The Hypothalamic-Pituitary-Thyroid (HPT) Axis in Birds and Its Role in Bird Development and Reproduction

This article reviews thyroid function and its hypothalamic-pituitary-thyroid (HPT) axis control in birds with emphasis on the similarities and differences in thyroid function compared to mammals and other vertebrate classes. Thyroid hormones are important in metabolism and the thermogenesis required for homeothermy in birds, as in mammals, the other homeothermic class of vertebrates. Thyroid hormones play important roles in development and growth in birds, as is the case for all vertebrate classes. The developmental effects of thyroid hormones in birds are presented in the context of differences in precocial and altricial patterns of development and growth with emphasis on oviparous development. The sections on thyroid hormone actions include discussion of effects on the development of a number of tissue types as well as on seasonal organismal processes and interactions of the thyroid axis with reproduction. The current picture of how environmental chemicals may disrupt avian thyroid function is relatively limited and is presented in the context of the assessment endpoints that have been used to date. These endpoints are categorized as thyroid and HPT axis endpoints versus target organ endpoints. The final section discusses two recommended assay protocols, the avian two-generation toxicity assay and the avian one-generation assay, and whether these protocols can evaluate thyroid disruption in birds.     

Ontogenic characterization of gene expression in the developing neuroendocrine system of the chick

The neuroendocrine system consists of five major hypothalamic-pituitary hormone axes that regulate several important metabolic processes, and it develops in all vertebrates during embryogenesis. In order to define initiation and establishment of these five axes, mRNA expression profiles of hypothalamic releasing and release-inhibiting factors, their pituitary receptors, and pituitary hormones were characterized during the second half of embryogenesis and first week post-hatch in the chick. Axis initiation was defined as the age when pituitary hormone mRNA levels began to increase substantially, and establishment was defined as the age when mRNA for all components had reached maximum expression levels. The adrenocorticotropic axis appears established by e12, as there were no major increases in gene expression after that age. Hypothalamic thyrotropin-releasing hormone and pituitary thyroid-stimulating hormone β-subunit increased between e10 and e18, indicating establishment of the thyrotropic axis during this period. Pituitary growth hormone substantially increased on e16, and hypothalamic growth hormone-releasing hormone did not increase until e20, indicating that somatotropic axis activity is established late in embryonic development. Lactotropic axis initiation is evident just prior to hatch, as pituitary prolactin and vasoactive intestinal peptide receptor 1 did not increase until e18 and e20, respectively. Hypothalamic gonadotropin-releasing hormone 1 increased after hatch, and pituitary luteinizing hormone β-subunit expression remained low until d3, indicating the gonadotropic axis is not fully functional until after hatching. This study is the first to characterize major hypothalamic and pituitary components of all five neuroendocrine axes simultaneously and considerably increases our understanding of neuroendocrine system establishment during development.     

肠道菌群与脑-肠轴功能相互影响的研究进展

人体肠道内的菌群参与了许多生理功能的维持和疾病的发生。作为大脑和胃肠道功能相互调节的重要桥梁,脑-肠轴功能的正常发挥是肠道菌群维持稳定的条件。脑-肠轴紊乱可激活肠黏膜免疫,对肠道菌群产生影响,使菌群结构发生改变。反之,肠道菌群结构改变亦会影响神经系统发育,导致脑-肠轴功能紊乱,其中迷走神经和血清代谢物质在脑-肠轴功能的调节中发挥重要作用。本文就肠道菌群与脑-肠轴功能相互影响的研究进展作一综述。     

5-羟色胺转运体在肠道疾病中的研究进展

5-羟色胺(5-HT)是脑-肠轴中的重要神经递质,参与胃肠动力和感觉的调节过程。5-羟色胺转运体(SERT)可再摄取5-HT,并将其灭活、降解,是调控5-HT表达水平的重要物质。近年来诸多研究表明,SERT表达异常与肠易激综合征(IBS)、炎症性肠病(IBD)、慢传输型便秘等多种肠道疾病密切相关。本文就SERT在肠道疾病中的研究进展作一综述。     

一种尖牙控轴直丝托槽的结构设计

目的 设计一种用于错畸形的正畸治疗的新型托槽——尖牙控轴直丝托槽,对其结构设计和应用原理进行探讨分析.方法 定性设计矫治器的结构,托槽两个对角旋转翼与另两个对角翼可以通过旋转轴发生转动,能灵活选择放入弓丝前不锈钢丝结扎托槽与放入弓丝后弹性结扎托槽等结扎方式.结果 设计出一种尖牙正畸控轴直丝托槽,其特征是两对角托槽翼与另两个对角翼可以通过旋转轴发生转动,从而改变托槽槽沟的高度及宽度.结论 使用尖牙控轴托槽时,可以通过结扎尖牙控轴托槽的合龈翼来选择采取不同的矫治系统.     

Toward an Empirically Based Classification of Personality Pathology

A number of investigations have utilized factor analysis or similar data analytic methods to examine the empirical validity of the Diagnostic and Statistical Manual of Mental Disorders classification system of Axis II personality pathology. This article reviews analyses of the Axis II cluster structure and the latent structure of individual personality disorder criteria. Overall, these studies do not provide sound empirical support for the current personality disorder organization described in the Diagnostic and Statistical Manual of Mental Disorders . They highlight the need for identifying the latent dimensions of personality pathology in order to create a different representation that would more accurately correspond to both a theoretical and functional model of personality disorder. Preliminary research identifying consensus across datasets is summarized. Clinical implications of these findings and future directions for research on personality pathology are discussed.     

不同轴向伸长率下兔股动、静脉的顺应性变化

目的：探讨不同轴向伸长率下兔股动、静脉的顺应性变化,以及对临床修复血管损伤时方法选择的影响。方法：以兔正常股动、静脉血管标本为研究对象,通过血管压力－轴向应变试验及检测血管轴向伸长率,获取兔正常股动、静脉顺应性变化规律。结果：顺应性不仅与压力有关,而且同轴向伸长率有关,在内压强为动脉血压时,兔股动脉血管在伸长率为１．９时比其正常生理伸长率１．５８下的横截面积减少４０％。静脉也有相似变化规律。结论：     

Radiology of postnatal skeletal development

Composites of C1 and C2 were analyzed in various roentgenographic projections to elucidate osseous interrelationships and the effect of overlap of different portions of these two vertebrae in standard radiographic projections during differing stages of postnatal chondro-osseous transformation. In anteroposterior projections the dentocentral synchrondrosis of C2 normally was located below the inferior rim of the C1 anterior ossification center. The upper extent of the dens ossification center was behind this anterior C1 center. The overlap made visualization of the ossiculum terminale difficult. The spinous process of C1 could be confused with the ossiculum. In tranverse projections, the normal laxity characteristic of young children allowed considerable variation in rotational interrelationships. Various degrees of such instability are illustrated. In lateral views variation of the anterior contour of the dens was significant. Such variation must be considered developmental due to the location and direction of growth of the chondrum terminale and interactive modeling between C1 and C2 to allow extension at this particular joint.