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1.
The role of neutrophils in mediating host inflammation was examined in mice vaccinated with living third-stage infective hookworm larvae (L3). Mice were vaccinated by oral immunization with 500 L3 (Ancylostoma caninum) once every 2 weeks for a total of three immunizations. The vaccinated mice were then challenged intraperitoneally with 2000 L3, 1 week after the final immunization. To stimulate peritoneal production of neutrophils, 2 ml of 2% glycogen were injected intraperitoneally at 16 h prior to the challenge infection. Neutrophils were found to comprise 85% of the peritoneal cell population. L3 from the challenge infection were collected and then examined at timed intervals by inverted light microscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Greater than a fivefold increase in the total numbers of peritoneal cells was noted in the vaccinated mice as compared to unvaccinated mice. In the peritoneal cavity of vaccinated mice, the neutrophils adhered to the L3 within 2 h, and over 55% of the L3 were surround by clusters of neutrophils to form a sausage-like sheath 4 h later. At 24–72 h after challenge, almost all of the L3 recovered from the vaccinated mice were covered with thick clusters of cells. Both SEM and TEM demonstrated extensive ultrastructural damage to the L3. In contrast, the L3 recovered from the unvaccinated mice appeared to be unaffected by neutrophils. These studies suggest that neutrophils, like macrophages, can have an important role as effector cells in L3-vaccinated mice.  相似文献   

2.
Abstract Two groups of 4 cows were vaccinated subcutaneously with live Streptococcus uberis strain 0140J or a surface extract derived from the same strain, at 14 days prior to the cessation of lactation (drying off) and at calving. Both groups also received an intramammary administration of the surface extract 7 days after drying off. A third group of unvaccinated animals acted as controls. Following intramammary challenge of two quarters per cow with the vaccine strain, all quarters on control cows and those vaccinated only with surface extract developed clinical mastitis. However, only 12.5% of challenged quarters on cows which were vaccinated with live bacteria developed clinical mastitis. In addition, the numbers of bacteria in the milk following challenge were 105 times higher from the control and extract vaccinated cows than those which received live vaccine. Serum levels of S. uberis specific IgG2 were elevated in the animals vaccinated with the live organism when compared to that of either extract-vaccinates or controls, whilst S. uberis specific levels of IgG1 and IgM were similar in all groups throughout the experiment. Specific antibody levels in milk were unaffected by vaccination. Despite increased levels of IgG2, no increase in opsonic activity was detected in any serum or milk samples. Peripheral blood lymphocytes from animals vaccinated with live organisms showed a considerable increase in proliferative response to S. uberis antigen in vitro when compared with lymphocytes from control and extract-vaccinated animals. These results suggest that neutrophils and specific opsonising antibody may not form the major defence against infection with S. uberis .  相似文献   

3.
采用田间试验方法,研究了杨树 苋菜间作系统,即株行距2 m×5 m(L1)和2 m×15 m(L2)在0(N0)、91(N1)、137(N2)和183(N3) kg·hm-2施氮水平下的土壤氮素流失特征.结果表明: 不同施氮水平对地表径流量、淋溶量和土壤侵蚀量的控制效果均为L1>L2>L3 (单作苋菜);L1、L2地表径流量分别比L3降低65.1%、55.9%;L1、L2距林带0.5 m处淋溶量比L3降低30.0%、28.9%,距林带1.5 m处淋溶量比L3降低25.6%、21.9%;L1、L2土壤侵蚀量分别比L3降低65.0%、55.1%.对地表径流和淋溶损失中TN、NO3--N、NH4+-N流失量的控制效果均为L1>L2>L3;常规施氮(91 kg·hm-2)水平下,L1地表径流中TN、NO3--N、NH4+-N流失量较L3分别降低62.9%、45.1%、69.2%,L2较L3分别降低23.4%、6.9%、46.2%;杨树间作密度越大、距离林带越近,对土壤NO3--N、NH4+-N的淋溶损失削减作用越强.同一间作密度下,随着施氮量的增加,地表径流中NO3--N流失比例减少,NH4+-N流失比例增加;淋溶流失中
NO3--N、NH4+-N浓度变化趋势一致,均为 N3>N2>N1>N0.  相似文献   

