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Biomedical subjects

Toshiaki Kato

Publications and source records attributed to Toshiaki Kato.

12 recordsLinked to original sources
PubMed2007

Generation of inflammatory cytokines and chemokines from peripheral blood mononuclear cells by HLA Class II antibody-containing plasma unit that was associated with severe nonhemolytic transfusion reactions.

BACKGROUND: HLA Class II antibodies are thought to be involved in severe transfusion reactions including transfusion-related acute lung injury (TRALI). The activation of monocytes by HLA Class II antibody may play an important role in the etiology of TRALI. CASE REPORT: An 81-year-old man with non-Hodgkin's lymphoma (Clinical Stage IIIA) received a plateletpheresis unit containing at least 4 x 10(11) platelets because of thrombocytopenia and a bleeding tendency. Approximately 30 minutes after the start of transfusion, he developed chills, tachycardia, dyspnea, lumber, and abdominal pain and then a fever (40.3 degrees C). His SaO(2) dropped to 70 percent. The transfusion was discontinued immediately. His symptoms disappeared after treatment with oxygen and the administration of corticosteroid and aminophyrine. A chest X-ray showed no sign of pulmonary edema. RESULTS: The donor serum sample had HLA-DR antibodies against multiple DR antigens including DR13, the recipient's HLA-DR type. The cross-match between the patient's lymphocytes and the donor serum was positive. The treatment of peripheral blood mononuclear cells from healthy subjects bearing DR13 antigen with the donor plasma caused the secretion of inflammatory cytokines (i.e., interleukin [IL]-1beta, IL-6, and tumor necrosis factor-alpha) and neutrophil-activating chemokines (i.e., IL-8 and CXCL1/GRO-alpha) in a cognate antigen-antibody relationship. In addition, the secretion of inflammatory cytokines appeared to require the involvement of CD32 and/or CD16. CONCLUSION: HLA-DR antibodies, detected in this case, had biologic functions to induce production of not only inflammatory cytokines but also neutrophil-attractant chemokines in vitro, which could contribute to the etiology of severe nonhemolytic transfusion reactions.

Acute Disease↗
PubMed2006

Heart slice NMR.

Nuclear magnetic resonance (NMR) spectroscopy of the heart is normally carried out using whole heart preparations under coronary perfusion. In such preparations, either radical changes in ionic composition of the perfusate or applications of numerous drugs would affect coronary microcirculation. This report communicates the first (31)P NMR spectroscopy study using a heart slice preparation (left ventricular slices) superfused with extracellular medium. The ratio of phosphocreatine concentration to ATP concentration was approximately 2.1. Also, intracellular pH and Mg(2+) concentration ([Mg(2+)](i)), estimated from the chemical shifts of inorganic phosphate and ATP, were comparable with those under retrograde perfusion. [Mg(2+)](i) was significantly increased by the removal of extracellular Na(+), supporting the essential role of Na(+)-coupled Mg(2+) transport in Mg(2+) homeostasis of the heart. Heart slice preparation could also be used to evaluate the potency of cardiac drugs, regardless of their possible effects on coronary microcirculation.

Adenosine Triphosphate↗
PubMed2005

Life-threatening adverse reaction followed by thrombocytopenia after passive transfusion of fresh frozen plasma containing anti-CD36 (Nak) isoantibody.

BACKGROUND: Anti-CD36 isoantibody in blood recipients is reported to cause refractoriness to platelet (PLT) transfusions and posttransfusion purpura-like syndrome. There are few reports, however, about the effects of passively transfused blood products containing this isoantibody on recipients. CASE REPORT: A 67-year-old Japanese woman underwent brain surgery. On the 6th postoperative day, the patient experienced tightness of the chest and nausea after receiving a transfusion of fresh frozen plasma (FFP). When she manifested hypotension, the transfusion was discontinued. No cutaneous manifestation was observed. The patient's condition gradually improved soon after the administration of steroids. RESULTS: Her pretransfusion PLT count was 17.1 x 10(4) per microL. It decreased to 1.9 x 10(4) per microL 12 hours after transfusion and recovered to 15.4 x 10(4) per microL 8 days after transfusion. The donor of the FFP had a Type I CD36 deficiency. Flow cytometric analysis identified anti-CD36 isoantibody in the FFP. The cross-match between the patient's PLTs and the FFP was positive. The FFP induced the aggregation of PLTs derived from healthy adults. CONCLUSION: This is the first reported case of life-threatening adverse effects and thrombocytopenia caused by passively transfused anti-CD36 isoantibody. The possibility of passive infusion of this antibody should be considered in the evaluation of life-threatening transfusion reactions followed by thrombocytopenia.

Acute Disease↗
PubMed2005

Structural and functional properties of homologous electrical synapses between retinal amacrine cells.

