H2O2诱导BRL-3A细胞模拟大鼠肝脏氧化应激损伤的研究

动物冷暴露过程中,肝脏因发生氧化应激而受损.利用不同浓度过氧化氢(H2O2)作用BRL-3A细胞,根据细胞存活率确定500 μmol/L H2O2作用细胞3h为施加条件,然后通过检测蛋白质羰基含量、超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-Px)和过氧化氢酶(CAT)活性,探讨在细胞水平上建立冷暴露大鼠肝脏损伤模型.结果显示,H2O2处理组细胞存活率下降,蛋白质羰基含量升高,SOD、GSH-Px和CAT活性均降低.与对照组相比,其存活率、细胞内蛋白质羰基含量和CAT活性,均差异极显著(P＜0.01),细胞内SOD和GSH-Px活性,差异显著(P＜0.05).结果表明,500 μmol/L H2O2作用于BRL-3A细胞可导致氧化应激的发生,其相关指标与大鼠冷暴露后肝脏受损指标改变趋势类似,利用BRL-3A细胞建立冷暴露引起的肝脏氧化损伤模型,为进一步探讨冷应激对肝脏损伤的机制奠定基础.     

线粒体凋亡通路在皮质酮(CORT)诱导海马神经元凋亡中的作用

为在细胞水平探讨皮质酮(CORT)诱导HT22细胞凋亡的机制,以模拟冷应激过程中机体分泌的糖皮质激素对海马神经元的作用。试验组HT22细胞用500μmol/L CORT处理3 h,对照组不予处理。用CCK8法检测CORT对HT22细胞活力的影响,Annexin/PI流式细胞术检测细胞凋亡率。为了进一步研究CORT引起的海马神经元凋亡是否是由线粒体凋亡通路介导的,用JC-1探针检测线粒体膜电位的变化,免疫蛋白印迹(Western blot)检测凋亡相关蛋白细胞色素c(Cyt-c)、Bcl-2、Bax、Caspase-3的表达。结果显示,与对照组相比,500μmol/L CORT处理组细胞生存率显著降低,细胞凋亡率显著升高,线粒体膜电位显著下降,Cyt-c、Bax/Bcl-2及活化的Caspase-3表达水平显著升高。结果表明,500μmol/L CORT处理3 h会导致HT22细胞凋亡,并且线粒体凋亡通路在该过程中发挥重要作用。     

白藜芦醇通过沉默调节蛋白1-解偶联蛋白2信号通路降低小鼠睾丸间质细胞TM3的氧化损伤

本试验旨在研究白藜芦醇(RES)对氧化损伤小鼠睾丸间质细胞TM3的保护作用,并探索其可能的作用机制。首先,用不同浓度(0、150、200、250、300μmol/L)的过氧化氢(H2O2)处理小鼠睾丸间质细胞TM3 8 h,确定建立氧化损伤细胞模型的适宜H2O2浓度;然后,用不同浓度(0、2.5、5.0和10.0μmol/L)的RES分别处理正常细胞24 h,确定RES安全浓度;最后,用安全浓度的RES处理氧化损伤细胞24 h。在整个培养过程中采用i CELLigence实时无标记细胞功能分析仪监测细胞的增殖情况;待安全浓度的RES处理氧化损伤细胞结束后采用2',7'-二氯荧光素二乙酸酯(DCFH-DA)探针法检测细胞中活性氧(ROS)的含量,实时荧光定量PCR(RT-q PCR)和蛋白质印迹(Western blotting)法分别检测沉默调节蛋白1(SIRT1)/解偶联蛋白2(UCP2)信号通路中关键因子SIRT1和UCP2 mRNA和蛋白质的相对表达量。结果表明:1)用浓度为150μmol/L及以上的H2O2处理细胞8 h后,极显著降低细胞存活率(P0.01),因此确定150μmol/L为建立氧化损伤细胞模型的适宜H2O2浓度。2)用10.0μmol/L及以下浓度的RES处理正常细胞24 h后,细胞存活率均无显著变化(P0.05);用2.5、5.0和10.0μmol/L的RES处理氧化损伤细胞24 h后,细胞存活率均显著提高(P0.05),且各浓度RES组间无显著差异(P0.05)。因此,选用5.0μmol/L为RES的安全浓度。3)用5.0μmol/L的RES处理氧化损伤细胞24 h后,细胞中ROS的含量极显著降低(P0.01);细胞中SIRT1 mRNA和蛋白质的相对表达量极显著增加(P0.01),而UCP2 mRNA和蛋白质的相对表达量则显著或极显著降低(P0.01或P0.05)。由此可见,适宜浓度的RES可激活SIRT1同时抑制UCP2的表达,UCP2通过负反馈调节方式减少细胞内ROS的生成,从而在一定程度上抑制TM 3细胞的氧化损伤。     

