Publications by authors named "Yuichi Riku"

Article Synopsis
  • Corticobasal degeneration (CBD) is a complex neurodegenerative disorder that requires pathological confirmation for an accurate diagnosis, and this study focused on Japanese patients to examine their clinical traits.
  • Out of 34 initially reviewed patients, 31 were analyzed, with a mean age of onset at 63.3 years and a median disease duration of 6 years; the most common clinical phenotype was progressive supranuclear palsy syndrome (PSPS), affecting 64.5% of participants.
  • The study highlighted that a significant number of patients (90.3%) experienced dysphagia early in the disease course, which is linked to reduced survival, while those receiving tube feeding had better survival rates compared to those who did not
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Prior to the formation of amyloid fibrils, the pathological hallmark in tau-related neurodegenerative disease, tau monomers aggregate into a diverse range of oligomers. Granular tau oligomers, consisting of approximately 40 tau protein molecules, are present in the prefrontal cortex of patients at Braak stages I-II, preclinical stages of Alzheimer's disease (AD). Antibodies to granular tau oligomers as antigens have not been reported.

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Aims: Corticobasal degeneration (CBD) is a rare neurodegenerative disorder. The status of the inferior olivary nucleus (ION) in CBD has been inadequately investigated. In this study, we conducted a pathological investigation of the ION in CBD.

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Introduction: Progressive supranuclear palsy (PSP) is characterized by pathology prominently in the basal ganglia, the tegmentum of the brainstem, and the frontal cortex. However, pathology varies according to clinical features. This study aimed to statistically verify the correspondence between the clinical and pathological subtypes of PSP.

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Multiple system atrophy (MSA) is an adult-onset neurodegenerative disorder that presents with variable combinations of autonomic dysfunction, cerebellar ataxia, parkinsonism, and pyramidal signs. The inferior olivary nucleus is targeted in MSA, with a phenotype of olivopontocerebellar atrophy in particular, and involvement of the olivocerebellar tract is well known. However, degeneration of the olivospinal tract has not been studied in MSA.

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The transactive response DNA-binding protein of 43 kDa (TDP-43) is a pathological protein of amyotrophic lateral sclerosis (ALS). TDP-43 pathology is characterized by a combination of the cytoplasmic aggregation and nuclear clearance of this protein. However, the mechanisms underlying TDP-43 pathology have not been fully clarified.

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Article Synopsis
  • The m. 3243A>G mutation is linked to mitochondrial diseases like MELAS, which lead to symptoms such as muscle weakness, brain dysfunction, and stroke-like episodes.
  • A study of six autopsied cases with the mutation revealed significant brain damage, especially in certain lobes, while the medial temporal lobe remained unaffected despite high mtDNA heteroplasmy.
  • Common neurological findings were inconsistent in mutant cases, suggesting distinct neuropathological markers, including unique changes in brain vessel structure and choroidal epithelial cells, which could aid in diagnosing mitochondrial disorders.
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Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder characterized by the degeneration of motor neurons. Although repeat expansion in C9orf72 is its most common cause, the pathogenesis of ALS isn't fully clear. In this study, we show that repeat expansion in LRP12, a causative variant of oculopharyngodistal myopathy type 1 (OPDM1), is a cause of ALS.

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The retinal pathology of genetically confirmed neuronal intranuclear inclusion disease (NIID) is yet unknown. We report the ocular findings in four NIID patients with NOTCH2NLC GGC repeat expansion to investigate the pathology of retinopathy. All four NIID patients were diagnosed by skin biopsy and NOTCH2NLC GGC repeat analysis.

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Transactivation response DNA binding protein 43 kDa (TDP-43) and tau are major pathological proteins of neurodegenerative disorders, of which neuronal and glial aggregates are pathological hallmarks. Interestingly, accumulating evidence from neuropathological studies has shown that comorbid TDP-43 pathology is observed in a subset of patients with tauopathies, and vice versa. The concomitant pathology often spreads in a disease-specific manner and has morphological characteristics in each primary disorder.

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Purpose: Intermittent claudication (IC) refers to leg pain that is induced by walking and relieved by rest. Neurogenic IC is usually associated with lumbar canal stenosis (LCS). We present rare findings from an autopsied patient who had neurogenic IC caused by vasculitis in the cauda equina.

