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Sample records for actinobacillus actinomycetemcomitans strains

  1. Detection and strain identification of Actinobacillus actinomycetemcomitans by nested PCR.

    PubMed Central

    Leys, E J; Griffen, A L; Strong, S J; Fuerst, P A

    1994-01-01

    By using PCR, Actinobacillus actinomycetemcomitans strains were identified directly from plaque samples without the need to isolate or culture bacteria. DNA fragments were generated by a nested, two-step PCR amplification of the ribosomal spacer region between the 16S and 23S rRNA genes. For the first amplification, primers homologous to sequences common to all bacterial species were used. This was followed by a second amplification with primers specific to A. actinomycetemcomitans. The ribosomal DNA spacer region was amplified from as few as 10 bacterial cells within a total population of 10(8) cells (0.00001%), and cross-reactivity between species was not observed. DNA fragments specific for Porphyromonas gingivalis were generated from the same samples by using a P. gingivalis-specific primer, and equivalent sensitivity and specificity were observed. A. actinomycetemcomitans was detected in 60% and P. gingivalis was detected in 79% of 52 subjects tested. Sequence analysis of the spacer region DNA fragment for A. actinomycetemcomitans gave precise strain identification, producing unique sequences for seven reference strains and identification of nine plaque-derived isolates. A phylogenetic tree based on quantitative sequence relationships was constructed. Two-step PCR amplification directly from plaque samples combined with sequence analysis of the ribosomal DNA spacer region provides a sensitive assay for detection and strain identification of multiple species directly from a single plaque sample. This simplified approach provides a practical method for large-scale studies on the transmission and pathogenicity of periodontitis-associated bacteria. Images PMID:8051258

  2. Actinobacillus actinomycetemcomitans strains Y4 and N27 adhere to hydroxyapatite by distinctive mechanisms.

    PubMed Central

    Kagermeier, A S; London, J

    1985-01-01

    Actinobacillus actinomycetemcomitans strains Y4 and N27 absorb to spheroidal hydroxyapatite in roughly the same numbers per milligram of substrate and with the same tenacity as two previously tested Cytophaga species. Although the two strains of A. actinomycetemcomitans exhibited similar affinities and number of binding sites for SHA, their response to enzyme treatment and heating were very different. The capacity of strain Y4 to attach to spheroidal hydroxyapatite was diminished by treatment with proteases and phospholipases and was unaffected by neuraminidase, while strain N27 was unaffected by proteases and phospholipases and lost its binding capabilities when treated with neuraminidase. Images PMID:3972445

  3. Actinobacillus actinomycetemcomitans endocarditis.

    PubMed Central

    Affias, S.; West, A.; Stewart, J. W.; Haldane, E. V.

    1978-01-01

    Two patients had infective endocarditis due to Actinobacillus actinomycetemcomitans. One, a 52-year-old woman with a prosthetic aortic valve, was successfully treated with carbenicillin and gentamicin. The other, a 47-year old man with calcific aortic valve disease, required emergency valvectomy and prosthetic valve replacement and responded to a combination of penicillin and gentamicin. PMID:647545

  4. Monoclonal antibodies to Actinobacillus actinomycetemcomitans.

    PubMed Central

    Place, D A; Scidmore, N C; McArthur, W P

    1988-01-01

    Murine hybridoma cell lines were developed which synthesized monoclonal antibodies against Actinobacillus actinomycetemcomitans-associated antigens. Monoclonal antibodies specific for an antigen(s) common to all A. actinomycetemcomitans isolates tested but not detected on other gram-negative oral plaque microorganisms or other Actinobacillus species were identified. Monoclonal antibodies specific for each serotype group of A. actinomycetemcomitans which did not bind to other Actinobacillus species or oral plaque microorganisms were also identified. PMID:3356470

  5. A bacteriocin of Actinobacillus actinomycetemcomitans.

    PubMed Central

    Hammond, B F; Lillard, S E; Stevens, R H

    1987-01-01

    An inhibitory factor from Actinobacillus actinomycetemcomitans Y4 was isolated, and its properties indicated that it was a bacteriocin (actinobacillicin). The bacteriocin was active against Streptococcus sanguis strains, Streptococcus uberis (FDC1), and Actinomyces viscosus T14 as well as other strains of A. actinomycetemcomitans, but not against other crevicular bacteria, including other streptococci and actinomycetes. The activity of this bacteriocin was inhibited by pronase, trypsin, and heat (45 min at 56 degrees C) but not by DNase, RNase, phospholipase, exposure to UV light, or low pH (1.0 to 6.5). Although actinobacillicin markedly inhibited glycolysis in S. sanguis, the primary mechanism of its bactericidal action appears to be alterations in cell permeability, with the resultant leakage of RNA, DNA, and other essential intracellular macromolecules. These findings provide an ecologic explanation for the reciprocal growth relationship between A. actinomycetemcomitans and S. sanguis/Actinomyces viscosus observed in localized juvenile periodontitis. Images PMID:3818090

  6. Differential regulation of the leukotoxin operon in highly leukotoxic and minimally leukotoxic strains of Actinobacillus actinomycetemcomitans.

    PubMed Central

    Hritz, M; Fisher, E; Demuth, D R

    1996-01-01

    The expression of the leukotoxin (ltx) operon varies significantly among Actinobacillus actinomycetemcomitans strains. The dual promoters driving ltx expression in the highly toxic strain JP2 have been previously characterized (J. M. Brogan, E. T. Lally, K. Poulsen, M. Kilian, and D. R. Demuth, Infect. Immun. 62:501-508, 1994), and genetic analyses of A. actinomycetemcomitans suggest that highly toxic strains like JP2 arose from minimally toxic strains, presumably by deletion of a 530-bp domain within the ltx promoter region (K. Poulsen, E. Theilade, E.T. Lally, D. R. Demuth, and M. Kilian, Microbiology 140:2049-2060, 1994). However, the ltx promoter of minimally toxic A. actinomycetemcomitans strains has not been well characterized. In this study, deletion and primer extension analyses showed that the ltx promoter of A. actinomycetemcomitans 652 is situated approximately 150 bp upstream of the ltxC gene and initiates transcription 138 nucleotides upstream of ltxC. In contrast to strain JP2, only a single promoter appears to drive ltx expression in 652. The 652 promoter resides within the 530-bp region that is absent from the JP2 promoter sequence, suggesting that the specific sequences controlling ltx expression differ in highly toxic and minimally toxic A. actinomycetemcomitans strains. In addition, ltx expression in strain 652 was shown to be induced three- to fourfold when cells were grown under anaerobic conditions. The induction of whole cell leukotoxicity, was accompanied by increases in the levels of Ltx polypeptide and the steady-state levels of ltx mRNA, suggesting that regulation occurred at the level of transcription. In contrast, the levels of leukotoxicity, Ltx polypeptide, and fix mRNA in strain JP2 were unaffected by anaerobic growth. These results suggest that the ltx operon is differentially regulated in highly toxic and minimally toxic A. actinomycetemcomitans strains and that the sequences controlling the oxygen-dependent regulation of ltx

  7. In vitro antimicrobial susceptibility of Actinobacillus actinomycetemcomitans.

    PubMed Central

    Slots, J; Evans, R T; Lobbins, P M; Genco, R J

    1980-01-01

    The agar dilution technique was used for determination of the antibiotic susceptibilities of 57 oral isolates and 2 nonoral isolates of Actinobacillus actinomycetemcomitans. Tetracycline, minocycline, and chloramphenicol inhibited more than 96% of the strains tested at a concentration of less than or equal to 2 micrograms/ml; 89% of the strains were inhibited by 2 micrograms of carbenicillin per ml. The other antimicrobial agents tested were less active. Approximately 10% of the A. actinomycetemcomitans strains were resistant to ampicillin, erythromycin, and penicillin G at concentrations of 32 to 64 micrograms/ml. These data suggest that tetracycline and minocycline may be valuable drugs in the treatment of A. actinomycetemcomitans infections. PMID:6903116

  8. Identification and characterization of the major cell envelope proteins of oral strains of Actinobacillus actinomycetemcomitans.

    PubMed Central

    Di Rienzo, J M; Spieler, E L

    1983-01-01

    The major cell envelope protein compositions of seven Actinobacillus actinomycetemcomitans strains of human origin were compared by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The major envelope polypeptides were homogeneous, in relation to molecular weight, in all of the strains that were examined. The characterization of the five major proteins, designated Env1 through Env5, in the leukotoxic strain Y4 revealed that proteins Env2 to -5 may reside in the outer membrane as suggested by differential detergent extractions and 125I-labeling experiments. The proteins did not demonstrate covalent or ionic interactions with the peptidoglycan; however, one protein, Env2, displayed heat-modifiable properties, having apparent molecular weights of 32,000 and 45,000 when heated in sodium dodecyl sulfate at 50 and 100 degrees C, respectively. The protein composition of the extracellular "bleb" material, normally released by strain Y4, was determined, and proteins Env1 to -4 were the predominant protein species found. A comparison of the cell envelope proteins of strain Y4 with those of other members of the human oral flora, including species within the genera Capnocytophaga, Bacteroides, and Fusobacterium, revealed distinct differences on the basis of molecular size and heat-modifiable properties. However, the membrane proteins of Haemophilus aphrophilus showed a remarkable degree of homology with those of A. actinomycetemcomitans. Images PMID:6401694

  9. Regulation of leukotoxin in leukotoxic and nonleukotoxic strains of Actinobacillus actinomycetemcomitans.

    PubMed Central

    Spitznagel, J; Kraig, E; Kolodrubetz, D

    1991-01-01

    Actinobacillus actinomycetemcomitans is a gram-negative bacterium that has been implicated in the etiology of several forms of periodontitis, especially localized juvenile periodontitis. A potent leukotoxin (Lkt) is produced by most A. actinomycetemcomitans isolates from patients with periodontal disease, but some isolates are leukotoxin nonproducing (Lkt-). The molecular bases for the differences in leukotoxin expression are being explored to clarify the role of leukotoxin in pathogenesis. We have previously cloned the leukotoxin structural gene, lktA, from the leukotoxin-producing (Lkt+) strain JP2 and have shown that it is linked to three other genes, lktB, lktC, and lktD, whose gene products are thought to be required for activation and localization of the leukotoxin. These genes have now been used in Southern blot analysis to demonstrate that Lkt- strains, like Lkt+ strains, contain all four genes of the lkt gene cluster. While restriction fragment length polymorphisms were detected, they did not correlate with toxin phenotype. RNA blot analysis demonstrated that Lkt+ strains produced two transcripts, one 9.3 kb in length and the other 4.3 kb. They encode lktCABD and lktCA. respectively. Lkt- strains contained significantly lower levels of the 4.3-kb transcript with no discernible 9.3-kb message. The leukotoxic activity of the A. actinomycetemcomitans strains, measured by chromium release assays, correlated with the lkt RNA content. Therefore, a major component of leukotoxin regulation is at the level of RNA transcription or stability. Interestingly, the lkt RNAs in JP2 are regulated during growth phase, being greatly reduced in cells approaching stationary phase. Thus, the regulation of lkt RNA can be affected by both genotype and environment. Images PMID:2004819

  10. Electron microscopy of phages in serotypes of Actinobacillus actinomycetemcomitans.

    PubMed

    Olsen, I; Namork, E; Myhrvold, V

    1993-12-01

    Actinobacillus actinomycetemcomitans, Actinobacillus ureae, Haemophilus aphrophilus, Haemophilus paraphrophilus, Haemophilus influenzae, Haemophilus parainfluenzae, Pasteurella haemolytica and Pasteurella multocida strains were examined by transmission electron microscopy for the presence of bacteriophages. Phages were detected in serotype a (SUNY 75) and e (UOH 1705) and in the fresh clinical isolates UOH Q1243 and UOH Q1247 of A. actinomycetemcomitans. Phages were not found in serotype b, c and d strains of A. actinomycetemcomitans, in the fresh clinical isolate UOH Q1244 of this species or in old strains (including reference strains) of related species from the Actinobacillus-Haemophilus-Pasteurella group.

  11. Evidence that extracellular components function in adherence of Actinobacillus actinomycetemcomitans to epithelial cells.

    PubMed Central

    Meyer, D H; Fives-Taylor, P M

    1993-01-01

    Extracellular microvesicles and a highly proteinaceous polymer associated with a leukotoxin-producing strain, Actinobacillus actinomycetemcomitans SUNY 75, were shown to increase adherence of other weakly adherent A. actinomycetemcomitans strains to KB epithelial cells. Images PMID:8406899

  12. cis Elements and trans factors are both important in strain-specific regulation of the leukotoxin gene in Actinobacillus actinomycetemcomitans.

    PubMed Central

    Kolodrubetz, D; Spitznagel, J; Wang, B; Phillips, L H; Jacobs, C; Kraig, E

    1996-01-01

    Actinobacillus actinomycetemcomitans, the etiologic agent of localized juvenile periodontitis, produces a potent leukotoxin that kills human neutrophils. The production of leukotoxin RNA can vary more than 50-fold among isolates of A. actinomycetemcomitans, and strains expressing high levels of leukotoxin RNA are most often found at sites of periodontal disease. To assess the relative contributions of transcription factors and promoter sequences in setting the disparate levels of leukotoxin RNA found, we have undertaken classical cis/trans analyses. First, the leukotoxin promoter regions from moderately leukotoxic (Y4) and minimally leukotoxic (ATCC 33384) strains of A. actinomycetemcomitans were cloned, sequenced, and compared with the previously sequences leukotoxin promoter region of the high-producer strain JP2. The Y4 and ATCC 33384 promoter regions each contain a 528-bp segment that is absent from JP2. Interestingly, the analysis of various deletion constructs in A. actinomycetemcomitans indicated that Y4, despite the large insertion, initiates leukotoxin RNA synthesis at the same promoter as JP2 does. To perform cis/trans analyses, these three leukotoxin promoter regions were cloned into a plasmid upstream of the reporter gene beta-galactosidase. Each plasmid was transformed into JP2, Y4, and ATCC 33384, and the beta-galactosidase levels were determined. The results indicated that the sequences responsible for down-regulating leukotoxin RNA levels in Y4 relative to JP2 are found within the transcribed region of the Y4 leukotoxin operon. Importantly, in ATCC 33384, strain-specific trans factors and promoter sequence differences are equally significant in determining the lower levels of leukotoxin RNA. We hypothesize that either strain ATCC 33384 has a negative regulatory protein (which is missing or mutated in JP2/Y4) or that JP2 and Y4 carry an activator that is missing or mutated in ATCC 33384. PMID:8751884

  13. Inhibition of fibroblast proliferation by Actinobacillus actinomycetemcomitans.

    PubMed Central

    Shenker, B J; Kushner, M E; Tsai, C C

    1982-01-01

    We have examined soluble sonic extracts of Actinobacillus actinomycetemcomitans for their ability to alter human and murine fibroblast proliferation. We found that extracts of all A. actinomycetemcomitans strains examined (both leukotoxic and nonleukotoxic) caused a dose-dependent inhibition of both murine and human fibroblast proliferation as assessed by DNA synthesis ([3H]thymidine incorporation). Addition of sonic extract simultaneously with [3H]thymidine had no effect on incorporation, indicating that suppression was not due to the presence of excessive amounts of cold thymidine. Inhibition of DNA synthesis was also paralleled by decreased RNA synthesis ([3H]uridine incorporation) and by a decrease in cell growth as assessed by direct cell counts; there was no effect on cell viability. The suppressive factor(s) is heat labile; preliminary purification and characterization studies indicate that it is a distinct and separate moiety from other A. actinomycetemcomitans mediators previously reported, including leukotoxin, immune suppressive factor, and endotoxin. Although it is not clear how A. actinomycetemcomitans acts to cause disease, we propose that one aspect of the pathogenicity of this organism rests in its ability to inhibit fibroblast growth, which in turn could contribute to the collagen loss associated with certain forms of periodontal disease, in particular juvenile periodontitis. PMID:7152684

  14. Monoclonal antibodies to leukotoxin of Actinobacillus actinomycetemcomitans.

    PubMed Central

    DiRienzo, J M; Tsai, C C; Shenker, B J; Taichman, N S; Lally, E T

    1985-01-01

    Hybridoma cell lines which produce monoclonal antibodies to a leukotoxin from Actinobacillus actinomycetemcomitans were prepared. The monoclonal antibodies were selected for their ability to neutralize the cytotoxic activity of the leukotoxin and recognize the toxin on nitrocellulose blots. The antibodies belonged to either the immunoglobulin G1 (IgG1) or IgG2 subclass and differed in their ability to bind to the leukotoxin on nitrocellulose blots. However, only slight differences in neutralization titers were observed. Use of the monoclonal antibodies revealed that polymyxin B-extracted or osmotic shock-released leukotoxin could be separated into several high-molecular-weight polypeptides by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Immunoblot analysis with the monoclonal antibodies also demonstrated that the leukotoxin was present in eight oral strains of A. actinomycetemcomitans that had been previously classified by a biological assay as leukotoxic. The availability of these monoclonal antibodies should facilitate and expand studies concerning the role of the leukotoxin in the pathogenicity of A. actinomycetemcomitans. Images PMID:3965404

  15. Transformation of Actinobacillus actinomycetemcomitans by electroporation, utilizing constructed shuttle plasmids.

    PubMed Central

    Sreenivasan, P K; LeBlanc, D J; Lee, L N; Fives-Taylor, P

    1991-01-01

    Actinobacillus actinomycetemcomitans, a periodontal pathogen, has been strongly implicated in human periodontal disease. Advances in the molecular analysis of A. actinomycetemcomitans virulence factors have been limited due to the unavailability of systems for genetic transfer, transposon mutagenesis, and gene complementation. Slow progress can be traced almost exclusively to the lack of gene vector systems and methods for the introduction of DNA into A. actinomycetemcomitans. An electrotransformation system that allowed at least five strains of A. actinomycetemcomitans to be transformed with stable shuttle plasmids which efficiently replicated in both Escherichia coli and A. actinomycetemcomitans was developed. One plasmid, a potential shuttle vector designated pDL282, is 5.7 kb in size, has several unique restriction enzyme sites, and codes for resistance to spectinomycin and ampicillin. E. coli and A. actinomycetemcomitans were transformed with equal efficiencies of approximately 10(5) transformants per micrograms of DNA. Similar transformation efficiencies were obtained whether the plasmid DNA was isolated from A. actinomycetemcomitans or E. coli. In addition, frozen competent cells of A. actinomycetemcomitans yielded comparable efficiencies of transformation. Restriction enzyme analysis of pDL282 isolated after transformation confirmed the presence of intact donor plasmids. A plasmid isolated from A. pleuropneumoniae was also capable of transforming some isolates of A. actinomycetemcomitans, although generally at a lower frequency. The availability of these shuttle plasmids and an efficient transformation procedure should significantly facilitate the molecular analysis of virulence factors of A. actinomycetemcomitans. PMID:1937823

  16. Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis in young Chinese adults.

    PubMed

    Mombelli, A; Gmür, R; Frey, J; Meyer, J; Zee, K Y; Tam, J O; Lo, E C; Di Rienzo, J; Lang, N P; Corbet, E F

    1998-08-01

    The aim of this study was to determine the presence or absence of Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis in young Chinese adults and to examine the A. actinomycetemcomitans isolates from positive subjects with regard to the serotype distribution, presence of the leukotoxin gene lktA and the promoter for the leukotoxin operon as well as the incidence of phage Aa phi 23. Sixty subjects, working in a knitting factory in the Province of Guangzhou, People's Republic of China, were investigated. Subgingival microbial samples were taken from both upper first molars. They were cultured both anaerobically and in 5% CO2. P. gingivalis was found in 33 subjects. On average, it constituted 7% of the total anaerobic cultivable counts. A. actinomycetemcomitans was detected in 37 subjects of which seven yielded counts > 10(5). Twenty-one subjects were positive for both organisms. A. actinomycetemcomitans serotype a was found in 9 subjects, serotype c was found in 23 and serotype e in 5. A. actinomycetemcomitans serotypes b and d were not detected in any subjects. Presence of the leukotoxin gene lktA was demonstrated for all A. actinomycetemcomitans isolates; however, none of the A. actinomycetemcomitans strains from the present study had a deletion in the promoter region of the leukotoxin operon. The results of this investigation show a high frequency of the putative periodontal pathogens P. gingivalis and A. actinomycetemcomitans and corroborate the concept that there is variation in virulence and pathogenic potential among isolates from different subjects.

  17. Selective medium for isolation of Actinobacillus actinomycetemcomitans.

    PubMed Central

    Slots, J

    1982-01-01

    A selective medium, TSBV (tryptic soy-serum-bacitracin-vancomycin) agar, was developed for the isolation of Actinobacillus actinomycetemcomitans, TSBV agar contained (per liter) 40 g of tryptic soy agar, 1 g of yeast extract, 100 ml of horse serum. 75 mg of bacitracin, and 5 mg of vancomycin. The TSBV medium suppressed most oral species and permitted significantly higher recovery of A. actinomycetemcomitans than nonselective blood agar medium. The distinct colonial morphology and positive catalase reaction of A. actinomycetemcomitans easily distinguished this bacterium from Haemophilus aphrophilus, Capnocytophaga species, and a few other contaminating organisms. With the TSBV medium, even modestly equipped laboratories will be able to isolate and identify A. actinomycetemcomitans from clinical specimens. Images PMID:7068837

  18. Immunosuppressive properties of Actinobacillus actinomycetemcomitans leukotoxin.

    PubMed Central

    Rabie, G; Lally, E T; Shenker, B J

    1988-01-01

    Actinobacillus actinomycetemcomitans produces a leukotoxin that kills human polymorphonuclear cells (PMNs) and monocytes but not lymphocytes. In this study, we examined A. actinomycetemcomitans leukotoxin for its ability to alter human peripheral blood lymphocyte (HPBL) responsiveness. After a 90-min exposure to the leukotoxin, all monocytes were killed and HPBL responsiveness to mitogens and antigens was significantly inhibited. The ability of the leukotoxin to inhibit HPBL responses was not surprising, since monocytes and macrophages are required for many lymphocyte functions. However, we were unable to totally restore HPBL responsiveness when adherent autologous monocytes were added back to cultures of leukotoxin-treated lymphocytes. These studies demonstrate that A. actinomycetemcomitans leukotoxin may also exert nonlethal effects directly on lymphocytes. Furthermore, impaired lymphocyte function did not appear to be the result of indirect effects of products released by dying monocytes. Although it is not clear how A. actinomycetemcomitans acts to cause disease, several investigators have proposed that impaired host defenses may play a pivotal role. Several studies have demonstrated defects in PMN, monocyte, and lymphocyte function in patients with periodontal disease. These findings, along with the data presented in this paper, support the hypothesis that patients who harbor A. actinomycetemcomitans could suffer from local or systemic immune suppression. The effects of this suppression may be to enhance the pathogenicity of A. actinomycetemcomitans itself or that of some other opportunistic organism. PMID:3335399

  19. Killing of Actinobacillus actinomycetemcomitans by human lactoferrin.

    PubMed Central

    Kalmar, J R; Arnold, R R

    1988-01-01

    Actinobacillus actinomycetemcomitans is a fastidious, facultative gram-negative rod associated with endocarditis, certain forms of periodontal disease, and other focal infections. Human neutrophils have demonstrated bactericidal activity against A. actinomycetemcomitans, and much of the oxygen-dependent killing has been attributed to the myeloperoxidase-H2O2-halide system. However, the contribution of other neutrophil components to killing activity is obscure. Lactoferrin, an iron-binding glycoprotein, is a major constituent of neutrophil-specific granules and is also found in mucosal secretions. In this report, we show that human lactoferrin is bactericidal for A. actinomycetemcomitans. Killing activity required an unsaturated (iron- and anion-free) molecule that produced a 2-log decrease in viability within 120 min at 37 degrees C at a concentration of 1.9 microM. Besides exhibiting concentration dependence, killing kinetics were affected by minor variations in temperature and pH. Magnesium, a divalent cation thought to stabilize lipopolysaccharide interactions on the surface of gram-negative organisms, enhanced lactoferrin killing of A. actinomycetemcomitans, while other cations, such as potassium and calcium, had no effect. Our data suggest that lactoferrin contributes to killing of A. actinomycetemcomitans by human neutrophils and that it may also play a significant role in innate secretory defense against this potential periodontopathogen. PMID:3417349

  20. Cloning and expression of the leukotoxin gene from Actinobacillus actinomycetemcomitans.

    PubMed Central

    Kolodrubetz, D; Dailey, T; Ebersole, J; Kraig, E

    1989-01-01

    The leukotoxin produced by Actinobacillus actinomycetemcomitans has been implicated in the etiology of juvenile periodontitis. To initiate a genetic analysis of the role of this protein in disease, we have cloned the leukotoxin gene in Escherichia coli. Recombinant colonies carrying toxin gene sequences were isolated by screening a genomic A. actinomycetemcomitans library with a DNA probe for the leukotoxin gene from a related bacterium, Pasteurella haemolytica. To demonstrate that the cloned A. actinomycetemcomitans DNA contained a functional leukotoxin gene, protein extracts of E. coli containing the A. actinomycetemcomitans clone were tested directly for leukotoxic activity against human cell lines in chromium release assays. A construct containing the entire cloned region produced a functional toxin. No cytotoxicity was seen when extracts from cells containing plasmids with deletions in the putative coding region were used. Furthermore, the toxin produced by the cloned gene has the same target cell specificity as the leukotoxin extracted directly from A. actinomycetemcomitans. These results indicate that sequences encoding a functional leukotoxin have been cloned and are expressed in E. coli. Southern blot analysis of DNA from leukotoxin-producing (Lkt+) and non-leukotoxin-producing (Lkt-) strains indicated that the Lkt- strain also contained a copy of the gene. Images PMID:2707855

  1. Actinomycetemcomitin: a new bacteriocin produced by Aggregatibacter (Actinobacillus) actinomycetemcomitans.

    PubMed

    Lima, Francisca Lúcia; de Carvalho, Maria Auxiliadora Roque; Apolônio, Ana Carolina Morais; Bemquerer, Marcelo Porto; Santoro, Marcelo Matos; Oliveira, Jamil Silvano; Alviano, Celuta Sales; Farias, Luiz de Macêdo

    2008-02-01

    Aggregatibacter (Actinobacillus) actinomycetemcomitans P(7-20) strain isolated from a periodontally diseased patient has produced a bacteriocin (named as actinomycetemcomitin) that is active against Peptostreptococcus anaerobius ATCC 27337. Actinomycetemcomitin was produced during exponential and stationary growth phases, and its amount decreased until it disappeared during the decline growth phase. It was purified by ammonium sulphate precipitation (30-60% saturation), and further by FPLC (mono-Q ionic exchange and Phenyl Superose hydrophobic interaction) and HPLC (C-18 reversed-phase). This bacteriocin loses its activity after incubation at a pH below 7.0 or above 8.0, following heating for 30 min at 45 degrees C, and after treatment with proteolytic enzymes such as trypsin, alpha-chymotrypsin, and papain. Actinomycetemcomitin has a molecular mass of 20.3 KDa and it represents a new bacteriocin from A. actinomycetemcomitans.

  2. The presence of phage-infected Actinobacillus actinomycetemcomitans in localized juvenile periodontitis patients.

    PubMed

    Preus, H R; Olsen, I; Namork, E

    1987-11-01

    Electron microscopy revealed 2 different types of bacteriophages isolated from Actinobacillus actinomycetemcomitans colonizing exclusively diseased sites in 4 patients with localized juvenile periodontitis (LJP). All sites infected with phage were undergoing periodontal destruction, as judged from consecutive routine radiographs. The phages isolated had a wide host range as assessed from their ability to infect a series of reference strains of A. actinomycetemcomitans. A 5th patient harboured non-infected A. actinomycetemcomitans in a surgically treated site which had undergone no bone destruction during the last 12 months. The present findings suggested that the pathogenic potential of A. actinomycetemcomitans in LJP may increase due to phage infection.

  3. Update on Actinobacillus Actinomycetemcomitans and Porphyromonas gingivalis in human periodontal disease.

    PubMed

    Slots, J

    1999-10-01

    Actinobacillus actinomycetemcomitans is an important pathogen of periodontitis in young individuals. Porphyromonas gingivalis is a major pathogen of severe adult periodontitis. A. actinomycetemcomitans and P. gingivalis can be transmitted from family member to family member and may cause periodontitis in the recipient individual. In the USA, A. actinomycetemcomitans occurs more frequently in Hispanics and Asians than in Caucasians. P. gingivalis is more common in Hispanics, Asians and Blacks than in Caucasians. A. actinomycetemcomitans and P. gingivalis strains differ in genotype, serotype, toxin and enzyme production, and cellular invasiveness. Variation in virulence may help explain differing clinical outcomes of periodontal A. actinomycetemcomitans and P. gingivalis infections. A. actinomycetemcomitans and P. gingivalis cannot be eradicated from the great majority of deep periodontal pockets by mechanical debridement alone. A. actinomycetemcomitans may be removed from subgingival sites by adjunctive systemic amoxicillin-metronidazole or other appropriate antibiotic therapies. Subgingival eradication of P. gingivalis may require periodontal surgery as well as antibiotic therapy.

  4. Cellular fatty acid and soluble protein composition of Actinobacillus actinomycetemcomitans and related organisms.

    PubMed Central

    Calhoon, D A; Mayberry, W R; Slots, J

    1981-01-01

    The cellular fatty acid and protein content of twenty-five representative strains of Actinobacillus actinomycetecomitans isolated from juvenile and adult periodontitis patients was compared to that of 15 reference strains of oral and nonoral Actinobacillus species and Haemophilus aphrophilus. Trimethylsilyl derivatives of the fatty acid methyl esters were analyzed by gas-liquid chromatography. The predominant fatty acids of all 40 strains examined were 14:0, 3-OH 14:0, 16 delta, and 16:0. Actinobacillus seminis (ATCC 15768) was unlike the other strains examined because of a greater amount of 14:0 detected. The soluble protein analysis using polyacrylamide gel electrophoresis revealed that A. actinomycetemcomitans, H. aphrophilus, and nonoral Actinobacillus species possessed distinct protein profiles attesting to the validity of separating these organisms into different species. Established biotypes of A. actinomycetemcomitans could not be differentiated on the basis of fatty acid or protein profiles. PMID:7287893

  5. Adhesion of Actinobacillus actinomycetemcomitans to a human oral cell line.

    PubMed Central

    Mintz, K P; Fives-Taylor, P M

    1994-01-01

    Two quantitative, rapid assays were developed to study the adhesion of Actinobacillus actinomycetemcomitans, an oral bacterium associated with periodontal disease, to human epithelial cells. The human oral carcinoma cell line KB was grown in microtiter plates, and adherent bacteria were detected by an enzyme-linked immunosorbent assay with purified anti-A. actinomycetemcomitans serum and horseradish peroxidase-conjugated secondary antibody or [3H]thymidine-labeled bacteria. Adhesion was found to be time dependent and increased linearly with increasing numbers of bacteria added. Variation in the level of adhesion was noted among strains of A. actinomycetemcomitans. Adhesion was not significantly altered by changes in pH (from pH 5 to 9) but was sensitive to sodium chloride concentrations greater than 0.15 M. Pooled human saliva was inhibitory for adhesion when bacteria were pretreated with saliva before being added to the cells. Pretreatment of the KB cells with saliva did not inhibit adhesion. Protease treatment of A. actinomycetemcomitans reduced adhesion of the bacteria to KB cells. The data are consistent with the hypothesis that a protein(s) is required for bacterial adhesion and that host components may play a role in modulating adhesion to epithelial cells. Images PMID:8063383

  6. Cellular fatty acid composition of Actinobacillus actinomycetemcomitans and Haemophilus aphrophilus.

    PubMed Central

    Braunthal, S D; Holt, S C; Tanner, A C; Socransky, S S

    1980-01-01

    Strains of Actinobacillus actinomycetemcomitans isolated from deep pockets of patients with juvenile periodontitis were analyzed for their content of cellular fatty acids. Oral Haemophilus strains, morphologically and biochemically similar to Haemophilus aphrophilus, were also examined for their content of cellular fatty acids. The extractable lipids of the actinobacilli represented approximately 10% of the cell dry weight, with the bound lipids representing 2 to 5%. The major fatty acids consisted of myristic (C14:0) and palmitic (C16:0) acids and a C16:1 acid, possibly palmitoleic acid, accounting for 21, 35, and 31% of the total extractable fatty acids, respectively. Haemophilus strains had a similar cellular fatty acid content. PMID:7430333

  7. Identification of an immunoglobulin Fc receptor of Actinobacillus actinomycetemcomitans.

    PubMed Central

    Mintz, K P; Fives-Taylor, P M

    1994-01-01

    Actinobacillus actinomycetemcomitans expresses proteins that bind to the Fc portion of immunoglobulins. The immunoglobulin Fc receptors on the surface of A. actinomycetemcomitans were detected by the binding of biotinylated human or murine Fc molecules to strain SUNY 465 adsorbed to the bottom of microtiter wells. Biotinylated Fc binding was inhibited by unlabeled Fc molecules and human plasma. Fc receptors were identified by the binding of biotinylated Fc molecules to bacterial membrane proteins separated by polyacrylamide gel electrophoresis and transferred to nitrocellulose. Multiple bands were identified, and the major Fc-binding protein was determined to be a heat-modifiable protein. This protein migrated with approximate molecular weights of 25,000 and 32,000 (unheated and heated, respectively). Amino-terminal sequence analysis of this protein revealed a sequence identical to the heat-modifiable protein described for A. actinomycetemcomitans ATCC 43718. This protein sequence exhibits significant homology with the N termini of outer membrane protein A (OmpA) of Escherichia coli and related OmpA-like proteins from other gram-negative bacteria. Images PMID:7927715

  8. [Role of Actinobacillus actinomycetemcomitans in human infection].

    PubMed

    Giglio, C; Aránguiz, V; Giglio, M S; Fernández, A

    1990-04-01

    Actinobacillus actinomycetemcomitans (AA), is a cocobacillus thin and small, non motile, uncapsulate and capnophilic. AA, is: one of the species encountered in the mouth's comensal flora being able to be isolated in gingival crevices culture and oral mucosa in a 20% of the healthy population. An important number of pathogenic factors make it well equipped, to protect itself from host's defense mechanisms, and to destroy the periodontal tissue. Between the most important we find lipopolisacarides and leucotoxines which promote tisular invasion and destructive qualities of this microorganism. Since 1912, there are numerous reports of infectious process associated to it, between which we find: endocarditis in native and prothesic valve, soft tissues abscess, pneumonia, brain's abscess, urethritis, vertebral osteomielitis, thyroid's abscess, pericarditis and periodontal juvenile illness, being this one in which its isolation is more frequent. In vitro, AA is very susceptible to tetracicline. This antibiotic reaches high concentrations in gingival crevices, has significant affinity to the alveolar bone and contributes to protect the collagen. These special feature make them the election drug in periodontal disease produced by this microorganism.

  9. Serology of oral Actinobacillus actinomycetemcomitans and serotype distribution in human periodontal disease.

    PubMed Central

    Zambon, J J; Slots, J; Genco, R J

    1983-01-01

    Actinobacillus actinomycetemcomitans from the human oral cavity was serologically characterized with rabbit antisera to the type strain NCTC 9710; a number of reference strains, including Y4, ATCC 29522, ATCC 29523, ATCC 29524, NCTC 9709; and our own isolates representative of each of 10 biotypes. Using immunoabsorbed antisera, we identified three distinct serotypes by immunodiffusion and indirect immunofluorescence. Serotype a was represented by ATCC 29523 and SUNYaB 75; serotype b was represented by ATCC 29522 and Y4; and serotype c was represented by NCTC 9710 and SUNYaB 67. Indirect immunofluorescence revealed no reaction between the three A. actinomycetemcomitans serotype-specific antisera and 62 strains representing 23 major oral bacterial species. Distinct from the serotype antigens were at least one A. actinomycetemcomitans species common antigen and an antigen shared with other Actinobacillus species, Haemophilus aphrophilus, and Haemophilus paraphrophilus. All serotype a A. actinomycetemcomitans strains failed to ferment xylose, whereas all serotype b organisms fermented xylose. Serotype c included xylose-positive as well as xylose-negative strains. A total of 301 isolates of A. actinomycetemcomitans from the oral cavity of 74 subjects were serologically categorized by indirect immunofluorescence with serotype-specific rabbit antisera. Each patient harbored only one serotype of A. actinomycetemcomitans. Fourteen healthy subjects, five diabetics, and seventeen adult periodontitis patients exhibited serotypes a and b in approximately equal frequency, whereas serotype c was found less frequently. In contrast, in 29 localized juvenile periodontitis patients, the incidence of serotype b was approximately two times higher than that of serotypes a or c, suggesting a particularly high periodontopathic potential of A. actinomycetemcomitans serotype b strains. In subjects infected with A. actinomycetemcomitans, serum antibodies were detected to the serotype

  10. Identification of Actinobacillus actinomycetemcomitans by leukotoxin gene-specific hybridization and polymerase chain reaction assays.

    PubMed Central

    Tønjum, T; Haas, R

    1993-01-01

    Eleven strains of Actinobacillus actinomycetemcomitans isolated from cases of systemic infections, local abscesses, and periodontitis were identified by genetic assays using the leukotoxin gene as the target. We have developed a polymerase chain reaction (PCR) assay, based on the leukotoxin structural gene of this pathogen, which clearly identified all tested strains of A. actinomycetemcomitans and separated them from the closely related Haemophilus aphrophilus as well as other bacterial species. Furthermore, DNA-DNA hybridization was performed with the cloned partial leukotoxin structural gene (lktA) as a probe, which again clearly distinguished A. actinomycetemcomitans from H. aphrophilus, parts of the normal oral flora, and species harboring RTX (repeats in toxin) family-related cytotoxins. The PCR fragment amplified from the leukotoxin structural gene gave results similar to those given by the cloned leukotoxin gene when used as a probe in hybridization experiments. The hybridization and PCR assays described here are fundamental improvements for the identification of A. actinomycetemcomitans. Images PMID:8349764

  11. Requirements for invasion of epithelial cells by Actinobacillus actinomycetemcomitans.

    PubMed Central

    Sreenivasan, P K; Meyer, D H; Fives-Taylor, P M

    1993-01-01

    Actinobacillus actinomycetemcomitans, an oral bacterium implicated in human periodontal disease, was recently demonstrated to invade cultured epithelial cells (D. H. Meyer, P. K. Sreenivasan, and P. M. Fives-Taylor, Infect. Immun. 59:2719-2726, 1991). This report characterizes the requirements for invasion of KB cells by A. actinomycetemcomitans. The roles of bacterial and host factors were investigated by using selective agents that influence specific bacterial or host cell functions. Inhibition of bacterial protein synthesis decreased invasion, suggesting the absence of a preformed pool of proteins involved in A. actinomycetemcomitans invasion. Inhibition of bacterial and eukaryotic energy synthesis also decreased invasion, confirming that A. actinomycetemcomitans invasion is an active process. Bacterial adherence to KB cells was indicated by scanning electron microscopy of infected KB cells. Further, the addition of A. actinomycetemcomitans-specific serum to the bacterial inoculum reduced invasion substantially, suggesting a role for bacterial attachment in invasion. Many of the adherent bacteria invaded the epithelial cells under optimal conditions. Inhibitors of receptor-mediated endocytosis inhibited invasion by A. actinomycetemcomitans. Like that of many facultatively intracellular bacteria, A. actinomycetemcomitans invasion was not affected by eukaryotic endosomal acidification. These are the first published observations describing the requirements for epithelial cell invasion by a periodontopathogen. They demonstrate that A. actinomycetemcomitans utilizes a mechanism similar to those used by many but not all invasive bacteria to gain entry into eukaryotic cells. Images PMID:8454326

  12. Activation of rat B lymphocytes by Actinobacillus actinomycetemcomitans.

    PubMed Central

    Yoshie, H; Taubman, M A; Ebersole, J L; Olson, C L; Smith, D J; Pappo, J

    1985-01-01

    We examined the lymphoproliferative responses of cervical lymphocytes and splenocytes of homozygous (rnu/rnu) congenitally athymic nude and normal heterozygous (rnu/+) Rowett rats to whole cells of Actinobacillus actinomycetemcomitans, a suspected periodontal disease pathogen. Previously sensitized cells from immunized only, infected only, or immunized and infected, normal rats demonstrated proliferation in response to formalinized A. actinomycetemcomitans, but cells from nude rats did not proliferate. The maximum antigenic response was observed at day 5 of culture. A. actinomycetemcomitans caused cervical lymphocytes and splenocytes from untreated naive normal and nude rats to undergo increased DNA synthesis at day 2 of culture. Highly enriched nonsensitized spleen T cells prepared on a nylon wool column did not respond to A. actinomycetemcomitans, whereas enriched nonsensitized B cells proliferated. Differences in response were probably not attributable to contributions from macrophages in the T- or B-cell populations, since macrophage percentages were approximately the same in both preparations. T-cell reconstitution of nude rats with neonatal thymus cells from rnu/+rats resulted in partial recovery of T-cell function but had no effect on the mitogenic response to A. actinomycetemcomitans. It is suggested that the antigenic responses to A. actinomycetemcomitans are dependent on T cells and that A. actinomycetemcomitans cells have mitogenic activity for B cells. The potential importance of these findings in periodontal disease is discussed. PMID:3871196

  13. Presence of bacteriophage Aa phi 23 correlates with the population genetic structure of Actinobacillus actinomycetemcomitans.

    PubMed

    Haubek, D; Willi, K; Poulsen, K; Meyer, J; Kilian, M

    1997-02-01

    Several bacteriophages associated with the oral bacterium Actinobacillus actinomycetemcomitans have been identified. Lysogeny might affect the virulence of this bacterium, which has been implicated in the etiology of juvenile and adult periodontitis. We have determined the presence of bacteriophage Aa phi 23-related DNA sequences among 185 A. actinomycetemcomitans strains belonging to 2 well-characterized collections and have related the findings to the population genetic structure of the collections. 2 cloned Aa phi 23-specific DNA probes were used in Southern blot hybridization experiments to detect homologous sequences in whole-cell DNA of the strains. DNA from 65 (35%) of the 185 strains hybridized to either of the DNA probes. The majority (74%) of the hybridizing strains showed an identical hybridization pattern, indicating presence of phage Aa phi 23. Whole-cell DNA from the remaining hybridizing strains hybridized to the probes with different patterns, indicating that DNA sequences related to but different from phage Aa phi 23 occur in these strains. The majority (81%) of the strains which harbored phage Aa phi 23 were of serotype a, whereas serotype d strains appeared to be resistant to infection with this phage. There was a clear correlation between hybridization patterns and genetic subdivisions based on our previous population genetic analyses of A. actinomycetemcomitans. However, there was no significant correlation between occurrence of Aa phi 23 among A. actinomycetemcomitans strains and the periodontal status of the patients from whom the isolates were obtained, suggesting that this bacteriophage does not significantly influence the virulence of A. actinomycetemcomitans.

  14. Structural proteins of the Actinobacillus actinomycetemcomitans bacteriophage phi Aa.

    PubMed

    Stevens, R H; Hammond, B F; Fine, D H

    1990-08-01

    øAa is an A1 morphotype bacteriophage which infects certain strains of Actinobacillus actinomycetemcomitans. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis of dissociated, purified phi Aa particles revealed 7 major structural proteins (P1-P7) ranging in size from 17.5 to 52.7 kilodaltons (Kd). Treatment of the intact phage particles with 67% dimethyl sulfoxide (DMSO) resulted in the separation of the virion head and tail subunits. Purification of the head subunits was accomplished by sucrose density gradient centrifugation of the DMSO-treated phage particles. The purified head subunits were composed of a single protein having an electrophoretic mobility which corresponded to a 39.5 Kd protein (P3) of the intact virus. Raising the pH of a purified phi Aa suspension to 12.7 disrupted the head subunits, as well as the tail tube and tail fibers, releasing intact contractile tail sheaths. The tail sheaths were collected by centrifugation. The purified tail sheaths were analyzed by SDS-PAGE and were found to be composed of two proteins (P1 and P2) having molecular weights of 52.7 and 41.2 Kd respectively. The location of each of the 4 remaining major structural proteins in the phi Aa virion remains to be determined.

  15. Evidence for invasion of a human oral cell line by Actinobacillus actinomycetemcomitans.

    PubMed Central

    Meyer, D H; Sreenivasan, P K; Fives-Taylor, P M

    1991-01-01

    Actinobacillus actinomycetemcomitans, an oral bacterial species associated with periodontal disease, was found to invade human cell lines. Invasion was demonstrated by recovery of viable organisms from gentamicin-treated KB cell monolayers and by light and electron microscopy. Internalization occurred through a cytochalasin D-sensitive process. Invasion efficiencies of some A. actinomycetemcomitans strains were comparable to those of invasive members of the family Enterobacteriaceae. Differences in invasiveness were correlated with bacterial colonial morphology. Smooth variants invaded more proficiently than rough variants. A. actinomycetemcomitans can undergo a smooth-to-rough colonial morphology shift which results in the loss of invasiveness. Coordinated regulation of genes involved in the rough-to-smooth phenotypic transitions may play a role in the episodic nature of periodontal disease. Images PMID:1855989

  16. Studies of leukotoxin from Actinobacillus actinomycetemcomitans using the promyelocytic HL-60 cell line.

    PubMed Central

    Zambon, J J; DeLuca, C; Slots, J; Genco, R J

    1983-01-01

    The promyelocytic HL-60 cell line was examined for susceptibility to leukotoxin from Actinobacillus actinomycetemcomitans. Strains of A. actinomycetemcomitans which caused lysis of human peripheral blood polymorphonuclear leukocytes also lysed HL-60 cells as determined by release of intracellular lactate dehydrogenase. The killing of HL-60 cells by A. actinomycetemcomitans was dose dependent and temperature dependent, reached maximal levels after 45 min of incubation, and was inhibited by rabbit antisera to A. actinomycetemcomitans. Of 100 oral isolates of A. actinomycetemcomitans from 55 subjects, 16% from 11 healthy subjects, 43% from 13 adult periodontitis patients, 75% from 4 insulin-dependent diabetics, 66% from 2 generalized juvenile periodontitis patients, and 55% from 25 localized juvenile periodontitis patients produced leukotoxin. The same subject could harbor both leukotoxin-producing and -nonproducing isolates. The significantly higher proportion of leukotoxin-producing isolates in the disease groups compared with the healthy group is consistent with the hypothesis that leukotoxin from A. actinomycetemcomitans is an important virulence factor in the pathogenesis of certain forms of periodontal disease. PMID:6572616

  17. Identification of genomic clonal types of Actinobacillus actinomycetemcomitans by restriction endonuclease analysis.

    PubMed Central

    Han, N; Hoover, C I; Winkler, J R; Ng, C Y; Armitage, G C

    1991-01-01

    To evaluate its utility in discriminating different strains, restriction endonuclease analysis was applied to 12 strains of Actinobacillus actinomycetemcomitans (3 serotype a, 5 serotype b, and 4 serotype c strains). DNA isolated from each strain was digested by 12 different restriction endonucleases, and the electrophoretic banding patterns of the resulting DNA fragments were compared. The DNA fragment patterns produced by SalI, XhoI, and XbaI for the 12 A. actinomycetemcomitans strains were simple (less than 30 bands) and allowed us to recognize easily 10 distinct genomic clonal types. The three serotype a strains exhibited distinctly different clonal types from one another, the five serotype b strains exhibited an additional four distinct clonal types, and the four serotype c strains showed another three different clonal types. The other endonucleases tested were less useful in typing A. actinomycetemcomitans. We conclude that restriction endonuclease analysis is a powerful tool for typing and discerning genetic heterogeneity and homogeneity among A. actinomycetemcomitans strains. It should, therefore, be very useful for epidemiologic studies. Images PMID:1761677

  18. In vitro susceptibilities of Actinobacillus actinomycetemcomitans to a number of antimicrobial combinations.

    PubMed Central

    Pavicić, M J; van Winkelhoff, A J; de Graaff, J

    1992-01-01

    The in vitro susceptibilities of Actinobacillus actinomycetemcomitans to 14 antimicrobial combinations were studied by using the checkerboard titration technique. The results, expressed as the range of the fractional inhibitory concentration indices, were as follows: for metronidazole or its hydroxymetabolite combined with cefixime, 0.2 to 0.6; for moxalactam, 0.2 to 0.6; for penicillin G, 0.3 to 0.6; for tobramycin, 0.8 to 2.0; for erythromycin, 0.8 to 1.7; for ciprofloxacin, 0.2 to 0.6; for tetracycline, 0.8 to 1.2. Our observations indicated that the beta-lactam antibiotics as well as ciprofloxacin act synergistically with both metronidazole and its hydroxymetabolite against A. actinomycetemcomitans. Synergistic interactions were independent of the individual MICs of the antibiotics tested. Erythromycin, tobramycin, and tetracycline combined with either metronidazole or its hydroxymetabolite showed additive to indifferent effects against the five strains of A. actinomycetemcomitans, with the fractional inhibitory concentration indices ranging from 0.8 to 2.0. A. actinomycetemcomitans was found to be highly susceptible to ciprofloxacin (MIC of ciprofloxacin for 90% of strains tested, 0.010 micrograms/ml) and cefixime (MIC of cefixime for 90% of strains tested, 0.8 micrograms/ml). The results indicate that in patients who are allergic to penicillin, cefixime and ciprofloxacin may be useful alternative antibiotics in combination with metronidazole for the treatment of A. actinomycetemcomitans-associated periodontitis. PMID:1482130

  19. Avidity of antibody responses to Actinobacillus actinomycetemcomitans in periodontitis.

    PubMed Central

    O'Dell, D S; Ebersole, J L

    1995-01-01

    We designed a study to examine the serum IgG antibody avidity characteristics in: (i) normal subjects (N); (ii) Actinobacillus actinomycetemcomitans-infected adult periodontitis (AP Aa+); (iii) A. actinomycetemcomitans-infected localized juvenile periodontitis (LJP Aa+); and (iv) AP subjects (AP) with various antibody patterns and disease presentation. Although there were significant elevations in antibody levels for AP Aa+ and LJP Aa+ patients compared with AP and normal patients (P < 0.0001), there were no significant differences in the avidity indices (AI). Correlations of antibody levels to avidity revealed that functional activity of the antibody as measured by avidity was independent of antibody levels. Increasing antibody levels correlated with an increase in the number of infected sites, yet there was a trend for A1 to decrease with increased infection. Avidity indices for all patient groups did not appear to show a strong biologic relationship to plaque; however, in AP Aa+ and LJP Aa+ patients there was a generally positive relationship between avidity and bleeding on probing or pocket depth. In AP Aa+ and LJP Aa+ patients, and in AP patients there was a positive relationship of avidity through a threshold of approximately 8 active disease sites. This study hypothesized that antibody avidity to A. actinomycetemcomitans could help to explain the relationship between the active host response and chronic infection with this pathogen. The results provide evidence that both antibody levels and avidity may contribute to the variation in host resistance to infection and disease associated with A. actinomycetemcomitans. PMID:7648712

  20. Oxidative and nonoxidative killing of Actinobacillus actinomycetemcomitans by human neutrophils.

    PubMed Central

    Miyasaki, K T; Wilson, M E; Brunetti, A J; Genco, R J

    1986-01-01

    Actinobacillus actinomycetemcomitans is a facultative gram-negative microorganism which has been implicated as an etiologic agent in localized juvenile periodontitis and in subacute bacterial endocarditis and abscesses. Although resistant to serum bactericidal action and to oxidant injury mediated by superoxide anion (O2-) and hydrogen peroxide (H2O2), this organism is sensitive to killing by the myeloperoxidase-hydrogen peroxide-chloride system (K.T. Miyasaki, M.E. Wilson, and R.J. Genco, Infect. Immun. 53:161-165, 1986). In this study, we examined the sensitivity of A. actinomycetemcomitans to killing by intact neutrophils under aerobic conditions, under anaerobic conditions, and under aerobic conditions in the presence of the heme-protein inhibitor sodium cyanide. Intact neutrophils killed opsonized A. actinomycetemcomitans under aerobic and anaerobic conditions, and the kinetics of these reactions indicated that both oxidative and nonoxidative mechanisms were operative. Oxidative mechanisms contributed significantly, and most of the killing attributable to oxidative mechanisms was inhibited by sodium cyanide, which suggested that the myeloperoxidase-hydrogen peroxide-chloride system participated in the oxidative process. We conclude that human neutrophils are capable of killing A. actinomycetemcomitans by both oxygen-dependent and oxygen-independent pathways, and that most oxygen-dependent killing requires myeloperoxidase activity. PMID:3013778

  1. A longitudinal microbiological investigation of Actinobacillus actinomycetemcomitans and Eikenella corrodens in juvenile periodontitis.

    PubMed Central

    Mandell, R L

    1984-01-01

    Longitudinal clinical and microbiological monitoring of subjects with localized juvenile periodontitis indicated that Actinobacillus actinomycetemcomitans and Eikenella corrodens were significantly associated (P less than 0.05) with active tissue destruction. PMID:6381313

  2. Intra- and Interspecies Regulation of Gene Expression by Actinobacillus actinomycetemcomitans LuxS

    PubMed Central

    Fong, Karen P.; Chung, Whasun O.; Lamont, Richard J.; Demuth, Donald R.

    2001-01-01

    The cell density-dependent control of gene expression is employed by many bacteria for regulating a variety of physiological functions, including the generation of bioluminescence, sporulation, formation of biofilms, and the expression of virulence factors. Although periodontal organisms do not appear to secrete acyl-homoserine lactone signals, several species, e.g., Porphyromonas gingivalis, Prevotella intermedia, and Fusobacterium nucleatum, have recently been shown to secrete a signal related to the autoinducer II (AI-2) of the signal system 2 pathway in Vibrio harveyi. Here, we report that the periodontal pathogen Actinobacillus actinomycetemcomitans expresses a homolog of V. harveyi luxS and secretes an AI-2-like signal. Cell-free conditioned medium from A. actinomycetemcomitans or from a recombinant Escherichia coli strain (E. coli AIS) expressing A. actinomycetemcomitans luxS induced luminescence in V. harveyi BB170 >200-fold over controls. AI-2 levels peaked in mid-exponential-phase cultures of A. actinomycetemcomitans and were significantly reduced in late-log- and stationary-phase cultures. Incubation of early-log-phase A. actinomycetemcomitans cells with conditioned medium from A. actinomycetemcomitans or from E. coli AIS resulted in a threefold induction of leukotoxic activity and a concomitant increase in leukotoxin polypeptide. In contrast, no increase in leukotoxin expression occurred when cells were exposed to sterile medium or to conditioned broth from E. coli AIS−, a recombinant strain in which luxS was insertionally inactivated. A. actinomycetemcomitans AI-2 also induced expression of afuA, encoding a periplasmic iron transport protein, approximately eightfold, suggesting that LuxS-dependent signaling may play a role in the regulation of iron acquisition by A. actinomycetemcomitans. Finally, A. actinomycetemcomitans AI-2 added in trans complemented a luxS knockout mutation in P. gingivalis by modulating the expression of the lux

  3. Lytic sensitivity of Actinobacillus actinomycetemcomitans Y4 to lysozyme.

    PubMed Central

    Iacono, V J; Boldt, P R; MacKay, B J; Cho, M I; Pollock, J J

    1983-01-01

    The ability of both human and hen egg white lysozymes to lyse Actinobacillus actinomycetemcomitans Y4 was investigated. Lysis was followed optically at 540 nm by measuring the percent reduction in turbidity of freshly harvested log-phase cells suspended in Tris-maleate buffers within a wide range of pH (5.2 to 8.5) and molarity (0.01 to 0.2 M) and containing various amounts of enzyme and EDTA. In several instances, treated microorganisms were subsequently examined in thin sections by electron microscopy. Reductions in turbidity and clearing of suspensions occurred with small amounts of lysozyme (less than 1 microgram) under relatively alkaline conditions and at low ionic strength and in the presence of small amounts of EDTA (greater than 0.01 mM). Under the most alkaline conditions, EDTA alone effected turbidity reductions similar to those observed in the presence of lysozyme, which suggested that EDTA not only increased outer membrane permeability but also caused cell lysis. Ultrastructural analysis did not always correspond to turbidimetric observations. Cell lysis was virtually complete in suspensions containing both lysozyme and EDTA. However, in contrast to turbidimetric findings, a significant percentage of cells (greater than 25%) was lysed in the presence of lysozyme alone. Furthermore, significant damage occurred in the presence of EDTA alone. Spheroplast-like cell ghosts were present which surrounded condensed cytoplasm or relatively clear spaces. These findings further support the concept of the requirement for electron microscopy to assess lytic damage in addition to turbidimetric and biochemical methods. Our results are the first to demonstrate the remarkable sensitivity of A. actinomycetemcomitans Y4 to lysozyme and to show that EDTA not only affects outer membrane permeability but effects cell lysis, possibly through activation of autolytic enzymes at the cytoplasmic membrane. The exquisite sensitivity of A. actinomycetemcomitans Y4 to lysis could be

  4. Occurrence of temperate bacteriophages in different Actinobacillus actinomycetemcomitans serotypes isolated from periodontally healthy individuals.

    PubMed

    Willi, K; Sandmeier, H; Asikainen, S; Saarela, M; Meyer, J

    1997-02-01

    The occurrence of temperate bacteriophages was studied in 34 isolates of Actinobacillus actinomycetemcomitans derived from 27 periodontally healthy Finnish individuals both by lysis/plaque assays and by DNA hybridizations. In addition the serotype, the ribotype and the arbitrarily primed polymerase chain reaction (AP-PCR) profile were determined for each A. actinomycetemcomitans strain. Fourteen isolates showed hybridization patterns very similar to that of a known lysogen when probed with the genome of the previously characterized temperate phage Aa phi 23. Only 6 of these 14 strains had produced lysis or single plaques on suitable indicator strains. Phage Aa phi 247 derived from one of these lysogens was indistinguishable from Aa phi 23 by electron microscopy, and the genomes showed highly related DNA hybridization patterns. The remaining 20 isolates exhibited hybridization patterns very different from that of Aa phi 23 DNA. Seven of these strains also gave lysis or single plaques, suggesting that 21 of the 34 strains were lysogenic. These data indicate that the prophages per se do not represent a virulence factor exclusively associated with periodontal disease. Presence of an Aa phi 23-related prophage correlated with serotype a and AP-PCR type 1 of the bacterial host. This may indicate that Aa phi 23 and related phages have a limited host range.

  5. Actinobacillus actinomycetemcomitans serotype e--biotypes, genetic diversity and distribution in relation to periodontal status.

    PubMed

    Doğan, B; Saarela, M H; Jousimies-Somer, H; Alaluusua, S; Asikainen, S

    1999-04-01

    Actinobacillus actinomycetemcomitans isolates from 356 individuals were screened for identification of serotype e in order to investigate its distribution in relation to periodontal status. From subjects with serotype e, 1-6 isolates per subject (n = 61) were genotyped using arbitrarily primed-polymerase chain reaction (AP-PCR) and apaH gene polymerase chain reaction-restriction fragment-length polymorphism (PCR-RFLP) analysis to determine the genetic heterogeneity within the serotype. Furthermore, one serotype e strain per subject was tested for fermentation of 8 carbohydrates for biotyping. Among patients with adult periodontitis (n = 219), localized juvenile periodontitis (n = 55) and other forms of early-onset periodontitis (n = 18) serotypes b, a and c, respectively, were the most frequently detected serotypes. Non-periodontitis subjects (n = 64) were predominantly colonized with serotype c. Serotype e was found in 30 (14%) adult periodontitis patients, 2 (11%) early-onset periodontitis patients and in 5 (8%) non-periodontitis individuals, but in none of the 55 localized juvenile periodontitis patients. AP-PCR distinguished 3 and apaH gene PCR-RFLP analysis 2 genotypes among the 61 A. actinomycetemcomitans serotype e isolates, one genotype per subject. The AP-PCR genotypes 1 and 3 represented the apaH genotype 1 and the AP-PCR genotype 2 the apaH genotype 2. On the basis of variable fermentation of galactose and xylose, 3 biotypes among A. actinomycetemcomitans serotype e were established. Contrary to the absence of A. actinomycetemcomitans serotype e in localized juvenile periodontitis patients, its detection frequency was comparable among other forms of periodontitis and periodontal health. Clinical serotype e isolates form at least 2 genetic types and 3 biotypes.

  6. Identification and characterization of genetic cluster groups of Actinobacillus actinomycetemcomitans isolated from the human oral cavity.

    PubMed Central

    DiRienzo, J M; McKay, T L

    1994-01-01

    Actinobacillus actinomycetemcomitans is recognized as a primary pathogen in localized juvenile periodontitis (LJP). Restriction fragment length polymorphisms (RFLP) within a collection of subgingival plaque isolates of this bacterium were identified and characterized as the first step in understanding the pathogenesis of LJP. Over 800 isolates, from members of 18 families (LJP families) with at least one member with active LJP or a documented history of the disease and one or more siblings, less than 13 years of age, having no clinical evidence of LJP and 32 healthy control subjects, were assigned to one of 13 distinct RFLP groups (II to XIV) by using a previously characterized 4.7-kb DNA probe cloned from the reference strain FDC Y4. Isolates belonging to RFLP groups II, IV, V, and XIII predominated subgingival sites in the subjects. Members of RFLP groups II, IV, VII, VIII, X, and XI were recovered only from LJP family subjects, while group XIII and XIV variants were found exclusively in healthy controls. A synthetic oligonucleotide, homologous to the 5' end of the leukotoxin gene (lktA), and the A. actinomycetemcomitans plasmid, pVT745, were tested for their abilities to subdivide the 13 RFLP groups. The leukotoxin probe specifically identified all RFLP group II variants because of the absence of a HindIII site in the upstream noncoding region of the lkt gene complex. The plasmid probe was not as selective but may be useful for identifying clinical isolates belonging to RFLP group I. The use of these probes for the identification of genetic variants of A. actinomycetemcomitans that may be preferentially colonize diseased and healthy subjects will facilitate the study of the role of this important pathogen in periodontal diseases. Images PMID:7907346

  7. Gene cloning of an Actinobacillus actinomycetemcomitans Y4 antigen which reacts with peripheral blood sera in patients with advanced destructive periodontitis.

    PubMed

    Arakawa, S; Hata, S; Ishikawa, I; Tsuchida, N

    1990-01-01

    Actinobacillus actinomycetemcomitans has been implicated in the aetiology of juvenile periodontitis and advanced destructive periodontitis. Levels of IgG antibody against A. actinomycetemcomitans in peripheral blood sera of patients with advanced destructive periodontitis are high, as are those against Bacteroides gingivalis. To clone the genes of antigens reactive with sera of such patients, a library of the A. actinomycetemcomitans strain Y4 DNA in lambda L47 was constructed and then screened, using an immunochemical detection method, with serum from a patient with the advanced disease. Six clones from among nearly 1000 reacted with the serum and also with that of another patient. They were designated 3, 4, 6, 7, 8 and 9. Restriction enzyme and Southern blot analyses indicated that clones 8 and 9 were identical and that all the clones were overlapping because they shared in common the 4 and 5 kbp HincII DNA fragments of A. actinomycetemcomitans. The cloned DNA fragment hybridized to the DNA of two other strains of A. actinomycetemcomitans but not to those of six periodontopathic bacteria examined. These findings suggest that a DNA sequence encoding an A. actinomycetemcomitans strain Y4 antigen strongly reactive with sera of patients with advanced destructive periodontitis was cloned. This sequence is present specifically in A. actinomycetemcomitans but not in other bacteria isolated from patients with periodontal diseases. Thus, the cloned DNA could serve as a probe for the diagnosis of periodontitis.

  8. Killing of human myelomonocytic leukemia and lymphocytic cell lines by Actinobacillus actinomycetemcomitans leukotoxin.

    PubMed Central

    Simpson, D L; Berthold, P; Taichman, N S

    1988-01-01

    The purified leukotoxin of Actinobacillus actinomycetemcomitans kills human leukemic cell lines (e.g., HL-60, U937, and KG-1) and human T- and B-cell lines (e.g., JURKAT, MOLT-4, Daudi, and Raji) in a dose- and time-dependent manner. The 50% effective doses for these cell lines are similar to those established for human polymorphonuclear leukocytes and monocytes. In contrast, other human and nonhuman tumor cell lines are not susceptible to the leukotoxin. These human leukemia and lymphoid cell lines will serve as useful model systems with which to study the molecular specificity and mechanism(s) of action of the actinobacillus leukotoxin. Images PMID:3258584

  9. Serum antibody in Actinobacillus actinomycetemcomitans-infected patients with periodontal disease.

    PubMed Central

    Ebersole, J L; Sandoval, M N; Steffen, M J; Cappelli, D

    1991-01-01

    This study was designed to (i) delineate the characteristics of serum antibody responses to Actinobacillus actinomycetemcomitans in patients with periodontitis who are infected with A. actinomycetemcomitans; irrespective of disease classification; (ii) assess the relationship of the elevated antibody levels to colonization of the oral cavity by A. actinomycetemcomitans; and (iii) describe the serotype distribution of A. actinomycetemcomitans and antibodies to the microorganism in infected patients with various clinical classifications. To compare the levels of various isotype-specific antibodies to the different antigens, studies were performed that allowed quantitation of each isotype-specific antibody in a human reference standard. By using this reference standard, it was shown that the levels of immunoglobulin G (IgG), IgM, and IgA responses to A. actinomycetemcomitans were similar among the infected patients, irrespective of disease classification. Also, we demonstrated that the serum antibody response to serotype b was quantitatively greater in all isotypes. Our findings indicate that b was the most frequent A. actinomycetemcomitans serotype detected in the patients and appears to be capable of initiating a substantial serum IgG antibody response that may contain cross-reactive antibodies to other serotypes of A. actinomycetemcomitans. Generally, in cases in which the response to a single serotype was elevated, only that type of A. actinomycetemcomitans was detected in the plaque. Individuals exhibiting elevated antibodies to multiple serotypes were most consistently colonized by the serotype b microorganism. This study represents the first report detailing the distribution of IgG subclass antibodies to A. actinomycetemcomitans in periodontal disease. The results demonstrated that the primary responses of patients with periodontitis to A. actinomycetemcomitans were of the IgG1 and IgG3 subclasses, which is consistent with elicited responses to protein antigens

  10. Bacteriocin production by Actinobacillus actinomycetemcomitans isolated from the oral cavity of humans with periodontal disease, periodontally healthy subjects and marmosets.

    PubMed

    Lúcia, Lima Francisca; Farias, Flávio F; Eustáquio, Costa José; Auxiliadora, Maria; Carvalho, R; Alviano, Celuta S; Farias, Luiz M

    2002-01-01

    The ability of Actinobacillus actinomycetemcomitans to produce bacteriocin has rarely been reported. Antagonistic substance production may confer an important ecological advantage for the producer microorganisms, especially in a competitive ecosystem such as the oral cavity. In the present study, 75 A. actinomycetemcomitans strains isolated from the oral cavity of human patients with periodontal disease, periodontally healthy subjects and marmosets, as well as two reference strains (A. actinomycetemcomitans ATCC 29523 and FDC Y4) were evaluated for auto-, iso-, and heteroantagonistic activity. Fifty-one (68.00%) strains exhibited antagonistic activity; heteroantagonism was observed more often than isoantagonism. Isolated strains antagonized 17 different species of gram-positive and gram-negative bacteria from the oral and nonoral microbiota. Sensitivity to heat and to proteolytic enzymes constituted strong evidence that the antagonistic substance has a proteic nature. Taken together, our data enabled us to confirm that the antagonistic substance detected was a bacteriocin. The wide spectrum of activity indicates the possibility that more than one antagonistic substance is produced and that these substances play an important role in the ecological balance of the oral ecosystem.

  11. Association of Actinobacillus actinomycetemcomitans leukotoxin with nucleic acids on the bacterial cell surface.

    PubMed Central

    Ohta, H; Hara, H; Fukui, K; Kurihara, H; Murayama, Y; Kato, K

    1993-01-01

    Actinobacillus actinomycetemcomitans, a periodontopathic gram-negative bacterium, produces a leukotoxin that is a member of the RTX cytotoxin family. Although genes may function in toxin secretion, the leukotoxin is not secreted extracellularly but remains associated with the bacterial cell surface. We report here that this toxin-cell surface association is mediated by nucleic acids and directly demonstrate that the extracellular secretion of toxin occurs in growing cultures with increased ionic strength of medium. All examinations were performed with freshly harvested A. actinomycetemcomitans 301-b from anaerobic fructose-limited chemostat cultures. The occurrence of cell surface-localized DNA was shown by directly digesting whole cells with the restriction endonuclease EcoRI or HindIII, which yielded many DNA fragments. The cell surface DNA constituted about 20% of the total cellular DNA. The leukotoxin was released from the whole cells by digestion with DNase I as well as restriction endonucleases. Because the leukotoxin binds ionically to DNA, it is dependent on the ionic strength of buffers or media. Accordingly, the toxin was released from cells suspended in saline at pH 7.5 in the presence of increasing amounts of MgCl2 (0 to 10 mM) or NaCl (0 to 50 mM). Moreover, a considerable quantity of leukotoxin was detected in the culture supernatant of fructose-limited chemostat cultures when sodium succinate solution was pumped into the steady state as an additional salt (30 and then 50 mM). This toxin-DNA association was also found in well-characterized strains including not only the leukotoxin-producing ATCC 29522 but also the toxin production-variable ATCC 29523 and the non-leukotoxin-producing ATCC 33384 when these strains were grown in the chemostat culture. Images PMID:8406888

  12. DNA analysis of temperate bacteriophage Aa(phi)23 isolated from actinobacillus actinomycetemcomitans.

    PubMed

    Willi, K; Meyer, J

    1998-05-01

    The DNA of the temperate bacteriophage Aaphi23 isolated from the oral bacterium Actinobacillus actinomycetemcomitans was examined structurally both in the phage head and in the prophage. The DNA in phage particles comprises 44 kb linear molecules with a terminal redundancy of 1.6 kb, which represent circular permutations. Thus, DNA is packaged into phage heads by the headful mechanism. The Aaphi23 prophage is integrated into the host chromosome.

  13. Actinobacillus actinomycetemcomitans adheres to human gingival fibroblasts and modifies cytoskeletal organization.

    PubMed

    Gutiérrez-Venegas, Gloria; Kawasaki-Cárdenas, Perla; Garcés, Carla Portillo; Román-Alvárez, Patricia; Barajas-Torres, Carolina; Contreras-Marmolejo, Luis Arturo

    2007-09-01

    Adherence of Actinobacillus actinomycetemcomitans to human gingival fibroblast cells induces cytoskeletal reorganization. A. actinomycetemcomitans is considered a pathogenic bacteria involved in localized aggressive periodontitis. Studies with epithelial cells have shown an adherent capacity of bacteria that is increased under anaerobic conditions. For adherence to take place, there is a need for interaction between extracellular vesicles and bacterial fimbriae. However, molecular events associated with the adherence process are still unknown. The aim of this study was to investigate whether A. actinomycetemcomitans adherence to human gingival fibroblasts promotes cytoskeletal reorganization. Adherence was determined with light microscopy and scanning electron microscopy. For F-actin visualization, cells were treated with fluorescein-isothiocyanate-phalloidin and samples were examined with epifluorescence optics. Fluorescent was recorded on Kodak T-Max 400 film. We showed that A. actinomycetemcomitans adheres to human gingival fibroblast primary cultures, this property stimulating an increase in the intracellular calcium levels. In human gingival fibroblast primary cultures, we observed that maximal A. actinomycetemcomitans adherence took place 1.5h after culture infection occurred and remained for 6h. The adherence was associated with morphologic alterations and an increased in the intracellular calcium levels. These experiments suggest that A. actinomycetemcomitans adherence cause morphological alterations, induce actin stress fibers and recruitment of intracellular calcium levels.

  14. The heat-modifiable outer membrane protein of Actinobacillus actinomycetemcomitans: relationship to OmpA proteins.

    PubMed Central

    Wilson, M E

    1991-01-01

    The outer membrane of Actinobacillus actinomycetemcomitans contains a 29-kDa protein which exhibits heat modifiability on sodium dodecyl sulfate-polyacrylamide gels and represents a major target for immunoglobulin G antibody in sera of periodontitis patients colonized by this organism. In the present study, the N-terminal amino acid sequence of the 29-kDa outer membrane protein was determined and compared with reported sequences for other known proteins. The heat-modifiable outer membrane protein of A. actinomycetemcomitans was found to exhibit significant N-terminal homology with the OmpA proteins of other gram-negative bacteria. Moreover, this protein reacted with antiserum raised against the purified OmpA protein of Escherichia coli K-12. Whether the heat-modifiable OMP of A. actinomycetemcomitans also shares functional properties of OmpA proteins, particularly with respect to bacteriophage receptor activity, is presently under investigation. Images PMID:2050416

  15. Murine macrophage interleukin-1 release by capsularlike serotype-specific polysaccharide antigens of Actinobacillus actinomycetemcomitans.

    PubMed Central

    Takahashi, T; Nishihara, T; Ishihara, Y; Amano, K; Shibuya, N; Moro, I; Koga, T

    1991-01-01

    Serotype-specific polysaccharide antigens (SPAs) were extracted from whole cells of Actinobacillus actinomycetemcomitans ATCC 29523 (serotype a), Y4 (serotype b), and NCTC 9710 (serotype c) by autoclaving and purified by chromatography on DEAE-Sephadex A-25 and Sephacryl S-300 columns. Y4 SPA induced interleukin-1 (IL-1) release by P388D1 murine macrophages. Polymyxin B had virtually no effect on the release of IL-1. Rabbit anti-murine IL-1 serum strongly suppressed the proliferation of C3H/HeJ mouse thymocytes induced with the culture supernatants of Y4 SPA-stimulated P388D1 cells and a submitogenic dose of concanavalin A. Gel filtration of the culture supernatants of Y4 SPA-stimulated macrophages on Sephacryl S-200 showed that an IL-1 peak at a point corresponding to approximately 16.5 kDa was eluted. The ability of SPAs from strains ATCC 29523 and NCTC 9710 to induce the release of IL-1 was lower than that of Y4 SPA. The IL-1-releasing ability of serotype a and c antigens was enhanced by deacetylation of both polysaccharides, suggesting that acetyl groups of these antigens might hinder the interaction between the antigens and macrophages. PMID:1987032

  16. Opsonic antibody activity against Actinobacillus actinomycetemcomitans in patients with rapidly progressive periodontitis.

    PubMed Central

    Sjöström, K; Darveau, R; Page, R; Whitney, C; Engel, D

    1992-01-01

    Actinobacillus actinomycetemcomitans has been closely associated with early-onset, severe periodontitis, and such patients often have serum immunoglobulin G (IgG) antibodies reactive with antigens of this gram-negative pathogen. We examined the functionality and potential importance of these antibodies. The opsonic activity against A. actinomycetemcomitans of sera from 30 patients with rapidly progressive periodontitis (RPP) and from 28 periodontally normal subjects was tested by using polymorphonuclear leukocyte (PMN) chemiluminescence and bactericidal assays. Peak chemiluminescence values correlated strongly with killing observed in the PMN-dependent bactericidal assay (r = 0.88; P < 0.001). Neither the mean IgG titer nor the mean peak chemiluminescence differed significantly between the two groups. However, when the relationship between chemiluminescence and titer was examined, regression analysis showed that antibodies present in low-titer normal sera were significantly more effective at opsonizing A. actinomycetemcomitans than antibodies present in low-titer RPP patient sera (P = 0.04). Thus, periodontally normal individuals may be better able than RPP patients to clear A. actinomycetemcomitans in early stages of colonization, and anti-A. actinomycetemcomitans antibodies in RPP patients may be relatively ineffective in preventing infection by this organism. PMID:1398993

  17. Extraction and isolation of a leukotoxin from Actinobacillus actinomycetemcomitans with polymyxin B.

    PubMed Central

    Tsai, C C; Shenker, B J; DiRienzo, J M; Malamud, D; Taichman, N S

    1984-01-01

    A leukotoxin from Actinobacillus actinomycetemcomitans was isolated by a procedure that includes polymyxin B extraction, ion-exchange chromatography, and gel filtration chromatography. The procedure resulted in the recovery of 48% of the toxin with a 99-fold increase in specific activity. The isolated toxin has a molecular mass of 180,000 daltons by gel filtration and 115,000 daltons by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. It retains all the major biological characteristics previously documented for crude leukotoxin preparations, including susceptibility to heat and proteolytic enzymes and neutralization by sera from patients with juvenile periodontitis. The isolated leukotoxin destroys human but not rat or guinea pig polymorphonuclear leukocytes and has no apparent effect on human erythrocytes. The availability of the A. actinomycetemcomitans leukotoxin should facilitate studies on its chemistry and mode of action as well as its role in the pathogenesis of human periodontal disease. Images PMID:6319288

  18. Subclass and molecular form of immunoglobulin A antibodies to Actinobacillus actinomycetemcomitans in juvenile periodontitis.

    PubMed Central

    Brown, T A; Byres, L; Gardner, M; Van Dyke, T E

    1991-01-01

    Patients with juvenile periodontitis frequently have elevated levels of serum immunoglobulin A (IgA) antibodies to antigens of Actinobacillus actinomycetemcomitans. IgA occurs in two subclasses, IgA1 and IgA2, and in monomeric and polymeric forms. Because IgA1 is susceptible to cleavage by IgA1 proteases produced by microorganisms found at mucosal sites and in the gingival crevice, we wished to determine the IgA subclass distribution of antibodies to antigens of A. actinomycetemcomitans. The molecular form was examined because it may indicate the origin of the IgA and because the form differs in acute and chronic infections. There is also evidence that monomeric and polymeric IgA have different biological functions. Serum was taken from patients with juvenile periodontitis before and at intervals during and after initiation of therapy. IgA subclass distribution was determined against a sonic extracts of A. actinomycetemcomitans ATCC 2952a (serotype b) by using monoclonal anti-subclass reagents in an enzyme-linked immunosorbent assay. To determine the molecular form of the antibodies, sera were separated by high-performance liquid chromatography on a size-exclusion column. Fractions were assayed for antibody activity by the enzyme-linked immunosorbent assay, and described above. The results of the subclass analysis of the sera indicated that while both IgA1 and IgA2 antibodies to A. actinomycetemcomitans sonic extract are often found before, during, and after treatment, IgA1 antibodies dominated the response. There was a predominance of monomeric IgA1 antibodies to A. actinomycetemcomitans sonic extracts in most samples before, during, and after treatment. The monomeric form is consistent with what is seen in other chronic infections. The predominance of IgA1 antibodies implies that any protective effects of the IgA response to A. actinomycetemcomitans could be compromised by microbial IgA1 proteases. PMID:1997415

  19. Cloning and sequencing of part of the S10 operon from Actinobacillus actinomycetemcomitans FDC Y4.

    PubMed

    Hayashida, H; Hotokezaka, H; Ohara, N; Kimura, M; Takagi, O; Yamada, T

    1997-06-01

    We have cloned and sequenced the 5.2 kb EcoRI fragment that contained part of the S10 operon from Actinobacillus actinomycetemcomitans FDC Y4. The order of the ribosomal protein genes was identical to that of the S10 operon of Haemophilus influenzae and Escherichia coli. The deduced amino acid sequences of ribosomal proteins in this operon displayed significant homologies (65.3%-100%) to those of H. influenzae, E. coli, Yersinia enterocolitica and Yersinia pseudotuberculosis. Phylogenetic trees obtained for these ribosomal proteins were similar to that obtained for 16S rRNA.

  20. Actinobacillus actinomycetemcomitans and localized juvenile periodontitis. Clinical, microbiologic and histologic studies.

    PubMed

    Christersson, L A

    1993-01-01

    The present studies examined Actinobacillus actinomycetemcomitans and its role in localized juvenile periodontitis (LJP). The distribution of the bacteria was studied in healthy normals, patients with adult periodontitis, diabetics, and those with LJP. Over 95% of the LJP patients harbored A. actinomycetemcomitans, whereas only 17% of healthy subjects, 21% of adult periodontitis patients, and 5% of diabetics were positive. All members of a LJP family harboring the organism yielded isolates of the same biotype and serotype. The transmission of the bacteria was studied after transfer of the bacteria, with periodontal probes from infected to healthy gingival sites, within the oral cavity of LJP patients. Newly colonized gingival sites, 50% of those involved, became free of A. actinomycetemcomitans after only 3 weeks. A purposely forceful inoculation contributed to a more predictable colonization (89%), but only prolonged the colonization with one week. Treatment of LJP lesions with scaling and root planing resulted in minimal clinical and microbiological changes during a 16 week follow-up period. However, gingival curettage and modified Widman flap surgery suppressed A. actinomycetemcomitans in 75% and 89% of the sites, and resulted in resolution of periodontal pocket depth and gain in attachment level. Gingival tissue specimens, from 35 LJP sites, 3 control sites, and one monkey biopsy, were studied to verify the hypothesis of gingival infiltration of A. actinomycetemcomitans. Bacteria were identified immunohistologically with rabbit antisera serospecific to the three A. actinomycetemcomitans serotypes. Positive staining was observed in the tissue from all but one LJP patient. Twenty-eight (80%) lesions were positive for A. actinomycetemcomitans antigens in the gingival connective tissue, often with antigens located both between and within cells. The specimen from a culture positive control demonstrated no signs of invasion, similar to the monkey specimen

  1. Crystallization and preliminary X-ray crystallographic analysis of MacA from Actinobacillus actinomycetemcomitans

    SciTech Connect

    Piao, Shunfu; Xu, Yongbin; Ha, Nam-Chul

    2008-05-01

    A periplasmic membrane-fusion protein MacA from Actinobacillus actinomycetemcomitans, an essential component of the multidrug efflux pump in Gram-negative bacteria, was crystallized. Periplasmic membrane-fusion proteins (MFPs) are an essential component of the multidrug efflux pump in Gram-negative bacteria. They play a crucial role in bridging the outer membrane porin TolC and two distinct types of inner membrane transporters. The MFP MacA bridges the inner membrane ABC-type multidrug transporter MacB and the outer membrane porin TolC. MacA from the pathogenic bacterium Actinobacillus actinomycetemcomitans was expressed in Escherichia coli B834 (DE3) and the recombinant protein was purified using Ni–NTA affinity, Q anion-exchange and gel-filtration chromatography. The purified MacA protein was crystallized using the vapour-diffusion method. A MAD diffraction data set was collected to a resolution of 3.0 Å at 100 K. The crystal belongs to space group P622, with unit-cell parameters a = b = 109.2, c = 255.4 Å, α = β = 90, γ = 120°, and contains one molecule in the asymmetric unit.

