Toll样受体与益生菌免疫

Toll样受体(Toll-like receptors,TLRs)是天然免疫反应中重要的细胞表面模式识别受体(pattern recognition receptors,PRRs),而益生菌在动物免疫中起着重要的作用,本文就TLRs的种类、配体类型和信号转导途径、益生菌的免疫作用、Toll样受体信号通路与益生菌的免疫作用的关系作简要综述。     

TGF-β/SMAD信号通路在哺乳动物卵巢发育调控中的作用研究进展

TGF-β/SMAD信号转导通路是典型的跨膜转导通路，该通路通过一组配体与受体结合，将细胞外的信号转导入细胞内，激活下游的SMAD蛋白、转录调节靶基因，从而介导配体对细胞的生物学作用。在卵母细胞成熟过程受到多种因子调控，其中一些细胞外信号通过TGF-β/SMAD信号通路发挥调控作用。TGF-β/SMAD信号通路主要通过不同的下游信号分子SMADs以自分泌/旁分泌途径方式发出信号，调控颗粒细胞增殖和卵母细胞生长，影响着卵巢发育。近年来，TGF-β/SMAD信号通路对卵巢发育的调控机制已成为生殖生理学领域研究热点之一，本文综述了TGF-β/SMAD蛋白的受体、TGF-β/SMAD信号通路，并分别从配体、调控因子以及与其他通路的作用关系的角度阐述了不同家畜TGF-β/SMAD通路在卵巢发育中的调控作用，为卵巢发育的调控机制研究提供思路，同时为畜牧业生产提供理论基础。     

詹纳斯激酶/信号转导蛋白转录激活因子信号通路在动物骨骼肌发育中作用的研究进展

詹纳斯激酶/信号转导蛋白转录激活因子（JAK/STAT）信号通路级联反应已被确定为肌肉发育的关键因素之一,其激活后影响骨骼肌成肌细胞的增殖、分化等。这条通路主要由3个部分组成,即詹纳斯激酶（JAK）、信号转导蛋白转录激活因子（STAT）及詹纳斯激酶受体。文章对JAK/STAT信号转导通路的基本途径及特点,以及它在动物骨骼肌修复生长过程中作用的研究进展进行总结。     

Toll样受体信号传导通路的研究进展

Toll样受体（toll like receptors,TLRs）能识别病原微生物相关分子模式,募集含有Toll/白介素-1受体（TIR）结构域的接头蛋白分子,通过髓样分化蛋白88（MyD88）依赖性信号传导通路或由β-干扰素TIR结构域衔接蛋白（TRIF）依赖性信号传导通路启动信号传导,继而引发特异性的免疫应答。作者就TLRs的结构特征、分布、配体识别、参与信号传导的接头蛋白分子及介导的信号传导通路的最新研究进展进行综述。     

垂体促性腺激素表达的受体后信号转导机制

对促性腺激素释放激素(GnRH)作用机制的研究是一个重要领域。文章综述了国内外GnRH的研究进展,认为GnRH与受体(Rs)结合后,要通过一系列的信号转导,调节和控制促卵泡激素(FSH)和黄体生成素(LH)的合成和分泌。GnRH受体后信号转导途径主要是通过3大信号转导系统完成的:环磷酸腺苷(cAMP)信号转导系统、蛋白激酶C(PKC)信号转导系统和丝裂原活化蛋白激酶(MAPK)信号转导系统。cAMP信号转导通路和PKC信号转导通路都属于G蛋白偶联的信号通路,二者最后都要通过激活MAPK信号转导系统来完成调控。这为进一步研究GnRH作用机制提供了依据,同时讨论了存在的问题,并对下一步的研究方向做出展望。     

胆汁酸调控S1PR2通路在动物炎症中的作用研究进展

胆汁酸(BAs)作为1-磷酸鞘氨醇受体2(S1PR2)上游激活物之一,可直接调控S1PR2活性,也可通过BAs相关信号通路法尼醇X受体(FXR)和G蛋白胆汁酸偶联受体5(TGR5)介导S1PR2途径.S1PR2通过平衡核因子Kappa B(NF-κB)与c-Jun氨基末端激酶(JNK)信号转导通路,调节动物体炎症.本文...     

