Parturition invokes changes in peripheral blood mononuclear cell populations in Holstein dairy cows naturally infected with Mycobacterium avium subsp. paratuberculosis

Johne's disease (JD) is characterized by a protracted period of subclinical infection. Infected cows may remain in the subclinical state until stressors such as parturition and lactation invoke more clinical signs of disease. The objective of this study was to evaluate changes in the percentages of CD4(+), CD8(+), and gammadelta T-cells, B-cells, monocytes, as well as the expression of the activation marker, CD5, on these cell subpopulations in the peripheral blood of dairy cows naturally infected with Mycobacterium avium subsp. paratuberculosis (MAP) during the periparturient period. Peripheral blood mononuclear cells (PBMCs) were collected from 3 wk pre- to 4 wk post-calving and freshly isolated or cultured for 7d. Day 7 cultures were infected with live MAP at a 10:1 MOI (bacteria to adherent PBMC), and cultures were incubated for an additional 24h. Fluorescent antibody labeling of lymphocyte subsets and monocytes was conducted and analyzed with flow cytometry. Freshly isolated PBMCs from subclinical cows expressed a greater (P<0.05) percentage of CD8(+) and gammadelta T-cells compared with clinical cows. The percentage of CD4(+) T-cells increased (P<0.08) in clinical cows as parturition approached. During the postpartum period, clinical cows had greater (P<0.05) CD4:CD8 ratios compared with subclinical and control cows. After 8d, uninfected PBMCs from clinical cows had greater (P<0.05) percentages of CD14(+) cells compared with subclinical cows. When infected with live MAP, there was no effect of infection group or parturition on cell subpopulations. In fresh PBMCs, clinical cows expressed lower percentages of CD4(+)CD5(bright) and CD8(+)CD5(bright) compared with control cows, but greater percentages of CD5(dim) cells for all lymphocyte subsets. These results suggest changes in the percentages of lymphocyte subsets, monocytes, and CD5 markers are modulated by both infection status and the periparturient period.     

The kinetics of cytokine production and CD25 expression by porcine lymphocyte subpopulations following exposure to classical swine fever virus (CSFV)

Surface expression of IL-2R-alpha (CD25) is widely used to identify activated lymphocyte populations, while interferon-gamma (IFN-gamma) levels have been shown to be a good indicator of cell-mediated immunity (CMI) in pigs. To investigate the relationship between these two parameters, we developed an intracellular cytokine-staining assay and studied the kinetics of cytokine (IFN-gamma and interleukin-10, IL-10) production relative to CD25 expression in porcine lymphocyte subpopulations, following immunization with a classical swine fever (CSF) vaccine. The number of activated memory T cells (CD4(+)CD8(+)CD25(+) cells) increased slightly in the peripheral blood mononuclear cell (PBMC) population soon after vaccination, then diminished within a few weeks. The number of activated cytotoxic T cells (CD4(-)CD8(+)CD25(+) cells) peaked approximately 2 weeks after the memory population. Although the number of IFN-gamma producing cells detected in this experiment was relatively low, the CD4(+)CD8(+) T cells were major IFN-gamma producers in the PBMCs throughout the experiment. In another experiment, CSF-vaccinated pigs were challenged with a virulent classical swine fever virus (CSFV), and the kinetics of CD25 expression and cytokine productions were monitored. Following exposure to the virus, the number of IFN-gamma producing cells in the PBMCs increased markedly in both the vaccinated and unvaccinated groups. The CD4(-)CD8(+) cells were major IFN-gamma producing cells in vaccinated pigs, while both CD4(+)CD8(+) and CD4(-)CD8(+) populations contributed to the IFN-gamma production in the control group. Interestingly, the enhanced IFN-gamma production was not associated with the upregulation of CD25 expression following the CSFV challenge. In addition, exposure to the virulent CSFV significantly increased interleukin-10 production by the CD4(-)CD8(+) populations in PBMCs of the unvaccinated pigs. Taken together, our results indicated that CD25 expression and IFN-gamma production were not tightly associated in porcine lymphocytes. In addition, the CD4(-)CD8(+) lymphocytes of the PBMCs played a major role in cytokine productions following the CSFV challenge.     