4.
An analysis was attempted of the factors which determine the adaptation of Nematodes to their vertebrate hosts. A further analysis was carried out on the adaptation to the intermediate host or hosts. A distinction was made between the intermediate host harbouring pre-infective stages (L1, L2 and the beginning of L3) and those harbouring post-infective larvae (the end of L3 and L4).  相似文献   

5.
设置全光照(L0)、透光率60%(L1)、透光率25%(L2)、透光率10%(L3)4种光环境,通过遮荫试验研究不同光照条件对香果树幼苗生理特性及叶肉细胞超微结构的影响。结果表明:遮荫影响叶片含水量及叶片形态。随着遮荫强度的加大,叶片含水量(LWC)递增,单叶面积(SLA)增加,单叶干重(SLWd)和比叶重(LAM)减小,比叶面积(LAM)增大。遮荫条件下幼苗光合作用效率呈现显著变化。全光和L1处理的PnTr日变化呈明显的双峰曲线,出现了明显的"午休",其余处理的变化相对缓和,双峰和"午休"现象不明显;Gs的日变化与Pn类似。PnTr的日均大小排序为L1 > L0 > L2 > L3。轻度遮光有利于香果树光合作用效率的提高。遮荫条件下叶片叶绿素和类胡萝卜素含量均有一定程度增加,且随着遮荫强度的加大其含量递增,提高了叶片的捕光能力。遮荫条件下MDA变化较为缓和,SOD、POD活性呈现先升后降的变化,但遮荫下的MDA含量始终小于全光照,可溶性糖也呈现类似的变化。全光下叶绿体与细胞壁平行分布,呈梭形,类囊体排列均匀,淀粉粒和嗜锇颗粒较少;遮荫条件下细胞内叶绿体数量有所增加,在整个细胞中占有比例显著增大,淀粉粒含量增多,类囊体排列紧密,堆叠程度增高,提高了弱光下的光合效率。适度遮荫香果树幼苗能维持正常的生理活动,但有效辐射光强须为自然光强的60%以上。  相似文献   

6.
以高产冬小麦品种济麦22为材料,研究不同灌溉畦长对小麦旗叶水势、光合特性和干物质积累与分配的影响.2010—2011年小麦生长季设置畦长为10(L10)、20(L20)、40(L40)、60(L60)、80(L80)和100 m(L100)的6个处理,2011—2012年和2012—2013年设置畦长为40(L40)、60(L60)、80(L80)和100 m(L100)的4个处理.结果表明: 2010—2011年生长季开花期0~200 cm土层平均土壤相对含水量为L80、L60>L100>L40>L20>L10,2011—2012年和2012—2013年为L80、L60>L100>L40.开花后11 d和21 d,旗叶水势、净光合速率和蒸腾速率均为L80、L100>L60>L40>L20、L10;花后31 d为L80>L60、L100>L40、L20、L10.L80各区间开花期和成熟期干物质积累量及籽粒产量变异系数小于L100,平均干物质积累量及开花后干物质积累量和对籽粒产量的贡献率显著高于L100、L40、L20和L10,平均籽粒产量和水分利用效率显著高于其他处理,是本试验条件下节水高产的最优畦长处理.  相似文献   

7.
Treatment of a THF solution of trans-[ReCl(N2)L4] (L = PMePh2) with a cyanamide, NCNR2 (R = Me, Et or H) or with cyanoguanidine, NCNC(NH2)2 , yields mer-[ReCl(N2)(NCNR2)L3] (1) or mer-[Re(N2)[Re(N2){NCNC(NH2)2}2L3]Cl (2), respectively, which, to our knowledge, are the first mixed dinitrogen-cyanamide-type complexes to be reported. The former products (1, R=Me or Et) can also be obtained from reaction of the benzoyldiazenido complex [ReCl2(NNCOPh)L3] with NCNR2 in refluxing methanol; the Re(II) complex mer-[ReCl2(NCNEt2)L3] (3) is also formed (conceivably via an unusual homolysis of the C---N bond of the benzoyldiazenido ligand) and its crystal structure is reported. It shows an unusual pyramidal conformation at the amine N atom of the diethylcyanamide ligand which also exhibits a significant structural trans influence on the phosphine, behaving as a stronger net electron donor than the latter ligand.  相似文献   

