Experimental and Numerical Investigation of an Axial Rotary Blood Pump

Left ventricular assist devices (LVADs) have become a standard therapy for patients with severe heart failure. As low blood trauma in LVADs is important for a good clinical outcome, the assessment of the fluid loads inside the pump is critical. More specifically, the flow features on the surfaces where the interaction between blood and artificial material happens is of great importance. Therefore, experimental data for the near‐wall flows in an axial rotary blood pump were collected and directly compared to computational fluid dynamic results. For this, the flow fields based on unsteady Reynolds‐averaged Navier–Stokes simulations‐computational fluid dynamics (URANS‐CFD) of an axial rotary blood pump were calculated and compared with experimental flow data at one typical state of operation in an enlarged model of the pump. The focus was set on the assessment of wall shear stresses (WSS) at the housing wall and rotor gap region by means of the wall‐particle image velocimetry technique, and the visualization of near‐wall flow structures on the inner pump surfaces by a paint erosion method. Additionally, maximum WSS and tip leakage volume flows were measured for 13 different states of operation. Good agreement between CFD and experimental data was found, which includes the location, magnitude, and direction of the maximum and minimum WSS and the presence of recirculation zones on the pump stators. The maximum WSS increased linearly with pressure head. They occurred at the upstream third of the impeller blades and exceeded the critical values with respect to hemolysis. Regions of very high shear stresses and recirculation zones could be identified and were in good agreement with simulations. URANS‐CFD, which is often used for pump performance and blood damage prediction, seems to be, therefore, a valid tool for the assessment of flow fields in axial rotary blood pumps. The magnitude of maximum WSS could be confirmed and were in the order of several hundred Pascal.     

125I粒子条联合胆道支架植入治疗恶性梗阻性黄疸22例疗效分析

目的研究和探讨125I粒子条联合胆道支架植入治疗恶性梗阻性黄疸的临床疗效。方法2011年6月—2013年9月收治恶性梗阻性黄疸患者40例。行胆道支架植入术治疗患者18例,为对照组;采用125I粒子条联合胆道支架植入患者22例,为观察组。两组均采用经皮肝穿刺胆道引流(PTCD)并胆道支架植入。结果观察组与对照组的平均胆道开通时间分别为(8.7±0.7)和(6.2±0.4)个月,两组比较差异有统计学意义(P<0.05)。观察组与对照组术后平均生存时间分别为(11.4±0.8)和(8.7±0.5)个月,生存时间的差异有统计学意义(P<0.05)。术后近期疗效及并发症两组之间的比较无明显差异(P>0.05),但是远期疗效有显著差异(P<0.05)。结论与对照组相比,观察组的术后生存时间及胆道开通时间明显延长,对于125I粒子条联合支架治疗恶性梗阻性黄疸值得进一步临床研究。     

α2－巨球蛋白活性检测方法的建立与优化

目的：建立α2－巨球蛋白（α2－macroglobulin ,α2－M）活性检测方法,检测Cohn组分Ⅳ中α2－M的活性。方法α2－M可与胰蛋白酶相互作用形成“α2－M－胰蛋白酶复合物”,利用酶标仪检测出“α2－M－胰蛋白酶复合物”与小分子底物Na－苯甲酰－DL－精氨酸－对硝基酰胺盐酸盐（ Na－benzoyl－DL－arginine 4－nitroanilide hydrochloride ,BAPNA）显色反应后的光密度值（410 nm）,根据建立的血浆α2－M活性标准曲线,定量计算出Cohn组分Ⅳ浓缩液中α2－M的活性。结果通过对实验体系中几个关键实验条件进行优化,建立了血浆α2－M活性标准曲线,并计算出Cohn组分Ⅳ浓缩液中α2－M活性的平均值为1．578 PU／ml。结论以正常人混合血浆作为参考标准品,用发色底物法检测Cohn组分Ⅳ浓缩液中α2－M的活性,方法简便易行,为α2－M制备过程中活性测定提供了实验基础。     