  2. Immunoglobulin G subclass response of localized juvenile periodontitis patients to Actinobacillus actinomycetemcomitans Y4 lipopolysaccharide.

    PubMed Central

    Wilson, M E; Hamilton, R G

    1992-01-01

    Sera from patients with localized juvenile periodontitis (LJP) often contain markedly elevated immunoglobulin G (IgG) antibody titers to serospecific determinants of the lipopolysaccharide (LPS) from Actinobacillus actinomycetemcomitans. The objective of the present study was to define the subclass distribution of the IgG antibody response of LJP patients to this key cell envelope antigen. IgG subclass antibody responses to A. actinomycetemcomitans LPS were quantified in an enzyme-linked immunosorbent assay with human IgG subclass-restricted monoclonal antibodies. Serum antibody concentrations were calculated by heterologous interpolation of a dose-response curve constructed by using human-mouse chimeric antibodies. Sixteen of 17 LJP serum samples tested contained significantly greater concentrations of IgG2 than IgG1 antibodies reactive toward A. actinomycetemcomitans LPS. Geometric mean antibody concentrations of IgG1 and IgG2 were 7.8 and 136.5 micrograms/ml, respectively, among LJP patients with elevated IgG titers to LPS (94% of whom were black). However, both IgG1 and IgG2 antibody concentrations were significantly greater than the corresponding values obtained from sera from LJP patients with low IgG titers to LPS. Among LJP patients with elevated IgG titers to A. actinomycetemcomitans LPS, serum IgG2 concentration and total IgG concentration were also significantly elevated compared with both low-titered LJP sera and sera from periodontally healthy race-matched controls. The results of this study indicate that the humoral response of a predominantly black population of LJP patients to A. actinomycetemcomitans includes the production of LPS-reactive IgG antibodies which are primarily of the IgG2 subclass. PMID:1563768

  3. Effect of adoptive transfer of cloned Actinobacillus actinomycetemcomitans-specific T helper cells on periodontal disease.

    PubMed Central

    Yamashita, K; Eastcott, J W; Taubman, M A; Smith, D J; Cox, D S

    1991-01-01

    Previously we isolated several Actinobacillus actinomycetemcomitans-specific T-cell clones from the spleens and lymph nodes of immunized Rowett rats. These clones were characterized as W3/13+, W3/25+, OX8-, and OX22-, suggesting a T helper (Th) phenotype. In the current experiments, 10(6) cells from a single A. actinomycetemcomitans-specific clone (A3) were adoptively transferred to a group (AaTh; n = 13) of normal heterozygous rats (rnu/+) at 28 days of age. A second group received no T cells (AaNT; n = 15), and a third group also received no T cells (NAaNT, n = 11). Beginning 1 day after transfer, the first and second groups were infected orally with A. actinomycetemcomitans for 5 consecutive days. The presence of infection was confirmed immediately after challenge and after 5 months, when the experiments were ended. Significantly higher numbers of lymphocytes were recovered from the gingival tissues of the first group than from those of either of the other groups. Also, this group showed significantly elevated (P less than 0.01) serum immunoglobulin G and immunoglobulin M antibody to A. actinomycetemcomitans in an enzyme-linked immunosorbent assay when compared with both other groups. Bone loss was significantly lower (P less than 0.01) in recipients of A. actinomycetemcomitans-specific cloned cells when compared with the other infected group and was approximately equal to the bone loss of the uninfected group. These results are consistent with the hypothesis that T-cell regulation can affect periodontal disease. In this regulation, T helper cells appear to interfere with periodontal bone loss. PMID:1825991

  4. Immune suppression induced by Actinobacillus actinomycetemcomitans: effects on immunoglobulin production by human B cells.

    PubMed Central

    Shenker, B J; Vitale, L A; Welham, D A

    1990-01-01

    Actinobacillus actinomycetemcomitans produces an immunosuppressive factor (ISF) which has been shown to suppress mitogen- and antigen-induced DNA, RNA, and protein synthesis in human T lymphocytes. In this study, we examined purified A. actinomycetemcomitans ISF for its ability to alter immunoglobulin production by human B cells. The ISF caused a dose-dependent inhibition of pokeweed mitogen (PWM)-induced immunoglobulin G (IgG) and IgM production. Preexposure to ISF was not required to achieve maximal inhibition of immunoglobulin synthesis, as previously observed for its effect on T-cell activation. Nevertheless, the ISF appeared to act by irreversibly affecting the early stages of cell activation. While PWM-induced immunoglobulin production is under the influence of T-regulatory circuits, it appears that the ISF interacts directly with B cells. First, ISF failed to alter either the synthesis of interleukin-2 (IL-2) or the expression of IL-2 receptors on T cells. Second, experiments in which individual purified populations of cells were exposed to ISF, washed, and placed back into tissue culture indicated that when all cells (i.e., T cells, B cells, and monocytes) were exposed to ISF, significant suppression was observed. However, when only one cell population was treated with ISF, suppression of both IgG and IgM synthesis was observed only when the B-cell-enriched population was exposed to ISF. These results in conjunction with our earlier findings suggest that the ISF functions via the activation of a regulatory subpopulation of B lymphocytes, which in turn either directly or indirectly (via suppressor T cells) downregulate both B- and T-cell responsiveness. Furthermore, it is hypothesized that patients who harbor A. actinomycetemcomitans could suffer from local or systemic immune suppression. This suppression may enhance the pathogenicity of A. actinomycetemcomitans itself or that of some other opportunistic organism. Images PMID:2254014

  5. Nucleotide sequence of the leukotoxin gene from Actinobacillus actinomycetemcomitans: homology to the alpha-hemolysin/leukotoxin gene family.

    PubMed Central

    Kraig, E; Dailey, T; Kolodrubetz, D

    1990-01-01

    The leukotoxin produced by Actinobacillus actinomycetemcomitans has been implicated in the etiology of localized juvenile periodontitis. To initiate a genetic analysis into the role of this protein in disease, we have cloned its gene, lktA. We now present the complete nucleotide sequence of the lktA gene from A. actinomycetemcomitans. When the deduced amino acid sequence of the leukotoxin protein was compared with those of other proteins, it was found to be homologous to the leukotoxin from Pasteurella haemolytica and to the alpha-hemolysins from Escherichia coli and Actinobacillus pleuropneumoniae. Each alignment showed at least 42% identity. As in the other organisms, the lktA gene of A. actinomycetemcomitans was linked to another gene, lktC, which is thought to be involved in the activation of the leukotoxin. The predicted LktC protein was related to the leukotoxin/hemolysin C proteins from the other bacteria, since they shared a minimum of 49% amino acid identity. Surprisingly, although actinobacillus species are more closely related to pasteurellae than to members of the family Enterobacteriaciae, LktA and LktC from A. actinomycetemcomitans shared significantly greater sequence identity with the E. coli alpha-hemolysin proteins than with the P. haemolytica leukotoxin proteins. Despite the overall homology to the other leukotoxin/hemolysin proteins, the LktA protein from A. actinomycetemcomitans has several unique properties. Most strikingly, it is a very basic protein with a calculated pI of 9.7; the other toxins have estimated pIs around 6.2. The unusual features of the A. actinomycetemcomitans protein are discussed in light of the different species and target-cell specificities of the hemolysins and the leukotoxins. Images PMID:2318535

  6. Distinctive characteristics of transcriptional profiles from two epithelial cell lines upon interaction with Actinobacillus actinomycetemcomitans.

    PubMed

    Mans, J J; Baker, H V; Oda, D; Lamont, R J; Handfield, M

    2006-08-01

    Transcriptional profiling and gene ontology analyses were performed to investigate the unique responses of two different epithelial cell lines to an Actinobacillus actinomycetemcomitans challenge. A total of 2867 genes were differentially regulated among all experimental conditions. The analysis of these 2867 genes revealed that the predominant specific response to infection in HeLa cells was associated with the regulation of enzyme activity, RNA metabolism, nucleoside and nucleic acid transport and protein modification. The predominant specific response in immortalized human gingival keratinocytes (IHGK) was associated with the regulation of angiogenesis, chemotaxis, transmembrane receptor protein tyrosine kinase signaling, cell differentiation, apoptosis and response to stress. Of particular interest, stress response genes were significantly - yet differently - affected in both cell lines. In HeLa cells, only three regulated genes impacted the response to stress, and the response to unfolded protein was the only term that passed the ontology filters. This strikingly contrasted with the profiles obtained for IHGK, in which 61 regulated genes impacted the response to stress and constituted an extensive network of cell responses to A. actinomycetemcomitans interaction (response to pathogens, oxidative stress, unfolded proteins, DNA damage, starvation and wounding). Hence, while extensive similarities were found in the transcriptional profiles of these two epithelial cell lines, significant differences were highlighted. These differences were predominantly found in pathways that are associated with host-pathogen interactions.

  7. Purification and characterization of the serotype c antigen from Actinobacillus actinomycetemcomitans.

    PubMed Central

    Zambon, J J; Slots, J; Miyasaki, K; Linzer, R; Cohen, R; Levine, M; Genco, R J

    1984-01-01

    The serotype c antigen from Actinobacillus actinomycetemcomitans was purified with fractional ethanol precipitation of cell-free culture supernatant, sequential ion-exchange chromatography, and gel filtration chromatography. The preparation obtained demonstrated a single precipitin line in immunodiffusion, immunoelectrophoresis, and crossed immunoelectrophoresis when rabbit antisera to serotype c whole bacterial cells were used. No immunological reaction was detected with antisera to serotype c lipopolysaccharide, indicating that lipopolysaccharide was not present in the preparation. The serotype c antigen was composed of 95% carbohydrate, 2% protein, and 3.1% phosphate. Gas chromatographic analysis of the antigen obtained from growth in either complex or chemically defined media revealed that the carbohydrate constituent was composed of 84 to 90.1% mannose, 4.8 to 16% glucose, 1.9% N-acetylglucosamine, 1.4% fucose, and 0.2% galactose. The present data suggest that A. actinomycetemcomitans serotype c antigen is predominantly a mannose-containing carbohydrate suggestive of a mannan. Images PMID:6423542

  8. Antigens of Actinobacillus actinomycetemcomitans recognized by patients with juvenile periodontitis and periodontally normal subjects.

    PubMed Central

    Sims, T J; Moncla, B J; Darveau, R P; Page, R C

    1991-01-01

    Most juvenile periodontitis patients respond to infection by Actinobacillus actinomycetemcomitans by producing serum antibodies. Specific antigens inducing the humoral immune response have not been identified, nor has the role of the resulting antibodies in disease progression been determined. Adsorbed and unadsorbed sera from juvenile periodontitis patients and normal subjects were analyzed by enzyme-linked immunosorbent assay and Western blots (immunoblots), using digested and undigested bacterial sonicates and French pressure cell fractions to determine the biochemical class, cross-reactivity, and cellular location of the antigens in different A. actinomycetemcomitans serotypes. Antigens detected by using high-titer sera included the following: (i) serotype-specific nonprotein material located on the cell surface, (ii) soluble-fraction proteins showing highly variable antibody binding, (iii) cross-reactive proteins, and (iv) a protein present in soluble and cell wall fractions and immunopositive for all sera tested. In addition, one apparently nonprotein component that was enriched in the cell wall fraction was observed. Sera with high immunoglobulin G titers to one, two, three, or none of the three A. actinomycetemcomitans serotypes were observed. There was a high degree of variation from one patient to another in the humoral immune response to serotype-specific and cross-reactive antigens. As demonstrated by whole-cell adsorption experiments, the serotype-specific surface antigen accounted for approximately 72 to 90% of the total antibody-binding activity for sera with titers greater than 100-fold above background, while cross-reactive antigen accounted for less than 28%. Antibody binding the whole-cell sonicate for high-titer sera was inhibited 90% by lipopolysaccharide from the same serotype, strongly suggesting that lipopolysaccharide is the immunodominant antigen class. Images PMID:1705243

  9. Biochemical and morphological characterization of the killing of human monocytes by a leukotoxin derived from Actinobacillus actinomycetemcomitans.

    PubMed Central

    Taichman, N S; Dean, R T; Sanderson, C J

    1980-01-01

    A potent, heat-labile leukotoxic material was extracted from Actinobacillus actinomycetemcomitans (strain Y4), an anaerobic gram-negative microorganism originally isolated from subgingival plaque in a patient with juvenile periodontitis. The cytopathic effects of Y4 toxin on purified monocytes were studied by the extracellular release of radioactive cytoplasmic markers and cell enzymes and by time-lapse microcinematography. Y4 toxin rapidly bound to the cells, producing dose- and time-dependent alterations culminating in cell death and release of intracellular constituents into the culture medium. The evidence to be presented suggests that the cell membrane of the monocyte may be the primary target in the development of these phenomena. Previous studies have shown that Y4 toxin also kills human polymorphonuclear leukocytes but not other cell types. It is conceivable that disruption of polymorphonuclear leukocytes and monocytes by Y4 toxin in the gingival crevice area may be relevant in the pathogenesis of juvenile periodontitis. Images Fig. 1 PMID:6155347

  10. Complete Genome Sequence of Aggregatibacter actinomycetemcomitans Strain IDH781

    PubMed Central

    May, Anthony C.; Ehrlich, Rachel L.; Balashov, Sergey; Ehrlich, Garth D.; Shanmugam, Mayilvahanan; Fine, Daniel H.; Ramasubbu, Narayanan

    2016-01-01

    We report here the complete genomic sequence and methylome of Aggregatibacter actinomycetemcomitans strain IDH781. This rough strain is used extensively as a model organism to characterize localized aggressive periodontitis pathogenesis, the basic biology and oral cavity colonization of A. actinomycetemcomitans, and its interactions with other members of the oral microbiome. PMID:27834722

  11. Nuclease-sensitive binding of an Actinobacillus actinomycetemcomitans leukotoxin to the bacterial cell surface.

    PubMed Central

    Ohta, H; Kato, K; Kokeguchi, S; Hara, H; Fukui, K; Murayama, Y

    1991-01-01

    A leukotoxin of Actinobacillus actinomycetemcomitans 301-b was solubilized from cell-associated membrane vesicles by treatment with externally added DNase and RNase and was further purified by a procedure which included ammonium sulfate fractionation, gel filtration chromatography, and ion-exchange chromatography. The purified toxin had a molecular mass of 113,000 Da by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and a high isoelectric point (approximately 8.8). From these characteristics, it was to be expected that the membrane vesicle toxin was almost identical to the leukotoxin extracted with polymyxin B in an earlier study (C.-C. Tsai, B. J. Shenker, J. M. DiRienzo, D. Malamud, and N. S. Taichman, Infect, Immun. 43:700-705, 1984). The treatment with DNase and RNase was also highly effective for solubilizing the leukotoxin directly from whole cells, suggesting that the toxin is secreted extracellularly but retained in nucleic acids on the outermost surface of bacterial cells. Images PMID:1937819

  12. Identification of the Exported Proteins of the Oral Opportunistic Pathogen Actinobacillus actinomycetemcomitans by Using Alkaline Phosphatase Fusions

    PubMed Central

    Ward, John; Fletcher, Julie; Nair, Sean P.; Wilson, Michael; Williams, Rachel J.; Poole, Stephen; Henderson, Brian

    2001-01-01

    A phoA fusion library of Actinobacillus actinomycetemcomitans genomic DNA has been screened to identify genes encoding exported and secreted proteins. A total of 8,000 colonies were screened, and 80 positive colonies were detected. From these, 48 genes were identified with (i) more than half having homology to known or hypothetical Haemophilus influenzae genes, (ii) 14 having no ascribed function, and (iii) 4 having very limited or no homology to known genes. The proteins encoded by these genes may, by virtue of their presence on the cell surface, be novel virulence determinants. PMID:11254647

  13. Resistance of Actinobacillus actinomycetemcomitans and differential susceptibility of oral Haemophilus species to the bactericidal effects of hydrogen peroxide.

    PubMed Central

    Miyasaki, K T; Wilson, M E; Reynolds, H S; Genco, R J

    1984-01-01

    We compared the sensitivities of oral and nonoral isolates of Actinobacillus actinomycetemcomitans, Haemophilus segnis, H. aphrophilus, and H. paraphrophilus to the bactericidal action of reagent hydrogen peroxide (H2O2). Susceptibility to a range of H2O2 concentrations (10(-6) to 10(-3) M) was assessed by incubating bacterial suspensions for 1 h at 37 degrees C in the presence of H2O2 and plating on chocolate agar to determine the concentration of H2O2 that would produce a 50% reduction in CFU (50% lethal dose). As a group, A. actinomycetemcomitans was more resistant to H2O2 than the oral haemophili, and H. aphrophilus was much more sensitive than all other organisms tested. The range of 50% lethal dose values for A. actinomycetemcomitans was between 8.5 X 10(-5) and 10(-3) M H2O2 or above. In contrast, H. aphrophilus exhibited 50% lethal dose values from below 1 X 10(-6) to 3.4 X 10(-4) M H2O2. The resistance of A. actinomycetemcomitans to H2O2 may be sufficient to protect these organisms from direct H2O2-mediated killing by host phagocytes. PMID:6500706

  14. Evidence that the serotype b antigenic determinant of Actinobacillus actinomycetemcomitans Y4 resides in the polysaccharide moiety of lipopolysaccharide.

    PubMed Central

    Wilson, M E; Schifferle, R E

    1991-01-01

    A high-molecular-weight polysaccharide-containing antigen was isolated from a phenol-water extract of Actinobacillus actinomycetemcomitans ATCC 43718 (formerly Y4) by gel permeation chromatography in lipopolysaccharide (LPS)-disaggregating buffer. The polysaccharide antigen formed a precipitin band with rabbit serotype b-specific antiserum but not with rabbit antisera to serotype a or c. Electroblotted serotype b antigen was probed with serum from a patient with localized juvenile periodontitis (LJP), resulting in a diffuse "smear" in the upper region of the lane. By utilizing an enzyme-linked immunosorbent assay, it was demonstrated that the geometric mean immunoglobulin G antibody titer to the serotype b polysaccharide was significantly higher in sera from LJP patients than in sera from periodontally healthy individuals. Moreover, LJP antibody titers to the serotype b polysaccharide exhibited age-dependent variation. Double immunodiffusion analysis revealed that the serotype b antigen formed a line of identity with low-molecular-weight LPS following reaction with serotype b-specific antiserum. Incubation of LJP serum in the presence of a lipid-free polysaccharide moiety obtained by mild acid hydrolysis of LPS from A. actinomycetemcomitans Y4 markedly reduced immunoglobulin G titer to the serotype b antigen. In contrast, solubilized lipid A was only weakly inhibitory. The results of this study indicate that the serotype b-specific determinant of A. actinomycetemcomitans resides in the polysaccharide moiety of LPS and represents a major target for immunoglobulin G antibody in serum of LJP subjects colonized by this organism. Images PMID:1706323

  15. Human immune responses to oral micro-organisms. I. Association of localized juvenile periodontitis (LJP) with serum antibody responses to Actinobacillus actinomycetemcomitans.

    PubMed Central

    Ebersole, J L; Taubman, M A; Smith, D J; Genco, R J; Frey, D E

    1982-01-01

    The association between periodontal disease in humans and serum and salivary antibody to Actinobacillus actinomycetemcomitans strain Y4 was determined. An Elisa was used to examine anti-Y4 antibody of the IgM, IgG, IgA and IgE isotypes in serum from 127 individuals and IgA in parotid saliva. Patients diagnosed as having localized juvenile periodontitis (n = 37) had significantly higher levels and frequency of serum IgG antibodies to Y4 than all other groups. Serum and salivary IgA and serum IgE antibody levels were significantly increased in patients with both localized and generalized types of juvenile periodontitis (n = 48) when compared to all other patient groups. Specificity studies suggested that the antigenic determinants that were differentiating the group responses were unique to the Y4 organism. These results indicate that serum antibodies to Y4 may reflect an infectious process with this micro-organism and that these responses may provide some diagnostic value in delineating different types of periodontal diseases. PMID:7094425

  16. Specific genetic variants of Actinobacillus actinomycetemcomitans correlate with disease and health in a regional population of families with localized juvenile periodontitis.

    PubMed Central

    DiRienzo, J M; Slots, J; Sixou, M; Sol, M A; Harmon, R; McKay, T L

    1994-01-01

    A geographically homogeneous population of 83 subjects, from 21 families with localized juvenile periodontitis (LJP), and 35 healthy control subjects was monitored, over a 5-year period, for the presence of the periodontal pathogen Actinobacillus actinomycetemcomitans. Restriction fragment length polymorphism (RFLP) analysis was used to monitor the distribution of genetic variants of this bacterium in LJP-susceptible subjects that converted from a healthy to a diseased periodontal status. A. actinomycetemcomitans was cultured from 57% of the LJP family members accessioned into the study. Nine of 36 LJP-susceptible subjects, in seven families, developed signs of periodontal destruction. All but one of these conversion subjects harbored A. actinomycetemcomitans. Bacterial variants representative of a single RFLP group (II) showed the strongest correlation with conversion (P < 0.002). Six of nine conversion subjects were infected with A. actinomycetemcomitans from this group. RFLP group II variants also prevailed in 8 of 22 probands but were absent in the 35 healthy control subjects. In contrast to the selective distribution of group II variants is diseased individuals, variants belonging to RFLP groups XIII and XIV were found exclusively in the control subjects. Thus, the use of RFLP to type clinical isolates of A. actinomycetemcomitans has resulted in the identification of genetic variants that predominate in LJP and health. These results indicate that studies concerned with the pathogenicity of this bacterium in LJP should be focused on the group II variants. PMID:7913695

  17. Despite large-scale T cell activation, only a minor subset of T cells responding in vitro to Actinobacillus actinomycetemcomitans differentiate into effector T cells.

    PubMed

    Zadeh, H H; Tanavoli, S; Haines, D D; Kreutzer, D L

    2000-06-01

    Recent studies in our laboratory have demonstrated that Actinobacillus actinomycetemcomitans has a potent T cell stimulatory effect, activating more than half of all T cells. However, since the fate of these activated T cells was not known, the present study sought to determine whether all of these T cells differentiate into effector cells. To that end, the intracellular expression of T cell cytokines (IL-2, IFN-gamma, IL-4 and IL-10) in response to A. actinomycetemcomitans was determined by flow cytometry. Results demonstrated a time-dependent increase in the expression of the cytokines, most reaching peak levels at 24-48 h. At 48 h, the proportion of T cells expressing each of the cytokines were as follows: IL-2 (1.7%+/-0.3), IFN-gamma (1.8%+/-0.5), IL-4 (1.0%+/-0.2) and IL-10 (1.5%+/-0.5). These data indicated that only 2-5% of all T cells stimulated with A. actinomycetemcomitans expressed any T cell cytokines. The finding of large-scale T cell activation in the absence of cytokine expression suggests that the activation of T cells in response to A. actinomycetemcomitans is incomplete. To investigate this phenomenon, peripheral blood mononuclear cells (PBMC) were cultured with A. actinomycetemcomitans for 24 h followed by sorting of the activated (CD69+) cells by immunomagnetic separation and restimulation with phorbol 12-myristate 13-acetate (PMA) and ionomycin. Results demonstrated that nearly 90% of the T cells were unresponsive to further restimulation. A possible explanation for this unresponsiveness is the induction of clonal anergy among the responding T cells. To determine possible preferential effects of the stimulation on specific cytokines, the expression of each cytokine among T cells responding to A. actinomycetemcomitans was compared to the maximum levels achieved by PMA + ionomycin stimulation. Results showed that number of IL-2+ and IFN-gamma+ T cells observed in response to A. actinomycetemcomitans were between 2% and 7% of those seen in

  18. Immunoglobulin class and subclass distribution of antibodies reactive with the immunodominant antigen of Actinobacillus actinomycetemcomitans serotype b.

    PubMed Central

    Lu, H; Califano, J V; Schenkein, H A; Tew, J G

    1993-01-01

    The aims of this study were to determine the immunodominant antigens of Actinobacillus actinomycetemcomitans serotype b (Aab) for the different immunoglobulin (Ig) classes and subclasses and to determine the relative levels of these different Igs in serum. Seropositive early-onset periodontitis patients were sampled, and the Ig classes IgG, IgA, and IgM and subclasses IgG1, IgG2, IgG3, IgG4, IgA1, and IgA2 were studied. Reactivity with Aab antigens was assessed by using the Western blot (immunoblot) in limiting dilution analysis and radioimmunoassay with sera from 13 early-onset periodontitis subjects. A smeared antigen in the upper portion of the immunoblots, typical of high-molecular-weight LPS, was immunodominant for IgG, IgA, IgM, IgG1, IgG2, IgG3, IgA1, and IgA2. This smeared antigen was present in every patient for all of these Igs at the endpoint. A few additional antigens were also present at the endpoint in some patients, but none were present in more than half of the subjects. The distribution of antibody titers by Ig classes reactive with the Aab immunodominant antigen was IgG > IgA > IgM. The distribution of antibody titers by IgG subclass was IgG2 > IgG1 approximately IgG3. Further quantitation by radioimmunoassay revealed that the mean concentration of IgG2 (65.7 micrograms/ml) was significantly greater than that of IgG1 (8.8 micrograms/ml). The IgA subclass distribution was IgA1 >> IgA2, with IgA1 apparently being second only to IgG2. Therefore, the Aab antigen eliciting the highest antibody level in virtually all Ig classes and subclasses appeared to be lipopolysaccharide, and IgG2 was markedly elevated over all other serum Ig classes or subclasses reactive with Aab. Images PMID:8500879

  19. Simultaneous measurement of the viability, aggregation, and live and dead adherence of Streptococcus crista, Streptococcus mutans and Actinobacillus actinomycetemcomitans in human saliva in relation to indices of caries, dental plaque and periodontal disease.

    PubMed

    Rudney, J D; Staikov, R K

    2002-05-01

    Salivary proteins have multiple functions and many share similar functions, which may be why it has been difficult to relate variations in their concentrations to oral health and ecology. An alternative is to focus on variations in the major functions of saliva. An hydroxyapatite-coated microplate model has been developed that simultaneously measures saliva-promoted bacterial viability, bacterial aggregation, and live and dead bacterial adherence, while simulating oral temperature and shearing forces from swallowing. That model was applied to resting whole and stimulated parotid saliva from 149 individuals, using representative strains of Streptococcus crista, S. mutans, and Actinobacillus actinomycetemcomitans. Two major factors were defined by multivariate analysis (this was successful only for whole-saliva). One factor was correlated with aggregation, live adherence and dead adherence for all three strains; the other was correlated with total viability of all three strains. Participants were grouped <25th percentile and >75th percentile for each factor. Those groups were compared for clinical indices of oral health. Caries scores were significantly lower in those with high scores for aggregation-adherence, regardless of whether total viability scores were low or high. Live bacteria always predominated on surfaces when live and dead adherence scores were expressed as ratios. However, participants with high scores for aggregation-adherence showed significantly more dead adherent bacteria than those with low scores (these ratios were uncorrelated with total viability). This finding may indicate that extreme differences in the ability to kill bacteria on surfaces can influence caries risk.

  20. The immunodominant outer membrane antigen of Actinobacillus actinomycetemcomitans is located in the serotype-specific high-molecular-mass carbohydrate moiety of lipopolysaccharide.

    PubMed Central

    Page, R C; Sims, T J; Engel, L D; Moncla, B J; Bainbridge, B; Stray, J; Darveau, R P

    1991-01-01

    Most patients with juvenile periodontitis manifest serum antibodies, sometimes at very high titers, to antigens of Actinobacillus actinomycetemcomitans, but the antigens inducing the immune response have been only partly characterized. We separated A. actinomycetemcomitans serotype b cells into protein, lipopolysaccharide (LPS), and soluble polysaccharide fractions and characterized them. Coomassie blue- and silver-stained sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels were used to detect protein and LPS components, and gas-liquid chromatography was used to determine their carbohydrate and fatty acid composition. Western blots, dot blots, and enzyme-linked immunosorbent assay inhibition with high-titer sera from juvenile periodontitis patients revealed which components were highest in antibody binding activity. These results showed that the major portion of the immunoglobulin G binding activity resides in the purified mannan-free LPS, with lesser amounts in the total protein fraction. Using Sephacryl S-300 chromatography, we separated LPS into high-molecular-mass components with high carbohydrate contents by gas-liquid chromatography and a low-molecular-mass component consisting mainly of lipid A and the inner core sugar heptulose. The results of quantitative dot blot assays and enzyme-linked immunosorbent assay inhibition show that the serotype-specific antibody binding activity is highly concentrated in the high-molecular-mass carbohydrate-rich LPS fraction and is almost completely absent in the low-molecular-weight lipid-rich fraction. Our observations contrast with previous reports that the predominant serotype antigen of A. actinomycetemcomitans resides in a mannan-rich polysaccharide isolated from spent culture medium. These observations support the conclusion that the immunodominant antigen of the outer membrane is the O antigen of the LPS. Images PMID:1716610

  1. Mouse interleukin-1 receptor antagonist induced by Actinobacillus actinomycetemcomitans lipopolysaccharide blocks the effects of interleukin-1 on bone resorption and osteoclast-like cell formation.

    PubMed Central

    Nishihara, T; Ohsaki, Y; Ueda, N; Saito, N; Mundy, G R

    1994-01-01

    We have reported that P388D1 cell line murine macrophages stimulated with lipopolysaccharide (LPS) from Actinobacillus actinomycetemcomitans release interleukin-1 (IL-1) inhibitor. The IL-1 inhibitor was purified from conditioned media of P388D1 cells stimulated with A. actinomycetemcomitans LPS for 72 h to homogeneity by a four-step procedure: acetic acid extraction from conditioned media; Bio-Gel P-60 gel filtration chromatography; DEAE-Sepharose CL-6B column chromatography; and reverse-phase high-performance liquid chromatography on a C18 hydrophobic support. The purified IL-1 inhibitor gave a single band of protein with a molecular mass of 26 kDa on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The purified IL-1 inhibitor was a heat- and acid-stable protein that was inactivated by digestion with trypsin and reduction with dithiothreitol. This inhibitory factor suppressed the proliferation of C3H/HeJ mouse thymocytes and the proliferation of IL-1-dependent cell lines, D10.G4.1 and RPMI 1788, induced by IL-1. However, this inhibitor did not affect the proliferation of IL-2-dependent CTLL-2 cells induced by IL-2, the proliferation of C3H/HeJ mouse thymocytes stimulated with a mitogenic dose of concanavalin A, and the proliferation of IL-6-dependent B9 cells induced by IL-6. Furthermore, the IL-1 inhibitor significantly blocked stimulation of bone resorption in organ cultures of newborn mouse calvaria and inhibited the osteoclast-like cell formation in mouse marrow cultures. A monoclonal antibody prepared against the purified IL-1 inhibitor reacted with mouse recombinant IL-1 receptor antagonist (rIL-1ra), and a polyclonal antibody to mouse rIL-1ra reacted with the IL-1 inhibitor by Western blot (immunoblot) analysis. These results indicate that the IL-1 inhibitor is an identical molecule to rIL-1ra, suggesting that the IL-1 inhibitor (IL-1ra) released by macrophages stimulated with LPS from A. actinomycetemcomitans may play an important mediative role

  2. Phenotypic changes in nonfimbriated smooth strains of Aggregatibacter actinomycetemcomitans grown in low-humidity solid medium.

    PubMed

    Pei, Zhenhua; Niu, Zhongying; Shi, Shenggen; Shi, Liang; Tang, Chuhua

    2013-04-01

    Aggregatibacter actinomycetemcomitans is the primary etiologic agent of localized aggressive periodontitis. In vitro, it can undergo fimbriated rough to nonfimbriated smooth phenotypic transition, accompanied by an increase in invasive ability and a decrease in adhesive ability. No opposite direction phenotypic transition was reported. To better understand its pathogenicity, the authors studied the morphological changes of nonfimbriated smooth strains induced by growth environmental humidity. Transmission electron microscopy was used to identify fimbriae expression change. It was found that the lower medium humidity, the more fimbriae reexpressed. In conclusion, the smooth strain of A. actinomycetemcomitans can reexpress the fimbriae in lower humidity environment.

  3. Actinobacillus actinomycetemcomitans lipopolysaccharide stimulates the phosphorylation of p44 and p42 MAP kinases through CD14 and TLR-4 receptor activation in human gingival fibroblasts.

    PubMed

    Gutiérrez-Venegas, Gloria; Kawasaki-Cárdenas, Perla; Cruz-Arroyo, Santa Rita; Pérez-Garzón, Miguel; Maldonado-Frías, Silvia

    2006-04-25

    Tyrosine phosphorylation is an early step in lipopolysaccharide (LPS) stimulated monocytes and macrophages that appears to play a key role in signal transduction. We have demonstrated that LPS purified from Actinobacillus actinomycetemcomitans also increases protein tyrosine phosphorylation in human gingival fibroblasts (HGF). This effect was elicited rapidly after LPS stimulation at concentrations that stimulate anti-bacterial responses in human gingival fibroblasts. Two main proteins, with an apparent molecular weight of 44 and 42 kDa, were phosphorylated after LPS stimulation of the human gingival fibroblasts. The phosphorylation was detected after 5 to 15 min and reached the maximum at 30 min of treatment. The increase in tyrosine phosphorylation was apparent following stimulation with LPS at 10 ng/ml and the response was dose dependent up to 10 microg/ml. Pretreatment with the tyrosine kinase inhibitors, herbimycin A and genistein inhibited the LPS-stimulated phosphorylation of p44 and p42 MAP kinases in a dose dependent manner. Pretreatment of human gingival fibroblasts with antibodies anti-CD14 or anti-TLR-4 but not anti-TLR-2 inhibited the LPS-induced tyrosine phosphorylation of p44 and p42. Additionally, LPS-induced p44 and p42 phosphorylation was inhibited by polymyxin treatment. These findings demonstrate that LPS from A. actinomycetemcomintans increases rapidly p44 and p42 phosphorylation (ERK 1 and ERK 2, respectively) in human gingival fibroblasts. Our data also suggest that CD14 and TLR-4 receptors are involved in the LPS effects in human gingival fibroblasts.

  4. Involvement of Ganglioside GM3 in G2/M Cell Cycle Arrest of Human Monocytic Cells Induced by Actinobacillus actinomycetemcomitans Cytolethal Distending Toxin

    PubMed Central

    Mise, Koji; Akifusa, Sumio; Watarai, Shinobu; Ansai, Toshihiro; Nishihara, Tatsuji; Takehara, Tadamichi

    2005-01-01

    Actinobacillus actinomycetemcomitans produces a toxin called cytolethal distending toxin (CDT), which causes host cell DNA damage leading to the induction of DNA damage checkpoint pathways. CDT consists of three subunits, CdtA, CdtB, and CdtC. CdtB is the active subunit of CDT and exerts its effect as a nuclease that damages nuclear DNA, triggering cell cycle arrest. In the present study, we confirmed that the only combination of toxin proteins causing cell cycle arrest was that of all three recombinant CDT (rCDT) protein subunits. Furthermore, in order for rCDT to demonstrate toxicity, it was necessary for CdtA and CdtC to access the cell before CdtB. The coexistence of CdtA and CdtC was necessary for these subunits to bind to the cell. Cells treated with the glucosylceramide synthesis inhibitor 1-phenyl-2-palmitoylamino-3-morpholino-1-propanol showed resistance to the cytotoxicity induced by rCDT. Furthermore, LY-B cells, which are deficient in the biosynthesis of sphingolipid, also showed resistance to the cytotoxicity induced by rCDT. To evaluate the binding of each subunit for glucosylceramides, we performed thin-layer chromatography immunostaining. The results indicated that each subunit reacted with the glycosphingolipids GM1, GM2, GM3, Gb3, and Gb4. The rCDT mixture incubated with liposomes containing GM3 displayed partially reduced toxicity. These results indicate that GM3 can act as a CDT receptor. PMID:16040998

  5. A numerical taxonomic study of Actinobacillus, Pasteurella and Yersinia.

    PubMed

    Sneath, P H; Stevens, M

    1985-10-01

    A numerical taxonomic study of strains of Actinobacillus, Pasteurella and Yersinia, with some allied bacteria, showed 23 reasonably distinct groups. These fell into three major areas. Area A contained species of Actinobacillus and Pasteurella: A. suis, A. equuli, A. lignieresii, P. haemolytica biovar A, P. haemolytica biovar T, P. multocida, A. actinomycetemcomitans, 'P. bettii', 'A. seminis', P. ureae and P. aerogenes. Also included in A was a composite group of Pasteurella pneumotropica and P. gallinarum, together with unnamed groups referred to as 'BLG', 'Mair', 'Ross' and 'aer-2'. Area B contained species of Yersinia: Y. enterocolitica, Y. pseudotuberculosis, Y. pestis and a group 'ent-b' similar to Y. enterocolitica. Area C contained non-fermenting strains: Y. philomiragia, Moraxella anatipestifer and a miscellaneous group 'past-b'. There were also a small number of unnamed single strains.

  6. Transcriptome Profiling of Wild-Type and pga-Knockout Mutant Strains Reveal the Role of Exopolysaccharide in Aggregatibacter actinomycetemcomitans.

    PubMed

    Shanmugam, Mayilvahanan; El Abbar, Faiha; Ramasubbu, Narayanan

    2015-01-01

    Exopolysaccharides have a diverse set of functions in most bacteria including a mechanistic role in protecting bacteria against environmental stresses. Among the many functions attributed to the exopolysaccharides, biofilm formation, antibiotic resistance, immune evasion and colonization have been studied most extensively. The exopolysaccharide produced by many Gram positive as well as Gram negative bacteria including the oral pathogen Aggregatibacter actinomycetemcomitans is the homopolymer of β(1,6)-linked N-acetylglucosamine. Recently, we reported that the PGA-deficient mutant of A. actinomycetemcomitans failed to colonize or induce bone resorption in a rat model of periodontal disease, and the colonization genes, apiA and aae, were significantly down regulated in the mutant strain. To understand the role of exopolysaccharide and the pga locus in the global expression of A. actinomycetemcomitans, we have used comparative transcriptome profiling to identify differentially expressed genes in the wild-type strain in relation to the PGA-deficient strain. Transcriptome analysis revealed that about 50% of the genes are differently expressed (P < 0.05 and fold change >1.5). Our study demonstrated that the absence of the pga locus affects the genes involved in peptidoglycan recycling, glycogen storage, and virulence. Further, using confocal microscopy and plating assays, we show that the viability of pga mutant strain is significantly reduced during biofilm growth. Thus, this study highlights the importance of pga genes and the exopolysaccharide in the virulence of A. actinomycetemcomitans.

  7. The TadV Protein of Actinobacillus actinomycetemcomitans Is a Novel Aspartic Acid Prepilin Peptidase Required for Maturation of the Flp1 Pilin and TadE and TadF Pseudopilins†

    PubMed Central

    Tomich, Mladen; Fine, Daniel H.; Figurski, David H.

    2006-01-01

    The tad locus of Actinobacillus actinomycetemcomitans encodes genes for the biogenesis of Flp pili, which allow the bacterium to adhere tenaciously to surfaces and form strong biofilms. Although tad (tight adherence) loci are widespread among bacterial and archaeal species, very little is known about the functions of the individual components of the Tad secretion apparatus. Here we characterize the mechanism by which the pre-Flp1 prepilin is processed to the mature pilus subunit. We demonstrate that the tadV gene encodes a prepilin peptidase that is both necessary and sufficient for proteolytic maturation of Flp1. TadV was also found to be required for maturation of the TadE and TadF pilin-like proteins, which we term pseudopilins. Using site-directed mutagenesis, we show that processing of pre-Flp1, pre-TadE, and pre-TadF is required for biofilm formation. Mutation of a highly conserved glutamic acid residue at position +5 of Flp1, relative to the cleavage site, resulted in a processed pilin that was blocked in assembly. In contrast, identical mutations in TadE or TadF had no effect on biofilm formation, indicating that the mechanisms by which Flp1 pilin and the pseudopilins function are distinct. We also determined that two conserved aspartic acid residues in TadV are critical for function of the prepilin peptidase. Together, our results indicate that the A. actinomycetemcomitans TadV protein is a member of a novel subclass of nonmethylating aspartic acid prepilin peptidases. PMID:16980493

  8. Differentiation among closely related organisms of the Actinobacillus-Haemophilus-Pasteurella group by means of lysozyme and EDTA.

    PubMed Central

    Olsen, I; Brondz, I

    1985-01-01

    Bacteriolysis in Tris-maleate buffer (0.005 M, pH 7.2) supplemented with EDTA (0.01 M) and hen egg white lysozyme (HEWL, 1.0 microgram/ml) was set up to assist differentiation between the taxonomically closely related Actinobacillus actinomycetemcomitans and Haemophilus aphrophilus. A. actinomycetemcomitans was more sensitive to lysis in this system than H. aphrophilus. The standard method for bacteriolysis separated the 10 tested strains of A. actinomycetemcomitans into two groups (I and II) based on their lysis patterns, whereas the 7 strains of H. aphrophilus examined were homogeneous. In group I of A. actinomycetemcomitans, EDTA displayed a considerable lytic effect, which was not increased by supplementation with HEWL. In group II, the lytic effect of EDTA was much less, but HEWL had a considerable supplementary lytic effect. When the turbidity of A. actinomycetemcomitans (ATCC 29522) or H. aphrophilus (ATCC 33389) suspended in Tris buffer was monitored at close pH intervals (0.2) from pH 5.2 to 9.2, maximal lysis of ATCC 29522 occurred with EDTA at pH 8.0 and with EDTA-HEWL at pH 7.6, while ATCC 33389 lysed with EDTA at pH 9.0 and with EDTA-HEWL at pH 9.2. When other members of the family Pasteurellaceae (Haemophilus influenzae type b, Haemophilus paraphrophilus, Pasteurella multocida, Pasteurella haemolytica, and Pasteurella ureae) were included for comparison, the group I strains of A. actinomycetemcomitans were the most rapidly lysed by EDTA. H. paraphrophilus was the least sensitive of the gram-negative strains tested, but not as resistant as Micrococcus luteus (control). M. luteus was the organism most sensitive to lysozyme, followed by P. ureae and the group II strains of A. actinomycetemcomitans, while the group I strains of A. actinomycetemcomitans, H. paraphrophilus, and P. haemolytica were the least sensitive organisms. Images PMID:3935663

  9. Experimental Identification of Actinobacillus pleuropneumoniae Strains L20 and JL03 Heptosyltransferases, Evidence for a New Heptosyltransferase Signature Sequence

    PubMed Central

    Merino, Susana; Knirel, Yuriy A.; Regué, Miguel; Tomás, Juan M.

    2013-01-01

    We experimentally identified the activities of six predicted heptosyltransferases in Actinobacillus pleuropneumoniae genome serotype 5b strain L20 and serotype 3 strain JL03. The initial identification was based on a bioinformatic analysis of the amino acid similarity between these putative heptosyltrasferases with others of known function from enteric bacteria and Aeromonas. The putative functions of all the Actinobacillus pleuropneumoniae heptosyltrasferases were determined by using surrogate LPS acceptor molecules from well-defined A. hydrophyla AH-3 and A. salmonicida A450 mutants. Our results show that heptosyltransferases APL_0981 and APJL_1001 are responsible for the transfer of the terminal outer core D-glycero-D-manno-heptose (D,D-Hep) residue although they are not currently included in the CAZY glycosyltransferase 9 family. The WahF heptosyltransferase group signature sequence [S(T/S)(GA)XXH] differs from the heptosyltransferases consensus signature sequence [D(TS)(GA)XXH], because of the substitution of D261 for S261, being unique. PMID:23383222

  10. Evolutionary Divergence of Aggregatibacter actinomycetemcomitans.

    PubMed

    Kittichotirat, W; Bumgarner, R E; Chen, C

    2016-01-01

    Gram-negative facultative Aggregatibacter actinomycetemcomitans is an oral pathogen associated with periodontitis. The genetic heterogeneity among A. actinomycetemcomitans strains has been long recognized. This study provides a comprehensive genomic analysis of A. actinomycetemcomitans and the closely related nonpathogenic Aggregatibacter aphrophilus. Whole genome sequencing by Illumina MiSeq platform was performed for 31 A. actinomycetemcomitans and 2 A. aphrophilus strains. Sequence similarity analysis shows a total of 3,220 unique genes across the 2 species, where 1,550 are core genes present in all genomes and 1,670 are variable genes (accessory genes) missing in at least 1 genome. Phylogenetic analysis based on 397 concatenated core genes distinguished A. aphrophilus and A. actinomycetemcomitans. The latter was in turn divided into 5 clades: clade b (serotype b), clade c (serotype c), clade e/f (serotypes e and f), clade a/d (serotypes a and d), and clade e' (serotype e strains). Accessory genes accounted for 14.1% to 23.2% of the A. actinomycetemcomitans genomes, with a majority belonging to the category of poorly characterized by Cluster of Orthologous Groups classification. These accessory genes were often organized into genomic islands (n = 387) with base composition biases, suggesting their acquisitions via horizontal gene transfer. There was a greater degree of similarity in gene content and genomic islands among strains within clades than between clades. Strains of clade e' isolated from human were found to be missing the genomic island that carries genes encoding cytolethal distending toxins. Taken together, the results suggest a pattern of sequential divergence, starting from the separation of A. aphrophilus and A. actinomycetemcomitans through gain and loss of genes and ending with the divergence of the latter species into distinct clades and serotypes. With differing constellations of genes, the A. actinomycetemcomitans clades may have evolved

  11. Microarray-based comparative genomic profiling of reference strains and selected Canadian field isolates of Actinobacillus pleuropneumoniae

    PubMed Central

    Gouré, Julien; Findlay, Wendy A; Deslandes, Vincent; Bouevitch, Anne; Foote, Simon J; MacInnes, Janet I; Coulton, James W; Nash, John HE; Jacques, Mario

    2009-01-01

    Background Actinobacillus pleuropneumoniae, the causative agent of porcine pleuropneumonia, is a highly contagious respiratory pathogen that causes severe losses to the swine industry worldwide. Current commercially-available vaccines are of limited value because they do not induce cross-serovar immunity and do not prevent development of the carrier state. Microarray-based comparative genomic hybridizations (M-CGH) were used to estimate whole genomic diversity of representative Actinobacillus pleuropneumoniae strains. Our goal was to identify conserved genes, especially those predicted to encode outer membrane proteins and lipoproteins because of their potential for the development of more effective vaccines. Results Using hierarchical clustering, our M-CGH results showed that the majority of the genes in the genome of the serovar 5 A. pleuropneumoniae L20 strain were conserved in the reference strains of all 15 serovars and in representative field isolates. Fifty-eight conserved genes predicted to encode for outer membrane proteins or lipoproteins were identified. As well, there were several clusters of diverged or absent genes including those associated with capsule biosynthesis, toxin production as well as genes typically associated with mobile elements. Conclusion Although A. pleuropneumoniae strains are essentially clonal, M-CGH analysis of the reference strains of the fifteen serovars and representative field isolates revealed several classes of genes that were divergent or absent. Not surprisingly, these included genes associated with capsule biosynthesis as the capsule is associated with sero-specificity. Several of the conserved genes were identified as candidates for vaccine development, and we conclude that M-CGH is a valuable tool for reverse vaccinology. PMID:19239696

  12. The T Cell Response to Actinobacillus actinomycetemcomitans

    DTIC Science & Technology

    2006-05-01

    disease (11). Other clinical features of the disease include deep pain on mastication, first molar mobility, distolabial migration of maxillary incisors...transformed into one shot chemically competent E. coli TOP -10 (InVitrogen). 40 .tl from each transformation was grown at 37°C overnight on LB plates...5. Peripheral Blood Mononuclear Cells (PBMCs) isolation The 13 ml vacutainer with SST Gel and Clot Activator, or "Tiger Top ," was centrifuged at 3800

  13. Serological characterisation and antimicrobial susceptibility of Actinobacillus pleuropneumoniae strains isolated from pigs in Spain.

    PubMed

    Gutiérrez, C B; Rodríguez Barbosa, J I; Tascón, R I; Costa, L; Riera, P; Rodríguez Ferri, E F

    1995-07-15

    Seventy-one isolates of Actinobacillus pleuropneumoniae isolated from the lungs of pigs in outbreaks of pleuropneumonia in Spain were serotyped by indirect haemagglutination. Serotype 4 (42.2 per cent), serotype 7 (22.5 per cent) and serotype 2 (12.8 per cent) were predominant, whereas serotypes 1, 3, 6, 8, 9, 12 and untypable isolates were present only in small numbers. Serotypes 1, 2, 4 and 7 originated mainly from cases of acute pleuropneumonia, whereas serotypes 3, 6, 8, 9 and 12 were associated with chronically infected herds. The susceptibility of the isolates to 20 antimicrobial agents was determined by agar disc diffusion. Most were susceptible to cefuroxime, cefaclor, cefazolin, kanamycin, tobramycin, gentamicin, oxolinic acid, ciprofloxacin, enoxacin, thiamphenicol, colistin and trimethoprim/sulphamethoxazole. Marked resistance was found with amoxicillin, ticarcillin, oxytetracycline, doxycycline and metronidazole. Rifampicin, fosfomycin and tiamulin were the agents most effective against the isolates tested.

  14. Integration host factor is required for replication of pYGK-derived plasmids in Aggregatibacter actinomycetemcomitans.

    PubMed

    Torres-Escobar, Ascención; Juárez-Rodríguez, María D; Demuth, Donald R

    2014-08-01

    In this study, we show that integration host factor protein (IHF) is required for replication of pYGK plasmids in Aggregatibacter actinomycetemcomitans. YGK plasmids were not replicated in A. actinomycetemcomitans strains lacking either the α- or β- subunit of IHF. However, the deletion mutants were complemented, and plasmid replication was restored when the promoter region and gene for either ihfA or ihfB was cloned into pYGK. We also identified two motifs that resemble the consensus IHF-binding site in a 813-bp fragment containing the pYGK origin of replication. Using electrophoretic mobility shift assays, purified IHFα-IHFβ protein complex was shown to bind to probes containing either of these motifs. To our knowledge, this is the first report showing that plasmid replication is IHF-dependent in the family Pasteurellaceae. In addition, using site-direct mutagenesis, the XbaI and KpnI restriction sites in the suicide vector pJT1 were modified to generate plasmid pJT10. The introduction of these new unique sites in pJT10 facilitates the transfer of transcriptional or translational lacZ fusion constructs for the generation of single-copy chromosomal insertion of the reporter construct. Plasmid pJT10 and its derivatives will be useful for genetic studies in Aggregatibacter (Actinobacillus) and probably other genera of Pasteurellaceae, including Haemophilus, Pasteurella, and Mannheimia.

  15. Microevolution and Patterns of Dissemination of the JP2 Clone of Aggregatibacter (Actinobacillus) actinomycetemcomitans▿

    PubMed Central

    Haubek, Dorte; Poulsen, Knud; Kilian, Mogens

    2007-01-01

    The natural history, microevolution, and patterns of interindividual transmission and global dissemination of the JP2 clone of Aggregatibacter (Actinobacillus) actinomycetemcomitans were studied by population genetic analysis. The JP2 clone is strongly associated with aggressive periodontitis in adolescents of African descent and differs from other clones of the species by several genetic peculiarities, including a 530-bp deletion in the promoter region of the leukotoxin gene operon, which results in increased leukotoxic activity. Multilocus sequence analysis of 82 A. actinomycetemcomitans strains, 66 of which were JP2 clone strains collected over a period of more than 20 years, confirmed that there is a clonal population structure with evolutionary lineages corresponding to serotypes. Although genetically highly conserved, as shown by alignment of sequences of eight housekeeping genes, strains belonging to the JP2 clone had a number of point mutations, particularly in the pseudogenes hbpA and tbpA. Characteristic mutations allowed isolates from individuals from the Mediterranean area and from West Africa, including the Cape Verde Islands, to be distinguished. The patterns of mutations indicate that the JP2 clone initially emerged as a distinct genotype in the Mediterranean part of Africa approximately 2,400 years ago and subsequently spread to West Africa, from which it was transferred to the American continents during the transatlantic slave trade. The sustained exclusive colonization of individuals of African descent despite geographical separation for centuries suggests that the JP2 clone has a distinct host tropism. The colonization of family members by JP2 clone strains with unique point mutations provides strong evidence that there is intrafamilial transmission and suggests that dissemination of the JP2 clone is restricted to close contacts. PMID:17353281

  16. Proteomics of Aggregatibacter actinomycetemcomitans Outer Membrane Vesicles.

    PubMed

    Kieselbach, Thomas; Zijnge, Vincent; Granström, Elisabeth; Oscarsson, Jan

    2015-01-01

    Aggregatibacter actinomycetemcomitans is an oral and systemic pathogen associated with aggressive forms of periodontitis and with endocarditis. Outer membrane vesicles (OMVs) released by this species have been demonstrated to deliver effector proteins such as cytolethal distending toxin (CDT) and leukotoxin (LtxA) into human host cells and to act as triggers of innate immunity upon carriage of NOD1- and NOD2-active pathogen-associated molecular patterns (PAMPs). To improve our understanding of the pathogenicity-associated functions that A. actinomycetemcomitans exports via OMVs, we studied the proteome of density gradient-purified OMVs from a rough-colony type clinical isolate, strain 173 (serotype e) using liquid chromatography-tandem mass spectrometry (LC-MS/MS). This analysis yielded the identification of 151 proteins, which were found in at least three out of four independent experiments. Data are available via ProteomeXchange with identifier PXD002509. Through this study, we not only confirmed the vesicle-associated release of LtxA, and the presence of proteins, which are known to act as immunoreactive antigens in the human host, but we also identified numerous additional putative virulence-related proteins in the A. actinomycetemcomitans OMV proteome. The known and putative functions of these proteins include immune evasion, drug targeting, and iron/nutrient acquisition. In summary, our findings are consistent with an OMV-associated proteome that exhibits several offensive and defensive functions, and they provide a comprehensive basis to further disclose roles of A. actinomycetemcomitans OMVs in periodontal and systemic disease.

  17. AI-2 of Aggregatibacter actinomycetemcomitans inhibits Candida albicans biofilm formation.

    PubMed

    Bachtiar, Endang W; Bachtiar, Boy M; Jarosz, Lucja M; Amir, Lisa R; Sunarto, Hari; Ganin, Hadas; Meijler, Michael M; Krom, Bastiaan P

    2014-01-01

    Aggregatibacter actinomycetemcomitans, a Gram-negative bacterium, and Candida albicans, a polymorphic fungus, are both commensals of the oral cavity but both are opportunistic pathogens that can cause oral diseases. A. actinomycetemcomitans produces a quorum-sensing molecule called autoinducer-2 (AI-2), synthesized by LuxS, that plays an important role in expression of virulence factors, in intra- but also in interspecies communication. The aim of this study was to investigate the role of AI-2 based signaling in the interactions between C. albicans and A. actinomycetemcomitans. A. actinomycetemcomitans adhered to C. albicans and inhibited biofilm formation by means of a molecule that was secreted during growth. C. albicans biofilm formation increased significantly when co-cultured with A. actinomycetemcomitans luxS, lacking AI-2 production. Addition of wild-type-derived spent medium or synthetic AI-2 to spent medium of the luxS strain, restored inhibition of C. albicans biofilm formation to wild-type levels. Addition of synthetic AI-2 significantly inhibited hypha formation of C. albicans possibly explaining the inhibition of biofilm formation. AI-2 of A. actinomycetemcomitans is synthesized by LuxS, accumulates during growth and inhibits C. albicans hypha- and biofilm formation. Identifying the molecular mechanisms underlying the interaction between bacteria and fungi may provide important insight into the balance within complex oral microbial communities.

  18. Azithromycin kills invasive Aggregatibacter actinomycetemcomitans in gingival epithelial cells.

    PubMed

    Lai, Pin-Chuang; Walters, John D

    2013-03-01

    Aggregatibacter actinomycetemcomitans invades periodontal pocket epithelium and is therefore difficult to eliminate by periodontal scaling and root planing. It is susceptible to azithromycin, which is taken up by many types of mammalian cells. This led us to hypothesize that azithromycin accumulation by gingival epithelium could enhance the killing of intraepithelial A. actinomycetemcomitans. [(3)H]azithromycin transport by Smulow-Glickman gingival epithelial cells and SCC-25 oral epithelial cells was characterized. To test our hypothesis, we infected cultured Smulow-Glickman cell monolayers with A. actinomycetemcomitans (Y4 or SUNY 465 strain) for 2 h, treated them with gentamicin to eliminate extracellular bacteria, and then incubated them with azithromycin for 1 to 4 h. Viable intracellular bacteria were released, plated, and enumerated. Azithromycin transport by both cell lines exhibited Michaelis-Menten kinetics and was competitively inhibited by l-carnitine and several other organic cations. Cell incubation in medium containing 5 μg/ml azithromycin yielded steady-state intracellular concentrations of 144 μg/ml in SCC-25 cells and 118 μg/ml in Smulow-Glickman cells. Azithromycin induced dose- and time-dependent intraepithelial killing of both A. actinomycetemcomitans strains. Treatment of infected Smulow-Glickman cells with 0.125 μg/ml azithromycin killed approximately 29% of the intraepithelial CFU of both strains within 4 h, while treatment with 8 μg/ml azithromycin killed ≥82% of the CFU of both strains (P < 0.05). Addition of carnitine inhibited the killing of intracellular bacteria by azithromycin (P < 0.05). Thus, human gingival epithelial cells actively accumulate azithromycin through a transport system that facilitates the killing of intraepithelial A. actinomycetemcomitans and is shared with organic cations.

  19. Mature Biofilm Degradation by Potential Probiotics: Aggregatibacter actinomycetemcomitans versus Lactobacillus spp.

    PubMed Central

    Mizuno, Kouhei; Okinaga, Toshinori

    2016-01-01

    The biofilm degradation of Aggregatibacter actinomycetemcomitans is essential as a complete periodontal disease therapy, and here we show the effects of potential probiotic bacteria such as Lactobacillus spp. for the biofilm of several serotypes of A. actinomycetemcomitans strains. Eight of the 13 species showed the competent biofilm degradation of ≥ 90% reduction in biofilm values in A. actinomycetemcomitans Y4 (serotype b) as well as four of the seven species for the biofilm of A. actinomycetemcomitans OMZ 534 (serotype e). In contrast, the probiotic bacteria did not have a big impact for the degradation of A. actinomycetemcomitans SUNY 75 (serotype a) biofilm. The dispersed A. actinomycetemcomitans Y4 cells through the biofilm detachment were still viable and plausible factors for the biofilm degradation were not due to the lactic acid and low pH conditions. The three enzymes, protease, lipase, and amylase may be responsible for the biofilm degradation; in particular, lipase was the most effective enzyme for the biofilm degradation of A. actinomycetemcomitans Y4 along with the protease activity which should be also important for the other serotypes. Remarkable lipase enzyme activities were detected from some of the potential probiotics and a supporting result using a lipase inhibitor presented corroborating evidence that lipase activity is one of the contributing factors for biofilm degradation outside of the protease which is also another possible factor for the biofilm of the other serotype of A. actinomycetemcomitans strains. On the other hand, the biofilm of A. actinomycetemcomitans SUNY 75 (serotype a) was not powerfully degraded by the lipase enzyme because the lipase inhibitor was slightly functional for only two of potential probiotics. PMID:27438340

  20. Prophage induction in lysogenic Aggregatibacter actinomycetemcomitans cells co-cultured with human gingival fibroblasts, and its effect on leukotoxin release.

    PubMed

    Stevens, Roy H; de Moura Martins Lobo Dos Santos, Caroline; Zuanazzi, David; de Accioly Mattos, Marcelo Barbosas; Ferreira, Davis Fernandes; Kachlany, Scott C; Tinoco, Eduardo M B

    2013-01-01

    Lysogeny is common among strains of the periodontal pathogen Aggregatibacter actinomycetemcomitans. Since lysogenic induction is known to result in the increased synthesis and release of bacterial toxins from lysogens, it would be important to elucidate the conditions under which induction of these bacteria may occur. Co-cultures of A. actinomycetemcomitans strains (either lysogenic or non-lysogenic) and human cells (either gingival fibroblasts or pharyngeal epithelial cells) were prepared. Following incubation, bacteriophage titers of up to 6.2 × 10(7) pfu/ml were detected in the cell-free, spent culture media from the co-cultures of the lysogenic A. actinomycetemcomitans strains and the fibroblasts. Little (maximum of 2 × 10(0) pfu/ml) or no titers of phage could be detected in the mono-cultures of the lysogenic A. actinomycetemcomitans strains alone. In contrast, no phage were detectable in the cell-free spent culture media of the lysogens cocultured with the epithelial cells. Futhermore, co-culture of the A. actinomycetemcomitans lysogens with the fibroblasts resulted in enhanced release of the A. actinomycetemcomitans leukotoxin into the culture medium, in comparison with the spent culture media from mono-cultures of the lysogens alone. These results are consistent with the concept that interaction with fibroblasts may mediate prophage induction in lysogenic strains of A. actinomycetemcomitans, and that leukotoxin release is greatly augmented following induction of the lysogens.

  1. The cell envelope proteome of Aggregatibacter actinomycetemcomitans.

    PubMed

    Smith, K P; Fields, J G; Voogt, R D; Deng, B; Lam, Y-W; Mintz, K P

    2015-04-01

    The cell envelope of gram-negative bacteria serves a critical role in maintenance of cellular homeostasis, resistance to external stress, and host-pathogen interactions. Envelope protein composition is influenced by the physiological and environmental demands placed on the bacterium. In this study, we report a comprehensive compilation of cell envelope proteins from the periodontal and systemic pathogen Aggregatibacter actinomycetemcomitans VT1169, an afimbriated serotype b strain. The urea-extracted membrane proteins were identified by mass spectrometry-based shotgun proteomics. The membrane proteome, isolated from actively growing bacteria under normal laboratory conditions, included 648 proteins representing 27% of the predicted open reading frames in the genome. Bioinformatic analyses were used to annotate and predict the cellular location and function of the proteins. Surface adhesins, porins, lipoproteins, numerous influx and efflux pumps, multiple sugar, amino acid and iron transporters, and components of the type I, II and V secretion systems were identified. Periplasmic space and cytoplasmic proteins with chaperone function were also identified. A total of 107 proteins with unknown function were associated with the cell envelope. Orthologs of a subset of these uncharacterized proteins are present in other bacterial genomes, whereas others are found exclusively in A. actinomycetemcomitans. This knowledge will contribute to elucidating the role of cell envelope proteins in bacterial growth and survival in the oral cavity.

  2. Role of exopolysaccharide in Aggregatibacter actinomycetemcomitans-induced bone resorption in a rat model for periodontal disease.

    PubMed

    Shanmugam, Mayilvahanan; Gopal, Prerna; El Abbar, Faiha; Schreiner, Helen C; Kaplan, Jeffrey B; Fine, Daniel H; Ramasubbu, Narayanan

    2015-01-01

    Aggregatibacter actinomycetemcomitans a causative agent of periodontal disease in humans, forms biofilm on biotic and abiotic surfaces. A. actinomycetemcomitans biofilm is heterogeneous in nature and is composed of proteins, extracellular DNA and exopolysaccharide. To explore the role played by the exopolysaccharide in the colonization and disease progression, we employed genetic reduction approach using our rat model of A. actinomycetemcomitans-induced periodontitis. To this end, a genetically modified strain of A. actinomycetemcomitans lacking the pga operon was compared with the wild-type strain in the rat infection model. The parent and mutant strains were primarily evaluated for bone resorption and disease. Our study showed that colonization, bone resorption/disease and antibody response were all elevated in the wild-type fed rats. The bone resorption/disease caused by the pga mutant strain, lacking the exopolysaccharide, was significantly less (P < 0.05) than the bone resorption/disease caused by the wild-type strain. Further analysis of the expression levels of selected virulence genes through RT-PCR showed that the decrease in colonization, bone resorption and antibody titer in the absence of the exopolysaccharide might be due to attenuated levels of colonization genes, flp-1, apiA and aae in the mutant strain. This study demonstrates that the effect exerted by the exopolysaccharide in A. actinomycetemcomitans-induced bone resorption has hitherto not been recognized and underscores the role played by the exopolysaccharide in A. actinomycetemcomitans-induced disease.

  3. Antimicrobial effect of chlorhexidine on Aggregatibacter actinomycetemcomitans biofilms associated with peri-implantitis.

    PubMed

    Kadkhoda, Zeinab; Amarlu, Zeinab; Eshraghi, Saeed; Samiei, Nazanin

    2016-01-01

    Background. This study aimed to assessthe antimicrobial effect of chlorhexidine (CHX) on Aggregatibacter actinomycetemcomitans biofilms isolated from subgingival plaque of peri-implantitis lesions. Methods. Thirteen patients requiring peri-implantitis treatment were consecutively selected and their subgingival biofilm was collected by inserting fine sterile paper points into peri-implant pockets for 15 seconds. A. actinomycetemcomitans was isolated from the subgingival biofilm and cultured. In this study, the standard strain of A. actinomycetemcomitans served as the positive control group and a blank disc impregnated with water served as the negative control; 0.1 mL of the bacterial suspension was cultured on specific culture medium and blank discs (6 mm in diameter) impregnated with 0.2%CHX mouthrinse (Behsa Pharmaceutical Co.) and negative control discs were placed on two sides of the bacterial culture plate. The size of growth inhibition zone was measured by a blinded independent observer in millimetres. Results. According to the results of disc diffusion test, the mean diameter of growth inhibition zone of A. actinomycetemcomitans around discs impregnated with CHX was larger in both standard (positive control) and biofilm samples of A. actinomycetemcomitans compared to the negative control group (blank disc) (P<0.001). Conclusion . Use of0.2% CHX mouthwash had antibacterial effects on A. actinomycetemcomitans species isolated from peri-implantitis sites.

  4. Antimicrobial effect of chlorhexidine on Aggregatibacter actinomycetemcomitans biofilms associated with peri-implantitis

    PubMed Central

    Kadkhoda, Zeinab; Amarlu, Zeinab; Eshraghi, Saeed; Samiei, Nazanin

    2016-01-01

    Background. This study aimed to assessthe antimicrobial effect of chlorhexidine (CHX) on Aggregatibacter actinomycetemcomitans biofilms isolated from subgingival plaque of peri-implantitis lesions. Methods. Thirteen patients requiring peri-implantitis treatment were consecutively selected and their subgingival biofilm was collected by inserting fine sterile paper points into peri-implant pockets for 15 seconds. A. actinomycetemcomitans was isolated from the subgingival biofilm and cultured. In this study, the standard strain of A. actinomycetemcomitans served as the positive control group and a blank disc impregnated with water served as the negative control; 0.1 mL of the bacterial suspension was cultured on specific culture medium and blank discs (6 mm in diameter) impregnated with 0.2%CHX mouthrinse (Behsa Pharmaceutical Co.) and negative control discs were placed on two sides of the bacterial culture plate. The size of growth inhibition zone was measured by a blinded independent observer in millimetres. Results. According to the results of disc diffusion test, the mean diameter of growth inhibition zone of A. actinomycetemcomitans around discs impregnated with CHX was larger in both standard (positive control) and biofilm samples of A. actinomycetemcomitans compared to the negative control group (blank disc) (P<0.001). Conclusion. Use of0.2% CHX mouthwash had antibacterial effects on A. actinomycetemcomitans species isolated from peri-implantitis sites. PMID:27651884

  5. Human Serum-Specific Activation of Alternative Sigma Factors, the Stress Responders in Aggregatibacter actinomycetemcomitans

    PubMed Central

    Tang-Siegel, Gaoyan; Bumgarner, Roger; Ruiz, Teresa; Kittichotirat, Weerayuth; Chen, Weizhen; Chen, Casey

    2016-01-01

    Aggregatibacter actinomycetemcomitans, a known pathogen causing periodontal disease and infective endocarditis, is a survivor in the periodontal pocket and blood stream; both environments contain serum as a nutrient source. To screen for unknown virulence factors associated with this microorganism, A. actinomycetemcomitans was grown in serum-based media to simulate its in vivo environment. Different strains of A. actinomycetemcomitans showed distinct growth phenotypes only in the presence of human serum, and they were grouped into high- and low-responder groups. High-responders comprised mainly serotype c strains, and showed an unusual growth phenomenon, featuring a second, rapid increase in turbidity after 9-h incubation that reached a final optical density 2- to 7-fold higher than low-responders. Upon further investigation, the second increase in turbidity was not caused by cell multiplication, but by cell death. Whole transcriptomic analysis via RNA-seq identified 35 genes that were up-regulated by human serum, but not horse serum, in high-responders but not in low-responders, including prominently an alternative sigma factor rpoE (σE). A lacZ reporter construct driven by the 132-bp rpoE promoter sequence of A. actinomycetemcomitans responded dramatically to human serum within 90 min of incubation only when the construct was carried by a high responder strain. The rpoE promoter is 100% identical among high- and low-responder strains. Proteomic investigation showed potential interactions between human serum protein, e.g. apolipoprotein A1 (ApoA1) and A. actinomycetemcomitans. The data clearly indicated a different activation process for rpoE in high- versus low-responder strains. This differential human serum-specific activation of rpoE, a putative extra-cytoplasmic stress responder and global regulator, suggests distinct in vivo adaptations among different strains of A. actinomycetemcomitans. PMID:27490177

  6. [Microbiological approach to a possible infective endocarditis case caused by Aggregatibacter actinomycetemcomitans].

    PubMed

    Gürcan, Şaban; Ünlü, Selahattin; Kuloğlu, Figen; Karadenizli, Aynur; Kuşkucu, Mert Ahmet

    2016-04-01

    Aggregatibacter (Actinobacillus) actinomycetemcomitans, a small, gram-negative coccobacillus that grows slow and fastidious, is generally colonized in the oral cavity. It is a rarely seen bacterium because of the difficulty of isolation but it can be a causative agent for dental infections and infective endocarditis (IE) particularly in the persons having prosthetic heart valves. In this report, a possible IE case caused by A.actinomycetemcomitans in a patient with aortic valve replacement has been presented. A 36-year-old man has admitted to Trakya University Hospital, Health Center for Medical Research and Practice, with the complaints of chills, malaise, intermittent fever, severe arthralgia and weight loss (20 kg). During his follow-up period, the blood cultures that were obtained three week intervals yielded the identical gram-negative coccobacilli morphology. The patient was then diagnosed as possible IE on the basis of having one major (growth of the typical microorganisms that may cause IE in two different blood cultures) and two minor (presence of prosthetic valve and high fever) criterias. The isolate could not be identified with conventional methods, while it was identified as Francisella tularensis with VITEK 2 (bioMerieux, France) system. Hence this identification was not confirmed by real-time Taqman polymerase chain reaction, so MALDI-TOF mass spectrometry was used to identify this bacteria. In the first run of the study, the isolate was named as Shigella dysenteriae initially, however when it was retested the next day it was identified as A.actinomycetemcomitans. In order to enlighten these conflicting results, 16S and 23S ribosomal DNA sequence analysis was performed, and consequently the bacterium was identified as A.actinomycetemcomitans. Doxycycline (2 x 100 mg po, 20 days) and streptomycin (2 x 10 mg/kg im, 10 days) therapy were initiated, considering the initial suspicious identification (F.tularensis), and on the fifth day of therapy the

  7. Virulence of Aggregatibacter actinomycetemcomitans serotypes and DGGE subtypes isolated from chronic adult periodontitis in Thailand.

    PubMed

    Pahumunto, Nuntiya; Ruangsri, Praphansri; Wongsuwanlert, Mutita; Piwat, Supatcharin; Dahlen, Gunnar; Teanpaisan, Rawee

    2015-12-01

    A high proportion of non-serotypeable isolates of Aggregatibacter actinomycetemcomitans among Thai periodontitis cases has been previously reported. The aim of this study was to investigate the expression of leukotoxin and toxicity, cytolethal distending toxin (Cdts), and internalization and the killing effect on fibroblasts by A. actinomycetemcomitans subtypes from Thai chronic periodontitis cases. A total of 96 A. actinomycetemcomitans strains from 37 periodontitis cases, previously serotyped with PCR and subtyped with DGGE, were examined for the presence of the ltx gene and cdt genes (cdtBC), and tested for leukotoxin expression, leukotoxicity, internalization, and apoptosis of fibroblast cells. The ltx gene was present in all isolates, while 84.4% showed the cdtBC gene. Two strains with a JP2-like ltx gene with a deletion of 530 bp in the promoter region, serotyped as c, showed virulence of similar magnitude to the JP2 strain. Furthermore, a higher virulence was found in the two non-serotypeable DGGE subtypes, NS1 and NS2, compared with the serotypeable strains (serotype a-f, serotype b and d were absent). Generally, the virulence of strains obtained from deep periodontal pockets was higher than those isolated from shallow non-bleeding pockets. A. actinomycetemcomitans subtypes isolated from adult Thais with chronic periodontitis showed a highly variable virulence, leukotoxin expression, leukotoxicity, internalization and apoptosis of fibroblast, and are regulated both genetically and environmentally.

  8. Aggregatibacter actinomycetemcomitans arcB influences hydrophobic properties, biofilm formation and adhesion to hydroxyapatite

    PubMed Central

    Longo, PL; Ota-Tsuzuki, C; Nunes, ACR; Fernandes, BL; Mintz, K; Fives-Taylor, P; Mayer, MPA

    2009-01-01

    The regulation of gene expression in the oral pathogen Aggregatibacter actinomycetemcomitans is still not fully elucidated. ArcAB is a two-component system which allows facultative anaerobic bacteria to sense various respiratory growth conditions and adapt their gene expression accordingly.This study investigated in A. actinomycetemcomitans the role of ArcB on the regulation of biofilm formation, adhesion to saliva coated hydroxyapatite (SHA) and the hydrophobic properties of the cell. These phenotypic traits were determined for an A. actinomycetemcomitans arcB deficient type and a wild type strain. Differences in hydrophobic properties were shown at early and late exponential growth phases under microaerobic incubation and at late exponential phase under anaerobiosis.The arcB mutant formed less biofilm than the wild type strain when grown under anaerobic incubation, but displayed higher biofilm formation activity under microaerobic conditions. The adherence to SHA was significantly lower in the mutant when compared with the wild type strain. These results suggest that the transmembrane sensor kinase ArcB, in A. actinomycetemcomitans, senses redox growth conditions and regulates the expression of surface components of the bacterial cell related to biofilm formation and adhesion to saliva coated surfaces. PMID:24031399

  9. The conserved carboxyl domain of MorC, an inner membrane protein of Aggregatibacter actinomycetemcomitans, is essential for membrane function.

    PubMed

    Smith, K P; Voogt, R D; Ruiz, T; Mintz, K P

    2016-02-01

    Morphogenesis protein C (MorC) of Aggregatibacter actinomycetemcomitans is important for maintaining the membrane morphology and integrity of the cell envelope of this oral pathogen. The MorC sequence and operon organization were found to be conserved in Gammaproteobacteria, based on a bioinformatic analysis of 435 sequences from representative organisms. Functional conservation of MorC was investigated using an A. actinomycetemcomitans morC mutant as a model system to express MorC homologs from four phylogenetically diverse representatives of the Gammaproteobacteria: Haemophilus influenzae, Escherichia coli, Pseudomonas aeruginosa, and Moraxella catarrhalis. The A. actinomycetemcomitans strains expressing the homologous proteins were assessed for sensitivity to bile salts, leukotoxin secretion, autoaggregation and membrane morphology. MorC from the most closely related organism (H. influenzae) was functionally identical to MorC from A. actinomycetemcomitans. However, the genes from more distantly related organisms restored some but not all A. actinomycetemcomitans mutant phenotypes. In addition, deletion mutagenesis indicated that the most conserved portion of the protein, the C-terminus DUF490 domain, was necessary to maintain the integrity of the membrane. Deletion of the last 10 amino acids of this domain of the A. actinomycetemcomitans MorC protein was sufficient to disrupt membrane stability and leukotoxin secretion. The data suggest that the MorC sequence is functionally conserved across Gammaproteobacteria and the C-terminus of the protein is essential for maintaining membrane physiology.

  10. Detection of antimicrobial activity of banana peel (Musa paradisiaca L.) on Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans: An in vitro study

    PubMed Central

    Kapadia, Suraj Premal; Pudakalkatti, Pushpa S.; Shivanaikar, Sachin

    2015-01-01

    Introduction and Aim: Banana is used widely because of its nutritional values. In past, there are studies that show banana plant parts, and their fruits can be used to treat the human diseases. Banana peel is a part of banana fruit that also has the antibacterial activity against microorganisms but has not been studied extensively. Since, there are no studies that relate the antibacterial activity of banana peel against periodontal pathogens. Hence, the aim of this study is to determine the antimicrobial activity of banana peel extract on Porphyromonas gingivalis (P. gingivalis) and Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans). Material and Methods: Standard strains of P. gingivalis and A. actinomycetemcomitans were used in this study which was obtained from the in-house bacterial bank of Department of Molecular Biology and Immunology at Maratha Mandal's Nathajirao G. Halgekar Institute of Dental Sciences and Research Centre. The banana peel extract was prepared, and the antibacterial activity was assessed using well agar diffusion method and minimum inhibitory concentration was assessed using serial broth dilution method. Results: In the current study, both the tested microorganisms showed antibacterial activity. In well diffusion method, P. gingivalis and A. actinomycetemcomitans showed 15 mm and 12 mm inhibition zone against an alcoholic extract of banana peel, respectively. In serial broth dilution method P. gingivalis and A. actinomycetemcomitans were sensitive until 31.25 μg/ml dilutions. Conclusion: From results of the study, it is suggested that an alcoholic extract of banana peel has antimicrobial activity against P. gingivalis and A. actinomycetemcomitans. PMID:26681854

  11. Pharmacokinetics of tildipirosin in porcine plasma, lung tissue, and bronchial fluid and effects of test conditions on in vitro activity against reference strains and field isolates of Actinobacillus pleuropneumoniae.

    PubMed

    Rose, M; Menge, M; Bohland, C; Zschiesche, E; Wilhelm, C; Kilp, S; Metz, W; Allan, M; Röpke, R; Nürnberger, M

    2013-04-01

    The pharmacokinetics of tildipirosin (Zuprevo(®) 40 mg/mL solution for injection for pigs), a novel 16-membered-ring macrolide for the treatment for swine respiratory disease (SRD), was investigated in studies collecting blood plasma and postmortem samples of lung tissue and bronchial fluid (BF) from swine. In view of factors influencing the in vitro activity of macrolides, and for the interpretation of tildipirosin pharmacokinetics in relation to minimum inhibitory concentrations (MIC), additional experiments were conducted to study the effects of pH, carbon dioxide-enriched atmosphere, buffers, and serum on tildipirosin MICs for various reference strains and Actinobacillus (A.) pleuropneumoniae field isolates. After single intramuscular (i.m.) injection at 4 mg/kg body weight, maximum plasma concentration (Cmax) was 0.9 μg/mL observed within 23 min (Tmax ). Mean residence time from the time of dosing to the time of last measurable concentration (MRTlast) and terminal half-life (T1/2) both were about 4 days. A dose-response relationship with no significant sex effect is observed for area under the plasma concentration-time curve from time 0 to the last sampling time with a quantifiable drug concentration (AUClast) over the range of doses up to 6 mg/kg. However, linear dose proportionality could not be proven with statistical methods. The time-concentration profile of tildipirosin in BF and lung far exceeded that in blood plasma. In lung, tildipirosin concentrations reached 3.1 μg/g at 2 h, peaked at 4.3 μg/g at day 1, and slowly declined to 0.8 μg/g at day 17. In BF, tildipirosin levels were 14.3, 7.0, and 6.5 μg/g at days 5, 10, and 14. T1/2 in lung was ∼7 days. Tildipirosin is rapidly and extensively distributed to the respiratory tract followed by slow elimination. Culture media pH and carbon dioxide-enriched atmosphere (CO2 -EA) had a marked impact on in vitro activity of tildipirosin in reference strains of various rapidly growing aerobic and

  12. Pathogenicity of the highly leukotoxic JP2 clone of Aggregatibacter actinomycetemcomitans and its geographic dissemination and role in aggressive periodontitis

    PubMed Central

    Haubek, Dorte; Johansson, Anders

    2014-01-01

    For decades, Aggregatibacter actinomycetemcomitans has been associated with aggressive forms of periodontitis in adolescents. In the middle of the 1990s, a specific JP2 clone of A. actinomycetemcomitans, belonging to the cluster of serotype b strains of A. actinomycetemcomitans and having a number of other characteristics, was found to be strongly associated with aggressive forms of periodontitis, particularly in North Africa. Although several longitudinal studies still point to the bacterial species, A. actinomycetemcomitans as a risk factor of aggressive periodontitis, it is now also widely accepted that the highly leukotoxic JP2 clone of A. actinomycetemcomitans is implicated in rapidly progressing forms of aggressive periodontitis. The JP2 clone strains are highly prevalent in human populations living in Northern and Western parts of Africa. These strains are also prevalent in geographically widespread populations that have originated from the Northwest Africa. Only sporadic signs of a dissemination of the JP2 clone strains to non-African populations have been found despite Africans living geographically widespread for hundreds of years. It remains an unanswered question if a particular host tropism exists as a possible explanation for the frequent colonization of the Northwest African population with the JP2 clone. Two exotoxins of A. actinomycetemcomitans are known, leukotoxin (LtxA) and cytolethal distending toxin (Cdt). LtxA is able to kill human immune cells, and Cdt can block cell cycle progression in eukaryotic cells and thus induce cell cycle arrest. Whereas the leukotoxin production is enhanced in JP2 clone strains thus increasing the virulence potential of A. actinomycetemcomitans, it has not been possible so far to demonstrate such a role for Cdt. Lines of evidence have led to the understanding of the highly leukotoxic JP2 clone of A. actinomycetemcomitans as an aetiological factor of aggressive periodontitis. Patients, who are colonized with the JP2

  13. Pathogenicity of the highly leukotoxic JP2 clone of Aggregatibacter actinomycetemcomitans and its geographic dissemination and role in aggressive periodontitis.

