in unloaded soleus muscle

    NASA Technical Reports Server (NTRS)

    Henriksen, E. J.; Tischler, M. E.

    1985-01-01

    Carbohydrate metabolism has been shown to be affected in a number of ways by different models of hypokinesia. In vivo glycogen levels in the soleus muscle are known to be increased by short-term denervation and harness suspension. In addition, exposure to 7 days of hypogravity also caused a dramatic increase in glycogen concentration in this muscle. The biochemical alterations caused by unloading that may bring about these increases in glycogen storage in the soleus were sought.

  7. Detection of human muscle glycogen by natural abundance /sup 13/C NMR

    SciTech Connect

    Avison, M.J.; Rothman, D.L.; Nadel, E.; Shulman, R.G.

    1988-03-01

    Natural abundance /sup 13/C nuclear magnetic resonance spectroscopy was used to detect signals from glycogen in the human gastrocnemius muscle. The reproducibility of the measurement was demonstrated, and the ability to detect dynamic changes was confirmed by measuring a decrease in muscle glycogen levels after exercise and its subsequent repletion. Single frequency gated /sup 1/H decoupling was used to obtain decoupled natural abundance /sup 13/C NMR spectra of the C-1 position of muscle glycogen.

  8. [Beneficial effect of swimming in thermal waters on muscle glycogen depletion].

    PubMed

    D'Amelio, G; Boninsegna, A; Calzavara, M; Bertolini, M

    1991-05-01

    The effect of swimming in the termal water on muscle glycogen stores was studied. After 30 min the muscle glycogen results in a diminution, but it is not depleted. On the contrary, 30 min of swimming in normal water results in a depletion of muscle glycogene stores. The glycemic homeostasis is well maintained in thermal water, and hypoglicemia occurs only after swimming in normal water.

  9. Post-Exercise Muscle Glycogen Repletion in the Extreme: Effect of Food Absence and Active Recovery

    PubMed Central

    Fournier, Paul A.; Fairchild, Timothy J.; Ferreira, Luis D.; Bräu, Lambert

    2004-01-01

    Glycogen plays a major role in supporting the energy demands of skeletal muscles during high intensity exercise. Despite its importance, the amount of glycogen stored in skeletal muscles is so small that a large fraction of it can be depleted in response to a single bout of high intensity exercise. For this reason, it is generally recommended to ingest food after exercise to replenish rapidly muscle glycogen stores, otherwise one’s ability to engage in high intensity activity might be compromised. But what if food is not available? It is now well established that, even in the absence of food intake, skeletal muscles have the capacity to replenish some of their glycogen at the expense of endogenous carbon sources such as lactate. This is facilitated, in part, by the transient dephosphorylation-mediated activation of glycogen synthase and inhibition of glycogen phosphorylase. There is also evidence that muscle glycogen synthesis occurs even under conditions conducive to an increased oxidation of lactate post-exercise, such as during active recovery from high intensity exercise. Indeed, although during active recovery glycogen resynthesis is impaired in skeletal muscle as a whole because of increased lactate oxidation, muscle glycogen stores are replenished in Type IIa and IIb fibers while being broken down in Type I fibers of active muscles. This unique ability of Type II fibers to replenish their glycogen stores during exercise should not come as a surprise given the advantages in maintaining adequate muscle glycogen stores in those fibers that play a major role in fight or flight responses. Key Points Even in the absence of food intake, skeletal muscles have the capacity to replenish some of their glycogen at the expense of endogenous carbon sources such as lactate. During active recovery from exercise, skeletal muscles rich in type II fibers replenish part of their glycogen stores even in the absence of food intake. Post-exercise muscle glycogen synthesis in the

  10. Glycogen supercompensation in rat soleus muscle during recovery from nonweight bearing

    NASA Technical Reports Server (NTRS)

    Henriksen, Erik J.; Kirby, Christopher R.; Tischler, Marc E.

    1989-01-01

    Events leading to the normalization of the glycogen metabolism in the soleus muscle of rat, altered by 72-h three days of hind-limb suspension, were investigated during the 72-h recovery period when the animals were allowed to bear weight on all four limbs. Relative importance of the factors affecting glycogen metabolism in skeletal muscle during the recovery period was also examined. Glycogen concentration was found to decrease within 15 min and up to 2 h of recovery, while muscle glucose 6-phosphate, and the fractional activities of glycogen phosphorylase and glycogen synthase increased. From 2 to 4 h, when the glycogen synthase activity remained elevated and the phosphorylase activity declined, glycogen concentration increased, until it reached maximum values at about 24 h, after which it started to decrease, reaching control values by 72 h. At 12 and 24 h, the inverse relationship between glycogen concentration and the synthase activity ratio was lost, indicating that the reloading transiently uncoupled glycogen control of this enzyme.

  11. Brain glycogen decreases with increased periods of wakefulness: implications for homeostatic drive to sleep.

    PubMed

    Kong, Jiming; Shepel, P Nicolas; Holden, Clark P; Mackiewicz, Mirek; Pack, Allan I; Geiger, Jonathan D

    2002-07-01

    Sleep is thought to be restorative in function, but what is restored during sleep is unclear. Here we tested the hypothesis that increased periods of wakefulness will result in decreased levels of glycogen, the principal energy store in brain, and with recovery sleep levels of glycogen will be replenished, thus representing a homeostatic component of sleep drive. Using a high-energy focused microwave irradiation method to kill animals and thereby snap-inactivate glycogen-producing and -metabolizing enzymes, we determined, with accuracy and precision, levels of brain glycogen and showed these levels to decrease significantly by approximately 40% in brains of rats deprived of sleep for 12 or 24 hr. Recovery sleep of 15 hr duration after 12 hr of sleep deprivation reversed the decreases in glycogen. Using a novel histochemical method to stain brain glycogen, we found glycogen to be concentrated in white matter; this finding was confirmed biochemically in white matter dissected from rats killed with microwave irradiation. Levels of glycogen, as determined histochemically, were significantly decreased in gray and white matter with sleep deprivation, and these decreases were reversed with recovery sleep. The observed decreases in levels of brain glycogen may be a consequence of increased wakefulness and/or a component integral to the homeostatic drive to sleep.

  12. A New Muscle Glycogen Storage Disease Associated with Glycogenin-1 Deficiency

    PubMed Central

    Malfatti, Edoardo; Nilsson, Johanna; Hedberg-Oldfors, Carola; Hernandez-Lain, Aurelio; Michel, Fabrice; Dominguez-Gonzalez, Cristina; Viennet, Gabriel; Akman, H. Orhan; Kornblum, Cornelia; den Bergh, Peter Van; Romero, Norma B.; Engel, Andrew G.; DiMauro, Salvatore; Oldfors, Anders

    2015-01-01

    We describe a slowly progressive myopathy in 7 unrelated adult patients with storage of polyglucosan in muscle fibers. Genetic investigation revealed homozygous or compound heterozygous deleterious variants in the glycogenin-1 gene (GYG1). Most patients showed depletion of glycogenin-1 in skeletal muscle, whereas 1 showed presence of glycogenin-1 lacking the C-terminal that normally binds glycogen synthase. Our results indicate that either depletion of glycogenin-1 or impaired interaction with glycogen synthase underlies this new form of glycogen storage disease that differs from a previously reported patient with GYG1 mutations who showed profound glycogen depletion in skeletal muscle and accumulation of glycogenin-1. PMID:25272951

  13. Sodium tungstate activates glycogen synthesis through a non-canonical mechanism involving G-proteins.

    PubMed

    Zafra, Delia; Nocito, Laura; Domínguez, Jorge; Guinovart, Joan J

    2013-01-31

    Tungstate treatment ameliorates experimental diabetes by increasing liver glycogen deposition through an as yet unidentified mechanism. The signalling mechanism of tungstate was studied in CHOIR cells and primary cultured hepatocytes. This compound exerted its pro-glycogenic effects through a new G-protein-dependent and Tyr-Kinase Receptor-independent mechanism. Chemical or genetic disruption of G-protein signalling prevented the activation of the Ras/ERK cascade and the downstream induction of glycogen synthesis caused by tungstate. Thus, these findings unveil a novel non-canonical signalling pathway that leads to the activation of glycogen synthesis and that could be exploited as an approach to treat diabetes.

  14. A Rare Case of Persistent Lactic Acidosis in the ICU: Glycogenic Hepatopathy and Mauriac Syndrome

    PubMed Central

    Alvarez, George F.

    2016-01-01

    Mauriac syndrome is a rare disorder that can present with the single feature of glycogenic hepatopathy in children and adults with poorly controlled diabetes mellitus. An often underrecognized finding of glycogenic hepatopathy is lactic acidosis and hyperlactatemia. Primary treatment of glycogenic hepatopathy is improved long-term blood glucose control. Resolution of symptoms and hepatomegaly will occur with improvement in hemoglobin A1C. We present here a case of a young adult female presenting to the intensive care unit with Mauriac syndrome. This case demonstrates exacerbation of lactic acidosis in a patient with glycogenic hepatopathy treated for diabetic ketoacidosis with high dose insulin and dextrose. PMID:27699071

  15. Glycogen distribution in the microwave‐fixed mouse brain reveals heterogeneous astrocytic patterns

    PubMed Central

    Baba, Otto; Ashida, Hitoshi; Nakamura, Kouichi C.

    2016-01-01

    In the brain, glycogen metabolism has been implied in synaptic plasticity and learning, yet the distribution of this molecule has not been fully described. We investigated cerebral glycogen of the mouse by immunohistochemistry (IHC) using two monoclonal antibodies that have different affinities depending on the glycogen size. The use of focused microwave irradiation yielded well‐defined glycogen immunoreactive signals compared with the conventional periodic acid‐Schiff method. The IHC signals displayed a punctate distribution localized predominantly in astrocytic processes. Glycogen immunoreactivity (IR) was high in the hippocampus, striatum, cortex, and cerebellar molecular layer, whereas it was low in the white matter and most of the subcortical structures. Additionally, glycogen distribution in the hippocampal CA3‐CA1 and striatum had a ‘patchy’ appearance with glycogen‐rich and glycogen‐poor astrocytes appearing in alternation. The glycogen patches were more evident with large‐molecule glycogen in young adult mice but they were hardly observable in aged mice (1–2 years old). Our results reveal brain region‐dependent glycogen accumulation and possibly metabolic heterogeneity of astrocytes. GLIA 2016;64:1532–1545 PMID:27353480

  16. Characterization of Function of the GlgA2 Glycogen/Starch Synthase in Cyanobacterium sp. Clg1 Highlights Convergent Evolution of Glycogen Metabolism into Starch Granule Aggregation.

    PubMed

    Kadouche, Derifa; Ducatez, Mathieu; Cenci, Ugo; Tirtiaux, Catherine; Suzuki, Eiji; Nakamura, Yasunori; Putaux, Jean-Luc; Terrasson, Amandine Durand; Diaz-Troya, Sandra; Florencio, Francisco Javier; Arias, Maria Cecilia; Striebeck, Alexander; Palcic, Monica; Ball, Steven G; Colleoni, Christophe

    2016-07-01

    At variance with the starch-accumulating plants and most of the glycogen-accumulating cyanobacteria, Cyanobacterium sp. CLg1 synthesizes both glycogen and starch. We now report the selection of a starchless mutant of this cyanobacterium that retains wild-type amounts of glycogen. Unlike other mutants of this type found in plants and cyanobacteria, this mutant proved to be selectively defective for one of the two types of glycogen/starch synthase: GlgA2. This enzyme is phylogenetically related to the previously reported SSIII/SSIV starch synthase that is thought to be involved in starch granule seeding in plants. This suggests that, in addition to the selective polysaccharide debranching demonstrated to be responsible for starch rather than glycogen synthesis, the nature and properties of the elongation enzyme define a novel determinant of starch versus glycogen accumulation. We show that the phylogenies of GlgA2 and of 16S ribosomal RNA display significant congruence. This suggests that this enzyme evolved together with cyanobacteria when they diversified over 2 billion years ago. However, cyanobacteria can be ruled out as direct progenitors of the SSIII/SSIV ancestral gene found in Archaeplastida. Hence, both cyanobacteria and plants recruited similar enzymes independently to perform analogous tasks, further emphasizing the importance of convergent evolution in the appearance of starch from a preexisting glycogen metabolism network.

  17. Contribution of dietary starch to hepatic and systemic carbohydrate fluxes in European seabass (Dicentrarchus labrax L.).

    PubMed

    Viegas, Ivan; Rito, João; Jarak, Ivana; Leston, Sara; Caballero-Solares, Albert; Metón, Isidoro; Pardal, Miguel A; Baanante, Isabel V; Jones, John G

    2015-05-14

    In the present study, the effects of partial substitution of dietary protein by digestible starch on endogenous glucose production were evaluated in European seabass (Dicentrarchus labrax). The fractional contribution of dietary carbohydrates v. gluconeogenesis to blood glucose appearance and hepatic glycogen synthesis was quantified in two groups of seabass fed with a diet containing 30% digestible starch (DS) or without a carbohydrate supplement as the control (CTRL). Measurements were performed by transferring the fish to a tank containing water enriched with 5% (2)H2O over the last six feeding days, and quantifying the incorporation of (2)H into blood glucose and hepatic glycogen by (2)H NMR. For CTRL fish, gluconeogenesis accounted for the majority of circulating glucose while for the DS fish, this contribution was significantly lower (CTRL 85 (SEM 4) % v. DS 54 (SEM 2) %; P < 0.001). Hepatic glycogen synthesis via gluconeogenesis (indirect pathway) was also significantly reduced in the DS fish, in both relative (CTRL 100 (SEM 1) % v. DS 72 (SEM 1) %; P < 0.001) and absolute terms (CTRL 28 (SEM 1) v. DS 17 (sem 1) μmol/kg per h; P < 0.001). A major fraction of the dietary carbohydrates that contributed to blood glucose appearance (33 (sem 1) % of the total 47 (SEM 2) %) had undergone exchange with hepatic glucose 6-phosphate. This indicated the simultaneous activity of hepatic glucokinase and glucose 6-phosphatase. In conclusion, supplementation of digestible starch resulted in a significant reduction of gluconeogenic contributions to systemic glucose appearance and hepatic glycogen synthesis.

  18. Priming Effect of a Morning Meal on Hepatic Glucose Disposition Later in the Day.

    PubMed

    Moore, Mary Courtney; Smith, Marta S; Farmer, Ben; Kraft, Guillaume; Shiota, Masakazu; Williams, Phillip E; Cherrington, Alan D

    2017-02-07

    We used hepatic balance and tracer ((3)H-glucose) techniques to examine the impact of "breakfast" on hepatic glucose metabolism later in the same day. From 0-240 min, 2 groups (n=9 each) of conscious dogs received a duodenal infusion of glucose (GLC) or saline (SAL), then fasted from 240-360 min. Three dogs from each group were euthanized for tissue collection at 360 min. From 360-600 min, the remaining dogs underwent a hyperinsulinemic (4x basal) hyperglycemic clamp (arterial blood glucose 146±2 mg/dL) with portal glucose infusion. The total glucose infusion rate was 14% greater in GLC vs SAL (AUC360-600min 2979±296 vs 2597±277 mg/kg, respectively). The rates (mg(.)kg(-1.)min(-1)) of hepatic glucose uptake (5.8±0.8 vs 3.2±0.3) and glycogen storage (4.7±0.6 vs 2.9±0.3) during the clamp were markedly greater in GLC vs SAL. Hepatic glycogen content was ≈50% greater, glycogen synthase activity was ≈50% greater, glycogen phosphorylase activity was ≈50% lower, and the amount of p-glycogen synthase was 34% lower, indicating activation of the enzyme, in GLC vs. SAL. Thus, morning GLC primed the liver to extract and store more glucose in the presence of hyperinsulinemic hyperglycemia later in the same day, indicating that breakfast enhances the liver's role in glucose disposal in subsequent same-day meals.

  19. Hepatitis A

    MedlinePlus

    ... inflammation of the liver.” This inflammation can be caused by a wide variety of toxins, drugs, and metabolic diseases, as well as infection. There are at least 5 hepatitis viruses. Hepatitis A is contracted when a child eats food or drinks water that is contaminated with the virus or has ...

  20. Hepatitis B

    MedlinePlus

    ... B to come back?Should I get the hepatitis B vaccine?What are the side effects of antiviral medicines?Will my liver ever be normal again? Last Updated: October 1996 This article ... B, hepatitis virus, Interferon alpha-2b, jaundice, Lamivudine, liver ...

  1. Effect of stress on hepatic 11beta-hydroxysteroid dehydrogenase activity and its influence on carbohydrate metabolism.

    PubMed

    Altuna, María Eugenia; Lelli, Sandra Marcela; San Martín de Viale, Leonor C; Damasco, María Cristina

    2006-10-01

    Stress activates the synthesis and secretion of catecholamines and adrenal glucocorticoids, increasing their circulating levels. In vivo, hepatic 11beta-hydroxysteroid dehydrogenase 1 (HSD1) stimulates the shift of 11-dehydrocorticosterone to corticosterone, enhancing active glucocorticoids at tissue level. We studied the effect of 3 types of stress, 1 induced by bucogastric overload with 200 mmol/L HCl causing metabolic acidosis (HCl), the second induced by bucogastric overload with 0.45% NaCl (NaCl), and the third induced by simulated overload (cannula), on the kinetics of hepatic HSD1 of rats and their influence on the activity of the gluconeogenic enzyme phosphoenolpyruvate carboxykinase, glycemia, and glycogen deposition. Compared with unstressed controls, all types of stress significantly increased HSD1 activity (146% cannula, 130% NaCl, and 253% HCl), phosphoenolpyruvate carboxykinase activity (51% cannula, 48% NaCl, and 86% HCl), and glycemia (29% cannula, 30% NaCl, and 41% HCl), but decreased hepatic glycogen (68% cannula, 68% NaCl, and 78% HCl). Owing to these results, we suggest the following events occur when stress is induced: an increase in hepatic HSD1 activity, augmented active glucocorticoid levels, increased gluconeogenesis, and glycemia. Also involved are the multiple events indirectly related to glucocorticoids, which lead to the depletion of hepatic glycogen deposits, thereby contributing to increased glycemia. This new approach shows that stress increments the activity of hepatic HSD1 and suggests that this enzyme could be involved in the development of the Metabolic Syndrome.

  2. Zero-order ultrasensitivity in the regulation of glycogen phosphorylase.

    PubMed Central

    Meinke, M H; Bishop, J S; Edstrom, R D

    1986-01-01

    The activity of glycogen phosphorylase (1,4-alpha-D-glucan:orthophosphate alpha-D-glucosyltransferase, EC 2.4.1.1) is controlled by a cyclic phosphorylation-dephosphorylation process through the action of the interconverting enzymes, phosphorylase b kinase (ATP:phosphorylase-b phosphotransferase, EC 2.7.1.38) and phosphorylase a phosphatase (phosphorylase a phosphohydrolase, EC 3.1.3.17). In muscle tissue, the combined concentration of the activated (phospho-) form, phosphorylase a, and the nonactivated (dephospho-) form, phosphorylase b, is substantially greater than the Km of either of the interconverting enzymes for its phosphorylase substrate. It has been predicted that, under such a set of conditions, a sensitivity amplification will occur for phosphorylase regulation due to the zero-order ultrasensitivity effect [LaPorte, D. C. & Koshland, D. E., Jr. (1983) Nature (London) 305, 286-290]. The sensitivity amplification will enhance the responsiveness of the phosphorylase interconversion cycle to changes in the ratio of activities of the kinase to phosphatase. We have studied the cyclic interconversion process using purified muscle enzymes in steady-state reactions and found that there is an enhancement in the control sensitivity of the process due to the zero-order ultrasensitivity effect. The potential for the in vivo enhancement of sensitivity in glycogen degradation by this effect is discussed. PMID:3458247

  3. Technical note: A method for isolating glycogen granules from ruminal protozoa for further characterization

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Evaluation of physical, compositional, and digestion characteristics of protozoal glycogen is best performed on a pure substrate in order to avoid interference from other cell components. A method for isolating protozoal glycogen without use of detergents was developed. Rumen inoculum was incubated ...

  4. Cinnamon increases liver glycogen in an animal model of insulin resistance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cinnamon, and aqueous polyphenol extracts of cinnamon, improve insulin sensitivity in vitro, and in animal and human studies. Given the relationship between the glucose/insulin system and glycogen metabolism, the objective of this study was to determine the effects of cinnamon on glycogen synthesis...

  5. Glycogen accumulation and degradation by the trichomonads Trichomonas vaginalis and Trichomonas tenax.

    PubMed

    Nielsen, Tyler J; Pradhan, Prajakta; Brittingham, Andrew; Wilson, Wayne A

    2012-01-01

    Several species of trichomonad have been shown to accumulate significant quantities of glycogen during growth, suggesting an important role for this compound in cell physiology. We provide the first analysis of the changes in glycogen content and glycogen phosphorylase activity that occur during in vitro growth of two trichomonad species: Trichomonas vaginalis and Trichomonas tenax. Both species accumulated glycogen following inoculation into fresh medium and utilized this compound during logarithmic growth. Glycogen phosphorylase activity also varied during growth in a species-specific manner. The expression of phosphorylase genes in T. vaginalis remained constant during growth and thus transcriptional control did not explain the observed fluctuations in phosphorylase activity. After cloning, expression, and purification, two recombinant glycogen phosphorylases from T. vaginalis and one recombinant glycogen phosphorylase from T. tenax had robust activity and, in contrast to many other eukaryotic glycogen phosphorylases, did not appear to be regulated by reversible protein phosphorylation. Furthermore, allosteric regulation, if present, was not mediated by compounds known to impact the activity of better characterized phosphorylases.

  6. Glycogen Supercompensation in the Rat Brain After Acute Hypoglycemia is Independent of Glucose Levels During Recovery.

    PubMed

    Duarte, João M N; Morgenthaler, Florence D; Gruetter, Rolf

    2017-01-12

    Patients with diabetes display a progressive decay in the physiological counter-regulatory response to hypoglycemia, resulting in hypoglycemia unawareness. The mechanism through which the brain adapts to hypoglycemia may involve brain glycogen. We tested the hypothesis that brain glycogen supercompensation following hypoglycemia depends on blood glucose levels during recovery. Conscious rats were submitted to hypoglycemia of 2 mmol/L for 90 min and allowed to recover at different glycemia, controlled by means of i.v. glucose infusion. Brain glycogen concentration was elevated above control levels after 24 h of recovery in the cortex, hippocampus and striatum. This glycogen supercompensation was independent of blood glucose levels in the post-hypoglycemia period. In the absence of a preceding hypoglycemia insult, brain glycogen concentrations were unaltered after 24 h under hyperglycemia. In the hypothalamus, which controls peripheral glucose homeostasis, glycogen levels were unaltered. Overall, we conclude that post-hypoglycemia glycogen supercompensation occurs in several brain areas and its magnitude is independent of plasma glucose levels. By supporting brain metabolism during recurrent hypoglycemia periods, glycogen may have a role in the development of hypoglycemia unawareness.

  7. Brain Glycogen Decreases During Intense Exercise Without Hypoglycemia: The Possible Involvement of Serotonin.

    PubMed

    Matsui, Takashi; Soya, Shingo; Kawanaka, Kentaro; Soya, Hideaki

    2015-07-01

    Brain glycogen stored in astrocytes, a source of lactate as a neuronal energy source, decreases during prolonged exercise with hypoglycemia. However, brain glycogen dynamics during exercise without hypoglycemia remain unknown. Since intense exercise increases brain noradrenaline and serotonin as known inducers for brain glycogenolysis, we hypothesized that brain glycogen decreases with intense exercise not accompanied by hypoglycemia. To test this hypothesis, we employed a well-established acute intense exercise model of swimming in rats. Rats swam for fourteen 20 s bouts with a weight equal to 8 % of their body mass and were sacrificed using high-power (10 kW) microwave irradiation to inactivate brain enzymes for accurate detection of brain glycogen and monoamines. Intense exercise did not alter blood glucose, but did increase blood lactate levels. Immediately after exercise, brain glycogen decreased and brain lactate increased in the hippocampus, cerebellum, cortex, and brainstem. Simultaneously, serotonin turnover in the hippocampus and brainstem mutually increased and were associated with decreased brain glycogen. Intense swimming exercise that does not induce hypoglycemia decreases brain glycogen associated with increased brain lactate, implying an importance of glycogen in brain energetics during intense exercise even without hypoglycemia. Activated serotonergic regulation is a possible underlying mechanism for intense exercise-induced glycogenolysis at least in the hippocampus and brainstem.

  8. Effect of tunicamycin on glycogen accumulation in the stratum intermedium and odontoblasts of rat incisor.

    PubMed

    Chardin, H; Septier, D; Lecolle, S; Goldberg, M

    1989-06-01

    Repeated injection of rats with tunicamycin over two days induced a 1- to 5-fold increase in glycogen. This accumulation occurred in the stratum intermedium of the enamel organ and in young secretory odontoblasts. In rats injected over 3 days, the number of glycogen particles was at least 10 times larger than in control rats, and large glycogen accumulations were observed in the cytosol of these two groups of cells. These results were obtained by staining with periodic acid-thiocarbohydrazide and silver proteinate, a specific method for the detection of glycoconjugates containing vic-glycol groups. The existence of a relationship between these local cytosolic accumulations of glycogen and the developmental stage of certain groups of cells was shown by the changes that occurred in glycogen distribution. The present results suggest that the stratum intermedium supplies energy for precursor transport.

  9. Restoration of anabolic deficit and muscle glycogen consumption in competitive orienteering.

    PubMed

    Johansson, C; Tsai, L; Hultman, E; Tegelman, R; Pousette, A

    1990-06-01

    Consumption and restoration of muscle glycogen and changes in anabolic and catabolic steroid hormones were analyzed in five male elite orienteers during and after an orienteering competition. The magnitude of glycogen consumption and pronounced increase in serum-cortisol during the orienteering race reflect the great muscular output demands during forest running. The free testosterone/cortisol ratio was normalized to the initial level within four hours post-exercise. Synchronously, only 25% of the muscle glycogen loss was restored. Within 24 hours post-exercise all runners showed normalized levels of testosterone, cortisol and free testosterone/cortisol ratio. The glycogen content was also restored except in one of the runners. We conclude that daily orienteering competitions per se do not seem to create risks for developing a state of hormonal imbalance or significant decrease in glycogen when the carbohydrate supply is appropriate.

  10. Dichloroacetate inhibits glycolysis and augments insulin-stimulated glycogen synthesis in rat muscle.

    PubMed Central

    Clark, A S; Mitch, W E; Goodman, M N; Fagan, J M; Goheer, M A; Curnow, R T

    1987-01-01

    The decrease in plasma lactate during dichloroacetate (DCA) treatment is attributed to stimulation of lactate oxidation. To determine whether DCA also inhibits lactate production, we measured glucose metabolism in muscles of fed and fasted rats incubated with DCA and insulin. DCA increased glucose-6-phosphate, an allosteric modifier of glycogen synthase, approximately 50% and increased muscle glycogen synthesis and glycogen content greater than 25%. Lactate release fell; inhibition of glycolysis accounted for greater than 80% of the decrease. This was associated with a decrease in intracellular AMP, but no change in citrate or ATP. When lactate oxidation was increased by raising extracellular lactate, glycolysis decreased (r = - 0.91), suggesting that lactate oxidation regulates glycolysis. When muscle lactate production was greatly stimulated by thermal injury, DCA increased glycogen synthesis, normalized glycogen content, and inhibited glycolysis, thereby reducing lactate release. The major effect of DCA on lactate metabolism in muscle is to inhibit glycolysis. PMID:3543056

  11. Effects of organosilicon compounds, bearing molecular substitutions, on mouse liver glycogen

    SciTech Connect

    Gulley, C.

    1987-01-01

    This study was conducted to observe the effects of organosilicon compounds on the liver glycogen levels of Jax Albino mice. Tris(trimethylisilyl) methylcarboxylic acid, hexaphenyldisilane and tris(trimethylsilyl) bromomethane were fed to mice ad libitum in an organosilicon compound-laboratory chow mixture for 3 one week periods. At the ends of each period, the mice were sacrificed, their livers removed, glycogen was extracted, and subjected to acid hydrolysis. The concentration of free glucose units were determined using the 3,5 dinitrosalicylate reagent. Compared with the controls, tris(trimethylsilyl) methylcarboxylic acid caused a slight depletion of liver glycogen. Hexaphenyldisilane caused a greater depletion of the glycogen stores, and tris(trimethylsilyl) bromomethane caused the greatest depletion of the glycogen stores.

  12. Hepatitis A

    MedlinePlus

    ... bowel movements Loss of appetite Low-grade fever Dark urine Joint pain Yellowing of the skin and ... person ingests even tiny amounts of contaminated fecal matter. The hepatitis A virus infects liver cells and ...

  13. Hepatic Encephalopathy

    MedlinePlus Videos and Cool Tools

    ... is a condition that causes temporary worsening of brain function in people with advanced liver disease. When ... travel through your body until they reach your brain, causing mental and physical symptoms of HE. Hepatic ...

  14. Hepatitis E

    MedlinePlus

    ... with a positive-sense, single-stranded ribonucleic acid (RNA) genome. The virus has at least 4 different ... RT-PCR) to detect the hepatitis E virus RNA in blood and/or stool; this assay requires ...

  15. Autoimmune hepatitis.

    PubMed

    Heneghan, Michael A; Yeoman, Andrew D; Verma, Sumita; Smith, Alastair D; Longhi, Maria Serena

    2013-10-26

    Autoimmune hepatitis is a disease of the hepatic parenchyma that can present in acute or chronic forms. In common with many autoimmune diseases, autoimmune hepatitis is associated with non-organ-specific antibodies in the context of hepatic autoimmunity. This dichotomy has made definition of a unifying hypothesis in the pathophysiology of the disease difficult, although data from the past 8 years have drawn attention to the role of regulatory T cells. Several triggers have been identified, and the disease arises in genetically susceptible individuals. Clinical and biochemical remission is achievable in up to 85% of cases. For the remaining patients, alternative immunosuppression strategies are an option. Liver transplantation provides an excellent outcome for patients with acute liver failure or complications of end-stage liver disease, including hepatocellular carcinoma. Variant or overlapping syndromes are worthy of consideration when unexpected disease features arise.

  16. Uterine glycogen metabolism in mink during estrus, embryonic diapause and pregnancy

    PubMed Central

    DEAN, Matthew; HUNT, Jason; MCDOUGALL, Lisa; ROSE, Jack

    2014-01-01

    We have determined uterine glycogen content, metabolizing enzyme expression and activity in the mink, a species that exhibits obligatory embryonic diapause, resulting in delayed implantation. Gross uterine glycogen concentrations were highest in estrus, decreased 50% by diapause and 90% in pregnancy (P ≤ 0.05). Endometrial glycogen deposits, which localized primarily to glandular and luminal epithelia, decreased 99% between estrus and diapause (P ≤ 0.05) and were nearly undetectable in pregnancy. Glycogen synthase and phosphorylase proteins were most abundant in the glandular epithelia. Glycogen phosphorylase activity (total) in uterine homogenates was higher during estrus and diapause, than pregnancy. While glycogen phosphorylase protein was detected during estrus and diapause, glycogen synthase was almost undetectable after estrus, which probably contributed to a higher glycogenolysis / glycogenesis ratio during diapause. Uterine glucose-6-phosphatase 3 gene expression was greater during diapause, when compared to estrus (P ≤ 0.05) and supports the hypothesis that glucose-6-phosphate resulting from phosphorylase activity was dephosphorylated in preparation for export into the uterine lumen. The relatively high amount of hexokinase-1 protein detected in the luminal epithelia during estrus and diapause may have contributed to glucose trapping after endometrial glycogen reserves were depleted. Collectively, our findings suggest to us that endometrial glycogen reserves may be an important source of energy, supporting uterine and conceptus metabolism up to the diapausing blastocyst stage. As a result, the size of uterine glycogen reserves accumulated prior to mating may in part, determine the number of embryos that survive to the blastocyst stage, and ultimately litter size. PMID:25225159

  17. Subcellular distribution of glycogen and decreased tetanic Ca2+ in fatigued single intact mouse muscle fibres.

    PubMed

    Nielsen, Joachim; Cheng, Arthur J; Ørtenblad, Niels; Westerblad, Hakan

    2014-05-01

    In skeletal muscle fibres, glycogen has been shown to be stored at different subcellular locations: (i) between the myofibrils (intermyofibrillar); (ii) within the myofibrils (intramyofibrillar); and (iii) subsarcolemmal. Of these, intramyofibrillar glycogen has been implied as a critical regulator of sarcoplasmic reticulum Ca(2+) release. The aim of the present study was to test directly how the decrease in cytoplasmic free Ca(2+) ([Ca(2+)]i) during repeated tetanic contractions relates to the subcellular glycogen distribution. Single fibres of mouse flexor digitorum brevis muscles were fatigued with 70 Hz, 350 ms tetani given at 2 s (high-intensity fatigue, HIF) or 10 s (low-intensity fatigue, LIF) intervals, while force and [Ca(2+)]i were measured. Stimulation continued until force decreased to 30% of its initial value. Fibres were then prepared for analyses of subcellular glycogen distribution by transmission electron microscopy. At fatigue, tetanic [Ca(2+)]i was reduced to 70 ± 4% and 54 ± 4% of the initial in HIF (P < 0.01, n = 9) and LIF (P < 0.01, n = 5) fibres, respectively. At fatigue, the mean inter- and intramyofibrillar glycogen content was 60-75% lower than in rested control fibres (P < 0.05), whereas subsarcolemmal glycogen was similar to control. Individual fibres showed a good correlation between the fatigue-induced decrease in tetanic [Ca(2+)]i and the reduction in intermyofibrillar (P = 0.051) and intramyofibrillar (P = 0.0008) glycogen. In conclusion, the fatigue-induced decrease in tetanic [Ca(2+)]i, and hence force, is accompanied by major reductions in inter- and intramyofibrillar glycogen. The stronger correlation between decreased tetanic [Ca(2+)]i and reduced intramyofibrillar glycogen implies that sarcoplasmic reticulum Ca(2+) release critically depends on energy supply from the intramyofibrillar glycogen pool.

  18. Hepatitis E.

    PubMed

    Krawczynski, K; Aggarwal, R; Kamili, S

    2000-09-01

    Hepatitis E, previously known as enterically transmitted non-A, non-B hepatitis, is an infectious viral disease with clinical and morphologic features of acute hepatitis. Its causative agent, hepatitis E virus, consists of small, 32- to 34-nm diameter, icosahedral, nonenveloped particles with a single-stranded, positive-sense, 7.5-kb RNA. The virus has two main geographically distinct strains, Asian and Mexican; recently, novel isolates from nonendemic areas and a genetically related swine HEV have been described. HEV is responsible for large epidemics of acute hepatitis and a proportion of sporadic hepatitis cases in the Indian subcontinent, southeast and central Asia, the Middle East, parts of Africa, and Mexico. The virus is excreted in feces and is transmitted predominantly by fecal-oral route, usually through contaminated water. Person-to-person transmission is uncommon. Clinical attack rates are the highest among young adults. Recent evidence suggests that humans with subclinical HEV infection and animals may represent reservoirs of HEV; however, further data are needed. Diagnosis of hepatitis E is usually made by detection of specific IgM antibody, which disappears rapidly over a few months; IgG anti-HEV persists for at least a few years. Clinical illness is similar to other forms of acute viral hepatitis except in pregnant women, in whom illness is particularly severe with a high mortality rate. Subclinical and unapparent infections may occur; however, chronic infection is unknown. No specific treatment is yet available. Use of clean drinking water and proper sanitation is currently the most effective method of prevention. Passive immunization has not been proved to be effective, and recombinant vaccines for travelers to disease-endemic areas and for pregnant women currently are being developed.

  19. Stimulation of glycogen synthesis by insulin in human erythroleukemia cells requires the synthesis of glycosyl-phosphatidylinositol.

    PubMed Central

    Lazar, D F; Knez, J J; Medof, M E; Cuatrecasas, P; Saltiel, A R

    1994-01-01

    Although the insulin-dependent hydrolysis of glycosyl-phosphatidylinositol (GPI) may play an important role in insulin action, an absolute requirement for this glycolipid has not been demonstrated. Human K562 cells were mutated to produce a cell line (IA) incapable of the earliest step in PI glycosylation, the formation of PI-GlcNAc. Another cell line (IVD) was deficient in the deacetylation of PI-GlcNAc to form PI-GlcN and subsequent mannosylated species. Each line was transfected with wild-type human insulin receptors. Similar insulin-stimulated receptor autophosphorylation was observed in all three lines, along with a nearly identical increase in the association of phosphorylated insulin receptor substrate 1 with endogenous PI 3-kinase. Both normal and GPI-defective lines also displayed a similar 2- to 3-fold increase in phosphorylation of the Shc protein and its association with growth factor receptor-bound protein 2 in response to insulin. In contrast to these results, striking differences were noted in insulin-stimulated glycogen synthesis. In normal cells, glycogen synthesis was significantly increased by insulin, whereas no insulin stimulation was observed in GPI-deficient IA cells, and only a trace of stimulation was detected in IVD cells. These results indicate that tyrosine phosphorylation produced by insulin is not dependent on GPI synthesis, and this effect is not sufficient to elicit at least some of the metabolic effects of the hormone. In contrast, GPI synthesis is required for the stimulation of glycogen synthesis by insulin in these cells. These findings support the existence of divergent pathways in the action of insulin. Images PMID:7524086

  20. Hepatitis A Test

    MedlinePlus

    ... AACC products and services. Advertising & Sponsorship: Policy | Opportunities Hepatitis A Testing Share this page: Was this page ... HAV-Ab total; Anti-HAV Formal name: Viral Hepatitis A Antibody Related tests: Hepatitis B Testing ; Hepatitis ...

