主动按压减压结合高频通气对心肺复苏犬的循环效应影响

目的　比较标准心肺复苏、主动按压减压心肺复苏、主动按压减压结合高频通气心肺复苏三种复苏法对心肺复苏循环效应影响 ;评价主动按压减压结合高频通气用于心肺复苏的可行性。方法　将9条犬经电击致颤制成心搏骤停模型 ,每只犬先后实施三种复苏法 ,①标准心肺复苏 ;②主动按压减压心肺复苏 ;③主动按压减压结合高频通气心肺复苏 ,实验顺序由随机法确定 ,每种复苏方法进行 5min ,待循环动力学稳定后记录收缩压、舒张压、心输出量。结果　收缩压、舒张压、心输出量均为主动按压减压结合高频通气模式大于主动按压减压心肺复苏模式 (P <0 0 1) ;主动按压减压心肺复苏模式大于标准心肺复苏模式 (P <0 0 1)。标准心肺复苏模式和主动按压减压心肺复苏模式胸外按压停顿期血压降至零 ,而主动按压减压结合高频通气心肺复苏模式血压持续稳定。结论　主动按压减压心肺复苏优于标准心肺复苏模式。主动按压减压结合高频通气心肺复苏模式既可产生较高的动脉血压、心输出量 ,又可提供充分的气体交换 ,值得进一步研究和推广应用     

Hemodynamic effects of sildenafil in patients with stable ischemic heart disease

Background: Recently the new specific phosphodiesterase-5 inhibitor sildenafil was introduced into therapy for erectile dysfunction. The hemodynamic effects of sildenafil may be potentially hazardous for patients with cardiac disease. Sildenafil has been reported to augment the hypotensive effects of nitrates. There is sparse information regarding the systemic and pulmonary hemodynamic effects of a single oral dose of sildenafil in patients with stable angina. Methods: Male patients referred for coronary angiography with diagnosis of chronic stable angina were enrolled in this study to assess the acute hemodynamic effects of sildenafil. Patients receiving long-acting or sublingual nitrates for the last 6 h before the study were excluded. Hemodynamic measurement were taken during right and left heart catheterization in the basal state and 60 min after 50 mg of oral sildenafil. Results: Twelve patients (age 53±7 years) were studied. All had stable angina CCS class II or III. Four had previous myocardial infarction. By coronary angiography, seven patients had at least one coronary artery with >70% stenosis, four had at least one with 50–70% stenosis, and one had only intimal irregularities. There were no significant effects of sildenafil on systemic or pulmonary arterial pressure, left ventricle endiastolic pressure, cardiac output, and systemic or pulmonary vascular resistance (P>0.05 for all). No adverse events were observed. Conclusion: A single oral dose of sildenafil had no significant hemodynamic effect in supine patients with stable angina. Isolated administration of sildenafil does not appear to be associated to adverse cardiovascular effects.     

Pattern formation and polarity sorting of driven actin filaments on lipid membranes

Collective motion of active matter is ubiquitously observed, ranging from propelled colloids to flocks of bird, and often features the formation of complex structures composed of agents moving coherently. However, it remains extremely challenging to predict emergent patterns from the binary interaction between agents, especially as only a limited number of interaction regimes have been experimentally observed so far. Here, we introduce an actin gliding assay coupled to a supported lipid bilayer, whose fluidity forces the interaction between self-propelled filaments to be dominated by steric repulsion. This results in filaments stopping upon binary collisions and eventually aligning nematically. Such a binary interaction rule results at high densities in the emergence of dynamic collectively moving structures including clusters, vortices, and streams of filaments. Despite the microscopic interaction having a nematic symmetry, the emergent structures are found to be polar, with filaments collectively moving in the same direction. This is due to polar biases introduced by the stopping upon collision, both on the individual filaments scale as well as on the scale of collective structures. In this context, positive half-charged topological defects turn out to be a most efficient trapping and polarity sorting conformation.