    PubMed

    Haubek, Dorte; Johansson, Anders

    2014-01-01

    For decades, Aggregatibacter actinomycetemcomitans has been associated with aggressive forms of periodontitis in adolescents. In the middle of the 1990s, a specific JP2 clone of A. actinomycetemcomitans, belonging to the cluster of serotype b strains of A. actinomycetemcomitans and having a number of other characteristics, was found to be strongly associated with aggressive forms of periodontitis, particularly in North Africa. Although several longitudinal studies still point to the bacterial species, A. actinomycetemcomitans as a risk factor of aggressive periodontitis, it is now also widely accepted that the highly leukotoxic JP2 clone of A. actinomycetemcomitans is implicated in rapidly progressing forms of aggressive periodontitis. The JP2 clone strains are highly prevalent in human populations living in Northern and Western parts of Africa. These strains are also prevalent in geographically widespread populations that have originated from the Northwest Africa. Only sporadic signs of a dissemination of the JP2 clone strains to non-African populations have been found despite Africans living geographically widespread for hundreds of years. It remains an unanswered question if a particular host tropism exists as a possible explanation for the frequent colonization of the Northwest African population with the JP2 clone. Two exotoxins of A. actinomycetemcomitans are known, leukotoxin (LtxA) and cytolethal distending toxin (Cdt). LtxA is able to kill human immune cells, and Cdt can block cell cycle progression in eukaryotic cells and thus induce cell cycle arrest. Whereas the leukotoxin production is enhanced in JP2 clone strains thus increasing the virulence potential of A. actinomycetemcomitans, it has not been possible so far to demonstrate such a role for Cdt. Lines of evidence have led to the understanding of the highly leukotoxic JP2 clone of A. actinomycetemcomitans as an aetiological factor of aggressive periodontitis. Patients, who are colonized with the JP2

  14. A gene cluster for the synthesis of serotype g-specific polysaccharide antigen in Aggregatibacter actinomycetemcomitans.

    PubMed

    Tsuzukibashi, Osamu; Saito, Masanori; Kobayashi, Taira; Umezawa, Koji; Nagahama, Fumio; Hiroi, Takachika; Hirasawa, Masatomo; Takada, Kazuko

    2014-04-01

    Aggregatibacter actinomycetemcomitans is an important pathogen related to aggressively progressive periodontal breakdown in adolescents and adults. The species can be divided into six serotypes (a-f) according to their surface carbohydrate antigens. Recently, a new serotype g of A. actinomycetemcomitans was proposed. The aim of the present study was to sequence the gene cluster associated with the biosynthesis of the serotype g-specific polysaccharide antigen and develop serotype-specific primers for PCR assay to identify serotype g strains of A. actinomycetemcomitans. The serotype-specific polysaccharide (SSPS) gene cluster of the NUM-Aa 4039 strain contained 21 genes in 21,842-bp nucleotides. The similarity of the SSPS gene cluster sequence was 96.7 % compared with that of the serotype e strain. Seventeen serotype g genes showed more than 90 % homology both in nucleotide and amino acids to the serotype e strain. Three additional genes with 1,579 bp in NUM-Aa 4039 were inserted into the corresponding ORF13 of the serotype e strain. The serotype g-specific primers were designed from the insertion region of NUM-Aa 4039. Serotypes of the a-f strains were not amplified by serotype-specific g primers; only NUM-Aa 4039 showed an amplicon band. The NUM-Aa 4039 strain was three genes in the SSPS gene cluster different from those of serotype e strain. The specific primers derived from these different regions are useful for identification and distribution of serotype g strain among A. actinomycetemcomitans from clinical samples.

  15. Disease severity associated with presence in subgingival plaque of Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, and Tannerella forsythia, singly or in combination, as detected by nested multiplex PCR.

    PubMed

    Ready, D; D'Aiuto, F; Spratt, D A; Suvan, J; Tonetti, M S; Wilson, M

    2008-10-01

    This study used a nested multiplex PCR method to detect three periodontal pathogens in subgingival plaque collected before treatment and at 2 and 6 months posttreatment from 107 patients with severe, generalized periodontitis. The proportions of the patients who harbored these bacteria before periodontal treatment were as follows: Tannerella forsythia, 81%; Porphyromonas gingivalis, 78%; and Aggregatibacter (formerly Actinobacillus) actinomycetemcomitans, 47%. At 2 months posttreatment there was a significant reduction in the numbers of patients harboring P. gingivalis (46%; P < 0.001) or T. forsythia (63%; P = 0.043) but not A. actinomycetemcomitans (50%) compared to pretreatment data. At 6 months posttreatment, significantly fewer patients harbored P. gingivalis (43%; P < 0.001); A. actinomycetemcomitans, (31%; P = 0.025), or T. forsythia (63%; P = 0.030). Interestingly, at baseline and at 2 months posttherapy, subjects who harbored only a single pathogen had a greater level of periodontal disease than subjects who harbored two, or all three, of these periodontal pathogens. These data suggest that a reduction in the number of species present may be associated with an increase in the severity of periodontal diseases.

  16. Aggregatibacter actinomycetemcomitans cytolethal distending toxin activates the NLRP3 inflammasome in human macrophages, leading to the release of proinflammatory cytokines.

    PubMed

    Shenker, Bruce J; Ojcius, David M; Walker, Lisa P; Zekavat, Ali; Scuron, Monika Damek; Boesze-Battaglia, Kathleen

    2015-04-01

    The cytolethal distending toxin (Cdt) is produced from a number of bacteria capable of causing infection and inflammatory disease. Our previous studies with Actinobacillus actinomycetemcomitans Cdt demonstrate not only that the active toxin subunit functions as a phosphatidylinositol-3,4,5-triphosphate (PIP3) phosphatase but also that macrophages exposed to the toxin were stimulated to produce proinflammatory cytokines. We now demonstrate that the Cdt-induced proinflammatory response involves the activation of the NLRP3 inflammasome. Specific inhibitors and short hairpin RNA (shRNA) were employed to demonstrate requirements for NLRP3 and ASC as well as caspase-1. Furthermore, Cdt-mediated inflammasome activation is dependent upon upstream signals, including reactive oxygen species (ROS) generation and Cdt-induced increases in extracellular ATP levels. Increases in extracellular ATP levels contribute to the activation of the P2X7 purinergic receptor, leading to K+ efflux. The relationship between the abilities of the active toxin subunit CdtB to function as a lipid phosphatase, activate the NLRP3 inflammasome, and induce a proinflammatory cytokine response is discussed. These studies provide new insight into the virulence potential of Cdt in mediating the pathogenesis of disease caused by Cdt-producing organisms such as Aggregatibacter actinomycetemcomitans.

  17. Aggregatibacter actinomycetemcomitans Cytolethal Distending Toxin Activates the NLRP3 Inflammasome in Human Macrophages, Leading to the Release of Proinflammatory Cytokines

    PubMed Central

    Ojcius, David M.; Walker, Lisa P.; Zekavat, Ali; Scuron, Monika Damek; Boesze-Battaglia, Kathleen

    2015-01-01

    The cytolethal distending toxin (Cdt) is produced from a number of bacteria capable of causing infection and inflammatory disease. Our previous studies with Actinobacillus actinomycetemcomitans Cdt demonstrate not only that the active toxin subunit functions as a phosphatidylinositol-3,4,5-triphosphate (PIP3) phosphatase but also that macrophages exposed to the toxin were stimulated to produce proinflammatory cytokines. We now demonstrate that the Cdt-induced proinflammatory response involves the activation of the NLRP3 inflammasome. Specific inhibitors and short hairpin RNA (shRNA) were employed to demonstrate requirements for NLRP3 and ASC as well as caspase-1. Furthermore, Cdt-mediated inflammasome activation is dependent upon upstream signals, including reactive oxygen species (ROS) generation and Cdt-induced increases in extracellular ATP levels. Increases in extracellular ATP levels contribute to the activation of the P2X7 purinergic receptor, leading to K+ efflux. The relationship between the abilities of the active toxin subunit CdtB to function as a lipid phosphatase, activate the NLRP3 inflammasome, and induce a proinflammatory cytokine response is discussed. These studies provide new insight into the virulence potential of Cdt in mediating the pathogenesis of disease caused by Cdt-producing organisms such as Aggregatibacter actinomycetemcomitans. PMID:25644004

  18. The cytolethal distending toxin of Aggregatibacter actinomycetemcomitans inhibits macrophage phagocytosis and subverts cytokine production.

    PubMed

    Ando-Suguimoto, Ellen Sayuri; da Silva, Maike Paulino; Kawamoto, Dione; Chen, Casey; DiRienzo, Joseph M; Mayer, Marcia Pinto Alves

    2014-03-01

    Aggregatibacter actinomycetemcomitans is an important periodontal pathogen that can participate in periodontitis and other non-oral infections. The cytolethal distending toxin (Cdt) is among the virulence factors produced by this bacterium. The Cdt is also secreted by several mucosa-associated Gram-negative pathogens and may play a role in perpetuating the infection by modulating the immune response. Although the toxin targets a wide range of eukaryotic cell types little is known about its activity on macrophages which play a key part in alerting the rest of the immune system to the presence of pathogens and their virulence factors. In view of this, we tested the hypothesis that the A. actinomycetemcomitans Cdt (AaCdt) disrupts macrophage function by inhibiting phagocytic activity as well as affecting the production of cytokines. Murine macrophages were co-cultured with either wild-type A. actinomycetemcomitans or a Cdt(-) mutant. Viable counts and qPCR showed that phagocytosis of the wild-type strain was significantly reduced relative to that of the Cdt(-) mutant. Addition of recombinant Aa(r)Cdt to co-cultures along with the Cdt(-) mutant diminished the phagocytic activity similar to that observed with the wild type strain. High concentrations of Aa(r)Cdt resulted in decreased phagocytosis of fluorescent bioparticles. Nitric oxide production was modulated by the presence of Cdt and the levels of IL-1β, IL-12 and IL-10 were increased. Production of TNF-α did not differ in the co-culture assays but was increased by the presence of Aa(r)Cdt. These data suggest that the Cdt may modulate macrophage function in A. actinomycetemcomitans infected sites by impairing phagocytosis and modifying the pro-inflammatory/anti-inflammatory cytokine balance.

  19. Minimal inhibitory concentrations of antimicrobial agents against Actinobacillus pleuropneumoniae.

    PubMed Central

    Nadeau, M; Larivière, S; Higgins, R; Martineau, G P

    1988-01-01

    Forty-five isolates of Actinobacillus pleuropneumoniae were tested for susceptibility to 12 antimicrobial agents using a microdilution method for the minimal inhibitory concentration determinations. These results confirmed the high prevalence of A. pleuropneumoniae strains resistant to antibiotics as reported earlier using the disc diffusion method (Kirby-Bauer method). While 36% of the isolates were resistant to the penicillins, 47% were resistant to chloramphenicol and 68% were resistant to tetracycline. Minimal inhibitory concentrations for the resistant isolates were approximately 32 times higher than those for the susceptible isolates to the above antibacterial agents. The isolates were in general weakly susceptible or resistant to spectinomycin, lincomycin, tiamulin and spiramycin whereas most of them were susceptible to gentamicin, trimethoprim and erythromycin. The susceptibility pattern was similar throughout the 1980 to 1984 period. The 14 serotype 5 isolates were more resistant to tetracycline but less resistant to chloramphenicol and the penicillins than the 28 serotype 1 isolates. PMID:3167716

  20. Identification of a novel bacterial outer membrane interleukin-1Β-binding protein from Aggregatibacter actinomycetemcomitans.

    PubMed

    Paino, Annamari; Ahlstrand, Tuuli; Nuutila, Jari; Navickaite, Indre; Lahti, Maria; Tuominen, Heidi; Välimaa, Hannamari; Lamminmäki, Urpo; Pöllänen, Marja T; Ihalin, Riikka

    2013-01-01

    Aggregatibacter actinomycetemcomitans is a gram-negative opportunistic oral pathogen. It is frequently associated with subgingival biofilms of both chronic and aggressive periodontitis, and the diseased sites of the periodontium exhibit increased levels of the proinflammatory mediator interleukin (IL)-1β. Some bacterial species can alter their physiological properties as a result of sensing IL-1β. We have recently shown that this cytokine localizes to the cytoplasm of A. actinomycetemcomitans in co-cultures with organotypic gingival mucosa. However, current knowledge about the mechanism underlying bacterial IL-1β sensing is still limited. In this study, we characterized the interaction of A. actinomycetemcomitans total membrane protein with IL-1β through electrophoretic mobility shift assays. The interacting protein, which we have designated bacterial interleukin receptor I (BilRI), was identified through mass spectrometry and was found to be Pasteurellaceae specific. Based on the results obtained using protein function prediction tools, this protein localizes to the outer membrane and contains a typical lipoprotein signal sequence. All six tested biofilm cultures of clinical A. actinomycetemcomitans strains expressed the protein according to phage display-derived antibody detection. Moreover, proteinase K treatment of whole A. actinomycetemcomitans cells eliminated BilRI forms that were outer membrane specific, as determined through immunoblotting. The protein was overexpressed in Escherichia coli in both the outer membrane-associated form and a soluble cytoplasmic form. When assessed using flow cytometry, the BilRI-overexpressing E. coli cells were observed to bind 2.5 times more biotinylated-IL-1β than the control cells, as detected with avidin-FITC. Overexpression of BilRI did not cause binding of a biotinylated negative control protein. In a microplate assay, soluble BilRI bound to IL-1β, but this binding was not specific, as a control protein for IL-1

  1. A Cytolethal Distending Toxin Variant from Aggregatibacter actinomycetemcomitans with an Aberrant CdtB That Lacks the Conserved Catalytic Histidine 160

    PubMed Central

    Obradović, Davor; Gašperšič, Rok; Caserman, Simon; Leonardi, Adrijana; Jamnik, Maja; Podlesek, Zdravko; Seme, Katja; Anderluh, Gregor; Križaj, Igor; Maček, Peter; Butala, Matej

    2016-01-01

    The periodontopathogen Aggregatibacter actinomycetemcomitans synthesizes several virulence factors, including cytolethal distending toxin (CDT). The active CDT holoenzyme is an AB-type tripartite genotoxin that affects eukaryotic cells. Subunits CdtA and CdtC (B-components) allow binding and intracellular translocation of the active CdtB (A-component), which elicits nuclear DNA damage. Different strains of A. actinomycetemcomitans have diverse virulence genotypes, which results in varied pathogenic potential and disease progression. Here, we identified an A. actinomycetemcomitans strain isolated from two patients with advance chronic periodontitis that has a regular cdtABC operon, which, however, codes for a unique, shorter, variant of the CdtB subunit. We describe the characteristics of this CdtBΔ116–188, which lacks the intact nuclear localisation signal and the catalytic histidine 160. We show that the A. actinomycetemcomitans DO15 isolate secretes CdtBΔ116–188, and that this subunit cannot form a holotoxin and is also not genotoxic if expressed ectopically in HeLa cells. Furthermore, the A. actinomycetemcomitans DO15 isolate is not toxic, nor does it induce cellular distention upon infection of co-cultivated HeLa cells. Biological significance of this deletion in the cdtB remains to be explained. PMID:27414641

  2. Comparative genomic hybridization and transcriptome analysis with a pan-genome microarray reveal distinctions between JP2 and non-JP2 genotypes of Aggregatibacter actinomycetemcomitans.

    PubMed

    Huang, Y; Kittichotirat, W; Mayer, M P A; Hall, R; Bumgarner, R; Chen, C

    2013-02-01

    It was postulated that the highly virulent JP2 genotype of Aggregatibacter actinomycetemcomitans may possess a constellation of distinct virulence determinants not found in non-JP2 genotypes. This study compared the genome content and the transcriptome of the serotype b JP2 genotype and the closely related serotype b non-JP2 genotype of A. actinomycetemcomitans. A custom-designed pan-genomic microarray of A. actinomycetemcomitans was constructed and validated against a panel of 11 sequenced reference strains. The microarray was subsequently used for comparative genomic hybridization of serotype b strains of JP2 (six strains) and non-JP2 (six strains) genotypes, and for transcriptome analysis of strains of JP2 (three strains) and non-JP2 (two strains). Two JP2-specific and two non-JP2-specific genomic islands were identified. In one instance, distinct genomic islands were found to be inserted into the same locus among strains of different genotypes. Transcriptome analysis identified five operons, including the leukotoxin operon, to have at least two genes with an expression ratio of 2 or greater between genotypes. Two of the differentially expressed operons were members of the membrane-bound nitrate reductase system (nap operon) and the Tol-Pal system of gram-negative bacterial species. This study is the first to demonstrate the differences in the full genome content and gene expression between A. actinomycetemcomitans strains of JP2 and non-JP2 genotypes. The information is essential for designing hypothesis-driven experiments to examine the pathogenic mechanisms of A. actinomycetemcomitans.

  3. Distribution of protein D, an immunoglobulin D-binding protein, in Haemophilus strains.

    PubMed Central

    Akkoyunlu, M; Ruan, M; Forsgren, A

    1991-01-01

    Protein D, a novel surface protein of the bacterial species Haemophilus influenzae with specific affinity for human immunoglobulin (Ig) D was detected in all 127 H. influenzae strains studied. All strains representing different serotypes of encapsulated strains and different biotypes of nonencapsulated strains bound 125I-labeled IgD to a high degree (38 to 74%). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blot (immunoblot) analysis showed that protein D from all H. influenzae strains had the same apparent molecular weight (i.e., 42,000) and reacted with all three different anti-protein D monoclonal antibodies. By Scatchard analysis, the number of protein D residues on a nontypeable H. influenzae strain was estimated to be approximately 2,800 per organism. The equilibrium constant for the reaction between a human IgD myeloma protein and IgD was found to be 5.8 x 10(8) M-1. Also, all strains of H. haemolyticus and H. aegypticus strains tested bound IgD, 21 to 28% and 41 to 48%, respectively. In extracts of those bacteria, a 42,000-molecular-weight protein reactive with IgD and all three anti-protein D monoclonal antibodies was found. In H. parainfluenzae, H. aphrophilus, H. paraphrophilus, and Actinobacillus actinomycetemcomitans, a 42,000-molecular-weight protein that was reactive with one to three of three anti-protein D monoclonal antibodies but not reactive with human IgD was detected with Western blot analysis. Other Haemophilus species (H. ducreyi, H. parasuis, H. parahaemolyticus, H. segnis, and H. haemoglobinophilus) did not react with human monoclonal IgD or anti-protein D antibodies. On the basis of the wide distribution of protein D among H. influenzae strains, we suggest that protein D could be a vaccine candidate. Images PMID:1900807

  4. Experimental aerosol transmission of Actinobacillus pleuropneumoniae to pigs.

    PubMed Central

    Jobert, J L; Savoye, C; Cariolet, R; Kobisch, M; Madec, F

    2000-01-01

    In order to demonstrate the possible role of aerosol in the transmission of Actinobacillus pleuropneumoniae, an experiment including 18 specific pathogen-free (SPF), 10-week-old piglets, randomly distributed into 2 adjacent units, was carried out. In these facilities, air was forced through absolute filters to prevent any contact with infectious agents. During the first 6 d post inoculation, the 2 units were connected by a rectangular opening and the air circulation was forced by the ventilation system from unit A (inoculated pigs) to unit B (non-inoculated pigs). The A. pleuropneumoniae strain (biovar 1 serovar 9) was isolated in France from an outbreak of porcine pleuropneumonia. Two different infecting doses, 10(7) cfu/animal and 10(8) cfu/animal, were inoculated by intranasal route in 6 pigs of unit A. The infection spread quickly from the inoculated pigs to the non-inoculated pigs. Clinical signs were acute during the 4 d post inoculation: hyperthermia, respiratory distress and, sometimes, death (6 pigs of the unit A and 2 pigs of the unit B). All pigs seroconverted against A. pleuropneumoniae serovar 9 within 2 weeks. Lung lesions were severe: fibrinous pleurisy and lung hemorrhages in the acute stage, pleural adherences and focal pulmonary necrosis in the chronic stage. Actinobacillus pleuropneumoniae was isolated from the tonsils and/or lungs in 16 animals. It could be also isolated from the air of the experimental unit. This study showed that A. pleuropneumoniae was readily transmitted through aerosol over a distance of at least 2.5 m. Images Figure 1. Figure 2. PMID:10680652

  5. Effects of Aggregatibacter actinomycetemcomitans leukotoxin on neutrophil migration and extracellular trap formation

    PubMed Central

    Hirschfeld, Josefine; Roberts, Helen M.; Chapple, Iain L. C.; Parčina, Marijo; Jepsen, Søren; Johansson, Anders; Claesson, Rolf

    2016-01-01

    Background Aggressive periodontitis is associated with the presence of Aggregatibacter actinomycetemcomitans, a leukotoxin (Ltx)-producing periodontal pathogen. Ltx has the ability to lyse white blood cells including neutrophils. Objectives This study was aimed at investigating the interactions between neutrophils and Ltx with regard to the chemotactic properties of Ltx and the release of neutrophil extracellular traps (NETs). Methods Neutrophils from healthy blood donors were isolated and incubated for 30 min and 3 h with increasing concentrations of Ltx (1, 10, and 100 ng/mL) as well as with A. actinomycetemcomitans strains (NCTC 9710 and HK 1651) producing different levels of Ltx. Formation of NETs and cell lysis were assessed by microscopy, fluorescence-based assays, and measurement of released lactate dehydrogenase. Neutrophil migration in response to different Ltx gradients was monitored by real-time video microscopy, and image analysis was performed using ImageJ software. Results Although Ltx (10 and 100 ng/mL) and the leukotoxic A. actinomycetemcomitans strain HK 1651 lysed some neutrophils, other cells were still capable of performing NETosis in a concentration-dependent manner. Low doses of Ltx and the weakly leukotoxic strain NCTC 9710 did not lead to neutrophil lysis, but did induce some NETosis. Furthermore, all three concentrations of Ltx enhanced random neutrophil movement; however, low directional accuracy was observed compared with the positive control (fMLP). Conclusions The results indicate that Ltx acts both as a neutrophil activator and also causes cell death. In addition, Ltx directly induces NETosis in neutrophils prior to cell lysis. In future studies, the underlying pathways involved in Ltx-meditated neutrophil activation and NETosis need to be investigated further. PMID:27834173

  6. Identification of a Novel Bacterial Outer Membrane Interleukin-1Β-Binding Protein from Aggregatibacter actinomycetemcomitans

    PubMed Central

    Paino, Annamari; Ahlstrand, Tuuli; Nuutila, Jari; Navickaite, Indre; Lahti, Maria; Tuominen, Heidi; Välimaa, Hannamari; Lamminmäki, Urpo; Pöllänen, Marja T.; Ihalin, Riikka

    2013-01-01

    Aggregatibacteractinomycetemcomitans is a gram-negative opportunistic oral pathogen. It is frequently associated with subgingival biofilms of both chronic and aggressive periodontitis, and the diseased sites of the periodontium exhibit increased levels of the proinflammatory mediator interleukin (IL)-1β. Some bacterial species can alter their physiological properties as a result of sensing IL-1β. We have recently shown that this cytokine localizes to the cytoplasm of A. actinomycetemcomitans in co-cultures with organotypic gingival mucosa. However, current knowledge about the mechanism underlying bacterial IL-1β sensing is still limited. In this study, we characterized the interaction of A. actinomycetemcomitans total membrane protein with IL-1β through electrophoretic mobility shift assays. The interacting protein, which we have designated bacterial interleukin receptor I (BilRI), was identified through mass spectrometry and was found to be Pasteurellaceae specific. Based on the results obtained using protein function prediction tools, this protein localizes to the outer membrane and contains a typical lipoprotein signal sequence. All six tested biofilm cultures of clinical A. actinomycetemcomitans strains expressed the protein according to phage display-derived antibody detection. Moreover, proteinase K treatment of whole A. actinomycetemcomitans cells eliminated BilRI forms that were outer membrane specific, as determined through immunoblotting. The protein was overexpressed in Escherichia coli in both the outer membrane-associated form and a soluble cytoplasmic form. When assessed using flow cytometry, the BilRI-overexpressing E. coli cells were observed to bind 2.5 times more biotinylated-IL-1β than the control cells, as detected with avidin-FITC. Overexpression of BilRI did not cause binding of a biotinylated negative control protein. In a microplate assay, soluble BilRI bound to IL-1β, but this binding was not specific, as a control protein for IL-1

  7. Aggregatibacter Actinomycetemcomitans – A Tooth Killer?

    PubMed Central

    Ummer, Fajar; Dhivakar, C.P

    2014-01-01

    Strong evidence is available on Aggregatibacter actinomycetemcomitans (A.a) on its role as the causative agent of localised juvenile periodontitis (LJP), a disease characterised by rapid destruction of the tooth-supporting tissues. This organism possesses a large number of virulence factors with a wide range of activities which enable it to colonise the oral cavity, invade periodontal tissues, evade host defences, initiate connective tissue destruction and interfere with tissue repair. Adhesion to epithelial and tooth surfaces is dependent on the presence of surface proteins and structures such as microvesicles and fimbriae. Invasion has been demonstrated in vivo and in vitro. The organism has a number of means of evading host defences which include: (i) production of leukotoxin; (ii) producing immunosuppressive factors; (iv) secreting proteases capable of cleaving IgG; and (v) producing Fc-binding. PMID:25302290

  8. Characterization of Actinobacillus pleuropneumoniae riboflavin biosynthesis genes.

    PubMed Central

    Fuller, T E; Mulks, M H

    1995-01-01

    In this paper, we report the identification, cloning, and complete nucleotide sequence of four genes from Actinobacillus pleuropneumoniae that are involved in riboflavin biosynthesis. The cloned genes can specify production of large amounts of riboflavin in Escherichia coli, can complement several defined genetic mutations in riboflavin biosynthesis in E. coli, and are homologous to riboflavin biosynthetic genes from E. coli, Haemophilus influenzae, and Bacillus subtilis. The genes have been designated A. pleuropneumoniae ribGBAH because of their similarity in both sequence and arrangement to the B. subtilis ribGBAH operon. PMID:8522537

  9. Profound Effects of Aggregatibacter actinomycetemcomitans Leukotoxin Mutation on Adherence Properties Are Clarified in in vitro Experiments.

    PubMed

    Velusamy, Senthil Kumar; Sampathkumar, Vandana; Godboley, Dipti; Fine, Daniel H

    2016-01-01

    Leukotoxin (Ltx) is a prominent virulence factor produced by Aggregatibacter actinomycetemcomitans, an oral microorganism highly associated with aggressive periodontitis. Ltx compromises host responsiveness by altering the viability of neutrophils, lymphocytes, and macrophages. Previously, we developed a Rhesus (Rh) monkey colonization model designed to determine the effect of virulence gene mutations on colonization of A. actinomycetemcomitans. Unexpectedly, an A. actinomycetemcomitans leukotoxin (ltxA) mutant (RhAa-VS2) failed to colonize in the Rh model. No previous literature suggested that Ltx was associated with A. actinomycetemcomitans binding to tooth surfaces. These results led us to explore the broad effects of the ltxA mutation in vitro. Results indicated that LtxA activity was completely abolished in RhAa-VS2 strain, while complementation significantly (P<0.0001) restored leukotoxicity compared to RhAa-VS2 strain. RT-PCR analysis of ltx gene expression ruled out polar effects. Furthermore, binding of RhAa-VS2 to salivary-coated hydroxyapatite (SHA) was significantly decreased (P<0.0001) compared to wild type RhAa3 strain. Real time RT-PCR analysis of the genes related to SHA binding in RhAa-VS2 showed that genes related to binding were downregulated [rcpA (P = 0.018), rcpB (P = 0.02), tadA (P = 0.002)] as compared to wild type RhAa3. RhAa-VS2 also exhibited decreased biofilm depth (P = 0.008) and exo-polysaccharide production (P<0.0001). Buccal epithelial cell (BEC) binding of RhAa-VS2 was unaffected. Complementation with ltxA restored binding to SHA (P<0.002) but had no effect on biofilm formation when compared to RhAa3. In conclusion, mutation of ltxA diminished hard tissue binding in vitro, which helps explain the previous in vivo failure of a ltxA knockout to colonize the Rh oral cavity. These results suggest that; 1) one specific gene knockout (in this case ltxA) could affect other seemingly unrelated genes (such as rcpA, rcpB tadA etc), and 2

  10. Profound Effects of Aggregatibacter actinomycetemcomitans Leukotoxin Mutation on Adherence Properties Are Clarified in in vitro Experiments

    PubMed Central

    Godboley, Dipti; Fine, Daniel H.

    2016-01-01

    Leukotoxin (Ltx) is a prominent virulence factor produced by Aggregatibacter actinomycetemcomitans, an oral microorganism highly associated with aggressive periodontitis. Ltx compromises host responsiveness by altering the viability of neutrophils, lymphocytes, and macrophages. Previously, we developed a Rhesus (Rh) monkey colonization model designed to determine the effect of virulence gene mutations on colonization of A. actinomycetemcomitans. Unexpectedly, an A. actinomycetemcomitans leukotoxin (ltxA) mutant (RhAa-VS2) failed to colonize in the Rh model. No previous literature suggested that Ltx was associated with A. actinomycetemcomitans binding to tooth surfaces. These results led us to explore the broad effects of the ltxA mutation in vitro. Results indicated that LtxA activity was completely abolished in RhAa-VS2 strain, while complementation significantly (P<0.0001) restored leukotoxicity compared to RhAa-VS2 strain. RT-PCR analysis of ltx gene expression ruled out polar effects. Furthermore, binding of RhAa-VS2 to salivary-coated hydroxyapatite (SHA) was significantly decreased (P<0.0001) compared to wild type RhAa3 strain. Real time RT-PCR analysis of the genes related to SHA binding in RhAa-VS2 showed that genes related to binding were downregulated [rcpA (P = 0.018), rcpB (P = 0.02), tadA (P = 0.002)] as compared to wild type RhAa3. RhAa-VS2 also exhibited decreased biofilm depth (P = 0.008) and exo-polysaccharide production (P<0.0001). Buccal epithelial cell (BEC) binding of RhAa-VS2 was unaffected. Complementation with ltxA restored binding to SHA (P<0.002) but had no effect on biofilm formation when compared to RhAa3. In conclusion, mutation of ltxA diminished hard tissue binding in vitro, which helps explain the previous in vivo failure of a ltxA knockout to colonize the Rh oral cavity. These results suggest that; 1) one specific gene knockout (in this case ltxA) could affect other seemingly unrelated genes (such as rcpA, rcpB tadA etc), and 2

  11. Changes in antimicrobial susceptibility of Actinobacillus pleuropneumoniae isolated from pigs in Spain during the last decade.

    PubMed

    Gutiérrez-Martín, César B; del Blanco, Noemí García; Blanco, Mónica; Navas, Jesús; Rodríguez-Ferri, Elías F

    2006-06-15

    A total of 229 Spanish Actinobacillus pleuropneumoniae isolates recovered from diseased pigs with pleuropneumonia from 1997 to 2004 was tested for their susceptibility to 11 antimicrobials in a broth microdilution method. All the isolates were susceptible to florfenicol and most of them to cephalothin; however, a high rate of resistance was observed to tetracycline. A bimodal or multimodal distribution of isolates over the MIC range were observed for penicillins, tetracycline, trimethoprim, sulfisoxazole and nalidixic acid, suggesting the development of acquired resistance. Eight resistance patterns were established, and 21.1% of the isolates were resistant to at least two antimicrobials. In addition, a considerable increase in the resistance to tetracyclines was observed during the last decade in Spain, when compared with other A. pleuropneumoniae strains isolated during 1987-1988 (Gutiérrez, C.B., Píriz, S., Vadillo, S., Rodríguez Ferri, E.F., 1993. In vitro susceptibility of Actinobacillus pleuropneumoniae strains to 42 antimicrobial agents. Am. J. Vet. Res. 54, 546-550); this finding was also observed for gentamicin in minor percentage.

  12. Transposon mutagenesis in Actinobacillus pleuropneumoniae with a Tn10 derivative.

    PubMed Central

    Tascon, R I; Rodriguez-Ferri, E F; Gutierrez-Martin, C B; Rodriguez-Barbosa, I; Berche, P; Vazquez-Boland, J A

    1993-01-01

    A transposon mutagenesis procedure functional in the gram-negative swine pathogen Actinobacillus pleuropneumoniae was developed for the first time. The technique involved the use of a suicide conjugative plasmid, pLOF/Km, carrying a mini-Tn10 with an isopropyl-beta-D-thiogalactopyranoside (IPTG)-inducible transposase located outside the mobile element (M. Herrero, V. de Lorenzo, and K. N. Timmis, J. Bacteriol. 172:6557-6567, 1990). The plasmid was mobilized from Escherichia coli to A. pleuropneumoniae through the RP4-mediated broad-host-range conjugal transfer functions provided by the chromosome of the donor strain. When IPTG was present in the mating medium, A. pleuropneumoniae CM5 transposon mutants were obtained at a frequency of 10(-5), while no mutants were detected in the absence of IPTG. Since the frequency of conjugal transfer of the RP4 plasmid from E. coli to A. pleuropneumoniae CM5 was found to be as low as 10(-4), the above result indicated that the expression level of the transposase was a critical factor for obtaining a workable efficiency of transposon mutagenesis. The transposon insertions occurred at random, as determined by Southern blotting of chromosomal DNA of randomly selected mutants and by the ability to generate mutants defective for the selected phenotypes. Almost all the mutants analyzed resulted from a single insertion of the Tn10 element. About 1.2% of the mutants resulted from the cointegration of pLOF/Km into the A. pleuropneumoniae chromosome. The applicability of this transposon mutagenesis system was verified on other A. pleuropneumoniae strains of different serotypes. The usefulness of this transposon mutagenesis system in genetic studies of A. pleuropneumoniae is discussed. Images PMID:8396122

  13. [Environmental factors affecting the succinic acid production by Actinobacillus succinogenes CGMCC 1593].

    PubMed

    Zheng, Pu; Zhou, Wei; Ni, Ye; Jiang, Min; Wei, Ping; Sun, Zhihao

    2008-06-01

    Actinobacillus succinogenes is a promising candidate for the production of bio-based succinic acid. Previously, we isolated a succinic acid-producing strain Actinobacillus succinogenes CGMCC 1593 from bovine rumen. In this paper, the influence of the environmental factors such as gas phase, pH, ORP, on succinic acid production by A. succinogenes CGMCC 1593 was studied. The results showed that CO2 was the optimum gas phase for anaerobic fermentation ofA. succinogenes CGMCC 1593 as well as one of the substrate for the succinic acid synthesis. Using MgCO3 as a pH regulator, the pH was maintained within 7.1-6.2 during the anaerobic fermentation for the cell growth and acid production of A. succinogenes CGMCC 1593. Our results showed that low initial ORP was disadvantageous for the growth of A. succinogenes CGMCC 1593 and an ORP of -270 mV was demonstrated to be beneficial to the succinic acid production. By adding Na2S.9H2O to decrease ORP to -270 mV at the end of exponential growth phase in batch culture of A. succinogenes CGMCC 1593, the succinic acid concentration reached 37 g/L and the yield of succinic acid was 129% at 48 h. This work might provide valuable information for further optimization of succinic acid fermentation by A. succinogenes CGMCC 1593.

  14. Optimization of succinic acid fermentation with Actinobacillus succinogenes by response surface methodology (RSM).

    PubMed

    Zhang, Yun-jian; Li, Qiang; Zhang, Yu-xiu; Wang, Dan; Xing, Jian-min

    2012-02-01

    Succinic acid is considered as an important platform chemical. Succinic acid fermentation with Actinobacillus succinogenes strain BE-1 was optimized by central composite design (CCD) using a response surface methodology (RSM). The optimized production of succinic acid was predicted and the interactive effects between glucose, yeast extract, and magnesium carbonate were investigated. As a result, a model for predicting the concentration of succinic acid production was developed. The accuracy of the model was confirmed by the analysis of variance (ANOVA), and the validity was further proved by verification experiments showing that percentage errors between actual and predicted values varied from 3.02% to 6.38%. In addition, it was observed that the interactive effect between yeast extract and magnesium carbonate was statistically significant. In conclusion, RSM is an effective and useful method for optimizing the medium components and investigating the interactive effects, and can provide valuable information for succinic acid scale-up fermentation using A. succinogenes strain BE-1.

  15. Nucleotide sequence of the hemolysin I gene from Actinobacillus pleuropneumoniae.

    PubMed Central

    Frey, J; Meier, R; Gygi, D; Nicolet, J

    1991-01-01

    The DNA sequence of the gene encoding the structural protein of hemolysin I (HlyI) of Actinobacillus pleuropneumoniae serotype 1 strain 4074 was analyzed. The nucleotide sequence shows a 3,072-bp reading frame encoding a protein of 1,023 amino acids with a calculated molecular size of 110.1 kDa. This corresponds to the HlyI protein, which has an apparent molecular size on sodium dodecyl sulfate gels of 105 kDa. The structure of the protein derived from the DNA sequence shows three hydrophobic regions in the N-terminal part of the protein, 13 glycine-rich domains in the second half of the protein, and a hydrophilic C-terminal area, all of which are typical of the cytotoxins of the RTX (repeats in the structural toxin) toxin family. The derived amino acid sequence of HlyI shows 42% homology with the hemolysin of A. pleuropneumoniae serotype 5, 41% homology with the leukotoxin of Pasteurella haemolytica, and 56% homology with the Escherichia coli alpha-hemolysin. The 13 glycine-rich repeats and three hydrophobic areas of the HlyI sequence show more similarity to the E. coli alpha-hemolysin than to either the A. pleuropneumoniae serotype 5 hemolysin or the leukotoxin (while the last two are more similar to each other). Two types of RTX hemolysins therefore seem to be present in A. pleuropneumoniae, one (HlyI) resembling the alpha-hemolysin and a second more closely related to the leukotoxin. Ca(2+)-binding experiments using HlyI and recombinant A. pleuropneumoniae prohemolysin (HlyIA) that was produced in E. coli shows that HlyI binds 45Ca2+, probably because of the 13 glycine-rich repeated domains. Activation of the prohemolysin is not required for Ca2+ binding. Images PMID:1879928

  16. Inner-membrane protein MorC is involved in fimbriae production and biofilm formation in Aggregatibacter actinomycetemcomitans.

    PubMed

    Smith, Kenneth P; Ruiz, Teresa; Mintz, Keith P

    2016-03-01

    Fimbrial subunit synthesis, secretion and assembly on the surface of the periodontal pathogen Aggregatibacter actinomycetemcomitans are essential for biofilm formation. A recent quantitative proteomics study employing an afimbriated strain and a developed mutant isogenic for the inner-membrane protein morphogenesis protein C (MorC) revealed that the abundance of the proteins of the fimbrial secretion apparatus in the membrane is dependent on MorC. To investigate further the relationship between MorC and fimbriation, we identified and complemented the defect in fimbriae production in the afimbriated laboratory strain. The transformed strain expressing a plasmid containing genes encoding the WT fimbrial subunit and the prepilin peptidase displayed all of the hallmarks of a fimbriated bacterium including the distinct star-like colony morphology, robust biofilm formation, biofilm architecture composed of discrete microcolonies and the presence of fimbriae. When the identical plasmid was transformed into a morC mutant strain, the bacterium did not display any of the phenotypes of fimbriated strains. Extension of these studies to a naturally fimbriated clinical strain showed that the resulting morC mutant maintained the characteristic colony morphology of fimbriated strains. There was, however, a reduction in the secretion of fimbrial subunits, and fewer fimbriae were observed on the surface of the mutant strain. Furthermore, the morC mutant of the fimbriated strain displayed a significantly altered biofilm microcolony architecture, while maintaining a similar biofilm mass to the parent strain. These results suggest that MorC influences fimbrial secretion and microcolony formation in A. actinomycetemcomitans.

  17. Aggregatibacter actinomycetemcomitans Invasion Induces Interleukin-1β Production Through Reactive Oxygen Species and Cathepsin B.

    PubMed

    Okinaga, Toshinori; Ariyoshi, Wataru; Nishihara, Tatsuji

    2015-06-01

    Interleukin-1 (IL-1) cytokines, IL-1α, IL-1β, and IL-18 play a crucial role in inflammatory responses in a variety of diseases including periodontitis. In this study, the periodontopathic bacterial pathogen, Aggregatibacter actinomycetemcomitans, induced cell death and cytokine release in macrophages. Cell viability was reduced by A. actinomycetemcomitans invasion using (3-[4, 5-dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide assay. The production of IL-1β in A. actinomycetemcomitans-invaded macrophage cells was detected by real-time reverse transcriptase-polymerase chain reaction, western blotting, and enzyme-linked immunosorbent assay. Treatment with a caspase-1 inhibitor and silencing of the caspase-1 gene had no effect on IL-1β secretion induced by A. actinomycetemcomitans invasion. Pattern recognition receptor, NLRP3 was upregulated in A. actinomycetemcomitans-invaded macrophages. However, NLRP3 knockdown had no effect on the secretion of IL-1β in A. actinomycetemcomitans-invaded RAW 264 cells. In addition, A. actinomycetemcomitans invasion induced the generation of reactive oxygen species (ROS) and the release of cathepsin B in RAW 264 cells. Interestingly, CA074-Me, a cathepsin B inhibitor, and N-Acetyl-l-cysteine, a ROS inhibitor, prevented the production of IL-1β induced by A. actinomycetemcomitans. Taken together, these results suggest A. actinomycetemcomitans induce IL-1β production in RAW 264 cells through the production of ROS and cathepsin B, but not through the NLRP3/caspase-1 pathway.

  18. Aggregatibacter actinomycetemcomitans infection mimicking lung cancer: a case report.

    PubMed

    Matzumura-Kuan, Melissa; Jennings, Jeffrey

    2014-09-01

    Pulmonary infections can mimic a pulmonary neoplasm. Multiple organisms, including bacteria, viruses, and fungi, can present with similar clinical, radiographic, and surgical findings as neoplastic processes. Because treatment and the prognosis are completely different, an accurate diagnosis is crucial, and lung biopsy is usually required. Aggregatibacter actinomycetemcomitans is part of the normal oral flora and is a rare cause of invasive infection due to hematogenous dissemination or aspiration, particularly infective endocarditis. We present a case of A. actinomycetemcomitans and Actinomyces co-infection that presented as a mediastinal mass, with surgical findings similar to lung malignancy but with biopsy and culture showing an infectious origin. After antibiotic treatment, follow-up images showed resolution of the mass.

  19. Stability of the JP2 clone of Aggregatibacter actinomycetemcomitans.

    PubMed

    Haubek, D; Ennibi, O-K; Vaeth, M; Poulsen, S; Poulsen, K

    2009-09-01

    The JP2 clone of Aggregatibacter actinomycetemcomitans is strongly associated with aggressive periodontitis. To obtain information about colonization dynamics of the JP2 clone, we used PCR to examine its presence in 365 Moroccan juveniles from whom periodontal plaque samples were collected at baseline and after one and two years. Periodontal attachment loss was measured at baseline and at the two-year follow-up. At baseline, 43 (12%) carriers of the JP2 clone were found. Nearly half (44 %) of these were persistently colonized with the clone. The relative risk for the development of aggressive periodontitis, adjusted for the concomitant presence of other genotypes of A. actinomycetemcomitans, was highest for individuals continuously infected by the JP2 clone (RR = 13.9; 95% CI, 9.0 to 21.4), indicating a relationship between infectious dose and disease, which further substantiates the evidence for the JP2 clone as a causal factor in aggressive periodontitis.

  20. Leukotoxic activity of Aggregatibacter actinomycetemcomitans and periodontal attachment loss.

    PubMed

    Höglund Åberg, Carola; Haubek, Dorte; Kwamin, Francis; Johansson, Anders; Claesson, Rolf

    2014-01-01

    Aggregatibacter actinomycetemcomitans is a Gram-negative periodontitis-associated bacterium that expresses a toxin that selectively affects leukocytes. This leukotoxin is encoded by an operon belonging to the core genome of this bacterial species. Variations in the expression of the leukotoxin have been reported, and a well-characterized specific clonal type (JP2) of this bacterium with enhanced leukotoxin expression has been isolated. In particular, the presence of the JP2 genotype significantly increases the risk for the progression of periodontal attachment loss (AL). Based on these findings we hypothesized that variations in the leukotoxicity are linked to disease progression in infected individuals. In the present study, the leukotoxicity of 239 clinical isolates of A. actinomycetemcomitans was analysed with different bioassays, and the genetic peculiarities of the isolates were related to their leukotoxicity based on examination with molecular techniques. The periodontal status of the individuals sampled for the presence of A. actinomycetemcomitans was examined longitudinally, and the importance of the observed variations in leukotoxicity was evaluated in relation to disease progression. Our data show that high leukotoxicity correlates with an enhanced risk for the progression of AL. The JP2 genotype isolates were all highly leukotoxic, while the isolates with an intact leukotoxin promoter (non-JP2 genotypes) showed substantial variation in leukotoxicity. Genetic characterization of the non-JP2 genotype isolates indicated the presence of highly leukotoxic genotypes of serotype b with similarities to the JP2 genotype. Based on these results, we conclude that A. actinomycetemcomitans harbours other highly virulent genotypes besides the previously described JP2 genotype. In addition, the results from the present study further highlight the importance of the leukotoxin as a key virulence factor in aggressive forms of periodontitis.

  1. Differential transcriptional regulation of Aggregatibacter actinomycetemcomitans lsrACDBFG and lsrRK operons by integration host factor protein.

    PubMed

    Torres-Escobar, Ascención; Juárez-Rodríguez, María Dolores; Demuth, Donald R

    2014-04-01

    We previously showed that the Aggregatibacter actinomycetemcomitans lsrACDBFG and lsrRK operons are regulated by LsrR and cyclic AMP receptor protein (CRP) and that proper regulation of the lsr locus is required for optimal biofilm growth by A. actinomycetemcomitans. Here, we identified sequences that reside immediately upstream from both the lsrA and lsrR start codons that closely resemble the consensus recognition sequence of Escherichia coli integration host factor (IHF) protein. A. actinomycetemcomitans IHFα and IHFβ were expressed and purified as hexahistidine fusion proteins, and using electrophoretic mobility shift assays (EMSAs), the IHFα-IHFβ protein complex was shown to bind to probes containing the putative IHF recognition sequences. In addition, single-copy chromosomal insertions of lsrR promoter-lacZ and lsrA promoter-lacZ transcriptional fusions in wild-type A. actinomycetemcomitans and ΔihfA and ΔihfB mutant strains showed that IHF differentially regulates the lsr locus and functions as a negative regulator of lsrRK and a positive regulator of lsrACDBFG. Deletion of ihfA or ihfB also reduced biofilm formation and altered biofilm architecture relative to the wild-type strain, and these phenotypes were partially complemented by a plasmid-borne copy of ihfA or ihfB. Finally, using 5' rapid amplification of cDNA ends (RACE), two transcriptional start sites (TSSs) and two putative promoters were identified for lsrRK and three TSSs and putative promoters were identified for lsrACDBFG. The function of the two lsrRK promoters and the positive regulatory role of IHF in regulating lsrACDBFG expression were confirmed with a series of lacZ transcriptional fusion constructs. Together, our results highlight the complex transcriptional regulation of the lsrACDBFG and lsrRK operons and suggest that multiple promoters and the architecture of the lsrACDBFG-lsrRK intergenic region may control the expression of these operons.

  2. Porphyromonas gingivalis gingipain is involved in the detachment and aggregation of Aggregatibacter actinomycetemcomitans biofilm.

    PubMed

    Haraguchi, A; Miura, M; Fujise, O; Hamachi, T; Nishimura, F

    2014-06-01

    Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans are major periodontal pathogens that cause several types of periodontal disease. Our previous study suggested that P. gingivalis gingipains secreted in the subgingival environment are related to the detachment of A.actinomycetemcomitans biofilms. However, it remains unclear whether arginine-specific cysteine proteinase (Rgp) and lysine-specific proteinase (Kgp) play different roles in the detachment of A. actinomycetemcomitans biofilm. The aim of this study was to investigate possible disruptive roles of Kgp and Rgp in the aggregation and attachment of A. actinomycetemcomitans. While P. gingivalis ATCC33277 culture supernatant has an ability to decrease autoaggregation and coaggregation of A. actinomycetemcomitans cells, neither the boiled culture supernatant of ATCC33277 nor the culture supernatant of KDP136 showed this ability. The addition of KYT-1 and KYT-36, specific inhibitors of Rgp and Kgp, respectively, showed no influence on the ability of P. gingivalis culture supernatant. The result of gelatin zymography suggested that other proteases processed by gingipains mediated the decrease of A. actinomycetemcomitans aggregations. We also examined the biofilm-destructive effect of gingipains by assessing the detachment of A. actinomycetemcomitans from polystyrene surfaces. Scanning electron microscope analysis indicated that A. actinomycetemcomitans cells were detached by P. gingivalis Kgp. The quantity of A. actinomycetemcomitans in biofilm was decreased in co-culture with P. gingivalis. However, this was not found after the addition of KYT-36. These findings suggest that Kgp is a critical component for the detachment and decrease of A. actinomycetemcomitans biofilms.

  3. In vitro efficacy of diallyl sulfides against the periodontopathogen Aggregatibacter actinomycetemcomitans.

    PubMed

    Velliyagounder, Kabilan; Ganeshnarayan, Krishnaraj; Velusamy, Senthil Kumar; Fine, Daniel H

    2012-05-01

    The in vitro antibacterial effects of diallyl sulfide (DAS) against the Gram-negative periodontopathogen Aggregatibacter actinomycetemcomitans, the key etiologic agent of the severe form of localized aggressive periodontitis and other nonoral infections, were studied. A. actinomycetemcomitans was treated with garlic extract, allicin, or DAS, and the anti-A. actinomycetemcomitans effects of the treatment were evaluated. Garlic extract, allicin, and DAS significantly inhibited the growth of A. actinomycetemcomitans (greater than 3 log; P < 0.01) compared to control cells. Heat inactivation of the garlic extracts significantly reduced the protein concentration; however, the antimicrobial effect was retained. Purified proteins from garlic extract did not exhibit antimicrobial activity. Allicin lost all its antimicrobial effect when it was subjected to heat treatment, whereas DAS demonstrated an antimicrobial effect similar to that of the garlic extract, suggesting that the antimicrobial activity of garlic extract is mainly due to DAS. An A. actinomycetemcomitans biofilm-killing assay performed with DAS showed a significant reduction in biofilm cell numbers, as evidenced by both confocal microscopy and culture. Scanning electron microscopy (SEM) analysis of DAS-treated A. actinomycetemcomitans biofilms showed alterations of colony architecture indicating severe stress. Flow cytometry analysis of OBA9 cells did not demonstrate apoptosis or cell cycle arrest at therapeutic concentrations of DAS (0.01 and 0.1 μg/ml). DAS-treated A. actinomycetemcomitans cells demonstrated complete inhibition of glutathione (GSH) S-transferase (GST) activity. However, OBA9 cells, when exposed to DAS at similar concentrations, showed no significant differences in GST activity, suggesting that DAS-induced GST inhibition might be involved in A. actinomycetemcomitans cell death. These findings demonstrate that DAS exhibits significant antibacterial activity against A. actinomycetemcomitans and

  4. In Vitro Efficacy of Diallyl Sulfides against the Periodontopathogen Aggregatibacter actinomycetemcomitans

    PubMed Central

    Ganeshnarayan, Krishnaraj; Velusamy, Senthil Kumar; Fine, Daniel H.

    2012-01-01

    The in vitro antibacterial effects of diallyl sulfide (DAS) against the Gram-negative periodontopathogen Aggregatibacter actinomycetemcomitans, the key etiologic agent of the severe form of localized aggressive periodontitis and other nonoral infections, were studied. A. actinomycetemcomitans was treated with garlic extract, allicin, or DAS, and the anti-A. actinomycetemcomitans effects of the treatment were evaluated. Garlic extract, allicin, and DAS significantly inhibited the growth of A. actinomycetemcomitans (greater than 3 log; P < 0.01) compared to control cells. Heat inactivation of the garlic extracts significantly reduced the protein concentration; however, the antimicrobial effect was retained. Purified proteins from garlic extract did not exhibit antimicrobial activity. Allicin lost all its antimicrobial effect when it was subjected to heat treatment, whereas DAS demonstrated an antimicrobial effect similar to that of the garlic extract, suggesting that the antimicrobial activity of garlic extract is mainly due to DAS. An A. actinomycetemcomitans biofilm-killing assay performed with DAS showed a significant reduction in biofilm cell numbers, as evidenced by both confocal microscopy and culture. Scanning electron microscopy (SEM) analysis of DAS-treated A. actinomycetemcomitans biofilms showed alterations of colony architecture indicating severe stress. Flow cytometry analysis of OBA9 cells did not demonstrate apoptosis or cell cycle arrest at therapeutic concentrations of DAS (0.01 and 0.1 μg/ml). DAS-treated A. actinomycetemcomitans cells demonstrated complete inhibition of glutathione (GSH) S-transferase (GST) activity. However, OBA9 cells, when exposed to DAS at similar concentrations, showed no significant differences in GST activity, suggesting that DAS-induced GST inhibition might be involved in A. actinomycetemcomitans cell death. These findings demonstrate that DAS exhibits significant antibacterial activity against A. actinomycetemcomitans and

  5. Actinobacillus rossii sp. nov., Actinobacillus seminis sp. nov., nom. rev., Pasteurella bettii sp. nov., Pasteurella lymphangitidis sp. nov., Pasteurella mairi sp. nov., and Pasteurella trehalosi sp. nov.

    PubMed

    Sneath, P H; Stevens, M

    1990-04-01

    Evidence from numerical taxonomic analysis and DNA-DNA hybridization supports the proposal of new species in the genera Actinobacillus and Pasteurella. The following new species are proposed: Actinobacillus rossii sp. nov., from the vaginas of postparturient sows; Actinobacillus seminis sp. nov., nom. rev., associated with epididymitis of sheep; Pasteurella bettii sp. nov., associated with human Bartholin gland abscess and finger infections; Pasteurella lymphangitidis sp. nov. (the BLG group), which causes bovine lymphangitis; Pasteurella mairi sp. nov., which causes abortion in sows; and Pasteurella trehalosi sp. nov., formerly biovar T of Pasteurella haemolytica, which causes septicemia in older lambs.

  6. A Unique Capsule Locus in the Newly Designated Actinobacillus pleuropneumoniae Serovar 16 and Development of a Diagnostic PCR Assay

    PubMed Central

    Li, Yanwen; Sárközi, Rita; Gottschalk, Marcelo; Angen, Øystein; Nedbalcova, Katerina; Rycroft, Andrew N.; Fodor, László

    2017-01-01

    ABSTRACT Actinobacillus pleuropneumoniae causes pleuropneumonia, an economically significant lung disease of pigs. Recently, isolates of A. pleuropneumoniae that were serologically distinct from the previously characterized 15 serovars were described, and a proposal was put forward that they comprised a new serovar, serovar 16. Here we used whole-genome sequencing of the proposed serovar 16 reference strain A-85/14 to confirm the presence of a unique capsular polysaccharide biosynthetic locus. For molecular diagnostics, primers were designed from the capsule locus of strain A-85/14, and a PCR was formulated that differentiated serovar 16 isolates from all 15 known serovars and other common respiratory pathogenic/commensal bacteria of pigs. Analysis of the capsule locus of strain A-85/14 combined with the previous serological data show the existence of a sixteenth serovar—designated serovar 16—of A. pleuropneumoniae. PMID:28053219

  7. A Unique Capsule Locus in the Newly Designated Actinobacillus pleuropneumoniae Serovar 16 and Development of a Diagnostic PCR Assay.

    PubMed

    Bossé, Janine T; Li, Yanwen; Sárközi, Rita; Gottschalk, Marcelo; Angen, Øystein; Nedbalcova, Katerina; Rycroft, Andrew N; Fodor, László; Langford, Paul R

    2017-03-01

    Actinobacillus pleuropneumoniae causes pleuropneumonia, an economically significant lung disease of pigs. Recently, isolates of A. pleuropneumoniae that were serologically distinct from the previously characterized 15 serovars were described, and a proposal was put forward that they comprised a new serovar, serovar 16. Here we used whole-genome sequencing of the proposed serovar 16 reference strain A-85/14 to confirm the presence of a unique capsular polysaccharide biosynthetic locus. For molecular diagnostics, primers were designed from the capsule locus of strain A-85/14, and a PCR was formulated that differentiated serovar 16 isolates from all 15 known serovars and other common respiratory pathogenic/commensal bacteria of pigs. Analysis of the capsule locus of strain A-85/14 combined with the previous serological data show the existence of a sixteenth serovar-designated serovar 16-of A. pleuropneumoniae.

  8. Interleukin-1-like activity in capsular material from Haemophilus actinomycetemcomitans.

    PubMed Central

    Harvey, W; Kamin, S; Meghji, S; Wilson, M

    1987-01-01

    This paper describes the activity of a bacterial surface component (capsular material, CM) in biological assays for interleukin-1 (IL-1). CM from the periodontal pathogen Haemophilus actinomycetemcomitans was tested in the following in vitro assays: mouse thymocyte proliferation (LAF assay), stimulation of collagenase and prostaglandin (PG) E2 synthesis by articular chondrocytes, and stimulation of PGE2 synthesis by fibroblasts. In all these assays, CM gave a response similar to an IL-1 preparation. This ability to mimic IL-1 suggests an important role for CM in both cell-mediated immunity and connective tissue destruction in localized juvenile periodontitis (LJP). PMID:3032779

  9. Genetic Diversity of Actinobacillus pleuropneumoniae Assessed by Amplified Fragment Length Polymorphism Analysis▿

    PubMed Central

    Kokotovic, Branko; Angen, Øystein

    2007-01-01

    Amplified fragment length polymorphism (AFLP) was evaluated as a method for genotypic characterization and subtyping within the bacterial species Actinobacillus pleuropneumoniae. A total of 155 isolates of A. pleuropneumoniae, representing the serotypic variation described to occur within this species, were analyzed. In order to elucidate the species boundaries, six strains of the phylogenetically closely related species Actinobacillus lignieresii were also included. Furthermore, the ability of AFLP to subtype was studied using 42 isolates of serovar 2 and the performance compared to that obtained by pulsed-field gel electrophoresis (PFGE). AFLP analysis provided a clear separation of A. lignieresii and A. pleuropneumoniae and divided the isolates of A. pleuropneumoniae into 20 clusters. Most of the serovars of A. pleuropneumoniae were represented by single and quite homogeneous clusters. The exceptions were serovars 10, K2:O7, and K1:O7, which were represented by two clusters each. In the cases where the serovars were represented by more than one cluster, the existence of these clusters was supported by additional phenotypic or genotypic properties. Furthermore, AFLP typing was able to allocate serologically nontypeable isolates to appropriate genetic groups within the species. Further investigations are needed to determine whether some of the clusters revealed through AFLP analysis represent additional serovars. When evaluated as a method for subtyping within serovar 2 of A. pleuropneumoniae, AFLP was found to achieve a degree of separation among isolates superior to that obtained by PFGE. However, a higher degree of separation between serovar 2 isolates was obtained by a combination of the two methods. PMID:17959758

  10. Morphological, biochemical, antigenic, and cytochemical relationships among Haemophilus somnus, Haemophilus agni, Haemophilus haemoglobinophilus, Histophilus ovis, and Actinobacillus seminis.

    PubMed Central

    Stephens, L R; Humphrey, J D; Little, P B; Barnum, D A

    1983-01-01

    Morphology, biochemical reactions, pigmentation, antigens, and cell envelope proteins were examined in 12 strains of Haemophilus somnus, Haemophilus agni, Histophilus ovis, and Actinobacillus seminis. All of the strains except A. seminis are related and are considered as a single Haemophilus-Histophilus (HH) group. In immunodiffusion tests, HH group bacteria had at least two antigens common to all members of the group, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that they have similar cell envelope protein profiles. A quantitatively variable yellow pigment with absorption maxima of 430 to 435 nm was present in strains of H. somnus and H. agni. The HH group did not produce catalase and grew only in air containing 10% CO2. Of 10 HH group bacteria, 9 required thiamine monophosphate for growth. A. seminis was distinguished from the HH group by its lack of yellow pigment, production of catalase, growth in air, lack of a thiamine monophosphate requirement, and different cell envelope protein profile. In gel immunodiffusion tests, A. seminis antigens produced two lines of partial identity with the HH group when antiserum against H. somnus was used. Reference strains of Haemophilus influenzae, Actinobacillus lignieresii, and Haemophilus haemoglobinophilus were compared with the test strains. In immunodiffusion tests, a single antigen was found to be common to H. haemoglobinophilus, A. seminis, and the HH group. No similarities between any of the test strains and H. influenzae or A. lignieresii were noted. The close relationship of H. somnus, H. agni, and Histophilus ovis suggests that these unofficially named bacteria may belong to a single taxon. Images PMID:6408118

  11. Sustained mitogen-activated protein kinase activation with Aggregatibacter actinomycetemcomitans causes inflammatory bone loss.

    PubMed

    Dunmyer, J; Herbert, B; Li, Q; Zinna, R; Martin, K; Yu, H; Kirkwood, K L

    2012-10-01

    Aggregatibacter actinomycetemcomitans is a gram-negative facultative capnophile involved in pathogenesis of aggressive forms of periodontal disease. In the present study, we interrogated the ability of A. actinomycetemcomitans to stimulate innate immune signaling and cytokine production and established that A. actinomycetemcomitans causes bone loss in a novel rat calvarial model. In vitro studies indicated that A. actinomycetemcomitans stimulated considerable production of soluble cytokines, tumor necrosis factor-α, interleukin-6 and interleukin-10 in both primary bone marrow-derived macrophages and NR8383 macrophages. Immunoblot analysis indicated that A. actinomycetemcomitans exhibits sustained activation of all major mitogen-activated protein kinase (MAPK) pathways, as well as the negative regulator of MAPK signaling, MAPK phosphatase-1 (MKP-1), for at least 8 h. In a rat calvarial model of inflammatory bone loss, high and low doses of formalin-fixed A. actinomycetemcomitans were microinjected into the supraperiosteal calvarial space for 1-2 weeks. Histological staining and micro-computed tomography of rat calvariae revealed a significant increase of inflammatory and fibroblast infiltrate and increased bone resorption as measured by total lacunar pit formation. From these data, we provide new evidence that fixed whole cell A. actinomycetemcomitans stimulation elicits a pro-inflammatory host response through sustained MAPK signaling, leading to enhanced bone resorption within the rat calvarial bone.

  12. Aggregatibacter actinomycetemcomitans, a potent immunoregulator of the periodontal host defense system and alveolar bone homeostasis.

    PubMed

    Herbert, B A; Novince, C M; Kirkwood, K L

    2016-06-01

    Aggregatibacter actinomycetemcomitans is a perio-pathogenic bacteria that has long been associated with localized aggressive periodontitis. The mechanisms of its pathogenicity have been studied in humans and preclinical experimental models. Although different serotypes of A. actinomycetemcomitans have differential virulence factor expression, A. actinomycetemcomitans cytolethal distending toxin (CDT), leukotoxin, and lipopolysaccharide (LPS) have been most extensively studied in the context of modulating the host immune response. Following colonization and attachment in the oral cavity, A. actinomycetemcomitans employs CDT, leukotoxin, and LPS to evade host innate defense mechanisms and drive a pathophysiologic inflammatory response. This supra-physiologic immune response state perturbs normal periodontal tissue remodeling/turnover and ultimately has catabolic effects on periodontal tissue homeostasis. In this review, we have divided the host response into two systems: non-hematopoietic and hematopoietic. Non-hematopoietic barriers include epithelium and fibroblasts that initiate the innate immune host response. The hematopoietic system contains lymphoid and myeloid-derived cell lineages that are responsible for expanding the immune response and driving the pathophysiologic inflammatory state in the local periodontal microenvironment. Effector systems and signaling transduction pathways activated and utilized in response to A. actinomycetemcomitans will be discussed to further delineate immune cell mechanisms during A. actinomycetemcomitans infection. Finally, we will discuss the osteo-immunomodulatory effects induced by A. actinomycetemcomitans and dissect the catabolic disruption of balanced osteoclast-osteoblast-mediated bone remodeling, which subsequently leads to net alveolar bone loss.

  13. First Human Case of Meningitis and Sepsis in a Child Caused by Actinobacillus suis or Actinobacillus equuli

    PubMed Central

    Montagnani, Carlotta; Pecile, Patrizia; Moriondo, Maria; Petricci, Patrizia; Becciani, Sabrina; Chiappini, Elena; Indolfi, Giuseppe; Rossolini, Gian Maria; de Martino, Maurizio

    2015-01-01

    We report the first human case of meningitis and sepsis caused in a child by Actinobacillus suis or A. equuli, a common opportunistic pathogen of swine or horses, respectively. Identification was performed by matrix-assisted laser desorption ionization–time of flight mass spectrometry and real-time PCR assay. A previous visit to a farm was suspected as the source of infection. PMID:25878346

  14. Quantitative proteomics reveal distinct protein regulations caused by Aggregatibacter actinomycetemcomitans within subgingival biofilms.

    PubMed

    Bao, Kai; Bostanci, Nagihan; Selevsek, Nathalie; Thurnheer, Thomas; Belibasakis, Georgios N

    2015-01-01

    Periodontitis is an infectious disease that causes the inflammatory destruction of the tooth-supporting (periodontal) tissues, caused by polymicrobial biofilm communities growing on the tooth surface. Aggressive periodontitis is strongly associated with the presence of Aggregatibacter actinomycetemcomitans in the subgingival biofilms. Nevertheless, whether and how A. actinomycetemcomitans orchestrates molecular changes within the biofilm is unclear. The aim of this work was to decipher the interactions between A. actinomycetemcomitans and other bacterial species in a multi-species biofilm using proteomic analysis. An in vitro 10-species "subgingival" biofilm model, or its derivative that included additionally A. actinomycetemcomitans, were anaerobically cultivated on hydroxyapatite discs for 64 h. When present, A. actinomycetemcomitans formed dense intra-species clumps within the biofilm mass, and did not affect the numbers of the other species in the biofilm. Liquid chromatography-tandem mass spectrometry was used to identify the proteomic content of the biofilm lysate. A total of 3225 and 3352 proteins were identified in the biofilm, in presence or absence of A. actinomycetemcomitans, respectively. Label-free quantitative proteomics revealed that 483 out of the 728 quantified bacterial proteins (excluding those of A. actinomycetemcomitans) were accordingly regulated. Interestingly, all quantified proteins from Prevotella intermedia were up-regulated, and most quantified proteins from Campylobacter rectus, Streptococcus anginosus, and Porphyromonas gingivalis were down-regulated in presence of A. actinomycetemcomitans. Enrichment of Gene Ontology pathway analysis showed that the regulated groups of proteins were responsible primarily for changes in the metabolic rate, the ferric iron-binding, and the 5S RNA binding capacities, on the universal biofilm level. While the presence of A. actinomycetemcomitans did not affect the numeric composition or absolute protein

  15. Quantitative Proteomics Reveal Distinct Protein Regulations Caused by Aggregatibacter actinomycetemcomitans within Subgingival Biofilms

    PubMed Central

    Bao, Kai; Bostanci, Nagihan; Selevsek, Nathalie; Thurnheer, Thomas; Belibasakis, Georgios N.

    2015-01-01

    Periodontitis is an infectious disease that causes the inflammatory destruction of the tooth-supporting (periodontal) tissues, caused by polymicrobial biofilm communities growing on the tooth surface. Aggressive periodontitis is strongly associated with the presence of Aggregatibacter actinomycetemcomitans in the subgingival biofilms. Nevertheless, whether and how A. actinomycetemcomitans orchestrates molecular changes within the biofilm is unclear. The aim of this work was to decipher the interactions between A. actinomycetemcomitans and other bacterial species in a multi-species biofilm using proteomic analysis. An in vitro 10-species “subgingival” biofilm model, or its derivative that included additionally A. actinomycetemcomitans, were anaerobically cultivated on hydroxyapatite discs for 64 h. When present, A. actinomycetemcomitans formed dense intra-species clumps within the biofilm mass, and did not affect the numbers of the other species in the biofilm. Liquid chromatography-tandem mass spectrometry was used to identify the proteomic content of the biofilm lysate. A total of 3225 and 3352 proteins were identified in the biofilm, in presence or absence of A. actinomycetemcomitans, respectively. Label-free quantitative proteomics revealed that 483 out of the 728 quantified bacterial proteins (excluding those of A. actinomycetemcomitans) were accordingly regulated. Interestingly, all quantified proteins from Prevotella intermedia were up-regulated, and most quantified proteins from Campylobacter rectus, Streptococcus anginosus, and Porphyromonas gingivalis were down-regulated in presence of A. actinomycetemcomitans. Enrichment of Gene Ontology pathway analysis showed that the regulated groups of proteins were responsible primarily for changes in the metabolic rate, the ferric iron-binding, and the 5S RNA binding capacities, on the universal biofilm level. While the presence of A. actinomycetemcomitans did not affect the numeric composition or absolute

  16. Effects of Aggregatibacter actinomycetemcomitans leukotoxin on endothelial cells.

    PubMed

    Dietmann, Anelia; Millonig, Alban; Combes, Valery; Couraud, Pierre-Olivier; Kachlany, Scott C; Grau, Georges E

    2013-01-01

    Aggregatibacter actinomycetemcomitans is a human pathogen that produces leukotoxin (LtxA) as a major virulence factor. In this study the effect of LtxA on microvascular endothelial cell viability and phenotype was studied. High doses of single LtxA treatment (500 ng/ml to 5 μg/ml) significantly and irreversibly decreased cell proliferation and induced apoptosis, as assessed by tetrazolium salt and annexin V assay, respectively. Apoptosis was partially inhibited by the pan-caspase inhibitor, z-VAD-fmk. LtxA caused a cell cycle arrest in the G2/M phase after 72 h. Between 500 ng/ml and 5 μg/ml, after long- or short-term stimulation LtxA increased the expression of ICAM-1 and VCAM-1, as well as the percentages of endothelial cells expressing these adhesion molecules. Thus, A. actinomycetemcomitans LtxA has substantial pro-inflammatory effects on human brain endothelial cells by upregulation of ICAM-1 and VCAM-1. Furthermore, LtxA in higher concentration was found to decrease proliferation and induces apoptosis in microvascular endothelial cells.

  17. Comparison of conventional and long-acting oxytetracyclines in prevention of induced Actinobacillus (Haemophilus) pleuropneumoniae infection of growing swine.

    PubMed Central

    Kiorpes, A L; Bäckström, L R; Collins, M T; Kruse, G O

    1989-01-01

    These experiments tested the hypothesis that long-acting oxytetracycline (oxytetracycline-LA) was more effective than regular oxytetracycline in preventing porcine pleuropneumonia when administered either 24 or 48 h prior to experimental challenge with virulent strains of Actinobacillus pleuropneumoniae. Two experiments (1 and 2) were conducted using growing pigs (average weight 12-15 kg). Antibiotic treatments were administered once intramuscularly at 20 mg/kg body weight; controls received an equivalent volume of saline. Clinical signs were recorded over seven days, and mortality rates and pathological lesions were analyzed using analysis of variance. Serum oxytetracycline levels were compared 48 and 72 h postinjection. All pigs developed clinical disease following experimental infection. Actinobacillus pleuropneumoniae was recovered from 42% of experiment 1 pigs and all of experiment 2 pigs. The data showed that both oxytetracycline and oxytetracycline-LA given at the same dose protected pigs against experimental infection when given 24 h prior to challenge, and there was no difference between the efficacy of the two drugs in this experiment. When administered 48 h prior to challenge, only oxytetracycline-LA reduced the clinical signs and pathological changes following A. pleuropneumoniae challenge. Between 48 and 72 h postinjection, oxytetracycline-LA blood levels were significantly greater compared to oxytetracycline-treated pigs. PMID:2531629

  18. Growth of Actinobacillus pleuropneumoniae is promoted by exogenous hydroxamate and catechol siderophores.

    PubMed

    Diarra, M S; Dolence, J A; Dolence, E K; Darwish, I; Miller, M J; Malouin, F; Jacques, M

    1996-03-01

    Siderophores bind ferric ions and are involved in receptor-specific iron transport into bacteria. Six types of siderophores were tested against strains representing the 12 different serotypes of Actinobacillus pleuropneumoniae. Ferrichrome and bis-catechol-based siderophores showed strong growth-promoting activities for A. pleuropneumoniae in a disk diffusion assay. Most strains of A. pleuropneumoniae tested were able to use ferrichrome (21 of 22 or 95%), ferrichrome A (20 of 22 or 90%), and lysine-based bis-catechol (20 of 22 or 90%), while growth of 36% (8 of 22) was promoted by a synthetic hydroxamate, N5-acetyl-N5-hydroxy-L-ornithine tripeptide. A. pleuropneumoniae serotype 1 (strain FMV 87-682) and serotype 5 (strain 2245) exhibited a distinct yellow halo around colonies on Chrome Azurol S agar plates, suggesting that both strains can produce an iron chelator (siderophore) in response to iron stress. The siderophore was found to be neither a phenolate nor a hydroxamate by the chemical tests of Arnow and Csaky, respectively. This is the first report demonstrating the production of an iron chelator and the use of exogenous siderophores by A. pleuropneumoniae. A spermidine-based bis-catechol siderophore conjugated to a carbacephalosporin was shown to inhibit growth of A. pleuropneumoniae. A siderophore-antibiotic-resistant strain was isolated and shown to have lost the ability to use ferrichrome, synthetic hydroxamate, or catechol-based siderophores when grown under conditions of iron restriction. This observation indicated that a common iron uptake pathway, or a common intermediate, for hydroxamate- and catechol-based siderophores may exist in A. pleuropneumoniae.

  19. Diverse Toll-like receptors mediate cytokine production by Fusobacterium nucleatum and Aggregatibacter actinomycetemcomitans in macrophages.

    PubMed

    Park, Se-Ra; Kim, Dong-Jae; Han, Seung-Hyun; Kang, Min-Jung; Lee, Jun-Young; Jeong, Yu-Jin; Lee, Sang-Jin; Kim, Tae-Hyoun; Ahn, Sang-Gun; Yoon, Jung-Hoon; Park, Jong-Hwan

    2014-05-01

    Toll-like receptors (TLRs) orchestrate a repertoire of immune responses in macrophages against various pathogens. Fusobacterium nucleatum and Aggregatibacter actinomycetemcomitans are two important periodontal pathogens. In the present study, we investigated TLR signaling regulating cytokine production of macrophages in response to F. nucleatum and A. actinomycetemcomitans. TLR2 and TLR4 are redundant in the production of cytokines (interleukin-6 [IL-6] and tumor necrosis factor alpha [TNF-α]) in F. nucleatum- and A. actinomycetemcomitans-infected macrophages. The production of cytokines by macrophages in response to F. nucleatum and A. actinomycetemcomitans infection was impaired in MyD88-deficient macrophages. Moreover, cytokine concentrations were lower in MyD88-deficient macrophages than in TLR2/TLR4 (TLR2/4) double-deficient cells. An endosomal TLR inhibitor, chloroquine, reduced cytokine production in TLR2/4-deficient macrophages in response to F. nucleatum and A. actinomycetemcomitans, and DNA from F. nucleatum or A. actinomycetemcomitans induced IL-6 production in bone marrow-derived macrophages (BMDMs), which was abolished by chloroquine. Western blot analysis revealed that TLR2/4 and MyD88 were required for optimal activation of NF-κB and mitogen-activated protein kinases (MAPKs) in macrophages in response to F. nucleatum and A. actinomycetemcomitans, with different kinetics. An inhibitor assay showed that NF-κB and all MAPKs (p38, extracellular signal-regulated kinase [ERK], and Jun N-terminal protein kinase [JNK]) mediate F. nucleatum-induced production of cytokines in macrophages, whereas NF-κB and p38, but not ERK and JNK, are involved in A. actinomycetemcomitans-mediated cytokine production. These findings suggest that multiple TLRs may participate in the cytokine production of macrophages against periodontal bacteria.

  20. Distribution of biotypes and leukotoxic activity of Aggregatibacter actinomycetemcomitans isolated from Brazilian patients with chronic periodontitis.

    PubMed

    Gaetti-Jardim, Elerson; Wahasugui, Thais Cristiane; Tomazinho, Paulo Henrique; Marques, Márcia Martins; Nakano, Viviane; Avila-Campos, Mario Julio

    2008-10-01

    Aggregatibacter actinomycetemcomitans is an important etiologic agent of the periodontitis and is associated with extra-oral infections. In this study, the detection of the ltxA gene as well as the ltx promoter region from leukotoxic A. actinomycetemcomitans isolated from 50 Brazilian patients with periodontitis and 50 healthy subjects was performed. The leukotoxic activity on HL-60 cells was also evaluated. Leukotoxic activity was determined using a trypan blue exclusion method. The 530 bp deletion in the promoter region was evaluated by PCR using a PRO primer pair. A. actinomycetemcomitans was detected by culture and directly from crude subgingival biofilm by PCR using specific primers. By culture, A. actinomycetemcomitans was detected in nine (18%) of the periodontal patients and one (2%) healthy subject. However, by PCR, this organism was detected in 44% of the periodontal patients and in 16% of the healthy subjects. It was verified a great discrepancy between PCR detection of the ltx operon promoter directly from crude subgingival biofilm and from bacterial DNA. Only one periodontal sample harbored highly leukotoxic A. actinomycetemcomitans. Moreover, biotype II was the most prevalent and no correlation between biotypes and leukotoxic activity was observed. The diversity of leukotoxin expression by A. actinomycetemcomitans suggests a role of this toxin in the pathogenesis of periodontal disease and other infectious diseases.

  1. Distribution of biotypes and leukotoxic activity of Aggregatibacter actinomycetemcomitans isolated from Brazilian patients with chronic periodontitis

    PubMed Central

    Gaetti-Jardim Jr., Elerson; Wahasugui, Thais Cristiane; Tomazinho, Paulo Henrique; Marques, Márcia Martins; Nakano, Viviane; Avila-Campos, Mario Julio

    2008-01-01

    Aggregatibacter actinomycetemcomitans is an important etiologic agent of the periodontitis and is associated with extra-oral infections. In this study, the detection of the ltxA gene as well as the ltx promoter region from leukotoxic A. actinomycetemcomitans isolated from 50 Brazilian patients with periodontitis and 50 healthy subjects was performed. The leukotoxic activity on HL-60 cells was also evaluated. Leukotoxic activity was determined using a trypan blue exclusion method. The 530 bp deletion in the promoter region was evaluated by PCR using a PRO primer pair. A. actinomycetemcomitans was detected by culture and directly from crude subgingival biofilm by PCR using specific primers. By culture, A. actinomycetemcomitans was detected in nine (18%) of the periodontal patients and one (2%) healthy subject. However, by PCR, this organism was detected in 44% of the periodontal patients and in 16% of the healthy subjects. It was verified a great discrepancy between PCR detection of the ltx operon promoter directly from crude subgingival biofilm and from bacterial DNA. Only one periodontal sample harbored highly leukotoxic A. actinomycetemcomitans. Moreover, biotype II was the most prevalent and no correlation between biotypes and leukotoxic activity was observed. The diversity of leukotoxin expression by A. actinomycetemcomitans suggests a role of this toxin in the pathogenesis of periodontal disease and other infectious diseases. PMID:24031284

  2. Apa is a trimeric autotransporter adhesin of Actinobacillus pleuropneumoniae responsible for autoagglutination and host cell adherence.

    PubMed

    Xiao, Longwen; Zhou, Liang; Sun, Changjiang; Feng, Xin; Du, ChongTao; Gao, Yu; Ji, Qun; Yang, Shuxin; Wang, Yu; Han, Wenyu; Langford, P R; Lei, Liancheng

    2012-10-01

    Actinobacillus pleuropneumoniae is the causative agent of porcine pleuropneumonia, and adherence to host cells is a key step in the pathogenic process. Although trimeric autotransporter adhesins (TAAs) were identified in many pathogenic bacteria in recent years, none in A. pleuropneumoniae have been characterized. In this study, we identified a TAA from A. pleuropneumoniae, Apa, and characterized the contribution of its amino acid residues to the adhesion process. Sequence analysis of the C-terminal amino acid residues of Apa revealed the presence of a putative translocator domain and six conserved HsfBD1-like or HsfBD2-like binding domains. Western blot analysis revealed that the 126 C-terminal amino acids of Apa could form trimeric molecules. By confocal laser scanning microscopy, one of these six domains (ApaBD3) was determined to mediate adherence to epithelial cells. Adherence assays and adherence inhibition assays using a recombinant E. coli- ApaBD3 strain which expressed ApaBD3 on the surface of E. coli confirmed that this domain was responsible for the adhesion activity. Moreover, cellular enzyme-linked immunosorbent assays demonstrated that ApaBD3 mediated high-level adherence to epithelial cell lines. Intriguingly, autoagglutination was observed with the E. coli- ApaBD3 strain, and this phenomenon was dependent upon the association of the expressed ApaBD3 with the C-terminal translocator domain.

  3. NLRP3 inflammasome is required for apoptosis of Aggregatibacter actinomycetemcomitans-infected human osteoblastic MG63 cells.

