Ascidian embryonic development: An emerging model system for the study of cell fate specification in chordates

The ascidian tadpole larva represents the basic body plan of all chordates in a relatively small number of cells and tissue types. Although it had been considered that ascidians develop largely in a determinative way, whereas vertebrates develop in an inductive way, recent studies at the molecular and cellular levels have uncovered several similarities in the way developmental fates are specified. In this review, we describe ascidian embryogenesis and its cell lineages, introduce several characteristics of ascidian embryos, describe recent advances in understanding of the mechanisms of cell fate specification, and discuss them in the context of what is known in vertebrates and other organisms. Developmental Dynamics 236:1748–1757, 2007. © 2007 Wiley‐Liss, Inc.     

一种拥有自主知识产权的国产可膨胀阴茎假体

勃起功能障碍是常见的男性疾病，部分ED患者在非手术治疗无效后，最终将植入阴茎假体进行治疗，且可获得满意的效果。本文简述这种疾病现状及其治疗方法，介绍一种拥有自主知识产权的国产阴茎假体的特征及其临床应用情况。     

A comparative study of plateletpheresis using Baxter Autopheresis C and Haemonetics PCS Plus

SUMMARY. This study compared plateletpheresis on the Haemonetics PCS Plus (PCS Plus) and the Baxter Autopheresis C (Auto C) using the same 100 selected donors. The number of packs meeting UK BTS/NIBSC specification (>2.2 times 10¹¹ platelets per pack) was achieved by 99% of PCS Plus and 82% of Auto C procedures. The positive correlation found between donor precount and final platelet yield was better for the PCS Plus. Both machines met U.K. specification for white-cell contamination but this was significantly greater for the Auto C. Plasma yields were similar.
As a result of this study we chose to use the PCS Plus for routine plateletpheresis in our unit. This has enabled us not only to comply with UK BTS/NIBSC specifications for apheresis platelets easily and cost effectively but also to meet our own higher specification (2.75 times 10¹¹ platelets per pack) using existing staff and without extending the working day.     

CR临床应用的几点体会

众所周知，CR是将透过人体的X线影像信息记录于影像板(image plate，IP)而不是记录在胶片上。记录在IP上的影像信息要经过读取处理和显示等步骤才能显示数字化图像。CR的设备，除X线机以外，主要有IP影像读取装置，影像存储和显示装置，以及控制用的计算机。     

fMRI技术在脑胶质瘤的应用体会

目的:利用血氧水平依赖法(BOL D)成像对患者脑胶质瘤并可能累及脑皮层功能区的患者进行功能磁共振成像(f MRI)检查,有助于外科治疗方案的制定,以提高手术的成功率和治愈率,避免重要脑功能中枢受到损伤。方法:对12例患有脑胶质瘤的患者用双手对指刺激的方法实行动态MR脑功能成像,共计5 0个动态,每次10个动态,18个层面,扫描时间为15 9s,分别间隔以等时间的静息期,检测感兴趣区正相关系数。结果:12例患者的图像采集满意,激活区均激活边缘系统,丘脑区,激活的脑功能区包括初级和次级躯体感觉区,尤以脑胶质瘤对侧激活最为显著(8例) ,同侧也有部分激活(4例)。结论:左右手对指激活特定的脑功能区,表明患者今后的恢复功能可能是对侧功能的代偿。这对外科制定手术方案,恢复的评估以及避免脑神经功能区的损伤有一定的指导意义。     

钙剂治疗轻中度妊高征临床应用分析

目的：观察钙剂治疗轻中度妊高征的临床疗效。方法：选择2007年3月-2009年12朋我院产科门诊和住院的轻中度妊高征患者50例,随机分为治疗组和对照组,治疗组给予硝苯地平5-10mg＋碳酸钙、维生素D3合成制剂1片/d;对照组给予硝苯地平5-10mg/次,根据血压变化调整每天硝苯地平用药次数,观察血压、蛋白尿的平均水平,并对结果进行统计学分析。结果：两组患者治疗2周后,平均动脉压、尿蛋白下降,血清钙含量增加,治疗组有效率为92%,对照组为80%,两组疗效比较,差异有统计学意义（P〈0.05）。结论：硝苯地平常用于高血压的治疗,但副作用较大,常需频繁地调整药物剂量,患者尤其妊高征患者对药物的顺应性较差,钙剂几乎没有副作用发生,在联合硝苯地平治疗妊高征的同时为胎儿的发育需要提供了充足的钙源,故应将补充钙剂作为临床轻中度妊高征治疗的首选措施。     

Optimal pole assignment into specified regions and its application to rotating mechanical systems

This paper considers a pole assignment problem to cluster all poles of a closed-loop system into some specified regions by introducing the complex state for systems having an isotropic property and by using the Riccati equation. The algebraic relations for the distribution of the eigenvalues of a complex matrix are used in order to cluster the poles into specified regions, which guarantees the relative stability margin, e.g. uniform damping or uniform damping ratio. The proposed scheme is essentially a combination of the pole assignment approach and linear quadratic design, taking the advantages of both. A block modal control method—an extension of recursive pole assignment—is also developed for the vibration control of rotating systems by clustering the forward and backward modes in order. Vibration control simulations with an isotropic rotor—bearing system, a magnetic bearing system and a rotating circular disc are treated in order to demonstrate the advantages of the proposed method.     