Effects of phenylbutazone and anabolic steroids on adrenal and thyroid gland function tests in healthy horses

Adrenal and/or thyroid gland function tests were evaluated in horses at various times during short-term therapy with phenylbutazone, stanozolol, and boldenone undecylenate. There were no significant treatment or time effects on mean basal plasma cortisol concentrations in horses during treatment with the following: phenylbutazone, given twice daily (4 to 5 mg/kg, IV) for 5 days; stanozolol, given twice weekly (0.55 mg/kg, IM) for 12 days; boldenone undecylenate, given twice weekly (1.1 mg/kg, IM) for 12 days; or nothing. There was no significant effect of phenylbutazone treatment on the changes in plasma cortisol concentration during the combined dexamethasone-suppression adrenocorticotropic hormone (ACTH)-stimulation test. Plasma cortisol concentration was significantly decreased from base line at 3 hours after dexamethasone administration and was significantly increased from base line at 2 hours after ACTH in all horses (P less than 0.05). Likewise, the stimulation of basal plasma cortisol concentrations at 2 hours after administration of ACTH (P less than 0.05) was not affected by treatment with stanozolol or boldenone undecylenate. There were no significant treatment effects on mean basal plasma concentrations of thyroxine (T4) or triiodothyronine (T3) among horses during the following treatments: stanozolol, given twice weekly (0.55 mg/kg, IM) for 12 days; boldenone undecylenate, given twice weekly (1.1 mg/kg, IM) for 12 days; or nothing. There was a significant time effect on overall mean basal plasma T4 and T3 concentrations (P less than 0.05): plasma T4 was lower on day 8 than on days 1, 10, and 12; plasma T3 was higher on day 8 than on days 4 and 12.(ABSTRACT TRUNCATED AT 250 WORDS)     

地塞米松和饲粮能量水平对肉仔鸡能量采食及神经肽Y基因表达的影响

本试验旨在探讨注射地塞米松(DEX)模拟应激状态下,应激和饲粮能量水平对肉仔鸡能量采食的影响。选取体重相近的180只23日龄的雄性爱拔益加(AA)肉鸡随机分成6组,每组3个重复,每个重复10只鸡。试验采用2×3析因设计,因素为DEX[处理(注射DEX2 mg/kg)、未处理(注射等剂量生理盐水)]和饲粮能量水平[高能(HE)、低能(LE)以及高能、低能自由采食(H-LE)]。预试期5 d,正试期7 d。结果表明:1)DEX处理极显著降低了肉仔鸡的采食量和体增重(P<0.01),极显著提高了耗料增重比、耗能增重比、腹脂率以及血浆葡萄糖、甘油三酯和尿酸的浓度(P<0.01),显著提高了肠道指数(P<0.05)。2)采用LE饲粮体增重(P<0.05)、腹脂率(P<0.01)显著低于其他2种饲粮,耗料增重比显著低于HE饲粮(P<0.05);采用HE饲粮耗能增重比极显著高于其他2种饲粮(P<0.01);采用H-LE饲粮神经肽Y(NPY)基因表达量显著高于LE饲粮(P<0.05)。3)DEX、饲粮能量水平对耗料增重比(P<0.05)和耗能增重比(P<0.01)的影响存在显著的互作效应。结果提示,DEX应激可使肉仔鸡血浆中葡萄糖、尿酸和甘油三酯的浓度升高;DEX应激和HE饲粮均能增加脂肪在腹部沉积,提高耗料增重比和耗能增重比;H-LE饲粮能上调肉仔鸡下丘脑NPY基因表达。     

Improved immune responses against avian influenza virus following oral vaccination of chickens with HA DNA vaccine using attenuated Salmonella typhimurium as carrier

This study evaluates the immune responses of single avian influenza virus (AIV) HA DNA vaccine immunization using attenuated Salmonella enterica sv. Typhimurium as an oral vaccine carrier and intramuscular (IM) DNA injection. One-day-old specific-pathogen-free (SPF) chicks immunized once by oral gavage with 10(9) Salmonella colony-forming units containing plasmid expression vector encoding the HA gene of A/Ck/Malaysia/5858/04 (H5N1) (pcDNA3.1.H5) did not show any clinical manifestations. Serum hemagglutination inhibition (HI) titer samples collected from the IM immunized chickens were low compared to those immunized with S. typhimurium.pcDNA3.1.H5. The highest average antibody titers were detected on day 35 post immunization for both IM and S. typhimurium.pcDNA3.1.H5 immunized groups, at 4.0±2.8 and 51.2±7.5, respectively. S. typhimurium.pcDNA3.1.H5 also elicited both CD4(+) and CD8(+) T cells from peripheral blood mononuclear cells (PBMCs) of immunized chickens as early as day 14 after immunization, at 20.5±2.0 and 22.9±1.9%, respectively. Meanwhile, the CD4(+) and CD8(+) T cells in chickens vaccinated intramuscularly were low at 5.9±0.9 and 8.5±1.3%, respectively. Immunization of chickens with S. typhimurium.pcDNA3.1.H5 enhanced IL-1β, IL-12β, IL-15 and IL-18 expressions in spleen although no significant differences were recorded in chickens vaccinated via IM and orally with S. typhimurium and S. typhimurium.pcDNA3.1. Hence, single oral administrations of the attenuated S. typhimurium containing pcDNA3.1.H5 showed antibody, T cell and Th1-like cytokine responses against AIV in chickens. Whether the T cell response induced by vaccination is virus-specific and whether vaccination protects against AIV infection requires further study.     

