炎症反应与白细胞迁移

人体自我防御中,白细胞定向迁移是先天性免疫必不可少的步骤。然而白细胞在创伤部位的募集也导致了炎症反应的发生。白细胞的移动和它周围微环境的变化精确地调控着一系列级联事件。趋化因子在白细胞迁移过程中起着重要的作用,对介导细胞黏附和迁移的趋化因子的深入研究将有助于对疾病病理状态的了解和控制。     

高职化学在畜牧兽医专业中的教学问题与创新

作为畜牧兽医专业具有基础和前沿学科的化学，它对于该专业起着重要的作用。随我国经济发展，人民生活水平的提高，畜牧养殖业规模的扩大和数量的增多，学习和运用好作为专业领跑者的化学专业，有助于更好地推动和发挥畜牧兽医专业的实践作用。为此，做好化学与畜牧兽医专业两者的衔接与密切联系，对于高职教学是尤为重要的。但是，在教学实践中也发现存在一些问题亟需改革，基于此，对这两个专业间的问题进行探索。     

营养化学感应系统研究进展

人和动物消化器官的营养化学感应系统是胃肠上皮细胞受体对食物信息感受与内脏迷走神经元之间信息传递和互作的复杂信号传递系统。营养化学感应系统由独立化学感应细胞组成,具有形态学的多样性,在体内分布十分广泛,这为其功能作用的发挥奠定了基础。研究表明,营养化学感应系统在调控采食、消化与吸收、肠道生长与功能、肠道防御机制以及宿主与微生物的互作中起着重要作用,并且不同细胞型之间具有不同的功能。它们是营养物质消化吸收的重要调控途径,其功能研究有助于化学感应机制的营养学作用的理解。因此,为了更好的理解和研究营养化学感应系统,本文就营养化学感应系统的分布及其功能作用进行了简要综述。     

草鱼CC趋化因子基因CCL24及其可变剪接

CC趋化因子是一类能够促进动物体内炎症部位的各种白细胞的补充、激活和黏附的趋化性细胞因子家族,是鱼类天然免疫系统的重要组成部分。分析了从草鱼肠道cDNA文库中筛选到的CC趋化因子基因CCL24,并克隆了阅读框区域内的基因组序列。序列分析表明,CCL24基因由4个外显子和3个内含子组成;外显子拼接的序列与CCL24cDNA序列完全一致,编码95个氨基酸,有2个相邻的半胱氨酸(CC),为典型的CC趋化因子亚家族成员。此外,还发现草鱼CCL24基因存在可变剪接现象,第1内含子没有被剪切掉的非正常转录本翻译后可能产生没有CC趋化因子活性的24个氨基酸的短肽,而且这种转录本在精巢、头肾、皮肤、肝胰脏、肠道、肌肉、肾脏等组织均检测到;而正常剪接的CCL24转录本,仅在肾脏和肠道中检测到,且其表达量要明显低于非正常剪接的转录本。     

草鱼CC趋化因子基因CCL24及其可变剪接

CC趋化因子是一类能够促进动物体内炎症部位的各种白细胞的补充、激活和黏附的趋化性细胞因子家族,是鱼类天然免疫系统的重要组成部分。分析了从草鱼肠道cDNA文库中筛选到的CC趋化因子基因CCL24,并克隆了阅读框区域内的基因组序列。序列分析表明,CCL24基因由4个外显子和3个内含子组成;外显子拼接的序列与CCL24cDNA序列完全一致,编码95个氨基酸,有2个相邻的半胱氨酸(CC),为典型的CC趋化因子亚家族成员。此外,还发现草鱼CCL24基因存在可变剪接现象,第1内含子没有被剪切掉的非正常转录本翻译后可能产生没有CC趋化因子活性的24个氨基酸的短肽,而且这种转录本在精巢、头肾、皮肤、肝胰脏、肠道、肌肉、肾脏等组织均检测到;而正常剪接的CCL24转录本,仅在肾脏和肠道中检测到,且其表达量要明显低于非正常剪接的转录本。     

白细胞介素10对巨噬细胞源泡沫细胞趋化因子表达的影响

目的探讨白细胞介素10对单核-巨噬细胞源性泡沫细胞转化过程中趋化因子表达的影响及其机制。方法以佛波醇酯诱导THP-1单核细胞分化为巨噬细胞，在氧化型低密度脂蛋白作用下形成泡沫细胞，同时给予白细胞介素10干预，采用逆转录聚合酶链反应和凝胶阻滞试验研究单核细胞趋化蛋白1、巨噬细胞炎性蛋白5、白细胞介素8mRNA的表达变化及白细胞介素10对核因子KB活性的影响。结果在白细胞介素10作用下，泡沫细胞中单核细胞趋化蛋白1和巨噬细胞炎性蛋白5mRNA相对表达量均显著降低，且与作用时间成正相关，而白细胞介素8相对表达量变化不明显。同时白细胞介素10能显著抑制氧化型低密度脂蛋白诱导的核因子KB活化。结论白细胞介素10选择性抑制单核-巨噬细胞源性泡沫细胞形成中趋化因子mRNA的表达与有效地抑制核因子KB活性密切相关。这对降低炎症反应。减少泡沫细胞形成，延缓动脉粥样斑块形成具有重要意义。     