8.
Ketenylidenetriphenylphosphorane, Ph3PC=C=O, 1, has been used to synthesize platinum-substituted ketenes [PtMe{η1-C(PPh3)CO}L2]BF4, 2a, b (L2=1,5-cyclooctadiene, cod (a), 1,2-bis(diphenylphosphino)ethane, diphos (b)). Parent compound [PtCl{η1-C(PPh3)CO}L2]BF4, 3, with L2=cis-1,2-bis(diphenylphosphino)ethene, diphoe, was also synthesized, which is stable only at low temperature. The stability of 2 and 3 and the reactivity of the C=C=O moiety have been examined and discussed in terms of the electronic and steric characteristics of the ancillary ligands, also taking into account the reactivity of the ‘PtXL2’ fragment with other carbonyl stabilized phosphorus ylides, Ph3PCHCOR (R=Me, Ph, OMe, OEt).  相似文献   

9.
Cationic palladium(II) complexes of the type [L2Pd(CH3)(CH3CN)]BF4 (L2 = 1,3-bis(diphenylphosphino)propane (Dppp) or 1,2-bis(2,5-dimethylphospholano)benzene (Me-Duphos)) were found to catalyze the alternating copolymerization of ethene, propene and cyclopentene with sulfur dioxide, as well as the terpolymerization of ethene, propene and sulfur dioxide. The resultant materials are high melting solids with an alternating alkene-SO2 structure and an exclusive head-to-tail enchainment for propene.  相似文献   

10.
Sheep were challenged with a single large dose of larvae after vaccination with irradiated Trichostrongylus colubriformis larvae. Worm counts performed on vaccinated sheep 6 or 7 days after challenge (DAC) showed that they were solidly immune and only retarded L3 larvae were recovered at this time. Enteric plasma loss (EPL) in vaccinated animals increased immediately after challenge to peak 4–6 DAC and then decreased to pre-challenge levels. In contrast, a substantial rise in EPL did not occur in unvaccinated sheep until 10 DAC. Secretion of histamine into the duodenum of immunized sheep increased significantly from 2 to 7 DAC with the highest value at 6 DAC which corresponded with a lower duodenal tissue histamine level at this time. Histamine and 5HT secretion into the small intestine of previously uninfected sheep gradually increased during 12 weeks of a trickle infection of 3000 normal T. colubriformis larvae per week. The results indicate that rejection of incoming larvae by immune sheep is accompanied by an intestinal inflammatory response involving secretion of biogenic amines and a concurrent plasma loss.  相似文献   

11.
The enhancement of resistance by i.p. administration of murine rTNF-alpha into mice against i.p. challenge with virulent Salmonella typhimurium was studied. Administration of TNF-alpha (5 x 10(4) U/mouse) into mice at 6 or 12 h before the challenge with S. typhimurium organisms enhanced the bactericidal capacity in the peritoneal cavities of the mice. The diminution of the infecting organism in the peritoneal cavities of the TNF-alpha-treated mice was not due to the systemic spread of the organism inasmuch as few organism were recovered from other areas such as the spleen and liver. The TNF-alpha treatment effected a slight increase of neutrophils in the peritoneal cavity, but did not effect an increase of macrophages, including Ia-bearing macrophages. The survival rate of mice infected with Salmonella was improved by the i.p. injection of TNF-alpha before infection. Co-administration of smaller doses of TNF-alpha (5 x 10(3) U) and murine rIFN-gamma (10(2) U) at 6 h before the challenge also effectively enhanced bactericidal activity and protectivity. The cooperative effect of TNF-alpha and IFN-gamma was only seen when these recombinant cytokines were injected together at the proper time before the challenge. Injection of rabbit anti-TNF-alpha serum abolished the effects of TNF-alpha and the cooperative effect of TNF-alpha and IFN-gamma. Furthermore, the serum could abolish the cooperative effect of IFN-gamma and LPS on bactericidal activity, suggesting participation of LPS-induced TNF-alpha in the cooperation.  相似文献   