禽类Toll样受体研究进展

Toll样受体(TLRs)是模式识别受体家族的一员,在天然免疫反应中扮演重要角色。在禽类中至今已发现10种TLRs。研究表明在机体感染病原体时,将激活TLRs并引起一系列抗病毒相关因子的上调,参与宿主抗感染免疫反应。论文主要介绍禽类TLRs的基本特征及抗病毒信号转导通路,同时对TLRs的抗微生物作用进行分析,为TLRs的分子机制研究提供参考。     

转化生长因子β1/Smads信号传导通路在哺乳动物卵巢发育中的调控作用及其作用机制

不同信号转导通路间的彼此协调保证了机体的正常运行。在众多的信号通路中,转化生长因子(TGF)β1/Smads信号传导通路越来越受到学者们的关注,已经成为分子生物学和细胞生物学研究的一大热点。已有研究证实,TGF-β1/Smads信号传导通路是调控卵泡发育的重要途径。本文就TGF-β1/Smads信号传导通路与哺乳动物卵巢卵泡的发育进行综述,分别从TGF-β受体、Smads蛋白、骨形态发生蛋白(BMP)、血小板反应蛋白1(THB-S1)、S期激酶相关蛋白1(SKP1)和其他调节机制阐述TGF-β1/Smads信号传导通路在哺乳动物卵巢发育中的调控作用及其机制,旨在引起人们对TGF-β1/Smads调控卵巢发育的关注,并为卵巢发育过程中某些疾病的治疗提供一些参考。     

Toll样受体及其对肠黏膜免疫的调节作用

Toll样受体(TLRs)是近年来备受关注的一种模式识别受体,在脊椎与非脊椎动物中具有病原体传感器的功能。TLRs对体内外特异性配体的识别是启动先天免疫的基础,并迅速增加对抗入侵病原体的保护性反应,最终激活适应性免疫。TLRs在肠道免疫对病原菌与益生菌的区分过程中发挥重要作用,同时TLRs可调控动物肠道上皮分泌抗菌肽杀灭病原菌,对肠道健康具有积极的作用。本文介绍了TLRs的种类、配体及相应的信号通路,探讨TLRs在肠道免疫调节中的关键作用。     

调控Hippo通路的因子及其研究方法

Hippo通路是由核心激酶、效应因子、辅助因子和转录因子共同组成的激酶级联反应链,调控细胞的生长、代谢和信号转导等重要过程。跨膜蛋白、机械信号、G蛋白偶联受体、营养素等均能调控Hippo通路。通过条件性小鼠敲除模型和使用靶向性化学制剂,研究人员发现姜黄素、叶酸、白藜芦醇等通过Hippo通路发挥调控细胞发育的作用,即Hippo信号通路在营养素调控动物生长方面扮演重要角色。为此本文对Hippo通路的组成、作用模式、调控因子和目前的研究方法进行综述,以期为Hippo通路在畜牧生产上的研究提供支持。     

Phase I evaluation of CCNU (lomustine) in tumor-bearing cats

1-(2-Chloroethyl)3-cyclohexyl-1-nitrosourea (CCNU) is an alkylating agent in the nitrosourea subclass. A prospective evaluation of CCNU was done to determine the maximally tolerated dosage of CCNU in tumor-bearing cats. Response data were obtained when available. Twenty-five cats were treated with CCNU at a dosage of 50-60 mg/m3 body surface area. Complete hematologic data were available for 13 cats. Neutropenia was the acute dose-limiting toxicity. The median neutrophil count at the nadir was 1,000 cells/microL (mean, 2,433 cells/microL; range, 0-9,694 cells/microL). The time of neutrophil nadir was variable, occurring 7-28 days after treatment, and counts sometimes did not return to normal for up to 14 days after the nadir. Based on these findings, a 6-week dosing interval and weekly hematologic monitoring after the 1st treatment with CCNU are recommended. The nadir of the platelet count may occur 14-21 days after treatment. The median platelet count at the nadir was 43,500 cells/microL. No gastrointestinal, renal, or hepatic toxicities were observed after a single CCNU treatment, and additional studies to evaluate the potential for cumulative toxicity should be performed. Five cats with lymphoma and 1 cat with mast cell tumor had measurable responses to CCNU. Phase II studies to evaluate antitumor activity should be completed with a dosing regimen of 50-60 mg/m3 every 6 weeks.     