Modulation of sheep lymphocyte responses by Fasciola hepatica excretory-secretory products

The effect of Fasciola hepatica excretory-secretory products (FhESPs) on mitogen-induced proliferation of sheep peripheral blood mononuclear cells (PBMCs) and PBMC subsets (CD2(+), CD4(+), CD8(+), gammadeltaTCR(+) or CD21(+) cells) were studied. PBMCs were incubated with Concanavalin A (ConA) or phytohemagglutinin (PHA) at optimal (1 microg per well) or suboptimal (0.25 microg per well) doses and with FhESPs at several doses (1.25-20 microg per well). PBMC subsets were incubated with ConA at a suboptimal dose and with FhESPs at 5 microg per well. These cells were incubated with or without monocytes (CD14(+) cell). FhESPs slightly increased the proliferation of PBMCs stimulated with optimal doses of PHA. FhESPs (10 and 20 microg per well) inhibited the PBMCs stimulated with optimal doses of ConA. FhESP dose-dependent inhibition was observed on PBMCs stimulated with suboptimal doses of ConA. CD21(+) lymphocytes (B lymphocytes), CD14(+) cells (monocytes) and gammadeltaTCR(+) cells were not stimulated by ConA. T lymphocyte subsets (CD2(+), CD4(+) or CD8(+) cells) proliferation was decreased by FhESPs at 5 microg per well. FhESPs inhibits the ConA-induced stimulation of sheep PBMCs and sheep T lymphocyte subsets. Further studies should be done to investigate the mechanism of this FhESP immunomodulatory effect.     

微生态制剂对应激雄性肉仔鸡生长性能和肠道健康的影响

本试验旨在研究应激对肉仔雄鸡生长性能和肠道健康的影响,以及微生态制剂的可能缓解作用。试验采用对肉仔雄鸡注射糖皮质激素(地塞米松)的应激模型,选取1日龄爱拔益加(AA)肉仔雄鸡176只,按照2×2析因进行试验设计,分为应激+微生态制剂组[皮下注射2 mg/kg BW地塞米松,饮用微生态制剂0.02 g/(只·d)]、应激组(注射2 mg/kg BW地塞米松)、微生态制剂组[注射2 mg/kg BW生理盐水,饮用微生态制剂0.02 g/(只·d)]、空白组(注射2 mg/kg BW生理盐水)4个组,每组4个重复,每个重复11只鸡。微生态制剂组和应激+微生态制剂组在肉鸡11~14日龄和25~28日龄饮水中添加用冷却沸水溶解的微生态制剂,应激组和空白组饮用相同体积不含微生态制剂的冷却沸水。应激组和应激+微生态制剂组在肉鸡12~14日龄和26~28日龄皮下注射地塞米松磷酸钠,微生态制剂组和空白组注射相同剂量的生理盐水。试验期35 d。结果表明:应激导致肉仔雄鸡35日龄的平均体重、平均日增重和欧洲效益指数显著降低(P0.05),料重比和死淘率显著提高(P0.05),15日龄和29日龄的免疫器官指数和空肠绒毛高度显著降低(P0.05);微生态制剂使肉仔雄鸡29日龄的胰脂肪酶活性和空肠绒毛高度显著提高(P0.05),隐窝深度显著降低(P0.05)。在绒毛高度/隐窝深度指标上,应激和微生态制剂有显著的交互作用(P0.05)。结果提示:应激能破坏肉仔雄鸡肠道微环境,降低肉仔雄鸡生长性能,抑制免疫器官正常发育;微生态制剂能显著缓解应激对肠道绒毛的损伤,但未发现微生态制剂对生长性能的显著作用。     

Flow cytometric analysis of peripheral blood mononuclear cells induced by experimental endotoxemia in horse