12.
The dimetal μ-vinylidene complexes Cp(CO)2MnPt(μ-C = CHPh)L2 (L = tert.-phosphine or -phosphite), which have been obtained by coupling of the mononuclear complex Cp(CO)2Mn=C=CHPh and unsaturated PtL2 unit, add smoothly the Fe(CO)4 moiety to produce trimetal MnFePt compounds. The μ3-vinylidene cluster CpMnFePt(μ3-C=CHPh)(CO)6(PPh3) was prepared in quantitative yields from the reactions of Cp(CO)2MnPt(μ-C=CHPh)(PPh3)L (L = PPh3 or CO) with Fe2(CO)9 in benzene at 20 °C. The phosphite-substituted complexes Cp(CO)2Mnpt(μ-C=CHPh)L2 (L = P(OEt)3 or P(OPri)3) react under analogous conditions with Fe2(CO)9 to give mixtures (2:3) of the penta- and hexacarbonyl clusters, CpMnFePt(μ3-C = CHPh)(CO)5L2 and CpMnFePt(μ3-C = CHPh)(CO)6L, respectively. The similar reaction of the dimetal complex Cp(CO)2MnPt(μ-C = CHPh)(dppm), in which the Pt atom is chelated by dppm = Ph2PCH2PPhPin2 ligand, gives only a 15% yield of the analogous trimetal μ3-vinylidene hexacarbonyl product CpMnFePt(μ3-C = CHPh)(CO)(dppm), but the major product (40%) is the tetranuclear μ4-vinylidene cluster (dppm)PtFe34-C = CHPh)(CO)9. The IR and 1H, 13C and 31P NMR data for the new complexes are reported and discussed.  相似文献   

13.
Abstract Mycobacterial mannophosphoinositides (PIMs) encapsulated in liposomes made of egg phosphatidylcholine (EPC) and cholesterol (CH) (2:1.5 molar ratio) were able to induce humoral and delayed type hypersensitivity (DTH, foot-pad swelling reaction) responses in mice without the help of any carrier protein. Animals immunized with this glycophospholipid antigen demonstrated enhanced percent survival on intravenous challenge with virulent M. tuberculosis . On fractionation of PIMs, pentamannophosphoinositide (PIM5) was found to induce higher antibody and DTH reaction and proved to be more immunoprotective than other fractions. Inclusion of lipid A as immunomodulator in liposomes containing PIMs or PIM5 resulted in a significantly increased immune response. Further, mice immunized with PIMs or PIM5 in lipid A-containing liposomes exhibited decreased mortality on challenge with M. tuberculosis H37Rv, which was comparable to BCG vaccinated animals.  相似文献   

14.
过量施用氮肥导致氮肥利用率降低,环境风险加大.合理降低施氮量、优化氮肥运筹对于小麦高产高效栽培具有重要意义.本研究采用大田试验,以常规施氮方式(240 kg N·hm-2, 基肥∶拔节肥∶孕穗肥=5∶3∶2)为对照,研究了不同施氮量(240、180、150 kg N·hm-2,分别用N240、N180、N150表示)及基苗肥施用时期(基施、4叶期施、6叶期施,分别用L0、L4、L6表示)对小麦产量和氮素利用效率的影响.结果表明: 小麦籽粒产量随施氮量的降低而降低,但N180与N240处理相比无显著差异,而N150处理显著降低;氮肥农学效率和吸收效率均以N180处理最高.不同施肥时期间,L4处理的籽粒产量和氮肥利用率最高.N180四叶施肥(N180L4)处理的产量与对照无显著差异,但氮肥利用率显著提高.N180L4处理叶面积指数、旗叶光合速率、叶片氮含量、旗叶硝酸还原酶和谷氨酰胺合成酶活性、拔节后干物质和氮素积累量较对照未显著降低.适量降低氮肥用量配合基肥后移能够提高生育后期光合生产能力和氮素吸收同化能力,在保持高产的条件下实现氮素利用效率的同步提高.  相似文献   