Collective motion of active matter is ubiquitous, with observations ranging from flocks of birds (1) and schools of fish (2) to propelled colloids (3). The interactions between agents in such systems lead to the formation of complex structures including clusters, swirls, or lanes of agents moving coherently (4). The structure of the emerging patterns strongly depends on both the agents’ shape and their velocity alignment mechanism. A particular case is that of elongated microscopic particles that translate along their major axis in a quasi-two-dimensional environment and only interact upon collision (5, 6). In the context of cytoskeletal systems, gliding actin filaments or microtubules propelled by molecular motors are found to be able to readily crawl over each other and only retain a weak level of alignment upon binary collisions, which eventually leads at high densities to a diverse set of patterns (7). Such resulting patterns are found to be strongly dependent on this weak microscopic alignment interaction, and therefore, even slightly tuning it causes the system to switch between polar and nematic phases, separated by a coexistence regime (8, 9). Observed structures in cytoskeletal systems with weak to moderate interactions include nematic lanes, polar waves, and vortices (10–12). Conversely, pattern formation in systems of elongated bacteria or granular matter is often based on hard interactions with a strong steric component (13–18). In this repulsion-dominated regime, particles are unable to crawl over each other and must stop upon collision. In the limiting case of spherical self-propelled particles, this kind of steric interaction can lead to a stable phase separation between stuck and moving particles, the so-called motility induced phase separation (MIPS) (19). On the other hand, in the case of elongated particles, steric effects can still act as velocity aligning mechanisms. As orientation mismatches are unstable, particles end up aligning and this leads to flocking behavior rather than to phase separation (5, 20–25). This latter case, in which strong steric constraints dominate binary interactions but alignment is still present, is poorly understood, and how modeling has to be extended to account for the emergent collective behavior of elongated, flexible agents with volume exclusion also remains still under debate (26–30). This is partly due to the lack of microscopic experimental systems allowing to explore this regime. Semiflexible cytoskeletal filaments would be the best candidate, but their volume exclusion is usually too weak. However, having them propelled by motors immobilized on a fluid membrane would be a promising route to bridge this experimental gap (31).Here, we enforce a steric repulsion-dominated interaction, leading to alignment between actin filaments by coupling myosin motors to a fluid-supported lipid bilayer. Because of the slippage of the motors on the membrane, the force propelling the filaments is too weak to enable filaments to crawl over each other and thus effectively implements a repulsion-dominated regime, with filaments stopping upon collisions. Eventually, however, because of the thermal fluctuations of their tips, filaments can align and resume motion. The experimental realization of such a microscopic binary interaction, based on volume exclusion, enables us to observe and quantify the resulting pattern formation process in a system of active semiflexible filaments. We then first characterize the interaction at the single filament scale, showing that it leads to nematic alignment. As the filaments’ density is increased, patterns of collective motion emerge, ranging from clusters to thick streams and vortices. Despite the nematic collision rule, we find the emerging structures to be locally polar. The repulsion-dominated interaction indeed introduces a polar bias not only due to the tendency of active filaments or clusters to keep moving together after a polar collision but also by forcing filaments with similar orientation to stop and accumulate when encountering an obstacle. In particular, at high densities, such an interaction leads to the formation of transient local +1/2 topological defects, which act as wedges and, therefore, effectively trap and polarity-sort motile filaments. We interpret this trapping mechanism as an analog of MIPS for elongated self-propelled particles.     

老年高血压患者心功能、外周血管阻力与血清Hcy、血脂水平的相关性研究

目的 探讨老年高血压患者心功能和外周血管阻力的变化,并分析老年高血压患者心功能、外周血管阻力与同型半胱氨酸(Hcy)、血脂水平的相关性.方法 选取2017年10月～2019年3月于山西医科大学第一医院老年病科就诊的年龄≥60岁的高血压患者126例为高血压组,并选取同期来院体检年龄≥60岁的健康体检者107名为对照组.分...     

Dune formation under bimodal winds

The study of dune morphology represents a valuable tool in the investigation of planetary wind systems—the primary factor controlling the dune shape is the wind directionality. However, our understanding of dune formation is still limited to the simplest situation of unidirectional winds: There is no model that solves the equations of sand transport under the most common situation of seasonally varying wind directions. Here we present the calculation of sand transport under bimodal winds using a dune model that is extended to account for more than one wind direction. Our calculations show that dunes align longitudinally to the resultant wind trend if the angle θ_w between the wind directions is larger than 90°. Under high sand availability, linear seif dunes are obtained, the intriguing meandering shape of which is found to be controlled by the dune height and by the time the wind lasts at each one of the two wind directions. Unusual dune shapes including the “wedge dunes” observed on Mars appear within a wide spectrum of bimodal dune morphologies under low sand availability.     