Cellular activation and functional cell surface markers were evaluated during experimentally-induced endotoxemia in healthy horses. Eight healthy adult horses were infused a low dose of endotoxin (lipopolysaccharide from Escherichia coli O26: B6, 30 ng/kg of body weight, IV) and five control horses were given an equivalent volume of sterile saline solution. Venous blood samples were collected for flow cytometric analysis of peripheral blood mononuclear cells (PBMCs) and to measure plasma endotoxin concentrations. Clinical signs of endotoxemia were recorded at 10, 20, 30, 40, 50 min, 1, 2, 3, 4, 8, 16, 24 and 48 hr after endotoxin or saline solution administration. Clinical findings characteristic of endotoxemia (tachycardia, tachypnea, increased rectal temperature, and leukopenia) occurred transiently in all horses administered endotoxin; however, plasma endotoxin concentrations were detectable in only 50% (4/8) of the endotoxin-infused horses. The percentage of CD4(+), CD5(+), and CD8(+) cells decreased while the percentage of CD14(+), IgM(+), and MHC class II(+) cells increased significantly after endotoxin infusion. Alterations in the immunophenotype of PBMCs from horses with experimentally-induced endotoxemia were associated with changes in vital signs, indicating that endotoxin altered the immuno balance.     

In vitro effects of dexamethasone on bovine CD25(+)CD4(+) and CD25(-)CD4(+) cells

This paper investigates the in vitro effect of dexamethasone on bovine CD25(high)CD4(+), CD25(low)CD4(+) and CD25(-)CD4(+) T cells. Only a small percentage of bovine CD25(high)CD4(+) (2-4%) and CD25(low)CD4(+) (1-2%) cells expressed Foxp3. Dexamethasone caused considerable loss of CD25(-)CD4(+) cells, but it increased the relative and absolute numbers of CD25(high)CD4(+) and CD25(low)CD4(+) lymphocytes, while at the same time reducing the percentage of Foxp3(+) cells within the latter subpopulations. Considering all these, as well as the intrinsically poor Foxp3 expression in bovine CD25(+)CD4(+), it can be concluded that the drug most probably increased the number of activated non-regulatory CD4(+) lymphocytes. It has been found that changes in cell number were at least partly caused by proapoptotic effect of the drug on CD25(-)CD4(+) cells and antiapoptotic effect on CD25(high)CD4(+) and CD25(low)CD4(+) cells. The results obtained from this study indicate that the involvement of CD4(+) lymphocytes in producing the anti-inflammatory and immunosuppressive effect of dexamethasone in cattle results from the fact that the drug had a depressive effect on the production of IFN-γ by CD25(-)CD4(+) cells. Secretion of TGF-β and IL-10 by CD4(+) lymphocytes was not involved in producing these pharmacological effects, because the drug did not affect production of TGF-β and, paradoxically, it reduced the percentage of IL-10(+)CD4(+) cells.     

Comparative effects of fluoroquinolones on subsets of T lymphocytes in normothermic and hyperthermic mice

The subsets of T lymphocytes in thymus, spleen and mesenteric lymph nodes were investigated in normothermic and hyperthermic mice treated with fluoroquinolones administered orally six times at 24 h intervals at doses of 15 or 75 mg/kg (flumequine, norfloxacin and ciprofloxacin) and 5 or 25 mg/kg (enrofloxacin). It has been found that fluoroquinolones can modulate CD3+, CD4+ and CD8+ marker expression on thymocytes, splenocytes and lymphocytes of mesenteric lymph nodes. Flumequine (15 mg/kg) decreased the percentage of immature CD4+CD8+ thymic cells and increased the percentage of mature CD4+ and CD8+. When the dose of flumequine was increased to 75 mg/kg a reduction in the maturation of thymocytes was observed. Administration of flumequine, norfloxacin and ciprofloxacin, irrespective of doses applied, increased the percentages of CD3+ splenocytes of CD4+ spleen cells. Exposure to enrofloxacin decreased the percentage of T helper-inducer cells. Flumequine and ciprofloxacin augmented the percentage of CD3+ mesenteric lymph node cells and increased the percentage of CD8+ cells. In contrast, norfloxacin and enrofloxacin decreased the percentage of CD3+ mesenteric lymph node cells and the percentage of CD4+ cells. Lipopolysaccharide (LPS) from E. coli (25 micro g/mouse) increased the percentage of single-positive CD4+ thymocytes, but did not affect the percentage of CD3+, CD4+ and CD8+ splenocytes and mesenteric lymph node cells. Flumequine and ciprofloxacin administered to mice pior to LPS potentiated its stimulant effect on the maturation of thymic cells ( increased percentage of mature CD4+ and CD8+ thymocytes). Pre-treatment with norfloxacin or enrofloxacin either reduced or did not modify the stimulant effect of LPS on maturation of thymic cells. Flumequine, norfloxacin, enrofloxacin and ciprofloxacin administered prior to LPS decreased the percentage of CD8+ splenocytes and increased the percentage of CD4+ spleen cells. Norfloxacin and ciprofloxacin at a dose of 75 mg/kg reduced the percentage of CD8+ mesenteric lymph node cells in hyperthermic mice. Pretreatment with norfloxacin at a dose of 15 mg/kg augmented the percentage of mesenteric lymph node cells. It was concluded that the modulating effects of fluoroquinolones depends on the chemial structure of drugs, dose administered as well as immunologic status.     

