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

Mycoplasma pneumoniae must attach to respiratory tract cells to cause primary atypical pneumoniae. The attachment process involves a receptor site on the external membrane surface of the host cell and a specialized attachment tip on the mycoplasmal cells. Attachment to lung fibroblasts and ciliated tracheal explants is time dependent, with maxima reached in 45-90 min at 37 C. Attachment to ciliated cells is slower, apparently because of continuous ciliary motion. Normally, less than 10% of available mycoplasmas become cell associated in vitro, perhaps because the pathogen must be in a particular growth phase or because only a small fraction of the M. pneumoniae population has complete or effective attachment tips. Mycoplasmas that attach to host cells normally have the constricted attachment tip oriented toward the host cell surface. Mycoplasmas are oriented vertically in cultures of densely ciliated cells, but can lie horizontally alone--and in close apposition to--cell membranes of sparsely ciliated or nonciliated cells. The site to which M. pneumoniae attaches, a sialoglycoprotein, is readily inactivated by neuraminidase, partially sensitive to pronase, and resistant to trypsin. Purified glycoprotein extracts bind to M. pneumoniae.
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PMID:A review of the morphological and biochemical features of the attachment process in infections with Mycoplasma pneumoniae. 681 1

Attachment of Mycoplasma pneumoniae to human WiDr cell culture monolayers was examined by using radiolabeled M. pneumoniae. The amount of attachment was proportional to the density of the WiDr cells and to the concentration of M. pneumoniae in the assay. Saturation of the monolayers was achieved with 40 micrograms of virulent strain M129 per assay, whereas binding of avirulent strain B176 was 70% less than that of strain M129. A competitive attachment inhibition assay was used to measure specific binding component activity. Attachment was inhibited when WiDr cells were pretreated with unlabeled virulent strain M129, whereas avirulent noncytadsorbing strain B176 did not inhibit attachment as well as the virulent strain. A protein-rich extract prepared from virulent, cytadsorbing strains of M. pneumoniae also inhibited attachment. The amount of inhibition was dependent on the amount of extract used, and units for binding component activity in the extract were calculated from the competitive attachment inhibition assays. The competitive attachment inhibition assay was also used to investigate the nature of the receptor site on the WiDr cells. Attachment was inhibited when the radiolabeled M. pneumoniae suspensions were pretreated with human sialoglycoproteins, such as orosomucoid and ceruloplasmin, and bovine gangliosides. These findings support the present concept that the mammalian receptor site for M. pneumoniae is a sialic acid-containing glycoprotein.
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PMID:Mycoplasma pneumoniae attachment: competitive inhibition by mycoplasmal binding component and by sialic acid-containing glycoconjugates. 681 97

Several Mycoplasma and Acholeplasma species chosen at random and solubilized with sodium dodecyl sulphate showed a common periodic acid-Schiff positive band with an apparent molecular weight of about 64 000, when examined by polyacrylamide gel electrophoresis. Another more cathodic minor band was detected in M. hyopneumoniae and M. flocculare. The common periodic acid-Schiff positive band appeared when a precipitate of serum constituents of the uninoculated growth medium after incubation was examined. The minor band was identified as a serum glycoprotein contaminating mycoplasmas grown in the presence of swine serum. We draw attention to the compounds as a possible source of error in serological tests or in the lymphocyte stimulation response. After lithium diiodosalicylate solubilization and aqueous phenol extraction, polyacrylamide gel electrophoresis showed a periodic acid-Schiff positive band in membranes from M. hyopneumoniae (molecular weight 75 000) and M. hyorhinis (molecular weight 80 000), suggesting the presence of a membrane glycoprotein. Such a glycoprotein was absent from A. granularum. Since the common periodic acid-Schiff positive band was not extracted by aqueous phenol, this growth medium constituent did not contaminate the preparations of membrane glycoproteins. However, the minor band was present in glycoprotein preparations of M. hyopneumoniae grown in the presence of swine serum.
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PMID:Growth medium constituents contaminating mycoplasma preparations and their role in the study of membrane glycoproteins in porcine mycoplasmas. 719 Sep 98