Furosemide continuous rate infusion in the horse: evaluation of enhanced efficacy and reduced side effects

Continuous rate infusion (CRI) of furosemide in humans is considered superior to intermittent administration (IA). This study examined whether furosemide CRI, compared with IA, would increase diuretic efficacy with decreased fluid and electrolyte fluctuations and activation of the renin-angiotensin-aldosterone system (RAAS) in the horse. Five mares were used in a crossover-design study. During a 24-hour period, each horse received a total of 3 mg/kg furosemide by either CRI (0.12 mg/kg/h preceded by a loading dose of 0.12 mg/kg IV) or IA (1 mg/kg IV q8h). There was not a statistically significant difference in urine volume over 24 hours between methods; however, urine volume was significantly greater after CRI compared with IA during the first 8 hours ([median 25th percentile, 75th percentile]: 9.6 L [8.9, 14.4] for CRI versus 5.9 L [5.3, 6.0] for IA). CRI produced a more uniform urine flow, decreased fluctuations in plasma volume, and suppressed renal concentrating ability throughout the infusion period. Potassium, Ca, and Cl excretion was greater during CRI than IA (1,133 mmol [1.110, 1,229] versus 764 mmol [709, 904], 102.7 mmol [96.0, 117.2] versus 73.3 mmol [65.0, 73.5], and 1,776 mmol [1,657, 2.378] versus 1,596 mmol [1,457, 1,767], respectively). Elimination half-lives of furosemide were 1.35 and 0.47 hours for CRI and IA, respectively. The area under the excretion rate curve was 1,285.7 and 184.2 mL x mg/mL for CRI and IA, respectively. Furosemide CRI (0.12 mg/kg/h) for 8 hours, preceded by a loading dose (0.12 mg/kg), is recommended when profound diuresis is needed acutely in horses.     

Prevalence of gastric lesions in racing Alaskan sled dogs

Human and equine athletes are reported to have a high prevalence of gastric disease, and anecdotal evidence suggests a similar phenomenon applies to racing sled dogs. To investigate the prevalence of gastric disease in racing sled dogs, we conducted 2 gastroscopy studies on dogs competing in the annual Iditarod Sled Dog Race. A pilot study of dogs that were either dropped from the 2000 Iditarod Sled Dog Race because of illness or that finished the race indicated that, approximately 5 days after competing, 10 of 28 dogs (35%) had endoscopic evidence of gastric ulceration, erosion, or hemorrhage. The next year, an endoscopic study of 73 dogs participating in the 2001 Iditarod race was performed in order to evaluate a larger population of dogs. Data from 70 of these dogs could be used; 34 (48.5%) had ulceration, erosion, gastric hemorrhage, or some combination of these findings. When this group of 70 dogs was compared retrospectively to a control group of 87 dogs presented to the Texas A&M University (TAMU) Veterinary Medical Teaching Hospital, the Iditarod sled dogs had a significantly higher prevalence (P = .049) of gastric lesions. These findings suggest that, similar to athletes of other species, elite canine athletes have an increased prevalence of gastric disease compared to the canine population at large.     

Internal Parasites and Haematological Values in Cattle Slaughtered in Buea Subdivision of Cameroon

Tropical Animal Health and Production -     

The Epidemiology of Gastrointestinal Nematodes of Dairy Cattle in Central Kenya

The epidemiology of H. placei and of other gastrointestinal nematodes in yearling dairy cattle was examined on two farms in Kiambu District, central Kenya during each of 13 one-month periods from April 1993 to April 1994. On each farm, 32 newly weaned dairy calves were given a single dose of albendazole and then placed on experimental pastures. Twelve of the animals were designated for bi-monthly slaughter (n = 2) and analysis of worm population characteristics and 20 were designated for blood and faecal collection and for weighing. Two parasite-free tracer calves were grazed alongside the weaner calves each month throughout the study period and were also slaughtered for analysis of worm populations. Faecal egg counts, haematological and serum pepsinogen determinations, herbage larval counts, and animal live weight changes were recorded monthly. The study revealed that Haemonchus placei, Trichostrongylus axei, Cooperia spp. and Oesophagostomum radiatum were responsible for parasitic gastroenteritis and that H. placei was the predominant nematode present in the young cattle on both farms. Faecal egg counts from resident cattle and necropsy worm counts revealed that pasture larval levels were directly related to the amount of rainfall. The total worm burdens in the animals were highest during the rainy season (March–June and October–December) and lowest during the dry seasons (July–September and January–February). The very low recovery of immature larvae of H. placei from the tracer calves indicated that arrested development is not a feature of the life cycle of this parasite in central Kenya. The maintenance of the parasite population depended on continuous cycling of infection between the host and the pasture. The agroclimatic conditions of the study area were such that, in general, favourable weather conditions for the development and survival of the free-living stages of gastrointestinal nematodes existed all year round.     