  1. Travelers' Health: Hepatitis A

    MedlinePlus

    ... 3 - Helminths, Soil-Transmitted Chapter 3 - Hepatitis B Hepatitis A Noele P. Nelson, Trudy V. Murphy INFECTIOUS ... hepatitis/HAV Table 3-02. Vaccines to prevent hepatitis A VACCINE TRADE NAME (MANUFACTURER) AGE (Y) DOSE ...

  2. Hepatitis B Foundation

    MedlinePlus

    ... worldwide 2 Billion People have been infected with Hepatitis B Worldwide The Hepatitis B Foundation is working ... of people living with hepatitis B. Learn About Hepatitis B in 11 Other Languages . Resource Video See ...

  3. Hepatitis A FAQs

    MedlinePlus

    ... Professional Resources Patient Education Resources Quick Links to Hepatitis … A | B | C | D | E Viral Hepatitis Home ... Grantees Policy and Programs Resource Center Viral Hepatitis Hepatitis A Questions and Answers for the Public Recommend ...

  4. Hepatitis (For Parents)

    MedlinePlus

    ... people at risk for contracting hepatitis. But frequent hand washing and good hygiene practices can reduce this risk. ... After Having Hepatitis B? Hepatitis B (HBV) Hepatitis Hand Washing Blood Transfusions Body Piercing Tattoos Contact Us Print ...

  5. Efficacy of helper-dependent adenovirus vector-mediated gene therapy in murine glycogen storage disease type Ia.

    PubMed

    Koeberl, Dwight D; Sun, B; Bird, A; Chen, Y T; Oka, K; Chan, L

    2007-07-01

    Genetic deficiency of glucose-6-phosphatase (G6Pase) underlies glycogen storage disease type Ia (GSD-Ia, also known as von Gierke disease; MIM 232200), an autosomal recessive disorder of metabolism associated with life-threatening hypoglycemia and growth retardation. We tested whether helper-dependent adenovirus (HDAd)-mediated hepatic delivery of G6Pase would lead to prolonged survival and sustained correction of the metabolic abnormalities in G6Pase knockout (KO) mice, a model for a severe form of GSD-Ia. An HDAd vector encoding G6Pase was administered intravenously (2 or 5 x 10(12)vector particles/kg) to 2-week-old (w.o.) G6Pase-KO mice. Following HDAd vector administration survival was prolonged to a median of 7 months, in contrast to untreated affected mice that did not survive past 3 weeks of age. G6Pase levels increased more than tenfold between 3 days and 28 weeks after HDAd injection (P < 0.03). The weights of untreated 2 w.o. G6Pase-KO mice were approximately half those of their unaffected littermates, and treatment stimulated their growth to the size of wild-type mice. Severe hypoglycemia and hypercholesterolemia, which are hallmarks of GSD-Ia both in humans and in mice, were also restored to normalcy by the treatment. Glycogen accumulation in the liver was markedly reduced. The efficacy of HDAd-G6Pase treatment in reversing the physiological and biochemical abnormalities associated with GSD-Ia in affected G6Pase-KO mice justifies further preclinical evaluation in murine and canine models of GSD-Ia.

  6. Enzymatically synthesized glycogen reduces lipid accumulation in diet-induced obese rats.

    PubMed

    Furuyashiki, Takashi; Ogawa, Rui; Nakayama, Yoko; Honda, Kazuhisa; Kamisoyama, Hiroshi; Takata, Hiroki; Yasuda, Michiko; Kuriki, Takashi; Ashida, Hitoshi

    2013-09-01

    Based on a recent study indicating that enzymatically synthesized glycogen (ESG) possesses a dietary, fiber-like action, we hypothesized that ESG can reduce the risk of obesity. In this study, the antiobesity effects of ESG were investigated in a model of diet-induced obesity. Male Sprague-Dawley rats were divided into 4 groups and fed a normal or high-fat diet, with or without 20% ESG, for 4 weeks. Body weight, food intake, lipid deposition in the white adipose tissues and liver, fecal lipid excretion, and plasma lipid profiles were measured. At week 3, the body fat mass was measured using an x-ray computed tomography system, which showed that ESG significantly suppressed the high-fat diet-induced lipid accumulation. Similar results were observed in the weight of the adipose tissue after the experiment. Moreover, ESG significantly suppressed the lipid accumulation in the liver but increased fecal lipid excretion. The plasma concentrations of triacylglycerol and nonesterified fatty acid were lowered after a high-fat diet, whereas the total bile acid concentration was increased by ESG. However, the hepatic messenger RNA (mRNA) levels of enzymes related to lipid metabolism were not affected by ESG. Conversely, the mRNA levels of long-chain acyl-CoA dehydrogenase and medium-chain acyl-CoA dehydrogenase were up-regulated by ESG in the muscle. These results suggest that the combined effects of increased fecal lipid excretion, increased mRNA levels of enzymes that oxidize fatty acids in the muscle, and increased total bile acid concentration in the plasma mediate the inhibitory effect of ESG on lipid accumulation.

  7. Proteome analysis of fatty liver in feed-deprived dairy cows reveals interaction of fuel sensing, calcium, fatty acid, and glycogen metabolism.

    PubMed

    Kuhla, Björn; Albrecht, Dirk; Kuhla, Siegfried; Metges, Cornelia C

    2009-04-10

    The liver of dairy cows is involved in signaling the current hepatic metabolic state to the brain via metabolites and nerval afferents to control and adjust feed intake. Feed deprivation may result in mobilization of body reserves favoring hepatic steatosis. While the overall metabolic changes are well characterized, specific regulatory mechanisms are not readily understood. To identify molecular events associated with metabolic adaptation and the control of energy homeostasis, liver specimens from six ad libitum-fed and six feed-deprived cows were analyzed for selected metabolites, for the activation of AMP kinase, and for regulatory/regulated proteins using two-dimensional gel electrophoresis and MALDI-TOF-MS. Feed deprivation increased total liver fat and the calcium content, as well as augmented AMPK phosphorylation, while it decreased the contents of protein, glucose, glycogen, and cholesterol when expressed as a percentage of dry matter. Among 34 differentially expressed proteins identified, we found downregulation of proteins associated with fatty acid oxidation, glycolysis, electron transfer, protein degradation, and antigen processing, as well as cytoskeletal rearrangement. Proteins upregulated after feed deprivation included enzymes of the urea cycle, fatty acid or cholesterol transport proteins, an inhibitor of glycolysis, and previously unknown changes in calcium signaling network. Direct correlation was found between expression of glycolytic enzymes and glucose/glycogen content, whereas inverse correlation exists between expression of beta-oxidative enzymes and total liver fat content. In conclusion, the regulatory response of identified proteins may help to explain development and consequences of hepatic lipidosis but also offers novel candidates potentially involved in signaling for maintaining energy homeostasis.

  8. Pathogenesis of growth failure and partial reversal with gene therapy in murine and canine Glycogen Storage Disease type Ia.

    PubMed

    Brooks, Elizabeth Drake; Little, Dianne; Arumugam, Ramamani; Sun, Baodong; Curtis, Sarah; Demaster, Amanda; Maranzano, Michael; Jackson, Mark W; Kishnani, Priya; Freemark, Michael S; Koeberl, Dwight D

    2013-06-01

    Glycogen Storage Disease type Ia (GSD-Ia) in humans frequently causes delayed bone maturation, decrease in final adult height, and decreased growth velocity. This study evaluates the pathogenesis of growth failure and the effect of gene therapy on growth in GSD-Ia affected dogs and mice. Here we found that homozygous G6pase (-/-) mice with GSD-Ia have normal growth hormone (GH) levels in response to hypoglycemia, decreased insulin-like growth factor (IGF) 1 levels, and attenuated weight gain following administration of GH. Expression of hepatic GH receptor and IGF 1 mRNAs and hepatic STAT5 (phospho Y694) protein levels are reduced prior to and after GH administration, indicating GH resistance. However, restoration of G6Pase expression in the liver by treatment with adeno-associated virus 8 pseudotyped vector expressing G6Pase (AAV2/8-G6Pase) corrected body weight, but failed to normalize plasma IGF 1 in G6pase (-/-) mice. Untreated G6pase (-/-) mice also demonstrated severe delay of growth plate ossification at 12 days of age; those treated with AAV2/8-G6Pase at 14 days of age demonstrated skeletal dysplasia and limb shortening when analyzed radiographically at 6 months of age, in spite of apparent metabolic correction. Moreover, gene therapy with AAV2/9-G6Pase only partially corrected growth in GSD-Ia affected dogs as detected by weight and bone measurements and serum IGF 1 concentrations were persistently low in treated dogs. We also found that heterozygous GSD-Ia carrier dogs had decreased serum IGF 1, adult body weights and bone dimensions compared to wild-type littermates. In sum, these findings suggest that growth failure in GSD-Ia results, at least in part, from hepatic GH resistance. In addition, gene therapy improved growth in addition to promoting long-term survival in dogs and mice with GSD-Ia.

  9. Glucose uptake and transport in contracting, perfused rat muscle with different pre-contraction glycogen concentrations.

    PubMed Central

    Hespel, P; Richter, E A

    1990-01-01

    1. Glucose uptake and transport, muscle glycogen, free glucose and glucose-6-phosphate concentrations were studied in perfused resting and contracting rat skeletal muscle with different pre-contraction glycogen concentrations. Rats were pre-conditioned by a combination of swimming exercise and diet, resulting in either low (glycogen-depleted rats), normal (control rats) or high (supercompensated rats) muscle glycogen concentrations at the time their hindlimbs were perfused. 2. Compared with control rats, pre-contraction muscle glycogen concentration was approximately 40% lower in glycogen-depleted rats, whereas it was 40% higher in supercompensated rats. Muscle glycogen break-down correlated positively (r = 0.76; P less than 0.001) with pre-contraction muscle glycogen concentration. 3. Glucose uptake during contractions was approximately 50% higher in glycogen-depleted hindquarters than in control hindquarters; in supercompensated hindquarters it was 30% lower. When rats with similar muscle glycogen concentrations were compared, glucose uptake in hindquarters from rats that had exercised on the preceding day was approximately 20% higher than in hindquarters from rats that had not exercised on the preceding day. 4. Muscle membrane glucose transport, as measured by the rate of accumulation of 14C-3-O-methylglucose in the contracting muscles, was 25% lower in supercompensated than in glycogen-depleted muscles at the onset as well as at the end of the 15 min contraction period. 5. Intracellular concentrations of free glucose and glucose-6-phosphate were higher at rest and during the entire 15-min stimulation period in supercompensated muscles than in glycogen-depleted muscles, and glucose uptake during contractions correlated negatively with free glucose (r = -0.52; P less than 0.01) as well as with glucose-6-phosphate (r = -0.49; P less than 0.01) concentrations. 6. It is concluded that: (a) The rate of glucose uptake in contracting skeletal muscle is dependent on the

  10. Feature Hepatitis: Hepatitis Symptoms, Diagnosis, Treatment & Prevention

    MedlinePlus

    ... Navigation Bar Home Current Issue Past Issues Feature Hepatitis Hepatitis: Symptoms, Diagnosis, Treatment & Prevention Past Issues / Spring 2009 ... No appetite Fever Headaches Diagnosis To check for hepatitis viruses, your doctor will test your blood. You ...

  11. Glycogen Synthase Kinase-3 (GSK-3)-Targeted Therapy and Imaging

    PubMed Central

    Pandey, Mukesh K.; DeGrado, Timothy R.

    2016-01-01

    Glycogen synthase kinase-3 (GSK-3) is associated with various key biological processes, including glucose regulation, apoptosis, protein synthesis, cell signaling, cellular transport, gene transcription, proliferation, and intracellular communication. Accordingly, GSK-3 has been implicated in a wide variety of diseases and specifically targeted for both therapeutic and imaging applications by a large number of academic laboratories and pharmaceutical companies. Here, we review the structure, function, expression levels, and ligand-binding properties of GSK-3 and its connection to various diseases. A selected list of highly potent GSK-3 inhibitors, with IC50 <20 nM for adenosine triphosphate (ATP)-competitive inhibitors and IC50 <5 μM for non-ATP-competitive inhibitors, were analyzed for structure activity relationships. Furthermore, ubiquitous expression of GSK-3 and its possible impact on therapy and imaging are also highlighted. Finally, a rational perspective and possible route to selective and effective GSK-3 inhibitors is discussed. PMID:26941849

  12. Aggressive therapy improves cirrhosis in glycogen storage disease type IX.

    PubMed

    Tsilianidis, Laurie A; Fiske, Laurie M; Siegel, Sara; Lumpkin, Chris; Hoyt, Kate; Wasserstein, Melissa; Weinstein, David A

    2013-06-01

    Glycogen storage disease type IX (GSD IX) is described as a benign condition that often does not require treatment. Most patients with the disease are thought to outgrow the childhood manifestations, which include hepatomegaly, poor growth, and ketosis with or without hypoglycemia. Long term complications including fibrosis and cirrhosis have seldom been reported in the most common subtype, GSD IXα. We present two cases of children with GSD IXα who had fibrosis at the time of diagnosis in addition to the commonly reported disease manifestations. Structured therapy with frequent doses of uncooked cornstarch and protein supplementation was initiated, and both children responded with improved growth velocity, increased energy, decreased hepatomegaly and improved well-being. Additionally, radiographic features of fibrosis improved. We propose that GSD IXα is not a benign condition. Even in patients with a less severe presentation, consideration of a structured treatment regimen to improve quality of life appears warranted.

  13. Noncompaction myocardium in association with type Ib glycogen storage disease.

    PubMed

    Goeppert, Benjamin; Lindner, Martin; Vogel, Monika Nadja; Warth, Arne; Stenzinger, Albrecht; Renner, Marcus; Schnabel, Philipp; Schirmacher, Peter; Autschbach, Frank; Weichert, Wilko

    2012-10-15

    Noncompaction myocardium is a rare disorder assumed to occur as an arrest of the compaction process during the normal development of the heart. Left ventricular noncompaction has been reported to be associated with a variety of cardiac and extracardiac, especially neuromuscular abnormalities. Moreover, it has been suggested that metabolic alterations could be responsible for the noncompaction. However, no association of noncompaction myocardium with type Ib glycogen storage disease (GSD) has been reported so far. Type Ib GSD is due to a defect of a transmembrane protein which results, similar to type Ia GSD, in hypoglycemia, a markedly enlarged liver and, additionally, in neutropenia, recurrent infections, and inflammatory bowel disease. Until now, no muscular or cardiac involvement has been described in type Ib GSD patients. The present case represents the first report of a noncompaction myocardium in a child with type Ib GSD who died of sudden clinical deterioration at the age of four.

  14. Large Animal Models and New Therapies for Glycogen Storage Disease

    PubMed Central

    Brooks, Elizabeth D.

    2015-01-01

    Glycogen storage diseases (GSD), a unique category of inherited metabolic disorders, were first described early in the 20th century. Since then, the biochemical and genetic bases of these disorders have been determined, and an increasing number of animal models for GSD have become available. At least 7 large mammalian models have been developed for laboratory research on GSDs. These models have facilitated the development of new therapies, including gene therapy, which are undergoing clinical translation. For example, gene therapy prolonged survival and prevented hypoglycemia during fasting for greater than one year in dogs with GSD type Ia, and the need for periodic re-administration to maintain efficacy was demonstrated in that dog model. The further development of gene therapy could provide curative therapy for patients with GSD and other inherited metabolic disorders. PMID:25224826

  15. Emerging therapies for glycogen storage disease type I.

    PubMed

    Koeberl, D D; Kishnani, P S; Bali, D; Chen, Y-T

    2009-07-01

    Glycogen storage disease type I (GSD I) is caused by deficiency of the glucose-6-phosphatase catalytic subunit in type Ia or of glucose-6-phosphate transporter in type Ib. The cellular bases for disruptions of homeostasis have been increasingly understood in GSD I, including those for anemia, renal failure and neutropenia. Advances in the understanding of cellular abnormalities in GSD I have provided rationales for new therapy, and recent developments in gene therapy have led to potential curative treatments for GSD I. These advances will benefit patients with GSD I in the future, improving both quality of life and survival, as well as illuminating the molecular effects of altered metabolism upon multiple organ systems.

  16. Large animal models and new therapies for glycogen storage disease.

    PubMed

    Brooks, Elizabeth D; Koeberl, Dwight D

    2015-05-01

    Glycogen storage diseases (GSD), a unique category of inherited metabolic disorders, were first described early in the twentieth century. Since then, the biochemical and genetic bases of these disorders have been determined, and an increasing number of animal models for GSD have become available. At least seven large mammalian models have been developed for laboratory research on GSDs. These models have facilitated the development of new therapies, including gene therapy, which are undergoing clinical translation. For example, gene therapy prolonged survival and prevented hypoglycemia during fasting for greater than one year in dogs with GSD type Ia, and the need for periodic re-administration to maintain efficacy was demonstrated in that dog model. The further development of gene therapy could provide curative therapy for patients with GSD and other inherited metabolic disorders.

  17. Hyperactivity: glycogen synthase kinase-3 as a therapeutic target.

    PubMed

    Mines, Marjelo A

    2013-05-15

    The diagnosis of hyperactivity-associated disorders has increased within the past few years. The prevalence of hyperactivity-associated disorders is indicative of the need to more fully understand the underlying causes and to develop improved therapeutic interventions. There is increasing evidence that glycogen synthase kinase-3 (GSK3) mediates locomotor hyperactivity in a number of animal models, and therefore may be a potential target for therapeutic intervention in hyperactivity-associated behaviors. In this review, we discuss 1) the effect of manipulations of GSK3 in the absence of drugs and disorders on locomotor activity, 2) the role of GSK3 in drug-induced hyperactivity in rodents, and 3) regulation of locomotor activity by GSK3 in transgenic mouse models related to specific disorders. These studies link GSK3 regulation and activity to hyperactivity-associated behaviors and disease pathologies.

  18. Glycogen storage disease type III in the Irish population.

    PubMed

    Crushell, Ellen; Treacy, Eileen P; Dawe, J; Durkie, M; Beauchamp, Nicholas J

    2010-12-01

    Glycogen storage disease type III (GSD III) results from mutations of the AGL gene encoding the glycogen debrancher enzyme. The disease has clinical and biochemical heterogeneity reflecting the severity of the AGL mutations. We sought to characterise the molecular defects in our cohort of Irish patients with GSD III. Fifteen patients from eight unrelated Irish families were identified: six males and nine females. The age ranged from 2-39 years old, and all presented in the first 3 years of life. Four patients (of three families) had mild disease with hepatomegaly, mild hypoglycaemia and normal creatine kinase (CK) levels. Five families had more severe disease, with liver and skeletal muscle involvement and elevated CK. Eleven different mutations were identified amongst the eight families. Of the 11, six were novel: p.T512fs, p.S736fs, p.A1400fs, p.K1407fs, p.Y519X and p.D627Y. The family homozygous for p.A1400fs had the most severe phenotype (early-onset hypoglycaemia, massive hepatomegaly, myopathy and hypertrophic cardiomyopathy before age 2 years), which was not halted by aggressive carbohydrate and protein supplementation. Conversely, the only missense mutation identified in the cohort, p.D627Y, was associated with a mild phenotype. The phenotypic diversity in our GSD III cohort is mirrored by the allelic heterogeneity. We describe two novel null mutations in exon 32 in two families with severe GSD III resistant to current treatment modalities. Knowledge of the specific mutations segregating in this cohort may allow for the development of new therapeutic interventions.

  19. Aquaporins-2 and -4 regulate glycogen metabolism and survival during hyposmotic-anoxic stress in Caenorhabditis elegans

    PubMed Central

    LaMacchia, John C.

    2015-01-01

    Periods of oxygen deprivation can lead to ion and water imbalances in affected tissues that manifest as swelling (edema). Although oxygen deprivation-induced edema is a major contributor to injury in clinical ischemic diseases such as heart attack and stroke, the pathophysiology of this process is incompletely understood. In the present study we investigate the impact of aquaporin-mediated water transport on survival in a Caenorhabditis elegans model of edema formation during complete oxygen deprivation (anoxia). We find that nematodes lacking aquaporin water channels in tissues that interface with the surrounding environment display decreased edema formation and improved survival rates in anoxia. We also find that these animals have significantly reduced demand for glycogen as an energetic substrate during anoxia. Together, our data suggest that reductions in membrane water permeability may be sufficient to induce a hypometabolic state during oxygen deprivation that reduces injury and extends survival limits. PMID:26017147

  20. Hepatic vein obstruction (Budd-Chiari)

    MedlinePlus

    ... your provider if: You have symptoms of hepatic vein obstruction You are being treated for this condition and you develop new symptoms Alternative Names Budd-Chiari syndrome; Hepatic veno-occlusive disease Images Digestive system Digestive system organs Blood clot formation ...

  1. Dysfunctional glycogen storage in a mouse model of alpha1-antitrypsin deficiency.

    PubMed

    Hubner, Ralf H; Leopold, Philip L; Kiuru, Maija; De, Bishnu P; Krause, Anja; Crystal, Ronald G

    2009-02-01

    Autophagy is an intracellular pathway that contributes to the degradation and recycling of unfolded proteins. Based on the knowledge that autophagy affects glycogen metabolism and that alpha(1)-antitrypsin (AAT) deficiency is associated with an autophagic response in the liver, we hypothesized that the conformational abnormalities of the Z-AAT protein interfere with hepatocyte glycogen storage and/or metabolism. Compared with wild-type mice (WT), the Z-AAT mice had lower liver glycogen stores (P < 0.001) and abnormal activities of glycogen-related enzymes, including acid alpha-glucosidase (P < 0.05) and the total glycogen synthase (P < 0.05). As metabolic consequences, PiZ mice demonstrated lower blood glucose levels (P < 0.05), lower body weights (P < 0.001), and lower fat pad weights (P < 0.001) compared with WT. After the stress of fasting or partial hepatectomy, PiZ mice had further reduced liver glycogen and lower blood glucose levels (both P < 0.05 compared WT). Finally, PiZ mice exhibited decreased survival after partial hepatectomy (P < 0.01 compared with WT), but this was normalized with postoperative dextrose supplementation. In conclusion, these observations are consistent with the general concept that abnormal protein conformation and degradation affects other cellular functions, suggesting that diseases in the liver might benefit from metabolic compensation if glycogen metabolism is affected.

  2. Chronic corticosterone exposure reduces hippocampal glycogen level and induces depression-like behavior in mice.

    PubMed

    Zhang, Hui-yu; Zhao, Yu-nan; Wang, Zhong-li; Huang, Yu-fang

    2015-01-01

    Long-term exposure to stress or high glucocorticoid levels leads to depression-like behavior in rodents; however, the cause remains unknown. Increasing evidence shows that astrocytes, the most abundant cells in the central nervous system (CNS), are important to the nervous system. Astrocytes nourish and protect the neurons, and serve as glycogen repositories for the brain. The metabolic process of glycogen, which is closely linked to neuronal activity, can supply sufficient energy substrates for neurons. The research team probed into the effects of chronic corticosterone (CORT) exposure on the glycogen level of astrocytes in the hippocampal tissues of male C57BL/6N mice in this study. The results showed that chronic CORT injection reduced hippocampal neurofilament light protein (NF-L) and synaptophysin (SYP) levels, induced depression-like behavior in male mice, reduced hippocampal glycogen level and glycogen synthase activity, and increased glycogen phosphorylase activity. The results suggested that the reduction of the hippocampal glycogen level may be the mechanism by which chronic CORT treatment damages hippocampal neurons and induces depression-like behavior in male mice.

  3. Chronic corticosterone exposure reduces hippocampal glycogen level and induces depression-like behavior in mice*

    PubMed Central

    Zhang, Hui-yu; Zhao, Yu-nan; Wang, Zhong-li; Huang, Yu-fang

    2015-01-01

    Long-term exposure to stress or high glucocorticoid levels leads to depression-like behavior in rodents; however, the cause remains unknown. Increasing evidence shows that astrocytes, the most abundant cells in the central nervous system (CNS), are important to the nervous system. Astrocytes nourish and protect the neurons, and serve as glycogen repositories for the brain. The metabolic process of glycogen, which is closely linked to neuronal activity, can supply sufficient energy substrates for neurons. The research team probed into the effects of chronic corticosterone (CORT) exposure on the glycogen level of astrocytes in the hippocampal tissues of male C57BL/6N mice in this study. The results showed that chronic CORT injection reduced hippocampal neurofilament light protein (NF-L) and synaptophysin (SYP) levels, induced depression-like behavior in male mice, reduced hippocampal glycogen level and glycogen synthase activity, and increased glycogen phosphorylase activity. The results suggested that the reduction of the hippocampal glycogen level may be the mechanism by which chronic CORT treatment damages hippocampal neurons and induces depression-like behavior in male mice. PMID:25559957

  4. Glycogen in honeybee queens, workers and drones (Apis mellifera carnica Pollm.).

    PubMed

    Crailsheim, K; Panzenböck, U

    1997-02-21

    Honey bees (Apis mellifera carnica Pollm.) have low glycogen reserves in summer. Upon emergence drones have significantly larger amounts per unit weight when emerging, than workers; perhaps as adaption to the risk of not being fed as intensely as young workers. Maximum content was 0.23mg for workers (28d), and 0.59mg for drones (after emergence). Workers have relatively constant glycogen contents during their life, and very young drones have more glycogen than older ones. Young queens are similar to workers. In workers and queens in summer the greatest amounts of glycogen are found in the thorax. When the bees start flying (6th-8th day of life), drones have the highest amounts in the head (probably to supply their eyes), and upon maturity, drones have the least glycogen in the abdomen.Workers in winter show different glycogen values depending on whether they are active bees from the core area (0.23mg) or inactive ones from the outer surface of the winter cluster (0.37mg). They use glycogen from the thorax and the abdomen for their ongoing energy need.

  5. Liver glycogen metabolism during short-term insulin-induced hypoglycemia in fed rats.

    PubMed

    Obici, Simoni; Lopes-Bertolini, Gisele; Curi, Rui; Bazotte, Roberto Barbosa

    2008-10-01

    The activities of glycogen phosphorylase and synthase during infusions of glucagon, isoproterenol, or cyanide in isolated liver of fed rats submitted to short-term insulin-induced hypoglycemia (IIH) was investigated. A condition of hyperinsulinemia/hypoglycemia was obtained with an intraperitoneal injection of regular insulin (1.0 U kg(-1)). The control group received ip saline. The experiments were carried out 60 min after insulin (IIH group) or saline (COG group) injection. The rats were anesthetized and after laparotomy, blood was collected from the vena cava for glucose and insulin measurements. The liver was then infused with glucagon (1 nM), isoproterenol (2 microM), or cyanide (0.5 mM) during 20 min and a sample of the organ was collected for determination of the activities of glycogen phosphorylase and synthase 5 min after starting and 10 min after stopping the infusions. The infusions of cyanide, glucagons, and isoproterenol did not change the activities of glycogen synthase and glycogen phosphorylase. However, glycogen catabolism was decreased during the infusions of glucagon and isoproterenol in IIH rats, being more intense with isoproterenol (p < 0.05), than glucagon. It was concluded that short-term IIH promoted changes in the liver responsiveness of glycogen degradation induced by glucagon and isoproterenol without a change in the activities of glycogen phosphorylase and synthase.

  6. FLCN and AMPK Confer Resistance to Hyperosmotic Stress via Remodeling of Glycogen Stores

    PubMed Central

    Possik, Elite; Ajisebutu, Andrew; Manteghi, Sanaz; Gingras, Marie-Claude; Vijayaraghavan, Tarika; Flamand, Mathieu; Coull, Barry; Schmeisser, Kathrin; Duchaine, Thomas; van Steensel, Maurice; Hall, David H.; Pause, Arnim

    2015-01-01

    Mechanisms of adaptation to environmental changes in osmolarity are fundamental for cellular and organismal survival. Here we identify a novel osmotic stress resistance pathway in Caenorhabditis elegans (C. elegans), which is dependent on the metabolic master regulator 5’-AMP-activated protein kinase (AMPK) and its negative regulator Folliculin (FLCN). FLCN-1 is the nematode ortholog of the tumor suppressor FLCN, responsible for the Birt-Hogg-Dubé (BHD) tumor syndrome. We show that flcn-1 mutants exhibit increased resistance to hyperosmotic stress via constitutive AMPK-dependent accumulation of glycogen reserves. Upon hyperosmotic stress exposure, glycogen stores are rapidly degraded, leading to a significant accumulation of the organic osmolyte glycerol through transcriptional upregulation of glycerol-3-phosphate dehydrogenase enzymes (gpdh-1 and gpdh-2). Importantly, the hyperosmotic stress resistance in flcn-1 mutant and wild-type animals is strongly suppressed by loss of AMPK, glycogen synthase, glycogen phosphorylase, or simultaneous loss of gpdh-1 and gpdh-2 enzymes. Our studies show for the first time that animals normally exhibit AMPK-dependent glycogen stores, which can be utilized for rapid adaptation to either energy stress or hyperosmotic stress. Importantly, we show that glycogen accumulates in kidneys from mice lacking FLCN and in renal tumors from a BHD patient. Our findings suggest a dual role for glycogen, acting as a reservoir for energy supply and osmolyte production, and both processes might be supporting tumorigenesis. PMID:26439621

  7. Liver Cancer and Hepatitis B

    MedlinePlus

    ... Our Accomplishments Annual Reports Our Videos What Is Hepatitis B? What Is Hepatitis B? The ABCs of Viral Hepatitis Liver Cancer and Hepatitis B Hepatitis Delta Coinfection Hepatitis C Coinfection HIV/AIDS ...

  8. Hepatitis C: Sex and Sexuality

    MedlinePlus

    ... with Hepatitis » Sex and Sexuality: Entire Lesson Viral Hepatitis Menu Menu Viral Hepatitis Viral Hepatitis Home For ... hepatitis C virus through sex. Can you pass hepatitis C to a sex partner? Yes, but it ...

  9. Epidermal growth factor counteracts the glycogenic effect of insulin in parenchymal hepatocyte cultures.

    PubMed Central

    Chowdhury, M H; Agius, L

    1987-01-01

    Rat parenchymal hepatocytes in monolayer culture were used to study the metabolic effects of epidermal growth factor (EGF) and insulin on ketogenesis, gluconeogenesis and glycogen metabolism. EGF, unlike insulin, did not inhibit ketogenesis from palmitate or gluconeogenesis from pyruvate in hepatocyte cultures. It also had no effect on these pathways in the presence of insulin. In contrast, EGF potently counteracted the stimulation of [14C]pyruvate incorporation into glycogen by insulin, and also glycogen deposition from both gluconeogenic precursors and glucose. The EGF concentration causing half-maximal effect was about 0.1 nM. The anti-glycogenic effect of EGF was observed after both long-term (24 h) and short-term (1 h) exposure to EGF, and was more marked in the presence of insulin than in its absence. EGF did not displace bound insulin, suggesting that it neither competes for the insulin receptor nor affects the affinity of the receptor for insulin. EGF did not alter cellular cyclic AMP; and inhibition of cyclic AMP phosphodiesterase activity did not prevent the anti-glycogenic effect of EGF. In liver-derived dividing epithelial cells, Hep-G2 cells and fibroblasts, which have no capacity for gluconeogenesis, EGF did not counteract the stimulatory effect of insulin on [14C]glucose incorporation into glycogen, and in the epithelial cells EGF increased [14C]glucose incorporation into glycogen. The counter-effect of EGF on the glycogenic action of insulin in parenchymal hepatocytes may be due to a direct effect on glycogen metabolism or to an interaction with the post-receptor events in insulin action. PMID:2827626

  10. Pathological glycogenesis through glycogen synthase 1 and suppression of excessive AMP kinase activity in myeloid leukemia cells

    PubMed Central

    Nonami, Atsushi; Weisberg, Ellen L.; Bonal, Dennis; Kirschmeier, Paul T.; Salgia, Sabrina; Podar, Klaus; Galinsky, Ilene; Chowdary, Tirumala K.; Neuberg, Donna; Tonon, Giovanni; Stone, Richard M.; Asara, John; Griffin, James D.; Sattler, Martin

    2015-01-01

    The rapid proliferation of myeloid leukemia cells is highly dependent on increased glucose metabolism. Through an unbiased metabolomics analysis of leukemia cells, we found that the glycogenic precursor UDP-D-glucose is pervasively upregulated, despite low glycogen levels. Targeting the rate-limiting glycogen synthase 1 (GYS1) not only decreased glycolytic flux but also increased activation of the glycogen-responsive AMPK (AMP kinase), leading to significant growth suppression. Further, genetic and pharmacological hyper-activation of AMPK was sufficient to induce the changes observed with GYS1 targeting. Cancer genomics data also indicate that elevated levels of the glycogenic enzymes GYS1/2 or GBE1 (glycogen branching enzyme 1) are associated with poor survival in AML. These results suggest a novel mechanism whereby leukemic cells sustain aberrant proliferation by suppressing excess AMPK activity through elevated glycogenic flux and provide a therapeutic entry point for targeting leukemia cell metabolism. PMID:25703587

  11. The Saccharomyces cerevisiae fermentation stress response protein Igd1p/Yfr017p regulates glycogen levels by inhibiting the glycogen debranching enzyme.

    PubMed

    Walkey, Christopher J; Luo, Zongli; Borchers, Christoph H; Measday, Vivien; van Vuuren, Hennie J J

    2011-09-01

    Wine fermentation imposes a number of stresses on Saccharomyces cerevisiae, and wine yeasts respond to this harsh environment by altering their transcriptional profile (Marks et al., 2008). We have labeled this change in gene expression patterns the fermentation stress response (FSR). An important component of the FSR is the increased expression of 62 genes for which no function has been identified for their protein products. We hypothesize that a function for these proteins may only be revealed late in grape must fermentation, when the yeast cells are facing conditions much more extreme than those normally encountered in laboratory media. We used affinity copurification to identify interaction partners for the FSR protein Yfr017p, and found that it interacts specifically with the glycogen debranching enzyme (Gdb1p). The expression of both of these proteins is strongly induced during wine fermentation. Therefore, we investigated the role of Yfr017p in glycogen metabolism by constructing wine yeast strains that lack this protein. These YFR017C null cells displayed a significant reduction in their ability to accumulate glycogen during aerobic growth and fermentation. Moreover, Yfr017p inhibits Gdb1p activity in vitro. These results suggest that Yfr017p functions as an inhibitor of Gdb1p, enhancing the ability of yeast cells to store glucose as glycogen. Therefore, we propose IGD1 (for inhibitor of glycogen debranching) as a gene name for the YFR017C ORF.

  12. In vitro inhibition of glycogen-degrading enzymes and glycosidases by six-membered sugar mimics and their evaluation in cell cultures.

    PubMed

    Kuriyama, Chinami; Kamiyama, Ogusa; Ikeda, Kyoko; Sanae, Fujiko; Kato, Atsushi; Adachi, Isao; Imahori, Tatsushi; Takahata, Hiroki; Okamoto, Tadashi; Asano, Naoki

    2008-08-01

    We investigated in vitro inhibition of mammalian carbohydrate-degrading enzymes by six-membered sugar mimics and their evaluation in cell cultures. 1-Deoxynojirimycin (DNJ) showed no significant inhibition toward glycogen phosphorylase (GP) but was a potent inhibitor of another glycogen-degrading enzyme, amylo-1,6-glucosidase (1,6-GL), with an IC(50) value of 0.16 microM. In primary rat hepatocytes, the inhibition of glycogen breakdown by DNJ reached plateau at 100 microM with 25% inhibition and then remained unchanged. The potent GP inhibitor 1,4-dideoxy-1,4-imino-D-arabinitol (D-AB1) inhibited hepatic glucose production with an IC(50) value of about 9 microM and the inhibition by D-AB1 was further enhanced in the presence of DNJ. DNJ and alpha-homonojirimycin (HNJ) are very potent inhibitors of rat intestinal maltase, with IC(50) values of 0.13 and 0.08 microM, respectively, and also showed a similar strong inhibition toward maltase in Caco-2 cell model system, with IC(50) value of 0.05 and 0.10 microM, respectively. D-Isofagomine (D-IFG) and L-IFG are competitive and noncompetitive inhibitors of human lysosomal beta-glucosidase (beta-GL), respectively, with K(i) values of 8.4 nM and 6.9 microM. D-IFG increased intracellular beta-GL activity by twofold at 10 microM in Gaucher N370S cell line as an 'active-site-specific' chaperone, and surprisingly a noncompetitive inhibitor L-IFG also increased intracellular beta-GL activity by 1.6-fold at 500 microM.

  13. AJS1669, a novel small-molecule muscle glycogen synthase activator, improves glucose metabolism and reduces body fat mass in mice.

    PubMed

    Nakano, Kazuhiro; Takeshita, Sen; Kawasaki, Noriko; Miyanaga, Wataru; Okamatsu, Yoriko; Dohi, Mizuki; Nakagawa, Tadakiyo

    2017-04-01

    Impaired glycogen synthesis and turnover are common in insulin resistance and type 2 diabetes. As glycogen synthase (GS) is a key enzyme involved in the synthetic process, it presents a promising therapeutic target for the treatment of type 2 diabetes. In the present study, we identified a novel, potent and orally available GS activator AJS1669 {sodium 2-[[5-[[4-(4,5-difluoro-2-methylsulfanyl-phenyl)phenoxy] methyl]furan-2-carbonyl]-(2-furylmethyl)amino] acetate}. In vitro, we performed a glycogen synthase 1 (GYS1) activation assay for screening GS activators and identified that the activity of AJS1669 was further potentiated in the presence of glucose-6-phosphate (G6P). In vivo, we used ob/ob mice to evaluate the novel anti-diabetic effects of AJS1669 by measuring basal blood glucose levels, glucose tolerance and body fat mass index. Repeated administration of AJS1669 over 4 weeks reduced blood glucose and hemoglobin A1c (HbA1c) levels in ob/ob mice. AJS1669 also improved glucose tolerance in a dose-dependent manner, and decreased body fat mass. The mRNA levels of genes involved in mitochondrial fatty acid oxidation and mitochondrial biogenesis were elevated in skeletal muscle tissue following AJS1669 treatment. Hepatic tissue of treated mice also exhibited elevated expression of genes associated with fatty acid oxidation. In contrast to ob/ob mice, in C57Bl/6 mice AJS1669 administration did not alter body weight or reduce glucose levels. These results demonstrate that pharmacological agents that activate GYS1, the main GS subtype found in skeletal muscle, have potential for use as novel treatments for diabetes that improve glucose metabolism in skeletal muscle.