    PubMed

    Zhao, Panyu; Liu, Junchao; Pan, Chunling; Pan, Yaping

    2014-09-01

    Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans) is a Gram-negative bacterium which is implicated in the pathogenesis of human periodontal disease and in particular aggressive periodontitis. Virulence factors from A. actinomycetemcomitans have been shown to induce apoptosis of osteoblasts, however, the underlying mechanisms of the induction of apoptosis are poorly understood. In the present study, the infection of A. actinomycetemcomitans in human osteoblastic MG63 cells was established. Accordingly, A. actinomycetemcomitans infection enhanced significant apoptosis of MG63 cells. We found that both expression levels of NLRP3 and ASC were increased dramatically after MG63 cell cultures exposed to A. actinomycetemcomitans. Moreover, the secretion of mature interleukin-1β (IL-1β) and IL-18 were extensively induced in A. actinomycetemcomitans-infected cells as compared with non-invasion group of MG63 cell cultures, indicating the activation of the NLRP3 inflammasome during infection. Finally, we found that the knockdown expression of NLRP3 by specific small interfering RNA (siRNA) attenuated apoptosis of A. actinomycetemcomitans-infected MG63 cells. Our data suggest that A. actinomycetemcomitans promotes apoptosis of human osteoblasts at least partially through the NLRP3 inflammasome.

  4. [Breeding of Actinobacillus succiniogenes mutants with improved succinate production based on metabolic flux analysis].

    PubMed

    Pan, Lijun; Li, Xingjiang; Jiang, Shaotong; Wei, Zhaojun; Chen, Xiaohui; Cai, Licheng; Wang, Hefeng; Jiang, Jijun

    2008-09-01

    It is very important to obtain high yield mutant strains on the base of metabolic flux analysis of Actinobacillus succinogenes S.JST for the industrial bioconversion of succinic acid. The metabolic pathway was analized at first and the flux of the metabolic networks was calculated by matrix. In order to decrease acetic acid flux, the strains mutated by soft X-ray of synchronous radiation were screened on the plates with high concentration of fluoroacetic acid. For decreasing the metabolic flux of ethanol the site-directed mutagenesis was carried out for the reduction of alcohol dehydrogenase(Adh) specific activity. Then the enzyme activity determination and the gene sequence analysis of the mutant strain was compared with those of the parent strain. Metabolic flux analysis of the parent strain indicated that the flux of succinic acid was 1.78(mmol/g/h) and that the flux of acetic acid and ethanol were 0.60 (mmol/g/h) and 1.04( mmol/g/h), respectively. Meanwhile the metabolic pathway analysis showed that the ethanol metabolism enhanced the lacking of H electron donor during the synthesis of succinic acid and that the succinic acid flux was weakened by the metabolism of byproducts ethanol and acetic acid. Compared with the parent strain, the acetic acid flux of anti-fluoroacetic mutant strain S.JST1 was 0.024 (mmol/g/h), decreasing by 96%. Then the enzyme determination showed that the specific activity unit of phosphotransacetylase(Pta) decreased from 602 to 74 and a mutated site was founded in the pta gene of the mutant strain S.JST1. Compared with that of the parent strain S.JST1 the ethanol flux of adh-site-directed mutant strain S.JST2 was 0.020 (mmol/g/h), decreasing by 98%. Then the enzyme determination showed that the specific activity unit of Adh decreased from 585 to 62 and the yield of end product succinic acid was 65.7 (g/L). The interdiction of Adh and Pta decreased the metabolism of byproducts and the H electron donor was well balanced, thus the succinic

  5. Reaction of Human Sera from Juvenile Periodontitis, Rapidly Progressive Periodontitis, and Adult Periodontitis Patients with Selected Periodontopathogens,

    DTIC Science & Technology

    1984-11-13

    Fusobacterium nucleatum, and Actinobacillus actinomycetemcomitans (Y-4) serving as antigens. Increased i ii ~. DD I 1473 EDITION OF I NOV 6 , IS OBSOLETE...Bacteroides ging1valis, Capnocytophaga (Bacteroides) ochraceus, Fusobacterium nucleatum, and Actinobacillus actinomycetemcomitans (Y-4) serving as...thio-dependent collagenolytic activity has been identified in the culture filtrate of B. gingivalis. 3’ Actinobacillus actinomycetemcomitans (Aa) has

  6. Cloning and expression of a transferrin-binding protein from Actinobacillus pleuropneumoniae.

    PubMed Central

    Gerlach, G F; Anderson, C; Potter, A A; Klashinsky, S; Willson, P J

    1992-01-01

    An expression library was constructed from Actinobacillus pleuropneumoniae serotype 7. Escherichia coli transformants expressing recombinant proteins were identified by immunoscreening with porcine convalescent serum. One transformant expressing a 60-kDa protein (60K protein) in aggregated form was identified. Serum raised against the recombinant protein recognized a polypeptide with an indistinguishable electrophoretic mobility in the A. pleuropneumoniae wild type after iron-restricted growth only. The recombinant protein bound transferrin after blotting onto nitrocellulose. Using a competitive enzyme-linked immunosorbent assay (ELISA), the specificity of this binding for the amino-terminal half of iron-saturated porcine transferrin was established. Also, the 60K wild-type protein bound hemin as assessed by hemin-agarose chromatography. Hemin could inhibit transferrin binding of the recombinant protein in the competitive ELISA, whereas hemoglobin and synthetic iron chelators failed to do so. Southern blot analysis of several other A. pleuropneumoniae strains indicated that highly homologous sequence is present in eight of eight isolates of serotype 7 and in some isolates of serotypes 2, 3, and 4. Images PMID:1541562

  7. Role of (p)ppGpp in Viability and Biofilm Formation of Actinobacillus pleuropneumoniae S8

    PubMed Central

    Li, Gang; Xie, Fang; Zhang, Yanhe; Bossé, Janine T.; Langford, Paul R.; Wang, Chunlai

    2015-01-01

    Actinobacillus pleuropneumoniae is a Gram-negative bacterium and the cause of porcine pleuropneumonia. When the bacterium encounters nutritional starvation, the relA-dependent (p)ppGpp-mediated stringent response is activated. The modified nucleotides guanosine 5’-diphosphate 3’-diphosphate (ppGpp) and guanosine 5’-triphosphate 3’-diphosphate (pppGpp) are known to be signaling molecules in other prokaryotes. Here, to investigate the role of (p)ppGpp in A. pleuropneumoniae, we created a mutant A. pleuropneumoniae strain, S8ΔrelA, which lacks the (p)ppGpp-synthesizing enzyme RelA, and investigated its phenotype in vitro. S8ΔrelA did not survive after stationary phase (starvation condition) and grew exclusively as non-extended cells. Compared to the wild-type (WT) strain, the S8ΔrelA mutant had an increased ability to form a biofilm. Transcriptional profiles of early stationary phase cultures revealed that a total of 405 bacterial genes were differentially expressed (including 380 up-regulated and 25 down-regulated genes) in S8ΔrelA as compared with the WT strain. Most of the up-regulated genes are involved in ribosomal structure and biogenesis, amino acid transport and metabolism, translation cell wall/membrane/envelope biogenesis. The data indicate that (p)ppGpp coordinates the growth, viability, morphology, biofilm formation and metabolic ability of A. pleuropneumoniae in starvation conditions. Furthermore, S8ΔrelA could not use certain sugars nor produce urease which has been associated with the virulence of A. pleuropneumoniae, suggesting that (p)ppGpp may directly or indirectly affect the pathogenesis of A. pleuropneumoniae during the infection process. In summary, (p)ppGpp signaling represents an essential component of the regulatory network governing stress adaptation and virulence in A. pleuropneumoniae. PMID:26509499

  8. Surface Polysaccharide Mutants Reveal that Absence of O Antigen Reduces Biofilm Formation of Actinobacillus pleuropneumoniae

    PubMed Central

    Hathroubi, S.; Hancock, M. A.; Langford, P. R.; Tremblay, Y. D. N.; Labrie, J.

    2015-01-01

    Actinobacillus pleuropneumoniae is a Gram-negative bacterium belonging to the Pasteurellaceae family and the causative agent of porcine pleuropneumonia, a highly contagious lung disease causing important economic losses. Surface polysaccharides, including lipopolysaccharides (LPS) and capsular polysaccharides (CPS), are implicated in the adhesion and virulence of A. pleuropneumoniae, but their role in biofilm formation is still unclear. In this study, we investigated the requirement for these surface polysaccharides in biofilm formation by A. pleuropneumoniae serotype 1. Well-characterized mutants were used: an O-antigen LPS mutant, a truncated core LPS mutant with an intact O antigen, a capsule mutant, and a poly-N-acetylglucosamine (PGA) mutant. We compared the amount of biofilm produced by the parental strain and the isogenic mutants using static and dynamic systems. Compared to the findings for the biofilm of the parental or other strains, the biofilm of the O antigen and the PGA mutants was dramatically reduced, and it had less cell-associated PGA. Real-time PCR analyses revealed a significant reduction in the level of pgaA, cpxR, and cpxA mRNA in the biofilm cells of the O-antigen mutant compared to that in the biofilm cells of the parental strain. Specific binding between PGA and LPS was consistently detected by surface plasmon resonance, but the lack of O antigen did not abolish these interactions. In conclusion, the absence of the O antigen reduces the ability of A. pleuropneumoniae to form a biofilm, and this is associated with the reduced expression and production of PGA. PMID:26483403

  9. The RNA Chaperone Hfq Promotes Fitness of Actinobacillus pleuropneumoniae during Porcine Pleuropneumonia

    PubMed Central

    Subashchandrabose, Sargurunathan; Leveque, Rhiannon M.; Kirkwood, Roy N.; Kiupel, Matti

    2013-01-01

    Actinobacillus pleuropneumoniae is the etiological agent of porcine pleuropneumonia, an economically important disease of pigs. The hfq gene in A. pleuropneumoniae, encoding the RNA chaperone and posttranscriptional regulator Hfq, is upregulated during infection of porcine lungs. To investigate the role of this in vivo-induced gene in A. pleuropneumoniae, an hfq mutant strain was constructed. The hfq mutant was defective in biofilm formation on abiotic surfaces. The level of pgaC transcript, encoding the biosynthesis of poly-β-1,6-N-acetylglucosamine (PNAG), a major biofilm matrix component, was lower and PNAG content was 10-fold lower in the hfq mutant than in the wild-type strain. When outer membrane proteins were examined, cysteine synthase, implicated in resistance to oxidative stress and tellurite, was not found at detectable levels in the absence of Hfq. The hfq mutant displayed enhanced sensitivity to superoxide generated by methyl viologen and tellurite. These phenotypes were readily reversed by complementation with the hfq gene expressed from its native promoter. The role of Hfq in the fitness of A. pleuropneumoniae was assessed in a natural host infection model. The hfq mutant failed to colonize porcine lungs and was outcompeted by the wild-type strain (median competitive index of 2 × 10−5). Our data demonstrate that the in vivo-induced gene hfq is involved in the regulation of PNAG-dependent biofilm formation, resistance to superoxide stress, and the fitness and virulence of A. pleuropneumoniae in pigs and begin to elucidate the role of an in vivo-induced gene in the pathogenesis of pleuropneumonia. PMID:23732171

  10. The RNA chaperone Hfq promotes fitness of Actinobacillus pleuropneumoniae during porcine pleuropneumonia.

    PubMed

    Subashchandrabose, Sargurunathan; Leveque, Rhiannon M; Kirkwood, Roy N; Kiupel, Matti; Mulks, Martha H

    2013-08-01

    Actinobacillus pleuropneumoniae is the etiological agent of porcine pleuropneumonia, an economically important disease of pigs. The hfq gene in A. pleuropneumoniae, encoding the RNA chaperone and posttranscriptional regulator Hfq, is upregulated during infection of porcine lungs. To investigate the role of this in vivo-induced gene in A. pleuropneumoniae, an hfq mutant strain was constructed. The hfq mutant was defective in biofilm formation on abiotic surfaces. The level of pgaC transcript, encoding the biosynthesis of poly-β-1,6-N-acetylglucosamine (PNAG), a major biofilm matrix component, was lower and PNAG content was 10-fold lower in the hfq mutant than in the wild-type strain. When outer membrane proteins were examined, cysteine synthase, implicated in resistance to oxidative stress and tellurite, was not found at detectable levels in the absence of Hfq. The hfq mutant displayed enhanced sensitivity to superoxide generated by methyl viologen and tellurite. These phenotypes were readily reversed by complementation with the hfq gene expressed from its native promoter. The role of Hfq in the fitness of A. pleuropneumoniae was assessed in a natural host infection model. The hfq mutant failed to colonize porcine lungs and was outcompeted by the wild-type strain (median competitive index of 2 × 10(-5)). Our data demonstrate that the in vivo-induced gene hfq is involved in the regulation of PNAG-dependent biofilm formation, resistance to superoxide stress, and the fitness and virulence of A. pleuropneumoniae in pigs and begin to elucidate the role of an in vivo-induced gene in the pathogenesis of pleuropneumonia.

  11. A consortium of Aggregatibacter actinomycetemcomitans, Streptococcus parasanguinis, and Filifactor alocis is present in sites prior to bone loss in a longitudinal study of localized aggressive periodontitis.

    PubMed

    Fine, Daniel H; Markowitz, Kenneth; Fairlie, Karen; Tischio-Bereski, Debbie; Ferrendiz, Javier; Furgang, David; Paster, Bruce J; Dewhirst, Floyd E

    2013-09-01

    Aggregatibacter actinomycetemcomitans-induced localized aggressive periodontitis (LAP) in African-American adolescents has been documented but is poorly understood. Two thousand fifty-eight adolescents aged 11 to 17 years were screened for their periodontal status and the presence of A. actinomycetemcomitans in their oral cavity. Seventy-one A. actinomycetemcomitans-negative and 63 A. actinomycetemcomitans-positive periodontally healthy subjects were enrolled, sampled, examined, and radiographed yearly for 3 years. Gingival and periodontal pocket depth and attachment levels were recorded. Disease presentation was characterized by bone loss (BL). Subgingival sites were sampled every 6 months to assess (i) the role of A. actinomycetemcomitans in BL and (ii) the association of A. actinomycetemcomitans and other microbes in their relationships to BL. Sixteen of 63 subjects with A. actinomycetemcomitans developed BL (the other 47 subjects with A. actinomycetemcomitans had no BL). No A. actinomycetemcomitans-negative subjects developed BL. Human oral microbe identification microarray (HOMIM) was used for subgingival microbial assessment. On a subject level, pooled data from A. actinomycetemcomitans-positive subjects who remained healthy had higher prevalences of Streptococcus and Actinomyces species, while A. actinomycetemcomitans-positive subjects with BL had higher prevalences of Parvimonas micra, Filifactor alocis, A. actinomycetemcomitans, and Peptostreptococcus sp. human oral taxon 113 (HOT-113). At vulnerable sites, A. actinomycetemcomitans, Streptococcus parasanguinis, and F. alocis levels were elevated prior to BL. In cases where the three-organism consortium (versus A. actinomycetemcomitans alone) was detected, the specificity for detecting sites of future BL increased from 62% to 99%, with a sensitivity of 89%. We conclude that detecting the presence of A. actinomycetemcomitans, S. parasanguinis, and F. alocis together indicates sites of future BL in LAP. A

  12. A Consortium of Aggregatibacter actinomycetemcomitans, Streptococcus parasanguinis, and Filifactor alocis Is Present in Sites Prior to Bone Loss in a Longitudinal Study of Localized Aggressive Periodontitis

    PubMed Central

    Markowitz, Kenneth; Fairlie, Karen; Tischio-Bereski, Debbie; Ferrendiz, Javier; Furgang, David; Paster, Bruce J.; Dewhirst, Floyd E.

    2013-01-01

    Aggregatibacter actinomycetemcomitans-induced localized aggressive periodontitis (LAP) in African-American adolescents has been documented but is poorly understood. Two thousand fifty-eight adolescents aged 11 to 17 years were screened for their periodontal status and the presence of A. actinomycetemcomitans in their oral cavity. Seventy-one A. actinomycetemcomitans-negative and 63 A. actinomycetemcomitans-positive periodontally healthy subjects were enrolled, sampled, examined, and radiographed yearly for 3 years. Gingival and periodontal pocket depth and attachment levels were recorded. Disease presentation was characterized by bone loss (BL). Subgingival sites were sampled every 6 months to assess (i) the role of A. actinomycetemcomitans in BL and (ii) the association of A. actinomycetemcomitans and other microbes in their relationships to BL. Sixteen of 63 subjects with A. actinomycetemcomitans developed BL (the other 47 subjects with A. actinomycetemcomitans had no BL). No A. actinomycetemcomitans-negative subjects developed BL. Human oral microbe identification microarray (HOMIM) was used for subgingival microbial assessment. On a subject level, pooled data from A. actinomycetemcomitans-positive subjects who remained healthy had higher prevalences of Streptococcus and Actinomyces species, while A. actinomycetemcomitans-positive subjects with BL had higher prevalences of Parvimonas micra, Filifactor alocis, A. actinomycetemcomitans, and Peptostreptococcus sp. human oral taxon 113 (HOT-113). At vulnerable sites, A. actinomycetemcomitans, Streptococcus parasanguinis, and F. alocis levels were elevated prior to BL. In cases where the three-organism consortium (versus A. actinomycetemcomitans alone) was detected, the specificity for detecting sites of future BL increased from 62% to 99%, with a sensitivity of 89%. We conclude that detecting the presence of A. actinomycetemcomitans, S. parasanguinis, and F. alocis together indicates sites of future BL in LAP. A

  13. The antibacterial mechanism of berberine against Actinobacillus pleuropneumoniae.

    PubMed

    Kang, Shuai; Li, Zhengwen; Yin, Zhongqiong; Jia, Renyong; Song, Xu; Li, Li; Chen, Zhenzhen; Peng, Lianci; Qu, Jing; Hu, Zhiqiang; Lai, Xin; Wang, Guangxi; Liang, Xiaoxia; He, Changliang; Yin, Lizi

    2015-01-01

    This study demonstrated berberine to be a potential natural compound against Actinobacillus pleuropneumoniae. Liquid doubling dilution, transmission electron microscopy (TEM), SDS-PAGE and 4',6-diamidino-2-phenylindole (DAPI) staining were employed to elucidate the antibacterial activity and mechanism of berberine. The minimal inhibitory concentration of berberine was 0.3125 mg/mL, and time-kill curves showed concentration and time dependence. The TEM micrographs displayed damaged cell wall, concentrated cytoplasm, cytoplasmic content leakage and cell death. SDS-PAGE and DAPI assays revealed that berberine can restrain DNA and protein syntheses. Berberine inhibited the synthesis of proteins associated with the growth and cleavage of bacteria and then blocked the division and development of bacteria. The compound ultimately induced cytoplasm pyknosis and bacterial death.

  14. Succinic acid production from sucrose by Actinobacillus succinogenes NJ113.

    PubMed

    Jiang, Min; Dai, Wenyu; Xi, Yonglan; Wu, Mingke; Kong, Xiangping; Ma, Jiangfeng; Zhang, Min; Chen, Kequan; Wei, Ping

    2014-02-01

    In this study, sucrose, a reproducible disaccharide extracted from plants, was used as the carbon source for the production of succinic acid by Actinobacillus succinogenes NJ113. During serum bottle fermentation, the succinic acid concentration reached 57.1g/L with a yield of 71.5%. Further analysis of the sucrose utilization pathways revealed that sucrose was transported and utilized via a sucrose phosphotransferase system, sucrose-6-phosphate hydrolase, and a fructose PTS. Compared to glucose utilization in single pathway, more pathways of A. succinogenes NJ113 are dependent on sucrose utilization. By changing the control strategy in a fed-batch culture to alleviate sucrose inhibition, 60.5g/L of succinic acid was accumulated with a yield of 82.9%, and the productivity increased by 35.2%, reaching 2.16g/L/h. Thus utilization of sucrose has considerable potential economics and environmental meaning.

  15. Aggregatibacter actinomycetemcomitans leukotoxin cytotoxicity occurs through bilayer destabilization

    PubMed Central

    Brown, Angela C.; Boesze-Battaglia, Kathleen; Du, Yurong; Stefano, Frank P.; Kieba, Irene R.; Epand, Raquel F.; Kakalis, Lazaros; Yeagle, Philip L.; Epand, Richard M.; Lally, Edward T.

    2012-01-01

    Summary The Gram-negative bacterium, Aggregatibacter actinomycetemcomitans, is a common inhabitant of the human upper aerodigestive tract. The organism produces an RTX (Repeats in ToXin) toxin (LtxA) that kills human white blood cells. LtxA is believed to be a membrane-damaging toxin, but details of the cell surface interaction for this and several other RTX toxins have yet to be elucidated. Initial morphological studies suggested that LtxA was bending the target cell membrane. Because the ability of a membrane to bend is a function of its lipid composition, we assessed the proficiency of LtxA to release of a fluorescent dye from a panel of liposomes composed of various lipids. Liposomes composed of lipids that form nonlamellar phases were susceptible to LtxA-induced damage while liposomes composed of lipids that do not form non-bilayer structures were not. Differential scanning calorimetry demonstrated that the toxin decreased the temperature at which the lipid transitions from a bilayer to a nonlamellar phase, while 31P nuclear magnetic resonance studies showed that the LtxA-induced transition from a bilayer to an inverted hexagonal phase occurs through the formation of an isotropic intermediate phase. These results indicate that LtxA cytotoxicity occurs through a process of membrane destabilization. PMID:22309134

  16. NADPH Oxidase Contributes to Resistance against Aggregatibacter actinomycetemcomitans-Induced Periodontitis in Mice.

    PubMed

    Bast, Antje; Kubis, Helen; Holtfreter, Birte; Ribback, Silvia; Martin, Heiner; Schreiner, Helen C; Dominik, Malte J; Breitbach, Katrin; Dombrowski, Frank; Kocher, Thomas; Steinmetz, Ivo

    2017-02-01

    Aggregatibacter actinomycetemcomitans is a Gram-negative commensal bacterium of the oral cavity which has been associated with the pathogenesis of periodontitis with severe alveolar bone destruction. The role of host factors such as reactive oxygen and nitrogen intermediates in periodontal A. actinomycetemcomitans infection and progression to periodontitis is still ill-defined. Therefore, this study aimed to analyze the role of NADPH oxidase and inducible nitric oxide synthase (iNOS) in a murine model of A. actinomycetemcomitans-induced periodontitis. NADPH oxidase-deficient (gp91(phox) knockout [KO]), iNOS-deficient (iNOS KO), and C57BL/6 wild-type mice were orally infected with A. actinomycetemcomitans and analyzed for bacterial colonization at various time points. Alveolar bone mineral density and alveolar bone volume were quantified by three-dimensional micro-computed tomography, and the degree of tissue inflammation was calculated by histological analyses. At 5 weeks after infection, A. actinomycetemcomitans persisted at significantly higher levels in the murine oral cavities of infected gp91(phox) KO mice than in those of iNOS KO and C57BL/6 mice. Concomitantly, alveolar bone mineral density was significantly lower in all three infected groups than in uninfected controls, but with the highest loss of bone density in infected gp91(phox) KO mice. Only infected gp91(phox) KO mice revealed significant loss of alveolar bone volume and enhanced inflammatory cell infiltration, as well as an increased number of osteoclasts. Our results indicate that NADPH oxidase is important to control A. actinomycetemcomitans infection in the murine oral cavity and to prevent subsequent alveolar bone destruction and osteoclastogenesis.

  17. Aggregatibacter actinomycetemcomitans lipopolysaccharide affects human gingival fibroblast cytoskeletal organization.

    PubMed

    Gutiérrez-Venegas, Gloria; Contreras-Marmolejo, Luis Arturo; Román-Alvárez, Patricia; Barajas-Torres, Carolina

    2008-04-01

    The cytoskeleton is a dynamic structure that plays a key role in maintaining cell morphology and function. This study investigates the effect of bacterial wall lipopolysaccharide (LPS), a strong inflammatory agent, on the dynamics and organization of actin, tubulin, vimentin, and vinculin proteins in human gingival fibroblasts (HGF). A time-dependent study showed a noticeable change in actin architecture after 1.5 h of incubation with LPS (1 microg/ml) with the formation of orthogonal fibers and further accumulation of actin filament at the cell periphery by 24 h. When 0.01-10 microg/ml of LPS was added to human gingival fibroblast cultures, cells acquired a round, flat shape and gradually developed cytoplasmic ruffling. Lipopolysaccharides extracted from Aggregatibacter actinomycetemcomitans periodontopathogenic bacteria promoted alterations in F-actin stress fibres of human gingival cells. Normally, human gingival cells have F-actin fibres that are organized in linear distribution throughout the cells, extending along the cell's length. LPS-treated cells exhibited changes in cytoskeletal protein organization, and F-actin was reorganized by the formation of bundles underneath and parallel to the cell membrane. We also found the reorganization of the vimentin network into vimentin bundling after 1.5 h of treatment. HGF cells exhibited diffuse and granular gamma-tubulin stain. There was no change in LPS-treated HGF. However, vinculin plaques distributed in the cell body diminished after LPS treatment. We conclude that the dynamic and structured organization of cytoskeletal filaments and actin assembly in human gingival fibroblasts is altered by LPS treatment and is accompanied by a decrease in F-actin pools.

  18. Aggregatibacter actinomycetemcomitans induces Th17 cells in atherosclerotic lesions.

    PubMed

    Jia, Ru; Hashizume-Takizawa, Tomomi; Du, Yuan; Yamamoto, Masafumi; Kurita-Ochiai, Tomoko

    2015-04-01

    Th17 cells have been linked to the pathogenesis of several chronic inflammatory and autoimmune diseases. However, the role of Th17 cells and IL-17 in atherosclerosis remains poorly understood. We previously reported that Aggregatibacter actinomycetemcomitans (Aa) bacteremia accelerated atherosclerosis accompanied by inflammation in apolipoprotein E-deficient spontaneously hyperlipidemic (Apoe(shl)) mice. In this study, we investigated whether Aa promotes the Th17 inducing pathway in Aa-challenged Apoe(shl) mice. Mice were intravenously injected with live Aa HK1651 or vehicles. Time-course analysis of splenic IL-17(+)CD4(+) cell frequencies, the proximal aorta lesion area, serum IL-17, IL-6, TGF-β and IL-1β levels, the mRNA expression of Th17-related molecules such as IL-1β, IL-6, IL17RA, STAT3, IL-21, IL-23, TGF-β and RORγt, Th17-related microRNA levels and the levels of AIM-2, Mincle and NLRP3 were examined. Challenge with Aa time dependently induced tropism of Th17 cells in the spleen and increase in atheromatous lesions in the aortic sinus of Apoe(shl) mice. Serum IL-17, IL-6, TGF-β and IL-1β levels were significantly enhanced by Aa. The gene expression of IL-1β, IL-6, IL-17RA, IL-21, IL-23, TGF-β, STAT3, RORγt, AIM-2, Mincle and NLRP3 was also time dependently stimulated in the aorta of Aa-challenged mice. Furthermore, Aa challenge significantly increased the expression of miR-146b and miR-155 in the aorta. Based on the results, it seems that Aa stimulates Th17 induction that affects the progression of Aa-accelerated atherosclerosis.

  19. Transcriptional regulation of the Aggregatibacter actinomycetemcomitans ygiW-qseBC operon by QseB and integration host factor proteins.

    PubMed

    Juárez-Rodríguez, María Dolores; Torres-Escobar, Ascención; Demuth, Donald R

    2014-12-01

    The QseBC two-component system plays a pivotal role in regulating virulence and biofilm growth of the oral pathogen Aggregatibacter actinomycetemcomitans. We previously showed that QseBC autoregulates the ygiW-qseBC operon. In this study, we characterized the promoter that drives ygiW-qseBC expression. Using lacZ transcriptional fusion constructs and 5'-rapid amplification of cDNA ends, we showed that ygiW-qseBC expression is driven by a promoter that initiates transcription 53 bases upstream of ygiW and identified putative cis-acting promoter elements, whose function was confirmed using site-specific mutagenesis. Using electrophoretic mobility shift assays, two trans-acting proteins were shown to interact with the ygiW-qseBC promoter. The QseB response regulator bound to probes containing the direct repeat sequence CTTAA-N6-CTTAA, where the CTTAA repeats flank the -35 element of the promoter. The ygiW-qseBC expression could not be detected in A. actinomycetemcomitans ΔqseB or ΔqseBC strains, but was restored to WT levels in the ΔqseBC mutant when complemented by single copy chromosomal insertion of qseBC. Interestingly, qseB partially complemented the ΔqseBC strain, suggesting that QseB could be activated in the absence of QseC. QseB activation required its phosphorylation since complementation did not occur using qseB(pho-), encoding a protein with the active site aspartate substituted with alanine. These results suggest that QseB is a strong positive regulator of ygiW-qseBC expression. In addition, integration host factor (IHF) bound to two sites in the promoter region and an additional site near the 5' end of the ygiW ORF. The expression of ygiW-qseBC was increased by twofold in ΔihfA and ΔihfB strains of A. actinomycetemcomitans, suggesting that IHF is a negative regulator of the ygiW-qseBC operon.

  20. Immunological study of an attenuated Salmonella Typhimurium expressing ApxIA, ApxIIA, ApxIIIA and OmpA of Actinobacillus pleuropneumoniae in a mouse model.

    PubMed

    Hur, Jin; Eo, Seong Kug; Park, Sang-Youel; Choi, Yoonyoung; Lee, John Hwa

    2016-01-01

    Salmonella Typhimurium strain expressing the Actinobacillus pleuropneumoniae antigens, ApxIA, ApxIIA, ApxIIIA and OmpA, was previously constructed as a vaccine candidate for porcine pleuropneumonia. This strain was a live attenuated (∆lon∆cpxR∆asd)Salmonella as a delivery host and contained a vector containing asd. An immunological study of lymphocyte proliferation, T-lymphocyte subsets and cytokines in the splenocytes of a mouse model was carried out after stimulation with the candidate Salmonella Typhimurium by intranasal inoculation. The splenic lymphocyte proliferation and the levels of IL-4, IL-6 and IL-12 of the inoculated mice were significantly increased, and the T- and B-cell populations were also elevated. Collectively, the candidate may efficiently induce the Th1- and Th2-type immune responses.

  1. Serotype b of Aggregatibacter actinomycetemcomitans increases osteoclast and memory T-lymphocyte activation.

    PubMed

    Melgar-Rodríguez, S; Díaz-Zúñiga, J; Alvarez, C; Rojas, L; Monasterio, G; Carvajal, P; Escobar, A; Sanz, M; Vernal, R

    2016-04-01

    During periodontitis, alveolar bone resorption is associated with activation of T helper type 17 (Th17) lymphocytes and receptor activator of nuclear factor-κB ligand (RANKL) -induced osteoclasts. We previously reported that serotype b of Aggregatibacter actinomycetemcomitans has a higher capacity to trigger Th17-type differentiation and function in activated T lymphocytes and its lipopolysaccharide is a more potent immunogen compared with the other serotypes. This study aimed to investigate whether serotype b of A. actinomycetemcomitans induces higher Th17-associated RANKL production, RANKL-induced osteoclast activation, and antigen-specific memory T lymphocyte proliferation. On naive CD4(+) T lymphocytes stimulated with autologous dendritic cells primed with different A. actinomycetemcomitans serotypes, RANKL production, T-bet, GATA-3, RORC2 and Foxp3 expression, RORC2/RANKL intracellular double-expression, TRAP(+) osteoclast activation, and bone resorption were quantified. The frequency of proliferating memory T lymphocytes in response to A. actinomycetemcomitans serotypes was determined in periodontitis and healthy subjects. Naive CD4(+) T lymphocytes stimulated by serotype b-primed dendritic cells elicited higher levels of RANKL, RORC2, TRAP(+) osteoclasts, and bone resorption than the same cells stimulated with the other serotypes. RANKL positively correlated and co-expressed with RORC2. Memory T lymphocytes responding to serotype b were more frequently detected in periodontitis patients than healthy subjects. These results indicate that serotype b of A. actinomycetemcomitans is associated with higher production of RANKL and these increased levels are associated with Th17 lymphocyte induction, osteoclast activation, and bone resorption.

  2. Catecholamines promote Actinobacillus pleuropneumoniae growth by regulating iron metabolism.

    PubMed

    Li, Lu; Chen, Zhaohui; Bei, Weicheng; Su, Zhipeng; Huang, Qi; Zhang, Liang; Chen, Huanchun; Zhou, Rui

    2015-01-01

    Catecholamines are host stress hormones that can induce the growth of many bacteria by facilitating iron utilization and/or regulate the expression of virulence genes through specific hormone receptors. Whether these two responsive pathways are interconnected is unknown. In our previous study, it was found that catecholamines can regulate the expression of a great number of genes of Actinobacillus pleuropneumoniae, an important swine respiratory pathogen. However, bacterial growth was not affected by catecholamines in rich medium. In this study, it was discovered that catecholamines affected A. pleuropneumoniae growth in chemically defined medium (CDM). We found that serum inhibited A. pleuropneumoniae growth in CDM, while epinephrine, norepinephrine and dopamine promoted A. pleuropneumoniae growth in the CDM containing serum. The known bacterial hormone receptor QseC didn't play roles in this process. Ion-supplementation and transcriptome analysis indicated that serum addition resulted in iron-restricted conditions which were alleviated by the addition of catecholamines. Transferrin, one of the components in serum, inhibited the growth of A. pleuropneumoniae in CDM, an effect reversed by addition of catecholamines in a TonB2-dependent manner. Our data demonstrate that catecholamines promote A. pleuropneumoniae growth by regulating iron-acquisition and metabolism, which is independent of the adrenergic receptor QseC.

  3. Experimental infection of SPF pigs with Actinobacillus pleuropneumoniae serotype 9 alone or in association with Mycoplasma hyopneumoniae.

    PubMed

    Marois, Corinne; Gottschalk, Marcelo; Morvan, Hervé; Fablet, Christelle; Madec, François; Kobisch, Marylène

    2009-03-30

    The purpose of this study was to compare in SPF pigs, the pathogenicity of an Actinobacillus pleuropneumoniae serotype 9 strain 21 (isolated from the palatine tonsils of a healthy gilt on a French nucleus pig farm, with no clinical signs or lung lesions but a highly positive reaction to A. pleuropneumoniae serotype 9 antibodies) with a pathogenic A. pleuropneumoniae strain 4915 serotype 9 (isolated in France from an outbreak of porcine pleuropneumonia). The pathogenicity of one Mycoplasma hyopneumoniae strain alone or associated with A. pleuropneumoniae strain 21 was also compared. Eight groups of 7 pigs were infected (at 6 or 10 weeks of age) and a control group was kept non-infected. Results showed that sensitivity to A. pleuropneumoniae was related to the age of the pig (6 weeks vs 10 weeks) whatever the strain. Surviving pigs infected at 6 weeks of age developed severe clinical signs, lung lesions typical of A. pleuropneumoniae and they seroconverted. In contrast, symptoms and lung lesions were almost non-existent in pigs infected with strain 21 at 10 weeks of age, but a seroconversion was observed with very high ELISA titres. These results were in accordance with those observed in the nucleus pig farm. Infection with M. hyopneumoniae alone induced typical mycoplasmal symptoms, pneumonia and seroconversion. Symptoms and lung lesions were the most noticeable in pigs infected with M. hyopneumoniae at 6 weeks of age and with A. pleuropneumoniae 4 weeks later. Our results show that the presence of A. pleuropneumoniae serotype 9 in a pig herd may be clinically unnoticed and that M. hyopneumoniae may potentiate A. pleuropneumoniae infection.

  4. Adhesion Protein ApfA of Actinobacillus pleuropneumoniae Is Required for Pathogenesis and Is a Potential Target for Vaccine Development

    PubMed Central

    Zhou, Yang; Li, Lu; Chen, Zhaohui; Yuan, Hong; Chen, Huanchun

    2013-01-01

    Actinobacillus pleuropneumoniae is the etiologic agent of porcine pleuropneumonia, which causes serious economic losses in the pig farming industry worldwide. Due to a lack of knowledge of its virulence factors and a lack of effective vaccines able to confer cross-serotype protection, it is difficult to place this disease under control. By analyzing its genome sequences, we found that type IV fimbrial subunit protein ApfA is highly conserved among different serotypes of A. pleuropneumoniae. Our study shows that ApfA is an adhesin since its expression was greatly upregulated (135-fold) upon contact with host cells, while its deletion mutant attenuated its capability of adhesion. The inactivation of apfA dramatically reduced the ability of A. pleuropneumoniae to colonize mouse lung, suggesting that apfA is a virulence factor. Purified recombinant ApfA elicited an elevated humoral immune response and conferred robust protection against challenges with A. pleuropneumoniae serovar 1 strain 4074 and serovar 7 strain WF83 in mice. Importantly, the anti-ApfA serum conferred significant protection against both serovar 1 and serovar 7 in mice. These studies indicate that ApfA promotes virulence through attachment to host cells, and its immunogenicity renders it a promising novel subunit vaccine candidate against infection with A. pleuropneumoniae. PMID:23269417

  5. Evaluation of a multiplex PCR to identify and serotype Actinobacillus pleuropneumoniae serovars 1, 5, 7, 12 and 15.

    PubMed

    Turni, C; Singh, R; Schembri, M A; Blackall, P J

    2014-10-01

    The aim of this study was to validate a multiplex PCR for the species identification and serotyping of Actinobacillus pleuropneumoniae serovars 1, 5, 7, 12 and 15. All 15 reference strains and 411 field isolates (394 from Australia, 11 from Indonesia, five from Mexico and one from New Zealand) of A. pleuropneumoniae were tested with the multiplex PCR. The specificity of this multiplex PCR was validated on 26 non-A. pleuropneumoniae species. The multiplex PCR gave the expected results with all 15 serovar reference strains and agreed with conventional serotyping for all field isolates from serovars 1 (n = 46), 5 (n = 81), 7 (n = 80), 12 (n = 16) and serovar 15 (n = 117). In addition, a species-specific product was amplified in the multiplex PCR with all 411 A. pleuropneumoniae field isolates. Of 25 nontypeable field isolates only two did not yield a serovar-specific band in the multiplex PCR. This multiplex PCR for serovars 1, 5, 7, 12 and 15 is species specific and capable of serotyping isolates from diverse locations. Significance and impact of the study: A multiplex PCR that can recognize serovars 1, 5, 7, 12 and 15 of A. pleuropneumoniae was developed and validated. This novel diagnostic tool will enable frontline laboratories to provide key information (the serovar) to guide targeted prevention and control programmes for porcine pleuropneumonia, a serious economic disease of pigs. The previous technology, traditional serotyping, is typically provided by specialized reference laboratories, limiting the capacity to respond to this key disease.

  6. Mitogen-Activated Protein Kinase 2 Signaling Shapes Macrophage Plasticity in Aggregatibacter actinomycetemcomitans-Induced Bone Loss.

    PubMed

    Herbert, Bethany A; Steinkamp, Heidi M; Gaestel, Matthias; Kirkwood, Keith L

    2017-01-01

    Aggregatibacter actinomycetemcomitans is associated with aggressive periodontal disease, which is characterized by inflammation-driven alveolar bone loss. A. actinomycetemcomitans activates the p38 mitogen-activated protein kinase (MAPK) and MAPK-activated protein kinase 2 (MK2) stress pathways in macrophages that are involved in host responses. During the inflammatory process in periodontal disease, chemokines are upregulated to promote recruitment of inflammatory cells. The objective of this study was to determine the role of MK2 signaling in chemokine regulation during A. actinomycetemcomitans pathogenesis. Utilizing a murine calvarial model, Mk2(+/+) and Mk2(-/-) mice were treated with live A. actinomycetemcomitans bacteria at the midsagittal suture. MK2 positively regulated the following macrophage RNA: Emr1 (F4/80), Itgam (CD11b), Csf1r (M-CSF Receptor), Itgal (CD11a), Tnf, and Nos2 Additionally, RNA analysis revealed that MK2 signaling regulated chemokines CCL3 and CCL4 in murine calvarial tissue. Utilizing the chimeric murine air pouch model, MK2 signaling differentially regulated CCL3 and CCL4 in the hematopoietic and nonhematopoietic compartments. Bone resorption pits in calvaria, observed by micro-computed tomography, and osteoclast formation were decreased in Mk2(-/-) mice compared to Mk2(+/+) mice after A. actinomycetemcomitans treatment. In conclusion, these data suggest that MK2 in macrophages contributes to regulation of chemokine signaling during A. actinomycetemcomitans-induced inflammation and bone loss.

  7. MyD88 is essential for alveolar bone loss induced by Aggregatibacter actinomycetemcomitans lipopolysaccharide in mice.

    PubMed

    Madeira, M F M; Queiroz-Junior, C M; Cisalpino, D; Werneck, S M C; Kikuchi, H; Fujise, O; Ryffel, B; Silva, T A; Teixeira, M M; Souza, D G

    2013-12-01

    Aggregatibacter actinomycetemcomitans is a Gram-negative bacteria highly associated with localized aggressive periodontitis. The recognition of microbial factors, such as lipopolysaccharide from A. actinomycetemcomitans ((Aa)LPS), in the oral environment is made mainly by surface receptors known as Toll-like receptors (TLR). TLR4 is the major LPS receptor. This interaction leads to the production of inflammatory cytokines by myeloid differentiation primary-response protein 88 (MyD88) -dependent and -independent pathways, which may involve the adaptor Toll/interleukin-1 receptor-domain-containing adaptor inducing interferon-β (TRIF). The aim of this study was to assess the involvement of MyD88 in alveolar bone loss induced by (Aa)LPS in mice. C57BL6/J wild-type (WT) mice, MyD88, TRIF or TRIF/MyD88 knockout mice received 10 injections of Aa LPS strain FDC Y4 (5 μg in 3 μl), in the palatal gingival tissue of the right first molar, every 48 h. Phosphate-buffered saline was injected in the opposite side and used as control. Animals were sacrificed 24 h after the 10th injection and the maxillae were removed for macroscopic and biochemical analyses. The injections of Aa LPS induced significant alveolar bone loss in WT mice. In the absence of MyD88 or TRIF/MyD88 no bone loss induced by (Aa)LPS was observed. In contrast, responses in TRIF(-/-) mice were similar to those in WT mice. Diminished bone loss in the absence of MyD88 was associated with fewer TRAP-positive cells and increased expression of osteoblast markers, RUNX2 and osteopontin. There was also reduced tumor necrosis factor-α production in MyD88(-/-) mice. There was less osteoclast differentiation of hematopoietic bone marrow cells from MyD88(-/-) mice after (Aa)LPS stimulation. Hence, the signaling through MyD88 is pivotal for (Aa)LPS-induced osteoclast formation and alveolar bone loss.

  8. Characterization of monoclonal antibodies that recognize common epitopes located on O antigen of lipopolysaccharide of serotypes 1, 9 and 11 of Actinobacillus pleuropneumoniae.

    PubMed

    Rodríguez Barbosa, J I; Gutiérrez Martín, C B; Tascón, R I; González, O R; Mittal, K R; Rodríguez Ferri, E F

    1996-12-31

    Seven murine monoclonal antibodies (mAbs) against serotype 1 of Actinobacillus (Haemophilus) pleuropneumoniae (reference strain Shope 4074) were produced and characterized. All hybridomas secreting mAbs were reactive with whole-cell antigens from reference strains of serotypes 1, 9 and 11, except for mAb 5D6 that failed to recognized serotype 9. They did not react with other taxonomically related Gram-negative organisms tested. The predominant isotype was immunoglobulin (Ig) M, although IgG2a, IgG2b, and IgG3 were also obtained. The epitopes identified by these mAbs were resistant to proteinase K treatment and boiling in the presence of sodium dodecyl sulfate and reducing conditions; however, they were sensitive to sodium periodate treatment. Enhanced chemiluminescence-immunodetection assay showed that mAbs could be divided in two groups according to the patterns of immunoreaction observed. Group 1 (mAbs 3E10, 4B7, 9H5 and 11C3) recognized a ladder-like banding profile consistent with the O antigen of lipopolysaccharide (LPS) from smooth strains. Group II (mAbs 3B10 and 9H1) recognized a long smear of high molecular weight which ranged from 60 to 200 kDa. The mAbs were tested against 96 field isolates belonging to serotypes 1, 5, 9, 11 and 12, which had previously been classified by a combination of serological techniques based on polyclonal rabbit sera (counterimmunoelectrophoresis, immunodiffusion and coagglutination). The panel of mAbs identified all isolates of serotypes 9 and 11, but only 66% of those belonging to serotype 1. This may suggest the existence of antigenic heterogeneity among isolates of A. pleuropneumoniae serotype 1. These mAbs reacted with epitopes common to serotypes 1, 9 and 11 of Actinobacillus pleuropneumoniae which were located on the O antigen of LPS.

  9. Characterisation of a mobilisable plasmid conferring florfenicol and chloramphenicol resistance in Actinobacillus pleuropneumoniae.

    PubMed

    Bossé, Janine T; Li, Yanwen; Atherton, Tom G; Walker, Stephanie; Williamson, Susanna M; Rogers, Jon; Chaudhuri, Roy R; Weinert, Lucy A; Holden, Matthew T G; Maskell, Duncan J; Tucker, Alexander W; Wren, Brendan W; Rycroft, Andrew N; Langford, Paul R

    2015-08-05

    The complete nucleotide sequence of a 7.7kb mobilisable plasmid (pM3446F), isolated from a florfenicol resistant isolate of Actinobacillus pleuropneumoniae, showed extended similarity to plasmids found in other members of the Pasteurellaceae containing the floR gene as well as replication and mobilisation genes. Mobilisation into other Pasteurellaceae species confirmed that this plasmid can be transferred horizontally.

  10. Actinobacillus equuli as a primary pathogen in breeding sows and piglets

    PubMed Central

    Thompson, Amy B.; Postey, Rosemary C.; Snider, Tim; Pasma, Tim

    2010-01-01

    The death of over 300 sows in 2 months on a 3000 sow farrow-to-isowean operation in Manitoba was attributed to infection with Actinobacillus equuli. This pathogen commonly infects foals, and is rarely reported in swine. Our report is the second recently published case of this pathogen in North American swine. PMID:21286321

  11. Actinobacillus pleuropneumoniae infections in closed swine herds: infection patterns and serological profiles.

    PubMed

    Chiers, Koen; Donné, Eef; Van Overbeke, Ingrid; Ducatelle, Richard; Haesebrouck, Freddy

    2002-04-02

    Many farrow-to-finish herds are endemically infected with Actinobacillus pleuropneumoniae. In order to control the disease efficiently, a better knowledge of the ages at which pigs become infected is necessary. Furthermore, no information is available concerning the influence of maternally derived antibodies on the colonization of the upper respiratory tract. Therefore, A. pleuropneumoniae infection patterns were studied in five farrow-to-finish pig herds (A-E) with a history of pleuropneumonia. A longitudinal study was carried out in herds A and B. In these herds, piglets from sows carrying A. pleuropneumoniae in their noses or tonsils were sampled. Nasal and tonsillar swabs as well as sera, were collected from these animals at the age of 4, 8, 12, 16 (herds A and B) and 23 weeks (herd B). At these ages other pigs from the same sows were euthanized. The lungs were macroscopically examined and samples from nose, tonsils and lungs were collected at necropsy. A cross-sectional study was performed in herds C-E. In these herds nasal and tonsillar swabs, as well as sera, were taken from 10 animals of 4, 8, 12 and 16 weeks of age. Lung, nasal and tonsillar samples were tested for the presence of A. pleuropneumoniae by routine bacteriology and PCR with mixed bacterial cultures. The sera were examined for the presence of Apx toxin neutralizing antibodies. In herd A, A. pleuropneumoniae serotype 2 and 10 strains were isolated, whereas serotype 2, 3, 5b and 8 strains were demonstrated in herd B. In most herds, A. pleuropneumoniae was detected in mixed bacterial cultures of tonsillar and/or nasal samples by PCR from the age of 4 weeks onwards. Colonization of the lungs and development of lung lesions was observed in 12- and 16-week-old animals of herd A and 23-week-old animals of herd B. In most herds, high antibody titres were detected in 4-week-old piglets. These titres decreased during the first 12 weeks of age, but thereafter, increased. It was concluded that PCR with

  12. Differential gene expression profiling of Actinobacillus pleuropneumoniae during induction of primary alveolar macrophage apoptosis in piglets.

    PubMed

    Wang, Lei; Qin, Wanhai; Ruidong, Zhai; Liu, Shiting; Zhang, Hu; Sun, Changjiang; Feng, Xin; Gu, Jingmin; Du, Chongtao; Han, Wenyu; Langford, P R; Lei, Liancheng

    2015-01-01

    Actinobacillus pleuropneumoniae (A. pleuropneumoniae) is the causative agent of porcine pleuropneumonia, a disease that causes serious problems for the swine industry. Successful infection by this bacterium requires breaking the first line of defence in the lungs, the primary alveolar macrophages (PAMs). Therefore, exploring A. pleuropneumoniae-PAM interactions will provide vital groundwork for the scientific control of this infectious disease, which has been little studied up to now. In this work, PAMs were isolated from piglets and co-incubated with A. pleuropneumoniae serovar 5b strain L20 in vitro, and their interaction, PAM cell death, and differential gene expression of A. pleuropneumoniae in response to PAM cell death were observed and analysed using confocal microscopy, electron microscopy, RT-PCR, Western blot, flow cytometry and the use of a gene expression profile chip. A. pleuropneumoniae quickly adhered to and invaded PAMs, inducing apoptosis, which was confirmed using transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The highest percentage of apoptosis in cells was confirmed using flow cytometry when the cells were infected at a multiplicity of infection (MOI) of 10 and incubated for 5 h, with higher expression of activated caspase-3 as measured by Western blot. Using microarray gene chips with 2868 probes containing nearly all of the genomic sequence of A. pleuropneumoniae serotype 5b strain L20, a total of 185 bacterial genes were found to be differentially expressed (including 92 up-regulated and 93 down-regulated genes) and involved in the process of apoptosis, as compared with the expression of control bacteria cultured without PAMs in BHI medium (mean expression ratios >1.5-fold, p < 0.05). The up-regulated genes are involved in energy metabolism, gene transcription and translation, virulence related gene such as LPS, Trimeric Autotransporter Adhesin, RTX and similar genes. The down-regulated genes are

  13. Aggregatibacter actinomycetemcomitans: virulence of its leukotoxin and association with aggressive periodontitis.

    PubMed

    Åberg, Carola Höglund; Kelk, Peyman; Johansson, Anders

    2015-01-01

    Periodontitis is an infection-induced inflammatory disease that causes loss of the tooth supporting tissues. Much focus has been put on comparison of the microbial biofilm in the healthy periodontium with the diseased one. The information arising from such studies is limited due to difficulties to compare the microbial composition in these two completely different ecological niches. A few longitudinal studies have contributed with information that makes it possible to predict which individuals who might have an increased risk of developing aggressive forms of periodontitis, and the predictors are either microbial or/and host-derived factors. The most conspicuous condition that is associated with disease risk is the presence of Aggregatibacter actinomycetemcomitans at the individual level. This Gram-negative bacterium has a great genetic variation with a number of virulence factors. In this review we focus in particular on the leukotoxin that, based on resent knowledge, might be one of the most important virulence factors of A. actinomycetemcomitans.

  14. Development of a cps-based multiplex PCR for typing of Actinobacillus pleuropneumoniae serotypes 1, 2 and 5.

    PubMed

    Ito, Hiroya

    2010-05-01

    A cps-based multiplex PCR for typing of Actinobacillus pleuropneumoniae serotypes 1, 2 and 5 was developed. This method should be specific and practical in Japan where more than 88% of isolates are serotypes 1, 2 or 5.

  15. ICEApl1, an Integrative Conjugative Element Related to ICEHin1056, Identified in the Pig Pathogen Actinobacillus pleuropneumoniae

    PubMed Central

    Bossé, Janine T.; Li, Yanwen; Fernandez Crespo, Roberto; Chaudhuri, Roy R.; Rogers, Jon; Holden, Matthew T. G.; Maskell, Duncan J.; Tucker, Alexander W.; Wren, Brendan W.; Rycroft, Andrew N.; Langford, Paul R.

    2016-01-01

    ICEApl1 was identified in the whole genome sequence of MIDG2331, a tetracycline-resistant (MIC = 8 mg/L) serovar 8 clinical isolate of Actinobacillus pleuropneumoniae, the causative agent of porcine pleuropneumonia. PCR amplification of virB4, one of the core genes involved in conjugation, was used to identify other A. pleuropneumoniae isolates potentially carrying ICEApl1. MICs for tetracycline were determined for virB4 positive isolates, and shotgun whole genome sequence analysis was used to confirm presence of the complete ICEApl1. The sequence of ICEApl1 is 56083 bp long and contains 67 genes including a Tn10 element encoding tetracycline resistance. Comparative sequence analysis was performed with similar integrative conjugative elements (ICEs) found in other members of the Pasteurellaceae. ICEApl1 is most similar to the 59393 bp ICEHin1056, from Haemophilus influenzae strain 1056. Although initially identified only in serovar 8 isolates of A. pleuropneumoniae (31 from the UK and 1 from Cyprus), conjugal transfer of ICEApl1 to representative isolates of other serovars was confirmed. All isolates carrying ICEApl1 had a MIC for tetracycline of 8 mg/L. This is, to our knowledge, the first description of an ICE in A. pleuropneumoniae, and the first report of a member of the ICEHin1056 subfamily in a non-human pathogen. ICEApl1 confers resistance to tetracycline, currently one of the more commonly used antibiotics for treatment and control of porcine pleuropneumonia. PMID:27379024

  16. ICEApl1, an Integrative Conjugative Element Related to ICEHin1056, Identified in the Pig Pathogen Actinobacillus pleuropneumoniae.

    PubMed

    Bossé, Janine T; Li, Yanwen; Fernandez Crespo, Roberto; Chaudhuri, Roy R; Rogers, Jon; Holden, Matthew T G; Maskell, Duncan J; Tucker, Alexander W; Wren, Brendan W; Rycroft, Andrew N; Langford, Paul R

    2016-01-01

    ICEApl1 was identified in the whole genome sequence of MIDG2331, a tetracycline-resistant (MIC = 8 mg/L) serovar 8 clinical isolate of Actinobacillus pleuropneumoniae, the causative agent of porcine pleuropneumonia. PCR amplification of virB4, one of the core genes involved in conjugation, was used to identify other A. pleuropneumoniae isolates potentially carrying ICEApl1. MICs for tetracycline were determined for virB4 positive isolates, and shotgun whole genome sequence analysis was used to confirm presence of the complete ICEApl1. The sequence of ICEApl1 is 56083 bp long and contains 67 genes including a Tn10 element encoding tetracycline resistance. Comparative sequence analysis was performed with similar integrative conjugative elements (ICEs) found in other members of the Pasteurellaceae. ICEApl1 is most similar to the 59393 bp ICEHin1056, from Haemophilus influenzae strain 1056. Although initially identified only in serovar 8 isolates of A. pleuropneumoniae (31 from the UK and 1 from Cyprus), conjugal transfer of ICEApl1 to representative isolates of other serovars was confirmed. All isolates carrying ICEApl1 had a MIC for tetracycline of 8 mg/L. This is, to our knowledge, the first description of an ICE in A. pleuropneumoniae, and the first report of a member of the ICEHin1056 subfamily in a non-human pathogen. ICEApl1 confers resistance to tetracycline, currently one of the more commonly used antibiotics for treatment and control of porcine pleuropneumonia.

  17. Development of two real-time polymerase chain reaction assays to detect Actinobacillus pleuropneumoniae serovars 1-9-11 and serovar 2.

    PubMed

    Marois-Créhan, Corinne; Lacouture, Sonia; Jacques, Mario; Fittipaldi, Nahuel; Kobisch, Marylène; Gottschalk, Marcelo

    2014-01-01

    Two real-time, or quantitative, polymerase chain reaction (qPCR) assays were developed to detect Actinobacillus pleuropneumoniae serovars 1-9-11 (highly related serovars with similar virulence potential) and serovar 2, respectively. The specificity of these assays was verified on a collection of 294 strains, which included all 16 reference A. pleuropneumoniae strains (including serovars 5a and 5b), 263 A. pleuropneumoniae field strains isolated between 1992 and 2009 in different countries, and 15 bacterial strains other than A. pleuropneumoniae. The detection levels of both qPCR tests were evaluated using 10-fold dilutions of chromosomal DNA from reference strains of A. pleuropneumoniae serovars 1 and 2, and the detection limit for both assays was 50 fg per assay. The analytical sensitivities of the qPCR tests were also estimated by using pure cultures and tonsils experimentally spiked with A. pleuropneumoniae. The detection threshold was 2.5 × 10(4) colony forming units (CFU)/ml and 2.9 × 10(5) CFU/0.1 g of tonsil, respectively, for both assays. These specific and sensitive tests can be used for the serotyping of A. pleuropneumoniae in diagnostic laboratories to control porcine pleuropneumonia.

  18. Construction of new cloning, lacZ reporter and scarless-markerless suicide vectors for genetic studies in Aggregatibacter actinomycetemcomitans.

    PubMed

    Juárez-Rodríguez, María Dolores; Torres-Escobar, Ascención; Demuth, Donald R

    2013-05-01

    To elucidate the putative function of a gene, effective tools are required for genetic characterization that facilitate its inactivation, deletion or modification on the bacterial chromosome. In the present study, the nucleotide sequence of the Escherichia coli/Aggregatibacter actinomycetemcomitans shuttle vector pYGK was determined, allowing us to redesign and construct a new shuttle cloning vector, pJT4, and promoterless lacZ transcriptional/translational fusion plasmids, pJT3 and pJT5. Plasmids pJT4 and pJT5 contain the origin of replication necessary to maintain shuttle vector replication. In addition, a new suicide vector, pJT1, was constructed for the generation of scarless and markerless deletion mutations of genes in the oral pathogen A. actinomycetemcomitans. Plasmid pJT1 is a pUC-based suicide vector that is counter-selectable for sucrose sensitivity. This vector does not leave antibiotic markers or scars on the chromosome after gene deletion and thus provides the option to combine several mutations in the same genetic background. The effectiveness of pJT1 was demonstrated by the construction of A. actinomycetemcomitans isogenic qseB single deletion (ΔqseB) mutant and lsrRK double deletion mutants (ΔlsrRK). These new vectors may offer alternatives for genetic studies in A. actinomycetemcomitans and other members of the HACEK (Haemophilus spp., A. actinomycetemcomitans, Cardiobacterium hominis, Eikenella corrodens, and Kingella kingae) group of Gram-negative bacteria.

  19. Construction of new cloning, lacZ reporter and scarless-markerless suicide vectors for genetic studies in Aggregatibacter actinomycetemcomitans

    PubMed Central

    Juárez-Rodríguez, María Dolores; Torres-Escobar, Ascención; Demuth, Donald R.

    2013-01-01

    To elucidate the putative function of a gene, effective tools are required for genetic characterization that facilitate its inactivation, deletion or modification on the bacterial chromosome. In the present study, the nucleotide sequence of the Escherichia coli/Aggregatibacter actinomycetemcomitans shuttle vector pYGK was determined, allowing us to redesign and construct a new shuttle cloning vector, pJT4, and promoterless lacZ transcriptional/translational fusion plasmids, pJT3 and pJT5. Plasmids pJT4 and pJT5 contain the origin of replication necessary to maintain shuttle vector replication. In addition, a new suicide vector, pJT1, was constructed for the generation of scarless and markerless deletion mutations of genes in the oral pathogen A. actinomycetemcomitans. Plasmid pJT1 is a pUC-based suicide vector that is counter-selectable for sucrose sensitivity. This vector does not leave antibiotic markers or scars on the chromosome after gene deletion and thus provides the option to combine several mutations in the same genetic background. The effectiveness of pJT1 was demonstrated by the construction of A. actinomycetemcomitans isogenic qseB single deletion (ΔqseB) mutant and lsrRK double deletion mutants (ΔlsrRK). These new vectors may offer alternatives for genetic studies in A. actinomycetemcomitans and other members of the HACEK (Haemophilus spp., A. actinomycetemcomitans, Cardiobacterium hominis, Eikenella corrodens, and Kingella kingae) group of Gram-negative bacteria. PMID:23353051

  20. Characterization of Biofilm Formation in [Pasteurella] pneumotropica and [Actinobacillus] muris Isolates of Mouse Origin

    PubMed Central

    Sager, Martin; Benten, W. Peter M.; Engelhardt, Eva; Gougoula, Christina; Benga, Laurentiu

    2015-01-01

    [Pasteurella] pneumotropica biotypes Jawetz and Heyl and [Actinobacillus] muris are the most prevalent Pasteurellaceae species isolated from laboratory mouse. However, mechanisms contributing to their high prevalence such as the ability to form biofilms have not been studied yet. In the present investigation we analyze if these bacterial species can produce biofilms in vitro and investigate whether proteins, extracellular DNA and polysaccharides are involved in the biofilm formation and structure by inhibition and dispersal assays using proteinase K, DNase I and sodium periodate. Finally, the capacity of the biofilms to confer resistance to antibiotics is examined. We demonstrate that both [P.] pneumotropica biotypes but not [A.] muris are able to form robust biofilms in vitro, a phenotype which is widely spread among the field isolates. The biofilm inhibition and dispersal assays by proteinase and DNase lead to a strong inhibition in biofilm formation when added at the initiation of the biofilm formation and dispersed pre-formed [P.] pneumotropica biofilms, revealing thus that proteins and extracellular DNA are essential in biofilm formation and structure. Sodium periodate inhibited the bacterial growth when added at the beginning of the biofilm formation assay, making difficult the assessment of the role of β-1,6-linked polysaccharides in the biofilm formation, and had a biofilm stimulating effect when added on pre-established mature biofilms of [P.] pneumotropica biotype Heyl and a majority of [P.] pneumotropica biotype Jawetz strains, suggesting that the presence of β-1,6-linked polysaccharides on the bacterial surface might attenuate the biofilm production. Conversely, no effect or a decrease in the biofilm quantity was observed by biofilm dispersal using sodium periodate on further biotype Jawetz isolates, suggesting that polysaccharides might be incorporated in the biofilm structure. We additionally show that [P.] pneumotropica cells enclosed in biofilms

  1. Characterization of Biofilm Formation in [Pasteurella] pneumotropica and [Actinobacillus] muris Isolates of Mouse Origin.

    PubMed

    Sager, Martin; Benten, W Peter M; Engelhardt, Eva; Gougoula, Christina; Benga, Laurentiu

    2015-01-01

    [Pasteurella] pneumotropica biotypes Jawetz and Heyl and [Actinobacillus] muris are the most prevalent Pasteurellaceae species isolated from laboratory mouse. However, mechanisms contributing to their high prevalence such as the ability to form biofilms have not been studied yet. In the present investigation we analyze if these bacterial species can produce biofilms in vitro and investigate whether proteins, extracellular DNA and polysaccharides are involved in the biofilm formation and structure by inhibition and dispersal assays using proteinase K, DNase I and sodium periodate. Finally, the capacity of the biofilms to confer resistance to antibiotics is examined. We demonstrate that both [P.] pneumotropica biotypes but not [A.] muris are able to form robust biofilms in vitro, a phenotype which is widely spread among the field isolates. The biofilm inhibition and dispersal assays by proteinase and DNase lead to a strong inhibition in biofilm formation when added at the initiation of the biofilm formation and dispersed pre-formed [P.] pneumotropica biofilms, revealing thus that proteins and extracellular DNA are essential in biofilm formation and structure. Sodium periodate inhibited the bacterial growth when added at the beginning of the biofilm formation assay, making difficult the assessment of the role of β-1,6-linked polysaccharides in the biofilm formation, and had a biofilm stimulating effect when added on pre-established mature biofilms of [P.] pneumotropica biotype Heyl and a majority of [P.] pneumotropica biotype Jawetz strains, suggesting that the presence of β-1,6-linked polysaccharides on the bacterial surface might attenuate the biofilm production. Conversely, no effect or a decrease in the biofilm quantity was observed by biofilm dispersal using sodium periodate on further biotype Jawetz isolates, suggesting that polysaccharides might be incorporated in the biofilm structure. We additionally show that [P.] pneumotropica cells enclosed in biofilms

  2. Effects of ketoprofen and flunixin in pigs experimentally infected with Actinobacillus pleuropneumoniae.

    PubMed

    Swinkels, J M; Pijpers, A; Vernooy, J C; Van Nes, A; Verheijden, J H

    1994-08-01

    The antipyretic effect of the non-steroidal anti-inflammatory drugs (NSAIDs) ketoprofen (3 mg/kg) and flunixin (2 mg/kg) were studied in pigs. The drugs were administered intramuscularly at 8 and 32 h following endobronchial challenge with Actinobacillus pleuropneumoniae. Infected (non-medicated) and non-infected (non-medicated) controls were used. Endobronchial challenge with Actinobacillus pleuropneumoniae induced laboured breathing, coughing, fever, reduced food and water consumption and increased white blood cell counts. At autopsy, pleuropneumonia was evident. Ketoprofen showed a highly significant antipyretic effect but flunixin did not. The decrease in food consumption of ketoprofen-treated pigs was significantly less than that of the infected (non-medicated) controls. Blood parameters were not significantly influenced by either NSAID and, at necropsy, gastric and renal side-effects were not observed for either drug.

  3. Quantitative PCR studies of Aggregatibacter actinomycetemcomitans and Treponema denticola/Tanerella forsythensis Complex as Etiological Factors of Chronic Periodontitis.

    PubMed

    Yanushevich, O O; Ayvazova, R A; Shibaeva, A V; Rebrikov, D V; Trubnikova, E V; Kudykina, Yu K; Zylnikova, M V; Zaripova, R S; Shevelev, A B

    2016-02-01

    Real-time quantitative PCR (Dentofl or kit) was used to detect DNA of periodontal pathogens in specimens from 92 patients with chronic periodontitis and from a control sample of 12 normal subjects. A bimodal distribution of patients by periodontium colonization with A. actinomycetemcomitans, P. gingivalis, P. intermedia, T. forsythensis, and T. denticola was demonstrated. A new approach to interpretation of the results of quantitative evaluation of periodontal pathogens, including the notion of pathological colonization level, led to classification of all cases with chronic generalized periodontitis into 3 groups: associated with A. actinomycetemcomitans, with T. forsythensis/T. denticola complex, and cases of uncertain genesis.

  4. Phylogenomic and molecular demarcation of the core members of the polyphyletic pasteurellaceae genera actinobacillus, haemophilus, and pasteurella.

    PubMed

    Naushad, Sohail; Adeolu, Mobolaji; Goel, Nisha; Khadka, Bijendra; Al-Dahwi, Aqeel; Gupta, Radhey S

    2015-01-01

    The genera Actinobacillus, Haemophilus, and Pasteurella exhibit extensive polyphyletic branching in phylogenetic trees and do not represent coherent clusters of species. In this study, we have utilized molecular signatures identified through comparative genomic analyses in conjunction with genome based and multilocus sequence based phylogenetic analyses to clarify the phylogenetic and taxonomic boundary of these genera. We have identified large clusters of Actinobacillus, Haemophilus, and Pasteurella species which represent the "sensu stricto" members of these genera. We have identified 3, 7, and 6 conserved signature indels (CSIs), which are specifically shared by sensu stricto members of Actinobacillus, Haemophilus, and Pasteurella, respectively. We have also identified two different sets of CSIs that are unique characteristics of the pathogen containing genera Aggregatibacter and Mannheimia, respectively. It is now possible to demarcate the genera Actinobacillus sensu stricto, Haemophilus sensu stricto, and Pasteurella sensu stricto on the basis of discrete molecular signatures. The other members of the genera Actinobacillus, Haemophilus, and Pasteurella that do not fall within the "sensu stricto" clades and do not contain these molecular signatures should be reclassified as other genera. The CSIs identified here also provide useful diagnostic targets for the identification of current and novel members of the indicated genera.

  5. Phylogenomic and Molecular Demarcation of the Core Members of the Polyphyletic Pasteurellaceae Genera Actinobacillus, Haemophilus, and Pasteurella

    PubMed Central

    Naushad, Sohail; Adeolu, Mobolaji; Goel, Nisha; Khadka, Bijendra; Al-Dahwi, Aqeel; Gupta, Radhey S.

    2015-01-01

    The genera Actinobacillus, Haemophilus, and Pasteurella exhibit extensive polyphyletic branching in phylogenetic trees and do not represent coherent clusters of species. In this study, we have utilized molecular signatures identified through comparative genomic analyses in conjunction with genome based and multilocus sequence based phylogenetic analyses to clarify the phylogenetic and taxonomic boundary of these genera. We have identified large clusters of Actinobacillus, Haemophilus, and Pasteurella species which represent the “sensu stricto” members of these genera. We have identified 3, 7, and 6 conserved signature indels (CSIs), which are specifically shared by sensu stricto members of Actinobacillus, Haemophilus, and Pasteurella, respectively. We have also identified two different sets of CSIs that are unique characteristics of the pathogen containing genera Aggregatibacter and Mannheimia, respectively. It is now possible to demarcate the genera Actinobacillus sensu stricto, Haemophilus sensu stricto, and Pasteurella sensu stricto on the basis of discrete molecular signatures. The other members of the genera Actinobacillus, Haemophilus, and Pasteurella that do not fall within the “sensu stricto” clades and do not contain these molecular signatures should be reclassified as other genera. The CSIs identified here also provide useful diagnostic targets for the identification of current and novel members of the indicated genera. PMID:25821780

  6. Environmental and physiological factors affecting the succinate product ratio during carbohydrate fermentation by Actinobacillus sp. 130Z.

    PubMed

    Van der Werf, M J; Guettler, M V; Jain, M K; Zeikus, J G

    1997-06-01

    Actinobacillus sp. 130Z fermented glucose to the major products succinate, acetate, and formate. Ethanol was formed as a minor fermentation product. Under CO2-limiting conditions, less succinate and more ethanol were formed. The fermentation product ratio remained constant at pH values from 6.0 to 7.4. More succinate was produced when hydrogen was present in the gas phase. Actinobacillus sp. 130Z grew at the expense of fumarate and l-malate reduction, with hydrogen as an electron donor. Other substrates such as more-reduced carbohydrates (e.g., d-sorbitol) resulted in higher succinate and/or ethanol production. Actinobacillus sp. 130Z contained the key enzymes involved in the Embden-Meyerhof-Parnas and the pentose-phosphate pathways and contained high levels of phosphoenolpyruvate (PEP) carboxykinase, malate dehydrogenase, fumarase, fumarate reductase, pyruvate kinase, pyruvate formate-lyase, phosphotransacetylase, acetate kinase, malic enzyme, and oxaloacetate decarboxylase. The levels of PEP carboxykinase, malate dehydrogenase, and fumarase were significantly higher in Actinobacillus sp. 130Z than in Escherichia coli K-12 and accounted for the differences in succinate production. Key enzymes in end product formation in Actinobacillus sp. 130Z were regulated by the energy substrates.

  7. Photosensitization of Aggregatibacter actinomycetemcomitans with methylene blue: a microbiological and spectroscopic study

    NASA Astrophysics Data System (ADS)

    Yamada Júnior, Aécio M.; Prates, Renato A.; Cai, Silvana; Ribeiro, Martha S.

    2008-03-01

    The aim of this study was to determinate the efficiency of methylene blue (MB) to kill cultures of Aggregatibacter actinomycetemcomitans under red light and to investigate MB photobleaching by optical absorption spectroscopy. Bacteria were diluted in aqueous solution, putted in glass tubes and distributed in 5 groups: (L-MB-) control group; (L+MB-) laser alone by 5min; (L-MB+) MB alone through 5min; (3L+MB+) MB+laser 3min; (5L+MB+) MB+laser 5min. Laser parameters were P=30mW, λ=660nm, E=9J in 5min and E=5.4J in 3min. The samples were diluted and bacterial colonies were counted and converted into colony forming units (CFU). Absorption spectra of the MB-stained bacterial suspension and photosensitized bacterial suspension were obtained. Groups L-MB-, L+MB-, and L-MB+ did not show a decrease in CFU/mL. L+MB+ groups showed a significant decrease in CFU/mL but no statistically significant differences were observed between 3min and 5min. Spectroscopy showed that MB is photodegraded after irradiation and that dimer species are more notably consumed than monomeric species. These results suggest that MB is a suitable photosensitizer to reduce A. actinomycetemcomitans, and that 3min of irradiation are enough to produce a significant effect. Due to the spectral changes observed on MB solution after irradiation a type I mechanism may be involved.

  8. Aggregatibacter actinomycetemcomitans leukotoxin: a powerful tool with capacity to cause imbalance in the host inflammatory response.

    PubMed

    Johansson, Anders

    2011-03-01

    Aggregatibacter actinomycetemcomitans has been described as a member of the indigenous oral microbiota of humans, and is involved in the pathology of periodontitis and various non-oral infections. This bacterium selectively kills human leukocytes through expression of leukotoxin, a large pore-forming protein that belongs to the Repeat in Toxin (RTX) family. The specificity of the toxin is related to its prerequisite for a specific target cell receptor, LFA-1, which is solely expressed on leukocytes. The leukotoxin causes death of different leukocyte populations in a variety of ways. It activates a rapid release of lysosomal enzymes and MMPs from neutrophils and causes apoptosis in lymphocytes. In the monocytes/macrophages, the toxin activates caspase-1, a cysteine proteinase, which causes a proinflammatory response by the activation and secretion of IL-1β and IL-18. A specific clone (JP2) of A. actinomycetemcomitans with enhanced leukotoxin expression significantly correlates to disease onset in infected individuals. Taken together, the mechanisms by which this toxin kills leukocytes are closely related to the pathogenic mechanisms of inflammatory disorders, such as periodontitis. Therapeutic strategies targeting the cellular and molecular inflammatory host response in periodontal diseases might be a future treatment alternative.

  9. Aggregatibacter actinomycetemcomitans: Virulence of its leukotoxin and association with aggressive periodontitis

    PubMed Central

    Åberg, Carola Höglund; Kelk, Peyman; Johansson, Anders

    2015-01-01

    Periodontitis is an infection-induced inflammatory disease that causes loss of the tooth supporting tissues. Much focus has been put on comparison of the microbial biofilm in the healthy periodontium with the diseased one. The information arising from such studies is limited due to difficulties to compare the microbial composition in these two completely different ecological niches. A few longitudinal studies have contributed with information that makes it possible to predict which individuals who might have an increased risk of developing aggressive forms of periodontitis, and the predictors are either microbial or/and host-derived factors. The most conspicuous condition that is associated with disease risk is the presence of Aggregatibacter actinomycetemcomitans at the individual level. This Gram-negative bacterium has a great genetic variation with a number of virulence factors. In this review we focus in particular on the leukotoxin that, based on resent knowledge, might be one of the most important virulence factors of A. actinomycetemcomitans. PMID:25494963

  10. Purification and characterization of a protease from Actinobacillus pleuropneumoniae serotype 1, an antigen common to all the serotypes.

    PubMed Central

    Negrete-Abascal, E; Tenorio, V R; Guerrero, A L; García, R M; Reyes, M E; de la Garza, M

    1998-01-01

    A high molecular-mass proteolytic enzyme of Actinobacillus pleuropneumoniae serotype 1, was purified from culture supernatants (CSN) by using DEAE-cellulose and sepharose-4B-gelatin chromatography. In 10% SDS-polyacrylamide gels copolymerized with porcine gelatin, the protease showed a single band of activity of > 200 kDa. However, minor molecular-mass proteolytic bands were observed when the protease was electrophoresed in the presence of either 5% beta-mercaptoethanol, 50 mM dithiothreitol, or 0.25 M urea. Furthermore, when the > 200-kDa purified protein was passed through a sucrose gradient, several bands with proteolytic activity were found: 62, 90, 190, and 540 kDa. The proteolytic activity was increased in the presence of calcium or zinc and was not affected after being heated at 90 degrees C for 5 min. Proteolytic activities were also observed in CSN from all A. pleuropneumoniae serotypes and biotypes. The purified protease hydrolyzed porcine IgA and IgG in vitro. In addition, by immunoblot the protease was recognized by serum of naturally infected pigs with serotypes 1 and 5, and by serum of pigs experimentally infected with serotypes 1, 2, 8, or 9. Serum of a pig vaccinated with CSN of a serotype 3 strain also recognized the protease, but not sera of pigs vaccinated with a bacterin (serotype 1). Proteins from CSN of all the serotypes, which were precipitated with 70% (NH4)2SO4, were recognized by a polyclonal antibody raised against the purified protease. Taken together these results indicate that an antigenic protease is produced in vivo by all the serotypes of A. pleuropneumoniae. The results indicate that proteases could have a role in the disease and in the immune response of pigs infected with A. pleuropneumoniae. Images Figure 2A. Figure 2B. Figure 3. Figure 4. Figure 5A. Figure 5B. Figure 6A. Figure 6B. PMID:9684047

  11. Interleukin-1β is internalised by viable Aggregatibacter actinomycetemcomitans biofilm and locates to the outer edges of nucleoids.

    PubMed

    Paino, Annamari; Lohermaa, Elina; Sormunen, Raija; Tuominen, Heidi; Korhonen, Jari; Pöllänen, Marja T; Ihalin, Riikka

    2012-11-01

    The opportunistic pathogen Aggregatibacter actinomycetemcomitans causes periodontitis, which is a biofilm infection that destroys tooth-supportive tissues. Interleukin (IL)-1β, a central proinflammatory cytokine of periodontitis, is an essential first line cytokine for local inflammation that modulates the cell proliferation and anti-pathogen response of human gingival keratinocytes. Previously, we demonstrated that A. actinomycetemcomitans biofilms bind IL-1β; however, whether this binding is an active process is not known. In this study, we showed for the first time with immuno-electron microscopy that viable bacterial biofilm cells internalised IL-1β when co-cultured with an organotypic mucosa. Decreased biofilm viability hindered the ability of biofilm to sequester IL-1β and caused IL-1β leakage into the culture medium. In some A. actinomycetemcomitans cells, intracellular IL-1β localized to the outer edges of the nucleoids. We identified the DNA-binding protein HU as an IL-1β interacting protein with mass spectroscopy and showed the interaction of recombinant HU and IL-1βin vitro using enzyme-linked immunosorbent assay (ELISA). Close contact with a viable A. actinomycetemcomitans biofilm decreased the proliferation and apoptosis of human gingival keratinocytes as demonstrated using Ki-67 and the terminal deoxynucleotidyl transferase dUTP nick-end labelling (TUNEL) staining, respectively. Our results suggest that viable A. actinomycetemcomitans biofilms may disturb the critical first steps of local inflammation in periodontitis by binding and internalising IL-1β. The interaction of IL-1β with conserved HU provides a potential mechanism for shaping bacterial gene expression.

  12. Antibacterial Effect of an Herbal Product Persica on Porphyromonas Gingivalis and Aggregatibacter Actinomycetemcomitans: An In-Vitro Study

    PubMed Central

    Jelvehgaran Esfahani, Zahra; Kadkhoda, Zeinab; Eshraghi, Seyed Saeed; Salehi Surmaghi, Mohammad Hossein

    2014-01-01

    Objective: The plant Salvadora persica is used for oral hygiene in many parts of the world. It has been suggested that it has antibacterial properties, in addition to its ability to mechanically remove plaques. The aim of this study was to assess the antimicrobial activity of the herbal product Persica containing Salvadora persica against periodontopathogens Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans in vitro. Materials and Methods: Fifty patients with moderate and severe periodontitis were recruited. Using paper points, subgingival plaque samples were taken from pockets with attachment loss ≥ 3mm. The samples were subjected to microbial culture to yield P. gingivalis and A. actinomycetemcomitans. The ditch plate method was used for antimicrobial susceptibility testing of the bacteria to Persica compared to chlorhexidine and distilled water. The growth inhibition zones of microorganisms around the ditches were measured in millimeters. The data were analyzed using SPSS 16. Freidman test and Wilcoxon signed ranks test with Bonferroni adjustment were used for analysis of variance with 5% significance level. P<0.05 for main comparisons and P< 0.017 for multiple comparisons were considered statistically significant. Results: P. gingivalis was sensitive to chlorhexidine and persica. There was a significant difference (P=0.001) between antimicrobial activity of chlorhexidine (mean 28.733mm, SD 5.216) and Persica (mean 16.333mm, SD 5.259) compared to water against P. gingivalis. There was a significant difference (P< 0.001) between the antimicrobial activity of chlorhexidine (24.045mm, SD 3.897) and Persica (0.545mm, SD 2.558) with respect to A. actinomycetemcomitans. There was no significant difference (P=0.317) between the antimicrobial activity of Persica and water against A. actinomycetemcomitans. Conclusion: The herbal product Persica had significant antimicrobial activity against P. gingivalis and negligible antimicrobial activity against A

  13. Multifocal suppurative granuloma caused by Actinobacillus lignieresii in the peritoneum of a beef steer

    PubMed Central

    KASUYA, Kazufumi; MANCHANAYAKE, Tilusha; UENOYAMA, Kei; KAWA, Sayaka; TAKAYAMA, Kou; IMAI, Naoto; SHIBAHARA, Tomoyuki

    2016-01-01

    An imported crossbred Angus beef steer aged eight to twelve months died suddenly on the eighth day of a quarantine period in Japan. Gross examination showed the peritoneum and mesentery consisted of numerous nodules of various sizes. Histological examination revealed chronic suppurative granulomatous peritonitis with eosinophilic rosettes surrounding colonies of Gram-negative bacilli. The bacteria isolated from the nodules were confirmed to be Actinobacillus lignieresii based on the results of 16S rRNA gene sequencing and immunohistochemistry. Antibiotic sensitivity testing showed that the isolate was resistant to penicillin. Thus, a diagnosis of atypical actinobacillosis caused by A. lignieresii was made. PMID:27773882

  14. Production of succinic acid from oil palm empty fruit bunch cellulose using Actinobacillus succinogenes

    NASA Astrophysics Data System (ADS)

    Pasma, Satriani Aga; Daik, Rusli; Maskat, Mohamad Yusof

    2013-11-01

    Succinic acid is a common metabolite in plants, animals and microorganisms. It has been used widely in agricultural, food and pharmaceutical industries. Enzymatic hydrolysate glucose from oil palm empty fruit bunch (OPEFB) cellulose was used as a substrate for succinic acid production using Actinobacillus succinogenes. Using cellulose extraction from OPEFB can enhance the production of glucose as a main substrate for succinic acid production. The highest concentration of glucose produced from enzymatic hydrolysis is 167 mg/mL and the sugar recovery is 0.73 g/g of OPEFB. By optimizing the culture medium for succinic acid fermentation with enzymatic hydrolysate of OPEFB cellulose, the nitrogen sources could be reduced to just only 2.5 g yeast extract and 2.5 g corn step liquor. Batch fermentation was carried out using enzymatic hydrolysate of OPEFB cellulose with yeast extract, corn steep liquor and the salts mixture, 23.5 g/L succinic acid was obtained with consumption of 72 g/L glucose in enzymatic hydrolysate of OPEFB cellulose at 38 hours and 37°C. This study suggests that enzymatic hydrolysate of OPEFB cellulose maybe an alternative substrate for the efficient production of succinic acid by Actinobacillus succinogenes.