Myocardial scintigraphy — 25 years after start

The development of myocardial scintigraphy (MS) reflects the clinical success of a representative procedure in nuclear medicine. Radiopharmaceuticals for visualizing vital and damaged myocardium and techniques (planar-qualitative, planar-quantitative, SPECT-qualitative — quantitative with comparative sensitivities) are briefly reviewed with the main focus on their clinical application in coronary (CHD) and noncoronary heart disease, where recent literature from the United States and Europe is considered. The limited value of MS for screening of CHD is outlined and its present and future role in detecting asymptomatic (silent) ischemia/infarction and asymptomatic patients at professional risk is stressed. The present state of MS in coronary heart disease is discussed for single and multivessel disease, previous infarction, and risk stratification (myocardial washout, pulmonary uptake, ischemic dilation, absent heart sign), reflecting the importance of the procedure in exercise-induced ischemia as well as in ischemia at rest for prognostication of the natural and therapeutic course, i.e., therapy control (angioplasty, bypass, lysis, cardiac drugs). More marginal but upcoming clinical indications are mentioned, such as progressive systemic sclerosis, cardiac transplantation, pediatric cardiology, and problems of nephrology/urology. The normal values and the impact of digital radiology and of contrast cardiography are touched upon. Preliminary cases with ¹¹¹In-antimyosin and ^99mTc-Isonitriles are presented including correlative results between global ejection fraction determination according to gated ^99mTc-isonitrile and conventional ^99mTc-erythrocyte ventriculogram (r=0,75; n=10).Dedicated to Prof. Heinz Hundeshagen on the occasion of his 60th birthday     

Ventral specification and perturbed boundary formation in the mouse midbrain in the absence of Hedgehog signaling.

Although Hedgehog (HH) signaling plays a critical role in patterning the ventral midbrain, its role in early midbrain specification is not known. We examined the midbrains of sonic hedgehog (Shh) and smoothened (Smo) mutant mice where HH signaling is respectively attenuated and eliminated. We show that some ventral (Evx1+) cell fates are specified in the Shh-/- mouse in a Ptc1- and Gli1-independent manner. HH-independent ventral midbrain induction was further confirmed by the presence of a Pax7-negative ventral midbrain territory in both Shh-/- and Smo-/- mice at and before embryonic day (E) 8.5. Midbrain signaling centers are severely disrupted in the Shh-/- mutant. Interestingly, dorsal markers are up-regulated (Wnt1, Gdf7, Pax7), down-regulated (Lfng), or otherwise altered (Zic1) in the Shh-/- midbrain. Together with the increased cell death seen specifically in Shh-/- dorsal midbrains (E8.5-E9), our results suggest specific regulation of dorsal patterning by SHH, rather than a simple deregulation due to its absence.     

Early stages of chick somite development

We report on the formation and early differentiation of the somites in the avian embryo. The somites are derived from the mesoderm which, in the body (excluding the head), is subdivided into four compartments: the axial, paraxial, intermediate and lateral plate mesoderm. Somites develop from the paraxial mesoderm and constitute the segmental pattern of the body. They are formed in pairs by epithelialization, first at the cranial end of the paraxial mesoderm, proceeding caudally, while new mesenchyme cells enter the paraxial mesoderm as a consequence of gastrulation. After their formation, which depends upon cell-cell and cell-matrix interactions, the somites impose segmental pattern upon peripheral nerves and vascular primordia. The newly formed somite consists of an epithelial ball of columnar cells enveloping mesenchymal cells within a central cavity, the somitocoel. Each somite is surrounded by extracellular matrix material connecting the somite with adjacent structures. The competence to form skeletal muscle is a unique property of the somites and becomes realized during compartmentalization, under control of signals emanating from surrounding tissues. Compartmentalization is accompanied by altered patterns of expression of Pax genes within the somite. These are believed to be involved in the specification of somite cell lineages. Somites are also regionally specified, giving rise to particular skeletal structures at different axial levels. This axial specification appears to be reflected in Hox gene expression. MyoD is first expressed in the dorsomedial quadrant of the still epithelial somite whose cells are not yet definitely committed. During early maturation, the ventral wall of the somite undergoes an epithelio-mesenchymal transition forming the sclerotome. The sclerotome later becomes subdivided into rostral and caudal halves which are separated laterally by von Ebner's fissure. The lateral part of the caudal half of the sclerotome mainly forms the ribs, neural arches and pedicles of vertebrae, whereas within the lateral part of the rostral half the spinal nerve develops. The medially migrating sclerotomal cells form the peri-notochordal sheath, and later give rise to the vertebral bodies and intervertebral discs. The somitocoel cells also contribute to the sclerotome. The dorsal half of the somite remains epithelial and is referred to as the dermomyotome because it gives rise to the dermis of the back and the skeletal musculature. The cells located within the lateral half of the dermomyotome are the precursors of the muscles of the hypaxial domain of the body, whereas those in the medial half are precursors of the epaxial (back) muscles. Single epithelial cells at the cranio-medial edge of the dermomyotome elongate in a caudal direction, beneath the dermomyotome, and become anchored at its caudal margin. These post-mitotic and muscle protein-expressing cells form the myotome. At limb levels, the precursors of hypaxial muscles undergo an epithelio-mesenchymal transition and migrate into the somatic mesoderm, where they replicate and later differentiate. These cells express the Pax-3 gene prior to, during and after this migration. All compartments of the somite contribute endothelial cells to the formation of vascular primordia. These cells, unlike all other cells of the somite, occasionally cross the midline of the developing embryo. We also suggest a method for staging somites according to their developmental age.