颅神经嵴干细胞成牙本质样细胞分化诱导的体内实验研究

目的观察诱导颅神经嵴干细胞(cranial neural crest stem cell,CNCSC)后的裸鼠体内成牙本质样细胞表型分化,探讨CNCSC用于牙再生研究的可行性。方法颅神经管组织块无血清条件培养法获取CNCSC,体外经成纤维生长因子8(FGF8)、骨形态发生蛋白2(BMP2)、转化生长因子β1(TGFβ1)、牙本质基质非胶原蛋白等因子诱导后,与胶原-壳聚糖三维凝胶支架复合植入裸鼠背部皮下,免疫组织化学方法检测型胶原表达、牙本质涎磷蛋白(DSPP)表达,鉴定其成牙本质样细胞表型分化特征。结果诱导后CNCSC植入体内后1月表现为型胶原及DSPP阳性表达,2月后DSPP表达增强,局部区域可见极性栅栏状排列的细胞分布,并可见明显的细胞外基质形成。结论CNCSC在体内可向成牙本质样细胞表型分化,为进一步开展牙再生研究奠定了基础。     

安氏Ⅱ类错[牙合]拔牙与非拔牙矫治病例牙槽嵴吸收的对比研究

目的：了解拔牙与非拔牙矫治在治疗安氏Ⅱ类错[牙合]时牙槽嵴高度的变化情况。方法：选取双期矫治病例16例,摆式矫治器病例18例及拔牙矫治病例20例,治疗前后均拍摄上前牙根尖片,比较上前牙治疗前后”CEJ—AC距离”在三个治疗组中的平均变化量,并作方差分析及组间LSD—t检验。结果：治疗结束时,三治疗组的CEJ—AC变化量存在组间差别,并具有统计学意义如〈0．05）,其中双期矫治组和摆式矫治器组的CEJ—AC分别增加了0．19mm和0．21mm,两组间无统计学差异（p〉0．05）,均小于拔牙矫治组的0．41mm,并有显著的统计意义（p〈0．001）。三治疗组在治疗结束时的CEJ—AC距离均不超过2mm。结论：双期矫治、摆式矫治器及拔牙矫治在治疗安氏Ⅱ类错[牙合]时,均会造成牙槽嵴高度下降,其中拔牙矫治的下降程度较为严重,但三种方法均未造成具有临床意义的牙槽骨丧失。     

有机磷农药中毒患者血液中性粒细胞的变化及意义

目的：探讨急性有机磷农药中毒(AOPP)患者血液白细胞(WBC)、中性粒细胞(N)百分数及N形态学改变的临床意义。方法：根据患者入院时中毒程度设轻、中、重度中毒组及健康对照组。分别在入院后第1、7天抽静脉血1mL做WBC及分类计数(包括N占WBC总数的百分数，N毒性指数及核棘突积分)；健康对照组门诊采血一次做同样检测。结果：中毒第1天，除轻度中毒组WBC计数一项正常外，各中毒组上述各项均显著升高(与对照组比较P＜0．05和P＜0．01)。中毒第7天，轻度中毒组除中毒指数1项外，其余各项均恢复正常；中、重度中毒组则除中度中毒组WBC 1项外，其余各项均仍显著升高(与对照组比较P＜0．05和P＜0．01)。但中度中毒组中毒第7天与第1天比较，WBC、核棘突积分和中毒指数均有显著降低(P＜0．05和P＜0．01)，而重度中毒组与中毒第1天比较，各项指标均未见显著变化(均P＞0．05)。结论：AOPP患者血液中WBC计数、N百分数、N形态学改变及恢复的速度与中毒的严重程度有关，动态观察上述各项指标，对了解患者病情及转归，指导治疗有重要帮助。     

Cellular and molecular mechanisms in the development of a cleft lip and/or cleft palate; insights from zebrafish (Danio rerio)