Retinal amacrine cells regulate activities of retinal ganglion cells, the output neurons to higher visual centers, through cellular mechanism of lateral inhibition in the inner plexiform layer (IPL). Electrical properties of gap junction networks between amacrine cells in the IPL were investigated using combined techniques of intracellular recordings, Lucifer yellow and Neurobiotin injection, dual patch-clamp recordings and high voltage electron microscopy in isolated retinas of cyprinid fish. Six types of gap-junctionally connected amacrine cells were classified after their light-evoked responses to light flashes were recorded. Among them, gap junction networks of three types of amacrine cells were studied with structure-function correlation analysis. Cellular morphology of intercellular connections between three homologous cell classes was characterized. The interconnections between laterally extending dendrites in the IPL were localized at dendritic tip terminals. Three types of cells presented the dendrodendritic connections of tip-contact manner in the homologous cell population. High voltage as well as conventional electron microscopy revealed gap junctions between the dendritic tips of Neurobiotin-coupled cells. Receptive field properties of these amacrine cells were examined, displacing a slit of light along the distance from recording sites in the dorsal intermediate region of the retina. Receptive field size, space length constant, response latency and conduction velocity were measured. Spatial and temporal properties of receptive fields were symmetric along horizontally expanding dendrites in the dorsal retina. Simultaneous dual patch-clamp recordings revealed that the lateral gap junction connections between homologous amacrine cells expressed bidirectional electrical synapses passing Na(+) spikes. These results demonstrate that bidirectional electrical transmission in gap junction networks of these amacrine cells is symmetric along the lateral gap junction connections between horizontally extending dendrites. Lateral inhibition regulated by amacrine cells in the IPL appears to be associated with the directional extension of the dendrites and the orientation of dendrodendritic gap junctions.

Action Potentials↗
PubMed2004

Transfusion-transmitted hepatitis E caused by apparently indigenous hepatitis E virus strain in Hokkaido, Japan.

BACKGROUND: In industrialized countries, sporadic cases of hepatitis E have been reported in individuals who have never been in an endemic area. Hepatitis E virus (HEV) infection commonly occurs via the fecal-oral route but a potential risk of transfusion transmission route has been suggested. STUDY DESIGN AND METHODS: A 67-year-old Japanese male patient who had never been abroad received a transfusion of blood from 23 voluntary donors and developed acute hepatitis with unknown etiology after transfusion. His blood samples were tested for viral markers of hepatitis viruses. RESULTS: HAV, HBV, HCV, CMV, and EBV were ruled out as causative agents in this case. The patient's blood sample in the acute phase contained HEV RNA as well as IgM and IgG anti-HEV. HEV RNA was also detected in one of the FFP units transfused. The donor had no history of traveling abroad and had a normal ALT level at the time of donation. The PCR products from the patient and the donor showed complete identity for two distinct regions of HEV within open reading frame 1. CONCLUSION: The patient was infected with HEV via transfused blood from a volunteer donor. A potential risk of posttransfusion hepatitis E should be considered even in nonendemic countries.

Adult↗
PubMed2003

Development of computerized Kana Pick-out Test for the neuropsychological examination.

The Kana Pick-out Test, which was developed in Japan and done with paper and pencil, is said to be suitable for inspecting higher-order brain function and to be a good method for screening persons with mild or slight dementia. We have developed a computerized version of the Kana Pick-out Test, which runs on a stand-alone computer, intended to be utilized for mass screening and self-administration. The program was developed with Microsoft Visual Basic 6.0 and runs under the Windows operating system on any IBM PC compatible computer. In this study, all subjects could use the system by interacting with the computer and it was found that the system seemed to have the capability of detecting cognitive status equal to the paper-based Kana Pick-out Test. Besides this, we developed a network-based Kana Pick-out game software which was intended to attract user's notice. The game program was written in JAVA language and runs on a web-browser supporting JAVA on any operating system. The program, a so called applet, is located on our web site (http://environ.med.tottori-u.ac.jp) and anyone can use the applet by accessing our homepage.

Adult↗
PubMed2003

Biologic activity of RANTES in apheresis PLT concentrates and its involvement in nonhemolytic transfusion reactions.

BACKGROUND: RANTES, one of the PLT-derived biologic response modifiers, accumulates in PLT concentrates (PCs) during storage and may play a causative role in nonhemolytic transfusion reactions (NHTRs) after PC transfusion. STUDY DESIGN AND METHODS: To investigate the association of RANTES with NHTRs, the biologic activity of RANTES in the supernatant of stored PC at the intravascular concentration expected after PC transfusion was assessed by examining chemotaxis and histamine release in human basophils. In addition, the levels of RANTES in PCs involved in NHTRs were compared with those in PCs causing no transfusion reactions. RESULTS: The supernatant of PC diluted to contain 1 nM RANTES significantly increased the migration of and release of histamine from basophils. Neutralizing antibody to RANTES suppressed the PC-triggered migration, but not histamine release. The levels of RANTES in PCs involved in NHTRs after PC transfusion were comparable to those in PCs that did not cause any transfusion reactions. CONCLUSION: RANTES that accumulated in PCs during storage was biologically active in a basophil chemotaxis assay at the intravascular concentration expected after PC transfusion. However, the NHTRs after PC transfusion were not simply related to the RANTES level in PCs.

Basophils↗
PubMed2002

Expression of gap junction connexin36 in adult rat retinal ganglion cells.

Electrophysiological and ultrastructural studies have demonstrated that gap junctions connect diverse types of neurons in the central nervous system, permitting direct electrical and metabolic coupling. A member of gap junction channel subunit connexin36 (Cx36), is probed for the location of cell-to-cell communication in the mammalian retina, where gap junction networks of major classes of neurons are present. We present an analysis of the expression and localization of Cx36 protein in adult Wistar rat retina, using a newly generated polyclonal antibody against a sequence in the predicted cytoplasmic loop of the Cx36 amino acid alignment, deduced from the cDNA sequence. The affinity-purified antibody, recognizing a single 36-kDa protein, consistently labeled discrete puncta of subcellular structures likely to be associated with gap junctions in the inner plexiform layer, and also cytoplasm within somata and dendrites of retinal amacrine and ganglion cells, following examination with various fixation protocols and double labeling immuno-fluorescence. These results provide that prominent cell-to-cell communication appears in mature excitatory neurons such as retinal ganglion cells, in addition to inhibitory amacrine cells, mediated by gap junctions in the adult retina.

Amacrine Cells↗