Publications by authors named "Keiichi Ishikawa"

Sleep bruxism (SB) involves involuntary jaw movements during sleep and is potentially caused by motor neuronal hyperexcitability and GABAergic system dysfunction. However, the molecular basis remains unclear. In this study, we aimed to investigate changes in the expression of several genes associated with the pathophysiology of SB.

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  • Lewy body diseases, including Parkinson's disease, involve the spread of a protein called alpha-synuclein (αSyn) between neurons, making it important to study for treatment development.
  • The research focused on how neuronal activity affects the release of αSyn from dopaminergic neurons derived from human stem cells, comparing healthy neurons to those with a PD-related gene mutation.
  • Findings showed that increased neuronal activity boosts αSyn release, while decreased activity reduces it, highlighting the role of neuronal activity in the spread of Lewy pathology and suggesting potential new treatment strategies for neurodegenerative diseases.
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Parkinson's disease (PD), the second most prevalent neurodegenerative disorder, was classically attributed to alpha-synuclein aggregation and consequent loss of dopaminergic neurons in the substantia nigra pars compacta. Recently, emerging evidence suggested a broader spectrum of contributing factors, including exosome-mediated intercellular communication, which can potentially serve as biomarkers and therapeutic targets. However, there is a remarkable lack of comprehensive studies that connect the serum exosome microRNA (miRNA) transcriptome with demographic, clinical, and neuroimaging data in PD patients.

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  • Parkinson's disease (PD) is a progressive neurodegenerative disorder, and early biomarkers are needed for better diagnosis and understanding. This study focuses on analyzing the substantia nigra, an area affected in PD, using a new feature extraction method.
  • The researchers used images from 263 patients (124 PD and 139 non-PD) to test their method, which included training a model to classify differences in the substantia nigra between the two groups, achieving a sensitivity of 0.72 and specificity of 0.64.
  • Although the accuracy of the method is not yet on par with expert physicians, the study highlights the potential of using advanced tensorial feature extraction for diagnosing PD
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  • Cadherin 23 (CDH23) is linked to hereditary hearing loss, with mutations leading to various symptoms based on specific gene changes.
  • Researchers created an induced pluripotent stem cell (iPSC) line from a patient with progressive high-frequency hearing loss due to specific CDH23 mutations.
  • The iPSC line was validated for normal genetic structure and potential to differentiate into various cell types, aiding in disease modeling and understanding the effects of CDH23 mutations.
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Rolling walkers are common walking aids for individuals with poor physical fitness or balance impairments. There is no doubt that rolling walkers are useful in assisting locomotion. On the other hand, it is arguable that walking with rolling walkers (WW) is effective for maintaining or restoring the nervous systems that are recruited during conventional walking (CW).

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The CMT1A variant accounts for over 60% of cases of Charcot-Marie-Tooth disease (CMT), one of the most common human neuropathies. The cause of CMT1A has been identified as the duplication of PMP22, a myelin protein expressed in Schwann cells. Yet, the pathological mechanisms have not been elucidated, and no treatment is currently available.

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  • - PARK2 is the most common autosomal recessive form of Parkinson’s disease, caused by mutations in the parkin gene, leading to early loss of dopamine-producing neurons in the substantia nigra.
  • - This study created an induced pluripotent stem cell (iPSC) line from a patient with a specific mutation (homozygous exon 3 deletion) in PARK2.
  • - The iPSCs displayed characteristics of pluripotency, meaning they can develop into any cell type, and maintained normal genetic structures (karyotypes).
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  • - Parkinson's disease is the second most common neurodegenerative disorder, marked by the presence of Lewy bodies, which are aggregates of the synuclein protein in neurons.
  • - An increase in the synuclein gene (SNCA) leads to higher levels of synuclein, causing hereditary Parkinson's disease that follows an autosomal dominant pattern.
  • - The study created three isogenic induced pluripotent stem cells (iPSCs) from a patient with SNCA duplication, which demonstrated the ability to differentiate into various cell types and maintained normal genetic structure.
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  • - A new iPSC line was created from a healthy male donor for research on Parkinson's disease (PD).
  • - The iPSCs demonstrated pluripotency, the ability to develop into three different cell types, and maintained normal chromosome structure.
  • - This healthy iPSC line serves as a crucial control for studies investigating PD-related changes in patient-derived iPSCs.
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  • * The iPSCs are capable of differentiating into three germ layers and have normal genetic structure (karyotypes).
  • * This iPSC line does not show any genetic abnormalities associated with PD, making it a valuable resource for further PD research.
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Motor imagery (MI) is used for rehabilitation and sports training. Previous studies focusing on the upper limb have investigated the effects of MI on corticospinal excitability in the muscles involved in the imagined movement (i.e.

