| Project/Area Number |
04454240
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Gastroenterology
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| Research Institution | University of Tokyo |
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Principal Investigator |
FUJIWARA Kenji Univ.of Tokyo, Fac.Of Med., Lecturer, 医学部(病), 講師 (80101088)
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| Co-Investigator(Kenkyū-buntansha) |
TOMIYA Tomoaki Univ.of Tokyo, Fac.Of Med., Senior Resident, 医学部(病), 医員 (90227637)
NAGOSHI Sumiko Univ.of Tokyo, Fac.Of Med., Senior Resident, 医学部(病), 医員
HIRATA Keiichi Univ.of Tokyo, Fac.Of Med., Assistant Professor, 医学部(病), 助手 (50199064)
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| Project Period (FY) |
1992 – 1993
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| Project Status |
Completed (Fiscal Year 1993)
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| Budget Amount *help |
¥6,900,000 (Direct Cost: ¥6,900,000)
Fiscal Year 1993: ¥1,600,000 (Direct Cost: ¥1,600,000)
Fiscal Year 1992: ¥5,300,000 (Direct Cost: ¥5,300,000)
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| Keywords | Hepatocyte plasma membrane / Hepatocyte growth factor / liver regeneration / Putrescine / TGFbeta / 劇症肝炎 |
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| Research Abstract |
Our previous observations show that rat plasma membrane has the ability to enhance induction of DNA synthesis by hepatocyte growth factors in cultured rat hepatocytes. The present study was attempted to purify this comitogenic factor from plasma membrane of rat hepatocytes and find its action sites. The following results have been so far obtained.
1.Purification
The comitogenic activity was extracted by collagenase digestion of the plasma membrane of rat hepatocytes partially purified according to the method of Hubbard et al., but the yield was too small to use for further purification by electrophoresis and column preparations. Although the yield was increased to 50% of the original activity by extraction with acetone, n-butanol or CHAPS,most of the activity was lost after column preparations with ion exchange resins. Antiserum against such extracts made using rabbits inhibited DNA synthesis by cultured rat hepatocytes, but immunoblot analysis revealed a lot of bands in the antiserum. To obtain hybridoma for a monoclonal antibody against the factor has not yet been successful.
2.Action site(s)
The plasma membrane increased concentrations of putrescine, an essential polyamine for hepatocyte proliferation, in cultured rat hapatocytes, while it abolished completely the decrease in DNA synthesis by the hepatocytes induced by ddition of TGF beta. When rats underwent 70% hepatectomy, the comitogenic activity in the liver was gradually decreased after 6 hr and disappeared at 24 hr, but recovered to normal levels at 31 hr. The comitogenic factor might act at the G1-phase of the cell cycle in association with putrescine production, and be inactivated or consumed during exerting its action.
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