S Kato

National Defense Medical College, Tokorozawa, Saitama, Japan

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Publications (59)269.41 Total impact

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    ABSTRACT: 1.4-Dihydroxy-2-naphthoic acid (DHNA), a bifidogenic growth stimulator from Propionibacterium freudenreichii, is thought to have a beneficial effect as a prebiotic; however, its in vivo effect on intestinal inflammation remains unknown. The aim of this study was to determine whether oral administration of DHNA can ameliorate dextran sodium sulphate (DSS) induced colitis and to determine the possible underlying mechanisms. Colitis was induced in mice by treatment with 2.0% DSS for seven days. DHNA (0.6 or 2.0 mg/kg) was given in drinking water prior to (preventive study) or after (therapeutic study) DSS administration. Colonic damage was histologically scored, and mucosal addressin cell adhesion molecule 1 (MAdCAM-1) expression and beta7 positive cell infiltration were determined by immunohistochemistry. mRNA levels of proinflammatory cytokines (interleukin (IL)-1beta, IL-6 and tumour necrosis factor alpha (TNF-alpha)) were determined by quantitative real time polymerase chain reaction. In addition, bacterial flora in the caecum, concentrations of short chain acids, and luminal pH were examined. DHNA improved survival rate and histological damage score in mice administered DSS in both the preventive and therapeutic studies. DHNA significantly attenuated the enhanced expression of MAdCAM-1, the increased beta7 positive cell number, and the increased mRNA levels of IL-1beta, IL-6, and TNF-alpha in DSS treated colon. In addition, the decreased number of Lactobacillus and Enterobacteriaceae induced by DSS was recovered by DHNA. Preventive effects on decrease in butyrate concentration and decrease in pH level in mice administered DSS were also observed in the DHNA preventive study. DHNA, a novel type of prebiotic, attenuates colonic inflammation not only by balancing intestinal bacterial flora but also by suppressing lymphocyte infiltration through reduction of MAdCAM-1.
    Gut 06/2006; 55(5):681-8. DOI:10.1136/gut.2005.070490 · 13.32 Impact Factor
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    ABSTRACT: The objective of this study was to determine whether specific adhesion molecules modulate lymphocyte movement from Peyer's patches into intestinal microlymphatics. The fluorochrome acridine orange was injected via a micropipette into Peyer's patches to fill lymphatics. The flux of labeled lymphocytes into intestinal microlymphatics was monitored with intravital fluorescence microscopy. The lymphatic microvessels in the perifollicular area of Peyer's patches were filled with lymphocytes, most of which remained within the lymphatics. Some lymphocytes became detached and were drained into intestinal lymph. Administration of antibodies directed against ICAM-1 significantly increased lymphocyte flux into interfollicular lymphatics. The immunohistochemical study showed intense ICAM-1 expression on the lymphocytes densely packed in the lymphatics surrounding follicles in Peyer's patches. A large number of lymphocytes are normally sequestered in the lymphatic network of Peyer's patches. This sequestration of lymphocytes is largely mediated by ICAM-1-dependent cell-cell interactions.
    Journal of Leukocyte Biology 01/2002; 70(6):896-902. · 4.30 Impact Factor
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    ABSTRACT: Human gastric mucosa contains three alcohol dehydrogenase (ADH) isozymes (classes I, III, and IV). Various factors such as Helicobacter pylori infection, sex, age, and the part of the stomach involved have been suggested to affect alcohol dehydrogenase activities, although these views are controversial. In this study, these unsettled issues were reexamined. Activities of class I and IV ADHs were evaluated in the cytosolic fraction of human gastric mucosa samples by reduction of their preferred substrates, namely acetaldehyde and m-nitrobenzaldehyde, and activities of class III were evaluated by oxidation of its preferred substrate, formaldehyde. Then, effects of Helicobacter pylori infection, sex, age, and the part of the stomach involved were examined. Class I, III, and IV ADH activities were 17.5 +/- 8.4, 4.2 +/- 2.5, and 8.9 +/- 3.9 nmol of nicotinamide adenine dinucleotide oxidation per minute per milligram of protein, respectively, for the entire population. Helicobacter pylori infection significantly reduced class I and IV ADH activities but did not affect activity of class III. In the samples without Helicobacter pylori infection and severe gastritis, sex did not affect class I, III, or IV ADH activities. In the same series, class IV ADH activity significantly decreased with age (p = 0.006), whereas no correlation was found between age and ADH activity of class I and III ADHs. The level of class IV ADH activity was significantly higher in the upper body than in the lower regions, whereas no such heterogeneity was observed in class I and III ADH. Various factors affect human gastric ADH activities, such that careful interpretation of their significance is necessary.
