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61.
Antigens of virulent and attenuated Rickettsia tsutsugamushi. 总被引:1,自引:0,他引:1
We studied the antigens present in L929 mouse fibroblast or rabbit testicular cells, which had been infected or not with a prototype strain of Rickettsia tsutsugamushi, the causal agent of scrub typhus, and its attenuated variant. Immunoblotting revealed four antigens, designated 1, 1a, 2 and 3, which appeared to be specifically associated with infection with this organism. Antigens 1 and 1a had similar mol. wt of about 60 kD and antigen 2 and 3 had mol. wts of 45 kD and 28 kD respectively. Whereas antigen 1a, 2 and 3 were common to infection with either the virulent or the attenuated strains of the organism, antigen 1 was only detected in cells infected with the virulent strain and was reactive only with the antiserum raised against cells infected with that strain. In addition, two antigens were also detected by crossed immunoelectrophoresis, one of which was similarly associated with infection with the virulent strain as antigen 1, while the other was common to infection with either of the strains. It seems that the antigenic cross reaction between the two strains may account, in part at least, for the protection of mice against infection with the virulent strain afforded by the attenuated strain, while the loss or modification of antigen 1 might be associated with attenuation of the organism with respect to its virulence to mice. 相似文献
62.
Effect of cyclic adenosine 3'',5''-monophosphate antagonists on endotoxin-induced inhibition of human neutrophil chemotaxis. 下载免费PDF全文
We reported previously that Escherichia coli endotoxin inhibited human neutrophil chemotaxis toward C5a. This effect of endotoxin was antagonized by anti-inflammatory steroids. We now report that dibutyryl cyclic adenosine 3',5'-monophosphate, prostaglandin E1, isoproterenol, and cholera toxin also antagonize the suppression of chemotaxis by endotoxin. Each compound inhibited the effect of endotoxin in a dose-dependent fashion. To be effective, each compound except cholera toxin had to be present at the time of endotoxin challenge. Furthermore, propranolol blocked the protective effect of isoproterenol against endotoxin but not the protective effect of dibutyrl cyclic adenosine 3',5'-monophosphate or prostaglandin E1. Dibutyryl cyclic guanosine 3',5'-monophosphate, adenosine 5'-monophosphate, phenylephrine, prostaglandin F2 alpha, and carbachol did not modify the suppression of chemotaxis by endotoxin. Anti-inflammatory steroids and dibutyryl cyclic adenosine 3',5'-monophosphate are thought to stabilize phospholipids in certain cell membranes. This phospholipid-stabilizing action may contribute, at least in part, to the protective effect against endotoxin-mediated suppression of neutrophil chemotaxis. 相似文献
63.
Hepatocytes are anchorage-dependent cells sensitive to microenvironment; the control of the physicochemical properties of the extra-cellular matrices may be useful to the maintenance of hepatocyte functions in vitro for various applications. In a microcapsule-based 3-D hepatocyte culture microenvironment, we could control the physical properties of the collagen nano-fibres by fine-tuning the complex-coacervation reaction between methylated collagen and terpolymer of hydroxylethyl methacrylate-methyl methacrylate-methylacrylic acid. The physical properties of the nano-fibres were quantitatively characterized using back-scattering confocal microscopy to help optimize the physical support for hepatocyte functions. We further enhanced the chemical properties of the collagen nano-fibres by incorporating galactose onto collagen, which can specifically interact with the asialoglycoprotein receptor on hepatocytes. By correlating a range of collagen nano-fibres of different physicochemical properties with hepatocyte functions, we have identified a specific combination of methylated and galactosylated collagen nano-fibres optimal for maintaining hepatocyte functions in vitro. A model of how the physical and chemical supports interplay to maintain hepatocyte functions is discussed. 相似文献
64.
