Faculty Profiles - YOKOTA Kenji

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Helicobacter pyloriのHSP60の発現と生物活性の検討

横田憲治, 石井栄子, 綾田潔, 平井義一, 林俊治, 藤永由佳子, 小熊惠二

日本細菌学雑誌 54 ( 1 ) 212 - 212 1999.2

船守有香, 横田憲治, 藤永由佳子, 井上薫, 小熊惠二

日本細菌学雑誌 54 ( 1 ) 203 - 203 1999.2

Gastric ulcers in SCID mice induced by Helicobacter pylori infection after transplanting lymphocytes from patients with gastric lymphoma

YOKOTA K

Gastroenterology 117 893 - 899 1999

Structure and function of Clostridium botulinum progenitor toxin

K Oguma, K Inoue, Y Fujinaga, K Yokota, T Watanabe, T Ohyama, K Takeshi, K Inoue

JOURNAL OF TOXICOLOGY-TOXIN REVIEWS 18 ( 1 ) 17 - 34 1999

Language：English Publisher：MARCEL DEKKER INC

Clostridium botulinum strains produce seven immunologically distinct neurotoxins (NTX), type A to G. The NTXs associate with nontoxic components in cultures, and become large complexes with three forms (128, 16S, and 19S) designated progenitor toxins. The 12S toxin consists of a NTX and a nontoxic component having no hemagglutinin (HA) activity (described here as non-toxic non-HA, NTNH), and the 168 and 19S toxins are formed by conjugation of the 12S toxin with HA. Based on the genetic- and protein chemical-analyses of the progenitor toxins it became clear that 1) the HA consists of four subcomponents namely HA1 (Mr. 33 similar to 35 kDa), HA2 (15 similar to 17 kDa), HA3a (19 similar to 23 kDa), and HA3b (52 similar to 53 kDa), 2) the genes coding for NTX (ntx), NTNH (ntnh), and HA (ha) occur as a cluster; ha lies just upstream of ntnh, and ntx lies just downstream of ntnh, 3) ha is in the opposite orientation from that of ntnh and ntx, 4) ha consists of three ORFs (ha1, ha2, and ha3), 5) the gene product (70 kDa) of ha3 is split into HA3a and HA3b after translation, 6) HA3a is cleaved at several different sites of its N-terminal region to form proteins with slightly different Mrs, 7) the 19S toxin is a dimer of 16S toxin crosslinked by HA1, 8) The NTNHs of type A to D 12S toxins have a cleavage(s) on their N-terminal regions. It also became clear that the HA prays an important role when the 16S land 19S) toxin is absorbed from the small intestine.

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Classification of Clostridium butyricum based on sodium dodecyl sulfate polyacrylamide gel electrophoresis and pulsed-field gel electrophoresis

K Yokota, Y Fujinaga, K Inoue, S Shimazaki, G Seo, K Takeshi, E Nagamachi, K Oguma

ANAEROBE 4 ( 4 ) 177 - 181 1998.8

Language：English Publisher：ACADEMIC PRESS LTD

Eleven strains of Clostridium butyricum collected from different sources were analysed by both sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and pulsed-field gel electrophoresis (PFGE). The strains could be classified into four groups based on their banding profiles of the proteins extracted from the cells on SDS-PAGE. Group I consisted of seven strains, and these strains were further divided into five subgroups by PFGE. The strains belonging to groups II, III, and IV on SDS-PAGE were also classified into the same II to IV groups by PFGE. These data indicate that grouping of the strains of C. butyricum can be performed by employing both SDS-PAGE and PFGE. (C) 1998 Academic Press.

