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Biological Studies on Alcohol-Induced Neuronal Damage
Masaru Tateno,Toshikazu Saito 대한신경정신의학회 2008 PSYCHIATRY INVESTIGATION Vol.5 No.1
Alcohol is a well-known cytotoxic agent which causes various kinds of neuronal damage. In spite of thousands of published studies, the true mechanism of alcohol-induced neuronal damage remains unclear. Neurogenesis is the generation of neurons from neural stem cells (NSCs) and occurs in predominantly two regions of the brain, the subventricular zone and the dentate gyrus of the hippocampus. NSCs are the self-renewing, multipotent precursor cells of neurons, strocytes, and oligodendrocytes in the central nervous system. Recent studies have begun to illuminate the role of neurogenesis in the biological and cellular basis of psychiatric disorders and several clinical symptoms seen in alcoholism such as depression, cognitive impairment, underlying stress and brain atrophy have been linked to impaired neurogenesis. Heavy alcohol consumption decreases neurogenesis in animals, while in vitro studies have shown decreased generation of new neurons after alcohol exposure. These findings suggest that decreased neurogenesis is important in the pathophysiology of alcoholism. Neurogenesis can be divided into four stages; proliferation, migration, differentiation and survival. Our in vitro studies on NSCs showed that alcohol decreased neuronal differentiation at doseslower than those that affected cell survival and suggested that neuron-restrictive silencer factor, or repressor element-1 silencing transcription factor (NRSF/REST) could be involved in alcohol-induced inhibition of neuronal differentiation. In an animal model of fetal alcohol effects behavioral symptoms improved after NSC transplantation. Neurogenesis could be the target for new strategies to treat alcohol related disorders. Alcohol is a well-known cytotoxic agent which causes various kinds of neuronal damage. In spite of thousands of published studies, the true mechanism of alcohol-induced neuronal damage remains unclear. Neurogenesis is the generation of neurons from neural stem cells (NSCs) and occurs in predominantly two regions of the brain, the subventricular zone and the dentate gyrus of the hippocampus. NSCs are the self-renewing, multipotent precursor cells of neurons, strocytes, and oligodendrocytes in the central nervous system. Recent studies have begun to illuminate the role of neurogenesis in the biological and cellular basis of psychiatric disorders and several clinical symptoms seen in alcoholism such as depression, cognitive impairment, underlying stress and brain atrophy have been linked to impaired neurogenesis. Heavy alcohol consumption decreases neurogenesis in animals, while in vitro studies have shown decreased generation of new neurons after alcohol exposure. These findings suggest that decreased neurogenesis is important in the pathophysiology of alcoholism. Neurogenesis can be divided into four stages; proliferation, migration, differentiation and survival. Our in vitro studies on NSCs showed that alcohol decreased neuronal differentiation at doseslower than those that affected cell survival and suggested that neuron-restrictive silencer factor, or repressor element-1 silencing transcription factor (NRSF/REST) could be involved in alcohol-induced inhibition of neuronal differentiation. In an animal model of fetal alcohol effects behavioral symptoms improved after NSC transplantation. Neurogenesis could be the target for new strategies to treat alcohol related disorders.
