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R Naor

Publications and source records attributed to R Naor.

11 recordsLinked to original sources
PubMed2004

Identification of a Fusobacterium nucleatum 65 kDa serine protease.

A 65 kDa protease was partially purified from extracellular vesicles of Fusobacterium nucleatum cultures by preparative SDS-PAGE followed by electroelution. The pH optimum of the protease is 7.5-8.0 and its activity could be inhibited by serine protease inhibitors. The protease was found to degrade the extracellular matrix proteins fibrinogen and fibronectin as well as collagen I and collagen IV which were degraded at 37 degrees C but not at 28 degrees C, indicating the presence of a gelatinase activity in these bacteria. The 65 kDa protease was also able to digest the alpha-chains of immunoglobulin A but not immunoglobulin G. The 65 kDa F. nucleatum protease, capable of degrading native proteins, may play an important role in both the nutrition and pathogenicity of these periodontal microorganisms. The degradation of extracellular matrix proteins by bacterial enzymes may contribute to the damage of periodontal tissues, and degradation of IgA may help the evasion of the immune system of the host by the bacteria.

Collagen Type I↗
PubMed2003

Bacteriophage isolation from human saliva.

AIMS: To detect bacteriophages for Gram-positive oral pathogens in human saliva. METHODS AND RESULTS: Saliva samples from 31 donors were screened for the presence of bacteriophages for Streptococcus sobrinus, Streptococcus mutans, Streptococcus salivarius, Actinomyces viscosus and Enterococcus faecalis. Bacteriophages for Enterococcus faecalis were found in seven samples. Enterococcus faecalis phages were still present in saliva re-collected from one donor one month, and one year after initial saliva collection. CONCLUSIONS: The presence and stability of the Enterococcus faecalis bacteriophages in human saliva suggests a possible role of these bacteriophages in the oral ecosystem. SIGNIFICANCE AND IMPACT OF THE STUDY: Phage therapy as a way to control oral bacteria might be considered.

Actinomyces viscosus↗
PubMed2001

The purification and characterization of an 88-kDa Porphyromonas endodontalis 35406 protease.

A Porphyromonas endodontalis ATCC 35406 protease was purified from Triton X-114 cell extracts by preparative SDS-PAGE followed by electroelution. The purified enzyme exhibits a molecular size of 88 kDa and was dissociated into two polypeptides of 43 and 41 kDa upon heating in the presence of sodium dodecyl sulfate with or without a reducing agent. The protease (pH optimum 7.5-8.0) degraded the extracellular matrix proteins fibrinogen and fibronectin. Collagen IV was also degraded at 37 degrees C but not at 28 degrees C. The protease also cleaved the bioactive peptide angiotensin at amino acid residue phenylalanine-8 and tyrosine-4 but failed to hydrolyze bradykinin, vasopressin and synthetic chromogenic substrates with phenylalanine or tyrosine at the P1 position. In addition, two peptidases were detected in P. endodontalis cells: a proline aminopeptidase that remained associated with the cell pellet after detergent extraction and peptidase/s that partitioned into the Triton X-114 phase after phase separation and degraded the bioactive peptides bradykinin and vasopressin. These P. endodontalis peptidases and proteases may play an important role in both the nutrition and pathogenicity of these assacharolytic microorganisms. The inactivation of bioactive peptides and degradation of extracellular matrix proteins by bacterial enzymes may contribute to the damage of host tissues accompanied with endodontic infections.

Aminopeptidases↗
PubMed1999

Multiple forms of the major phenylalanine specific protease in Treponema denticola.

The 160, 190 and 270 kDa outer sheath proteases of Treponema denticola ATCC 35404 were found to be multiple forms of the major 91 kDa phenylalanine protease (PAP) by immunoblotting using anti-91 kDa specific antibodies. Multiple forms of the phenylalanine protease were also found in 2 other T. denticola strains studied, ATCC 33520 and the clinical isolate GM-1. Protein, proteolytic and Western blot analyses using antibodies against the PAP and the major outer sheath protein (MSP) indicated that the 190 and 270 kDa proteases were protein complexes formed by the MSP and the PAP. These complexes dissociated by storage in 0.3% or higher SDS concentrations. The purified PAP was found to completely degrade keratin, but was unable to degrade native actin either in its monomeric or polymerized form. The association of the MSP adhesin with a protease capable of degrading host native proteins may benefit the obtention of protein-based nutrients necessary to support the growth of these treponemes. These complexes may also play a role in the structural organization of T. denticola outer sheath.

Actins↗
PubMed1999

Activation of murine macrophages by lipoprotein and lipooligosaccharide of Treponema denticola.

