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Riboflavin Tetrabutylate가 약물대사 효소 및 지질 과산화효소에 미치는 영향
이향우,김원준,홍사석,곽창열,홍사오 大韓藥理學會 1980 대한약리학잡지 Vol.16 No.2
Lipid peroxidation in vitro has been identified as a basic deteriorative reaction in cellular mechanism of aging processes, such as air pollution oxidant damage to cell and to the lung, chlorinated hydrocarbon hepatotoxicity. Many experimental evidences were reported by several investigators that lipid peroxidation could be one of the principle causes for the hepatotoxicity produced by <TEX>$CCl_4$</TEX>. It is now reasonably established that <TEX>$CCl_4$</TEX> is activated to a free radical in vivo, that lipid peroxidation occurs very quickly in microsomes prepared from damaged livers, that the peroxidation is associated with loss of enzyme activity of microsomes, and that various antioxidants can protect animals against the hepatotoxic effect of <TEX>$CCl_4$</TEX>. Recent studies have drawn attention to some other feature of microsomal lipid peroxidation. Incubation of liver microsomes in the presence of NADPH has led to a loss of cytochrome <TEX>$P_{450}$</TEX>. However, the presence of an antioxidant prevented lipid peroxidation and preserved cytochrome <TEX>$P_{450}$</TEX>. Decrease of cytochrome <TEX>$P_{450}$</TEX> in microsomes under in vitro incubation can be enhanced by <TEX>$CCl_4</TEX> and these changes were parallel to a loss of microsomal polyunsaturated fatty acid and formation of malonaldehyde. The primary purpose of this experiment was to study the effect of riboflavin tetrabutylate on lipid peroxidation, specially, the relationship between lipid peroxidation and drug metabolizing enzyme system which is located in smooth endoplasmic recticulum as well as the effect of ritoflavin tetrabutylate on drug metabolizing enzyme system of animal treated with <TEX>$CCl_4$</TEX>. Albino rats were used for experimental animal. In order to induce drug metabolizing enzyme system, phenobarbital was injected intraperitoneally. <TEX>$CCl_$</TEX> and riboflavin tetrabutylate were given intraperitoneally as solution in olive oil. Microsomal fraction was isolated from
담즙분비와 Cyclic nucleotides간의 상호관계에 관한 연구
이향우,김원준,홍사석,조석준,홍사오,임중기,Lee, H.W.,Kim, W.J.,Hong, S.S.,Cho, S.J.,Hong, S.U.,Lim, C.K. 대한약리학회 1982 대한약리학잡지 Vol.18 No.1
Bile formation is a complex process comprised of three separate physiologic mechanism operating at two anatomical sites. At present time, it was known that at least two processes are responsible for total canalicular secretion at the bile canaliculus. One of the processes is bile salt-dependent secretion (BSDS) hypothesis that the active transport of bile salts from plasma to bile provided a primary stimulus for bile formation: the osmotic effect of actively transported bile acid was responsible for the movement of water and ions into bile. The other process is bile salt-independent secretion (ESIS), which is unrelated to bile salt secretion at the canaliculus and which may involve the active transport of sodium. The third process for bile formation involves the biliary ductal epithelium. Secretin-stimulated bile characteristically contained bicarbonate in high concentration. Therefor, it was suggested that secretin stimulated water and bicarbonate secretion from the biliary ductules. One the other hand, it was found that a large amounts of cAMP was present in canine bile but no apparent relationship between bile salt secretion and cAMP content in dog bile. However, bile flow studies in human have demonstrated that secretin and glucagon increase bile cAMP secretion as does secretin in baboons. Secretin increases baboon bile duct mucosal cAMP levels in addition to bile CAMP levels suggesting that in that species secretin-stimulated bile flow may be cAMP mediated. It has been postulated that glucagon and theophylline which increase the bile salt-independent secretion in dogs might act through an increased in liver cAMP content. In a few studies, the possible role of cAMP on bile formation has teen tested by administration of an exogenous derivative of cAMP, dibutyryl cAMP. In the rat, DB cAMP did not modify bile flow, but injection of DB cAMP in the dog promoted an increase in the bile salt-independent secretion. Because of these contradictory results, this study was carried out to examine the relationship between cyclic nucleotides and bile flow due to various bile salts as well as secretin or theophylline. Experiments were performed in rabbits with anesthesia produced by the injection of seconal(30 mg/kg). Rabbits had the cystic duct ligated and the proximal end of the divided common duct cannulated with an appropriately sized polyethylene catheter. A similar catheter was placed into the inferior vena cava for administration of drugs. Bile was collected for determination of cyclic nucleotides and total cholate in 15 min. intervals for a few hours. The results are summerized as followings. 1) Administrations of taurocholic acid or chenodeoxycholic acid increased significantly the concentrations of cAMP and cGMP in bile of rabbits. 2) Concentration of cAMP in bile during the continuous infusion of ursodeoxycholic acid, was remarkedly increased in accordance with the increase of bile flow, while on the contrary concentration of cGMP in bile was decreased significantly. 3) Dehydrocholic acid and deoxycholic acid significantly increased bile flow, total cholate output and cyclic nucleotides in bile. 4) Only cAMP concentration in bile was significantly increased from control value by secretin, while theophylline increased cAMP as well as cGMP in rabbit bile. 5) In addition, the administration of secretin to taurocholic acid-stimulated bile flow increased cAMP while theophylline produced the increases of cAMP and cGMP in bile. 6) The administration of insulin to taurocholic acid-stimulated bile flow decreased cAMP concentration, while on the contrary cGMP was remarkedly increased in rabbit bile.