  15. Actinobacillus pleuropneumoniae serotype 10 derived ApxI induces apoptosis in porcine alveolar macrophages.

    PubMed

    Chien, Maw-Sheng; Chan, You-Yu; Chen, Zeng-Weng; Wu, Chi-Ming; Liao, Jiunn-Wang; Chen, Ter-Hsin; Lee, Wei-Cheng; Yeh, Kuang-Sheng; Hsuan, Shih-Ling

    2009-03-30

    Actinobacillus pleuropneumoniae (AP) is the causative agent of swine pleuropneumonia, a fibrinous, exudative, hemorrhagic, necrotizing pleuropneumonia affecting all ages of pigs. Actinobacillus pleuropneumoniae exotoxins (Apx) are one of the major virulence factors of AP. Due to the complex nature of Apx toxins produced by AP, little is known regarding the interactions of individual species of Apx toxin with target cells. The objective of this study was to examine whether AP serotype 10-derived exotoxin, ApxI, caused apoptosis in porcine alveolar macrophages (PAMs) and to delineate the underlying signaling pathways. Isolated PAMs were stimulated with different concentrations of native ApxI and monitored for apoptosis using Hoechst staining, TUNEL, and DNA laddering assays. The ApxI-stimulated PAMs exhibited typical morphological features of apoptosis, including condensation of chromatin, formation of apoptotic bodies and DNA laddering. ApxI-induced apoptosis in a concentration- and time-dependent manner. Furthermore, to delineate the signaling events involved in ApxI-induced apoptosis, it was observed that caspase 3 was activated in ApxI-stimulated PAMs. Ablation of caspase 3 activity via specific inhibitors protected PAMs from apoptosis by ApxI. This study is the first to demonstrate that native ApxI causes apoptosis in PAMs at low concentrations and that these apoptotic events are mediated via a caspase 3-dependent pathway. These findings suggest a role of ApxI in AP infection as it might impair the host defense system through the induction of apoptosis in PAMs.

  16. Inflammatory Bone Loss in Experimental Periodontitis Induced by Aggregatibacter actinomycetemcomitans in Interleukin-1 Receptor Antagonist Knockout Mice

    PubMed Central

    Izawa, A.; Mizutani, H.; Kobayashi, S.; Goto, H.; Okabe, E.; Takeda, H.; Ozawa, Y.; Kamiya, Y.; Sugita, Y.; Kubo, K.; Kamei, H.; Kikuchi, T.; Mitani, A.; Hayashi, J.; Nishihara, T.; Maeda, H.; Noguchi, T.

    2014-01-01

    The interleukin-1 receptor antagonist (IL-1Ra) binds to IL-1 receptors and inhibits IL-1 activity. However, it is not clear whether IL-1Ra plays a protective role in periodontal disease. This study was undertaken to compare experimental periodontitis induced by Aggregatibacter actinomycetemcomitans in IL-1Ra knockout (KO) mice and wild-type (WT) mice. Computed tomography (CT) analysis and hematoxylin-and-eosin (H&E) and tartrate-resistant acid phosphatase (TRAP) staining were performed. In addition, osteoblasts were isolated; the mRNA expression of relevant genes was assessed by real-time quantitative PCR (qPCR); and calcification was detected by Alizarin Red staining. Infected IL-1Ra KO mice exhibited elevated (P, <0.05) levels of antibody against A. actinomycetemcomitans, bone loss in furcation areas, and alveolar fenestrations. Moreover, protein for tumor necrosis factor alpha (TNF-α) and IL-6, mRNA for macrophage colony-stimulating factor (M-CSF), and receptor activator of NF-κB ligand (RANKL) in IL-1Ra KO mouse osteoblasts stimulated with A. actinomycetemcomitans were increased (P, <0.05) compared to in WT mice. Alkaline phosphatase (ALP), bone sialoprotein (BSP), osteocalcin (OCN)/bone gla protein (BGP), and runt-related gene 2 (Runx2) mRNA levels were decreased (P, <0.05). IL-1α mRNA expression was increased, and calcification was not observed, in IL-1 Ra KO mouse osteoblasts. In brief, IL-1Ra deficiency promoted the expression of inflammatory cytokines beyond IL-1 and altered the expression of genes involved in bone resorption in A. actinomycetemcomitans-infected osteoblasts. Alterations consistent with rapid bone loss in infected IL-Ra KO mice were also observed for genes expressed in bone formation and calcification. In short, these data suggest that IL-1Ra may serve as a potential therapeutic drug for periodontal disease. PMID:24566623

  17. The pga gene cluster in Aggregatibacter actinomycetemcomitans is necessary for the development of natural competence in Ca(2+) -promoted biofilms.

    PubMed

    Hisano, K; Fujise, O; Miura, M; Hamachi, T; Matsuzaki, E; Nishimura, F

    2014-04-01

    Natural competence is the ability of bacteria to incorporate extracellular DNA into their genomes. This competence is affected by a number of factors, including Ca(2+) utilization and biofilm formation. As bacteria can form thick biofilms in the presence of extracellular Ca(2+) , the additive effects of Ca(2+) -promoted biofilm formation on natural competence should be examined. We evaluated natural competence in Aggregatibacter actinomycetemcomitans, an important periodontal pathogen, in the context of Ca(2+) -promoted biofilms, and examined whether the pga gene cluster, required for bacterial cell aggregation, is necessary for competence development. The A. actinomycetemcomitans cells grown in the presence of 1 mm CaCl2 exhibited enhanced cell aggregation and increased levels of cell-associated Ca(2+) . Biofilm-derived cells grown in the presence of Ca(2+) exhibited the highest levels of natural transformation frequency and enhanced expression of the competence regulator gene, tfoX. Natural competence was enhanced by the additive effects of Ca(2+) -promoted biofilms, in which high levels of pga gene expression were also detected. Mutation of the pga gene cluster disrupted biofilm formation and competence development, suggesting that these genes play a critical role in the ability of A. actinomycetemcomitans to adapt to its natural environment. The Ca(2+) -promoted biofilms may enhance the ability of bacteria to acquire extracellular DNA.

  18. Adh enhances Actinobacillus pleuropneumoniae pathogenicity by binding to OR5M11 and activating p38 which induces apoptosis of PAMs and IL-8 release.

    PubMed

    Wang, Lei; Qin, Wanhai; Zhang, Jing; Bao, Chuntong; Zhang, Hu; Che, Yanyi; Sun, Changjiang; Gu, Jingmin; Feng, Xin; Du, Chongtao; Han, Wenyu; Richard, Paul Langford; Lei, Liancheng

    2016-04-05

    Members of the Trimeric Autotransporter Adhesin (TAA) family play a crucial role in the adhesion of Gram-negative pathogens to host cells, but the immunopathogenesis of TAAs remains unknown. Our previous studies demonstrated that Adh from Actinobacillus pleuropneumoniae (A. pleuropneumoniae) is required for full bacterial pathogenicity. Alveolar macrophages are the first line of defense against respiratory infections. This study compared the interactions between porcine alveolar macrophages (PAMs) and wild-type A. pleuropneumoniae (5b WT) or an Adh-deletion strain (5b ΔAdh) via gene microarray, immunoprecipitation and other technologies. We found that Adh was shown to interact with the PAMs membrane protein OR5M11, an olfactory receptor, resulting in the high-level secretion of IL-8 by activation of p38 MAPK signaling pathway. Subsequently, PAMs apoptosis via the activation of the Fax and Bax signaling pathways was observed, followed by activation of caspases 8, 9, and 3. The immunological pathogenic roles of Adh were also confirmed in both murine and piglets infectious models in vivo. These results identify a novel immunological strategy for TAAs to boost the pathogenicity of A. pleuropneumoniae. Together, these datas reveal the high versatility of the Adh protein as a virulence factor and provide novel insight into the immunological pathogenic role of TAAs.

  19. Transcriptional regulation of Aggregatibacter actinomycetemcomitans lsrACDBFG and lsrRK operons and their role in biofilm formation.

    PubMed

    Torres-Escobar, Ascención; Juárez-Rodríguez, María Dolores; Lamont, Richard J; Demuth, Donald R

    2013-01-01

    Autoinducer-2 (AI-2) is required for biofilm formation and virulence of the oral pathogen Aggregatibacter actinomycetemcomitans, and we previously showed that lsrB codes for a receptor for AI-2. The lsrB gene is expressed as part of the lsrACDBFG operon, which is divergently transcribed from an adjacent lsrRK operon. In Escherichia coli, lsrRK encodes a repressor and AI-2 kinase that function to regulate lsrACDBFG. To determine if lsrRK controls lsrACDBFG expression and influences biofilm growth of A. actinomycetemcomitans, we first defined the promoters for each operon. Transcriptional reporter plasmids containing the 255-bp lsrACDBFG-lsrRK intergenic region (IGR) fused to lacZ showed that essential elements of lsrR promoter reside 89 to 255 bp upstream from the lsrR start codon. Two inverted repeat sequences that represent potential binding sites for LsrR and two sequences resembling the consensus cyclic AMP receptor protein (CRP) binding site were identified in this region. Using electrophoretic mobility shift assay (EMSA), purified LsrR and CRP proteins were shown to bind probes containing these sequences. Surprisingly, the 255-bp IGR did not contain the lsrA promoter. Instead, a fragment encompassing nucleotides +1 to +159 of lsrA together with the 255-bp IGR was required to promote lsrA transcription. This suggests that a region within the lsrA coding sequence influences transcription, or alternatively that the start codon of A. actinomycetemcomitans lsrA has been incorrectly annotated. Transformation of ΔlsrR, ΔlsrK, ΔlsrRK, and Δcrp deletion mutants with lacZ reporters containing the lsrA or lsrR promoter showed that LsrR negatively regulates and CRP positively regulates both lsrACDBFG and lsrRK. However, in contrast to what occurs in E. coli, deletion of lsrK had no effect on the transcriptional activity of the lsrA or lsrR promoters, suggesting that another kinase may be capable of phosphorylating AI-2 in A. actinomycetemcomitans. Finally, biofilm

  20. Agents of the "suis-ide diseases" of swine: Actinobacillus suis, Haemophilus parasuis, and Streptococcus suis.

    PubMed Central

    MacInnes, J I; Desrosiers, R

    1999-01-01

    In recent years, Actinobacillus suis, Haemophilus parasuis, and Streptococcus suis have emerged as important pathogens of swine, particularly in high health status herds. Their association with a wide range of serious clinical conditions and has given rise to the moniker "suis-ide diseases." These organisms are early colonizers and, for that reason, are difficult to control by management procedures such as segregated early weaning. Vaccination, serodiagnostic testing, and even serotyping are complicated by the presence of multiple serotypes, cross-reactive antigens, and the absence of clear markers for virulence. In this review, we discuss our current understanding of the pathogenesis, epidemiology, and management of the causative agents of the "suis-ide diseases" of swine. Images Figure 1. Figure 2. Figure 3. PMID:10369563

  1. Isolation of Actinobacillus seminis from a goat with clinical epididymo-orchitis in Brazil.

    PubMed

    dos Santos, Fabrine Alexandre; de Azevedo, Edísio Oliveira; de Azevedo, Sérgio Santos; Garino Júnior, Felício; Mota, Rinaldo Aparecido; de Cássia Peixoto Kim, Pomy; Gomes, Ana Lisa Vale; Alves, Clebert José

    2014-01-01

    The present study reports the first isolation of Actinobacillus seminis from a goat in Brazil. A four-year-old Moxotó breeding goat in a flock of 70 goats and 65 sheep reared together in the county of Patos, semiarid region of Northeastern Brazil, showed clinical signs of unilateral orchitis and epididymitis. Diagnosis of A. seminis infection was confirmed by association of clinical findings, bacterial isolation and 16S rRNA gene sequencing. This result suggests that A. seminis may be an additional cause of infertility in goats, and that sheep may be the source of infection because the mixed farming system allows the contact between sheep and goats in the semiarid region of Northeastern Brazil.

  2. Succinic acid production from duckweed (Landoltia punctata) hydrolysate by batch fermentation of Actinobacillus succinogenes GXAS137.

    PubMed

    Shen, Naikun; Wang, Qingyan; Zhu, Jing; Qin, Yan; Liao, Siming; Li, Yi; Zhu, Qixia; Jin, Yanling; Du, Liqin; Huang, Ribo

    2016-07-01

    Duckweed is potentially an ideal succinic acid (SA) feedstock due to its high proportion of starch and low lignin content. Pretreatment methods, substrate content and nitrogen source were investigated to enhance the bioconversion of duckweed to SA and to reduce the costs of production. Results showed that acid hydrolysis was an effective pretreatment method because of its high SA yield. The optimum substrate concentration was 140g/L. The optimum substrate concentration was 140g/L. Corn steep liquor powder could be considered a feasible and inexpensive alternative to yeast extract as a nitrogen source. Approximately 57.85g/L of SA was produced when batch fermentation was conducted in a 1.3L stirred bioreactor. Therefore, inexpensive duckweed can be a promising feedstock for the economical and efficient production of SA through fermentation by Actinobacillus succinogenes GXAS137.

  3. Isolation of Actinobacillus seminis from a goat with clinical epididymo-orchitis in Brazil

    PubMed Central

    dos Santos, Fabrine Alexandre; de Azevedo, Edísio Oliveira; de Azevedo, Sérgio Santos; Júnior, Felício Garino; Mota, Rinaldo Aparecido; de Cássia Peixoto Kim, Pomy; Gomes, Ana Lisa Vale; Alves, Clebert José

    2014-01-01

    The present study reports the first isolation of Actinobacillus seminis from a goat in Brazil. A four-year-old Moxotó breeding goat in a flock of 70 goats and 65 sheep reared together in the county of Patos, semiarid region of Northeastern Brazil, showed clinical signs of unilateral orchitis and epididymitis. Diagnosis of A. seminis infection was confirmed by association of clinical findings, bacterial isolation and 16S rRNA gene sequencing. This result suggests that A. seminis may be an additional cause of infertility in goats, and that sheep may be the source of infection because the mixed farming system allows the contact between sheep and goats in the semiarid region of Northeastern Brazil. PMID:24948932

  4. Aggregatibacter actinomycetemcomitans outer membrane vesicles are internalized in human host cells and trigger NOD1- and NOD2-dependent NF-κB activation.

    PubMed

    Thay, Bernard; Damm, Anna; Kufer, Thomas A; Wai, Sun Nyunt; Oscarsson, Jan

    2014-10-01

    Aggregatibacter actinomycetemcomitans is an oral and systemic pathogen associated with aggressive forms of periodontitis and with endocarditis. We recently demonstrated that outer membrane vesicles (OMVs) disseminated by A. actinomycetemcomitans could deliver multiple proteins, including biologically active cytolethal distending toxin (CDT), into the cytosol of HeLa cells and human gingival fibroblasts (HGF). In the present work, we have used immunoelectron and confocal microscopy analysis and fluorescently labeled vesicles to further investigate mechanisms for A. actinomycetemcomitans OMV-mediated delivery of bacterial antigens to these host cells. Our results supported that OMVs were internalized into the perinuclear region of HeLa cells and HGF. Colocalization analysis revealed that internalized OMVs colocalized with the endoplasmic reticulum and carried antigens, detected using an antibody specific to whole A. actinomycetemcomitans serotype a cells. Consistent with OMV internalization mediating intracellular antigen exposure, the vesicles acted as strong inducers of cytoplasmic peptidoglycan sensor NOD1- and NOD2-dependent NF-κB activation in human embryonic kidney cells. Moreover, NOD1 was the main sensor of OMV-delivered peptidoglycan in myeloid THP1 cells, contributing to the overall inflammatory responses induced by the vesicles. This work reveals a role of A. actinomycetemcomitans OMVs as a trigger of innate immunity via carriage of NOD1- and NOD2-active pathogen-associated molecular patterns (PAMPs).

  5. Amphotericin B down-regulates Aggregatibacter actinomycetemcomitans-induced production of IL-8 and IL-6 in human gingival epithelial cells.

    PubMed

    Imai, Haruka; Fujita, Tsuyoshi; Kajiya, Mikihito; Ouhara, Kazuhisa; Miyagawa, Tsuyoshi; Matsuda, Shinji; Shiba, Hideki; Kurihara, Hidemi

    2014-08-01

    Gingival epithelium is the primary barrier against microorganism invasion and produces inflammatory cytokines. Amphotericin B, a major antifungal drug, binds to cholesterol in the mammalian cell membrane in addition to fungal ergosterol. Amphotericin B has been shown to regulate inflammatory cytokines in host cells. To investigate the suppressive effect of amphotericin B on the gingival epithelium, we examined the expression of interleukin (IL)-8 and IL-6 and involvement of MAP kinase in human gingival epithelial cells (HGEC) stimulated by Aggregatibacter actinomycetemcomitans. Amphotericin B and the p38 MAP kinase inhibitor down-regulated the A. actinomycetemcomitans-induced increase in the expression of IL-8 and IL-6 at the mRNA. The ERK inhibitor suppressed the A. actinomycetemcomitans-induced IL-8 mRNA expression. Amphotericin B inhibited the A. actinomycetemcomitans-induced phosphorylation of ERK and p38 MAP kinase. Furthermore, amphotericin B inhibited the A. actinomycetemcomitans-induced production of prostaglandin E2. These results suggest that amphotericin B regulate inflammatory responses in HGEC.

  6. Use of 16S rRNA Sequencing for Identification of Actinobacillus ureae Isolated from a Cerebrospinal Fluid Sample

    PubMed Central

    Whitelaw, A. C.; Shankland, I. M.; Elisha, B. G.

    2002-01-01

    Actinobacillus ureae, previously Pasteurella ureae, has on rare occasions been described as a cause of human infection. Owing to its rarity, it may not be easily identified in clinical microbiology laboratories by standard tests. This report describes a patient with acute bacterial meningitis due to A. ureae. The identity of the isolate was determined by means of DNA sequence analysis of a portion of the 16S rRNA gene. PMID:11825992

  7. Evidence obtained with monoclonal antibodies that O antigen is the major antigen responsible for the cross-reactivities between serotypes 4 and 7 of Actinobacillus (Haemophilus) pleuropneumoniae.

    PubMed Central

    Rodríguez Barbosa, J I; Gutiérrez Martín, C B; Tascón, R I; Suárez, J; Rodríguez Ferri, E F

    1995-01-01

    Monoclonal antibodies (MAbs) against Actinobacillus (Haemophilus) pleuropneumoniae serotype 4 (reference strain M62 and field isolate F6) were produced and characterized. Three hybridoma clones were raised against strain M62, and 13 were raised against strain F6. The predominant antibody class was immunoglobulin M (IgM), although IgG2a and IgG2b were also obtained. Three of the MAbs produced to field isolate F6 (5C5, 1E10, and 5H7) did not recognize the reference strain of serotype 4, another (6F7) was reactive with both reference strains of serotypes 4 and 7, and the remaining 12 MAbs reacted only with the reference strain of the homologous serotype. All epitopes recognized by MAbs, except for one (6F7), were sensitive to periodic acid oxidation, and all of them were resistant to boiling in the presence of sodium dodecyl sulfate and reducing conditions, as evidenced by immunodot. Enhanced chemioluminiscence-immunoblot assays revealed that 10 MAbs (3E12, 5B8, 7C3, 6F7, 7F5, 7E6, 5G4, 4F1, 7E10, and 4B8) recognized a ladder-like banding pattern, which is in accordance with the O side chain antigen of lipopolysaccharide (LPS), while the remaining 6 MAbs (5C5, 5H7, 1E10, 6D11, 6B4, and 5E4) blotted with high-molecular-weight regions composed of a single banding pattern. The suitability of MAbs for serotyping of 78 field isolates was also examined. A high correlation was found between the results previously established by indirect hemagglutination with polyclonal sera and those obtained by enzyme-linked immunosorbent assay with MAbs. According to the different immunoreactivity of MAbs, three groups were established: group I (MAbs 3E12, 5B8, 7C3, 6F7, and 7F5), group II (MAbs 7E6, 5G4, 4F1, 7E10, and 4B8), and group III (MAbs 5C5, 5H7, and 1E10). MAbs 6D11, 6B4, and 5E4 could not be included in any of the described above. At least six different immunodominant epitopes on the O antigen of the A. pleuropneumoniae serotype 4 LPS were identified. Finally, the implications

  8. Alteration of Homeostasis in Pre-osteoclasts Induced by Aggregatibacter actinomycetemcomitans CDT.

    PubMed

    Kawamoto, Dione; Ando-Suguimoto, Ellen S; Bueno-Silva, Bruno; DiRienzo, Joseph M; Mayer, Marcia P A

    2016-01-01

    The dysbiotic microbiota associated with aggressive periodontitis includes Aggregatibacter actinomycetemcomitans, the only oral species known to produce a cytolethal distending toxin (AaCDT). Give that CDT alters the cytokine profile in monocytic cells, we aimed to test the hypothesis that CDT plays a role in bone homeostasis by affecting the differentiation of precursor cells into osteoclasts. Recombinant AaCDT was added to murine bone marrow monocytes (BMMC) in the presence or absence of RANKL and the cell viability and cytokine profile of osteoclast precursor cells were determined. Multinucleated TRAP(+) cell numbers, and relative transcription of genes related to osteoclastogenesis were also evaluated. The addition of AaCDT did not lead to loss in cell viability but promoted an increase in the average number of TRAP(+) cells with 1-2 nuclei in the absence or presence of RANKL (Tukey, p < 0.05). This increase was also observed for TRAP(+) cells with ≥3nuclei, although this difference was not significant. Levels of TGF-β, TNF-α, and IL-6, in the supernatant fraction of cells, were higher when in AaCDT exposed cells, whereas levels of IL-1β and IL-10 were lower than controls under the same conditions. After interaction with AaCDT, transcription of the rank (encoding the receptor RANK), nfatc1 (transcription factor), and ctpK (encoding cathepsin K) genes was downregulated in pre-osteoclastic cells. The data indicated that despite the presence of RANKL and M-CSF, AaCDT may inhibit osteoclast differentiation by altering cytokine profiles and repressing transcription of genes involved in osteoclastogenesis. Therefore, the CDT may impair host defense mechanisms in periodontitis.

  9. Bioactive glass combined with bisphosphonates provides protection against biofilms formed by the periodontal pathogen Aggregatibacter actinomycetemcomitans.

    PubMed

    Hiltunen, Anna K; Skogman, Malena E; Rosenqvist, Kirsi; Juvonen, Helka; Ihalainen, Petri; Peltonen, Jouko; Juppo, Anne; Fallarero, Adyary

    2016-03-30

    Biofilms play a pivotal role in the progression of periodontitis and they can be treated with antiseptics (i.e. chlorhexidine) or antibiotics, but these therapeutic alternatives are unable of ameliorating periodontal alveolar bone loss, which has been, on the other hand, successfully treated with bone-preserving agents. The improved bone formation achieved in animal models by the combination of two such agents: bioactive glass (BAG) and bisphosphonates has attracted the interest for further exploring dental applications. However, the antimicrobial effects that may result from combining them have not been yet investigated. Here, our aim was to explore the anti-biofilm effects that could result from combining BAG with bisphosphonates, particularly in a dental biofilm model. The experiments were performed with an oral cavity single-specie (Aggregatibacter actinomycetemcomitans) biofilm assay, which was optimized in this contribution. Risedronate displayed an intrinsic anti-biofilm effect, and all bisphosphonates, except clodronate, reduced biofilm formation when combined with BAG. In particular, the anti-biofilm activity of risedronate was significantly increased by the combination with BAG. Since it has been proposed that some of the antimicrobial effects of BAG are caused by local pH changes, studies of pH variations were performed to gain a mechanistic understanding. However, the observed anti-biofilm effects could not be explained with lowered pHs. Overall, these results do provide further support for the promising use of bisphosphonate-BAG combinations in dental applications. These findings are particularly relevant for patients undergoing cancer chemotherapy, or osteoporotic patients, which are known to be more vulnerable to periodontitis. In such cases, bisphosphonate treatment could play a double positive effect: local treatment of periodontitis (in combination with BAG) and systemic treatment of osteoporosis, prevention of hypercalcemia and metastases.

  10. Aggregatibacter actinomycetemcomitans leukotoxin induces cytosol acidification in LFA-1 expressing immune cells.

    PubMed

    Balashova, N; Dhingra, A; Boesze-Battaglia, K; Lally, E T

    2016-02-01

    Studies have suggested that Aggregatibacter actinomycetemcomitans leukotoxin (LtxA) kills human lymphocyte function-associated antigen 1 (LFA-1; CD11a/CD18)-bearing immune cells through a lysosomal-mediated mechanism. Lysosomes are membrane-bound cellular organelles that contain an array of acid hydrolases that are capable of breaking down biomolecules. The lysosomal membrane bilayer confines the pH-sensitive enzymes within an optimal acidic (pH 4.8) environment thereby protecting the slightly basic cytosol (pH 6.8-7.5). In the current study, we have probed the effect of LtxA-induced cytolysis on lysosomal integrity in two different K562 erythroleukemia cell lines. K562-puro/LFA-1 cells were stably transfected with CD11a and CD18 cDNA to express LFA-1 on the cell surface while K562-puro, which does not express LFA-1, served as a control. Following treatment with 100 ng ml(-1) LtxA cells were analyzed by live cell imaging in conjunction with time-lapse confocal microscopy and by flow cytometry. Using a pH-sensitive indicator (pHrodo(®)) we demonstrated that the toxin causes a decrease in the intracellular pH in K562-puro/LFA-1 cells that is noticeable within the first 15 min of treatment. This process correlated with the disappearance of lysosomes in the cytosol as determined by both acridine orange and LysoTracker(®) Red DND-99 staining. These changes were not observed in K562-puro cells or when heat inactivated toxin was added to K562-puro/LFA-1. Our results suggest that LtxA induces lysosomal damage, cytosol acidification, which is followed by cell death in K562-puro/LFA-1 cells.

  11. Alteration of Homeostasis in Pre-osteoclasts Induced by Aggregatibacter actinomycetemcomitans CDT

    PubMed Central

    Kawamoto, Dione; Ando-Suguimoto, Ellen S.; Bueno-Silva, Bruno; DiRienzo, Joseph M.; Mayer, Marcia P. A.

    2016-01-01

    The dysbiotic microbiota associated with aggressive periodontitis includes Aggregatibacter actinomycetemcomitans, the only oral species known to produce a cytolethal distending toxin (AaCDT). Give that CDT alters the cytokine profile in monocytic cells, we aimed to test the hypothesis that CDT plays a role in bone homeostasis by affecting the differentiation of precursor cells into osteoclasts. Recombinant AaCDT was added to murine bone marrow monocytes (BMMC) in the presence or absence of RANKL and the cell viability and cytokine profile of osteoclast precursor cells were determined. Multinucleated TRAP+ cell numbers, and relative transcription of genes related to osteoclastogenesis were also evaluated. The addition of AaCDT did not lead to loss in cell viability but promoted an increase in the average number of TRAP+ cells with 1-2 nuclei in the absence or presence of RANKL (Tukey, p < 0.05). This increase was also observed for TRAP+ cells with ≥3nuclei, although this difference was not significant. Levels of TGF-β, TNF-α, and IL-6, in the supernatant fraction of cells, were higher when in AaCDT exposed cells, whereas levels of IL-1β and IL-10 were lower than controls under the same conditions. After interaction with AaCDT, transcription of the rank (encoding the receptor RANK), nfatc1 (transcription factor), and ctpK (encoding cathepsin K) genes was downregulated in pre-osteoclastic cells. The data indicated that despite the presence of RANKL and M-CSF, AaCDT may inhibit osteoclast differentiation by altering cytokine profiles and repressing transcription of genes involved in osteoclastogenesis. Therefore, the CDT may impair host defense mechanisms in periodontitis. PMID:27064424

  12. Occurrence of Aggregatibacter actinomycetemcomitans in Indian chronic periodontitis patients and periodontally healthy adults

    PubMed Central

    Joshi, Vinayak Mahableshwar; Bhat, Kishore Gajanan; Kugaji, Manohar Suresh; Ingalgi, Preeti Shivaji

    2016-01-01

    Background: Aggregatibacter actinomycetemcomitans (Aa), an important primary periodontal pathogen, is known for its strong virulence characteristics that cause periodontal disease. We investigated Aa occurrence in Indian individuals using culture and 16 s rDNA polymerase chain reaction (PCR). Materials and Methods: A cross-sectional study with 100 participants each in the healthy and chronic periodontitis (CP) groups was conducted. The subgingival plaque was collected and immediately plated on selective media for Aa. The remaining plaque samples were used for DNA extraction. PCR was performed using specific primers for Aa. Statistical Analysis Used: The detection of bacteria and the clinical parameters between the groups were compared using the Mann–Whitney U-test. For assessing the agreement between the results of anaerobic culture and PCR, Kappa analyses were performed. Results: Aa levels using culture and PCR was 51% and 69% in the CP group and 12% and 30% in the healthy group, respectively. The two groups showed significant differences (P < 0.00001). The detection accuracy of culture and PCR was assessed, and the coefficient of accuracy (k) was highly significant in the healthy (0.3103; P < 0.0001) and CP groups (0.1536; P < 0.0497). Conclusions: Aa was predominantly found in the CP group compared with the healthy group, which is consistent with previous findings. Our results showed that both techniques can be used for detecting Aa. An ideal technique for detecting subgingival microorganisms should be carefully selected depending on the scope of the intended future work. PMID:27143824

  13. Aggregatibacter actinomycetemcomitans leukotoxin induces cytosol acidification in LFA-1 expressing immune cells

    PubMed Central

    Balashova, Nataliya; Dhingra, Anuradha; Boesze-Battaglia, Kathleen; Lally, Edward T.

    2015-01-01

    Summary Studies have suggested that Aggregatibacter actinomycetemcomitans leukotoxin (LtxA) kills human LFA-1(CD11a/CD18)-bearing immune cells through a lysosomal-mediated mechanism. Lysosomes are membrane-bound cellular organelles that contain an array of acid hydrolases that are capable of breaking down biomolecules. The lysosomal membrane bilayer confines the pH-sensitive enzymes within an optimal acidic (pH 4.8) environment thereby protecting the slightly basic cytosol (pH 6.8–7.5). In the current study, we have probed the effect of LtxA-induced cytolysis on lysosomal integrity in two different K562 erythroleukemia cell lines. K562-puro/LFA-1 cells were stably transfected with CD11a and CD18 cDNA to express LFA-1 on the cell surface while K562-puro, which does not express LFA-1, served as a control. Following treatment with 100 ng/ml LtxA cells were analyzed by live cell imaging in conjunction with time-lapse confocal microscopy and by flow cytometry. Using a pH sensitive indicator (pHrodo®, Life Technologies) we demonstrated that the toxin causes a decrease in the intracellular pH in K562-puro/LFA-1 cells noticeable within the first 15 min of treatment. This process correlated with the disappearance of lysosomes in the cytosol as determined by both acridine orange and LysoTracker® Red DND-99 (Life Technologies) staining. These changes were not observed in K562-puro cells or when heat inactivated toxin was added to K562-puro/LFA-1. Our results suggest that LtxA induces lysosomal damage, cytosol acidification, which is followed by cell death in K562-puro/LFA-1 cells. PMID:26361372

  14. Photocatalytical Antibacterial Activity of Mixed-Phase TiO2 Nanocomposite Thin Films against Aggregatibacter actinomycetemcomitans.

    PubMed

    Yeniyol, Sinem; Mutlu, Ilven; He, Zhiming; Yüksel, Behiye; Boylan, Robert Joseph; Ürgen, Mustafa; Karabuda, Zihni Cüneyt; Basegmez, Cansu; Ricci, John Lawrence

    2015-01-01

    Mixed-phase TiO2 nanocomposite thin films consisting of anatase and rutile prepared on commercially pure Ti sheets via the electrochemical anodization and annealing treatments were investigated in terms of their photocatalytic activity for antibacterial use around dental implants. The resulting films were characterized by scanning electron microscopy (SEM), and X-ray diffraction (XRD). The topology was assessed by White Light Optical Profiling (WLOP) in the Vertical Scanning Interferometer (VSI) mode. Representative height descriptive parameters of roughness R a and R z were calculated. The photocatalytic activity of the resulting TiO2 films was evaluated by the photodegradation of Rhodamine B (RhB) dye solution. The antibacterial ability of the photocatalyst was examined by Aggregatibacter actinomycetemcomitans suspensions in a colony-forming assay. XRD showed that anatase/rutile mixed-phase TiO2 thin films were predominantly in anatase and rutile that were 54.6 wt% and 41.9 wt%, respectively. Craters (2-5 µm) and protruding hills (10-50 µm) on Ti substrates were produced after electrochemical anodization with higher R a and R z surface roughness values. Anatase/rutile mixed-phase TiO2 thin films showed 26% photocatalytic decolorization toward RhB dye solution. The number of colonizing bacteria on anatase/rutile mixed-phase TiO2 thin films was decreased significantly in vitro. The photocatalyst was effective against A. actinomycetemcomitans colonization.

  15. Photocatalytical Antibacterial Activity of Mixed-Phase TiO2 Nanocomposite Thin Films against Aggregatibacter actinomycetemcomitans

    PubMed Central

    Yeniyol, Sinem; Mutlu, Ilven; He, Zhiming; Yüksel, Behiye; Boylan, Robert Joseph; Ürgen, Mustafa; Karabuda, Zihni Cüneyt; Basegmez, Cansu; Ricci, John Lawrence

    2015-01-01

    Mixed-phase TiO2 nanocomposite thin films consisting of anatase and rutile prepared on commercially pure Ti sheets via the electrochemical anodization and annealing treatments were investigated in terms of their photocatalytic activity for antibacterial use around dental implants. The resulting films were characterized by scanning electron microscopy (SEM), and X-ray diffraction (XRD). The topology was assessed by White Light Optical Profiling (WLOP) in the Vertical Scanning Interferometer (VSI) mode. Representative height descriptive parameters of roughness Ra and Rz were calculated. The photocatalytic activity of the resulting TiO2 films was evaluated by the photodegradation of Rhodamine B (RhB) dye solution. The antibacterial ability of the photocatalyst was examined by  Aggregatibacter actinomycetemcomitans suspensions in a colony-forming assay. XRD showed that anatase/rutile mixed-phase TiO2 thin films were predominantly in anatase and rutile that were 54.6 wt% and 41.9 wt%, respectively. Craters (2–5 µm) and protruding hills (10–50 µm) on Ti substrates were produced after electrochemical anodization with higher Ra and Rz surface roughness values. Anatase/rutile mixed-phase TiO2 thin films showed 26% photocatalytic decolorization toward RhB dye solution. The number of colonizing bacteria on anatase/rutile mixed-phase TiO2 thin films was decreased significantly in vitro. The photocatalyst was effective against A. actinomycetemcomitans colonization. PMID:26576430

  16. Mlc is a transcriptional activator with a key role in integrating cyclic AMP receptor protein and integration host factor regulation of leukotoxin RNA synthesis in Aggregatibacter actinomycetemcomitans

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aggregatibacter actinomycetemcomitans, a periodontal pathogen, synthesizes leukotoxin (LtxA), a protein that helps the bacterium evade the host immune response. Transcription of the ltxA operon is induced during anaerobic growth. The cAMP receptor protein (CRP) indirectly increases ltxA expression...

  17. Improving succinic acid production by Actinobacillus succinogenes from raw industrial carob pods.

    PubMed

    Carvalho, Margarida; Roca, Christophe; Reis, Maria A M

    2016-10-01

    Carob pods are an inexpensive by-product of locust bean gum industry that can be used as renewable feedstock for bio-based succinic acid. Here, for the first time, unprocessed raw carob pods were used to extract a highly enriched sugar solution, afterwards used as substrate to produce succinic acid using Actinobacillus succinogenes. Batch fermentations containing 30g/L sugars resulted in a production rate of 1.67gSA/L.h and a yield of 0.39gSA/g sugars. Taking advantage of A. succinogenes' metabolism, uncoupling cell growth from succinic acid production, a fed-batch mode was implemented to increase succinic acid yield and reduce by-products formation. This strategy resulted in a succinic acid yield of 0.94gSA/g sugars, the highest yield reported in the literature for fed-batch and continuous experiments, while maintaining by-products at residual values. Results demonstrate that raw carob pods are a highly efficient feedstock for bio-based succinic acid production.

  18. Carob pod water extracts as feedstock for succinic acid production by Actinobacillus succinogenes 130Z.

    PubMed

    Carvalho, Margarida; Roca, Christophe; Reis, Maria A M

    2014-10-01

    Carob pods are a by-product of locust bean gum industry containing more than 50% (w/w) sucrose, glucose and fructose. In this work, carob pod water extracts were used, for the first time, for succinic acid production by Actinobacillus succinogenes 130Z. Kinetic studies of glucose, fructose and sucrose consumption as individual carbon sources till 30g/L showed no inhibition on cell growth, sugar consumption and SA production rates. Sugar extraction from carob pods was optimized varying solid/liquid ratio and extraction time, maximizing sugar recovery while minimizing the extraction of polyphenols. Batch fermentations containing 10-15g/L total sugars resulted in a maximum specific SA production rate of 0.61Cmol/Cmol X.h, with a yield of 0.55Cmol SA/Cmol sugar and a volumetric productivity of 1.61g SA/L.h. Results demonstrate that carob pods can be a promising low cost feedstock for bio-based SA production.

  19. Identification of Actinobacillus pleuropneumoniae biovars 1 and 2 in pigs using a PCR assay.

    PubMed

    Serrano-Rubio, Luis E; Tenorio-Gutiérrez, Víctor; Suárez-Güemes, Francisco; Reyes-Cortés, Ruth; Rodríguez-Mendiola, Martha; Arias-Castro, Carlos; Godínez-Vargas, Delfino; de la Garza, Mireya

    2008-01-01

    Actinobacillus pleuropneumoniae causes swine pleuropneumonia worldwide. Previously, we described a gene sequence of approximately 800bp in A. pleuropneumoniae serotype 1 that encodes a metalloprotease of 24kDa, (Genbank accession no. AY217757). We selected primers carrying the forward and reverse 5'-terminal sequences of this region of the gene for the development of a species-specific PCR assay. The primers amplified an 800bp sequence from isolated DNA and lysed bacteria of the 13 A. pleuropneumoniae biovar 1 serotypes, with the exception of subtype 1b. The primers also amplified the sequence in nasal secretion cultures from pigs with chronic and acute experimental pleuropneumonia. No PCR products were detected when A. pleuropneumoniae serotypes of biovar 2 were used. Internal primers from this gene sequence detected biovar 2 and subtype 1b, leading to the production of a 350bp PCR product. The primers did not amplify DNA from other related species from the Pasteurellaceae family. The 800bp PCR assay was sensitive in vitro, with a detection limit of 5.5pg of extracted DNA, and an average of 120CFU. The specificity and sensitivity of this PCR assay make it a useful method for the rapid identification and diagnosis of A. pleuropneumoniae.

  20. Galleria mellonella is an effective model to study Actinobacillus pleuropneumoniae infection.

    PubMed

    Pereira, Monalessa Fábia; Rossi, Ciro César; de Queiroz, Marisa Vieira; Martins, Gustavo Ferreira; Isaac, Clement; Bossé, Janine T; Li, Yanwen; Wren, Brendan W; Terra, Vanessa Sofia; Cuccui, Jon; Langford, Paul R; Bazzolli, Denise Mara Soares

    2015-02-01

    Actinobacillus pleuropneumoniae is responsible for swine pleuropneumonia, a respiratory disease that causes significant global economic loss. Its virulence depends on many factors, such as capsular polysaccharides, RTX toxins and iron-acquisition systems. Analysis of virulence may require easy-to-use models that approximate mammalian infection and avoid ethical issues. Here, we investigate the potential use of the wax moth Galleria mellonella as an informative model for A. pleuropneumoniae infection. Genotypically distinct A. pleuropneumoniae clinical isolates were able to kill larvae at 37 °C but had different LD50 values, ranging from 10(4) to 10(7) c.f.u. per larva. The most virulent isolate (1022) was able to persist and replicate within the insect, while the least virulent (780) was rapidly cleared. We observed a decrease in haemocyte concentration, aggregation and DNA damage post-infection with isolate 1022. Melanization points around bacterial cells were observed in the fat body and pericardial tissues of infected G. mellonella, indicating vigorous cell and humoral immune responses close to the larval dorsal vessel. As found in pigs, an A. pleuropneumoniae hfq mutant was significantly attenuated for infection in the G. mellonella model. Additionally, the model could be used to assess the effectiveness of several antimicrobial agents against A. pleuropneumoniae in vivo. G. mellonella is a suitable inexpensive alternative infection model that can be used to study the virulence of A. pleuropneumoniae, as well as assess the effectiveness of antimicrobial agents against this pathogen.

  1. Succinic acid production with Actinobacillus succinogenes ZT-130 in the presence of succinic acid.

    PubMed

    Corona-Gonzalez, Rosa Isela; Bories, Andre; González-Alvarez, Víctor; Snell-Castro, Raul; Toriz-González, Guillermo; Pelayo-Ortiz, Carlos

    2010-01-01

    Glucose fermentation with Actinobacillus succinogenes was carried out at different initial concentrations of succinic acid (SA(0)) to determine its effect on growth and on the production of succinic acid itself. The specific rates of biomass production, succinic, formic and acetic acids decreased with SA(0) (0-40 g/l). The partially dissociated form of succinic acid had a higher effect on cell growth and production of succinic acid as compared to the non-dissociated forms of the acids, a fact that has not been reported until now. Cell growth fitted the Jerusalimski model, and the Aiba-Shoda model was suitable for quantification of the inhibition for the production of succinic acid. The growth inhibition constants K(is) and K(ip) and their summatory were consistent with the experimental values obtained, i.e., 22 g/l for the produced acids and 38 g/l for total acids that were the limits at which the biomass formation ceased.

  2. Immobilization of Actinobacillus succinogenes by adhesion or entrapment for the production of succinic acid.

    PubMed

    Corona-González, Rosa Isela; Miramontes-Murillo, Ricardo; Arriola-Guevara, Enrique; Guatemala-Morales, Guadalupe; Toriz, Guillermo; Pelayo-Ortiz, Carlos

    2014-07-01

    The production of succinic acid was studied with entrapped and adsorbed Actinobacillus succinogenes. The adsorption of fermentation products (organic acids in the concentration range of 1-20 g/L) on different supports was evaluated. It was found that succinic acid was adsorbed in small quantities on diatomite and zeolite (12.6 mg/g support). The highest production of succinic acid was achieved with A. succinogenes entrapped in agar beads. Batch fermentations with immobilized cells were carried out with glucose concentrations ranging from 20 to 80 g/L. Succinic acid (43.4 g/L) was obtained from 78.3g/L glucose, and a high productivity (2.83 g/Lh) was obtained with a glucose concentration of 37.6g/L. For repeated batch fermentations (5 cycles in 72 h) with immobilized cells in agar, the total glucose consumed was 147.55 g/L, while the production of succinic acid was 107 g/L. Immobilized cells reduced significantly the fermentation time, yield, productivity and final concentration of succinic acid.

  3. Renaturation and purification of ApxII toxin of Actinobacillus pleuropneumoniae.

    PubMed

    Wang, Chunlai; Liu, Siguo; Peng, Yonggang; Shao, Meili; Wang, Yong; Gong, Qiang; Chang, Yuehong; Liu, Jiandong; Liu, Huifang; Liu, Di; Kong, Xiangang

    2007-04-01

    ApxII toxin is the only Apx toxin that is produced by Actinobacillus pleuropneumoniae serotype 7. In order to determine whether the recombinant ApxII that derived from Escherichia coli (E. coli) expression is faithful to the natural ApxII so that can be used as additional component in vaccine preparation, the structure gene apxIIA of ApxII toxin was expressed in E. coli with prokaryotic expression vector pGEX-6p-1 (formed pGEX-6p-A). pGZRS-C which is A. pleuropneumoniae-E. coli shuttle vector pGZRS-38 expressing the post-transcriptional activation gene apxII C was co-expressed with pGEX-6p-A. The expression product of rApxII A formed inclusion. The inclusion protein was oxidized, refolded and restored hemolytic activity after denaturation, renaturation and purification. The result indicated that E. coli expressed recombinant ApxII toxin has good fidelity, which makes it possible to produce this valuable antigen for vaccine preparation or diagnosis.

  4. CO2 Biofixation of Actinobacillus succinogenes Through Novel Amine-Functionalized Polystyrene Microsphere Materials.

    PubMed

    Zhu, Wenhao; Li, Qiang; Dai, Ning

    2017-02-01

    CO2-derived succinate production was enhanced by Actinobacillus succinogenes through polystyrene (PSt) microsphere materials for CO2 adsorption in bioreactor, and the adhesion forces between A. succinogenes bacteria and PSt materials were characterized. Synthesized uniformly sized and highly cross-linked PSt microspheres had high specific surface areas. After modification with amine functional groups, the novel amine-functionalized PSt microspheres exhibited a high adsorption capacity of 25.3 mg CO2/g materials. After addition with the functionalized microspheres into the culture broth, CO2 supply to the cells increased. Succinate production by A. succinogenes can be enhanced from 29.6 to 48.1 g L(-1). Moreover, the characterization of interaction forces between A. succinogenes cells and the microspheres indicated that the maximal adhesive force was about 250 pN. The amine-functionalized PSt microspheres can adsorb a large amount of CO2 and be employed for A. succinogenes anaerobic cultivation in bioreactor for high-efficiency production of CO2-derived succinate.

  5. Production and immunogenicity of Actinobacillus pleuropneumoniae ApxIIA protein in transgenic rice callus.

    PubMed

    Kim, Mi-Young; Kim, Tae-Geum; Yang, Moon-Sik

    2017-04-01

    Actinobacillus pleuropneumoniae is a major etiological agent that is responsible for swine pleuropneumonia, a highly contagious respiratory infection that causes severe economic losses in the swine production industry. ApxIIA is one of the virulence factors in A. pleuropneumoniae and has been considered as a candidate for developing a vaccine against the bacterial infection. A gene encoding an ApxIIA fragment (amino acids 439-801) was modified based on a plant-optimized codon and constructed into a plant expression vector under the control of a promoter and the 3' UTR of the rice amylase 3D gene. The plant expression vector was introduced into rice embryogenic callus (Oryza sativa L. cv. Dongjin) via particle bombardment-mediated transformation. The integration and transcription of the ApxIIA439-801 gene were confirmed by using genomic DNA PCR amplification and Northern blot analysis, respectively. The synthesis of ApxIIA439-801 antigen protein in transgenic rice callus was confirmed by western blot analysis. The concentration of antigen protein in lyophilized samples of transgenic rice callus was 250 μg/g. Immunizing mice with protein extracts from transgenic plants intranasally elicited secretory IgA. These results demonstrate the feasibility of using a transgenic plant to elicit immune responses against A. pleuropneumoniae.

  6. Succinic Acid Production from Cheese Whey using Actinobacillus succinogenes 130 Z

    NASA Astrophysics Data System (ADS)

    Wan, Caixia; Li, Yebo; Shahbazi, Abolghasem; Xiu, Shuangning

    Actinobacillus succinogenes 130 Z was used to produce succinic acid from cheese whey in this study. At the presence of external CO2 supply, the effects of initial cheese whey concentration, pH, and inoculum size on the succinic acid production were studied. The by-product formation during the fermentation process was also analyzed. The highest succinic acid yield of 0.57 was obtained at initial cheese whey concentration of 50 g/L, while the highest succinic acid productivity of 0.58 g h-1 L-1 was obtained at initial cheese whey concentration of 100 g/L. Increase in pH and inoculum size caused higher succinic acid yield and productivity. At the preferred fermentation condition of pH 6.8, inoculum size of 5% and initial cheese whey concentration of 50 g/L, succinic acid yield of 0.57, and productivity of 0.44 g h-1 L-1 were obtained. Acetic acid and formic acid were the main by-products throughout the fermentation run of 48 h. It is feasible to produce succinic acid using lactose from cheese whey as carbon resource by A. succinogenes 130 Z.

  7. Secreted proteases from Actinobacillus pleuropneumoniae serotype 1 degrade porcine gelatin, hemoglobin and immunoglobulin A.

    PubMed Central

    Negrete-Abascal, E; Tenorio, V R; Serrano, J J; Garcia, C; de la Garza, M

    1994-01-01

    It was found that 48 hour cultures of Actinobacillus pleuropneumoniae secreted proteases into the medium. Electrophoresis in polyacrylamide gels (10%) copolymerized with porcine gelatin (0.1%), of the 70% (NH4)2SO4 precipitate from the culture supernatants, displayed protease activities of different molecular weights: > 200, 200, 90, 80, 70 and 50 kDa. They had activity over a broad range of pHs (4-8), with an optimal pH of 6-7. All were inhibited by 10 mM EDTA, and reactivated by 10 mM calcium. They were stable at -20 degrees C for more than a month. The proteases also degraded porcine IgA and porcine, human, and bovine hemoglobin, although they appeared to be less active against the hemoglobins. The IgA was totally cleaved in 48 h, using supernatants concentrated with polyvinyl pyrrolidone or the 70% (NH4)2SO4. Extracellular proteases could play a role in virulence. Images Fig. 1. Fig. 2. Fig. 3. Fig. 4. PMID:8004545

  8. [Optimization of succinic acid fermentation with Actinobacillus succinogenes by response surface methodology].

    PubMed

    Shen, Naikun; Qin, Yan; Wang, Qingyan; Xie, Nengzhong; Mi, Huizhi; Zhu, Qixia; Liao, Siming; Huang, Ribo

    2013-10-01

    Succinic acid is an important C4 platform chemical in the synthesis of many commodity and special chemicals. In the present work, different compounds were evaluated for succinic acid production by Actinobacillus succinogenes GXAS 137. Important parameters were screened by the single factor experiment and Plackeet-Burman design. Subsequently, the highest production of succinic acid was approached by the path of steepest ascent. Then, the optimum values of the parameters were obtained by Box-Behnken design. The results show that the important parameters were glucose, yeast extract and MgCO3 concentrations. The optimum condition was as follows (g/L): glucose 70.00, yeast extract 9.20 and MgCO3 58.10. Succinic acid yield reached 47.64 g/L at the optimal condition. Succinic acid increased by 29.14% than that before the optimization (36.89 g/L). Response surface methodology was proven to be a powerful tool to optimize succinic acid production.

  9. Succinic acid production by Actinobacillus succinogenes using hydrolysates of spent yeast cells and corn fiber.

    PubMed

    Chen, Ke-Quan; Li, Jian; Ma, Jiang-Feng; Jiang, Min; Wei, Ping; Liu, Zhong-Min; Ying, Han-Jie

    2011-01-01

    The enzymatic hydrolysate of spent yeast cells was evaluated as a nitrogen source for succinic acid production by Actinobacillus succinogenes NJ113, using corn fiber hydrolysate as a carbon source. When spent yeast cell hydrolysate was used directly as a nitrogen source, a maximum succinic acid concentration of 35.5 g/l was obtained from a glucose concentration of 50 g/l, with a glucose utilization of 95.2%. Supplementation with individual vitamins showed that biotin was the most likely factor to be limiting for succinic acid production with spent yeast cell hydrolysate. After supplementing spent yeast cell hydrolysate and 90 g/l of glucose with 150 μg/l of biotin, cell growth increased 32.5%, glucose utilization increased 37.6%, and succinic acid concentration was enhanced 49.0%. As a result, when biotin-supplemented spent yeast cell hydrolysate was used with corn fiber hydrolysate, a succinic acid yield of 67.7% was obtained from 70.3 g/l of total sugar concentration, with a productivity of 0.63 g/(l h). Our results suggest that biotin-supplemented spent yeast cell hydrolysate may be an alternative nitrogen source for the efficient production of succinic acid by A. succinogenes NJ113, using renewable resources.

  10. Inverse Association of Plasma IgG Antibody to Aggregatibacter actinomycetemcomitans and High C-Reactive Protein Levels in Patients with Metabolic Syndrome and Periodontitis.

    PubMed

    Thanakun, Supanee; Pornprasertsuk-Damrongsri, Suchaya; Gokyu, Misa; Kobayashi, Hiroaki; Izumi, Yuichi

    2016-01-01

    The association between clinically diagnosed periodontitis, a common chronic oral infection, and metabolic syndrome has been previously reported. The aim of this study was to investigate the association of plasma IgG levels against Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, and Prevotella intermedia, C-reactive protein, and periodontal status with metabolic syndrome. Plasma IgG levels and C-reactive protein were measured by enzyme-linked immunosorbent assay, and salivary levels of A. actinomycetemcomitans and P. gingivalis were determined by quantitative real-time polymerase chain reaction. Among 127 individuals aged 35-76 years, 57 participants had metabolic syndrome and severe periodontitis, 25 had metabolic syndrome and an absence of severe periodontitis, 17 healthy individuals had severe periodontitis, and 28 healthy individuals were without severe periodontitis. Patients with metabolic syndrome had reduced humoral immune response to A. actinomycetemcomitans (p = 0.008), regardless of their salivary levels or periodontitis status compared with healthy participants. The IgG antibody response to P. gingivalis, regardless of their salivary levels or participants' health condition, was significantly higher in severe periodontitis patients (p<0.001). Plasma IgG titers for P. intermedia were inconsistent among metabolic syndrome or periodontal participants. Our results indicate that the presence of lower levels of IgG antibodies to A. actinomycetemcomitans (OR = 0.1; 95%CI 0.0-0.7), but not P. gingivalis, a severe periodontitis status (OR = 7.8; 95%CI 1.1-57.0), high C-reactive protein levels (OR = 9.4; 95%CI 1.0-88.2) and body mass index (OR = 3.0; 95%CI 1.7-5.2), are associated with the presence of metabolic syndrome. The role of the decreased IgG antibody response to A. actinomycetemcomitans, increased C-reactive protein levels on the association between periodontal disease and metabolic syndrome in a group of Thai patients is suggested.

  11. Al(III), Pd(II), and Zn(II) phthalocyanines for inactivation of dental pathogen Aggregatibacter actinomycetemcomitans as planktonic and biofilm-cultures

    NASA Astrophysics Data System (ADS)

    Kussovski, V.; Mantareva, V.; Angelov, I.; Avramov, L.; Popova, E.; Dimitrov, S.

    2012-06-01

    The Gram-negative, oral bacterium Aggregatibacter actinomycetemcomitans has been implicated as the causative agent of several forms of periodontal disease in humans. The new periodontal disease treatments are emergence in order to prevent infection progression. Antimicrobial photodynamic therapy (a-PDT) can be a useful tool for this purpose. It involves the use of light of specific wavelength to activate a nontoxic photosensitizing agent in the presence of oxygen for eradication of target cells, and appears effective in photoinactivation of microorganisms. The phthalocyanine metal complexes of Pd(II)- (PdPcC) and Al(III)- (AlPc1) were evaluated as photodynamic sensitizers towards a dental pathogen A. actinomycetemcomitans in comparison to the known methylpyridyloxy-substituted Zn(II) phthalocyanine (ZnPcMe). The planktonic and biofilm-cultivated species of A. actinomycetemcomitans were treated. The photophysical results showed intensive and far-red absorbance with high tendency of aggregation for Pd(II)-phthalocyanine. The dark toxicities of both photosensitizers were negligible at concentrations used (< 0.5 log decrease of viable cells). The photodynamic response for planktonic cultured bacteria was full photoinactivation after a-PDT with ZnPcMe. In case of the newly studied complexes, the effect was lower for PdPcC (4 log) as well as for AlPc1 (1.5-2 log). As it is known the bacterial biofilms were more resistant to a-PDT, which was confirmed for A. actinomycetemcomitans biofilms with 3 log reductions of viable cells after treatment with ZnPcMe and approximately 1 log reduction of biofilms after PdPcC and AlPc1. The initial results suggest that a-PDT can be useful for effective inactivation of dental pathogen A. actinomycetemcomitans.

  12. Aggregatibacter actinomycetemcomitans QseBC is activated by catecholamines and iron and regulates genes encoding proteins associated with anaerobic respiration and metabolism

    PubMed Central

    Weigel, WA; Demuth, DR; Torres-Escobar, A; Juárez-Rodríguez, MD

    2015-01-01

    Aggregatibacter actinomycetemcomitans QseBC regulates its own expression and is essential for biofilm growth and virulence. However, the signal that activates the QseC sensor has not been identified and the qseBC regulon has not been defined. In this study, we show that QseC is activated by catecholamine hormones and iron but not by either component alone. Activation of QseC requires an EYRDD motif in the periplasmic domain of the sensor and site-specific mutations in EYRDD or the deletion of the periplasmic domain inhibits catecholamine/iron-dependent induction of the ygiW-qseBC operon. Catecholamine/iron-dependent induction of transcription also requires interaction of the QseB response regulator with its binding site in the ygiW-qseBC promoter. Whole genome microarrays were used to compare gene expression profiles of A. actinomycetemcomitans grown in a chemically defined medium with and without catecholamine and iron supplementation. Approximately 11.5% of the A. actinomycetemcomitans genome was differentially expressed by at least two-fold upon exposure to catecholamines and iron. The expression of ferritin was strongly induced, suggesting that intracellular iron storage capacity is increased upon QseBC activation. Consistent with this, genes encoding iron binding and transport proteins were down-regulated by QseBC. Strikingly, 57% of the QseBC up-regulated genes (56/99) encode proteins associated with anaerobic metabolism and respiration. Most of these up-regulated genes were recently reported to be induced during in vivo growth of A. actinomycetemcomitans. These results suggest that detection of catecholamines and iron by QseBC may alter the cellular metabolism of A. actinomycetemcomitans for increased fitness and growth in an anaerobic host environment. PMID:25923132

  13. Inactivation of Aggregatibacter actinomycetemcomitans by two different modalities of photodynamic therapy using Toluidine blue O or Radachlorin as photosensitizers: an in vitro study.

    PubMed

    Moslemi, Neda; Soleiman-Zadeh Azar, Pardis; Bahador, Abbas; Rouzmeh, Nina; Chiniforush, Nasim; Paknejad, Mojgan; Fekrazad, Reza

    2015-01-01

    Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans) is one of the periodontopathogens strongly associated with aggressive periodontitis. The aim of this investigation was to compare the effect of laser and light-emitting diode on the photodynamic inactivation of A. actinomycetemcomitans. Eighty-four samples of bacterial suspensions (200 μL) were prepared and divided in seven groups: control group (no treatment), laser group (indium-gallium-aluminum-phosphate laser with wavelength of 662 ± 0.1 nm, energy density of 6 j/cm(2), and irradiation time of 34 s), light-emitting diode (LED) group (wavelength 625-635 nm, energy density 6 j/cm(2), time of irradiation 30 s), Toluidine blue O (TBO) group (0.1 mg/mL), Radachlorin group (0.1 %), Radachlorin + laser group (after pre-irradiation time of 10 min, laser was irradiated), and TBO + LED group (after preirradiation time of 10 min, LED was irradiated). Then, 100 μL of each sample was cultured in brain heart infusion (BHI) plates and incubated for 48-72 h in microaerophilic atmosphere for colony counting. Application of Radachlorin + laser resulted in a significant decrease in the concentration of A. actinomycetemcomitans (P values <0.05). Photodynamic therapy with laser + Radachlorin was more effective than that of LED + TBO in suppression of this microorganism (P value <0.05). Within the limits of this study, it can be concluded that photodynamic inactivation using laser and Radachlorin was more effective than that of LED and TBO in eradication of A. actinomycetemcomitans.

  14. Aggregatibacter actinomycetemcomitans QseBC is activated by catecholamines and iron and regulates genes encoding proteins associated with anaerobic respiration and metabolism.

    PubMed

    Weigel, W A; Demuth, D R; Torres-Escobar, A; Juárez-Rodríguez, M D

    2015-10-01

    Aggregatibacter actinomycetemcomitans QseBC regulates its own expression and is essential for biofilm growth and virulence. However, the signal that activates the QseC sensor has not been identified and the qseBC regulon has not been defined. In this study, we show that QseC is activated by catecholamine hormones and iron but not by either component alone. Activation of QseC requires an EYRDD motif in the periplasmic domain of the sensor and site-specific mutations in EYRDD or the deletion of the periplasmic domain inhibits catecholamine/iron-dependent induction of the ygiW-qseBC operon. Catecholamine/iron-dependent induction of transcription also requires interaction of the QseB response regulator with its binding site in the ygiW-qseBC promoter. Whole genome microarrays were used to compare gene expression profiles of A. actinomycetemcomitans grown in a chemically defined medium with and without catecholamine and iron supplementation. Approximately 11.5% of the A. actinomycetemcomitans genome was differentially expressed by at least two-fold upon exposure to catecholamines and iron. The expression of ferritin was strongly induced, suggesting that intracellular iron storage capacity is increased upon QseBC activation. Consistent with this, genes encoding iron binding and transport proteins were down-regulated by QseBC. Strikingly, 57% of the QseBC up-regulated genes (56/99) encode proteins associated with anaerobic metabolism and respiration. Most of these up-regulated genes were recently reported to be induced during in vivo growth of A. actinomycetemcomitans. These results suggest that detection of catecholamines and iron by QseBC may alter the cellular metabolism of A. actinomycetemcomitans for increased fitness and growth in an anaerobic host environment.

  15. ygiW and qseBC are co-expressed in Aggregatibacter actinomycetemcomitans and regulate biofilm growth.

    PubMed

    Juárez-Rodríguez, María Dolores; Torres-Escobar, Ascención; Demuth, Donald R

    2013-06-01

    The quorum-sensing Escherichia coli regulators B and C (QseBC) two-component system were previously shown to regulate biofilm growth of the oral pathogen Aggregatibacter actinomycetemcomitans and to be essential for virulence. In this study, we use RT-PCR to show that an open reading frame, ygiW, residing upstream of qseBC and encoding a hypothetical protein is co-expressed with qseBC. In addition, using a series of lacZ transcriptional fusion constructs and 5'-rapid amplification of cDNA Ends (RACE), the promoter that drives expression of the ygiW-qseBC operon and the transcriptional start site was mapped to the 372 bp intergenic region upstream from ygiW. No internal promoters drive qseBC expression independently from ygiW. However, qseBC expression is attenuated by approximately ninefold by a putative attenuator stem-loop (ΔG = -77.0 KJ/mol) that resides in the 137 bp intergenic region between ygiW and qseB. The QseB response regulator activates expression of the ygiW-qseBC operon and transcription from the ygiW promoter is drastically reduced in ΔqseB and ΔqseBC mutants of A. actinomycetemcomitans. In addition, transcriptional activity of the ygiW promoter is significantly reduced in a mutant expressing an in-frame deletion of qseC that lacks the sensor domain of QseC, suggesting that a periplasmic signal is required for QseB activation. Finally, a non-polar in-frame deletion in ygiW had little effect on biofilm depth but caused a significant increase in surface coverage relative to wild-type. Complementation of the mutant with a plasmid-borne copy of ygiW reduced surface coverage back to wild-type levels. Interestingly, deletion of the sensor domain of QseC or of the entire qseC open reading frame resulted in significant reductions in biofilm depth, biomass and surface coverage, indicating that the sensor domain is essential for optimal biofilm formation by A. actinomycetemcomitans. Thus, although ygiW and qseBC are co-expressed, they regulate biofilm

  16. Structural analysis of the Actinobacillus pleuropneumoniae-RTX-toxin I (ApxI) operon.

    PubMed Central

    Jansen, R; Briaire, J; Kamp, E M; Gielkens, A L; Smits, M A

    1993-01-01

    Actinobacillus pleuropneumoniae-RTX-toxin I (ApxI), an important virulence factor, is secreted by serotypes 1, 5, 9, 10, and 11 of A. pleuropneumoniae. However, sequences homologous to the secretion genes apxIBD of the ApxI operon are present in all 12 serotypes except serotype 3. The purpose of this study was to determine and compare the structures of the ApxI operons of the 12 A. pleuropneumoniae serotypes. We focused on the nucleotide sequence comparison of the ApxI-coding genes, the structures of the ApxI operons, and the transcription of the ApxI operons. We determined the nucleotide sequences of the toxin-encoding apxICA genes of serotype 9 and found that the gene for the structural toxin, apxIA, was almost identical to the apxIA gene of serotype 1. The toxin-encoding genes of the other serotypes are also similar for the main part; nevertheless, two variants were identified, one in serotypes 1, 9, and 11 and one in serotypes 5 and 10. The two apxIA variants differ mainly within the distal 110 nucleotides. Structural analysis demonstrated that intact ApxI operons, consisting of the four contiguous genes apxICABD, are present in serotypes 1, 5, 9, 10, and 11. ApxI operons with a major deletion in the apxICA genes are present in serotypes 2, 4, 6, 7, 8, and 12. Serotype 3 does not contain ApxI operon sequences. We found that all ApxI operons are transcriptionally active despite the partial deletion of the operon in some serotypes. The implications of these data for the expression and secretion of ApxI and the other Apx-toxins, ApxII and ApxIII, as well as for the development of a subunit vaccine against A. pleuropneumoniae will be discussed. Images PMID:8359891

  17. A computational strategy for the search of regulatory small RNAs in Actinobacillus pleuropneumoniae

    PubMed Central

    Rossi, Ciro C.; Bossé, Janine T.; Li, Yanwen; Witney, Adam A.; Gould, Kate A.; Langford, Paul R.; Bazzolli, Denise M.S.

    2016-01-01

    Bacterial regulatory small RNAs (sRNAs) play important roles in gene regulation and are frequently connected to the expression of virulence factors in diverse bacteria. Only a few sRNAs have been described for Pasteurellaceae pathogens and no in-depth analysis of sRNAs has been described for Actinobacillus pleuropneumoniae, the causative agent of porcine pleuropneumonia, responsible for considerable losses in the swine industry. To search for sRNAs in A. pleuropneumoniae, we developed a strategy for the computational analysis of the bacterial genome by using four algorithms with different approaches, followed by experimental validation. The coding strand and expression of 17 out of 23 RNA candidates were confirmed by Northern blotting, RT-PCR, and RNA sequencing. Among them, two are likely riboswitches, three are housekeeping regulatory RNAs, two are the widely studied GcvB and 6S sRNAs, and 10 are putative novel trans-acting sRNAs, never before described for any bacteria. The latter group has several potential mRNA targets, many of which are involved with virulence, stress resistance, or metabolism, and connect the sRNAs in a complex gene regulatory network. The sRNAs identified are well conserved among the Pasteurellaceae that are evolutionarily closer to A. pleuropneumoniae and/or share the same host. Our results show that the combination of newly developed computational programs can be successfully utilized for the discovery of novel sRNAs and indicate an intricate system of gene regulation through sRNAs in A. pleuropneumoniae and in other Pasteurellaceae, thus providing clues for novel aspects of virulence that will be explored in further studies. PMID:27402897

  18. Succinic acid-producing biofilms of Actinobacillus succinogenes: reproducibility, stability and productivity.

    PubMed

    Maharaj, K; Bradfield, M F A; Nicol, W

    2014-09-01

    Continuous anaerobic fermentations were performed in a biofilm reactor packed with Poraver® beads. Dilution rates (D) varied between 0.054 and 0.72 h(-1), and D-glucose and CO2 gas were used as carbon substrates. Steady-state conditions were shown to be repeatable and independent of the operational history. Production stability was achieved over periods exceeding 80 h at values of D below 0.32 h(-1). In these situations, steady-state variation (expressed as fluctuations in NaOH neutralisation flow rates) exhibited a standard deviation of less than 5 % while no indication of biofilm deactivation was detected. The total biomass amount was found to be independent of the dilution rate with an average dry concentration of 23.8 ± 2.9 g L(-1) obtained for all runs. This suggests that the attachment area controls the extent of biofilm accumulation. Specific succinic acid (SA) productivities, based on the total biomass amount, exhibited a substantial decrease with decreasing D. An SA volumetric productivity of 10.8 g L(-1) h(-1) was obtained at D = 0.7 h(-1)-the highest value reported to date in Actinobacillus succinogenes fermentations. SA yields on glucose increased with decreasing D, with a yield of 0.90 ± 0.01 g g(-1) obtained at a D of 0.054 h(-1). Production of formic acid approached zero with decreasing D, while the succinic to acetic acid ratio increased with decreasing D, resulting in an increasing SA yield on glucose.

  19. Sub-inhibitory concentrations of penicillin G induce biofilm formation by field isolates of Actinobacillus pleuropneumoniae.

    PubMed

    Hathroubi, S; Fontaine-Gosselin, S-È; Tremblay, Y D N; Labrie, J; Jacques, M

    2015-09-30

    Actinobacillus pleuropneumoniae is a Gram-negative bacterium and causative agent of porcine pleuropneumonia. This is a highly contagious disease that causes important economic losses to the swine industry worldwide. Penicillins are extensively used in swine production and these antibiotics are associated with high systemic clearance and low oral bioavailability. This may expose A. pleuropneumoniae to sub-inhibitory concentrations of penicillin G when the antibiotic is administered orally. Our goal was to evaluate the effect of sub-minimum inhibitory concentration (MIC) of penicillin G on the biofilm formation of A. pleuropneumoniae. Biofilm production of 13 field isolates from serotypes 1, 5a, 7 and 15 was tested in the presence of sub-MIC of penicillin G using a polystyrene microtiter plate assay. Using microscopy techniques and enzymatic digestion, biofilm architecture and composition were also characterized after exposure to sub-MIC of penicillin G. Sub-MIC of penicillin G significantly induced biofilm formation of nine isolates. The penicillin G-induced biofilms contained more poly-N-acetyl-D-glucosamine (PGA), extracellular DNA and proteins when compared to control biofilms grown without penicillin G. Additionally, penicillin G-induced biofilms were sensitive to DNase which was not observed with the untreated controls. Furthermore, sub-MIC of penicillin G up-regulated the expression of pgaA, which encodes a protein involved in PGA synthesis, and the genes encoding the envelope-stress sensing two-component regulatory system CpxRA. In conclusion, sub-MICs of penicillin G significantly induce biofilm formation and this is likely the result of a cell envelope stress sensed by the CpxRA system resulting in an increased production of PGA and other matrix components.

  20. Actinobacillus hominis osteomyelitis: First reported case in the English language medical literature

    PubMed Central

    O’Neill, Gavin; Mohammed, Aslam; Karcher, Anne Marie

    2016-01-01

    Introduction: Actinobacillus hominis is currently a rarely reported pathogen. It has previously been associated with respiratory tract infections and bacteraemia in debilitated patients. However, under-reporting may occur due to misidentification by commonly used laboratory bacterial identification systems. This case is, to the best of our knowledge, the first reported case of A. hominis osteomyelitis in the English language medical literature. Case presentation: A 37-year-old male presented with a painful foot. He had no previous foot problems, history of injury or animal contact. Osteomyelitis was confirmed by magnetic resonance imaging (MRI), and blood cultures were positive for Gram-variable bacilli. The organism was identified initially as Pasteurella pneumotropica by the local routine diagnostic laboratory and as a Pasteurella species by the UK National Reference Laboratory (Colindale, London, UK), using standard operating procedures at the time. It was finally identified as an A. hominis using 16S rRNA gene sequence analysis. Difficulties in the accurate identification of this organism remain current, as other biochemical identification systems have also resulted in misidentifications. The patient refused admission and intravenous antibiotics. He was successfully treated using an 8-week course of oral ciprofloxacin and amoxicillin based on antibiotic disc susceptibility testing resulting in clinical, serological and radiological resolution. Conclusion: Laboratories should maintain a high index of suspicion for A. hominis as several commonly used bacterial identification systems may not accurately identify the organism. Colonial morphology and absence of animal contact should prompt consideration of this organism in appropriate clinical situations. Oral ciprofloxacin and amoxicillin treatment was successful in this case. PMID:28348754

  1. Actinobacillus pleuropneumoniae Possesses an Antiviral Activity against Porcine Reproductive and Respiratory Syndrome Virus

    PubMed Central

    Labrie, Josée; Hernandez Reyes, Yenney; Burciaga Nava, Jorge A.; Gagnon, Carl A.; Jacques, Mario

    2014-01-01

    Pigs are often colonized by more than one bacterial and/or viral species during respiratory tract infections. This phenomenon is known as the porcine respiratory disease complex (PRDC). Actinobacillus pleuropneumoniae (App) and porcine reproductive and respiratory syndrome virus (PRRSV) are pathogens that are frequently involved in PRDC. The main objective of this project was to study the in vitro interactions between these two pathogens and the host cells in the context of mixed infections. To fulfill this objective, PRRSV permissive cell lines such as MARC-145, SJPL, and porcine alveolar macrophages (PAM) were used. A pre-infection with PRRSV was performed at 0.5 multiplicity of infection (MOI) followed by an infection with App at 10 MOI. Bacterial adherence and cell death were compared. Results showed that PRRSV pre-infection did not affect bacterial adherence to the cells. PRRSV and App co-infection produced an additive cytotoxicity effect. Interestingly, a pre-infection of SJPL and PAM cells with App blocked completely PRRSV infection. Incubation of SJPL and PAM cells with an App cell-free culture supernatant is also sufficient to significantly block PRRSV infection. This antiviral activity is not due to LPS but rather by small molecular weight, heat-resistant App metabolites (<1 kDa). The antiviral activity was also observed in SJPL cells infected with swine influenza virus but to a much lower extent compared to PRRSV. More importantly, the PRRSV antiviral activity of App was also seen with PAM, the cells targeted by the virus in vivo during infection in pigs. The antiviral activity might be due, at least in part, to the production of interferon γ. The use of in vitro experimental models to study viral and bacterial co-infections will lead to a better understanding of the interactions between pathogens and their host cells, and could allow the development of novel prophylactic and therapeutic tools. PMID:24878741

  2. Whole Genome Sequencing for Surveillance of Antimicrobial Resistance in Actinobacillus pleuropneumoniae.

    PubMed

    Bossé, Janine T; Li, Yanwen; Rogers, Jon; Fernandez Crespo, Roberto; Li, Yinghui; Chaudhuri, Roy R; Holden, Matthew T G; Maskell, Duncan J; Tucker, Alexander W; Wren, Brendan W; Rycroft, Andrew N; Langford, Paul R

    2017-01-01

    The aim of this study was to evaluate the correlation between antimicrobial resistance (AMR) profiles of 96 clinical isolates of Actinobacillus pleuropneumoniae, an important porcine respiratory pathogen, and the identification of AMR genes in whole genome sequence (wgs) data. Susceptibility of the isolates to nine antimicrobial agents (ampicillin, enrofloxacin, erythromycin, florfenicol, sulfisoxazole, tetracycline, tilmicosin, trimethoprim, and tylosin) was determined by agar dilution susceptibility test. Except for the macrolides tested, elevated MICs were highly correlated to the presence of AMR genes identified in wgs data using ResFinder or BLASTn. Of the isolates tested, 57% were resistant to tetracycline [MIC ≥ 4 mg/L; 94.8% with either tet(B) or tet(H)]; 48% to sulfisoxazole (MIC ≥ 256 mg/L or DD = 6; 100% with sul2), 20% to ampicillin (MIC ≥ 4 mg/L; 100% with blaROB-1), 17% to trimethoprim (MIC ≥ 32 mg/L; 100% with dfrA14), and 6% to enrofloxacin (MIC ≥ 0.25 mg/L; 100% with GyrAS83F). Only 33% of the isolates did not have detectable AMR genes, and were sensitive by MICs for the antimicrobial agents tested. Although 23 isolates had MIC ≥ 32 mg/L for tylosin, all isolates had MIC ≤ 16 mg/L for both erythromycin and tilmicosin, and no macrolide resistance genes or known point mutations were detected. Other than the GyrAS83F mutation, the AMR genes detected were mapped to potential plasmids. In addition to presence on plasmid(s), the tet(B) gene was also found chromosomally either as part of a 56 kb integrative conjugative element (ICEApl1) in 21, or as part of a Tn7 insertion in 15 isolates. Our results indicate that, with the exception of macrolides, wgs data can be used to accurately predict resistance of A. pleuropneumoniae to the tested antimicrobial agents and provides added value for routine surveillance.

  3. Tissue reaction and immunity in swine immunized with Actinobacillus pleuropneumoniae vaccines.

    PubMed Central

    Willson, P J; Rossi-Campos, A; Potter, A A

    1995-01-01

    These studies were done to develop a subunit vaccine for swine that would protect against disease, but not create unacceptable tissue reactions at the immunization site. Swine were used to evaluate the local effects of subunit vaccines prepared from extracts of Actinobacillus pleuropneumoniae serotype 1 containing one of a wide variety of adjuvants. The antigen was an anionic fraction of a saline extract of A. pleuropneumoniae (ANEX). The adjuvants used were vegetable oils (peanut, sesame, canola, or corn oils, vitamin E, or Lipposyn II emulsion); mineral oil (Marcol-52) and other materials (aluminum hydroxide, polyethylene glycol, Quil-A, Amphigen, or Emulsigen-Plus). Two types of experiments were done. In the 1st set of experiments, pigs were given multiple simultaneous injections in different sites and euthanized on days 1, 3, 7, 14, 21, or 28. Tissues were examined for gross and histopathological lesions. In the 2nd set of experiments, 48 pigs were allocated to 6 groups and vaccinated twice with a vaccine containing ANEX antigen combined with one of various adjuvants. Antibody responses and protection from challenge were evaluated. Among the adjuvants that were tested, mineral oils induced protective immunity, although the mineral oil Marcol-52 resulted in severe tissue reactions. The vegetable oils induced little protective immunity, and some of them were quite irritating. The response to the other materials ranged from little irritation or protection induced by the vaccine containing aluminum hydroxide to effective protection without irritation after vaccination with ANEX/Amphigen or ANEX/Emulsigen-Plus combinations. In conclusion, swine were protected against disease by a subunit vaccine that did not create unacceptable tissue reaction at the immunization site. PMID:8548692

  4. Improved protection against lung colonization by Actinobacillus pleuropneumoniae ghosts: characterization of a genetically inactivated vaccine.

    PubMed

    Huter, V; Hensel, A; Brand, E; Lubitz, W

    2000-09-29

    Pigs immunized with Actinobacillus pleuropneumoniae ghosts or a formalin-inactivated bacterin were found to be protected against clinical disease in both vaccination groups, whereas colonization of the lungs with A. pleuropneumoniae was only prevented in ghost-vaccinated pigs. Bacterial ghosts are empty cell envelopes created by the expression of a cloned bacteriophage lysis gene and, unlike formalin-inactivated bacteria, suffer no denaturing steps during their production. This quality may lead to a superior presentation of surface antigens to the immune system. Analysis by SDS-PAGE and immunoblotting of the two vaccine preparations revealed different contents of antigenic proteins. In order to better understand the immunogenic properties of A. pleuropneumoniae ghosts and formalin-inactivated bacteria, we compared the serum antibody response induced in both treatment groups. Immune sera were tested on whole cell antigen or purified virulence factors including outer membrane protein preparations (OMPs), outer membrane lipoprotein OmlA1, transferrin binding proteins (TfbA1, TfbA7 and TfbB) and Apx toxins (ApxI, II and III). SDS-PAGE and immunoblots revealed no specific antibody response against the single virulence factors tested in any vaccinated animal. The two vaccination groups showed different recognition patterns of whole cell antigen and OMP-enriched preparations. A 100 kDa protein was recognized significantly stronger by ghost-vaccinated pigs than convalescent pigs. This unique antibody population induced by ghosts could play a determining role in the prevention of lung colonization. The same 100 kDa antigen was recognized by ghost-sera in homologous as well as heterologous serotype A. pleuropneumoniae protein preparations. Indications for a crossprotective potential in the ghost vaccine were supported by studies on rabbit hyperimmune sera.

  5. The N-linking glycosylation system from Actinobacillus pleuropneumoniae is required for adhesion and has potential use in glycoengineering

    PubMed Central

    Bossé, Janine T.; Abouelhadid, Sherif; Li, Yanwen; Lin, Chia-Wei; Vohra, Prerna; Tucker, Alexander W.; Rycroft, Andrew N.; Maskell, Duncan J.; Aebi, Markus; Langford, Paul R.

    2017-01-01

    Actinobacillus pleuropneumoniae is a mucosal respiratory pathogen causing contagious porcine pleuropneumonia. Pathogenesis studies have demonstrated a major role for the capsule, exotoxins and outer membrane proteins. Actinobacillus pleuropneumoniae can also glycosylate proteins, using a cytoplasmic N-linked glycosylating enzyme designated NGT, but its transcriptional arrangement and role in virulence remains unknown. We investigated the NGT locus and demonstrated that the putative transcriptional unit consists of rimO, ngt and a glycosyltransferase termed agt. From this information we used the A. pleuropneumoniae glycosylation locus to decorate an acceptor protein, within Escherichia coli, with a hexose polymer that reacted with an anti-dextran antibody. Mass spectrometry analysis of a truncated protein revealed that this operon could add up to 29 repeat units to the appropriate sequon. We demonstrated the importance of NGT in virulence, by creating deletion mutants and testing them in a novel respiratory cell line adhesion model. This study demonstrates the importance of the NGT glycosylation system for pathogenesis and its potential biotechnological application for glycoengineering. PMID:28077594

  6. Enterococcus faecalis lipoteichoic acid suppresses Aggregatibacter actinomycetemcomitans lipopolysaccharide-induced IL-8 expression in human periodontal ligament cells.