Clinical Characteristics of Patients with Hepatitis C Virus-Related Chronic Liver Disease Seropositive for Anticentromere Antibody

The association between anticentromere antibody (ACA) and hepatitis C virus (HCV) infection remains unclear. We subjected eight patients with HCV-related chronic liver disease (CLD) seropositive for ACA to a battery of clinical and laboratory tests. The patient cohort was dominated by females, and four of the eight (50%) patients had a concomitant autoimmune disease. All of the patients had high titers of ACA (≥1:320). The histological activity index scores in chronic hepatitis C (CH-C) patients with ACA were significantly higher than those in CH-C patients without antinuclear antibody (ANA) (12.8 ± 1.8 vs. 8.3 ± 4.5, P = 0.0372). The frequency of human leukocyte antigen (HLA) DR-8 in patients with HCV-related CLD seropositive for ACA was significantly higher than that in patients with CH-C seronegative for ANA (71 vs. 18%, P = 0.0108). These findings suggest that ACA is induced by chronic HCV infection in association with HLA DR-8, and that CH-C patients with ACA exhibit more severe hepatic fibrosis and inflammation than CH-C patients without ANA.     

风湿性心脏病合并重度肺动脉高压患者体外循环前、后肺血流动力学改变

目的：观察风湿性心脏病（风心病）重度肺动脉高压患者体外循环（ＣＰＢ）前、后肺血流动力学变化规律。方法：体外循环前、后用Ｓｗａｎ－Ｇａｎｚ导管监测１５例风心病重度肺动脉高压患者肺血流动力学参数。结果：ＣＰＢ前肺动脉压为３．７／２．３～１１．６／６．０ｋＰａ（２８／１７～８７／４５ｍｍＨｇ），ＣＰＢ后为２．９／１．１～１１．８／５．５ｋＰａ（２２／８～８９／４１ｍｍＨｇ）。二尖瓣替换术后肺动脉收缩压无明显降低（－９％，Ｐ＞０．０５），肺动脉舒张压（－２０％）和平均压（－１４％）均明显降低（Ｐ＜０．０５）。肺血管阻力（ＰＶＲ）在ＣＰＢ前高达６０．３±４０．９ｋＰａ·ｓ／Ｌ，ＣＰＢ后明显降低（－４０％，Ｐ＜０．０５）。回归方程为：ＣＰＢ后ＰＶＲ＝０．５４６ＰＶＲｂ＋２３．２４，Ｒ２＝０．６５１（ＰＶＲｂ为肺血管阻力基础值）。鱼精蛋白静脉用药１０例，肺动脉压升高者４例；动脉用药５例，均未发现肺动脉压改变。结论：风心病肺动脉高压患者术后大部分ＰＶＲ不能恢复正常。动脉系统用药可减少肝素鱼精蛋白复合物引起的不良反应。     

椎管内麻醉用于妇科腹腔镜手术的安全性与有效性研究

目的：研究椎管内麻醉用于妇科短小腹腔镜手术的可行性。方法：采用随机双盲法，将60例行妇科腹腔镜检查治疗手术患者（手术时间≤60min，ASAⅠ～Ⅱ级）分成两组：Ⅰ组为腰硬联合麻醉组，Ⅱ组为气管插管一静脉复合麻醉组，每组各20例。患者人室后每隔5min分别记录SBP、HR、SpO2、RR及潮气量，并于麻醉前、放气腹时、术后30min分别测定患者挠动脉血糖、血气分析，并观察术后疼痛情况。结果：两组患者PaO2、PaCO2放气腹时、术后30min较术前升高；Ⅰ组术后30min PaO2高于放气腹时（P〈0．05），Ⅱ组降低（P〉0．05）。但放气腹时Ⅰ组低于Ⅱ组（P〈0．05）；HCO3-、血糖、呼吸及血流动力学两组比较差异无显著性。Ⅰ组术后镇痛明显优于Ⅱ组。结论：椎管内麻醉可以满足妇科短小腹腔镜手术的麻醉。     

Evidence that cerebral blood volume can provide brain activation maps with better spatial resolution than deoxygenated hemoglobin

With the aim of evaluating the relative performance of hemodynamic contrasts for mapping brain activity, the spatio-temporal response of oxy-, deoxy-, and total-hemoglobin concentrations were imaged with diffuse optical tomography during electrical stimulation of the rat somatosensory cortex. For both 6-s and 30-s stimulus durations, total hemoglobin images provided smaller activation areas than oxy- or deoxy-hemoglobin images. In addition, analysis of regions of interest near the sagittal sinus vein show significantly greater contrast in both oxy- and deoxy-relative to total hemoglobin, suggesting that oximetric contrasts have larger draining vein contributions compared to total hemoglobin contrasts under the given stimulus conditions. These results indicate that total hemoglobin and cerebral blood volume may have advantages as hemodynamic mapping contrasts, particularly for large amplitude, longer duration stimulus paradigms.