We have recently demonstrated that the periodontopathogenic oral spirochete Treponema denticola possesses membrane-associated lipoproteins in addition to lipooligosaccharide (LOS). The aim of the present study was to test the potential of these oral spirochetal components to induce the production of inflammatory mediators by human macrophages, which in turn may stimulate tissue breakdown as observed in periodontal diseases. An enriched lipoprotein fraction (dLPP) from T. denticola ATCC 35404 obtained upon extraction of the treponemes with Triton X-114 was found to stimulate the production of nitric oxide (NO), tumor necrosis factor alpha (TNF-alpha), and interleukin-1 (IL-1) by mouse macrophages in a dose-dependent manner. Induction of NO by dLPP was at 25% of the levels obtained by Salmonella typhosa lipopolysaccharide (LPS) at similar concentrations, while IL-1 was produced at similar levels by both inducers. dLPP-mediated macrophage activation was unaffected by amounts of polymyxin B that neutralized the induction produced by S. typhosa LPS. dLPP also induced NO and TNF-alpha secretion from macrophages isolated from endotoxin-unresponsive C3H/HeJ mice to an extent similar to the stimulation produced in endotoxin-responsive mice. Purified T. denticola LOS also produced a concentration-dependent activation of NO and TNF-alpha in LPS-responsive and -nonresponsive mouse macrophages. However, macrophage activation by LOS was inhibited by polymyxin B. These results suggest that T. denticola lipoproteins and LOS may play a role in the inflammatory processes that characterize periodontal diseases.

Animals↗
PubMed1997

Lipoproteins of Treponema denticola: their effect on human polymorphonuclear neutrophils.

The presence of lipoproteins and lipooligosaccharides in Treponema denticola, an oral spirochaete associated with periodontal diseases, was investigated. T. denticola ATCC 35404 and the clinical isolate GM-1 were metabolically labeled with [3H]-cis-9-octadecenoic acid and extracted with the non-ionic detergent Triton X-114. The extract was phase separated, precipitated with acetone and delipidated to remove non-covalently bound lipid (dLPP). In T. denticola ATCC 35404, sodium dodecyl sulfate polyacrylamide electrophoretic separation followed by autoradiography showed [3H]-cis-9-octadecenoic acid incorporation in bands with apparent molecular masses of 14, 20, 26, 31, 38, 72 and 85 kDa and a broad band running from 113 kDa to the top of the gel. This last band resolved into a 53 kDa [3H]-cis-9-octadecenoic acid band upon heating for 10 min, at 100 degrees C. The structural relationship of the outer sheath major oligomeric polypeptide of strain ATCC 35404 and the 53 kDa protein was demonstrated immunologically. Antibodies against the 113 kDa component of the oligomer cross-reacted with the 53 kDa protein. Proteinase K degraded the [3H]-cis-9-octadecenoic acid bands with the exception of the 14 kDa. The 14 kDa was also the major [3H]-fatty acid labeled compound found in the water phase following phenol-water extraction of whole T. denticola ATCC 35404 cells. This compound was purified from the water phase by gel filtration followed by hydrophobic chromatography. Chemical analysis showed that hexadecanoic acid was the predominant fatty acid bound to T. denticola lipoproteins. In the GM-1 strain [3H]-cis-9-octadecenoic acid incorporation was observed in the 116 kDa and 14 kDa bands. dLPP from strain ATCC 35404 caused an enhanced (0.8-8 micrograms/ml) luminol dependent chemiluminiscence (LDCL) effect in human polymorphonuclear neutrophils (PMN) which could be related to protein concentration. The addition of dLPP to PMN together with FMLP at submaximal concentration (1 microM) resulted in a synergistic activation of LDCL. At 21 micrograms/ml, dLPP also induced lysozyme release by the PMN at approximately 30% of the release induced by the chemotactic peptide at 1 microM. In addition, dLPP (21 micrograms/ml) increased additively the release of lysozyme caused by 1 microM FMLP. The release of beta-glucuronidase was not affected. The modulation of neutrophil activity was abolished by preincubation of dLPP with proteinase K. The purified 14 kDa had no effect on either LDCL or exocytosis of lysosomal enzymes of PMN. These data strongly suggest that T. denticola possesses several lipoproteins including outer sheath major oligomeric polypeptides (113-234 kDa) and a lipooligosaccharide of molecular mass of 14 kDa. In addition, an enriched lipoprotein fraction from this oral spirochaete modulates oxygen dependent and independent mechanisms for controlling microorganisms by human PMN.

Antibodies↗
PubMed1995

Proteases of Treponema denticola outer sheath and extracellular vesicles.