    Alcoholism Clinical and Experimental Research 07/2001; 25(6 Suppl):29S-34S. · 3.31 Impact Factor
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    ABSTRACT: Although the negative effect of excessive alcohol consumption on later stressful events has long been recognized, pathophysiological mechanisms are incompletely understood. We examined possible roles of oxygen radicals and glutathione content in mesenteric venules of chronically ethanol-fed rats exposed to ischemia-reperfusion. Changes in microvascular hemodynamics, such as red blood cell (RBC) velocity, leukocyte adherence, and albumin extravasation, were monitored in postcapillary venules by intravital fluorescence microscopy. Chronic ethanol feeding significantly exaggerated the magnitude of the decrease in RBC velocity, the increased number of adherent leukocytes, and increased albumin leakage elicited by 10 min of ischemia followed by 30 min of reperfusion. Oxidative stress in the endothelium of venules monitored by dihydrorhodamine 123 (DHR) fluorescence was more severe in rats fed ethanol chronically. Both superoxide dismutase and N-acetyl-L-cysteine, which is known to increase glutathione content, reduced the ischemia-reperfusion-induced decrease in RBC velocity, the number of adherent leukocytes, and the increase in albumin leakage, as well as oxidative activation of DHR. This suggests that the increased reperfusion-induced microvascular disturbances in the mesenteric venules of rats fed ethanol chronically are significantly correlated with excessive production of oxygen-derived free radicals and decreased glutathione synthesis.
    AJP Gastrointestinal and Liver Physiology 06/2001; 280(5):G939-48. · 3.74 Impact Factor
  • Gastroenterology 04/2001; 120(5). DOI:10.1016/S0016-5085(01)80125-6 · 13.93 Impact Factor
  • Gastroenterology 04/2001; 120(5). DOI:10.1016/S0016-5085(01)83530-7 · 13.93 Impact Factor
  • Gastroenterology 04/2001; 120(5). DOI:10.1016/S0016-5085(01)82600-7 · 13.93 Impact Factor
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    ABSTRACT: We evaluated the effect of 12 months of 300-mg oral sarpogrelate hydrochloride (SH) once daily on the symptoms of Raynaud's phenomenon, respiratory failure and cardiac function in seven patients with systemic sclerosis. Arterial blood gases, pulmonary function, mean pulmonary arterial pressure, left ventricular ejection fraction (LVEF), right ventricular ejection fraction (RVEF), white blood cell count, C-reactive protein and the plasma concentrations of fibrinopeptide A, beta-thromboglobulin, platelet factor 4 and thrombomodulin were evaluated before and 2 and 12 months after SH administration. After 2 and 12 months of SH administration, a significant decrease was found in the frequency and duration of Raynaud's phenomenon, as well as the coldness, numbness and pain of Raynaud's phenomenon. Respiratory failure, as estimated by Hugh-Jones classification, was significantly decreased, whereas the percentage carbon monoxide diffusion capacity was significantly increased. The mean pulmonary arterial pressure decreased significantly, as did plasma fibrinopeptide A, beta-thromboglobulin and platelet factor 4. There was no significant change in LVEF after 2 or 12 months, but after 12 months of SH administration, RVEF increased significantly. In conclusion, use of SH may prevent Raynaud's phenomenon, respiratory failure and right ventricular failure in patients with systemic sclerosis.
