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91.
Mycoplasma arthritidis causes arthritis in rodents that resembles human rheumatoid arthritis. It produces a superantigen (MAM) that stimulates production of cytokines by making a bridge between lymphocyte T-cell receptor with the appropriate Vbeta chain, and H-2 1-Ealpha MHC class II molecules. Here we studied MAM-induced nitric oxide (NO) production in mouse peritoneal macrophages and found that it was: (1) time and concentration dependent, (2) possibly derived from inducible NOS synthase since it was reduced significantly by amino guanidine pretreatment, (3) restricted to H-2(K) (C3H/HePas and C3H/HeJ) and H-2(d) strains (BALB/c), (4) independent of TLR4 signaling since the coisogenic strains C3H/HePas and C3H/HeJ (TLR4 deficient) produced similar levels of NO following MAM stimulation, (5) potentiated by lipopolysaccharide, and (6) dependent on the presence of nonadherent peritoneal cells. Neutralization of interferon-gamma (IFNgamma in the peritoneal cell cultures with monoclonal antibodies abolished MAM-induced NO production. Addition of rIFNgamma to the adherent cells substituted the nonadherent cells for MAM-induced NO production. A macrophage cell line, J774A.1 (H-2(d)), also produced NO upon MAM stimulation but only when BALB/c spleen lymphocytes were added. Thus, in murine macrophages, MAM induces NO production that is dependent on signaling through MHC class II molecules and IFNgamma but independent of TLR4 expression.  相似文献   
92.
通过实验动物模型探讨肺炎支原体感染动物肺泡灌洗液中特异抗原检出率的动态变化,为肺炎支原体感染的临床诊断提供理论依据。小鼠经鼻自然感染肺炎支原体,分别采集感染后不同时间点小鼠的支气管灌洗液,应用量子点标记肺炎支原体P1蛋白抗体,直接免疫荧光法检测感染鼠肺泡灌洗液中肺炎支原体P1特异抗原,同时通过PCR检测肺组织肺炎支原体DNA及肺组织病理切片观察肺部炎性变化确定小鼠感染。结果显示,感染鼠肺炎支原体特异抗原在感染后第3天检出阳性率为75%,第7天达高峰为83%,之后随病程延长,抗原检测的阳性率逐渐下降,在感染后第14、21天检出阳性率分别为58%和25%。肺炎支原体特异抗原在感染早期检出率高。应用量子点标记肺炎支原体P1蛋白抗体,直接免疫荧光法检测肺炎支原体特异抗原可应用于肺炎支原体感染的早期诊断。  相似文献   
93.
目的 分析抚顺地区泌尿生殖道解脲支原体和人型支原体感染情况及药敏情况。方法 采用支原体培养、鉴定、药敏一体化试剂盒对710名患者进行解脲支原体(Uu)和人型支原体(Mh)检测和其对9种抗菌药物的药敏试验。结果 710名患者中共检出支原体感染者200名,阳性率为28.17%。其中Uu 140名(19.71%),Mh 12名(1.69%),Uu+Mh混合感染48名(6.76%)。药敏结果表明,支原体对强力霉素、美满霉素和克拉霉素敏感率高,分别为95.71%,98.57%和91.42%。结论 抚顺地区支原体感染发病率较高,以单纯Uu感染为主,美满霉素是治疗支原体感染的首选药物。  相似文献   
94.
为探讨血小板源性生长因子 - BB(PDGF- BB)在肺炎支原体反复肺感染导致肺间质纤维化的发病机制中的作用 ,作者于 2 4周内给大鼠反复 9次吸入肺炎支原体复制慢性肺感染模型。随后用 PDGF- BB单克隆抗体按 SABC法行免疫组织化学染色和定量图像分析 ,以观察肺组织 PDGF- BB蛋白质水平表达的变化。结果显示 :(1)感染组动物 (n=4)支气管肺泡灌洗液肺炎支原体 - PCR检测均为阳性 ,而对照组 (n=4)和感染加红霉素治疗组动物 (n=4)均为阴性 (P<0 .0 5 ) ;三组动物的支气管和肺组织常规细菌培养结果均为阴性 ;感染组动物透射电镜检查见肺泡间隔增宽 ,其中有较多胶原纤维堆积 ,其余两组则未见明显异常。 (2 )感染组动物肺间质结缔组织内、支气管壁和小血管壁内可见较强的 PDGF- BB阳性染色 ,其积分光密度为 37.90± 10 .14(n=4) ,显著高于对照组者 (7.5 4± 1.98,n=4,P<0 .0 5 )和感染加红霉素治疗组者 (10 .90± 3.30 ,n=4,P<0 .0 5 )。提示肺炎支原体反复肺感染的 PDGF- BB蛋白质水平表达增加 ,可能参与肺间质纤维化的发病过程  相似文献   
95.