  14. AJS1669, a novel small-molecule muscle glycogen synthase activator, improves glucose metabolism and reduces body fat mass in mice

    PubMed Central

    Nakano, Kazuhiro; Takeshita, Sen; Kawasaki, Noriko; Miyanaga, Wataru; Okamatsu, Yoriko; Dohi, Mizuki; Nakagawa, Tadakiyo

    2017-01-01

    Impaired glycogen synthesis and turnover are common in insulin resistance and type 2 diabetes. As glycogen synthase (GS) is a key enzyme involved in the synthetic process, it presents a promising therapeutic target for the treatment of type 2 diabetes. In the present study, we identified a novel, potent and orally available GS activator AJS1669 {sodium 2-[[5-[[4-(4,5-difluoro-2-methylsulfanyl-phenyl) phenoxy] methyl]furan-2-carbonyl]-(2-furylmethyl)amino] acetate}. In vitro, we performed a glycogen synthase 1 (GYS1) activation assay for screening GS activators and identified that the activity of AJS1669 was further potentiated in the presence of glucose-6-phosphate (G6P). In vivo, we used ob/ob mice to evaluate the novel anti-diabetic effects of AJS1669 by measuring basal blood glucose levels, glucose tolerance and body fat mass index. Repeated administration of AJS1669 over 4 weeks reduced blood glucose and hemoglobin A1c (HbA1c) levels in ob/ob mice. AJS1669 also improved glucose tolerance in a dose-dependent manner, and decreased body fat mass. The mRNA levels of genes involved in mitochondrial fatty acid oxidation and mitochondrial biogenesis were elevated in skeletal muscle tissue following AJS1669 treatment. Hepatic tissue of treated mice also exhibited elevated expression of genes associated with fatty acid oxidation. In contrast to ob/ob mice, in C57Bl/6 mice AJS1669 administration did not alter body weight or reduce glucose levels. These results demonstrate that pharmacological agents that activate GYS1, the main GS subtype found in skeletal muscle, have potential for use as novel treatments for diabetes that improve glucose metabolism in skeletal muscle. PMID:28290602

  15. Assessment of heavy metal (Cu, Ni, Fe, Co, Mn, Cr, Zn) pollution in effluent dominated rivulet water and their effect on glycogen metabolism and histology of Mastacembelus armatus.

    PubMed

    Javed, Mehjbeen; Usmani, Nazura

    2013-01-01

    The present study was conducted to examine the contamination of rivulet situated at Kasimpur, Aligarh (27.218° N; 79.378° E). It receives the wastewater of Harduaganj Thermal Power Plant (HTPS) containing fly ash and heavy metals. Among the heavy metals estimated in the rivulet water, Fe (8.71 mgL(-1)) was present in the highest concentration followed by Cu (0.86 mgL(-1)), Zn (0.30 mgL(-1)) Mn (0.21 mgL(-1)), Ni (0.12 mgL(-1)), Co (0.11 mgL(-1)) and Cr (0.10 mgL(-1)). The values for the heavy metals such as Fe, Ni and Mn were beyond the limits set by UNEPGEMS. Bioaccumulation of these heavy metals was detected in tissues such as gills, liver, kidney, muscle and integument of the fish Mastacembelus armatus. Accumulation of Fe (213.29 - 2601.49 mgkg(-1).dw) was highest in all the organs. Liver was the most influenced organ and integument had the least metal load. The accumulation of Fe, Zn, Cu and Mn, observed in the tissues were above the values recommended by FAO/WHO. Biochemical estimation related to blood glucose, liver and muscle glycogen conducted showed significant (p < 0.01) elevation in blood glucose content over control (17.73%), whereas liver glycogen dropped significantly (p < 0.01) over control (-89.83%), and similarly muscle glycogen also decreased significantly (p < 0.05) over control (-71.95%), suggesting enhanced glycolytic capacity to fuel hepatic metabolism. Histopathological alterations were also observed in selected organs (gills, liver and kidney) of Mastacembelus armatus.

  16. Identification and Structural Basis of Binding to Host Lung Glycogen by Streptococcal Virulence Factors

    SciTech Connect

    Lammerts van Bueren,A.; Higgins, M.; Wang, D.; Burke, R.; Boraston, A.

    2007-01-01

    The ability of pathogenic bacteria to recognize host glycans is often essential to their virulence. Here we report structure-function studies of previously uncharacterized glycogen-binding modules in the surface-anchored pullulanases from Streptococcus pneumoniae (SpuA) and Streptococcus pyogenes (PulA). Multivalent binding to glycogen leads to a strong interaction with alveolar type II cells in mouse lung tissue. X-ray crystal structures of the binding modules reveal a novel fusion of tandem modules into single, bivalent functional domains. In addition to indicating a structural basis for multivalent attachment, the structure of the SpuA modules in complex with carbohydrate provides insight into the molecular basis for glycogen specificity. This report provides the first evidence that intracellular lung glycogen may be a novel target of pathogenic streptococci and thus provides a rationale for the identification of the streptococcal {alpha}-glucan-metabolizing machinery as virulence factors.

  17. Glycogen synthase (GYS1) mutation causes a novel skeletal muscle glycogenosis.

    PubMed

    McCue, Molly E; Valberg, Stephanie J; Miller, Michael B; Wade, Claire; DiMauro, Salvatore; Akman, Hasan O; Mickelson, James R

    2008-05-01

    Polysaccharide storage myopathy (PSSM) is a novel glycogenosis in horses characterized by abnormal glycogen accumulation in skeletal muscle and muscle damage with exertion. It is unlike glycogen storage diseases resulting from known defects in glycogenolysis, glycolysis, and glycogen synthesis that have been described in humans and domestic animals. A genome-wide association identified GYS1, encoding skeletal muscle glycogen synthase (GS), as a candidate gene for PSSM. DNA sequence analysis revealed a mutation resulting in an arginine-to-histidine substitution in a highly conserved region of GS. Functional analysis demonstrated an elevated GS activity in PSSM horses, and haplotype analysis and allele age estimation demonstrated that this mutation is identical by descent among horse breeds. This is the first report of a gain-of-function mutation in GYS1 resulting in a glycogenosis.

  18. Evidence for endogenous formation of the hepatocarcinogen N-nitrosodihydrouracil in rats treated with dihydrouracil and sodium nitrite: a potential source of human hepatic DNA carboxyethylation.

    PubMed

    Wang, Mingyao; Cheng, Guang; Khariwala, Samir S; Bandyopadhyay, Dipankar; Villalta, Peter W; Balbo, Silvia; Hecht, Stephen S

    2013-10-25

    An earlier study demonstrated that hydrolysates of all human liver DNA samples analyzed contain the DNA adduct 7-(2'-carboxyethyl)guanine (7-CEGua) with an average level of 74.6 adducts per 10(9) nucleotides. One possible source of this DNA adduct would be endogenous nitrosation of the normal pyrimidine metabolites dihydrouracil (DHU) and β-ureidopropionic acid (β-UPA), yielding the corresponding nitroso compounds N-nitrosodihydrouracil, a potent hepatocarcinogen, and N-nitroso-β-ureidopropionic acid. Another potential source would be reaction of endogenously formed acrylic acid with DNA. We tested these hypotheses in a study in which rats were treated with NaNO2 in the drinking water, alone, or in combination with dietary DHU or β-UPA, or with acrylic acid in the drinking water, for either 2 or 4 weeks. Hepatic DNA from these rats was analyzed for 7-CEGua, using liquid chromatography-tandem mass spectrometry-selected reaction monitoring with confirmation by high resolution mass spectrometry. The results demonstrated consistent statistically significant increases of 7-CEGua in hepatic DNA of the rats treated with the combination of NaNO2 and DHU compared to the corresponding controls, while the other treatments gave variable results. These results support the hypothesis that endogenous nitrosation of DHU could be a major source of 7-CEGua in human hepatic DNA. Development of methodology for analysis of 7-CEGua in human leukocyte DNA is also reported, which will allow testing of this hypothesis in epidemiologic and clinical studies.

  19. Rescue administration of a helper-dependent adenovirus vector with long-term efficacy in dogs with glycogen storage disease type Ia.

    PubMed

    Crane, B; Luo, X; Demaster, A; Williams, K D; Kozink, D M; Zhang, P; Brown, T T; Pinto, C R; Oka, K; Sun, F; Jackson, M W; Chan, L; Koeberl, D D

    2012-04-01

    Glycogen storage disease type Ia (GSD-Ia) stems from glucose-6-phosphatase (G6Pase) deficiency and causes hypoglycemia, hepatomegaly, hypercholesterolemia and lactic acidemia. Three dogs with GSD-Ia were initially treated with a helper-dependent adenovirus encoding a human G6Pase transgene (HDAd-cG6Pase serotype 5) on postnatal day 3. Unlike untreated dogs with GSD-Ia, all three dogs initially maintained normal blood glucose levels. After 6-22 months, vector-treated dogs developed hypoglycemia, anorexia and lethargy, suggesting that the HDAd-cG6Pase serotype 5 vector had lost efficacy. Liver biopsies collected at this time revealed significantly elevated hepatic G6Pase activity and reduced glycogen content, when compared with affected dogs treated only by frequent feeding. Subsequently, the HDAd-cG6Pase serotype 2 vector was administered to two dogs, and hypoglycemia was reversed; however, renal dysfunction and recurrent hypoglycemia complicated their management. Administration of a serotype 2 HDAd vector prolonged survival in one GSD-Ia dog to 12 months of age and 36 months of age in the other, but the persistence of long-term complications limited HDAd vectors in the canine model for GSD-Ia.

  20. Delivery of glucose-6-phosphatase in a canine model for glycogen storage disease, type Ia, with adeno-associated virus (AAV) vectors.

    PubMed

    Beaty, R M; Jackson, M; Peterson, D; Bird, A; Brown, T; Benjamin, D K; Juopperi, T; Kishnani, P; Boney, A; Chen, Y T; Koeberl, D D

    2002-08-01

    Therapy in glycogen storage disease type Ia (GSD Ia), an inherited disorder of carbohydrate metabolism, relies on nutritional support that postpones but fails to prevent long-term complications of GSD Ia. In the canine model for GSD Ia, we evaluated the potential of intravenously delivered adeno-associated virus (AAV) vectors for gene therapy. In three affected canines, liver glycogen was reduced following hepatic expression of canine glucose-6-phosphatase (G6Pase). Two months after AAV vector administration, one affected dog had normalization of fasting glucose, cholesterol, triglycerides, and lactic acid. Concatamerized AAV vector DNA was confirmed by Southern blot analysis of liver DNA isolated from treated dogs, as head-to-tail, head-to-head, and tail-to-tail concatamers. Six weeks after vector administration, the level of vector DNA signal in each dog varied from one to five copies per cell, consistent with variation in the efficiency of transduction within the liver. AAV vector administration in the canine model for GSD Ia resulted in sustained G6Pase expression and improvement in liver histology and in biochemical parameters.

  1. Glycogen synthase kinase 3β suppresses polyglutamine aggregation by inhibiting Vaccinia-related kinase 2 activity

    PubMed Central

    Lee, Eunju; Ryu, Hye Guk; Kim, Sangjune; Lee, Dohyun; Jeong, Young-Hun; Kim, Kyong-Tai

    2016-01-01

    Huntington’s disease (HD) is a neurodegenerative disorder caused by an abnormal expansion of polyglutamine repeats in the N-terminal of huntingtin. The amount of aggregate-prone protein is controlled by various mechanisms, including molecular chaperones. Vaccinia-related kinase 2 (VRK2) is known to negatively regulate chaperonin TRiC, and VRK2-facilitated degradation of TRiC increases polyQ protein aggregation, which is involved in HD. We found that VRK2 activity was negatively controlled by glycogen synthase kinase 3β (GSK3β). GSK3β directly bound to VRK2 and inhibited the catalytic activity of VRK2 in a kinase activity-independent manner. Furthermore, GSK3β increased the stability of TRiC and decreased the formation of HttQ103-GFP aggregates by inhibiting VRK2. These results indicate that GSK3β signaling may be a regulatory mechanism of HD progression and suggest targets for further therapeutic trials for HD. PMID:27377031

  2. Electrophoretic analysis of liver glycogen phosphorylase activation in the freeze-tolerant wood frog.

    PubMed

    Crerar, M M; David, E S; Storey, K B

    1988-08-19

    As an adaptation for overwinter survival, the wood frog, Rana sylvatica is able to tolerate the freezing of extracellular body fluids. Tolerance is made possible by the production of very high amounts of glucose in liver which is then sent to other organs where it acts as a cryoprotectant. Cryoprotectant synthesis is under the control of glycogen phosphorylase which in turn is activated in response to ice formation. To determine the mechanism of phosphorylase activation, a quantitative analysis of phosphorylase protein concentration and enzymatic activity in liver was carried out following separation of the phosphorylated a and nonphosphorylated b forms of the enzyme on native polyacrylamide gels. The results suggest that in gels, the b form is completely inactive, even in the presence of AMP and sodium sulfate, whereas the a form is active and stimulated 3-fold by these substances. Further, phosphorylase activation appears to arise solely from conversion of the b to a form of the enzyme without an increase in phosphorylase concentration or activation of a second isozyme. The quantitative analysis presented here should prove generally useful as a simple and rapid method for examining the physiological and genetic regulation of phosphorylase in animal cells.

  3. GLC3 and GHA1 of Saccharomyces cerevisiae are allelic and encode the glycogen branching enzyme.

    PubMed Central

    Rowen, D W; Meinke, M; LaPorte, D C

    1992-01-01

    In the yeast Saccharomyces cerevisiae, glycogen serves as a major storage carbohydrate. In a previous study, mutants with altered glycogen metabolism were isolated on the basis of the altered iodine-staining properties of colonies. We found that when glycogen produced by strains carrying the glc-1p (previously called gha1-1) mutation is stained with iodine, the absorption spectrum resembles that of starch rather than that of glycogen, suggesting that this mutation might reduce the level of branching in the glycogen particles. Indeed, glycogen branching activity was undetectable in extracts from a glc3-1p strain but was elevated in strains which expressed GLC3 from a high-copy-number plasmid. These observations suggest that GLC3 encodes the glycogen branching enzyme. In contrast to glc3-1p, the glc3-4 mutation greatly reduces the ability of yeast to accumulate glycogen. These mutations appear to be allelic despite the striking difference in the phenotypes which they produce. The GLC3 clone complemented both glc3-1p and glc3-4. Deletions and transposon insertions in this clone had parallel effects on its ability to complement glc3-1p and glc3-4. Finally, a fragment of the cloned gene was able to direct the repair of both glc3-1p and glc3-4. Disruption of GLC3 yielded the glycogen-deficient phenotype, indicating that glycogen deficiency is the null phenotype. The glc3-1p allele appears to encode a partially functional product, since it is dominant over glc3-4 but recessive to GLC3. These observations suggest that the ability to introduce branches into glycogen greatly increases the ability of the cell to accumulate that polysaccharide. Northern (RNA) blot analysis identified a single mRNA of 2,300 nucleotides that increased in abundance ca. 20-fold as the culture approached stationary phase. It thus appears that the expression of GLC3 is regulated, probably at the level of transcription. Images PMID:1729600

  4. C-Glucopyranosyl-1,2,4-triazoles As New Potent Inhibitors of Glycogen Phosphorylase

    PubMed Central

    2013-01-01

    Glycogen phosphorylase inhibitors are considered as potential antidiabetic agents. 3-(β-d-Glucopyranosyl)-5-substituted-1,2,4-triazoles were prepared by acylation of O-perbenzoylated N1-tosyl-C-β-d-glucopyranosyl formamidrazone and subsequent removal of the protecting groups. The best inhibitor was 3-(β-d-glucopyranosyl)-5-(2-naphthyl)-1,2,4-triazole (Ki = 0.41 μM against rabbit muscle glycogen phosphorylase b). PMID:24900719

  5. Effect of pH on Cleavage of Glycogen by Vaginal Enzymes

    PubMed Central

    Spear, Greg T.; McKenna, Mary; Landay, Alan L.; Makinde, Hadijat; Hamaker, Bruce; French, Audrey L.; Lee, Byung-Hoo

    2015-01-01

    Glycogen expressed by the lower genital tract epithelium is believed to support Lactobacillus growth in vivo, although most genital isolates of Lactobacillus are not able to use glycogen as an energy source in vitro. We recently reported that α-amylase is present in the genital fluid of women and that it breaks down glycogen into small carbohydrates that support growth of lactobacilli. Since the pH of the lower genital tract can be very low, we determined how low pH affects glycogen processing by α-amylase. α-amylase in saliva degraded glycogen similarly at pH 6 and 7, but activity was reduced by 52% at pH 4. The glycogen degrading activity in nine genital samples from seven women showed a similar profile with an average reduction of more than 50% at pH 4. However, two samples collected from one woman at different times had a strikingly different pH profile with increased glycogen degradation at pH 4, 5 and 6 compared to pH 7. This second pH profile did not correlate with levels of human α-acid glucosidase or human intestinal maltase glucoamylase. High-performance anion-exchange chromatography showed that mostly maltose was produced from glycogen by samples with the second pH profile in contrast to genital α-amylase that yielded maltose, maltotriose and maltotetraose. These studies show that at low pH, α-amylase activity is reduced to low but detectable levels, which we speculate helps maintain Lactobacillus growth at a limited but sustained rate. Additionally, some women have a genital enzyme distinct from α-amylase with higher activity at low pH. Further studies are needed to determine the identity and distribution of this second enzyme, and whether its presence influences the makeup of genital microbiota. PMID:26171967

  6. Levels of liver glycogen during normal and radiation-induced metamorphosis in Rana cyanophlyctis.

    PubMed

    Ahmad, M; Ashraf, J; Siddiqui, P Q; Khan, K R

    1979-01-01

    This study shows that significant changes in the pattern of glycogen deposition are brought about by irradiation with 2,000 R gamma-rays. The sharp fall during the 1st week can be attributed to its emergent mobilization. However, glycogen stored in the liver during the 2nd and 3rd week prior to the resorptive process substantiates the fact that tadpoles complete metamorphic transformations in spite of sublethal irradiation.

  7. Studies on glycogen autophagy: effects of phorbol myristate acetate, ionophore A23187, or phentolamine.

    PubMed

    Kalamidas, S A; Kotoulas, O B; Hann, A C

    2002-06-15

    The effects of agents that could manipulate the lysosomal calcium such as phorbol myristate acetate, ionophore A23187, and phentolamine on the lysosomal glycogen degradation were studied by electron microscopy, morphometric analysis, and biochemical assays in newborn rat hepatocytes. Phorbol myristate acetate, which promotes the input of calcium to lysosomes, increased the total volume of autophagic vacuoles and the activity of lysosomal glycogen-hydrolyzing acid alpha 1,4 glucosidase and decreased the fractional volume of undigested glycogen inside the autophagic vacuoles and also decreased the activity of acid mannose 6-phosphatase. Ionophore A23187, which releases lysosomal calcium, produced opposite results in these enzyme activities. Phentolamine, an alpha-adrenergic blocking agent which interferes with the generation of phosphoinositides and may activate the lysosomal calcium uptake pump, increased the total volume of autophagic vacuoles and the activity of lysosomal glycogen-hydrolyzing acid glucosidase and decreased the fractional volume of undigested glycogen inside the autophagic vacuoles. The results of this study constitute evidence that changes in lysosomal calcium may influence certain aspects of autophagy, including the degradation of glycogen inside the autophagic vacuoles. They also support our previous postulate [Kalamidas and Kotoulas (2000a,b) Histol Histopathol 15:29-35, 1011-1018] that stimulation of autophagic mechanisms in newborn rat hepatocytes may be associated with acid mannose 6-phosphatase activity-deficient lysosomes.

  8. Stimulation of lymphocyte proliferation by oyster glycogen sulfated at C-6 position.

    PubMed

    Yang, Jingfeng; Zhu, Beiwei; Zheng, Jie; Sun, Liming; Zhou, Dayong; Dong, Xiuping; Yu, Chenxu

    2013-04-15

    In this study, glycogen was extracted from oyster Ostrea talienwhanensis Crosse and used as a model to investigate the structure-activity correlation of polysaccharides. Purified oyster glycogen was characterized by methylation analysis, nuclear magnetic resonance (NMR) spectroscopy and infrared spectroscopy (IR). The oyster glycogen was subsequently sulfated by chlorosulfonic acid-pyridine method, and a C-6 substituted species (SOG) was identified to be the primary sulfated oyster glycogen species by (13)C NMR spectroscopy. The molecular weight and sulfate content of the SOG was determined to be 3.2×10(4) g/mol and 33.6%, respectively. Another sulfated oyster glycogen species (SOG1) with C-2 and C-3 substitution was also identified at a lesser amount in the final product. SOG exhibited a much stronger stimulation effect to splenic lymphocyte proliferation than SOG1 in vitro, indicating that the position of sulfate substitution is a major determining factor on the efficacy of sulfated glycogens to stimulate lymphocyte proliferation.

  9. Creatine supplementation does not affect human skeletal muscle glycogen content in the absence of prior exercise.

    PubMed

    Sewell, Dean A; Robinson, Tristan M; Greenhaff, Paul L

    2008-02-01

    Due to the current lack of clarity, we examined whether 5 days of dietary creatine (Cr) supplementation per se can influence the glycogen content of human skeletal muscle. Six healthy male volunteers participated in the study, reporting to the laboratory on four occasions to exercise to the point of volitional exhaustion, each after 3 days of a controlled normal habitual dietary intake. After a familiarization visit, participants cycled to exhaustion in the absence of any supplementation (N), and then 2 wk later again they cycled to exhaustion after 5 days of supplementation with simple sugars (CHO). Finally, after a further 2 wk, they again cycled to exhaustion after 5 days of Cr supplementation. Muscle samples were taken at rest before exercise, at the time point of exhaustion in visit 1, and at subsequent visit time of exhaustion. There was a treatment effect on muscle total Cr content in Cr compared with N and CHO supplementation (P < 0.01). Resting muscle glycogen content was elevated above N following CHO (P < 0.05) but not after Cr. At exhaustion following N, glycogen content was no different from CHO and Cr measured at the same time point during exercise. Cr supplementation under conditions of controlled habitual dietary intake had no effect on muscle glycogen content at rest or after exhaustive exercise. We suggest that any Cr-associated increases in muscle glycogen storage are the result of an interaction between Cr supplementation and other mediators of muscle glycogen storage.

  10. Dynamic metabolic profiling of cyanobacterial glycogen biosynthesis under conditions of nitrate depletion.

    PubMed

    Hasunuma, Tomohisa; Kikuyama, Fumi; Matsuda, Mami; Aikawa, Shimpei; Izumi, Yoshihiro; Kondo, Akihiko

    2013-07-01

    Cyanobacteria represent a globally important biomass because they are responsible for a substantial proportion of primary production in the hydrosphere. Arthrospira platensis is a fast-growing halophilic cyanobacterium capable of accumulating glycogen and has the potential to serve as a feedstock in the fermentative production of third-generation biofuels. Accordingly, enhancing cyanobacterial glycogen production is a promising biofuel production strategy. However, the regulatory mechanism of glycogen metabolism in cyanobacteria is poorly understood. The aim of the present study was to determine the metabolic flux of glycogen biosynthesis using a dynamic metabolomic approach. Time-course profiling of widely targeted cyanobacterial metabolic intermediates demonstrated a global metabolic reprogramming that involves transient increases in the levels of some amino acids during the glycogen production phase induced by nitrate depletion. Also, in vivo labelling with NaH(13)CO3 enabled direct measurement of metabolic intermediate turnover in A. platensis, revealing that under conditions of nitrate depletion glycogen is biosynthesized with carbon derived from amino acids released from proteins via gluconeogenesis. This dynamic metabolic profiling approach provided conclusive evidence of temporal alterations in the metabolic profile in cyanobacterial cells.

  11. Effects of swimming training on tissue glycogen content in experimental thyrotoxic rats.

    PubMed

    Ribeiro, Luiz Fernando Paulino; Teixeira, Inaian Pignatti; Aparecido da Silva, Glaucio; Dalia, Rodrigo Augusto; Júnior, Marcelo Costa; Bertolini, Natalia Oliveira; Rostom de Mello, Maria Alice; Luciano, Eliete

    2012-05-01

    Thyrotoxicosis, a condition in which there is an excessive amount of circulating thyroid hormones, leads to reduced glycogen content in different tissues. In this study we analyzed the effects of aerobic swimming training on liver, heart, and skeletal muscle glycogen content in experimentally induced thyrotoxicosis. Wistar male rats were divided into euthyroid sedentary (ES, n = 12), euthyroid trained (ET, n = 11), thyrotoxic sedentary (TS, n = 12), and thyrotoxic trained (TT, n = 10) groups. Thyrotoxic groups received daily i.p. doses of T4 (sodium levothyroxine, 25 µg/100 g body mass) through the experimental period, and trained groups swam for 1 h at 80% of the aerobic-anaerobic transition intensity, 5 days/week for 4 weeks. Heart and liver glycogen stores were ∼30% lower in T4 treated compared with nontreated groups, but were not changed by training status. On the other hand, glycogen content in mixed fiber type gastrocnemius of TT was 1.5- to 2.3-fold greater than those in other groups, whereas no significant differences were found for the slow soleus muscle. Increased gastrocnemius but not soleus, liver, or heart glycogen indicates that in mild long-term thyrotoxicosis chronic swimming affects glycogen stores in a tissue-specific manner.

  12. Investigation of potential glycogen synthase kinase 3 inhibitors using pharmacophore mapping and virtual screening.

    PubMed

    Dessalew, Nigus; Bharatam, Prasad V

    2006-09-01

    Glycogen synthase kinase-3 is a serine/threonine kinase that has attracted significant drug discovery attention in recent years. To investigate the identification of new potential glycogen synthase kinase-3 inhibitors, a pharmacophore mapping study was carried out using a set of 21 structurally diverse glycogen synthase kinase-3 inhibitors. A hypothesis containing four features: two hydrophobic, one hydrogen bond donor and another hydrogen bond acceptor was found to be the best from the 10 common feature hypotheses produced by HipHop module of Catalyst. The best hypothesis has a high cost of 156.592 and higher best fit values were obtained for the 21 inhibitors using this best hypothesis than the other HipHop hypotheses. The best hypothesis was then used to screen electronically the NCI2000 database. The hits obtained were docked into glycogen synthase kinase-3beta active site. A total of five novel potential leads were proposed after: (i) visual examination of how well they dock into the glycogen synthase kinase-3beta-binding site, (ii) comparative analysis of their FlexX, G-Score, PMF-Score, ChemScore and D-Scores values, (iii) comparison of their best fit value with the known inhibitors and (iv) examination of the how the hits retain interactions with the important amino acid residues of glycogen synthase kinase-3beta-binding site.

  13. Cecropia peltata accumulates starch or soluble glycogen by differentially regulating starch biosynthetic genes.

    PubMed

    Bischof, Sylvain; Umhang, Martin; Eicke, Simona; Streb, Sebastian; Qi, Weihong; Zeeman, Samuel C

    2013-04-01

    The branched glucans glycogen and starch are the most widespread storage carbohydrates in living organisms. The production of semicrystalline starch granules in plants is more complex than that of small, soluble glycogen particles in microbes and animals. However, the factors determining whether glycogen or starch is formed are not fully understood. The tropical tree Cecropia peltata is a rare example of an organism able to make either polymer type. Electron micrographs and quantitative measurements show that glycogen accumulates to very high levels in specialized myrmecophytic structures (Müllerian bodies), whereas starch accumulates in leaves. Compared with polymers comprising leaf starch, glycogen is more highly branched and has shorter branches--factors that prevent crystallization and explain its solubility. RNA sequencing and quantitative shotgun proteomics reveal that isoforms of all three classes of glucan biosynthetic enzyme (starch/glycogen synthases, branching enzymes, and debranching enzymes) are differentially expressed in Müllerian bodies and leaves, providing a system-wide view of the quantitative programming of storage carbohydrate metabolism. This work will prompt targeted analysis in model organisms and cross-species comparisons. Finally, as starch is the major carbohydrate used for food and industrial applications worldwide, these data provide a basis for manipulating starch biosynthesis in crops to synthesize tailor-made polyglucans.

  14. Glycogen synthase kinase-3 inhibitors: Rescuers of cognitive impairments

    PubMed Central

    King, Margaret K.; Pardo, Marta; Cheng, Yuyan; Downey, Kimberlee; Jope, Richard S.; Beurel, Eléonore

    2013-01-01

    Impairment of cognitive processes is a devastating outcome of many diseases, injuries, and drugs affecting the central nervous system (CNS). Most often, very little can be done by available therapeutic interventions to improve cognitive functions. Here we review evidence that inhibition of glycogen synthase kinase-3 (GSK3) ameliorates cognitive deficits in a wide variety of animal models of CNS diseases, including Alzheimer's disease, Fragile X syndrome, Down syndrome, Parkinson's disease, spinocerebellar ataxia type 1, traumatic brain injury, and others. GSK3 inhibitors also improve cognition following impairments caused by therapeutic interventions, such as cranial irradiation for brain tumors. These findings demonstrate that GSK3 inhibitors are able to ameliorate cognitive impairments caused by a diverse array of diseases, injury, and treatments. The improvements in impaired cognition instilled by administration of GSK3 inhibitors appear to involve a variety of different mechanisms, such as supporting long-term potentiation and diminishing long-term depression, promotion of neurogenesis, reduction of inflammation, and increasing a number of neuroprotective mechanisms. The potential for GSK3 inhibitors to repair cognitive deficits associated with many conditions warrants further investigation of their potential for therapeutic interventions, particularly considering the current dearth of treatments available to reduce loss of cognitive functions. PMID:23916593

  15. Preclinical Development of New Therapy for Glycogen Storage Diseases

    PubMed Central

    Sun, Baodong; Brooks, Elizabeth D.; Koeberl, Dwight D.

    2015-01-01

    Glycogen storage disease (GSD) consists of more than 10 discrete conditions for which the biochemical and genetic bases have been determined, and new therapies have been under development for several of these conditions. Gene therapy research has generated proof-of-concept for GSD types I (von Gierke disease) and II (Pompe disease). Key features of these gene therapy strategies include the choice of vector and regulatory cassette, and recently adeno-associated virus (AAV) vectors containing tissue-specific promoters have achieved a high degree of efficacy. Efficacy of gene therapy for Pompe disease depend upon the induction of immune tolerance to the therapeutic enzyme. Efficacy of von Gierke disease is transient, waning gradually over the months following vector administration. Small molecule therapies have been evaluated with the goal of improving standard of care therapy or ameliorating the cellular abnormalities associated with specific GSDs. The receptor-mediated uptake of the therapeutic enzyme in Pompe disease was enhanced by administration of β2 agonists. Rapamycin reduced the liver fibrosis observed in GSD III. Further development of gene therapy could provide curative therapy for patients with GSD, if efficacy from preclinical research is observed in future clinical trials and these treatments become clinically available. PMID:26122079

  16. Preclinical Development of New Therapy for Glycogen Storage Diseases.

    PubMed

    Sun, Baodong; Brooks, Elizabeth D; Koeberl, Dwight D

    2015-01-01

    Glycogen storage disease (GSD) consists of more than 10 discrete conditions for which the biochemical and genetic bases have been determined, and new therapies have been under development for several of these conditions. Gene therapy research has generated proof-of-concept for GSD types I (von Gierke disease) and II (Pompe disease). Key features of these gene therapy strategies include the choice of vector and regulatory cassette, and recently adeno-associated virus (AAV) vectors containing tissue-specific promoters have achieved a high degree of efficacy. Efficacy of gene therapy for Pompe disease depend upon the induction of immune tolerance to the therapeutic enzyme. Efficacy of von Gierke disease is transient, waning gradually over the months following vector administration. Small molecule therapies have been evaluated with the goal of improving standard of care therapy or ameliorating the cellular abnormalities associated with specific GSDs. The receptor-mediated uptake of the therapeutic enzyme in Pompe disease was enhanced by administration of β2 agonists. Rapamycin reduced the liver fibrosis observed in GSD III. Further development of gene therapy could provide curative therapy for patients with GSD, if efficacy from preclinical research is observed in future clinical trials and these treatments become clinically available.

  17. Serum lipoproteins of patients with glycogen storage disease.

    PubMed

    Rosenfeld, E L; Chibisov, I V; Karmansky, I M; Tabolin, V A; Chistova, L V; Leontiev, A F

    1980-03-14

    Seventeen patients with different types of glycogen storage disease (GSD) were under observation. The type of the disease was defined from glucaemic and lactotaemic curves obtained in glucose, galactose and adrenaline tolerance tests and by biochemical analysis of liver biopsy specimens. Seven patients were found to have Type I; five patients, Type III; one patient, Type VI; and four patients, the Type IX (or X) of GSD. The serum lipoprotein (LP) content was determined in all patients using analytical ultracentrifugation. Hyperlipoproteinaemia (HLP) was found in virtually all patients. Patients with Type I of GSD were found to have Types 2b and 4 of HLP; and patients with Type III of GSD, 2b Type of HLP. 2a Type of HLP was diagnosed in patients with GSD of VI and IX (X) Types. Patients with Type III GSD, in contrast to those with GSD of other types, had enhanced levels of Sf 12-20 LP. The levels of Sf 100-400 and Sf 20-100 LP were greatly increased only in patients with Type I GSD.

  18. The role of glycogen synthase kinase-3beta in schizophrenia.

    PubMed

    Koros, Eliza; Dorner-Ciossek, Cornelia

    2007-09-01

    Glycogen synthase kinase (GSK)-3beta is recognized as a ubiquitous multifunctional enzyme involved in the modulation of many aspects of neuronal function. Inhibitory control of GSK-3beta has been identified to be crucial for the phosphoinositide 3'-kinase (PI3K)-protein kinase B (Akt)-mediated cell survival. Several lines of evidence converge in implicating abnormal GSK-3beta activity in the pathogenesis of schizophrenia. Preclinical evidence showing that both typical and atypical antipsychotics can indirectly inhibit the activity of GSK-3beta, has pointed to GSK-3beta as a possible therapeutic target for schizophrenia. It is well known that GSK-3beta can be indirectly inhibited via regulation of several intracellular signaling cascades, including the canonical Wnt, Reelin and tyrosine kinase receptor (Trk)-PI3K-Akt. Recently, direct inhibition of GSK-3beta has emerged as a possible option in the pharmacotherapy of several neuropsychiatric disorders. There is, however, a number of issues that need to be considered regarding therapeutic utility of GSK-3beta inhibitors. This article reviews the evidence supporting the possible role of aberrant GSK-3beta in the pathogenesis of schizophrenia and thus suggesting GSK-3beta to be a potential therapeutic target for this disorder.

  19. Skeletal muscle respiratory capacity, endurance, and glycogen utilization.

    PubMed

    Fitts, R H; Booth, F W; Winder, W W; Holloszy, J O

    1975-04-01

    This study was undertaken to evaluate the relationship between physical performance capacity and the mitochondrial content of skeletal muscle. Four groups of rats were trained by means of treadmill running 5 days/wk for 13 wk. One group ran 10 min/day, a second group ran 30 min/day, a third group ran 60 min/day, and a fourth group ran 120 min/day. The magnitude of the exercise-induced adaptive increase in gastrocnemius muscle respiratory capacity varied over a twofold range in the four groups. There were significant correlations between the levels of three mitochondrial markers (cytochrome c, citrate synthase, respiratory capacity) in the animals' gastrocnemius muscles and the duration of a run to exhaustion. There was also a significant correlation between the amounts of glycogen remaining in liver and skeletal muscle after a 30-min-long exercise test and the respiratory capacity of the animal's leg muscles. These findings are compatible with the interpretation that a close relationshiop exists between skeletal muscle mitochondrial content and the capacity to perform endurance exercise.

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

    PubMed Central

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

    2013-01-01

    Glycogen storage disease type-Ia (GSD-Ia) patients deficient in glucose-6-phosphatase-α (G6Pase-α or G6PC) manifest impaired glucose homeostasis characterized by fasting hypoglycemia, growth retardation, hepatomegaly, nephromegaly, hyperlipidemia, hyperuricemia, and lactic acidemia. Two efficacious recombinant adeno-associated virus pseudotype 2/8 (rAAV8) vectors expressing human G6Pase-α have been independently developed. One is a single-stranded vector containing a 2864-bp of the G6PC promoter/enhancer (rAAV8-GPE) and the other is a double-stranded vector containing a shorter 382-bp minimal G6PC promoter/enhancer (rAAV8-miGPE). To identify the best construct, a direct comparison of the rAAV8-GPE and the rAAV8-miGPE vectors was initiated to determine the best vector to take forward into clinical trials. We show that the rAAV8-GPE vector directed significantly higher levels of hepatic G6Pase-α expression, achieved greater reduction in hepatic glycogen accumulation, and led to a better toleration of fasting in GSD-Ia mice than the rAAV8-miGPE vector. Our results indicated that additional control elements in the rAAV8-GPE vector outweigh the gains from the double-stranded rAAV8-miGPE transduction efficiency, and that the rAAV8-GPE vector is the current choice for clinical translation in human GSD-Ia. PMID:23856420

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

    PubMed

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

    2013-11-01

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

  2. Cyclin-Dependent kinase 5 targeting prevents β-Amyloid aggregation involving glycogen synthase kinase 3β and phosphatases.

