涡轮叶栅叶冠泄漏流动数值研究

以小展弦比涡轮叶栅为研究对象,利用三维数值计算的方法研究了篦齿数、篦齿排列型式、上下游压力以及径向间隙对叶冠泄漏流量的影响,并分析了泄漏流动与主流的相互作用。研究表明,叶片排上下游压比和径向间隙是影响叶冠泄漏流动的主要因素,篦齿数和篦齿排列型式对泄漏流量的大小和出口气流角均有重要影响。考虑了主流的影响之后,叶冠出口流动呈现出高度的三维性和周向不均匀性。在周向压力梯度的作用下,径向速度以正负交替的形式出现,而且周向速度和轴向速度则出现了明显的分层结构。      

Estimation of Volume Doubling Time and Cell Loss in an Experimental Rat Glioma Model in Vivo

Summary  We estimated the volume doubling time (Vd) of the ethylnitrosourea-induced rat glioma by serial magnetic resonance imaging, and the results were compared with potential doubling time (Tp) determined immunohistochemically.  Vd ranged from 3.3 to 29.2 days (11.03±7.74) and Tp ranged from 2.3 to 13.3 days (6.81±3.33). Each tumour showed a wide range of bromodeoxyuridine (BUdR) labelling indices (LI), however, Vd and Tp correlated well with BUdR-LI. Vd was estimated as 17.6×BUdR-LI^−0.63 (R=−0.76, P<0.001, n=13) and Tp was estimated as 22.6×BUdR-LI^−1.02 (R=−0.92, P<0.0001, n=12).  In addition, we compared the apoptotic indices (AI), determined by terminal deoxynucleotidyltransferase(Tdt)-mediated biotinylated dUTP-biotin nick-end labelling (TUNEL) techniques, with BUdR-LI and mitoses indices (MI). The results were: AI=0.23+0.25Ln(BUdR-LI) (R=0.971, n=8, P<0.0001) and AI=1.05+0.29Ln(MI) (R=0.937, n=8, P<0.001). Cell loss factors (CLF) also correlated well with BUdR-LI and MI. However, CLF calculated from Tp and Vd were lower than the values previously presumed, probably because of shorter Vd than true doubling time for tumour cell population. These results suggest that even malignant tumours retain a mechanism of adjusting their growth at least partly.     

Experimental Investigation of Left Ventricular Flow Patterns After Percutaneous Edge‐to‐Edge Mitral Valve Repair

Mitral valve percutaneous edge‐to‐edge repair (PEtER) is a viable solution in high‐risk patients with severe symptomatic mitral regurgitation. However, the generated double‐orifice configuration poses challenges for the evaluation of the hemodynamic performance of the mitral valve and may alter flow patterns in the left ventricle (LV) during diastole. This in vitro study aims to evaluate the hemodynamic modifications following a simulated PEtER. A custom‐made mitral valve was developed, and two configurations were tested: (i) a single‐orifice valve with mitral regurgitation and (ii) a double‐orifice mitral valve configuration following PEtER. The hemodynamic performance of the valve was evaluated using Doppler echocardiography and catheterization, while the flow patterns in the LV were investigated using particle image velocimetry (PIV). The tests were run at a stroke volume of 65 mL and a heart rate of 70 bpm. PEtER was found to significantly reduce the regurgitant volume (15 vs. 34 mL). There was a good agreement between Doppler and catheter transmitral pressure gradients (peak gradient: 9 vs. 7 mm Hg; mean gradient: 4 vs. 3 mm Hg) as well as an excellent agreement between maximal velocity measured by Doppler and PIV (1.60 vs. 1.58 m/s). Vortex development in the LV during diastole was significantly different after repair. PEtER significantly increased the amplitude of Reynolds and viscous shear stresses, as well as the number of high shear regions in the LV, potentially promoting thromboembolism events.     