An inflammatory toxin was extracted from Mycoplasma bovis with 75 percent aqueous ethanol. The toxin is a complex polysaccharide composed of glucose, glucosamine or galactosamine, and a heptose, is heat-stable, devoid of protein and lipid, and has a molecular weight of 73,000. The holotoxin in the cell membrane is a glycoprotein; however, it is the polysaccharide portion that is toxic. This inflammatory toxin increases vascular permeability and is capable of activating complement. Infusion of 0.9 milligram of toxin into the bovine udder resulted in the characteristic eosinophilic mastitis produced by Mycoplasma bovine.
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PMID:Inflammatory toxin from Mycoplasma bovis: isolation and characterization. 723 96

Rabbit antibodies made to an Epstein-Barr virus (EBV)-associated hydrophobic protein p105 that cross-reacts antigenically with the herpes simplex virus glycoprotein gB inhibited the ability of EBV to induce immunoglobulin synthesis by normal B cells. Sequencing of p105 indicated that it was a keratin-like protein and not encoded by EBV. Analysis of EBV-producing cells with and without mycoplasma indicated that p105 is probably a mycoplasma protein that associates with the EBV virion.
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PMID:The Epstein-Barr virus-associated protein p105 is not encoded by the Epstein-Barr virus genome. 812 34

Serum alpha-1-acid glycoprotein (alpha 1AG) was measured in 212 Landrace White pigs between birth and finishing age. The alpha 1AG level of healthy pigs five to ten months of age was 338 +/- 79 micrograms/mL, and the upper normal limit in mature swine has been established as 500 micrograms/mL. In both specific pathogen-free (SPF) and conventional pigs, the alpha 1AG level within one day of birth was 14,263 +/- 2,393 micrograms/mL, 40 times the normal adult value, but rapidly decreased to 699 +/- 186 micrograms/mL by four weeks of age. In conventional pigs, alpha 1AG began to increase after four weeks, averaged 1,428 micrograms/mL by eight weeks, but gradually decreased to adult levels by 20 weeks of age. In comparison, alpha 1AG of SPF pigs was only 800 micrograms/mL at eight weeks and decreased more rapidly to normal by 16 weeks of age. The conventional pigs had a high incidence of clinical pneumonia and specific antibodies to Actinobacillus pleuropneumoniae and Mycoplasma hyopneumoniae at the age of eight weeks. As the clinical pneumonia disappeared, serum alpha 1AG level also gradually declined. In contrast, SPF pigs had little clinical illness, low alpha 1AG, and little serological evidence of microbial infection. Conventional pigs with nonrespiratory infections, encephalitis, or with hernias had increased alpha 1AG. While the very high alpha 1AG level of the neonatal pig may be due to genetic influences, increases later in life are likely in response to stimuli from its external environment. Monitoring of serum alpha 1AG in several herds aided in the recognition of disease processes and may have potential use in swine herd health management.
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PMID:The influence of age and health status on the serum alpha 1-acid glycoprotein level of conventional and specific pathogen-free pigs. 849 Aug 10

It has been stated that two terminal carbohydrates from polysaccharide complexes which are on the surface of human epithelial tissues, namely, alpha-D-glucose and N-acetylneuramino acid bound with subterminal galactose via alpha 2-->3-bond (NeuAc alpha 2-->3 Gal), may serve receptors for Mycoplasma fermentans adhesion on human epithelial cells. M. fermentans shows high selectivity to these receptors, though very low affinity. The latter, probably, explains why this mycoplasma is able to infect only the limited number of peoples. In the authors' opinion people with the lower content of glucose in urine, as well as those who suffer from diseases associated with hypothalamo-hypophyseal insufficiency are subjected to infection with M. fermentans. People with normal (3.33-5.55 mM) and elevated alpha-D-glucose content in blood and in urine are not susceptible to this mycoplasma. Results of the research carried have shown that alpha-D-glucose solutions of definite concentration may be used to eliminate M. fermentans from the urogenital tract of people who have it. The ability of M. fermentans to discriminate terminal structure of NeuAc alpha 2-->3 Gal provides it with the possibility to adhere human immunodeficiency virus virions on its cells as glycoprotein (gp120) of that virus has among its own oligosaccharides certain glycopolymers of the similar terminal structure. Then M. fermentans transports the virions directly to target cells for this virus. The target cells express receptor CD4 glycolized by oligosaccharides of the mentioned terminal structure. It provides adhesion of the mycoplasma on the receptor.
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PMID:[Carbohydrate receptors for Mycoplasma fermentans adhesion on human epithelial tissues]. 854 67