    PubMed

    Castro-Alvarez, John Fredy; Uribe-Arias, Alejandro; Cardona-Gómez, Gloria Patricia

    2015-08-01

    Inappropriate activation of cyclin-dependent kinase 5 (CDK5) resulting from proteolytic release of the activator fragment p25 from the membrane contributes to the formation of neurofibrillary tangles, β-amyloid (βA) aggregation, and chronic neurodegeneration. At 18 months of age, 3× Tg-AD mice were sacrificed after either 3 weeks (short term) or 1 year (long term) of CDK5 knockdown. In short-term-treated animals, CDK5 knockdown reversed βA aggregation in the hippocampi via inhibitory phosphorylation of glycogen synthase kinase 3β Ser9 and activation of phosphatase PP2A. In long-term-treated animals, CDK5 knockdown induced a persistent reduction in CDK5 and prevented βA aggregation, but the effect on amyloid precursor protein processing was reduced, suggesting that yearly booster therapy would be required. These findings further validate CDK5 as a target for preventing or blocking amyloidosis in older transgenic mice.

  3. Hepatic differentiation of embryonic stem cells by murine fetal liver mesenchymal cells.

    PubMed

    Ishii, Takamichi; Yasuchika, Kentaro; Ikai, Iwao

    2013-01-01

    Hepatocytes derived from embryonic stem cells (ESCs) are a potential cell source for regenerative medicine. However, it has been technically difficult to differentiate ESCs into mature hepatocytes because the definitive growth factors and molecular mechanisms governing hepatocyte differentiation have not yet been well defined. The CD45(-)CD49f(+/-)Thy1(+)gp38(+) mesenchymal cells that reside in murine fetal livers induce hepatic progenitor cells to differentiate into mature hepatocytes by direct cell-cell contact. Utilizing these cells, we employ a two-step procedure for hepatic maturation of ESCs: first, ESCs are differentiated into endodermal cells or hepatic progenitor cells, and second, ESC-derived endodermal cells are matured into functional hepatocytes by coculture with murine fetal liver mesenchymal cells. The ESC-derived hepatocyte-like cells possess hepatic functions, including ammonia removal activity, albumin secretion ability, glycogen synthesis and storage, and cytochrome P450 enzymatic activity.

  4. Glycogen content and excitation-contraction coupling in mechanically skinned muscle fibres of the cane toad.

    PubMed

    Stephenson, D G; Nguyen, L T; Stephenson, G M

    1999-08-15

    1. Mechanically skinned skeletal muscle fibres from the twitch region of the iliofibularis muscle of cane toads were used to investigate the relationship between fibre glycogen content and fibre capacity to respond to transverse tubular (T-) system depolarization. 2. A large proportion of total fibre glycogen remained in mechanically skinned muscle fibres exposed to aqueous solutions. This glycogen pool (about 80% of total fibre glycogen) was very stable when the preparation was incubated in a rigor solution (pH 7.0) but decreased gradually at a rate of 0.59+/-0.20% min-1 in a relaxing solution (200 nM [Ca2+]). The rate was considerably higher (2.66+/-0.38% min(-1)) when the preparations were exposed to 30 microM [Ca2+]. An even greater rate of glycogen loss was found after T-system depolarization-induced contractions. The Ca2+-dependent loss of fibre glycogen was caused by endogenous glycogenolytic processes. 3. Silver stained SDS gels of components eluted into relaxing solution from single skinned fibres revealed a rapid (2 min) loss of parvalbumin and at least 10 other proteins varying in molecular mass between 10 and 80 kDa but there was essentially no loss of myosin heavy and light chains and actin. Subsequent elution for a further 30 min in either relaxing or maximally Ca2+-activating solution did not result in additional, appreciable detectable loss of fibre protein. 4. Depletion of fibre glycogen was associated with loss of fibre ability to respond to T-system depolarization even though the bathing solutions contained high levels of ATP (8 mM) and creatine phosphate (10 mM). 5. The capacity of mechanically skinned fibres to respond to T-system depolarization was highly positively correlated (P<0.0001) with initial fibre glycogen concentration. 6. In conclusion, the results show that (i) the capacity of skeletal muscle to respond to T-system depolarization is related directly or indirectly to the non-washable glycogen pool in fibres, (ii) this relationship

  5. Gene expression profiling of mice with genetically modified muscle glycogen content.

    PubMed

    Parker, Gretchen E; Pederson, Bartholomew A; Obayashi, Mariko; Schroeder, Jill M; Harris, Robert A; Roach, Peter J

    2006-04-01

    Glycogen, a branched polymer of glucose, forms an energy re-serve in numerous organisms. In mammals, the two largest glyco-gen stores are in skeletal muscle and liver, which express tissue-specific glycogen synthase isoforms. MGSKO mice, in which mGys1 (mouse glycogen synthase) is disrupted, are devoid of muscle glycogen [Pederson, Chen, Schroeder, Shou, DePaoli-Roach and Roach (2004) Mol. Cell. Biol. 24, 7179-7187]. The GSL30 mouse line hyper-accumulates glycogen in muscle [Manchester, Skurat, Roach, Hauschka and Lawrence (1996) Proc. Natl. Acad. Sci. U.S.A. 93, 10707-10711]. We performed a microarray analysis of mRNA from the anterior tibialis, medial gastrocnemius and liver of MGSKO mice, and from the gastroc-nemius of GSL30 mice. In MGSKO mice, transcripts of 79 genes varied in their expression in the same direction in both the anterior tibialis and gastrocnemius. These included several genes encoding proteins proximally involved in glycogen metabolism. The Ppp1r1a [protein phosphatase 1 regulatory (inhibitor) sub-unit 1A] gene underwent the greatest amount of downregulation. In muscle, the downregulation of Pfkfb1 and Pfkfb3, encoding isoforms of 6-phosphofructo-2-kinase/fructose-2,6-bisphospha-tase, is consistent with decreased glycolysis. Pathways for branched-chain amino acid, and ketone body utilization appear to be downregulated, as is the capacity to form the gluconeogenic precursors alanine, lactate and glutamine. Expression changes among several members of the Wnt signalling pathway were identified, suggesting an as yet unexplained role in glycogen meta-bolism. In liver, the upregulation of Pfkfb1 and Pfkfb3 expression is consistent with increased glycolysis, perhaps as an adaptation to altered muscle metabolism. By comparing changes in muscle expression between MGSKO and GSL30 mice, we found a subset of 44 genes, the expression of which varied as a function of muscle glycogen content. These genes are candidates for regulation by glycogen levels

  6. Methodologies of tissue preservation and analysis of the glycogen content of the broiler chick liver.

    PubMed

    Bennett, L W; Keirs, R W; Peebles, E D; Gerard, P D

    2007-12-01

    The current study was performed to develop convenient, rapid, reliable, and pragmatic methodologies by which to harvest and preserve liver tissue glycogen and to analyze its levels within reasonable limits of quantification and with extended chromophore stability. Absorbance values decreased by 2 h and again by 24 h after preparation of the iodine-potassium iodide chromophore, whereas absorbance values of the phenol-sulfuric acid chromophore remained constant over the same time period. These absorbance trends for each chromophore followed full color development within 5 min after combining the analyte with the respective chromophore reagent. Use of the phenol-sulfuric acid reagent allowed for a 10-fold reduction in assay limits of detection and quantification when compared with the iodine-potassium iodide reagent. Furthermore, glycogen concentration-absorbance relationships were affected by the source (i.e., rabbit liver vs. bovine liver) of glycogen standards when the iodine-potassium iodide chromophore was used, but the source of the standards had no influence when the phenol-sulfuric acid chromophore was used. The indifference of the phenol-sulfuric acid method to the glycogen source, as exhibited by similar linear regressions of absorbance, may be attributed to actual determination of glucose subunit concentrations after complete glycogen hydrolysis by sulfuric acid. This is in contrast to the actual measurement of whole glycogen, which may exhibit source- or time-related molecular structural differences. The iodine-potassium iodide methodology is a test of whole glycogen concentrations; therefore, it may be influenced by glycogen structural differences. Liver tissue sample weight (between 0.16 and 0.36 g) and processing, which included mincing, immediate freezing, or refrigeration in 10% perchloric acid for 1 wk prior to tissue grinding, had no effect on glycogen concentrations that were analyzed by using the phenol-sulfuric acid reagent. These results

  7. Hepatitis B virus (image)

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    Hepatitis B is also known as serum hepatitis and is spread through blood and sexual contact. It is ... population. This photograph is an electronmicroscopic image of hepatitis B virus particles. (Image courtesy of the Centers for ...

  8. Hepatitis Risk Assessment

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  9. Preventing hepatitis A

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    Hepatitis A is inflammation (irritation and swelling) of the liver caused by the hepatitis A virus. You can take several steps to ... reduce your risk of spreading or catching the hepatitis A virus: Always wash your hands thoroughly after ...

  10. Hepatitis B Test

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    ... AACC products and services. Advertising & Sponsorship: Policy | Opportunities Hepatitis B Testing Share this page: Was this page ... known as: HBV Tests; Hep B; anti-HBs; Hepatitis B Surface Antibody; HBsAg; Hepatitis B Surface Antigen; ...

  11. HIV and Hepatitis C

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    ... AIDS-Related Opportunistic Infections and Coinfections HIV and Hepatitis C (Last updated 8/31/2016; last reviewed ... the medicines for any side effects. What is hepatitis C? Hepatitis C is a liver disease caused ...

  12. HIV and Hepatitis B

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    ... AIDS-Related Opportunistic Infections and Coinfections HIV and Hepatitis B (Last updated 8/31/2016; last reviewed ... should be treated for both diseases. What is hepatitis B? Hepatitis B is a liver disease caused ...

  13. Drug-induced hepatitis

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    Toxic hepatitis ... to get liver damage. Some drugs can cause hepatitis with small doses, even if the liver breakdown ... liver. Many different drugs can cause drug-induced hepatitis. Painkillers and fever reducers that contain acetaminophen are ...

  14. Adult Living with Hepatitis B

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    ... Viral Hepatitis Liver Cancer and Hepatitis B Hepatitis Delta Coinfection Hepatitis C Coinfection HIV/AIDS Coinfection Prevention & ... Institute Education & Training Hep B United Coalition Hepatitis Delta Connect 2017 International HBV Meeting National Patient Advocacy ...

  15. Glucose analogue inhibitors of glycogen phosphorylase: from crystallographic analysis to drug prediction using GRID force-field and GOLPE variable selection.

    PubMed

    Watson, K A; Mitchell, E P; Johnson, L N; Cruciani, G; Son, J C; Bichard, C J; Fleet, G W; Oikonomakos, N G; Kontou, M; Zographos, S E

    1995-07-01

    Several inhibitors of the large regulatory enzyme glycogen phosphorylase (GP) have been studied in crystallographic and kinetic experiments. GP catalyses the first step in the phosphorylysis of glycogen to glucose-l-phosphate, which is utilized via glycolysis to provide energy to sustain muscle contraction and in the liver is converted to glucose. alpha-D-Glucose is a weak inhibitor of glycogen phosphorylase form b (GPb, K(i) = 1.7 mM) and acts as a physiological regulator of hepatic glycogen metabolism. Glucose binds to phosphorylase at the catalytic site and results in a conformational change that stabilizes the inactive T state of the enzyme, promoting the action of protein phosphatase 1 and stimulating glycogen synthase. It has been suggested that in the liver, glucose analogues with greater affinity for glycogen phosphorylase may result in a more effective regulatory agent. Several N-acetyl glucopyranosylamine derivatives have been synthesized and tested in a series of crystallographic and kinetic binding studies with GPb. The structural results of the bound enzyme-ligand complexes have been analysed together with the resulting affinities in an effort to understand and exploit the molecular interactions that might give rise to a better inhibitor. Comparison of the N-methylacetyl glucopyranosylamine (N-methylamide, K(i) = 0.032 mM) with the analogous beta-methylamide derivative (C-methylamide, K(i) = 0.16 mM) illustrate the importance of forming good hydrogen bonds and obtaining complementarity of van der Waals interactions. These studies also have shown that the binding modes can be unpredictable but may be rationalized with the benefit of structural data and that a buried and mixed polar/non-polar catalytic site poses problems for the systematic addition of functional groups. Together with previous studies of glucose analogue inhibitors of GPb, this work forms the basis of a training set suitable for three-dimensional quantitative structure

  16. Bone mineral density in glycogen storage disease type Ia and Ib.

    PubMed

    Minarich, Laurie A; Kirpich, Alexander; Fiske, Laurie M; Weinstein, David A

    2012-04-05

    Purpose:The aim of this study was to characterize the pathogenesis of low bone mineral density in glycogen storage disease type Ia and Ib.Methods:A retrospective chart review performed at the University of Florida Glycogen Storage Disease Program included patients with glycogen storage disease type Ia and Ib for whom dual-energy X-ray absorptiometry analysis was performed. A Z-score less than -2 SD was considered low. Analysis for association of bone mineral density with age, gender, presence of complications, mean triglyceride and 25-hydroxyvitamin D concentrations, erythrocyte sedimentation rate, duration of granulocyte colony-stimulating factor therapy, and history of corticosteroid use was performed.Results:In glycogen storage disease Ia, 23/42 patients (55%) had low bone mineral density. Low bone mineral density was associated with other disease complications (P = 0.02) and lower mean serum 25-hydroxyvitamin D concentration (P = 0.03). There was a nonsignificant trend toward lower mean triglyceride concentration in the normal bone mineral density group (P = 0.1).In patients with glycogen storage disease type Ib, 8/12 (66.7%) had low bone mineral density. We did not detect an association with duration of granulocyte colony-stimulating factor therapy (P = 0.68), mean triglyceride level (P = 0.267), erythrocyte sedimentation rate (P = 0.3), or 25-hydroxyvitamin D (P = 0.63) concentration, and there was no evidence that corticosteroid therapy was associated with lower bone mineral density (P = 1).Conclusion:In glycogen storage disease type Ia, bone mineral density is associated with other complications and 25-hydroxyvitamin D status. In glycogen storage disease type Ib, bone mineral density was not associated with any covariates analyzed, suggesting multifactorial etiology or reflecting a small sample.Genet Med advance online publication 5 April 2012.

  17. Characterization of a canine model of glycogen storage disease type IIIa.

    PubMed

    Yi, Haiqing; Thurberg, Beth L; Curtis, Sarah; Austin, Stephanie; Fyfe, John; Koeberl, Dwight D; Kishnani, Priya S; Sun, Baodong

    2012-11-01

    Glycogen storage disease type IIIa (GSD IIIa) is an autosomal recessive disease caused by deficiency of glycogen debranching enzyme (GDE) in liver and muscle. The disorder is clinically heterogeneous and progressive, and there is no effective treatment. Previously, a naturally occurring dog model for this condition was identified in curly-coated retrievers (CCR). The affected dogs carry a frame-shift mutation in the GDE gene and have no detectable GDE activity in liver and muscle. We characterized in detail the disease expression and progression in eight dogs from age 2 to 16 months. Monthly blood biochemistry revealed elevated and gradually increasing serum alanine transaminase (ALT), aspartate transaminase (AST) and alkaline phosphatase (ALP) activities; serum creatine phosphokinase (CPK) activity exceeded normal range after 12 months. Analysis of tissue biopsy specimens at 4, 12 and 16 months revealed abnormally high glycogen contents in liver and muscle of all dogs. Fasting liver glycogen content increased from 4 months to 12 months, but dropped at 16 months possibly caused by extended fibrosis; muscle glycogen content continually increased with age. Light microscopy revealed significant glycogen accumulation in hepatocytes at all ages. Liver histology showed progressive, age-related fibrosis. In muscle, scattered cytoplasmic glycogen deposits were present in most cells at 4 months, but large, lake-like accumulation developed by 12 and 16 months. Disruption of the contractile apparatus and fraying of myofibrils was observed in muscle at 12 and 16 months by electron microscopy. In conclusion, the CCR dogs are an accurate model of GSD IIIa that will improve our understanding of the disease progression and allow opportunities to investigate treatment interventions.

  18. Characterization of a canine model of glycogen storage disease type IIIa

    PubMed Central

    Yi, Haiqing; Thurberg, Beth L.; Curtis, Sarah; Austin, Stephanie; Fyfe, John; Koeberl, Dwight D.; Kishnani, Priya S.; Sun, Baodong

    2012-01-01

    SUMMARY Glycogen storage disease type IIIa (GSD IIIa) is an autosomal recessive disease caused by deficiency of glycogen debranching enzyme (GDE) in liver and muscle. The disorder is clinically heterogeneous and progressive, and there is no effective treatment. Previously, a naturally occurring dog model for this condition was identified in curly-coated retrievers (CCR). The affected dogs carry a frame-shift mutation in the GDE gene and have no detectable GDE activity in liver and muscle. We characterized in detail the disease expression and progression in eight dogs from age 2 to 16 months. Monthly blood biochemistry revealed elevated and gradually increasing serum alanine transaminase (ALT), aspartate transaminase (AST) and alkaline phosphatase (ALP) activities; serum creatine phosphokinase (CPK) activity exceeded normal range after 12 months. Analysis of tissue biopsy specimens at 4, 12 and 16 months revealed abnormally high glycogen contents in liver and muscle of all dogs. Fasting liver glycogen content increased from 4 months to 12 months, but dropped at 16 months possibly caused by extended fibrosis; muscle glycogen content continually increased with age. Light microscopy revealed significant glycogen accumulation in hepatocytes at all ages. Liver histology showed progressive, age-related fibrosis. In muscle, scattered cytoplasmic glycogen deposits were present in most cells at 4 months, but large, lake-like accumulation developed by 12 and 16 months. Disruption of the contractile apparatus and fraying of myofibrils was observed in muscle at 12 and 16 months by electron microscopy. In conclusion, the CCR dogs are an accurate model of GSD IIIa that will improve our understanding of the disease progression and allow opportunities to investigate treatment interventions. PMID:22736456

  19. Dorsomedial hindbrain catecholamine regulation of hypothalamic astrocyte glycogen metabolic enzyme protein expression: Impact of estradiol.

    PubMed

    Tamrakar, P; Shrestha, P K; Briski, K P

    2015-04-30

    The brain astrocyte glycogen reservoir is a vital energy reserve and, in the cerebral cortex, subject among other factors to noradrenergic control. The ovarian steroid estradiol potently stimulates nerve cell aerobic respiration, but its role in glial glycogen metabolism during energy homeostasis or mismatched substrate supply/demand is unclear. This study examined the premise that estradiol regulates hypothalamic astrocyte glycogen metabolic enzyme protein expression during normo- and hypoglycemia in vivo through dorsomedial hindbrain catecholamine (CA)-dependent mechanisms. Individual astrocytes identified in situ by glial fibrillary acidic protein immunolabeling were laser-microdissected from the ventromedial hypothalamic (VMH), arcuate hypothalamic (ARH), and paraventricular hypothalamic (PVH) nuclei and the lateral hypothalamic area (LHA) of estradiol (E)- or oil (O)-implanted ovariectomized (OVX) rats after insulin or vehicle injection, and pooled within each site. Stimulation [VMH, LHA] or suppression [PVH, ARH] of basal glycogen synthase (GS) protein expression by E was reversed in the former three sites by caudal fourth ventricular pretreatment with the CA neurotoxin 6-hydroxydopamine (6-OHDA). E diminished glycogen phosphorylase (GP) protein profiles by CA-dependent [VMH, PVH] or -independent mechanisms [LHA]. Insulin-induced hypoglycemia (IIH) increased GS expression in the PVH in OVX+E, but reduced this protein in the PVH, ARH, and LHA in OVX+O. Moreover, IIH augmented GP expression in the VMH, LHA, and ARH in OVX+E and in the ARH in OVX+O, responses that normalized by 6-OHDA. Results demonstrate site-specific effects of E on astrocyte glycogen metabolic enzyme expression in the female rat hypothalamus, and identify locations where dorsomedial hindbrain CA input is required for such action. Evidence that E correspondingly increases and reduces basal GS and GP in the VMH and LHA, but augments the latter protein during IIH suggests that E regulates

  20. Influence of differing macronutrient intakes on muscle glycogen resynthesis after resistance exercise.

    PubMed

    Roy, B D; Tarnopolsky, M A

    1998-03-01

    The provision of additional protein (Pro) to a carbohydrate (CHO) supplement resulted in an enhanced rate of muscle glycogen resynthesis after endurance exercise (Zawadzki et al., J. Appl. Physiol. 72: 1854-1859, 1992). A comparison of isoenergetic CHO and CHO/Pro formula drinks on muscle glycogen resynthesis has not been examined after either endurance or resistance exercise. We studied the effect of isoenergetic CHO (1 g/kg) and CHO/Pro/fat (66% CHO, 23% Pro, 11% fat) defined formula drinks and placebo (Pl) given immediately (t = 0 h) and 1 h (t = +1 h) after resistance exercise in 10 healthy young men. They performed a whole body workout (9 exercises/3 sets at 80% 1 repetition maximum) with unilateral knee extension exercise [exercise (Ex) and control (Con) leg]. The CHO/Pro/fat and CHO trials resulted in significantly greater (P < 0. 05) plasma insulin and glucose concentration compared with Pl. Muscle glycogen was significantly lower (P < 0.05) for the Ex vs. Con leg immediately postexercise for all three conditions. The rate of glycogen resynthesis was significantly greater (P < 0.05) for both CHO/Pro/fat and CHO (23.0 +/- 4.5 and 19.3 +/- 6.1 mmol . kg dry muscle-1 . h-1, respectively) vs. Pl (Ex = 2.8 +/- 2.3 and Con = 1.4 +/- 3.6 mmol . kg dry muscle-1 . h-1). These results demonstrated that a bout of resistance exercise resulted in a significant decrease in muscle glycogen and that consumption of an isoenergetic CHO or CHO/Pro/fat formula drink resulted in similar rates of muscle glycogen resynthesis after resistance exercise. This suggests that total energy content and CHO content are important in the resynthesis of muscle glycogen.

  1. The appearance and degradation of specific hepatocellular cytoplasmic inclusion bodies in rat liver due to D-galactosamine. I. The relation between the amount of liver glycogen and the appearance of the atypical dense bodies in the liver cell.

    PubMed

    Lesch, R; Meinhardt, K; Häberle, B; Enzan, H

    1976-10-01

    One of the most sensitive and specific signs of the galactosamine effect upon the rat liver cell is the appearance of PAS-positive and diastase-resistant granules within the cytoplasm of hepatocytes. Light-microscopic, histochemical, biochemical, and electron-microscopic findings reveal that the appearance of these ADB (= atypical dense bodies) depends upon a working glycogen metabolism at the time of GalN treatment. The ADB are composed of particles resembling, due to shape and size, ribosomes and beta particles of glycogen. Most of them are surrounded by the rER, but they are never enclosed by a limiting membrane. Due to sequential changes they can be generally classified into three types; the early, the intermediate, and the late type. In seven experiments it can be shown, that the appearance of the ADB depends upon the time and dosage after GalN treatment. They occur even if an additional treatment with galactose or uridine prevents the liver from the features of a hepatitis, as also shown in the livers of newborn animals up to 3 weeks of age. The histochemical response against various glucosidases, hexosaminidases, pronase, and RNAse as well as against various fixatives indicates that ADB are composed of, at least, two different constituents, the former RNAse-sensitive and visible with routine light-microscopic staining procedures, the latter RNA-resistant, PAS-positive, and invisible after staining with H & E or toluidine blue. The latter is diastase-resistant, suggesting that this portion of ADB does not represent the usual glycoproteins but some abnormal metabolite of glycogen. The ADB can be detected with maximal accumulation in the cytoplasm of hepatocytes at that time when the glycogen content determined in the liver homogenate by biochemical methods is greatly reduced.

  2. Gene Therapy for Type I Glycogen Storage Diseases

    PubMed Central

    Chou, Janice Y.; Mansfield, Brian C.

    2008-01-01

    The type I glycogen storage diseases (GSD-I) are a group of related diseases caused by a deficiency in the glucose-6-phosphatase-α (G6Pase-α) system, a key enzyme complex that is essential for the maintenance of blood glucose homeostasis between meals. The complex consists of a glucose-6-phosphate transporter (G6PT) that translocates glucose-6-phosphate from the cytoplasm into the lumen of the endoplasmic reticulum, and a G6Pase-α catalytic unit that hydrolyses the glucose-6-phosphate into glucose and phosphate. A deficiency in G6Pase-α causes GSD type Ia (GSD-Ia) and a deficiency in G6PT causes GSD type Ib (GSD-Ib). Both GSD-Ia and GSD-Ib patients manifest a disturbed glucose homeostasis, while GSD-Ib patients also suffer symptoms of neutropenia and myeloid dysfunctions. G6Pase-α and G6PT are both hydrophobic endoplasmic reticulum-associated transmembrane proteins that can not expressed in soluble active forms. Therefore protein replacement therapy of GSD-I is not an option. Animal models of GSD-Ia and GSD-Ib that mimic the human disorders are available. Both adenovirus- and adeno-associated virus (AAV)-mediated gene therapies have been evaluated for GSD-Ia in these model systems. While adenoviral therapy produces only short term corrections and only impacts liver expression of the gene, AAV-mediated therapy delivers the transgene to both the liver and kidney, achieving longer term correction of the GSD-Ia disorder, although there are substantial differences in efficacy depending on the AAV serotype used. Gene therapy for GSD-Ib in the animal model is still in its infancy, although an adenoviral construct has improved the metabolic profile and myeloid function. Taken together further refinements in gene therapy may hold long term benefits for the treatment of type I GSD disorders. PMID:17430128

  3. Hepatitis B Vaccine

    MedlinePlus

    ... a combination product containing Haemophilus influenzae type b, Hepatitis B Vaccine) ... combination product containing Diphtheria, Tetanus Toxoids, Acellular Pertussis, Hepatitis B, Polio Vaccine)

  4. Genetic regulation of glycogen biosynthesis in Escherichia coli: in vitro effects of cyclic AMP and guanosine 5'-diphosphate 3'-diphosphate and analysis of in vivo transcripts.

    PubMed Central

    Romeo, T; Preiss, J

    1989-01-01

    Glycogen accumulation in Escherichia coli is inversely related to the growth rate and occurs most actively when cells enter the stationary phase. The levels of the three biosynthetic enzymes undergo corresponding changes under these conditions, suggesting that genetic control of enzyme biosynthesis may account for at least part of the regulation (J. Preiss, Annu. Rev. Microbiol. 38:419-458, 1984). We have begun to explore the molecular basis of this control by identifying factors which affect the expression of the glycogen genes and by determining the 5'-flanking regions required to mediate the regulatory effects. The in vitro coupled transcription-translation of two of the biosynthetic genes, glgC (ADPglucose pyrophosphorylase) and glgA (glycogen synthase), was enhanced up to 26- and 10-fold, respectively, by cyclic AMP (cAMP) and cAMP receptor protein (CRP). Guanosine 5'-diphosphate 3'-diphosphate stimulated the expression of these genes 3.6- and 1.8-fold, respectively. The expression of glgB (glycogen branching enzyme) was affected weakly or negligibly by the above-mentioned compounds. Assays which measured the in vitro formation of the first dipeptide of glgC showed that a restriction fragment which contained 0.5 kilobases of DNA upstream from the initiation codon supported cAMP-CRP-activated expression. Sequence-specific binding of cAMP-CRP to a 243-base-pair restriction fragment from the region upstream from glgC was observed by virtue of the altered electrophoretic mobility of the bound DNA. S1 nuclease protection analysis identified 5' termini of four in vivo transcripts within 0.5 kilobases of the glgC coding region. The relative concentrations of transcripts were higher in the early stationary phase than in the exponential phase. Two mutants which overproduced the biosynthesis enzymes accumulated elevated levels of specific transcripts. The 5' termini of three of the transcripts were mapped to a high resolution. Their upstream sequences showed weak

  5. Impaired glycogen synthesis causes metabolic overflow reactions and affects stress responses in the cyanobacterium Synechocystis sp. PCC 6803.

    PubMed

    Gründel, Marianne; Scheunemann, Ramon; Lockau, Wolfgang; Zilliges, Yvonne

    2012-12-01

    The biosynthesis of glycogen or starch is one of the main strategies developed by living organisms for the intracellular storage of carbon and energy. In phototrophic organisms, such polyglucans accumulate due to carbon fixation during photosynthesis and are used to provide maintenance energy for cell integrity, function and viability in dark periods. Moreover, it is assumed that glycogen enables cyanobacteria to cope with transient starvation conditions, as observed in most micro-organisms. Here, glycogen accumulates when an appropriate carbon source is available in sufficient amounts but growth is inhibited by lack of other nutrients. In this study, the role of glycogen in energy and carbon metabolism of phototrophic cyanobacteria was first analysed via a comparative physiological and metabolic characterization of knockout mutants defective in glycogen synthesis. We first proved the role of glycogen as a respiratory substrate in periods of darkness, the role of glycogen as a reserve to survive starvation periods such as nitrogen depletion and the role of glycogen synthesis as an ameliorator of carbon excess conditions in the model organism Synechocystis sp. PCC 6803. We provide striking new insights into the complex carbon and nitrogen metabolism of non-diazotrophic cyanobacteria: a phenotype of sensitivity to photomixotrophic conditions and of reduced glucose uptake, a non-bleaching phenotype based on an impaired acclimation response to nitrogen depletion and furthermore a phenotype of energy spilling. This study shows that the analysis of deficiencies in glycogen metabolism is a valuable tool for the identification of metabolic regulatory principles and signals.

  6. Structural basis for glycogen recognition by AMP-activated protein kinase.

    PubMed

    Polekhina, Galina; Gupta, Abhilasha; van Denderen, Bryce J W; Feil, Susanne C; Kemp, Bruce E; Stapleton, David; Parker, Michael W

    2005-10-01

    AMP-activated protein kinase (AMPK) coordinates cellular metabolism in response to energy demand as well as to a variety of stimuli. The AMPK beta subunit acts as a scaffold for the alpha catalytic and gamma regulatory subunits and targets the AMPK heterotrimer to glycogen. We have determined the structure of the AMPK beta glycogen binding domain in complex with beta-cyclodextrin. The structure reveals a carbohydrate binding pocket that consolidates all known aspects of carbohydrate binding observed in starch binding domains into one site, with extensive contact between several residues and five glucose units. beta-cyclodextrin is held in a pincer-like grasp with two tryptophan residues cradling two beta-cyclodextrin glucose units and a leucine residue piercing the beta-cyclodextrin ring. Mutation of key beta-cyclodextrin binding residues either partially or completely prevents the glycogen binding domain from binding glycogen. Modeling suggests that this binding pocket enables AMPK to interact with glycogen anywhere across the carbohydrate's helical surface.

  7. The molecular basis of glycogen breakdown and transport in Streptococcus pneumoniae.

    PubMed

    Abbott, D Wade; Higgins, Melanie A; Hyrnuik, Susanne; Pluvinage, Benjamin; Lammerts van Bueren, Alicia; Boraston, Alisdair B

    2010-07-01

    The genome of Streptococcus pneumoniae strains, as typified by the TIGR4 strain, contain several genes encoding proteins putatively involved in alpha-glucan degradation, modification and synthesis. The extracellular components comprise an ATP binding cassette-transporter with its solute binding protein, MalX, and the hydrolytic enzyme SpuA. We show that of the commonly occurring exogenous alpha-glucans, S. pneumoniae TIGR4 is only able to grow on glycogen in a MalX- and SpuA-dependent manner. SpuA is able to degrade glycogen into a ladder of alpha-1,4-glucooligosaccharides while the high-affinity interaction (K(a) approximately 10(6) M(-1)) of MalX with maltooligosaccharides plays a key role in promoting the selective uptake of the glycogen degradation products that are produced by SpuA. The X-ray crystallographic analyses of apo- and complexed MalX illuminate the protein's specificity for the degradation products of glycogen and its striking ability to recognize the helical structure of the ligand. Overall, the results of this work provide new structural and functional insight into streptococcal alpha-glucan metabolism while supplying biochemical support for the hypothesis that the substrate of the S. pneumoniaealpha-glucan metabolizing machinery is glycogen, which in a human host is abundant in lung epithelial cells, a common target for invasive S. pneumoniae.

  8. Nonlethal evaluation of the physiological health of unionid mussels: Method for biopsy and glycogen analysis

    USGS Publications Warehouse

    Naimo, T.J.; Damschen, E.D.; Rada, R.G.; Monroe, E.M.

    1998-01-01

    In long-lived unionid mussels, many short-term measures of growth are of limited value. Changes in physiological condition may be an early indication of stress, because the increased energy demand associated with stress often results in a depletion of glycogen reserves, the principal storage form of carbohydrates in unionid mussels. Our goal was to nonlethally extract tissue from freshwater mussels and then to develop a rapid and dependable method for the analysis of glycogen in the tissue extracts. A biopsy technique was developed to remove between 5 and 10 mg of food tissue in Amblema plicata plicata. The survival rate did not differ between biopsied and non-biopsied mussels during a 581-d observation period, demonstrating that the biopsy technique will allow nonlethal evaluation of the physiological condition of individual mussels through measurement of changes in contaminant, genetic, and biochemical indicators in tissue. We also modified the standard alkaline digestion and phenol-sulfuric acid analysis of glycogen for use on the small samples of biopsied tissue and to reduce analysis time and cost. We present quality control data, including method detection limits and estimates of precision and bias. The modified analytical method is rapid and accurate and has a method detection limit of 0.014 mg glycogen. Glycogen content in the biopsied samples was well above the method detection limit; it ranged from 0.09 to 0.36 mg, indicating that the method should be applicable to native mussels.

  9. Platelet-derived growth factor (PDGF) stimulates glycogen synthase activity in 3T3 cells

    SciTech Connect

    Chan, C.P.; Bowen-Pope, D.F.; Ross, R.; Krebs, E.G.

    1986-05-01

    Hormonal regulation of glycogen synthase, an enzyme that can be phosphorylated on multiple sites, is often associated with changes in its phosphorylation state. Enzyme activation is conventionally monitored by determining the synthase activity ratio ((activity in the absence of glucose 6-P)/(activity in the presence of glucose 6-P)). Insulin causes an activation of glycogen synthase with a concomitant decrease in its phosphate content. In a previous report, the authors showed that epidermal growth factor (EGF) increases the glycogen synthase activity ratio in Swiss 3T3 cells. The time and dose-dependency of this response was similar to that of insulin. Their recent results indicate that PDGF also stimulates glycogen synthase activity. Enzyme activation was maximal after 30 min. of incubation with PDGF; the time course observed was very similar to that with insulin and EGF. At 1 ng/ml (0.03nM), PDGF caused a maximal stimulation of 4-fold in synthase activity ratio. Half-maximal stimulation was observed at 0.2 ng/ml (6 pM). The time course of changes in enzyme activity ratio closely followed that of /sup 125/I-PDGF binding. The authors data suggest that PDGF, as well as EFG and insulin, may be important in regulating glycogen synthesis through phosphorylation/dephosphorylation mechanisms.

  10. Glycogen synthase (GYS1) mutation causes a novel skeletal muscle glycogenosis

    PubMed Central

    McCue, Molly E; Valberg, Stephanie J; Miller, Michael B; Wade, Claire; DiMauro, Salvatore; Akman, Hasan O; Mickelson, James R

    2008-01-01

    Summary We describe a gain of function mutation in the skeletal muscle glycogen synthase gene that is responsible for a novel myopathy, and is highly prevalent in multiple breeds of horses because it arose before the founding of many modern breeds. Polysaccharide Storage Myopathy (PSSM) is a novel glycogenosis in horses characterized by abnormal glycogen accumulation in skeletal muscle and muscle damage with exertion. It is unlike glycogen storage diseases resulting from known defects in glycogenolysis, glycolysis and glycogen synthesis that have been described in humans and domestic animals. A genome wide association identified GYS1, encoding skeletal muscle glycogen synthase (GS), as a candidate gene for PSSM. DNA sequence analysis revealed a mutation resulting in an arginine to histidine substitution in a highly conserved region of GS. Functional analysis demonstrated an elevated GS activity in PSSM horses and haplotype analysis and allele age estimation demonstrated that this mutation is identical by descent among horse breeds. This is the first report of a gain of function mutation in GYS1 resulting in a glycogenosis. PMID:18358695

  11. Homeostasis and the glycogen shunt explains aerobic ethanol production in yeast

    PubMed Central

    Shulman, Robert G.; Rothman, Douglas L.

    2015-01-01

    Aerobic glycolysis in yeast and cancer cells produces pyruvate beyond oxidative needs, a paradox noted by Warburg almost a century ago. To address this question, we reanalyzed extensive measurements from 13C magnetic resonance spectroscopy of yeast glycolysis and the coupled pathways of futile cycling and glycogen and trehalose synthesis (which we refer to as the glycogen shunt). When yeast are given a large glucose load under aerobic conditions, the fluxes of these pathways adapt to maintain homeostasis of glycolytic intermediates and ATP. The glycogen shunt uses glycolytic ATP to store glycolytic intermediates as glycogen and trehalose, generating pyruvate and ethanol as byproducts. This conclusion is supported by studies of yeast with a partial block in the glycogen shunt due to the cif mutation, which found that when challenged with glucose, the yeast cells accumulate glycolytic intermediates and ATP, which ultimately leads to cell death. The control of the relative fluxes, which is critical to maintain homeostasis, is most likely exerted by the enzymes pyruvate kinase and fructose bisphosphatase. The kinetic properties of yeast PK and mammalian PKM2, the isoform found in cancer, are similar, suggesting that the same mechanism may exist in cancer cells, which, under these conditions, could explain their excess lactate generation. The general principle that homeostasis of metabolite and ATP concentrations is a critical requirement for metabolic function suggests that enzymes and pathways that perform this critical role could be effective drug targets in cancer and other diseases. PMID:26283370

  12. Pathogenesis of growth failure and partial reversal with gene therapy in murine and canine Glycogen Storage Disease type Ia

    PubMed Central

    Brooks, Elizabeth Drake; Little, Dianne; Arumugam, Ramamani; Sun, Baodong; Curtis, Sarah; DeMaster, Amanda; Maranzano, Michael; Jackson, Mark W.; Kishnani, Priya; Freemark, Michael S.; Koeberl, Dwight D.