材料化学工程研究进展

随着科技的不断进步,材料化学已经成为材料科学的一个重要分支。材料化学在新材料的发现过程中起着重要的作用,通过不断开发合成新的材料,我国的化学工艺和纳米材料也有了非常明显的进步。本文主要介绍了材料化学工程的研究进展,阐述材料化学工程的光明前景,以促进材料化学工程更好地发展。     

细胞因子与高血压关系的研究进展

细胞因子是一种由造血、免疫系统或炎症反应中的活化细胞产生的 ,能调节细胞分化增殖和诱导细胞发挥功能的多肽、蛋白质或糖蛋白。细胞因子也是体内细胞之间相互作用的主要介质 ,在机体的免疫应答、炎症反应、造血功能 ,乃至胚胎发生、生长发育等各个方面都起着关键的作用。细胞因子的产生和相互作用对机体防御疾病和维持生理恒定有重要意义 ,细胞因子或其受体的异常增多、减少、异常分布或网络失衡等常常与疾病相关。最近十几年来 ,人们发现了几十种细胞因子并进行了大量的研究。一些细胞因子的化学结构已阐明 ,对它们的生物学功能和作用机…     

化学信息素在植物-植食性昆虫(螨类)--天敌相互关系中的作用

植物、植食性昆虫(螨类、天敌间通过各种物理因素和化学因素相互作用。近年来,随着化学生态学的发展,人们发现化学信息素在三者间的相互关系中起着非常重要的作用。本文对不同来源(植物、植食性昆虫(螨类))的化学信息素在三者关系中的作用进行了综述。     

实验探究中的变量控制

科学探究是同学们获取化学知识、认识和解决化学问题的一种重要实践活动，也是同学们的一种学习方式。新课程改革，特别强调了对学生科学探究能力的培养，因而以考查探究能力为主的探究性试题在中考试卷中便应用而生，并成为了一种固定题型，所以解答好这类试题对于提高化学成绩起着举足轻重的作用。     

The role of CCR7 in TH1 and TH2 cell localization and delivery of B cell help in vivo

Subsets of murine CD4+ T cells localize to different areas of the spleen after adoptive transfer. Na?ve and T helper 1 (TH1) cells, which express the chemokine receptor CCR7, are home to the periarteriolar lymphoid sheath, whereas activated TH2 cells, which lack CCR7, form rings at the periphery of the T cell zones near B cell follicles. Retroviral transduction of TH2 cells with CCR7 forces them to localize in a TH1-like pattern and inhibits their participation in B cell help in vivo but not in vitro. Thus, differential expression of chemokine receptors results in unique cellular migration patterns that are important for effective immune responses.     

Regulation of homeostatic chemokine expression and cell trafficking during immune responses

The chemokines CCL21 and CXCL13 are immune factors that dictate homing and motility of lymphocytes and dendritic cells in lymphoid tissues. However, the means by which these chemokines are regulated and how they influence cell trafficking during immune responses remain unclear. We show that CCL21 and CXCL13 are transiently down-regulated within lymphoid tissues during immune responses by a mechanism controlled by the cytokine interferon-gamma. This modulation was found to alter the localization of lymphocytes and dendritic cells within responding lymphoid tissues. As a consequence, priming of T cell responses to a second distinct pathogen after chemokine modulation became impaired. We propose that this transient chemokine modulation may help orchestrate local cellularity, thus minimizing competition for space and resources in activated lymphoid tissues.     

Developmental biology of T cell receptors

T cell receptors are the antigen-recognizing elements found on the effector cells of the immune system. Two isotypes have been discovered, TCR-gamma delta and TCR-alpha beta, which appear in that order during ontogeny. The maturation of prothymocytes that colonize the thymic rudiment at defined gestational stages occurs principally within the thymus, although some evidence for extrathymic maturation also exists. The maturation process includes the rearrangement and expression of the T cell receptor genes. Determination of these mechanisms, the lineages of the cells, and the subsequent thymic selection that results in self-tolerance is the central problem in developmental immunology and is important for the understanding of autoimmune diseases.     

动物源耐甲氧西林葡萄球菌的研究进展

动物源耐甲氧西林葡萄球菌感染可引起多种动物发病,这些菌株不仅对β-内酰胺类抗生素耐药,而且也对其它药物耐药,引起临床治疗的难度增加。概述了动物源耐甲氧西林葡萄球菌的发现过程、耐药机制、兽医临床分布以及传播与扩散,以引起有关学者的关注。     

Self-nonself discrimination by T cells

The alpha beta T cell receptor (TCR) recognizes antigens that are presented by major histocompatibility complex (MHC)-encoded cell surface molecules by binding to both the antigen and the MHC molecules. Discrimination of self from nonself antigens and MHC molecules is achieved by negative and positive selection of T cells in the thymus: potentially harmful T cells with receptors that bind to self antigens plus self MHC molecules are deleted before they can mount immune responses. In contrast, the maturation of useful T cells with receptors that bind foreign antigens plus self MHC molecules requires the binding of their receptor to MHC molecules on thymic epithelium in the absence of foreign antigen. The binding of the TCR to either class I or class II MHC molecules directs differentiation of the selected cells into either CD4-8+ (killer) or CD4+8- (helper) T cells, respectively.     