Effects of dexamethasone, levamisole, and dexamethasone-levamisole combination on neutrophil function in female goats

Effects of dexamethasone, levamisole, or combined dexamethasone-levamisole administration on polymorphonuclear neutrophil (PMN) function in healthy, adult female goats were studied. Goats were assigned to treated (n = 6) and control (n = 6) groups. In experiment 1, treated goats were given levamisole (6 mg/kg of body weight, IM). In experiment 2, treated goats were given 0.1 mg of dexamethasone/kg, IV, for 3 consecutive days, 1 mg of dexamethasone/kg, IV, for 6 consecutive days, and 6 mg of levamisole/kg, IM, with a 4th injection of 1 mg of dexamethasone/kg. All injections were administered 12 hours before blood collection. The PMN were evaluated for random migration and chemotaxis under agarose, ingestion of Staphylococcus aureus, cytochrome C reduction, iodination, and antibody-dependent cell-mediated cytotoxicity. Levamisole alone did not alter the function of caprine PMN. Both doses of dexamethasone caused increased random migration and decreased cytochrome C reduction and iodination. Dexamethasone resulted in no changes in chemotaxis, S aureus ingestion, and antibody-dependent cell-mediated cytotoxicity. Random migration and cytochrome C reduction returned toward base line in cells from dexamethasone and levamisole-treated goats. Although iodination activity in cells from dexamethasone-treated goats remained significantly (P less than 0.05) lower than those of controls after levamisole administration, a rebound toward base-line activity occurred.     

盐酸小檗碱对肉兔屠宰性能及肉质的影响

采用单因子随机区组试验设计,选用128只50日龄体重相近的健康新西兰兔,随机分为4组,1个对照组和3个处理组,每组32个重复,每个重复1只。对照组饲喂基础饲粮,3个处理组分别在基础饲粮上添加10、20、30 mg/kg的盐酸小檗碱。预试期为7 d,正试期为27 d。结果表明:对照组屠宰率极显著低于其余3组(P<0.01);20 mg/kg组和30 mg/kg组背最长肌总能含量分别显著(P<0.05)和极显著(P<0.01)低于10 mg/kg组和对照组;对照组背最长肌粗脂肪含量极显著高于其余3组(P<0.01),而10 mg/kg组显著高于20 mg/kg组和30 mg/kg(P<0.05);对照组和10 mg/kg组背最长肌pH和熟肉率均极显著低于20 mg/kg组和30 mg/kg组(P<0.01),而失水率和剪切力均极显著高于20 mg/kg组和30 mg/kg组(P<0.01);对照组背最长肌滴水损失极显著高于其余3组(P<0.01),30 mg/kg组分别显著(P<0.05)和极显著(P<0.01)低于20 mg/kg组和10 mg/kg组。结果提示,饲粮添加小檗碱可提高肉兔屠宰率,改善肉品物理性状,但会降低肉品粗脂肪含量。     

Influence of bestatin, an inhibitor of aminopeptidases, on T and B lymphocyte subsets in mice