    2013-01-01

    Glycogen Storage Disease type Ia (GSD-Ia) in humans frequently causes delayed bone maturation, decrease in final adult height, and decreased growth velocity. This study evaluates the pathogenesis of growth failure and the effect of gene therapy on growth in GSD-Ia affected dogs and mice. Here we found that homozygous G6pase (−/−) mice with GSD-Ia have normal growth hormone (GH) levels in response to hypoglycemia, decreased insulin-like growth factor (IGF) 1 levels, and attenuated weight gain following administration of GH. Expression of hepatic GH receptor and IGF 1 mRNAs and hepatic STAT5 (phospho Y694) protein levels are reduced prior to and after GH administration, indicating GH resistance. However, restoration of G6Pase expression in the liver by treatment with adeno-associated virus 8 pseudotyped vector expressing G6Pase (AAV2/8-G6Pase) corrected body weight, but failed to normalize plasma IGF 1 in G6pase (−/−) mice. Untreated G6pase (−/−) mice also demonstrated severe delay of growth plate ossification at 12 days of age; those treated with AAV2/8-G6Pase at 14 days of age demonstrated skeletal dysplasia and limb shortening when analyzed radiographically at 6 months of age, in spite of apparent metabolic correction. Moreover, gene therapy with AAV2/9-G6Pase only partially corrected growth in GSD-Ia affected dogs as detected by weight and bone measurements and serum IGF 1 concentrations were persistently low in treated dogs. We also found that heterozygous GSD-Ia carrier dogs had decreased serum IGF 1, adult body weights and bone dimensions compared to wild-type littermates. In sum, these findings suggest that growth failure in GSD-Ia results, at least in part, from hepatic GH resistance. In addition, gene therapy improved growth in addition to promoting long-term survival in dogs and mice with GSD-Ia. PMID:23623482

  13. N-Alkylprotoporphyrin Formation and Hepatic Porphyria in Dogs After Administration of a New Antiepileptic Drug Candidate: Mechanism and Species Specificity

    PubMed Central

    Nicolas, Jean-Marie; Chanteux, Hugues; Mancel, Valérie; Dubin, Guy-Marie; Gerin, Brigitte; Staelens, Ludovicus; Depelchin, Olympe; Kervyn, Sophie

    2014-01-01

    A new antiepileptic synaptic vesicle 2a (SV2a) ligand drug candidate was tested in 4-week oral toxicity studies in rat and dog. Brown pigment inclusions were found in the liver of high-dose dogs. The morphology of the deposits and the accompanying liver changes (increased plasma liver enzymes, increased total hepatic porphyrin level, decreased liver ferrochelatase activity, combined induction, and inactivation of cytochrome P-450 CYP2B11) suggested disruption of the heme biosynthetic cascade. None of these changes was seen in rat although this species was exposed to higher parent drug levels. Toxicokinetic analysis and in vitro metabolism assays in hepatocytes showed that dog is more prone to oxidize the drug candidate than rat. Mass spectrometry analysis of liver samples from treated dogs revealed an N-alkylprotoporphyrin adduct. The elucidation of its chemical structure suggested that the drug transforms into a reactive metabolite which is structurally related to a known reference porphyrogenic agent allylisopropylacetamide. That particular metabolite, primarily produced in dog but neither in rat nor in human, has the potential to alkylate the prosthetic heme of CYP. Overall, the data suggested that the drug candidate should not be porphyrogenic in human. This case study further exemplifies the species variability in the susceptibility to drug-induced porphyria. PMID:24973095

  14. ¹³C MRS reveals a small diurnal variation in the glycogen content of human thigh muscle.

    PubMed

    Takahashi, Hideyuki; Kamei, Akiko; Osawa, Takuya; Kawahara, Takashi; Takizawa, Osamu; Maruyama, Katsuya

    2015-06-01

    There is marked diurnal variation in the glycogen content of skeletal muscles of animals, but few studies have addressed such variations in human muscles. (13)C MRS can be used to noninvasively measure the glycogen content of human skeletal muscle, but no study has explored the diurnal variations in this parameter. This study aimed to investigate whether a diurnal variation in glycogen content occurs in human muscles and, if so, to what extent it can be identified using (13)C MRS. Six male volunteers were instructed to maintain their normal diet and not to perform strenuous exercise for at least 3 days before and during the experiment. Muscle glycogen and blood glucose concentrations were measured six times in 24 h under normal conditions in these subjects. The glycogen content in the thigh muscle was determined noninvasively by natural abundance (13)C MRS using a clinical MR system at 3 T. Nutritional analysis revealed that the subjects' mean carbohydrate intake was 463 ± 137 g, being approximately 6.8 ± 2.4 g/kg body weight. The average sleeping time was 5.9 ± 1.0 h. The glycogen content in the thigh muscle at the starting point was 64.8 ± 20.6 mM. Although absolute and relative individual variations in muscle glycogen content were 7.0 ± 2.1 mM and 11.3 ± 4.6%, respectively, no significant difference in glycogen content was observed among the different time points. This study demonstrates that normal food intake (not fat and/or carbohydrate rich), sleep and other daily activities have a negligible influence on thigh muscle glycogen content, and that the diurnal variation of the glycogen content in human muscles is markedly smaller than that in animal muscles. Moreover, the present results also support the reproducibility and availability of (13)C MRS for the evaluation of the glycogen content in human muscles.

  15. Hepatitis B (HBV)

    MedlinePlus

    ... Loss Surgery? A Week of Healthy Breakfasts Shyness Hepatitis B (HBV) KidsHealth > For Teens > Hepatitis B (HBV) A A A What's in this article? ... poisons). There are several different types of hepatitis . Hepatitis B is a type that can move from one ...

  16. Pho85p, a cyclin-dependent protein kinase, and the Snf1p protein kinase act antagonistically to control glycogen accumulation in Saccharomyces cerevisiae.

    PubMed Central

    Huang, D; Farkas, I; Roach, P J

    1996-01-01

    In Saccharomyces cerevisiae, nutrient levels control multiple cellular processes. Cells lacking the SNF1 gene cannot express glucose-repressible genes and do not accumulate the storage polysaccharide glycogen. The impaired glycogen synthesis is due to maintenance of glycogen synthase in a hyperphosphorylated, inactive state. In a screen for second site suppressors of the glycogen storage defect of snf1 cells, we identified a mutant gene that restored glycogen accumulation and which was allelic with PHO85, which encodes a member of the cyclin-dependent kinase family. In cells with disrupted PHO85 genes, we observed hyperaccumulation of glycogen, activation of glycogen synthase, and impaired glycogen synthase kinase activity. In snf1 cells, glycogen synthase kinase activity was elevated. Partial purification of glycogen synthase kinase activity from yeast extracts resulted in the separation of two fractions by phenyl-Sepharose chromatography, both of which phosphorylated and inactivated glycogen synthase. The activity of one of these, GPK2, was inhibited by olomoucine, which potently inhibits cyclin-dependent protein kinases, and contained an approximately 36-kDa species that reacted with antibodies to Pho85p. Analysis of Ser-to-Ala mutations at the three potential Gsy2p phosphorylation sites in pho85 cells implicated Ser-654 and/or Thr-667 in PHO85 control of glycogen synthase. We propose that Pho85p is a physiological glycogen synthase kinase, possibly acting downstream of Snf1p. PMID:8754836

  17. Synthesis, screening and docking of small heterocycles as glycogen phosphorylase inhibitors.

    PubMed

    Schweiker, Stephanie S; Loughlin, Wendy A; Lohning, Anna S; Petersson, Maria J; Jenkins, Ian D

    2014-09-12

    A series of morpholine substituted amino acids (phenylalanine, leucine, lysine and glutamic acid) was synthesized. A fragment-based screening approach was then used to evaluate a series of small heterocycles, including morpholine, oxazoline, dihydro-1,3-oxazine, tetrahydro-1,3-oxazepine, thiazoline, tetrahydro-1,3-pyrimidine, tetrahydro-1,3-diazepine and hexahydro-1H-benzimidazole, as potential inhibitors of Glycogen Phosphorylase a. Thiazoline 7 displayed an improved potency (IC50 of 25 μM) and had good LE and LELP values, as compared to heterocycles 1, 5, 9-13 and 19 (IC50 values of 1.1 mM-23.9 mM). A docking study using the crystal structure of human liver Glycogen Phosphorylase, provided insight into the interactions of heterocycles 5, 7, 9-13 and 19 with Glycogen Phosphorylase.

  18. Glycogen storage disease type Ia and VI associated with hepatocellular carcinoma: two case reports.

    PubMed

    Manzia, T M; Angelico, R; Toti, L; Cillis, A; Ciano, P; Orlando, G; Anselmo, A; Angelico, M; Tisone, G

    2011-05-01

    Glycogen storage diseases (GSD) are inherited metabolic disorders of glycogen metabolism due to intracellular enzyme deficiency resulting in abnormal storage of glycogen in tissues. GSD represents an indication for liver transplantation (OLT) when medical treatment fails to control the metabolic dysfunction and/or there is an high risk of malignant transformation of hepatocellular adenomas (HCA). Herein we have reported two cases of GSD, type Ia and type VI, which were both associated with rapidly growing HCA, and underwent OLT because of suspect changes in their radiological features. Final histological findings in the explanted liver showed the presence of hepatocellular carcinoma (HCC) in both cases. In GSD type Ia and VI, OLT is considered to be the treatment of choice when a liver neoplasm is suspected. While the association of HCC with GSD type Ia is well known, this is the first case of HCC in GSD type VI so far reported to the best of our knowledge.

  19. Dietary tools to modulate glycogen storage in gilthead seabream muscle: glycerol supplementation.

    PubMed

    Silva, Tomé S; Matos, Elisabete; Cordeiro, Odete D; Colen, Rita; Wulff, Tune; Sampaio, Eduardo; Sousa, Vera; Valente, Luisa M P; Gonçalves, Amparo; Silva, Joana M G; Bandarra, Narcisa; Nunes, Maria Leonor; Dinis, Maria Teresa; Dias, Jorge; Jessen, Flemming; Rodrigues, Pedro M

    2012-10-24

    The quality and shelf life of fish meat products depend on the skeletal muscle's energetic state at slaughter, as meat decomposition processes can be exacerbated by energy depletion. In this study, we tested dietary glycerol as a way of replenishing muscle glycogen reserves of farmed gilthead seabream. Two diets were tested in duplicate (n = 42/tank). Results show 5% inclusion of crude glycerol in gilthead seabream diets induces increased muscle glycogen, ATP levels and firmness, with no deleterious effects in terms of growth, proximate composition, fatty acid profile, oxidative state, and organoleptic properties (aroma and color). Proteomic analysis showed a low impact of glycerol-supplementation on muscle metabolism, with most changes probably reflecting increased stress coping capacity in glycerol-fed fish. This suggests inclusion of crude glycerol in gilthead seabream diets (particularly in the finishing phase) seems like a viable strategy to increase glycogen deposition in muscle without negatively impacting fish welfare and quality.

  20. [Hepatomegaly due to glycogen storage disease and type 1 diabetes mellitus].

    PubMed

    Flotats Bastardas, M; Miserachs Barba, M; Ricart Cumeras, A; Clemente León, M; Gussinyer Canadell, M; Yeste Fernández, D; Albisu Aparicio, María A; Carrascosa Lezcano, A

    2007-08-01

    Patients with type 1 diabetes and poor metabolic control can develop hepatomegaly due to intrahepatic glycogen deposition. If these patients also have elevated liver enzymes, dyslipidemia, cushingoid features and delayed growth or sexual maturation, Mauriac syndrome can be diagnosed. This disorder is common and reversible with optimization of insulin therapy. We report three adolescents with type 1 diabetes and a long-standing history of poor glycemic control, who developed hepatomegaly, elevated liver enzymes and dyslipidemia with preserved liver function. One of these patients also had delayed growth and another had hypogonadotropic hypogonadism. Liver ultrasound showed changes suggestive of glycogenosis. In all three patients, optimization of insulin therapy achieved good glycemic control and reversed the manifestations within 2 weeks. The etiology of Mauriac syndrome is controversial since both prolonged hyperglycemia and hyperinsulinization produce glycogen accumulation in the liver. Hypercortisolism (due to ketosis or hypoglycemia) contributes to glycogen storage and also causes growth and sexual maturation delay.

  1. Purification, characterization and partial amino acid sequence of glycogen synthase from Saccharomyces cerevisiae.

    PubMed Central

    Carabaza, A; Arino, J; Fox, J W; Villar-Palasi, C; Guinovart, J J

    1990-01-01

    Glycogen synthase from Saccharomyces cerevisiae was purified to homogeneity. The enzyme showed a subunit molecular mass of 80 kDa. The holoenzyme appears to be a tetramer. Antibodies developed against purified yeast glycogen synthase inactivated the enzyme in yeast extracts and allowed the detection of the protein in Western blots. Amino acid analysis showed that the enzyme is very rich in glutamate and/or glutamine residues. The N-terminal sequence (11 amino acid residues) was determined. In addition, selected tryptic-digest peptides were purified by reverse-phase h.p.l.c. and submitted to gas-phase sequencing. Up to eight sequences (79 amino acid residues) could be aligned with the human muscle enzyme sequence. Levels of identity range between 37 and 100%, indicating that, although human and yeast glycogen synthases probably share some conserved regions, significant differences in their primary structure should be expected. Images Fig. 1. Fig. 2. Fig. 3. PMID:2114092

  2. [Glycogen storage disease by amylo 1,6-glucosidase deficiency (author's transl)].

    PubMed

    Méndez Aparicio, F M

    1980-10-01

    A case of liver glycogen storage disease with amylo 1,6-glucosidase deficiency is reported. Enlarged liver was found at birth, and it is now accompanied by splenomegaly, low fasting blood glucose with ketonuria, elevation of transaminase values and glycogen accumulation with connective periportal tissue in liver histological study. In this glucogenosis results of functional tests on carbohidrate metabolism and glycogen enzymatic assay showed a direct relationship between functional and biochemical behaviour of liver cells. Amylo 1,6-glucosidase deficiency is accompanied by absence of glucogenolysis when glucagon is administrated after a long fast, and an increase of blood glucose when glucagon is administrated after food ingestion. Glycolisis tests show blood lactate elevation when some hexose or alanine are administrated; glyconeogenesis tests show blood glucose elevation when hexose, alanine or glycerol are administrated.

  3. A mutation in PRKAG3 associated with excess glycogen content in pig skeletal muscle.

    PubMed

    Milan, D; Jeon, J T; Looft, C; Amarger, V; Robic, A; Thelander, M; Rogel-Gaillard, C; Paul, S; Iannuccelli, N; Rask, L; Ronne, H; Lundström, K; Reinsch, N; Gellin, J; Kalm, E; Roy, P L; Chardon, P; Andersson, L

    2000-05-19

    A high proportion of purebred Hampshire pigs carries the dominant RN- mutation, which causes high glycogen content in skeletal muscle. The mutation has beneficial effects on meat content but detrimental effects on processing yield. Here, it is shown that the mutation is a nonconservative substitution (R200Q) in the PRKAG3 gene, which encodes a muscle-specific isoform of the regulatory gamma subunit of adenosine monophosphate-activated protein kinase (AMPK). Loss-of-function mutations in the homologous gene in yeast (SNF4) cause defects in glucose metabolism, including glycogen storage. Further analysis of the PRKAG3 signaling pathway may provide insights into muscle physiology as well as the pathogenesis of noninsulin-dependent diabetes mellitus in humans, a metabolic disorder associated with impaired glycogen synthesis.

  4. Fetal programming of perivenous glucose uptake reveals a regulatory mechanism governing hepatic glucose output during refeeding.

    PubMed

    Murphy, Helena C; Regan, Gemma; Bogdarina, Irina G; Clark, Adrian J L; Iles, Richard A; Cohen, Robert D; Hitman, Graham A; Berry, Colin L; Coade, Zoe; Petry, Clive J; Burns, Shamus P

    2003-06-01

    Increased hepatic gluconeogenesis maintains glycemia during fasting and has been considered responsible for elevated hepatic glucose output in type 2 diabetes. Glucose derived periportally via gluconeogenesis is partially taken up perivenously in perfused liver but not in adult rats whose mothers were protein-restricted during gestation (MLP rats)-an environmental model of fetal programming of adult glucose intolerance exhibiting diminished perivenous glucokinase (GK) activity. We now show that perivenous glucose uptake rises with increasing glucose concentration (0-8 mmol/l) in control but not MLP liver, indicating that GK is flux-generating. The data demonstrate that acute control of hepatic glucose output is principally achieved by increasing perivenous glucose uptake, with rising glucose concentration during refeeding, rather than by downregulation of gluconeogenesis, which occurs in different hepatocytes. Consistent with these observations, glycogen synthesis in vivo commenced in the perivenous cells during refeeding, MLP livers accumulating less glycogen than controls. GK gene transcription was unchanged in MLP liver, the data supporting a recently proposed posttranscriptional model of GK regulation involving nuclear-cytoplasmic transport. The results are pertinent to impaired regulation of hepatic glucose output in type 2 diabetes, which could arise from diminished GK-mediated glucose uptake rather than increased gluconeogenesis.

  5. Multiple determinants influence complex formation of the hepatitis C virus NS3 protease domain with its NS4A cofactor peptide.

    PubMed

    Urbani, A; Biasiol, G; Brunetti, M; Volpari, C; Di Marco, S; Sollazzo, M; Orrú, S; Piaz, F D; Casbarra, A; Pucci, P; Nardi, C; Gallinari, P; De Francesco, R; Steinkühler, C

    1999-04-20

    The interaction of the hepatitis C virus (HCV) NS3 protease domain with its NS4A cofactor peptide (Pep4AK) was investigated at equilibrium and at pre-steady state under different physicochemical conditions. Equilibrium dissociation constants of the NS3-Pep4AK complex varied by several orders of magnitude depending on buffer additives. Glycerol, NaCl, detergents, and peptide substrates were found to stabilize this interaction. The extent of glycerol-induced stabilization varied in an HCV strain-dependent way with at least one determinant mapping to an NS3-NS4A interaction site. Conformational transitions affecting at least the first 18 amino acids of NS3 were the main energy barriers for both the association and the dissociation reactions of the complex. However, deletion of this N-terminal portion of the protease molecule only slightly influenced equilibrium dissociation constants determined under different physicochemical conditions. Limited proteolysis experiments coupled with mass spectrometric identification of cleavage fragments suggested a high degree of conformational flexibility affecting at least the first 21 residues of NS3. The accessibility of this region of the protease to limited chymotryptic digestion did not significantly change in any condition tested, whereas a significant reduction of chymotryptic cleavages within the NS3 core was detected under conditions of high NS3-Pep4AK complex affinity. We conclude the following: (1) The N-terminus of the NS3 protease that, according to the X-ray crystal structure, makes extensive contacts with the cofactor peptide is highly flexible in solution and contributes only marginally to the thermodynamic stability of the complex. (2) Affinity enhancement is accomplished by several factors through a general stabilization of the fold of the NS3 molecule.

  6. Effect of exercise-diet manipulation on muscle glycogen and its subsequent utilization during performance.

    PubMed

    Sherman, W M; Costill, D L; Fink, W J; Miller, J M

    1981-05-01

    This study examined the effect of three exercise-diet regimens on muscle glycogen supercompensation and subsequent performance during a 20.9-km run. A diet containing 15% carbohydrate (CHO,L), 50% CHO (M), or 70% (CHO (H) was arranged in three trials as follows: trial A = 3 days L, 3 days H; trial B = 3 days M, 3 days H; trial C = 6 days M. For each trial a 5-day depletion-taper exercise sequence was conducted on the treadmill at 73% VO2 max. The runs were 90, 40, 40, 20, and 20 min, respectively. A day of rest preceded the 20.9-km performance run. Muscle biopsies were obtained from the gastrocnemius on days 4 and 7 (both prior to and after the performance run). Trials A, B, and C elevated muscle glycogen to 207, 203, and 159 mmol glucosyl units/kg wet tissue (mmG), respectively. The performance run in both trials A and B utilized significantly more glycogen than in trial C: 5.0 and 5.1 mmG/km vs. 3.1 mmG/km. There were, however, no differences in either performance run times or post-performance run glycogen levels between the trials. These data demonstrate that (1) muscle glycogen can be elevated to high levels with a moderate exercise-diet regimen; (2) initial muscle glycogen levels influence the amount subsequently utilized during exercise; (3) carbohydrate loading is of no benefit to performance for trained runners during a 20.9-km run.

  7. Postexercise Glycogen Recovery and Exercise Performance is Not Significantly Different Between Fast Food and Sport Supplements.

    PubMed

    Cramer, Michael J; Dumke, Charles L; Hailes, Walter S; Cuddy, John S; Ruby, Brent C

    2015-10-01

    A variety of dietary choices are marketed to enhance glycogen recovery after physical activity. Past research informs recommendations regarding the timing, dose, and nutrient compositions to facilitate glycogen recovery. This study examined the effects of isoenergetic sport supplements (SS) vs. fast food (FF) on glycogen recovery and exercise performance. Eleven males completed two experimental trials in a randomized, counterbalanced order. Each trial included a 90-min glycogen depletion ride followed by a 4-hr recovery period. Absolute amounts of macronutrients (1.54 ± 0.27 g·kg-1 carbohydrate, 0.24 ± 0.04 g·kg fat-1, and 0.18 ±0.03g·kg protein-1) as either SS or FF were provided at 0 and 2 hr. Muscle biopsies were collected from the vastus lateralis at 0 and 4 hr post exercise. Blood samples were analyzed at 0, 30, 60, 120, 150, 180, and 240 min post exercise for insulin and glucose, with blood lipids analyzed at 0 and 240 min. A 20k time-trial (TT) was completed following the final muscle biopsy. There were no differences in the blood glucose and insulin responses. Similarly, rates of glycogen recovery were not different across the diets (6.9 ± 1.7 and 7.9 ± 2.4 mmol·kg wet weight- 1·hr-1 for SS and FF, respectively). There was also no difference across the diets for TT performance (34.1 ± 1.8 and 34.3 ± 1.7 min for SS and FF, respectively. These data indicate that short-term food options to initiate glycogen resynthesis can include dietary options not typically marketed as sports nutrition products such as fast food menu items.

  8. Isolation of a glycogen synthase I kinase that is independent of adenosine 3':5'-monophosphate.

    PubMed Central

    Schlender, K K; Reimann, E M

    1975-01-01

    Three protein kinases (ATP:protein phosphotransferase, EC 2.7.1.37) were detected when the soluble fraction of rabbit kidney medulla was chromatographed on DEAE-cellulose with a linear NaC1 gradient. The first two kinases eluted (Peak 1 and Peak II) were cyclic-AMP-dependent, wheras Peak III was cyclic-AMP-independent. A procedure was developed to separate the catalytic subunit of Peak II cyclic-AMP-dependent protein kinase (representing the bulk of the histone kinase activity) from Peak III protein kinase. In contrast to the catalytic subunit, Peak III protein kinase phosphorylated casein more rapidly than histone. Peak III was insensitive to the heat-stable protein inhibitor of cyclic-AMP-dependent protein kinases and appeared to have a higher requirement for ATP than did the catalytic subunit. Peak III catalyzed the conversion of glycogen synthase (UDPglucose:glycogen alpha-4-glucosyltransferase, EC 2.4.1.11) from the I (glucose-6-phosphate-independent) to the D (glucose-6-phosphate-dependent) form. This conversion was dependent on Mg-2+ and ATP and was unaffected by cyclic AMP, cyclic GMP, or the protein inhibitor. Glycogen synthase I in the soluble fraction of kidney medulla could be converted to the D form by endogenous glycogen synthase I kinase if Mg-2+ and ATP were added. Most of this glycogen synthase I kinase activity was unaffected by cyclic AMP or by the protein inhibitor, suggesting that Peak III may be of major importance in the regulation of glycogen synthase in vivo. PMID:166380

  9. Antibody-mediated enzyme replacement therapy targeting both lysosomal and cytoplasmic glycogen in Pompe disease.

    PubMed

    Yi, Haiqing; Sun, Tao; Armstrong, Dustin; Borneman, Scott; Yang, Chunyu; Austin, Stephanie; Kishnani, Priya S; Sun, Baodong

    2017-02-02

    Pompe disease is characterized by accumulation of both lysosomal and cytoplasmic glycogen primarily in skeletal and cardiac muscles. Mannose-6-phosphate receptor-mediated enzyme replacement therapy (ERT) with recombinant human acid α-glucosidase (rhGAA) targets the enzyme to lysosomes and thus is unable to digest cytoplasmic glycogen. Studies have shown that anti-DNA antibody 3E10 penetrates living cells and delivers "cargo" proteins to the cytosol or nucleus via equilibrative nucleoside transporter ENT2. We speculate that 3E10-mediated ERT with GAA will target both lysosomal and cytoplasmic glycogen in Pompe disease. A fusion protein (FabGAA) containing a humanized Fab fragment derived from the murine 3E10 antibody and the 110 kDa human GAA precursor was constructed and produced in CHO cells. Immunostaining with an anti-Fab antibody revealed that the Fab signals did not co-localize with the lysosomal marker LAMP2 in cultured L6 myoblasts or Pompe patient fibroblasts after incubation with FabGAA. Western blot with an anti-GAA antibody showed presence of the 150 kDa full-length FabGAA in the cell lysates, in addition to the 95- and 76 kDa processed forms of GAA that were also seen in the rhGAA-treated cells. Blocking of mannose-6-phosphate receptor with mannose-6-phosphate markedly reduced the 95- and the 76 kDa forms but not the 150 kDa form. In GAA-KO mice, FabGAA achieved similar treatment efficacy as rhGAA at an equal molar dose in reducing tissue glycogen contents. Our data suggest that FabGAA retains the ability of rhGAA to treat lysosomal glycogen accumulation and has the beneficial potential over rhGAA to reduce cytoplasmic glycogen storage in Pompe disease.

  10. Glycogen metabolism protects against metabolic insult to preserve carotid body function during glucose deprivation.

    PubMed

    Holmes, Andrew P; Turner, Philip J; Carter, Paul; Leadbeater, Wendy; Ray, Clare J; Hauton, David; Buckler, Keith J; Kumar, Prem

    2014-10-15

    The view that the carotid body (CB) type I cells are direct physiological sensors of hypoglycaemia is challenged by the finding that the basal sensory neuronal outflow from the whole organ is unchanged in response to low glucose. The reason for this difference in viewpoint and how the whole CB maintains its metabolic integrity when exposed to low glucose is unknown. Here we show that, in the intact superfused rat CB, basal sensory neuronal activity was sustained during glucose deprivation for 29.1 ± 1.2 min, before irreversible failure following a brief period of excitation. Graded increases in the basal discharge induced by reducing the superfusate PO2 led to proportional decreases in the time to the pre-failure excitation during glucose deprivation which was dependent on a complete run-down in glycolysis and a fall in cellular energy status. A similar ability to withstand prolonged glucose deprivation was observed in isolated type I cells. Electron micrographs and immunofluorescence staining of rat CB sections revealed the presence of glycogen granules and the glycogen conversion enzymes glycogen synthase I and glycogen phosphorylase BB, dispersed throughout the type I cell cytoplasm. Furthermore, pharmacological attenuation of glycogenolysis and functional depletion of glycogen both significantly reduced the time to glycolytic run-down by ∼33 and 65%, respectively. These findings suggest that type I cell glycogen metabolism allows for the continuation of glycolysis and the maintenance of CB sensory neuronal output in periods of restricted glucose delivery and this may act as a key protective mechanism for the organ during hypoglycaemia. The ability, or otherwise, to preserve energetic status may thus account for variation in the reported capacity of the CB to sense physiological glucose concentrations and may even underlie its function during pathological states associated with augmented CB discharge.

  11. Histological Changes on Liver Glycogen Storage in Mice (Mus musculus) Caused by Unbalanced Diets

    PubMed Central

    Ulusoy, Esma; Eren, Banu

    2008-01-01

    Weight-losing diets have appealed to people who want to lose weight in the short-term. They usually apply high-protein (HP) diets (like Atkin’s, Stillman’s, Scarsdale) which they practice for 2 weeks or so. Unfortunately, these people who have rapid weight loss return to their old habits and quickly regain the weight lost. We have shown in previous work that actually these weight losses have been associated with body fluids, protein and glycogen storage. In our study, we examined the effect of unbalanced diet—related to an HP diet- on liver glycogen storage. For this study 40 Swiss albino mice consisting of two groups were used. The first group (HPSD) was fed with 25% HP for fifteen days and then were fed standard meals for the remaining 15 days; the other group was fed with standard meals throughout. The two groups were fed their respective diets for 30 days. At the end of 15th, 20th, 25th and 30th days 5 from each group were killed with cervical dislocation. The livers were removed perfused and then fixated. There were major differences in weight between the first and the fifteenth days. We detected remarkable increase in the weight gain of mice in the remaining 15 days. Glycogen storage was significantly reduced in HPSD (15) stained with PAS. In the others 20th, 25th and 30th days abnormally dense glycogen deposits were observed. Vacuoles in the hepatocyte cytoplasm, brownish deposits within hepatocytes, wide sinusoids, macrovesiculler steatosis structures and hydropic degeneration were observed in PAS and H&E stained HPSD group. As a result for the HPSD group a significant decrement in glycogen storage at the 15th day and also an accumulation of excessive amounts of glycogen deposits in mice liver was observed in the normal feeding phase. PMID:21876654

  12. Natural dendrimers: synthesis and in vitro characterization of glycogen-cysteamine conjugates.

    PubMed

    Perrone, Mara; Lopedota, Angela; Liberati, Elisa; Russo, Vincenzo; Cutrignelli, Annalisa; Laquintana, Valentino; de Sousa, Irene Pereira; Franco, Massimo; Tongiani, Serena; Denora, Nunzio; Bernkop-Schnürch, Andreas

    2017-03-05

    The aim of this study was to synthesize, characterize and evaluate the mucoadhesive properties of the first thiolated hyperbranched natural polysaccharide with biodegradability and biocompatibility features. In detail, glycogen-cysteamine conjugates were synthesized through a first step of oxidative ring opening applying increasing concentrations of sodium periodate, to obtain polymers with different degrees of oxidation, and a second step of reductive amination with a constant amount of cysteamine. The obtained glycogen-cysteamine conjugates were characterized regarding their content of free and total thiol groups by Ellman's assay, biocompatibility, swelling/erosion behavior, rheological synergism and mucoadhesive properties in comparison to the unmodified glycogen. The higher the concentration of periodate was, the higher was the content of total thiol groups being in the range of 255.7 ± 12 - 1194.5 ± 82 μmol/g, biocompatibility remained unaffected by these structural changes. On the contrary, the mucoadhesive properties, evaluated by tensile, rheological synergism and rotating cylinder studies, appear to be influenced by the thiol groups concentration on the glycogen. In particular the glycogen-cysteamine conjugate exhibiting the highest degree of thiolation showed a 79-fold increase in viscosity over a time period of 8 h, as well as, remained attached on freshly excised porcine mucosa 32-fold longer than the unmodified polymer. The higher was the amount of conjugated thiol groups, the higher was the water absorption capacity of glycogen-cysteamine tablets in Simulated Intestinal Fluid pH 6.8 (SIF). The introduction of thiol moieties on polymer changed the characteristics of the polysaccharide by improving mucoadhesion properties. Therefore, this work represents the first study describing thiolated natural dendrimers as potential platform useful to realize appropriate mucoadhesive nanocarrier systems suitable to prolong mucosal residence time.

  13. Alglucosidase alfa enzyme replacement therapy as a therapeutic approach for glycogen storage disease type III.

    PubMed

    Sun, Baodong; Fredrickson, Keri; Austin, Stephanie; Tolun, Adviye A; Thurberg, Beth L; Kraus, William E; Bali, Deeksha; Chen, Yuan-Tsong; Kishnani, Priya S

    2013-02-01

    We investigated the feasibility of using recombinant human acid-α glucosidase (rhGAA, Alglucosidase alfa), an FDA approved therapy for Pompe disease, as a treatment approach for glycogen storage disease type III (GSD III). An in vitro disease model was established by isolating primary myoblasts from skeletal muscle biopsies of patients with GSD IIIa. We demonstrated that rhGAA significantly reduced glycogen levels in the two GSD IIIa patients' muscle cells (by 17% and 48%, respectively) suggesting that rhGAA could be a novel therapy for GSD III. This conclusion needs to be confirmed in other in vivo models.

  14. Progression of renal damage in glycogen storage disease type I is associated to hyperlipidemia: a multicenter prospective Italian study.

    PubMed

    Melis, Daniela; Cozzolino, Mariarosaria; Minopoli, Giorgia; Balivo, Francesca; Parini, Rossella; Rigoldi, Miriam; Paci, Sabrina; Dionisi-Vici, Carlo; Burlina, Alberto; Andria, Generoso; Parenti, Giancarlo

    2015-04-01

    Angiotensin converting enzyme (ACE)-inhibitors decrease glomerular hyperfiltration but not microalbuminuria and proteinuria in glycogen storage disease type I. In the current study, we demonstrated that severe hyperlipidemia is associated with ACE-inhibitor ineffectiveness. We underline the importance of adequate metabolic control in glycogen storage disease type I. A combination therapy with ACE-inhibitors and lipid lowering drugs might be considered.

  15. Molecular Pathophysiology of Hepatic Glucose Production

    PubMed Central

    Sharabi, Kfir; Tavares, Clint D. J.; Rines, Amy K.; Puigserver, Pere

    2015-01-01

    Maintaining blood glucose concentration within a relatively narrow range through periods of fasting or excess nutrient availability is essential to the survival of the organism. This is achieved through an intricate balance between glucose uptake and endogenous glucose production to maintain constant glucose concentrations. The liver plays a major role in maintaining normal whole body glucose levels by regulating the processes of de novo glucose production (gluconeogenesis) and glycogen breakdown (glycogenolysis), thus controlling the levels of hepatic glucose release. Aberrant regulation of hepatic glucose production (HGP) can result in deleterious clinical outcomes, and excessive HGP is a major contributor to the hyperglycemia observed in Type 2 diabetes mellitus (T2DM). Indeed, adjusting glycaemia as close as possible to a non-diabetic range is the foremost objective in the medical treatment of patients with T2DM and is currently achieved in the clinic primarily through suppression of HGP. Here, we review the molecular mechanisms controlling HGP in response to nutritional and hormonal signals and discuss how these signals are altered in T2DM. PMID:26549348

  16. Molecular pathophysiology of hepatic glucose production.

    PubMed

    Sharabi, Kfir; Tavares, Clint D J; Rines, Amy K; Puigserver, Pere

    2015-12-01

    Maintaining blood glucose concentration within a relatively narrow range through periods of fasting or excess nutrient availability is essential to the survival of the organism. This is achieved through an intricate balance between glucose uptake and endogenous glucose production to maintain constant glucose concentrations. The liver plays a major role in maintaining normal whole body glucose levels by regulating the processes of de novo glucose production (gluconeogenesis) and glycogen breakdown (glycogenolysis), thus controlling the levels of hepatic glucose release. Aberrant regulation of hepatic glucose production (HGP) can result in deleterious clinical outcomes, and excessive HGP is a major contributor to the hyperglycemia observed in Type 2 diabetes mellitus (T2DM). Indeed, adjusting glycemia as close as possible to a non-diabetic range is the foremost objective in the medical treatment of patients with T2DM and is currently achieved in the clinic primarily through suppression of HGP. Here, we review the molecular mechanisms controlling HGP in response to nutritional and hormonal signals and discuss how these signals are altered in T2DM.

  17. Increased mitochondrial ROS formation by acetaminophen in human hepatic cells is associated with gene expression changes suggesting disruption of the mitochondrial electron transport chain.

    PubMed

    Jiang, Jian; Briedé, Jacob J; Jennen, Danyel G J; Van Summeren, Anke; Saritas-Brauers, Karen; Schaart, Gert; Kleinjans, Jos C S; de Kok, Theo M C M

    2015-04-16

    Acetaminophen (APAP) overdosage results in hepatotoxicity, but the underlying molecular mechanisms are still not completely understood. In the current study, we focused on mitochondrial-specific oxidative liver injury induced by APAP exposure. Owning to genetic polymorphisms in the CYP2E1 gene or varying inducibility by xenobiotics, the CYP2E1 mRNA level and protein activity vary extensively among individuals. As CYP2E1 is a known ROS generating enzyme, we chose HepG2 to minimize CYP2E1-induced ROS formation, which will help us better understand the APAP induced mitochondrial-specific hepatotoxicity in a subpopulation with low CYP2E1 activity. HepG2 cells were exposed to a low and toxic dose (0.5 and 10mM) of APAP and analyzed at four time points for genome-wide gene expression. Mitochondria were isolated and electron spin resonance spectroscopy was performed to measure the formation of mitochondrial ROS. The yield of ATP was measured to confirm the impact of the toxic dose of APAP on cellular energy production. Our results indicate that 10mM APAP significantly influences the expression of mitochondrial protein-encoding genes in association with an increase in mitochondrial ROS formation. Additionally, 10mM APAP affects the expression of genes encoding the subunits of electron transport chain (ETC) complexes, which may alter normal mitochondrial functions by disrupting the assembly, stability, and structural integrity of ETC complexes, leading to a measurable depletion of ATP, and cell death. The expression of mitochondrium-specific antioxidant enzyme, SOD2, is reduced which may limit the ROS scavenging ability and cause imbalance of the mitochondrial ROS homeostasis. Overall, transcriptome analysis reveals the molecular processes involved in the observed APAP-induced increase of mitochondrial ROS formation and the associated APAP-induced oxidative stress.