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  • Endoplasmic reticulum-mitochondrial contact sites (ERMCS) are crucial for mitochondrial function, calcium signaling, and autophagy, and their disruption is associated with neurodegenerative diseases like Alzheimer's and Parkinson's.
  • Researchers examined ERMCS in dopaminergic neurons derived from a patient with a genetic mutation linked to Parkinson's, finding a significant reduction in ERMCS compared to control neurons.
  • The study suggests that this decrease in ERMCS leads to impaired calcium signaling between the endoplasmic reticulum and mitochondria, contributing to the degeneration of dopaminergic neurons in patients with mutations.
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Parkinson's disease (PD) is a common neurodegenerative disorder that results from the loss of dopaminergic neurons. Mutations in coiled-coil-helix-coiled-coil-helix domain containing 2 (CHCHD2) gene cause a familial form of PD with α-Synuclein aggregation, and we here identified the pathogenesis of the T61I mutation, the most common disease-causing mutation of CHCHD2. In Neuro2a cells, CHCHD2 is in mitochondria, whereas the T61I mutant (CHCHD2 ) is mislocalized in the cytosol.

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  • Parkinson's disease (PD) is characterized by the loss of midbrain dopaminergic neurons, and the study explores using human iPSC-derived dopaminergic progenitor cells as a potential cell therapy.
  • The researchers induced iPSCs into these progenitor cells using a previously developed method and transplanted them into PD model mice to assess motor function improvement and cell viability.
  • Results showed that over 90% of the transplanted cells differentiated into mDA neurons, leading to significant enhancements in motor function and indicating the method's potential for PD treatment.
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  • Autophagy is a crucial process for clearing damaged or excess cellular components, and its decline is linked to age-related diseases and tissue degeneration.
  • The research reveals that autophagy helps maintain NAD levels, which are vital for cell survival, and its deficiency can lead to mitochondrial dysfunction and cell death due to stress responses.
  • Interventions that target the NAD depletion process show promise in improving survival rates in autophagy-deficient cells in yeast, mouse models, and human neurons, highlighting potential treatment avenues for diseases related to autophagy and mitochondrial issues.
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  • * The VPS35 gene is specifically associated with a rare form of Parkinson's called PARK17, which is inherited in an autosomal dominant way.
  • * Researchers created three isogenic induced pluripotent stem cell (iPSC) lines from a patient with a specific VPS35 gene variant, confirming their pluripotency and ability to differentiate into various cell types.
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  • * Parkinson's disease primarily affects midbrain dopaminergic neurons, which cannot be easily sourced from living patients for research.
  • * The described method effectively transforms human iPS cells into midbrain dopaminergic neurons, offering insights into the disease and potential new treatments.
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Osteocytes differentiated from osteoblasts play significant roles as mechanosensors in modulating the bone remodeling process. While the well-aligned osteocyte network along the trabeculae with slender cell processes perpendicular to the trabeculae surface is known to facilitate the sensing of mechanical stimuli by cells and the intracellular communication in the bone matrix, the mechanisms underlying osteocyte network formation remains unclear. Here, we developed a novel in vitro collagen matrix system exerting a uniaxially-fixed mechanical boundary condition on which mouse osteoblast-like MC3T3-E1 cells were subcultured, evoking cellular alignment along the uniaxial boundary condition.

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  • Mitochondrial changes impact cell function, apoptosis, and neurodegenerative conditions, with PRKN playing a key role in mitochondrial quality control.
  • Parkinson's disease linked to PRKN mutations leads to the loss of dopaminergic neurons due to damaged mitochondria, yet ultrastructural analysis of these neurons from iPSC has been limited.
  • Researchers created TH-GFP iPSC lines to specifically label dopaminergic neurons, revealing that these neurons have smaller, less functional mitochondria, and their ability to form spheroid-shaped mitochondria is impaired compared to controls.
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  • The chapter outlines a method for creating midbrain dopaminergic neurons from patient-derived induced pluripotent stem (iPS) cells to study neurodegenerative diseases, specifically Parkinson's.
  • It involves using immunostaining techniques to assess cell death and mitochondrial health in these neurons.
  • The combination of this differentiation method with image analysis tools like the IN Cell Analyzer allows for quantitative evaluations that could be useful for drug screening.
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  • Parkin (PRKN) is a ubiquitin ligase essential for mitochondrial quality control, and mutations in this gene lead to the loss of dopaminergic neurons in the substantia nigra, likely due to impaired mitochondrial function.
  • Research showed that individuals with PRKN mutations had fewer specific types of astrocytes (glial fibrillary acidic protein and vimentin-positive) in their substantia nigra compared to those with idiopathic Parkinson's disease.
  • The study also involved differentiating patient-specific induced pluripotent stem cells into midbrain organoids, finding a similar reduction in astrocytes, highlighting a possible link between astrocytic alterations and neuron cell death in PRKN-mutated patients.
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The pathologic hallmark of Parkinson's disease is the accumulation of α-synuclein-containing Lewy bodies/neurites almost exclusively in neurons, and rarely in glial cells. However, emerging evidence suggests that glia such as astrocytes play an important role in the development of α-synuclein pathology. Using induced pluripotent stem-derived dopaminergic neurons and astrocytes from healthy subjects and patients carrying mutations in lysosomal , a monogenic form of synucleinopathy, we found that astrocytes rapidly internalized α-synuclein, and exhibited higher lysosomal degradation rates compared with neurons.

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