Bestatin, a low-molecular weight dipeptide, is a potent inhibitor of aminopeptidase N which has been demonstrated to have antitumor and immunomodulatory effects. The effects of bestatin (10, 1 and 0.1 mg/kg) administered intraperitoneally once, five or ten times to mice on the total number of lymphocytes in the thymus, spleen and mesenteric lymph nodes and the percentage and the absolute number of T cell subsets (CD4+CD8+, CD4-CD8-, CD4+, CD8+) in the thymus and T (CD3+, CD4+, CD8+) and B (CD19+) lymphocytes in the spleen and mesenteric lymph nodes were studied. It has been found that bestatin administered ten times at doses of 10, 1 and 0.1 mg/kg increased the total number of thymocytes, splenocytes and lymphocytes of mesenteric lymph nodes. Bestatin also changed the percentage and the absolute number of T cell subsets in the thymus and T and B lymphocytes in the peripheral lymphatic organs. Five and ten exposures to bestatin (10, 1 and 0.1 mg/kg) increased the absolute count of both immature CD4+CD8+ and CD4-CD8- thymic cells. Moreover, both a single and multiple administration of bestatin (1 and 0.1 mg/kg) decreased the percentage and absolute count of CD3+ splenocytes and mesenteric lymph node cells with corresponding decreases in the percentage and absolute count of CD4+ and CD8+ cells. Both a single and multiple administration of bestatin at all the doses under investigation augmented the percentage and the absolute count of CD19+ (B lymphocytes) in the peripheral lymphatic organs. The results of the study show that there is a relationship between the effect induced by bestatin and the dose of the drug as well as the number of doses applied. The strongest effect on the T and B lymphocyte subsets was noted after five injections of bestatin at doses of 1 and 0.1 mg/kg.     

Experimental haemonchosis in goats: effects of single and multiple infections in the host response

Histopathological changes and the distribution of T lymphocytes (CD3), B cells (CD79alpha) and IgG secreting plasma cells were recorded in the abomasum and abomasal lymph nodes of goats during early and late post-infection stages with one to four doses of Haemonchus contortus L3. The infiltration of eosinophils, mast cells, CD3(+) T lymphocytes, CD79alpha(+)B cells and IgG(+) plasma cells in the abomasal mucosa increased dramatically from 10dpi onwards, whereas globule leukocytes were observed only during chronic infection. In late post-infection stages abomasal infiltration of globule leukocytes, CD3(+) T lymphocytes, CD79alpha(+)B cells and IgG(+) plasma cells was significantly higher (P<0.05) in reinfected (groups 6-8) than in primarily infected goats (group 5). In the abomasal lymph nodes, marked hyperplasia of lymphoid follicles and medullary cords, with increase of CD3(+) T lymphocytes, CD79alpha(+)B cells and IgG(+) plasma cells was recorded from 10dpi (group 3) onwards. Worm burdens and the severe abomasal response during the late post-infection stages suggests that a rapid expulsion of nematodes did not occur. The prolonged time required for generating globule leukocytes suggested that immune mechanisms dependent of this cell type are of crucial importance in the protective immunity against H. contortus in goats.     

壳寡糖对虹鳟生长性能、血清生化指标及非特异性免疫功能的影响

本文旨在研究壳寡糖对虹鳟生长性能、血清生化指标及非特异性免疫功能的影响。选用体重约为 ６０ｇ的虹鳟 ４８０尾,随机分为 ４组（每组 ４个重复,每个重复 ３０尾）,分别饲喂在基础饲料中添加 ０、１００、２００和 ４００ｍｇ／ｋｇ壳寡糖的试验饲料。试验期为 ４９ｄ。结果表明：１）与对照组相比,１００、２００和 ４００ｍｇ／ｋｇ壳寡糖组的特定生长率分别提高了 ５．６０％（Ｐ＜０．０５）、１５．８９％（Ｐ＜０．０５）和１８．６９％（Ｐ＜０．０５）,增重率分别提高了７．５３％（Ｐ＜０．０５）、２１．２１％（Ｐ＜０．０５）和 ２６．０２％（Ｐ＜０．０５）,蛋白质效率分别提高了 ０．６０％（Ｐ＞０．０５）、７．０２％（Ｐ＞０．０５）和９．７９％（Ｐ＜０．０５）,饲料系数分别降低了 ０．６０％（Ｐ＞０．０５）、６．５５％（Ｐ＞０．０５）和 ８．９３％（Ｐ＜０．０５）;２）饲料中添加壳寡糖提高了虹鳟血清总蛋白、白蛋白、球蛋白含量（Ｐ＞０．０５）,降低了血清甘油三酯、胆固醇、葡萄糖含量以及谷丙转氨酶和谷草转氨酶活性（Ｐ＞０．０５）;３）饲料中添加２００和 ４００ｍｇ／ｋｇ壳寡糖可显著或极显著提高虹鳟的白细胞吞噬百分率（Ｐ＜０．０５）、吞噬指数（Ｐ＜０．０５）,血清杀菌百分率（Ｐ＜０．０１）以及血清、肝脏和鳃中溶菌酶活性（Ｐ＜０．０５）;４）虹鳟全鱼水分、粗蛋白质、粗脂肪、灰分含量在各组间差异不显著（Ｐ＞０．０５）。由此得出,在本试验条件下,饲料中添加壳寡糖可提高虹鳟的生长性能和非特异性免疫功能,建议添加量为２００ｍｇ／ｋｇ。     