Human cleft lip and/or palate (CLP) are immediately recognizable congenital abnormalities of the face. Lip and palate develop from facial primordia through the coordinated activities of ectodermal epithelium and neural crest cells (NCCs) derived from ectomesenchyme tissue. Subtle changes in the regulatory mechanisms of NCC or ectodermal epithelial cells can result in CLP. Genetic and environmental contributions or a combination of both play a significant role in the progression of CLP. Model organisms provide us with a wealth of information in understanding the pathophysiology and genetic etiology of this complex disease. Small teleost, zebrafish (Danio rerio) is one of the popular model in craniofacial developmental biology. The short generation time and large number of optically transparent, easily manipulated embryos increase the value of zebrafish to identify novel candidate genes and gene regulatory networks underlying craniofacial development. In addition, it is widely used to identify the mechanisms of environmental teratogens and in therapeutic drug screening. Here, we discuss the value of zebrafish as a model to understand epithelial and NCC induced ectomesenchymal cell activities during early palate morphogenesis and robustness of the zebrafish in modern research on identifying the genetic and environmental etiological factors of CLP.     

Role of the extracellular matrix in neural crest cell migration

Development of the neural crest involves a remarkable feat of coordinated cell migration in which cells detach from the neural tube, take varying routes of migration through the embryonic tissues and then differentiate at the end of their journey to participate in the formation of a number of organ systems. In general, neural crest cells appear to migrate without the guidance of long-range physical or chemical cues, but rather they respond to heterogeneity in the extracellular matrix that forms their migration substrate. Molecules such as fibronectin and laminin act as permissive substrate components, encouraging neural crest cell attachment and spreading, whereas chondroitin sulphate proteoglycans are nonpermissive for migration. A balance between permissive and nonpermissive substrate components seems to be necessary to ensure successful migration, as indicated by a number of studies in mouse mutant systems where nonpermissive molecules are over-expressed, leading to inhibition of neural crest migration. The neural crest expresses cell surface receptors that permit interaction with the extracellular matrix and may also modify the matrix by secretion of proteases. Thus the principles that govern the complex migration of neural crest cells are beginning to emerge.     

Iliac crest free flap and submental island flap for maxillary reconstruction

Abstract

The iliac crest free flap is one of the most reliable flaps for maxillary reconstruction because of the large amount of bone provided and the chance to harvest both muscle and skin. However, reconstruction of maxillary through-and-through defects requires special skills to be managed. Simultaneous replacement of oral lining and external tissue with the same features as the resected skin is difficult to achieve with conventional techniques and the use of flaps association is often necessary to ensure acceptable cosmetic and functional results. In the case presented the submental island flap was a good choice to overcome these difficulties.     

Developmental and evolutionary significance of the mandibular arch and prechordal/premandibular cranium in vertebrates: revising the heterotopy scenario of gnathostome jaw evolution

The cephalic neural crest produces streams of migrating cells that populate pharyngeal arches and a more rostral, premandibular domain, to give rise to an extensive ectomesenchyme in the embryonic vertebrate head. The crest cells forming the trigeminal stream are the major source of the craniofacial skeleton; however, there is no clear distinction between the mandibular arch and the premandibular domain in this ectomesenchyme. The question regarding the evolution of the gnathostome jaw is, in part, a question about the differentiation of the mandibular arch, the rostralmost component of the pharynx, and in part a question about the developmental fate of the premandibular domain. We address the developmental definition of the mandibular arch in connection with the developmental origin of the trabeculae, paired cartilaginous elements generally believed to develop in the premandibular domain, and also of enigmatic cartilaginous elements called polar cartilages. Based on comparative embryology, we propose that the mandibular arch ectomesenchyme in gnathostomes can be defined as a Dlx1-positive domain, and that the polar cartilages, which develop from the Dlx1-negative premandibular ectomesenchyme, would represent merely posterior parts of the trabeculae. We also show, in the lamprey embryo, early migration of mandibular arch mesenchyme into the premandibular domain, and propose an updated version of the heterotopy theory on the origin of the jaw.     

Abstract Digest—The Cutting Edge

Abstract

This paper describes a rapid protocol for iliac crest biopsies with embedding in LR White plastic to facilitate diagnosis of osteomalacia. Sections were cut and stained for light and electron microscopy using traditional staining methods with minor modifications. Total processing time was within three days. (The J Histotechnol 13:125, 1990)