DOI： 10.1006/anae.1998.0163

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Effect of rebamipide, a novel antiulcer agent, on Helicobacter pylori adhesion to gastric epithelial cells

S Hayashi, T Sugiyama, KI Amano, H Isogai, E Isogai, M Aihara, M Kikuchi, M Asaka, K Yokota, K Oguma, N Fujii, Y Hirai

ANTIMICROBIAL AGENTS AND CHEMOTHERAPY 42 ( 8 ) 1895 - 1899 1998.8

Language：English Publisher：AMER SOC MICROBIOLOGY

Helicobacter pylori is a major etiological agent in gastroduodenal disorders. The adhesion of H. pylori to human gastric epithelial cells is the initial step of H. pylori infection. Inhibition of H, pylori adhesion is thus a therapeutic target in the prevention of H, pylori infection. Experiments were performed to evaluate the effect of rebamipide, a novel antiulcer agent, on H. pylori adhesion to gastric epithelial cells. MKN-28 and MKN-45 cells, derived from human gastric carcinomas, were used as target cells. Ten H. pylori strains isolated from patients with chronic gastritis and gastric ulcer were used in the study. We evaluated the effect of rebamipide on H. pylori adhesion to MKN-28 and MKN-45 cells quantitatively using our previously established enzyme-linked immunosorbent assay. The adhesion of H. pylori to MKN-28 and MKN-45 cells was significantly inhibited by pretreatment of these cells with 100 mu g of rebamipide per mi. However, the adhesion was not affected by the pretreatment of H. pylori with rebamipide. On the other hand, the viabilities of H. pylori, MKN-28 cells, and MKN-45 cells were not affected by rebamipide, Our studies suggest that rebamipide inhibits the adhesion of H. pylori to gastric epithelial cells.

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ボツリヌス毒素

小熊惠二, 井上薫, 藤永由佳子, 横田憲治, 武士甲一, 大山徹, 池田徹也, 渡部俊弘, 井上勝弘

Modern Media 44 ( 7 ) 9-18,213-222 - 222 1998.7

Helicobacter pyloriのワクチン療法 (特集 Helicobacter pyloriの基礎と臨床)

小熊恵二, 横田憲治, 平井義一

診断と治療 86 ( 1 ) 89 - 94 1998.1

The haemagglutinin of Clostridium botulinum type C progenitor toxin plays an essential role in binding of toxin to the epithelial cells of guinea pig small intestine, leading to the efficient absorption of the toxin

Y Fujinaga, K Inoue, S Watanabe, K Yokota, Y Hirai, E Nagamachi, K Oguma

MICROBIOLOGY-UK 143 3841 - 3847 1997.12

Language：English Publisher：SOC GENERAL MICROBIOLOGY

Binding of the purified type C 7S (neurotoxin), 12S and 16S botulinum toxins to epithelial cells of ligated small intestine or colon of the guinea pig (in vivo test) and to pre-fixed gastrointestinal tissue sections (in vitro test) wasanalysed. The 165 toxin bound intensely to the microvilli of epithelial cells of the small intestine in both in vivo and in vitro tests, but did not bind to cells of the stomach or colon. The neurotoxin and 12S toxin did not bind to epithelial cells of the small intestine or to cells of the stomach or colon. Absorption of the toxins was assessed by determining the toxin titre in the sera of guinea pigs 6-8 h after the intra-intestinal administration of the toxins. When the 165 toxin [1 x 10(5) minimum lethal dose (MLD)] was injected, 200-660 MLD ml(-1) was detected in the sera, whereas when the 12S toxin (2 x 10(5) MLD) or 7S toxin (2 x 10(5) MLD) was injected, little toxin activity was detected in the sera. Therefore, the haemagglutinin of type C 16S toxin is apparently very important in the binding and absorption of botulinum toxin in the small intestine.

DOI： 10.1099/00221287-143-12-3841

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Effect of ecabet sodium on Helicobacter pylori adhesion to gastric epithelial cells

HAYASHI Shunji, SUGIYAMA Toshiro, YACHI Akira, YOKOTA Kenji, HIRAI Yoshikazu, OGUMA Keiji, FUJII Nobuhiro

32 ( 5 ) 593 - 597 1997.10

ボツリヌス神経毒素-無毒成分複合体の構造と機能

井上薫, 藤永由佳子, 横田憲治

蛋白質核酸酵素 42 ( 13 ) 2049 - 2060 1997.10

Helicobacter pylori. Prospects on development of Helicobacter pylori vaccine.