    The Journal of international medical research 12/2000; 28(6):258-68. DOI:10.1177/147323000002800602 · 1.10 Impact Factor
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    ABSTRACT: Mucosal addressin cell adhesion molecule-1 (MAdCAM-1) is an adhesion molecule that mediates recruitment of lymphocytes into the gut mucosa. Attenuation of excessive expression of MAdCAM-1 in the inflamed mucosa could be useful for treatment of inflammatory bowel diseases. The aim of this study was to investigate whether anti-MAdCAM-1 antibody has a prophylactic effect on experimental colitis induced by dextran sulfate sodium (DSS). Colitis was induced by orally feeding BALB/c mice 5% DSS (mol. wt. 5000). Mice were sacrificed at intervals up to 21 days after administration to evaluate the changes over time in intestinal damage. The infiltrating lymphocytes and their subpopulations, and the expression of cell adhesion molecules were determined by immunohistochemistry. In another set of experiments, the attenuating effect of i.p.-injected anti-MAdCAM-1 antibody on colonic lesions was evaluated on day 14. Significant histological damage with shortening of crypts was observed on day 14 in colonic mucosa of DSS-treated mice. Before mucosal inflammation had become significant, expression of MAdCAM-1 was already increased in the microvessels of lamina propria on day 7. Significant infiltration of beta7-integrin-positive T and B cells in the mucosa was then noted on day 14. Administration of anti-MAdCAM-1 antibody significantly reduced colonic injury as well as the infiltration of beta7-integrin-positive lymphocytes in the colonic mucosa. This antibody also was effective when given 7 days after the start of DSS treatment. In the present study, we demonstrated that anti-MAdCAM-1 antibody significantly ameliorates DSS-induced colitis, suggesting that MAdCAM-1 may be useful for control of inflammatory bowel diseases.
    Journal of Pharmacology and Experimental Therapeutics 11/2000; 295(1):183-9. · 3.86 Impact Factor
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    ABSTRACT: Different authors have postulated both toxic and protective effects for nitric oxide (NO) in the pathophysiology of active inflammation. To examine the role of NO, especially that produced by the inducible form of nitric oxide synthase (iNOS), by investigating the effects of NOS inhibitors and NO donors on inflammation in experimental acute colitis. Acute colitis was induced in rats by dextran sulphate sodium (DSS). White blood cell counts and levels of thiobarbituric acid reactants in the portal blood were determined, as were histological changes in the colonic mucosa. We then evaluated the effects of N(G)-nitro-L-arginine methyl ester (L-NAME), aminoguanidine (AG) and an NO donor on DSS-induced changes in these inflammatory parameters. Inhibition of NO production by either L-NAME or AG worsened DSS-induced inflammation, suggesting a protective role for NO in acute colitis. On the other hand, a NO donor also exaggerated DSS-induced inflammatory parameters, suggesting that acute colitis may be aggravated by either too much or too little NO. These results suggest that medical treatment of ulcerative colitis must aim for maintenance of appropriate NO levels in the intestinal mucosa.
    Alimentary Pharmacology & Therapeutics 05/2000; 14 Suppl 1(1):26-32. DOI:10.1046/j.1365-2036.2000.014s1026.x · 5.48 Impact Factor
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    ABSTRACT: Expression of two subtypes of 5-hydroxytryptamine (5-HT) receptors, 5-HT1B and 5-HT2A, was investigated in normal rat arteries (abdominal aorta) and veins (inferior vena cava) by the quantitative reverse transcription-polymerase chain reaction (RT-PCR). The arterial 5-HT2A receptor mRNA level in artery was 25-fold (p < 0.01) higher than the venous level, and the arterial 5-HT1B receptor mRNA level was at least 7000-fold (p < 0.005) higher the venous level.
    Molecular and Cellular Biochemistry 09/1999; 199(1-2):57-61. DOI:10.1023/A:1006999031932 · 2.39 Impact Factor
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    ABSTRACT: The FREEDOM O2 DC Concentrator, an oxygen concentrator which can be powered by a car battery, was evaluated. The oxygen concentrator was used by a 67 year-old man with sequelae of pulmonary tuberculosis who was receiving long-term oxygen therapy at home (HOT), and whose work required automobile trips over long distances. The equipment used was an adsorption-type oxygen concentrator capable of operating on a DC 12 V power supply, and which can be powered from a residential power outlet (AC 100 V) using a dedicated voltage converter. The trunk-shaped equipment measured 21/584 x 42 cm and weighed 17 kg. The noise level of the equipment was 58.2 +/- 2.5 dB (at 1 meter), and the flow rate can be set to 0.25, 0.50, 0.75, 1.0, 1.5, and 2.0 l/min. Results: 1) The O2 concentration which can be generated by this equipment is 93 +/- 3% (0.25 to 1.5 l/min) or 90 +/- 2.8% (2.0 l/min). 2) Using this equipment, the patient was capable of driving himself in comfort for two hours or longer. Further, it was possible to stay in a hotel during a trip, inhaling oxygen generated by the equipment. Hereafter, this equipment should enable or facilitate long-distance driving, travel and lodging for HOT patients.
    08/1998; 36(7):595-600.