  18. Glycogen storage diseases: a brief review and update on clinical features, genetic abnormalities, pathologic features, and treatment.

    PubMed

    Hicks, John; Wartchow, Eric; Mierau, Gary

    2011-10-01

    Glycogen storage diseases (GSD) affect primarily the liver, skeletal muscle, heart, and sometimes the central nervous system and the kidneys. These unique diseases are quite varied in age of onset of symptoms, morbidity, and mortality. Glycogen storage diseases are classified according to their individual enzyme deficiency. Each of these enzymes regulates synthesis or degradation of glycogen. Interestingly, there is great phenotypic variation and variable clinical courses even when a specific enzyme is altered by mutation. Depending on the specific mutation in an enzyme, a GSD patient may have a favorable or unfavorable prognosis. With neonatal or infantile forms, some GSDs lead to death within the first year of life, whereas other glycogen storage diseases are relatively asymptomatic or may cause only exercise intolerance. The paper provides a brief review and update of glycogen storage diseases, with respect to clinical features, genetic abnormalities, pathologic features, and treatment.

  19. Cryo-chemical decellularization of the whole liver for mesenchymal stem cells-based functional hepatic tissue engineering.

    PubMed

    Jiang, Wei-Cheng; Cheng, Yu-Hao; Yen, Meng-Hua; Chang, Yin; Yang, Vincent W; Lee, Oscar K

    2014-04-01

    Liver transplantation is the ultimate treatment for severe hepatic failure to date. However, the limited supply of donor organs has severely hampered this treatment. So far, great potentials of using mesenchymal stem cells (MSCs) to replenish the hepatic cell population have been shown; nevertheless, there still is a lack of an optimal three-dimensional scaffold for generation of well-transplantable hepatic tissues. In this study, we utilized a cryo-chemical decellularization method which combines physical and chemical approach to generate acellular liver scaffolds (ALS) from the whole liver. The produced ALS provides a biomimetic three-dimensional environment to support hepatic differentiation of MSCs, evidenced by expression of hepatic-associated genes and marker protein, glycogen storage, albumin secretion, and urea production. It is also found that hepatic differentiation of MSCs within the ALS is much more efficient than two-dimensional culture in vitro. Importantly, the hepatic-like tissues (HLT) generated by repopulating ALS with MSCs are able to act as functional grafts and rescue lethal hepatic failure after transplantation in vivo. In summary, the cryo-chemical method used in this study is suitable for decellularization of liver and create acellular scaffolds that can support hepatic differentiation of MSCs and be used to fabricate functional tissue-engineered liver constructs.

  20. Direct hepatic differentiation of mouse embryonic stem cells induced by valproic acid and cytokines

    PubMed Central

    Dong, Xue-Jun; Zhang, Guo-Rong; Zhou, Qing-Jun; Pan, Ruo-Lang; Chen, Ye; Xiang, Li-Xin; Shao, Jian-Zhong

    2009-01-01

    AIM: To develop a protocol for direct hepatic lineage differentiation from early developmental progenitors to a population of mature hepatocytes. METHODS: Hepatic progenitor cells and then mature hepatocytes from mouse embryonic stem (ES) cells were obtained in a sequential manner, induced by valproic acid (VPA) and cytokines (hepatocyte growth factor, epidermal growth factor and insulin). Morphological changes of the differentiated cells were examined by phase-contrast microscopy and electron microscopy. Reverse transcription polymerase chain reaction and immunocytochemical analyses were used to evaluate the gene expression profiles of the VPA-induced hepatic progenitors and the hepatic progenitor-derived hepatocytes. Glycogen storage, cytochrome P450 activity, transplantation assay, differentiation of bile duct-like structures and tumorigenic analyses were performed for the functional identification of the differentiated cells. Furthermore, FACS and electron microscopy were used for the analyses of cell cycle profile and apoptosis in VPA-induced hepatic differentiated cells. RESULTS: Based on the combination of VPA and cytokines, mouse ES cells differentiated into a uniform and homogeneous cell population of hepatic progenitor cells and then matured into functional hepatocytes. The progenitor population shared several characteristics with ES cells and hepatic stem/progenitor cells, and represented a novel progenitor cell between ES and hepatic oval cells in embryonic development. The differentiated hepatocytes from progenitor cells shared typical characteristics with mature hepatocytes, including the patterns of gene expression, immunological markers, in vitro hepatocyte functions and in vivo capacity to restore acute-damaged liver function. In addition, the differentiation of hepatic progenitor cells from ES cells was accompanied by significant cell cycle arrest and selective survival of differentiating cells towards hepatic lineages. CONCLUSION: Hepatic cells

  1. Skeletal muscle glycogen synthase subcellular localization: effects of insulin and PPAR-alpha agonist (K-111) administration in rhesus monkeys.

    PubMed

    Ortmeyer, Heidi K; Adall, Yohannes; Marciani, Karina R; Katsiaras, Andreas; Ryan, Alice S; Bodkin, Noni L; Hansen, Barbara C

    2005-06-01

    Insulin covalently and allosterically regulates glycogen synthase (GS) and may also cause the translocation of GS from glycogen-poor to glycogen-rich locations. We examined the possible role of subcellular localization of GS and glycogen in insulin activation of GS in skeletal muscle of six obese monkeys and determined whether 1) insulin stimulation during a hyperinsulinemic euglycemic clamp and/or peroxisome proliferator-activated receptor (PPAR)-alpha agonist treatment (K-111, 3 mg.kg(-1).day(-1); Kowa) induced translocation of GS and 2) translocation of GS was associated with insulin activation of GS. GS and glycogen were present in all fractions obtained by differential centrifugation, except for the cytosolic fraction, under both basal and insulin-stimulated conditions. We found no evidence for translocation of GS by insulin. GS total (GST) activity was strongly associated with glycogen content (r = 0.70, P < 0.001). Six weeks of treatment with K-111 increased GST activity in all fractions, except the cytosolic fraction, and mean GST activity, GS independent activity, and glycogen content were significantly higher in the insulin-stimulated samples compared with basal samples, effects not seen with vehicle. The increase in GST activity was strongly related to the increase in glycogen content during the hyperinsulinemic euglycemic clamp after K-111 administration (r = 0.74, P < 0.001). Neither GS protein expression nor GS gene expression was affected by insulin or by K-111 treatment. We conclude that 1) in vivo insulin does not cause translocation of GS from a glycogen-poor to a glycogen-rich location in primate skeletal muscle and 2) the mechanism of action of K-111 to improve insulin sensitivity includes an increase in GST activity without an increase in GS gene or protein expression.

  2. Impaired glucose tolerance and predisposition to the fasted state in liver glycogen synthase knock-out mice.

    PubMed

    Irimia, Jose M; Meyer, Catalina M; Peper, Caron L; Zhai, Lanmin; Bock, Cheryl B; Previs, Stephen F; McGuinness, Owen P; DePaoli-Roach, Anna; Roach, Peter J

    2010-04-23

    Conversion to glycogen is a major fate of ingested glucose in the body. A rate-limiting enzyme in the synthesis of glycogen is glycogen synthase encoded by two genes, GYS1, expressed in muscle and other tissues, and GYS2, primarily expressed in liver (liver glycogen synthase). Defects in GYS2 cause the inherited monogenic disease glycogen storage disease 0. We have generated mice with a liver-specific disruption of the Gys2 gene (liver glycogen synthase knock-out (LGSKO) mice), using Lox-P/Cre technology. Conditional mice carrying floxed Gys2 were crossed with mice expressing Cre recombinase under the albumin promoter. The resulting LGSKO mice are viable, develop liver glycogen synthase deficiency, and have a 95% reduction in fed liver glycogen content. They have mild hypoglycemia but dispose glucose less well in a glucose tolerance test. Fed, LGSKO mice also have a reduced capacity for exhaustive exercise compared with mice carrying floxed alleles, but the difference disappears after an overnight fast. Upon fasting, LGSKO mice reach within 4 h decreased blood glucose levels attained by control floxed mice only after 24 h of food deprivation. The LGSKO mice maintain this low blood glucose for at least 24 h. Basal gluconeogenesis is increased in LGSKO mice, and insulin suppression of endogenous glucose production is impaired as assessed by euglycemic-hyperinsulinemic clamp. This observation correlates with an increase in the liver gluconeogenic enzyme phosphoenolpyruvate carboxykinase expression and activity. This mouse model mimics the pathophysiology of glycogen storage disease 0 patients and highlights the importance of liver glycogen stores in whole body glucose homeostasis.

  3. Comparative hepatic in vitro depletion and metabolite formation of major perfluorooctane sulfonate precursors in Arctic polar bear, beluga whale, and ringed seal.

    PubMed

    Letcher, Robert J; Chu, Shaogang; McKinney, Melissa A; Tomy, Gregg T; Sonne, Christian; Dietz, Rune

    2014-10-01

    Perfluorooctane sulfonate (PFOS) has been reported to be among the most concentrated persistent organic pollutants in Arctic marine wildlife. The present study examined the in vitro depletion of major PFOS precursors, N-ethyl-perfluorooctane sulfonamide (N-EtFOSA) and perfluorooctane sulfonamide (FOSA), as well as metabolite formation using an assay based on enzymatically viable liver microsomes for three top Arctic marine mammalian predators, polar bear (Ursus maritimus), beluga whale (Delphinapterus leucas), and ringed seal (Pusa hispida), and in laboratory rat (Rattus rattus) serving as a general mammalian model and positive control. Rat assays showed that N-EtFOSA (38 nM or 150 ng mL(-1)) to FOSA metabolism was >90% complete after 10 min, and at a rate of 23 pmol min(-1) mg(-1) protein. Examining all species in a full 90 min incubation assay, there was >95% N-EtFOSA depletion for the rat active control and polar bear microsomes, ∼65% for ringed seals, and negligible depletion of N-EtFOSA for beluga whale. Concomitantly, the corresponding in vitro formation of FOSA from N-EtFOSA was also quantitatively rat≈polar bear>ringed seal>beluga whale. A lack of enzymatic ability and/or a rate too slow to be detected likely explains the lack of N-EtFOSA to FOSA transformation for beluga whale. In the same assays, the depletion of the FOSA metabolite was insignificant (p>0.01) and with no concomitant formation of PFOS metabolite. This suggests that, in part, a source of FOSA is the biotransformation of accumulated N-EtFOSA in free-ranging Arctic ringed seal and polar bear.

  4. Decreased Glycogen Content Might Contribute to Chronic Stress-Induced Atrophy of Hippocampal Astrocyte volume and Depression-like Behavior in Rats

    PubMed Central

    Zhao, Yunan; Zhang, Qiang; Shao, Xiao; Ouyang, Liufeng; Wang, Xin; Zhu, Kexuan; Chen, Lin

    2017-01-01

    The involvement of brain glycogen in the progress of chronic stress-induced impairment of hippocampal astrocyte structural plasticity and depression-like behavior is yet to be clarified. The present study designed three experiments to determine the role of brain glycogen in the plasticity and behavioral consequences of chronic stress. Time course studies on brain glycogen, astrocytes, and behavioral responses to stress were conducted in Experiment 1. Chronic stress decreased the hippocampal glycogen levels, reduced astrocytic size and protrusion length in the hippocampus, and induced depression-like behavior. Glycogen synthase 1 mRNA in the hippocampus was silenced by lentiviral vector-based RNA interference (RNAi) in Experiment 2. This RNAi produced a lack of glycogen in the hippocampus, decreased the hippocampal astrocyte size, and induced depressive behavior in rats. The mechanisms of chronic stress-induced brain glycogen decrease were investigated in Experiment 3. Chronic stress promoted hippocampal glycogen breakdown and increased hippocampal glycogen synthesis. Results suggest that decreased glycogen content was associated with chronic stress-induced atrophy of hippocampal astrocyte size and depression-like behavior. Furthermore, the decrease of glycogen content in the hippocampus might be due to the compensation of glycogen synthesis for breakdown in an insufficient manner. PMID:28233800

  5. Benzo(a)pyrene (B(a)P) metabolism and in vitro formation of B(a)P-DNA adducts by hepatic microsomes from rats fed diets containing corn and menhaden oils

    SciTech Connect

    Dharwadkar, S.; Bellow, J.; Ramanathan, R.; Wade, A.

    1986-03-01

    Dietary unsaturated fat is required for maximum induction of hepatic mixed function oxidases responsible for activating carcinogens which may bind covalently to DNA. The aim of this study was to assess the influence of dietary fat type on in vitro B(a)P metabolism and B(a)P-DNA adduct formation. Male rats were starved 2 days and refed diet devoid of fat, or containing 20% corn oil (CO) or 20% menhaden oil (MO) for 4 days. Both dietary fats increased Vmax for B(a)P hydroxylation without affecting Km. Phenobarbital (PB) administration increased Vmax in all animals but Km was increased only in rats fed the fat diets. PB resulted in decreased B(a)P metabolism when conducted at 15 =M only in rats fed the two fat diets even in the presence of increased cytochrome P-450 (P-450). This effect was due to a decrease in B(a)P metabolism at low substrate concentrations in PB treated fat-fed animals. Binding of B(a)P to calf-thymus DNA was increased in animals fed both fats which was enhanced further by PB only in rats fed the CO and MO diets. When the data are calculated as B(a)P metabolized per unit of P-450, PB seems to induce a P-450 in fat-fed animals having lower affinity and capacity for B(a)P metabolism and activation.

  6. Hepatitis Information for the Public

    MedlinePlus

    ... of Viral Hepatitis Contact Us Quick Links to Hepatitis … A | B | C | D | E Viral Hepatitis Home ... Local Partners & Grantees Policy and Programs Resource Center Hepatitis Information for the Public Recommend on Facebook Tweet ...

  7. Lessons from new mouse models of glycogen storage disease type 1a in relation to the time course and organ specificity of the disease.

    PubMed

    Rajas, Fabienne; Clar, Julie; Gautier-Stein, Amandine; Mithieux, Gilles

    2015-05-01

    Patients with glycogen storage diseases type 1 (GSD1) suffer from life-threatening hypoglycaemia, when left untreated. Despite an intensive dietary treatment, patients develop severe complications, such as liver tumors and renal failure, with aging. Until now, the animal models available for studying the GSD1 did not survive after weaning. To gain further insights into the molecular mechanisms of the disease and to evaluate potential treatment strategies, we have recently developed novel mouse models in which the catalytic subunit of glucose-6 phosphatase (G6pc) is deleted in each glucose-producing organ specifically. For that, B6.G6pc(ex3lox/ex3lox) mice were crossed with transgenic mice expressing a recombinase under the control of the serum albumin, the kidney androgen protein or the villin promoter, in order to obtain liver, kidney or intestine G6pc(-/-) mice, respectively. As opposed to total G6pc knockout mice, tissue-specific G6pc deficiency allows mice to maintain their blood glucose by inducing glucose production in the other gluconeogenic organs. Even though it is considered that glucose is produced mainly by the liver, liver G6pc(-/-) mice are perfectly viable and exhibit the same hepatic pathological features as GSD1 patients, including the late development of hepatocellular adenomas and carcinomas. Interestingly, renal G6pc(-/-) mice developed renal symptoms similar to the early human GSD1 nephropathy. This includes glycogen overload that leads to nephromegaly and morphological and functional alterations in the kidneys. Thus, our data suggest that renal G6Pase deficiency per se is sufficient to induce the renal pathology of GSD1. Therefore, these new mouse models should allow us to improve the strategies of treatment on both nutritional and pharmacological points of view.

  8. Detecting glycogen in peripheral blood mononuclear cells with periodic acid schiff staining.

    PubMed

    Tabatabaei Shafiei, Mahdieh; Carvajal Gonczi, Catalina M; Rahman, Mohammed Samiur; East, Ashley; François, Jonathan; Darlington, Peter J

    2014-12-23

    Periodic acid Schiff (PAS) staining is an immunohistochemical technique used on muscle biopsies and as a diagnostic tool for blood samples. Polysaccharides such as glycogen, glycoproteins, and glycolipids stain bright magenta making it easy to enumerate positive and negative cells within the tissue. In muscle cells PAS staining is used to determine the glycogen content in different types of muscle cells, while in blood cell samples PAS staining has been explored as a diagnostic tool for a variety of conditions. Blood contains a proportion of white blood cells that belong to the immune system. The notion that cells of the immune system possess glycogen and use it as an energy source has not been widely explored. Here, we describe an adapted version of the PAS staining protocol that can be applied on peripheral blood mononuclear immune cells from human venous blood. Small cells with PAS-positive granules and larger cells with diffuse PAS staining were observed. Treatment of samples with amylase abrogates these patterns confirming the specificity of the stain. An alternate technique based on enzymatic digestion confirmed the presence and amount of glycogen in the samples. This protocol is useful for hematologists or immunologists studying polysaccharide content in blood-derived lymphocytes.

  9. The effect of fixatives and temperature on the quality of glycogen demonstration.

    PubMed

    Zakout, Yosef Mohamed Azzam; Salih, Magdi M; Ahmed, H G

    2010-04-01

    Glycogen is demonstrated in a number of lesions and is diagnostically significant, particularly in certain tumors. To stain glycogen accurately, it is essential to choose a suitable fixative, temperature and staining method. We used rabbit liver to assess these variables. Specimens were fixed in three fixatives at two temperatures: 10% formalin, neutral buffered formalin (NBF) and Bouin's solution at 37 and 4 degrees C. Seventy-two paraffin sections were prepared and stained with periodic acid-Schiff (PAS), hexamine (methenamine) silver and Best's carmine methods. Negative control sections using diastase digestion were used for all methods to confirm the presence of glycogen. For the PAS reaction, Bouin's fixative gave better results at both temperatures compared to the other fixatives. For hexamine (methenamine) silver, the quality of staining was improved for tissues fixed in both 10% formalin and NBF at 37 degrees C compared to Bouin's solution. Both 10% formalin and NBF at 4 degrees C gave better results than Bouin's solution. For Best's carmine, Bouin's solution gave the best results for tissues fixed at 4 degrees C. Fixation of tissues with NBF at 37 degrees C gave the best quality staining. We concluded that the quality of glycogen staining in paraffin sections is greatly affected by both the fixative and the temperature of fixation.

  10. Stimulatory effect of apigenin-6-C-beta-L-fucopyranoside on insulin secretion and glycogen synthesis.

    PubMed

    Cazarolli, Luisa Helena; Folador, Poliane; Moresco, Henrique Hunger; Brighente, Inês Maria Costa; Pizzolatti, Moacir Geraldo; Silva, Fátima Regina M Barreto

    2009-11-01

    In vivo and in vitro treatments were carried out to investigate the effects of apigenin-6-C-beta-L-fucopyranoside (1), isolated from Averrhoa carambola L. (Oxalidaceae), on serum glucose and insulin levels in hyperglycemic rats as well as its effect on glycogen synthesis in normal rat soleus muscle. Apigenin-6-C-beta-L-fucopyranoside showed an acute effect on blood glucose lowering in hyperglycemic rats and stimulated glucose-induced insulin secretion. A stimulatory effect of 1 on glycogen synthesis was observed when muscles were incubated with this flavonoid and also its effect was completely nullified by pre-treatment with insulin signal transduction inhibitors. Taking this into account, the MAPK-PP1 and PI3K-GSK3 pathways are involved in the apigenin-6-C-beta-L-fucopyranoside-induced increase in glycogen synthesis in muscle. This study provides evidence for dual effects of apigenin-6-C-beta-L-fucopyranoside as an antihyperglycemic (insulin secretion) as well as an insulinomimetic (glycogen synthesis) agent.

  11. Early alterations in soleus GLUT-4, glucose transport, and glycogen in voluntary running rats

    NASA Technical Reports Server (NTRS)

    Henriksen, Erik J.; Halseth, Amy E.

    1994-01-01

    Voluntary wheel running (WR) by juvenile female rats was used as a noninterventional model of soleus muscle functional overload to study the regulation of insulin-stimulated glucose transport activity by the glucose transporter (GLUT-4 isoform) protein level and glycogen concentration. Soleus total protein content was significantly greater (+18%;P greater than 0.05) than in age-matched controls after 1 wk of WR, and this hypertrophic response continued in weeks 2-4 (+24-32%). GLUT-4 protein was 39% greater than in controls in 1-wk WR soleus, and this adaptation was accompanied by a similar increase in in vitro insulin-stimulated glucose transport activity(+29%). After 2 and 4 wk of WR, however, insulin-stimulated glucose transport activity had returned to control levels, despite a continued elevation (+25-28%) of GLUT-4 protein. At these two time points, glycogen concentration was significantly enhanced in WR soleus (+21-42%), which coincided with significant reductions in glycogen synthase activity ratios (-23 to-41%). These results indicate that, in this model of soleus muscle functional overload, the GLUT-4 protein level may initially regulate insulin-stimulated glucose transport activity in the absence of changes in other modifying factors. However,this regulation of glucose transport activity by GLUT-4 protein may be subsequently overridden by elevated glycogen concentration.

  12. Optimization of molecular design in the evolution of metabolism: the glycogen molecule.

    PubMed Central

    Meléndez-Hevia, E; Waddell, T G; Shelton, E D

    1993-01-01

    The animal glycogen molecule has to be designed in accordance with its metabolic function as a very effective fuel store allowing quick release of large amounts of glucose. In addition, the design should account for a high capacity of glucose storage in the least possible space. We have studied the optimization of these variables by means of a mathematical model of the glycogen molecule. Our results demonstrate that the structure is optimized to maximize (a) the total glucose stored in the smallest possible volume, (b) the proportion of it that can be directly released by phosphorylase before any debranching occurs, and (c) the number of non-reducing ends (points of attack for phosphorylase), which maximizes the speed of fuel release. The optimization of these four variables is achieved with appropriate values for two key parameters in glycogen design: the degree of branching and the length of the chains. The optimal values of these two parameters are precisely those found in cellular glycogen. PMID:8240246

  13. Initiation of glycogen biosynthesis in rat heart. Studies with a purified preparation

    SciTech Connect

    Blumenfeld, M.L.; Krisman, C.R.

    1985-09-25

    Two fractions of glycogen synthase were isolated from rat cardiac muscle on the basis of a different affinity for DEAE-cellulose and omega-aminobutyl-agarose. One of these fractions was able to transfer glucosyl residues from UDP-glucose not only to glycogen (GS-1 activity) but also to an endogenous acceptor. The latter reaction (GS-2 activity) occurred in the absence of added glycogen, and its reaction product was insoluble in trichloroacetic acid. This compound was degraded by amylolytic enzymes, thus showing that the product synthesized on the endogenous acceptor was an alpha 1,4-glucan. After incubation with alpha-amylase-free proteolytic enzyme, the compound was rendered trichloroacetic acid-soluble. Polyacrylamide gel electrophoresis, under both native and denaturing conditions, showed that GS-2 reaction products moved electrophoretically associated to protein. The results give further evidence for the association between an alpha 1,4-glucan and protein, which the authors postulate is related to the initiation of glycogen biosynthesis.

  14. Comparison of methods for glycogen analysis of in vitro fermentation pellets produced with strained ruminal inoculum

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Microbial glycogen measurement is used to account for fates of carbohydrate substrates. It is commonly applied to washed cells or pure cultures which can be accurately subsampled, and it uses smaller sample sizes. However, the nonhomogenous fermentation pellets produced with strained rumen inoculum ...

  15. The Drosophila NR4A Nuclear Receptor DHR38 Regulates Carbohydrate Metabolism and Glycogen Storage

    PubMed Central

    Ruaud, Anne-Françoise; Lam, Geanette; Thummel, Carl S.

    2011-01-01

    Animals balance nutrient storage and mobilization to maintain metabolic homeostasis, a process that is disrupted in metabolic diseases like obesity and diabetes. Here, we show that DHR38, the single fly ortholog of the mammalian nuclear receptor 4A family of nuclear receptors, regulates glycogen storage during the larval stages of Drosophila melanogaster. DHR38 is expressed and active in the gut and body wall of larvae, and its expression levels change in response to nutritional status. DHR38 null mutants have normal levels of glucose, trehalose (the major circulating form of sugar), and triacylglycerol but display reduced levels of glycogen in the body wall muscles, which constitute the primary storage site for carbohydrates. Microarray analysis reveals that many metabolic genes are mis-regulated in DHR38 mutants. These include phosphoglucomutase, which is required for glycogen synthesis, and the two genes that encode the digestive enzyme amylase, accounting for the reduced amylase enzyme activity seen in DHR38 mutant larvae. These studies demonstrate that a critical role of nuclear receptor 4A receptors in carbohydrate metabolism has been conserved through evolution and that nutritional regulation of DHR38 expression maintains the proper uptake and storage of glycogen during the growing larval stage of development. PMID:21084378

  16. Hepatitis B and concomitant hepatic steatosis

    PubMed Central

    Lim, Chong Teik

    2017-01-01

    Hepatic steatosis is becoming more common in Asia with prevalence becoming as common as Western countries. Concomitant Hepatitis B and hepatic steatosis is increasingly encountered in clinical practice. The interaction between the two concomitant conditions at both molecular level and clinical outcome remains to be explored. The present review is aimed at summarizing the existing literature on the complex interaction of the two-concomitant disease. PMID:28251117

  17. An efficient nonviral gene-delivery vector based on hyperbranched cationic glycogen derivatives

    PubMed Central

    Liang, Xuan; Ren, Xianyue; Liu, Zhenzhen; Liu, Yingliang; Wang, Jue; Wang, Jingnan; Zhang, Li-Ming; Deng, David YB; Quan, Daping; Yang, Liqun

    2014-01-01

    Background The purpose of this study was to synthesize and evaluate hyperbranched cationic glycogen derivatives as an efficient nonviral gene-delivery vector. Methods A series of hyperbranched cationic glycogen derivatives conjugated with 3-(dimethylamino)-1-propylamine (DMAPA-Glyp) and 1-(2-aminoethyl) piperazine (AEPZ-Glyp) residues were synthesized and characterized by Fourier-transform infrared and hydrogen-1 nuclear magnetic resonance spectroscopy. Their buffer capacity was assessed by acid–base titration in aqueous NaCl solution. Plasmid deoxyribonucleic acid (pDNA) condensation ability and protection against DNase I degradation of the glycogen derivatives were assessed using agarose gel electrophoresis. The zeta potentials and particle sizes of the glycogen derivative/pDNA complexes were measured, and the images of the complexes were observed using atomic force microscopy. Blood compatibility and cytotoxicity were evaluated by hemolysis assay and MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) assay, respectively. pDNA transfection efficiency mediated by the cationic glycogen derivatives was evaluated by flow cytometry and fluorescence microscopy in the 293T (human embryonic kidney) and the CNE2 (human nasopharyngeal carcinoma) cell lines. In vivo delivery of pDNA in model animals (Sprague Dawley rats) was evaluated to identify the safety and transfection efficiency. Results The hyperbranched cationic glycogen derivatives conjugated with DMAPA and AEPZ residues were synthesized. They exhibited better blood compatibility and lower cytotoxicity when compared to branched polyethyleneimine (bPEI). They were able to bind and condense pDNA to form the complexes of 100–250 nm in size. The transfection efficiency of the DMAPA-Glyp/pDNA complexes was higher than those of the AEPZ-Glyp/pDNA complexes in both the 293T and CNE2 cells, and almost equal to those of bPEI. Furthermore, pDNA could be more safely delivered to the blood vessels in brain

  18. Systemic Correction of Murine Glycogen Storage Disease Type IV by an AAV-Mediated Gene Therapy.

    PubMed

    Yi, Haiqing; Zhang, Quan; Brooks, Elizabeth D; Yang, Chunyu; Thurberg, Beth L; Kishnani, Priya S; Sun, Baodong

    2016-11-10

    Deficiency of glycogen branching enzyme (GBE) causes glycogen storage disease type IV (GSD IV), which is characterized by the accumulation of a less branched, poorly soluble form of glycogen called polyglucosan (PG) in multiple tissues. This study evaluates the efficacy of gene therapy with an adeno-associated viral (AAV) vector in a mouse model of adult form of GSD IV (Gbe1(ys/ys)). An AAV serotype 9 (AAV9) vector containing a human GBE expression cassette (AAV-GBE) was intravenously injected into 14-day-old Gbe1(ys/ys) mice at a dose of 5 × 10(11) vector genomes per mouse. Mice were euthanized at 3 and 9 months of age. In the AAV-treated mice at 3 months of age, GBE enzyme activity was highly elevated in heart, which is consistent with the high copy number of the viral vector genome detected. GBE activity also increased significantly in skeletal muscles and the brain, but not in the liver. The glycogen content was reduced to wild-type levels in muscles and significantly reduced in the liver and brain. At 9 months of age, though GBE activity was only significantly elevated in the heart, glycogen levels were significantly reduced in the liver, brain, and skeletal muscles of the AAV-treated mice. In addition, the AAV treatment resulted in an overall decrease in plasma activities of alanine transaminase, aspartate transaminase, and creatine kinase, and a significant increase in fasting plasma glucose concentration at 9 months of age. This suggests an alleviation of damage and improvement of function in the liver and muscles by the AAV treatment. This study demonstrated a long-term benefit of a systemic injection of an AAV-GBE vector in Gbe1(ys/ys) mice.

  19. Therapeutic approaches in glycogen storage disease type II/Pompe Disease.

    PubMed

    Schoser, Benedikt; Hill, Victoria; Raben, Nina

    2008-10-01

    Glycogen storage disease type II (GSDII)/Pompe disease is an autosomal recessive multi-system disorder due to a deficiency of the glycogen-degrading lysosomal enzyme, acid alpha-glucosidase. Without adequate levels of alpha-glucosidase, there is a progressive accumulation of glycogen inside the lysosome, resulting in lysosomal expansion in many tissues, although the major clinical manifestations are seen in cardiac and skeletal muscle. Pompe disease presents as a continuum of clinical phenotypes. In the most severe cases, disease onset occurs in infancy and death results from cardiac and respiratory failure within the first 1 or 2 years of life. In the milder late-onset forms, cardiac muscle is spared and muscle weakness is the primary symptom. Weakness of respiratory muscles is the major cause of mortality in these cases. Enzyme replacement therapy (ERT) with alglucosidase alfa (Myozyme; Genzyme Corp., Framingham, MA) is now available for all forms of glycogen storage disease type II. ERT has shown remarkable success in reversing pathology in cardiac muscle and extending life expectancy in infantile patients. However, skeletal muscle has proven to be a more challenging target for ERT. Although ERT is less effective in skeletal muscle than was hoped for, the lessons learned from both clinical and pre-clinical ERT studies have greatly expanded our understanding of the pathogenesis of the disease. A combination of fundamental studies and clinical follow-up, as well as exploration of other therapies, is necessary to take treatment for glycogen storage disease type II to the next level.

  20. Effect of passive and active recovery on the resynthesis of muscle glycogen.

    PubMed

    Choi, D; Cole, K J; Goodpaster, B H; Fink, W J; Costill, D L

    1994-08-01

    The purpose of this investigation was to determine the effect of passive and active recovery on the resynthesis of muscle glycogen after high-intensity cycle ergometer exercise in untrained subjects. In a cross-over design, six college-aged males performed three, 1-min exercise bouts at approximately 130% VO2max with a 4-min rest period between each work bout. The exercise protocol for each trial was identical, while the recovery following exercise was either active (30 min at 40-50% VO2max, 30-min seated rest) or passive (60-min seated rest). Initial muscle glycogen values averaged 144.2 +/- 3.8 mmol.kg-1 w.w. for the active trial and 158.7 +/- 8.0 mmol.kg-1 w.w. for the passive trial. Corresponding immediate postexercise glycogen contents were 97.7 +/- 5.4 and 106.8 +/- 4.7 mmol.kg-1 w.w., respectively. These differences between treatments were not significant. However, mean muscle glycogen after 60 min of passive recovery increased 15.0 +/- 4.9 mmol.kg-1 w.w., whereas it decreased 6.3 +/- 3.7 mmol.kg-1 w.w. following the 60 min active recovery protocol (P < 0.05). Also, the decrease in blood lactate concentration during active recovery was greater than during passive recovery and significantly different at 10 and 30 min of the recovery period (P < 0.05). These data suggest that the use of passive recovery following intense exercise results in a greater amount of muscle glycogen resynthesis than active recovery over the same duration.

  1. An isozyme of acid alpha-glucosidase with reduced catalytic activity for glycogen.

    PubMed Central

    Beratis, N G; LaBadie, G U; Hirschhorn, K

    1980-01-01

    Both the common and a variant isozyme of acid alpha-glucosidase have been purified from a heterozygous placenta with CM-Sephadex, ammonium sulfate precipitation, dialysis, Amicon filtration, affinity chromatography by Sephadex G-100, and DEAE-cellulose chromatography. Three and two activity peaks, from the common and variant isozymes, respectively, were obtained by DEAE-cellulose chromatography using a linear NaCl gradient. The three peaks of activity of the common isozyme were eluted with 0.08, 0.12, and 0.17 M NaCl, whereas the two peaks of the variant, with 0.01 and 0.06 M NaCl. The pH optimum and thermal denaturation at 57 degrees C were the same in all enzyme peaks of both isozymes. Rabbit antiacid alpha-glucosidase antibodies produced against the common isozyme were found to cross-react with both peaks of the variant isozyme. The two isozymes shared antigenic identity and had similar Km's with maltose as substrate. Normal substrate saturation kinetics were observed with the common isozyme when glycogen was the substrate, but the variant produced an S-shaped saturation curve indicating a phase of negative and positive cooperativity at low and high glycogen concentrations, respectively. The activity of the variant was only 8.6% and 19.2% of the common isozyme when assayed with nonsaturating and saturating concentrations of glycogen, respectively. A similar rate of hydrolysis of isomaltose by both isozymes was found indicating that the reduced catalytic activity of the variant isozyme toward glycogen is not the result of a reduced ability of this enzyme to cleave the alpha-1,6 linkages of glycogen. Images Fig. 2 Fig. 4 Fig. 6 PMID:6770674

  2. Effect of alcohol intake on muscle glycogen storage after prolonged exercise.

    PubMed

    Burke, Louise M; Collier, Greg R; Broad, Elizabeth M; Davis, Peter G; Martin, David T; Sanigorski, Andrew J; Hargreaves, Mark

    2003-09-01

    We studied the effects of alcohol intake on postexercise muscle glycogen restoration with samples from vastus lateralis being collected immediately after glycogen-depleting cycling and after a set recovery period. Six well-trained cyclists undertook a study of 8-h recovery (2 meals), and another nine cyclists undertook a separate 24-h protocol (4 meals). In each study, subjects completed three trials in crossover order: control (C) diet [meals providing carbohydrate (CHO) of 1.75 g/kg]; alcohol-displacement (A) diet (1.5 g/kg alcohol displacing CHO energy from C) and alcohol + CHO (AC) diet (C + 1.5 g/kg alcohol). Alcohol intake reduced postmeal glycemia especially in A trial and 24-h study, although insulin responses were maintained. Alcohol intake increased serum triglycerides, particularly in the 24-h study and AC trial. Glycogen storage was decreased in A diets compared with C at 8 h (24.4 +/- 7 vs. 44.6 +/- 6 mmol/kg wet wt, means +/- SE, P < 0.05) and 24 h (68 +/- 5 vs. 82 +/- 5 mmol/kg wet wt, P < 0.05). There was a trend to reduced glycogen storage with AC in 8 h (36.2 +/- 8 mmol/kg wet wt, P = 0.1) but no difference in 24 h (85 +/- 9 mmol/kg wet wt). We conclude that 1). the direct effect of alcohol on postexercise glycogen synthesis is unclear, and 2). the main effect of alcohol intake is indirect, by displacing CHO intake from optimal recovery nutrition practices.

  3. Structural basis of glycogen branching enzyme deficiency and pharmacologic rescue by rational peptide design

    PubMed Central

    Froese, D. Sean; Michaeli, Amit; McCorvie, Thomas J.; Krojer, Tobias; Sasi, Meitav; Melaev, Esther; Goldblum, Amiram; Zatsepin, Maria; Lossos, Alexander; Álvarez, Rafael; Escribá, Pablo V.; Minassian, Berge A.; von Delft, Frank; Kakhlon, Or; Yue, Wyatt W.

