bluuebunny/crossref_metadata_2025 huggingface dataset:
Immunodominant antigens of Porphyromonas gingivalis in patients with rapidly progressive periodontitis
Authors: Chen H.A. , Weinberg A. , Darveau R.P. , Engel D. , Page R.C.
Published: December 2007

We studied 4 isolates of Porphorymonas gingivalis, ATCC 33277, 381, A7A1‐28, and W50, to identify major cell surface antigens and select the best strain from which to obtain antigen for a test vaccine. Immunoglobulin G (IgG) titers measured by enzyme‐linked immunosorbent assay using whole‐cell sonicates as antigen were significantly elevated for the sera of 64 rapidly progressive periodontitis patients relative to sera of 30 normal control subjects for each of the 4 strains studied. Western blots were prepared for all 4 strains and developed using sera from 22 patients and 20 control subjects to identify and determine the frequency of antibody‐binding components. The intensity of binding by patient sera was greatest for the 75‐kDa and 55‐kDa components. The 43‐kDa component was also widely recognized. Strains ATCC 33277 and 381 appeared to be antigenically similar. Because of the higher serum antibody titers, the larger proportion of seropositive patients and higher frequency of binding to specific protein components in Western blots, our efforts were focused on strain ATCC 33277. Whole‐cell sonicates, proteinase K‐digested sonicate, lipopolysaccharide, capsular polysaccharide, and whole‐cell protein fractions were prepared and evaluated for anti‐genie activity. By dot immunoblot, most of the antibody binding activity was found in the whole‐cell protein fraction, with much lesser amounts in lipopolysaccharide and none in capsular polysaccharide. The antibody‐binding activity was accessible on the cell surface, since 98.9% of P. gingivalis‐specific antibody, including antibody binding to the 43‐kDa, 55‐kDa and 75‐kDa components on Western blot, was removed by whole‐cell adsorption. Furthermore, the 43‐kDa and 55‐kDa but not the 75‐kDa component on intact cells were accessible for labeling with 125I, confirming their cell surface location and accessibility.
Microbial alterations in supragingival dental plaque in response to a triclosan‐containing dentifrice
Authors: Zambon J. J. , Reynolds H. S. , Dunford R. G. , DeVizio W. , Volpe A. R. , Berta R. , Tempro J. P. , Bonta Y.
Published: December 2007

A total of 325 subjects were entered into a double‐blind, stratified 2–treatment clinical study that examined the effects of a dentifrice containing 0.3% triclosan, 2% Gantrez® copolymer and 0.243% sodium fluoride on supragingival dental plaque and gingivitis. A subset of 159 subjects including 72 men and 87 women participated in the microbiological component of this study, which was designed to detect shifts in supragingival bacterial species in response to triclosan. Subjects were divided into two groups: one performed normal oral hygiene with the triclosan/copolymer dentifrice and a control group used a placebo dentifrice without triclosan. At baseline, 3 and 6 months during treatment and at 6, 12, 18 and 24 weeks post‐treatment, supragingival dental plaque was collected from the buccal and lingual surfaces of the 4 first molar teeth and assayed for: 1) bacterial morphotypes by phase‐contrast microscopy; 2) select bacterial groups and bacterial species by culture; and 3) target periodontal pathogens including Actinobacillus actinomycetemcomitans, Bacteroides forsythus, Porphyromonas gingivalis and Prevotella intermedia by immunofluorescence microscopy. There were few statistically significant differences between treatment groups in any of the 90 microbiological parameters measured at the 7 different time points. The control group demonstrated significantly higher levels of cultivable Neisseria and higher proportions at the 3–month treatment period of P. gingivalis‐infected subjects and mean cells. After 6 months of treatment, the triclosan group demonstrated higher levels of fusiforms. Analysis of triclosan resistance data failed to detect a shift towards increased proportions of bacteria resistant to triclosan, and both treatment groups demonstrated triclosan‐resistant strains, predominantly Veillonella dispar. This study confirms the microbiological safety of triclosan‐containing dentifrices and suggests that continued use can be associated with beneficial alterations in the bacterial composition of supragingival dental plaque.
In vivo cleavage of immunoglobulin A1 by immunoglobulin A1 proteases from Prevotella and Capnocytophaga species
Authors: Frandsen E. V. G. , Reinholdt J. , Kjeldsen M. , Kilian M.
Published: December 2007

