Publications by authors named "Kakiuchi C"

Article Synopsis
  • - The study investigates the link between rare copy number variations (CNVs) in synaptic genes and bipolar disorder (BD) in a Japanese population, using genome hybridization techniques on nearly 2,000 BD patients and 2,760 controls.
  • - Results indicate a strong association between the RNF216 gene and BD, with significant findings also related to postsynaptic membrane components, suggesting these genetic factors contribute to BD risk.
  • - The findings enhance understanding of BD's genetic underpinnings, highlighting the importance of CNVs in gene regions that may influence the disorder's development.
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Background: Self-disturbance has been considered as a core symptomatology of schizophrenia and its emergence from the prodromal phase makes it a crucial target for early detection and intervention in schizophrenia. Currently, the clinical assessment of self-disturbance relies on the self-report of patients, and clinicians have no diagnostic tools in clinical practice. Identifying the neural substrate of self-disturbance would be of great clinical value by shedding light on the core dimension of schizophrenia.

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Patients with bipolar disorder often report self-perceived treatment resistance. However, it is not known to what extent it is due to actual treatment resistance. The Juntendo University provides "Bipolar Disorder Treatment Rebuilding Program," in which patients with self-reported treatment resistant bipolar disorder are hospitalized for 2 weeks and undergo detailed examinations.

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Aim: To investigate the real-world effectiveness and safety of lemborexan for treating comorbid insomnia associated with other psychiatric disorders, and whether lemborexant helps reduce the dose of benzodiazepines (BZs).

Methods: This retrospective observational study was conducted on outpatients and inpatients treated by physicians of Juntendo University Hospital Mental Clinic between April 2020 and December 2021.

Results: Data of 649 patients who were treated with lemborexant were eventually enrolled.

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Article Synopsis
  • The study investigates the differences and similarities in copy number variations (CNVs) related to bipolar disorder (BD), schizophrenia (SCZ), and autism spectrum disorder (ASD) using data from 8708 Japanese individuals.
  • It reveals that BD has a greater burden of smaller exonic deletions, while SCZ and ASD show a prevalence of larger exonic CNVs, with notable differences in the effect sizes and distributions of these CNVs across disorders.
  • Despite these differences, some shared molecular mechanisms, particularly in chromatin biology, were identified, and certain synaptic genes were linked to BD risk, suggesting potential pathways for further research into its causes.
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SLC6A4, which encodes the serotonin transporter, has a functional polymorphism called the serotonin transporter-linked polymorphic region (5-HTTLPR). The 5-HTTLPR consists of short (S) and long (L) alleles, each of which has 14 or 16 tandem repeats. In addition, the extralong (XL) and other rare alleles have been reported in 5-HTTLPR.

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  • The study investigates the relationship between altered DNA methylation of the SLC6A4 gene (which encodes the serotonin transporter) and schizophrenia, finding significant hypermethylation in male patients across three different groups.
  • Chronic treatment with risperidone did not impact DNA methylation levels at a specific CpG site, suggesting that the hypermethylation is a defining feature of the disorder rather than a treatment effect.
  • Additionally, low-activity variants of the 5-HTT-linked polymorphic region (5-HTTLPR) were linked to greater hypermethylation and a negative correlation with left amygdala volume, indicating a potential relationship between genetic factors, DNA methyl
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Recent studies have shown that microRNAs (miRNAs) play a role as regulators of neurodevelopment by modulating gene expression. Altered miRNA expression has been reported in various psychiatric disorders, including schizophrenia. However, the changes in the miRNA expression profile that occur during the initial stage of schizophrenia have not been fully investigated.

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Inequity aversion (negative feelings induced by outcome differences between the self and other) plays a key role in human social behaviors. The neurotransmitters oxytocin and GABA have been implicated in neural responses to inequity. However, it remains poorly understood not only how individual genetic factors related to oxytocin and GABA affect the neural mechanisms behind inequity aversion, but also how these genes interact.

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Monozygotic twins are assumed to have identical genomes. Based on this assumption, phenotypic discordance in monozygotic twins has been previously attributed to environmental factors. However, recent genomic studies have identified characteristic somatic mutations in monozygotic twins discordant for Darier disease, Van der Woude syndrome, and Dravet syndrome.

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Aim: Schizophrenia (SZ) and bipolar disorder (BD) have been known to share genetic and environmental risk factors, and complex gene-environmental interactions may contribute to their pathophysiology. In contrast to high genetic overlap between SZ and BD, as revealed by genome-wide association studies, the extent of epigenetic overlap remains largely unknown. In the present study, we explored whether SZ and BD share epigenetic risk factors in the same manner as they share genetic components.

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The mechanism underlying the vulnerability to developing schizophrenia (SCZ) during adolescence remains elusive. Hypofunction of -methyl-d-aspartate receptors (NMDARs) has been implicated in the pathophysiology of SCZ. During development, the composition of synaptic NMDARs dramatically changes from NR2B-containing NMDARs to NR2A-containing NMDARs through the phosphorylation of NR2B S1480 or Y1472 by CDK5, CSNK2A1, and EphB2, which plays a pivotal role in the maturation of neural circuits.