    2015-01-01

    Glycogen branching enzyme 1 (GBE1) plays an essential role in glycogen biosynthesis by generating α-1,6-glucosidic branches from α-1,4-linked glucose chains, to increase solubility of the glycogen polymer. Mutations in the GBE1 gene lead to the heterogeneous early-onset glycogen storage disorder type IV (GSDIV) or the late-onset adult polyglucosan body disease (APBD). To better understand this essential enzyme, we crystallized human GBE1 in the apo form, and in complex with a tetra- or hepta-saccharide. The GBE1 structure reveals a conserved amylase core that houses the active centre for the branching reaction and harbours almost all GSDIV and APBD mutations. A non-catalytic binding cleft, proximal to the site of the common APBD mutation p.Y329S, was found to bind the tetra- and hepta-saccharides and may represent a higher-affinity site employed to anchor the complex glycogen substrate for the branching reaction. Expression of recombinant GBE1-p.Y329S resulted in drastically reduced protein yield and solubility compared with wild type, suggesting this disease allele causes protein misfolding and may be amenable to small molecule stabilization. To explore this, we generated a structural model of GBE1-p.Y329S and designed peptides ab initio to stabilize the mutation. As proof-of-principle, we evaluated treatment of one tetra-peptide, Leu-Thr-Lys-Glu, in APBD patient cells. We demonstrate intracellular transport of this peptide, its binding and stabilization of GBE1-p.Y329S, and 2-fold increased mutant enzymatic activity compared with untreated patient cells. Together, our data provide the rationale and starting point for the screening of small molecule chaperones, which could become novel therapies for this disease. PMID:26199317

  4. Skeletal muscle glycogen concentration and metabolic responses following a high glycaemic carbohydrate breakfast.

    PubMed

    Chryssanthopoulos, Costas; Williams, Clyde; Nowitz, Andrea; Bogdanis, Gregory

    2004-01-01

    The purpose of this study was to examine the influence of a carbohydrate-rich meal on post-prandial metabolic responses and skeletal muscle glycogen concentration. After an overnight fast, eight male recreational/club endurance runners ingested a carbohydrate (CHO) meal (2.5 g CHO x kg(-1) body mass) and biopsies were obtained from the vastus lateralis muscle before and 3 h after the meal. Ingestion of the meal resulted in a 10.6 +/- 2.5% (P < 0.05) increase in muscle glycogen concentration (pre-meal vs post-meal: 314.0 +/- 33.9 vs 347.3 +/- 31.3 mmol x kg(-1) dry weight). Three hours after ingestion, mean serum insulin concentrations had not returned to pre-feeding values (0 min vs 180 min: 45 +/- 4 vs 143 +/- 21 pmol x l(-1)). On a separate occasion, six similar individuals ingested the meal or fasted for a further 3 h during which time expired air samples were collected to estimate the amount of carbohydrate oxidized over the 3 h post-prandial period. It was estimated that about 20% of the carbohydrate consumed was converted into muscle glycogen, and about 12 % was oxidized. We conclude that a meal providing 2.5 g CHO x kg(-1) body mass can increase muscle glycogen stores 3 h after ingestion. However, an estimated 67% of the carbohydrate ingested was unaccounted for and this may have been stored as liver glycogen and/or still be in the gastrointestinal tract.

  5. Effects of commercially available pneumatic compression on muscle glycogen recovery after exercise.

    PubMed

    Keck, Nathan A; Cuddy, John S; Hailes, Walter S; Dumke, Charles L; Ruby, Brent C

    2015-02-01

    The purpose of this study was to investigate the effects of pneumatic compression pants on postexercise glycogen resynthesis. Active male subjects (n = 10) completed 2 trials consisting of a 90-minute glycogen depleting ride, followed by 4 hours of recovery with either a pneumatic compression device (PCD) or passive recovery (PR) in a random counterbalanced order. A carbohydrate beverage (1.8 g·kg bodyweight) was provided at 0 and 2 hours after exercise. Muscle biopsies (vastus lateralis) were obtained immediately and 4 hours after exercise for glycogen analyses. Blood samples were collected throughout recovery to measure glucose and insulin. Eight fingerstick blood samples for lactate were collected in the last 20 minutes of the exercise period and during the initial portion of the recovery period. Heart rate was monitored throughout the trial. During the PCD trial, subjects recovered using a commercially available recovery device (NormaTec PCD) operational at 0-60 and 120-180 minutes into recovery period. The same PCD was worn during the PR trial but was not turned on to create pulsatile pressures. There was no difference in muscle glycogen resynthesis during the recovery period (6.9 ± 0.8 and 6.9 ± 0.5 mmol·kg wet wt·h for the PR and PCD trials, respectively). Blood glucose, insulin, and lactate concentrations changed with respect to time but were not different between trials (p > 0.05). The use of PCD did not alter the rate of muscle glycogen resynthesis, blood lactate, or blood glucose and insulin concentrations associated with a postexercise oral glucose load.

  6. Glycogenformation by Rhodococcus species and the effect of inhibition of lipid biosynthesis on glycogen accumulation in Rhodococcus opacus PD630.

    PubMed

    Hernández, Martín A; Alvarez, Héctor M

    2010-11-01

    Members of the genus Rhodococcus were investigated for their ability to produce glycogen during cultivation on gluconate or glucose. Strains belonging to Rhodococcus ruber, Rhodococcus opacus, Rhodococcus fascians, Rhodococcus erythropolis and Rhodococcus equi were able to produce glycogen up to 0.2–5.6% of cellular dry weight (CDW). The glycogen content varied from 0.8% to 3.2% of CDW in cells of R. opacus PD630, which is a well-known oleaginous bacterium, during the exponential growth phase, when cultivated on diverse carbon sources. Maltose and pyruvate promoted glycogen accumulation by cells of strain PD630 to a greater extent than glucose, gluconate, lactose, sucrose or acetate. This strain was able to produce triacylglycerols, polyhydroxyalkanoates and glycogen as storage compounds during growth on gluconate, although triacylglycerols were always the main product under the conditions of this study. Cerulenin, an inhibitor of de novo fatty acid synthesis, inhibited the accumulation of triacylglycerols from gluconate and increased the content of polyhydroxyalkanoates (from 2.0% to 4.2%, CDW) and glycogen (from 0.1% to 3.0%, CDW). An increase of the polyhydroxyalkanoates and glycogen content was also observed in two mutants of R. opacus PD630, which produced reduced amounts of triacylglycerols during cultivation of cells on gluconate.

  7. Hepatitis B Foundation Newsletter: B Informed

    MedlinePlus

    ... Our Accomplishments Annual Reports Our Videos What Is Hepatitis B? What Is Hepatitis B? The ABCs of Viral Hepatitis Liver Cancer and Hepatitis B Hepatitis Delta Coinfection Hepatitis C Coinfection HIV/AIDS ...

  8. Hemostasis and Hepatic Surgery.

    PubMed

    Eeson, Gareth; Karanicolas, Paul J

    2016-04-01

    Operative blood loss is a major source of morbidity and even mortality for patients undergoing hepatic resection. This review discusses strategies to minimize blood loss and the utilization of allogeneic blood transfusion pertaining to oncologic hepatic surgery.

  9. Delta agent (Hepatitis D)

    MedlinePlus

    ... this page: //medlineplus.gov/ency/article/000216.htm Delta agent (Hepatitis D) To use the sharing features on this page, please enable JavaScript. Delta agent is a type of virus called hepatitis ...

  10. Know More Hepatitis

    MedlinePlus

    ... Boomers Hepatitis Risk Assessment Campaign Materials Fact Sheets Posters Infographics Videos Buttons & Badges Email Signatures Radio Ads and Scripts Know More Hepatitis Logos Presentation Templates Guidelines for using materials and logos About ...

  11. Hepatitis A - children

    MedlinePlus

    ... hepatitis A. Children can get hepatitis A at day care center from other children or from child care ... treatment with immunoglobulin therapy. If your child attends day care: Make sure the children and staff at the ...

  12. Hepatic (Liver) Function Panel

    MedlinePlus

    ... related side effects. The hepatic function panel evaluates: Alanine aminotransferase (ALT). This enzyme, found in the liver, ... MORE ON THIS TOPIC Mononucleosis Hepatitis Blood Test: Alanine Aminotransferase (ALT, or SGPT) Blood Test: Aspartate Aminotransferase ( ...

  13. Hepatitis Foundation International

    MedlinePlus

    ... million people globally. admin / 03/17/2015 Viral Hepatitis An estimated 4.4 million Americans from all ... Events section below. EVENTS FULL CALENDAR Loading… VIRAL HEPATITIS DISPARITIES HARD TO REACH, HARD TO TREAT™ AFRICAN ...

  14. Hepatitis virus panel

    MedlinePlus

    ... page: //medlineplus.gov/ency/article/003558.htm Hepatitis virus panel To use the sharing features on this page, please enable JavaScript. The hepatitis virus panel is a series of blood tests used ...

  15. Hepatitis B -- children

    MedlinePlus

    ... at birth: Newborn babies should receive their first hepatitis B vaccine and one dose of immunoglobulins (IG) within 12 hours. The baby should complete all hepatitis B vaccines as recommended during the first six months. Some ...

  16. Hepatitis B (HBV)

    MedlinePlus

    ... special immune injection and the first dose of hepatitis B vaccine at birth. How Is It Prevented? Because people ... B virus. Doctors recommend that teens get a hepatitis B immunization (vaccine). It's a series of three shots over a ...

  17. Hepatitis C (image)

    MedlinePlus

    Hepatitis C is a virus-caused liver inflammation which may cause jaundice, fever and cirrhosis. Persons who are most at risk for contracting and spreading hepatitis C are those who share needles for injecting drugs ...

  18. Restoration of muscle functionality by genetic suppression of glycogen synthesis in a murine model of Pompe disease.

    PubMed

    Douillard-Guilloux, Gaelle; Raben, Nina; Takikita, Shoichi; Ferry, Arnaud; Vignaud, Alban; Guillet-Deniau, Isabelle; Favier, Maryline; Thurberg, Beth L; Roach, Peter J; Caillaud, Catherine; Richard, Emmanuel

    2010-02-15

    Glycogen storage disease type II (GSDII) or Pompe disease is an autosomal recessive disorder caused by acid alpha-glucosidase (GAA) deficiency, leading to lysosomal glycogen accumulation. Affected individuals store glycogen mainly in cardiac and skeletal muscle tissues resulting in fatal hypertrophic cardiomyopathy and respiratory failure in the most severe infantile form. Enzyme replacement therapy has already proved some efficacy, but results remain variable especially in skeletal muscle. Substrate reduction therapy was successfully used to improve the phenotype in several lysosomal storage disorders. We have recently demonstrated that shRNA-mediated reduction of glycogen synthesis led to a significant reduction of glycogen accumulation in skeletal muscle of GSDII mice. In this paper, we analyzed the effect of a complete genetic elimination of glycogen synthesis in the same GSDII model. GAA and glycogen synthase 1 (GYS1) KO mice were inter-crossed to generate a new double-KO model. GAA/GYS1-KO mice exhibited a profound reduction of the amount of glycogen in the heart and skeletal muscles, a significant decrease in lysosomal swelling and autophagic build-up as well as a complete correction of cardiomegaly. In addition, the abnormalities in glucose metabolism and insulin tolerance observed in the GSDII model were corrected in double-KO mice. Muscle atrophy observed in 11-month-old GSDII mice was less pronounced in GAA/GYS1-KO mice, resulting in improved exercise capacity. These data demonstrate that long-term elimination of muscle glycogen synthesis leads to a significant improvement of structural, metabolic and functional defects in GSDII mice and offers a new perspective for the treatment of Pompe disease.

  19. Glycogen content regulates peroxisome proliferator activated receptor-∂ (PPAR-∂) activity in rat skeletal muscle.

    PubMed

    Philp, Andrew; MacKenzie, Matthew G; Belew, Micah Y; Towler, Mhairi C; Corstorphine, Alan; Papalamprou, Angela; Hardie, D Grahame; Baar, Keith

    2013-01-01

    Performing exercise in a glycogen depleted state increases skeletal muscle lipid utilization and the transcription of genes regulating mitochondrial β-oxidation. Potential candidates for glycogen-mediated metabolic adaptation are the peroxisome proliferator activated receptor (PPAR) coactivator-1α (PGC-1α) and the transcription factor/nuclear receptor PPAR-∂. It was therefore the aim of the present study to examine whether acute exercise with or without glycogen manipulation affects PGC-1α and PPAR-∂ function in rodent skeletal muscle. Twenty female Wistar rats were randomly assigned to 5 experimental groups (n = 4): control [CON]; normal glycogen control [NG-C]; normal glycogen exercise [NG-E]; low glycogen control [LG-C]; and low glycogen exercise [LG-E]). Gastrocnemius (GTN) muscles were collected immediately following exercise and analyzed for glycogen content, PPAR-∂ activity via chromatin immunoprecipitation (ChIP) assays, AMPK α1/α2 kinase activity, and the localization of AMPK and PGC-1α. Exercise reduced muscle glycogen by 47 and 75% relative to CON in the NG-E and LG-E groups, respectively. Exercise that started with low glycogen (LG-E) finished with higher AMPK-α2 activity (147%, p<0.05), nuclear AMPK-α2 and PGC-1α, but no difference in AMPK-α1 activity compared to CON. In addition, PPAR-∂ binding to the CPT1 promoter was significantly increased only in the LG-E group. Finally, cell reporter studies in contracting C2C12 myotubes indicated that PPAR-∂ activity following contraction is sensitive to glucose availability, providing mechanistic insight into the association between PPAR-∂ and glycogen content/substrate availability. The present study is the first to examine PPAR-∂ activity in skeletal muscle in response to an acute bout of endurance exercise. Our data would suggest that a factor associated with muscle contraction and/or glycogen depletion activates PPAR-∂ and initiates AMPK translocation in skeletal muscle in

  20. Hepatitis E Pathogenesis

    PubMed Central

    Lhomme, Sébastien; Marion, Olivier; Abravanel, Florence; Chapuy-Regaud, Sabine; Kamar, Nassim; Izopet, Jacques

    2016-01-01

    Although most hepatitis E virus (HEV) infections are asymptomatic, some can be severe, causing fulminant hepatitis and extra-hepatic manifestations, including neurological and kidney injuries. Chronic HEV infections may also occur in immunocompromised patients. This review describes how our understanding of the pathogenesis of HEV infection has progressed in recent years. PMID:27527210

  1. What Is Hepatitis?

    MedlinePlus

    ... عربي 中文 English Français Русский Español What is hepatitis? Online Q&A Reviewed July 2016 Q: What ... Question and answer archives Submit a question World Hepatitis Day Know hepatitis - Act now Event notice Key ...

  2. Hepatitis C.

    PubMed

    Burra, Patrizia

    2009-02-01

    Hepatitis C virus (HCV) is a leading cause of end-stage liver disease worldwide and the most common indication for liver transplantation in the United States and Europe. HCV nearly always recurs in liver-transplanted patients, and 10 to 25% of them develop cirrhosis within 5 to 10 years. One of the strategies suggested to limit virological HCV recurrence is pretransplant antiviral treatment, but studies are warranted on the pharmacokinetics of antiviral drugs in cirrhotic patients, the benefits of fixed or escalating antiviral drug dosage schedules, the duration of the treatment, and the indications for using growth factors. Several risk factors are associated with a more aggressive recurrent HCV and early allograft failure, such as an older donor age. The relationship between immunosuppression and fibrosis progression in HCV recurrence remains uncertain. Concerning the antiviral treatment, treating established recurrent disease with a combination of interferon and ribavirin has been the mainstay of management to date, but when it is best to start and how to manage the side effects are still controversial issues. Antiviral treatment should be started once the disease has been confirmed by a biopsy when the fibrosis develops, providing that ongoing acute or chronic rejection, biliary obstruction, vascular damage, autoimmune diseases and sepsis, and any other standard contraindications for antiviral therapy, have been excluded. HCV recurrence after liver transplantation may well lead to graft failure and become an indication for retransplantation, but this is done in a relatively small number of cases, accounting for only 3 to 5% of retransplanted patients, since retransplantation is associated with much worse results than primary liver transplant procedures. We must be prepared for the fact that increasing numbers of HCV-positive recipients with allografts failing due to recurrent HCV will be asking to be retransplanted-and we do not know yet how to respond to this

  3. [Epidemiology of viral hepatitis].

    PubMed

    Kaić, Bernard; Vilibić-Cavlek, Tatjana; Filipović, Sanja Kurecić; Nemeth-Blazić, Tatjana; Pem-Novosel, Iva; Vucina, Vesna Visekruna; Simunović, Aleksandar; Zajec, Martina; Radić, Ivan; Pavlić, Jasmina; Glamocanin, Marica; Gjenero-Margan, Ira

    2013-10-01

    Understanding the country-specific epidemiology of disease, which may vary greatly among countries, is crucial for identifying the most appropriate preventive and control measures. An overview of the local epidemiology of viral hepatitis in Croatia is given in this paper. The overall prevalence of hepatitis B in Croatia is low (less than 2% HBsAg carriers in the general population). Hepatitis B incidence and prevalence began to decline significantly following the introduction of universal hepatitis B vaccination in 1999. Information on HBsAg seroprevalence is derived from routine testing of certain subpopulations (pregnant women, blood donors) and seroprevalence studies mostly targeted at high-risk populations. Universal childhood vaccination against hepatitis B remains the main preventive measure. We recommend testing for immunity one to two months after the third dose of hepatitis B vaccine for health-care workers. The incidence and prevalence of hepatitis C have also been declining in the general population. The main preventive measures are ensuring safety of blood products, prevention of drug abuse, and harm reduction programs for intravenous drug users. Hepatitis A incidence has declined dramatically since fifty years ago, when thousands of cases were reported annually. In the last five years, an average of twenty cases have been reported per year. The reduction of hepatitis A is a consequence of improved personal and community hygiene and sanitation. Hepatitis D has not been reported in Croatia. The risk of hepatitis D will get to be even smaller as the proportion of population vaccinated against hepatitis B builds up. Hepatitis E is reported only sporadically in Croatia, mostly in persons occupationally in contact with pigs and in travelers to endemic countries. In conclusion, Croatia is a low prevalence country for hepatitides A, B and C. Hepatitis D has not been reported to occur in Croatia and there are only sporadic cases of hepatitis E. Since hepatitis

  4. Developmental changes in hepatic glucose metabolism in a newborn piglet model: A comparative analysis for suckling period and early weaning period.

    PubMed

    Xie, Chunyan; Wang, Qinhua; Wang, Jing; Tan, Bie; Fan, Zhiyong; Deng, Ze-yuan; Wu, Xin; Yin, Yulong

    2016-02-19

    The liver glucose metabolism, supplying sufficient energy for glucose-dependent tissues, is important in suckling or weaned animals, although there are few studies with piglet model. To better understand the development of glucose metabolism in the piglets during suckling period and early weaning period, we determined the hepatic glycogen content, and investigated the relative protein expression of key enzymes of glucogenesis (GNG) and mRNA levels of some glucose metabolism-related genes. During suckling period, the protein level of G6Pase in the liver of suckling piglets progressively declined with day of age compared with that of newborn piglets (at 1 day of age), whereas the PEPCK level stabilized until day 21 of age, indicating that hepatic GNG capacity gradually weakened in suckling piglets. The synthesis of hepatic glycogen, which was consistent with the fluctuation of glycolytic key genes PFKL and PKLR that gradually decreased after birth and was more or less steady during latter suckling period, although both the mRNA levels of GCK and key glucose transporter GLUT2 presented uptrend in suckling piglets. However, early weaning significantly suppressed the hepatic GNG in the weaned piglets, especially at d 3-5 of weaning period, then gradually recovered at d 7 of weaning period. Meanwhile, PFKL, PKLR and GLUT2 showed the similar trend during weaning period. On the contrast, the hepatic glycogen reached the maximum value when the G6Pase and PEPCK protein expression were at the lowest level, although the GCK level maintained increasing through 7 days of weaning period. Altogether, our study provides evidence that hepatic GNG and glycolysis in newborn piglets were more active than other days during suckling period, and early weaning could significantly suppressed glucose metabolism in liver, but this inhibition would progressively recover at day 7 after weaning.

  5. Inhibition of glycogen biosynthesis via mTORC1 suppression as an adjunct therapy for Pompe disease.

    PubMed

    Ashe, Karen M; Taylor, Kristin M; Chu, Qiuming; Meyers, Elizabeth; Ellis, Allen; Jingozyan, Varvara; Klinger, Katherine; Finn, Patrick F; Cooper, Christopher G F; Chuang, Wei-Lien; Marshall, John; McPherson, John M; Mattaliano, Robert J; Cheng, Seng H; Scheule, Ronald K; Moreland, Rodney J

    2010-08-01

    Pompe disease, also known as glycogen storage disease (GSD) type II, is caused by deficiency of lysosomal acid alpha-glucosidase (GAA). The resulting glycogen accumulation causes a spectrum of disease severity ranging from a rapidly progressive course that is typically fatal by 1-2years of age to a more slowly progressive course that causes significant morbidity and early mortality in children and adults. Recombinant human GAA (rhGAA) improves clinical outcomes with variable results. Adjunct therapy that increases the effectiveness of rhGAA may benefit some Pompe patients. Co-administration of the mTORC1 inhibitor rapamycin with rhGAA in a GAA knockout mouse reduced muscle glycogen content more than rhGAA or rapamycin alone. These results suggest mTORC1 inhibition may benefit GSDs that involve glycogen accumulation in muscle.

  6. Structural basis for the transglycosylase activity of a GH57-type glycogen branching enzyme from Pyrococcus horikoshii.

    PubMed

    Na, Soohui; Park, Minjeong; Jo, Inseong; Cha, Jaeho; Ha, Nam-Chul

    2017-03-18

    Glycogen branching enzyme (GBE) catalyzes the formation of α-1,6-branching points during glycogenesis by cleaving α-1,4 bonds and making new α-1,6 bonds. Most GBEs belong to the glycoside hydrolase 13 family (GH13), but new GBEs in the GH57 family have been isolated from Archaea. Here, we determined the crystal structure of a GH57 GBE from the hyperthermophilic archaeon Pyrococcus horikoshii (PhGBE) at a resolution of 2.3 Å. PhGBE exhibits both α-1,6-branching activity and endo-α-1,4 hydrolytic activity. PhGBE has a central (β/α)7-barrel domain that contains an embedded helix domain and an α-helix-rich C-terminal domain. The active-site cleft is located at the interface of the central and C-terminal domains. Amino acid substitution at Trp22, which is separate from the catalytic nucleophilic residue, abolished both enzymatic activities, indicating that Trp22 might be responsible for substrate recognition. We also observed that shortening of the flexible loop near the catalytic residue changed branched chain lengths of the reaction products with increased hydrolytic activity. Taken together, our findings propose a molecular mechanism for how GH57 GBEs exhibit the two activities and where the substrate binds the enzyme.

  7. Progesterone Receptor A Stability Is Mediated by Glycogen Synthase Kinase-3β in the Brca1-deficient Mammary Gland*

    PubMed Central

    Wang, Shaohui; Li, Ying; Hsu, Pang-Hung; Lee, Sou-Ying; Kim, Yoon; Lee, Eva Y.-H. P.

    2013-01-01

    Germ line mutations of the BRCA1 gene increase the risk of breast and ovarian cancer, but the basis of this tissue-specific tumor predisposition is not fully understood. Previously, we reported that the progesterone receptors are stabilized in Brca1-deficient mammary epithelial cells, and treating with anti-progesterone delays mammary tumorigenesis in Brca1/p53 conditional knock-out mice, suggesting that the progesterone has a critical role in breast carcinogenesis. To further explore how the stability of progesterone receptor is modulated, here, we have found that glycogen synthase kinase (GSK)-3β phosphorylation of progesterone receptor-A (PR-A) facilitates its ubiquitination. GSK-3β-mediated phosphorylation of serine 390 in PR-A regulates its subsequent ubiquitination and protein stability. Expression of PR-AS390A mutant in the human breast epithelial cells, MCF-10A, results in enhanced proliferation and formation of aberrant acini structure in the three-dimensional culture. Consistently, reduction of phosphorylation of serine 390 of PR-A and GSK-3β activity is observed in the Brca1-deficient mammary gland. Taken together, these results provide important aspects of tissue specificity of BRCA1-mediated suppression of breast carcinogenesis. PMID:23880761

  8. Progesterone receptor A stability is mediated by glycogen synthase kinase-3β in the Brca1-deficient mammary gland.

    PubMed

    Wang, Shaohui; Li, Ying; Hsu, Pang-Hung; Lee, Sou-Ying; Kim, Yoon; Lee, Eva Y-H P

    2013-09-06

    Germ line mutations of the BRCA1 gene increase the risk of breast and ovarian cancer, but the basis of this tissue-specific tumor predisposition is not fully understood. Previously, we reported that the progesterone receptors are stabilized in Brca1-deficient mammary epithelial cells, and treating with anti-progesterone delays mammary tumorigenesis in Brca1/p53 conditional knock-out mice, suggesting that the progesterone has a critical role in breast carcinogenesis. To further explore how the stability of progesterone receptor is modulated, here, we have found that glycogen synthase kinase (GSK)-3β phosphorylation of progesterone receptor-A (PR-A) facilitates its ubiquitination. GSK-3β-mediated phosphorylation of serine 390 in PR-A regulates its subsequent ubiquitination and protein stability. Expression of PR-A(S390A) mutant in the human breast epithelial cells, MCF-10A, results in enhanced proliferation and formation of aberrant acini structure in the three-dimensional culture. Consistently, reduction of phosphorylation of serine 390 of PR-A and GSK-3β activity is observed in the Brca1-deficient mammary gland. Taken together, these results provide important aspects of tissue specificity of BRCA1-mediated suppression of breast carcinogenesis.

  9. Association of cellular localization of glycogen synthase kinase 3beta in the digestive tract with cancer development.

    PubMed

    Hirakawa, Hiroshi; Nakayama, Toshiyuki; Shibata, Kenichiro; Sekine, Ichiro

    2009-09-01

    Glycogen synthase kinase 3beta (GSK-3beta) is a multifunctional serine/threonine kinase involved in several signaling pathways. Recently, we reported the polarized localization of GSK-3beta on the apical membrane of normal colon epithelium. To investigate the functions of this molecule, we studied stomach and colorectal cancer tissues. In normal simple columnar epithelium, GSK-3beta was localized with tight junction-associated protein ZO-1 in a single line at the apical cell border. GSK-3beta and ZO-1 were localized in the apical regions of tubular adenocarcinoma, similar to their localization in normal epithelium; however, their localization was different at the invasive front of the cancer and was found to be associated with lymphatic invasion. In signet-ring cell carcinoma of the stomach, the expression of these proteins was reduced and dot-like expression was observed in each cell of the signet-ring cell carcinoma. We speculated that GSK-3beta is involved in glandular structure formation and that the non-apical localization of membrane-localized GSK-3beta in tubular adenocarcinoma is associated with cancer development.

  10. [Salivary glands and oral mucous membrane status in patients with chronic hepatitis].

    PubMed

    Afanas'ev, V V; Muromtsev, A V; Derkach, N V

    2008-01-01

    The status of salivary glands and oral mucous membrane was investigated in 50 patients with chronic active hepatitis against the background of chronic alcoholism. The check up disclosed sialadenosis in 38% of patients and in 54% of patients - such diseases of oral mucous membrane as stomatitis, candidosis and geographic tonque. Besides there were disclosed such disturbances as big and small salivary glands secretion reduction, mixed saliva viscosity increase, increase of protein, P, K, Na and catalase content in it, glycogen hyperaccumulation in gingival tissues. The received data indicated the necessity of dispensary supervision of such patients and their treatment in stomatologist.

  11. Integrated imaging of hepatic tumors in childhood. Part II. Benign lesions (congenital, reparative, and inflammatory)

    SciTech Connect

    Miller, J.H.; Greenspan, B.S.

    1985-01-01

    The authors have encountered benign liver masses as frequently as malignant lesions in children with hepatomegaly. Lesions studied included abscesses, cavernous hemangioma/hemangioendothelioma, adenoma of glycogen storage disease, choledochal cysts, focal nodular hyperplasia, cystic hepatoblastoma, and hamartoma. An intergrated imaging protocol involving ultrasound, computed tomography, and scintigraphy proved to be more helpful than any one modality in establishing the benign or malignant nature of a hepatic neoplasm and the type of tumor, which is of particular importance when surgical exploration and/or biopsy is contraindicated.

  12. In search of proof-of-concept: gene therapy for glycogen storage disease type Ia.

    PubMed

    Koeberl, Dwight D

    2012-07-01

    The emergence of life threatening long-term complications in glycogen storage disease type Ia (GSD-Ia) has emphasized the need for new therapies, such as gene therapy, which could achieve biochemical correction of glucose-6-phosphatase deficiency and reverse clinical involvement. We have developed gene therapy with a novel adeno-associated virus (AAV) vector that: 1) prevented mortality and corrected glycogen storage in the liver, 2) corrected hypoglycemia during fasting, and 3) achieved efficacy with a low number of vector particles in G6Pase-deficient mice and dogs. However, the gradual loss of transgene expression from episomal AAV vector genomes eventually necessitated the administration of a different pseudotype of the AAV vector to sustain dogs with GSD-Ia. Further preclinical development of AAV vector-mediated gene therapy is therefore warranted in GSD-Ia.

  13. Acute effects of mercuric chloride on glycogen and protein content of zebra fish, Danio rerio.

    PubMed

    Vutukuru, S S; Basani, Kalpana

    2013-03-01

    Presence of mercury and other heavy metals above permissible levels in water bodies across the globe is posing a serious threat to aquatic biota and public health. Occurrence of mercury above the permissible limits in the aquatic ecosystem of Hyderabad city is well established. In this context, we carried out static- renewal bioassays on the zebra fish, Danio rerio exposed to different concentrations of mercuric chloride, and the 96-h median lethal concentration (LC50) was found to be 0.077 mgl(-1). Behavioral manifestations like loss of scales, hyper secretion of mucus, surfacing and darting movements, loss of balance, irregular swimming patterns were noticed in the fish exposed to 0.077 mgl(-1). The present study also examined the toxic effects of mercuric chloride on vital biochemical constituent's total glycogen and total protein. Significant decrease (p < 0.001) in glycogen and protein content of fish exposed to 0.077 mgl(-1).

  14. Hyperglycaemia induces metabolic dysfunction and glycogen accumulation in pancreatic β-cells

    PubMed Central

    Brereton, Melissa F.; Rohm, Maria; Shimomura, Kenju; Holland, Christian; Tornovsky-Babeay, Sharona; Dadon, Daniela; Iberl, Michaela; Chibalina, Margarita V.; Lee, Sheena; Glaser, Benjamin; Dor, Yuval; Rorsman, Patrik; Clark, Anne; Ashcroft, Frances M.

    2016-01-01

    Insulin secretion from pancreatic β-cells is impaired in all forms of diabetes. The resultant hyperglycaemia has deleterious effects on many tissues, including β-cells. Here we show that chronic hyperglycaemia impairs glucose metabolism and alters expression of metabolic genes in pancreatic islets. In a mouse model of human neonatal diabetes, hyperglycaemia results in marked glycogen accumulation, and increased apoptosis in β-cells. Sulphonylurea therapy rapidly normalizes blood glucose levels, dissipates glycogen stores, increases autophagy and restores β-cell metabolism. Insulin therapy has the same effect but with slower kinetics. Similar changes are observed in mice expressing an activating glucokinase mutation, in in vitro models of hyperglycaemia, and in islets from type-2 diabetic patients. Altered β-cell metabolism may underlie both the progressive impairment of insulin secretion and reduced β-cell mass in diabetes. PMID:27882918

  15. Electron autoradiographic study of intracellular conversion of fatty acids into glycogen in rats with alloxan diabetes

    SciTech Connect

    Lebkova, N.P.; Bobkov, Y.I.; Gorbonova, V.D.; Kolesova, O.E.

    1985-05-01

    An electron-autoradiographic study was undertaken of the intracellular distribution of hydrogen of fatty acids in alloxan diabetes. Alloxan diabetes was induced in rats; between 2 weeks and 2 months after development of the disease 0.1 ml of tritium-oleic or tritium-arachidonic acid was injected into the caudel vein of the rats. After decapitation, myocardial tissue from the subendocardial zone of the left ventricle, liver tissue, and glycogen isolated from the liver by a biochemical method, were taken for electron-autoradiographic investigation. Analysis of the data showed that a radioactive isotope, injected into the blood stream of the animals in the form of oleic or arachidonic acids, is incorporated into various structures of hepatocytes and cardiomyocytes. Direct proof is obtained to show that glycogen in hepatocytes and cardiomyoctyes of diabetic rats may be formed from fatty acids.

  16. THE RESISTANCE OF PUPS TO LATE CHLOROFORM POISONING IN ITS RELATION TO LIVER GLYCOGEN

    PubMed Central

    Graham, Evarts A.

    1915-01-01

    The relative difficulty with which the characteristic central lobular liver necrosis can be produced in young pups after chloroform administration is in some way referable to the high glycogen contents of their livers. Evidence for this conclusion lies in the following facts: 1. Pups can readily be made to show the central liver necrosis which is found in chloroform poisoning in adults, if, prior to the administration of chloroform, they have been starved or starved and made diabetic by phlorhizin. 2. A single quantitative experiment showed that the liver of a normal, well nourished pup, twenty-four hours old, contained as much as 9.07 per cent. of glycogen. 3. The feeding of carbohydrates to adult animals lessens their susceptibility to the production of liver necrosis by chloroform. PMID:19867861

  17. Differences in glycogen, lipids, and enzymes in livers from rats flown on Cosmos 2044

    NASA Technical Reports Server (NTRS)

    Merrill, Alfred H., Jr.; Wang, Elaine; Laroque, Regina; Mullins, Richard E.; Morgan, Edward T.; Hargrove, James L.; Bonkovsky, Herbert L.; Popova, Irina A.

    1992-01-01

    Livers from rats flown aboard Cosmos 2044 were analyzed for protein, carbohydrate (glycogen), and lipids as well as the activities of a number of key enzymes involved in metabolism of these compounds and xenobiotics. The major differences between the flight group and the synchronous control were elevations in microsomal protein, liver glycogen content, tyrosine aminotransferase, and tryptophan oxygenase and reductions in sphingolipids and the rate-limiting enzyme of heme biosynthesis delta-aminolevulinic acid synthase. These results provide further evidence that spaceflight has pronounced and diverse effects on liver function; however, some of the results with samples from Cosmos 2044 differed notably from those from previous spaceflights. This may be due to conditions of spaceflight and/or the postflight recovery period for Cosmos 2044.

  18. Conformational plasticity of glycogenin and its maltosaccharide substrate during glycogen biogenesis.

    PubMed

    Chaikuad, Apirat; Froese, D Sean; Berridge, Georgina; von Delft, Frank; Oppermann, Udo; Yue, Wyatt W

    2011-12-27

    Glycogenin initiates the synthesis of a maltosaccharide chain covalently attached to itself on Tyr195 via a stepwise glucosylation reaction, priming glycogen synthesis. We have captured crystallographic snapshots of human glycogenin during its reaction cycle, revealing a dynamic conformational switch between ground and active states mediated by the sugar donor UDP-glucose. This switch includes the ordering of a polypeptide stretch containing Tyr195, and major movement of an approximately 30-residue "lid" segment covering the active site. The rearranged lid guides the nascent maltosaccharide chain into the active site in either an intra- or intersubunit mode dependent upon chain length and steric factors and positions the donor and acceptor sugar groups for catalysis. The Thr83Met mutation, which causes glycogen storage disease XV, is conformationally locked in the ground state and catalytically inactive. Our data highlight the conformational plasticity of glycogenin and coexistence of two modes of glucosylation as integral to its catalytic mechanism.

  19. McArdle's disease (glycogen storage disease type V) and anesthesia--a case report and review of the literature.

    PubMed

    Bollig, Georg

    2013-09-01

    McArdles disease (glycogen storage disease type v) is a rare condition in which energy-metabolism in the muscle is hampered. A case report is presented and the possible risk for perioperative complications including malignant hyperthermia is discussed. A checklist for the anesthesiological management of patients with McArdles disease is provided. A short overview of anesthesiological challenges and perioperative complications of other glycogen storage diseases is given.

  20. Homogenization-dependent responses of acid-soluble and acid-insoluble glycogen to exercise and refeeding in human muscles.

    PubMed

    Barnes, Phillip D; Singh, Anish; Fournier, Paul A

    2009-12-01

    Muscle glycogen exists as acid-insoluble (AIG) and acid-soluble (ASG) forms, with AIG levels reported in most recent studies in humans to be the most responsive to exercise and refeeding. Because the muscle samples in these studies were not homogenized to extract glycogen, such homogenization-free protocols might have resulted in a suboptimal yield of ASG. Our goal, therefore, was to determine whether similar findings can be achieved using homogenized muscle samples by comparing the effect of exercise and refeeding on ASG and AIG levels. Eight male participants cycled for 60 minutes at 70% Vo(2peak) before ingesting 10.9 +/- 0.6 g carbohydrate per kilogram body mass over 24 hours. Muscle biopsies were taken before exercise and after 0, 2, and 24 hours of recovery. Using a homogenization-dependent protocol to extract glycogen, 77% to 91% of it was extracted as ASG, compared with 11% to 24% with a homogenization-free protocol. In response to exercise, muscle glycogen levels fell from 366 +/- 24 to 184 +/- 46 mmol/kg dry weight and returned to 232 +/- 32 and 503 +/- 59 mmol/kg dry weight after 2 and 24 hours, respectively. Acid-soluble glycogen but not AIG accounted for all the changes in total glycogen during exercise and refeeding when extracted using a homogenization-dependent protocol, but AIG was the most responsive fraction when extracted using a homogenization-free protocol. In conclusion, the patterns of response of ASG and AIG levels to changes in glycogen concentrations in human muscles are highly dependent on the protocol used to acid-extract glycogen, with the physiologic significance of the many previous studies on AIG and ASG being in need of revision.

  1. Sex-specific basal and hypoglycemic patterns of in vivo caudal dorsal vagal complex astrocyte glycogen metabolic enzyme protein expression.

    PubMed

    Tamrakar, Pratistha; Shrestha, Prem; Briski, Karen P

    2014-10-24

    Astrocytes contribute to neurometabolic stability through uptake, catabolism, and storage of glucose. These cells maintain the major brain glycogen reservoir, which is a critical fuel supply to neurons during glucose deficiency and increased brain activity. We used a combinatory approach incorporating immunocytochemistry, laser microdissection, and Western blotting to investigate the hypothesis of divergent expression of key enzymes regulating glycogen metabolism and glycolysis during in vivo normo- and/or hypoglycemia in male versus female hindbrain astrocytes. Glycogen synthase (GS) and glycogen phosphorylase (GP) levels were both enhanced in dorsal vagal complex astrocytes from vehicle-injected female versus male controls, with incremental increase in GS exceeding GP. Insulin-induced hypoglycemia (IIH) diminished GS and increased glycogen synthase kinase-3-beta (GSK3β) expression in both sexes, but decreased phosphoprotein phosphatase-1 (PP1) levels only in males. Astrocyte GP content was elevated by IIH in male, but not female rats. Data reveal sex-dependent sensitivity of these enzyme proteins to lactate as caudal hindbrain repletion of this energy substrate fully or incompletely reversed hypoglycemic inhibition of GS and prevented hypoglycemic augmentation of GSK3β and GP in females and males, respectively. Sex dimorphic patterns of glycogen branching and debranching enzyme protein expression were also observed. Levels of the rate-limiting glycolytic enzyme, phosphofructokinase, were unaffected by IIH with or without lactate repletion. Current data demonstrating sex-dependent basal and hypoglycemic patterns of hindbrain astrocyte glycogen metabolic enzyme expression imply that glycogen volume and turnover during glucose sufficiency and shortage may vary accordingly.