Immunoglobulin Al (IgA1) proteases secreted by oral Prevotella and Capnocytophaga species specifically cleave IgA1 at the same peptide bond in the hinge region, leaving intact monomeric Fab and Fc fragments. Assuming that Prevotella‐ and Capnocytophaga‐induced Fab fragments of IgA1 expose a specific, immunogenic neoepitope at the cleavage site, we established an enzyme‐linked immunosorbent assay to measure human serum antibodies to this neoepitope as indirect evidence of in vivo activity of Prevotella and Capnocytophaga IgA1 proteases. The assay used a monoclonal antibody with specificity for the neoepitope, and the ability to block binding of the monoclonal antibody to the neoepitope was investigated. Absorption of sera with Prevotella melaninogenica‐induced Fab fragments of IgA1 resulted in removal of antibodies blocking binding of the monoclonal antibody, whereas absorption with Fab fragments induced by bacterial IgA1 proteases of other cleavage specificities did not remove blocking antibodies. Consequently, we assume that the antibodies detected had been induced by a neoepitope on the Fab fragment of IgA1 exposed exclusively after cleavage with IgA1 proteases from Prevotella and Capnocytophaga, indicating in vivo activity of these IgA1 proteases. Evidence, though indirect, of in vivo activity of Prevotella and Capnocytophaga IgA1 proteases was present in 42 of 92 sera examined and in a significantly higher proportion of sera from adults with periodontal disease compared with control individuals. No correlation with disease was observed for the juvenile periodontitis groups.
Porphyromonas gingivalis outer membrane vesicles promote bacterial resistance to chlorhexidine
Authors: Grenier D. , Bertrand J. , Mayrand D.
Published: December 2007

Porphyromonas gingivalis has been frequently associated with some types of periodontal diseases and possesses various mechanisms favoring the pathogenic process. It has been recently observed that vesicles elaborated by P. gingivalis are able to protect bacteria from the bactericidal activity of human serum. The aim of the present investigation was to evaluate the ability of vesicles from P. gingivalis in protecting oral bacteria against chlorhexidine. Data indicate that vesicles released by P. gingivalis may bind chlorhexidine, thus allowing protection for itself and for other oral bacterial species. It has also been demonstrated that lipopolysaccharides are the major component involved in the binding of chlorhexidine by vesicles. The mechanism of resistance reported in this study indicates that bacterial interactions in the oral cavity may influence the sensitivity of microbes.
Mechanism of inhibition of glycolysis in Streptococcus mutans NCIB 11723 by chlorhexidine
Authors: Iwami Y. , Schachtele C. F. , Yamada T.
Published: December 2007

Inhibition of the rate of acid production from glucose by the cells of Streptococcus mutans was directly related to the concentrations of 0.075 to 0.20 mM chlorhexidine. Lactate production was inhibited to a greater extent than acetate and formate. Quantification of glycolytic intermediates revealed that the steps in glycolysis inhibited by chlorhexidine were the reactions catalyzed by phosphofructokinase and glyceraldehyde 3‐phosphate dehydrogenase and/or phosphoglycerate kinase. However, the activities of these enzymes were not decreased in cells treated with the inhibitor. It was demonstrated that chlorhexidine caused leakage of metabolites from the cells. Our results indicate that the decreased rate of glycolysis caused by chlorhexidine is due to the leakage of metabolic intermediates and not to direct effects on enzymes involved in glycolysis by S. mutans NCIB 11723.
Viability of four putative periodontal pathogens and enteric rods in the anaerobic transport medium VMGA III
Authors: Ali R. W. , Bancescu G. , Nielsen Ø. , Skaug N.
Published: December 2007

