Natural history of trisomy 18 and trisomy 13: II. Psychomotor development

Developmental data were abstracted from medical records on 50 trisomy 18 individuals ranging in age from 1 to 232 months and 12 trisomy 13 individuals ranging in age from 1 to 130 months. Data on the age when trisomy 18 and trisomy 13 children achieved developmental skills were collected from a larger group of 62 trisomy 18 individuals and 14 trisomy 13 individuals whose families filled out parent questionnaires. Developmental quotient (DQ), defined as developmental age divided by chronological age, averaged 0.18 for trisomy 18 and 0.25 for trisomy 13. There was a dramatic drop in DQ from infancy to later childhood. The highest DQs and the greatest variation in DQs were in the first 2–3 years of life. Developmental ages in 7 skill areas were significantly different, with daily living and receptive language having the highest values and motor and communication skills having the lowest. When chronological age was taken into account, there was no significant difference in DQs in the same 7 skill areas, although there was a trend that was similar to the pattern of differences with developmental age. Older children could use a walker, understand words and phrases, use a few words and/or signs, crawl, follow simple commands, recognize and interact with others, and play independently. Walking and some toileting skills were also reported for trisomy 13. Although individuals with trisomy 18 and trisomy 13 were clearly functioning in the severe to profound developmentally handicapped range, they did achieve some psychomotor maturation and always continued to learn. © 1994 Wiley-Liss, Inc.     

强磁场对幼年大鼠生长发育的影响

将幼年Ｗｉｓｔａｒ大鼠分别于１０日龄和２０日龄时两次暴露于１０Ｔ稳态磁场中，每次３０ｍｉｎ，观察强磁场对幼年大鼠生长发育的影响。与对照组相比，４０日龄时强磁场组的生长体重无明显差异，心、肝、脾、肾、脑、垂体、性腺的重量亦无明显差异，但肾上腺重量显著增加。提示稳态１０Ｔ磁场可引起应激反应，但对生长发育无明显影响。     

重庆城乡育龄妇女中介生育率变量研究

影响妇女生育率的直接因素,如妇女已婚比、避孕及人工流产等的定量分析是卫生人口统计分析中的重要内容。本文应用美国人口学者Bongaarts提出的中介生育率变量模型就重庆城乡妇女生育率直接影响因素作一定量研究     

Retinal growth and cell addition during embryogenesis in the teleost, Haplochromis burtoni.

Neurogenesis of the developing embryonic retina is described for the African cichlid fish, Haplochromis burtoni, from 4 days post fertilization until all cell phenotypes are generated (day 7). Cell addition and differentiation both begin at the same absolute location which later becomes the central retina. As observed in most other vertebrates, cones and ganglion cells differentiate first, followed by amacrine and bipolar cells. Rod photoreceptors, which are added late, differentiate last. Changes in retinal thickness, retinal stretching, cell size, and cell density were measured during development. From day 4 through 7, there is an increase in retinal thickness largely due to the expansion of the inner plexiform layer (IPL) and outer nuclear layer (ONL). The inner nuclear layer (INL) decreases in thickness and there is a transient decrease in the density of cells in the scleral portion of the INL. Cells increase in size in the ganglion cell layer (GCL) and the vitread INL, decrease in size in the sclerad INL, and remain the same in the ONL. Changes in the density of the cell layers were observed: the density of ONL cells increased, the density of GCL cells decreased, and INL cells increased then decreased. From day 4 to day 6, eye growth is entirely due to cell addition because no retinal stretching was observed in the ONL or the horizontal layer. During this same developmental period, the pattern and rate of neurogenesis were measured in the differentiated portion of the retina by means of 3H-thymidine labeling. A small number of cell divisions within the differentiated INL precede the onset of cell divisions in the ONL. The number of 3H-thymidine labeled cells within the INL increases at a low rate consistent with an asymmetric pattern of cell division characteristic of stem cells. In contrast, cell divisions in the ONL increase exponentially, consistent with a symmetric pattern of cell division characteristic of progenitor cells. Double-label experiments (3H-thymidine and a rod specific opsin antibody) show that some of the symmetrically dividing cells in the ONL express the rod specific opsin within 2 days, suggesting that these dividing cells are rod progenitors. Although we do not hae conclusive evidence, these developmental processes support the hypothesis that stem cells within the INL could be the source of rod precursors in the embryonic teleost retina.     