Effects of dexamethasone on emesis in cats sedated with xylazine hydrochloride

OBJECTIVE: To determine antiemetic efficacy of prophylactic administration of dexamethasone and its influence on sedation in cats sedated with xylazine hydrochloride. ANIMALS: 6 healthy adult cats (3 males and 3 females). PROCEDURE: The prophylactic antiemetic effect of 4 doses of dexamethasone (1, 2, 4, and 8 mg/kg of body weight, IM) or saline (0.9% NaCl) solution (0.066 ml/kg, IM) administered 1 hour before administration of xylazine (0.66 mg/kg, IM) was evaluated. Cats initially were given saline treatment (day 0) and were given sequentially increasing doses of xylazine on days 7, 14, 21, and 28. After xylazine injection, all cats were observed for 30 minutes to allow assessment of frequency of emesis and time until onset of the first emetic episode.The influence of dexamethasone on xylazine-induced sedation in these cats also was evaluated. RESULTS: Prior treatment with 4 or 8 mg/kg of dexamethasone significantly reduced the frequency of emetic episodes and also significantly prolonged the time until onset of the first emetic episode after xylazine injection. Time until onset of the first emetic episode also was significantly prolonged for dexamethasone at a dose of 2 mg/kg. Time until onset of sedation after administration of xylazine was not altered by administration of dexamethasone. CONCLUSIONS AND CLINICAL RELEVANCE: Dexamethasone (4 or 8 mg/kg, IM) significantly decreased the frequency of emetic episodes induced by xylazine without compromising sedative effects in cats. Dexamethasone may be used prophylactically as an antiemetic in cats treated with xylazine.     

Influence of betulinic acid on lymphocyte subsets and humoral immune response in mice

Betulinic acid is a pentacyclic triterpene found in many plant species, among others, in the bark of white birch Betula alba. Betulinic acid was reported to display a wide range of biological effects, including antiviral, antiparasitic, antibacterial, anticancer and anti-inflammatory activities. The effects of betulinic acid (50, 5, 0.5 mg/kg) administered orally five times at 24 hours intervals to non-immunized and red blood cells (SRBC)-immunized mice were determined. The present study examined the total number of lymphocytes in the thymus, spleen and mesenteric lymph nodes, and the percentage of subsets of T cells (CD4+CD8+, CD4CD8, CD4+, CD8+) in thymus,T (CD3+, CD4+, CD8+) and B (CD19+) lymphocytes in the spleen and mesenteric lymph nodes, as well as white blood cell (WBC) and differential leukocyte counts in non-immunized mice, and humoral immune response in SRBC-immunized mice. SRBC was injected 24 hours after administration of the last dose of betulinic acid. It was found that betulinic acid administered orally five times at the dose of 0.5 mg/kg increased the total number of thymocytes, splenocytes, lymphocytes of mesenteric lymph node cells, and the weight ratio of the spleen and mesenteric lymph nodes in non-immunized mice. Betulinic acid also changed the percentage of T cell subsets in the thymus and T and B lymphocytes in peripheral lymphatic organs. The effects of betulinic acid on T and B cell subpopulations depended on the dose applied. The strongest stimulating effect of betulinic acid was observed when the drug was administered at the dose of 0.5 mg/kg. Five exposures to betulinic acid (0.5 mg/kg) decreased the percentage of immature CD4+CD8+ thymic cells with corresponding increases in the percentage and absolute count of mature, single-positive CD4+ thymocytes and decreased the percentage and total count of CD3+ splenocytes and mesenteric lymph node cells with corresponding decreases in the percentage and absolute count of CD4+ and CD8+ cells. Multiple administration of betulinic acid at the investigated doses augmented the percentage and absolute count of CD19+ cells in the peripheral lymphatic organs. Moreover, betulinic acid at the dose of 5 mg/kg administered prior to SRBC immunization increased the number of plaque forming cells (PFC) but decreased the production of anti-SRBC antibodies on day 4 after priming. Thus, betulinic acid is a potential biological response modifier and may strengthen the immune response of its host.     