The aim of this study was to determine the survival in VMGA III of Porphyromonas gingivalis, Prevotella intermedia, Fusobacterium nucleatum, Actinobacillus actinomycetemcomitans and enteric rods in laboratory cultures as well as in sub‐gingival plaque samples. Laboratory strains of the 4 putative periodontal pathogens and Escherichia coli were used in the laboratory part of the study. Also, 31 subgingival plaque samples were obtained from 22 periodontal patients and stored in VMGA III. Each sample, from both the laboratory and the clinical parts, was divided into 3 portions. One portion was cultured within a few hours of collection (baseline), while the second was processed after 24 h (day 2) and the third 48 h later (day 3). The results of the clinical part indicate that the detection frequencies of all 4 periodontal pathogens and their levels in positive samples decreased, to different degrees, by day 2 and decreased further by day 3. Enteric rods were not detected in baseline samples. However, they were present in 16.1% and 22.6% of day 2 and day 3 samples, respectively. Similarly, the laboratory results demonstrate a significant decrease in the levels of the 4 periodontal pathogens tested by day 2 and day 3, whereas the opposite occurred for E. coli. P. gingivalis, P. intermedia, and F. nucleatum survived better in the presence of E. coli than alone, whereas A. actinomycetemcomitans survived less well when co‐inoculated with E. coli. VMGA III appears to maintain microbial population ratios for periods up to 24 h. After 24 h, the multiplication of enteric organisms may alter the original proportions of the sample.
Detection of human viruses in periodontal pockets using polymerase chain reaction
Authors: Parra B. , Slots J.
Published: December 2007

Even though viruses have been implicated in the etiology of several medical and dental disorders, little or no data are available on the possible involvement of human viruses in the pathogenesis of human periodontal disease. This study investigated the presence of human cytomegalovirus, Epstein‐Barr virus, herpes simplex virus, human papillomavirus and human immunodeficiency virus (HIV) in crevicular fluid samples from 30 patients with advanced periodontitis and 26 subjects with gingivitis. Viral identification was performed on direct subgingival samples from 3 diseased sites in each patient using the polymerase chain reaction technique. Seventy‐eight percent of advanced periodontitis patients were positive for at least one of the five test viruses. Cytomegalovirus was detected in 60% of the periodontitis patients, Epstein‐Barr virus in 30%, herpes simplex virus in 20%, human papillomavirus in 17% and HIV in 7%. Forty percent of the periodontitis patients revealed coinfection by 2 to 5 viruses. Only 31 % of the gingivitis subjects showed a positive viral identification in crevicular fluid, and infected individuals only revealed human cytomegalovirus. This study demonstrated that human viruses may occur in periodontitis lesions with relatively high prevalence. The pathogenetic significance of human viruses in destructive periodontal disease needs to be determined.
Lipopolysaccharide isolated from Porphyromonas gingivalis grown in hemin‐limited chemostat conditions has a reduced capacity for human neutrophil priming
Authors: Champagne C. M. , Holt S. C. , Van Dyke T. E. , Gordon B. J. , Shapira L.
Published: December 2007

