SUMMARYSyntaxin-binding protein 1 (STXBP1) is essential for synaptic vesicle exocytosis. Mutations of its encoding gene, STXBP1, are among the most frequent genetic causes of epileptic encephalopathies. However, the precise pathophysiology of STXBP1 haploinsufficiency has not been elucidated. Using patient-derived induced pluripotent stem cells (iPSCs), we aimed to establish a neuronal model for STXBP1 haploinsufficiency and determine the pathophysiologic basis for STXBP1 encephalopathy. We generated iPSC lines from a patient with Ohtahara syndrome (OS) harboring a heterozygous nonsense mutation of STXBP1 (c.1099C>T; p.R367X) and performed neuronal differentiation. Both STXBP1 messenger RNA (mRNA) and STXBP1 protein expression levels of OS-derived neurons were approximately 50% lower than that of controlderived neurons, suggesting that OS-derived neurons are a suitable model for elucidating the pathophysiology of STXBP1 haploinsufficiency. Through Western blot and immunocytochemistry assays, we found that OS-derived neurons show reduced levels and mislocalization of syntaxin-1, a component of soluble N-ethylmaleimide-sensitive factor attachment receptor (SNARE) proteins. In addition, OS-derived neurons have impaired neurite outgrowth. In conclusion, this model enables us to investigate the neurobiology of STXBP1 encephalopathy throughout the stages of neurodevelopment. Reduced expression of STXBP1 leads to changes in the expression and localization of syntaxin-1 that may contribute to the devastating phenotype of STXBP1 encephalopathy. KEY WORDS: Ohtahara syndrome, Induced pluripotent stem cell, SNARE complex.Epileptic encephalopathies (EEs) are a group of devastating epileptic disorders, occurring at a critical period of brain development, where frequent seizures and/or persistent severe electroencephalography (EEG) abnormalities lead to behavioral, cognitive, and motor deterioration or regression. EEs have numerous causes, including damage to or malformation of the brain. In cases without such identifiable causes, recent investigations have found disease-causing mutations in several genes. Studies of mutations in these genes can help elucidate the pathophysiology of diseasecausing alterations in the nervous system, encouraging progress toward new treatments.Ohtahara syndrome (OS), also known as early infantile EE with suppression-burst (S-B), is one of the most severe and earliest forms of EE. Mutations in STXBP1 are among the most frequent genetic causes of OS.1 In addition, STXBP1 mutations result in not only OS but also West

Dravet syndrome (DS) is a severe childhood epilepsy typically caused by de novo dominant mutations in SCN1A. Although patients with DS frequently have neurocognitive abnormalities, the precise neural mechanisms responsible for their expression have not been elucidated. There are wide phenotypic differences among individuals with SCN1A mutations, suggesting that factors other than the SCN1A mutation modify the phenotype. Therefore, a well-controlled cellular model system is required to improve our understanding of the mechanisms underlying DS. Here we generated induced pluripotent stem cell (iPSC) lines from an individual with SCN1A mutation mosaicism, and separately cloned iPSC lines both with and without the SCN1A mutation. These clones theoretically have the same genetic backgrounds, except for the SCN1A gene, and should serve as an ideal pair for investigating the pathophysiology caused by SCN1A mutations. Quantitative reverse transcription-PCR and western blot analysis revealed higher tyrosine hydroxylase mRNA and protein expression levels in mutant neurons than in wild-type neurons. Moreover, dopamine concentrations in media collected from mutant neural cultures were higher than those from wild-type neural cultures. Our findings suggest that SCN1A mutation leads to changes in the dopamine system that may contribute to the behavioral abnormalities in DS.

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Background: Few studies have reported the measurement of anatomical dead space (V d,an) and alveolar tidal volume (V A) in ventilated neonates with respiratory distress. Objective: The aim of this study was to determine the differences in V d,an and V A in ventilated infants between the early and recovery phases of respiratory distress using volumetric capnography (V cap) based on ventilator graphics and capnograms. Methods: This study enrolled twenty-five ventilated infants (mean birth weight, 2,220 ± 635 g; mean gestational age, 34.7 ± 3.3 weeks). We adjusted respiratory settings to maintain appropriate oxygenation and tidal volume (V T), and performed V cap based on waveforms of ventilator graphics and capnograms. V d,an and V A were measured in infants with respiratory disorders, immediately after intubation (early phase) and subsequently when they were clinically stable (recovery phase). Results: The early phase, with lower dynamic lung compliance, required a higher level of ventilator support, not positive end-expiratory pressure, than the recovery phase. There were significant differences between the early and recovery phases for V d,an