研究背景:
動靜脈廔管阻塞是血液透析患者長期預後的重要議題，而之前的回顧文獻針對動靜脈廔管其暢通率，整理出較為相關的影響因子，除了年紀、抽菸、本來的血管狀態之外，糖尿病也是關鍵的危險因子。糖尿病和心血管疾病的關係中，血管平滑肌細胞遷徙和增生似乎扮演重要角色，而ROCK和此機轉以及發炎反應也有密切相關。而另一方面Galectin-3在靜脈栓塞和周邊血管疾病也有相關研究。而這次我們希望可以探索在動靜脈廔管阻塞中的潛在機轉。

研究方法:
在成大醫院和斗六分院心導管室中，我們收集38位動靜脈廔管阻塞的病人，於進行導管介入術式的同時收集第一次的血液檢體，作為動靜脈廔管阻塞時的狀況，再於至少間隔一個月之後收集第二次的血液檢體，作為動靜脈廔管通暢時的對照組，比較同一個病人身上在廔管阻塞和暢通時各種物質的相關變化，其中29位患者接受完整的追蹤，再以HbA1C最為糖尿病控制好壞的分界。
血液檢體中血小板萃取分離之後，用西方墨點法檢測galectin-3、以及用ROCK下游產物MYPT的磷酸化比例代表血小板中ROCK活性，除此之外，我們也用ELISA的方式檢測血漿中游離galectin-3和其結合蛋白的濃度。

實驗結果:
當動靜脈廔管阻塞時血小板中MYPT磷酸化的比例和galectin-3都比動靜脈廔管通暢時為有統計意義的上升[MYPT ratio: 0.5 (0.3-1.4) vs. 0.4 (0.3-0.6), p=0.01; galectin-3: 1.2 (0.4-1.6) vs. 0.7 (0.1-1.2), p=0.0004]。而血漿中游離的galectin-3結合蛋白在ELISA上的檢測也是呈現一樣的趨勢[8.4 (6.0-9.7) μg/ml vs. 7.1 (4.5-9.1) μg/ml, p=0.009]。此外，我們也發現阻塞時指數上升的比例在血糖控制不好的患者有更高的趨勢[MYPT ratio: 1.7 (1.0-3.0) vs. 1.1 (0.7-1.3), p=0.06, galectin-3: 1.6 (1.3-3.4) vs. 1.1 (0.8-1.9), p=0.05]。另外我們以多因子變異回歸分析也看到，阻塞時的MYPT磷酸化比例和galectin-3阻塞時的上升幅度，和患者的HbA1C有關。

結論:
血小板中ROCK活性和galectin-3在動靜脈廔管阻塞時上升，在糖尿病控制不好的患者身上尤其重要。

Introduction
Vascular access dysfunction plays a critical role for hemodialysis patients and is associated with substantial morbidity and mortality. Diabetes mellitus is one of major factors to influence patent rate of arteriovenous shunt. Hyperglycemia is an important factor in the development of macrovascular complications in diabetes, potentially associated with RhoA/ROCK pathway. Besides, galectin-3 mediates thrombotic mechanisms in the field of venous thrombosis and myocardial infarction. This time, we thus hypothesized that high ROCK activity and galectin-3 level are associated with increased risk for arteriovenous shunt dysfunction in diabetic patients.
Methods
We prospectively enrolled 38 patients diagnosed as arteriovenous shunt dysfunction and referred to receive percutaneous intervention in our catheterization laboratory room of National Cheng Kung University Medical Center and Dou-liu branch. Among these patients, 29 patients received complete follow-up and were drawn for two times of blood sample, which were collected at first visit for occluded status of arteriovenous shunt and at least 1 month later for patent status. After platelet extraction, Western blot assay for myosin phosphatase target subunit was performed for predicting Rho kinase activity, as the ratio of phosphorylation levels of MYPT divided by total MYPT. Besides, Western blot assay for platelet galectin-3 was also done. Circulating galectin-3 and galectin-3 binding protein were measured by Galectin-3 and Galectin-3 binding protein ELISA assay.

Results
First, higher platelet MYPT ratio and Galectin-3 level were shown at the status of arteriovenous shunt occlusion [MYPT ratio: 0.5 (0.3-1.4) vs. 0.4 (0.3-0.6), p=0.01; galectin-3: 1.2 (0.4-1.6) vs. 0.7 (0.1-1.2), p=0.0004]. Plasma galectin-3 binding protein ELISA were also higher at the status of arteriovenous shunt occlusion [8.4 (6.0-9.7) μg/ml vs. 7.1 (4.5-9.1) μg/ml, p=0.009]. Second, we also found that a trend of higher biomarker ratio (occluded/patent status) was noted in poorly-controlled diabetic patients [MYPT ratio: 1.7 (1.0-3.0) vs. 1.1 (0.7-1.3), p=0.06; galectin-3: 1.6 (1.3-3.4) vs. 1.1 (0.8-1.9), p=0.05]. Besides, MYPT ratio and galectin-3 difference (occluded/patent status) seemed to be associated with HbA1C by multivariate linear regression analysis.
Conclusion
High platelet ROCK activity and galectin-3 level are associated with increased risk for arteriovenous shunt dysfunction, especially in poorly-controlled diabetic patients.

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