Chemokine Up-regulation and activated T cell attraction by maturing dendritic cells

Langerhans' cells migrating from contact-sensitized skin were found to up-regulate expression of macrophage-derived chemokine (MDC) during maturation into lymph node dendritic cells (DCs). Na?ve T cells did not migrate toward MDC, but antigen-specific T cells rapidly acquired MDC responsiveness in vivo after a subcutaneous injection of antigen. In chemotaxis assays, maturing DCs attracted activated T cells more strongly than na?ve T cells. These studies identified chemokine up-regulation as part of the Langerhans' cell maturation program to immunogenic T cell-zone DC. Preferential recruitment of activated T cells may be a mechanism used by maturing DCs to promote encounters with antigen-specific T cells.     

Natural killer cell signaling pathways

Natural killer (NK) cells are lymphocytes of the innate immune system that are involved in the early defenses against foreign cells, as well as autologous cells undergoing various forms of stress, such as microbial infection or tumor transformation. NK cell activation is controlled by a dynamic balance between complementary and antagonistic pathways that are initiated upon interaction with potential target cells. NK cells express an array of activating cell surface receptors that can trigger cytolytic programs, as well as cytokine or chemokine secretion. Some of these activating cell surface receptors initiate protein tyrosine kinase (PTK)-dependent pathways through noncovalent associations with transmembrane signaling adaptors that harbor intracytoplasmic ITAMs (immunoreceptor tyrosine-based activation motifs). Additional cell surface receptors that are not directly coupled to ITAMs also participate in NK cell activation. These include NKG2D, which is noncovalently associated to the DAP10 transmembrane signaling adaptor, as well as integrins and cytokine receptors. NK cells also express cell surface inhibitory receptors that antagonize activating pathways through protein tyrosine phosphatases (PTPs). These inhibitory cell surface receptors are characterized by intracytoplasmic ITIMs (immunoreceptor tyrosine-based inhibition motifs). The tyrosine-phosphorylation status of several signaling components that are substrates for both PTKs and PTPs is thus key to the propagation of the NK cell effector pathways. Understanding the integration of these multiple signals is central to the understanding and manipulation of NK cell effector signaling pathways.     

Use of chemokine receptors by poxviruses

Chemokine receptors serve as portals of entry for certain intracellular pathogens, most notably human immunodeficiency virus (HIV). Myxoma virus is a member of the poxvirus family that induces a lethal systemic disease in rabbits, but no poxvirus receptor has ever been defined. Rodent fibroblasts (3T3) that cannot be infected with myxoma virus could be made fully permissive for myxoma virus infection by expression of any one of several human chemokine receptors, including CCR1, CCR5, and CXCR4. Conversely, infection of 3T3-CCR5 cells can be inhibited by RANTES, anti-CCR5 polyclonal antibody, or herbimycin A but not by monoclonal antibodies that block HIV-1 infection or by pertussis toxin. These findings suggest that poxviruses, like HIV, are able to use chemokine receptors to infect specific cell subtypes, notably migratory leukocytes, but that their mechanisms of receptor interactions are distinct.     

Allergy, parasites, and the hygiene hypothesis

The increase of allergic diseases in the industrialized world has often been explained by a decline in infections during childhood. The immunological explanation has been put into the context of the functional T cell subsets known as T helper 1 (TH1) and T helper 2 (TH2) that display polarized cytokine profiles. It has been argued that bacterial and viral infections during early life direct the maturing immune system toward TH1, which counterbalance proallergic responses of TH2 cells. Thus, a reduction in the overall microbial burden will result in weak TH1 imprinting and unrestrained TH2 responses that allow an increase in allergy. This notion is contradicted by observations that the prevalence of TH1-autoimmune diseases is also increasing and that TH2-skewed parasitic worm (helminth) infections are not associated with allergy. More recently, elevations of anti-inflammatory cytokines, such as interleukin-10, that occur during long-term helminth infections have been shown to be inversely correlated with allergy. The induction of a robust anti-inflammatory regulatory network by persistent immune challenge offers a unifying explanation for the observed inverse association of many infections with allergic disorders.     

基因治疗及其在兽医学中的应用

基因治疗是20世纪90年代形成的，该技术的研究一开始就与动物医学的发展密不可分，主要是通过建立动物疾病模型分析和研究基因治疗各种层面上的问题，但它真正在兽医临床上的研究是近年才开始的。许多试验结果表明，一旦载体的安全性有了保障，基因治疗将有可能成为动物重大疫病有效预防和治疗的方法，在兽医学中有很广阔的应用前景。