Biomedical subjects

Masahito Mihara

Publications and source records attributed to Masahito Mihara.

5 recordsLinked to original sources

PubMed2026

Multiancestry genome-wide association and multiomics analyses elucidate spatiocellular features of multiple sclerosis genetics.

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system characterized by demyelination disseminated in space and time. Here we performed a genome-wide association study (GWAS) using 688 MS cases and 205,199 controls from the Japanese population and identified significant associations in the major histocompatibility complex region and a population-specific risk variant in 11q24. Through cross-population GWAS meta-analyses using a total of 29,374 cases and 1,843,563 controls from 4 ancestral populations, we identified 22 novel susceptibility loci. Integration of GWAS and single-cell and single-nucleus RNA sequencing of peripheral blood mononuclear cells and subcortical lesions from patients with MS revealed enrichment of genetic risk factors for MS in CD4+ T helper cell lineage and regulatory T cells, as well as in endothelial cells. Furthermore, spatial transcriptomics of subcortical lesions demonstrated spatial and temporal heterogeneity in associations with MS genetic risk. Our study demonstrates the value of investigation of spatiocellular features of disease genetics across diverse populations and omics modalities.

Humans↗

PubMed2006

Frontal regions involved in learning of motor skill--A functional NIRS study.

To investigate cerebral mechanisms underlying learning of motor skill, we assessed serial changes of cortical activation patterns during a pursuit rotor (PR) task in 18 right-handed, healthy subjects using a functional near-infrared spectroscopy (fNIRS) system. Subjects performed the task with the right hand for 30 s alternated with 30-s rest for 8 repetitions (cycle1 to 8). Gains in motor skill were evaluated by time for keeping the stylus on the target (max 30 s), surface EMG patterns and trajectories of the arm. Performance improved with repetitions of the task cycles (12.9/17.1/19.3/20.0/21.1/22.2/23.6/23.9 s on average) and reached plateau at the 7th cycle. Reciprocal EMG patterns and steady trajectories were associated with acquisition of the motor skill. Task-related increases of oxygenated hemoglobin (oxyHb) were observed in the channels covering the sensorimotor cortex (SMC), premotor and prefrontal regions. There were also task-related decreases of deoxygenated hemoglobin (deoxyHb) in these areas although the changes were smaller compared with those of oxyHb. The center of task-related increases of oxyHb was initially located in the presupplementary motor area (preSMA) and shifted caudally to the supplementary motor area (SMA) with cycle repetitions. The ratios of oxyHb changes in preSMA to SMA significantly decreased with task repetitions. DeoxyHb changes confirmed the activation patterns. These data suggest that preSMA plays an important role in the early phase of motor learning while the SMA might be more involved in the late learning phase of the motor skill.

Adult↗

PubMed2006

Magnetic resonance spectroscopic study of Alzheimer's disease and frontotemporal dementia/Pick complex.

Disease-specific metabolic changes in Alzheimer's disease and frontotemporal dementia/Pick complex were examined by proton magnetic resonance spectroscopy at 3.0 T. Spectra were acquired from posterior and anterior cingulate cortices and the parieto-occipital and frontal white matter. This study included eight Alzheimer's disease patients, 10 frontotemporal dementia/Pick complex patients and 14 healthy volunteers. N-acetylaspartate/creatine+phosphocreatine ratio was reduced in the posterior cingulate cortex in the Alzheimer's disease and frontotemporal dementia/Pick complex patients. The Alzheimer's disease patients, however, showed a posterior dominant decrease, whereas the frontotemporal dementia/Pick complex patients showed a frontal predominant decrease. These different distributions of metabolic changes may represent the underlying pathological processes in each disease. Our standardized protocol of proton magnetic resonance spectroscopy measurement may be helpful in differentiating these dementia subtypes.

Aged↗

PubMed2006

The "cross" signs in patients with multiple system atrophy: a quantitative study.

Patients with multiple system atrophy (MSA) may show the "cross" sign in the pontine base that has been considered as an expression of the degeneration of pontine neurons and transverse pontocerebellar fibers. However, correlations between pontine base atrophy and existence of "cross" sign have not been fully investigated. The authors studied 68 patients with MSA (47 MSA-C [predominantly cerebellar ataxia], 21 MSA-P [predominantly parkinsonism], mean [+/-SD ] 58.7 +/- 10.9 years). T1-weighted (T1W) sagittal and axial images and T2-weighted (T2W) axial images were obtained for all patients and controls. To measure the areas of pontine basis and cerebellar vermis, the authors used midsagittal T1W images and analyzed a bit map transformed on a computer. They classified atrophy in the pontine base into 3 grades. There is significant correlation between atrophies of pontine base and existence of the cross sign. All patients with a smaller area of pontine base 2 standard deviations below those of normal controls had the cross sign. This supports that existence of the cross sign depends only on the extent of pontine base atrophies.

Adult↗

PubMed2004

A pitfall in MRI.

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