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Progressive supranuclear palsy (PSP) can be diagnosed despite the presence of asymmetrical parkinsonism depending on the clinical diagnostic criteria. Some studies have reported that atrophy of the superior cerebellar peduncle (SCP) is more frequent in PSP than in Parkinson's disease. There have also been reports of PSP cases with an asymmetrically atrophic SCP.

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Article Synopsis
  • The neuropathological background of parkinsonism comprises several neurodegenerative disorders like Lewy body disease (LBD), multiple system atrophy (MSA), progressive supranuclear palsy (PSP), and corticobasal degeneration (CBD).
  • Macroscopic examination of the brain reveals distinct patterns, such as atrophy and discoloration, which guide further microscopic analysis essential for diagnosis based on the unique proteinopathies present in these conditions.
  • The review emphasizes the importance of these macroscopic clues and highlights the complexities involved in validating findings due to factors like disease duration and mixed pathologies.
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  • Researchers found that in progressive supranuclear palsy (PSP), a type of tauopathy, the role of filamin-A was crucial in promoting tau aggregation despite the absence of tau mutations.
  • They discovered that higher levels of filamin-A in PSP brains led to increased phosphorylation and insolubility of tau, possibly by interacting with actin filaments.
  • The study showed that reducing filamin-A levels corrected abnormal tau levels in cell cultures and that transgenic mice expressing human filamin-A exhibited tau pathology similar to that seen in PSP, suggesting filamin-A is a key player in the disease's progression.
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Neurolymphomatosis is a neurological manifestation of lymphoma that involves the cranial or spinal peripheral nerves, nerve roots, and plexus with direct invasion of neoplastic cells. Neurolymphomatosis is rare among patients with low-grade lymphoma. We report an autopsied case of neurolymphomatosis that arose from follicular lymphoma.

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Subacute sclerotic panencephalitis (SSPE) is a refractory neurological disorder after exposure to measles virus. Recently, SSPE cases have been treated with antiviral therapies, but data on the efficacy are inconclusive. Abnormal tau accumulation has been reported in the brain tissue of SSPE cases, but there are few reports in which this is amply discussed.

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TDP-43 is mislocalized from the nucleus and aggregates within the cytoplasm of affected neurons in cases of amyotrophic lateral sclerosis. TDP-43 pathology has also been found in brain tissues under non-amyotrophic lateral sclerosis conditions, suggesting mechanistic links between TDP-43-related amyotrophic lateral sclerosis and various neurological disorders. This study aimed to assess TDP-43 pathology in the spinal cord motor neurons of tauopathies.

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We report an autopsy case of multiple sclerosis (MS) manifesting as a long spinal cord lesion. The patient was a Japanese woman. At the age of 59 years, she presented with a one-month history of progressive paraplegia, dysesthesia in the lower extremities, and urinary retention.

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Objectives: Recent neuroimaging studies have indicated that the mesolimbic pathway, known to work as reward neuronal circuitry, regulates cognitive-behavioral flexibility in prolonged anorexia nervosa (AN). Although AN is associated with the highest mortality rate among psychiatric disorders, there have been few neuropathological studies on this topic. This study aims to identify alterations of the reward circuitry regions, especially in the nucleus accumbens (NAcc), using AN brain tissues.

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Amyotrophic lateral sclerosis (ALS) is a motor neuron disease that is clinically and pathologically characterized by impairment of the upper and lower motor neurons. The clinical diagnosis of ALS is not always straightforward because of the lack of specific biomarkers and clinical heterogeneity. This review presents the clinical and pathological findings of four autopsied cases that had been diagnosed with ALS before death.

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The hot cross bun (HCB) sign encompasses a cross-shaped hyperintensity area in the pons on axial T2-weighted magnetic resonance imaging (MRI). The HCB sign is characteristic of multiple system atrophy (MSA) and has occasionally been observed in other neurological disorders. Here, we report an autopsied case of corticobasal degeneration (CBD) that showed the HCB sign.

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Article Synopsis
  • The study investigates multiple system atrophy (MSA) patients with a specific focus on those showing significant pathological changes in the hippocampus, a region of the brain involved in memory.
  • Out of 146 autopsied MSA patients, 12 (8.2%) exhibited severe neuronal cytoplasmic inclusions (NCIs) in the hippocampus and associated areas, showing a distinct profile compared to the rest.
  • Notable findings include a higher number of affected women, longer disease duration, increased cognitive impairment, and distinctive NCI morphologies, indicating the need for further understanding of MSA variants linked to hippocampal pathology.
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