One way prokaryotes respond to environmental stresses is by modifying selected outer membrane components. Iron, in the form of hemin, has been shown to be a significant regulator of Porphyromonas gingivalis growth and virulence and of the expression of outer membrane proteins and lipopolysaccharide. Since lipopolysaccharide has profound effects on host immune cells, this study compared the effect of hemin‐restricted and hemin‐normal P. gingivalis growth conditions on lipopolysaccharide priming of N‐formylmethionyl‐leucyl‐phenylalanine‐induced superoxide generation by human neutrophils. P. gingivalis was grown in a chemostat under normal (5 μg hemin/ml) and hemin‐restricted (0.08 μg hemin/ml) conditions. Purified lipopolysaccharide from both P. gingivalis normal and hemin‐limited environments increased N‐formylmethionyl‐leucyl‐phenylalanine‐induced superoxide release by neutrophils in a dose‐dependent manner. Lipopolysaccharide isolated from the hemin‐normal conditions was a significantly more potent neutrophil priming agent than the lipopolysaccharide isolated from hemin‐restricted conditions. Addition of normal human serum enhanced the priming effect of both lipopolysaccharide preparations; this effect, however, was more evident with the hemin‐normal lipopolysaccharide. Further, this enhancing effect of serum was partly reduced in the presence of antibodies raised against the serum lipopolysaccharide‐binding protein. The differences in the biological activity of the two lipopolysaccharide preparations could be associated with structural differences detected by sodium dodecyl sulfate‐poly acrylamide gel electrophoresis analysis. These results indicate that hemin availability affects regulation of an aspect of P. gingivalis virulence, lipopolysaccharide‐human neutrophils priming. The reduced capacity for neutrophil priming by hemin‐restricted lipopolysaccharide appears to be related to lipopolysaccharide‐neutrophil interactions and not to serum factors. Targeting bacterial cell‐surface components involved in hemin transport might be effective therapy for P. gingivalis‐associated periodontal diseases.
Mammalian viruses in human periodontitis
Authors: Contreras A. , Slots J.
Published: December 2007

A prior investigation has demonstrated a higher prevalence of human cytomegalovirus (HCMV) and Epstein‐Barr virus (EBV) in subgingival specimens from periodontitis patients than from gingivitis patients. This study aimed to determine the frequency of HCMV, EBV‐1, EBV‐2, herpes simplex virus (HSV) and human immunodeficiency virus (HIV) in subgingival samples from 27 adults who each contributed both a periodontitis and a gingivitis site. Viral detection was performed using a nested‐polymerase chain reaction method. Twenty‐four subjects (89%) yielded at least one of the five test viruses from deep periodontal pockets, wheras only 15 (56%) showed viruses from shallow periodontal sites (P=0.015; chi‐square test). Viral co‐infection occurred more frequently in deep than in shallow periodontal sites (P=0.015). HCMV was detected with higher frequency in deep than in shallow periodontal sites (P=0.023). The possible periodontopathogenic mechanisms of mammalian viruses in human periodontitis are discussed. The role and importance of HCMV and other mammalian viruses in the initiation and progression of destructive periodontal disease merits further investigation.
Isolation and preliminary characterization of the Streptococcus mutans rpsJ gene
Authors: Shibata Y. , Kuramitsu H. K.
Published: December 2007

We previously reported that four putative open reading frames were identified in the regions flanking the Streptococcus mutans GS‐5 fructosyltransferase gene. For one of these, ORF 4, only a small region had been isolated and the first 30 nucleotides had been sequenced. In order to determine whether this open reading frame is part of an expressed gene, we isolated a DNA fragment containing intact ORF 4 and a portion of the downstream ORF 5 by inverse polymerase chain reaction. A comparison of the deduced amino acid sequences of ORF 4 and ORF 5 with other proteins revealed that the ORF 4 and ORF 5 gene products were highly homologous to ribosomal proteins S10 and L3, respectively, of several bacteria. To identify the precise transcriptional start site for the ORF 4 gene, primer extension analysis was carried out. The results indicated initiation at a G residue with corresponding ‐10 and ‐35 regions homologous to the Escherichia coli consensus promoter sequences. These results indicate that the sequences of ORF 4 and ORF 5 are consistent with the structures of ribosomal proteins S10 and L3, respectively, and are present in a ribosomal protein operon.
Immunohistological characteristics of periodontal lesions associated with Porphyromonas gingivalis and Actinobacillus actinomycetemcomitans infections
Authors: Wikström M. , Wennstrom J. L. , Renvert S. , Jonsson R.
Published: December 2007