96.
The ribosomal protein gene cluster of Mycoplasma capricolum   总被引:15,自引:0,他引:15  
Summary The DNA sequence of the part of the Mycoplasma capricolum genome that contains the genes for 20 ribosomal proteins and two other proteins has been determined. The organization of the gene cluster is essentially the same as that in the S10 and spc operons of Escherichia coli. The deduced amino acid sequence of each protein is also well conserved in the two bacteria. The G+C content of the M. capricolum genes is 29%, which is much lower than that of E. coli (51%). The codon usage pattern of M. capricolum is different from that of E. coli and extremely biased to use of A and U(T): about 91% of codons have A or U in the third position. UGA, which is a stop codon in the universal code, is used more abundantly than UGG to dictate tryptophan.  相似文献   
97.
The in vitro stability (temperature, pH, and trypsin) of Mycoplasma hyopneumoniae antigen (MHA) with and without enteric-coated microencapsulation were examined. Microencapsulation of MHA with cellulose acetate phthalate (CAP) is an effective route to produce enteric-coated vaccine microspheres for oral administration. The effect of temperature on the rate of inactivation of MHA was studied by exposing MHA to various temperatures, such as 25, 37, 50 and 60 degrees C. The MHA microspheres were thermally more stable than that of the unencapsulated MHA. The kinetic parameters were observed to follow an Arrhenius-type temperature dependence. The MHA microspheres were also more stable in acidic regions (pH 1.2-4.0) than that of the free one. The enteric-coated MHA microspheres exhibited an excellent enteric function to prevent acidic degradation. A model similar to the well-known Michaelis-Menten equation was formulated to describe the effect of trypsin on the antigenic degradation of MHA. The equilibrium constant K(A) and the maximum reaction velocity V(m) were obtained from experimental data for both free and microencapsulated MHA. Both K(A) and V(m) values of the microencapsulated MHA were smaller than that of the free one, i.e., the resistance to proteolytic enzyme such as trypsin was enhanced by microencapsulation. The storage stability of enteric-coated MHA microspheres has been satisfactorily prolonged that they could preserve more than 90% of original antigenicity after 30 days, and over 80% of antigenicity of MHA was retained in the microspheres for 95 days when it was stored at 4 degrees C.  相似文献   
98.
Physical mapping of the Mycoplasma capricolum genome   总被引:7,自引:0,他引:7  
A physical map of Mycoplasma capricolum ATCC 27343 genome was constructed, based on estimation of the restriction fragment sizes by pulse-field electrophoresis. The linkage order of restriction fragments was determined by two-dimensional electrophoresis of partial and complete single digests and complete double digests and by Southern hybridization analysis. The genome size was established at 1155.5 kb, and 26 cleavage sites for 7 endonucleases were assigned to the map.  相似文献   
99.
Two cholesterol pools in Acholeplasma laidlawii membranes   总被引:2,自引:0,他引:2  
Cholesterol exchange kinetics between [14C]cholesterol-labeled Acholeplasma laidlawii and Mycoplasma gallisepticum cells and phosphatidylcholine-cholesterol vesicles followed a biphasic curve, with faster exchange rates for A. laidlawii. The same biphasic curve was obtained with isolated membranes. Cholesterol exchange between lipid vesicles and A. laidlawii cells depleted of phospholipids by phospholipase A2, fitted a monophasic linear curve. The data support the hypothesis that the biphasic cholesterol exchange kinetics do not result from the transbilayer distribution of cholesterol, but reflect the presence in the membrane of two cholesterol pools associated with lipids of high and low affinity for cholesterol.  相似文献   
100.
Superspreading, the phenomenon where a small proportion of individuals contribute disproportionately to new infections, has profound effects on disease dynamics. Superspreading can arise through variation in contacts, infectiousness or infectious periods. The latter has received little attention, yet it drives the dynamics of many diseases of critical public health, livestock health and conservation concern. Here, we present rare evidence of variation in infectious periods underlying a superspreading phenomenon in a free‐ranging wildlife system. We detected persistent infections of Mycoplasma ovipneumoniae, the primary causative agent of pneumonia in bighorn sheep (Ovis canadensis), in a small number of older individuals that were homozygous at an immunologically relevant genetic locus. Interactions among age‐structure, genetic composition and infectious periods may drive feedbacks in disease dynamics that determine the magnitude of population response to infection. Accordingly, variation in initial conditions may explain divergent population responses to infection that range from recovery to catastrophic decline and extirpation.  相似文献   
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