Lai, KWH

Lau, CP

Tipoe, GL

Yu, CM

HKU Scholars Hub

Title Expression of Cyclooxygenase-2 Protein in Acute MyocardialInfarctionAuthor(s) Yu, CM; Lai, KWH; Tipoe, GL; Lau, CPCitation The 5th Medical Research Conference, Hong Kong, China,January 2000, v. 22 n. Supp 2, p. 32Issued Date 2000URL http://hdl.handle.net/10722/45642Rights Creative Commons: Attribution 3.0 Hong Kong LicenseS-C-11Time-Frequency Analysis of Intracardiac ElectrogramsWeichao Xu*. Chu-Pak Lau**, Francis H. Y. Chan*, Hung-Fat Tse**, and Peter C. W. Fung***Department of Electrical and Electronic Engineering,**Department of Medicine,The University of Hong Kong, Hong KongAbstract: Atrial fibrillation (AF) is the most common supraventricular arrhythmia and remains achallenge in curative catheter ablation. The irregularity of atrial activity during atrial fibrillation(AF) makes it very difficult to determine ablation sites in curative catheter ablation operations.The advantages of wavelet transform (WT) over conventional time- or frequency-domainanalyses motivate us to develop a measure of the spatial organization of atrial activationprocesses during AF by means of WT based compression technique. Five channels of right atrialsignals from 5 patients are analyzed. Experimental results showed that zero rates (ZR) of WTcoefficients after compression can well characterize the complexity of atrial activity during AFand thus can offer helpful information for the choice of ablation sites. Table 1 below summarizesthe statistics of ZRs belonging to different intracardiac electrograms.Table 1: Statistics of ZR of Three Types of SignalsMSDSI96.50.08FL95.00.14AF194.00.64AF294.10.67AF393.80.50AF493.60.57AF593.80.74S-C-12Expression of Cyclooxygenase-2 Protein in Acute Myocardial InfarctionCM Yu, WH Lai. *G Tipoe, CP Lau. Division of Cardiology, Department of Medicine, Queen Mary Hospital,Hong Kong and *Department of Anatomy, The University of Hong Kong.Background: Cyclooxygenase is a key enzyme in prostadglandins synthesis. Its inducible forms,cyclooxygenase-2 (cox-2), can be triggered by cytokines, growth factors and hypoxia. Under acute myocardialinfraction (AMI), many cytokines are secreted in the heart. However, the role of cox-2 is still unknown. Wehypothesized that cox-2 protein is activated in the heart after AMI which may have pathological significance.Methods: A animal model of AMI was established by ligating the left anterior descending coronary artery ofthe 10-week old male Sprague-Dawley rats. Sixteen post-AMI rats were killed at day-3, day-7, day-14, andday-28 after AMI. Four sham-operated rats were used as controls. The expression of MIF was revealed byimmunohistochemistry. The macrophage infiltration was also studied by immunohistochemical method usinganti-EDl antibody.Results: There was no cox-2 staining found in sham rats. At day-3 after AMI, macrophages were foundinfiltrating into the infracted area but without cox-2 staining. At day-7, macrophage infiltration was increasedand cox-2 protein was stained inside the cardiomyocytes near the infarct zone of the left ventricle. The cox-2protein was most abundant at day-14 in the cardiomyocytes. At day-28, cox-2 protein expression was decreasedthough it was found in both cardiomyocytes and macrophages in the infarct zone, as well as at the walls of theblood vessels in both infarcted and non-infarct areas of left ventricle, compatible with its potential role inangiogenesis after AMI.Conclusion: This study have demonstrated, for the first time, the expression of cox-2 protein in thecardiomyocytes after AMI which is closed timed to macrophage infiltration. Its role in cardiac remodellingafter AMI therefore warrant further investigation. In addition, its late expression in the coronary arteries mayimplicate its potential role in angiogenesis.- 32 -

Expression of Cyclooxygenase-2 Protein in Acute Myocardial Infarction

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Expression of Cyclooxygenase-2 Protein in Acute Myocardial Infarction

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