PERK在玉米赤霉烯酮诱导TM4细胞凋亡中的作用

以TM4细胞(小鼠睾丸支持细胞株)为材料,用不同浓度的玉米赤酶烯酮(zearalenone,ZEA)染毒,利用透射电子显微镜(设0,5,10,20μmol/L ZEA浓度组),流式细胞仪、Western blot等技术检测了细胞超微结构、凋亡率、凋亡相关调控蛋白以及内质网应激相关蛋白的变化(设0,0.1,1,10,20μmol/L ZEA浓度组);通过转染PERK(蛋白激酶R样内质网激酶)siRNA,沉默PERK基因后检测了ZEA诱导TM4细胞凋亡率和凋亡相关蛋白的变化。结果显示:与对照组相比,20μmol/L浓度组损伤最为严重。随着ZEA浓度的增加,细胞凋亡相关蛋白Bax/Bcl-2的值逐渐升高,cleaved caspase 9、cleaved caspase 3蛋白表达量均呈升高趋势,1μmol/L以上染毒组均较各自对照组有极显著差异(P0.01);内质网应激相关蛋白BIP、CHOP的表达量也呈升高趋势,10μmol/L以上染毒组BIP、0.1μmol/L以上染毒组CHOP的表达量均较对照组有显著或极显著差异(P0.05或P0.01);PERK通路蛋白含量在10μmol/L时最高,20,30μmol/L时逐渐降低,但各染毒组与对照组相比呈显著或极显著差异(P0.05或P0.01);TM4细胞caspase3的活性和凋亡率均呈升高趋势,10μmol/L以上染毒组caspase3的活性较对照组均有极显著差异(P0.01),各染毒组细胞的凋亡率较对照组均有极显著差异(P0.01)。与10μmol/L ZEA处理组相比,siRNA PERK+10μmol/L ZEA组细胞凋亡率呈显著下降(P0.01),Bax/Bcl-2比值、cleaved caspase 3、cleaved caspase 9表达量均下降(P0.05或P0.01)。结果表明,ZEA可触发TM4细胞内质网应激,通过PERK-eLF2α-ATF4信号通路诱导细胞发生凋亡,PERK信号通路在ZEA诱导TM4细胞凋亡中发挥重要作用。     

小鼠胚胎DNA氧化损伤模型的建立

为了研究胚胎DNA损伤修复机制,试验以H2O2为DNA损伤诱导剂,建立小鼠胚胎DNA氧化损伤模型,采用不同浓度H2O2培养小鼠受精卵,观察其对小鼠胚胎发育能力的影响;再通过免疫荧光方法检测γH2AX和ρATM蛋白的表达状况,以判断H2O2处理所导致的胚胎DNA损伤情况及较适宜的诱导条件。结果表明:1.5~2.4μmol/L H2O2处理对小鼠胚胎发育能力具有影响,与KOSM(-)对照组相比,H2O2处理组小鼠胚胎的分裂率、囊胚率呈下降趋势,其中1.8~2.4μmol/L H2O2处理组的胚胎分裂率、囊胚率呈显著下降趋势(P0.05)。免疫荧光法检测发现KOSM(-)对照组中,2-细胞期胚胎的γH2AX焦点数多于1-细胞期胚胎,ρATM在两个时期的胚胎中未检测到。γH2AX和ρATM在1.5,1.8μmol/L H2O2处理组的1-细胞期胚胎中均未检测到;2-细胞期胚胎表达γH2AX,未检测到ρATM。2.1,2.4μmol/L H2O2处理组的1-细胞和2-细胞期胚胎均有γH2AX和ρATM表达,其中2.4μmol/L H2O2处理组两个时期胚胎的γH2AX焦点数多于2.1μmol/L H2O2处理组。说明1.5~2.4μmol/L H2O2处理会影响小鼠胚胎体外发育能力,2.1,2.4μmol/L H2O2处理可诱导小鼠胚胎发生DNA双链断裂现象。     

