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Query: UMLS:C0014118 (endocarditis)
 15,629 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Human rheumatoid factors are antibodies of IgG, IgA, or IgM class that show reactions with antigenic determinants present on other immunoglobulin molecules. The most commonly measured rheumatoid factor relates to the 19S IgM type, which reacts by agglutination of latex particles coated with 7S IgG and is often measured in the standard latex fixation test. Approximately 65 to 70 per cent of patients with rheumatoid arthritis show positive serologic tests for rheumatoid factor; however, a number of other chronic disease conditions are also associated with positive rheumatoid factor reactions, including infective endocarditis, sarcoidosis, leprosy, and other hyperglobulinemic conditions. Although extensive serologic and immunochemical studies have identified a number of specific antigenic structural sites on immunoglobulin molecules that react with rheumatoid factors, recent studies have shown that a certain proportion of such antibodies may show cross-reactivity with DNA-histone complexes as well. It is still not entirely clear how rheumatoid factors fit into the pathogenesis of rheumatoid arthritis itself.
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PMID:Symposium on the immunodiagnosis of rheumatic and related diseases, Part II. Rheumatoid factors. 618 75

Streptococcus is the dominant bacterial genus in the human oral cavity and a leading cause of infective endocarditis. Streptococcus sanguinis belongs to the mitis group of streptococci and produces hydrogen peroxide (H2O2) by the action of SpxB, a pyruvate oxidase. In this study, we investigated the involvement of SpxB in survival of S. sanguinis in human blood and whether bacterial H2O2 exhibits cytotoxicity against human neutrophils. Results of a bactericidal test with human whole blood revealed that the spxB mutation in S. sanguinis is detrimental to its survival in blood. When S. sanguinis strains were exposed to isolated neutrophils, the bacterial survival rate was significantly decreased by spxB deletion. Furthermore, human neutrophils exposed to the S. sanguinis wild-type strain, in contrast to those exposed to an spxB mutant strain, underwent cell death with chromatin de-condensation and release of web-like extracellular DNA, reflecting induction of neutrophil extracellular traps (NETs). Since reactive oxygen species-mediated NET induction requires citrullination of arginine residues in histone proteins and subsequent chromatin de-condensation, we examined citrullination levels of histone in infected neutrophils. It is important to note that the citrullinated histone H3 was readily detected in neutrophils infected with the wild-type strain, as compared to infection with the spxB mutant strain. Moreover, decomposition of streptococcal H2O2 with catalase reduced NET induction. These results suggest that H2O2 produced by S. sanguinis provokes cell death of neutrophils and NET formation, thus potentially affecting bacterial survival in the bloodstream.
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PMID:Streptococcus sanguinis induces neutrophil cell death by production of hydrogen peroxide. 2822 25