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    ABSTRACT: Although it has been speculated that active oxidants and mitochondrial membrane damages play roles in ethanol-induced gastric mucosal damages, its detail remains unknown. The present study was designed to investigate whether ethanol induces oxidative stress and mitochondrial permeability transition (MPT) before cell death of gastric mucosal cells. Rat gastric mucosal cells (RGM-1) were kept in serum-free Dulbecco's modified Eagle's medium before addition of various concentrations of ethanol. Nuclear morphological aftemations and membrane barrier dysfunction of RGM-1 cells were assessed by staining with Hoechst 33342 and propidium iodide, respectively. To assess the contribution of oxygen-derived free radicals and intracellular glutathione, scavenger of hydrogen peroxide and the hydroxyl radical, N,N-dimethylthiourea, glutathione precursor, N-acetyl-L-cysteine, and an inhibitor of alcohol dehydrogenase, 4-methylpyrazole were added before treatment with ethanol. To investigate MPT, calcein and tetramethylrhodamine methyl ester were loaded before addition of ethanol, and the changes of fluorescence intensity were monitored using a laser scanning confocal microscope. Ethanol (>5% v/v) dose-dependently increased the number of propidium iodide-positive cells, suggesting a diminished barrier function of cell membrane. After addition of ethanol, mitochondria were filled quickly with calcein indicating MPT, which was accompanied by mitochondrial depolarization, as shown by loss of tetramethylrodamine methyl ester before cell death. Ethanol-induced cell death was significantly attenuated by simultaneous incubation with either N,N-dimethylthiourea or N-acetyl-L-cysteine, suggesting the importance of intracellular redox states in inducing cellular damage, whereas such change was not attenuated by 4-methylpyrazole. Present results suggest that ethanol treatment induces intracellular oxidative stress and produces MPT and mitochondrial depolarization, which are preceding cell death in gastric mucosal cells. Intracellular antioxidants, such as glutathione, may have a significant protective action against ethanol in gastric mucosal cells.
    Alcoholism Clinical and Experimental Research 06/1998; 22(3 Suppl):111S-114S. DOI:10.1097/00000374-199803001-00007 · 3.31 Impact Factor
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    ABSTRACT: Endotoxin is postulated to be an important aggravating factor for alcoholic liver disease. We have previously reported that rats fed ethanol are more vulnerable to endotoxin-induced liver damage, and hepatic microcirculatory disturbance plays an important role for this liver damage by observation with an intravital microscopy. In this study, we have investigated the role of adhesion molecules in endotoxin-induced microcirculatory disturbance in chronic ethanol-fed rats. Male Wistar rats were pair-fed with ethanol liquid diet (ethanol group) or an isocaloric control diet (control group) for 6 weeks. Leukocyte adherence to the hepatic sinusoid by stimulation with lipopolysaccharides (1 mg/kg of body weight) was observed by an inverted fluorescence microscopy equipped with a silicon-intensified target camera and was found to be enhanced in ethanol-fed rats. Tumor necrosis factor-alpha and GRO/CINC-1 (rat counterpart of interleukin-8) was increased in the blood in these animals. Subsequent expression of adhesion molecules, LFA-1 beta-chain on leukocytes were demonstrated by flow cytometry, which suggests a possible involvement of leukocyte adherence to the hepatic damage in ethanol-fed animals. Preadministration of anti-rat LFA-1 beta-chain monoclonal antibody effectively suppressed leukocyte adherence to the hepatic sinusoid. These results suggest that the enhanced sequestration of neutrophils to the liver with these adhesion molecules may play a significant role in the pathogenesis of alcoholic liver disease.
    Alcoholism Clinical and Experimental Research 06/1998; 22(3 Suppl):129S-132S. · 3.31 Impact Factor
  • Gastroenterology 04/1998; 114(4). DOI:10.1016/S0016-5085(98)85340-7 · 13.93 Impact Factor
  • Gastroenterology 04/1998; 114(4). DOI:10.1016/S0016-5085(98)85314-6 · 13.93 Impact Factor
  • Nippon Shokakibyo Gakkai zasshi The Japanese journal of gastro-enterology 02/1998; 95(1):60-5.
