Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0021311 (Infection)
 38,178 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Infections due to Yersinia enterocolitica are usually limited to the bowel. When infection is generalized, the role of iron overload and iron chelation has been discussed. We report the case of a 55 year-old patient with sideroblastic anemia who received repetitive transfusions and deferoxamine for 4 years and heme arginate for 2 months, and who was admitted in our institution for Yersinia enterocolitica sepsis. Treatment by third-generation cephalosporins and aminoglycosides has allowed favorable outcome.
 ...
PMID:[Yersinia enterocolitica septicemia, iron overload and deferoxamine]. 748 Nov 60

The Yersinia pseudotuberculosis inv gene encodes invasin, a 103-kDa outer membrane protein allowing bacteria to penetrate mammalian cells. This protein is produced in vitro at below 30 degrees C. In this work, we studied the antibody response against invasin in humans suffering from yersiniosis and in mice orally infected with a virulent strain of Y. pseudotuberculosis. Infection with enteropathogenic Yersinia strains did not induce either a systemic or a gut antibody response to invasin. Our results suggest that the inv gene is not expressed in the gut at 37 degrees C and, therefore, that invasin is not present to the immune system when microorganisms multiply in the host tissues.
 ...
PMID:Lack of antibody response to invasin in humans with yersiniosis. 749 52

Outer membrane protein YadA, Yersinia adhesin, is one of the plasmid-encoded virulence factors of yersiniae. YadA protects bacteria against host defense through several different mechanisms. One important role of YadA is to mediate binding to several collagen types. Our recent study revealed that a yadA null mutant of Yersinia enterocolitica serotype O:8 has a drastically reduced arthritogenic capacity when injected intravenously into Lewis rats. To further characterize the arthritogenic role of YadA, we repeated the rat experiments with strain Y. enterocolitica O:8/pYV082; this strain expresses a YadA deletion derivative lacking 22 amino acids from the amino-terminal hydrophobic region and does not bind to collagen. Y. enterocolitica O:8/pYV082 induced arthritis in 5 to 14% of rats inoculated with arthritogenic doses, whereas the arthritis incidence with the wild-type parent strain was 65%. The parent strain was slightly more virulent than Y. enterocolitica O:8/pYV082, as determined by rat mortality. It also frequently induced skin abscesses, whereas Y. enterocolitica O:8/pYV082 did not. Infection kinetics in spleen and mesenteric lymph nodes were about the same with both of the bacterial strains used, and the same was true of the Yersinia-specific antibody response. Altogether, these results suggest that YadA-mediated collagen binding contributes to the arthritogenicity of Y. enterocolitica O:8.
 ...
PMID:Role of YadA-mediated collagen binding in arthritogenicity of Yersinia enterocolitica serotype O:8: experimental studies with rats. 762 53

Salmonellae possess the ability to adhere to and invade macrophages and in so doing trigger a number of intracellular events that are associated with cellular activation. As an initial approach to defining the mechanisms by which invasive salmonellae alter macrophage function, we have explored the impact of Salmonella infection on the production of human immunodeficiency virus (HIV) in U1 cells, a promonocytic cell line latently infected with the virus. Infection of U1 cells with a pathogenic strain of Salmonella enteritidis resulted in a marked induction of macrophage activation and HIV production. The stimulatory effect of salmonellae was mediated by signals other than lipopolysaccharide. Salmonella mutants with specific defects in invasion or intracellular survival were markedly less effective in the induction of HIV production. In contrast to S. enteritidis, strains of Yersinia enterocolitica, Legionella pneumophila, and Escherichia coli did not induce HIV production. However, all of these bacteria induced comparable levels of gene expression mediated by the HIV long terminal repeat. The results of this study are consistent with the notion that invasive salmonellae possess the ability to activate the macrophage by at least one mechanism that is not shared with several other species of gram-negative bacteria. Furthermore, the expression of this unique property is maximal with Salmonella strains that are not only invasive but also capable of prolonged survival within the macrophage. Our results indicate that the U1 cell line may be a very useful model system with which to examine the biochemical pathways by which internalized salmonellae modulate the activation state of the macrophage.
 ...
PMID:Regulation of macrophage activation and human immunodeficiency virus production by invasive Salmonella strains. 772 90

Tyrosine phosphorylation is an important component of the signaling pathways responsible for the activation of the macrophage respiratory burst. Because the virulence plasmid of Yersinia enterocolitica encodes a phosphotyrosine phosphatase, YopH, it is possible that the pathogenic strategy of Y. enterocolitica involves the disruption of tyrosine phosphorylation in the macrophage leading to inhibition of respiratory burst activity. We have investigated the effects of Yersinia infection on tyrosine phosphorylation and respiratory burst activity in murine bone marrow-derived macrophages. Infection of macrophages with virulent [Ye(pYV+)] but not avirulent [Ye(pYV-)] strains of Y. enterocolitica was found to suppress both tyrosine phosphorylation and respiratory burst activity in response to zymosan. Mutational inactivation of YopH reversed the suppressive effect of Ye(pYV+) on zymosan-induced tyrosine phosphorylation, indicating that YopH is responsible for the dephosphorylation of macrophage phosphotyrosine-containing proteins observed in macrophages infected with the virulent strain of Y. enterocolitica. In contrast, mutational loss of YopH failed to reverse the inhibitory effect of Ye(pYV+) on the zymosan-triggered respiratory burst. We conclude that the inhibition of the macrophage respiratory burst by Y. enterocolitica involves a plasmid-encoded virulence protein(s) other than, or in addition to, YopH.
 ...
PMID:Role of YopH in the suppression of tyrosine phosphorylation and respiratory burst activity in murine macrophages infected with Yersinia enterocolitica. 779 Jul 80

