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

The beneficial effects of polynuclear eosinophils (PE) are well known. However, under certain circumstances, PE can be harmful. The heart is a prime target for PE toxicity which is due to release of basic proteins by eosinophils including major basic protein, cationic protein, and peroxidase. The most common manifestation of PE toxicity is chronic parietal endocarditis (CPE) which regroups two entities: Loeffler's fibroplastic endocarditis and Davies' endomyocardial fibrosis. Loeffler's fibroplastic endocarditis occurs mainly in temperate climates. Patients present high, persistent eosinophil levels similar to those observed in essential hypereosinophilic syndrome (EHS) or Chusid syndrome. Davies' endomyocardial fibrosis occurs in tropical countries where eosinophilic helminthiasis are endemic. The incidence of eosinophilic myocarditis (EM) is low but probably underestimated. EM can be observed in any case involving PE and has been described in many cases of drug-induced atopy, in Churg and Strauss syndrome, and in EHS. The most common cause of death is short-term occurrence of cardiogenic shock or dilated hypokinetic cardiomyopathy. Some patients have been successfully treated by early, intensive corticosteroid therapy and/or heart transplantation. The nosological classification of EM and CPE remains controversial. The two disorders may form a continuum with CPE as the second phase. Other authors have suggested that EM and CPE result from the action of PE on two distinct targets, i.e. endothelial cells for EM and myocytes for CPE. In the future, it may be possible to identify subjects with a predisposition to PE-induced heart disease by studying of genes coding for interleukins (IL-5, IL-4, IL-3) and GM-CSF in the 5q31-q33 region of chromosome 5.
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PMID:[The heart and the eosinophil]. 1041 Mar 66

Staphylococcus epidermidis is one of the most common causes of infections of prosthetic heart valves (prosthetic valve endocarditis [PVE]) and an increasingly common cause of infections of native heart valves (native valve endocarditis [NVE]). While S. epidermidis typically causes indolent infections of prosthetic devices, including prosthetic valves and intravascular catheters, S. epidermidis NVE is a virulent infection associated with valve destruction and high mortality. In order to see if the differences in the course of infection were due to characteristics of the infecting organisms, we examined 31 S. epidermidis NVE and 65 PVE isolates, as well as 21 isolates from blood cultures (representing bloodstream infections [BSI]) and 28 isolates from nasal specimens or cultures considered to indicate skin carriage. Multilocus sequence typing showed both NVE and PVE isolates to have more unique sequence types (types not shared by the other groups; 74 and 71%, respectively) than either BSI isolates (10%) or skin isolates (42%). Thirty NVE, 16 PVE, and a total of 9 of the nasal, skin, and BSI isolates were tested for virulence in Caenorhabditis elegans. Twenty-one (70%) of the 30 NVE isolates killed at least 50% of the worms by day 5, compared to 1 (6%) of 16 PVE isolates and 1 (11%) of 9 nasal, skin, or BSI isolates. In addition, the C. elegans survival rate as assessed by log rank analyses of Kaplan-Meier survival curves was significantly lower for NVE isolates than for each other group of isolates (P < 0.0001). There was no correlation between the production of poly-beta(1-6)-N-acetylglucosamine exopolysaccharide and virulence in worms. This study is the first analysis suggesting that S. epidermidis isolates from patients with NVE constitute a more virulent subset within this species.
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PMID:Analysis of the genotype and virulence of Staphylococcus epidermidis isolates from patients with infective endocarditis. 1879 84

The mitis group, a member of the genetically diverse viridans group streptococci, predominately colonizes the human oropharynx. This group has been shown to cause a wide range of infectious complications in humans, including bacteremia in patients with neutropenia, orbital cellulitis and infective endocarditis. Hydrogen peroxide (H2O2) has been identified as a virulence factor produced by this group of streptococci. More importantly, it has been shown that Streptococcus oralis and S. mitis induce epithelial cell and macrophage death via the production of H2O2. Previously, H2O2 mediated killing was observed in the nematode Caenorhabditis elegans in response to S. oralis and S. mitis. The genetically tractable model organism C. elegans is an excellent system to study mechanisms of pathogenicity and stress responses. Using this model, we observed rapid H2O2 mediated killing of the worms by S. gordonii in addition to S. mitis and S. oralis. Furthermore, we observed colonization of the intestine of the worms when exposed to S. gordonii suggesting the involvement of an infection-like process. In response to the H2O2 produced by the mitis group, we demonstrate the oxidative stress response is activated in the worms. The oxidative stress response transcription factor SKN-1 is required for the survival of the worms and provides protection against H2O2 produced by S. gordonii. We show during infection, H2O2 is required for the activation of SKN-1 and is mediated via the p38-MAPK pathway. The activation of the p38 signaling pathway in the presence of S. gordonii is not mediated by the endoplasmic reticulum (ER) transmembrane protein kinase IRE-1. However, IRE-1 is required for the survival of worms in response to S. gordonii. These finding suggests a parallel pathway senses H2O2 produced by the mitis group and activates the phosphorylation of p38. Additionally, the unfolded protein response plays an important role during infection.
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PMID:The activation of the oxidative stress response transcription factor SKN-1 in Caenorhabditis elegans by mitis group streptococci. 3011 61

Caenorhabditis elegans (C. elegans), a free-living nematode, has emerged as an attractive model to study host-pathogen interactions. The presented protocol uses this model to determine the pathogenicity caused by the mitis group streptococci via the production of H2O2. The mitis group streptococci are an emerging threat that cause many human diseases such as bacteremia, endocarditis, and orbital cellulitis. Described here is a protocol to determine the survival of these worms in response to H2O2 produced by this group of pathogens. Using the gene skn-1 encoding for an oxidative stress response transcription factor, it is shown that this model is important for identifying host genes that are essential against streptococcal infection. Furthermore, it is shown that activation of the oxidative stress response can be monitored in the presence of these pathogens using a transgenic reporter worm strain, in which SKN-1 is fused to green fluorescent protein (GFP). These assays provide the opportunity to study the oxidative stress response to H2O2 derived by a biological source as opposed to exogenously added reactive oxygen species (ROS) sources.
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PMID:Studying Oxidative Stress Caused by the Mitis Group Streptococci in Caenorhabditis elegans. 3095 78