新鲜组织块标本经乙醇直接固定二年的流式细胞术DNA分析

本文报道了一种实体组织用于DesoxyribonucleicAcid(DNA)分析的Flowcy tometry(FCM) )样品保存新方法 ,即新鲜组织块乙醇直接固定法。所用样品为头颈部肿瘤手术切除的新鲜标本 3 0例 ,每例标本重约 0 5～ 1 g ,均等分为两份 ,1份置 70 %乙醇直接固定 ,室温放置 ,待两年后FCM检测。另一份置生理盐水中立即行流式细胞术DNA分析。两组样品经机械法制成单细胞悬液 ,PI染色后上机检测。结果显示 :从两组样品的DNA直方图分析 ,CV(coefficiencyofvariation)值、GO/G1、S及G2 /M各期比率无显著差异 (P >0 0 5)。我们认为在样品收集短期内难以完成 ,需积累保存 ,或需保存半年以上者 ,且不具备低温冷冻设备的条件下 ,新鲜组织块乙醇直接固定法是优于将组织块先制备成单细胞悬液再行乙醇固定的流式细胞术DNA样品保存方法     

Blood flow velocity in the common carotid artery in humans during graded exercise on a treadmill

Cerebral blood volume flow and flow velocity have been reported to increase during dynamic exercise, but whether the two increase in parallel and whether both increases occur as functions of exercise intensity remain unsettled. In this study, blood flow velocity in the common carotid artery was measured using the Doppler ultrasound method in eight healthy male students during graded treadmill exercise. The exercise consisted of stepwise progressive increases and decreases in exercise intensity. The peak intensity corresponded to approximately 85% of maximal oxygen consumption. During this exercise, the heart rate (f _c), mean blood pressure (BP) in the brachial artery and mean blood flow velocity (_cc) in the common carotid artery increased as functions of exercise intensity. At the peak exercise intensity, (f _c), BP and _cc increased by 134.5%, 20.5% and 51.8% over the control levels before exercise (P < 0.01), respectively. The resistance index (RI) and pulsatility index (PI) were determined from the velocity profile and were expected to reflect the distal cerebral blood flow resistance. The RI and PI increased during the graded exercise, but tended to decrease at the highest levels of exercise intensity. As _cc increased with increases in exercise intensity it would be expected that cerebral blood flow would also increase at these higher intensities. It is also suggested that blood flow velocity in the cerebral artery does not proportionately reflect the cerebral blood flow during dynamic exercise, since the cerebral blood flow resistance changes.     

Time-resolved particle image velocimetry and laser doppler anemometry study of the turbulent flow field of bileaflet mechanical mitral prostheses

Dynamic particle image velocimetry (PIV) was applied to the study of the flow field associated with prosthetic heart valves. The results were compared with those of laser Doppler anemometry (LDA). Anatomically and antianatomically oriented Jyros (JR) and St. Jude Medical (SJM) valves were compared in the mitral position to study the effects of valve design on the downstream flow field. The experimental program used a dynamic PIV system utilizing high-speed, high-resolution video to map the true time-resolved velocity field inside the simulated ventricle. This system was complemented by a study using the more traditional LDA system for comparison. Based on the experimental data, the following general conclusions can be made. High-resolution dynamic PIV can capture true chronological changes in the velocity and turbulence fields. It also produces very detailed velocity and turbulence information comparable to the LDA results. In the vertical measuring plane that passes both the center of the aortic and mitral valves (A-A section), the two valves (the SJM and the JR) show distinct circulatory flow patterns when the valve is installed in the antianatomical orientation. Small differences in valve design can generate noticeable differences, particularly during the accelerating flow phase. The SJM valve maintains a relatively high velocity through the central orifice; the curved leaflets of the JR valve generate higher velocities with a divergent flow during the accelerating and peak flow phases. In the velocity field directly below the mitral valve and normal to the previous measuring plane (B-B section), where characteristic differences in valve design will be visible, symmetrical twin circulations were observed because of the divergent nature of the flow generated by the two inclined half-disks installed in the antianatomical orientation. The SJM valve, with a central downward flow near the valve, is contrasted with the JR valve, which has a peripheral downward circulation with higher, turbulent stresses.     

