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Query: UMLS:C0026936 (Mycoplasma)
 14,761 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of a purified glycoprotein extract from Klebsiella pneumoniae with non-specific immunostimulating properties (RU 41740) on the development and course of mycoplasma arthritis was investigated. Male A/J mice aged 2-3 months were given RU-41740 either intraperitoneally (i.p.) or orally prior to injection with Mycoplasma arthritidis. RU-41740 injected i.p. at 0.1 mg kg-1 or given orally at 1 mg kg-1 prior to the infection and subsequently on alternate days enhanced the resistance of mice to mycoplasma arthritis (P less than 0.001). Doses of 1 mg kg-1 i.p. or 10 mg kg-1 orally did not modify the course of the arthritis significantly, probably due to immunosuppressive factors from monocytes. It is suggested that RU-41740 protects the mice by stimulating macrophages. This immunostimulant might prove useful in the treatment of mycoplasma diseases, especially in the immunocompromised host.
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PMID:Klebsiella pneumoniae glycoprotein RU-41740 enhances resistance of mice against Mycoplasma arthritidis-induced arthritis. 193 Nov 33

Five strains of Mycoplasma gallisepticum (MG) were examined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blot analysis for the presence of carbohydrate-containing components. Staining with periodic acid-Schiff (PAS) demonstrated carbohydrate components in three of the five strains studied. The PAS-reactive bands counterstained for protein, indicating a possible glycoprotein nature. Western blot analysis using three biotinylated lectin probes demonstrated the presence of additional glycoconjugates in the blot profiles of each MG strain. The carbohydrate specificity of lectin binding was demonstrated by competition experiments using specific sugars. Differences in the number, electrophoretic mobility and the morphology of PAS and lectin reactive bands were reproducible among separate preparations of each MG strain. These findings indicate substantial phenotypic diversity among the five MG strains in their ability to produce or acquire glycoconjugates.
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PMID:Glycoconjugate heterogeneity among five strains of Mycoplasma gallisepticum. 228 23

A 100 kilodalton glycoprotein receptor for Mycoplasma pneumoniae has been isolated from MRC-5 human lung fibroblasts. This receptor, as well as anti-receptor serum, were both capable of inhibiting the attachment of 14C-labelled M. pneumoniae to MRC-5 fibroblasts. The receptor was also capable of inhibiting the attachment of C-labelled M. gallisepticum and M. genitalium, but not M. pulmonis, to MRC-5 fibroblasts. This indicates that a common sequence may exist in these binding proteins of M. pneumoniae, M. genitalium, and M. gallisepticum. This receptor and anti-receptor serum were utilized to probe M. pneumoniae, M. genitalium, and M. gallisepticum for their corresponding binding proteins. A 32 kilodalton protein in M. pneumoniae, a 90 kilodalton protein in M. genitalium and a 139 kilodalton protein in M. gallisepticum were recognized.
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PMID:Identification of Mycoplasma binding proteins utilizing a 100 kilodalton lung fibroblast receptor. 251 89

Mycoplasma pneumoniae, a respiratory pathogen of humans, is the etiologic agent of primary atypical pneumonia. The mycoplasma attaches to the host cell by means of a specialized terminal structure. This structure binds the organism to the corresponding receptor site on the host cell. A glycoprotein receptor site for M. pneumoniae was isolated from MRC-5 human lung fibroblasts. It was isolated from a Triton X-100 extract by column affinity chromatography, utilizing wheat germ agglutinin bound sepharose 6MB. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis revealed it to have an MW of approximately 100 kilodaltons (kDa) and to be composed of subunits of approximately 21 kDa. At a concentration of 56 micrograms/ml, the receptor inhibited the binding of 14C-labeled M. pneumoniae to MRC-5 fibroblasts by 77%. Chemical analysis determined that it does not contain any detectable sialic acid. Knowledge of the biochemical and immunological characteristics of the receptor site are essential to understand the attachment phase of the pathogenic process and to further the development of effective prophylaxis.
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PMID:Characterization of a human lung fibroblast receptor site for Mycoplasma pneumoniae. 311 26

The aim of this study was to investigate whether I antigen occurs in association with Mycoplasma pneumoniae in a form that may be immunogenic during natural infection or experimental immunization. I antigen activity was detected by radioimmunoassay in suspensions of M. pneumoniae MY11965 and in the soluble phase of mycoplasma lysates prepared with Triton X-100. There was evidence for the occurrence of I antigen in at least two macromolecular forms. The first form partitioned in the lipid phase following chloroform-methanol extraction and chromatographed on thin-layer chromatograms as a ceramide decasaccharide. The second form was associated with the residue after lipid extraction and was solubilized by treatment with sodium dodecyl sulfate or pepsin; this component was tentatively designated a glycoprotein or polysaccharide and was not investigated further. In a lipid extract from mycoplasmas that had been surface labeled by the galactose oxidase-NaB3H4 method, two 3H-labeled glycolipids were detected as minor components which chromatographed on thin-layer chromatograms in the region of an authentic I-active ceramide decasaccharide. However, no significant radioactivity was incorporated into glycolipids after metabolic labeling with [3H]glucosamine. These observations suggested that the mycoplasmas contained surface-associated glycolipids with I antigen activity that were of exogenous origin. This was supported by the observations that horse, rabbit, and fetal calf sera contained I antigen activity and that the I antigen activity in M. pneumoniae cultures reflected the levels found in the sera included in the culture media. From rabbit serum, which expressed the highest antigen activity, an I-active glycolipid was isolated that chromatographed as a ceramide decasaccharide. I-active substances passively adsorbed onto M. pneumoniae are potentially immunogenic. However, we consider these unlikely to be the main stimulus for autoantibody production in natural infection, since the autoantibodies elicited are restricted to the I carbohydrate antigen and there is a lack of antibodies to other glycolipids that may be adsorbed from serous and cellular components of the host tissues. In our view, the more likely stimulus is the specific complex formed between the mycoplasma and the sialo-oligosaccharide receptors of the Ii antigen type, as suggested previously.
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PMID:Evidence for occurrence of passively adsorbed I antigen activity on a cultured strain of Mycoplasma pneumoniae. 314 Dec 77