  2. Structural changes in the progression of atrial fibrillation: potential role of glycogen and fibrosis as perpetuating factors

    PubMed Central

    Zhang, Ling; Huang, Bing; Scherlag, Benjamin J; Ritchey, Jerry W; Embi, Abraham A; Hu, Jialu; Hou, Yuemei; Po, Sunny S

    2015-01-01

    Background: Previous studies of the goat heart subjected to prolonged atrial pacing induced sustained atrial fibrillation (AF). Structural changes included marked accumulation of glycogen in atrial myocytes. Aims: In the present study, we hypothesized that glycogen deposition in canine atrial myocytes promotes paroxysmal forms of AF and is involved in fibrosis development in the later stages of AF. Material & methods: In dogs under pentobarbital anesthesia, tissues were obtained from the right and left atrial appendages (LAA/RAA). Periodic acid Schiff (PAS) and Masson’s trichrome staining of the LAA/RAA from normal dogs, and those subjected to atrial pacing induced AF for 48 h or 8 weeks determined glycogen and collagen concentrations, respectively, using morphometric analysis. Results: At baseline, there was a significant greater concentration of glycogen in the LAA than the RAA (P ≤ 0.05). Compared to the RAA, the LAA glycogen, was dense and locked against the intercalated discs. After pacing induced AF for 48 hours and 8 weeks there was a marked increase in glycogen deposition, significantly greater than in the baseline state (P ≤ 0.05). There was a similar and progressive increase in collagen concentrations in each group (P ≤ 0.05). Conclusions: The differential in glycogen concentration, in conjunction with other factors, neural and electrophysiological, provide a basis for the greater propensity of the left atrium for paroxysmal AF, at baseline and 48 hours of pacing induced AF. The marked increase in collagen at 8 weeks of pacing provides a substrate for sustained AF. Evidence is presented linking glycogen accumulation and fibrosis as factors in the persistent forms of AF. PMID:25973058

  3. The cyclin-dependent kinase (CDK) inhibitor flavopiridol inhibits glycogen phosphorylase.

    PubMed

    Kaiser, A; Nishi, K; Gorin, F A; Walsh, D A; Bradbury, E M; Schnier, J B

    2001-02-15

    Flavopiridol has been shown to induce cell cycle arrest and apoptosis in various tumor cells in vitro and in vivo. Using immobilized flavopiridol, we identified glycogen phosphorylases (GP) from liver and brain as flavopiridol binding proteins from HeLa cell extract. Purified rabbit muscle GP also bound to the flavopiridol affinity column. GP is the rate-limiting enzyme in intracellular glycogen breakdown. Flavopiridol significantly inhibited the AMP-activated GP-b form of the purified rabbit muscle isoenzyme (IC50 of 1 microM at 0.8 mM AMP), but was less inhibitory to the active phosphorylated form of GP, GP-a (IC50 of 2.5 microM). The AMP-bound GP-a form was poorly inhibited by flavopiridol (40% at 10 microM). Increasing concentrations of the allosteric effector AMP resulted in a linear decrease in the GP-inhibitory activity of flavopiridol suggesting interference between flavopiridol and AMP. In contrast the GP inhibitor caffeine had no effect on the relative GP inhibition by flavopiridol, suggesting an additive effect of caffeine. Flavopiridol also inhibited the phosphorylase kinase-catalyzed phosphorylation of GP-b by inhibiting the kinase in vitro. Flavopiridol thus is able to interfere with both activating modifications of GP-b, AMP activation and phosphorylation. In A549 NSCLC cells flavopiridol treatment caused glycogen accumulation despite of an increase in GP activity, suggesting direct GP inhibition in vivo rather than inhibition of GP activation by phosphorylase kinase. These results suggest that the cyclin-dependent kinase inhibitor flavopiridol interferes with glycogen degradation, which may be responsible for flavopiridol's cytotoxicity and explain its resistance in some cell lines.

  4. Effect of fat emulsion infusion and fat feeding on muscle glycogen utilization during cycle exercise.

    PubMed

    Vukovich, M D; Costill, D L; Hickey, M S; Trappe, S W; Cole, K J; Fink, W J

    1993-10-01

    Elevated plasma fatty acids have been shown to spare muscle glycogen during exercise. However, on the basis of recent findings, the saturation of fatty acids may influence this response. The purpose of this study was to determine whether saturated or unsaturated fatty acids affected muscle glycogenolysis to varying degrees during cycle exercise. Five healthy men completed three 60-min cycle ergometer trials (EX) at approximately 70% maximal O2 uptake (VO2max). Triglyceride levels were elevated by a fat feeding (FF) composed of 90% saturated fatty acids (heavy whipping cream, 90 g) or by the infusion of Intralipid (IL; Clintec Nutrition; 45 ml/h of 20% IL, 9.0 g), which was 85% unsaturated. A control trial (CON) consisted of a light breakfast (43 g carbohydrate and 1 g fat). Heparin (2,000 U) was administered 15 min before EX in FF and IL trials, resulting in one- and threefold increases in free fatty acid (FFA) levels in IL and FF, respectively. Pre-EX muscle glycogen did not differ. The utilization of muscle glycogen during 60 min of EX was less (P < 0.05) during the FF (60.0 +/- 5.2 mmol/kg wet wt) and IL (58.6 +/- 6.2 mmol/kg wet wt) compared with CON (81.8 +/- 7.5 mmol/kg wet wt). There was no difference between FF and IL in the amount of glycogen utilized. Serum triglyceride levels were greater (P < 0.05) at preheparin in FF (1.58 +/- 0.37 mmol/l) and IL (0.98 +/- 0.13 mmol/l) compared with CON (0.47 +/- 0.14 mmol/l).(ABSTRACT TRUNCATED AT 250 WORDS)

  5. MiR-19a regulates PTEN expression to mediate glycogen synthesis in hepatocytes

    PubMed Central

    Dou, Lin; Meng, Xiangyu; Sui, Xiaofang; Wang, Shuyue; Shen, Tao; Huang, Xiuqing; Guo, Jun; Fang, Weiwei; Man, Yong; Xi, Jianzhong; Li, Jian

    2015-01-01

    MiR-19a, a member of mir-17-92 microRNA clusters, has been demonstrated to promote cell proliferation and angiogenesis via regulating the PI3K/AKT pathway, the major insulin signaling pathway. However, whether miR-19a plays an important role in glycogen synthesis in hepatocytes remains unknown. Here, we define the impact of miR-19a on glycogen synthesis and IL-6-induced reduced glycogenesis in hepatocytes and its underlying mechanisms. Our studies indicate that miR-19a was down-regulated in the livers of db/db mice and mice injected with IL-6, as well as mouse NCTC 1469 hepatocytes and HEP 1–6 hepatocytes treated by IL-6. We found that over-expression of miR-19a in NCTC 1469 cells and HEP 1–6 cells led to increased activation of the AKT/GSK pathway and synthesis of glycogen, whereas down-regulation of miR-19a impaired AKT/GSK phosphorylation and glycogenesis. Over-expression of miR-19a ameliorated IL-6-induced reduced glycogen synthesis in hepatocytes. Moreover, we identified PTEN as the target of miR-19a by a luciferase assay. Down-regulation of PTEN rescued the effects of miR-19a suppression on the activation of the AKT/GSK pathway and improved glycogenesis in NTC 1469 cells. These findings show for the first time that miR-19a might activate the AKT/GSK pathway and glycogenesis via down-regulation of PTEN expression. PMID:26111969

  6. Regulation of yeast glycogen metabolism and sporulation by Glc7p protein phosphatase.

    PubMed Central

    Ramaswamy, N T; Li, L; Khalil, M; Cannon, J F

    1998-01-01

    Glc7p is an essential serine/threonine type 1 protein phosphatase (PP1) from the yeast Saccharomyces cerevisiae, which has a role in many processes including cell cycle progression, sporulation, glycogen accumulation, translation initiation, and glucose repression. Two hallmarks of PP1 enzymes are very high amino acid sequence conservation and association of the catalytic subunit with a variety of noncatalytic, regulatory subunits. We tested the hypothesis that PP1 sequence conservation was the result of each PP1 residue playing a role in multiple intermolecular interactions. Analysis of 24 glc7 mutants, isolated primarily by their glycogen accumulation traits, revealed that every mutated Glc7p residue altered many noncatalytic subunit affinities and conferred unselected sporulation traits to various degrees. Furthermore, quantitative analysis showed that Glc7p affinity for the glycogen-binding noncatalytic subunit Gac1p was not the only parameter that determines the glycogen accumulation by a glc7 mutant. Sds22p is one Glc7p noncatalytic subunit that is essential for mitotic growth. Surprisingly, several mutant Glc7p proteins had undetectable affinity for Sds22p, yet grew apparently normally. The characterization of glc7 diploid sporulation revealed that Glc7p has at least two meiotic roles. Premeiotic DNA synthesis was undetectable in glc7 mutants with the poorest sporulation. In the glc7 diploids examined, expression of the meiotic inducer IME1 was proportional to the glc7 diploid sporulation frequency. Moreover, IME1 hyperexpression could not suppress glc7 sporulation traits. The Glc7p/Gip1p holoenzyme may participate in completion of meiotic divisions or spore packaging because meiotic dyads predominate when some glc7 diploids sporulate. PMID:9584086

  7. Glycogen synthesis from lactate in skeletal muscle of the lizard Dipsosaurus dorsalis.

    PubMed

    Gleeson, T T

    1985-01-01

    The capacity of skeletal muscle to synthesize glycogen from lactate was tested in the iliofibularis muscle of the desert iguana, Dipsosaurus dorsalis. Like other reptiles, Dipsosaurus accumulates significant lactic acid concentrations following vigorous exercise. After 5 min of progressively faster treadmill running at 35 degrees C (final speed = 2.2 km/h), blood lactate concentration increased over 14 mM, which decreased 11 mM after 2 h of recovery. Blood glucose concentration remained unchanged throughout at 8.6 +/- 0.46 mM. The role that muscle gluconeogenesis might play in the removal of post-exercise lactate was evaluated. Animals were run to exhaustion at 1.5 km/h on a treadmill thermostatted at 35 degrees C. Animals (n = 43) ran 6.9 +/- 0.75 min prior to exhaustion. Animals were sacrificed and iliofibularis muscles of both hindlimbs removed and stimulated at 2 Hz for 5 min, reducing twitch tension to 6% of prestimulus tension. Fatigued muscles were then split into red and white fiber bundles and incubated 2 h or 5 h at 35 degrees C in Ringer solution or in Ringer plus 20 mM lactate. In muscles tested in August, red fiber bundles incubated in lactate demonstrated a rate of glycogen synthesis of approximately 1 mg/(g muscle . h). In muscles tested in December, red fiber bundles synthesized glycogen at a reduced rate that was not statistically different than in fiber bundles incubated in Ringer solution without lactate. Glycogen synthesis from lactate was not evident in white fiber bundles in either August or December. The period of peak gluconeogenic capacity coincides with the field active season of Dipsosaurus.(ABSTRACT TRUNCATED AT 250 WORDS)

  8. Hepatic serine and alanine metabolism during endotoxin-induced fever in sheep.

    PubMed Central

    Southorn, B G; Thompson, J R

    1987-01-01

    Time course changes in plasma amino acid concentrations and the hepatic metabolism of serine and alanine were measured in six mature wethers during endotoxin-induced fever. In separate trials, the animals' responses to injections of saline and endotoxin were measured. The endotoxin was from Escherichia coli serotype 055:B5 and was injected intravenously (4 micrograms/kg body weight). Liver biopsies were obtained from the sheep at 6 h postinjection during both endotoxin and saline injection trials. Rectal temperature in the endotoxin treated animals was increased (P less than 0.05, above that in control animals from 4.25 h to 9 h postinjection, with a maximum rise of 2.43 degrees C at 5.5 h postinjection. Glucose concentration in jugular plasma decreased (P less than 0.05) by 3 h postinjection and remained depressed throughout the 24 h postinjection sampling period. Plasma serine concentration was decreased (P less than 0.05) by 3 h postinjection. Plasma alanine concentration was decreased significantly (P less than 0.05) only at 24 h postinjection. Endotoxin injection increased (P less than 0.05) hepatic oxidation of 14C-serine (162%) and the net incorporation of 14C-serine carbon into hepatic protein (173%) and glycogen (275%). The net incorporation of 14C-alanine carbon into hepatic protein (172%) and glycogen (323%) were increased (P less than 0.05) by endotoxin injection, while alanine oxidation was not affected by endotoxin treatment (P greater than 0.05). The increased hepatic use of serine may explain, in part, the dramatic decrease in plasma concentrations of this amino acid following endotoxin injection into sheep. PMID:3115552

  9. Melatonin reduces hepatic mitochondrial dysfunction in diabetic obese rats.

    PubMed

    Agil, Ahmad; El-Hammadi, Mazen; Jiménez-Aranda, Aroa; Tassi, Mohamed; Abdo, Walied; Fernández-Vázquez, Gumersindo; Reiter, Russel J

    2015-08-01

    Hepatic mitochondrial dysfunction is thought to play a role in the development of liver steatosis and insulin resistance, which are both common characteristics of obesity and type 2 diabetes mellitus (T2DM). It was hypothesized that the antioxidant properties of melatonin could potentially improve the impaired functions of hepatic mitochondria in diabetic obese animals. Male Zucker diabetic fatty (ZDF) rats and lean littermates (ZL) were given either melatonin (10 mg/kg BW/day) orally for 6 wk (M-ZDF and M-ZL) or vehicle as control groups (C-ZDF and C-ZL). Hepatic function was evaluated by measurement of serum alanine transaminase and aspartate transaminase levels, liver histopathology and electron microscopy, and hepatic mitochondrial functions. Several impaired functions of hepatic mitochondria were observed in C-ZDF in comparison with C-ZL rats. Melatonin treatment to ZDF rats decreases serum levels of ALT (P < 0.001), alleviates liver steatosis and vacuolation, and also mitigates diabetic-induced mitochondrial abnormalities, glycogen, and lipid accumulation. Melatonin improves mitochondrial dysfunction in M-ZDF rats by increasing activities of mitochondrial citrate synthase (P < 0.001) and complex IV of electron transfer chain (P < 0.05) and enhances state 3 respiration (P < 0.001), respiratory control index (RCR) (P < 0.01), and phosphorylation coefficient (ADP/O ratio) (P < 0.05). Also melatonin augments ATP production (P < 0.05) and diminishes uncoupling protein 2 levels (P < 0.001). These results demonstrate that chronic oral melatonin reduces liver steatosis and mitochondria dysfunction in ZDF rats. Therefore, it may be beneficial in the treatment of diabesity.

  10. Late form of Pompe disease with glycogen storage in peripheral nerves axons.

    PubMed

    Fidziańska, Anna; Ługowska, Agnieszka; Tylki-Szymańska, Anna

    2011-02-15

    Pompe disease is caused by the deficiency of acid α-glucosidase (GAA), which degrades glycogen into glucose. Its manifestation is characterized by a broad and continuous spectrum of clinical severity ranging from severe infantile to relatively benign adult form. We describe a 12-year-old girl diagnosed at a presymptomatic stage of late form Pompe disease due to fortuitous detection of an elevated level of serum creatine kinase (CK) at the age of 4. Biopsies were taken from the quadriceps muscle and studied with histological and histochemical techniques, as well as in electron microscope. Sporadic muscle cells showed the accumulation of lysosomal glycogen, suggesting Pompe disease. Interestingly, we found lysosomal bound glycogen, located in the axons of intramuscular nerves. The diagnosis was confirmed by deficient GAA activity in leukocytes. Mutation analysis revealed changes IVS1-13T>G and p.C103G in the GAA gene. The patient was able to obtain enzyme replacement therapy in the early asymptomatic stage of the disease.

  11. Exercise testing in late-onset glycogen storage disease type II patients undergoing enzyme replacement therapy.

    PubMed

    Marzorati, Mauro; Porcelli, Simone; Bellistri, Giuseppe; Morandi, Lucia; Grassi, Bruno

    2012-12-01

    Enzyme replacement therapy (ERT) has recently became available for patients with glycogen storage disease type II. Previous studies have demonstrated clinical efficacy of enzyme replacement therapy, however, data on physiological variables related to exercise tolerance are scarce. Four glycogen storage disease type II late-onset patients (45 ± 6 years) performed an incremental exercise on a cycle ergometer, up to voluntary exhaustion, before (BEFORE) and after 12 months of ERT (AFTER). Peak workload, oxygen uptake, heart rate, cardiac output (by impedance cardiography) and vastus lateralis oxygenation indices (by continuous-wave near-infrared spectroscopy, NIRS) were determined. Peak workload and oxygen uptake values significantly increased during ERT (54 ± 30 vs. 63 ± 31 watt, and 17.2 ± 4.4 vs. 19.7 ± 3.5 ml/kg/min, respectively, in BEFORE vs. AFTER). On the other hand, for both peak cardiac output (12.3 ± 5.3 vs. 14.8 ± 4.5L/min) and the NIRS-determined peak skeletal muscle fractional O(2) extraction, expressed as a percentage of the maximal values during a transient limb ischemia (30 ± 39% vs. 38 ± 28%), the observed increases were not statistically significant. Our findings suggest that in glycogen storage disease type II patients enzyme replacement therapy is associated with a mild improvement of exercise tolerance. The findings need to be validated during a longer follow-up on a larger group of patients.

  12. Carbohydrate ingestion and muscle glycogen depletion during marathon and ultramarathon racing.

    PubMed

    Noakes, T D; Lambert, E V; Lambert, M I; McArthur, P S; Myburgh, K H; Benade, A J

    1988-01-01

    Two studies were undertaken to characterize the effects of carbohydrate ingestion on fuel/hormone response to exercise and muscle glycogen utilization during prolonged competitive exercise. In study 1, eighteen subjects were divided into three groups, matched for maximum oxygen consumption (VO2max) and blood lactate turnpoint. All subjects underwent a 3-day carbohydrate (CHO) depletion phase, followed by 3 days of CHO loading (500-600 g.day-1). During the race, the groups drank either 2% glucose (G), 8% glucose polymer (GP), or 8% fructose (F). Muscle biopsies were performed before and after the race and venous blood was sampled before and at regular intervals during the race. In study 2, eighteen subjects divided into 2 matched groups ingested either a 4% G or 10% GP solution during a 56 km race. Despite significantly greater CHO ingestion by GP and F in study 1 and by GP in study 2, blood glucose, free fatty acids and insulin concentrations, muscle glycogen utilization and running performance were not different between groups. These studies show (i) that hypoglycaemia is uncommon in athletes competing in races of up to 56 km provided they CHO-load before and ingest a minimum of 10 g CHO.h-1 during competition; (ii) that neither the amount (10 g vs 40 g.h-1) nor the type of carbohydrate (G vs GP vs F) has any effect on the extent of muscle glycogen depletion or running performance in matched subjects racing over distances up to 56 km.

  13. Incorporation of metabolites into glycogen and lipids of the oyster, crassostrea virginica

    SciTech Connect

    Swift, M.L.; Humphrey, C.L. )

    1987-05-01

    Groups of oysters, either fed or unfed, were exposed to U-{sup 14}C labelled D-glucose, L-asp, L-leu, L-ala or acetate for 6 hrs. Except for the glucose trials, the disappearance of radioactivity from the saline of the unfed oysters was greater (83%) than for the fed animals (65%). With glucose, 88% of the radioactivity disappeared in each trial. The specific radioactivity of glycogen isolated from oysters exposed to labelled glucose, asp and ala was 1283, 468 and 8.22 dpm/mg glycogen respectively. Radioactivity was found primarily in the triacylglycerols and phospholipids (PL) in fed oysters and in PL only in unfed oysters. Phosphatidyl choline, phosphatidyl ethanolamine, and a fraction containing phosphatidyl serine and phosphatidyl inositol, had 32%, 25% and 35-40% of the radioactivity respectively. Incorporation of total radioactivity into PL was 70% lower in unfed vs. fed trials, but the distribution of counts among the phospholipids classes was unchanged. Glycogenesis does not appear to be a significant pathway in the oyster. Apparently well-fed oysters are able to store excess dietary calories as lipid. During periods of starvation exogenous small metabolites along with glucose from glycogen are catabolized.

  14. Effect of Alpha-Particle Irradiation on Brain Glycogen in the Rat

    NASA Technical Reports Server (NTRS)

    Wolfe, L. S.; Klatzo, Igor; Miquel, Jaime; Tobias, Cornelius; Haymaker, Webb

    1962-01-01

    The studies of Klatzo, Miquel, Tobias and Haymaker (1961) have shown that one of the earliest and most sensitive indications of the effects of alpha-particle irradiation on rat bran is the appearance of glycogen granules mainly in the neuroglia of the exposed area of the brain. Periodic acid-Schiff (PAS) positive, alpha-amylase soluble granules were demonstrated within 12 hr after irradiation, preceding by approximately 36 hr the first microscopically detectable vascular permeability disturbances, as shown by the fluorescein labeled serum protein technique. These studies suggested that the injurious effects of alpha-particle energy were on cellular elements primarily, according to the physical properties and distribution of the radiation in the tissue, and that the vascular permeability disturbances played a secondary role in pathogenesis. The purpose of this study was to correlate the histochemical observations on glycogen with a quantitative assessment of the glycogen in the irradiated brain tissue. It is felt that such a study may contribute to the understanding of radiation injury at the molecular level. A practical aspect of this problem is that the information on biological radiation effects due to accelerated particles from the cyclotron source, is employed in this study, is applicable to radiation from cosmic particles both in free space and entrapped in the Van Allen belts.

  15. Neurodegeneration and functional impairments associated with glycogen synthase accumulation in a mouse model of Lafora disease

    PubMed Central

    Valles-Ortega, Jordi; Duran, Jordi; Garcia-Rocha, Mar; Bosch, Carles; Saez, Isabel; Pujadas, Lluís; Serafin, Anna; Cañas, Xavier; Soriano, Eduardo; Delgado-García, José M; Gruart, Agnès; Guinovart, Joan J

    2011-01-01

    Lafora disease (LD) is caused by mutations in either the laforin or malin gene. The hallmark of the disease is the accumulation of polyglucosan inclusions called Lafora Bodies (LBs). Malin knockout (KO) mice present polyglucosan accumulations in several brain areas, as do patients of LD. These structures are abundant in the cerebellum and hippocampus. Here, we report a large increase in glycogen synthase (GS) in these mice, in which the enzyme accumulates in LBs. Our study focused on the hippocampus where, under physiological conditions, astrocytes and parvalbumin-positive (PV+) interneurons expressed GS and malin. Although LBs have been described only in neurons, we found this polyglucosan accumulation in the astrocytes of the KO mice. They also had LBs in the soma and some processes of PV+ interneurons. This phenomenon was accompanied by the progressive loss of these neuronal cells and, importantly, neurophysiological alterations potentially related to impairment of hippocampal function. Our results emphasize the relevance of the laforin–malin complex in the control of glycogen metabolism and highlight altered glycogen accumulation as a key contributor to neurodegeneration in LD. PMID:21882344

  16. Neuromuscular responses to mild-muscle damaging eccentric exercise in a low glycogen state.

    PubMed

    Gavin, James P; Myers, Stephen D; Willems, Mark E T

    2015-02-01

    The aim of this study was to examine the effect of low muscle glycogen on the neuromuscular responses to maximal eccentric contractions. Fourteen healthy men (22 ± 3 years) performed single-leg cycling (20 min at ~75% maximal oxygen uptake (V̇O2 max); eight 90 s sprints at a 1:1 work-to-rest ratio (5% decrements from 90% to 55% V̇O2 max until exhaustion) the evening before 100 eccentric (1.57 rads(-1)) with reduced (RED) and normal glycogen (NORM). Neuromuscular responses were measured during and up to 48 h after with maximal voluntary and involuntary (twitch, 20 Hz and 50 Hz) isometric contractions. During eccentric contractions, peak torque decreased (RED: -16.1 ± 2.5%; NORM: -6.2 ± 5.1%) and EMG frequency increased according to muscle length. EMG activity decreased for RED only. After eccentric contractions, maximal isometric force was reduced up to 24h for NORM (-13.5 ± 5.8%) and 48 h for RED (-7.4 ± 10.9%). Twelve hours after eccentric contractions, twitch force and the 20:50 Hz ratio were decreased for RED but not for NORM. Immediate involuntary with prolonged voluntary force loss suggests that reduced glycogen is associated with increased susceptibility to mild muscle-damaging eccentric exercise with contributions of peripheral and central mechanisms to be different during recovery.

  17. Dicarboxylic aciduria during ketotic phases in various types of glycogen storage disease.

    PubMed

    Pettersen, J E; Winsnes, A

    1981-01-01

    Urine samples were collected before and after a starvation period of 14-16 h from patients with glycogen storage disease, one with type III (amylo-1,6-glucosidase deficiency), four with type VIII (phosphorylase-b-kinase deficiency), and one with an unclassified type. The excretion of adipic, suberic, and 3-hydroxybutyric acid was measured by combined gas chromatography-mass spectrometry. The tendency towards ketosis seemed to decline with age in the patients with type VIII. In the non-ketotic patients no excess amounts of dicarboxylic acids were excreted. Therefore, glycogen storage disease per se seems to have no direct relationship to the excretion of adipic or suberic acid. A positive correlation was, however, found between the urinary excretion of on one side 3-hydroxybutyric and on the other adipic (correlation coefficient (Kendall's tau) +0.64, P less than 0.002 (one-sided test)) or suberic (+0.61, P less than 0.003) acid. The two dicarboxylic acids are most probably formed from long-chain monocarboxylic acids by omega- and beta-oxidation. It is speculated that succinyl-CoA formed by this pathway may counteract the tendency to ketosis in patients with glycogen storage disease.

  18. Molecular and biochemical characterization of Tunisian patients with glycogen storage disease type III.

    PubMed

    Mili, Amira; Ben Charfeddine, Ilhem; Mamaï, Ons; Abdelhak, Sonia; Adala, Labiba; Amara, Abdelbasset; Pagliarani, Serena; Lucchiarri, Sabrina; Lucchiari, Sabrina; Ayadi, Abdelkarim; Tebib, Neji; Harbi, Abdelaziz; Bouguila, Jihene; H'Mida, Dorra; Saad, Ali; Limem, Khalifa; Comi, G P; Gribaa, Moez

    2012-03-01

    Glycogen storage disease type III (GSD III) is an autosomal recessive inborn error of metabolism caused by mutations in the glycogen debranching enzyme amylo-1,6-glucosidase gene, which is located on chromosome 1p21.2. GSD III is characterized by the storage of structurally abnormal glycogen, termed limit dextrin, in both skeletal and cardiac muscle and/or liver, with great variability in resultant organ dysfunction. The spectrum of AGL gene mutations in GSD III patients depends on ethnic group. The most prevalent mutations have been reported in the North African Jewish population and in an isolate such as the Faroe Islands. Here, we present the molecular and biochemical analyses of 22 Tunisian GSD III patients. Molecular analysis revealed three novel mutations: nonsense (Tyr1148X) and two deletions (3033_3036del AATT and 3216_3217del GA) and five known mutations: three nonsense (R864X, W1327X and W255X), a missense (R524H) and an acceptor splice-site mutation (IVS32-12A>G). Each mutation is associated to a specific haplotype. This is the first report of screening for mutations of AGL gene in the Tunisian population.

  19. Correction of glycogen storage disease type II by an adeno-associated virus vector containing a muscle-specific promoter.

    PubMed

    Sun, Baodong; Zhang, Haoyue; Franco, Luis M; Brown, Talmage; Bird, Andrew; Schneider, Ayn; Koeberl, Dwight D

    2005-06-01

    Glycogen storage disease type II (Pompe disease) causes death in infancy from cardiorespiratory failure due to acid alpha-glucosidase (GAA; acid maltase) deficiency. An AAV2 vector pseudotyped as AAV6 (AAV2/6 vector) transiently expressed high-level human GAA in GAA-knockout (GAA-KO) mice without reducing glycogen storage; however, in immunodeficient GAA-KO/SCID mice the AAV2/6 vector expressed high-level GAA and reduced the glycogen content of the injected muscle for 24 weeks. A CD4+/CD8+ lymphocytic infiltrate was observed in response to the AAV2/6 vector in immunocompetent GAA-KO mice. When a muscle-specific creatine kinase promoter was substituted for the CB promoter (AAV-MCKhGAApA), that AAV2/6 vector expressed high-level GAA and reduced glycogen content in immunocompetent GAA-KO mice. Muscle-restricted expression of hGAA provoked only a humoral (not cellular) immune response. Intravenous administration of a high number of particles of AAV-MCKhGAApA as AAV2/7 reduced the glycogen content of the heart and skeletal muscle and corrected individual myofibers in immunocompetent GAA-KO mice 24 weeks postinjection. In summary, persistent correction of muscle glycogen content was achieved with an AAV vector containing a muscle-specific promoter in GAA-KO mice, and this approach should be considered for muscle-targeted gene therapy in Pompe disease.

  20. Effect of eccentric exercise with reduced muscle glycogen on plasma interleukin-6 and neuromuscular responses of musculus quadriceps femoris.

    PubMed

    Gavin, James P; Myers, Stephen D; Willems, Mark E T

    2016-07-01

    Eccentric exercise can result in muscle damage and interleukin-6 (IL-6) secretion. Glycogen availability is a potent stimulator of IL-6 secretion. We examined effects of eccentric exercise in a low-glycogen state on neuromuscular function and plasma IL-6 secretion. Twelve active men (23 ± 4 yr, 179 ± 5 cm, 77 ± 10 kg, means ± SD) completed two downhill treadmill runs (gradient, -12%, 5 × 8 min; speed, 12.1 ± 1.1 km/h) with normal (NG) and reduced muscle glycogen (RG) in randomized order and at least 6 wk apart. Muscle glycogen was reduced using an established cycling protocol until exhaustion and dietary manipulation the evening before the morning run. Physiological responses were measured up to 48 h after the downhill runs. During recovery, force deficits of musculus quadriceps femoris by maximal isometric contractions were similar. Changes in low-frequency fatigue were larger with RG. Voluntary activation and plasma IL-6 levels were similar in recovery between conditions. It is concluded that unaccustomed, damaging eccentric exercise with low muscle glycogen of the m. quadriceps femoris 1) exacerbated low-frequency fatigue but 2) had no additional effect on IL-6 secretion. Neuromuscular impairment after eccentric exercise with low muscle glycogen appears to have a greater peripheral component in early recovery.

  1. Microfluorometric analyses of glycogen in freshly dissected, single skeletal muscle fibres of the cane toad using a mechanically skinned fibre preparation.

    PubMed

    Nguyen, L T; Stephenson, D G; Stephenson, G M

    1998-08-01

    The main objective of this study was to analyse glycogen in single muscle fibres, using a recently developed microfluorometric method which detects subpicomol amounts of NADPH, glucose and glycogen (as glucosyl units) (detection limit 0.16-0.17 pmol in a 25 nl sample) without fluorochrome amplification. The fibres were freshly dissected from the twitch region of the iliofibularis muscle of the cane toad (Bufo marinus), and were mechanically skinned under paraffin oil to gain access to the intracellular compartments. The results show that (1) glycogen concentrations in toad skeletal muscle fibres range between 25.8 and 369 mmol glucosyl units/litre fibre volume; (2) there is a large variation in glycogen content between individual fibres from the iliofibularis muscle of one animal; (3) there are seasonal differences in the glycogen content of toad single muscle fibres; (4) the total amount of glycogen in single muscle fibres of the toad does not decrease significantly when storing the tissue, under paraffin oil, at 20-25 degree C for up to 6 h or at 4 degree C for up to 24 h; and (5) 15-26% of fibre glycogen can be washed in an aqueous solution at pH 5-7, within 5 min, while 74-85% of fibre glycogen remains associated with the washed skinned fibre, even after 40 min exposure of the skinned fibre preparation to the aqueous environment. The retention of most glycogen in the fibre preparation after mechanical removal of the plasma membrane and extensive washing indicates that in toad skeletal muscle fibres the largest proportion of glycogen is tightly bound to intracellular structures. The results also show that the skinned muscle fibre preparation is well suited for microfluorometric glycogen determination, since low molecular weight non-glycogen contributors to the fluorescence signal can be removed from the myoplasmic space prior to the glycogen hydrolysis step.

  2. Hepatic hematoma and hepatic rupture in pregnancy.

    PubMed

    Poo, Jorge Luis; Góngora, Julieta

    2006-01-01

    Hepatic perforation is an unusual complication of woman pregnancy associated with a poor outcome. A comprehensive review of epidemiology, clinical spectrum, diagnostic methods and therapeutic options is presented in this short paper.

  3. Autophagy in hepatic fibrosis.

    PubMed

    Song, Yang; Zhao, Yingying; Wang, Fei; Tao, Lichan; Xiao, Junjie; Yang, Changqing

    2014-01-01

    Hepatic fibrosis is a leading cause of morbidity and mortality worldwide. Hepatic fibrosis is usually associated with chronic liver diseases caused by infection, drugs, metabolic disorders, or autoimmune imbalances. Effective clinical therapies are still lacking. Autophagy is a cellular process that degrades damaged organelles or protein aggregation, which participates in many pathological processes including liver diseases. Autophagy participates in hepatic fibrosis by activating hepatic stellate cells and may participate as well through influencing other fibrogenic cells. Besides that, autophagy can induce some liver diseases to develop while it may play a protective role in hepatocellular abnormal aggregates related liver diseases and reduces fibrosis. With a better understanding of the potential effects of autophagy on hepatic fibrosis, targeting autophagy might be a novel therapeutic strategy for hepatic fibrosis in the near future.

  4. Preventing hepatitis B or C

    MedlinePlus

    ... page: //medlineplus.gov/ency/patientinstructions/000401.htm Preventing hepatitis B or C To use the sharing features on this page, please enable JavaScript. Hepatitis B and hepatitis C infections cause irritation and ...

  5. Hepatocyte nuclear factor 4alpha controls the development of a hepatic epithelium and liver morphogenesis.

    PubMed

    Parviz, Fereshteh; Matullo, Christine; Garrison, Wendy D; Savatski, Laura; Adamson, John W; Ning, Gang; Kaestner, Klaus H; Rossi, Jennifer M; Zaret, Kenneth S; Duncan, Stephen A

    2003-07-01

    Although advances have been made in understanding cell differentiation, only rudimentary knowledge exists concerning how differentiated cells form tissues and organs. We studied liver organogenesis because the cell and tissue architecture of this organ is well defined. Approximately 60% of the adult liver consists of hepatocytes that are arranged as single-cell anastomosing plates extending from the portal region of the liver lobule toward the central vein. The basal surface of the hepatocytes is separated from adjacent sinusoidal endothelial cells by the space of Disse, where the exchange of substances between serum and hepatocytes takes place. The hepatocyte's apical surface forms bile canaliculi that transport bile to the hepatic ducts. Proper liver architecture is crucial for hepatic function and is commonly disrupted in disease states, including cirrhosis and hepatitis. Here we report that hepatocyte nuclear factor 4alpha (Hnf4alpha) is essential for morphological and functional differentiation of hepatocytes, accumulation of hepatic glycogen stores and generation of a hepatic epithelium. We show that Hnf4alpha is a dominant regulator of the epithelial phenotype because its ectopic expression in fibroblasts induces a mesenchymal-to-epithelial transition. Most importantly, the morphogenetic parameters controlled by Hnf4alpha in hepatocytes are essential for normal liver architecture, including the organization of the sinusoidal endothelium.

  6. Insulin receptor Thr1160 phosphorylation mediates lipid-induced hepatic insulin resistance

    PubMed Central

    Petersen, Max C.; Madiraju, Anila K.; Gassaway, Brandon M.; Marcel, Michael; Nasiri, Ali R.; Butrico, Gina; Marcucci, Melissa J.; Zhang, Dongyan; Abulizi, Abudukadier; Zhang, Xian-Man; Philbrick, William; Hubbard, Stevan R.; Samuel, Varman T.; Rinehart, Jesse

    2016-01-01

    Nonalcoholic fatty liver disease (NAFLD) is a risk factor for type 2 diabetes (T2D), but whether NAFLD plays a causal role in the pathogenesis of T2D is uncertain. One proposed mechanism linking NAFLD to hepatic insulin resistance involves diacylglycerol-mediated (DAG-mediated) activation of protein kinase C-ε (PKCε) and the consequent inhibition of insulin receptor (INSR) kinase activity. However, the molecular mechanism underlying PKCε inhibition of INSR kinase activity is unknown. Here, we used mass spectrometry to identify the phosphorylation site Thr1160 as a PKCε substrate in the functionally critical INSR kinase activation loop. We hypothesized that Thr1160 phosphorylation impairs INSR kinase activity by destabilizing the active configuration of the INSR kinase, and our results confirmed this prediction by demonstrating severely impaired INSR kinase activity in phosphomimetic T1160E mutants. Conversely, the INSR T1160A mutant was not inhibited by PKCε in vitro. Furthermore, mice with a threonine-to-alanine mutation at the homologous residue Thr1150 (InsrT1150A mice) were protected from high fat diet–induced