野外采集牦牛睾丸组织的冷冻保存及其生精细胞的复苏培养研究

采用玻璃化冷冻方法对野外采集的牦牛睾丸组织进行冷冻,通过HE(hematoxylin-eosin)染色分析发现玻璃化冷冻后的牦牛睾丸组织曲细精管结构保存较完好,曲细精管可见大量形态完好的各类生精细胞。采用台盼蓝染色检测细胞活率,发现冷冻复苏后细胞活率可达80.20%。分别通过生精细胞和精原干细胞标志蛋白DDX4和GFRA1免疫荧光染色发现复苏后培养14天后的生精细胞和精原干细胞的数量明显减少。通过RT-qPCR对复苏后不同实验处理组牦牛睾丸细胞标志基因的表达分析,发现培养30天的生精细胞中的精原干细胞标志基因Thy1和UCHL1的表达量显著增高。因此,玻璃化冷冻保存的牦牛睾丸组织中曲细精管及其生精细胞得到了较好的保护,该方法对于其他哺乳动物生精细胞的长久有效保存具有重要的参考价值。     

不同浓度海藻糖对奶山羊睾丸组织冷冻保存效果的影响

为了研究含有不同浓度海藻糖的冷冻保护液对关中奶山羊睾丸组织冷冻保存的效果,将关中奶山羊的睾丸组织切碎后,冷冻保存在含有不同浓度海藻糖的冷冻保护液中,保存1个月后解冻,分别检测冷冻保存前后睾丸组织总细胞活力、总抗氧化酶(T-AOC)、超氧化物歧化酶(SOD)、过氧化氢酶(CAT)活性以及谷胱甘肽(GSH)、丙二醛(MDA)含量。结果:各试验组总细胞活力、T-AOC、SOD、CAT活性以及GSH含量均高于对照组,各试验组MDA含量低于对照组。另外,经含有15%海藻糖的冷冻保护液保存后,总细胞活力显著高于其他试验组(P0.05),T-AOC、SOD、CAT活性和GSH含量均显著高于其他试验组(P0.05),MDA含量显著低于其他试验组(P0.05)。研究结果表明,在冷冻保护液中添加海藻糖能够通过保护组织中抗氧化酶活性,提高奶山羊睾丸组织冷冻保存的效果;添加海藻糖的最佳浓度为15%。     

精原干细胞移植的研究进展

精原干细胞移植原理与其它细胞移植原理相似,主要利用显微注射法,将供体的精原千细胞移入受体睾丸内,使其能够继续进行生精过程。结合精原干细胞分离培养、纯化、冷冻,该技术开创了基因工程和家畜生产的新途径。本文对精原干细胞的分离培养、纯化、冷冻,以及同源移植和异源移植进行了简要综述。     

犊牛睾丸组织培养及PGP 9.5基因的检测

收集新生牛睾丸,进行组织学观察与组织的体外培养,在10%血清培养液中培养1周和2周后进行组织学观察与RT-PCR分析。结果表明:新生牛睾丸组织经体外培养1周时,管腔直径增大,精原干细胞数明显增多;体外培养2周时,管腔直径继续扩增,精原干细胞数量减少;在新鲜睾丸组织、培养1周和2周的睾丸组织中PGP 9.5持续表达。     

精原干细胞的体外培养及其潜在治疗应用价值

精原干细胞(SSCs)能够自我更新,产生大量分化的生殖细胞并在出生以后形成精子,将遗传信息传递给下一代。因为所有雌性生殖干细胞在出生前已停止增殖,所以SSCs是成年哺乳动物唯一的生殖干细胞。将有生育能力的雄性供体睾丸细胞移植到不育症雄性睾丸细胞中,不育症的雄性可以重新进行精子发生和恢复生育能力。这项移植技术已经用来研究SSCs的生物学特性。研究发现,精原干细胞可以在小鼠的曲细精管进行复制,然后迁移,精原干细胞所需自我更新的生长因子保存在哺乳动物中。因此相信该培养技术很快会被应用于人类的精原干细胞中。本文讨论了现有的和潜在的运用移植技术和体外培养精原干细胞的方法。由于辅助的生殖技术能使精子细胞进入卵母细胞使之受精,所以在体外培养分化精原干细胞使之成为成熟生殖细胞的技术,将会促使人的临床精原干细胞的应用得到长足发展。     

鸡胚精原干细胞体外保存能力的研究

采用二酶3步法获取孵化第19 d的鸡胚精原干细胞（SSCs）,比较在快速冷冻条件下3种冷冻保护剂（DMSO、乙二醇、甘油）在3个浓度5%、10%、15%条件下对鸡胚精原干细胞的冷冻保存效果进行研究。结果显示：（1）当DMSO的浓度为5%、10%及15%时,复苏后细胞存活率分别为73.1%、88.6%和74.8%,三者差异显著（P〈0.05）;而10%DMSO保存精原干细胞的存活率、复苏后培养细胞生长和集落形成均显著高于其它2个浓度;当乙二醇浓度为5%、10%和15%时,复苏后细胞存活率分别为69.4%、83.1%和65.2%,三者差异显著（P〈0.05）;复苏后无论饲养层存在与否,SSCs均能增殖,但未有AKP阳性集落生成;当甘油浓度为5%、10%、15%时,复苏后细胞存活率均小于15%,三者差异不显著（P〉0.05）;复苏后细胞存活时间极短,仅存活12 h左右;（2）当在10%DMSO浓度条件,复苏后SSCs在有饲养细胞层的条件下,培养5 d形成集落,表明10%DMSO是鸡胚精原干细胞适宜的冷冻保护剂。     

新生牛生精上皮细胞体外培养的研究

两步酶消化法制备新生牛生精上皮细胞悬液,分离纯化、鉴定精原干细胞和支持细胞,冷冻保存支持细胞。以支持细胞为饲养层探索不同培养条件下精原干细胞的增殖情况,免疫组化鉴定。结果表明:10%DMSO与0.1mol/L的海藻糖组合作为冷冻保护剂,冷冻效果较好;血清浓度为2.5%、支持细胞密度为5×105个/mL时,新生牛精原干细胞较易形成集落;精原干细胞及其集落的AKP染色和C-kit免疫组化均呈阳性。     

同源物种不同饲养层对鸡精原干细胞体外培养的影响

分别以鸡胚来源的不同细胞为饲养层培养精原干细胞,比较3种不同的饲养层对精原干细胞体外培养的影响。结果显示:精原干细胞在鸡胚成纤维细胞饲养层和鸡睾丸支持细胞饲养层上存活时间较长、生长增殖状况良好。在鸡胚成纤维饲养层上传至四代,每代的AKP阳性克隆率分别为45%、40%、36%和21%。在以睾丸支持细胞为饲养层进行培养时传至三代,每代的AKP阳性克隆率分别是40%、32%、和22%。而以鸡肝细胞作为饲养层,精原干细胞未见有克隆形成,不能进行传代培养,表明鸡胚肝细胞饲养层不适合培养精原干细胞。     

小鼠精原干细胞体外培养的一般特性

将分离纯化的7～8d小鼠精原干细胞进行体外培养，结果显示，精原干细胞24h后可完全贴壁，贴壁后呈规则的圆形或卵圆形，直径(11±1)μm，以链、团状或散在方式贴附于混杂其中的睾丸体细胞层上；睾丸体细胞为多突起细胞，胞质形成2～4个突起；体外培养50～60h后，精原干细胞开始分裂。上述结果表明，在本试验培养基所提供的体外环境中，精原干细胞能够存活一定时间并发生贴壁、分裂增殖等行为。     

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