[Therapeutics for Mitochondrial Encephalomyopathy].

In MELAS, taurine modification defect in the anticodon of mitochondrial leucine tRNA causes codon translation failure. An investigator-started clinical trials of high-dose taurine therapy, that showed its efficacy in preventing stroke-like episodes, and improving the taurine modification rate. The drug was found to be safe. Taurine has been approved as a drug covered by public insurance for prevention of stroke-like episodes since 2019. Recently, L-arginine hydrochloride has also been approved for off-label use as a treatment for both acute and intermittent stages of stroke-like episodes.

Circulating α-Klotho Counteracts Transforming Growth Factor-ß-Induced Sarcopenia.

α-Klotho is a longevity-related protein. Its deficiency shortens lifespan with prominent senescent phenotypes, including muscle atrophy and weakness in mice. α-Klotho has two forms: membrane α-Klotho and circulating α-Klotho (c-α-Klotho). Loss of membrane α-Klotho impairs a phosphaturic effect, thereby accelerating phosphate-induced aging. However, the mechanisms of senescence on c-α-Klotho loss remain largely unknown. Herein, with the aging of wild-type mice, c-α-Klotho declined, whereas Smad2, an intracellular transforming growth factor (TGF)-ß effector, became activated in skeletal muscle. Moreover, c-α-Klotho suppressed muscle-wasting TGF-ß molecules, including myostatin, growth and differentiation factor 11, activin, and TGF-ß1, through binding to ligands as well as type I and type II serine/threonine kinase receptors. Indeed, c-α-Klotho reversed impaired in vitro myogenesis caused by these TGF-ßs. Oral administration of Ki26894, a small-molecule inhibitor of type I receptors for these TGF-ßs, restored muscle atrophy and weakness in α-Klotho (-/-) mice and in elderly wild-type mice by suppression of activated Smad2 and up-regulated Cdkn1a (p21) transcript, a target of phosphorylated Smad2. Ki26894 also induced the slow to fast myofiber switch. These findings show c-α-Klotho's potential as a circulating inhibitor counteracting TGF-ß-induced sarcopenia. These data highlight the potential of a novel therapy involving TGF-ß blockade to prevent sarcopenia.

Human transthyretin gene expression is markedly increased in repair Schwann cells in an in vitro model of hereditary transthyretin amyloidosis.

Hereditary transthyretin (TTR) amyloidosis (ATTRv) is characterized by TTR amyloid deposition in the peripheral nervous system. It remains unknown why variant TTR preferentially deposits in the peripheral nerves and dorsal root ganglia. We previously detected low levels of TTR expression in Schwann cells and established an immortalized Schwann cell line, TgS1, derived from a mouse model of ATTRv amyloidosis expressing the variant TTR gene. In the present study, the expression of TTR and Schwann cell marker genes was investigated in TgS1 cells by quantitative RT-PCR. TTR gene expression was markedly upregulated in TgS1 cells incubated in non-growth medium-Dulbecco's modified Eagle's medium supplemented with 10% fetal bovine serum. The expression levels of c-Jun, Gdnf and Sox2 were increased, while Mpz was downregulated, suggesting that TgS1 cells exhibit a repair Schwann cell-like phenotype in the non-growth medium. Western blot analysis revealed that TTR protein was produced and secreted by the TgS1 cells. Furthermore, downregulation of Hsf1 with siRNA induced TTR aggregates in the TgS1 cells. These findings indicate that TTR expression is markedly increased in repair Schwann cells, likely to promote axonal regeneration. Therefore, aged dysfunctional repair Schwann cells may cause the deposition of variant TTR aggregates in the nerves of patients with ATTRv.

Alterations of ATG4A and LC3B in neurons derived from Alzheimer's disease patients.

