• Journal of the East Asian Society of Dietary Life
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• v.23 no.3
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• pp.311-319
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• 2013

The purpose of the present study is to investigate the effects of green tea catechin on microsomal phospholipase $A_2(PLA_2)$ activity and the arachidonic acid (AA) cascade in hearts of microwave exposed rats. Sprague-Dawley male rats weighing $100{\pm}10$ g were randomly assigned to one normal group and three microwave exposed groups. The microwave exposed groups were subdivided into three groups: catechin free diet (MW) group, 0.25% catechin (MW-0.25C group and 0.5% catechin (MW-0.5C) group according to the levels of dietary catechin supplementation. Rats were sacrificed $6^{th}$ day after microwave irradiations (2.45 GHz, 15 min). The heart microsome $PLA_2$ activity in the MW group was 130% greater than that of normal groups, whereas there was no significant difference between normal group and MW-0.25C, MW-0.5C group. The per- centage phosphatidyl ethanolamine (PE) hydrolyzed in the heart microsome in the MW was increased 54% by microwave irra- diation, whereas there was no significant difference between normal group and MW-0.5C group. The percentage phosphatidyl choline (PC) hydrolyzed in the heart microsome in the MW group was increased by 104% and by microwave irradiation, whereas there was no significant difference between normal group and MW-0.5C group. The formation of thromboxane $A_2(TXA_2)$ in the heart microsome was 70% greater in the MW group than in the normal group. However, the MW-0.25C and MW-0.5C group maintained the normal level. The formation of prostacyclin ($PGI_2$) in the heart microsome was 21% lower in the MW group than in the normal group, while that of MW-0.25C and MW-0.5C group were maintained in the normal group. The heart microsomal thiobarbituric acid reactive substances (TBARS) concentrations, as an index of lipid peroxide, were 71% greater in the MW group, as compared with normal group. However, the MW-0.25C and MW-0.5C group were 4.6% and 9.2% lower, respectively, than that of MW group. In conclusion, heart function appeared to be improved by green tea catechin supplementation due to its antithrombus action, which in return controls the AA cascade system.

• Journal of Chest Surgery
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• v.35 no.7
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• pp.501-510
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• 2002

Background: The various pathogeneses of acute respiratory distress syndrome have been suggested but not established yet. In the present study, the role of group II phospholipase $A_2$($PLA_2$) in the pathogenesis of gut ischemia-reperfusion(I/R) induced acute lung injury (ALI), especially in the pulmonary oxidative stress with infiltration of neutrophils was investigated. Material and Method: To induce ALI, reperfusion of mesentery was done for 120 min after clamping of superior mesenteric artery for 60 min in Sprague-Dawley rats that weighed about 300g. To exmaine the role of group II $PLA_2$ in ALI, especially endothelial injury associated with the action of neutrophils, lung myeloperoxidase activity, lung leak index, bronchoalveolar lavage fluid protein were measured, and pulmonary $PLA_2$ activity changes in gut I/R were also measured. The role of group II $PLA_2$in the neutrophilic generation of free radicals was assessed by inhibiting group II $PLA_2$ with rutin, manoalide and scalaradial. Furthermore, to verify the oxidative stress in the lung, histologic and free radical detecting cytochemical electron microscopy were done. Result: After reperfusion, ALI was developed with accumulation of neutrophils in the lung, which was confirmed by the increase of myeloperoxidase activity, lung leak index and bronchoalveolar lavage protein (p<0.001). The pulmonary and intestinal group II $PLA_2$ activities significantly increased after gut I/R which were reversed by rutin(p<0.001). In vitro, cytochrome-c reduction assay denoted the inhibitory effects of rutin, scalaradial and manoalide on the production of free radicals from isolated human neutrophils. Histologically, neutrophilic accumulation and pericapillary edema in the lung after gut I/R was detected by light microscopy which was suppressed by rutin. In $CeCl_3$ cytochemical electron microscopy, the increased production of hydrogen peroxide in the lung after gut I/R was confirmed and also the production of hydrogen peroxide was decreased by rutin. Conclusion: On the basis of these experimental results, the inhibition of group II $PLA_2$ seemed to mitigate gut I/R-induced ALI by suppressing the production of free radicals from the infiltrated neutrophils. Collectively, group II $PLA_2$ seems to play a crucial role in gut I/R-induced ALI by neutrophilic oxidative stress.

• Journal of the Korean Society of Food Science and Nutrition
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• v.41 no.7
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• pp.936-942
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• 2012

In the present study, the effects of green tea catechin on microsomal phospholipase $A_2$ ($PLA_2$) activity and the arachidonic acid (AA) cascade in the lungs of microwave exposed rats were investigated. One Sprague-Dawley male rats weighting $100{\pm}10$ g was randomly assigned to the normal group and three were assigned to the microwave exposed groups. The microwave exposed groups were subdivided into three groups according to the levels of dietary catechin supplementation: catechin free diet (MW) group, 0.25% catechin (MW-0.25C) group and 0.5% catechin (MW-0.5C) group. Rats were sacrificed on the 6th day after microwave irradiation (2.45 GHz, 15 min). The lung microsomal $PLA_2$ activity in the MW and MW-0.25C groups was 30% and 15% greater than that of the normal group, respectively, whereas no significant difference between the normal group and MW-0.5C group was observed. The percentage of phosphatidylethanolamine (PE) hydrolyzed in the lung microsome in the MW, MW-0.25C and MW-0.5C group increased by 47%, 18% and 20%, respectively, due to microwave irradiation. The formation of thromboxane $A_2$ ($TXA_2$) in the lung microsome was 50% greater in the MW group than in the normal group. However, the levels of $TXA_2$ in the MW-0.25C and MW-0.5C group were normal. The formation of prostacyclin ($PGI_2$) in the lung microsome was 31% lower in the MW group than in the normal group, while the levels of $PGI_2$ in the MW-0.25C and MW-0.5C group were similar to the normal group. The lung microsomal thiobarbituric acid reactive substances (TBARS) concentration, which can be used as an index of lipid peroxide was 34% greater in the MW group, when compared with the normal group. However, there was no difference between the MW-0.25C, MW-0.5C and normal groups. In conclusion, lung function appeared to be improved by green tea catechin supplementation due to its antithrombus action, which in turn controls the AA cascade system.