Electron microscopical observations of the oral periodontopathogen Treponema denticola show the presence of extracellular vesicles bound to the bacterial surface or free in the surrounding medium. Extracellular vesicles from T. denticola ATCC 35404, 50 to 100 nm in diameter, were isolated and further characterized. Protein and proteolytic patterns of the vesicles were found to be very similar to those of isolated T. denticola outer sheaths. They were enriched with the major outer sheath polypeptides (molecular sizes, 113 to 234 kDa) and with outer sheath proteases of 91, 153, 173, and 228 kDa. These findings indicate that treponemal outer sheath vesicles contain the necessary adhesins and proteolytic arsenal for adherence to and damage of eucaryotic cells and mammalian matrix proteins. The major outer sheath- and vesicle-associated protease of T. denticola ATCC 35404 was purified and characterized. The purified enzyme had a molecular size of 91 kDa, and it dissociated into three polypeptides of 72, 38, and 35 kDa upon heating in the presence of sodium dodecyl sulfate with or without a reducing agent. The activity of the enzyme could be inhibited by diisopropylfluorophosphate, phenylmethylsulfonyl fluoride, and phenylboronic acid. The value of the second-order rate constant of the protease inactivation by phenylmethylsulfonyl fluoride was 0.48 x 10(4) M(-1) min-1. Inhibition of the enzyme by phenylboronic acid was rapid (< 1 min) and pH dependent. These data strongly suggest that this major surface proteolytic activity belongs to a family of serine proteases.

Amino Acid Sequence↗
PubMed1994

Characterization of fibrinolytic activities of Treponema denticola.

Several fibrinolytic activities of Treponema denticola, an oral spirochete associated with gingivitis and periodontal disease, were identified and characterized following phase partitioning with the nonionic detergent Triton X-114. The apparent molecular masses of the proteases ranged from 91 to 228 kDa when analyzed in sodium dodecyl sulfate-polyacrylamide gels containing fibrinogen as the protease substrate. A qualitative analysis of zymograms showed that the proteases were highly enriched in the detergent phase, although the 91-, 173-, and 228-kDa proteases were also found in the aqueous phase. Zymograms of crude outer sheaths prepared by repeated freezing-thawing revealed that the proteases may be associated with this subcellular compartment. The proteases displayed substrate specificity towards fibrinogen, were susceptible to sulfhydryl group reagents, and had a pH optimum between 7 and 8. The similarities in their sensitivity to inhibitors, temperature stability, pH optimum, and laddered protein profiles suggest that these hydrolytic enzymes may be part of a family of oligomeric proteases that may play an important role in the invasiveness of and tissue damage caused by the spirochete.

Endopeptidases↗
PubMedDate not supplied

Periodontal status among adult immigrants from rural Ethiopia.

Dental research has emphasized the importance of understanding the epidemiology and etiology of periodontal disease, the second most prevalent dental pathology. The World Health Organization includes periodontal health prevalence, according to the Community Periodontal Index of Treatment Needs (CPITN), in its Global Oral Data Bank. Recent immigrants to Israel from Ethiopia offer a unique and important opportunity for investigation. Seventy adults aged 35-45 years were examined. Dividing the dentition into six sextants (according to CPITN), on average, two sextants were found to be healthy and only 1.18 sextants revealed shallow or deep pockets. These results demonstrate a relatively healthy periodontal status, as compared both to Israeli adults and data from the WHO Data Bank. Periodontal health has traditionally been related to regular dental visits (professional teeth cleaning) and home oral hygiene maintenance (toothbrushing and flossing). This population of immigrants had never visited dentists or hygienists nor used toothbrushes or dental floss. The periodontal health of this population is therefore of particular interest.

Adult↗
PubMedDate not supplied

The composition of subgingival microflora in two groups of children with and without primary dentition alveolar bone loss.

The is study examined the relationships between the microbial composition of the subgingival plaque, contact loss caused by caries and alveolar bone loss (ABL) in primary molars. The study included 10 children with contact loss in at least two sites, one with ABL and one without ABL, and 10 children without ABL with sites with or without contact loss. The microbial composition of subgingival plaque was examined by dark-field microscopy and by cultures of total anaerobic bacteria, Actinobacillus actinomycetemcomitans (Aa) and Porphyromonas gingivalis (Pg). Dark-field microscopy confirmed that spirochetes and motile rods may be part of the indigenous flora of the oral cavity. More spirochetes and motile rods were observed in sites with ABL than in control sites in the same subject and control subjects without ABL. Lower numbers of cocci were seen in sites with ABL than in sites in children without ABL, but a significant difference was not observed between sites with ABL and healthy sites within the same subjects. No significant differences in the dark-field values were evident in sites without ABL, with or without contact loss. Aa and Pg were found in children and sites with or without ABL. In sites with Aa, larger proportions of spirochetes, lower values of cocci, and more colonies of Pg were evident. No significant differences in anaerobic bacteria were evident between sites with or without contact loss or with or without ABL. ABL in the primary dentition was found to be related to the microbial composition of the subgingival plaque, but not related to contact loss per se.

Aggregatibacter actinomycetemcomitans↗