维拉帕米对低温诱发腹水综合征肉鸡右心功能的影响

本试验旨在探讨钙离子内流阻滞剂维拉帕米（verapamile）对腹水综合征肉鸡右心功能的影响。结果显示，维拉帕米使低温诱发的肉鸡腹水症发生率以及肉鸡腹水心脏指数降低。与低温对照组相比，维拉帕米组28日龄鸡右心室收缩压显著降低（P〈0．05），36、44日龄鸡右心室收缩压有所降低（P〉0．05），而28和36日龄鸡右心室舒张压显著降低（P〈0．01）。     

2种组胺受体拮抗剂对低温诱发的肉鸡肺动脉高压的影响

为探讨组胺H1受体拮抗剂扑尔敏和H2受体拮抗剂西咪替丁对低温诱发的肉鸡肺动脉高压的影响,并由此推测组胺在低温诱发的肉鸡肺动脉高压形成过程中的作用。140只17日龄AA肉鸡随机分为4组。(1)常温组:40只在常温条件下饲养(22～23℃),每日注射生理盐水2次;(2)低温组:40只在低温环境中饲养(9～11℃),每日注射生理盐水2次;(3)扑尔敏组:40只在低温环境中饲养(9～11℃),每日注射扑尔敏2次;(4)西咪替丁组:20只在低温环境中饲养(9～11℃),于24日龄至38日龄期间每日注射西咪替丁2次。分别于低温处理后1周(24日龄)、2周(31日龄)、3周(38日龄)、4周(45日龄)从常温组,低温组,扑尔敏组中各随机抽取10只,西咪替丁组在低温处理后2周(31日龄)、3周(38日龄)各随机抽取10只,称取体重,然后利用右心导管法测定肺动脉压(PAP),并测定红细胞压积(PCV),腹水心脏指数(AHI)。结果发现:(1)24日龄、31日龄、38日龄时,低温组肺动脉收缩压,舒张压显著高于(P<0105)或极显著高于(P<0101)同日龄常温组。24日龄时扑尔敏组肺动脉收缩压显著低于(P<0105)同日龄低温组。38日龄时西咪替丁组肺动脉收缩压,舒张压极显著低于(P<0101)同日龄低温组。(2)24日龄、31日龄、38日龄、45日龄时,低温组PCV极显著高于(P<0101)同日龄常温组。24日龄时扑尔敏组     

维拉帕米对肺动脉高压综合征肉鸡心、肺组织中肥大细胞的影响

为了探索肥大细胞（MC）钙信号系统在肉鸡肺动脉高压综合征（PHS）形成中的作用,采用低温诱发肉鸡PHS,给予钙通道阻断剂（维拉帕米）后,右心导管法测定肉鸡血流动力学,常规阿尔新蓝法显示MC,免疫组化方法显示组胺,利用焦锑酸钾组化电镜技术,观察肺组织MC脱颗粒时胞浆钙沉积现象。结果：（1）维拉帕米组肉鸡肺动脉收缩压和舒张压显著低于低温组;（2）维拉帕米维持右心舒缩功能相对正常,抑制右心肥大;（3）维拉帕米组肺血管壁MC数显著（P〈0.05）高于低温组,心脏MC数极显著（P〈0.01）高于低温组,31和38日龄维拉帕米组肺呼吸毛细管和肺小动脉血管壁MC脱颗粒率也显著（P〈0.05）低于低温组;（4）维拉帕米组肺呼吸毛细管组胺阳性细胞数显著（P〈0.05）高于低温组,血管壁组胺阳性细胞数亦显著（P〈0.05）高于低温组;（5）肺动脉高压综合征肉鸡的脱颗粒MC胞浆中可见Ca^2＋颗粒沉积,出现Ca^2＋超载现象。研究表明钙信号参与PHS肉鸡MC的激活,维拉帕米稳定肺和心脏中的MC,防止MC脱颗粒,抑制组胺的释放,同时降低了肺动脉压,这可能是维拉帕米抑制PHS形成的重要机制之一。     