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Aim: Hypofunction of N-methyl-D-aspartate receptors (NMDAR) may contribute to the pathophysiology of schizophrenia (SCZ). Recently, the glycine cleavage system (GCS) was shown to affect NMDAR function in the brain. GCS functional defects cause nonketotic hyperglycinemia, the atypical phenotype of which presents psychiatric symptoms similar to SCZ.

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Tourette Syndrome (TS) is a neurodevelopmental disorder characterized by chronic motor and vocal tics. Although there is a large genetic contribution, the genetic architecture of TS remains unclear. Exome sequencing has successfully revealed the contribution of de novo mutations in sporadic cases with neuropsychiatric disorders such as autism and schizophrenia.

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Article Synopsis
  • The study investigates the impact of rare missense variants in the POLG1 gene on bipolar disorder by using multiple assessment methods, including in silico predictions, in vitro biochemical assays, and clinical evaluations.
  • Researchers analyzed variants in 796 Japanese bipolar disorder patients and 767 controls, finding 23 distinct variants to assess.
  • Results indicated that deleterious POLG1 variants were significantly more common in patients than in controls, suggesting these variants contribute to the risk of bipolar disorder through mitochondrial dysfunction.
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Oxytocin appears beneficial for autism spectrum disorder (ASD), and more than 20 single-nucleotide polymorphisms (SNPs) in oxytocin receptor (OXTR) are relevant to ASD. However, neither biological functions of OXTR SNPs in ASD nor critical OXTR SNPs that determine oxytocin's effects on ASD remains known. Here, using a machine-learning algorithm that was designed to evaluate collective effects of multiple SNPs and automatically identify most informative SNPs, we examined relationships between 27 representative OXTR SNPs and six types of behavioral/neural response to oxytocin in ASD individuals.

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Several recent gene expression studies on schizophrenia, including one using monozygotic twins discordant for the disease, have reported the upregulation of adrenomedullin (ADM), which was initially identified as a vasodilator hormone. It has been hypothesized that upregulation of ADM may be a susceptibility factor for schizophrenia, although the exact role of ADM in the central nervous system remains unclear. In this study, we used a microarray analysis to investigate the changes in global gene expression induced by the administration of exogenous ADM in SK-N-SH cells, which allowed us to evaluate the effects of elevated ADM on the central nervous system.

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  • Multichannel near-infrared spectroscopy (NIRS) is a noninvasive method for measuring blood oxygenation changes in the brain, allowing for the analysis of resting state functional connectivity (RSFC).
  • A study involving 17 healthy participants utilized a multi-distance probe arrangement and independent component analysis to separate brain signals, finding that partial correlation analysis effectively reduced external noise and yielded significant connectivity results.
  • The method demonstrated notable RSFC patterns between brain regions, with females showing increased connectivity in certain areas compared to males, indicating NIRS's potential for studying neural networks and sex differences in brain activity.
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The SLITRK1 (Slit and Trk-like 1) gene has been suggested to be a promising candidate for Tourette syndrome (TS) since the first report that identified its two rare variants adjacent to the chromosome inversion in a TS child with inv(13) (q31.1;q33.1).

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Autism spectrum disorder is a heterogeneous neurodevelopmental disorder with strong genetic basis. To identify common genetic variations conferring the risk of ASD, we performed a two-stage genome-wide association study using ASD family and healthy control samples obtained from East Asian populations. A total of 166 ASD families (n = 500) and 642 healthy controls from the Japanese population were used as the discovery cohort.

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Mental health problems, such as depression, are increasingly common among workers. Job-related stresses, including psychological demands and a lack of discretion in controlling one's own work environment, are important causal factors. However, the mechanisms through which job-related stress may affect brain function remain unknown.

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  • Accumulating evidence links epigenetic changes in brain-derived neurotrophic factor (BDNF) to psychiatric disorders, with alterations found in various tissues, including peripheral blood cells (PBC) and saliva.
  • In a study involving Japanese participants, researchers analyzed DNA methylation levels of BDNF promoters in PBC from both healthy controls and schizophrenia patients, identifying significantly higher methylation at promoter I in the schizophrenia group.
  • Findings suggest that the BDNF methylation pattern may be indicative of schizophrenia's underlying pathophysiology and could serve as a potential biomarker, with sex differences influencing the results.
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The early growth response 3 (EGR3) gene is an immediate early gene that is expressed throughout the brain and has been suggested as a potential susceptibility gene for schizophrenia (SZ). EGR3 impairment is associated with various neurodevelopmental dysfunctions, and some animal studies have reported a role for EGR3 function in the prefrontal cortex. Therefore, EGR3 genotype variation may be reflected in prefrontal function.

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Epidemiological studies have revealed that schizophrenia is highly heritable. However, genetic studies have not fully elucidated its etiology. Accumulating evidence suggests that epigenetic alterations may provide an additional explanation of its pathophysiology.

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