Enfermedad por almacenamiento de glucógeno de tipo III en pacientes colombianos: caracterización clínica y molecular / Molecular and clinical characterization of Colombian patients suffering from type III glycogen storage disease

Resumen Introducción. La enfermedad por almacenamiento de glucógeno de tipo III es una alteración autosómica recesiva, en la cual las mutaciones del gen AGL causan una deficiencia en la enzima desramificadora de glucógeno. Se caracteriza por hipoglucemia, hepatomegalia y miopatías progresivas. El análisis molecular del gen AGL ha evidenciado mutaciones que difieren según la población estudiada. En la actualidad, no existen reportes que describan mutaciones en el AGL de pacientes colombianos con esta condición. Objetivo. Describir las características clínicas y moleculares de diez pacientes colombianos con enfermedad por almacenamiento del glucógeno de tipo III. Materiales y métodos. Se analizaron diez pacientes pediátricos colombianos con la enfermedad y se hizo su estudio genético mediante la secuenciación de las regiones que codifican y las intrónicas circundantes del gen AGL con el método de Sanger. Resultados. Todos los pacientes tenían el fenotipo clásico de la enfermedad. El estudio genético reveló la mutación p.Arg910X en dos pacientes. Uno presentó la mutación p.Glu1072AspfsX36 y otro resultó heterocigoto compuesto con las mutaciones p.Arg910X y p.Glu1072AspfsX36. Asimismo, en tres pacientes se detectó la deleción de los exones 4, 5 y 6 del gen AGL. Los estudios de simulación computacional predijeron que estos defectos eran patogénicos. En tres pacientes no se encontraron mutaciones en las regiones amplificadas. Conclusión. Se encontraron mutaciones y deleciones que explican el fenotipo clínico de los pacientes. Este es el primer reporte en el que se describe el fenotipo clínico y el espectro de mutaciones en el gen AGL de pacientes colombianos, lo cual es importante para ofrecer un apropiado pronóstico, y asesoría genética al paciente y a su familia.

Abstract Introduction: Type III glycogen storage disease (GSD III) is an autosomal recessive disorder in which a mutation in the AGL gene causes deficiency of the glycogen debranching enzyme. The disease is characterized by fasting hypoglycemia, hepatomegaly and progressive myopathy. Molecular analyses of AGL have indicated heterogeneity depending on ethnic groups. The full spectrum of AGL mutations in Colombia remains unclear. Objective: To describe the clinical and molecular characteristics of ten Colombian patients diagnosed with GSD III. Materials and methods: We recruited ten Colombian children with a clinical and biochemical diagnosis of GSD III to undergo genetic testing. The full coding exons and the relevant exon-intron boundaries of the AGL underwent Sanger sequencing to identify mutation. Results: All patients had the classic phenotype of the GSD III. Genetic analysis revealed a mutation p.Arg910X in two patients. One patient had the mutation p.Glu1072AspfsX36, and one case showed a compound heterozygosity with p.Arg910X and p.Glu1072AspfsX36 mutations. We also detected the deletion of AGL gene 3, 4, 5, and 6 exons in three patients. The in silico studies predicted that these defects are pathogenic. No mutations were detected in the amplified regions in three patients. Conclusion: We found mutations and deletions that explain the clinical phenotype of GSDIII patients. This is the first report with a description of the clinical phenotype and the spectrum of AGLmutations in Colombian patients. This is importantto provide appropriate prognosis and genetic counseling to the patient and their relatives.

Skeletal Muscle Glycogen Breakdown According to Duration of Endurance Training / 대한스포츠의학회지

Endurance exercise training such as marathon can increase the ability of exercise performance. Muscle glycogen is associated with an exercise performance, because glycogen depletion is primary causes of muscle fatigue. This review summarizes the glycogen saving effect according to duration of endurance exercise training. Long-term endurance exercise-induced mitochondrial biogenesis contributes to glycogen saving effect that is reduced glycogen breakdown and lactate accumulation. Glycogen sparing is due to a smaller decrease in adenosine triphosphate and phosphocreatine and a smaller increase in inorganic phosphate in the working muscles. It takes required endurance exercise training for about 4 weeks or more. Single bout or short-term endurance exercise is not sufficient to bring an increase in functional mitochondria. But peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) increases rapidly after single bout of endurance exercise. PGC-1α downregulates glycogenolytic and glycolytic enzymes to reduce muscle glycogen breakdown and lactic acid accumulation after short-term endurance exercise.