OGUMA KEIJI, HIRAI YOSHIKAZU, YOKOTA KENJI

臨床検査 41 ( 2 ) 185 - 188 1997.2

Structure and function of Clostridium botulinum progenitor toxins

K. Inoue, Y. Fujinaga, K. Yokota, K. Oguma

Tanpakushitsu kakusan koso. Protein, nucleic acid, enzyme 42 ( 13 ) 2049 - 2060 1997

Helicobacter pylori and gastroduodenal disease

K Yokota, Y Hirai, K Oguma

JAPANESE JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH 42 ( 3 ) 193 - 209 1996.6

Language：Japanese Publishing type：Book review, literature introduction, etc. Publisher：PHARMACEUTICAL SOC JAPAN

Helicobacter pylori is a gram negative spiral bacterium, which is colonized in human gastric mucosa. This organism was first reported in Australia, 1983. Now H. pylori has been recognized to cause chronic active gastritis, and is a major factor in the pathogenesis of duodenal ulcer and gastric ulcer. It was also reported that its infection is a risk factor for both MALT (mucosa associated lymphoid tissue) lymphoma and gastric adenocarcinoma.
H. pylori has many virulence factors. Urease is one of the most important colonization and virulence factors studied. Ammonia made by urease protects the organisms from gastric low pH, and is toxigenic to gastric epithelial cells. Vacuolating toxin and CagA proteins are thought to be pathogenic agents especially for causing gastric and duodenal ulcers. Neutrophil reactions against the bacteria, and the abnormal immunological reactions are also considered to cause the damage of gastric epithelial cells, although the detailed pathogenic mechanisms are still not clear.
In developing countries, infection by H. pylori is established in childhood, and the organisms can be identified in the mouth and feces, indicating its infection through water.
The infected organisms can be eradicated by administration with proton pump inhibitor and one or two antibiotics. This may provide an useful therapeutic means to the patients especially with recurrent ulceration and MALT lymphoma.

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Quantitative detection of secretory immunoglobulin a to Helicobacter pylori in gastric juice: Antibody capture enzyme-linked immunosorbent assay

S Hayashi, T Sugiyama, K Hisano, T Awakawa, Kurokawa, I, A Yachi, H Isogai, E Isogai, K Yokota, Y Hirai, K Oguma, N Fujii

JOURNAL OF CLINICAL LABORATORY ANALYSIS 10 ( 2 ) 74 - 77 1996

Language：English Publisher：WILEY-LISS

Helicobacter pylori is a major etiologic agent in gastroduodenal disorders. In this study, immunoglobulin A (IgA) antibodies to H. pylori were estimated in serum and gastric juice specimens from patients with gastritis and peptic ulcers using antibody capture enzyme-linked immunosorbent assays (ACELISAs). The antibody titers of the ACELISAs are independent of the antibody concentration and reflect the ratio of H. pylori-specific IgA to total IgA. The ratio is stable, although the antibody concentration fluctuates in gastric juice. Using the ACELISAs it was possible to evaluate quantitatively not only serum IgA (SR-IgA) antibodies but also secretory IgA (SC-IgA) antibodies in gastric juice. There were significant differences between the patients and control group in the SR-IgA and SC-IgA ACELISAs. Furthermore, the ACELISAs made it possible to compare between SR-IgA antibodies in serum and SC-IgA antibodies in gastric juice. In all patients, the ratios of H. pylori-specific IgA were higher in gastric juice than in serum. These results suggest that H. pylori SC-IgA antibodies are mainly produced by the local immune response in the gastric mucosa. Our studies indicate that ACELISA is well suited for the analysis of local immune response in mucosa. (C) 1996 Wiley-Liss, Inc.