Interaction of plasma fibronectin (pFN) with membranous constituents of peritoneal exudate cells and pulmonary macrophages 总被引:2,自引:0,他引:2
The prominent role of plasma fibronectin (pFN) in the host defense system as an opsonin for gelatin (collagen)-coated colloids has been established. In the present study we investigated the interaction of pFN and membrane isolates from cells devoid of collagen, as well as several tissues. In a liver slice assay system it was shown that subcellular membrane fractions from lung macrophages, peritoneal exudate cells, spleen, tests, and liver were able to competitively inhibit the pFN-mediated uptake of 125I-gelatin coated latex beads (gLtx) at low concentrations. Endocytosis of 125I-labeled membrane isolates by macrophage monolayers was also promoted by addition of pFN. In an attempt to characterize the membrane component(s) interacting with pFN, it was found that mild extraction procedure with 1 M KBr could release a significant amount of this inhibitory activity. Further studies demonstrated that the agent(s) responsible for inhibition of gLtx uptake was heat sensitive, not altered by trypsin treatment, and did not contain actin, a protein known to interact with pFN. This work indicates that pFN interacts specifically with an as yet unknown membrane component(s) and that such interaction will promote clearance of cellular debris by macrophages. This suggests that pFN may be an important opsonin for the reticuloendothelial system in clearance of collagenous and noncollagenous cellular debris once they are exposed to interact with it. 相似文献
65.
J Anthony R Near S L Wong E Iida E Ernst M Wittekind E Haber S C Ng 《Molecular immunology》1992,29(10):1237-1247
We have created a bacterial expression-export system and have used it to express (14 mg l-1) the variable region fragment (Fv) of an anti-digoxin antibody (26-10) in Escherichia coli. The expression-export plasmid contains a T7 promoter and the E. coli signal sequences ompA [Movva et al., J. biol. Chem. 255, 27-29 (1980)] and phoA [Inouye et al., J. Bacteriol. 149, 434-439 (1982)] fused to heavy chain (VH) and light chain (VL) variable region sequences to generate an artificial cistron. The 26-10 Fv protein made using this system was soluble, unlike many other expression systems which produce insoluble proteins in the form of inclusion bodies. The 26-10 VH and VL proteins were cleaved at their mature N-termini and exported into the bacterial periplasm where they could be easily extracted and affinity purified on ouabain-Sepharose. 26-10 Fv bound to digoxin with similar affinity and specificity as the whole 26-10 antibody (Ka for Fv, 1.3 x 10(9) M-1, Ka for IgG, 7 x 10(9) M-1). 26-10 Fv appears to be remarkably stable in comparison with other Fv fragments. The half-life for chain dissociation of 26-10 Fv was 48 hr compared to the reported 1.5 hr half-life of McPC603 Fv. We present the proton NMR spectra of the 26-10 Fv as preliminary evidence that this expression-export system can be used to facilitate the analysis of the solution structure of 26-10 Fv by NMR. 相似文献
66.
Pulmonary pathological features in coronavirus associated severe acute respiratory syndrome (SARS) 总被引:5,自引:0,他引:5
Tse GM To KF Chan PK Lo AW Ng KC Wu A Lee N Wong HC Mak SM Chan KF Hui DS Sung JJ Ng HK 《Journal of clinical pathology》2004,57(3):260-265
BACKGROUND: Severe acute respiratory syndrome (SARS) became a worldwide outbreak with a mortality of 9.2%. This new human emergent infectious disease is dominated by severe lower respiratory illness and is aetiologically linked to a new coronavirus (SARS-CoV). METHODS: Pulmonary pathology and clinical correlates were investigated in seven patients who died of SARS in whom there was a strong epidemiological link. Investigations include a review of clinical features, morphological assessment, histochemical and immunohistochemical stainings, ultrastructural study, and virological investigations in postmortem tissue. RESULTS: Positive viral culture for coronavirus was detected in most premortem nasopharyngeal aspirate specimens (five of six) and postmortem lung tissues (two of seven). Viral particles, consistent with coronavirus, could be detected in lung pneumocytes in most of the patients. These features suggested that pneumocytes are probably the primary target of infection. The pathological features were dominated by diffuse alveolar damage, with the presence of multinucleated pneumocytes. Fibrogranulation tissue proliferation in small airways and airspaces (bronchiolitis obliterans organising pneumonia-like lesions) in subpleural locations was also seen in some patients. CONCLUSIONS: Viable SARS-CoV could be isolated from postmortem tissues. Postmortem examination allows tissue to be sampled for virological investigations and ultrastructural examination, and when coupled with the appropriate lung morphological changes, is valuable to confirm the diagnosis of SARS-CoV, particularly in clinically unapparent or suspicious but unconfirmed cases. 相似文献
67.