37℃热应激对实验性大肠杆菌病肉鸡肺动脉压和右心功能的影响

160只商品代AA肉仔鸡于29日龄时随机均分为常温对照组、热应激对照组、常温感染组和热应激感染组．研究了37℃热应激对实验性感染大肠杆菌肉鸡肺动脉压和右心功能的影响。结果37℃热应激1～3d极显著降低（P〈0．01）肉鸡感染大肠杆菌引起的肺动脉高压，肺动脉收缩压、舒张压和平均肺动脉压分别下降了34．78％、45．83％、40．48％。热应激3、7d，感染大肠杆菌肉鸡右心室收缩压显著下降（P〈0．05，P〈0．01），分别下降了26．60％、28．00％，右心室收缩和舒张压最大变化速率显著下降（P〈0．05），分别下降了77．50％，50．77％和75．00％、50．58％。结果表明，37℃热应激可以拮抗肉鸡感染大肠杆菌引起的肺动脉高压，降低感染肉鸡死亡率，但使右心功能下降。     

日粮中添加L—NAME对肉鸡腹水综合征发生的影响及其机理

应用低温环境和日粮中添加三碘甲腺原氨酸（3，3，5－triiodothyronine,T3)诱发肉鸡腹水综合征，同时通过日粮添加一氧化氮合酶抑制剂L－NAME，研究了抑制NO的合成对肉鸡肺动脉压及肉鸡腹水综合征发生的影响。180羽AA肉鸡随机等分为对照组（C）、试验组（A、B），参试鸡14日前按常规条件饲养。14日龄后C组鸡按常规条件饲养，A、B组鸡舍温按每日1－2℃逐步降至12℃，同时日粮中添加T3 1．5mg/kg以诱发腹水综合征。另外，B组肉鸡从14日龄起在日粮中添加100mg/kgL－NAME至试验结束。分别于3、4、5、6周龄测定各组肉鸡肺动脉平均压（mean pulmonary arterial pressure,mPAP)、红细胞压积、右心全心比、血浆一氧化氮（NO）和内皮素（endothelin-1,ET-1)水平并记录腹水综合征发病率。结果显示：低温添加T3处理后，A、B组肉鸡腹水综合征发病率增加，但B组高于A组；A、B组肉鸡mPAP从5周龄起高于C组（P＜0．05）；A、B组右心全心比的升高分别在6、5周龄时出现，B组右心全心比的升高比A组提前1周；B组 肉鸡血浆NO水平低于A组，差异不显著；A、B组肉鸡血浆ET－1水平高于C组（P＜0．05）；在6周龄时，A组肉鸡心率明显降低，B组肉鸡心率明显升高。随着肺动脉高压和右心肥大的出现，心率的升高可能促进了右心衰竭和肉鸡腹水综合征的发生。上述结果提示，抑制NO的合成可能促进了肉鸡肺动脉高压，右心肥大的形成和肉鸡腹水综合征的发生。     

卡托普利对腹水综合征肉鸡右心功能的影响

150只15日龄AA肉鸡随机分为常温组、低温组和卡托普利组,探讨卡托普利对腹水综合征肉鸡右心功能的影响。结果:卡托普利降低低温诱发肉鸡腹水的发生率;卡托普利降低低温诱发肉鸡肺动脉高压;卡托普利与低温组比降低肉鸡腹水心脏指数;28、36日龄和44日龄,卡托普利组右心室收缩压低于低温组(P0.05);28、36日龄和44日龄,卡托普利组右心室舒张压分别极低于低温组((P0.01)。本试验证明卡托普利可以降低腹水发生率和右心肥大,有效维护右心功能。     

维拉帕米对低温诱发腹水综合征病鸡右心功能的影响

300只15日龄商品肉仔鸡随机分为常温组、低温组和维拉帕米组，以研究L型电压依赖性钙通道拮抗剂维拉帕米对腹水综合征病鸡右心功能的影响。结果，与低温组相比，维拉帕米可显著降低肉鸡腹水综合征的发生率；维拉帕米组肉鸡腹水心脏指数分别在29、36、43和50日龄时显著或极显著降低；右心室收缩压在36和43日龄时极显著降低，右心室舒张压在36和43日龄时也显著或极显著下降；右心室内压最大变化速率在43日龄时极显著升高。结果表明，维拉帕米可显著降低肉鸡腹水和右心肥大的发生，能有效维护右心功能。     

