鸡源致病性大肠杆菌对鸡胚气管上皮细胞的粘着作用

采用透射电镜和扫描电镜观察了鸡源大肠杆菌在改良马丁肉汤、营养肉汤、麦康凯琼脂和普通营养琼脂培养基上生长时菌毛的表达以及致病性大肠杆菌对培养的鸡胚气管上皮细胞的粘着。大肠杆菌Ｏ７８、Ｏ３６、Ｏ４９在改良马丁肉汤和麦原凯琼脂上经３７℃７２小时培养后菌毛生长良好，能够牢固地粘着在鸡胚气管上皮细胞绒毛上。     

鸡源致病性大肠杆菌对鸡胚气管上皮细胞的粘着作用

采用透射电镜和扫描电镜观察了鸡源大肠杆菌在改良马丁肉汤、营养肉汤、麦康凯琼脂和普通营养琼脂培养基上生长时菌毛的表达以及致病性大肠杆菌对培养的鸡胚气管上皮细胞的粘着。大肠杆菌Ｏ７８、Ｏ３６、Ｏ４９在改良马丁肉汤和麦康凯琼脂上经３７℃７２小时培养后菌毛生长良好，能够牢固地粘着在鸡胚气管上皮细胞绒毛上。     

禽大肠杆菌内毒素对蛋鸡致病作用的病理学研究

将鸡源致病性大肠杆菌悬液反复冻融，提取粗制细菌内毒素．以静脉注射和腹腔注射途径接种于产蛋鸡。结果证明，鸡大肠杆菌内毒素可引起产蛋鸡急性死亡，病理变化以出血性坏死和弥散性血管内凝血为特征．     

禽大肠杆菌内毒素对蛋鸡致病作用的病理学研究

将鸡源致病性大肠杆菌悬液反复冻融，提取粗制细菌内毒素，以静脉注射和腥腔注射途径接种于产蛋鸡，结果证明，鸡大肠杆菌内毒素可引起产蛋鸡急性死亡，病理变化以出血性坏死和弥散性血管内凝血为特征。     

鸡源大肠埃希氏菌某些生物学特性

对鸡源大肠埃希氏菌的某些生物学特性进行了研究,包括对１日龄鸡的致病性、溶血性、菌毛的表达、血凝性、对鸡胚成纤维细胞（ＣＥＦ）的粘附特性、体内外与鸡气管粘膜的粘附特征、质粒特征、全菌蛋白ＳＤＳ－ＰＡＧＥ电泳及免疫转印等。结果表明,鸡源大肠埃希氏菌的溶血性、质粒特征、对ＣＥＦ的粘附特性与其致病性无关;菌毛与致病性有关,大部分菌株表达Ⅰ型菌毛;血凝能被Ｄ－甘露糖抑制,不同菌株血凝谱具有差异;体内外与气管粘膜的粘附特性与菌株致病性有关;在全菌蛋白ＳＤＳ－ＰＡＧＥ电泳中,相对分子质量约为４０７００的多肽仅存在于具有致病性的菌株中,经免疫转印证实,该多肽为致病性大肠埃希氏菌所特有     

禽大肠杆菌菌毛粘附特性的研究

用透射电镜观察了鸡大肠杆菌的３个致病菌株ＧＬ７（Ｏ５０）、ＨＢ５（Ｏ７８）及ＴＧ１８（Ｏ８８），发现在营养肉汤中于３７℃培养均表达菌毛，但在１８℃培养不表达菌毛，用３７℃培养的大肠杆菌对鸡气管粘膜做粘附试验，并用扫描电镜观察，发现它们对体内体外的鸡气管均可粘附，但１８℃培养的大肠杆菌均缺乏这种粘附作用。采用粘附抑制试验测定这３种菌株对体外鸡气管节段粘附的特异性，结果是抗这３种细菌菌毛的抗体能显著抑制各自相应的菌株对气管上皮的粘附；Ｏ７８株和Ｏ８８株对气管上皮的粘附作用可被甘露糖显著抑制，表明甘露糖对介导菌体对气管粘膜上皮细胞受体起重作用。用甘露糖不能抑制Ｏ５０菌株对气管上皮的粘着，表明该菌体的粘附作用不由甘露糖介导。用高碘酸钠处理能抑制所有菌株的粘附作用，再次表明细菌对气管上皮的粘附作用是由单糖介导的     