Pathogenic bacteria that penetrate the intestinal epithelial barrier stimulate an inflammatory response in the adjacent intestinal mucosa. The present studies asked whether colon epithelial cells can provide signals that are important for the initiation and amplification of an acute mucosal inflammatory response. Infection of monolayers of human colon epithelial cell lines (T84, HT29, Caco-2) with invasive strains of bacteria (Salmonella dublin, Shigella dysenteriae, Yersinia enterocolitica, Listeria monocytogenes, enteroinvasive Escherichia coli) resulted in the coordinate expression and upregulation of a specific array of four proinflammatory cytokines, IL-8, monocyte chemotactic protein-1, GM-CSF, and TNF alpha, as assessed by mRNA levels and cytokine secretion. Expression of the same cytokines was upregulated after TNF alpha or IL-1 stimulation of these cells. In contrast, cytokine gene expression was not altered after infection of colon epithelial cells with noninvasive bacteria or the noninvasive protozoan parasite, G. lamblia. Notably, none of the cell lines expressed mRNA for IL-2, IL-4, IL-5, IL-6, IL-12p40, IFN-gamma, or significant levels of IL-1 or IL-10 in response to the identical stimuli. The coordinate expression of IL-8, MCP-1, GM-CSF and TNF alpha appears to be a general property of human colon epithelial cells since an identical array of cytokines, as well as IL-6, also was expressed by freshly isolated human colon epithelial cells. Since the cytokines expressed in response to bacterial invasion or other proinflammatory agonists have a well documented role in chemotaxis and activation of inflammatory cells, colon epithelial cells appear to be programmed to provide a set of signals for the activation of the mucosal inflammatory response in the earliest phases after microbial invasion.
 ...
PMID:A distinct array of proinflammatory cytokines is expressed in human colon epithelial cells in response to bacterial invasion. 1113 75

Suppression of host-cell-mediated immunity is a hallmark feature of Yersinia pseudotuberculosis infection. To better understand this process, the interaction of Y. pseudotuberculosis with macrophages and the effect of the virulence plasmid-encoded Yersinia tyrosine phosphatase (YopH) on the oxidative burst was analyzed in a chemiluminescence assay. An oxidative burst was generated upon infection of macrophages with a plasmid-cured strain of Y. pseudotuberculosis opsonized with immunoglobulin G antibody. Infection with plasmid-containing Y. pseudotuberculosis inhibited the oxidative burst triggered by secondary infection with opsonized bacteria. The tyrosine phosphatase activity of YopH was necessary for this inhibition. These results indicate that YopH inhibits Fc receptor-mediated signal transduction in macrophages in a global fashion. In addition, bacterial protein synthesis was not required for macrophage inhibition, suggesting that YopH export and translocation are controlled at the posttranslational level.
 ...
PMID:Inhibition of the Fc receptor-mediated oxidative burst in macrophages by the Yersinia pseudotuberculosis tyrosine phosphatase. 782 39

Virulent strains of Yersinia pseudotuberculosis and Y. enterocolitica cultured at 10 degrees C were studied with respect to their interaction with cultured fish cells. Infection with Yersinia at 25 degrees C resulted in the formation of pseudopodia and the adherence of bacteria to the cell surface. The adherent bacteria were ingested 2 h after infection. Yersinia was found to be cytotoxic for the cells and the intracellular bacteria seemed to reside in phagosomes and were found in stages of division but were never observed in the nucleus.
 ...
PMID:Interaction between Yersinia pseudotuberculosis and Y. enterocolitica and fish cells. 783 93

Pathogenic bacteria of the genus Yersinia release in vitro a set of antihost proteins called Yops. Upon infection of cultured epithelial cells, extracellular Yersinia pseudotuberculosis transfers YopE across the host cell plasma membrane. To facilitate the study of this translocation process, we constructed a recombinant Yersinia enterocolitica strain producing YopE fused to a reporter enzyme. As a reporter, we selected the calmodulin-dependent adenylate cyclase of Bordetella pertussis and we monitored the accumulation of cyclic AMP (cAMP). Since bacteria do not produce calmodulin, cyclase activity marks the presence of hybrid enzyme in the cytoplasmic compartment of the eukaryotic cell. Infection of a monolayer of HeLa cells by the recombinant Y. enterocolitica strain led to a significant increase of cAMP. This phenomenon was dependent not only on the integrity of the Yop secretion pathway but also on the presence of YopB and/or YopD. It also required the presence of the adhesin YadA at the bacterial surface. In contrast, the phenomenon was not affected by cytochalasin D, indicating that internalization of the bacteria themselves was not required for the translocation process. Our results demonstrate that Y. enterocolitica is able to transfer hybrid proteins into eukaryotic cells. This system can be used not only to study the mechanism of YopE translocation but also the fate of the other Yops or even of proteins secreted by other bacterial pathogens.
 ...
PMID:Translocation of a hybrid YopE-adenylate cyclase from Yersinia enterocolitica into HeLa cells. 788 36

Many of the feline zoonoses occur more frequently in veterinary personnel owing to their direct contact with cats and the potential for exposure to infected body tissue or fluids. Infection of humans with Afipia felis, Yersinia pestis, Francisella tularensis, and other aerobic/anaerobic bacteria may cause great discomfort and in some situations terminal illness. Although many systemic fungal agents infect humans and cats, only Sporothrix schenckii has been shown to infect humans following direct exposure to infected cats. Various parasites, enteric protozoans and bacteria, and Toxoplasma gondii infections also may cause significant human illness. Therefore, routine handling of cats may expose human personnel in a veterinary facility to an array of important or emerging feline-associated human illnesses that occur in the United States.
 ...
PMID:Feline zoonotic diseases. 842 89


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>