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기니피그 위저부 윤상근의 비아드레날린성 비콜린성 반응에 관한 연구
황일순(Il Soon Whang),송치욱(Chi Wook song),강동훈(Dong Hoon Kang),이홍식(Hong Sik Lee),이상우(Sang Woo Lee),최재현(Jae Hyun Choi),김창덕(Chang Duck Kim),류호상(Ho Sang Ryu),현진해(Jin Hae Hyun) 대한소화기학회 1997 대한소화기학회지 Vol.29 No.4
N/A Background/Aims: The neurogenic responses of gastrointestinal smooth muscles to electrical field stimulation(EFS) is biphasic, consisting firstly of cholinergic contraction, followed by a transient relaxation. It is well known that a transient relaxation does involve the inhibitory non- adrenergic non-cholinergic(NANC) systems. However, the exact nature of the neurotransmitter released by these neurons is controversial. This study was done to investigate the relaxing agents and their action mechanisms by the use of organ bath with platinum electrodes. Methods: In 10 guinea-pigs, muscle strips of fundus, 10mm x 2mm, were prepared in a circular axis. Isometric tension study was performed in 30ml organ baths containing Krebs bicarbonate buffer, tnaintatined at 37 'C and gassed with 5% CO and 95% Oz. Results: The fundic relaxation by EFS was suppressed by NG-nitro-L-arginine methyl ester(L-NAME) and nitric oxide(NO) synthase inhibitor, in a dose-dependent manner and these effects were reversed by L-arginine, precurssar of NO. Nitroprusside, NO-donor, suppressed the fundic basal tension largely. Methylene blue, inhibitor of guanylate cyclase, suppressed the fundic basal tension and decreased EFS-induced relaxations. Forskolin and isoprenaline, which are activators of adenylate cyclase, suppressed the fundic basal tension as rnuch as nitroprusside. Intracellularly permeable cGMP and cAMP pro- duced relaxations in the precontracted fundic muscle with noradrenaline. TEA, non-specific K' channel blocker, and aparnin, Ca ' activated K' channel blocker, increased the fundic basal tension and EFS-induced relaxations. Conclusions: Above results indicate that NO is released upon stimulation of the NANC nerves in the guinea-pig fundic muscle and play a major role in the receptive relaxation of the fundus region. The release of NO is related with K' channel, and some other inhibitory agents may be involved in transient relaxation through modulative effects on cAMP or cGMP. (Korean J Gastroenterol 1997;29:430-441)
토양에서 분리된 Xanthomonas sp. 의 Chitinase 유전자 cloning 과 E.coli 에서의 발현
황철원,김호상,성기영,은무영 ( Cher Won Hwang,Ho Sang Kim,Ki Young Seong,Moo Young Eun ) 한국응용생명화학회 1998 Applied Biological Chemistry (Appl Biol Chem) Vol.41 No.2
Xanthomonas sp. isolated from soil exhibited cell wall lytic activity of Candida albicans and secreted chitinase in chitin media. Especially, the chitinase activity was induced by chitin and reached a maximum level at 3 days culture in chitin media. We constructed genomic library of Xanthomonas sp. using cosmid vector in E. coli. Oligonucleotide probe, was synthesized from the consensus sequence corresponding to chitinase active site, which was derived from the comparison of amino acid sequences of bacterial chitinase genes. Using this oligonucleotide probe, we screened the genomic library. By restriction enzyme mapping of the positive clones, we identified 4 independent clones which may contain the chitinase gene. One of the clones, named pXCH1 (1.2 kb insert), was further analyzed. Northern blot analysis indicated that is transcripts, 1 kb and 0.8 kb, were induced by chitin. When the cloned gene was induced by IPTG in E.coli cell, chitinase activity which was secreted onto culture media was not observed. However, when the cell was disrupted by using sonicator and then centrifuged, the supernatant exhibited chitinase activity. SDS-PAGE of the supernatant indicated that about 35 kDa protein was induced by IPTG. From these results, it was concluded that the cloned DNA was one of the chitinase genes of Xanthomonas sp.