Publications by authors named "Hayato Koizumi"

The mechanisms that generate robust ionic oscillation in circadian pacemaker neurons are under investigation. Here, we demonstrate critical functions of the mitochondrial cation antiporter leucine zipper-EF-hand-containing transmembrane protein 1 (LETM1), which exchanges K/H in Drosophila and Ca/H in mammals, in circadian pacemaker neurons. Letm1 knockdown in Drosophila pacemaker neurons reduced circadian cytosolic H rhythms and prolonged nuclear PERIOD/TIMELESS expression rhythms and locomotor activity rhythms.

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Cholecystokinin (CCK) and leptin are satiety-controlling peptides, yet their interactive roles remain unclear. Here, we addressed this issue using in vitro and in vivo models. In rat C6 glioma cells, leptin pre-treatment enhanced Ca mobilization by a CCK agonist (CCK-8s).

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Vertebrate eyes are known to contain circadian clocks, but their regulatory mechanisms remain largely unknown. To address this, we used a cell line from human retinal pigment epithelium (hRPE-YC) with stable coexpression of reporters for molecular clock oscillations () and intracellular Ca concentrations (). We observed concentration-dependent increases in cytosolic Ca concentrations after treatment with histamine (1-100 µM) and complete suppression of histamine-induced Ca mobilizations by H histamine receptor (HR) antagonist -chlorpheniramine (-CPA) in hRPE-YC cells.

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The particle dispersion behavior was compared for ultrasonic irradiation and mechanical stirring. The experiment and calculation were carried out with polymethylmethacrylate (PMMA) particles. The dispersion rate of the agglomerated particles increased with the decreasing ultrasonic frequency and the increasing electric power, whereas it increased with the increasing rotation speed for the mechanical stirring.

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We demonstrate physical implementation of information-theoretic secure oblivious transfer based on bounded observability using optical correlated randomness in semiconductor lasers driven by common random light broadcast over optical fibers. We demonstrate that the scheme can achieve one-out-of-two oblivious transfer with effective key generation rate of 110 kb/s. The results show that this scheme is a promising approach to achieve information-theoretic secure oblivious transfer over long distances for future applications of secure computation such as privacy-preserving database mining, auctions and electronic-voting.

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It has been proposed that a secure key distribution scheme using correlated random bit sequences can be implemented using common random-signal induced synchronization of semiconductor laser systems. In this scheme it is necessary to use laser systems consisting of multiple cascaded lasers to be secure against a powerful eavesdropper. In this paper, we report the results of an experimental study that demonstrate that the common random-signal induced synchronization is possible in cascaded semiconductor laser systems.

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We experimentally and numerically observe the synchronization between two semiconductor lasers induced by common optical injection with constant-amplitude and random-phase modulation in configurations with and without optical feedback. Large cross correlation (~0.9) between the intensity oscillations of the two response lasers can be achieved although the correlation between the drive laser and either one of the two response lasers is very small (~0.

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We previously reported strong induction of ovalbumin (OVA)-specific tumor immunity in mice injected subcutaneously with OVA-entrapping nanoparticles comprising amphiphilic poly(γ-glutamic acid) (OVA/γ-PGA NPs). In the present study we investigated antitumor efficacy and associated immune responses in mice vaccinated with OVA/γ-PGA NPs via the nasal cavity. Mice vaccinated intranasally with OVA/γ-PGA NPs resisted challenge by E.

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