15.
为研究鱼粉水平和养殖密度对青鱼(Mylopharyngodon plceus)幼鱼生长及免疫的影响, 试验采用鱼粉水平(10%、20%)×养殖密度(50、100和200尾/箱)的双因素设计, 将青鱼幼鱼(2.50±0.02) g分为L50、L100、L200、H50、H100和H200 6组, 每组3个重复, 养殖试验在水库网箱(1.5 m×1.5 m×1.5 m)中进行。结果显示: (1)生长性能: 实验中期(第8周), 青鱼的增重率随养殖密度的增加呈先上升后下降趋势, 且H200组的青鱼增重率在养殖中期与L200组相比有提高的趋势, 但差异不显著(P>0.05), 在实验后期(第16周)显著低于L200组(P<0.05); L200的存活率低于L50组(P>0.05), 养殖密度和鱼粉水平对青鱼存活率与增重率有交互效应(P<0.05)。(2)免疫应激指标: 在实验中期, 低鱼粉组青鱼的溶菌酶(LSZ)、血糖(GLU)随密度的升高先下降后上升, 肠道分泌性免疫球蛋白A (S-IgA)有提高的趋势; H200组的LSZ、补体4 (C4)、免疫球蛋白M (IgM)、S-IgA和皮质醇(COR)含量均高于L200组, GLU低于L200组(P>0.05)。在实验后期, 高低鱼粉组的C4随密度的增加均呈下降后上升的趋势(P>0.05)。H200组的IgM和COR含量均高于L200组, GLU低于L200组(P>0.05)。综上所述, 在本实验条件下, 实验中期高密度养殖会使青鱼幼鱼生长性能有降低趋势, 对机体免疫、抗应激能力产生负面影响, 增加鱼粉水平有一定改善作用, 实验后期高密度养殖降低了低鱼粉饲料组青鱼的存活率, 提高鱼粉水平对高密度组青鱼生长性能和免疫功能无改善作用。  相似文献   

16.
Herpes Simplex Virus type-1 (HSV-1) and type-2 (HSV-2) establish life-long infections and cause significant orofacial and genital infections in humans. HSV-1 is the leading cause of infectious blindness in the western world. Currently, there are no available vaccines to protect against herpes simplex infections. Recently, we showed that a single intramuscular immunization with an HSV-1(F) mutant virus lacking expression of the viral glycoprotein K (gK), which prevents the virus from entering into distal axons of ganglionic neurons, conferred significant protection against either virulent HSV-1(McKrae) or HSV-2(G) intravaginal challenge in mice. Specifically, 90% of the mice were protected against HSV-1(McKrae) challenge, while 70% of the mice were protected against HSV-2(G) challenge. We constructed the recombinant virus VC2 that contains specific mutations in gK and the membrane protein UL20 preventing virus entry into axonal compartments of neurons, while allowing efficient replication in cell culture, unlike the gK-null virus, which has a major defect in virus replication and spread. Intramuscular injection of mice with 107 VC2 plaque forming units did not cause any significant clinical disease in mice. A single intramuscular immunization with the VC2 virus protected 100% of mice against lethal intravaginal challenge with either HSV-1(McKrae) or HSV-2(G) viruses. Importantly, vaccination with VC2 produced robust cross protective humoral and cellular immunity that fully protected vaccinated mice against lethal disease. Quantitative PCR did not detect any viral DNA in ganglionic tissues of vaccinated mice, while unvaccinated mice contained high levels of viral DNA. The VC2 virus may serve as an efficient vaccine against both HSV-1 and HSV-2 infections, as well as a safe vector for the production of vaccines against other viral and bacterial pathogens.  相似文献   

