A Mouse Model of Glycogen Storage Disease Type IX-Beta: A Role for Phkb in Glycogenolysis.

Glycogen storage disease type IX (GSD-IX) constitutes nearly a quarter of all GSDs. This ketotic form of GSD is caused by mutations in phosphorylase kinase (PhK), which is composed of four subunits (α, ß, γ, δ). PhK is required for the activation of the liver isoform of glycogen phosphorylase (PYGL), which generates free glucose-1-phosphate monomers to be used as energy via cleavage of the α -(1,4) glycosidic linkages in glycogen chains. Mutations in any of the PhK subunits can negatively affect the regulatory and catalytic activity of PhK during glycogenolysis. To understand the pathogenesis of GSD-IX-beta, we characterized a newly created PHKB knockout (Phkb−/−) mouse model. In this study, we assessed fasting blood glucose and ketone levels, serum metabolite concentrations, glycogen phosphorylase activity, and gene expression of gluconeogenic genes and fibrotic genes. Phkb−/− mice displayed hepatomegaly with lower fasting blood glucose concentrations. Phkb−/− mice showed partial liver glycogen phosphorylase activity and increased sensitivity to pyruvate, indicative of partial glycogenolytic activity and upregulation of gluconeogenesis. Additionally, gene expression analysis demonstrated increased lipid metabolism in Phkb−/− mice. Gene expression analysis and liver histology in the livers of old Phkb−/− mice (>40 weeks) showed minimal profibrogenic features when analyzed with age-matched wild-type (WT) mice. Collectively, the Phkb−/− mouse recapitulates mild clinical features in patients with GSD-IX-beta. Metabolic and molecular analysis confirmed that Phkb−/− mice were capable of sustaining energy homeostasis during prolonged fasting by using partial glycogenolysis, increased gluconeogenesis, and potentially fatty acid oxidation in the liver.

Exosomal MicroRNAs as Potential Biomarkers of Hepatic Injury and Kidney Disease in Glycogen Storage Disease Type Ia Patients.

Glycogen storage disease type Ia (GSDIa) is an inherited metabolic disorder caused by mutations in the enzyme glucose-6-phosphatase-α (G6Pase-α). Affected individuals develop renal and liver complications, including the development of hepatocellular adenoma/carcinoma and kidney failure. The purpose of this study was to identify potential biomarkers of the evolution of the disease in GSDIa patients. To this end, we analyzed the expression of exosomal microRNAs (Exo-miRs) in the plasma exosomes of 45 patients aged 6 to 63 years. Plasma from age-matched normal individuals were used as controls. We found that the altered expression of several Exo-miRs correlates with the pathologic state of the patients and might help to monitor the progression of the disease and the development of late GSDIa-associated complications.

Liver Glycogen Phosphorylase Deficiency Leads to Profibrogenic Phenotype in a Murine Model of Glycogen Storage Disease Type VI.

Mutations in the liver glycogen phosphorylase (Pygl) gene are associated with the diagnosis of glycogen storage disease type VI (GSD-VI). To understand the pathogenesis of GSD-VI, we generated a mouse model with Pygl deficiency (Pygl -/-). Pygl -/- mice exhibit hepatomegaly, excessive hepatic glycogen accumulation, and low hepatic free glucose along with lower fasting blood glucose levels and elevated blood ketone bodies. Hepatic glycogen accumulation in Pygl -/- mice increases with age. Masson's trichrome and picrosirius red staining revealed minimal to mild collagen deposition in periportal, subcapsular, and/or perisinusoidal areas in the livers of old Pygl -/- mice (>40 weeks). Consistently, immunohistochemical analysis showed the number of cells positive for alpha smooth muscle actin (α-SMA), a marker of activated hepatic stellate cells, was increased in the livers of old Pygl -/- mice compared with those of age-matched wild-type (WT) mice. Furthermore, old Pygl -/- mice had inflammatory infiltrates associated with hepatic vessels in their livers along with up-regulated hepatic messenger RNA levels of C-C chemokine ligand 5 (Ccl5/Rantes) and monocyte chemoattractant protein 1 (Mcp-1), indicating inflammation, while age-matched WT mice did not. Serum levels of aspartate aminotransferase and alanine aminotransferase were elevated in old Pygl -/- mice, indicating liver damage. Conclusion: Pygl deficiency results in progressive accumulation of hepatic glycogen with age and liver damage, inflammation, and collagen deposition, which can increase the risk of liver fibrosis. Collectively, the Pygl-deficient mouse recapitulates clinical features in patients with GSD-VI and provides a model to elucidate the mechanisms underlying hepatic complications associated with defective glycogen metabolism.