DOI： 10.1002/(SICI)1098-2825(1996)10:2<74::AID-JCLA3>3.0.CO;2-L

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Characterization of Streptococcus sanguis Isolated from Patients with Behcet's Disease

YOKOTA Kenji, HAYASHI Shynji, ARAKI Yoshio, ISOGAI Emiko, KOTAKE Satoshi, YOSHIKAWA Kouji, FUJII Nobuhiro, HIRAI Yoshikazu, OGUMA Keiji

Microbiol Immunol 39 ( 9 ) 729 - 732 1995.9

スナネズミおよびマウスを用いる感染実験モデル． Helicobacter pylori と胃粘膜障害

磯貝浩, 磯貝恵美子, 横田憲治, 小熊恵二

日本臨床 51 ( 12 ) 3183 - 3143 1993

Development and Evaluation of Capture Enzyme-Linked Immunosorbent Assays for Detection of Immunoglobulin G and M Antibodies to Group A Streptococcal Antigens

Hayashi Shunji, Yokota Kenji, Takizawa Yoshihiko, Tomizawa Isao, Nejime Tetsuya, Oguma Keiji

Japanese Journal of Microbiology 37 ( 4 ) 271 - 279 1993

Language：English Publisher：Center For Academic Publications Japan

Capture enzyme-linked immunosorbent assays (ELISAs) were developed to detect immunoglobulin G and M antibodies to group A streptococcal (GAS) antigens, streptolysin O, streptokinase, and group A carbohydrate. The sensitivities and the specificities of the IgM capture ELISAs to each GAS antigen were high enough to distinguish the patients with GAS infections (diagnosed as GAS pharyngitis or scarlet fever) from the control groups (healthy people and patients with pharyngitis from whom GAS could not be isolated). On the other hand, the specificities of the IgG capture ELISAs were not very effective in diagnosis of GAS infections. When the capture ELISA and an indirect ELISA detecting IgM antibodies to group A carbohydrate were compared, false-positive reactions due to rheumatoid factor occurred in the indirect ELISA, but did not occur in the capture ELISA. These results indicate that the capture ELISA works better than the indirect ELISA in detecting the IgM antibody, and that the IgM capture ELISA to GAS antigen provides a rapid and highly reliable serodiagnosis for GAS infections employing only a single serum.

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Demonstration of antigen-specific immune response against Streptococcus sanguis

Norihisa Ishii, Emiko Isogai, Yuko Yamakawa, Hiroshi Nakajima, Shigeaki Ohno, Hiroshi Isogai, Shunji Hayashi, Kenji Yokota, Keiji Oguma

Journal of Dermatological Science 5 ( 3 ) 182 - 189 1993

Language：English

The genetic control of Streptococcus sanguis antigen response was studied. Mice sensitized with inactivated S. sanguis organisms antigen-injected at the base of the tail developed footpad swelling. Those with an I-Ak,q,r region of H-2 showed a strong footpad response, whereas those with an I-Ab,d,s region showed a weak response to S. sanguis cell wall antigen. Footpad response was mediated by CD4+, 8- T cells by using in vitro monoclonal antibody treatment. Similar evidence of genetic control was obtained with an in vitro T cell proliferation assay. However, quantitation of antibodies against S. sanguis showed that antibody production was not controlled by H-2. These results indicated that both in vivo footpad swelling and in vitro T cell proliferation responses were functions of helper (CD3+, 4+, 8-) T cells and controlled by the I-A region of H-2. © 1993.

DOI： 10.1016/0923-1811(93)90765-H

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A NOVEL ENZYME-IMMUNOASSAY FOR SERODIAGNOSIS OF HELICOBACTER-PYLORI INFECTION

T SUGIYAMA, K IMAI, H YOSHIDA, Y TAKAYAMA, T YABANA, K YOKOTA, K OGUMA, A YACHI

GASTROENTEROLOGY 101 ( 1 ) 77 - 83 1991.7

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