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Query: UMLS:C0348321 (Haemophilus)
 15,372 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Haemophilus influenzae is a heme-dependent bacterium. However, little is known of the heme-iron uptake mechanism in this organism. By using a batch ligand affinity chromatography method, a hemin-binding protein of 39,500 molecular weight was isolated from total membranes derived from H. influenzae type b grown under iron-depleted but not under iron-sufficient conditions. Detection of the hemin-binding protein in a whole-cell binding assay demonstrated a surface-exposed location. Competition binding experiments indicated that this hemin-protein interaction was specific, since only hemin or heme-containing proteins, such as human hemoglobin and bovine catalase, but not protoporphyrin IX, iron-loaded human lactoferrin, or transferrin, could abrogate binding. In a limited survey of other H. influenzae strains, an identical hemin-binding protein was isolated, implying that this polypeptide may be structurally and functionally conserved among strains.
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PMID:Isolation of an outer membrane hemin-binding protein of Haemophilus influenzae type b. 154 54

There is now considerable evidence to show that in the Neisseria and Haemophilus species, membrane receptors specific for either transferrin or lactoferrin are involved in the acquisition of iron from these glycoproteins. In Neisseria meningitidis, the transferrin receptor appears to consist of two proteins, one of which (TBP 1) has an M(r) of 95,000 and the other of which (TBP 2) has an M(r) ranging from 68,000 to 85,000, depending on the strain; TBP 2 binds transferrin after sodium dodecyl sulfate-polyacrylamide gel electrophoresis and electroblotting, but TBP 1 does not do so. The relative contributions of these two proteins to the binding reaction observed with intact cells and to iron uptake are presently unknown. However, they are being considered as potential components of a group B meningococcal vaccine. Analogous higher- and lower-molecular-weight proteins associated with transferrin binding have been found in N. gonorrhoeae and Haemophilus influenzae. Previous work with polyclonal antibodies raised in mice with whole cells of iron-restricted N. meningitidis showed that the meningococcal TBP 2 exhibits considerable antigenic heterogeneity. Here, we report that antiserum against purified TBP 2 from one strain of N. meningitidis cross-reacts on immunoblotting with the TBP 2 of all meningococcal isolates examined, as well as with the TBP 2 of N. gonorrhoeae. This antiserum also cross-reacted with the TBP 2 of several strains of H. influenzae type b, thus showing the presence of common antigenic domains among these functionally equivalent proteins in different pathogens; no cross-reaction was detected with a purified sample of the human transferrin receptor.
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PMID:Common antigenic domains in transferrin-binding protein 2 of Neisseria meningitidis, Neisseria gonorrhoeae, and Haemophilus influenzae type b. 158 6

The ability of Haemophilus influenzae, H. parainfluenzae and H. paraphrophilus to utilize iron complexes, iron-proteins and exogenous microbial siderophores was evaluated. In a plate bioassay, all three species used not only ferric nitrate but also the iron chelates ferric citrate, ferric nitrilotriacetate and ferric 2,3-dihydroxybenzoate. Each Haemophilus species examined also used haemin, haemoglobin and haem-albumin as iron sources although only H. influenzae could acquire iron from transferrin or from haemoglobin complexed with haptoglobin. None of the haemophili obtained iron from ferritin or lactoferrin or from the microbial siderophores aerobactin or desferrioxamine B. However, the phenolate siderophore enterobactin supplied iron to both H. parainfluenzae and H. paraphrophilus, and DNA isolated from both organisms hybridized with a DNA probe prepared from the Escherichia coli ferric enterobactin receptor gene fepA. In addition, a monospecific polyclonal antiserum raised against the E. coli 81 kDa ferric enterobactin receptor (FepA) recognized an iron-repressible outer membrane protein (OMP) in H. parainfluenzae of between 80 and 82 kDa (depending on the strain). This anti-FepA serum did not cross-react with any of the OMPs of H. paraphrophilus or H. influenzae. The OMPs of each Haemophilus species were also probed with antisera raised against the 74 kDa Cir or 74 kDa IutA (aerobactin receptor) proteins of E. coli. Apart from one H. parainfluenzae strain (NCTC 10665), in which an OMP of about 80 kDa cross-reacted with the anti-IutA sera, no cross-reactivity was observed between Cir, IutA and the OMPs of H. influenzae, H. parainfluenzae or H. paraphrophilus.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Utilization of enterobactin and other exogenous iron sources by Haemophilus influenzae, H. parainfluenzae and H. paraphrophilus. 215 Apr 14

Otitis media with effusion is a significant cause of hearing loss in young children. We hypothesized that persistent bacterial antigens in middle ear effusions (MEEs) might act as chronic inflammatory stimuli causing release of neutrophil proteins. Concentrations of neutrophil lactoferrin and a 37-kd cationic bactericidal protein (CAP 37) were measured in 47 MEEs collected from 27 children at the time of tympanostomy tube placement. Antigens of Streptococcus pneumoniae were detected by latex particle agglutination and those of Haemophilus influenzae by dot-blot assay. Bacterial antigens were detectable in 24 (51%) of MEEs: S pneumoniae in 10 (21%), H influenzae in 12 (26%), and both antigens in 2 (4%). Concentrations of lactoferrin and CAP 37 in H influenzae antigen-positive MEEs were significantly higher than in either S pneumoniae antigen-positive or antigen-negative MEEs. We conclude that H influenzae antigen causes a greater middle-ear inflammatory response, as judged by neutrophil products, than does S pneumoniae antigen.
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PMID:Bacterial antigens and neutrophil granule proteins in middle ear effusions. 230 52