    PubMed

    Im, Jintaek; Baik, Jung Eun; Kim, Kyoung Whun; Kang, Seok-Seong; Jeon, Jun Ho; Park, Ok-Jin; Kim, Hyun Young; Kum, Kee-Yeon; Yun, Cheol-Heui; Han, Seung Hyun

    2015-08-01

    Periodontitis is caused by multi-bacterial infection and Aggregatibacter actinomycetemcomitans and Enterococcus faecalis are closely associated with inflammatory periodontal diseases. Although lipopolysaccharide (LPS) of A. actinomycetemcomitans (Aa.LPS) and lipoteichoic acid of E. faecalis (Ef.LTA) are considered to be major virulence factors evoking inflammatory responses, their combinatorial effect on the induction of chemokines has not been investigated. In this study, we investigated the interaction between Aa.LPS and Ef.LTA on IL-8 expression in human periodontal ligament (PDL) cells. Aa.LPS, but not Ef.LTA, substantially induced IL-8 expression at the protein and mRNA levels. Interestingly, Ef.LTA suppressed Aa.LPS-induced IL-8 expression without affecting the binding of Aa.LPS to Toll-like receptor (TLR) 4. Ef.LTA reduced Aa.LPS-induced phosphorylation of mitogen-activated protein kinases, including ERK, JNK and p38 kinase. Furthermore, Ef.LTA inhibited the Aa.LPS-induced transcriptional activities of the activating protein 1, CCAAT/enhancer-binding protein and nuclear factor-kappa B transcription factors, all of which are known to regulate IL-8 gene expression. Ef.LTA augmented the expression of IL-1 receptor-associated kinase-M (IRAK-M), a negative regulator of TLR intracellular signaling pathways, in the presence of Aa.LPS at both the mRNA and protein levels. Small interfering RNA silencing IRAK-M reversed the attenuation of Aa.LPS-induced IL-8 expression by Ef.LTA. Collectively, these results suggest that Ef.LTA down-regulates Aa.LPS-induced IL-8 expression in human PDL cells through up-regulation of the negative regulator IRAK-M.

  7. Aggregatibacter actinomycetemcomitans leukotoxin (LtxA; Leukothera) induces cofilin dephosphorylation and actin depolymerization during killing of malignant monocytes

    PubMed Central

    Kaur, Manpreet

    2014-01-01

    Leukotoxin (LtxA; Leukothera), a protein toxin secreted by the oral bacterium Aggregatibacter actinomycetemcomitans, specifically kills white blood cells (WBCs). LtxA binds to the receptor known as lymphocyte function associated antigen-1 (LFA-1), a β2 integrin expressed only on the surface of WBCs. LtxA is being studied as a virulence factor that helps A. actinomycetemcomitans evade host defences and as a potential therapeutic agent for the treatment of WBC diseases. LtxA-mediated cell death in monocytes involves both caspases and lysosomes; however, the signalling proteins that regulate and mediate cell death remain largely unknown. We used a 2D-gel proteomics approach to analyse the global protein expression changes that occur in response to LtxA. This approach identified the protein cofilin, which underwent dephosphorylation upon LtxA treatment. Cofilin is a ubiquitous actin-binding protein known to regulate actin dynamics and is regulated by LIM kinase (LIMK)-mediated phosphorylation. LtxA-mediated cofilin dephosphorylation was dependent on LFA-1 and cofilin dephosphorylation did not occur when LFA-1 bound to its natural ligand, ICAM-1. Treatment of cells with an inhibitor of LIMK (LIMKi) also led to cofilin dephosphorylation and enhanced killing by LtxA. This enhanced sensitivity to LtxA coincided with an increase in lysosomal disruption, and an increase in LFA-1 surface expression and clustering. Both LIMKi and LtxA treatment also induced actin depolymerization, which could play a role in trafficking and surface distribution of LFA-1. We propose a model in which LtxA-mediated cofilin dephosphorylation leads to actin depolymerization, LFA-1 overexpression/clustering, and enhanced lysosomal-mediated cell death. PMID:25169107

  8. Prevalence of Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis and Tannerella forsythia in Japanese patients with generalized chronic and aggressive periodontitis.

    PubMed

    Tomita, Sachiyo; Komiya-Ito, Akiyo; Imamura, Kentaro; Kita, Daichi; Ota, Koki; Takayama, Saori; Makino-Oi, Asako; Kinumatsu, Takashi; Ota, Mikio; Saito, Atsushi

    2013-01-01

    This study aimed to investigate the prevalence and levels of major periodontal pathogens, Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis and Tannerella forsythia in subgingival plaque samples of a group of Japanese patients with aggressive periodontitis (AgP) and chronic periodontitis (CP). A total of 40 patients with clinical diagnosis of AgP or CP and 10 periodontally healthy volunteers were subjected to clinical and microbiological analysis. Subgingival plaque samples were analyzed for A. actinomycetemcomitans, P. gingivalis and T. forsythia with a real-time polymerase chain reaction (PCR) technique. The prevalence of P. gingivalis and T. forsythia was relatively high in patients with periodontitis: over 60% of AgP or CP patients harbored these pathogens whereas they were not detected in the subgingival plaque samples from periodontally healthy individuals. P. gingivalis and T. forsythia were relatively frequently detected together in AgP and CP patients. No significant differences in the prevalence or level of the 3 pathogens were found between periodontitis groups. The proportion of T. forsythia was approximately 4-fold higher in CP group than in AgP group (P = 0.02). In periodontitis patients, a significant positive correlation was found between periodontal parameters (probing depth and clinical attachment level) and the numbers of total bacteria, P. gingivalis and T. forsythia. No distinct pattern of the subgingival profile of these pathogens was discerned between the two disease entities, except for the difference in the proportion of T. forsythia. The red complex bacteria, P. gingivalis and T. forsythia were highly prevalent in this population of Japanese AgP and CP patients, collaborating their roles in periodontitis.

  9. Whole Genome Sequencing for Surveillance of Antimicrobial Resistance in Actinobacillus pleuropneumoniae

    PubMed Central

    Bossé, Janine T.; Li, Yanwen; Rogers, Jon; Fernandez Crespo, Roberto; Li, Yinghui; Chaudhuri, Roy R.; Holden, Matthew T. G.; Maskell, Duncan J.; Tucker, Alexander W.; Wren, Brendan W.; Rycroft, Andrew N.; Langford, Paul R.

    2017-01-01

    The aim of this study was to evaluate the correlation between antimicrobial resistance (AMR) profiles of 96 clinical isolates of Actinobacillus pleuropneumoniae, an important porcine respiratory pathogen, and the identification of AMR genes in whole genome sequence (wgs) data. Susceptibility of the isolates to nine antimicrobial agents (ampicillin, enrofloxacin, erythromycin, florfenicol, sulfisoxazole, tetracycline, tilmicosin, trimethoprim, and tylosin) was determined by agar dilution susceptibility test. Except for the macrolides tested, elevated MICs were highly correlated to the presence of AMR genes identified in wgs data using ResFinder or BLASTn. Of the isolates tested, 57% were resistant to tetracycline [MIC ≥ 4 mg/L; 94.8% with either tet(B) or tet(H)]; 48% to sulfisoxazole (MIC ≥ 256 mg/L or DD = 6; 100% with sul2), 20% to ampicillin (MIC ≥ 4 mg/L; 100% with blaROB-1), 17% to trimethoprim (MIC ≥ 32 mg/L; 100% with dfrA14), and 6% to enrofloxacin (MIC ≥ 0.25 mg/L; 100% with GyrAS83F). Only 33% of the isolates did not have detectable AMR genes, and were sensitive by MICs for the antimicrobial agents tested. Although 23 isolates had MIC ≥ 32 mg/L for tylosin, all isolates had MIC ≤ 16 mg/L for both erythromycin and tilmicosin, and no macrolide resistance genes or known point mutations were detected. Other than the GyrAS83F mutation, the AMR genes detected were mapped to potential plasmids. In addition to presence on plasmid(s), the tet(B) gene was also found chromosomally either as part of a 56 kb integrative conjugative element (ICEApl1) in 21, or as part of a Tn7 insertion in 15 isolates. Our results indicate that, with the exception of macrolides, wgs data can be used to accurately predict resistance of A. pleuropneumoniae to the tested antimicrobial agents and provides added value for routine surveillance. PMID:28321207

  10. A genomic perspective on the potential of Actinobacillus succinogenes for industrial succinate production

    PubMed Central

    2010-01-01

    Background Succinate is produced petrochemically from maleic anhydride to satisfy a small specialty chemical market. If succinate could be produced fermentatively at a price competitive with that of maleic anhydride, though, it could replace maleic anhydride as the precursor of many bulk chemicals, transforming a multi-billion dollar petrochemical market into one based on renewable resources. Actinobacillus succinogenes naturally converts sugars and CO2 into high concentrations of succinic acid as part of a mixed-acid fermentation. Efforts are ongoing to maximize carbon flux to succinate to achieve an industrial process. Results Described here is the 2.3 Mb A. succinogenes genome sequence with emphasis on A. succinogenes's potential for genetic engineering, its metabolic attributes and capabilities, and its lack of pathogenicity. The genome sequence contains 1,690 DNA uptake signal sequence repeats and a nearly complete set of natural competence proteins, suggesting that A. succinogenes is capable of natural transformation. A. succinogenes lacks a complete tricarboxylic acid cycle as well as a glyoxylate pathway, and it appears to be able to transport and degrade about twenty different carbohydrates. The genomes of A. succinogenes and its closest known relative, Mannheimia succiniciproducens, were compared for the presence of known Pasteurellaceae virulence factors. Both species appear to lack the virulence traits of toxin production, sialic acid and choline incorporation into lipopolysaccharide, and utilization of hemoglobin and transferrin as iron sources. Perspectives are also given on the conservation of A. succinogenes genomic features in other sequenced Pasteurellaceae. Conclusions Both A. succinogenes and M. succiniciproducens genome sequences lack many of the virulence genes used by their pathogenic Pasteurellaceae relatives. The lack of pathogenicity of these two succinogens is an exciting prospect, because comparisons with pathogenic Pasteurellaceae could

  11. A Transcriptome Map of Actinobacillus pleuropneumoniae at Single-Nucleotide Resolution Using Deep RNA-Seq

    PubMed Central

    Su, Zhipeng; Zhu, Jiawen; Xu, Zhuofei; Xiao, Ran; Zhou, Rui; Li, Lu; Chen, Huanchun

    2016-01-01

    Actinobacillus pleuropneumoniae is the pathogen of porcine contagious pleuropneumoniae, a highly contagious respiratory disease of swine. Although the genome of A. pleuropneumoniae was sequenced several years ago, limited information is available on the genome-wide transcriptional analysis to accurately annotate the gene structures and regulatory elements. High-throughput RNA sequencing (RNA-seq) has been applied to study the transcriptional landscape of bacteria, which can efficiently and accurately identify gene expression regions and unknown transcriptional units, especially small non-coding RNAs (sRNAs), UTRs and regulatory regions. The aim of this study is to comprehensively analyze the transcriptome of A. pleuropneumoniae by RNA-seq in order to improve the existing genome annotation and promote our understanding of A. pleuropneumoniae gene structures and RNA-based regulation. In this study, we utilized RNA-seq to construct a single nucleotide resolution transcriptome map of A. pleuropneumoniae. More than 3.8 million high-quality reads (average length ~90 bp) from a cDNA library were generated and aligned to the reference genome. We identified 32 open reading frames encoding novel proteins that were mis-annotated in the previous genome annotations. The start sites for 35 genes based on the current genome annotation were corrected. Furthermore, 51 sRNAs in the A. pleuropneumoniae genome were discovered, of which 40 sRNAs were never reported in previous studies. The transcriptome map also enabled visualization of 5'- and 3'-UTR regions, in which contained 11 sRNAs. In addition, 351 operons covering 1230 genes throughout the whole genome were identified. The RNA-Seq based transcriptome map validated annotated genes and corrected annotations of open reading frames in the genome, and led to the identification of many functional elements (e.g. regions encoding novel proteins, non-coding sRNAs and operon structures). The transcriptional units described in this study

  12. Comparative in vitro activity of 16 antimicrobial agents against Actinobacillus pleuropneumoniae.

    PubMed

    Yoshimura, H; Takagi, M; Ishimura, M; Endoh, Y S

    2002-01-01

    Sixteen antimicrobial agents were tested for their activity against 68 isolates of Actinobacillus pleuropneumoniae by determining the minimum inhibitory concentrations (MICs). Ceftiofur and the fluoroquinolones danofloxacin and enrofloxacin were the most active compounds, with a MIC for 90% of the isolates (MIC90) of (0.05 microg/ml. The MIC90 values of benzylpenicillin, amoxicillin and aspoxicillin were 0.78 units/ml, 0.39 microg/ml and < or = 0.05 microg/ml, respectively. Three isolates (4.4%) were resistant to penicillins, but aspoxicillin was as active as ceftiofur against the susceptible isolates, with MICs of < or = 0.05 microg/ml for all isolates. Resistance to oxytetracycline, chloramphenicol and thiamphenicol occurred in 22 (32.4%), 14 (20.6%) and 15 (22.1%) of the isolates, respectively. Doxycycline was more active than oxytetracycline, with a MIC90 of 1.56 microg/ml as against 25 microg/ml. Florfenicol was not only as active as thiamphenicol, with a MIC for 50% of the isolates (MIC50) of 0.39 microg/ml, but also active against thiamphenicol-resistant isolates. All the isolates were susceptible to florfenicol. All the isolates were also susceptible to gentamicin, spectinomycin, tilmicosin, colistin and tiamulin. Of these, spectinomycin was the least active, with a MIC50 of 25 microg/ml, followed by tiamulin, with a MIC50 of 6.25 microg/ml. Of the 68 isolates tested, 49 (72.0%) were of serotype 2; 14 (20.5%) were of serotype 1; 2 each (3.0%) were of serotypes 5 and 6; and one was of serotype 7. Of the isolates, 23 (33.8%) were resistant to one or more of the major antibiotics. Antibiotic resistance was found only infrequently among serotype 2, with 5 (10.2%) of 49 isolates being resistant to chloramphenicol and/or oxytetracycline, while it occurred in 18 (94.7%) of the 19 isolates of other serotypes.

  13. Breaking the Gingival Epithelial Barrier: Role of the Aggregatibacter actinomycetemcomitans Cytolethal Distending Toxin in Oral Infectious Disease

    PubMed Central

    DiRienzo, Joseph M.

    2014-01-01

    The Gram-negative bacterium Aggregatibacter actinomycetemcomitans is part of the HACEK group that causes infective endocarditis, a constituent of the oral flora that promotes some forms of periodontal disease and a member of the family of species that secrete a cytolethal distending toxin (Cdt). The family of bacteria that express the cdt genes participate in diseases that involve the disruption of a mucosal or epithelial layer. In vitro studies have shown that human gingival epithelial cells (HGEC) are native targets of the Cdt that typically induces DNA damage that signals growth arrest at the G2/M interphase of the cell cycle. The gingival epithelium is an early line of defense in the oral cavity against microbial assault. When damaged, bacteria collectively gain entry into the underlying connective tissue where microbial products can affect processes and pathways in infiltrating inflammatory cells culminating in the destruction of the attachment apparatus of the tooth. One approach has been the use of an ex vivo gingival explant model to assess the effects of the Cdt on the morphology and integrity of the tissue. The goal of this review is to provide an overview of these studies and to critically examine the potential contribution of the Cdt to the breakdown of the protective gingival barrier. PMID:24861975

  14. Bagasse hydrolyzates from Agave tequilana as substrates for succinic acid production by Actinobacillus succinogenes in batch and repeated batch reactor.

    PubMed

    Corona-González, Rosa Isela; Varela-Almanza, Karla María; Arriola-Guevara, Enrique; Martínez-Gómez, Álvaro de Jesús; Pelayo-Ortiz, Carlos; Toriz, Guillermo

    2016-04-01

    The aim of this work was to obtain fermentable sugars by enzymatic or acid hydrolyses of Agave tequilana Weber bagasse in order to produce succinic acid with Actinobacillus succinogenes. Hydrolyses were carried out with mineral acids (sulfuric and hydrochloric acids) or a commercial cellulolytic enzyme, and were optimized statistically by a response surface methodology, having as factors the concentration of acid/enzyme and time of hydrolysis. The concentration of sugars obtained at optimal conditions for each hydrolysis were 21.7, 22.4y 19.8g/L for H2SO4, HCl and the enzymatic preparation respectively. Concerning succinic acid production, the enzymatic hydrolyzates resulted in the highest yield (0.446g/g) and productivity (0.57g/Lh) using A. succinogenes in a batch reactor system. Repeated batch fermentation with immobilized A. succinogenes in agar and with the enzymatic hydrolyzates resulted in a maximum concentration of succinic acid of 33.6g/L from 87.2g/L monosaccharides after 5 cycles in 40h, obtaining a productivity of 1.32g/Lh.

  15. Simultaneous saccharification and fermentation of acid-pretreated rapeseed meal for succinic acid production using Actinobacillus succinogenes.

    PubMed

    Chen, Kequan; Zhang, Han; Miao, Yelian; Wei, Ping; Chen, Jieyu

    2011-04-07

    Rapeseed meal was evaluated for succinic acid production by simultaneous saccharification and fermentation using Actinobacillus succinogenes ATCC 55618. Diluted sulfuric acid pretreatment and subsequent hydrolysis with pectinase was used to release sugars from rapeseed meal. The effects of culture pH, pectinase loading and yeast extract concentration on succinic acid production were investigated. When simultaneous saccharification and fermentation of diluted acid pretreated rapeseed meal with a dry matter content of 12.5% (w/v) was performed at pH 6.4 and a pectinase loading of 2% (w/w, on dry matter) without supplementation of yeast extract, a succinic acid concentration of 15.5 g/L was obtained at a yield of 12.4 g/100g dry matter. Fed-batch simultaneous saccharification and fermentation was carried out with supplementation of concentrated pretreated rapeseed meal and pectinase at 18 and 28 h to yield a final dry matter content of 20.5% and pectinase loading of 2%, with the succinic acid concentration enhanced to 23.4 g/L at a yield of 11.5 g/100g dry matter and a productivity of 0.33 g/(Lh). This study suggests that rapeseed meal may be an alternative substrate for the efficient production of succinic acid by A. succinogenes without requiring nitrogen source supplementation.

  16. Structure of PEP carboxykinase from the succinate-producing Actinobacillus succinogenes: a new conserved active-site motif.

    PubMed

    Leduc, Yvonne A; Prasad, Lata; Laivenieks, Maris; Zeikus, J Gregory; Delbaere, Louis T J

    2005-07-01

    Actinobacillus succinogenes can produce, via fermentation, high concentrations of succinate, an important industrial commodity. A key enzyme in this pathway is phosphoenolpyruvate carboxykinase (PCK), which catalyzes the production of oxaloacetate from phosphoenolpyruvate and carbon dioxide, with the concomitant conversion of adenosine 5'-diphosphate to adenosine 5'-triphosphate. 1.85 and 1.70 A resolution structures of the native and a pyruvate/Mn(2+)/phosphate complex have been solved, respectively. The structure of the complex contains sulfhydryl reducing agents covalently bound to three cysteine residues via disulfide bonds. One of these cysteine residues (Cys285) is located in the active-site cleft and may be analogous to the putative reactive cysteine of PCK from Trypanosoma cruzi. Cys285 is also part of a previously unreported conserved motif comprising residues 280-287 and containing the pattern NXEXGXY(/F)A(/G); this new motif appears to have a structural role in stabilizing and positioning side chains that bind substrates and metal ions. The first few residues of this motif connect the two domains of the enzyme and a fulcrum point appears to be located near Asn280. In addition, an active-site Asp residue forms two coordinate bonds with the Mn(2+) ion present in the structure of the complex in a symmetrical bidentate manner, unlike in other PCK structures that contain a manganese ion.

  17. Actinobacillus succinogenes ATCC 55618 Fermentation Medium Optimization for the Production of Succinic Acid by Response Surface Methodology

    PubMed Central

    Zhu, Li-Wen; Wang, Cheng-Cheng; Liu, Rui-Sang; Li, Hong-Mei; Wan, Duan-Ji; Tang, Ya-Jie

    2012-01-01

    As a potential intermediary feedstock, succinic acid takes an important place in bulk chemical productions. For the first time, a method combining Plackett-Burman design (PBD), steepest ascent method (SA), and Box-Behnken design (BBD) was developed to optimize Actinobacillus succinogenes ATCC 55618 fermentation medium. First, glucose, yeast extract, and MgCO3 were identified to be key medium components by PBD. Second, preliminary optimization was run by SA method to access the optimal region of the key medium components. Finally, the responses, that is, the production of succinic acid, were optimized simultaneously by using BBD, and the optimal concentration was located to be 84.6 g L−1 of glucose, 14.5 g L−1 of yeast extract, and 64.7 g L−1 of MgCO3. Verification experiment indicated that the maximal succinic acid production of 52.7 ± 0.8 g L−1 was obtained under the identified optimal conditions. The result agreed with the predicted value well. Compared with that of the basic medium, the production of succinic acid and yield of succinic acid against glucose were enhanced by 67.3% and 111.1%, respectively. The results obtained in this study may be useful for the industrial commercial production of succinic acid. PMID:23093852

  18. Identification and characterization of a DNA region involved in the export of capsular polysaccharide by Actinobacillus pleuropneumoniae serotype 5a.

    PubMed Central

    Ward, C K; Inzana, T J

    1997-01-01

    Actinobacillus pleuropneumoniae synthesizes a serotype-specific capsular polysaccharide that acts as a protective barrier to phagocytosis and complement-mediated killing. To begin understanding the role of A. pleuropneumoniae capsule in virulence, we sought to identify the genes involved in capsular polysaccharide export and biosynthesis. A 5.3-kb XbaI fragment of A. pleuropneumoniae serotype 5a J45 genomic DNA that hybridized with DNA probes specific for the Haemophilus influenzae type b cap export region was cloned and sequenced. This A. pleuropneumoniae DNA fragment encoded four open reading frames, designated cpxDCBA. The nucleotide and predicted amino acid sequences of cpxDCBA contained a high degree of homology to the capsule export genes of H. influenzae type b bexDCBA, Neisseria meningitidis group B ctrABCD, and, to a lesser extent, Escherichia coli K1 and K5 kpsE and kpsMT. When present in trans, the cpxDCBA gene cluster complemented kpsM::TnphoA or kpsT::TnphoA mutations, determined by enzyme immunoassay and by restored sensitivity to a K5-specific bacteriophage. A cpxCB probe hybridized to genomic DNA from all A. pleuropneumoniae serotypes tested, indicating that this DNA was conserved among serotypes. These data suggest that A. pleuropneumoniae produces a group II family capsule similar to those of related mucosal pathogens. PMID:9169799

  19. Use of corn steep liquor as an economical nitrogen source for biosuccinic acid production by Actinobacillus succinogenes

    NASA Astrophysics Data System (ADS)

    Tan, J. P.; Jahim, J. M.; Wu, T. Y.; Harun, S.; Mumtaz, T.

    2016-06-01

    Expensive raw materials are the driving force that leads to the shifting of the petroleum-based succinic acid production into bio-based succinic acid production by microorganisms. Cost of fermentation medium is among the main factors contributing to the total production cost of bio-succinic acid. After carbon source, nitrogen source is the second largest component of the fermentation medium, the cost of which has been overlooked for the past years. The current study aimed at replacing yeast extract- a costly nitrogen source with corn steep liquor for economical production of bio-succinic acid by Actinobacillus succinogenes 130Z. In this study, a final succinic acid concentration of 20.6 g/L was obtained from the use of corn steep liquor as the nitrogen source, which was comparable with the use of yeast extract as the nitrogen source that had a final succinate concentration of 21.4 g/l. In terms of economical wise, corn steep liquor was priced at 200 /ton, which was one fifth of the cost of yeast extract at 1000 /ton. Therefore, corn steep liquor can be considered as a potential nitrogen source in biochemical industries instead of the costly yeast extract.

  20. Changes in gene expression of Actinobacillus pleuropneumoniae in response to anaerobic stress reveal induction of central metabolism and biofilm formation.

    PubMed

    Li, Lu; Zhu, Jiawen; Yang, Kui; Xu, Zhuofei; Liu, Ziduo; Zhou, Rui

    2014-06-01

    Actinobacillus pleuropneumoniae is an important porcine respiratory pathogen causing great economic losses in the pig industry worldwide. Oxygen deprivation is a stress that A. pleuropneumoniae will encounter during both early infection and the later, persistent stage. To understand modulation of A. pleuropneumoniae gene expression in response to the stress caused by anaerobic conditions, gene expression profiles under anaerobic and aerobic conditions were compared in this study. The microarray results showed that 631 genes (27.7% of the total ORFs) were differentially expressed in anaerobic conditions. Many genes encoding proteins involved in glycolysis, carbon source uptake systems, pyruvate metabolism, fermentation and the electron respiration transport chain were up-regulated. These changes led to an increased amount of pyruvate, lactate, ethanol and acetate in the bacterial cells as confirmed by metabolite detection. Genes encoding proteins involved in cell surface structures, especially biofilm formation, peptidoglycan biosynthesis and lipopolysaccharide biosynthesis were up-regulated as well. Biofilm formation was significantly enhanced under anaerobic conditions. These results indicate that induction of central metabolism is important for basic survival of A. pleuropneumoniae after a shift to an anaerobic environment. Enhanced biofilm formation may contribute to the persistence of this pathogen in the damaged anaerobic host tissue and also in the early colonization stage. These discoveries give new insights into adaptation mechanisms of A. pleuropneumoniae in response to environmental stress.

  1. Evaluation of a single dose versus a divided dose regimen of amoxycillin in treatment of Actinobacillus pleuropneumoniae infection in pigs.

    PubMed

    Lauritzen, B; Lykkesfeldt, J; Friis, C

    2005-08-01

    The theory of a time-dependent effect of amoxycillin was examined in a model of porcine Actinobacillus pleuropneumoniae (Ap)-infection using clinically relevant dosage regimens. Twenty hours after infection of fourteen pigs, when clinical signs of pneumonia were present, one group of pigs received a single dose of amoxycillin (20 mg/kg, i.m.), whereas another group received four doses of 5 mg/kg injected at 8-h intervals. A similar AUC of the plasma amoxycillin concentration versus time curve was obtained in the two groups, whereas the maximum concentration was threefold higher using the single high dose. Plasma amoxycillin was above the MIC for twice as long using the fractionated dosage scheme. The condition of the animals was evaluated by clinical and haematological observations combined with quantification of biochemical infection markers: C-reactive protein, zinc and ascorbic acid. Within 48 h of treatment, the pigs in both treatment groups recovered clinically. No significant differences in the time-course of clinical observations or plasma concentrations of the biomarkers of infection were observed between the two treatments. In conclusion, the efficacy of these two dosage regimens of amoxycillin was not significantly different in treatment of acute Ap-infection in pigs.

  2. A TolC-Like Protein of Actinobacillus pleuropneumoniae Is Involved in Antibiotic Resistance and Biofilm Formation

    PubMed Central

    Li, Ying; Cao, Sanjie; Zhang, Luhua; Lau, Gee W.; Wen, Yiping; Wu, Rui; Zhao, Qin; Huang, Xiaobo; Yan, Qigui; Huang, Yong; Wen, Xintian

    2016-01-01

    Actinobacillus pleuropneumoniae is the etiologic agent of porcine contagious pleuropneumonia, a significant disease that causes serious economic losses to the swine industry worldwide. Persistent infections caused by bacterial biofilms are recalcitrant to treat because of the particular drug resistance of biofilm-dwelling cells. TolC, a key component of multidrug efflux pumps, are responsible for multidrug resistance (MDR) in many Gram-negative bacteria. In this study, we identified two TolC-like proteins, TolC1 and TolC2, in A. pleuropneumoniae. Deletion of tolC1, but not tolC2, caused a significant reduction in biofilm formation, as well as increased drug sensitivity of both planktonic and biofilm cells. The genetic-complementation of the tolC1 mutation restored the competent biofilm and drug resistance. Besides, biofilm formation was inhibited and drug sensitivity was increased by the addition of phenylalanine-arginine beta-naphthylamide (PAβN), a well-known efflux pump inhibitor (EPI), suggesting a role for EPI in antibacterial strategies toward drug tolerance of A. pleuropneumoniae. Taken together, TolC1 is required for biofilm formation and is a part of the MDR machinery of both planktonic and biofilm cells, which could supplement therapeutic strategies for resistant bacteria and biofilm-related infections of A. pleuropneumoniae clinical isolate SC1516. PMID:27822201

  3. Evaluation of antimicrobial action of Carie Care™ and Papacarie Duo™ on Aggregatibacter actinomycetemcomitans a major periodontal pathogen using polymerase chain reaction

    PubMed Central

    Kush, Anil; Thakur, Rachna; Patil, Sandya Devi S.; Paul, Santhosh T.; Kakanur, Madhu

    2015-01-01

    Background: In the present scenario, we are made available with chemomechanical caries removal system containing a natural proteolytic enzyme for the ease in the excavation of infected dentine. The additive action for these agents is providing antimicrobial and anti-inflammatory properties. Aim: This study was undertaken for assessing the action of Carie Care™ and Papacarie Duo™ on Aggregatibacter actinomycetemcomitans. Materials and Methods: The samples were collected for cultivation of the periodontal pathogen from the clinical periodontal pockets using sterile paper points. The samples cultured under suitable conditions were analyzed with quantitative polymerase chain reaction targeting 16s r-DNA. The samples were divided into three groups namely, Group A: Control, Group B: With Papacarie Duo, Group C: With Carie Care. The pathogen inoculums plugs were inserted in the petri dishes containing chemically defined medium and the experimental gels at different concentrations and were incubated under optimal conditions. The inhibition of growth of the pathogen was studied visually. Results: There was visual inhibition of growth for Group B and C and also exhibited a dose-dependent effect also. Conclusion: Based on the results of the present study, Carie Care™ gel demonstrated better antimicrobial action against A. actinomycetemcomitans which is a major periodontal disease causing pathogen. PMID:26681861

  4. Immunoprotective Efficacy of Six In vivo-Induced Antigens against Actinobacillus pleuropneumoniae as Potential Vaccine Candidates in Murine Model

    PubMed Central

    Zhang, Fei; Cao, Sanjie; Zhu, Zhuang; Yang, Yusheng; Wen, Xintian; Chang, Yung-Fu; Huang, Xiaobo; Wu, Rui; Wen, Yiping; Yan, Qigui; Huang, Yong; Ma, Xiaoping; Zhao, Qin

    2016-01-01

    Six in vivo-induced (IVI) antigens—RnhB, GalU, GalT, Apl_1061, Apl_1166, and HflX were selected for a vaccine trial in a mouse model. The results showed that the IgG levels in each immune group was significantly higher than that of the negative control (P < 0.001). Except rRnhB group, proliferation of splenocytes was observed in all immunized groups and a relatively higher proliferation activity was observed in rGalU and rGalT groups (P < 0.05). In the rGalT vaccinated group, the proportion of CD4+ T cells in spleen was significant higher than that of negative control (P < 0.05). Moreover, proportions of CD4+ T cells in other vaccinated groups were all up-regulated to varying degrees. Up-regulation of both Th1 (IFN-γ, IL-2) and Th2 (IL-4) cytokines were detected. A survival rate of 87.5, 62.5, and 62.5% were obtained among rGalT, rAPL_1166, and rHflX group, respectively while the remaining three groups was only 25%. Histopathological analyses of lungs indicated that surviving animals from the vaccinated groups showed relatively normal pulmonary structure alveoli. These findings confirm that IVI antigens used as vaccine candidates provide partial protection against Actinobacillus pleuropneumoniae infection in a mouse model, which could be used as potential vaccine candidates in piglets. PMID:27818646

  5. Oral immunization against porcine pleuropneumonia using the cubic phase of monoolein and purified toxins of Actinobacillus pleuropneumoniae.

    PubMed

    Lopez-Bermudez, Jorge; Quintanar-Guerrero, David; Lara Puente, Horacio; Tórtora Perez, Jorge; Suárez Güemez, Francisco; Ciprián Carrasco, Abel; Mendoza Elvira, Susana

    2014-11-28

    The main goal of this work was to obtain an orally administered immunogen that would protect against infections by Actinobacillus pleuropneumoniae. The Apx I, II and III toxins were obtained from the supernatants of cultures of serotypes 1 and 3 of A. pleuropneumoniae. The capacity of monoolein gel to trap and protect the Apx toxins, and the effect of their incorporation on the stability of the cubic phase were evaluated. The gel was capable of trapping a 400-μg/ml concentration of the antigen with no effects on its structure. Approximately 60% of the protein molecules were released from the gel within 4h. Four experimental groups were formed, each one with four pigs. All challenges were conducted in a nebulization chamber. Group A: Control (-) not vaccinated and not challenged; Group B: Control (+) not vaccinated but challenged; Group C: vaccinated twice intramuscularly with ToxCom (a commercial toxoid) at an interval of 15 days and then challenged; and Group D: vaccinated orally twice a week for 4 weeks with ToxOral (an oral toxoid) and challenged on day 28 of the experiment with a same dose of 2.0 × 10(4) UFC of A. pleuropneumoniae serotypes 1 and 3. The lesions found in group B covered 27.7-43.1% of the lungs; the pigs in group C had lesions over 12.3-28%; and those in group D over 15.4-32.3%. No lesions were found in the Group A pigs. A. pleuropneumoniae induced macroscopic lesions characteristic of infection by and lesions microscopic detected by histopathology. The etiologic agent was recovered from the infected lungs, tonsils and spleen. The serotypes identified were 1 and 3. An indirect ELISA test identified the antibodies against the Apx toxins in the serum of the animals immunized orally.

  6. Comparison of four lung scoring systems for the assessment of the pathological outcomes derived from Actinobacillus pleuropneumoniae experimental infections

    PubMed Central

    2014-01-01

    Background In this study, four lung lesion scoring methods (Slaughterhouse Pleurisy Evaluation System [SPES], Consolidation Lung Lesion Score [LLS], Image analyses [IA] and Ratio of lung weight/body weight [LW/BW]) were compared for the assessment of the different pathological outcomes derived from an Actinobacillus pleuropneumoniae (App) experimental infection model. Moreover, pathological data was coupled with clinical (fever, inappetence and clinical score), production (average daily weigh gain [ADWG]) and diagnostic (PCR, ELISA and bacterial isolation) parameters within the four infection outcomes (peracute, acute, subclinically infected and non-infected). Results From the 61 inoculated animals, 9 were classified as peracute (presence of severe App-like clinical signs and lesions and sudden death or euthanasia shortly after inoculation), 31 as acutely affected (presence of App-like clinical signs and lesions and survival until the end of the experiment), 12 as subclinically infected (very mild or no clinical signs but App infection confirmed) and 9 as non-infected animals (lack of App-like clinical signs and lack of evidence of App infection). A significant correlation between all lung lesion scoring systems was found with the exception of SPES score versus LW/BW. SPES showed a statistically significant association with all clinical, production and diagnostic (with the exception of PCR detection of App in the tonsil) variables assessed. LLS and IA showed similar statistically significant associations as SPES, with the exception of seroconversion against App at necropsy. In contrast, LW/BW was statistically associated only with App isolation in lungs, presence of App-like lesions and ELISA OD values at necropsy. Conclusions In conclusion, SPES, LLS and IA are economic, fast and easy-to-perform lung scoring methods that, in combination with different clinical and diagnostic parameters, allow the characterization of different outcomes after App infection. PMID

  7. Macrophages largely contribute to heterologous anti-Propionibacterium acnes antibody-mediated protection from Actinobacillus pleuropneumoniae infection in mice.

    PubMed

    Ma, Qiuyue; Sun, Changjiang; Yang, Feng; Wang, Lei; Qin, Wanhai; Xia, Xiaojing; Feng, Xin; Du, Chongtao; Gu, Jingmin; Han, Wenyu; Lei, Liancheng

    2015-03-01

    Actinobacillus pleuropneumoniae is the causative agent of acute and chronic pleuropneumonia. Propionibacterium acnes is a facultative anaerobic gram-positive corynebacterium. We have previously found that anti-P. acnes antibodies can prevent A. pleuropneumoniae infections in mice. To investigate the role of macrophages in this process, affinity-purified anti-P. acnes IgG and anti-A. pleuropneumoniae IgG were used in opsonophagocytosis assays. Additionally, the efficacy of passive immunization with P. acnes serum against A. pleuropneumoniae was tested in macrophage-depleted mice. It was found that anti-P. acnes IgG had an effect similar to that of anti-A. pleuropneumoniae IgG (P > 0.05), which significantly promotes phagocytosis of A. pleuropneumoniae by macrophages (P < 0.01). It was also demonstrated that, after passive immunization with anti-P. acnes serum, macrophage-replete mice had the highest survival rate (90%), whereas the survival rate of macrophage-depleted mice was only 40% (P < 0.05). However, macrophage-depleted mice that had been passively immunized with naïve serum had the lowest survival rate (20%), this rate being lower than that of macrophage-replete mice that had been passively immunized with naïve serum. Overall, anti-P. acnes antibodies did not prevent A. pleuropneumoniae infection under conditions of macrophage depletion (P > 0.05). Furthermore, in mice that had been passively immunized with anti-P. acnes serum, macrophage depletion resulted in a greater A. pleuropneumoniae burden and more severe pathological features of pneumonia in lung tissues than occurred in macrophage-replete mice. It was concluded that macrophages are essential for the process by which anti-P. acnes antibody prevents A. pleuropneumoniae infection in mice.

  8. Branched-Chain Amino Acids Are Required for the Survival and Virulence of Actinobacillus pleuropneumoniae in Swine▿

    PubMed Central

    Subashchandrabose, Sargurunathan; LeVeque, Rhiannon M.; Wagner, Trevor K.; Kirkwood, Roy N.; Kiupel, Matti; Mulks, Martha H.

    2009-01-01

    In Actinobacillus pleuropneumoniae, which causes porcine pleuropneumonia, ilvI was identified as an in vivo-induced (ivi) gene and encodes the enzyme acetohydroxyacid synthase (AHAS) required for branched-chain amino acid (BCAA) biosynthesis. ilvI and 7 of 32 additional ivi promoters were upregulated in vitro when grown in chemically defined medium (CDM) lacking BCAA. Based on these observations, we hypothesized that BCAA would be found at limiting concentrations in pulmonary secretions and that A. pleuropneumoniae mutants unable to synthesize BCAA would be attenuated in a porcine infection model. Quantitation of free amino acids in porcine pulmonary epithelial lining fluid showed concentrations of BCAA ranging from 8 to 30 μmol/liter, which is 10 to 17% of the concentration in plasma. The expression of both ilvI and lrp, a global regulator that is required for ilvI expression, was strongly upregulated in CDM containing concentrations of BCAA similar to those found in pulmonary secretions. Deletion-disruption mutants of ilvI and lrp were both auxotrophic for BCAA in CDM and attenuated compared to wild-type A. pleuropneumoniae in competitive index experiments in a pig infection model. Wild-type A. pleuropneumoniae grew in CDM+BCAA but not in CDM−BCAA in the presence of sulfonylurea AHAS inhibitors. These results clearly demonstrate that BCAA availability is limited in the lungs and support the hypothesis that A. pleuropneumoniae, and potentially other pulmonary pathogens, uses limitation of BCAA as a cue to regulate the expression of genes required for survival and virulence. These results further suggest a potential role for AHAS inhibitors as antimicrobial agents against pulmonary pathogens. PMID:19703979

  9. Effects of Areca Nut Extracts on Phagocytosis of Actinobacillus actinomycete mcomitans ATCC 33384 by Neutrophils in Patients with Chronic Periondontitis

    PubMed Central

    Patil, Kavita Gangaram; Metgud, Sharada Chidanand

    2013-01-01

    Background & Objective: A higher prevalence of periodontal disease among areca nut chewers than non chewers has been demonstrated. Neutrophils, the first line of defence mechanism against microbial infection play an important role in maintaining the periodontal health. In this context our aim was to evaluate the effects of areca nut extracts on phagocytic activity by neutrophils isolated from gingival crevicular washing of healthy subjects and patients with chronic periodontitis. Material and Methods: Sample size consisted of a total of 60 subjects which were divided into two groups of 30 each. Group I consisted healthy subjects and Group II consisted clinically diagnosed cases of chronic periodontitis. Neutrophils isolated from gingival crevicular washings of both groups were treated with aqueous extracts of ripe areca nut (rANE) and tender areca nut (tANE) and examined for their effect on cellular viability of neutrophils using typan blue exclusion assay. The possible/ ableffects on the phagocytic activity of neutrophils against a periodontal pathogen Aggregatibacter actinomycetemcomitans(ATCC 33384) was determined by using microscopic method. Results: Both rANE and tANE affected the phagocytic activity by neutrophils in healthy and patients with chronic periodontitis. Ripe areca nut extract has altered the neutrophil functions more than tender areca nut in both the groups. There was no difference seen in the cell viability of neutrophils when treated with rANE and tANE in both the groups (p> 0.05). Conclusion: Both ripe and tender arecanut extract affected the neutrophil function in healthy and patients with chronic periodontitis. Ripe arecanut extract significantly altered the neutrophils functions more than tender areca nut extract. Thus, alterations in these functions of neutrophils may lead to signs of clinical diseases associated with areca chewing. PMID:24298462

  10. A 24-kDa cloned zinc metalloprotease from Actinobacillus pleuropneumoniae is common to all serotypes and cleaves actin in vitro.

    PubMed Central

    García-Cuéllar, C; Montañez, C; Tenorio, V; Reyes-Esparza, J; Durán, M J; Negrete, E; Guerrero, A; de la Garza, M

    2000-01-01

    Actinobacillus pleuropneumoniae causes pleuropneumonia in swine. This bacterium secretes proteases that degrade porcine hemoglobin and IgA in vitro. To further characterize A. pleuropneumoniae proteases, we constructed a genomic library expressed in Escherichia coli DH5alpha, and selected a clone that showed proteolytic activity. The recombinant plasmid carries an 800-base pair A. pleuropneumoniae gene sequence that.codes for a 24-kDa polypeptide. A 350-base pair PstI fragment from the sequence hybridized at high stringency with DNA from 12 serotypes of A. pleuropneumoniae, but not with DNA from Actinobacillus suis, Haemophilus parasuis, Pasteurella haemolytica, Pasteurella multocida A or D, or E. coli DH5alpha, thus showing specificity for A. pleuropneumoniae. The expressed polypeptide was recognized as an antigen by convalescent-phase pig sera. Furthermore, a polyclonal antiserum developed against the purified polypeptide recognized an A. pleuropneumoniae oligomeric protein in both crude-extract and cell-free culture media. This recombinant polypeptide cleaved azocoll, gelatin, and actin. Inhibition of the proteolytic activity by diethylpyrocarbonate suggests that this polypeptide is a zinc metalloprotease. Images Figure 1. Figure 2. Figure 3. Figure 4. Figure 6. Figure 7. PMID:10805246

  11. Determination of antibacterial activity of green coffee bean extract on periodontogenic bacteria like Porphyromonas gingivalis, Prevotella intermedia, Fusobacterium nucleatum and Aggregatibacter actinomycetemcomitans: An in vitro study

    PubMed Central

    Bharath, Nagaraj; Sowmya, Nagur Karibasappa; Mehta, Dhoom Singh

    2015-01-01

    Background: The aim of this study was to evaluate the antibacterial activity of pure green coffee bean extract on periodonto pathogenic bacteria Porphyromonas gingivalis (Pg), Prevotella intermedia (Pi), Fusobacterium nucleatum (Fn) and Aggregatibacter actinomycetemcomitans (Aa). Materials and Methods: Minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBC) were used to assess the antibacterial effect of pure green coffee bean extract against periodonto pathogenic bacteria by micro dilution method and culture method, respectively. Results: MIC values of Pg, Pi and Aa were 0.2 μg/ml whereas Fn showed sensitive at concentration of 3.125 μg/ml. MBC values mirrors the values same as that of MIC. Conclusion: Antimicrobial activity of pure green coffee bean extract against Pg, Pi, Fn and Aa suggests that it could be recommended as an adjunct to mechanical therapy in the management of periodontal disease. PMID:26097349

  12. Lipopolysaccharide of Aggregatibacter actinomycetemcomitans induces the expression of chemokines MCP-1, MIP-1α, and IP-10 via similar but distinct signaling pathways in murine macrophages.

    PubMed

    Park, Ok-Jin; Cho, Min-Kyung; Yun, Cheol-Heui; Han, Seung Hyun

    2015-09-01

    Aggregatibacter actinomycetemcomitans is a Gram-negative bacterium frequently isolated from lesions of patients with localized aggressive periodontitis. Lipopolysaccharide (LPS), a major cell wall component of Gram-negative bacteria, stimulates innate immune cells via Toll-like receptor 4 (TLR4) to initiate inflammatory responses. In this study, we purified LPS from A. actinomycetemcomitans (AaLPS) and investigated its ability to induce the expression of chemokines, which play an important role in recruitment of leukocytes to the infection site. AaLPS induced the expression of chemokines, MCP-1, MIP-1α, and IP-10 in murine macrophages, leading to the infiltration of peripheral blood mononuclear cells in a transwell system. Although TLR4 was essential for the induction of all these chemokines by AaLPS, MCP-1 and MIP-1α expressions were MyD88-dependent, but IP-10 expression was MyD88-independent, as determined using macrophages from mice deficient in TLR4 or MyD88. Furthermore, the activation of ERK and JNK were necessary for the expression of MCP-1 and MIP-1α, whereas p38 MAP kinase and JNK activations were required for IP-10 expression. In addition, IFN-β/STAT1 signaling was exclusively involved in IP-10 expression but not in MCP-1 or MIP-1α expression. AaLPS also activated the transcription factors, NF-κB, AP-1, NF-IL6, and ISRE, all of which are involved in chemokine gene expression. These results suggest that AaLPS induces the expression of chemokines MCP-1, MIP-1α, and IP-10 through TLR4 in murine macrophages. Further, the induction of MCP-1 and MIP-1α requires MyD88, ERK, and JNK, whereas the induction of IP-10 requires JNK, p38 MAP kinase, and IFN-β/STAT1.

  13. A novel intrinsically disordered outer membrane lipoprotein of Aggregatibacter actinomycetemcomitans binds various cytokines and plays a role in biofilm response to interleukin-1β and interleukin-8

    PubMed Central

    Ahlstrand, Tuuli; Tuominen, Heidi; Beklen, Arzu; Torittu, Annamari; Oscarsson, Jan; Sormunen, Raija; Pöllänen, Marja T.; Permi, Perttu; Ihalin, Riikka

    2017-01-01

    ABSTRACT Intrinsically disordered proteins (IDPs) do not have a well-defined and stable 3-dimensional fold. Some IDPs can function as either transient or permanent binders of other proteins and may interact with an array of ligands by adopting different conformations. A novel outer membrane lipoprotein, bacterial interleukin receptor I (BilRI) of the opportunistic oral pathogen Aggregatibacter actinomycetemcomitans binds a key gatekeeper proinflammatory cytokine interleukin (IL)-1β. Because the amino acid sequence of the novel lipoprotein resembles that of fibrinogen binder A of Haemophilus ducreyi, BilRI could have the potential to bind other proteins, such as host matrix proteins. However, from the tested host matrix proteins, BilRI interacted with neither collagen nor fibrinogen. Instead, the recombinant non-lipidated BilRI, which was intrinsically disordered, bound various pro/anti-inflammatory cytokines, such as IL-8, tumor necrosis factor (TNF)-α, interferon (IFN)-γ and IL-10. Moreover, BilRI played a role in the in vitro sensing of IL-1β and IL-8 because low concentrations of cytokines did not decrease the amount of extracellular DNA in the matrix of bilRI− mutant biofilm as they did in the matrix of wild-type biofilm when the biofilms were exposed to recombinant cytokines for 22 hours. BilRI played a role in the internalization of IL-1β in the gingival model system but did not affect either IL-8 or IL-6 uptake. However, bilRI deletion did not entirely prevent IL-1β internalization, and the binding of cytokines to BilRI was relatively weak. Thus, BilRI might sequester cytokines on the surface of A. actinomycetemcomitans to facilitate the internalization process in low local cytokine concentrations. PMID:27459270

  14. A novel intrinsically disordered outer membrane lipoprotein of Aggregatibacter actinomycetemcomitans binds various cytokines and plays a role in biofilm response to interleukin-1β and interleukin-8.

    PubMed

    Ahlstrand, Tuuli; Tuominen, Heidi; Beklen, Arzu; Torittu, Annamari; Oscarsson, Jan; Sormunen, Raija; Pöllänen, Marja T; Permi, Perttu; Ihalin, Riikka

    2017-02-17

    Intrinsically disordered proteins (IDPs) do not have a well-defined and stable 3-dimensional fold. Some IDPs can function as either transient or permanent binders of other proteins and may interact with an array of ligands by adopting different conformations. A novel outer membrane lipoprotein, bacterial interleukin receptor I (BilRI) of the opportunistic oral pathogen Aggregatibacter actinomycetemcomitans binds a key gatekeeper proinflammatory cytokine interleukin (IL)-1β. Because the amino acid sequence of the novel lipoprotein resembles that of fibrinogen binder A of Haemophilus ducreyi, BilRI could have the potential to bind other proteins, such as host matrix proteins. However, from the tested host matrix proteins, BilRI interacted with neither collagen nor fibrinogen. Instead, the recombinant non-lipidated BilRI, which was intrinsically disordered, bound various pro/anti-inflammatory cytokines, such as IL-8, tumor necrosis factor (TNF)-α, interferon (IFN)-γ and IL-10. Moreover, BilRI played a role in the in vitro sensing of IL-1β and IL-8 because low concentrations of cytokines did not decrease the amount of extracellular DNA in the matrix of bilRI(-) mutant biofilm as they did in the matrix of wild-type biofilm when the biofilms were exposed to recombinant cytokines for 22 hours. BilRI played a role in the internalization of IL-1β in the gingival model system but did not affect either IL-8 or IL-6 uptake. However, bilRI deletion did not entirely prevent IL-1β internalization, and the binding of cytokines to BilRI was relatively weak. Thus, BilRI might sequester cytokines on the surface of A. actinomycetemcomitans to facilitate the internalization process in low local cytokine concentrations.

  15. In vitro sensitivity of oral, gram-negative, facultative bacteria to the bactericidal activity of human neutrophil defensins.

    PubMed Central

    Miyasaki, K T; Bodeau, A L; Ganz, T; Selsted, M E; Lehrer, R I

    1990-01-01

    Neutrophils play a major role in defending the periodontium against infection by oral, gram-negative, facultative bacteria, such as Actinobacillus actinomycetemcomitans, Eikenella corrodens, and Capnocytophaga spp. We examined the sensitivity of these bacteria to a mixture of low-molecular-weight peptides and highly purified individual defensin peptides (HNP-1, HNP-2, and HNP-3) isolated from human neutrophils. Whereas the Capnocytophaga spp. strains were killed significantly by the mixed human neutrophil peptides, the A. actinomycetemcomitans and E. corrodens strains were resistant. Killing was attributable to the defensins. The bactericidal activities of purified defensins HNP-1 and HNP-2 were equal, and both of these activities were greater than HNP-3 activity against strains of Capnocytophaga sputigena and Capnocytophaga gingivalis. The strain of Capnocytophaga ochracea was more sensitive to defensin-mediated bactericidal activity than either C. sputigena or C. gingivalis was. The three human defensins were equipotent in killing C. ochracea. C. ochracea was killed under aerobic and anaerobic conditions and over a broad pH range. Killing was most effective under hypotonic conditions but also occurred at physiologic salt concentrations. We concluded that Capnocytophaga spp. are sensitive to oxygen-independent killing by human defensins. Additional studies will be required to identify other components that may equip human neutrophils to kill A. actinomycetemcomitans, E. corrodens, and other oral gram-negative bacteria. Images PMID:2254020

  16. Natural Strain

    NASA Technical Reports Server (NTRS)

    Freed, Alan D.

    1995-01-01

    The purpose of this paper is to present a consistent and thorough development of the strain and strain-rate measures affiliated with Hencky. Natural measures for strain and strain-rate, as I refer to them, are first expressed in terms of of the fundamental body-metric tensors of Lodge. These strain and strain-rate measures are mixed tensor fields. They are mapped from the body to space in both the Eulerian and Lagrangian configurations, and then transformed from general to Cartesian fields. There they are compared with the various strain and strain-rate measures found in the literature. A simple Cartesian description for Hencky strain-rate in the Lagrangian state is obtained.

  17. Detection of Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans after Systemic Administration of Amoxicillin Plus Metronidazole as an Adjunct to Non-surgical Periodontal Therapy: A Systematic Review and Meta-Analysis

    PubMed Central

    Dakic, Aleksandar; Boillot, Adrien; Colliot, Cyrille; Carra, Maria-Clotilde; Czernichow, Sébastien; Bouchard, Philippe

    2016-01-01

    Objective: To evaluate the variations in the detection of Porphyromonas gingivalis and/or Aggregatibacter actinomycetemcomitans before and after systemic administration of amoxicillin plus metronidazole in association with non-surgical periodontal therapy (NSPT). Background: The adjunctive use of antibiotics has been advocated to improve the clinical outcomes of NSPT. However, no systematic review has investigated the microbiological benefit of this combination. Materials and Methods: An electronic search was conducted up to December 2015. Randomized clinical trials comparing the number of patients testing positive for P. gingivalis and/or A. actinomycetemcomitans before and after NSPT with (test group) or without (control group) amoxicillin plus metronidazole were included. The difference between groups in the variation of positive patients was calculated using the inverse variance method with a random effects model. Results: The frequency of patients positive for A. actinomycetemcomitans was decreased by 30% (p = 0.002) and by 25% (p = 0.01) in the test group compared to the control group at 3- and 6-month follow-up, respectively. Similar findings were observed when considering the frequency of patients positive for Porphyromonas gingivalis, with a reduction by 28% (p < 0.0001), 32% (p < 0.0001), and 34% (p = 0.03) in the test group compared to the control group at 3-, 6-, and 12-month follow-up, respectively. Conclusion: The systemic administration of amoxicillin plus metronidazole as an adjunct to NSPT significantly decreased the number of patients positive for P. gingivalis and A. actinomycetemcomitans compared with periodontal therapy alone or with a placebo. PMID:27594851

  18. Utilization of Electrically Reduced Neutral Red by Actinobacillus succinogenes: Physiological Function of Neutral Red in Membrane-Driven Fumarate Reduction and Energy Conservation

    PubMed Central

    Park, D. H.; Zeikus, J. G.

    1999-01-01

    Neutral red (NR) functioned as an electronophore or electron channel enabling either cells or membranes purified from Actinobacillus succinogenes to drive electron transfer and proton translocation by coupling fumarate reduction to succinate production. Electrically reduced NR, unlike methyl or benzyl viologen, bound to cell membranes, was not toxic, and chemically reduced NAD. The cell membrane of A. succinogenes contained high levels of benzyl viologen-linked hydrogenase (12.2 U), fumarate reductase (13.1 U), and diaphorase (109.7 U) activities. Fumarate reductase (24.5 U) displayed the highest activity with NR as the electron carrier, whereas hydrogenase (1.1 U) and diaphorase (0.8 U) did not. Proton translocation by whole cells was dependent on either electrically reduced NR or H2 as the electron donor and on the fumarate concentration. During the growth of Actinobacillus on glucose plus electrically reduced NR in an electrochemical bioreactor system versus on glucose alone, electrically reduced NR enhanced glucose consumption, growth, and succinate production by about 20% while it decreased acetate production by about 50%. The rate of fumarate reduction to succinate by purified membranes was twofold higher with electrically reduced NR than with hydrogen as the electron donor. The addition of 2-(n-heptyl)-4-hydroxyquinoline N-oxide to whole cells or purified membranes inhibited succinate production from H2 plus fumarate but not from electrically reduced NR plus fumarate. Thus, NR appears to replace the function of menaquinone in the fumarate reductase complex, and it enables A. succinogenes to utilize electricity as a significant source of metabolic reducing power. PMID:10198002

  19. Strain Gage

    NASA Technical Reports Server (NTRS)

    1995-01-01

    HITEC Corporation developed a strain gage application for DanteII, a mobile robot developed for NASA. The gage measured bending forces on the robot's legs and warned human controllers when acceptable forces were exceeded. HITEC further developed the technology for strain gage services in creating transducers out of "Indy" racing car suspension pushrods, NASCAR suspension components and components used in motion control.

  20. The Aggregatibacter actinomycetemcomitans Cytolethal Distending Toxin Active Subunit CdtB Contains a Cholesterol Recognition Sequence Required for Toxin Binding and Subunit Internalization.

    PubMed

    Boesze-Battaglia, Kathleen; Walker, Lisa P; Zekavat, Ali; Dlakić, Mensur; Scuron, Monika Damek; Nygren, Patrik; Shenker, Bruce J

    2015-10-01

    Induction of cell cycle arrest in lymphocytes following exposure to the Aggregatibacter actinomycetemcomitans cytolethal distending toxin (Cdt) is dependent upon the integrity of lipid membrane microdomains. Moreover, we have previously demonstrated that the association of Cdt with target cells involves the CdtC subunit which binds to cholesterol via a cholesterol recognition amino acid consensus sequence (CRAC site). In this study, we demonstrate that the active Cdt subunit, CdtB, also is capable of binding to large unilamellar vesicles (LUVs) containing cholesterol. Furthermore, CdtB binding to cholesterol involves a similar CRAC site as that demonstrated for CdtC. Mutation of the CRAC site reduces binding to model membranes as well as toxin binding and CdtB internalization in both Jurkat cells and human macrophages. A concomitant reduction in Cdt-induced toxicity was also noted, indicated by reduced cell cycle arrest and apoptosis in Jurkat cells and a reduction in the proinflammatory response in macrophages (interleukin 1β [IL-1β] and tumor necrosis factor alpha [TNF-α] release). Collectively, these observations indicate that membrane cholesterol serves as an essential ligand for both CdtC and CdtB and, further, that this binding is necessary for both internalization of CdtB and subsequent molecular events leading to intoxication of cells.

  1. MicroRNAs responsive to Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis LPS modulate expression of genes regulating innate immunity in human macrophages.

    PubMed

    Naqvi, Afsar R; Fordham, Jezrom B; Khan, Asma; Nares, Salvador

    2014-07-01

    MicroRNAs (miRNAs) are a class of small, noncoding RNAs that regulate post-transcriptional expression of their respective target genes and are responsive to various stimuli, including LPS. Here we examined the early (4 h) miRNA responses of THP1-differentiated macrophages challenged with LPS derived from the periodontal pathogens, Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis or environmentally-modified LPS obtained from P. gingivalis grown in cigarette smoke extract. Predicted miRNA-gene target interactions for LPS-responsive miR-29b and let-7f were confirmed using dual-luciferase assays and by transfection experiments using miRNA mimics and inhibitors. Convergent and divergent miRNA profiles were observed in treated samples where differences in miRNA levels related to the type, concentration and incubation times of LPS challenge. Dual-luciferase experiments revealed miR-29b targeting of interleukin-6 receptorα (IL-6Rα) and IFN-γ inducible protein 30 and let-7f targeting of suppressor of cytokine signaling 4 and thrombospondin-1. Transfection experiments confirmed miR-29b and let-7f modulation of IL-6Rα and SOCS4 protein expression levels, respectively. Thus, we have demonstrated convergent/divergent miRNA responses to wild type LPS and its environmentally-modified LPS, and demonstrate miRNA targeting of key genes linked to inflammation and immunity. Our data indicate that these LPS-responsive miRNAs may play a key role in fine-tuning the host response to periodontal pathogens.

  2. Periodontitis‐associated pathogens P. gingivalis and A. actinomycetemcomitans activate human CD14+ monocytes leading to enhanced Th17/IL‐17 responses

    PubMed Central

    Cheng, Wan‐Chien; van Asten, Saskia D.; Burns, Lachrissa A.; Evans, Hayley G.; Walter, Gina J.; Hashim, Ahmed; Hughes, Francis J.

    2016-01-01

    The Th17/IL‐17 pathway is implicated in the pathogenesis of periodontitis (PD), however the mechanisms are not fully understood. We investigated the mechanism by which the periodontal pathogens Porphyromonas gingivalis (Pg) and Aggregatibacter actinomycetemcomitans (Aa) promote a Th17/IL‐17 response in vitro, and studied IL‐17+ CD4+ T‐cell frequencies in gingival tissue and peripheral blood from patients with PD versus periodontally healthy controls. Addition of Pg or Aa to monocyte/CD4+ T‐cell co‐cultures promoted a Th17/IL‐17 response in vitro in a dose‐ and time‐dependent manner. Pg or Aa stimulation of monocytes resulted in increased CD40, CD54 and HLA‐DR expression, and enhanced TNF‐α, IL‐1β, IL‐6 and IL‐23 production. Mechanistically, IL‐17 production in Pg‐stimulated co‐cultures was partially dependent on IL‐1β, IL‐23 and TLR2/TLR4 signalling. Increased frequencies of IL‐17+ cells were observed in gingival tissue from patients with PD compared to healthy subjects. No differences were observed in IL‐17+ CD4+ T‐cell frequencies in peripheral blood. In vitro, Pg induced significantly higher IL‐17 production in anti‐CD3 mAb‐stimulated monocyte/CD4+ T‐cell co‐cultures from patients with PD compared to healthy controls. Our data suggest that periodontal pathogens can activate monocytes, resulting in increased IL‐17 production by human CD4+ T cells, a process that appears enhanced in patients with PD. PMID:27334899

  3. Correlation of Aggregatibacter actinomycetemcomitans Detection with Clinical/Immunoinflammatory Profile of Localized Aggressive Periodontitis Using a 16S rRNA Microarray Method: A Cross-Sectional Study

    PubMed Central

    Gonçalves, Patricia F.; Klepac-Ceraj, Vanja; Huang, Hong; Paster, Bruce J.; Aukhil, Ikramuddin; Wallet, Shannon M.; Shaddox, Luciana M.

    2013-01-01

    Objective The objective of this study was to determine whether the detection of Aggregatibacter actinomycetemcomitans (Aa) correlates with the clinical and immunoinflammatory profile of Localized Aggressive Periodontitis (LAP), as determined by by 16S rRNA gene-based microarray. Subjects and Methods Subgingival plaque samples from the deepest diseased site of 30 LAP patients [PD ≥ 5 mm, BoP and bone loss] were analyzed by 16S rRNA gene-based microarrays. Gingival crevicular fluid (GCF) samples were analyzed for 14 cyto/chemokines. Peripheral blood was obtained and stimulated in vitro with P.gingivalis and E.coli to evaluate inflammatory response profiles. Plasma lipopolysaccharide (LPS) levels were also measured. Results Aa was detected in 56% of LAP patients and was shown to be an indicator for different bacterial community structures (p<0.01). Elevated levels of pro-inflammatory cyto/chemokines were detected in LPS-stimulated blood samples in both Aa-detected and Aa-non-detected groups (p>0.05). Clinical parameters and serum LPS levels were similar between groups. However, Aa-non-detected GCF contained higher concentration of IL-8 than Aa-detected sites (p<0.05). TNFα and IL1β were elevated upon E.coli LPS stimulation of peripheral blood cells derived from patients with Aa-detected sites. Conclusions Our findings demonstrate that the detection of Aa in LAP affected sites, did not correlate with clinical severity of the disease at the time of sampling in this cross-sectional study, although it did associate with lower local levels of IL-8, a different subgingival bacterial profile and elevated LPS-induced levels of TNFα and IL1β. PMID:24376864

  4. No overall relationship between average daily weight gain and the serological response to Mycoplasma hyopneumoniae and Actinobacillus pleuropneumoniae in eight chronically infected Danish swine herds.

    PubMed

    Andreasen, M; Mousing, J; Thomsen, L K

    2001-04-13

    The association between the average daily weight gain (from approximately 4 to 20 weeks of age) and the serological responses to respiratory infections was examined in a longitudinal study including 825 pigs from eight chronically infected herds. Pigs were bled every 4th week (starting from approximately 4 weeks of age), and sera were analyzed for antibodies to Mycoplasma hyopneumoniae and Actinobacillus pleuropneumoniae serotypes 2, 5-7 and 12.Mixed analysis of covariance analyzed the relationship between the average daily weight gain and a categorical variable defining seroconversion as none, early or late as compared to the median time (estimated across herds) of seroconversion for the particular pathogen. The variables "gender", "weight at an approximate age of 4 weeks" and "time" (defining the exact length of the follow-up period), were included as explanatory variables, and "litter" and "herd" were included as explanatory random variables. The individual pig was the unit of concern. The variable defining time at seroconversion was not significantly associated with the average daily weight gain, when evaluating models across all eight herds. The apparent lack of effect could be because most pigs included in the study were subclinically infected, or because a temporary negative influence of the infections is hidden due to an increased growth in the period following infection. In conclusion, at least in these eight herds, seroresponses to M. hyopneumoniae and A. pleuropneumoniae could not be used to predict the effect of the pathogens on the daily weight gain.

  5. Variation in the Antimicrobial Susceptibility of Actinobacillus pleuropneumoniae Isolates in a Pig, Within a Batch of Pigs, and Among Batches of Pigs from One Farm.

    PubMed

    Dayao, Denise Ann E; Dawson, Susan; Kienzle, Marco Jean-Paul; Gibson, Justine S; Blackall, Patrick J; Turni, Conny

    2015-08-01

    Antimicrobial resistance in bacterial porcine respiratory pathogens has been shown to exist in many countries. However, little is known about the variability in antimicrobial susceptibility within a population of a single bacterial respiratory pathogen on a pig farm. This study examined the antimicrobial susceptibility of Actinobacillus pleuropneumoniae using multiple isolates within a pig and across the pigs in three different slaughter batches. Initially, the isolates from the three batches were identified, serotyped, and subsample genotyped. All the 367 isolates were identified as A. pleuropneumoniae serovar 1, and only a single genetic profile was detected in the 74 examined isolates. The susceptibility of the 367 isolates of A. pleuropneumoniae to ampicillin, tetracycline and tilmicosin was determined by a disc diffusion technique. For tilmicosin, the three batches were found to consist of a mix of susceptible and resistant isolates. The zone diameters of the three antimicrobials varied considerably among isolates in the second sampling. In addition, the second sampling provided statistically significant evidence of bimodal populations in terms of zone diameters for both tilmicosin and ampicillin. The results support the hypothesis that the antimicrobial susceptibility of one population of a porcine respiratory pathogen can vary within a batch of pigs on a farm.

  6. Mitogen-activated protein kinases p38 and JNK mediate Actinobacillus pleuropneumoniae exotoxin ApxI-induced apoptosis in porcine alveolar macrophages.

    PubMed

    Wu, Chi-Ming; Chen, Zeng-Weng; Chen, Ter-Hsin; Liao, Jiunn-Wang; Lin, Cheng-Chung; Chien, Maw-Sheng; Lee, Wei-Cheng; Hsuan, Shih-Ling

    2011-08-05

    Actinobacillus pleuropneumoniae exotoxins (Apx) are major virulence factors that play important roles in the pathogenesis of pleuropneumonia in swine. A previous study has demonstrated that native ApxI at low concentrations induces apoptosis in primary porcine alveolar macrophages (PAMs) via a caspase-3-dependent pathway. However, the molecular mechanisms underlying ApxI-induced apoptosis remain largely unknown. In this study, it was shown that ApxI treatment in PAMs rapidly induced phosphorylation of both p38 and JNK, members of the mitogen-activated protein kinase family. Application of a selective p38 or JNK inhibitor significantly reduced ApxI-induced apoptosis, indicating the involvement of p38 and JNK pathways in this event. Furthermore, activation of both caspase-8 and -9 were observed in ApxI-stimulated PAMs. Inhibition of caspase-8 and caspase-9 activity significantly protected PAMs from ApxI-induced apoptosis. In addition, Bid activation was also noted in ApxI-treated PAMs, and inhibition of caspase-8 suppressed the activation of Bid and caspase-9, suggesting that ApxI was able to activate the caspases-8-Bid-caspase-9 pathway. Notably, inhibition of p38 or JNK pathway greatly attenuated the activation of caspases-3, -8, and -9. This study is the first to demonstrate that ApxI-induced apoptosis of PAMs involves the activation of p38 and JNK, and engages the extrinsic and intrinsic apoptotic pathways.

  7. Pharmacokinetic/pharmacodynamic evaluation of marbofloxacin in the treatment of Haemophilus parasuis and Actinobacillus pleuropneumoniae infections in nursery and fattener pigs using Monte Carlo simulations.

    PubMed

    Vilalta, C; Giboin, H; Schneider, M; El Garch, F; Fraile, L

    2014-12-01

    This study evaluated the theoretical clinical outcome of three marbofloxacin posology regimens in two groups of pigs (weaners and fatteners) for the treatment of Actinobacillus pleuropneumoniae (App) and Haemophilus parasuis (Hp) infection and the appearance of resistant bacteria due to the antibiotic treatment. The probability of target attainment (PTA) for pharmacokinetic/pharmacodynamics (PK/PD) ratios associated with clinical efficacy and with the appearance of antimicrobial resistance for fluoroquinolones at each minimum inhibitory concentration (MIC) or mutant prevention concentration (MPC) were calculated, respectively. The cumulative fraction of response (CFR) was calculated for the three posology regimens against App and they ranged from 91.12% to 96.37% in weaners and from 93% to 97.43% in fatteners, respectively. In the case of Hp, they ranged from 80.52% to 85.14% in weaners and from 82.01% to 88.49% in fatteners, respectively. Regarding the PTA of the PK/PD threshold associated with the appearance of antimicrobial resistance, results showed that marbofloxacin would prevent resistances in most of the animals up to the MPC value of 1 μg/mL.

  8. Bacteriocin production by Fusobacterium isolates recovered from the oral cavity of human subjects with and without periodontal disease and of marmosets.

    PubMed

    Oliveira, A A; Farias, L M; Nicoli, J R; Costa, J E; Carvalho, M A

    1998-09-01

    Bacteriocin production has been studied in very few anaerobic bacteria, and no report is available for Fusobacterium species. In the present study a total of 167 Fusobacterium isolates were tested for bacteriocin production: 70 isolates were obtained from the oral cavity of patients with periodontal disease, 47 were recovered from healthy oral sites of human subjects and 50 from the oral cavity of Callithrix penicillata. Autoantagonism and isoantagonism were observed when the bacteriocin-producing isolates were tested against themselves. Heteroantagonism was detected by testing the Fusobacterium isolates against 14 reference strains and 2 strains of Actinobacillus actinomycetemcomitans from our laboratory collection. The auto-, iso- and heteroantagonism phenomena observed in this comparative study suggest a possible ecological role for this (these) antagonistic substance(s) in the oral environment.

  9. Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, and Treponema denticola / Prevotella intermedia Co-Infection Are Associated with Severe Periodontitis in a Thai Population.

    PubMed

    Torrungruang, Kitti; Jitpakdeebordin, Supawadee; Charatkulangkun, Orawan; Gleebbua, Yingampa

    2015-01-01

    Periodontitis is a polymicrobial infection of tooth-supporting tissues. This cross-sectional study aimed to examine the associations between five target species and severe periodontitis in a Thai population. Using the CDC/AAP case definition, individuals diagnosed with no/mild and severe periodontitis were included. Quantitative analyses of Aggregatibacter actinomycetemcomitans (Aa), Porphyromonas gingivalis (Pg), Tannerella forsythia (Tf), Treponema denticola (Td), and Prevotella intermedia (Pi) in subgingival plaque were performed using real-time polymerase chain reaction. The association between target species and severe periodontitis was examined using logistic regression analysis. The study subjects comprised 479 individuals with no/mild periodontitis and 883 with severe periodontitis. Bacterial prevalence and quantity were higher in subjects with severe periodontitis than in those with no/mild disease. In the fully adjusted model, all species except Tf showed a dose-dependent relationship with periodontitis. The mere presence of Pg, even in low amount, was significantly associated with severe periodontitis, while the amount of Aa, Td, and Pi had to reach the critical thresholds to be significantly associated with disease. Compared to individuals with low levels of both Td and Pi, high colonization by either Td or Pi alone significantly increased the odds of having severe periodontitis by 2.5 (95%CI 1.7-3.5) folds. The odds ratio was further increased to 14.8 (95%CI 9.2-23.8) in individuals who were highly colonized by both species. Moreover, the presence of Pg and high colonization by Aa were independently associated with severe periodontitis with odds ratios of 5.6 (95%CI 3.4-9.1) and 2.2 (95%CI 1.5-3.3), respectively. Our findings suggest that the presence of Pg and high colonization by Aa, Td, and Pi play an important role in severe periodontitis in this study population. We also demonstrate for the first time that individuals co-infected with Td and Pi

  10. Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, and Treponema denticola / Prevotella intermedia Co-Infection Are Associated with Severe Periodontitis in a Thai Population

    PubMed Central

    Torrungruang, Kitti; Jitpakdeebordin, Supawadee; Charatkulangkun, Orawan; Gleebbua, Yingampa

    2015-01-01

    Periodontitis is a polymicrobial infection of tooth-supporting tissues. This cross-sectional study aimed to examine the associations between five target species and severe periodontitis in a Thai population. Using the CDC/AAP case definition, individuals diagnosed with no/mild and severe periodontitis were included. Quantitative analyses of Aggregatibacter actinomycetemcomitans (Aa), Porphyromonas gingivalis (Pg), Tannerella forsythia (Tf), Treponema denticola (Td), and Prevotella intermedia (Pi) in subgingival plaque were performed using real-time polymerase chain reaction. The association between target species and severe periodontitis was examined using logistic regression analysis. The study subjects comprised 479 individuals with no/mild periodontitis and 883 with severe periodontitis. Bacterial prevalence and quantity were higher in subjects with severe periodontitis than in those with no/mild disease. In the fully adjusted model, all species except Tf showed a dose-dependent relationship with periodontitis. The mere presence of Pg, even in low amount, was significantly associated with severe periodontitis, while the amount of Aa, Td, and Pi had to reach the critical thresholds to be significantly associated with disease. Compared to individuals with low levels of both Td and Pi, high colonization by either Td or Pi alone significantly increased the odds of having severe periodontitis by 2.5 (95%CI 1.7–3.5) folds. The odds ratio was further increased to 14.8 (95%CI 9.2–23.8) in individuals who were highly colonized by both species. Moreover, the presence of Pg and high colonization by Aa were independently associated with severe periodontitis with odds ratios of 5.6 (95%CI 3.4–9.1) and 2.2 (95%CI 1.5–3.3), respectively. Our findings suggest that the presence of Pg and high colonization by Aa, Td, and Pi play an important role in severe periodontitis in this study population. We also demonstrate for the first time that individuals co-infected with Td

  11. Actinobacillus pleuropneumoniae is impaired by the garlic volatile allyl methyl sulfide (AMS) in vitro and in-feed garlic alleviates pleuropneumonia in a pig model.

    PubMed

    Becker, Petra M; van Wikselaar, Piet G; Mul, Monique F; Pol, Arjan; Engel, Bas; Wijdenes, Jan W; van der Peet-Schwering, Carola M C; Wisselink, Henk J; Stockhofe-Zurwieden, Norbert

    2012-01-27

    Decomposition products of ingested garlic are to a certain extent excreted via the lungs. If the supposed health-supporting capacities associated with garlic extend to these exhaled sulfurous compounds, they could have an effect on the course of pneumonia. In this study, the garlic-derived volatile allyl methyl sulfide (AMS) as a lead compound of volatile garlic metabolites was shown to exhibit an antibacterial effect against the pig pathogen Actinobacillus pleuropneumoniae serotype 9. AMS caused a delay in the appearance of the optical density-monitored growth of A. pleuropneumoniae in medium when compared to unaffected growth curves, yet without lowering the stationary phase yield at the concentration range tested. At 1.1mM, AMS impaired the in vitro growth rate of A. pleuropneumoniae serotype 9 by 8% compared to unimpeded growth. In an animal trial, a garlic-fed group of 15 pigs that received a diet with 5% garlic feed component and a control group of 15 pigs that received a diet without garlic were infected with A. pleuropneumoniae serotype 2 via an aerosol and subsequently followed for 4 days. At the day of the challenge, blood AMS in the garlic-fed group amounted to 0.32 ± 0.13 μM. A beneficial, alleviating effect of garlic on the course and severity of an A. pleuropneumoniae infection in pigs was indicated by the reduced occurrence of characteristic pleuropneumonia lesions (27% of the lungs affected in the garlic-fed group vs. 47% in the control group) and a near to significant (p=0.06) lower relative lung weight post mortem in the garlic-fed group.

  12. DNA vaccine encoding type IV pilin of Actinobacillus pleuropneumoniae induces strong immune response but confers limited protective efficacy against serotype 2 challenge.

    PubMed

    Lu, Yu-Chun; Li, Min-Chen; Chen, Yi-Min; Chu, Chun-Yen; Lin, Shuen-Fuh; Yang, Wen-Jen

    2011-10-13

    Actinobacillus pleuropneumoniae is a gram-negative bacterial pathogen that causes swine pleuropneumonia, a highly contagious and often fatal disease that occurs worldwide. Our previous study showed that DNA vaccines encoding Apx exotoxin structural proteins ApxIA and/or ApxIIA, are a promising novel approach for immunization against the lethal challenge of A. pleuropneumoniae serotype 1. Vaccination against A. pleuropneumoniae is impeded by the lack of vaccines inducing reliable cross-serotype protection. Type IV fimbrial protein ApfA has been shown to be present and highly conserved in various serotypes of A. pleuropneumoniae. A novel DNA vaccine encoding ApfA (pcDNA-apfA) was constructed to evaluate the protective efficacy against infection with A. pleuropneumoniae serotype 2. A significant antibody response against pilin was generated following pcDNA-apfA immunization, suggesting that it was expressed in vivo. The IgG subclass (IgG1 and IgG2a) analysis indicates that the pcDNA-apfA vaccine induces both Th1 and Th2 immune responses. The IgA analysis shows that mucosal immunity could be enhanced by this DNA vaccine. Nevertheless, the strong antibody response induced by pcDNA-apfA vaccine only provided limited 30% protective efficacy against the serotype 2 challenge. These results in this study do not coincide with that the utility of type IV pilin is a good vaccine candidate against other infectious pathogens. It indicates that pilin should play a limited role in the development of a vaccine against A. pleuropneumoniae infection.

  13. High temperature strain gage apparent strain compensation

    NASA Technical Reports Server (NTRS)

    Holmes, Harlan K.; Moore, T. C., Sr.

    1992-01-01

    Once an installed strain gage is connected to a strain indicating device and the instrument is balanced, a subsequent change in temperature of the gage installation will generally produce a resistance change in the gage. This purely temperature-induced resistance will be registered by the indicating device as a strain and is referred to as 'apparent strain' to distinguish it from strain due to applied stress. One desirable technique for apparent strain compensation is to employ two identical gages with identical mounting procedures which are connected with a 'half bridge' configuration where gages see the same thermal environment but only one experiences a mechanical strain input. Their connection in adjacent arms of the bridge will then balance the thermally induced apparent strains and, in principle, only the mechanical strain remains. Two approaches that implement this technique are discussed.

  14. Efficacy of vaccination against Actinobacillus pleuropneumoniae in two Belgian farrow-to-finish pig herds with a history of chronic pleurisy.

    PubMed

    Del Pozo Sacristán, R; Michiels, A; Martens, M; Haesebrouck, F; Maes, D

    2014-03-22

    The efficacy of an Actinobacillus pleuropneumoniae subunit vaccine based on ApxIA, ApxIIA, ApxIIIA and OMP-2 (Porcilis App, MSD) was investigated in two farrow-to-finish pig herds (A and B) affected by chronic pleurisy. In total, 1161 pigs were included. At three weeks of age, the pigs were randomly allocated to non-vaccinated control (NV; n=580) and vaccinated (V; n=581) groups. At 6 and 10 weeks of age, pigs were injected with Porcilis-APP (V group) or adjuvant (NV group). At slaughter (26 weeks), pleurisy and pneumonia lesions were assessed. All pigs were weighed individually at 6 and 26 weeks of age, and average daily weight gain (ADG; g/pig/day) was calculated. Mortality and days of additional treatment (DAT) were registered during the whole experiment. Data were analysed using binary logistic regression or analysis of variance for proportions or continuous variables, respectively. The prevalence of pleurisy and pneumonia was (NV-A=19.3, V-A=7.9, (P=0.000); NV-B=17.9, V-B=0.7, (P=0.000)) and (NV-A=42.4, V-A=21.2, (P=0.000); NV-B=46.7, V-B=19.0, (P=0.000)), respectively. The ADG was NV-A=632±157, V-A=647±91, (P=0.162); NV-B=660±115, V-B=670±82, (P=0.232). The mortality during the experiment was NV-A=5.7, V-A=1.8, (P=0.015); NV-B=2.3, V-B=1.0, (P=0.170) per cent. The DAT was: NV-A=15.04±1.41, V-A=14.95±0.67, (P=0.010); NV-B=21.68±2.43, V-B=16.99±0.62, (P=0.000). The present study showed a significant reduction of the prevalence of pleurisy and pneumonia, and antimicrobial use in V pigs from both herds, and in mortality in V pigs from one herd.

  15. Geobacteraceae strains and methods

    DOEpatents

    Lovley, Derek R.; Nevin, Kelly P.; Yi, Hana

    2015-07-07

    Embodiments of the present invention provide a method of producing genetically modified strains of electricigenic microbes that are specifically adapted for the production of electrical current in microbial fuel cells, as well as strains produced by such methods and fuel cells using such strains. In preferred embodiments, the present invention provides genetically modified strains of Geobacter sulfurreducens and methods of using such strains.

  16. Muscle strain treatment

    MedlinePlus

    Treatment - muscle strain ... Question: How do you treat a muscle strain ? Answer: Rest the strained muscle and apply ice for the first few days after the injury. Anti-inflammatory medicines or acetaminophen ( ...

