The restriction endonuclease SmaI has been used for the diagnosis of neurogenic muscle weakness, ataxia and retinitis pigmentosa disease or Leigh’s disease, caused by the Mt8993T→G mutation which results in a Leu156Arg replacement that blocks proton translocation activity of subunit a of F₀F₁-ATPase. Our ultimate goal is to apply SmaI to gene therapy for this disease, because the mutant mitochondrial DNA (mtDNA) coexists with the wild-type mtDNA (heteroplasmy), and because only the mutant mtDNA, but not the wild-type mtDNA, is selectively restricted by the enzyme. For this purpose, we transiently expressed the SmaI gene fused to a mitochondrial targeting sequence in cybrids carrying the mutant mtDNA. Here, we demonstrate that mitochondria targeted by the SmaI enzyme showed specific elimination of the mutant mtDNA. This elimination was followed with repopulation by the wild-type mtDNA, resulting in restoration of both the normal intracellular ATP level and normal mitochondrial membrane potential. Furthermore, in vivo electroporation of the plasmids expressing mitochondrion-targeted EcoRI induced a decrease in cytochrome c oxidase activity in hamster skeletal muscles while causing no degenerative changes in nuclei. Delivery of restriction enzymes into mitochondria is a novel strategy for gene therapy of a special form of mitochondrial diseases.

Four mutations (C1939G, G3370T, 3746delG, and 4870delT) are relatively more prevalent in this population, accounting for 60% of the mutations in this study. This study revealed that the G3370T mutation was associated with milder forms of MM and the G3510A mutation was associated with a more severe form.

Objective and methodsDysferlin encoded by DYSF deficiency leads to two main phenotypes, limb girdle muscular dystrophy (LGMD) 2B and Miyoshi myopathy. To reveal in detail the mutational and clinical features of LGMD2B in Japan, we observed 40 Japanese patients in 36 families with LGMD2B in whom dysferlin mutations were confirmed.Results and conclusionsThree mutations (c.1566C>G, c.2997G>T and c.4497delT) were relatively more prevalent. The c.2997G>T mutation was associated with late onset, proximal dominant forms of dysferlinopathy, a high probability that muscle weakness started in an upper limb and lower serum creatine kinase (CK) levels. The clinical features of LGMD2B are as follows: (1) onset in the late teens or early adulthood, except patients homozygous for the c.2997G>T mutation; (2) lower limb weakness at onset; (3) distal change of lower limbs on muscle CT at an early stage; (4) impairment of lumbar erector spinal muscles on muscle CT at an early stage; (5) predominant involvement of proximal upper limbs; (6) preservation of function of the hands at late stage; (7) preservation of strength in neck muscles at late stage; (8) lack of facial weakness or dysphagia; (9) avoidance of scoliosis; (10) hyper-Ckaemia; (11) preservation of cardiac function; and (12) a tendency for respiratory function to decline with disease duration. It is important that the late onset phenotype is found with prevalent mutations.

BackgroundMolecular hydrogen has prominent effects on more than 30 animal models especially of oxidative stress-mediated diseases and inflammatory diseases. In addition, hydrogen effects on humans have been reported in diabetes mellitus type 2, hemodialysis, metabolic syndrome, radiotherapy for liver cancer, and brain stem infarction. Hydrogen effects are ascribed to specific radical-scavenging activities that eliminate hydroxyl radical and peroxynitrite, and also to signal-modulating activities, but the detailed molecular mechanisms still remain elusive. Hydrogen is a safe molecule that is largely produced by intestinal bacteria in rodents and humans, and no adverse effects have been documented.MethodsWe performed open-label trial of drinking 1.0 liter per day of hydrogen-enriched water for 12 weeks in five patients with progressive muscular dystrophy (PMD), four patients with polymyositis/dermatomyositis (PM/DM), and five patients with mitochondrial myopathies (MM), and measured 18 serum parameters as well as urinary 8-isoprostane every 4 weeks. We next conducted randomized, double-blind, placebo-controlled, crossover trial of 0.5 liter per day of hydrogen-enriched water or placebo water for 8 weeks in 10 patients with DM and 12 patients with MM, and measured 18 serum parameters every 4 weeks.ResultsIn the open-label trial, no objective improvement or worsening of clinical symptoms was observed. We, however, observed significant effects in lactate-to-pyruvate ratios in PMD and MM, fasting blood glucose in PMD, serum matrix metalloproteinase-3 (MMP3) in PM/DM, and serum triglycerides in PM/DM. In the double-blind trial, no objective clinical effects were observed, but a significant improvement was detected in lactate in MM. Lactate-to-pyruvate ratios in MM and MMP3 in DM also exhibited favorable responses but without statistical significance. No adverse effect was observed in either trial except for hypoglycemic episodes in an insulin-treated MELAS patient, which subsided by reducing the insulin dose.ConclusionsHydrogen-enriched water improves mitochondrial dysfunction in MM and inflammatory processes in PM/DM. Less prominent effects with the double-blind trial compared to the open-label trial were likely due to a lower amount of administered hydrogen and a shorter observation period, which implies a threshold effect or a dose-response effect of hydrogen.

The restriction endonuclease Sinai has been used for the diagnosis of neurogenic muscle weakness, ataxia and retinitis pigmentosa disease or Leigh's disease, caused by the Mt8993T~G mutation which results in a Leu156Arg replacement that blocks proton translocation activity of subunit a of FoF1-ATPase. Our ultimate goal is to apply Sinai to gene therapy for this disease, because the mutant mitochondrial DNA (mtDNA) coexists with KARG E P~Fax+41 61 306 12 34 E-Mail karger@karger.ch w-~.~.karger, corn