谷氨酰胺及其二肽对过氧化氢诱导山羊瘤胃上皮细胞凋亡及凋亡相关基因表达的影响

本试验通过建立过氧化氢(H2O2)诱导山羊瘤胃上皮传代细胞凋亡模型,研究谷氨酰胺(Gln)、甘氨酰谷氨酰胺(Gly-Gln)和丙氨酰谷氨酰胺(Ala-Gln)对凋亡细胞的凋亡率及Bcl-2、Bax基因表达量的影响。选用60日龄湘东黑山羊的瘤胃上皮传代细胞,采用不同浓度[0(对照组)、100、400、800μmol/L]的H2O2培养细胞,应用流式细胞术检测细胞凋亡情况。传代瘤胃上皮细胞分为5组,对照组和1组分别添加0、800μmol/L H2O2,2组、3组、4组均添加800μmol/L H2O2,同时分别添加17.28 mmol/L Gly-Gln(2组)、16.0 mmol/L Gln(3组)、16.0 mmol/L AlaGln(4组),应用流式细胞术检测细胞凋亡情况,同时采用实时荧光定量PCR(FQ-PCR)法检测细胞Bcl-2、Bax基因表达量。结果显示:1)与对照组相比,当H2O2浓度增加到800μmol/L时,早期凋亡的凋亡率显著增加(P0.05),而晚期凋亡的凋亡率随着H2O2浓度的增加呈现增加后减少的趋势,但相对于对照组,都呈显著增加(P0.05)。2)与对照组相比,4组晚期凋亡的凋亡率显著增加(P0.05),试验组早期凋亡的凋亡率均显著增加(P0.05)。3)与对照组相比,试验组Bcl-2/Bax均显著增加(P0.05);与1组相比,2组、3组和4组Bcl-2/Bax均显著增加(P0.05),且2组显著高于3组、4组(P0.05)。综合得出,Gly-Gln对H2O2引起山羊瘤胃上皮细胞早期凋亡具有一定的保护作用。     

L-茶氨酸对过氧化氢诱导山羊瘤胃上皮传代细胞凋亡的影响

本试验通过建立过氧化氢(H_2O_2)诱导山羊瘤胃上皮传代细胞凋亡模型,研究L-茶氨酸对H_2O_2诱导山羊瘤胃上皮传代细胞凋亡比率及其凋亡通路关键基因表达量的影响。选取42日龄湘东黑山羊的瘤胃上皮传代细胞,培养于含5%胎牛血清(FBS)的DMEM/F12培养基中,待细胞密度达到60%~70%时,随机分为5组,分别为培养基中无额外添加物的对照组、添加800μmol/L H_2O_2的Ⅰ组、添加800μmol/L H_2O_2+4 mmol/L L-茶氨酸的Ⅱ组、添加800μmol/L H_2O_2+8 mmol/L L-茶氨酸的Ⅲ组和添加800μmol/L H_2O_2+16 mmol/L L-茶氨酸的Ⅳ组,每组3个重复。作用12 h后,应用流式细胞术(FCM)检测山羊瘤胃上皮传代细胞凋亡比率,并采用实时荧光定量PCR(RT-q PCR)对山羊瘤胃上皮传代细胞凋亡通路关键基因半胱氨酸天冬氨酸-3(Caspase-3)、半胱氨酸天冬氨酸-8(Caspase-8)、半胱氨酸天冬氨酸-9(Caspase-9)、Fas相关死亡域蛋白(FADD)和凋亡酶激活因子(Apaf-1)的表达量进行检测。结果显示:1)通过膜联蛋白-V(annexin V)/碘化丙啶(PI)联合染色结果可知,与Ⅰ组相比,各L-茶氨酸添加组(Ⅱ、Ⅲ和Ⅳ组)细胞晚期凋亡比率显著降低(P0.05),且细胞晚期凋亡比率随L-茶氨酸添加浓度的增加逐渐降低。2)通过RT-q PCR检测结果可知,与Ⅰ组相比,各L-茶氨酸添加组Caspase-3、Caspase-9、Apaf-1基因的表达量皆显著降低(P0.05)。由此得出,L-茶氨酸对H_2O_2引起的山羊瘤胃上皮传代细胞凋亡具有一定的保护作用,该结果可为今后研究反刍家畜瘤胃氧化应激损伤机制提供技术支持和理论参考。     

