奶牛皱胃变位病因及发病机制研究进展

奶牛皱胃变位是指皱胃的正常解剖位置发生改变,导致消化机能障碍的内科疾病。此病多发于高产奶牛,造成了巨大的经济损失。论文通过对遗传、品种、胎次及生产水平、发病时期、营养和新陈代谢及环境等来综述奶牛皱胃变位的病因,从皱胃弛缓学说和机械因素学说两方面综述其发病机制研究进展,为该病的有效预防和控制提供理论基础。     

两株H5N1亚型禽流感病毒的基因分析及其在不同宿主中致病性的比较

为了解两株高致病性禽流感病毒(HPAIV)的分子特征及其对不同宿主的致病性,本研究对DK/HuN/4/08和CK/GX/2/09进行全基因组序列的测定,分析结果表明:两个病毒分离株HA基因的裂解位点均具有HPAIV特有的基序(341RRR(R)KR345/346),并且均属于Clade2.3.2分支,基因组同源性在97.4%～98.3%之间。致病性试验显示,两个病毒分离株均能够以106EID50感染量在3 d内引起鸡全部死亡,并且各脏器均检测到高滴度的病毒含量;两者在SPF鸭中呈现不同的致病性,CK/GX/2/09在4 d内可以使感染鸭100%死亡,而DK/HuN/4/08只引起25%的死亡率;同样在小鼠试验中,两者致病力差异与在鸭体中的反应一致,其MLD50分别为1.63 log10EID50和6.2 log10EID50。本研究表明,这两株遗传背景相似的HPAIV在鸡、鸭和小鼠中的致病性不同,为进一步利用反向遗传技术研究这两株病毒对水禽和哺乳动物致病力差异的分子机制奠定了基础。     

胸膜肺炎放线杆菌毒力因子研究进展

胸膜肺炎放线杆菌是引起猪传染性胸膜肺炎的重要病原。在APP致病过程中各种毒力因子发挥着决定性的作用,且致病机理较为复杂。目前,疫苗免疫是预防和控制该病的有效措施。研制亚单位疫苗及基因工程苗具有良好的应用价值,而了解和认识APP的毒力因子的特性是开展这一工作的基础。     

奶牛皱胃变位发病机理研究进展

近20年来,我国奶牛集约化饲养的规模在大中城市近郊地区迅速扩大,其皱胃变位的发病率也有明显增加。调查发现,平均有3.3%的奶牛会发生皱胃变位,产前3周到产后4周的围产期是发生此病的危险期。其中有85%表现为左方变位(left displace,LD),15%表现右方变位(right displace,RD)。文章从皱胃弛缓、机械性因素、胃壁损伤、某些营养物质缺乏、有毒物质慢性中毒、遗传因素及饲养管理等方面阐述了皱胃变位的可能发病原因及可能的发病机理,从而对该病的实验室检验指标进行描述和分析,以便建立系统的诊断思路。     

细胞凋亡在肾脏疾病中的作用

细胞凋亡是基因调控的细胞生理性死亡形式 ,是一种主动、自发性的过程 ,是目前生物学和医学界的研究热点。文章通过对细胞凋亡的形态学、生物化学、免疫化学和分子生物学的检测方法、促进细胞凋亡和抑制细胞凋亡的基因、以及细胞凋亡与肾脏疾病的关联作一综述。旨在阐明细胞凋亡在肾小球肾炎、肾小管疾病以及继发性肾脏疾病等肾脏疾病发病机制中的重要作用     

从抑郁共病失眠机制探寻抑郁症新药研发的方向

抑郁症是一种常见的情感障碍类精神疾病,失眠是包括抑郁障碍在内的诸多精神疾病的独立危险因素,失眠不仅是抑郁的症状之一,抑郁与失眠是一种循环往复持续进展的一种共同疾病状态。本文就近年来抑郁症与失眠发病共同机制作一综述,初步探寻研发抑郁症新药的方向。     

The Reoviridae family

The members of the Reoviridae family are extremely varied in host ranges and have such diverse natural histories that it is compelling to conclude that their structural asset and replication strategy are uniquely successful in evolutionary terms. It follows that their study addresses fundamental aspects of virology, besides the ones which are customary with important pathogens affecting humans, animals and plants. We deal here with the present taxonomy of the family Reoviridae and of its genera, two of which (Orbivirus and Rotavirus) are treated separately in this issue. Along with a cursory presentation of the remaining genera, we give a concise update of recent findings on the genus Orthoreovirus.     

Fine Structure of the Early Interaction of Lily Roots with Fusarium oxysporum f.sp. lilii

The early interaction of lily roots with the cortical rot pathogen Fusarium oxysporum f.sp. lilii was studied using roots of lily bulblets grown in Hoagland's solution, inoculated with the pathogen, and sampled up to 48h later. Conidia produced germ tubes within 6h, which extended towards and into the mucilage covering the root elongation zone, and along and into the anticlinal grooves and middle lamellae of epidermal cells. By 24–48h, infecting hyphae had reached the periclinal walls and intercellular spaces between the epidermis and the outermost cells of the cortex. Penetration of intercellularly growing hyphae directly across host cell walls was not observed; invasion of the cell lumen only occurred by gradual infringing of hyphae upon successive primary wall layers. Non-cellulosic wall appositions rich in vesicles and covered by a cellulosic protective-like layer were formed in response to approaching hyphae in resistant cv.Connecticut King, but rarely in susceptible cv. Esther which seemed more susceptible to plasmolysis and rot. Finger-like projections of the appositions into the host cell cytoplasm likely represent early stages of transfer cell formation.     

Experimental Salmonellosis in Guinea-pigs: Haematological and Biochemical Studies

Some haematological and biochemical parameters were studied in guinea-pigs infected intraperitoneally with Salmonella dublin 493 at 1×10⁶ viable cells per animal. The infected animals showed a rise in temperature within 24 h, followed by depression and loss of body weight. On the 15th day post infection, haematological studies revealed a significant increase in the total leukocyte count due to both lymphocytosis and neutrophilia, and a decrease in the total erythrocyte count and haemoglobin concentration. There was also a significantly higher mean corpuscular volume and lower mean corpuscular haemoglobin concentration, indicating a macrocytic hypochromic anaemia. The infection caused a significant increase in alanine aminotransferase activity and creatinine, blood urea nitrogen and globulin concentrations, and a decrease in albumin and triiodothyronine. There was no significant effect on serum total protein or on thyroxine, or in the activity of aspartate aminotransferase in the serum.     

小麦纹枯病菌胞外蛋白酶致病机理的研究

 将小麦纹枯病菌(Rhizoctonia cerealis Vander Hoeven)产生的一种类胰蛋白酶作用于小麦细胞壁,经测定酶作用后底物中的蛋白含量及产物中羟脯氨酸含量的变化,证明了该酶能够降解寄主细胞壁结构蛋白。电镜观察该酶对活体小麦组织超微结构影响的结果显示,该酶能够降解细胞中的膜蛋白。活体内蛋白酶活性检测结果表明,小麦纹枯病菌在小麦组织内还能产生类胰蛋白酶之外的其它蛋白酶。