  17. Muscle strain (image)

    MedlinePlus

    A muscle strain is the stretching or tearing of muscle fibers. A muscle strain can be caused by sports, exercise, a ... something that is too heavy. Symptoms of a muscle strain include pain, tightness, swelling, tenderness, and the ...

  18. Simultaneous Detection of Antibodies against Apx Toxins ApxI, ApxII, ApxIII, and ApxIV in Pigs with Known and Unknown Actinobacillus pleuropneumoniae Exposure Using a Multiplexing Liquid Array Platform

    PubMed Central

    Giménez-Lirola, Luis G.; Jiang, Yong-Hou; Sun, Dong; Hoang, Hai; Yoon, Kyoung-Jin; Halbur, Patrick G.

    2014-01-01

    Surveillance for the presence of Actinobacillus pleuropneumoniae infection in a population plays a central role in controlling the disease. In this study, a 4-plex fluorescent microbead-based immunoassay (FMIA), developed for the simultaneous detection of IgG antibodies to repeat-in-toxin (RTX) toxins (ApxI, ApxII, ApxIII, and ApxIV) of A. pleuropneumoniae, was evaluated using (i) blood serum samples from pigs experimentally infected with each of the 15 known A. pleuropneumoniae serovars or with Actinobacillus suis, (ii) blood serum samples from pigs vaccinated with a bacterin containing A. pleuropneumoniae serovar 1, 3, 5, or 7, and (iii) blood serum samples from pigs with an unknown A. pleuropneumoniae exposure status. The results were compared to those obtained in a previous study where a dual-plate complement fixation test (CFT) and three commercially available enzyme-linked immunosorbent assays (ELISAs) were conducted on the same sample set. On samples from experimentally infected pigs, the 4-plex Apx FMIA detected specific seroconversion to Apx toxins as early as 7 days postinfection in a total of 29 pigs inoculated with 14 of the 15 A. pleuropneumoniae serovars. Seroconversion to ApxII and ApxIII was detected by FMIA in pigs inoculated with A. suis. The vaccinated pigs showed poor humoral responses against ApxI, ApxII, ApxIII, and ApxIV. In the field samples, the humoral response to ApxIV and the A. pleuropneumoniae seroprevalence increased with age. This novel FMIA (with a sensitivity of 82.7% and a specificity of 100% for the anti-ApxIV antibody) was found to be more sensitive and accurate than current tests (sensitivities, 9.5 to 56%; specificity, 100%) and is potentially an improved tool for the surveillance of disease and for monitoring vaccination compliance. PMID:24226091

  19. Use of the rapid fermentation test in determining carbohydrate reactions of fastidious bacteria in clinical laboratories.

    PubMed Central

    Hollis, D G; Sottnek, F O; Brown, W J; Weaver, R E

    1980-01-01

    The rapid fermentation test was used to determine the carbohydrate reactions of some of the fastidious bacteria encountered in clinical laboratories, such as: Haemophilus species, including Haemophilus vaginalis; Actinobacillus actinomycetemcomitans; Cardiobacterium hominis; Kingella species; Corynebacterium species; Propionibacterium species; and Erysipelothrix rhusiopathiae. Results were usually obtained within 4 h by using inocula from 24- or 48-h blood or chocolate agar media. PMID:6999028

  20. Persistence of associated gram-negative bacteria in experimental actinomycotic lesions in mice.

    PubMed Central

    Jordan, H V; Kelly, D M

    1983-01-01

    Mixed actinomycotic infections were established in a susceptible weanling mouse model by using combinations of Actinomyces israelii and Eikenella corrodens or A. israelii and Actinobacillus actinomycetemcomitans. Acute lesions caused by either of the gram-negative organisms alone were resolved within a few weeks; however, these organisms persisted up to 3 months in chronic lesions in combination with A. israelii. PMID:6341251

  1. Superlattice strain gage

    DOEpatents

    Noel, B.W.; Smith, D.L.; Sinha, D.N.

    1988-06-28

    A strain gage comprising a strained-layer superlattice crystal exhibiting piezoelectric properties is described. A substrate upon which such a strained-layer superlattice crystal has been deposited is attached to an element to be monitored for strain. A light source is focused on the superlattice crystal and the light reflected from, passed through, or emitted from the crystal is gathered and compared with previously obtained optical property data to determine the strain in the element. 8 figs.

  2. Superlattice strain gage

    DOEpatents

    Noel, Bruce W.; Smith, Darryl L.; Sinha, Dipen N.

    1990-01-01

    A strain gage comprising a strained-layer superlattice crystal exhibiting piezoelectric properties is described. A substrate upon which such a strained-layer superlattice crystal has been deposited is attached to an element to be monitored for strain. A light source is focused on the superlattice crystal and the light reflected from, passed through, or emitted from the crystal is gathered and compared with previously obtained optical property data to determine the strain in the element.

  3. Elevated temperature strain gages

    NASA Technical Reports Server (NTRS)

    Brittain, J. O.; Geslin, D.; Lei, J. F.

    1985-01-01

    Materials were evaluated that could be used in manufacturing electrical resistance strain gages for static strain measurements at temperatures at or above 1273 K. Strain gage materials must have a characteristic response to strain, temperature and time that is reproducible or that varies in a predictable manner within specified limits. Several metallic alloys were evaluated, as well as a series of transition metal carbides, nitrides and silicides.

  4. Sprains and Strains

    MedlinePlus

    ... happens. A strain is a stretched or torn muscle or tendon. Tendons are tissues that connect muscle to bone. Twisting or pulling these tissues can ... suddenly or develop over time. Back and hamstring muscle strains are common. Many people get strains playing ...

  5. Strain powered antennas

    NASA Astrophysics Data System (ADS)

    Domann, John P.; Carman, Greg P.

    2017-01-01

    This paper proposes the creation of strain powered antennas that radiate electromagnetic energy by mechanically vibrating a piezoelectric or piezomagnetic material. A closed form analytic model of electromagnetic radiation from a strain powered electrically small antenna is derived and analyzed. Fundamental scaling laws and the frequency dependence of strain powered antennas are discussed. The radiation efficiency of strain powered electrically small antennas is contrasted with a conventional electric dipole. Analytical results show that operating at the first mechanical resonance produces the most efficient strain powered radiation relative to electric dipole antennas. A resonant analysis is exploited to determine the material property space that produces efficient strain powered antennas. These results show how a properly designed strain powered antenna can radiate more efficiently than an equally sized electric dipole antenna.

  6. Functional Pentameric Formation via Coexpression of the Escherichia coli Heat-Labile Enterotoxin B Subunit and Its Fusion Protein Subunit with a Neutralizing Epitope of ApxIIA Exotoxin Improves the Mucosal Immunogenicity and Protection against Challenge by Actinobacillus pleuropneumoniae▿

    PubMed Central

    Kim, Jung-Mi; Park, Seung-Moon; Kim, Jung-Ae; Park, Jin-Ah; Yi, Min-Hee; Kim, Nan-Sun; Bae, Jong-Lye; Park, Sung Goo; Jang, Yong-Suk; Yang, Moon-Sik; Kim, Dae-Hyuk

    2011-01-01

    A coexpression strategy in Saccharomyces cerevisiae using episomal and integrative vectors for the Escherichia coli heat-labile enterotoxin B subunit (LTB) and a fusion protein of an ApxIIA toxin epitope produced by Actinobacillus pleuropneumoniae coupled to LTB, respectively, was adapted for the hetero-oligomerization of LTB and the LTB fusion construct. Enzyme-linked immunosorbent assay (ELISA) with GM1 ganglioside indicated that the LTB fusion construct, along with LTB, was oligomerized to make the functional heteropentameric form, which can bind to receptors on the mucosal epithelium. The antigen-specific antibody titer of mice orally administered antigen was increased when using recombinant yeast coexpressing the pentameric form instead of recombinant yeast expressing either the LTB fusion form or antigen alone. Better protection against challenge infection with A. pleuropneumoniae was also observed for coexpression in recombinant yeast compared with others. The present study clearly indicated that the coexpression strategy enabled the LTB fusion construct to participate in the pentameric formation, resulting in an improved induction of systemic and mucosal immune responses. PMID:22030372

  7. Physicochemical and structural investigation of the surfaces of some anaerobic subgingival bacteria.

    PubMed Central

    Cowan, M M; van der Mei, H C; Rouxhet, P G; Busscher, H J

    1992-01-01

    The surfaces of nine clinical isolates of Porphyromonas gingivalis, Prevotella intermedia, Actinobacillus actinomycetemcomitans, and Peptostreptococcus micros and that of laboratory strain P. gingivalis W83 were studied by using contact angle measurements, X-ray photoelectron spectroscopy, infrared spectroscopy, microelectrophoresis of whole cells, and transmission electron microscopy of whole and sectioned cells. P. intermedia strains were hydrophilic, as judged from their small water contact angles, and had highly negative zeta potentials, consistent with the presence of a prominent ruthenium red (RR)-staining layer and fibrillar appendages which are probably partly carbohydrate. The two clinical isolates of P. gingivalis were also hydrophilic and highly negatively charged despite the presence of prominent fibrils, which usually yield less negative zeta potentials. This finding suggests that the RR-staining layer dominates the suspension characteristics of P. gingivalis and P. intermedia strains. P. gingivalis W83 had no demonstrable fibrils and a morphologically distinct RR-staining layer, and it was more hydrophobic than the two clinical isolates of P. gingivalis. P. micros isolates were hydrophobic and much less negatively charged than the other species. The A. actinomycetemcomitans strains displayed long, prominent fibrils and a very thin RR-staining layer, which resulted in high hydrophobicity but distinctly different zeta potentials for the two. Physicochemical data on microbial cell surfaces usually have clear and predictable relationships with each other. For the strains in this study that did not follow these relationships, their aberrant behavior could be explained as due to a masking effect caused by specific surface architecture. We conclude that this combined analysis provides a detailed image of subgingival bacterial surface architecture. Images PMID:1599251

  8. Three dimensional strained semiconductors

    DOEpatents

    Voss, Lars; Conway, Adam; Nikolic, Rebecca J.; Leao, Cedric Rocha; Shao, Qinghui

    2016-11-08

    In one embodiment, an apparatus includes a three dimensional structure comprising a semiconductor material, and at least one thin film in contact with at least one exterior surface of the three dimensional structure for inducing a strain in the structure, the thin film being characterized as providing at least one of: an induced strain of at least 0.05%, and an induced strain in at least 5% of a volume of the three dimensional structure. In another embodiment, a method includes forming a three dimensional structure comprising a semiconductor material, and depositing at least one thin film on at least one surface of the three dimensional structure for inducing a strain in the structure, the thin film being characterized as providing at least one of: an induced strain of at least 0.05%, and an induced strain in at least 5% of a volume of the structure.

  9. Strain sensor comprising a strain sensitive, two-mode optical

    NASA Technical Reports Server (NTRS)

    Egalon, Claudio Oliveira (Inventor); Rogowski, Robert S. (Inventor)

    1994-01-01

    A strain sensor uses an optical fiber including a strain sensitive portion and at least one strain insensitive portion. The strain sensitive portion is mounted on the surface of a structure at a location where a strain is desired to be measured. The strain insensitive portion(s) may be fused to the strain sensitive portion to transmit light therethrough, so that the resulting pattern may be detected to determine the amount of strain by comparison with a similar fiber not subjected to strain, or with the light pattern produced when the fiber is not under strain.

  10. Thin film strain transducer

    NASA Technical Reports Server (NTRS)

    Rand, J. L. (Inventor)

    1984-01-01

    A strain transducer system and process for making the same is disclosed. A beryllium copper ring having four strain gages is electrically connected in Wheatstone bridge fashion to the output instrumentation. Tabs are bonded to a balloon or like surface with strain on the surface causing bending of a ring which provides an electrical signal through the gages proportional to the surface strain. A photographic pattern of a one half ring segment as placed on a sheet of beryllium copper for chem-mill etch formation is illustrated.

  11. Mechanical strain isolator mount

    NASA Technical Reports Server (NTRS)

    James, Gordon E. (Inventor)

    1991-01-01

    Certain devices such as optical instruments must preserve their alignmental integrity while being subjected to mechanical strain. A mechanical strain isolator mount is provided to preserve the alignmental integrity of an alignment sensitive instrument. An alignment sensitive instrument is mounted on a rectangular base. Flexural legs are connected at their proximal ends to the rectangular base. Flexural legs are also spaced parallel to the sides. Mounting pads are connected to the legs at the distal end and the mechanical strain isolator mount is attached to the substrate by means of threaded bolts. When a mounting pad and its respective leg is subjected to lateral strain in either the X or Y direction via the substrate, the respective leg relieves the strain by bending in the direction of the strain. An axial strain on a mounting pad in the Z direction is relieved by a rotational motion of the legs in the direction of the strain. When the substrate is stress free, the flexural legs return to their original condition and thus preserve the original alignment integrity of the alignment sensitive instrument.

  12. Light intensity strain analysis

    NASA Technical Reports Server (NTRS)

    Williams, J. G. (Inventor)

    1973-01-01

    A process is described for the analysis of the strain field of structures subjected to large deformations involving a low modulus substrate having a high modulus, relatively thin coating. The optical properties of transmittance and reflectance are measured for the coated substrate while stressed and unstressed to indicate the strain field for the coated substrate.

  13. Thin film strain transducer

    NASA Astrophysics Data System (ADS)

    Rand, J. L.

    1981-01-01

    Previous attempts to develop an appropriate sensor for measuring the stress or strain of high altitude balloons during flight are reviewed as well as the various conditions that must be met by such a device. The design, development and calibration of a transducer which promises to satisfy the necessary design constraints are described. The thin film strain transducer has a low effective modulus so as not to interfere with the strain that would naturally occur in the balloon. In addition, the transducer has a high sensitivity to longitudinal strain (7.216 mV/V/unit strain) which is constant for all temperature from room temperature to -80 C and all strains from 5 percent compression to 10 percent tensile strain. At the same time, the sensor is relatively insensitive (0.27 percent) to transverse forces. The device has a standard 350 ohm impedance which is compatible with available bridge balance, amplification and telemetry instrumentation now available for balloon flight. Recommendations are included for improved coatings to provide passive thermal control as well as model, tethered and full scale flight testing.

  14. Strain gauge installation tool

    DOEpatents

    Conard, Lisa Marie

    1998-01-01

    A tool and a method for attaching a strain gauge to a test specimen by maaining alignment of, and applying pressure to, the strain gauge during the bonding of the gauge to the specimen. The tool comprises rigid and compliant pads attached to a spring-loaded clamp. The pads are shaped to conform to the specimen surface to which the gauge is to be bonded. The shape of the pads permits the tool to align itself to the specimen and to maintain alignment of the gauge to the specimen during the bond curing process. A simplified method of attaching a strain gauge is provided by use of the tool.

  15. Differences in purinergic amplification of osmotic cell lysis by the pore-forming RTX toxins Bordetella pertussis CyaA and Actinobacillus pleuropneumoniae ApxIA: the role of pore size.

    PubMed

    Masin, Jiri; Fiser, Radovan; Linhartova, Irena; Osicka, Radim; Bumba, Ladislav; Hewlett, Erik L; Benz, Roland; Sebo, Peter

    2013-12-01

    A large subgroup of the repeat in toxin (RTX) family of leukotoxins of Gram-negative pathogens consists of pore-forming hemolysins. These can permeabilize mammalian erythrocytes (RBCs) and provoke their colloid osmotic lysis (hemolytic activity). Recently, ATP leakage through pannexin channels and P2X receptor-mediated opening of cellular calcium and potassium channels were implicated in cell permeabilization by pore-forming toxins. In the study described here, we examined the role played by purinergic signaling in the cytolytic action of two RTX toxins that form pores of different sizes. The cytolytic potency of ApxIA hemolysin of Actinobacillus pleuropneumoniae, which forms pores about 2.4 nm wide, was clearly reduced in the presence of P2X7 receptor antagonists or an ATP scavenger, such as pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid (PPADS), Brilliant Blue G, ATP oxidized sodium salt, or hexokinase. In contrast, antagonists of purinergic signaling had no impact on the hemolytic potency of the adenylate cyclase toxin-hemolysin (CyaA) of Bordetella pertussis, which forms pores of 0.6 to 0.8 nm in diameter. Moreover, the conductance of pores formed by ApxIA increased with the toxin concentration, while the conductance of the CyaA single pore units was constant at various toxin concentrations. However, the P2X7 receptor antagonist PPADS inhibited in a concentration-dependent manner the exacerbated hemolytic activity of a CyaA-ΔN489 construct (lacking 489 N-terminal residues of CyaA), which exhibited a strongly enhanced pore-forming propensity (>20-fold) and also formed severalfold larger conductance units in planar lipid bilayers than intact CyaA. These results point to a pore size threshold of purinergic amplification involvement in cell permeabilization by pore-forming RTX toxins.

  16. Sprains and Strains

    MedlinePlus

    ... Typically, people with a strain experience pain, limited motion, muscle spasms, and possibly muscle weakness. They also ... program designed to prevent stiffness, improve range of motion, and restore the joint's normal flexibility and strength. ...

  17. Strains and Sprains

    MedlinePlus

    ... in the joint or muscle swelling and bruising warmth and redness of the injured area difficulty moving ... looks "bent" or misshapen signs of infection (increased warmth, redness, streaks, swelling, and pain) a strain or ...

  18. Strain and magnetic remanence

    NASA Astrophysics Data System (ADS)

    Borradaile, Graham John

    1993-05-01

    Experimental data may be compatible with the hypothesis that a single direction of magnetic remanence rotates as a rigid marker with strains up to 40% shortening in coaxial, perfect flattening ( X = Y > Z). Detailed agreement with the passive line model is relatively poor for the specimens in which remanance is carried by magnetite. However, for this range of strains the differences with the passive line model (Wettstein's equation) are so slight that the latter model may be more easily employed to de-strain or restore deformed remanance to its original attitude. In the case of hematite-bearing remanences, the differences between the passive line and rigid marker model are even smaller because of the higher aspect ratios of grains of hematite. Therefore it is suggested that Wettstein's equation may be safely used to restore remanence after even higher strains, where the remanence is carried by hematite.

  19. Strain isolated ceramic coatings

    NASA Technical Reports Server (NTRS)

    Tolokan, R. P.; Brady, J. B.; Jarrabet, G. P.

    1985-01-01

    Plasma sprayed ceramic coatings are used in gas turbine engines to improve component temperature capability and cooling air efficiency. A compliant metal fiber strain isolator between a plasma sprayed ceramic coating and a metal substrate improves ceramic durability while allowing thicker coatings for better insulation. Development of strain isolated coatings has concentrated on design and fabrication of coatings and coating evaluation via thermal shock testing. In thermal shock testing, five types of failure are possible: buckling failure im compression on heat up, bimetal type failure, isothermal expansion mismatch failure, mudflat cracking during cool down, and long term fatigue. A primary failure mode for thermally cycled coatings is designated bimetal type failure. Bimetal failure is tensile failure in the ceramic near the ceramic-metal interface. One of the significant benefits of the strain isolator is an insulating layer protecting the metal substrate from heat deformation and thereby preventing bimetal type failure.

  20. Strain avalanches in plasticity

    NASA Astrophysics Data System (ADS)

    Argon, A. S.

    2013-09-01

    Plastic deformation at the mechanism level in all solids occurs in the form of discrete thermally activated individual stress relaxation events. While there are clear differences in mechanisms between dislocation mediated events in crystalline solids and by individual shear transformations in amorphous metals and semiconductors, such relaxation events interact strongly to form avalanches of strain bursts. In all cases the attendant distributions of released energy as amplitudes of acoustic emissions, or in serration amplitudes in flow stress, the levels of strain bursts are of fractal character with fractal exponents in the range from -1.5 to -2.0, having the character of phenomena of self-organized criticality, SOC. Here we examine strain avalanches in single crystals of ice, hcp metals, the jerky plastic deformations of nano-pillars of fcc and bcc metals deforming in compression, those in the plastic flow of bulk metallic glasses, all demonstrating the remarkable universality of character of plastic relaxation events.

  1. Strain gauge installation tool

    DOEpatents

    Conard, L.M.

    1998-06-16

    A tool and a method are disclosed for attaching a strain gauge to a test specimen by maintaining alignment of, and applying pressure to, the strain gauge during the bonding of the gauge to the specimen. The tool comprises rigid and compliant pads attached to a spring-loaded clamp. The pads are shaped to conform to the specimen surface to which the gauge is to be bonded. The shape of the pads permits the tool to align itself to the specimen and to maintain alignment of the gauge to the specimen during the bond curing process. A simplified method of attaching a strain gauge is provided by use of the tool. 6 figs.

  2. Radio frequency strain monitor

    NASA Technical Reports Server (NTRS)

    Heyman, Joseph S. (Inventor); Rogowski, Robert S. (Inventor); Holben, Jr., Milford S. (Inventor)

    1989-01-01

    A radio frequency strain monitor includes a voltage controlled oscillator for generating an oscillating signal that is input into a propagation path. The propagation path is preferably bonded to the surface of a structure to be monitored and produces a propagated signal. A phase difference between the oscillating and propagated signals is detected and maintained at a substantially constant value which is preferably a multiple of 90.degree. by changing the frequency of the oscillating signal. Any change in frequency of the oscillating signal provides an indication of strain in the structure to which the propagation path is bonded.

  3. Muscle strain injuries.

    PubMed

    Garrett, W E

    1996-01-01

    One of the most common injuries seen in the office of the practicing physician is the muscle strain. Until recently, little data were available on the basic science and clinical application of this basic science for the treatment and prevention of muscle strains. Studies in the last 10 years represent action taken on the direction of investigation into muscle strain injuries from the laboratory and clinical fronts. Findings from the laboratory indicate that certain muscles are susceptible to strain injury (muscles that cross multiple joints or have complex architecture). These muscles have a strain threshold for both passive and active injury. Strain injury is not the result of muscle contraction alone, rather, strains are the result of excessive stretch or stretch while the muscle is being activated. When the muscle tears, the damage is localized very near the muscle-tendon junction. After injury, the muscle is weaker and at risk for further injury. The force output of the muscle returns over the following days as the muscle undertakes a predictable progression toward tissue healing. Current imaging studies have been used clinically to document the site of injury to the muscle-tendon junction. The commonly injured muscles have been described and include the hamstring, the rectus femoris, gastrocnemius, and adductor longus muscles. Injuries inconsistent with involvement of a single muscle-tendon junction proved to be at tendinous origins rather than within the muscle belly. Important information has also been provided regarding injuries with poor prognosis, which are potentially repairable surgically, including injuries to the rectus femoris muscle, the hamstring origin, and the abdominal wall. Data important to the management of common muscle injuries have been published. The risks of reinjury have been documented. The early efficacy and potential for long-term risks of nonsteroidal antiinflammatory agents have been shown. New data can also be applied to the field

  4. Detection of RTX toxin genes in gram-negative bacteria with a set of specific probes.

    PubMed Central

    Kuhnert, P; Heyberger-Meyer, B; Burnens, A P; Nicolet, J; Frey, J

    1997-01-01

    The family of RTX (RTX representing repeats in the structural toxin) toxins is composed of several protein toxins with a characteristic nonapeptide glycine-rich repeat motif. Most of its members were shown to have cytolytic activity. By comparing the genetic relationships of the RTX toxin genes we established a set of 10 gene probes to be used for screening as-yet-unknown RTX toxin genes in bacterial species. The probes include parts of apxIA, apxIIA, and apxIIIA from Actinobacillus pleuropneumoniae, cyaA from Bordetella pertusis, frpA from Neisseria meningitidis, prtC from Erwinia chrysanthemi, hlyA and elyA from Escherichia coli, aaltA from Actinobacillus actinomycetemcomitans and lktA from Pasteurella haemolytica. A panel of pathogenic and nonpathogenic gram-negative bacteria were investigated for the presence of RTX toxin genes. The probes detected all known genes for RTX toxins. Moreover, we found potential RTX toxin genes in several pathogenic bacterial species for which no such toxins are known yet. This indicates that RTX or RTX-like toxins are widely distributed among pathogenic gram-negative bacteria. The probes generated by PCR and the hybridization method were optimized to allow broad-range screening for RTX toxin genes in one step. This included the binding of unlabelled probes to a nylon filter and subsequent hybridization of the filter with labelled genomic DNA of the strain to be tested. The method constitutes a powerful tool for the assessment of the potential pathogenicity of poorly characterized strains intended to be used in biotechnological applications. Moreover, it is useful for the detection of already-known or new RTX toxin genes in bacteria of medical importance. PMID:9172345

  5. Sadovskii vortex in strain

    NASA Astrophysics Data System (ADS)

    Freilich, Daniel; Llewellyn Smith, Stefan

    2015-11-01

    Sadovskii vortices are patches of fluid with uniform vorticity surrounded by a vortex sheet. They were first constructed as models for wakes behind bluff objects. We investigate the Sadovskii vortex in a straining field and examine limiting cases to validate our computational method. One limit is the patch vortex in strain (Moore & Saffman, Aircraft wake turbulence and its detection 1971), where there is no vortex sheet. We solve this as a free-boundary problem, and show that a simple method using the Biot-Savart law quickly gives solutions for stable shapes. When used for the more elongated (stronger straining field) situations, the method also leads to new vortex shapes. In the hollow vortex case, where there is no vortex patch and the circulation is entirely due to the vortex sheet (Llewellyn Smith and Crowdy, J. Fluid Mech. 691 2012), we use the Birkhoff-Rott equation to calculate the velocity of the fluid on the vortex boundary. The combination of these two methods can then be used to calculate the shape and velocity field of the Sadovksii vortex in strain.

  6. Strain gage barometric transmitter

    NASA Technical Reports Server (NTRS)

    Viton, P.

    1977-01-01

    A strain gage barometric transmitter for measuring the atmospheric pressure in severe environmental conditions is described. This equipment specifications are presented and its performance assessed. It is shown that this barometric sensor can measure the atmospheric pressure with a precision of 0.5 mb during a 6 month period.

  7. Hamstring strain - aftercare

    MedlinePlus

    ... not to push yourself too hard or too fast. A hamstring strain can recur, or your hamstring may tear. Talk to your provider before returning to work or any physical activity. Returning to normal activity too early can cause re-injury.

  8. Repetitive strain injury.

    PubMed

    Al-Otaibi, S T

    2001-05-01

    Repetitive strain injury is a group of musculoskeletal disorders affecting muscles, tendons, nerves and blood vessels. These disorders could be attributed to occupational causes; however non-occupational causes should be excluded. The management of these cases required a multidisciplinary team approach.

  9. Balloon film strain measurement

    NASA Astrophysics Data System (ADS)

    Rand, James L.

    In order to understand the state of stress in scientific balloons, a need exists for the measurement of film deformation in flight. The results of a flight test program are reported where material strain was measured for the first time during the inflation, launch, ascent and float of a typical natural shape, zero pressure scientific balloon.

  10. Detection of Actinobacillus pleuropneumoniae in cultures from nasal and tonsillar swabs of pigs by a PCR assay based on the nucleotide sequence of a dsbE-like gene.

    PubMed

    Chiers, K; Van Overbeke, I; Donné, E; Baele, M; Ducatelle, R; De Baere, T; Haesebrouck, F

    2001-11-08

    A PCR assay for the detection of Actinobacillus pleuropneumoniae was developed based on the amplification of a dsbE-like gene. All of 157 field isolates of A. pleuropneumoniae reacted in the PCR by the amplification of a 342bp product. No reaction was observed with related bacterial species or other bacterial species isolated from pigs, except for A. lignieresii. The lower detection limit of the PCR was 10(2) CFU per PCR test tube and was not affected by the addition of 10(6) CFU Escherichia coli. The PCR was evaluated on mixed bacterial cultures from nasal and tonsillar swabs as well as suspensions of nasal conchae and tonsils obtained from specific pathogen-free (SPF) pigs, experimentally infected pigs, and pigs from farrow-to-finish herds. The results of the new PCR were compared with a PCR based on the detection of the omlA gene coding for an outer membrane protein, with a commercially available PCR (Adiavet APP, Adiagène, Saint-Brieuc, France), and with conventional culturing. No positive reactions were observed with any of the PCR methods in samples of SPF animals. In samples of the other animals, no or low significant differences between nasal swabs and suspensions as well as tonsillar swabs and suspensions were observed in any method. In general, more positive results were obtained from tonsillar samples in comparison to nasal samples. Interassay sensitivity and specificity values were assessed for each test by pair wise comparisons between assays. The agreement between tests was evaluated by calculating Cohen's kappa coefficient. From these analyses the three PCR assays showed a good agreement. The dsbE-based PCR proved to be highly sensitive (95 and 93%) and specific (82 and 74%) in comparison to the omlA-based PCR and the commercially available PCR, respectively. It was concluded that the dsbE-like gene-based PCR is a reliable diagnostic assay for demonstration of A. pleuropneumoniae. Furthermore, it was demonstrated that tonsillar swabs can be used for

  11. Highly stretchable miniature strain sensor for large dynamic strain measurement

    DOE PAGES

    Song, Bo; Yao, Shurong; Nie, Xu; ...

    2016-01-01

    In this paper, a new type of highly stretchable strain sensor was developed to measure large strains. The sensor was based on the piezo-resistive response of carbon nanotube (CNT)/polydimethylsiloxane (PDMS) composite thin films. The piezo-resistive response of CNT composite gives accurate strain measurement with high frequency response, while the ultra-soft PDMS matrix provides high flexibility and ductility for large strain measurement. Experimental results show that the CNT/PDMS sensor measures large strains (up to 8 %) with an excellent linearity and a fast frequency response. The new miniature strain sensor also exhibits much higher sensitivities than the conventional foil strain gages,more » as its gauge factor is 500 times of that of the conventional foil strain gages.« less

  12. Highly stretchable miniature strain sensor for large dynamic strain measurement

    SciTech Connect

    Song, Bo; Yao, Shurong; Nie, Xu; Yu, Xun; Blecke, Jill

    2016-01-01

    In this paper, a new type of highly stretchable strain sensor was developed to measure large strains. The sensor was based on the piezo-resistive response of carbon nanotube (CNT)/polydimethylsiloxane (PDMS) composite thin films. The piezo-resistive response of CNT composite gives accurate strain measurement with high frequency response, while the ultra-soft PDMS matrix provides high flexibility and ductility for large strain measurement. Experimental results show that the CNT/PDMS sensor measures large strains (up to 8 %) with an excellent linearity and a fast frequency response. The new miniature strain sensor also exhibits much higher sensitivities than the conventional foil strain gages, as its gauge factor is 500 times of that of the conventional foil strain gages.

  13. Strain patterns and strain accumulation along plate margins

    NASA Technical Reports Server (NTRS)

    Savage, J. C.

    1978-01-01

    Observations of strain accumulation along plate margins in Japan, New Zealand, and the United States indicate that: (1) a typical maximum rate of secular strain accumulation is on the order of 0.3 ppm/a, (2) a substantial part of the strain accumulation process can be attributed to slip at depth on the major plate boundary faults, and (3) some plastic deformation in a zone 100 km or more in width is apparently involved in the strain accumulation process.

  14. High temperature strain gages

    NASA Technical Reports Server (NTRS)

    Gregory, Otto J. (Inventor); You, Tao (Inventor)

    2011-01-01

    A ceramic strain gage based on reactively sputtered indium-tin-oxide (ITO) thin films is used to monitor the structural integrity of components employed in aerospace propulsion systems operating at temperatures in excess of 1500.degree. C. A scanning electron microscopy (SEM) of the thick ITO sensors reveals a partially sintered microstructure comprising a contiguous network of submicron ITO particles with well defined necks and isolated nanoporosity. Densification of the ITO particles was retarded during high temperature exposure with nitrogen thus stabilizing the nanoporosity. ITO strain sensors were prepared by reactive sputtering in various nitrogen/oxygen/argon partial pressures to incorporate more nitrogen into the films. Under these conditions, sintering and densification of the ITO particles containing these nitrogen rich grain boundaries was retarded and a contiguous network of nano-sized ITO particles was established.

  15. Strained Ring Energetic Binders

    DTIC Science & Technology

    1993-08-27

    polyhomobenzvalene ( PHBV ). PHBV was not found to have the mechanical instability problems of PBV, but was still thermally unstable (Tonset - 660C, Tmax - 1090C...DISCUSSION 4 Polybenzvalene (PBV) 4 Polyhomobenzvalene ( PHBV ) 6 Chain-Transfer Studies 11 CONCLUSIONS 15 EXPERIMENTAL PROCEDURES 16 .F 4E 19 APPENDICES A...strained ring polymers similar to PBV are known. The investigation of one of these polymers, polyhomobenzvalene ( PHBV ), is also described in this report

  16. Strain Gage Signal Interpretation.

    DTIC Science & Technology

    1986-02-01

    blades and vanes in many engines have been collected, played back and examined. The engine types encompass GE’s stable of turbine engines from the small...aeromechanical engineer . 1.3 SUMMARY OF RESULTS Strain gage signals from vibrating rotor blades and vanes were collected, examined, classified, and generalized...turboprops, to turbojets and to the large high bypass turbofan engines . Test conditions include all the phases that are investigated

  17. Strain Measurement - Unidirectional.

    DTIC Science & Technology

    1983-04-20

    a ballpoint pen or a rounded piece of brass rod. If critical alignment is not necessary, gage lines may be located outside the immediate gage location...supplemented as needed by tabulated values. If the test design includes specification limits for the values, they should be included on the plots. Plots of...enough baseline before the event to allow estimation of the noise and stability. If the strain is to be correlated to specific events, the events should

  18. Cardiobacterium hominis-induced acute dacryocystitis and lacrimal abscess

    PubMed Central

    Manderwad, Guru Prasad; Kodiganti, Manjulatha; Ali, Mohammad Javed

    2014-01-01

    Cardiobacterium hominis is a member of the HACEK (Haemophilus sp., Actinobacillus actinomycetemcomitans, C. hominis, Eikenella corrodens, and Kingella kingae) group commonly associated with endocarditits and is normally present in the respiratory tract. We describe the first case of acute dacryocystitis with lacrimal abscess caused by C. hominis along with a brief review of the literature. The patient responded to oral and topical ciprofloxacin after incision and drainage and awaits dacryocystorhinostomy. PMID:24008805

  19. Activity of human beta-defensin 3 alone or combined with other antimicrobial agents against oral bacteria.

    PubMed

    Maisetta, Giuseppantonio; Batoni, Giovanna; Esin, Semih; Luperini, Filippo; Pardini, Manuela; Bottai, Daria; Florio, Walter; Giuca, Maria Rita; Gabriele, Mario; Campa, Mario

    2003-10-01

    The in vitro activities of human beta-defensin 3 (hBD-3) alone or combined with lysozyme, metronidazole, amoxicillin, and chlorhexidine were investigated with the oral bacteria Streptococcus mutans, Streptococcus sanguinis, Streptococcus sobrinus, Lactobacillus acidophilus, Actinobacillus actinomycetemcomitans, and Porphyromonas gingivalis. hBD-3 showed bactericidal activity against all of the bacterial species tested. The bactericidal effect was enhanced when the peptide was used in combination with the antimicrobial agents mentioned above.

  20. Development of a Rapid Qualitative Assay for Determining Elevated Antibody Levels to Periodontopathic Organisms

    DTIC Science & Technology

    1990-01-01

    Slots, J. (1 983a) Actinobacillus actinomycetemcomitans in human periodontal disease: prevalence in patient groups and distribution of biotypes and...AD-A220 865 SECURITY CLASSIFICATION OF THIS PAGE REPORT DOCUMENTATION PAGE Form ApprovedOMB No. 0704-0181-7 la. REPORT SECURITY CLASSIFICATION Ib...RESTR ’rIVE MARKINGS UNCLASSIFIED NONE 2a. SECURITY CLASSIFICATION AUTHORITY 3. DISTRIBOTION/AVAILABILITY OF REPORT APPROVED FOR PUBLIC RELEASE; 2b

  1. What Are Sprains and Strains?

    MedlinePlus

    ... hands and arms a lot. Examples are gymnastics, tennis, rowing, and golf. People who play these sports sometimes strain their hand or arm. Elbow strains can also happen when playing sports. What ...

  2. Strain balanced quantum posts

    SciTech Connect

    Alonso-Alvarez, D.; Alen, B.; Ripalda, J. M.; Llorens, J. M.; Taboada, A. G.; Briones, F.; Roldan, M. A.; Hernandez-Saz, J.; Hernandez-Maldonado, D.; Herrera, M.; Molina, S. I.

    2011-04-25

    Quantum posts are assembled by epitaxial growth of closely spaced quantum dot layers, modulating the composition of a semiconductor alloy, typically InGaAs. In contrast with most self-assembled nanostructures, the height of quantum posts can be controlled with nanometer precision, up to a maximum value limited by the accumulated stress due to the lattice mismatch. Here, we present a strain compensation technique based on the controlled incorporation of phosphorous, which substantially increases the maximum attainable quantum post height. The luminescence from the resulting nanostructures presents giant linear polarization anisotropy.

  3. [Susceptibility of potential periodontopathic bacteria to metronidazole, spiramycin and their combination].

    PubMed

    Mouton, C; Dextraze, L; Mayrand, D

    1984-03-01

    A total of 65 bacterial strains originating mostly from subgingival plaque were tested for their susceptibilities to metronidazole, spiramycin, and their combination, ornidazole, erythromycin and tetracycline by means of an agar dilution technique. All agents were active against all anaerobic Gram-negative rods. Bacteroides gingivalis and Fusobacterium nucleatum showed marked susceptibility to metronidazole (MIC less than or equal to 0.06 microgram/ml) whereas 4-64 micrograms/ml were required to inhibit the capnophilic Actinobacillus actinomycetemcomitans and Capnocytophaga. Gram-positive facultatives were resistant to nitro-imidazoles but were inhibited at macrolide concentrations less than or equal to 0.5 microgram/ml. Except for F. nucleatum and Veillonella strains (2 less than or equal to MIC less than or equal to 128 micrograms/ml) macrolides were active against all other anaerobic bacteria tested. At concentrations less than or equal to 2 micrograms/ml the combination of spiramycin and metronidazole (2 : 1) was active against virtually all bacteria tested but our results failed to show a synergistic effect.

  4. Influence of Sublethal Antibiotic Concentrations on Bacterial Adherence to Saliva-Treated Hydroxyapatite

    PubMed Central

    Peros, W. J.; Gibbons, R. J.

    1982-01-01

    The influence of growth in the presence of sublethal concentrations of nine antibiotics on the ability of certain potentially odontopathic bacteria to attach to saliva-treated hydroxyapatite surfaces which mimic teeth was studied. Cells of Actinomyces viscosus LY7 and S2, Bacteroides gingivalis 381, Capnocytophaga ochraceus 6, and Actinobacillus actinomycetemcomitans N27 attached in lower numbers to saliva-treated hydroxyapatite when grown in the presence of 50% of the minimum inhibitory concentration of tetracycline. Electron microscopic observations of negatively stained preparations indicated that tetracycline-grown A. viscosus LY7 cells had fewer fimbriae than did untreated cells, which may account for the impaired ability of the treated cells to attach. However, cells of Actinomyces naeslundii L13 and S4 attached in higher numbers when grown in the presence of tetracycline, clindamycin, erythromycin, chloramphenicol, or neomycin. Streptococcus mutans strains H12 and JBP also exhibited increased adherence to saliva-treated hydroxyapatite when grown in the presence of 50 or 25% of the minimum inhibitory concentration of penicillin. Thus, growth in the presence of sublethal antibiotic concentrations could increase as well as decrease the adherence of bacteria to saliva-treated hydroxyapatite. Antibiotic-grown cells of the Actinomyces strains showed enhanced hemagglutination activity, but this did not correlate with their ability to attach to saliva-treated hydroxyapatite. Sublethal concentrations of antibiotics in the growth media also affected the coaggregation reactions of several organisms; the effects were specific for one member of the coaggregation pair. Images PMID:6274799

  5. Sadovskii vortex in strain

    NASA Astrophysics Data System (ADS)

    Freilich, Daniel; Llewellyn Smith, Stefan

    2014-11-01

    A Sadovskii vortex is a patch of fluid with uniform vorticity surrounded by a vortex sheet. Using a boundary element type method, we investigate the steady states of this flow in an incompressible, inviscid straining flow. Outside the vortex, the fluid is irrotational. In the limiting case where the entire circulation is due to the vortex patch, this is a patch vortex (Moore & Saffman, Aircraft wake turbulence and its detection 1971). In the other limiting case, where all the circulation is due to the vortex sheet, this is a hollow vortex (Llewellyn Smith and Crowdy, J. Fluid Mech. 691, 2012). This flow has two governing nondimensional parameters, relating the strengths of the straining field, vortex sheet, and patch vorticity. We study the relationship between these two parameters, and examine the shape of the resulting vortices. We also work towards a bifurcation diagram of the steady states of the Sadovskii vortex in an attempt to understand the connection between vortex sheet and vortex patch desingularizations of the point vortex. Support from NSF-CMMI-0970113.

  6. Repetitive strain injury.

    PubMed

    van Tulder, Maurits; Malmivaara, Antti; Koes, Bart

    2007-05-26

    Repetitive strain injury remains a controversial topic. The term repetitive strain injury includes specific disorders such as carpal tunnel syndrome, cubital tunnel syndrome, Guyon canal syndrome, lateral epicondylitis, and tendonitis of the wrist or hand. The diagnosis is usually made on the basis of history and clinical examination. Large high-quality studies using newer imaging techniques, such as MRI and ultrasonography are few. Consequently, the role of such imaging in diagnosis of upper limb disorders remains unclear. In many cases, no specific diagnosis can be established and complaints are labelled as non-specific. Little is known about the effectiveness of treatment options for upper limb disorders. Strong evidence for any intervention is scarce and the effect, if any, is mainly short-term pain relief. Exercise is beneficial for non-specific upper limb disorders. Immobilising hand braces and open carpal tunnel surgery release are beneficial for carpal tunnel syndrome, and topical and oral non-steroidal anti-inflammatory drugs, and corticosteroid injections are helpful for lateral epicondylitis. Exercise is probably beneficial for neck pain, as are corticosteroid injections and exercise for shoulder pain. Although upper limb disorders occur frequently in the working population, most trials have not exclusively included a working population or assessed effects on work-related outcomes. Further high-quality trials should aim to include sufficient sample sizes, working populations, and work-related outcomes.

  7. Strain Pattern in Supercooled Liquids

    NASA Astrophysics Data System (ADS)

    Illing, Bernd; Fritschi, Sebastian; Hajnal, David; Klix, Christian; Keim, Peter; Fuchs, Matthias

    2016-11-01

    Investigations of strain correlations at the glass transition reveal unexpected phenomena. The shear strain fluctuations show an Eshelby-strain pattern [˜cos (4 θ ) /r2 ], characteristic of elastic response, even in liquids, at long times. We address this using a mode-coupling theory for the strain fluctuations in supercooled liquids and data from both video microscopy of a two-dimensional colloidal glass former and simulations of Brownian hard disks. We show that the long-ranged and long-lived strain signatures follow a scaling law valid close to the glass transition. For large enough viscosities, the Eshelby-strain pattern is visible even on time scales longer than the structural relaxation time τ and after the shear modulus has relaxed to zero.

  8. Hydrogen production from microbial strains

    DOEpatents

    Harwood, Caroline S; Rey, Federico E

    2012-09-18

    The present invention is directed to a method of screening microbe strains capable of generating hydrogen. This method involves inoculating one or more microbes in a sample containing cell culture medium to form an inoculated culture medium. The inoculated culture medium is then incubated under hydrogen producing conditions. Once incubating causes the inoculated culture medium to produce hydrogen, microbes in the culture medium are identified as candidate microbe strains capable of generating hydrogen. Methods of producing hydrogen using one or more of the microbial strains identified as well as the hydrogen producing strains themselves are also disclosed.

  9. Strain relaxation in nanopatterned strained silicon round pillars

    NASA Astrophysics Data System (ADS)

    Himcinschi, C.; Singh, R.; Radu, I.; Milenin, A. P.; Erfurth, W.; Reiche, M.; Gösele, U.; Christiansen, S. H.; Muster, F.; Petzold, M.

    2007-01-01

    Periodic arrays of strained Si (sSi) round nanopillars were fabricated on sSi layers deposited on SiGe virtual substrates by electron-beam lithography and subsequent reactive-ion etching. The strain in the patterned sSi nanopillars was determined using high-resolution UV micro-Raman spectroscopy. The strain relaxes significantly upon nanostructuring: from 0.9% in the unpatterned sSi layer to values between 0.22% and 0.57% in the round sSi pillars with diameters from 100 up to 500nm. The strain distribution in the sSi nanopillars was analyzed by finite element (FE) modeling. The FE calculations confirm the strain relaxation after patterning, in agreement with the results obtained from Raman spectroscopy.

  10. Adaptor for Measuring Principal Strains with Tuckerman Strain Gage

    NASA Technical Reports Server (NTRS)

    Mcpherson, A E

    1943-01-01

    An adapter is described which uses three Tuckerman optical strain gages to measure the displacement of the three vortices of an equilateral triangle along lines 120 degrees apart. These displacements are substituted in well-known equations in order to compute the magnitude and direction of the principal strains. Tests of the adaptor indicate that principal strains over a gage length of 1.42 inch may be measured with a systematic error not exceeding 4 percent and a mean observational error of the order of + or minus 0.000006. The maximum observed error in strain was of the order of 0.00006. The directions of principal strains for unidirectional stress were measured with the adaptor with an average error of the order of 1 degree.

  11. Strained graphene Hall bar

    NASA Astrophysics Data System (ADS)

    Milovanović, S. P.; Peeters, F. M.

    2017-02-01

    The effects of strain, induced by a Gaussian bump, on the magnetic field dependent transport properties of a graphene Hall bar are investigated. The numerical simulations are performed using both classical and quantum mechanical transport theory and we found that both approaches exhibit similar characteristic features. The effects of the Gaussian bump are manifested by a decrease of the bend resistance, R B, around zero-magnetic field and the occurrence of side-peaks in R B. These features are explained as a consequence of bump-assisted scattering of electrons towards different terminals of the Hall bar. Using these features we are able to give an estimate of the size of the bump. Additional oscillations in R B are found in the quantum description that are due to the population/depopulation of Landau levels. The bump has a minor influence on the Hall resistance even for very high values of the pseudo-magnetic field. When the bump is placed outside the center of the Hall bar valley polarized electrons can be collected in the leads.

  12. Biomechanical strain of goldsmiths.

    PubMed

    Cândido, Paula Emanuela Fernandes; Teixeira, Juliana Vieira Schmidt; Moro, Antônio Renato Pereira; Gontijo, Leila Amaral

    2012-01-01

    The work of the goldsmiths consists in the manufacture of jewelry. The piece, be it an earring, bracelet or necklace, is hand-assembled. This task requires precision, skill, kindness and patience. In this work, we make use of tools such as cuticle clippers and rounded tip, beads or precious stones and also pieces of metal. This type of activity requires a biomechanical stress of hands and wrists. In order to quantify the biomechanical stress, we performed a case study to measure the movements performed by an assembly of pieces of jewelry. As method for research, filming was done during assembly of parts to a paste, using a Nikon digital camera, for 1 (one) hour. The film was edited by Kinovea software, and the task was divided into cycles, each cycle corresponds to a complete object. In one cycle, there are four two movements of supination and pronation movements of the forearm. The cycle lasts approximately sixteen seconds, totaling 1800 cycles in eight hours. Despite the effort required of the wrists, the activity shows no complaints from the employees, but this fact does not mischaracterizes the ability of employees to acquire repetitive strain injuries and work-related musculoskeletal disorders.

  13. Characterization of Salmonella enteritidis strains.

    PubMed Central

    Poppe, C; McFadden, K A; Brouwer, A M; Demczuk, W

    1993-01-01

    A study was conducted to characterize 318 Salmonella enteritidis strains that were mainly isolated from poultry and their environment in Canada. Biotype, phagetype (PT), plasmid profile (PP), hybridization with a plasmid-derived virulence sequence probe, antibiotic resistance, outer membrane proteins (OMPs), and lipopolysaccharide (LPS) profiles were determined. Relationships of these properties to one another, and their diagnostic and pathogenic significance were assessed. Biotyping indicated that failure to ferment rhamnose was sometimes useful as a marker for epidemiologically related strains. Phagetyping was the most effective method for subdividing S. enteritidis; it distinguished 12 PTs. Phagetype 13 was occasionally associated with septicemia and mortality in chickens. The strains belonged to 15 PPs. A 36 megadalton (MDa) plasmid was found in 97% of the strains. Only the 36 MDa plasmid hybridized with the probe. Seventeen percent of the strains were drug resistant; all strains were sensitive to ciprofloxacin. Thirty-five of 36 strains possessed the same OMP profile, and 36 of 41 strains contained smooth LPS. Images Fig. 1. PMID:8358678

  14. Difference Between Strain and Sprain.

    ERIC Educational Resources Information Center

    Connors, G. Patrick

    Provided in this description of the differences between a strain (damage to the muscle or tendon) and a sprain (damage to the ligament) are definitions of mild, moderate, and severe (first, second, and third degree) strains and sprains. A final caution is given that these are two separate and distinct problems and should be treated as such. (DC)

  15. Hypothetical strain-free oligoradicals

    PubMed Central

    Hoffmann, Roald; Eisenstein, Odile; Balaban, Alexandru T.

    1980-01-01

    Several new classes of oligoradicals free of angle strain are suggested and examined by means of molecular orbital calculations. The collapse products of these hypothetical radicals are highly strained molecules. Various electronic strategies for the stabilization of these oligoradicals have been explored. PMID:16592882

  16. Strain gage system evaluation program

    NASA Technical Reports Server (NTRS)

    Dolleris, G. W.; Mazur, H. J.; Kokoszka, E., Jr.

    1978-01-01

    A program was conducted to determine the reliability of various strain gage systems when applied to rotating compressor blades in an aircraft gas turbine engine. A survey of current technology strain gage systems was conducted to provide a basis for selecting candidate systems for evaluation. Testing and evaluation was conducted in an F 100 engine. Sixty strain gage systems of seven different designs were installed on the first and third stages of an F 100 engine fan. Nineteen strain gage failures occurred during 62 hours of engine operation, for a survival rate of 68 percent. Of the failures, 16 occurred at blade-to-disk leadwire jumps (84 percent), two at a leadwire splice (11 percent), and one at a gage splice (5 percent). Effects of erosion, temperature, G-loading, and stress levels are discussed. Results of a post-test analysis of the individual components of each strain gage system are presented.

  17. Strain Insensitive Optical Phase Locked Loop

    NASA Technical Reports Server (NTRS)

    Egalon, Claudio O. (Inventor); Rogowski, Robert S. (Inventor)

    1998-01-01

    A strain sensor uses optical fibers including strain insensitive portions and a strain sensitive portion. The optical fibers form a sensitive arm of an optical phase locked loop (OPLL). The use of the OPLL allows for multimode optical fiber to be used in a strain insensitive configuration. Only strain information for the strain sensitive portion is monitored rather than the integrated strain measurements commonly made with optical fiber sensors.

  18. High temperature strain measurement with a resistance strain gage

    NASA Technical Reports Server (NTRS)

    Lei, Jih-Fen; Fichtel, ED; Mcdaniel, Amos

    1993-01-01

    A PdCr based electrical resistance strain gage was demonstrated in the laboratory to be a viable sensor candidate for static strain measurement at high temperatures. However, difficulties were encountered while transferring the sensor to field applications. This paper is therefore prepared for recognition and resolution of the problems likely to be encountered with PdCr strain gages in field applications. Errors caused by the measurement system, installation technique and lead wire attachment are discussed. The limitations and some considerations related to the temperature compensation technique used for this gage are also addressed.

  19. Recent advances in echocardiography: strain and strain rate imaging

    PubMed Central

    Mirea, Oana; Duchenne, Jurgen; Voigt, Jens-Uwe

    2016-01-01

    Deformation imaging by echocardiography is a well-established research tool which has been gaining interest from clinical cardiologists since the introduction of speckle tracking. Post-processing of echo images to analyze deformation has become readily available at the fingertips of the user. New parameters such as global longitudinal strain have been shown to provide added diagnostic value, and ongoing efforts of the imaging societies and industry aimed at harmonizing methods will improve the technique further. This review focuses on recent advances in the field of echocardiographic strain and strain rate imaging, and provides an overview on its current and potential future clinical applications. PMID:27158476

  20. PnuC and the utilization of the nicotinamide riboside analog 3-aminopyridine in Haemophilus influenzae.

    PubMed

    Sauer, Elizabeta; Merdanovic, Melisa; Mortimer, Anne Price; Bringmann, Gerhard; Reidl, Joachim

    2004-12-01

    The utilization pathway for the uptake of NAD and nicotinamide riboside was previously characterized for Haemophilus influenzae. We now report on the cellular location, topology, and substrate specificity of PnuC. pnuC of H. influenzae is only distantly related to pnuC of Escherichia coli and Salmonella enterica serovar Typhimurium. When E. coli PnuC was expressed in an H. influenzae pnuC mutant, it was able to take up only nicotinamide riboside and not nicotinamide mononucleotide. Therefore, we postulated that PnuC transporters in general possess specificity for nicotinamide riboside. Earlier studies showed that 3-aminopyridine derivatives (e.g., 3-aminopyridine adenine dinucleotide) are inhibitory for H. influenzae growth. By testing characterized strains with mutations in the NAD utilization pathway, we show that 3-aminopyridine riboside is inhibitory to H. influenzae and is taken up by the NAD-processing and nicotinamide riboside route. 3-Aminopyridine riboside is utilized effectively in a pnuC+ background. In addition, we demonstrate that 3-aminopyridine adenine dinucleotide resynthesis is produced by NadR. 3-Aminopyridine riboside-resistant H. influenzae isolates were characterized, and mutations in nadR could be detected. We also tested other species of the family Pasteurellaceae, Pasteurella multocida and Actinobacillus actinomycetemcomitans, and found that 3-aminopyridine riboside does not act as a growth inhibitor; hence, 3-aminopyridine riboside represents an anti-infective agent with a very narrow host range.

  1. Polyclonal B-cell activation induced by extracts of Gram-negative bacteria isolated from periodontally diseased sites.

    PubMed Central

    Bick, P H; Carpenter, A B; Holdeman, L V; Miller, G A; Ranney, R R; Palcanis, K G; Tew, J G

    1981-01-01

    The objective of this research was to determine whether gram-negative bacteria frequently isolated from periodontally diseased sites contained polyclonal B-cell activators. Polyclonal B-cell activation, which results in nonspecific activation of multiple B-cell clones was analyzed by a hemolysis-in-gel assay designed to detect a broad range of antibody specificities. Extracts from numerous bacterial strains, including Bacteroides gingivalis, Bacteroides melaninogenicus subsp. melaninogenicus, B. melaninogenicus subsp. intermedius, Fusobacterium nucleatum, Selenomonas sputigena, Capnocytophaga ochracea, and Actinobacillus actinomycetemcomitans, were tested. Extracts of the above organisms were found to stimulate polyclonal antibody responses in cultures of normal human peripheral blood lymphocytes, although the magnitude of stimulation varied among the extracts. Optimal antibody-forming cell responses were found at stimulator doses between 5 and 1,000 micrograms/ml. We conclude that the resident gram-negative subgingival flora associated with periodontal lesions possesses potent polyclonal B-cell activators. These activators may contribute to disease pathogenesis by inducing B lymphocytes to produce antibody, osteolytic factors, or both and possibly other mediators of inflammation. PMID:6975240

  2. Low TCR nanocomposite strain gages

    NASA Technical Reports Server (NTRS)

    Gregory, Otto J. (Inventor); Chen, Ximing (Inventor)

    2012-01-01

    A high temperature thin film strain gage sensor capable of functioning at temperatures above 1400.degree. C. The sensor contains a substrate, a nanocomposite film comprised of an indium tin oxide alloy, zinc oxide doped with alumina or other oxide semiconductor and a refractory metal selected from the group consisting of Pt, Pd, Rh, Ni, W, Ir, NiCrAlY and NiCoCrAlY deposited onto the substrate to form an active strain element. The strain element being responsive to an applied force.

  3. Virtual strain gage size study

    SciTech Connect

    Reu, Phillip L.

    2015-09-22

    DIC is a non-linear low-pass spatial filtering operation; whether we consider the effect of the subset and shape function, the strain window used in the strain calculation, of other post-processing of the results, each decision will impact the spatial resolution, of the measurement. More fundamentally, the speckle size limits, the spatial resolution by dictating the smallest possible subset. After this decision the processing settings are controlled by the allowable noise level balanced by possible bias errors created by the data filtering. This article describes a process to determine optimum DIC software settings to determine if the peak displacements or strains are being found.

  4. Radio Frequency (RF) strain monitor

    NASA Technical Reports Server (NTRS)

    Heyman, Joseph S. (Inventor); Rogowski, Robert S. (Inventor); Holben, Milford S., Jr. (Inventor)

    1988-01-01

    This invention relates to an apparatus for measuring strain in a structure. In particular, the invention detects strain in parts per million to over ten percent along an entire length (or other dimension) of a structure measuring a few millimeters to several kilometers. By using a propagation path bonded to the structure, the invention is not limited by the signal attenuation characteristics of the structure and thus frequencies in the megahertz to gigahertz range may be used to detect strain in part per million to over ten percent with high precision.

  5. Strain accumulation in quasicrystalline solids

    NASA Technical Reports Server (NTRS)

    Nori, Franco; Ronchetti, Marco; Elser, Veit

    1988-01-01

    The relaxation of two-dimensional quasicrystalline elastic networks when their constituent bonds are perturbed homogeneously is studied. Whereas ideal, quasi-periodic networks are stable against such perturbations, significant accumulations of strain in a class of disordered networks generated by a growth process are found. The grown networks are characterized by root mean square phason fluctuations which grow linearly with system size. The strain accumulation observed in these networks also grows linearly with system size. Finally, dependence of strain accumulation on cooling rate is found.

  6. PLASTICITY AND NON-LINEAR ELASTIC STRAINS

    DTIC Science & Technology

    conditions existing in plane waves in an extended medium to give the time rate of change of stress as a function of the time rate of change of strain, the stress invariants, the total strain and the plastic strain. (Author)

  7. Magnetic Domain Strain Sensor Program

    DTIC Science & Technology

    1990-08-01

    static strain measurement at elevated temperatures. 2.2 Magnetic Strain Measurement Theory The initial work at GED investigated the Barkhausen effect...including large and small Barkhausen jumps. This is a wave propaga- tion phenomenon in which a magnetic wave velocity is measured. The wave velocity in a...theory explaining the phenomenon that deviates from the Barkhausen effect. Some basic concepts had to be examined to better understand magnetic phenomena

  8. HIGH-TEMPERATURE STRAIN GAGE,

    DTIC Science & Technology

    The patent involves a high-temperature tensometer consisting of a strain-sensitive wire grid, a connecting and insulating material, a sub-layer of...heat-resistant material, deposited on the part being investigated or on a backing by gas flame deposition, and a connector to fasten the strain...adhesion, the tension-sensitive wire grid is fastened through the sub-layer to the part being tested by the connecting and insulating material. (Author)

  9. NUTRITION OF FIVE BACTEROIDES STRAINS

    PubMed Central

    Quinto, Grace

    1962-01-01

    Quinto, Grace (University of Kentucky College of Medicine, Lexington). Nutrition of five Bacteroides strains. J. Bacteriol. 84:559–562. 1962.—Some of the nutritional requirements of five gram-negative anaerobic bacilli, including Ristella perfoetens, Zuberella clostridiformis, and three Bacteroides strains freshly isolated from clinical exudates, were investigated. A fluid maintenance medium was developed in which the three freshly isolated strains, C-4, C-7, and C-2795, grew maximally in 12 to 24 hr. The maintenance medium contained 2.0% Trypticase and Proteose Peptone, 0.5% glucose, and 0.1% sodium thioglycolate; it was adjusted to pH 7.2 and supplemented with 0.1 μg of hemin/ml. Strains C-4, C-7, and C-2795 were cultivated through 14 serial cultures in fluid maintenance medium containing 0.1 μg of hemin/ml. The most satisfactory inoculum was a 1:100 or 1:1,000 dilution of a 24-hr seed culture. All the strains except Z. clostridiformis grew serially in a defined medium. R. perfoetens required pantothenic acid, nicotinic acid, and the following amino acids: histidine, tryptophan, tyrosine, valine, phenylalanine, cystine, and probably arginine, glutamic acid, methionine, glycine, isoleucine, leucine, and lysine. The C-4, C-7, and C-2795 strains required the hemin supplement in defined medium, but not vitamins, purines, or pyrimidines. PMID:13972793

  10. Applications of strained layer superlattices

    NASA Astrophysics Data System (ADS)

    Smith, D. L.; Laurich, B. K.; Mailhiot, C.

    1990-04-01

    Because of different band edge lineups, strain conditions, and growth orientations, various strained layer superlattice (SLS) materials can exhibit qualitatively new physical behavior in their optical properties. Two examples are given of new physical behavior in SLS: strain generated electric fields in polar growth axis superlattices and strained type 2 superlattices. In SLS, large electric fields can be generated by the piezoelectric effect. The fields are largest for SLS with a (111) growth axis; they vanish for SLS with a (100) growth axis. The strain generated electric fields strongly modify the optical properties of the superlattice. Photogenerated electron-hole pairs screen the fields leading to a large nonlinear optical response. Application of an external electric field leads to a large linear electrooptical response. The absorption edge can be either red or blue shifted. Optical studies of (100), (111), and (211) oriented GaInAs/GaAs superlattices confirm the existence of the strain generated electric fields. Small band gap semiconductors are useful for making intrinsic long wavelength infrared detectors. Arbitrarily small band gaps can be reached in the type 2 superlattice InAs/GaSb. However, for band gaps less than 0.1 eV, the layer thicknesses are large and the overlap of electron and hole wavefunctions are small. Thus, the absorption coefficient is too small for useful infrared (IR) detection. Including In in the GaSb introduces strain in he InAs/GaInSb superlattice which shifts the band edges so that small band gaps can be reached in thin layer superlattices. Good absorption at long IR wavelengths is thus achieved.

  11. Magnetic susceptibility, petrofabrics and strain

    NASA Astrophysics Data System (ADS)

    Borradaile, Graham John

    1988-12-01

    Magnetic susceptibility is a non-destructive technique for quantifying the average fabric of a small sample of rock. The interpretation of the magnetic fabric is not always straightforward. However, the principal directions of the magnitude ellipsoid of susceptibility commonly show orientations consistent with the kinematic interpretations of folds, shear zones and other structural features. The directions may correspond with the orientations of strained objects or with the planar-linear mineral orientations. There will usually be multiple mineralogical sources of susceptibility, often involving silicates. If the sources are known, or if the susceptibility can be attributed to a single mineral species, it may be possible to establish a correlation between the strain ellipsoid and the susceptibility ellipsoid. This correlation will be of principal directions in many instances and occasionally there may be a weak correlation of strain magnitudes as well. In other circumstances it may be possible to establish a correlation between changes in susceptibility and the strain. Nevertheless magnetic fabric studies are not routine substitutes for strain analysis. Even where information on strain is not provided, the magnetic fabrics (and subfabrics) yield a measure of the preferred crystallographic orientation or preferred dimensional orientation of the minerals that may be integrated profitably with other petrofabric data. Experimental deformation of certain synthetic aggregates indicates that directions of magnetic susceptibility spin rapidly with advancing strain, especially where the matrix grains undergo crystal-plastic deformation. In certain experiments, simple shear appears to change the intensity of magnetic fabric more effectively than pure shear. Experiments indicate also that the initial anisotropy of a rock-like material is not easily overprinted by deformation whereas field studies are equivocal.

  12. G(-) anaerobes-reactive CD4+ T-cells trigger RANKL-mediated enhanced alveolar bone loss in diabetic NOD mice.

    PubMed

    Mahamed, Deeqa A; Marleau, Annette; Alnaeeli, Mawadda; Singh, Bhagirath; Zhang, Xiaoxia; Penninger, Joseph M; Teng, Yen-Tung A

    2005-05-01

    Diabetic patients experience a higher risk for severe periodontitis; however, the underlying mechanism remains unclear. We investigated the contribution of antibacterial T-cell-mediated immunity to enhanced alveolar bone loss during periodontal infection in nonobese diabetic (NOD) mice by oral inoculation with Actinobacillus actinomycetemcomitans, a G(-) anaerobe responsible for juvenile and severe periodontitis. The results show that 1) inoculation with A. actinomycetemcomitans in pre-diabetic NOD mice does not alter the onset, incidence, and severity of diabetes; 2) after A. actinomycetemcomitans inoculation, diabetic NOD mice (blood glucose >200 mg/dl and with severe insulitis) exhibit significantly higher alveolar bone loss compared with pre-diabetic and nondiabetic NOD mice; and 3) A. actinomycetemcomitans-reactive CD4+ T-cells in diabetic mice exhibit significantly higher proliferation and receptor activator of nuclear factor kappaB ligand (RANKL) expression. When diabetic mice are treated with the RANKL antagonist osteoprotegerin (OPG), there is a significant reversal of alveolar bone loss, as well as reduced RANKL expression in A. actinomycetemcomitans-reactive CD4+ T-cells. This study clearly describes the impact of autoimmunity to anaerobic infection in an experimental periodontitis model of type 1 diabetes. Thus, microorganism-reactive CD4+ T-cells and the RANKL-OPG axis provide the molecular basis of the advanced periodontal breakdown in diabetes and, therefore, OPG may hold therapeutic potential for treating bone loss in diabetic subjects at high risk.

  13. Optical Strain Measurement System Development

    NASA Technical Reports Server (NTRS)

    Lant, C. T.

    1985-01-01

    Investigations of physical phenomena affecting the durability of SSME components require measurement systems operational in hostile environments. The need for such instrumentation caused the definition and operation of an optical strain measurement system. This optical strain measurement system based on the speckle shift method is being developed. This is a noncontact, automatic method of measuring surface strain in one dimension that corrects for error due to rigid body motion. It provides a gauge length of 1 to 2 mm and allows the region of interest on the test specimen to be mapped point by point. The output is a graphics map of the points inspected on the specimen; data points is stored in quasi-real time. This is the first phase of a multiphase effort in optical strain measurement. The speckle pattern created by the test specimen is interpreted as high order interference fringes resulting from a random diffraction grating, being the natural surface roughness of the specimen. Strain induced on the specimen causes a change in spacing of the surface roughness, which in turn shifts the position of the interference pattern (speckles).

  14. Measuring mine roof bolt strains

    DOEpatents

    Steblay, Bernard J.

    1986-01-01

    A mine roof bolt and a method of measuring the strain in mine roof bolts of this type are disclosed. According to the method, a flat portion on the head of the mine roof bolt is first machined. Next, a hole is drilled radially through the bolt at a predetermined distance from the bolt head. After installation of the mine roof bolt and loading, the strain of the mine roof bolt is measured by generating an ultrasonic pulse at the flat portion. The time of travel of the ultrasonic pulse reflected from the hole is measured. This time of travel is a function of the distance from the flat portion to the hole and increases as the bolt is loaded. Consequently, the time measurement is correlated to the strain in the bolt. Compensation for various factors affecting the travel time are also provided.

  15. Photoacoustic spectroscopy of Entamoeba histolytica strains

    NASA Astrophysics Data System (ADS)

    Acosta-Avalos, D.; Alvarado-Gil, J. J.; Silva, E. F.; Orozco, E.; de Menezes, L. F.; Vargas, H.

    2005-06-01

    Pathogenic and non-pathogenic strains of E. histolytica are studied using photoacoustic spectroscopy. It is shown that the pathogenic strain presents a spectrum similar to that of iron sulfur proteins. The non-pathogenic strain does not show any relevant absorption at the studied wavelength range. The differences observed between the optical absorption spectra of both strains opens the possibility of using photoacoustic spectroscopy as a reliable and simple technique to identify different types of E. histolytica strains.

  16. Characterization of strains of Corynebacterium bovis.

    PubMed Central

    Brooks, B W; Barnum, D A

    1984-01-01

    The biochemical and morphological characteristics of 104 strains of Corynebacterium bovis isolated from bovine milk samples and the C. bovis reference strain were found to be uniform. Valuable criteria for identification were presence of catalase and oxidase, production of acid from glucose and fructose and a requirement for enriched basal media. Six strains of human and three strains of bovine origin were found to be inconsistent with the reference strain. PMID:6722650

  17. Chronic occupational repetitive strain injury.

    PubMed Central

    O'Neil, B. A.; Forsythe, M. E.; Stanish, W. D.

    2001-01-01

    OBJECTIVE: To review common repetitive strain injuries (RSIs) that occur in the workplace, emphasizing diagnosis, treatment, and etiology of these conditions. QUALITY OF EVIDENCE: A MEDLINE search from January 1966 to June 1999 focused on articles published since 1990 because RSIs are relatively new diagnoses. MeSH headings that were explored using the thesaurus included "cumulative trauma disorder," "overuse injury," and "repetitive strain injury." The search was limited to English articles only, and preference was given to randomized controlled trials. MAIN MESSAGE: Repetitive strain injuries result from repeated stress to the body's soft tissue structures including muscles, tendons, and nerves. They often occur in patients who perform repetitive movements either in their jobs or in extracurricular activities. Common RSIs include tendon-related disorders, such as rotator cuff tendonitis, and peripheral nerve entrapment disorders, such as carpal tunnel syndrome. A careful history and physical examination often lead to the diagnosis, but newer imaging techniques, such as magnetic resonance imaging and ultrasound, can help in refractory cases. Conservative management with medication, physiotherapy, or bracing is the mainstay of treatment. Surgery is reserved for cases that do not respond to treatment. CONCLUSION: Repetitive strain injury is common; primary care physicians must establish a diagnosis and, more importantly, its relationship to occupation. Treatment can be offered by family physicians who refer to specialists for cases refractory to conservative management. PMID:11228032

  18. Trials with a Strain Gauge.

    ERIC Educational Resources Information Center

    Auty, Geoff

    1996-01-01

    Describes an attempt to match the goals of the practical demonstration of the use of a strain gauge and the technical applications of science and responding to student questions in early trials, while keeping within the level of electronics in advanced physics. (Author/JRH)

  19. Bacteriocins and novel bacterial strains.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Poultry is thought to be a significant source of Campylobacter in human disease. We evaluated anti-Campylobacter activity among 365 Bacillus and Paenibacillus isolates from poultry. One novel antagonistic Bacillus circulans and three Paenibacillus polymyxa strains were identified and further studi...

  20. Extreme Temperature Strain Measurement System

    DTIC Science & Technology

    1990-08-01

    Electrix Industries, Inc., P.O. Box 306, Lombard, IL 60148, Phone (312) 627-6802 38 Foil Strain gages. ° HiTEC Corp., Nardone Industrial Park...Planer Ltd., CERL-Planer Capacitive Transducer, Windmill Road, Sunbury -on- Thames, Middx., England, Phone: Sunbury 86262-3-4-5 • HiTEC Corp., Nardone

  1. A NEW STRAIN OF TRANSMISSIBLE LEUCEMIA IN FOWLS (STRAIN H).

    PubMed

    Ellermann, V

    1921-03-31

    1. A new strain of fowl leucosis has been transmitted through twelve generations of fowls. 2. An increase in virulence was observed during its passage. This was shown in a shortening of the interval between inoculation and death. The increase in virulence does not affect the number of successful inoculations, which remains approximately constant in from 20 to 40 per cent of the birds employed. 3. As with former strains, the disease manifests itself in various forms; i.e., myeloid and intravascular lymphoid types. A single lymphatic case was observed. 4. In several intravascular cases a diminution in the hemolytic power of the serum was established. This phenomenon was absent in a number of myeloid cases. 5. Active immunization cannot be produced by means of the subcutaneous injection of virulent material. 6. The finding of previous experiments that the virus is filterable has been confirmed. 7. The inoculation of human leucemic material into fowls gave negative results.

  2. Material mechanical characterization method for multiple strains and strain rates

    SciTech Connect

    Erdmand, III, Donald L.; Kunc, Vlastimil; Simunovic, Srdjan; Wang, Yanli

    2016-01-19

    A specimen for measuring a material under multiple strains and strain rates. The specimen including a body having first and second ends and a gage region disposed between the first and second ends, wherein the body has a central, longitudinal axis passing through the first and second ends. The gage region includes a first gage section and a second gage section, wherein the first gage section defines a first cross-sectional area that is defined by a first plane that extends through the first gage section and is perpendicular to the central, longitudinal axis. The second gage section defines a second cross-sectional area that is defined by a second plane that extends through the second gage section and is perpendicular to the central, longitudinal axis and wherein the first cross-sectional area is different in size than the second cross-sectional area.

  3. Strains

    MedlinePlus

    Pulled muscle ... can include: Pain and difficulty moving the injured muscle Discolored and bruised skin Swelling ... if you still have pain. Rest the pulled muscle for at least a day. If possible, keep ...

  4. Modelling to very high strains

    NASA Astrophysics Data System (ADS)

    Bons, P. D.; Jessell, M. W.; Griera, A.; Evans, L. A.; Wilson, C. J. L.

    2009-04-01

    Ductile strains in shear zones often reach extreme values, resulting in typical structures, such as winged porphyroclasts and several types of shear bands. The numerical simulation of the development of such structures has so far been inhibited by the low maximum strains that numerical models can normally achieve. Typical numerical models collapse at shear strains in the order of one to three. We have implemented a number of new functionalities in the numerical platform "Elle" (Jessell et al. 2001), which significantly increases the amount of strain that can be achieved and simultaneously reduces boundary effects that become increasingly disturbing at higher strain. Constant remeshing, while maintaining the polygonal phase regions, is the first step to avoid collapse of the finite-element grid required by finite-element solvers, such as Basil (Houseman et al. 2008). The second step is to apply a grain-growth routine to the boundaries of polygons that represent phase regions. This way, the development of sharp angles is avoided. A second advantage is that phase regions may merge or become separated (boudinage). Such topological changes are normally not possible in finite element deformation codes. The third step is the use of wrapping vertical model boundaries, with which optimal and unchanging model boundaries are maintained for the application of stress or velocity boundary conditions. The fourth step is to shift the model by a random amount in the vertical direction every time step. This way, the fixed horizontal boundary conditions are applied to different material points within the model every time step. Disturbing boundary effects are thus averaged out over the whole model and not localised to e.g. top and bottom of the model. Reduction of boundary effects has the additional advantage that model can be smaller and, therefore, numerically more efficient. Owing to the combination of these existing and new functionalities it is now possible to simulate the

  5. Strain tolerant microfilamentary superconducting wire

    DOEpatents

    Finnemore, Douglas K.; Miller, Theodore A.; Ostenson, Jerome E.; Schwartzkopf, Louis A.; Sanders, Steven C.

    1993-02-23

    A strain tolerant microfilamentary wire capable of carrying superconducting currents is provided comprising a plurality of discontinuous filaments formed from a high temperature superconducting material. The discontinuous filaments have a length at least several orders of magnitude greater than the filament diameter and are sufficiently strong while in an amorphous state to withstand compaction. A normal metal is interposed between and binds the discontinuous filaments to form a normal metal matrix capable of withstanding heat treatment for converting the filaments to a superconducting state. The geometry of the filaments within the normal metal matrix provides substantial filament-to-filament overlap, and the normal metal is sufficiently thin to allow supercurrent transfer between the overlapped discontinuous filaments but is also sufficiently thick to provide strain relief to the filaments.

  6. Virtual strain gage size study

    DOE PAGES

    Reu, Phillip L.

    2015-09-22

    DIC is a non-linear low-pass spatial filtering operation; whether we consider the effect of the subset and shape function, the strain window used in the strain calculation, of other post-processing of the results, each decision will impact the spatial resolution, of the measurement. More fundamentally, the speckle size limits, the spatial resolution by dictating the smallest possible subset. After this decision the processing settings are controlled by the allowable noise level balanced by possible bias errors created by the data filtering. This article describes a process to determine optimum DIC software settings to determine if the peak displacements or strainsmore » are being found.« less

  7. Strain softening in stretched DNA

    PubMed Central

    Luan, Binquan; Aksimentiev, Aleksei

    2010-01-01

    The microscopic mechanics of DNA stretching was characterized using extensive molecular dynamics simulations. By employing an anisotropic pressure control method, realistic force-extension dependences of effectively infinite DNA molecules were obtained. A coexistence of B- and S-DNA domains was observed during the overstretching transition. The simulations revealed that strain softening may occur in the process of stretching torsionally constrained DNA. The latter observation was qualitatively reconciled with available experimental data using a random-field Ising model. PMID:18851334

  8. High Temperature Capacitive Strain Gage

    NASA Technical Reports Server (NTRS)

    Wnuk, Stephen P., Jr.; Wnuk, Stephen P., III; Wnuk, V. P.

    1990-01-01

    Capacitive strain gages designed for measurements in wind tunnels to 2000 F were built and evaluated. Two design approaches were followed. One approach was based on fixed capacitor plates with a movable ground plane inserted between the plates to effect differential capacitive output with strain. The second approach was based on movable capacitor plates suspended between sapphire bearings, housed in a rugged body, and arranged to operate as a differential capacitor. A sapphire bearing gage (1/4 in. diameter x 1 in. in size) was built with a range of 50,000 and a resolution of 200 microstrain. Apparent strain on Rene' 41 was less than + or - 1000 microstrain from room temperature to 2000 F. Three gage models were built from the Ground Plane Differential concept. The first was 1/4 in. square by 1/32 in. high and useable to 700 F. The second was 1/2 in. square by 1/16 in. high and useable to 1440 F. The third, also 1/2 in. square by 1/16 in. high was expected to operate in the 1600 to 2000 F range, but was not tested because time and funding ended.

  9. High temperature capacitive strain gage

    NASA Astrophysics Data System (ADS)

    Wnuk, Stephen P., Jr.; Wnuk, Stephen P., III; Wnuk, V. P.

    1990-01-01

    Capacitive strain gages designed for measurements in wind tunnels to 2000 F were built and evaluated. Two design approaches were followed. One approach was based on fixed capacitor plates with a movable ground plane inserted between the plates to effect differential capacitive output with strain. The second approach was based on movable capacitor plates suspended between sapphire bearings, housed in a rugged body, and arranged to operate as a differential capacitor. A sapphire bearing gage (1/4 in. diameter x 1 in. in size) was built with a range of 50,000 and a resolution of 200 microstrain. Apparent strain on Rene' 41 was less than + or - 1000 microstrain from room temperature to 2000 F. Three gage models were built from the Ground Plane Differential concept. The first was 1/4 in. square by 1/32 in. high and useable to 700 F. The second was 1/2 in. square by 1/16 in. high and useable to 1440 F. The third, also 1/2 in. square by 1/16 in. high was expected to operate in the 1600 to 2000 F range, but was not tested because time and funding ended.

  10. Strain-Detecting Composite Materials

    NASA Technical Reports Server (NTRS)

    Wallace, Terryl A. (Inventor); Smith, Stephen W. (Inventor); Piascik, Robert S. (Inventor); Horne, Michael R. (Inventor); Messick, Peter L. (Inventor); Alexa, Joel A. (Inventor); Glaessgen, Edward H. (Inventor); Hailer, Benjamin T. (Inventor)

    2016-01-01

    A composite material includes a structural material and a shape-memory alloy embedded in the structural material. The shape-memory alloy changes crystallographic phase from austenite to martensite in response to a predefined critical macroscopic average strain of the composite material. In a second embodiment, the composite material includes a plurality of particles of a ferromagnetic shape-memory alloy embedded in the structural material. The ferromagnetic shape-memory alloy changes crystallographic phase from austenite to martensite and changes magnetic phase in response to the predefined critical macroscopic average strain of the composite material. A method of forming a composite material for sensing the predefined critical macroscopic average strain includes providing the shape-memory alloy having an austenite crystallographic phase, changing a size and shape of the shape-memory alloy to thereby form a plurality of particles, and combining the structural material and the particles at a temperature of from about 100-700.degree. C. to form the composite material.

  11. Classification, Identification, and Clinical Significance of Haemophilus and Aggregatibacter Species with Host Specificity for Humans

    PubMed Central

    2014-01-01

    SUMMARY The aim of this review is to provide a comprehensive update on the current classification and identification of Haemophilus and Aggregatibacter species with exclusive or predominant host specificity for humans. Haemophilus influenzae and some of the other Haemophilus species are commonly encountered in the clinical microbiology laboratory and demonstrate a wide range of pathogenicity, from life-threatening invasive disease to respiratory infections to a nonpathogenic, commensal lifestyle. New species of Haemophilus have been described (Haemophilus pittmaniae and Haemophilus sputorum), and the new genus Aggregatibacter was created to accommodate some former Haemophilus and Actinobacillus species (Aggregatibacter aphrophilus, Aggregatibacter segnis, and Aggregatibacter actinomycetemcomitans). Aggregatibacter species are now a dominant etiology of infective endocarditis caused by fastidious organisms (HACEK endocarditis), and A. aphrophilus has emerged as an important cause of brain abscesses. Correct identification of Haemophilus and Aggregatibacter species based on phenotypic characterization can be challenging. It has become clear that 15 to 20% of presumptive H. influenzae isolates from the respiratory tracts of healthy individuals do not belong to this species but represent nonhemolytic variants of Haemophilus haemolyticus. Due to the limited pathogenicity of H. haemolyticus, the proportion of misidentified strains may be lower in clinical samples, but even among invasive strains, a misidentification rate of 0.5 to 2% can be found. Several methods have been investigated for differentiation of H. influenzae from its less pathogenic relatives, but a simple method for reliable discrimination is not available. With the implementation of identification by matrix-assisted laser desorption ionization–time of flight mass spectrometry, the more rarely encountered species of Haemophilus and Aggregatibacter will increasingly be identified in clinical microbiology

  12. Strains and Sprains Are a Pain

    MedlinePlus

    ... strain at some point. Strains and sprains are common injuries, especially for kids who are very active or ... such as twisting your ankle. This kind of injury is common in sports, but also can happen any time ...