线粒体凋亡途径在玉米赤霉烯酮致大鼠睾丸支持细胞凋亡中的作用

为探讨玉米赤霉烯酮(zearalenon,ZEA)雄性生殖毒性作用机理,研究ZEA诱导大鼠睾丸支持细胞(sertoli cell,SC)的凋亡途径,试验选取大鼠原代SC为研究材料,用不同浓度ZEA(0、5、10、20μmol/L)处理SC 24 h后,采用实时荧光定量PCR法检测Bax和Bcl-2 mRNA表达水平;用Western blotting法检测Bax、Bcl-2等线粒体凋亡途径相关蛋白表达;同时检测了20μmol/L ZEA联合Caspase-8抑制剂(Z-IETD-FMK)处理对SC凋亡率和线粒体凋亡相关蛋白的影响。结果显示,与对照组相比,20μmol/L ZEA组细胞Bcl-2转录水平显著下降(P0.05),Bax转录水平显著上升(P0.05);10、20μmol/L ZEA组Bax/Bcl-2比值及Cyto-CytC、Cleaved Caspase-9、Cleaved Caspase-3表达量极显著上升(P0.01),而Mito-CytC表达量极显著下降(P0.01);与ZEA组相比,ZEA与Z-IETD-FMK联合处理可使ZEA诱导的SC凋亡率极显著下降(P0.01),tBid/Bid、Bax/Bcl-2、Cyto-CytC、Cleaved-Caspase3、Cleaved-Caspase9蛋白表达显著或极显著下降(P0.05;P0.01),而Mito-CytC表达量极显著上升(P0.01)。综合试验结果,ZEA能够通过线粒体途径诱导大鼠SC发生凋亡。     

线粒体凋亡途径在玉米赤霉烯酮致大鼠睾丸支持细胞凋亡中的作用

为探讨玉米赤霉烯酮(zearalenon,ZEA)雄性生殖毒性作用机理,研究ZEA诱导大鼠睾丸支持细胞(sertoli cell,SC)的凋亡途径,试验选取大鼠原代SC为研究材料,用不同浓度ZEA(0、5、10、20μmol/L)处理SC 24 h后,采用实时荧光定量PCR法检测Bax和Bcl-2 mRNA表达水平;用Western blotting法检测Bax、Bcl-2等线粒体凋亡途径相关蛋白表达;同时检测了20μmol/L ZEA联合Caspase-8抑制剂(Z-IETD-FMK)处理对SC凋亡率和线粒体凋亡相关蛋白的影响。结果显示,与对照组相比,20μmol/L ZEA组细胞Bcl-2转录水平显著下降(P<0.05),Bax转录水平显著上升(P<0.05);10、20μmol/L ZEA组Bax/Bcl-2比值及Cyto-CytC、Cleaved Caspase-9、Cleaved Caspase-3表达量极显著上升(P<0.01),而Mito-CytC表达量极显著下降(P<0.01);与ZEA组相比,ZEA与Z-IETD-FMK联合处理可使ZEA诱导的SC凋亡率极显著下降(P<0.01),tBid/Bid、Bax/Bcl-2、Cyto-CytC、Cleaved-Caspase3、Cleaved-Caspase9蛋白表达显著或极显著下降(P<0.05;P<0.01),而Mito-CytC表达量极显著上升(P<0.01)。综合试验结果,ZEA能够通过线粒体途径诱导大鼠SC发生凋亡。     

过氧化氢诱导的奶牛乳腺上皮细胞氧化损伤模型的建立

本试验旨在利用过氧化氢(hydrogen peroxide,H2O2)作为刺激源,以细胞存活率及抗氧化指标为判断指标,建立奶牛乳腺上皮细胞(bovine mammary epithelial cells,BMEC)的氧化损伤模型。试验一采用单因子完全随机试验设计,将第3代贴壁生长的BMEC随机分为42组,每组10个重复。细胞培养液中分别添加0、100、200、400、600、800和1 000μmol/L H2O2,使之分别作用2、4、6、8、12、24 h,测定细胞数量,计算存活率。试验二是在试验一得出的适宜H2O2作用时间(本试验的结果为6 h)的基础上,采用单因子完全随机试验设计,将第3代贴壁生长的BMEC随机分为7组,每组6个重复,BMEC中添加不同浓度的H2O2(0、100、200、400、600、800和1 000μmol/L)作用细胞6 h,收集细胞和培养液测定抗氧化指标,筛选使细胞发生氧化损伤的适宜H2O2作用浓度。试验一结果表明,600μmol/L H2O2作用细胞6 h,BMEC的存活率降低至79.79%。试验二结果表明,600~1 000μmol/L组与其他各组相比均显著降低了谷胱甘肽过氧化物酶、超氧化物歧化酶和过氧化氢酶活性,提高了丙二醛含量(P<0.05),但600、800和1 000μmol/L组之间差异不显著(P>0.10)。结果 提示,H2O2作用浓度为600μmol/L、作用时间为6 h,使BMEC产生了明显的氧化应激,可作为建立细胞氧化损伤模型时的适宜条件。     

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.     

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.     

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.     

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