镉致大鼠大脑皮质神经细胞凋亡的机理及N-乙酰半胱氨酸的保护作用

对神经细胞用不同浓度(0、5、10、20 μmol/L)醋酸镉染毒和N-乙酰半胱氨酸(NAC)(100μmol/L)进行保护,通过流式细胞仪检测了细胞凋亡率、[Ca2+]i和活性氧(ROS)水平.结果表明,与对照组相比,各染毒组细胞凋亡率、细胞内[Ca2+]i和ROS水平明显升高,呈剂量-效应关系,除5 μmol/L组ROS水平外,均差异极显著(P<0.01).添加NAC组与相应染毒组比较,神经细胞凋亡率有降低趋势,但差异不显著(P>0.05);10、20μmol/L组细胞内[Ca2+]i和ROS水平显著降低(P<0.05或P<0.01).表明镉可诱导神经细胞凋亡,其机理可能与细胞内Ca2+和ROS水平升高有关,NAC对其有一定的保护作用.     

MAPK信号通路在镉致大鼠肝细胞凋亡中的作用

探讨MAPK通路在镉诱导大鼠肝细胞凋亡中的作用.采用两步灌流法获得大鼠肝细胞,经过24 h培养,用醋酸镉、醋酸镉与MAPK抑制剂(p38抑制剂SB202190、JNK抑制剂SP600125、ERK抑制剂U0126)共同处理肝细胞.用MTT法检测细胞存活率,倒置显微镜和荧光显微镜观察细胞形态和凋亡,免疫组织化学法检测p38蛋白表达.结果表明,镉可极显著提高肝细胞磷酸化p38的表达量(P＜0).01),而SB202190能极显著降低其表达(P＜0.01).SB202190可以显著或极显著提高镉处理组细胞的存活率(P＜0.05或P＜0.01),减少变形细胞和凋亡细胞数量,但SP600125和U0126作用相反.说明镉暴露导致肝细胞p38 MAPK途径激活而引起细胞凋亡.     

乐果引起大鼠肝细胞凋亡的机理

通过给大鼠肝细胞培养液中加入乐果(0、3、10、30、100、300μmol/L),染毒122、4 h后,Annexin V/PI双染法检测肝细胞凋亡率;分别用Fluo-2/AM、双氢-乙酰乙酸二氯荧光黄(DCFH-DA)和罗丹名123检测细胞内Ca2+浓度、活性氧(ROS)和线粒体膜电位(Δψm)变化,并在扫描电镜和荧光显微镜下观察凋亡细胞情况,探讨乐果对大鼠肝细胞凋亡的影响。结果显示,肝细胞染毒12、24 h后,出现了明显的细胞凋亡的形态学变化,细胞凋亡率明显升高,除3μmol/L组外,与对照组相比差异显著(P0.05或P0.01),且呈时间-剂量效应。3μmol/L组细胞内Ca2+浓度极显著高于对照组(P0.01),之后随染毒剂量的增加,细胞内Ca2+浓度逐渐下降;细胞内ROS水平在3~100μmol/L随染毒剂量的增大和染毒时间的延长而升高,而在300μmol/L组略有下降,除3μmol/L组外,与对照组相比均差异极显著(P0.01);Δψm除24 h 300μmol/L组外均出现持续下降。结果表明,低剂量乐果染毒可诱导肝细胞发生凋亡,细胞内Ca2+、ROS和Δψm可能参与了这一过程。     