Xiao Y Zhang Wing Y Chan Bruce M Whitney Dai M Fan John H S Chow Yong Liu Enders K W Ng Sheung C S Chung 《Diagnostic molecular pathology》2002,11(3):135-139
Helicobacter pylori (HP) infection induces expression of IL-8 and IL-10 in benign gastric epithelium. This study compared the expression of cytokines in CD4+ and CD8+ lymphocyte subsets of peripheral blood lymphocytes (PBL), benign mucosal lymphocytes (ML), and tumor infiltrative lymphocytes (TIL) as well as in the benign and malignant epithelial cells of the same patient, with respect to the presence of HP infection, lymph node metastases, and tumor histologic type. The mRNA of the cytokines was measured by a semiquantitative RT-PCR method. The levels were ranked and compared using the Wilcoxon sign-ranked test. Compared with CD8+ ML, the CD8+ TIL expresses higher levels of IL-6 and IL-8 but lower level of IL-4 in patients with lymph node metastases. In patients with HP infection, expression of IL-8 and IL-10 was higher in the gastric carcinoma cells than in the benign epithelial cells while expression of IL-6 and IL-8 were higher in CD8+ TIL than CD8+ ML. Overexpression of IL-8 in HP associated gastric carcinomas suggested that they might have arisen from HP-infected epithelial cells. 相似文献
68.
Ng PS Chan AS Sin WK Tang LC Cheung KB Yuen PM 《Human reproduction (Oxford, England)》2001,16(1):31-35
Postpartum haemorrhage accounts for nearly 28% of maternal mortality in developing countries. Syntometrine is an effective and commonly used oxytocic in preventing postpartum haemorrhage, but it requires a controlled storage environment and i.m. administration. Misoprostol is an orally active uterotonic agent. A total of 2058 patients having a singleton pregnancy, low risk for postpartum haemorrhage and vaginal delivery were randomized to receive either 1 ml syntometrine or 600 microgram misoprostol for the management of the third stage of labour. There were no significant differences between the two groups in the mean blood loss, the incidence of postpartum haemorrhage and the fall in haemoglobin concentration. The need for additional oxytocic injection was significantly higher in the misoprostol group [relative risk (RR) 1.62, 95% confidence interval (CI) 1.34-1.96], but that of manual removal of placenta was reduced (RR 0.29, 95% CI 0.09-0.87). Shivering and transient pyrexia were more common in the misoprostol group. Oral misoprostol might be used in the management of the third stage, especially in situations where the use of syntometrine is contraindicated and facilities for storage and parenteral administration of oxytocics are limited. 相似文献
69.
Flagella as a potential marker for Campylobacter jejuni strains associated with Guillain-Barré syndrome 总被引:2,自引:0,他引:2
Campylobacter jejuni recovered from patients with Guillain-Barré syndrome (GBS) in different geographical locations and bearing different heat-labile and heat-stable antigens were found to have identical amino acid sequences in their flagellar flaA short variable region, suggesting that it may be a potentially useful marker for GBS association. 相似文献
70.
Hurley CK Steiner N Gans CP Kosman C Mitton W Koester R Jones P Edson S Rizzuto G Hartzman RJ Ng J Rodriguez-Marino SG 《Tissue antigens》2001,57(5):474-477
Twelve new B*15 alleles are described. All of the known B*15 alleles are divided into subgroups based on serologic assignments and/or nucleotide sequence polymorphisms. These groups might be used as a reference for DNA-based testing at an intermediate (i.e. "serologic") level of resolution. 相似文献