The purpose of this study were 1) to determine the earliest pathological changes of germanium dioxide (GeO2)-induced myopathy; 2) to determine the pathomechanism of GeO2-induced myopathy; and 3) to determine the minimal dose of GeO2 to induce myopathy in rats. One hundred and twenty five male and female Sprague-Dawley rats, each weighing about 150 gm, were divided into seven groups according to daily doses of GeO2. Within each group, histopathological studies were done at 4, 8, 16, and 24 weeks of GeO2 administration. Characteristic mitochondrial myopathy was induced in the groups treated daily with 10 mg/kg of GeO2 or more. In conclusion, the results were as follows: 1) The earliest pathological change on electron microscope was the abnormalities of mitochondrial shape, size and increased number of mitochondria; 2) The earliest pathological change on light microscope was the presence of ragged red fibers which showed enhanced subsarcolemmal succinate dehydrogenase and cytochrome c oxidase reactivity; 3) GeO2 seemed to affect the mitochondrial oxidative metabolism of muscle fibers; 4) GeO2 could induce mitochondrial myopathy with 10 mg/kg of GeO2 for 4 weeks or less duration in rats.
Animal ; Cytochrome-c Oxidase/metabolism ; Female ; Germanium/toxicity* ; Histocytochemistry ; Male ; Mitochondrial Myopathies/pathology ; Mitochondrial Myopathies/enzymology ; Mitochondrial Myopathies/chemically induced* ; Muscles/ultrastructure ; Muscles/enzymology ; Rats ; Rats, Sprague-Dawley ; Succinate Dehydrogenase/metabolism

The persistence of muscle fiber number regardless of size reduction in muscle atrophy has not yet been fully explained. For the mechanism inherent in skeletal muscle tissues for preventing cellular death, the protective function of muscle tissue through transglutaminases has been tested, since the enzyme is responsible for structural stabilization and participates in signal transduction. In the present experiment, hindlimb suspension for two weeks caused a marked muscle atrophy in Wistar female rats. Comparison of muscle weight and histological analysis showed that suspension-induced atrophy in the hindlimb was more prominent in the soleus muscle, comprised mainly of type I fiber than that in the plantaris muscle of type II fibers. The immunohistochemical analysis with antitransglutaminase C antibody (anti TGase C Ab) showed that some atrophic bundles of soleus muscle were positively reacted with the antibody. The anti-TGase C Ab-reactive substances were observed to disappear significantly after endurance exercise, indicating their characteristic atrophy-dependency. The enzymatic analysis of transglutaminase showed the increase in activity in the atrophic soleus muscle tissue, compared with that in the normal or exercise-trained muscle tissues. From these results, the expression of TGase in the atrophic muscle is suggested to be the possible marker for muscle atrophy and its expression is probably related with the protective mechanism of the muscle tissue to prevent further cellular damage in the atrophic process.
Animal ; Atrophy ; Comparative Study ; Enzyme Induction ; Female ; Hindlimb ; Immobilization ; Muscle Fibers/pathology ; Muscle Proteins/*biosynthesis ; Muscles/*enzymology/pathology ; Physical Conditioning, Animal ; *Physical Endurance ; Rats ; Rats, Wistar ; Support, Non-U.S. Gov't ; Swimming ; Transglutaminases/*biosynthesis

OBJECTIVEGlycogen storage disease type III (GSD III) is an autosomal recessive disease caused by glycogen debranching enzyme (GDE) gene (AGL gene) mutation resulting in hepatomegaly, hypoglycemia, short stature and hyperlipidemia. GSD IIIA, involves both liver and muscle, and accounts for up to 80% of GSD III. The definitive diagnosis depends on either mutation analysis or liver and muscle glycogen debranching enzyme activity tests. This study aimed to establish enzymologic diagnostic method for GSD IIIA firstly in China by detecting muscular GDE activity, glycogen content and structure and to determine the normal range of muscular GDE activity, glycogen content and structure in Chinese children.

METHODMuscle samples were collected from normal controls (male 15, female 20; 12-78 years old), molecularly confirmed GSD III A patients (male 8, female 4, 2-27 years old) and other myopathy patients (male 9, 2-19 years old). Glycogen in the muscle homogenate was degraded into glucose by amyloglucosidase and phosphorylase respectively. The glycogen content and structure were identified by glucose yield determination. The debranching enzyme activity was determined using limit dextrin as substrate. Independent samples Kruskal-Wallis H test, Nemenyi-Wilcoxson-Wilcox test, and Chi-square test were used for statistical analyses by SPSS 11.5.

RESULT(1) GSD III A patients' glycogen content were higher, but G1P/G ratio and GDE activity were lower than those of the other two groups (P < 0.01). In all of the three parameters, there were no significant difference between normal controls and other myopathy patients. (2) The range of normal values: glycogen content 0.31%-0.43%, G1P/G ratio 22.37%- 26.43%, GDE activity 0.234-0.284 micromol/(g. min). (3) Enzymologic diagnostic method had a power similar to that of gene analysis in diagnosis of GSD-IIIA patients. The sensitivity and specificity of enzymologic diagnostic method and mutation detection were 91.7% and 100% respectively.

CONCLUSIONEnzymologic diagnostic method of GSD IIIA was firstly established in China. The range of normal values was determined. This method could be used in diagnosing suspected GSD IIIA patients in the clinic.

Adolescent ; Adult ; Aged ; Biopsy ; Case-Control Studies ; Child ; Child, Preschool ; China ; Female ; Glycogen ; analysis ; Glycogen Debranching Enzyme System ; analysis ; Glycogen Storage Disease Type III ; diagnosis ; enzymology ; pathology ; Humans ; Male ; Middle Aged ; Muscles ; chemistry ; pathology ; Young Adult