Blood glucose regulation during fasting in rats under food restriction since birth

The effect of severe food restriction since birth on regulation of fasting glycemia in male Wistar rats was investigated. The control group (CG) had free supply of chow, while the restriction group (RG) received 50 percent of the amount ingested by the CG. The experiments were done in adult (60 days) overnight fasted rats in which glycemia, liver free glucose levels and hepatic glycogen concentration were measured. In part of the experiments in situ liver perfusion was done. The results showed that livers from the RG had higher glycogenolysis rates but lower gluconeogenesis rates from L-alanine (10 mM). Since RG showed maintained glycemia during fasting, it could be concluded that livers from RG produced glucose preferentially from glycogenolysis in detriment of gluconeogenesis. These findings demonstrated that in spite of severe caloric restriction, the metabolic adaptations of the liver did exist to assure the maintenance of blood glucose for brain supply during fasting.

AN EFFECTIVE HIGH-INTENSITY INTERMITTENT EXERCISE PROTOCOL FOR DECREASING SKELETAL MUSCLE GLYCOGEN / 体力科学

The decrease of muscle glycogen may be useful for the improvement of endurance performance. Intense anaerobic exercise requires a high rate of glycogen utilization, but consecutive intense anaerobic exercises induce a pronounced decline of external power and muscle glycogen consumption. We hypothesized that a long rest period between consecutive intense anaerobic exercises may aid in sustaining external power and glycogen consumption. Secondly, we hypothesized that active rest (AR) during the long resting period may be more effective than passive rest (PR).Six subjects performed four 30-second Wingate tests (WAnT) with a 4-minute recovery between each bout (Consecutive method). The subjects also performed a similar exercise procedure, but with a 30-minute seated resting period after the second bout (PR method).The other six male subjects performed four 30-second WAnTs with a 4-minute recovery between each bout, with 30-minutes of cycling at 40% VO₂max after the second bout (AR method). The subjects also performed PR method.The total work during the third and fourth bouts was greatest under the AR condition, followed by the PR condition, and finally the Consecutive method (p<0.05 for all comparisons). Blood lactate concentration during resting period was significantly lower, while muscle glycogen consumption was greater AR method than PR method (p<0.05 for both).A long resting period between consecutive intense anaerobic exercises may prevent the decline in external power and work. Additionally, AR has more favorable effects on muscle glycogen consumption, resulting in very low muscle glycogen levels, even with a small total amount of exercise.

Effects of different general anesthetics on serum hemolysis and hepatic and muscular glycogenolysis in rats

Anesthetics can affect the structure and biological function of tissues and systems differentially. The aim of the present study was to compare three injectable anesthetics generally used in experiments with animals in terms of the degree of hemolysis and glycogenolysis occurring after profound anesthesia. Twenty-four male Wistar rats (330-440 g) were divided into three groups (N = 8): chloral hydrate (CH), ketamine + xylazine (KX), Zoletil 50® (zolazepam and tiletamine) + xylazine (ZTX). After deep anesthesia, total blood was collected. The liver and white (WG) and red gastrocnemius (RG) muscles were also immediately removed. The degree of serum hemolysis was quantified on the basis of hemoglobin concentration (g/L). Hepatic and muscular glycogen concentrations (mmol/kg wet tissue) were quantified by the phenol-sulfuric method. The CH and KX groups exhibited serum hemolysis (4.0 ± 2.2 and 1.9 ± 0.9 g/L, respectively; P < 0.05) compared to the ZTX group, which presented none. Only KX induced elevated glycogenolysis (mmol/kg wet tissue) in the liver (86.9 ± 63.2) and in WG (18.7 ± 9.0) and RG (15.2 ± 7.2; P < 0.05). The CH and ZTX groups exhibited no glycogenolysis in the liver (164.4 ± 41.1 and 176.8 ± 54.4, respectively), WG (28.8 ± 4.4, 32.0 ± 6.5, respectively) or RG (29.0 ± 4.9; 25.3 ± 8.6, respectively). Our data indicate that ZTX seems to be an appropriate general anesthetic for studies that seek to simultaneously quantify the concentration of glycogen and serum biochemical markers without interferences. ZTX is reasonably priced, found easily at veterinary markets, quickly induces deep anesthesia, and presents a low mortality rate.

