心外膜的发育

心外膜是覆盖在心脏外层的间皮组织。心外膜来源于脏壁中胚层的前心外膜,后者位于心管流入极附近。心外膜的部分细胞通过上皮间充质转化进入心外膜下层,随后形成血管内皮、成纤维和平滑肌细胞,最终导致冠脉系统的形成。心外膜细胞可能形成心肌细胞,并且可能是心脏驻留干细胞的来源。因此,它在心脏修复治疗中发挥巨大作用。本文回顾了该领域的最新研究进展并且提出了目前存在的问题。     

遗传谱系示踪技术揭示小鼠胚胎前体心外膜向心外膜转化过程

心外膜的形成是胚胎心脏发育的关键生理过程之一。利用遗传谱系示踪技术示踪观察前体心外膜向心外膜细胞转化过程,具有重要的科学研究价值。本研究拟利用Tbx18+前体/心外膜祖细胞遗传谱系示踪模型,揭示胚胎心外膜的起源及前体心外膜向心外膜转化的过程。利用整胚和切片原位杂交技术揭示,Tbx18 mRNA特异性表达于胚龄（E）9.5 d小鼠胚胎前体心外膜;故Tbx18是前体心外膜的特异性标记基因。利用整胚X-Gal染色,揭示报告基因Lacz在E9.5 d遗传谱系示踪模型鼠胚前体心外膜中大量表达,此时报告基因从前体心外膜逐渐迁移并开始少量表达于心外膜。Lacz在E10～E10.5 d双杂合鼠胚前体心外膜中表达逐渐减少,而在心外膜组织中逐渐增多;在E11.5 d,报告基因在前体心外膜中表达基本消失,而在心外膜组织中大量表达。切片进行X-Gal染色也揭示,报告基因Lacz定位于早期胚胎前体心外膜及心外膜。免疫荧光染色证实,早期胚胎心外膜细胞呈现未分化的祖细胞状态。通过报告基因的表达变化模式揭示,胚胎心外膜的形成经历了启动、转化、完成3个阶段;E9.5～11.5 d左右这个时间段发生的前体心外膜向心外膜转化,可能是心外膜形成的主要来源和形式。     

阿托伐他汀对肥胖家兔心房肌及心外膜脂肪中致心房颤动炎症因子的影响

目的:探讨肥胖家兔心外膜脂肪、血液、心房肌中致房颤炎症因子C反应蛋白(hs-CRP)、白细胞介素-6(IL-6)、白细胞介素-12(IL-12)、肿瘤坏死因子a(TNF-α)水平及阿托伐他汀的干预作用.方法:45只家兔随机分为普通饮食组(n=15)、肥胖饮食组(n=15)和阿托伐他汀干预组(n=15),肥胖饮食组预先给予高蛋白高脂饲料喂养4周制成肥胖模型(超重20％),肥胖组给予他汀喂养4周.ELISA法测定三组家兔血液、心肌、心外膜脂肪hs-CRP、IL-6、IL-12、TNF-α的水平.比较普通组、肥胖组、他汀干预组hs-CRP、IL-6、IL-12、TNF-α的水平,并进行统计学分析.结果:①肥胖组血清、心房肌、心外膜脂肪hs-CRP、IL-6、IL-12、TNF-α.的水平均高于普通组(P＜0.05);心房肌、心外膜脂肪中hs-CRP、IL-6、IL-12、TNF-α的水平均明显高于血液(P＜0.05).②肥胖他汀干预组血清、心房肌、心外膜脂肪hs-CRP、IL-6、IL-12、TNF-α的水平均低于肥胖组(P＜0.05).结论:肥胖可导致促房颤炎症因子的表达升高,心外膜脂肪中炎症因子表达高于心房肌,心房肌中炎症因子表达高于血液,心外膜脂肪组织可能是促房颤炎性因子的来源,参与了房颤的发生、发展,可能为始动环节,肥胖患房颤风险增高,阿托伐他汀可降低这种危险.     