乐果诱导大鼠肝胞凋亡的分析

为研究乐果对大鼠肝细胞凋亡的影响,将24只SD大鼠分成对照组和3个染毒组,分别按体质量以0、1、6和30 mg·kg-1的剂量灌服乐果,连续灌服30 d后,观察肝脏组织学和超微结构变化.同时,通过给大鼠肝细胞培养液中加入乐果(染毒终浓度分别为0、3、10、30、100和300 μmol·L-1),染毒12、24 h后,Annexin V/PI双染法检测肝细胞凋亡率;分别用Fluo-2/AM、双氢-乙酰乙酸二氯荧光黄(DCFH-DA)和罗丹明123检测细胞内Ca2+浓度、活性氧(ROS)和线粒体膜电位(△ψm)变化.结果表明,组织学和超微结构检查显示肝细胞脂肪变性、凋亡等.肝细胞染毒12和24 h后,细胞凋亡率明显升高,除3 μmol·L-1组外,与对照组相比差异显著(P<0.05或P<0.01),且呈时间-剂量效应;3μmol·L-1组细胞内Ca2+浓度极显著高于对照组(P<0.01),之后随染毒剂量的增加,细胞内Ca2+浓度逐渐下降;细胞内ROS水平在3～100μmol·L-1范围内随染毒剂量的增大和染毒时间的延长而升高,而在300 μmol·L-1组略有下降,除3μmol·L-1组外,与对照组相比均差异极显著(P<0.01);△ψm除24 h高剂量染毒组(300 μmol·L-1)外均出现持续下降,30～300 μmol·L-1组均小于对照组(P<0.01).本研究表明低剂量乐果染毒可诱导肝细胞发生凋亡,细胞内Ca2+、ROS和△ψm可能参与了这一过程.     

钙稳态失衡在镉诱导大鼠大脑皮质神经细胞凋亡中的作用

用不同浓度醋酸镉（0、5、10、20μmol／L）以及细胞内钙离子螯合剂BAPTA-AM（10μmol／L）单独或联合作用于大鼠大脑皮质神经细胞12h,利用流式细胞仪检测细胞凋亡率、细胞内[Ca2＋];、活性氧（ROS）水平以及线粒体膜电位（△ψm）。结果显示,与对照组相比,各镉染毒组细胞凋亡率、细胞内[Ca2＋]i和ROS水平显著或极显著升高（P〈0．05或P〈0．01）,△ψm显著或极显著降低（P〈0．05或P〈0O．01）。BAPTA-AM联合组与相应镉染毒组相比,细胞凋亡率、细胞内[Ca2＋]i和ROS水平降低,△ψm升高,部分组间差异显著或极显著（P〈0．05或P〈0．01）。结果表明,镉可诱导大脑皮质神经细胞凋亡,细胞内钙稳态失衡在镉诱导大脑皮质神经细胞凋亡中起着重要作用,凋亡机理可能与细胞内钙超栽引起ROS水平升高和△ψm下降有关。     

镉致大鼠肝细胞凋亡及N-乙酰半胱氨酸的保护作用

用两步灌流法获得大鼠肝细胞,应用四甲基偶氮噻唑蓝(MTT)比色法、Hoechst 33258荧光染色法和流式细胞仪检测醋酸镉对肝细胞存活率和凋亡率的影响,以及N-乙酰半胱氨酸(NAC)的保护效应.结果表明,肝细胞暴露于浓度为2.5、5、10μmol/L的醋酸镉后,细胞相对存活率显著下降(P<0.01),凋亡率显著升高(P<0.05),且具有剂量-效应关系;2 mmol/L的NAC可使细胞相对存活率明显提高(P<0.01),凋亡率下降.结果提示,一定浓度醋酸镉可引起肝细胞凋亡,NAC具有一定的保护作用.     

镉对体外培养大鼠大脑皮质神经元钙稳态的影响

选用原代培养大鼠大脑皮质神经元为模型,用神经元特异性烯醇化酶(NSE)抗体经免疫组织化学染色技术鉴定神经元.用不同浓度(0、5、10、20 μmol/L)醋酸镉染毒大鼠大脑皮质神经元12h,利用流式细胞仪检测细胞内[Ca2-]i,ATPase酶试剂盒测定Na-K+ ATPase和Ca2-Mg2--ATPase活性的变化,荧光定量PCR法测定钙调蛋白(CaM) mRNA转录水平.结果表明,免疫组化染色证实培养细胞呈现NSE阳性染色,证明是神经元.与对照组相比,各镉染毒组细胞内[Ca2+]i显著或极显著升高(P＜0.05或P＜0.01),Na--K--ATPase和Ca2+-Mg2+-ATPase活性显著或极显著降低(P＜0.05或P＜0.01),20 μmol/L组CaM mRNA转录水平极显著降低(P＜0.01).说明镉可能通过影响CaM的转录水平与维持钙稳态相关的酶(Na+-K-ATPase和Ca2+-Mg2+-ATPase)活性,干扰神经元细胞内钙稳态,进而造成神经元细胞损伤.     