Impact response of periodontal tissues

A new impact response method using a fracture of a pencil-lead to produce an excitation pulse is proposed. Impact excitations (rectangular pulse, triangular pulse and half-sine pulse) are strictly given in physical and mathematical definitions and complete solutions to the impact excitations are provided for Noyes' model of the human tooth. When a relatively long triangular pulse is applied to Noyes' model, which can express the physical characteristic of periodontal tissues, a sinusoidal damped vibration of a single degree-of-freedom model is approximately obtained. The acceleration response is characterised by the physical parameters (T, δ and A_o) and mechanical elements (m₁, c₁ and k) of which a single degree-of-freedom model is composed. By means of this method, the values of the parameters and elements in the cases of healthy maxillary, healthy mandibular and pathological mandibular incisors are obtained. The single degree-of-freedom model can express the high-frequency spectra of Noyes' model. The pathological tooth is characterised by a longer damped time constant and a larger acceleration maximum. This impact response method can effectively be applied to clinical diagnosis in view of the physical parameters and mechanical elements which have been derived.     

Laying the Cytotaxonomic Foundations of a New Model Grass, Brachypodium distachyon (L.) Beauv.

Brachypodium distachyon is a ubiquitous, temperate grass species which is being developed and exploited as an alternative model to rice, in order to gain access to important syntenic regions of the genomes of less tractable relatives such as wheat. As part of this initiative, this paper describes for the first time the cytotaxonomy of members of the polyploid series of this species, and challenges the assumption that the series evolved simply by chromosome doubling. In situ hybridization using genomic DNA probes and rDNA markers uncovers a hybrid origin of several of the polyploid ecotypes, and sheds light upon the complex evolution of this species and its close relatives.     

经咽旁入路选择性切除大鼠垂体前叶的研究

目的研究经咽旁入路选择性的切除大鼠垂体前叶，以制备大鼠垂体前叶激素缺乏模型如生长激素（GH）缺乏模型。方法经腹侧咽旁入路，运用显微神经外科技术经基蝶骨底选择性地切除垂体前叶。然后采用竞争免疫沉淀法检测大鼠生长激素的含量，术后统计死亡率、成功率。结果切除垂体前叶后大鼠的死亡率为26．7％，成活率为73．3％，全切率为91％；成功制备大鼠模型的GH显著低于假手术组和对照组。结论运用显微外科技术可以成功的选择性的切除大鼠垂体前叶，制备出垂体前叶激素如生长激素缺乏的动物模型。     

钙池操纵的Ca2+通道的激活机制研究进展

钙池操纵的Ca~(2 )通道(store-operated Ca~(2 ) channels,SOC)是非兴奋细胞Ca~(2 )内流的主要通道之一,参与多种病理和生理过程,在钙信号通路的研究中,SOC的激活机制一直是人们关注的焦点之一,迄今为止,钙内流因子模型(Ca~(2 ) innux factor model,CIF model)和构象耦联模型fconformational coupling model)受到广泛关注.部分学者已经从很多不同类型的细胞中提取出CIF,并证实钙非依赖性的磷脂酶A_2(Ca~(2 )-independent phospholipase A_2,iPLA_2)作为CIF的底物,在某些类型细胞的SOC激活过程中发挥重要作用,并进一步提出了ER- CIF-iPLA_2-CaM-LysoPLs-SOC通路模型.瞬时受体电位(transient receptor potential,TRP)通道蛋白与1.4,5-磷酸肌醇受体(inositol 1,4,5 trisphosphate receptor,IP_3R)的结构连接作为构象耦联模型的基础已被广泛证实,随着对IP_3R,Ryanodine受体、肌动蛋白等在钙信号通路中所发挥作用的深入研究,构象耦联模型将得到不断补充和完善.SOC激活机制的破解,将对进一步完善非兴奋细胞的钙通道特性及其调节机制理论带来重大突破.