核桃试管不定根的组织学研究

以核桃品种‘新早丰’试管嫩茎为试材,采用二步生根法诱导生根,对其试管苗不定根发生发育过程进行了解剖学研究。结果表明:核桃试管嫩茎内未发现潜伏根原基;诱导生根后,不定根原基起源于形成层,特别是髓射线正对的形成层部分,属于诱生根原基型;不定根上的侧根起源于中柱鞘细胞。核桃试管嫩茎不定根的发育过程可分为4个阶段:(1)形成层细胞分裂;(2)转变为分生组织细胞群(即根原始细胞);(3)细胞群发育成可见的根原基; (4)根原基内细胞继续分裂分化形成根尖的外形,其内发育出维管束,并向外生长,穿过皮层,突破茎表皮。在组织培养条件下长出的不定根内部解剖构造为典型的初生构造,移栽后68 d出现次生构造。另外,试管苗根毛出现与否及其发育状况受基质理化性质的影响,即生态条件可以改变组织发生及其形状。     

小鼠胚胎心包内动脉心外膜的形成及其细胞的分布变化

目的探讨小鼠胚胎心包内动脉心外膜的起源、形成及其所含细胞在心包内主、肺动脉管壁发育过程中可能的作用。方法取胚龄E9.5—E16的小鼠胚胎石蜡包埋连续切片,进行免疫组织化学染色。提取及培养E13小鼠胚胎心包内主、肺动脉组织原代心外膜祖细胞,进行免疫荧光染色。结果 E9.5—E10.5小鼠胚胎,心外膜逐渐形成并分布于心房、房室管和心室壁外表面,但流出道壁心外膜尚未形成;E11—E11.5小鼠胚胎,流出道非心肌部逐渐分隔为心包内升主动脉和肺动脉干,动脉心外膜开始出现在心包腔背侧壁以及与之相连的流出道壁远端;E12.5—E16小鼠胚胎,心包内主、肺动脉完全分隔,第二生心区前体细胞与动脉心外膜向平滑肌细胞分化,动脉瓣膜内也可见动脉心外膜来源的心外膜细胞。结论小鼠胚胎流出道非心肌部心外膜来自于动脉端心包腔背侧壁脏壁中胚层,动脉心外膜来源的间充质细胞可以进入动脉中膜,参与动脉壁的发育,同时参与动脉瓣膜的发育。     

心外膜脂肪与冠心病关系的研究进展

心外膜脂肪是沉积在心脏周围,特别是围绕在冠状动脉周围的内脏脂肪.心外膜脂肪可合成众多的脂肪细胞因子,通过旁分泌和滋养血管分泌作用于临近的冠状动脉或心脏,影响冠心痛的发生发展.对心外膜脂肪及其分泌的脂肪细胞因子的深入研究将为冠心病的防治提供新的关注靶点.     

蜈蚣草胚胎发育的观察

用石蜡切片技术观察了蜈蚣草(Pteris vittata L.)的胚胎发育过程.结果表明:蜈蚣草的胚胎由受精卵发育而来.合子最初3次的分裂顺序为X-Y-Z;球形胚最早分化出的组织是基足,其后几乎同时分化出第一叶原始细胞和第一根原始细胞,继而分别分化出第一叶原基和第一根原基,再后来才形成茎干原基;当第一叶、第一根形成时,茎干原基仍不活跃.总结出蜈蚣草的胚胎发育模式图,并讨论了有关分化的作用和意义.     

心脏发育中的细胞凋亡

重点讨论了心脏发育过程中主要的细胞凋亡以及信号串级联,这些信号串往往伴随着有序的形态学上的事件.细胞凋亡主要发生在胚胎心脏中非心肌的隔室中,其隔室由心内膜、心外膜和神经嵴衍生的细胞组成.这些信号的级联包含了潜在生长转化因子的激活,导致心肌细胞的迁移以及随后的心内膜垫的心肌化.错误的细胞凋亡将导致心脏发育的异常.     

心脏动脉极的形成

目前已发现与生心区形成心管这一过程有密切关系的关键基因和信号分子.对称的生心区后部促使心肌前体细胞形成心脏的流入区域或静脉极.最近在鸡和鼠胚胎中已经鉴定:心肌前体细胞群在咽中胚层中位于早期心管的前部.这种前部导致心脏的流出区域或动脉极处的心肌的产生.因此,脊椎动物的心脏起源于两种心肌前体细胞.这些细胞通过不同的基因程序有规律地出现.心区前部的发现对于解释突变鼠的心脏缺陷和研究人类先天性心脏病有非常重要的意义.     

