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Yamaguchi, Japan

Yamaguchi University is a national university in Yamaguchi Prefecture, Japan. It has campuses at the cities of Yamaguchi and Ube. Wikipedia.

Kanda T.,Yamaguchi University
Journal of Neurology, Neurosurgery and Psychiatry | Year: 2013

The blood-nerve barrier (BNB) is a dynamic and competent interface between the endoneurial microenvironment and the surrounding extracellular space or blood. It is localised at the innermost layer of the multilayered ensheathing perineurium and endoneurial microvessels, and is the key structure that controls the internal milieu of the peripheral nerve parenchyma. Since the endoneurial BNB is the point of entry for pathogenic T cells and various soluble factors, including cytokines, chemokines and immunoglobulins, understanding this structure is important to prevent and treat human immune mediated neuropathies such as Guillain-Barré syndrome, chronic inflammatory demyelinating polyneuropathy, POEMS (polyneuropathy, organomegaly, endocrinopathy, monoclonal protein and skin changes) syndrome and a subset of diabetic neuropathy. However, compared with the blood-brain barrier, only limited knowledge has been accumulated regarding the function, cell biology and clinical significance of the BNB. This review describes the basic structure and functions of the endoneurial BNB, provides an update of the biology of the cells comprising the BNB, and highlights the pathology and pathomechanisms of BNB breakdown in immune mediated neuropathies. The human immortalised cell lines of BNB origin established in our laboratory will facilitate the future development of BNB research. Potential therapeutic strategies for immune mediated neuropathies manipulating the BNB are also discussed. Source

Kimura K.,Yamaguchi University
Investigative ophthalmology & visual science | Year: 2013

TNF-α disrupts the barrier function of cultured human corneal epithelial (HCE) cells. We investigated the effects of the cytoprotective drug rebamipide on this barrier disruption by TNF-α as well as on corneal epithelial damage in a rat model of dry eye. The barrier function of HCE cells was evaluated by measurement of transepithelial electrical resistance. The distribution of tight-junction (ZO-1, occludin) and adherens-junction (E-cadherin, β-catenin) proteins, and the p65 subunit of nuclear factor-κB (NF-κB) was determined by immunofluorescence microscopy. Expression of junctional proteins as well as phosphorylation of the NF-κB inhibitor IκB-α and myosin light chain (MLC) were examined by immunoblot analysis. A rat model of dry eye was developed by surgical removal of exorbital lacrimal glands. Rebamipide inhibited the disruption of barrier function as well as the downregulation of ZO-1 expression, and the disappearance of ZO-1 from the interfaces of neighboring HCE cells induced by TNF-α. It also inhibited the phosphorylation and downregulation of IκB-α, the translocation of p65 to the nucleus, the formation of actin stress fibers, and the phosphorylation of MLC induced by TNF-α in HCE cells. Treatment with rebamipide eyedrops promoted the healing of corneal epithelial defects as well as attenuated the loss of ZO-1 from the surface of corneal epithelial cells in rats. Rebamipide protects corneal epithelial cells from the TNF-α-induced disruption of barrier function by maintaining the distribution and expression of ZO-1 as well as the organization of the actin cytoskeleton. Rebamipide is, thus, a potential drug for preventing or ameliorating the loss of corneal epithelial barrier function associated with ocular inflammation. Source

Iwao Y.,Yamaguchi University
Reproduction | Year: 2012

Fertilization is indispensable not only for restoring diploid genomes but also for the initiation of early embryonic cell cycles in sexual reproduction. While most animals exhibit monospermy, which is ensured by polyspermy blocks to prevent the entry of extra sperm into the egg at fertilization, several animals exhibit physiological polyspermy, in which the entry of several sperm is permitted but only one sperm nucleus participates in the formation of a zygote nucleus. Polyspermy requires that the sperm transmit the egg activation signal more slowly, thus allowing the egg to accept several sperm. An increase in intracellular Ca2+ concentration induced by the fertilizing sperm is both necessary and sufficient for egg activation in polyspermy. Multiple small Ca2+ waves induced by several fertilizing sperm result in a long-lasting Ca2+ rise, which is a characteristic of polyspermic amphibian eggs. We introduced a novel soluble sperm factor for egg activation, sperm-specific citrate synthase, into polyspermic newt eggs to cause Ca 2+ waves. Citrate synthase may perform dual functions: as an enzyme in mitochondria and as a Ca2+-inducing factor in egg cytoplasm. We also discuss the close relationship between the mode of fertilization and the Ca2+ rise at egg activation and consider changes in this process through evolution in vertebrates. © 2012 Society for Reproduction and Fertility. Source

Molecular simulation is attracting great interest in these days as a powerful tool to reveal the molecular mechanism of polymer crystallization. Most of the studies reported hitherto have dealt with simple model polymers like polyethylene, and the majority of polymers having more complex chemical structures remain almost untouched. In this report, we make a new challenge to the crystallization in a typical helical polymer isotactic polypropylene (iPP). We consider a relatively small system of 40 iPP oligomers each made of 50 propylene monomers by use of a realistic flexible model. The crystallization of iPP has long been considered too sluggish to be investigated by molecular simulations. We here take advantage of the accelerated crystallization from the highly stretched amorphous state. By carrying out very long simulations of about 600 ns total, we succeed in observing the onset of crystallization and subsequent crystal growth. Very unexpectedly, we come to see the growth of the smectic mesophase, which is believed to grow at temperatures much lower than the melting point. For the growth of crystals of stable forms of definite chirality, such as the α-form or the β-form, the chirality selection process will need a much longer time. The hypothesis is that the very fast crystallization observed here does not allow the slower processes of helical selection and gives rise to the formation of the smectic mesophase with somewhat random disposition of helices. © 2014 American Chemical Society. Source

Accumulation of lipid peroxide-derived aldehydes and ketones is a ubiquitous event in oxidative stress. The toxicity of these carbonyls, especially the α,β-unsaturated carbonyls (reactive carbonyls; RCS), in environmental-stressed plants has been demonstrated by several independent research groups, on the basis of the results that overexpression of different carbonyl-detoxifying enzymes commonly improved tolerance of the transgenic plants against environmental stresses. A positive correlation between the level of carbonyls and the stress-induced damage in these plants proves the cause-effect relationship between carbonyls and the cell injury. Comprehensive analysis of carbonyls has revealed that dozens of distinct RCS including highly toxic acrolein and 4-hydroxy-2-nonenal are contained at nmol/g fresh weight levels in the tissues of non-stressed plants. Stress treatments of plants increase the levels of these RCS, likely reaching a sub-mM order, but in the transgenic plants overproducing RCS-detoxifying enzymes, their increase is significantly suppressed. Immunological analyses have demonstrated that in non-stressed cells several proteins are modified by RCS and the extent of modification is increased on stresses. In heat-stressed leaves, the inactivation of the oxygen-evolving complex was associated with selective modification of OEC33 protein and photosystem II core proteins. RCS consume glutathione and inactivate various enzymes in chloroplasts and mitochondria, thereby accelerating oxidative stress status. Thus RCS, formed downstream of reactive oxygen species (ROS), act in a way biochemically distinct from that of ROS and play critical roles in the plant responses to oxidative stress. © 2012 Elsevier Masson SAS. Source

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