In Vitro Investigation of the St. Jude Medical Isoflow Centrifugal Pump: Flow Visualization and Hemolysis Studies

Abstract: Centrifugal blood pumps have become valuable therapeutic tools for cardiopulmonary bypass surgery. In addition, surgeons have used them as temporary ventricular assist devices, and this type of pump is also being developed for use as a permanent assist device and total artificial heart. However, centrifugal pumps create flow patterns that are significantly different from those the blood experiences physiologically. The St. Jude Medical Isoflow centrifugal pump has been used clinically during cardiopulmonary bypass surgery, yet no experimental results have been reported that describe the flow patterns within this pump or that quantify the hemolysis generated over a range of operating conditions. The purpose of this study was to investigate the flow patterns and hemolysis during 4 operating conditions. The experimental operating conditions included the design condition (6 L/min, 2,500 rpm, 350 mm Hg), a high flow condition (10 L/min, 2,500 rpm, 330 mm Hg), a low flow condition (2 L/min, 2,500 rpm, 370 mm Hg), and a near surge condition (2 L/min, 3,000 rpm, 550 mm Hg). The flow visualization results demonstrated that the flow within the impeller was well aligned with the impeller blades except near the inlet at the high flow condition. In contrast, the flow through the outlet was well aligned at the high flow condition while there was evidence of particle impact at the design condition, and the flow was disturbed at the low flow and near surge conditions. The indices of hemolysis (IH) for the 3 operating conditions at 2,500 rpm were 0.0082 ± 0.0026 (mean ± SD) for the design condition, 0.0035 ± 0.0014 for the high flow condition, and 0.0326 ± 0.0050 for the low flow condition. The indices for high and low flow were significantly different from that for the design condition (p < 0.05). The IH for the near surge condition (0.0748 ± 0.0039) was significantly higher than that for all other conditions (p < 0.05). In addition to de scribing the flow patterns within the Isoflow, this study independently validated St. Jude Medical's reported IH at the design condition and showed how that IH significantly changed based on operating conditions.     

人真皮来源淋巴管内皮细胞的流式细胞仪分选和生物学特点

目的用流式细胞仪分选培养人真皮来源淋巴管内皮细胞,研究其生物学特点。方法采用中性蛋白酶及胶原酶消化包皮组织获得真皮细胞悬液．应用流式细胞仪检测和分选Podoplanin＋和Podoplanin-／CD34＋细胞．所获细胞进行体外培养。传代细胞进行免疫荧光及RT-PCR方法检测LECs特异标志的表达,低密度脂蛋白吞噬、鼠尾胶原三维培养检测功能特点,MTT法及氚标记法测定细胞增殖周期和低氧条件对其增殖的影响。结果人真皮细胞中CD31＋,CD34＋和Podoplanin＋细胞所占比例分别是6．0％,4．4％和1.4％。Podoplanin＋CD34＋细胞在单层培养时形成内皮细胞典型的铺路石样外观,表达内皮细胞特异性标志CD3l及吞噬DiI-Ac-LDL和三维培养微管形成功能。Podoplanin＋细胞表达淋巴管内皮细胞特异性标志Prox-1,Ang2和VEGFIR-3．和CD34＋细胞间具有显著性差异。两组细胞生长曲线相似均于接种至培养板后的3～5d逐渐进入对数生长期,接种后的6—8d均进入停滞期。在缺氧环境下,氯化钴浓度为50μM和100μM时刺激细胞增殖,当浓度大于200μM细胞增殖明显受到抑制。结论应用流式细胞仪可以富集人真皮来源淋巴管内皮细胞和血管内皮细胞．尽管两者表达特异性分子标志不同,其在三维培养和缺氧条件下生长特点相似．     