We investigated the alterations in autophagy-related molecules in neurons differentiated from induced pluripotent stem cells obtained from patients with Alzheimer's disease (AD). Consistent with our previous microarray data, ATG4A protein was upregulated in the neurons derived from a familial AD patient with an APP-E693Δ mutation who showed accumulation of intracellular amyloid ß peptide (Aß). This upregulation was reversed by inhibiting Aß production, suggesting that the intracellular Aß may be responsible for the upregulation of ATG4A. The LC3B-II/LC3B-I ratio, an index of autophagosome formation, was lower in the neurons derived from the AD patient with APP-E693Δ as well as the neurons derived from other familial and sporadic AD patients. These findings indicate that dysregulation of autophagy-related molecules may accelerate the pathogenesis of AD.

Becker Muscular Dystrophy Accompanied by Anti-HMGCR Antibody-positive Immune-mediated Necrotizing Myopathy.

Becker muscular dystrophy (BMD) is an X-linked neuromuscular disease characterized by progressive muscle weakness that currently has no cure. Immune-mediated necrotizing myopathy (IMNM) is a type of autoimmune inflammatory myopathy characterized by proximal muscle weakness that is treated with immunosuppressive therapy. We herein report a patient diagnosed with BMD complicated with IMNM by a pathological analysis. Notably, the patient had an elevated serum anti-3-hydroxy-3-methylglutaryl-coenzyme A reductase antibody level. Oral glucocorticoid and methotrexate treatment partially improved the muscle weakness with decreased levels of serum creatine kinase. An accurate diagnosis is important for therapeutic decisions in these complicated cases.

Caveolin 3 suppresses phosphorylation-dependent activation of sarcolemmal nNOS.

Mutations of the caveolin 3 gene cause autosomal dominant limb-girdle muscular dystrophy (LGMD)1C. In mice, overexpression of mutant caveolin 3 leads to loss of caveolin 3 and results in myofiber hypotrophy in association with activation of neuronal nitric oxide synthase (nNOS) at the sarcolemma. Here, we show that caveolin 3 directly bound to nNOS and suppressed its phosphorylation-dependent activation at a specific residue, Ser1412 in the nicotinamide adenine dinucleotide phosphate (NADPH)-flavin adenine dinucleotide (FAD) module near the C-terminus of the reduction domain, in vitro. Constitutively active nNOS enhanced myoblast fusion, but not myogenesis, in vitro. Phosphorylation-dependent activation of nNOS occurred in muscles from caveolin 3-mutant mice and LGMD1C patients. Mating with nNOS-mutant mice exacerbated myofiber hypotrophy in the caveolin 3-mutant mice. In nNOS-mutant mice, regenerating myofibers after cardiotoxin injury became hypotrophic with reduced myoblast fusion. Administration of NO donor increased myofiber size and the number of myonuclei in the caveolin 3-mutant mice. Exercise also increased myofiber size accompanied by phosphorylation-dependent activation of nNOS in wild-type and caveolin 3-mutant mice. These data indicate that caveolin 3 inhibits phosphorylation-dependent activation of nNOS, which leads to myofiber hypertrophy via enhancing myoblast fusion. Hypertrophic signaling by nNOS phosphorylation could act in a compensatory manner in caveolin 3-deficient muscles.

Magnetic resonance imaging of dorsal root ganglion in a pre-symptomatic subject with familial amyloid polyneuropathy transthyretin E61K.

We recently reported evidence of transthyretin (TTR) familial amyloid polyneuropathy (TTR FAP) associated with TTR E61K, which is characterized by late-onset sensory dominant polyneuropathy, autonomic disturbances, and cardiomyopathy. In those TTR FAP patients, no amyloid deposits were observed in the endoneurium of examined sural nerves. Furthermore, the amyloidogenicity of E61K TTR was similar to that of wild-type TTR in vitro. Thus, we speculated that dorsal root ganglia (DRGs) may be the initial sites for the lesions in amyloid neuropathy because there is no blood-nerve barrier. In the present study, lumbar magnetic resonance imaging was performed to evaluate the DRGs in pre-symptomatic TTR E61K and V30M subjects. Magnetic resonance imaging (3 T) was used for three-dimensional T2-weighted imaging (coronal sections; slice thickness, 2 mm), and the DRG volumes were measured. The mean volumes of the bilateral L3, L4, and S1 DRGs in the pre-symptomatic TTR E61K subject were larger than those for the pre-symptomatic TTR V30M subject and five control patients. The mean volumes of the bilateral L4 to S1 DRGs in the pre-symptomatic TTR V30M subject were similar to those in control patients. A number of lumbar DRGs were enlarged in the pre-asymptomatic TTR E61K subject, suggesting that DRGs may be the sites of the initial lesions in the peripheral nervous system of this FAP.