스케일링 및 데이터 보존을 위한 2단자 사이리스터 랜덤 액세스 메모리 (T-RAM) 특성 분석
김향우(Hyangwoo Kim),조현수(Hyeonsu Cho),최민근(Minkeun Choi),공병돈(Byoung Don Kong),백창기(Chang-Ki Baek) 대한전자공학회 2020 대한전자공학회 학술대회 Vol.2020 No.8
2 terminal thyristor random-access memory (T-RAM) is investigated in terms of doping concentrations in the storage region to improve scalability and data retention time. When doping concentrations of N and P storage region are equal to each other at 1018 cm-3, T-RAM exhibits the highest retention time of 100 msec. In addition, it is proposed how to set the standby voltage in an energy-effective way. This standby voltage allows steady data retention of T-RAM with femto-scale leakage current until the erase operation is applied. Consequently, the proposed guideline can give a pathway to realize 2 terminal T-RAM as a promising capacitor-less DRAM technology.
Euglena의 Cytochrome C552 Methylation에 관한 연구
이향우(Hyang Woo Lee),백운기(Woon Ki Paik) 대한약학회 1988 약학회지 Vol.32 No.6
Post-translational modification of protein amino acid residues is a well known metabolic phenomenon. One such side chain modification, protein methylation, occur ubiquitously in nature, in organism ranging from prokaryotic to eukaryotic and the biological significance of protein methylation has begun to emerge. The observation that cytochrome C methylation facilitates the binding of this hemoprotein to mitochondria could be placed as the one of the examples along this line. However, the detail biological meaning of cytochrome C methylation is remained to be clarified. In the aspect of such reason this research was done. The results of this experiment were; 1) pure Euglena gracilis cytochrome C552 was isolated, 2) methylarginine and methylmethionine were not found in cytochrome C552 sequence, 3) however, Unknown Peak at 20.78 min of retention time was found, and 4) this Unknown Peak was found only from Euglena cytochrome C552, so far.
취외분비에 미치는 cyclic nucleotides의 역할
이향우,김원준,홍사석,Lee, H.W.,Kim, W.J.,Hong, S.S. 대한약리학회 1977 대한약리학잡지 Vol.13 No.2
In 1968, Case et al. first studied the importance of cyclic AMP as an intermediate in the action of secretin and cholecystokinin-pancreozymin and they suggested that the action of secretin, not that of cholecystokinin-pancreozymin, may be mediated through cyclic AMP. Recently Albano et al. reported that in the exocrine pancreas each of the two major physiological functions is modulated a specific cyclic nucleotide, enzyme secretion by cyclic GMP, and fluid and ionic secretion by cyclic AMP. But in pancreas still conflicting results have been reported on the role of cyclic nucleotides in enzyme and electrolyte secretion. In these study, the role of cyclic nucleotides in the exocrine pancreatic secretion was examined. The results are as follows. 1) Very strong stimulation on amylase release from guinea pig pancreatic slice was produced by 1 unit of cholecystokinin-pancreozymin but as compared to that of cholecystokinin-pancreozymin very weak response was observed by 1 unit of secretion or $1\;{\mu}g$ of VIP. 2) Both cholecystokinin-pancreozymin and acetylcholine produced a rapid and marked rise in cyclic GMP as well as cyclic AMP in isolated pancreatic tissue. However, both secretin and VIP failed to alter significantly the basal level of cyclic GMP in pancreatic fragments. 3) Atropine inhibited acetylcholine mediated amylase release, but did not affect the cholecystokinin-pancreozymin response. Furthermore, atropine pretreatment produced a marked inhibitory effect on the increase of tissue cyclic nucleotides induced by cholecystokinin-pancreozymin and acetylcholine. In summary, these results suggest that whereas the pancreatic secretion produced by secretin and VIP is modulated by the formation of cyclic AMP, the pancreatic enzyme secretion in response to cholecystokinin-pancreozymin and acetylcholine is triggered by both cyclic AMP and cyclic GMP.