Ionic mechanism underlying distinctive excitability in atrium and ventricle of the heart

心肌细胞兴奋性是维持正常的心脏活动的一个重要生理因素。本研究旨在使用全细胞膜片技术探讨豚鼠心房和心室肌细胞不同兴奋性的离子机理。结果显示,心室肌细胞兴奋性比心房肌细胞低。虽然豚鼠心室肌细胞的电压门控快nA+电流(InA)密度较低,但与其兴奋性较低并不相关,因为其在阀电位附近的可用度比率比心房肌细胞高。经典内向整流钾电流(Ik1)在心室肌细胞比在心房肌细胞更大,这可能是心室肌细胞兴奋性较低的部分原因。此外,去极化引起的有内向整流特性的瞬时外向钾电流(ITOIr)在心室肌细胞较大,并可能是其兴奋性较低的主要原因。在心室肌细胞,5μMOl/l bA2+显著抑制ITOIr,增强细胞兴奋性,并使InA激活的阈电位更负,其作用独立于对InA的影响。本研究结果证明,除经典的Ik1外,ITOIr在豚鼠心房肌和心室肌细胞的兴奋性差异形成和心肌兴奋性维持中起着主要作用。然而,ITOIr增加是否会通过降低兴奋性以保护心脏,还需要进一步研究。Cellular excitability is an important physiological factor in maintaining normal cardiac activity.The present study was designed to investigate the ionic mechanism underlying different excitability in atrial and ventricular myocytes of guinea pig heart using a whole-cell patch configuration.We found that excitability is lower in ventricular myocytes than that in atrial myocytes.Although the density of voltage-gated fast Na+ current(INa) was lower in ventricular myocytes, it would not correlate to the lower excitability since its availability was greater than that in atrial myocytes around threshold potential.Classical inward rectifier K+ current(IK1) was greater in ventricular myocytes than that in atrial myocytes, which might contribute in part to the lower excitability.In addition, the transient outward K+ current with inward rectification(Itoir) elicited by depolarization was greater in ventricular myocytes than that in atrial myocytes and might contribute to the lower excitability.In ventricular myocytes, Ba2+ at 5 μmol/L significantly inhibited Itoir, enhanced excitability, and shifted the threshold potential of INa activation to more negative, and the effect was independent of affecting INa.Our results demonstrate the novel information that in addition to classical IK1, Itoir plays a major role in determining the distinctive excitability in guinea pig atrial and ventricular myocytes and maintaining cardiac excitability.More effort is required to investigate whether increase of Itoir would be protective via reducing excitability.supportedbySunChiehYehHeartFoundationofHongKongandaGeneralResearchFund(HKU771712M)fromResearchGrantCouncilofHongKon

中医抗肝纤维化组方规律的文献研究

目的研究中医抗肝纤维化组方用药规律。方法检索中国期刊网(CNKI)1990年1月至2010年1月中医药防治肝纤维化研究的文献,统计药物的使用频次和频率,分析总结规律。结果共选取符合标准的文献80篇,其中临床研究44篇,动物实验研究36篇,所用中药共136味。临床研究文献中抗肝纤维化使用频率最高的前两类药是补虚药(27.76%)和活血化瘀药(23.62%),使用频率在1%以上的药物依次为活血化瘀药8味,补虚药7味,清热药3味,利水渗湿药2味,解表药、泻下药、止血药、消食药、理气药各1味;实验研究文献中抗肝纤维化使用频率最高的前两类药是补虚药(30.54%)和活血化瘀药(26.60%),使用频率在1%以上的药物依次为活血化瘀药7味,补虚药8味,清热药3味,利水渗湿药2味,解表药、泻下药各1味。结论补虚药和活血化瘀药是抗肝纤维化组方的基本构成要素,清热药、利水渗湿药、解表药、泻下药、止血药、消食药、理气药是主要配伍形式