Haemophilus influenzae and H. haemolyticus acquired iron bound to human transferrin but not to human lactoferrin, ovo- or porcine transferrins. Conversely the swine pathogens H. pleuropneumoniae and H. parasuis used iron bound only to porcine transferrin. Growth under conditions of iron deprivation induced the production of siderophores and iron-repressible outer membrane proteins in H. parainfluenzae, H. paraphrophilus and H. parasuis but not in H. influenzae, H. haemolyticus or H. pleuropneumoniae. The latter 3 Haemophilus species appear to sequester transferrin bound iron via a siderophore-independent mechanism. However, the ability to produce iron chelating compounds did not enable H. parainfluenzae or H. paraphrophilus to utilize transferrin bound iron.
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PMID:Utilization of transferrin-bound iron by Haemophilus species of human and porcine origins. 253 28

An affinity procedure with purified, biotinylated human transferrin and streptavidin-agarose was used to identify the transferrin-binding proteins in strains of Haemophilus influenzae. Proteins of 58 and 98 Kda were isolated from total membranes prepared from iron-deficient but not iron-sufficient H. influenzae KC548 cells. The 58-Kda protein was capable of binding human transferrin after sodium dodecyl sulphate (SDS)-polyacrylamide gel electrophoresis (PAGE) and electroblotting. Isolation of transferrin-binding proteins from type-b and non-typable H. influenzae strains demonstrated some variability in the size of the higher mol. wt protein (94-106 Kda) and in ease of elution of the smaller protein from the affinity resin. Use of purified, biotinylated human lactoferrin in the affinity isolation procedure with membranes from a strain expressing lactoferrin-binding activity resulted in isolation of proteins of 105 and 106 Kda distinct from the transferrin-binding proteins.
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PMID:Identification of the transferrin- and lactoferrin-binding proteins in Haemophilus influenzae. 254 20

The expression of human transferrin and lactoferrin binding activity in Haemophilus influenzae, detected by a binding assay using human transferrin or lactoferrin conjugated to peroxidase, was regulated by the level of available iron in the medium. Transferrin binding activity was present in all H. influenzae isolates tested but not detected in other Haemophilus species or in species of Pasteurella or Actinobacillus. Lactoferrin binding activity was only detected in 1/15 H. influenzae isolates tested. The transferrin and lactoferrin receptors were shown to be specific for the respective human proteins by means of a competition binding assay. Competition binding assays also showed that iron-loaded transferrin was more effective at blocking the transferrin receptor than apotransferrin, but no differences in receptor blocking were observed between iron-loaded lactoferrin and apolactoferrin.
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PMID:Characterization of the human transferrin and lactoferrin receptors in Haemophilus influenzae. 284 24

The mechanisms for acquisition of iron by Haemophilus influenzae and their role in pathogenesis are not known. Heme and nonheme sources of iron were evaluated for their effect on growth of type b and nontypable strains of H. influenzae in an iron-restricted, defined medium. All 13 strains acquired iron from heme, hemoglobin, hemoglobin-haptoglobin, and heme-hemopexin. Among nonheme sources of protein-bound iron, growth of H. influenzae was enhanced by partially saturated human transferrin but not by lactoferrin or ferritin. Purified ferrienterochelin and ferridesferrioxamine failed to provide iron to H. influenzae, and the supernatants of H. influenzae E1a grown in iron-restricted medium failed to enhance iron-restricted growth of siderophore-dependent strains of Escherichia coli, Salmonella typhimurium, and Arthrobacter terregens. Marked alterations in the profile of outer membrane proteins of H. influenzae were observed when the level of free iron was varied between 1 microM and 1 mM. Catechols were not detected in the supernatants of strain E1a; however, iron-related hydroxamate production was detected by two biochemical assays. We conclude that the sources of iron for H. influenzae are diverse. The significance of hydroxamate production and iron-related outer membrane proteins to H. influenzae iron acquisition is not yet clear.
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PMID:Iron acquisition by Haemophilus influenzae. 296 10

Haemophilus influenzae grown on enriched medium containing protoporphyrin IX rather than hemin was iron starved by the addition of the chelator ethylenediamine di-o-hydroxyphenylacetic acid. Iron starvation could be overcome in each of 33 H. influenzae type b isolates by 30% Fe-saturated human transferrin but not by human lactoferrin. Among nontypeable H. influenzae, 28 of 35 isolates, including 2 of 3 systemic isolates, were able to utilize Fe-transferrin. None of 18 H. parainfluenzae isolates was able to use Fe-transferrin. Iron starvation of H. influenzae type b resulted in increased amounts of three membrane proteins of 94,000 to 98,000 daltons.
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PMID:Haemophilus influenzae can use human transferrin as a sole source for required iron. 387 64

Bronchial secretions obtained during bronchoscopic examination of 60 children suffering from respiratory tract infections were studied for the concentration of immunoglobulins, anti-proteolytic factors, lactoferrin, and lysozyme. Eleven children having bronchial asthma without a history of chronic or recurrent infections of the respiratory tract were designated as a control. The results were analysed in relation to clinical diagnosis (chronic bronchitis, bronchitis, bronchiectasis) or to the local status of bronchial mucosa at the time of bronchoscopy (no inflammation, inflammation, inflammation with documented bacterial infection). The statistical analysis of the results revealed a decrease of lactoferrin and locally produced IgA in the group of children suffering from bronchitis and chronic bronchitis. Samples infected with Haemophilus species had significantly higher concentration of lactoferrin than any other group. Similarly, albumin in this group was higher than in the other group except that other bacteria were present. Samples infected with Haemophilus also had increased concentrations of S-IgA, IgG, and anti-proteolytic factors when compared with the group without local inflammation.
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PMID:Studies of bronchial secretion. The influence of inflammatory response and bacterial infection. 396 91


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