This article is focused on a family of carbohydrate structures which are (a) target antigens of autoantibodies and (b) onco-developmental antigens which change during embryonic development, cell differentiation, maturation and oncogenesis. Among the carrier molecules of these saccharide structures is the receptor for epidermal growth factor. Perturbation of these structures on the isolated receptor enhances autophosphorylation of the receptor glycoprotein. This suggests that the carbohydrate chains may be part of a growth regulatory network which may be 'tuned' or perturbed via interactions with endogenous lectins or by adhesins of infective agents. Certain sialylated forms of these oligosaccharide structures serve as receptors for a pathogen of man, Mycoplasma pneumoniae which, following infection, elicits anti-erythrocyte autoantibodies. These autoantibodies are directed against the backbone domain of the carbohydrate receptor and are therefore anti-receptor antibodies. These observations suggest that complex formation between the adhesins of infective agents and specific saccharides of host-cell membranes may be a 'new' mechanism for eliciting autoantibodies.
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PMID:Significance of carbohydrate components of cell surfaces. 331 6

The whole viable Mycoplasma gallisepticum (strain TT) organisms were found to possess neuraminidase activity with a pH optimum of 5.8 on substrates such as human transferrin, human alpha(1)-glycoprotein, and rabbit serum. The enzyme operated optimally at pH 4.5 when N-acetylneuraminyl-lactose was used as the test substrate.
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PMID:Neuraminidase activity in Mycoplasma gallisepticum. 467 93

A comparison of various in vitro models of respiratory tissue is presented. Tracheal ring explant cultures can be readily infected with M. pneumoniae. A decrease in vigor and extent of ciliary beating becomes apparent 24-48 h after 60-min exposure to 10(7) cfu of mycoplasmas. Cytotoxicity can be substantiated with assays of dehydrogenase activity, ATP content and oxygen uptake. For studies of pathogen attachment, perfusion culture of intact tracheas offers a distinct advantage over tracheal-ring explants. A greater proportion of the pathogen uptake is mediated by specific receptor sites because artificial cut surfaces are eliminated. Such matrix-embed/perfusion cultures have been used to assay the effectiveness of mycoplasma interactions with receptor site preparations. Triton X-100 effectively solubilizes glycoproteins which will bind with M. pneumoniae. Perfusion culture has also been used to study the synthesis and secretion of mucous glycoprotein by the respiratory epithelium.
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PMID:Respiratory tract organ cultures to assay attachment and pathogenicity of mycoplasmas. 642 25

The 250-kDa sialoglycoprotein of bovine erythrocyte membranes, GP-2, has been found to be an exceptionally rich source of branched sialo-oligosaccharides of poly-N-acetyllactosamine (I antigen) type with receptor activity for the human pathogen Mycoplasma pneumoniae. Desialylated GP-2 is the most potent I-active substance thus far tested. Since this glycoprotein is hydrophobic and can be readily re-incorporated into cell membranes, it should be useful in future studies of the mechanism of production of autoantibodies to the I antigen which commonly arise following human infection with M. pneumoniae.
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PMID:Cryptic I antigen activity and Mycoplasma pneumoniae-receptor activity associated with sialoglycoprotein GP-2 of bovine erythrocyte membranes. 643 60

Model systems for the study of mycoplasma infections are available with various degrees of complexity. They offer the advantages of simplicity and control of environmental variables. More significantly, they have a homogeneity of cell type, which is necessary when analyzing the biochemical factors in pathogenicity. Cell cultures of fibroblasts are especially useful in studies of receptor sites. Human lung fibroblasts in monolayer format contain a sialoglycoprotein to which Mycoplasma pneumoniae attaches. Fibroblast membranes are extracted with lithium diiodosalicylate or Triton X-100 to provide a fraction rich in glycoprotein. Polyacrylamide gel electrophoresis revealed less than eight proteins, with the majority of the carbohydrate in a single zone. Autoradiography of gels from fibroblasts grown in radiolabeled medium revealed that this zone also had high concentrations of glucosamine. Detergent extracts competitively inhibited the attachment of M. pneumoniae to fibroblasts. Cultures of fibroblasts also have been used to show that M. pneumoniae disrupts de novo purine synthesis within hours after infection. Monolayers of ciliated respiratory epithelial cells displayed an even distribution of receptor sites over the cell membrane. Intact trachea perfusion cultures were used to establish the pattern of pathogen distribution in upper airways. These in vitro approaches provide valuable insight into the process of mycoplasma attachment and the subsequent metabolic alterations that cause cytotoxicity.
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PMID:In vitro models for host-parasite interactions involving mycoplasmas. 643 79


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