A novel method to measure sensory nerve conduction of the posterior antebrachial cutaneous nerve.

INTRODUCTION/AIMS: Posterior antebrachial cutaneous (PABC) nerve conduction studies could be useful for distinguishing PABC neuropathy from C7 radiculopathy. In the conventional method using an antidromic method, the sensory nerve action potential (SNAP) is sometimes followed by a large volume-conducted motor potential. In this report we describe a reliable nerve conduction study using an orthodromic method for recording SNAPs of the PABC nerve. METHODS: Thirty-six healthy volunteers participated in this study. PABC SNAPs were recorded by placing a surface-active electrode 2 cm anterior to the lateral epicondyle. The PABC nerve was stimulated 10 cm distal to the active recording electrode along a line from the recording point to the mid-dorsum of the wrist, midway between the radial and ulnar styloid processes. We also performed PABC nerve conduction studies using an antidromic method and compared the findings. RESULTS: PABC SNAPs were recorded bilaterally from all subjects. The mean peak-to-peak amplitude for SNAPs was 13.4 ± 4.8 µV. Mean maximum conduction velocity was 62.7 ± 3.9 m/s and mean negative peak conduction velocity was 51.2 ± 2.6 m/s. The mean side-to-side difference in amplitude was 22.1 ± 16.0%. The mean amplitude of SNAPs obtained by our method was 48.9% higher than that of SNAPs obtained by the conventional method (13.4 vs 9.0 µV; P < .001). In contrast to the conventional method, our method enabled SNAPs to be recorded without a volume-conducted motor potential. DISCUSSION: The higher mean amplitude of SNAPs with our method enables them to be obtained easily.

Maximal Multistage Shuttle Run Test-induced Myalgia in a Patient with Muscle Phosphorylase B Kinase Deficiency.

Muscle phosphorylase b kinase (PHK) deficiency is a rare mild metabolic disorder caused by mutations of the PHKA1 gene encoding the αM subunit of PHK. A 16-year-old boy experienced myalgia during the maximal multistage 20-m shuttle run test targeting the maximal oxygen consumption. Although an ischemic forearm exercise test was normal, a muscle biopsy revealed subsarcolemmal glycogen accumulation. He harbored a novel insertion mutation in the PHKA1 gene that resulted in premature termination of the αM subunit close to the C-terminus. Compared with previously reported cases, his reduction in PHK activity was relatively mild.

A Novel PRPS1 Mutation in a Japanese Patient with CMTX5.

The PRPS1 gene encodes phosphoribosyl pyrophosphate synthetase 1 (PRS-1). The phenotypes associated with PRPS1 mutations include DFN2 (mild PRS-1 deficiency), X-linked Charcot-Marie-Tooth disease type 5 (CMTX5) (moderate PRS-1 deficiency), Arts syndrome (severe PRS-1 deficiency), and PRS-1 superactivity1. CMTX5 is a very rare hereditary neuropathy characterized by deafness, optic atrophy, and polyneuropathy. We herein report a Japanese patient with CMTX5 who had a novel hemizygous mutation c.82 G>C in PRPS1. Despite showing a typical clinical picture, the decrease in enzyme activity measured in the patient's erythrocytes was milder than in previously reported cases.

A web-based questionnaire survey on the influence of coronavirus disease-19 on the care of patients with muscular dystrophy.

