Left atrial volume index as a predictor of ventricle repolarization abnormalities in adult dialyzed patients

This study was performed to investigate the relationship between left atrium (LA) volume index (LAVI) and left ventricle electrical activity presumably repolarization in end‐stage renal disease patients. Study group was consisted of 120 dialyzed patients divided into two subgroups: 57 (age 50.7 ± 7.1) were on continuous ambulatory peritoneal dialysis (CAPD) and 73 (age 51.6 ± 7.6) were hemodialyzed (HD). All patients were undergoing three‐dimensional vectorcardiographic (VCG) monitoring to assess parameters concerning T vector: QRS‐T angle, Tel, and Taz. Standard echocardiography was performed to assess: LA_max, LA_short, LA_long. LAVI was calculated due to formula: LAVI = (π/6X [LA_max × LA_short × LA_long])/m². LAVI in HD as well as in CAPD patients was significantly higher compared with controls (respectively: 36.29 ± 10.92; 36.41 ± 11.06; 20.64 ± 6.77 mL/m²). The calculated cutoff value of LAVI was 36.32 mL/m². In HD patients, the strong correlations between LAVI and QRS‐T angle and Tel were determined (respectively: r = 0.407, P < 0.001 and r = 0.359, P = 0.006). Similarly in CAPD group were significant associations between LAVI and QRS‐T angle and Tel (respectively: r = 0.423, P < 0.001 and r = 0.374, P = 0.004). The QRS‐T angle, Tel and Taz are independently and markedly associated with LAVI in both HD and CAPD patients. LAVI and VCG indices are higher in both HD and CAPD patients. Correlation between QRS‐T angle and LAVI may reflect unfavorable influence on the electrical activity of the heart in dialyzed patients with left ventricle diastolic dysfunction. LAVI cutoff value is useful biomarker for stratification of ventricle repolarization disturbances in those patients.     

Personal viewpoint: hemodialysis--water, power, and waste disposal: rethinking our environmental responsibilities

While medical health professionals are trained to detect, treat, and comfort, they are not trained to consider the environmental impact of the services they provide. Dialysis practitioners seem particularly careless in the use of natural resources—especially water and power—and seem broadly ignorant of the profound medical waste issues created by single use dialysis equipment. If the data we have collected is an indication, then extrapolation of this data to a dialysis population currently estimated at ~2 million patients worldwide, a “world dialysis service” would use ~156 billion liters of water and discard ~2/3 of that during reverse osmosis. This waste occurs, despite the discarded water being high-grade “gray water” of potable standard. The same world dialysis service would consume 1.62 billion kWh of power—mostly generated from coal and other environmentally damaging sources. Our world dialysis service, based on ~2 kg of waste from each dialysis treatment, would generate ~625,000 tonnes of plastic waste—waste that would be potentially reusable if simple sterilizing techniques were applied to it at the point of generation. Dialysis services must begin to explore eco-dialysis potentials. The continued plundering of resources without considering reuse or recycling, exploration of renewable energy options, or the reduction of the carbon footprint of the dialysis process . . . is unsustainable. Sustainable dialysis practices should be a global goal in the coming decade.     

Plasma myeloperoxidase,NT‐proBNP,and troponin‐I in patients on CAPD compared with those on regular hemodialysis