Diversity of Ectoparasites in Sheep Flocks in Sa~o Paulo,Brazil

The occurrence of ectoparasites in sheep flocks is frequently reported but seldom quantified. Sheep production used to be a predominantly family activity in the state of Sa~o Paulo (Brazil), but it began to become a commercial activity in the past decade. Thus, information about the ectoparasites existing in sheep flocks has become necessary. The present data were obtained by means of questionnaires sent to all sheep breeders belonging to the `Associaça~o Paulista de Criadores de Ovinos' (ASPACO; Sa~o Paulo State Association of Sheep Breeders). Response reliability was tested by means of random visits paid to 10.6% of the respondents. Most of the properties (89.5%) reported the presence of one or more ectoparasites. Screw-worm (Cochliomyia hominivorax) was the most frequent ectoparasite (72.5%), followed by bot fly larvae (Dermatobia hominis, 45.0%), ticks (Amblyomma cajennense) and Boophilus microplus, 31.3%) and finally lice (Damalinia ovis, 13.8%). Combined infestations also occurred, the most common one being screw-worm with bot fly larvae (36.0%) followed by bot fly larvae with ticks (13.9%), screw-worm with ticks (9.3%), bot fly larvae with lice (6.9%), and ticks with lice (5.0%). The most common triple combination was screw-worm, bot fly larvae and ticks (12.8%). Breeds raised for meat or wool were attacked by bot fly larvae and ticks more often than other breeds. Lice were only absent from animals of indigenous breeds. The relationships among these ectoparasites are discussed in terms of sheep breeds, flock size, seasonality and the ectoparasitic combinations on the host.     

Chemotaxis of macrophage in inflammation

Our particular attention in this article was given to natural mediators for macrophages isolated from the sites of tissue injury. A number of chemotactic factors, which may satisfy many criteria making them acceptable as inflammatory leucocyte chemotactic factors, has been separated. Among them, our laboratory has isolated three macrophage (monocyte) chemotactic factors (MCF-a, -b and -c). Their purification, characterization and functional specificity are discussed.     

Evaluation of biohydrogenation rate of canola vs. soya bean seeds as unsaturated fatty acids sources for ruminants in situ

An experiment was conducted to study disappearance of C14 to C18 fatty acids, lag times and biohydrogenation (BH) rates of C18 fatty acids of ground soya bean and canola seeds in situ. Three ruminally fistulated Dallagh sheep were used to determine ruminal BH of unsaturated fatty acids (UFAs). Differences in the disappearance of fatty acids through the bags and lag times were observed between the oilseeds. We saw that the longer the incubation time of the oilseeds in the rumen, the lower the content of C18:2 and C18:3. Significantly higher lag times for both C18:2 and C18:3 were observed in ground canola compared to ground soya bean. BH rates of C18:2 and C18:3 fatty acids in soya bean were three times higher than those of canola. These results suggest that the fatty acid profile of fat source can affect the BH of UFAs by rumen micro‐organisms. So that UFAs of canola had higher ability to escape from ruminal BH. It seems that fatty acid profile of ruminant products is more affected by canola seed compared to soya bean seed.     

Serum biochemical values and mineral element contents of tissues in yaks

Serum biochemical values and the wet weight to dry weight ratios of tissues were determined in yaks in Shandan county of Gansu province. The liver, kidney, heart and muscle contents of seven elements in yaks were also analysed. Most serum biochemical values were similar to those of cattle, camels and sheep, but the calcium concentration was considerably above the normal range for other ruminants. The liver contained the highest concentrations of copper, manganese and cobalt and the kidney of selenium, iron and calcium.Abbreviations Alb albumin - ALT alanine aminotransferase - AST aspartate aminotransferase - BUN blood urea nitrogen - Chol cholesterol - Glob globulin - -GT -glutamyl transpeptidase - IP inorganic phosphorus - TP total protein