lncRNA NONRATT021477.2对氧化应激条件下BRL细胞增殖和凋亡的影响

以H₂O₂诱导BRL细胞建立氧化应激型模，通过ROS和MDA试剂盒检测氧化应激的发生状态。过表达和干扰表达lncRNA 77.2后，通过流式细胞术检测细胞凋亡，CCK-8法检测细胞增殖情况。结果显示，过表达lncRNA77.2后，BRL细胞内ROS和MDA含量均极显著下降(P<0.01),细胞增殖能力增强(P<0.01),细胞凋亡率下降(P<0.01);而干扰表达lncRNA77.2后，细胞内ROS显著升高(P<0.05),MDA含量极显著升高(P<0.01),细胞增殖能力下降(P<0.01),细胞凋亡率上升(P<0.01)。结果表明，lncRNA 77.2可作为抗氧化调控因子通过抑制凋亡和氧化损伤对大鼠肝细胞起到一定的保护作用。     

敌百虫对体外培养大鼠大脑皮质神经细胞凋亡的影响

为探讨敌百虫对大鼠大脑皮质神经细胞的毒性作用及机理,本研究在建立体外培养新生24h内SD大鼠大脑皮质神经细胞模型的基础上,在细胞培养液中添加0、5、20、80mg/L敌百虫染毒,在染毒后的不同时间测定细胞凋亡率、线粒体膜电位、细胞内[Ca2＋]i、ROS含量和ATP酶的变化。结果显示：①染毒12h,细胞凋亡率明显增加;②染毒12h,各染毒组线粒体膜电位逐渐降低,其中80mg/L组与对照组存在极显著差异（P〈0.01）;③染毒0.5h,各染毒组细胞内[Ca2＋]i显著高于对照组（P〈0.01）;染毒12h,各染毒组细胞内[Ca2＋]i呈下降趋势,但仍显著或极显著高于对照组（P〈0.05或P〈0.01）;④染毒12h和24h,细胞内ROS水平显著或极显著高于对照组（P〈0.05或P〈0.01）;⑤染毒12h,细胞Na＋-K＋-ATPase和Ca2＋-Mg2＋-ATPase活性逐渐降低,20、80mg/L组与对照组有极显著差异（P〈0.01）;上述指标的变化呈显著的剂量-效应关系。结果表明,低质量浓度敌百虫暴露可致大鼠大脑皮质神经细胞凋亡率和细胞内ROS含量升高,线粒体膜电位下降,细胞内钙离子超载且ATPase活性降低,提示细胞凋亡在敌百虫所致的大脑皮质神经细胞损伤过程中发挥主导作用。     

镉对大鼠原代肝细胞的毒性损伤

用两步灌流法获得大鼠肝细胞,肝细胞暴露于浓度为2.5、5、10μmol/L的醋酸镉24 h.测定了细胞活力、培养上清液中乳酸脱氢酶(LDH)、天冬氨酸转氨酶(AST)和丙氨酸转氨酶(ALT)活性及细胞内谷胱甘肽过氧化物酶(GSH-PX)活性、还原型谷胱甘肽(GSH)和丙二醛(MDA)含量的变化.结果表明,细胞相对存活率显著下降(P<0.01),LDH、AST和ALT的释放量增加,5μmol/L和10 μmol/L剂量组与对照组相比差异均显著(P<0.01),细胞内GSH-PX活性降低,各剂量染毒组与对照组相比,差异均极显著(P<0.01);细胞内GSH含量升高,5 μmol/L和10μmol/L剂量组与对照组差异均显著(P<0.05),细胞内MDA含量升高,10μmol/L剂量组与对照组相比差异显著(P<0.05).表明镉可致肝细胞损伤,并且氧化应激起了重要作用.     

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