Uma compilação sobre glicogenose tipo I / A comprehensive review on glycogenosis type I

A glicose é um nutriente essencial para o organismo humano, sendo a principal fonte de energia para muitas células que dependem da circulação sangüínea, afim de suprir suas necessidades. Dessa forma, a presente revisão literária enfatizou a glicogenose tipo I, uma doença caracterizada pela deficiência da enzima glicose-6-fosfatase, responsável por catalisar a hidrólise de glicose-6-fosfato á glicose e fosfato, nas etapas finais tanto da gliconeogênese como da glicogenólise. Os estudos recentemente consentiram da necessidade do uso freqüente de altas taxas de amido nas refeições diárias, além de infusões intra-gástricas noturnas de líquidos contendo polímeros de glicose. Além disso, o presente trabalho também alerta as pessoas sobre o meticuloso cuidado sobre os pacientes portadores desta doença, afim de proporcionar uma melhor qualidade de vida para os mesmos, bem como evitar complicações e subseqüentes prognósticos.

Glucose is an essential nutrient for human organism, being the main source of energy for a lot of cells which depend on blood stream in order to supply their needs. Therefore, this literature review emphasized glycogenosis type I, a disease characterized by deficiency of the enzyme glucose-6-phospatase, responsible to catalyze the hydrolysis of glucose-6-phosphate into glucose and phosphate, in the final steps not only neoglucogenesis but also glycogenolysis. Recent studies revealed the need for recurrent use of high rates of starch in diary meals, beyond nocturnal intra-gastric infusions of liquids containing glucose polymers. Moreover, this study also alerts people with respect to the meticulous care to those patients in order to provide them a better life style and prevent complications and subsequent prognostics.

Glycogenolysis response to adrenergic agonists in the liver of rats treated with monosodium glutamate (MSG)

Administração de glutamato monossódico (MSG) em ratos neonatos causa lesão no núcleo arqueado (NA), seguido por uma síndrome de disfunção neuroendócrina caracterizada por obesidade e reduzida atividade simpática. O objetivo da presente investigação foi examinar a resposta da glicogenólise hepática a agonistas adrenérgico em ratos tratados com MSG. Ratos Wistar machos receberam injeções subcutâneas de MSG (4 mg g-1 de peso corporal) ou salina equimolar (controles) durante cinco dias após o nascimento. Noventa dias após o tratamento, os fígados de ratos-MSG ou controles foram perfundidos in situ com epinefrina e agonistas alfa- e beta-adrenérgico. Isoproterenol, fenilefrina e epinefrina aumentaram a glicogenólise em ratos-MSG, comparados aos controles (50 ± 2,8 Vs 17 ± 0,89 µmol min-1 g-1 de fígado, p < 0,0001; 64 ± 0,15 Vs 37 ± 0,39, p < 0,0001; 35 ± 2,48 Vs 27 ± 0,98, p < 0,05, respectivamente). Concluiu-se que a lesão do NA aumentou o catabolismo do glicogênio aos agonistas adrenérgicos, possivelmente devido à reduzida atividade do eixo simpático - medula adrenal.

Administration of MSG to neonate rats causes lesions in the arcuate nucleus (AN), followed by a syndrome of neuroendocrine dysfunction characterized by obesity and decreased sympathetic activity. The aim of the present investigation was to examine the responses of hepatic glycogenolysis to alpha and beta-adrenergic agonists in rats? treatment with MSG. Male Wistar rats received subcutaneous injections of MSG (4 mg g-1 body weight) or hyperosmotic saline (controls) during five days after birth. Ninety days after treatment, the livers of the MSG or controls rats were perfused in situ with epinephryne and alpha- and beta-adrenergic agonists. Epinephryne, Isoproterenol and phenylephrine increased glycogenolysis in the MSG-treated rats, compared to the controls (50 ± 2.8 Vs 17 ± 0.89 µmol min-1 g-1 of liver, p < 0.0001; 64 ± 0.15 Vs 37 ± 0.39, p < 0.0001; 35 ± 2.48 Vs 27 ± 0.98, p < 0.05, respectively). Results indicated that the lesion in the AN increased glycogen catabolism to adrenergic agonists, possibly, due to the reduced activity of the sympathetic-adrenal axis.