To clarify the influence of coronavirus disease-19 (COVID-19) on the care of muscular dystrophy patients, we performed a questionnaire survey that was posted on the internet on May 11, 2020. By the end of July 2020, 542 responses had been collected. Approximately 30% of patients postponed regular consultations, and one-quarter of patients who received consultation more than once a month used telephone consultations. Two of 84 patients with Duchenne muscular dystrophy had reduced their steroid doses. A shortage of ventilator accessories and infection protection equipment occurred following the onset of COVID-19, and this shortage had a serious impact on medical care and infection prevention measures. Reductions in rehabilitation and other services, and avoidance of outings, led to a decrease in exercise and an increase in caregiver burden. Inpatients were restricted from going out and visiting family members. More than 20% of patients reported physical or mental complaints; however, few required treatment. COVID-19 has seriously affected the activities and quality of life of patients with muscular dystrophy. We will continue this survey and analyze the longitudinal changes.

Repurposing bromocriptine for Aß metabolism in Alzheimer's disease (REBRAnD) study: randomised placebo-controlled double-blind comparative trial and open-label extension trial to investigate the safety and efficacy of bromocriptine in Alzheimer's disease with presenilin 1 (PSEN1) mutations.

INTRODUCTION: Alzheimer's disease (AD) is one of the most common causes of dementia. Pathogenic variants in the presenilin 1 (PSEN1) gene are the most frequent cause of early-onset AD. Medications for patients with AD bearing PSEN1 mutation (PSEN1-AD) are limited to symptomatic therapies and no established radical treatments are available. Induced pluripotent stem cell (iPSC)-based drug repurposing identified bromocriptine as a therapeutic candidate for PSEN1-AD. In this study, we used an enrichment strategy with iPSCs to select the study population, and we will investigate the safety and efficacy of an orally administered dose of bromocriptine in patients with PSEN1-AD. METHODS AND ANALYSIS: This is a multicentre, randomised, placebo-controlled trial. AD patients with PSEN1 mutations and a Mini Mental State Examination-Japanese score of ≤25 will be randomly assigned, at a 2:1 ratio, to the trial drug or placebo group (≥4 patients in TW-012R and ≥2 patients in placebo). This clinical trial consists of a screening period, double-blind phase (9 months) and extension phase (3 months). The double-blind phase for evaluating the efficacy and safety is composed of the low-dose maintenance period (10 mg/day), high-dose maintenance period (22.5 mg/day) and tapering period of the trial drug. Additionally, there is an open-labelled active drug extension period for evaluating long-term safety. Primary outcomes are safety and efficacy in cognitive and psychological function. Also, exploratory investigations for the efficacy of bromocriptine by neurological scores and biomarkers will be conducted. ETHICS AND DISSEMINATION: The proposed trial is conducted according to the Declaration of Helsinki, and was approved by the Institutional Review Board (K070). The study results are expected to be disseminated at international or national conferences and published in international journals following the peer-review process. TRIAL REGISTRATION NUMBER: jRCT2041200008, NCT04413344.

Effect of Neurofeedback Facilitation on Poststroke Gait and Balance Recovery: A Randomized Controlled Trial.