口腔正畸结合修复治疗错颌畸形伴第一磨牙缺失的效果

目的 探究口腔正畸结合修复治疗在错颌畸形伴第一磨牙缺失患者中的应用效果。方法 选取 2021年1月-2023年1月于本院进行治疗的90例错颌畸形伴第一磨牙缺失患者作为研究对象,根据治疗方法 不同分为对照组和试验组,各45例。对照组给予传统牙齿修复治疗,试验组给予口腔正畸结合修复治疗, 比较两组咀嚼功能、牙周健康指标、口腔修复效果及不良反应发生情况。结果 两组治疗后咀嚼效率、咬 力值均高于治疗前,且试验组高于对照组（P ＜0.05）;两组治疗后牙龈指数（GI）、出血指数（BI）、探 诊深度（PD）均降低,且试验组低于对照组（P ＜0.05）;试验组口腔修复优良率为95.56%,高于对照组 的77.78%（P ＜0.05）;两组不良反应发生率比较,差异无统计学意义（P ＞0.05）。结论 错颌畸形伴第一 磨牙缺失患者采用口腔正畸结合修复治疗,能够提高咀嚼效率、咬力值,改善牙周健康指标,降低不良反 应发生率,提升口腔修复优良率,值得临床应用。     

牙齿缺失患者行即刻种植牙法的临床疗效

目的 探究牙齿缺失患者实施即刻牙种植或常规牙种植治疗后的效果。方法 选取我院2019年4月12日-2022年4月12日收治的54例牙齿缺失患者作为研究对象,采用随机数字表法分为参考组和研究组,各27例。参考组实施常规牙种植,研究组实施即刻牙种植,比较两组种植成功率、红色美学指数、种植体稳定性系数以及不良反应发生情况。结果 两组种植成功率比较,差异无统计学意义（P＞0.05）;研究组治疗后3、6个月后PES分值及ISQ评分均高于参考组,差异有统计学意义（P ＜0.05）;研究组不良反应发生率为3.70%,低于参考组的33.33%,差异有统计学意义（P ＜0.05）。结论 对牙齿缺失患者实施即刻牙种植后,患者牙齿美观度与牙齿稳定系数也更高,不良反应少,且具有相同的种植成功率,值得临床应用。     

Assessment of Bovine Platelet Life Span with Biotinylation and Flow Cytometry

Reduced platelet life span is associated with the implantation of a variety of cardiovascular devices and may be used as a gauge of device biocompatibility. In the bovine model, platelet life span has previously been assessed with radioisotope labeling of removed platelets followed by reinjection and periodic gamma counting of blood samples. We report here the use of protein-reactive biotin (sulfo- N -hydroxysuccinimido [NHS]-biotin) as an alternative to radioisotope techniques whereby reinjected biotinylated platelets are subsequently detected in blood samples using phycoerythrin-streptavidin and flow cytometric techniques. Platelet life span was quantified in a normal calf (4.9 days) and in a calf prior to (6.1 days) and following (3.1 days) implantation of a Nimbus Axial Flow Pump ventricular assist device. The assessment of bovine platelet life span with biotinylation and flow cytometry avoids the technical, regulatory, and safety considerations associated with radioisotope usage and appears readily amenable to application in cardiovascular device testing.     

Study of Secondary Flow in Centrifugal Blood Pumps Using a Flow Visualization Method with a High-Speed Video Camera

Abstract Four pump models with different vane configurations were evaluated with flow visualization techniques using a high-speed video camera. These models also were evaluated through in vivo hemolysis tests using bovine blood. The impeller having the greatest fluid velocity relative to the impeller, the largest velocity variance, and the most irregular local flow patterns in the flow passage caused the most hemolysis. Even if the pumps were operated at almost the same speed (rpm) at the same output, the impeller showing more irregular flow patterns had a statistically greater rate of hemolysis. This fact confirms that the existence of local irregular flow patterns in a centrifugal blood pump deteriorates its hemolytic performance. Thus, to optimize the design of the pump, it is very important to examine the secondary flow patterns in the centrifugal blood pump in detail using flow visualization with a high-speed video camera.