Cell-mediated immune function in lambs chronically treated with dexamethasone

Crossbred ewe and wether lambs were individually stanchioned in environmentally controlled rooms at 20 degrees C. On d 0, lambs were treated with .04 mg of dexamethasone (DEX; n = 10)/kg of BW or given an equal volume of saline vehicle (SAL; n = 10). Treatment was repeated every 48 h for 14 d. Samples of blood were obtained by puncture of the jugular vein on d 0 (before treatment), 2, 4, 7, 10, and 14. Total and differential leukocyte numbers, lymphocyte blastogenic responses to mitogens, and in vitro production of interleukin-2 (IL-2) were determined. No treatment x day interaction was noted for any of the experimental end points (P greater than .10); therefore, within-day comparisons between DEX- and SAL-treated lambs were not made. However, over all 14 d, DEX-treated lambs had increased (P less than .05) numbers of lymphocytes (6.5 +/- .4 vs 5.1 +/- .4 x 10(3) cells/microliters for SAL) and monocytes (.8 +/- .1 vs .6 +/- .1 x 10(3) cells/microliters for SAL), and these increases contributed to an increase (P less than .01) in total leukocytes (11.2 +/- .5 vs 9.1 +/- .5 x 10(3) cells/microliters for SAL). Lymphocyte blastogenic responses to mitogens were not affected by DEX treatment. Production of IL-2 was reduced (P less than .05) for DEX- (.90 +/- .12 units/ml) compared with SAL-treated lambs (1.27 +/- .13 units/ml). The data suggest that continued treatment of lambs with DEX may result in a modest reduction in production of IL-2, but mitogen-stimulated blastogenic responses of lymphocytes are not reduced by DEX treatment.     

Immune response and protective efficacy against homologous challenge in BALB/c mice vaccinated with DNA vaccine encoding Toxoplasma gondii actin depolymerizing factor gene

A DNA vaccine (pVAX1-TgADF) encoding Toxoplasma gondii actin depolymerizing factor (ADF) gene was constructed and the immune response and protective efficacy of this vaccine against homologous challenge in BALB/c mice were evaluated. High titers of specific antibody and increases in the percentage of CD4(+) and CD8(+) T lymphocyte cells were observed from BALB/c mice vaccinated with pVAX1-TgADF (P<0.05), when PBS group was used as control. The survival time of BALB/c mice in pVAX1-TgADF group was longer than those in control groups. The numbers of brain cysts in the experimental BALB/c mice immunized with pVAX1-TgADF reduced significantly compared with those in PBS group (P<0.05), and the rate of reduction could reach to around 42.8%. These results suggested that the DNA vaccine pVAX1-TgADF could generate specific humoral and cellular immune responses, prolong survival times, and reduce brain cysts load against T. gondii infection in BALB/c mice.     

壳聚糖对断奶仔猪生长性能、粪便评分及血清激素和T淋巴细胞亚群的影响

本试验旨在研究壳聚糖对断奶仔猪生长性能、粪便评分及血清激素和T淋巴细胞亚群的影响。选取28日龄断奶的杜×大×长三元杂交仔猪60头,随机分为5组(每组12头):对照组饲喂基础饲粮,试验组分别饲喂在基础饲粮中添加250、500、1 000和2 000 mg/kg壳聚糖的试验饲粮。试验期14 d。结果表明:1)饲粮添加250~2 000 mg/kg壳聚糖显著提高断奶仔猪的平均日增重(ADG)(P0.05),显著降低料重比(F/G)(P0.05);2)饲粮添加250~2 000 mg/kg壳聚糖显著降低试验第11天断奶仔猪的粪便评分(P0.05);3)饲粮添加适宜剂量的壳聚糖显著提高断奶仔猪的血清促生长激素释放激素(GHRH)(250~2 000 mg/kg)、生长激素(GH)(500~1 000 mg/kg)和瘦素(LP)(2 000 mg/kg)的浓度(P0.05),显著降低血清促肾上腺皮质激素释放激素(CRH)(250~2 000 mg/kg)、促肾上腺皮质激素(ACTH)(500~1 000 mg/kg)、皮质醇(COR)(250~2 000 mg/kg)和可溶性CD8(sCD8)(500~2 000 mg/kg)的浓度(P0.05)。由此可见,饲粮中添加适宜剂量的壳聚糖能够促进断奶仔猪的生长,降低腹泻,缓解断奶应激。