128道心外膜电位标测系统的设计

心外膜电位标测是一种重要的心脏电生理研究方法,特别适用于房颤等复杂心律失常电生理机制的研究。128道心外膜电位标测系统由柔性电极、放大器、数据采集卡以及相应的软件组成,可用于心外膜实时标测。通过对标测结果的分析可以确定心律失常的起源部位和传导路径,为临床诊断、治疗提供重要依据。     

A Unique Protease Cleavage Site Predicted in the Spike Protein of the Novel Pneumonia Coronavirus (2019-nCoV) Potentially Related to Viral Transmissibility

正Dear Editor,In December 2019, a novel human coronavirus caused an epidemic of severe pneumonia(Coronavirus Disease 2019,COVID-19) in Wuhan, Hubei, China(Wu et al. 2020; Zhu et al. 2020). So far, this virus has spread to all areas of China and even to other countries. The epidemic has caused 67,102 confirmed infections with 1526 fatal cases     

Curcuminoids as inhibitors of thioredoxin reductase: A receptor based pharmacophore study with distance mapping of the active site

Curcumin is the yellow pigment of turmeric that interacts irreversibly forming an adduct with thioredoxin reductase (TrxR), an enzyme responsible for redox control of cell and defence against oxidative stress. Docking at both the active sites of TrxR was performed to compare the potency of three naturally occurring curcuminoids, namely curcumin, demethoxy curcumin and bis-demethoxy curcumin. Results show that active sites of TrxR occur at the junction of E and F chains. Volume and area of both cavities is predicted. It has been concluded by distance mapping of the most active conformations that Se atom of catalytic residue SeCYS498, is at a distance of 3.56 from C13 of demethoxy curcumin at the E chain active site, whereas C13 carbon atom forms adduct with Se atom of SeCys 498. We report that at least one methoxy group in curcuminoids is necessary for interation with catalytic residues of thioredoxin. Pharmacophore of both active sites of the TrxR receptor for curcumin and demethoxy curcumin molecules has been drawn and proposed for design and synthesis of most probable potent antiproliferative synthetic drugs.     

Comparative morphology of the carpel in the Liliaceae: Hewardieae, Petrosavieae, and Tricyrteae

The young pistils in the melanthioid tribes, Hewardieae, Petrosavieae and Tricyrteae, are uniformly tricarpellate and syncarpous. They lack raphide idioblasts. All are multiovulate, with bitegmic ovules. The Petrosavieae are marked by the presence of septal glands and incomplete syncarpy. Tepals and stamens adhere to the ovary in the Hewardieae and the Petrosavieae but not in the Tricyrteae. Two vascular bundles occur in the stamens of the Hewartlieae and Tricyrtis latifolia. Ventral bundles in the upper part of the ovary of the Hewardieae are continuous with compound septal bundles and placental bundles in the lower part. Putative ventral bundles occur in the alternate position in the Tricyrteae and putative placental bundles in the opposite. position in the Petrosavieae. The dichtomously branched stigma in each carpel of the Tricyrteae is supplied by a bifurcated dorsal bundle.     

Selection with two alleles and complete dominance

For a plant selection model with frequency-independent viabilities, fertilities and selfing rates, it is shown that apart from global fixation, for certain parameter combinations a protected polymorphism and facultative fixation (either allele may become fixed according to initial frequencies) may both occur. Facultative fixation requires different selling rates for the dominant and recessive type. Protection of the polymorphism requires resource allocation for male and female function. In this connection the problem of purely genetically caused population extinction is discussed.
For general frequency dependence and regular segregation, the chances for establishment of a completely recessive gene are compared to those of a completely dominant gene. It is proven that the process of establishment of the recessive gene, despite a fitness advantage, may be considerably endangered by drift effects if random mating prevails. The recessive gene may reach the same effectivity in establishment as a dominant gene, only if the recessive homozygote mates exclusively with its own type during the period of establishment.     

Perinatal Vertical Transmission of Chikungunya Virus in Ruili,a Town on the Border between China and Myanmar

正Dear Editor,Chikungunya virus (CHIKV), an arbovirus in the family of Togaviridae, genus Alphavirus, is transmitted by the A.aegyptii or A. albopictus mosquito, and causes disease in humans characterized by fever, rash, and arthralgia (Silva and Dermody 2017; Suhrbier 2019). It was first reported in 1953 in Tanzania, and caused only a few outbreaks and sporadic cases in Africa and Asia in last century. However, in the epidemic in 2004, CHIKV acquired mutations that conferred enhanced transmission by the A. albopictus mosquito(Schuffenecker et al. 2006). Since then, it has successively caused outbreaks in Africa, the Indian Ocean, South East Asia, the South America, and Europe (Zeller et al. 2016).