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박응철,이장식,박정호,이병일,주승기 한국세라믹학회 2000 한국세라믹학회지 Vol.37 No.5
Effects of Ar ion damage prior to the phase transformation from pyrochlore to perovskite structure of PZT thin films have been investigated. As the degree of damage increased by increasing the acceleration voltage in the ion mass doping system, the phase transformation temperature decreased such that the temperature could be lowered down to 550$^{\circ}C$ when the film was damaged at 15 kV for 5 minutes. When the film was damaged prior to the heat treatment grain size of the perovskite thin films became less than 300${\AA}$. It turned out that relatively high value of the remanent polarization (about 30${\mu}$C/$\textrm{cm}^2$) as well as improvement of the fatigue characteristics to a large extent is closely related to the fine grain size of thus obtained PZT films.
배양한 흰쥐 해마신경세포에서 항우울제에 의한 c-fos mRNA의 발현
박응철,조연규,양병환,김광일,양보기,채영규,Park, Eung-Chul,Cho, Yun-Gyoo,Yang, Byung-Hwan,Kim, Kwang-Iel,Yang, Bo-Gee,Chai, Young-Gyu 대한생물정신의학회 2001 생물정신의학 Vol.8 No.1
This study was designed to examine the effects of two antidepressant drugs on the expression of c-fos mRNA in cultured embryonic rat hippocampal neurons. The drugs used were imipramine and amitriptyline. On the fourth day of culture, hippocampal neurons were treated with variable concentrations of each drug. Competitive RT-PCR(Reverse Transcriptase-PCR) analysis was used to quantify the c-fos mRNA expression induced by each drug. Experimental results showed that acute and direct treatment with imipramine and amitriptyline with relatively low concentrations(imipramine ${\leq}10{\mu}M$, amitriptylne ${\leq}10{\mu}M$) had no inductive effect on the expression of c-fos mRNA in the rat hippocampal neurons. However, after treatment with relatively high concentrations(imipramine ${\geq}100{\mu}M$, amitriptyline ${\geq}100{\mu}M$) c-fos mRNA was not detected. These findings suggest the followings. Firstly, the action mechanisms of these drugs on the hippocampal neurons might not be mediated by c-fos but by other immediate-early genes(IEGs). Secondly, their actions may be mediated indirectly via other areas of the brain. Thirdly, the expression of c-fos might be inhibited by high concentrations of these drugs, or the high concentrations could induce cell death. Finally, though cell death remains to be confirmed, the inhibition of c-fos induction or cell death could play a role in the cognitive impairments known to be adverse effects of some antidepressants. This study is believed to be a first step toward understanding the mechanisms of learning and memory. Further studies are needed to investigate the expression of various IEGs and changes in the hippocampal neurons of rat resulting from chronic treatment with antidepressant drugs.
정신분열병환자의 혈소판막과 ³H-spiperone결합에 관한 연구
양병환,박응철,정하승 大韓神經精神醫學會 1989 신경정신의학 Vol.28 No.5
This research was to determine whether changes of dopamine receptors on the platelet membrane of schizophrenics could be used as a biological marker for schizophrenia. ³H-spiperone binding to platelet membranes was carried out in 22 schizophrenic patients who fulfilled DSM-ⅢR criteria and 14 age-matched control subjects. ³H-spiperone specifically binds to dopamine D2 receptor with high affinity. Increased Bmax can suggests increase in the number of dopamine receptors on the platelet membrane. The results are as follows ; 1) Bmax of the patient group was significantly higher than that of control group(p<.05). 2) Kd was not significantly different between the two groups. 3) Bmax of the positive and the negative symptom groups were significantly higher than the control group when the patient group was subdivided into the positive, the negative and the mixed symptom groups(p<0.5). 4) Kd of the positive symptom groups, the negative symptom groups and the control group were not significantly different among each other. 5) Bmax and Kd of the positive and the mixed and the negative symptom groups were not significantly different among each other. This results shows that increase in the number of depamine receptors on the platelet membrane of schizophrenics would be a part of disease process in schizophrenia.