| Project/Area Number |
61570687
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Cerebral neurosurgery
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| Research Institution | Akita University |
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Principal Investigator |
MINEURA Katsuyoshi Department of Neurosurgery, Akita University School of Medicine, 医学部, 講師 (70134103)
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| Project Period (FY) |
1986 – 1988
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| Project Status |
Completed (Fiscal Year 1988)
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| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1988: ¥300,000 (Direct Cost: ¥300,000)
Fiscal Year 1987: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1986: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Keywords | brain / brain tumors / highly reiterated DNA / DNA sequencing / DNA damage / DNA損傷 / 抗癌剤 / グリア細胞 / 脳腫瘍細胞 / 脳細胞 / DNA / DNA回復酵素 |
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| Research Abstract |
The highly reiterated DNA sequence from brain or brain tumors was used to determine the presence and types of DNA damage that involve the CNS oncogenesis. Hind III-Hae III DNA fragments from rat brain or glioma cells were easily separated and were suitable for detection of the DNA damaged sites, while EcoRIEcoRI^* fragments were purified from human brain tumors. These defined and known repetitive sequences have been convenient targets to determine the DNA damage or DNA binding site of antitumor drugs. In vitro reaction with nitrosoureas such as ACNU and MCNU resulted in scission products corresponding to the locations of guanine. Subsequent piperidine hydrolysis produced more frequent breaks of the phosphodiester bonds at guanine positions, thus forming labile sites. Bleomycin (BLM) showed strand scissions in guanine-cytosine and guanine-thymine sequences of a defined fragment, potentiated by 2-mercaptoethanol.
It has been shown that neocarzinostatin (NCS) with 2-mercaptoethanol added breaks DNA fragments at thymine positions and, to a lessor extent, at adenine positions. Sequencing reaction were performed according to the procedure of Maxam and Gilbert, modified to include piperidine and enzymic reactions of M. leteus extract as probes for DNA damages. Sequencing gels did not reveal DNA damages or midifications in DNA isolated from rat brain or from buman brain tumors. Therefore,DNA damages or modifications detectable by this method accumulated in rat brain or human brain tumors. This indicate that either such damaged sites are not formed, or that the capacity to repair them remains efficient in rat brain and human tumor. Further extension of this method will elucidate the role of DNA damages in the CNS oncogenesis using various types of purified DNA-repair enzymes, and offer a rationale for chemotherapy in the treatment of malignant brain tumos.
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