  13. Strain Monitoring of Flexible Structures

    NASA Technical Reports Server (NTRS)

    Litteken, Douglas A.

    2017-01-01

    , such as tensile testing, fatigue testing, and shear testing, but common measurement techniques cannot be used on fabric. Measuring strain in a material and during a test is a critical parameter for an engineer to monitor the structure during the test and correlate to an analytical model. The ability to measure strain in fabric structures is a challenge for NASA. Foil strain gauges, for example, are commonplace on metallic structures testing, but are extremely difficult to interface with a fabric substrate. New strain measuring techniques need to be developed for use with fabric structures. This paper investigates options for measuring strain in fabric structures for both ground testing and in-space structural health monitoring. It evaluates current commercially available options and outlines development work underway to build custom measurement solutions for NASA's fabric structures.

  14. Turbulent Plane Wakes Subjected to Successive Strains

    NASA Technical Reports Server (NTRS)

    Rogers, Michael M.

    2003-01-01

    Six direct numerical simulations of turbulent time-evolving strained plane wakes have been examined to investigate the response of a wake to successive irrotational plane strains of opposite sign. The orientation of the applied strain field has been selected so that the flow is the time-developing analogue of a spatially developing wake evolving in the presence of either a favourable or an adverse streamwise pressure gradient. The magnitude of the applied strain rate a is constant in time t until the total strain e(sup at) reaches about four. At this point, a new simulation is begun with the sign of the applied strain being reversed (the original simulation is continued as well). When the total strain is reduced back to its original value of one, yet another simulation is begun with the sign of the strain being reversed again back to its original sign. This process is done for both initially "favourable" and initially "adverse" strains, providing simulations for each of these strain types from three different initial conditions. The evolution of the wake mean velocity deficit and width is found to be very similar for all the adversely strained cases, with both measures rapidly achieving exponential growth at the rate associated with the cross-stream expansive strain e(sup at). In the "favourably" strained cases, the wake widths approach a constant and the velocity deficits ultimately decay rapidly as e(sup -2at). Although all three of these cases do exhibit the same asymptotic exponential behaviour, the time required to achieve this is longer for the cases that have been previously adversely strained (by at approx. equals 1). These simulations confirm the generality of the conclusions drawn in Rogers (2002) regarding the response of plane wakes to strain. The evolution of strained wakes is not consistent with the predictions of classical self-similar analysis; a more general equilibrium similarity solution is required to describe the results. At least for the cases

  15. Using BEEM To Probe Strains In Semiconductors

    NASA Technical Reports Server (NTRS)

    Bell, L. Douglas; Milliken, Autumn M.; Manion, Stephen J.; Kaiser, William J.

    1996-01-01

    Ballistic-electron-emission microscopy (BEEM) useful in determining strains in semiconductors under some conditions. More specifically, BEEM is variant of scanning tunneling microscopy and sensitive to electronic structure of probed material. In present approach, BEEM used to obtain data on those aspects of variations in electronic structures related to variations in strains. Then by use of mathematical modeling of relationships between electronic structures and strains, variations in strains deduced from BEEM data.

  16. Temperature-Compensating Inactive Strain Gauge

    NASA Technical Reports Server (NTRS)

    Moore, Thomas C., Sr.

    1993-01-01

    Thermal contribution to output of active gauge canceled. High-temperature strain gauges include both active gauge wires sensing strains and inactive gauge wires providing compensation for thermal contributions to gauge readings. Inactive-gauge approach to temperature compensation applicable to commercially available resistance-type strain gauges operating at temperatures up to 700 degrees F and to developmental strain gauges operating at temperatures up to 2,000 degrees F.

  17. Optical Fibers Would Sense Local Strains

    NASA Technical Reports Server (NTRS)

    Egalon, Claudio O.; Rogowski, Robert S.

    1994-01-01

    Proposed fiber-optic transducers measure local strains. Includes lead-in and lead-out lengths producing no changes in phase shifts, plus short sensing length in which phase shift is sensitive to strain. Phase shifts in single-mode fibers vary with strains. In alternative version, multiple portions of optical fiber sensitive to strains characteristic of specific vibrational mode of object. Same principle also used with two-mode fiber.

  18. Strain Rate Effects on Ultimate Strain of Copper

    DTIC Science & Technology

    1979-05-01

    34Dogbone" Specimen Used for Quasi-Static 5 and Intermediate Rate Tests 2 Schematic of Split Hopkinso’v Bar Apparatus 7 3a PETN Filled Tube Specimen...48 Experiment 25 Calculated Stress Components in Copper Cylinder 52 Expanded by PETN 26 Fracture of Explosively Expanded Cylindrical 54 Tube A-la...Record of Shot No. 10 73 A7b Framing Camera Record of Shot No. 10 74 A-8 Strain Versus Time for Copper Tube Expanded 75 by PETN vi

  19. Haemophilus ducreyi Cutaneous Ulcer Strains Are Nearly Identical to Class I Genital Ulcer Strains

    PubMed Central

    Gangaiah, Dharanesh; Webb, Kristen M.; Humphreys, Tricia L.; Fortney, Kate R.; Toh, Evelyn; Tai, Albert; Katz, Samantha S.; Pillay, Allan; Chen, Cheng-Yen; Roberts, Sally A.; Munson, Robert S.; Spinola, Stanley M.

    2015-01-01

    Background Although cutaneous ulcers (CU) in the tropics is frequently attributed to Treponema pallidum subspecies pertenue, the causative agent of yaws, Haemophilus ducreyi has emerged as a major cause of CU in yaws-endemic regions of the South Pacific islands and Africa. H. ducreyi is generally susceptible to macrolides, but CU strains persist after mass drug administration of azithromycin for yaws or trachoma. H. ducreyi also causes genital ulcers (GU) and was thought to be exclusively transmitted by microabrasions that occur during sex. In human volunteers, the GU strain 35000HP does not infect intact skin; wounds are required to initiate infection. These data led to several questions: Are CU strains a new variant of H. ducreyi or did they evolve from GU strains? Do CU strains contain additional genes that could allow them to infect intact skin? Are CU strains susceptible to azithromycin? Methodology/Principal Findings To address these questions, we performed whole-genome sequencing and antibiotic susceptibility testing of 5 CU strains obtained from Samoa and Vanuatu and 9 archived class I and class II GU strains. Except for single nucleotide polymorphisms, the CU strains were genetically almost identical to the class I strain 35000HP and had no additional genetic content. Phylogenetic analysis showed that class I and class II strains formed two separate clusters and CU strains evolved from class I strains. Class I strains diverged from class II strains ~1.95 million years ago (mya) and CU strains diverged from the class I strain 35000HP ~0.18 mya. CU and GU strains evolved under similar selection pressures. Like 35000HP, the CU strains were highly susceptible to antibiotics, including azithromycin. Conclusions/Significance These data suggest that CU strains are derivatives of class I strains that were not recognized until recently. These findings require confirmation by analysis of CU strains from other regions. PMID:26147869

  20. Antigenic differentiation of classical swine fever vaccinal strain PAV-250 from other strains, including field strains from Mexico.

    PubMed

    Mendoza, Susana; Correa-Giron, Pablo; Aguilera, Edgar; Colmenares, Germán; Torres, Oscar; Cruz, Tonatiuh; Romero, Andres; Hernandez-Baumgarten, Eliseo; Ciprián, Abel

    2007-10-10

    Twenty-nine classical swine fever virus (CSFv) strains were grown in the PK15 or SK6 cell lines. Antigenic differentiation studies were performed using monoclonal antibodies (McAbs), produced at Lelystad (CDI-DLO), The Netherlands. The monoclonals which were classified numerically as monoclonals 2-13. Epitope map patterns that resulted from the reactivity with McAbs were found to be unrelated to the pathogenicity of the viruses studied. Antigenic determinants were recognized by McAbs 5 and 8, were not detected in some Mexican strains; however, sites for McAb 6 were absent in all strains. The PAV-250 vaccine strain was recognized by all MAbs, except by MAb 6. Furthermore, the Chinese C-S vaccine strain was found to be very similar to the GPE(-) vaccine. None of the studied Mexican vaccines or field strains was found to be similar to the PAV-250 vaccine strain.

  1. Effect of strain and strain rate on residual microstructures in copper

    SciTech Connect

    Stevens, M.F.; Follansbee, P.S.

    1986-01-01

    Several specimens of OFE Cu were deformed in compression to study the resulting microstructures at equivalent levels of threshold stress and strain. Equiaxed, diffuse dislocation cells are more persistent in Cu when tested at strain rates exceeding 10/sup 3/ sec/sup -1/. At quasi-static strain rates, dislocation collapse into more distinct, narrow microbands occurs at lower strain levels.

  2. Error quantification in strain mapping methods.

    PubMed

    Guerrero, Elisa; Galindo, Pedro; Yáñez, Andrés; Ben, Teresa; Molina, Sergio I

    2007-10-01

    In this article a method for determining errors of the strain values when applying strain mapping techniques has been devised. This methodology starts with the generation of a thickness/defocus series of simulated high-resolution transmission electron microscopy images of InAsxP1-x/InP heterostructures and the application of geometric phase. To obtain optimal defocusing conditions, a comparison of different defocus values is carried out by the calculation of the strain profile standard deviations among different specimen thicknesses. Finally, based on the analogy of real state strain to a step response, a characterization of strain mapping error near an interface is proposed.

  3. Tests of strain analysis by experimental deformation

    NASA Astrophysics Data System (ADS)

    Borradaile, G. J.; McArthur, J.

    1991-01-01

    The linearisation method and Robin's method of strain analysis of granular materials yield accurate strain estimates for a variety of materials deformed experimentally in pure shear. The breakdown of continuum behaviour at high pore fluid pressures causes the methods to overestimate the strain because they do not take added rigid-body rotation into account. Both methods tolerate some variation in initial shape ratio and some degree of initial preferred orientation at modest strains. Results of tests on polymict sandstone indicate that the lower than average ductility of competent clasts may be balanced against an unfavourable degree of preferred orientation to yield an improved strain estimate.

  4. Radio-Frequency Strain Monitor

    NASA Technical Reports Server (NTRS)

    Heyman, Joseph S.; Rogowski, Robert S.; Holben, Milford S., Jr.

    1988-01-01

    Radio-frequency (RF) strain monitor developed to measure lengths of objects. RF waveguide or cable bonded to structure monitored. Propagation of RF signal along waveguide results in phase shift proportional to length of path traveled. Impedance mismatches placed in RF cable at nodes of structure. Records mismatches and detects overall length of line and lengths of intervals between nodes. Used to detect changes in elements of large structure with single cable. Monitor has potential for many applications, including monitoring stability of such large structures as aircraft, bridges, and buildings in Earthquake zones.

  5. Demonstration test of burner liner strain measurements using resistance strain gages

    NASA Technical Reports Server (NTRS)

    Grant, H. P.; Anderson, W. L.

    1984-01-01

    A demonstration test of burner liner strain measurements using resistance strain gages as well as a feasibility test of an optical speckle technique for strain measurement are presented. The strain gage results are reported. Ten Kanthal A-1 wire strain gages were used for low cycle fatigue strain measurements to 950 K and .002 apparent strain on a JT12D burner can in a high pressure (10 atmospheres) burner test. The procedure for use of the strain gages involved extensive precalibration and postcalibration to correct for cooling rate dependence, drift, and temperature effects. Results were repeatable within + or - .0002 to .0006 strain, with best results during fast decels from 950 K. The results agreed with analytical prediction based on an axisymmetric burner model, and results indicated a non-uniform circumferential distribution of axial strain, suggesting temperature streaking.

  6. Strain engineering of graphene: a review

    NASA Astrophysics Data System (ADS)

    Si, Chen; Sun, Zhimei; Liu, Feng

    2016-02-01

    Graphene has intrigued the science community by many unique properties not found in conventional materials. In particular, it is the strongest two-dimensional material ever measured, being able to sustain reversible tensile elastic strain larger than 20%, which yields an interesting possibility to tune the properties of graphene by strain and thus opens a new field called ``straintronics''. In this article, the current progress in the strain engineering of graphene is reviewed. We first summarize the strain effects on the electronic structure and Raman spectra of graphene. We then highlight the electron-phonon coupling greatly enhanced by the biaxial strain and the strong pseudomagnetic field induced by the non-uniform strain with specific distribution. Finally, the potential application of strain-engineering in the self-assembly of foreign atoms on the graphene surface is also discussed. Given the short history of graphene straintronics research, the current progress has been notable, and many further advances in this field are expected.

  7. Multiplicative earthquake likelihood models incorporating strain rates

    NASA Astrophysics Data System (ADS)

    Rhoades, D. A.; Christophersen, A.; Gerstenberger, M. C.

    2017-01-01

    SUMMARYWe examine the potential for <span class="hlt">strain</span>-rate variables to improve long-term earthquake likelihood models. We derive a set of multiplicative hybrid earthquake likelihood models in which cell rates in a spatially uniform baseline model are scaled using combinations of covariates derived from earthquake catalogue data, fault data, and <span class="hlt">strain</span>-rates for the New Zealand region. Three components of the <span class="hlt">strain</span> rate estimated from GPS data over the period 1991-2011 are considered: the shear, rotational and dilatational <span class="hlt">strain</span> rates. The hybrid model parameters are optimised for earthquakes of M 5 and greater over the period 1987-2006 and tested on earthquakes from the period 2012-2015, which is independent of the <span class="hlt">strain</span> rate estimates. The shear <span class="hlt">strain</span> rate is overall the most informative individual covariate, as indicated by Molchan error diagrams as well as multiplicative modelling. Most models including <span class="hlt">strain</span> rates are significantly more informative than the best models excluding <span class="hlt">strain</span> rates in both the fitting and testing period. A hybrid that combines the shear and dilatational <span class="hlt">strain</span> rates with a smoothed seismicity covariate is the most informative model in the fitting period, and a simpler model without the dilatational <span class="hlt">strain</span> rate is the most informative in the testing period. These results have implications for probabilistic seismic hazard analysis and can be used to improve the background model component of medium-term and short-term earthquake forecasting models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25503536','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25503536"><span><span class="hlt">Strain</span> effects on oxygen migration in perovskites.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mayeshiba, Tam; Morgan, Dane</p> <p>2015-01-28</p> <p>Fast oxygen transport materials are necessary for a range of technologies, including efficient and cost-effective solid oxide fuel cells, gas separation membranes, oxygen sensors, chemical looping devices, and memristors. <span class="hlt">Strain</span> is often proposed as a method to enhance the performance of oxygen transport materials, but the magnitude of its effect and its underlying mechanisms are not well-understood, particularly in the widely-used perovskite-structured oxygen conductors. This work reports on an ab initio prediction of <span class="hlt">strain</span> effects on migration energetics for nine perovskite systems of the form LaBO3, where B = [Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Ga]. Biaxial <span class="hlt">strain</span>, as might be easily produced in epitaxial systems, is predicted to lead to approximately linear changes in migration energy. We find that tensile biaxial <span class="hlt">strain</span> reduces the oxygen vacancy migration barrier across the systems studied by an average of 66 meV per percent <span class="hlt">strain</span> for a single selected hop, with a low of 36 and a high of 89 meV decrease in migration barrier per percent <span class="hlt">strain</span> across all systems. The estimated range for the change in migration barrier within each system is ±25 meV per percent <span class="hlt">strain</span> when considering all hops. These results suggest that <span class="hlt">strain</span> can significantly impact transport in these materials, e.g., a 2% tensile <span class="hlt">strain</span> can increase the diffusion coefficient by about three orders of magnitude at 300 K (one order of magnitude at 500 °C or 773 K) for one of the most <span class="hlt">strain</span>-responsive materials calculated here (LaCrO3). We show that a simple elasticity model, which assumes only dilative or compressive <span class="hlt">strain</span> in a cubic environment and a fixed migration volume, can qualitatively but not quantitatively model the <span class="hlt">strain</span> dependence of the migration energy, suggesting that factors not captured by continuum elasticity play a significant role in the <span class="hlt">strain</span> response.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4222745','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4222745"><span>Distribution of Nontuberculous Mycobacteria <span class="hlt">strains</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p></p> <p>2013-01-01</p> <p>Aim Mycobacteria other than tuberculosis (MOTT) cause increasingly serious infections especially in immunosuppressive patients by direct transmission from the environment or after colonization. However, identification of these species is difficult because of the cost and difficulties in defining to species level. Identification and distribution of these species can help clinician in the choice of treatment. Materials and methods A total of 90 MOTT <span class="hlt">strains</span> obtained from four different centers were included in the study. These <span class="hlt">strains</span> were identified by sequence analysis of 16S rRNA and Hsp65 genetic regions. Results Accordingly, within the 90 MOTT <span class="hlt">strains</span>, 17 different species were identified. In order of frequency, these species were M. gordonea (n = 21), M. abscessus (n = 13), M. lentiflavum (n = 9), M. fortuitum (n = 8), M. intracellulare (n = 6), M. kumamotonense (n = 6), M. neoaurum (n = 5), M. chimaera (n = 5), M. alvei (n = 5), M. peregrinum (n = 3), M. canariasense (n = 3), M. flavescens (n = 1), M. mucogenicum (n = 1), M. chelona (n = 1), M. elephantis (n = 1), M. terrae (n = 1) and M. xenopi (n = 1). Most frequently identified MOTT species according to the geographical origin were as follows: M. abscessus was the most common species either in Istanbul or Malatya regions (n = 6, n = 6, consequently). While M. kumamotonense was the most frequent species isolated from Ankara region (n = 6), M. gordonea was the most common for Samsun region (n = 14). Conclusion Our study revealed that frequency of MOTT varies depending on the number of clinical samples and that frequency of these species were affected by the newly identified species as a result of the use of novel molecular methods. In conclusion, when establishing diagnosis and treatment methods, it is important to know that infections caused by unidentified MOTT species may vary according to the regions in Turkey. The results</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/11273014','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/11273014"><span>Antimicrobial activity of tannin components from Vaccinium vitis-idaea L.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ho, K Y; Tsai, C C; Huang, J S; Chen, C P; Lin, T C; Lin, C C</p> <p>2001-02-01</p> <p>Reactive oxygen species have been implicated as important pathological mediators in many clinical disorders, including periodontal disease. As a possible alternative for the treatment of periodontal disease, the antimicrobial activity of six tannins isolated from Vaccinium vitis-idaea L., with confirmed antioxidant activity, were assayed by the agar dilution method against selected periodontal pathogens, <span class="hlt">Actinobacillus</span> <span class="hlt">actinomycetemcomitans</span>, Porphyromonas gingivalis and Prevotella intermedia. The results showed that epicatechin-(4beta-->8)-epicatechin-(4beta-->8, 2beta-->O-->7)-catechin had strong antimicrobial activity against P. gingivalis and P. intermedia, but not A. <span class="hlt">actinomycetemcomitans</span>. The other tannins tested did not show antimicrobial activity. We conclude that tannins isolated from V. vitis-idaea L. with antimicrobial activity could potentially be used for the treatment of periodontal disease.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26902321','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26902321"><span>Comparison of <span class="hlt">Strain</span> Rosettes and Digital Image Correlation for Measuring Vertebral Body <span class="hlt">Strain</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Gustafson, Hannah; Siegmund, Gunter; Cripton, Peter</p> <p>2016-05-01</p> <p><span class="hlt">Strain</span> gages are commonly used to measure bone <span class="hlt">strain</span>, but only provide <span class="hlt">strain</span> at a single location. Digital image correlation (DIC) is an optical technique that provides the displacement, and therefore <span class="hlt">strain</span>, over an entire region of interest on the bone surface. This study compares vertebral body <span class="hlt">strains</span> measured using <span class="hlt">strain</span> gages and DIC. The anterior surfaces of 15 cadaveric porcine vertebrae were prepared with a <span class="hlt">strain</span> rosette and a speckled paint pattern for DIC. The vertebrae were loaded in compression with a materials testing machine, and two high-resolution cameras were used to image the anterior surface of the bones. The mean noise levels for the <span class="hlt">strain</span> rosette and DIC were 1 με and 24 με, respectively. Bland-Altman analysis was used to compare <span class="hlt">strain</span> from the DIC and rosette (excluding 44% of trials with some evidence of <span class="hlt">strain</span> rosette failure or debonding); the mean difference ± 2 standard deviations (SDs) was -108 με ± 702 με for the minimum (compressive) principal <span class="hlt">strain</span> and -53 με ± 332 με for the maximum (tensile) principal <span class="hlt">strain</span>. Although the DIC has higher noise, it avoids the relatively high risk we observed of <span class="hlt">strain</span> gage debonding. These results can be used to develop guidelines for selecting a method to measure <span class="hlt">strain</span> on bone.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AIPC.1723b0001D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AIPC.1723b0001D"><span>Modeling competition between yeast <span class="hlt">strains</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>de Gee, Maarten; van Mourik, Hilda; de Visser, Arjan; Molenaar, Jaap</p> <p>2016-04-01</p> <p>We investigate toxin interference competition between S. cerevisiae colonies grown on a solid medium. In vivo experiments show that the outcome of this competition depends strongly on nutrient availability and cell densities. Here we present a new model for S. cerevisiae colonies, calculating the local height and composition of the colonies. The model simulates yeast colonies that show a good fit to experimental data. Simulations of colonies that start out with a homogeneous mixture of toxin producing and toxin sensitive cells can display remarkable pattern formation, depending on the initial ratio of the <span class="hlt">strains</span>. Simulations in which the toxin producing and toxin sensitive species start at nearby positions clearly show that toxin production is advantageous.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20465860','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20465860"><span>Subtle bacterial endocarditis due to Kingella kingae in an infant: a case report.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Youssef, Dany; Henaine, Roland; Di Filippo, Sylvie</p> <p>2010-08-01</p> <p>A 9-month-old infant presented with fever, dyspnoea, and a murmur. Echocardiography showed a mitral vegetation with significant regurgitation. Mitral valve plasty was performed on day 6, and was polymerase chain reaction positive for Kingella kingae. The cardiac outcome was favourable. This case illustrates a subtle presentation of K. kingae mitral valve infective endocarditis in a normal-cardaic infant, treated with early surgery, and the agent belonged to the HACEK (Haemophilus spp <span class="hlt">Actinobacillus</span> <span class="hlt">actinomycetemcomitans</span>, Capnocytophaga spp, Cardiobacterium hominis, Eikenella corrodens, and Kingella kingae) group.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4963852','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4963852"><span>Impact of CDT Toxin on Human Diseases</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Faïs, Tiphanie; Delmas, Julien; Serres, Arnaud; Bonnet, Richard; Dalmasso, Guillaume</p> <p>2016-01-01</p> <p>Cytolethal distending toxin (CDT) is found in Gram-negative bacteria, especially in certain Proteobacteria such as the Pasteurellaceae family, including Haemophilus ducreyi and Aggregatibacter (<span class="hlt">Actinobacillus</span>) <span class="hlt">actinomycetemcomitans</span>, in the Enterobacteriaceae family and the Campylobacterales order, including the Campylobacter and Helicobacter species. In vitro and in vivo studies have clearly shown that this toxin has a strong effect on cellular physiology (inflammation, immune response modulation, tissue damage). Some works even suggest a potential involvement of CDT in cancers. In this review, we will discuss these different aspects. PMID:27429000</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4843387','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4843387"><span>Anti-microbial Activity of Tulsi {Ocimum Sanctum (Linn.)} Extract on a Periodontal Pathogen in Human Dental Plaque: An Invitro Study</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Devaraj, C.G.; Agarwal, Payal</p> <p>2016-01-01</p> <p>Introduction Tulsi is a popular healing herb in Ayurvedic medicine. It is widely used in the treatment of several systemic diseases because of its anti-microbial property. However, studies documenting the effect of Tulsi on oral disease causing organisms are rare. Hence, an attempt was made to determine the effect of Tulsi on a periodontal microorganism in human dental plaque. Aim To determine if Ocimum sanctum (Linn.) has an anti-microbial activity (Minimum Inhibitory Concentration and zone of inhibition) against <span class="hlt">Actinobacillus</span> <span class="hlt">actinomycetemcomitans</span> in human dental plaque and to compare the antimicrobial activity of Ocimum sanctum(Linn.) extract with 0.2% chlorhexidine as the positive control and dimethyl sulfoxide as the negative control. Materials and Methods A lab based invitro experimental study design was adopted. Ethanolic extract of Ocimum sanctum (Linn.) was prepared by the cold extraction method. The extract was diluted with an inert solvent, dimethyl sulfoxide, to obtain ten different concentrations (1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%) of extract. Plaque sample was collected from 05 subjects diagnosed with periodontal disease. Isolation of <span class="hlt">Actinobacillus</span> <span class="hlt">actinomycetemcomitans</span> from plaque samples was done using Tryptic Soy Serum Bacitracin Vancomycin agar (TSBV) medium. Identification of <span class="hlt">Actinobacillus</span> <span class="hlt">actinomycetemcomitans</span> was done based on cultural, microscopic, biochemical characterization and multiple drug resistance patterns. Anti-microbial activity of Ocimum sanctum (Linn.) extract was tested by agar well-diffusion method against 0.2% chlorhexidine as a positive control and dimethyl sulfoxide as a negative control. The zone of inhibition was measured in millimeters using Vernier callipers. Results At the 6% w/v concentration of Ocimum sanctum (Linn.) extract, a zone of inhibition of 22 mm was obtained. This was the widest zone of inhibition observed among all the 10 different concentrations tested. The zone of inhibition for positive control</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27429000','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27429000"><span>Impact of CDT Toxin on Human Diseases.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Faïs, Tiphanie; Delmas, Julien; Serres, Arnaud; Bonnet, Richard; Dalmasso, Guillaume</p> <p>2016-07-15</p> <p>Cytolethal distending toxin (CDT) is found in Gram-negative bacteria, especially in certain Proteobacteria such as the Pasteurellaceae family, including Haemophilus ducreyi and Aggregatibacter (<span class="hlt">Actinobacillus</span>) <span class="hlt">actinomycetemcomitans</span>, in the Enterobacteriaceae family and the Campylobacterales order, including the Campylobacter and Helicobacter species. In vitro and in vivo studies have clearly shown that this toxin has a strong effect on cellular physiology (inflammation, immune response modulation, tissue damage). Some works even suggest a potential involvement of CDT in cancers. In this review, we will discuss these different aspects.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24518385','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24518385"><span>The many shades of prion <span class="hlt">strain</span> adaptation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Baskakov, Ilia V</p> <p>2014-01-01</p> <p>In several recent studies transmissible prion disease was induced in animals by inoculation with recombinant prion protein amyloid fibrils produced in vitro. Serial transmission of amyloid fibrils gave rise to a new class of prion <span class="hlt">strains</span> of synthetic origin. Gradual transformation of disease phenotypes and PrP(Sc) properties was observed during serial transmission of synthetic prions, a process that resembled the phenomenon of prion <span class="hlt">strain</span> adaptation. The current article discusses the remarkable parallels between phenomena of prion <span class="hlt">strain</span> adaptation that accompanies cross-species transmission and the evolution of synthetic prions occurring within the same host. Two alternative mechanisms underlying prion <span class="hlt">strain</span> adaptation and synthetic <span class="hlt">strain</span> evolution are discussed. The current article highlights the complexity of the prion transmission barrier and <span class="hlt">strain</span> adaptation and proposes that the phenomenon of prion adaptation is more common than previously thought.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA571154','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA571154"><span>SNIT: SNP Identification for <span class="hlt">Strain</span> Typing</span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>2011-01-01</p> <p>Durkin S, Schneewind O, Nierman WC: Genome sequencing and analysis of Yersina pestis KIM D27, an avirulent <span class="hlt">strain</span> exempt from select agent regulation. PLoS...gener- ated from next-generation sequencing (NGS) data, we selected the recently published Yersinia pestis KIM D27 genome [12]. The Y. pestis D27 <span class="hlt">strain</span>...is a deriva- tive of Y. pestis KIM 10 <span class="hlt">strain</span> (accession no. NC_004088). The Y. pestis KIM D27 draft genome (accession no. ADDC00000000) was generated</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19840000339&hterms=vibrational+modes&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dvibrational%2Bmodes','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19840000339&hterms=vibrational+modes&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dvibrational%2Bmodes"><span>Deriving <span class="hlt">Strain</span> Modes From Vibrational Tests</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Young, J. W.; Joanides, J. C.</p> <p>1985-01-01</p> <p>Measurements and theoretical analysis complement each other. Experimental acceleration and <span class="hlt">strain</span> data used to calculate coefficients of low-frequency vibrational modes of object under test. An iterative comparison of experimental and calculated <span class="hlt">strains</span> give modal model of improved accuracy that predicts <span class="hlt">strains</span> under operating conditions. Method useful in fatigue life and reliability analyses of buildings, pumps, engines, vehicles, and other systems subject to vibrations and loud noises during operation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016MsT.........54S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016MsT.........54S"><span>Construction of an Optical Fiber <span class="hlt">Strain</span> Gauge</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sulaiman, Najwa</p> <p></p> <p>This project is focused on the construction of an optical fiber <span class="hlt">strain</span> gauge that is based on a <span class="hlt">strain</span> gauge described by Butter and Hocker. Our gauge is designed to generate an interference pattern from the signals carried on two bare single-mode fibers that are fastened to an aluminum cantilever. When the cantilever experiences flexural stress, the interference pattern should change. By observing this change, it is possible to determine the <span class="hlt">strain</span> experienced by the cantilever. I describe the design and construction of our optical fiber <span class="hlt">strain</span> gauge as well as the characterization of different parts of the apparatus.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_22 --> <div id="page_23" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="441"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/912475','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/912475"><span>Measurement of Sorption-Induced <span class="hlt">Strain</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Eric P. Robertson; Richard L. Christiansen</p> <p>2005-05-01</p> <p><span class="hlt">Strain</span> caused by the adsorption of gases was measured in samples of subbituminous coal from the Powder River basin of Wyoming, U.S.A. and high-volatile bituminous coal from east-central Utah, U.S.A. using an apparatus developed jointly at the Idaho National Laboratory (Idaho Falls, Idaho, U.S.A.) and Colorado School of Mines (Golden, Colorado, U.S.A.). The apparatus can be used to measure <span class="hlt">strain</span> on multiple small coal samples based on the optical detection of the longitudinal <span class="hlt">strain</span> instead of the more common usage of <span class="hlt">strain</span> gauges, which require larger samples and longer equilibration times. With this apparatus, we showed that the swelling and shrinkage processes were reversible and that accurate <span class="hlt">strain</span> data could be obtained in a shortened amount of time. A suite of <span class="hlt">strain</span> curves was generated for these coals using gases that included carbon dioxide, nitrogen, methane, helium, and various mixtures of these gases. A Langmuir-type equation was applied to satisfactorily model the <span class="hlt">strain</span> data obtained for pure gases. The sorption-induced <span class="hlt">strain</span> measured in the subbituminous coal was larger than the high-volatile bituminous coal for all gases tested over the range of pressures used in the experimentation, with the CO2-induced <span class="hlt">strain</span> for the subbituminous coal over twice as great at the bituminous coal.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20160000697','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20160000697"><span>Acceleration and Velocity Sensing from Measured <span class="hlt">Strain</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Pak, Chan-Gi; Truax, Roger</p> <p>2016-01-01</p> <p>A simple approach for computing acceleration and velocity of a structure from the <span class="hlt">strain</span> is proposed in this study. First, deflection and slope of the structure are computed from the <span class="hlt">strain</span> using a two-step theory. Frequencies of the structure are computed from the time histories of <span class="hlt">strain</span> using a parameter estimation technique together with an Autoregressive Moving Average model. From deflection, slope, and frequencies of the structure, acceleration and velocity of the structure can be obtained using the proposed approach. shape sensing, fiber optic <span class="hlt">strain</span> sensor, system equivalent reduction and expansion process.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/20976649','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/20976649"><span><span class="hlt">Strain</span> accommodation in inelastic deformation of glasses</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Murali, P.; Ramamurty, U.; Shenoy, Vijay B.</p> <p>2007-01-01</p> <p>Motivated by recent experiments on metallic glasses, we examine the micromechanisms of <span class="hlt">strain</span> accommodation including crystallization and void formation during inelastic deformation of glasses by employing molecular statics simulations. Our atomistic simulations with Lennard-Jones-like potentials suggests that a softer short range interaction between atoms favors crystallization. Compressive hydrostatic <span class="hlt">strain</span> in the presence of a shear <span class="hlt">strain</span> promotes crystallization whereas a tensile hydrostatic <span class="hlt">strain</span> is found to induce voids. The deformation subsequent to the onset of crystallization includes partial reamorphization and recrystallization, suggesting important atomistic mechanisms of plastic dissipation in glasses.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/366503','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/366503"><span>Investigation of a noncontact <span class="hlt">strain</span> measurement technique</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Damiano, B.; Talarico, L.J.</p> <p>1996-05-01</p> <p>The goal of this project was to investigate the feasibility of a new noncontact technique for directly and continuously monitoring peak <span class="hlt">strain</span> in rotating components. The technique utilizes the unique <span class="hlt">strain</span>-sensitive magnetic material properties of transformation Induced Plasticity (TRIP) steel alloys to measure <span class="hlt">strain</span>. These alloys are weakly magnetic when unstrained but become strongly ferromagnetic after mechanical deformation. A computer study was performed to determine whether the <span class="hlt">strain</span>-induced change in the magnetic material properties of a TRIP steel gage bonded to a rotating component would cause significant perturbations in the magnetic flux of a stationary electromagnet. The effects of <span class="hlt">strain</span> level, distance between the rotating component and the stationary electromagnet, and motion-induced eddy currents on flux perturbation magnitude were investigated. The calculated results indicate that a TRIP steel <span class="hlt">strain</span> sensing element can cause a significant perturbation in the magnetic flux of a stationary electromagnet. The magnetic flux perturbation magnitude was found to be inversely proportional to the distance between the magnet face and the TRIP steel element and directly proportional to the TRIP steel <span class="hlt">strain</span> level. The effect of motion-induced eddy currents on the magnetic flux was found to be negligible. It appears that the technique can be successfully applied to measure peak <span class="hlt">strain</span> in rotating components; however, the sensitivity of the magnetic flux perturbation magnitude to the distance between the <span class="hlt">strain</span> sensing element and the electromagnet may require making an independent proximity measurement.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/7453585','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/7453585"><span>[Antigenic relationships between Debaryomyces <span class="hlt">strains</span> (author's transl)].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Aksoycan, N</p> <p>1980-01-01</p> <p>The results of the agglutinations between homologous and heterologous Debaryomyces <span class="hlt">strains</span> and their agglutinating sera are shown in table I. According to these findings, D. hansenii and D. marama are antigenically different from other Debaryomyces <span class="hlt">strains</span> in this genus. In a previous study Aksoycan et al. have shown a common antigenic factor between D. hansenii, D. marama <span class="hlt">strains</span> and Salmonella 0:7 antigen. This factor was not present in other six <span class="hlt">strains</span> of Debaryomyces. These results also show that D. tamarii does not have any antigenic relationship with the other seven species of Debaryomyces in this genus.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012APS..MARV27001L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012APS..MARV27001L"><span>Making Novel Materials Using <span class="hlt">Strain</span> in Nanomembranes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lagally, Max G.</p> <p>2012-02-01</p> <p>The controlled introduction of <span class="hlt">strain</span> in materials offers an important degree of freedom for fundamental studies of materials as well as advanced device engineering. <span class="hlt">Strain</span> in a crystalline solid modifies the lattice constants and reduces the crystal symmetry. Because <span class="hlt">strain</span> energy is proportional to thickness, a free-standing crystalline thin sheet, which we call a nanomembrane (NM), can be <span class="hlt">strained</span> to a greater degree that a bulk material with the same surface area. I show the use of nanomembrane <span class="hlt">strain</span> engineering to make defect-free single crystals that cannot be grown any other way, and materials with <span class="hlt">strain</span> symmetries that they do not have naturally, in both cases alloys of Si and Ge. <span class="hlt">Strain</span> in NMs causes significant shifts in energy band edges, splitting of degenerate states, and changes in effective masses. These effects can be used to produce a desired band offset between different materials, to increase carrier mobility, and to change relative energy positions of valleys. In the latter respect, through the use of NMs it has recently become possible, using tensile <span class="hlt">strain</span>, to make Ge direct-bandgap and light emitting at room temperature. Periodic local stress can produce <span class="hlt">strain</span> superlattices and thus single-element heterojunctions. Work performed with the Roberto Paiella, Mark Eriksson, Feng Liu, and Irena Knezevic research groups.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/867015','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/867015"><span>Optical fiber sensor technique for <span class="hlt">strain</span> measurement</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Butler, Michael A.; Ginley, David S.</p> <p>1989-01-01</p> <p>Laser light from a common source is split and conveyed through two similar optical fibers and emitted at their respective ends to form an interference pattern, one of the optical fibers having a portion thereof subjected to a <span class="hlt">strain</span>. Changes in the <span class="hlt">strain</span> cause changes in the optical path length of the <span class="hlt">strain</span> fiber, and generate corresponding changes in the interference pattern. The interference pattern is received and transduced into signals representative of fringe shifts corresponding to changes in the <span class="hlt">strain</span> experienced by the <span class="hlt">strained</span> one of the optical fibers. These signals are then processed to evaluate <span class="hlt">strain</span> as a function of time, typical examples of the application of the apparatus including electrodeposition of a metallic film on a conductive surface provided on the outside of the optical fiber being <span class="hlt">strained</span>, so that <span class="hlt">strains</span> generated in the optical fiber during the course of the electrodeposition are measurable as a function of time. In one aspect of the invention, signals relating to the fringe shift are stored for subsequent processing and analysis, whereas in another aspect of the invention the signals are processed for real-time display of the <span class="hlt">strain</span> changes under study.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AcMSn..29..543X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AcMSn..29..543X"><span>Control of surface wettability via <span class="hlt">strain</span> engineering</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xiong, Wei; Liu, Jefferson Zhe; Zhang, Zhi-Liang; Zhen, Quan-Shui</p> <p>2013-08-01</p> <p>Reversible control of surface wettability has wide applications in lab-on-chip systems, tunable optical lenses, and microfluidic tools. Using a graphene sheet as a sample material and molecular dynamic simulations, we demonstrate that <span class="hlt">strain</span> engineering can serve as an effective way to control the surface wettability. The contact angles θ of water droplets on a graphene vary from 72.5° to 106° under biaxial <span class="hlt">strains</span> ranging from -10% to 10% that are applied on the graphene layer. For an intrinsic hydrophilic surface (at zero <span class="hlt">strain</span>), the variation of θ upon the applied <span class="hlt">strains</span> is more sensitive, i.e., from 0° to 74.8°. Overall the cosines of the contact angles exhibit a linear relation with respect to the <span class="hlt">strains</span>. In light of the inherent dependence of the contact angle on liquid-solid interfacial energy, we develop an analytic model to show the cos θ as a linear function of the adsorption energy E ads of a single water molecule over the substrate surface. This model agrees with our molecular dynamic results very well. Together with the linear dependence of E ads on biaxial <span class="hlt">strains</span>, we can thus understand the effect of <span class="hlt">strains</span> on the surface wettability. Thanks to the ease of reversibly applying mechanical <span class="hlt">strains</span> in micro/nano-electromechanical systems, we believe that <span class="hlt">strain</span> engineering can be a promising means to achieve the reversibly control of surface wettability.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19840004375','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19840004375"><span>Inflatable device for installing <span class="hlt">strain</span> gage bridges</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Cook, C. E.; Smith, G. E.; Monaghan, R. C. (Inventor)</p> <p>1983-01-01</p> <p>Methods and devices for installing in a tubular shaft multiple <span class="hlt">strain</span> gages are disclosed with focus on a method and a device for pneumatically forcing <span class="hlt">strain</span> gages into seated engagement with the internal surfaces of a tubular shaft in an installation of multiple <span class="hlt">strain</span> gages in a tubular shaft. The <span class="hlt">strain</span> gages or other electron devices are seated in a template-like component which is wrapped about a pneumatically expansible body. The component is inserted into a shaft and the body is pneumatically expanded after a suitable adhesive was applied to the surfaces.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002SPIE.4700..304A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002SPIE.4700..304A"><span>Microminiature temperature-compensated magnetoelastic <span class="hlt">strain</span> gauge</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Arms, Steven W.; Townsend, Christopher P.</p> <p>2002-07-01</p> <p>Our objective was to demonstrate a microminiature magnetoelastic <span class="hlt">strain</span> gauge that provides both <span class="hlt">strain</span> and temperature signals without additional sensors. Iron based magnetoelastic materials were embedded within superelastic nickel/titanium (NiTi) tubing. NiTi stress was transferred to the ferrite, causing a permeability change sensed by a tiny coil. The coil/bridge was excited (70 KHz AC), synchronously demodulated, and amplified to produce a voltage output proportional to coil/ferrite impedance. A DC voltage was also applied and separately conditioned to provide an output proportional to coil resistance; this signal was used to provide thermal compensation. Controlled <span class="hlt">strains</span> were applied and 6 Hz cyclic outputs recorded simultaneously from the magnetoelastic <span class="hlt">strain</span> gauge and conventional foil <span class="hlt">strain</span> gauges. The magnetoelastic <span class="hlt">strain</span> gauge tracked the foil gauge with minimal hysteresis and good linearity over 600 microstrain; repeatability was approximately 1.5 microstrain. The magnetoelastic <span class="hlt">strain</span> gauge's gauge factor was computed from delta inductance/original inductance under static <span class="hlt">strain</span> conditions. Temperatures of 25-140 deg C resulted in an uncompensated shift of 15 microstrain/deg C, and compensated shift of 1.0 microstrain/deg C. A sensitive micro-magnetoelastic <span class="hlt">strain</span> gauge was demonstrated using the same sensor to detect stress and temperature with no moving parts, high gauge factor, and good thermal stability.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014SPIE.9061E..31R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014SPIE.9061E..31R"><span>Distributed <span class="hlt">strain</span> monitoring for bridges: temperature effects</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Regier, Ryan; Hoult, Neil A.</p> <p>2014-03-01</p> <p>To better manage infrastructure assets as they reach the end of their service lives, quantitative data is required to better assess structural behavior and allow for more informed decision making. Distributed fiber optic <span class="hlt">strain</span> sensors are one sensing technology that could provide comprehensive data for use in structural assessments as these systems potentially allow for <span class="hlt">strain</span> to be measured with the same accuracy and gage lengths as conventional <span class="hlt">strain</span> sensors. However, as with many sensor technologies, temperature can play an important role in terms of both the structure's and sensor's performance. To investigate this issue a fiber optic distributed <span class="hlt">strain</span> sensor system was installed on a section of a two span reinforced concrete bridge on the TransCanada Highway. <span class="hlt">Strain</span> data was acquired several times a day as well as over the course of several months to explore the effects of changing temperature on the data. The results show that the <span class="hlt">strain</span> measurements are affected by the bridge behavior as a whole. The <span class="hlt">strain</span> measurements due to temperature are compared to <span class="hlt">strain</span> measurements that were taken during a load test on the bridge. The results show that even a small change in temperature can produce crack width and <span class="hlt">strain</span> changes similar to those due to a fully loaded transport truck. Future directions for research in this area are outlined.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4644690','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4644690"><span>Skeletal muscle tensile <span class="hlt">strain</span> dependence: hyperviscoelastic nonlinearity</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Wheatley, Benjamin B; Morrow, Duane A; Odegard, Gregory M; Kaufman, Kenton R; Donahue, Tammy L Haut</p> <p>2015-01-01</p> <p>Introduction Computational modeling of skeletal muscle requires characterization at the tissue level. While most skeletal muscle studies focus on hyperelasticity, the goal of this study was to examine and model the nonlinear behavior of both time-independent and time-dependent properties of skeletal muscle as a function of <span class="hlt">strain</span>. Materials and Methods Nine tibialis anterior muscles from New Zealand White rabbits were subject to five consecutive stress relaxation cycles of roughly 3% <span class="hlt">strain</span>. Individual relaxation steps were fit with a three-term linear Prony series. Prony series coefficients and relaxation ratio were assessed for <span class="hlt">strain</span> dependence using a general linear statistical model. A fully nonlinear constitutive model was employed to capture the <span class="hlt">strain</span> dependence of both the viscoelastic and instantaneous components. Results Instantaneous modulus (p<0.0005) and mid-range relaxation (p<0.0005) increased significantly with <span class="hlt">strain</span> level, while relaxation at longer time periods decreased with <span class="hlt">strain</span> (p<0.0005). Time constants and overall relaxation ratio did not change with <span class="hlt">strain</span> level (p>0.1). Additionally, the fully nonlinear hyperviscoelastic constitutive model provided an excellent fit to experimental data, while other models which included linear components failed to capture muscle function as accurately. Conclusions Material properties of skeletal muscle are <span class="hlt">strain</span>-dependent at the tissue level. This <span class="hlt">strain</span> dependence can be included in computational models of skeletal muscle performance with a fully nonlinear hyperviscoelastic model. PMID:26409235</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2951977','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2951977"><span>Prion <span class="hlt">strain</span> interactions are highly selective</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Nilsson, K. Peter R.; Joshi-Barr, Shivanjali; Winson, Olivia; Sigurdson, Christina J.</p> <p>2010-01-01</p> <p>Various misfolded and aggregated neuronal proteins commonly co-exist in neurodegenerative disease, but whether the proteins co-aggregate and alter the disease pathogenesis is unclear. Here we used mixtures of distinct prion <span class="hlt">strains</span>, which are believed to differ in conformation, to test the hypothesis that two different aggregates interact and change the disease in vivo. We tracked two prion <span class="hlt">strains</span> in mice histopathologically and biochemically, as well as by spectral analysis of plaque-bound polythiophene acetic acid (PTAA), a conformation-sensitive fluorescent amyloid ligand. We found that prion <span class="hlt">strains</span> interacted in a highly selective and <span class="hlt">strain</span>-specific manner, with either (i) no interaction, (ii) hybrid plaque formation, or (iii) blockage of one <span class="hlt">strain</span> by a second (interference). The hybrid plaques were maintained upon further passage in vivo and each <span class="hlt">strain</span> seemed to maintain its original conformational properties, suggesting that one <span class="hlt">strain</span> served only as a scaffold for aggregation of the second <span class="hlt">strain</span>. These findings not only further our understanding of prion <span class="hlt">strain</span> interactions, but also directly demonstrate interactions that may occur in other protein aggregate mixtures. PMID:20826672</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/9749560','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/9749560"><span><span class="hlt">Strain</span> amplification in the bone mechanosensory system.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cowin, S C; Weinbaum, S</p> <p>1998-09-01</p> <p>This article discusses the potential mechanisms by which the <span class="hlt">strain</span> induced at the membrane of an osteocyte may be amplified from the <span class="hlt">strain</span> experienced by the whole bone due to mechanical loading. These mechanisms address the question of how these mechanical load-induced small <span class="hlt">strains</span> of (typically) about 0.1% (but up to 0.5%) applied to a whole bone are amplified to <span class="hlt">strains</span> of 1% or larger at the membrane of the osteocyte buried in its lacuna in the bone matrix. The answer to this question is an important link in the mechanosensory system in bone and in relating in vitro cell studies to in vivo cellular response.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/10878089','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/10878089"><span>Surveillance of rotavirus <span class="hlt">strains</span> in the United States: identification of unusual <span class="hlt">strains</span>. The National Rotavirus <span class="hlt">Strain</span> Surveillance System collaborating laboratories.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Griffin, D D; Kirkwood, C D; Parashar, U D; Woods, P A; Bresee, J S; Glass, R I; Gentsch, J R</p> <p>2000-07-01</p> <p>Rotavirus <span class="hlt">strains</span> from 964 fecal specimens collected from children at 11 U.S. hospital laboratories from November 1997 to March 1998 and from samples collected at 12 laboratories from November 1998 to March 1999 were typed for G and P proteins. Serotype G1 was the predominant serotype in 1997-1998 (88%), followed by G2 (6.2%), G9 (3.3%), and G3 (1.5%). This pattern was similar to that seen in 1998-1999: G1 (79%), G2 (15%), G9 (3.0%), G4 (1.6%), and G3 (0.3%). Novel P[9] <span class="hlt">strains</span> were identified in both seasons, and analysis of a 364-nucleotide fragment from gene segment 4 of one of the <span class="hlt">strains</span> demonstrated 97.3% nucleotide identity with the prototype P3[9],G3 <span class="hlt">strain</span>, AU1, isolated in Japan. This is the first report of a human AU1-like <span class="hlt">strain</span> in the United States. These results reinforce our initial findings that serotype G9 persists in the United States but has not become a predominant <span class="hlt">strain</span> and that the common serotypes G1 to G4 account for almost 90% of <span class="hlt">strains</span> in circulation. Other uncommon <span class="hlt">strains</span> exist in the United States but may have been overlooked before because of their low prevalence and the use of inadequate diagnostic tools.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950047316&hterms=seismic&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dseismic','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950047316&hterms=seismic&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dseismic"><span>A comparison of eastern North American seismic <span class="hlt">strain</span>-rates to glacial rebound <span class="hlt">strain</span>-rates</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>James, Thomas S.; Bent, Allison L.</p> <p>1994-01-01</p> <p>Glacial rebound <span class="hlt">strain</span>-rates computed using a simple Laurentide glacial loading model are of the order of 10(exp -9) per year within the region of glaciation and extending several hundred kilometers beyond. The horizontal <span class="hlt">strain</span>-rates receive approximately equal contributions from horizontal and vertical velocities, a consequence of the spherical geometry adopted for the Earth model. In the eastern United States and southeastern Canada the computed <span class="hlt">strain</span>-rates are 1-3 orders of magnitude greater than an estimate of the average seismic <span class="hlt">strain</span>-rate (Anderson, 1986) and approximately 1 order of magnitude greater than predicted erosional <span class="hlt">strain</span>-rates. The predicted glacial rebound <span class="hlt">strain</span>-rates are not, in general, oriented in such a way as to augment the observed state of deviatoric stress, possibly explaining why the seismic <span class="hlt">strain</span>-rates are much smaller than the glacial rebound <span class="hlt">strain</span>-rates. An exception to this may be seismically active regions in the St. Lawrence valley.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016IJN....1560005S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016IJN....1560005S"><span>Simulation and Analysis of <span class="hlt">Strain</span> Sensitivity of CNT-Based <span class="hlt">Strain</span> Sensors</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sapra, Gaurav; Vig, Renu; Sharma, Manu</p> <p>2016-10-01</p> <p>Carbon nanotubes (CNT) is turning out to be a replacement to all the existing traditional sensors due to their high gauge factor, multidirectional sensing capability, high flexibility, low mass density, high dynamic range and high sensitivity to <span class="hlt">strains</span> at nano and macro- scales. The <span class="hlt">strain</span> sensitivity of CNT-based <span class="hlt">strain</span> sensors depends on number of parameters; quality and quantity of CNT used, type of polymer used, deposition and dispersion technique adopted and also on environmental conditions. Due to all these parameters, the piezoresistive behavior of CNT is diversified and it needs to be explored. This paper theoretically analyses the <span class="hlt">strain</span> sensitivity of CNT-based <span class="hlt">strain</span> sensors. The <span class="hlt">strain</span> sensitivity response of CNT <span class="hlt">strain</span> sensor is a result of change in total resistance of CNT network with respect to applied <span class="hlt">strain</span>. The total resistance of CNT network consists of intrinsic resistance and inter-tube resistance. It has been found that the change in intrinsic resistance under <span class="hlt">strain</span> is due to the variation of bandgap of individual, which depends on the chirality of the tube and it varies exponentially with <span class="hlt">strain</span>. The inter-tube resistance of CNT network changes nonlinearly due to change in distance between neighboring CNTs with respect to applied <span class="hlt">strain</span>. As the distance d between CNTs increases due to applied <span class="hlt">strain</span>, tunneling resistance Rtunnel increases nonlinearly in exponential manner. When the concentration of CNTs in composite is close to percolation threshold, then the change of inter-tube resistances is more dominant than intrinsic resistance. At percolation threshold, the total resistance of CNT networks changes nonlinearly and this effect of nonlinearity is due to tunneling effect. The <span class="hlt">strain</span> sensitivity of CNT-based <span class="hlt">strain</span> sensors also varies nonlinearly with the change in temperature. For the change of temperature from -20∘C to 50∘C, there is more than 100% change in <span class="hlt">strain</span> sensitivity of CNT/polymer composite <span class="hlt">strain</span> sensor. This change is</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/495681','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/495681"><span>Bicrystals with <span class="hlt">strain</span> gradient effects</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Shu, J.Y.</p> <p>1997-01-09</p> <p>Boundary between two perfectly bonded single crystals plays an important role in determining the deformation of the bicrystals. This work addresses the role of the grain boundary by considering the elevated hardening of a slip system due to a slip gradient. The slip gradients are associated with geometrically necessary dislocations and their effects become pronounced when a representative length scale of the deformation field is comparable to the dominant microstructural length scale of a material. A new rate-dependent crystal plasticity theory is presented and has been implemented within the finite element method framework. A planar bicrystal under uniform in-plane loading is studied using the new crystal theory. The <span class="hlt">strain</span> is found to be continuous but nonuniform within a boundary layer around the interface. The lattice rotation is also nonuniform within the boundary layer. The width of the layer is determined by the misorientation of the grains, the hardening of slip systems, and most importantly by the characteristic material length scales. The overall yield strength of the bicrystal is also obtained. A significant grain-size dependence of the yield strength, the Hall- Petch effect is predicted.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=punishment+AND+child&pg=7&id=EJ808655','ERIC'); return false;" href="http://eric.ed.gov/?q=punishment+AND+child&pg=7&id=EJ808655"><span>General <span class="hlt">Strain</span> Theory and Delinquency: Focusing on the Influences of Key <span class="hlt">Strain</span> Characteristics on Delinquency</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Moon, Byongook; Blurton, David; McCluskey, John D.</p> <p>2008-01-01</p> <p>The study examines the effects of recent, older, and chronic <span class="hlt">strains</span> and of perceived injustice of <span class="hlt">strain</span> on delinquency, sampling 777 Korean youth. Seven key <span class="hlt">strains</span> most likely leading to delinquency, some of which were often overlooked in previous research, were included, and these are family conflict, parental punishment, teachers' punishment,…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AIPC.1426..167J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AIPC.1426..167J"><span>High <span class="hlt">strain</span> rate behavior of polyurea compositions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Joshi, Vasant S.; Milby, Christopher</p> <p>2012-03-01</p> <p>High-<span class="hlt">strain</span>-rate response of three polyurea compositions with varying molecular weights has been investigated using a Split Hopkinson Pressure Bar arrangement equipped with aluminum bars. Three polyurea compositions were synthesized from polyamines (Versalink, Air Products) with a multi-functional isocyanate (Isonate 143L, Dow Chemical). Amines with molecular weights of 1000, 650, and a blend of 250/1000 have been used in the current investigation. These materials have been tested to <span class="hlt">strain</span> rates of over 6000/s. High <span class="hlt">strain</span> rate results from these tests have shown varying trends as a function of increasing <span class="hlt">strain</span>. While higher molecular weight composition show lower yield, they do not show dominant hardening behavior at lower <span class="hlt">strain</span>. On the other hand, the blend of 250/1000 show higher load bearing capability but lower <span class="hlt">strain</span> hardening effects than the 600 and 1000 molecular weight amine based materials. Results indicate that the initial increase in the modulus of the blend of 250/1000 may lead to the loss of <span class="hlt">strain</span> hardening characteristics as the material is compressed to 50% <span class="hlt">strain</span>, compared to 1000 molecular weight amine based material.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_23 --> <div id="page_24" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="461"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20090011203','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20090011203"><span>Nanocomposite <span class="hlt">Strain</span> Gauges Having Small TCRs</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Gregory, Otto; Chen, Ximing</p> <p>2009-01-01</p> <p>Ceramic <span class="hlt">strain</span> gauges in which the <span class="hlt">strain</span>-sensitive electrically conductive strips made from nanocomposites of noble metal and indium tin oxide (ITO) are being developed for use in gas turbine engines and other power-generation systems in which gas temperatures can exceed 1,500 F (about 816 C). In general, <span class="hlt">strain</span> gauges exhibit spurious thermally induced components of response denoted apparent <span class="hlt">strain</span>. When temperature varies, a <span class="hlt">strain</span>-gauge material that has a nonzero temperature coefficient of resistance (TCR) exhibits an undesired change in electrical resistance that can be mistaken for the change in resistance caused by a change in <span class="hlt">strain</span>. It would be desirable to formulate straingauge materials having TCRs as small as possible so as to minimize apparent <span class="hlt">strain</span>. Most metals exhibit positive TCRs, while most semiconductors, including ITO, exhibit negative TCRs. The present development is based on the idea of using the negative TCR of ITO to counter the positive TCRs of noble metals and of obtaining the benefit of the ability of both ITO and noble metals to endure high temperatures. The noble metal used in this development thus far has been platinum. Combinatorial libraries of many ceramic <span class="hlt">strain</span> gauges containing nanocomposites of various proportions of ITO and platinum were fabricated by reactive co-sputtering from ITO and platinum targets onto alumina- and zirconia-based substrates mounted at various positions between the targets.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19810000068&hterms=phase+locked+loop&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dphase%2Blocked%2Bloop','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19810000068&hterms=phase+locked+loop&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dphase%2Blocked%2Bloop"><span>Pulsed Phase-Locked-Loop <span class="hlt">Strain</span> Monitor</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Heyman, J. S.; Stone, F. D.</p> <p>1982-01-01</p> <p>P2sup.L2sup. <span class="hlt">strain</span> monitor measures <span class="hlt">strain</span> by monitoring change in phase of acoustic signal that passes through stressed sample. Phase sample causes shift in frequency of VCO. As with other monitors of this type, instrument is only accurate in elastic range of material. Monitor is expected to have broad application in materials testing, structural design, fabrication and assembly.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1993STIN...9426568W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1993STIN...9426568W"><span>Attachment techniques for high temperature <span class="hlt">strain</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wnuk, Steve P., Jr.</p> <p>1993-01-01</p> <p>Attachment methods for making resistive <span class="hlt">strain</span> measurements to 2500 F were studied. A survey of available <span class="hlt">strain</span> gages and attachment techniques was made, and the results are compiled for metal and carbon composite test materials. A theoretical analysis of <span class="hlt">strain</span> transfer into a bonded <span class="hlt">strain</span> gage was made, and the important physical parameters of the <span class="hlt">strain</span> transfer medium, the ceramic matrix, were identified. A pull tester to measure pull-out tests on commonly used <span class="hlt">strain</span> gage cements indicated that all cements tested displayed adequate strength for good <span class="hlt">strain</span> transfer. Rokide flame sprayed coatings produced significantly stronger bonds than ceramic cements. An in-depth study of the flame spray process produced simplified installation procedures which also resulted in greater reliability and durability. Application procedures incorporating improvements made during this program are appended to the report. <span class="hlt">Strain</span> gages installed on carbon composites, Rene' 41, 316 stainless steel, and TZM using attachment techniques developed during this program were successfully tested to 2500 F. Photographs of installation techniques, test procedures, and graphs of the test data are included in this report.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/8719177','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/8719177"><span>A natural vaccine candidate <span class="hlt">strain</span> against cholera.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Liu, Y Q; Qi, G M; Wang, S X; Yu, Y M; Duan, G C; Zhang, L J; Gao, S Y</p> <p>1995-12-01</p> <p>E1 Tor Vibrio cholerae (EVC) <span class="hlt">strains</span> may be classified into two kinds-epidemigenic (EEVC) <span class="hlt">strains</span> and non-epidemigenic (NEEVC) <span class="hlt">strains</span>-based on a phage-biotyping system. A large number of EEVC <span class="hlt">strains</span> have been screened for toxigenic and putative colonization attributes. One such naturally occurring <span class="hlt">strains</span> (designated IEM101) has been found which is devoid of genes encoding cholera toxin (CT), accessory cholera enterotoxin (ACE), zonula occludens toxin (ZOT), but possesses RS1 sequences and toxin-coregulated pilus A gene (icpA) although icpA is poorly expressed. It expresses type B pili but does not possess type C pili. It is an E1 Tor Ogawa <span class="hlt">strain</span> and does not cause fluid accumulation in rabbit ilcal loop tests. Active immunization of rabbits with <span class="hlt">strain</span> IEM101 elicited good protection against challenge with virulent <span class="hlt">strains</span> of V. cholerae O1. Oral administration caused no side effects in 15 human volunteers, colonized the gut for four to ten days and elicited good immune responses.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=nursing+AND+care&id=EJ1001107','ERIC'); return false;" href="http://eric.ed.gov/?q=nursing+AND+care&id=EJ1001107"><span>Medically Complex Home Care and Caregiver <span class="hlt">Strain</span></span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Moorman, Sara M.; Macdonald, Cameron</p> <p>2013-01-01</p> <p>Purpose of the study: To examine (a) whether the content of caregiving tasks (i.e., nursing vs. personal care) contributes to variation in caregivers' <span class="hlt">strain</span> and (b) whether the level of complexity of nursing tasks contributes to variation in <span class="hlt">strain</span> among caregivers providing help with such tasks. Design and methods: The data came from the Cash…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19700000207','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19700000207"><span>Inorganic bonding of semiconductor <span class="hlt">strain</span> gages</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Woodruff, N. L.</p> <p>1970-01-01</p> <p>Inorganic bonding materials minimize outgassing and improve electrical and mechanical properties of semiconductor <span class="hlt">strain</span>-gage transducers in high-vacuum and high-temperature operations. The two basic methods described are ceramic-glass-bonding and metallic bond formation between the <span class="hlt">strain</span> gage and the substrate.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/82645','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/82645"><span>On certain aspects of <span class="hlt">strain</span> rate sensitivity of sheet metals</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Shi, M.F.; Meuleman, D.J.</p> <p>1995-06-01</p> <p>The formability of a material depends upon the <span class="hlt">strain</span> hardening and <span class="hlt">strain</span> rate hardening of the material. In this study, constitutive parameters using the power law constitutive equation are determined for six different strength steels and two aluminum alloys over different <span class="hlt">strain</span> ranges, including approximations of the postuniform elongation range. Constitutive parameters are found to be different at different <span class="hlt">strain</span> ranges. The <span class="hlt">strain</span> hardening of steels increases with <span class="hlt">strain</span> at low <span class="hlt">strain</span> levels (less than 5%) and decreases at high <span class="hlt">strain</span> levels (greater than 10%). <span class="hlt">Strain</span> rate hardening decreases with <span class="hlt">strain</span> for all steels and aluminum alloys. Uniform elongation depends only on <span class="hlt">strain</span> hardening, and postuniform elongation depends only on <span class="hlt">strain</span> rate hardening. However, the total elongation depends on both <span class="hlt">strain</span> hardening and <span class="hlt">strain</span> rate hardening.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040090018&hterms=Mechanosensitive+channels&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DMechanosensitive%2Bchannels','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040090018&hterms=Mechanosensitive+channels&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DMechanosensitive%2Bchannels"><span>Transduction of mechanical <span class="hlt">strain</span> in bone</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Duncan, R. L.</p> <p>1995-01-01</p> <p>One physiologic consequence of extended periods of weightlessness is the rapid loss of bone mass associated with skeletal unloading. Conversely, mechanical loading has been shown to increase bone formation and stimulate osteoblastic function. The mechanisms underlying mechanotransduction, or how the osteoblast senses and converts biophysical stimuli into cellular responses has yet to be determined. For non-innervated mechanosensitive cells like the osteoblast, mechanotransduction can be divided into four distinct phases: 1) mechanocoupling, or the characteristics of the mechanical force applied to the osteoblast, 2) biochemical coupling, or the mechanism through which mechanical <span class="hlt">strain</span> is transduced into a cellular biochemical signal, 3) transmission of signal from sensor to effector cell and 4) the effector cell response. This review examines the characteristics of the mechanical <span class="hlt">strain</span> encountered by osteoblasts, possible biochemical coupling mechanisms, and how the osteoblast responds to mechanical <span class="hlt">strain</span>. Differences in osteoblastic responses to mechanical <span class="hlt">strain</span> are discussed in relation to the types of <span class="hlt">strain</span> encountered and the possible transduction pathways involved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26649476','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26649476"><span>Mechanical <span class="hlt">strain</span> effects on black phosphorus nanoresonators.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wang, Cui-Xia; Zhang, Chao; Jiang, Jin-Wu; Park, Harold S; Rabczuk, Timon</p> <p>2016-01-14</p> <p>We perform classical molecular dynamics simulations to investigate the effects of mechanical <span class="hlt">strain</span> on single-layer black phosphorus nanoresonators at different temperatures. We find that the resonant frequency is highly anisotropic in black phosphorus due to its intrinsic puckered configuration, and that the quality factor in the armchair direction is higher than in the zigzag direction at room temperature. The quality factors are also found to be intrinsically larger than those in graphene and MoS2 nanoresonators. The quality factors can be increased by more than a factor of two by applying tensile <span class="hlt">strain</span>, with uniaxial <span class="hlt">strain</span> in the armchair direction being the most effective. However, there is an upper bound for the quality factor increase due to nonlinear effects at large <span class="hlt">strains</span>, after which the quality factor decreases. The tension induced nonlinear effect is stronger along the zigzag direction, resulting in a smaller maximum <span class="hlt">strain</span> for quality factor enhancement.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24799688','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24799688"><span>Extraordinary <span class="hlt">strain</span> hardening by gradient structure.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wu, XiaoLei; Jiang, Ping; Chen, Liu; Yuan, Fuping; Zhu, Yuntian T</p> <p>2014-05-20</p> <p>Gradient structures have evolved over millions of years through natural selection and optimization in many biological systems such as bones and plant stems, where the structures change gradually from the surface to interior. The advantage of gradient structures is their maximization of physical and mechanical performance while minimizing material cost. Here we report that the gradient structure in engineering materials such as metals renders a unique extra <span class="hlt">strain</span> hardening, which leads to high ductility. The grain-size gradient under uniaxial tension induces a macroscopic <span class="hlt">strain</span> gradient and converts the applied uniaxial stress to multiaxial stresses due to the evolution of incompatible deformation along the gradient depth. Thereby the accumulation and interaction of dislocations are promoted, resulting in an extra <span class="hlt">strain</span> hardening and an obvious <span class="hlt">strain</span> hardening rate up-turn. Such extraordinary <span class="hlt">strain</span> hardening, which is inherent to gradient structures and does not exist in homogeneous materials, provides a hitherto unknown strategy to develop strong and ductile materials by architecting heterogeneous nanostructures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6565562','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6565562"><span><span class="hlt">Strain</span> rate effects in stress corrosion cracking</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Parkins, R.N. . Dept. of Metallurgy and Engineering Materials)</p> <p>1990-03-01</p> <p>Slow <span class="hlt">strain</span> rate testing (SSRT) was initially developed as a rapid, ad hoc laboratory method for assessing the propensity for metals an environments to promote stress corrosion cracking. It is now clear, however, that there are good theoretical reasons why <span class="hlt">strain</span> rate, as opposed to stress per se, will often be the controlling parameter in determining whether or not cracks are nucleated and, if so, are propagated. The synergistic effects of the time dependence of corrosion-related reactions and microplastic <span class="hlt">strain</span> provide the basis for mechanistic understanding of stress corrosion cracking in high-pressure pipelines and other structures. However, while this may be readily comprehended in the context of laboratory slow <span class="hlt">strain</span> tests, its extension to service situations may be less apparent. Laboratory work involving realistic stressing conditions, including low-frequency cyclic loading, shows that <span class="hlt">strain</span> or creep rates give good correlation with thresholds for cracking and with crack growth kinetics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1810513Q','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1810513Q"><span>Micro-scale <span class="hlt">strain</span> mapping technique: a tool to quantify <span class="hlt">strain</span> partitioning during creep deformation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Quintanilla-Terminel, Alejandra; Zimmerman, Mark; Evans, Brian; Kohlstedt, David</p> <p>2016-04-01</p> <p>Several deformation mechanisms interact to accommodate plastic deformation. Quantifying the contribution of each to the total <span class="hlt">strain</span> is necessary for establishing a better link between observed microstructures and mechanical data, as well as to allow more confident extrapolation from laboratory to natural conditions. In this contribution, we present the experimental and computational technique involved in micro-scale <span class="hlt">strain</span> mapping (MSSM). The MSSM technique relies on analyzing the relative displacement of initially regularly spaced markers after deformation. We present several microfabrication techniques that permit us to pattern various rocks with micrometric and nanometric metal markers, as well as the challenges faced in working at high temperatures and pressures. A Hough transform algorithm was used to detect the markers and automate as much as possible the <span class="hlt">strain</span> analysis. The von Mises <span class="hlt">strain</span> is calculated for a set of n-points and their relative displacements, which allow us to map the <span class="hlt">strain</span> at different length scales. We applied the MSSM technique to study <span class="hlt">strain</span> partitioning during deformation creep of Carrara marble and San Carlos olivine at a confining pressure, Pc, of 300 MPa and homologous temperatures of 0.3 to 0.6. We measured the local <span class="hlt">strain</span> and <span class="hlt">strain</span> heterogeneity produced during creep deformation of split cylinders of Carrara marble under conventional triaxial loading to inelastic <span class="hlt">strains</span> of 11 to 36% at a <span class="hlt">strain</span> rate of 3x10-5s-1, Pc = 300 MPa and 400o < T <700oC. We conclude that the evolution of deformation structures in marble takes place over a substantial interval in <span class="hlt">strain</span> and that the duration of this interval depends on <span class="hlt">strain</span> rate, temperature, and pressure. Our first results on <span class="hlt">strain</span> mapping of olivine deformed at T = 1150oC and Pc = 300 MPa demonstrate promise for characterizing intragranular <span class="hlt">strain</span> and better defining the contribution of grain boundary sliding to the total <span class="hlt">strain</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2551748','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2551748"><span>Amerindian Helicobacter pylori <span class="hlt">Strains</span> Go Extinct, as European <span class="hlt">Strains</span> Expand Their Host Range</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Domínguez-Bello, Maria G.; Pérez, Maria E.; Bortolini, Maria C.; Salzano, Francisco M.; Pericchi, Luis R.; Zambrano-Guzmán, Orlisbeth; Linz, Bodo</p> <p>2008-01-01</p> <p>We studied the diversity of bacteria and host in the H. pylori-human model. The human indigenous bacterium H. pylori diverged along with humans, into African, European, Asian and Amerindian groups. Of these, Amerindians have the least genetic diversity. Since niche diversity widens the sets of resources for colonizing species, we predicted that the Amerindian H. pylori <span class="hlt">strains</span> would be the least diverse. We analyzed the multilocus sequence (7 housekeeping genes) of 131 <span class="hlt">strains</span>: 19 cultured from Africans, 36 from Spanish, 11 from Koreans, 43 from Amerindians and 22 from South American Mestizos. We found that all <span class="hlt">strains</span> that had been cultured from Africans were African <span class="hlt">strains</span> (hpAfrica1), all from Spanish were European (hpEurope) and all from Koreans were hspEAsia but that Amerindians and Mestizos carried mixed <span class="hlt">strains</span>: hspAmerind and hpEurope <span class="hlt">strains</span> had been cultured from Amerindians and hpEurope and hpAfrica1 were cultured from Mestizos. The least genetically diverse H. pylori <span class="hlt">strains</span> were hspAmerind. <span class="hlt">Strains</span> hpEurope were the most diverse and showed remarkable multilocus sequence mosaicism (indicating recombination). The lower genetic structure in hpEurope <span class="hlt">strains</span> is consistent with colonization of a diversity of hosts. If diversity is important for the success of H. pylori, then the low diversity of Amerindian <span class="hlt">strains</span> might be linked to their apparent tendency to disappear. This suggests that Amerindian <span class="hlt">strains</span> may lack the needed diversity to survive the diversity brought by non-Amerindian hosts. PMID:18830403</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28049090','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28049090"><span>New regime in the mechanical behavior of skin: <span class="hlt">strain</span>-softening occurring before <span class="hlt">strain</span>-hardening.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nicolle, S; Decorps, J; Fromy, B; Palierne, J-F</p> <p>2017-05-01</p> <p>We report linear and non-linear shear tests on rat skin, evidencing a <span class="hlt">strain</span>-softening regime, from 1% to 50% <span class="hlt">strain</span>, followed by a strong <span class="hlt">strain</span>-hardening regime, leading to a 'deck chair-shaped' stress-<span class="hlt">strain</span> curve. The <span class="hlt">strain</span>-softening regime was never reported as such in the literature, possibly mistaken for the linear regime in experiments starting above 1% deformation. The time-dependent response is akin to that of a gel, with a power-law frequency-dependent dynamic shear modulus ranging from ~5.6kPa to ~10kPa between 0.1Hz and 10Hz. We present an analytical non-linear viscoelastic model that accounts for both time-dependent and <span class="hlt">strain</span>-dependent features of the skin. This eight-parameter model extends the one we proposed for parenchymatous organs by including <span class="hlt">strain</span>-softening.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23030102','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23030102"><span>Anisotropic <span class="hlt">strain</span> enhanced hydrogen solubility in bcc metals: the independence on the sign of <span class="hlt">strain</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhou, Hong-Bo; Jin, Shuo; Zhang, Ying; Lu, Guang-Hong; Liu, Feng</p> <p>2012-09-28</p> <p>When an impurity is doped in a solid, it inevitably induces a local stress, tending to expand or contract the lattice. Consequently, <span class="hlt">strain</span> can be applied to change the solubility of impurity in a solid. Generally, the solubility responds to <span class="hlt">strain</span> "monotonically," increasing (decreasing) with the tensile (compressive) <span class="hlt">strain</span> if the impurity induces a compressive stress or vice versa. Using first-principles calculations, however, we discovered that the H solubility can be enhanced by anisotropic <span class="hlt">strain</span> in some bcc metals, almost independent of the sign of <span class="hlt">strain</span>. This anomalous behavior is found to be caused by a continuous change of H location induced by anisotropic <span class="hlt">strain</span>. Our finding suggests a cascading effect of H bubble formation in bcc metals: the H solution leads to H bubble formation that induces anisotropic <span class="hlt">strain</span> that in turn enhances H solubility to further facilitate bubble growth.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008IJMPB..22.1255K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008IJMPB..22.1255K"><span>Dynamic Tensile Properties of Iron and Steels for a Wide Range of <span class="hlt">Strain</span> Rates and <span class="hlt">Strain</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kojima, Nobusato; Hayashi, Hiroyuki; Yamamoto, Terumi; Mimura, Koji; Tanimura, Shinji</p> <p></p> <p>The tensile stress-<span class="hlt">strain</span> curves of iron and a variety of steels, covering a wide range of strength level, over a wide <span class="hlt">strain</span> rate range on the order of 10-3 ~ 103 s-1, were obtained systematically by using the Sensing Block Type High Speed Material Testing System (SBTS, Saginomiya). Through intensive analysis of these results, the <span class="hlt">strain</span> rate sensitivity of the flow stress for the large <span class="hlt">strain</span> region, including the viscous term at high <span class="hlt">strain</span> rates, the true fracture strength and the true fracture <span class="hlt">strain</span> were cleared for the material group of the ferrous metals. These systematical data may be useful to develop a practical constitutive model for computer codes, including a fracture criterion for simulations of the dynamic behavior in crash worthiness studies and of work-pieces subjected to dynamic plastic working for a wide <span class="hlt">strain</span> rate range.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007IJMSp.259..140K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007IJMSp.259..140K"><span>Specific identification of Bacillus anthracis <span class="hlt">strains</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Krishnamurthy, Thaiya; Deshpande, Samir; Hewel, Johannes; Liu, Hongbin; Wick, Charles H.; Yates, John R., III</p> <p>2007-01-01</p> <p>Accurate identification of human pathogens is the initial vital step in treating the civilian terrorism victims and military personnel afflicted in biological threat situations. We have applied a powerful multi-dimensional protein identification technology (MudPIT) along with newly generated software termed Profiler to identify the sequences of specific proteins observed for few <span class="hlt">strains</span> of Bacillus anthracis, a human pathogen. Software termed Profiler was created to initially screen the MudPIT data of B. anthracis <span class="hlt">strains</span> and establish the observed proteins specific for its <span class="hlt">strains</span>. A database was also generated using Profiler containing marker proteins of B. anthracis and its <span class="hlt">strains</span>, which in turn could be used for detecting the organism and its corresponding <span class="hlt">strains</span> in samples. Analysis of the unknowns by our methodology, combining MudPIT and Profiler, led to the accurate identification of the anthracis <span class="hlt">strains</span> present in samples. Thus, a new approach for the identification of B. anthracis <span class="hlt">strains</span> in unknown samples, based on the molecular mass and sequences of marker proteins, has been ascertained.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006PMB....51.5245T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006PMB....51.5245T"><span>Resolution of axial shear <span class="hlt">strain</span> elastography</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Thitaikumar, Arun; Righetti, Raffaella; Krouskop, Thomas A.; Ophir, Jonathan</p> <p>2006-10-01</p> <p>The technique of mapping the local axial component of the shear <span class="hlt">strain</span> due to quasi-static axial compression is defined as axial shear <span class="hlt">strain</span> elastography. In this paper, the spatial resolution of axial shear <span class="hlt">strain</span> elastography is investigated through simulations, using an elastically stiff cylindrical lesion embedded in a homogeneously softer background. Resolution was defined as the smallest size of the inclusion for which the <span class="hlt">strain</span> value at the inclusion/background interface was greater than the average of the axial shear <span class="hlt">strain</span> values at the interface and inside the inclusion. The resolution was measured from the axial shear <span class="hlt">strain</span> profile oriented at 45° to the axis of beam propagation, due to the absence of axial shear <span class="hlt">strain</span> along the normal directions. The effects of the ultrasound system parameters such as bandwidth, beamwidth and transducer element pitch along with signal processing parameters such as correlation window length (W) and axial shift (ΔW) on the estimated resolution were investigated. The results show that the resolution (at 45° orientation) is determined by the bandwidth and the beamwidth. However, the upper bound on the resolution is limited by the larger of the beamwidth and the window length, which is scaled inversely to the bandwidth. The results also show that the resolution is proportional to the pitch and not significantly affected by the axial window shift.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26529510','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26529510"><span>Highly Invasive Listeria monocytogenes <span class="hlt">Strains</span> Have Growth and Invasion Advantages in <span class="hlt">Strain</span> Competition.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zilelidou, Evangelia A; Rychli, Kathrin; Manthou, Evanthia; Ciolacu, Luminita; Wagner, Martin; Skandamis, Panagiotis N</p> <p>2015-01-01</p> <p>Multiple Listeria monocytogenes <span class="hlt">strains</span> can be present in the same food sample; moreover, infection with more than one L. monocytogenes <span class="hlt">strain</span> can also occur. In this study we investigated the impact of <span class="hlt">strain</span> competition on the growth and in vitro virulence potential of L. monocytogenes. We identified two strong competitor <span class="hlt">strains</span>, whose growth was not (or only slightly) influenced by the presence of other <span class="hlt">strains</span> and two weak competitor <span class="hlt">strains</span>, which were outcompeted by other <span class="hlt">strains</span>. Cell contact was essential for growth inhibition. In vitro virulence assays using human intestinal epithelial Caco2 cells showed a correlation between the invasion efficiency and growth inhibition: the strong growth competitor <span class="hlt">strains</span> showed high invasiveness. Moreover, invasion efficiency of the highly invasive <span class="hlt">strain</span> was further increased in certain combinations by the presence of a low invasive <span class="hlt">strain</span>. In all tested combinations, the less invasive <span class="hlt">strain</span> was outcompeted by the higher invasive <span class="hlt">strain</span>. Studying the effect of cell contact on in vitro virulence competition revealed a complex pattern in which the observed effects depended only partially on cell-contact suggesting that competition occurs at two different levels: i) during co-cultivation prior to infection, which might influence the expression of virulence factors, and ii) during infection, when bacterial cells compete for the host cell. In conclusion, we show that growth of L. monocytogenes can be inhibited by <span class="hlt">strains</span> of the same species leading potentially to biased recovery during enrichment procedures. Furthermore, the presence of more than one L. monocytogenes <span class="hlt">strain</span> in food can lead to increased infection rates due to synergistic effects on the virulence potential.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4631365','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4631365"><span>Highly Invasive Listeria monocytogenes <span class="hlt">Strains</span> Have Growth and Invasion Advantages in <span class="hlt">Strain</span> Competition</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Manthou, Evanthia; Ciolacu, Luminita; Wagner, Martin; Skandamis, Panagiotis N.</p> <p>2015-01-01</p> <p>Multiple Listeria monocytogenes <span class="hlt">strains</span> can be present in the same food sample; moreover, infection with more than one L. monocytogenes <span class="hlt">strain</span> can also occur. In this study we investigated the impact of <span class="hlt">strain</span> competition on the growth and in vitro virulence potential of L. monocytogenes. We identified two strong competitor <span class="hlt">strains</span>, whose growth was not (or only slightly) influenced by the presence of other <span class="hlt">strains</span> and two weak competitor <span class="hlt">strains</span>, which were outcompeted by other <span class="hlt">strains</span>. Cell contact was essential for growth inhibition. In vitro virulence assays using human intestinal epithelial Caco2 cells showed a correlation between the invasion efficiency and growth inhibition: the strong growth competitor <span class="hlt">strains</span> showed high invasiveness. Moreover, invasion efficiency of the highly invasive <span class="hlt">strain</span> was further increased in certain combinations by the presence of a low invasive <span class="hlt">strain</span>. In all tested combinations, the less invasive <span class="hlt">strain</span> was outcompeted by the higher invasive <span class="hlt">strain</span>. Studying the effect of cell contact on in vitro virulence competition revealed a complex pattern in which the observed effects depended only partially on cell-contact suggesting that competition occurs at two different levels: i) during co-cultivation prior to infection, which might influence the expression of virulence factors, and ii) during infection, when bacterial cells compete for the host cell. In conclusion, we show that growth of L. monocytogenes can be inhibited by <span class="hlt">strains</span> of the same species leading potentially to biased recovery during enrichment procedures. Furthermore, the presence of more than one L. monocytogenes <span class="hlt">strain</s