| Project/Area Number |
01570048
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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 |
General physiology
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| Research Institution | Nara Medical University |
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Principal Investigator |
ENOKI Yasunori Nara Med. Univ., 2nd. Dept. Physiol., Professor, 医学部, 教授 (00075029)
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| Co-Investigator(Kenkyū-buntansha) |
SHIMIZU Satoshi Nara Med. Univ., 2nd. Dept. Physiol., Assistant, 医学部, 助手 (20216089)
OHGA Yoshimi Nara Med. Univ., 2nd. Dept. Physiol., Assistant, 医学部, 助手 (70094539)
SAKATA Susumu Nara Med. Univ., 2nd. Dept. Physiol., Assistant, 医学部, 助手 (20142383)
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| Project Period (FY) |
1989 – 1991
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| Project Status |
Completed (Fiscal Year 1991)
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| Budget Amount *help |
¥2,300,000 (Direct Cost: ¥2,300,000)
Fiscal Year 1991: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1990: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1989: ¥1,100,000 (Direct Cost: ¥1,100,000)
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| Keywords | Erythropoietin / Erythropoiesis / Hypoxia / Anemia / Kidney / Proximal convoluted tubule / Gentanicin / Erythroid colony inhibitory factor(s) / 低圧 / Gentamicin / ラット / マウス / 近位曲尿細菅 / 赤血球系コロニ-形成抑制因子 / ハイポチシア |
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| Research Abstract |
1. Reevalution and improvement of the microbioassay (FMLC) method for measuring plasma Epo. The microbioassay method, which had been developed and conventionally used in this laboratory, was critically reevaluated for its improvement with respect to sensitivity and reliability. The improvement was attained by 1) enrichment of CFU-E density in the fetal mouse liver cell suspension using Ficoll-Paque treatment, 2) by establishment of 'clonality' of, the erythroid colonies formed from 1-7.5xlO^3 cells plated per well and 3) by acid-boiling pretreatment of plasma to eliminate the erythroid colony inhibitory activity (ECIA). rHuEpo was found to be the most reliable Epo standard.
2. Quantitative relationship between Epo and the Epo activity assayed by FKLC method. Using a monoclonal antibody raised against rHuEpo, we found that about 20% of the assayed Epo activity was-due to nonspecific erythroid stimulating activity other than Epo. However, hypoxia-induced elevation of Epo activity was conc
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luded to be almost entirely due to Epo itself, since the nonspecific factor remained almost constant under hypoxic conditions.
3. Renal lesion by gentanicin and Epo response to hypoxic or anemic hypoxia in rats. Anesia-induced plasma Epo increase, which was normally observed in anesic patients with normal renal function, was not observed in patients of chronic renal failure at all. When rats were exposed to a sustained hypobaric (0.35 ats.) hypoxia, plasma Epo level showed a rapid elevation, attaining the peak after 6 h and then turned out to decline to recover the prehypoxic level after 24 h. The peak value was approximately 4 fold the prehypoxic level. Anemia, in which average blood b concentration was reduced by 40%, also induced similar but more pronounced Epo response. This response of Epo to hypoxia was dose-dependently depressed by gentanicin and almost entirely disappeared by a continued administration of the dose of 67.50 mg/Kg body weight/day for 14 days. Histological examinations disclosed that gentanicin induced renal tissue lesion of various degrees, from cloudy swelling to focal necrosis, limited to the proximal convoluted tubular region, and severity of the damage appears to depend on the dose. All these findings strongly support the idea that the proximal convoluted tubular region is closely involved in the hypoxia-induced production of Epo no matter how it is directly or indirectly through the 'oxygen sensing' sechaniss.
4. Possible cooperation of erythroid stimulatory (Epo) and inhibitory factors in physiological regulation of erythropoiesis. A linear reciprocal relationship (r=-0.71) was found between plasea Epo and erythroid inhibitory activities in anemic patients without renal failure. This connotes that physiological erythropoiesis is regulated by a cooperation of the both factors. Less
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