OBJECTIVE: To test the hypothesis that supplementary motor area (SMA) facilitation with functional near-infrared spectroscopy-mediated neurofeedback (fNIRS-NFB) augments poststroke gait and balance recovery, we conducted a 2-center, double-blind, randomized controlled trial involving 54 Japanese patients using the 3-meter Timed Up and Go (TUG) test. METHODS: Patients with subcortical stroke-induced mild to moderate gait disturbance more than 12 weeks from onset underwent 6 sessions of SMA neurofeedback facilitation during gait- and balance-related motor imagery using fNIRS-NFB. Participants were randomly allocated to intervention (28 patients) or placebo (sham: 26 patients). In the intervention group, the fNIRS signal contained participants' cortical activation information. The primary outcome was TUG improvement 4 weeks postintervention. RESULTS: The intervention group showed greater improvement in the TUG test (12.84 ± 15.07 seconds, 95% confidence interval 7.00-18.68) than the sham group (5.51 ± 7.64 seconds, 95% confidence interval 2.43-8.60; group difference 7.33 seconds, 95% CI 0.83-13.83; p = 0.028), even after adjusting for covariates (group × time interaction; F 1.23,61.69 = 4.50, p = 0.030, partial η2 = 0.083). Only the intervention group showed significantly increased imagery-related SMA activation and enhancement of resting-state connectivity between SMA and ventrolateral premotor area. Adverse effects associated with fNIRS-mediated neurofeedback intervention were absent. CONCLUSION: SMA facilitation during motor imagery using fNIRS neurofeedback may augment poststroke gait and balance recovery by modulating the SMA and its related network. CLASSIFICATION OF EVIDENCE: This study provides Class III evidence that for patients with gait disturbance from subcortical stroke, SMA neurofeedback facilitation improves TUG time (UMIN000010723 at UMIN-CTR; umin.ac.jp/english/).

Anatomical variations of the superficial branch of the radial nerve and the dorsal branch of the ulnar nerve: A detailed electrophysiological study.

INTRODUCTION: In this study we evaluated anatomic variations of the superficial branch of the radial nerve (SBRN) and the dorsal branch of the ulnar nerve (DBUN) electrophysiologically. METHODS: Antidromic nerve conduction studies (NCS) of the SBRN and DBUN were performed on healthy individuals. To identify individual responses from the distal branches of the SBRN and DBUN, sensory nerve action potentials of each finger (lateral side/medial side) were recorded. RESULTS: NCS were performed in 50 hands of 27 healthy control subjects. The thumb and the index finger were supplied by the SBRN in all cases. The lateral and medial sides of the third finger were supplied by the SBRN in 94.0% and 74.0% of the cases, but the lateral and medial sides of the fourth finger were supplied by the SBRN in only 10.0% and 2.0% of cases. The fifth finger and the medial side of the fourth finger were always supplied by the DBUN. The lateral side of the fourth finger was supplied by the DBUN in 98.0% of cases, but the lateral and medial sides of the third finger were supplied by the DBUN in 40.0% and 70.0% of cases. Dual innervation by the SBRN and DBUN was found in 34.0% and 46.0% of the lateral and medial sides of the third finger, but in only 8.0% and 2.0% of the lateral and medial sides of the fourth finger. DISCUSSION: There are considerable anatomic variations of the SBRN and DBUN in healthy individuals.

A low amyloidogenic E61K transthyretin mutation may cause familial amyloid polyneuropathy.

Patients with transthyretin (TTR)-type familial amyloid polyneuropathy (FAP) typically exhibit sensory dominant polyneuropathy and autonomic neuropathy. However, the molecular pathogenesis of the neuropathy remains unclear. In this study, we characterize the features of FAP TTR the substitution of lysine for glutamic acid at position 61 (E61K). This FAP was late-onset, with sensory dominant polyneuropathy, autonomic neuropathy, and cardiac amyloidosis. Interestingly, no amyloid deposits were found in the endoneurium of the four nerve specimens examined. Therefore, we examined the amyloidogenic properties of E61K TTR in vitro. Recombinant wild-type TTR, the substitution of methionine for valine at position 30 (V30M) TTR, and E61K TTR proteins were incubated at 37°C for 72 hr, and amyloid fibril formation was assessed using the thioflavin-T binding assay. Amyloid fibril formation by E61K TTR was less than that by V30M TTR, and similar to that by wild-type TTR. E61K TTR did not have an inhibitory effect on neurite outgrowth from adult rat dorsal root ganglion (DRG) neurons, but V30M TTR did. Furthermore, we studied the sural nerve of our patient by terminal deoxynucleotidyl transferase dUTP nick end labeling and electron microscopy. A number of apoptotic cells were observed in the endoneurium of the nerve by transferase dUTP nick end labeling. Chromatin condensation was confirmed in the nucleus of non-myelinating Schwann cells by electron microscopy. These findings suggest that E61K TTR is low amyloidogenic, in vitro and in vivo. However, TTR aggregates and amyloid fibrils in the DRG may cause sensory impairments in FAP because the DRG has no blood-nerve barrier. Moreover, Schwann cell apoptosis may contribute to the neurodegeneration.