In this study, various phenotypes of infiltrating cells in the periodontium adjacent to pockets harboring Porphyromonas gingivalis and Actinobacillus actinomycetemcomitans were evaluated. Furthermore, the pattern of Class II antigen expression in the periodontal tissues was determined. Eight lesions were associated with the presence of P. gingivalis and 12 with A. actinomycetemcomitans. Predominant cells in the inflammatory infiltrate were T‐ and B‐cells. In most biopsies T‐cells dominated over B‐cells. The proportion of P. gingivalis, but not of A. actinomycetemcomitans, was positively correlated to the total number of infiltrating cells in the tissue. A. actinomycetemcomitans sites demonstrated somewhat lower proportions of CD3+, CD4+ and CD19+ cells than P. gingivalis sites. However, the tendency of decreasing CD4+/CD8+ ratio with increasing number of A. actinomycetemcomitans indicates a local imbalance in immunoregulation. The frequency of class II antigen expression of both mononuclear and epithelial cells, a sign of immunological activation, was generally high.
The use of allozyme electrophoresis to assess genetic heterogeneity among previously subspeciated isolates of Fusobacterium nucleatum.
Authors: Morris M. L. , Andrews R. H. , Rogers A. H.
Published: December 2007

Fusobacterium nucleatum. has been implicated in the pathogenesis of periodontal diseases. Five subspecies have previously been proposed. The validity of these subdivisions was investigated using allozyme electrophoresis for 21 enzyme mobilities. The 18 F. nucleatum isolates tested had previously been subspeciated and included type strains as well as isolates from both oral and extraoral sites. The results showed 2 distinct genetic groups with fixed differences at 82.5% of the test loci, indicative of a species complex with a number of subspecies within each of the 2 groups. There was also evidence of a correlation between the 2 major groups of isolates and the site from which they were taken. It was concluded that there is a high degree of genetic heterogeneity within the species F. nucleatum and that its current subspeciation is of questionable validity.
Coaggregation of Candida albicans oral Actinomyces species
Authors: Grimaudo N. J. , Nesbitt W. E. , Clark W. B.
Published: December 2007

Eight strains of Actinomyces were examined for their ability to coaggregate in vitro with four strains of Candida albicans. The Actinomyces coaggregated to various degrees with all of the Candida strains. Exposure of the Candida but not the Actinomyces to heat, trypsin, proteinase K, amphotericin B or trichodermin abolished Coaggregation. All sugars tested did not inhibit any of the reactions. All coaggregating pairs were disaggregated by the addition of SDS, but nonionic detergents had no effect. The addition of urea or EDTA completely reversed Coaggregation. Actinomyces strains were sensitive to periodate oxidation, whereas the Candida strains were unaffected. These data suggest that the coaggregations involve a protein on the Candida surface that may interact with carbohydrates or carbohydrate‐containing molecules on the surface of the Actinomyces. These observations expand the known range of intergeneric coaggregations occurring between human oral microbes and indicate that Coaggregation of C. albicans and Actinomyces may be an important factor in oral colonization by this yeast.
Distribution and genetic analysis of oral Prevotella intermedia and Prevotella nigrescens
Authors: Mättö J. , Saarela M. , von Troil‐Lindén B. , Könönen E. , Jousimies‐Somer H. , Torkko H. , Alaluusua S. , Asikainen S.
Published: December 2007