非酒精性脂肪肝同病异证与肝活检病理学的相关性研究

目的:观察非酒精性脂肪肝(NAFLD)患者不同中医证型与临床指标、肝活检病理学的关系。方法:选择312例NAFLD患者进行辨证分型,均进行肝组织活检,常规判定NAFLD活动度积分(NAS)和肝纤维化分期。结果:NAFLD患者的中医证型频数分布为痰湿内阻证>肝郁脾虚证>湿热蕴结证>肝郁气滞证>痰瘀互结证。NAFLD患者性别、年龄、病程、血生化、体质量指数、肝硬度值、NAS积分等指标在不同中医证型的分布差异具有统计学意义(P<0.05)。结论:NAFLD患者痰湿内阻证、痰瘀互结证、湿热蕴结证三型NAS积分较高,故NAFLD的治疗应着重于健脾化痰、清热利湿、活血化瘀。国家自然科学基金项目(No.81503529,No.81673660,No.81873242);;福建省科技计划引导性项目(No.2015D007,No.2016D012);;厦门市科技计划项目(No.3502Z20174028);;厦门市重要重大疾病联合攻关项目(No.3502Z20179047);;福建省卫生计生医学创新科研人才培养项目(No.2018-CXB-28);;福建中医药大学基金项目(No.XB2016080);;陈国良名老中医传承工作室(厦门市卫生局资助项目);;全国第六批老中医药专家学术经验继承工作(2017年)~

Drag reduction using riblets downstream of a high Reynolds number inclined forward step flow

Micro-riblet is an efficient passive method for controlling turbulent boundary layers, with the potential to reduce frictional drag. In various applications within the transportation industry, flow separation is a prevalent flow phenomenon. However, the precise drag reduction performance of riblets in the presence of flow separation remains unclear. To address this, an inclined forward step model is proposed to investigate the interaction between riblet and upstream flow separation. The large eddy simulation (LES) method is applied to simulate the flow over geometries with different step angles and riblet positions. The results show riblets still reduce wall frictional resistance when subjected to the upstream flow separation. Remarkably, as the angle of the step increases from 0 degrees to 30 degrees, the drag reduction experiences an increment from 9.5% to 12.6%. From a turbulence statistics standpoint, riblets act to suppress the Reynold stress in the near-wall region and dampen ejection motions, thus weakening momentum exchange. Quadrant analysis reveals that with the augmentation of flow separation, the Q2 motion within the flow field intensifies, subsequently enhancing the riblet-induced drag reduction. Moreover, the position of the rib lets has a significant impact on the pressure drag. Riblets close to the point of separation enhance flow separation, altering the surface pressure distribution and thus increasing the resistance. The results reveal that when the riblets are positioned approximately 160 riblet heights away from the step, their effect on the upstream flow separation becomes negligible. The precise performance of riblets under complex flow conditions is important for their practical engineering application

Si上外延的n型3C-SiC欧姆接触研究

用LPCVD在si（111）上异质外延了n型3C-SiC，并在所外延的3C-SiC上蒸发Au／Ti，通过不同温度下的RTA（快速热退火）形成欧姆接触。用两种不同的传输线模型对Ti／3C-SiC欧姆接触的ρc（比接触电阻率）进行测量，在750℃退火后Ti／3C-SiC的ρc达到了最低值为3．68×10^-5Ω·cm^2这满足了应用的要求。AES分析结果还表明由于Ti的氧化，更高温度下的退火会使ρc增大

神经网络在DMMP红外光谱判别中的应用

介绍了神经网络在化学毒剂红外遥感监测领域应用的概况,探讨了反向传播人工神经网络分类器应用于红外光谱鉴别的可能性。用一个甲基膦酸二甲酯红外光谱数据样本集进行了实际的训练和鉴别性能预测。训练结果表明,这种分类器在一定条件下可以将95%以上的样本正确分离;预测结果表明,经过适当训练的神经网络分类器可以获得70%以上的鉴别率,具备了一定的识别能力