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    ABSTRACT: The role of leukocytes (WBCs) and platelets (PLTs) in the pulmonary circulation may be important in the development of monocrotaline (MCT)-induced pulmonary hypertension in rats. We investigated the changes in WBCs and PLTs in the pulmonary microvasculature during the development of chronic pulmonary hypertension in MCT rats by real-time confocal scanning laser microscopy. The number of WBCs sequestered in the pulmonary microvasculature increased significantly from day 7 after MCT injection, but no further increase occurred from days 14-28. The number of PLTs sequestered in the pulmonary microvasculature increased significantly from day 7 after MCT injection, and reached a peak on day 14. However, the number of PLTs sequestered on days 21 and 28 after MCT injection was significantly lower than on day 14. These findings suggest that PLTs mainly contribute to the initial and middle stages of the development of MCT-induced pulmonary hypertension in rats, while WBCs mainly contribute to the middle and late stages.
    International Journal of Microcirculation 11/1997; 17(6):290-7. DOI:10.1159/000179243
  • H Ishii, I Kurose, S Kato
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    ABSTRACT: Oxidative stress is well recognized to be a key step in the pathogenesis of ethanol-associated liver injury. Ethanol administration induces an increase in lipid peroxidation either by enhancing the production of oxygen reactive species and/or by decreasing the level of endogenous antioxidants. Numerous experimental studies have emphasized the role of the ethanol-inducible cytochrome P450 in the microsomes and the molybdo-flavoenzyme xanthine oxidase in the cytosol. This review shows the putative role of ethanol-induced disturbances in iron metabolism in relation to iron as a pro-oxidant factor. Ethanol administration also affects the mitochondrial free radical generation. Many previous studies suggest a role for active oxygens in ethanol-induced mitochondrial dysfunction in hepatocytes. Recent studies in our laboratory in the Department of Internal Medicine, Keio University, using a confocal laser scanning microscopic system strongly suggest that active oxidants generated during ethanol metabolism produce mitochondrial membrane permeability transition in isolated and cultured hepatocytes. In addition, acetaldehyde, ethanol consumption-associated endotoxaemia and subsequent release of inflammatory mediators may cause hepatocyte injury via both oxyradical-dependent and -independent mechanisms. These cytotoxic processes may lead to lethal hepatocyte injury. Investigations further implicate the endogenous glutathione-glutathione peroxidase system and catalase as important antioxidants and cytoprotective machinery in the hepatocytes exposed to ethanol.
    Journal of Gastroenterology and Hepatology 11/1997; 12(9-10):S272-82. · 3.63 Impact Factor
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    ABSTRACT: The precise pathogenic significance of oxidative injury in the evolution of alcohol-induced liver disease is still obscure. The present report was designed to investigate whether ethanol alters the production of active oxidants and biological activities of hepatocytes. The following parameters in rat hepatocytes were investigated by using fluorescence probes in vitro and ex vivo: (1) mitochondrial membrane potential and membrane permeability transition, (2) oxygen radicals generation, (3) membrane barrier function, and (4) glutathione level. Ethanol (50 mmol/L) increased oxidative stress in hepatocytes and subsequently induced an increased mitochondrial permeability transition and a decreased membrane potential. These ethanol-induced alterations were attenuated by an inhibitor of alcohol dehydrogenase and an intracellular oxidant scavenger, whereas they were enhanced by diethyl maleic acid, a glutathione depletor. Ethanol plus diethyl maleic acid but not ethanol alone increased the number of hepatocytes with membrane barrier dysfunction. A continuous infusion of ethanol (50 mmol/L) increased oxidative stress and decreased mitochondrial membrane potential in the pericentral area of isolated perfused rat liver. Active oxidants generated during ethanol metabolism increase mitochondrial permeability transition and modulate mitochondrial energy synthesis in hepatocytes. Reduction of glutathione level enhances mitochondrial dysfunction and impairs membrane barrier function of hepatocytes.
    Gastroenterology 05/1997; 112(4):1331-43. DOI:10.1016/S0016-5085(97)70147-1 · 13.93 Impact Factor

Publication Stats

999 Citations
269.41 Total Impact Points

Institutions

  • 2000–2006
    • National Defense Medical College
      • • Department of Internal Medicine
      • • Division of Medicine
      Tokorozawa, Saitama, Japan
  • 1992–2002
    • Keio University
      • Department of Internal Medicine
      Edo, Tōkyō, Japan
  • 1991–2000
    • Dokkyo Medical University
      • Division of Cardiology and Pneumology
      Totigi, Tochigi, Japan
    • Tottori University
      • Third Department of Internal Medicine
      TTJ, Tottori, Japan