Relationship between the Diabetic Polyneuropathy Index and the Neurological Findings of Diabetic Polyneuropathy.

Objective To achieve an accurate quantification in diabetic polyneuropathy (DPN), we developed a new electrophysiological index that we called the DPN index. The relationship between the DPN index and the neurological findings in diabetic patients was assessed. Methods The DPN index was calculated by the mean value of percentages of four parameters (tibial compound muscle action potential amplitude / F wave minimum latency, sural sensory nerve action potential amplitude / sensory nerve conduction velocity) against the mean normal values. Twenty healthy subjects were recruited as a control group. Patients A total of 348 diabetic patients who were hospitalized in our hospital during the period from December 2016 to August 2019 were retrospectively studied. The correlations between the DPN index and five neurological findings (subjective sensory symptoms, diminished or absent Achilles tendon reflex, impaired tactile and vibration sense, low coefficient of variation of R-R interval) were evaluated. Results The DPN index in healthy subjects was 129.3±32.7%. The DPN index in diabetic patients with one or more neurological findings was significantly lower than that in diabetic patients without any neurological findings (p<0.01: 89.3±27.8% vs. 118.4±21.2%). For each of the five neurological findings, the DPN index in the group with an abnormality was significantly lower than that in the group without any abnormality (each p<0.01). Spearman's correlation coefficients indicated that a greater number of neurological findings resulted in a lower DPN index (r=-0.711, p<0.01). Conclusion Our study suggested that the DPN index is useful for evaluating the severity of DPN.

[Study of care practices for patients with myotonic dystrophy in Japan-Nationwide patient survey].

We conducted a comprehensive anonymous questionnaire survey on medical care and treatment for patients with myotonic dystrophy, who registered in the Japanese national registry (Remudy) or were undergoing care in seven hospitals specializing neuromuscular diseases. The questionnaire consisted of 49 questions were distributed to 813 patients, and 342 valid responses were collected. Most prevalent symptoms or complaints were dysfunction of fingers and fatigue. One-third of the adult patients left the job, half of which was due to the disease. Twelve percent of the patients did not visit the specialist regularly, the main reason being distance. The most common reason that the patients did not follow the advice of using a ventilator by medical professionals was lack of feeling the need. One-fourth of the adult female patients had infertility treatment, 80% of which was before a diagnosis of this disorder. This first-time nationwide survey revealed the actual condition of Japanese patients with myotonic dystrophy and raised various care-related issues.

Schwann Cell and the Pathogenesis of Charcot-Marie-Tooth Disease.

Charcot-Marie-Tooth (CMT) disease is the most common hereditary neuropathy and genetically heterogeneous. CMT1 and CMTX are autosomal dominant and X-linked demyelinating neuropathies, respectively. CMT1A, CMT1B, and CMTX1 are the common forms of CMT, which are attributed to the genes encoding the myelin or gap junction proteins expressed in the myelinating Schwann cells. CMT4 is a rare autosomal recessive demyelinating neuropathy that usually shows an early-onset severe phenotype. Twelve genes have been described as CMT4, which encodes many kinds of proteins including mitochondrial proteins, phosphatases in the endosomal pathway, endocytic recycling proteins, and trafficking proteins. The genes responsible for CMT4 are expressed in Schwan cells and necessary for the development and maintenance in the peripheral nervous system. However, CMT1, CMT4, and CMTX1 are primarily demyelinating neuropathies, axonal degeneration is necessary for symptoms to develop. Schwann cell-axon interactions are impaired in the pathogenesis of demyelinating CMT.