静脉注射L-氨基胍对肉鸡肺动脉压及其相关指标的影响

按常规饲养条件饲养AA雄性肉鸡120羽，30日龄时随机分为试验组（T组）和对照组（C组）。T组肉鸡静脉注射L-AG（40mg／kg），C组肉鸡静脉注射生理盐水。分别在注射L-AG和生理盐水1、2、4h后测定平均肺动脉压（mPAP）、诱导型一氧化氮合酶（iNOS）活性、原生型一氧化氮舍酶（cNOS）活性、一氧化氮（NO）含量、红细胞压积（PCV）、电解质浓度、pH、超氧化物歧化酶（SOD）活性、过氧化氢酶（CAT）活性和丙二醛（MDA）含量。结果显示：（1）试验组mPAP、NO含量和iNOS活性均显著或极显著低于对照组（P〈0．05或P〈0．01）；（2）PCV和Ca^2＋在给药后2h和4h与对照组差异显著（P〈0．05）；（3）K^＋浓度在给药1h和2h后显著或极显著低于时照组（P〈0．05或P〈0．01）。结果表明，L-AG通过抑制iNOS活性，引起肉鸡肺动脉压的升高，从而推测iNOS具有调节肉鸡体内mPAP的作用并与肉鸡肺动脉高压综合征发生有着密切的联系。     

肺动脉高压综合征发病过程中肉鸡血清和肺脏iNOS和cNOS活性变化

常规饲养条件喂养的大群AA肉鸡，按临床症状分为肺动脉高压组（M组），肺动脉高压腹水组（S组）和正常对照组（C组）。分别测定21、28、35和42日龄S组、M组和C组肉鸡的腹水心脏指数（AHI）、全心与体重比（WH／BW）、平均肺动脉高压（mPAP）、血清一氧化氮（NO）水平、肺脏和血清cNOS和iNOS活性。试验结果表明：（1）S组和M组全心与体重比值（TV／BW）以及S组血清NO水平均从28日龄起显著或极显著高于C组（P〈O．01或P〈0．05）；（2）S组肺组织cNOS水平显著或极显著低于C组（P〈0．01或P〈0．05）；（3）S组肺组织iNOS在21、35和42日龄显著或极显著高于C组（P〈0．01或P〈0．05）；（4）S组从28日龄起血清中cNOS和iNOS与C组差异显著或极显著（P〈0．01或P〈0．05）；（5）正常对照组肉鸡血清中iNOS活性在21、35和42日龄均显著或极显著低于血清中cNOS活性（P〈0．01或P〈0．05）。此研究结果提示cNOS和iNOS活性的变化与PHS发病机理有着密切的关系，并在其中发挥着重要的作用。     

两种组胺受体拮抗剂对内毒素诱导雏鸡肺损伤的影响

为探讨2种组胺受体拮抗剂在内毒素诱导肺损伤中的作用机理,作者设计了本试验。将120羽20日龄雏鸡随机分为5组,每组24羽。内毒素诱导肺损伤模型组每天早晚注射生理盐水0.5 mL.只^-1,中午腹腔注射内毒素100μg.kg^-1;扑尔敏组每天早晚肌注扑尔敏0.5 mL.只^-1,中午腹腔注射内毒素100μg.kg^-1;西咪替丁组每天早晚肌注西咪替丁0.5 mL.只^-1,中午腹腔注射内毒素100μg.kg^-1;扑西联合组每天早晚肌注西咪替丁、扑尔敏各0.3 mL.只^-1,中午腹腔注射内毒素100μg.kg^-1;空白组每天早中晚注射同等剂量生理盐水,连续15d。在第5、10、15天,各组随机抽7个样本,颈动脉放血处死,称取肺质量,采集肺脏以荧光法测组胺含量,制备病理切片观察病理变化并评分。结果发现：（1）第5天,扑西联合组肺组织中组胺含量显著低于扑尔敏组和西咪替丁组（P〈0.05）。在第10天时,模型组肺组织中组胺含量显著高于扑西联合组和空白组（P〈0.05）;在第15天时,模型组肺组织中组胺含量显著（P〈0.05）高于扑尔敏组和空白组,极显著（P〈0.01）高于扑西联合组;（2）第10天时,扑尔敏组和空白组肺指数显著（P〈0.05）或极显著（P〈0.01）低于模型组,第15天时,扑尔敏组、扑西联合组和空白组肺指数显著（P〈0.05）低于模型组;（3）第5、10、15天时,模型组肺病理评分分值与其余各试验组差异极显著（P〈0.01）,在第5天时,扑西联合组极显著低于扑尔敏组和西咪替丁组（P〈0.01）,在第10、15天时,扑西联合组显著低于（P〈0.05）扑尔敏组,极显著低于其它各组（P〈0.01）。结果表明,组胺通过H1、H2受体参与介导内毒素诱导雏鸡肺的损伤,但H1受体起主导作用。     

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.     

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