松浦 徹

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.

Fragile X-related tremor/ataxia syndrome (FXTAS) is a neurodegenerative disease caused by CGG triplet repeat expansions in FMR1, which elicit repeat-associated non-AUG (RAN) translation and produce the toxic protein FMRpolyG. We show that FMRpolyG interacts with pathogenic CGG repeat-derived RNA G-quadruplexes (CGG-G4RNA), propagates cell to cell, and induces neuronal dysfunction. The FMRpolyG polyglycine domain has a prion-like property, preferentially binding to CGG-G4RNA. Treatment with 5-aminolevulinic acid, which is metabolized to protoporphyrin IX, inhibited RAN translation of FMRpolyG and CGG-G4RNA-induced FMRpolyG aggregation, ameliorating aberrant synaptic plasticity and behavior in FXTAS model mice. Thus, we present a novel therapeutic strategy to target G4RNA prionoids.

Spastin, a microtubule-severing AAA ATPase, regulates microtubule dynamics and plays important roles in cell division and neurogenesis. Mutations in the spastin-coding gene SPAST lead to neurodegenerative disorders and cause spastic paraplegia type 4. Spastin has two main isoforms, M1 and M87, that differ only in the presence or absence of 86 N-terminal amino acids and have alternative splicing variants that lack exon4. The N-terminal region of M1 contains a hydrophobic domain, nuclear localization signal (NLS), and nuclear export signal (NES), which partly explains the differences in the two isoforms' localization. However, the mechanisms involved in regulating isoform localization, and the effects of localization on spastin functions are not fully understood. We found endogenous M1 and M87 shuttled between the nucleus and cytoplasm during the cell cycle. We identified a NES (amino acids 195-204) that spans the microtubule-interacting and endosomal-trafficking domain and exon4 region. Furthermore, the NES sequence contains both the coiled-coil and exon4 region of spastin isoforms. Highly conserved leucine 195 in exon3 and the two residues in exon4 are crucial for predicted coiled-coil formation. Mutations in NES or leptomycin B treatment reduced cytoplasmic localization and microtubule fragmentation in M87 rather than in M1. Phosphomimetic mutation of threonine 306 adjacent to the NLS (amino acids 309-312) inhibited nuclear transport of M87. Our results indicate that the newly identified NES in the spastin isoforms containing exon4 regulates the subcellular localization of spastin in coordination with NLS controlled by the phosphorylation state of spastin, and is involved in microtubule severing.

Vertical gaze palsy is rarely a neurological symptom, although it has been observed in some cases. Here, we report the case of a patient presenting with complete upward and downward gaze palsy. In this case, a small lesion in the left rostral midbrain was observed on diffusion-weighted magnetic resonance (MR) images, and the lesion was considered to cause the ocular symptom. We consider that vertical gaze palsy is an important clue to an accurate topical diagnosis of a brain lesion.

Although foam sclerotherapy to varicose veins is now a popular treatment because of its high efficacy and safety, some neurologic complications have recently been reported. Presently, the effectiveness and safety of intravenous recombinant tissue-type plasminogen activator therapy to stroke following foam sclerotherapy remain unclear. Here, we report the case of a 68-year-old woman whose ischemic symptoms following foam sclerotherapy were treated by intravenous recombinant tissue-type plasminogen activator. After she was admitted, the venous thrombosis in her right soleus vein and a patent foramen ovale causing the right-to-left shunt were revealed. Thus, we diagnosed the ischemic symptoms were due to paradoxical embolism following foam sclerotherapy. After intravenous recombinant tissue-type plasminogen activator therapy, there was no complication and the outcome was good. Our case suggests the effectiveness and the safety of intravenous recombinant tissue-type plasminogen activator therapy to paradoxical embolism following foam sclerotherapy.