Proceeding from the structure and function of the shell glycoprotein gp120 of the human immunodeficiency virus (HIV) and receptor glycoprotein CD4 on target cells for this virus, the author assumes that in nature there is genetically determined human resistance to the HIV infection and AIDS. This resistance manifests itself indirectly via products of the glycosylation system and via the composition and order of amino-acid residues in receptor CD4 sites responsible for interaction between the receptor and glycoprotein gp120. The author thinks that people in whom the glycosylation system determines either B(III) or AB(IV) blood groups are potential subjects of the HIV infection. But development of AIDS necessitates some conditions more, one of them is susceptibility of the human organism to be infected with mollicute Mycoplasma fermentans. This mycoplasma is able to recognize terminal NeuAc alpha 2-3 Gal in the composition of oligosaccharides of gp120, which permits it to adhere HIV virions on itself and then to transport them directly to the cells expressing receptor CD4 and having oligosaccharides of the same terminal structure. Oligosaccharides of glycocalyx of the mycoplasma protect it from the action of the human immune system and the mycoplasma, having "transported" HIV virions to target cells combines with membranes of the latter, stimulates formation by them of interleukin-1 and tumour necrosis factor, the known effectors of this virus reproduction. On the basis of all these factors the author identifies four types of human resistance to HIV/AIDS.
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PMID:Molecular biological bases of resistance to HIV/AIDS (the hypothesis with elements of the theory). 854 75

Polyunsaturated fatty acids (PUFA) are immunomodulators, but few studies have examined how these dietary components influence infectious respiratory disease. Groups of nine pigs were fed casein and corn starch-based diets containing 10.5 g/100 g corn oil (CO), linseed oil (LO), menhaden oil (MO), linseed + corn oil (LC, 1:1) and menhaden + corn oil (MC, 1:1). As a methodological control, one group of pigs (n = 15) was fed a commercial ration (control diet; C). Pigs inoculated intratracheally with Mycoplasma hyopneumoniae after 4 wk of consuming the diets were killed 3 wk later. Gross lung lesions in MO-fed pigs were less (P < 0.05) than those in LC- and MC-fed pigs. Pigs fed MO had less peribronchial inflammation (P < 0.05) than all other groups. Gross lung lesions correlated negatively with basal in vitro alveolar macrophage tumor necrosis factor (TNF) production in pigs fed diets that contained negligible levels of (n-3) PUFA (C and CO). Basal macrophage TNF production did not correlate with lung lesion scores for diets containing more (n-3) PUFA than C or CO (LO, MO, LC and MC). For pigs fed the LO, MO, LC and MC diets, mean gross lung lesions increased as the mean ratio of (n-3):(n-6) PUFA in alveolar macrophage lipids decreased. Serum levels of alpha1 acid glycoprotein (AGP) were less (P < 0.05) in pigs fed MO, and there was a rise in mean lung lesions scores for each PUFA-fed group as mean AGP levels increased. These results indicate that dietary PUFA can affect disease pathogenesis and that the (n-3):(n-6) PUFA ratio may modulate the host response.
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PMID:Dietary polyunsaturated fatty acids modulate responses of pigs to Mycoplasma hyopneumoniae infection. 864 26

Mycoplasma pneumoniae infection in the human is often followed by a transient autoimmune hemolytic disorder characterized by high titer autoantibodies to a carbohydrate antigen, the I antigen. Because the major host cell receptor for the Mycoplasma is the sialylated form of this antigen, it is likely that the immunologic disorder is initiated by the microbe-saccharide interaction. Here we review briefly knowledge on the autoantibodies and the structures and distribution of the saccharide antigens and receptors. We discuss possible mechanisms for the triggering of autoantibody production and consider ways in which perturbation of various glycoprotein carriers of the carbohydrate ligands may elicit a variety of pathobiologic responses. We conclude by highlighting ideas on further molecular dissections of the elements of the microbe-host interaction.
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PMID:Carbohydrate recognition by Mycoplasma pneumoniae and pathologic consequences. 887 31


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