Preponderance for either α or β-adrenoceptor mediated sensitization in the rat submaxillary gland

The sensitivity of the rat submaxillary gland was examined 3–4 weeks after either parasympathetic decentralization or sympathetic decentralization or denervation. The threshold doses for secretion of saliva of parasympathomimetic (methacholine) and sympathomimetic (noradrenaline, adrenaline, phenylephrine and isoprenaline) drugs were estimated and the amount of saliva secreted in response to supraliminal doses of these drugs was measured. Each type of operation caused the development of a supersensitivity that involved all three types of receptors, i.e. muscarinic cholinoceptors, alpha;-adrenoceptors and β-adrenoceptors. Following parasympathetic decentralization the sensitization was predominantly mediated via α-adrenoceptors, and also via cholinoceptors. Following sympathetic decentralization or denervation the postjunctional sensitization was predominantly mediated via β-adrenoceptors; most of the supersensitivity to noradrenaline, adrenaline and phenylephrine found after sympathetic denervation was of the prejunctional type. An increase in receptor density and an intracellular arrangement where the response of cholinoceptors and α-adrenoceptors is mediated via one pathway and the response of β-adrenoceptors via another are suggested as factors that may be of importance for the development of the postjunctional supersensitivity. The present study shows that the traffic of secretory impulses in the sympathetic nerve is of importance for the level of sensitivity of the secretory cells. Since postjunctional supersensitivity following sympathetic denervation did not exceed that following sympathetic decentralization it is suggested that under normal conditions a continuous release of noradrenaline from the nerve endings is of little importance for the level of sensitivity.     

流式细胞术检测细胞毒方法的建立

目的：建立一种用流式细胞仪测定细胞介导细胞毒活性的方法。方法：用羧基荧光素二醋酸盐琥珀酰亚胺酯(CFSE)标记靶细胞，再用碘化丙碇(PI)标记DNA筛选细胞膜已破坏的靶细胞。效靶比为100：1—6．25：1，共孵育时间为1-6小时，流式细胞仪收集1000个靶细胞并测定被杀细胞的百分率。结果：CFSE是合适的标记靶细胞的荧光染料，18小时后也能很好地区分效靶细胞；靶细胞的自然死亡率低于5％；杀伤百分率随着效靶比和共孵育时间的增加而增加。最佳效靶比为50：1—25：1，共孵育时间为2—4小时。结论：CFSE／PI双荧光染料标记的流式细胞分析检测细胞毒具有多个优点：避免放射性试剂的应用，敏感性增强，单细胞水平的分析。     

经皮椎体后凸成形术治疗骨质疏松性椎体压缩骨折

目的初步探讨应用球囊扩张椎体后凸成形术治疗骨质疏松性椎体压缩骨折的临床疗效。方法应用球囊扩张椎体后凸成形术治疗骨质疏松性椎体压缩骨折患者24例28个椎体，并随访4～11个月，平均8个月。结果所有患者手术均获成功，无脊髓神经损伤，病椎疼痛缓解，后凸畸形平均矫正20°，随访期间，疗效满意，无病椎高度丢失。结论应用经皮椎体成形术治疗骨质疏松性椎体压缩骨折能明显改善患者疼痛症状，恢复椎体高度，矫正后凸畸形，是一种安全的微创方法。     

Distinct pathways for constitutive endocytosis of fully conformed and non-conformed L(d) molecules

PROBLEM: To characterize the constitutive internalization of major histocompatibility complex (MHC) class I molecules, we have studied the expression of completely conformed (full) and unconformed (empty) L(d) molecules on non-polarized murine P815 cells. METHODS OF STUDY: Spontaneous endocytosis of L(d) molecules was induced by cycloheximide, an inhibitor of protein synthesis, and their disappearance from the cell surface was determined by flow cytometry. In order to investigate the mechanism of internalization, a palette of inhibitors of endocytosis and vesicular transport was used. RESULTS: Inhibitors of clathrine endocytosis did not influence the internalization of L(d) molecules. Inhibitors of caveolar endocytosis and inhibitors of endolysosomal degradation prevented down-regulation of empty, but not of full L(d) molecules. CONCLUSIONS: Empty L(d) molecules are internalized mostly by caveolar endocytosis and full L(d) molecules use a different pathway, neither clathrine-mediated nor caveolar. After internalization, full L(d) molecules are probably degraded and empty L(d) molecules recycle between endosomal compartment and the cell surface before they enter into the degradation compartment.     