禽大肠杆菌病的流行、症状与预防

1流行情况 禽大肠杆菌病是由致病性大肠杆菌引起的禽类的急性或慢性疾病的总称。由大肠埃希氏引起的鸡的原发性与继发性条件性传染病一年四季均可发生。本病侵害各种年龄的鸡,对多数抗生素敏感。但由于极易产生抗药性给鸡场带来较大的经济损失。本病可经卵感染,腹膜炎及输管炎可使卵巢污染而引起卵内感染,卵壳被带菌粪便污染,可引起初生雏大肠杆菌败血症。本病菌经呼吸道吸入被大肠杆菌污染的绒毛粉尘而引起气囊炎及败血症。     

鸡场流行大肠杆菌的原因及对策

一、鸡场流行大肠杆菌病的成因： 1、饲养环境差，不卫生，或饲养密度过大，是常见的发病诱因。 在正常情况下，大肠杆菌普遍存在于鸡的肠道中。据检测，随意采1克健康鸡只粪便样品，运用微生物学方法计数，常常含有100万个左右的大肠杆菌。尽管多数是非致病性的，但也有不少可产生肠道外感染。常见的致病性菌株有O2、O78、O1、O35、和O36等血清型。这些致病性菌株随鸡粪排出体外后，有一部分随空气飘散，鸡只一呼一吸，就有可能落在鸡呼吸道粘膜上，借助菌毛（多为I型菌毛）粘附，得以在“上皮”上定居，从而获得“侵袭的通道”。当鸡只因饲养条件差，抵抗力下降时，致病性大肠杆菌便通过“侵袭的通道”乘机侵入体内，呈现急性、致死性败血症和亚急性心包炎和气囊炎。     

鸡传染性腺胃炎病毒(暂定名)的致病性

用暂定为鸡传染性腺胃炎病毒（ＩＰＶ）的ＺＪ９７１株,经口服、腹腔、泄殖腔、口服－腹腔－泄殖腔联合不同途径接种于８日龄来航非免疫雏鸡,均可引起雏鸡发病;其中,以口服－腹腔－泄殖腔联合途径感染效果最佳,腹腔途径次之一。感染雏鸡生长阻滞、体重增长缓慢;剖析眼观病变主要以腺胃重量增加,腺胃指数增大,胸腺、法氏囊萎缩为特征;病理组织学变化主要以萎缩性胃炎、法氏囊炎、十二脂肠卡他性炎为特征。     

禽致病性大肠杆菌菌毛研究进展

禽致病性大肠杆菌的血清型以O1、O2、O8、O78等为主。研究表明，这类大肠杆菌均具有菌毛。菌毛叉称纤毛、柔毛，是大肠杆菌的一种蛋白质突起，禽大肠杆菌菌毛主要有I型菌毛和P型菌毛两种，目前认为菌毛是大肠杆菌的重要致病因子，与大肠杆菌的致病性密切相关，菌体借助菌毛与气管黏膜上的特异性受体结合，从而致病。菌毛在体外的表达具有温度及营养的依赖性。近年来，对大肠杆菌菌毛的研究越来越多，特别是随着分子生物学的发展，对禽大肠杆菌菌毛的研究也不断深入，取得了不少的研究成果。本文试就禽致病性大肠杆菌菌毛的体外表达与提取、粘附特性与致病性、免疫学特性及其分子生物学的有关研究作一综述，以供参考。     

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