Myeloperoxidase (MPO) is a hemoprotein that is released during inflammation and may lead to irreversible protein and lipid modification, increasing levels of oxidized low density lipoprotein, and promoting athrogenesis. Recently, it has been considered as a risk factor for cardiovascular diseases. Similarly, the measurement of carotid intima‐media thickness gives an indication about the degree of atherosclerosis and prediction of clinical cardiovascular events. Elevated white blood cells counts may indicate a state of acute inflammation and follow its progression. Dialysis patients are at a high risk of developing cardiovascular disease compared with healthy subjects. The role of N‐terminal pro‐brain natriuretic peptide and increased cardiac troponin in identification and prognostication of cardiovascular diseases in end‐stage renal disease patients has been investigated. The current study aimed to evaluate plasma MPO and its possible relationship with carotid intima‐media thickness, troponin I, N‐terminal pro‐brain natriuretic peptide (NT‐proBNP), and insulin resistance as measured by homeostatic model assessment (HOMA index) in a cohort of Saudi patients who are undergoing hemodialysis (HD) vs. continuous ambulatory peritoneal dialysis for end‐stage renal disease. Plasma MPO was significantly higher in patients on continuous ambulatory peritoneal dialysis (CAPD) than in those on HD and in normal subjects (P<0.001). Conversely, NT‐proBNP plasma levels were significantly higher in patients on HD (both predialysis and postdialysis) than in those on CAPD (P<0.01) and than normal subjects. Similarly, plasma troponin‐I levels were significantly higher in patients on HD compared with those of CAPD and than normal subjects (P<0.001). Plasma troponin‐I and NT‐proBNP levels were positively correlated in the 3 groups namely those on CAPD, Pre‐HD, and post‐HD (r: 0.464 and P=0.047; r: 0.330 and P=0.013; and r: 0.452 and P=0.024), respectively. There was no correlation between the MPO level and carotid intima‐media thickness (P>0.05). However, plasma MPO level correlated positively with the white blood cell count in patients on CAPD and in those on HD (P<0.05). Our findings suggest an increased oxidative stress in CAPD patients compared with HD patients, while the reported difference in plasma NT‐proBNP and troponin‐I may be related to the rapid decline of residual renal function in HD and type of membrane used in the HD dialysis procedure itself.     

渗析法确定土水特征曲线的试验研究

土水特征曲线(SWCC)描述的是土体基质吸力与含水率之间的关系,它对于非饱和土的研究具有重要意义。在测定SWCC的各种方法中,渗析法的试验过程较简单、安全且可靠。本文以合肥地区非饱和膨胀土为研究对象,详细介绍了渗析法获得SWCC的试验过程和技术要领,并采用水浴恒温振荡器代替磁力搅拌器改进了渗析试验。结果表明:采用水浴恒温振荡器进行渗析试验是合理可行的,其优点是一次可以进行相同环境条件下多个浓度的渗析试验;使用水浴恒温振荡器对合肥地区膨胀土进行渗析试验时,其渗析平衡时间约为8天。在此基础上,采用Fredlund-Xing模型的3种型式对渗析试验结果进行了曲线拟合,得到了试验土体的SWCC及其拟合参数,可知模型3种型式的区别主要在高吸力部分。     

点击化学法制备SBS-TMA型阴离子交换膜及其性能

以聚苯乙烯-丁二烯-苯乙烯嵌段共聚物（SBS）为基质、炔丙基三甲胺盐（PTMA）为碱性功能基团,通过点击化学（click chemistry）法合成聚合物SBS-TMA,采用浇铸成膜法制得扩散渗析（DD）性能优异的均质型阴离子交换膜。借助核磁共振仪（¹H NMR）、扫描电镜（SEM）对聚合物的结构、形貌表征;借助热重分析仪（TG）、精密天平对膜的热、酸性稳定性能表征。研究了功能基团含量和温度双重因素对其DD性能的影响,结果表明：在室温下,当功能基团的含量为0.20（即SBS-TMA-0.20）时,膜的扩散系数（U_H⁺）为2.86×10^-2m/h,分离系数（S）为28.1,该膜的DD性能是商业膜DF-120（U_H⁺=9×10^-3m/h,S=18）的2～3倍;当系统温度由25℃升至70℃时,膜SBS-TMA-0.20的U_H⁺值由2.86×10^-2m/h增加至4.48×10^-2m/h,它的S值由28.1增加至30.1,随后由30.1快速下降至16.2。     