经皮睾丸微穿刺活检后冷冻精子的卵胞质内单精子注射

目的:对经皮睾丸微穿刺活检后冷冻保存精子卵胞质内单精子注射(ICSI)治疗非梗阻性无精子症所致不育进行临床总结,并对其影响治疗结果的因素进行探讨。方法:对62例非梗阻性无精子症患者进行经皮睾丸微穿刺活检,发现活动精子者(35例)对睾丸活检组织进行冷冻保存;女方促排卵常规使用促性腺激素释放激动剂(GnRHa)/卵泡刺激素(FSH)/人绒毛膜促性腺激素(hCG)方案,B超监测卵泡发育情况并引导经阴道取卵,冷冻的睾丸组织解冻后行ICSI,良好胚胎进行移植。结果:取卵周期为35个,冷冻的睾丸精子解冻后行ICSI,35个周期进行常规胚胎移植。13例临床妊娠。启动周期、取卵周期与移植周期临床妊娠率均为37.14%(13/35)。结论:经皮睾丸微穿刺活检后ICSI是治疗非梗阻性无精子症所致不育的最主要和有效的方法;活检后对有活动精子的睾丸组织进行冷冻保存不影响治疗结果,可以减少患者睾丸活检的次数,减轻患者痛苦。     

主动脉内球囊反搏在低射血分数患者非体外循环冠状动脉旁路移植术中应用的必要性探讨

目的探讨对低射血分数患者施行非体外循环冠状动脉旁路移植术(off-pump coronary artery bypass grafting, OPCAB)预防性应用主动脉内球囊反搏(intraaortic balloon pump, IABP)辅助的必要性. 方法 2001 年1 月～2004年10月对64例低射血分数(LVEF≤40%)施行OPCAB,将64例分为2组:术前或术中预防性应用IABP辅助者列为IABP组,共19例;未应用IABP者列为对照组,共45例. 结果 IABP组与对照组在术后并发症手术死亡、脑血管意外、肾功能衰竭衰血滤、围手术期心肌梗死等方面无显著差异(χ2=0.000,P=1.000).IABP组术后需要延长呼吸机带机时间(超过24 h)的比例显著高于对照组(IABP组8例,对照组3例; χ2=9.429,P=0.002);IABP组术后监护时间延长(超过48 h)的比例显著高于对照组(IABP组14例,对照组19例; χ2=4.110,P=0.043). 结论在无IABP辅助的情况下,为低射血分数患者实施OPCAB手术是可行的.     

Benign paroxysmal positional vertigo as the cause of dizziness in patients after severe traumatic brain injury: diagnosis and treatment

Objectives: To identify patients with benign paroxysmal positional vertigo (BPPV) among patients with severe traumatic brain injury (TBI) and to evaluate the effectiveness of the Particle Repositioning Maneouvre (PRM).

Design and methods: Eighteen months prospective study of 150 consecutive patients with severe TBI referred to an in-patients rehabilitation department.

Interventions: A structured interview emphasizing the possible presence of vertigo followed by a detailed neuro-otological examination. Patients diagnosed with BPPV were immediately treated with the PRM.

Main outcomes and results: BPPV diagnosis was based on a positive Dix-Hallpike positional test. PRM efficacy was determined by repeating the positional test 1 or 2 weeks after treatment. Twenty out of 150 (13.3%) patients complained about positional vertigo. The diagnosis of BPPV was confirmed in 10 patients. Signs and symptoms were completely relieved in six patients after a single PRM, while the other four patients needed repeated treatment for complete resolution of BPPV.

Conclusions: About half of the patients with severe TBI who complain about positional vertigo suffer from BPPV. These patients can be efficiently treated by physical maneouvres improving the rehabilitation outcome.     

Combined effect of alpha particles and cigarette smoke on human lung epithelial cells in vitro

Abstract

Purpose: The combined toxicity of alpha particles and cigarette smoke to the critical cells in the lungs was investigated to assess the risk of smoking workers who handle naturally occurring radioactive materials.

Materials and methods: The toxicity of alpha particles and cigarette smoke extract (CSE) was evaluated in terms of DNA double-strand break (DSB) induction and clonogenic cell death of human lung epithelial cells in vitro. The cells were exposed to alpha particles at doses of up to 0.25?Gy for gamma-H2AX assay and from 1.25?Gy to 5?Gy for clonogenic assay. CSE exposure of the cells was facilitated in the culture medium at CSE concentrations ranging from 1% to 12%. Additional experiments were performed using mouse endothelial cells for comparison.

Results: The increases in the levels of DNA DSBs were linearly dependent on radiation dose and CSE concentration. The CSE-treated cells also responded with a linearly increasing number of DNA DSBs to the radiation dose. Both human lung epithelial cells and mouse endothelial cells showed exponential decreases in clonogenic surviving fraction as the dose from alpha particle exposure increased. Both cells responded with the clonogenic surviving fractions decreasing in a linear proportion to the CSE concentration in the culture medium.

Conclusion: In our experimental in vitro setup, CSE treatment and alpha particle exposure affected the cells in an additive manner either for DNA DSB production or for clonogenic cell death induction.