Long-term safety and efficacy of AAV gene therapy in the canine model of glycogen storage disease type Ia.

BACKGROUND: Viral mediated gene therapy has progressed after overcoming early failures, and gene therapy has now been approved for several conditions in Europe and the USA. Glycogen storage disease (GSD) type Ia, caused by a deficiency of glucose-6-phosphatase-α, has been viewed as an outstanding candidate for gene therapy. This follow-up report describes the long-term outcome for the naturally occurring GSD-Ia dogs treated with rAAV-GPE-hG6PC-mediated gene therapy. METHODS: A total of seven dogs were treated with rAAV-GPE-hG6PC-mediated gene therapy. The first four dogs were treated at birth, and three dogs were treated between 2 and 6 months of age to assess the efficacy and safety in animals with mature livers. Blood and urine samples, radiographic studies, histological evaluation, and biodistribution were assessed. RESULTS: Gene therapy improved survival in the GSD-Ia dogs. With treatment, the biochemical studies normalized for the duration of the study (up to 7 years). None of the rAAV-GPE-hG6PC-treated dogs had focal hepatic lesions or renal abnormalities. Dogs treated at birth required a second dose of rAAV after 2-4 months; gene therapy after hepatic maturation resulted in improved efficacy after a single dose. CONCLUSION: rAAV-GPE-hG6PC treatment in GSD-Ia dogs was found to be safe and efficacious. GSD-Ia is an attractive target for human gene therapy since it is a monogenic disorder with limited tissue involvement. Blood glucose and lactate monitoring can be used to assess effectiveness and as a biomarker of success. GSD-Ia can also serve as a model for other hepatic monogenic disorders.

[ADMINISTRATION OF ENTERAL NUTRITION. USE OF INFUSION PUMPS]. / Administración de nutrición enteral. USO DE BOMBAS DE INFUSIÓN.

Enteral nutrition (NE) is a technique of artificial nutrition that enables management by digestive tract of a defined mixture of nutrients and water, by means of probes implanted nasally or by enterostomies (eg: gastrostomy). Whenever the patient present limitations for voluntary oral ingestion or swallowing of the nutrients, and digestive capacity permitted to absorb nutrients, will draw the administration through a tube. Concern for the nutritional status of the patients is a more present reality among health professionals have demonstrated the direct relationship between malnutrition and morbidity and mortality of hospitalized patients. Enteral nutrition has become a useful procedure for the treatment of these patients, reducing their morbidity and mortality. The NE can be administered by infusion by gravity drip (less clinical use) pump and syringe (bolus), taking into account the speed of it, thus avoiding a large number of complications (usually due to too rapid administrations), so the method employed will be adjusted to the needs of each patient, whereas, the tolerance and its risk of aspiration. In this paper we will focus on the NE by infusion pump administration emphasizing the reduction of complications with this methodology against the administration by bolus (syringe).

Is prosodic development correlated with grammatical and lexical development? Evidence from emerging intonation in Catalan and Spanish.

This investigation focuses on the development of intonation patterns in four Catalan-speaking children and two Spanish-speaking children between 0 ; 11 and 2 ; 4. Pitch contours were prosodically analyzed within the Autosegmental Metrical framework in all meaningful utterances, for a total of 6558 utterances. The pragmatic meaning and communicative function were also assessed. Three main conclusions arise from the results. First, the study shows that the Autosegmental Metrical model can be successfully used to transcribe early intonation contours. Second, results reveal that children's emerging intonation is largely independent of grammatical development, and generally it develops well before the appearance of two-word combinations. As for the relationship between lexical and intonational development, the data show that the emergence of intonational grammar is related to the onset of speech and the presence of a small lexicon. Finally, we discuss the implications of these results for the biological hypothesis of intonational production.