应用FIAstar5000和透析膜测定牛奶及乳制品中的亚硝酸盐和硝酸盐

样品在热萃取缓冲溶液中,是悬浊液。离心分离并快速冷却分离出脂肪。脱脂后的溶液注射到流动注射分析系统中。系统内透析膜用来除去蛋白质和残余脂肪。通过镉将硝酸根离子还原至亚硝酸根离子。在一个酸性的对氨基苯磺酰胺溶液中,亚硝酸根形成偶氮化合物。它与N-（1-萘基）-乙二胺二盐酸盐（NED）结合形成紫色的含氮染料,在540nm处进行测定。此方法为测定牛奶亚硝酸盐和硝酸盐的常规方法,检出限可达0．02mg／kg,RSD〈10,回收率〉90％。     

一阶导数光谱法测定血液透析用浓缩物中醋酸根含量

建立一种测定血液透析用浓缩物中醋酸根含量的方法。方法：采用一阶导数光谱法测定血液透析用浓缩物中醋酸根的含量。波长扫描范围：190-300nm。结果：醋酸根线性范围是9．8-58．6mmol／L（r=0．9998）,平均加样回收率为99．9％,RSD=0．80％（n=3）。结论：此方法操作简便,测定时间短,准确度高,浓缩物中其他离子对测定结果基本无影响。     

Risk factors for progression of aortic arch calcification in patients on maintenance hemodialysis and peritoneal dialysis

Vascular calcification is accelerated during dialysis and is known to be an important risk factor for cardiovascular disease. Progression of aortic arch calcification (AoAC) can be simply estimated with an AoAC score (AoACS) using plain chest radiography. The objective of this study was to evaluate risk factors for AoAC progression. The enrolled subjects were 125 newly treated hemodialysis patients and 59 peritoneal dialysis patients. In the patients who had undergone chest radiography before initial dialysis therapy and every year, we estimated AoACS and then divided the patients into two groups based on the presence or absence of AoAC progression. We also compared the baseline clinical and biochemical profiles in the two groups. Eighty‐five (46.2%) were men (mean age, 58.6 ± 12.7 years). Seventy‐six patients (41.3%) had AoAC before initial dialysis, with a mean AoACS of 13.0 ± 20.4%. The mean duration of follow‐up was 2.7 ± 1.0 years. Half of the patients (50%) had progressive AoAC. Age >65 years (p = 0.003), dialysis duration (p = 0.004), diabetes (p = 0.015), and the presence of AoAC at baseline (p = 0.001) were related to AoAC progression. No significant association was found between AoAC progression and the baseline clinical parameters, including gender, obesity, hypertension, and dialysis modality. In a multivariate analysis, dialysis duration (p = 0.003) and the presence of AoAC at baseline (p < 0.001) were independent risk factors for AoAC progression in patients undergoing dialysis. The duration of dialysis and the presence of AoAC before initial dialysis were significantly related to the progression of AoAC in these patients. The results suggest that patients should be carefully managed from the predialysis stage to prevent AoAC progression and to reduce cardiovascular morbidity.     

重组牛乳铁蛋白肽包含体的复性与纯化

通过分析透析液pH值，包含体蛋白浓度，DTT浓度3个参数对复性率的影响，确定了重组牛乳铁蛋白N-末端多肽（pGEX-4T1／rbLF—N）包含体透析复性的最佳条件和复性后蛋白纯化的适宜方法。采用谷胱甘肽琼脂糖凝肢4B柱（Glutathione Sapharose^TM 4B）时复性后的蛋白溶液进行纯化．纯化后的融和蛋白经胃蛋白酶酶解并检测其酶解产物的抗菌活性。试验表明包涵体蛋白可以部分复性。当pH值为8．5，包含体蛋白质量浓度为100mg／L，DTT浓度为24mmol／L，包含体的复性率最高。纯化后的融合蛋白酶解产物具有抗菌作用。     

面向酸碱回收过程的扩散渗析技术研究进展

介绍了膜扩散渗析技术对酸和碱回收的工作原理和应用领域,综合分析了当前国内外对扩散渗析技术的研究进展和应用现状,并简要评述了扩散渗析在回收酸碱中的应用前景。