17.
Complexes RuCl3(PPh3)L2 (L = MeIm (1a, Im (1b)) and [RuCl2(PPh3)2(bipy)]Cl·4H2O (2) have been synthesized via the ruthenium(III) precursor RuCl3(PPh3)2 (DMA), and characterized, including an X-ray structural analysis for 1a (MeIm = N-methylimidazole, Im = imidazole, bipy = 2,2′-bipyridyl, and DMA = N, N′-dimethylacetamide). Crystals of 1a are monoclinic, space group P21/n, A = 10.5491(5), B = 20.4934(9), C = 12.8285(4) Å, β = 90.166(4)°, Z = 4. The structure, which reveals a mer configuration for the chlorides, and cis-methylimidazoles, was solved by conventional heavy atom methods and was refined by full-matrix least-square procedures to R = 0.041 and Rw = 0.042 for 3328 reflections with I 3σ(I). From the RuCl2(PPh3)3 precursor, the ruthenium(II) complexes RuCl2(PPh3)2L2 and [RuCl(PPh3)L4]Cl have been made (L = Im or MeIm), while [RuCl(dppb)Im3]Cl has been made from [RuCl2(dppb)]2(μ-dppb) (dppb = Ph2P(CH2)4PPh2).  相似文献   

18.
Five Rocky Mountain bighorn sheep (Ovis canadensis canadensis), approximately 5 mo old and without detectable antibody titers to respiratory syncytial virus (RSV), were assigned to two groups to study the effects of RSV challenge inoculation in vaccinated (n = 3) and unvaccinated (n = 2) bighorns. The three lambs vaccinated with a modified live bovine RSV vaccine developed a detectable antibody response to the vaccine. Vaccinated and unvaccinated lambs challenged with an ovine isolate of RSV developed increased levels of neutralizing antibody, but clinical signs of disease were not observed. Neutralizing antibody titers to RSV remained higher (2-4-fold) in vaccinated lambs over time when compared to unvaccinated lambs.  相似文献   

19.
It was found that the reduction of Pt(II), Pt(III) and Pt(I,III) acetates with H2 in the presence of 1,10-phenanthroline (phen), according to the standard procedure for the synthesis of palladium-561 giant clusters, resulted, unexpectedly, in the high-nuclear Pt(I) complex of the empirical composition Pt8phen3(OAc)4(OH)4(H2O)6 instead of the expected platinum colloid. Data of electron microscopy (TEM, HREM), small-angle X-ray scattering (SAXS), EXAFS and thermal analysis (DTA-TG) combined with elemental microanalysis all point to a loose structure of the obtained complex, with a minor Pt---Pt bonding (average coordination number for the Pt---Pt bonds is about 1). Variation of the preparation procedure resulted in a series of polymeric phen-platinum complexes, containing Pt atoms in oxidation states ranging from (+1) to (+0.3), and whose main structural features were established by the above-mentioned techniques. Giant clusters with dense Pt/PtOx cores (coordination number for the Pt---Pt bonds is about 6) were obtained by gradual heating of the precursor Pt complex to about 200°C as well as by a modified preparation procedure at 20°C.  相似文献   

20.
Nitrosylation of Os(H)3ClL2 (L = P1Pr3) affords the known Os(H)2Cl(NO)L2 (2). Soft electrophiles (Ag, Na) react with complex 2 by chloride abstraction to ultimately yield truly 16-electron dihydride Os(H)2(NO)(P1Pr3)2 (4a), characterized by variable-temperature NMR. Complex 4a reversibly binds H2, forming Os(H)2(H2)(NO)(P1Pr3) with an unusually high barrier for intramolecular hydride exchange. Under kinetic conditions, protonation of 2 with strong acids follows the selectivity for chloride abstraction. Thermodynamically, protonation at the hydride is preferred, quantitatively producing cationic OsHCl(NO)L2+, isolated and characterized by X-ray diffraction as the BAr4F− salt (7) (ArF=3,5−(CF3)2C6H3). Structures of isoelectronic OsHCl(NO)(PH3)2 and OsHCl(CO)(PH3)2 were optimized with ab initio DFT (Becke3LYP) methods and compared to show the greater unsaturation of the metal in the cationic species. Both complexes, 4a and 7, are highly electrophilic and reversibly coordinate dichloromethane in solution. The observed reactivity patterns of the synthesized unsaturated hydrides are rationalized in terms of the determining influence of the ‘push-pull’ π-stabilization of the metal center.  相似文献   

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