Functional proteomics, human genetics and cancer biology of GIPC family members
Masaru Katoh 생화학분자생물학회 2013 Experimental and molecular medicine Vol.45 No.6
GIPC1, GIPC2 and GIPC3 consist of GIPC homology 1 (GH1) domain, PDZ domain and GH2 domain. The regions around the GH1 and GH2 domains of GIPC1 are involved in dimerization and interaction with myosin VI (MYO6), respectively. The PDZ domain of GIPC1 is involved in interactions with transmembrane proteins [IGF1R, NTRK1, ADRB1, DRD2, TGFbR3(transforming growth factorb receptor type III), SDC4, SEMA4C, LRP1, NRP1, GLUT1, integrin a5 and VANGL2], cytosolic signaling regulators (APPL1 and RGS19) and viral proteins (HBc and HPV-18 E6). GIPC1 is an adaptor protein with dimerizing ability that loads PDZ ligands as cargoes for MYO6-dependent endosomal trafficking. GIPC1 is required for cell-surface expression of IGF1R and TGFbR3. GIPC1 is also required for integrin recycling during cell migration, angiogenesis and cytokinesis. On early endosomes, GIPC1 assembles receptor tyrosine kinases (RTKs) and APPL1 for activation of PI3K–AKT signaling, and G protein-coupled receptors (GPCRs) and RGS19 for attenuation of inhibitory Ga signaling. GIPC1 upregulation in breast, ovarian and pancreatic cancers promotes tumor proliferation and invasion, whereas GIPC1 downregulation in cervical cancer with human papillomavirus type 18 infection leads to resistance to cytostatic transforming growth factorb signaling. GIPC2 is downregulated in acute lymphocytic leukemia owing to epigenetic silencing, while Gipc2 is upregulated in estrogen-induced mammary tumors. Somatic mutations of GIPC2 occur in malignant melanoma, and colorectal and ovarian cancers. Germ-line mutations of the GIPC3 or MYO6 gene cause nonsyndromic hearing loss. As GIPC proteins are involved in trafficking, signaling and recycling of RTKs, GPCRs, integrins and other transmembrane proteins, dysregulation of GIPCs results in human pathologies, such as cancer and hereditary deafness.
Flow Characteristics of Pulp Suspension in a 90° Bend
Masaru Sumida,Kentaro Imamura 한국유체기계학회 2020 International journal of fluid machinery and syste Vol.13 No.2
This study investigates the flow characteristics of pulp suspensions flowing through a 90° bend, which is used in the production system of an actual papermaking machine, e.g., for transporting the pulp suspensions from its stock reservoir to the header. Experiments were conducted on pulp suspensions with a fiber concentration Cs of 0.3 and 0.6 wt% and a bend with a diameter of 22 mm and a curvature radius ratio of 4.0. Flow visualization and measurements of the distributions of time-averaged fiber concentration Ca and axial velocity U were performed with a light section method and the particle image velocimetry (PIV) method, respectively, at representative bulk velocities and at various longitudinal stations. The influence of the flow rate on the changes of their distributions in the streamwise direction was examined. The flow characteristics of the pulp suspension depend on the flow pattern in the upstream straight tube and are greatly different from those of the single-phase water flow. For a low flow rate, the flocculated pulp fibers move without getting disentangled in the bend and the distribution of Ca shows a shape bias towards the inner wall side. As the flow rate is increased, Ca becomes larger in the outer part of the bend, and it changes into a rather flat distribution in the downstream tangent.
Masaru Sumida,Takahiro Kamahara 한국유체기계학회 2022 International journal of fluid machinery and syste Vol.15 No.3
T his study involved an experimental investigation of the distribution of pulp fiber concentration in t he region behind a partitio n plate with a taper ed trailing edge inserted in a convergen t channel The channel was modeled at the laboratory scale for the dispersio n and rectification components of the headbox passage in a papermaking machine. For t he exp e r iment s the inlet cross se c tional average flow velocity U a , of an actual pulp suspension was in the range of 0.03 3.3 m/s . T he flow was visualized and the fiber concentration distribution was measured. Subsequently, t he effects of the flow velocity on t h e time averaged and fluctu a ting fiber concentration distributions C a and C’ respectively ) in the flow direction were examined through compar i so n s with those in the case s where the plate was installed in the parallel channel or had a simple rectangular e d ge In the convergent chan n el with the taper ed trailing edge, t he fiber concentration def ect behind the plate was reduced abruptly . Moreover, the uniformity of the fiber concentration distribution at the convergence exit did not vary with the flow veloci t y , thereby having a low val u e. Overall, the fundamental observations obtained in this study can contribute to the optimization and improve ment of the headbox channel s of papermaking machine s