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박정수,이효민,정용,신동천,노재훈,문영한,Park, J.S.,Lee, H.M.,Chung, Y.,Shin, D.C.,Roh, J.H.,Moon, Y.H. 대한예방의학회 1992 Journal of Preventive Medicine and Public Health Vol.25 No.1
This study was conducted to investigate the mechanism of protective effect by sodium selenite in methylmercuric chloride neurotoxicity, increasing intracellular $Ca^{2+}$concentration of the neuron. Methylmercuric chloride of 3mg/kg of body weight was administered simultaneously with sodium selenite of 5mg/kg and pretreatment of sodium selenite via intraperitoneal injection to rats. Also, effect of methylmercuric chloride($25{\mu}M,\;50{\mu}M,\;100{\mu}M$) and sodium selenite($200{\mu}M$) on free intrasynaptosomal $Ca^{2+}$ concentration were studied using the fluorescent $Ca^{2+}$ indicator fura -2 in vitro. After the treatment, at 6, 24, and 48 hours later, mercury in the cerebral cortex, liver and kidney tissues, succlnic dehydrogenase activities, adenosin-5'-triphosphate concentration, acetylcholinesterase activities, and intracellular $Ca^{2+}$ concentration in the cerebral cortex were determined in vivo. Cerebral synaptosomes of rats were incubated with methylmercuric chloride and sodium selenite in Hepes buffer for 10 minutes and free intrasynaptosomal $Ca^{2+}$ concentration were measured with fura-2 in vitro. The results were summarized as follows ; 1. The combined administration of $CH_3HgCl$ and $Na_2SeO_3$ and pretreatment of $Na_2SeO_3$ according to time significantly more increased in the cerebral cortex and decreased in the liver, kidney mercury concentrations compared to the administration of $CH_3HgCl$ only. 2. The combined administration of $CH_3HgCl$ and $Na_2SeO_3$ and pretreatment of $Na_2SeO_3$ increased more succinic dehydrogenase and acetylcholinesterase activities compared to the administration of $CH_3HgCl$ only. Particularly pretreatment of $Na_2SeO_3$ significantly more compared to the administration of $CH_3HgCl$ only. The concentration of adenosine-5'-triphosphate in $Na_2SeO_3$ treatment groups revealed a favourable effect compared to the administration of $CH_3HgCl$ only. 3. Intracellular $Ca^{2+}$ concentration in administration of $CH_3HgCl$ only was increased significantly more than control group in all test hours but was increased significantly more at 48 hours only after treatment in combined administration of $CH_3HgCl$ and $Na_2SeO_3$ and pretreatment of $Na_2SeO_3$ according to time interval more decreased significantly intracellular $Ca^{2+}$ concentration compared to the administration of $CH_3HgCl$ only. 4. Free intrasynaptosomal $Ca^{2+}$ concentration in the combined administration of $CH_3HgCl$ and $Na_2SeO_3$ was decreased ($24%{\sim}40%$) significantly more than the administration of $CH_3HgCl$ only. From the above results, the specific dosage of $Na_2SeO_3$ decreased increment of intracellular $Ca^{2+}$ concentration induced by administration of $CH_3HgCl$. These findings suggest the protective mechanism of $Na_2SeO_3$ on the neurotoxicity of $CH_3HgCl$.
[論文] 충격하중을 받는 유한평판의 3차원 동탄성이론에 의한 응력해석-충격하중 함수근사식의 제안을 중심으로-
양인영(I.Y.Yang),김선규(S.K.Kim),박정수(C.S.Park) 한국자동차공학회 1991 오토저널 Vol.13 No.5
In this paper, an attempt is made to analyze the impulsive stress directly underneath the concentrated impact point for a supported square plate by using the three-dimensional dynamic theory of elasticity and the potential theory of displacement (stress function) on the supposition that the load, F_0 sin ωt, acted on the central part of it.<br/> The results obtained from this study are as follows:<br/> 1. The impulsive stresses cannot be analyzed directly underneath the acting point of concenrated impact load in privious theories, but can be analyzed by using the three-dimensional<br/> dynamic theory of elasticity and the potential theory of displacement.<br/> 2. Theorically, with increasing the pulse width of applied load, it was possible to clarify that<br/> the amount of stress in the point of concentrated impact load was increased and that of stress per unit impulse was decreased.<br/> 3. The numerical inversion of laplace transformation by the use of the F.F.T algorithm contributes the reduction of C.P.U time and the improvement of the accuracy of results.<br/> 4. In this paper recommended, it is found that the approximate equation of impact load function P (τ)=Aτ exp(ㆍBτ), and P (τ)=O.85A exp (-Bτ) sinCτ could actually apply to all impact problem. In compared with the experimental results, the propriety of the analytical method is reasonable.