Physics-Driven CFD Modeling of Complex Anatomical Cardiovascular Flows—A TCPC Case Study

Recent developments in medical image acquisition combined with the latest advancements in numerical methods for solving the Navier-Stokes equations have created unprecedented opportunities for developing simple and reliable computational fluid dynamics (CFD) tools for meeting patient-specific surgical planning objectives. However, for CFD to reach its full potential and gain the trust and confidence of medical practitioners, physics-driven numerical modeling is required. This study reports on the experience gained from an ongoing integrated CFD modeling effort aimed at developing an advanced numerical simulation tool capable of accurately predicting flow characteristics in an anatomically correct total cavopulmonary connection (TCPC). An anatomical intra-atrial TCPC model is reconstructed from a stack of magnetic resonance (MR) images acquired in vivo. An exact replica of the computational geometry was built using transparent rapid prototyping. Following the same approach as in earlier studies on idealized models, flow structures, pressure drops, and energy losses were assessed both numerically and experimentally, then compared. Numerical studies were performed with both a first-order accurate commercial software and a recently developed, second-order accurate, in-house flow solver. The commercial CFD model could, with reasonable accuracy, capture global flow quantities of interest such as control volume power losses and pressure drops and time-averaged flow patterns. However, for steady inflow conditions, both flow visualization experiments and particle image velocimetry (PIV) measurements revealed unsteady, complex, and highly 3D flow structures, which could not be captured by this numerical model with the available computational resources and additional modeling efforts that are described. Preliminary time-accurate computations with the in-house flow solver were shown to capture for the first time these complex flow features and yielded solutions in good agreement with the experimental observations. Flow fields obtained were similar for the studied total cardiac output range (1–3 l/min); however hydrodynamic power loss increased dramatically with increasing cardiac output, suggesting significant energy demand at exercise conditions. The simulation of cardiovascular flows poses a formidable challenge to even the most advanced CFD tools currently available. A successful prediction requires a two-pronged, physics-based approach, which integrates high-resolution CFD tools and high-resolution laboratory measurements.     

Computational simulations of mitral regurgitation quantification using the flow convergence method: Comparison of hemispheric and hemielliptic formulae

Mitral regurgitation results from the incomplete closure of the mitral valve, and the noninvasive diagnosis of this disease remains an important clinical goal. In this study, steady flow computer simulations were used to evaluate flow convergence method for flow rate estimation. The hemispheric and hemielliptic formulae were compared for accuracy in the presence of complicating factors such, as ventricular confinement, orifice shape, and aortic outflow. Results showed that in the absence of aortic outflow and ventricular confinement, there was a plateau zone where the hemispheric formula approximated the true flow rate, independent of orifice shape. However, in the presence of complicating factors such as aortic outflow and ventricular confinement, there was no clear zone where the hemispheric formula could be applied. The hemielliptic formula, however, worked in, all cases, regardless of chamber size or magnitude of aortic outflow. Therefore, application of the hemielliptic formula shold be considered in future clinical studies.     

Interleukin-21 is a T-helper cytokine that regulates humoral immunity and cell-mediated anti-tumour responses

Cytokines and their receptors represent key targets for therapeutic intervention. Ligands are being used to supplement cell numbers that become depleted as a result of disease (organ failure, infection) or subsequent disease treatments (i.e. chemotherapy). Conversely, the inhibition of target cell binding by cytokines is an established strategy for abrogating pathologic cellular activities common to many immunological diseases. Considerable effort in biomedical research is being focused on the cytokine families that play a dominant role in regulating immunity and then prioritizing each member for its therapeutic potential. Currently, the interleukin-2 (IL-2) family of cytokines is widely recognized for its central involvement in controlling lymphocyte function and is the most explored for medical utility. Collectively, these proteins (or their antagonists) are either marketed drugs or have received advanced testing for an impressive array of indications including cancer, infectious disease, transplantation, inflammation and allergic asthma. Here we review the current understanding of IL-21, the most recent member of this cytokine family to be discovered. As will be discussed, IL-21 shares many of the same attributes as its relatives in that it has broad immunoregulatory activity and can modulate both humoral and cell-mediated responses. Its ability to stimulate durable anti-tumour responses in mice defines one therapeutic indication that merits clinical development.