A total of 344 Prevotella intermedia and nigrescens group isolates from 59 subjects were identified by hybridization with nonradioactively labeled species‐specific oligonucleotide probes. Identification of 20 P. intermedia and 46 P. nigrescens isolates was confirmed by analyzing the electrophoretic mobilities of malate and glutamate dehydrogenase enzymes. A total of 111 isolates (32%) were identified as P. intermedia and 233 isolates (68%) as P. nigrescens. Identification performed with oligonucleotide probes and with malate and glutamate dehydrogenase electrophoresis matched perfectly. The distribution of oral P. intermedia and P. nigrescens in various periodontal status groups was investigated in periodontally healthy or diseased individuals. To reveal intra‐ and interindividual genetic diversity and possible intrafamilial transmission, P. intermedia and P. nigrescens isolates from 16 to 59 subjects, representing 8 married couples, were ribotyped. The stability of colonization was examined in 12 of the 59 subjects, of whom 6 received periodontal treatment and 6 were untreated. All children and periodontally healthy adults and most subjects with initial periodontitis (13/21) harbored only P. nigrescens. Of the 20 subjects with advanced periodontitis, 7 harbored both P. intermedia and P. nigrescens, 7 only P. intermedia and 6 only P. nigrescens. One or two ribotypes of P. intermedia and/or P. nigrescens were found intraindividually. The spouses in 5 of the 8 married couples shared an identical ribotype of P. intermedia or P. nigrescens, whereas ribotypes from unrelated subjects were mostly unique. Colonization was stable, since the same ribotypes were found 1–6 months apart in both periodontally treated and untreated subjects. In conclusion, the study indicates that P. intermedia and P. nigrescens may occur simultaneously in the oral cavity, the colonization is stable and P. intermedia is associated with periodontal diseases. Ribotyping revealed considerable genetic heterogeneity in unrelated subjects, whereas isolates obtained from spouses could represent the same ribotype, which suggests transmission of these species.
Hyaluronan, a possible ligand mediating Treponema denticola binding to periodontal tissue
Authors: Haapasalo M. , Hannam P. , McBride B.C. , Uitto V.‐J.
Published: December 2007

Binding of Treponema denticola ATCC 35405 to glycosaminoglycans, fibrinogen, type I collagen and porcine periodontal ligament epithelial cells was studied using an enzyme‐linked immunosorbent assay. T. denticola bound to hyaluronan (hyaluronic acid) and its hexameric fragments, whereas little or no binding was detected to chondroitin‐4‐sulfate or dermatan sulfate proteoglycan. Binding of T. denticola to hyaluronan gradually increased during the 2‐h incubation time. In contrast, binding to fibrinogen and type I collagen was more rapid, peaking within 5 min. T. denticola also bound to microbeads coated with hyaluronan and formed visible aggregates in solution. Pretreatment of the bacteria with hyaluronan or fibrinogen inhibited binding to hyaluronan. Gelatin, bovine serum albumin, chondroitin‐4‐sulfate, chondroitin‐6‐sulfate, heparin, dermatan sulfate, glucuronic acid, N‐acetylglucosamine and N‐acetyl‐galactosamine did not inhibit binding. Binding was also inhibited by heating T. denticola and by pretreatment of the spirochetes with sodium periodate, phenylmethylsulfonyl fluoride, and p‐chloromercurybenzoic acid. All these treatments also inhibited the chymotrypsin‐like activity of T. denticola. Hyaluronan strongly inhibited binding of T. denticola to epithelial cells, whereas the other glycosaminoglycans and N‐acetyl‐glucosamine did not. The results show that T. denticola binds to hyaluronan, possibly by a mechanism involving the chymotrypsin‐like surface protein of T. denticola.
Properties of practical oral liposome‐Streptococcus mutans glucosyltransferase vaccines for effective induction of caries protection
Authors: Childers N. K. , Zhang S. S. , Harokopakis E. , Harmon C. C. , Michalek S. M.
Published: December 2007

Here we report the effectiveness of various liposome vaccines containing Streptococcus mutans glucosyltransferase (GTF) in protecting against dental caries after oral immunization. Rats were immunized by gastric intubation of the appropriate liposome vaccine at weaning and boosted 3 times. Rats were infected with S. mutans following initial immunization and fed cariogenic diet (Diet 305). Saliva and serum were collected during the study and assessed for antibody activity by enzyme‐linked immunosorbent assay. Mandibles were removed on day 47 and assessed for S. mutans levels and then for caries. Animals immunized with sonicated, filtered and microemulsined GTF liposome preparations had decreased levels of dental caries compared with control animals given empty liposomes. Rats given dehydrated/rehydrated or purified liposomal GTF also had significantly less caries than control group (GTF alone). Because of economy, ease of preparation and efficiency in amount of antigen used, filtered, dehydrated/rehydrated and purified liposomal GTF preparations are most practical for use in further assessing the efficacy of liposomal GTF in oral immunization.
Catabolic pathway for aerobic degradation of lactate by Actinomyces naeslundii
Authors: Takahashi N. , Yamada T.
Published: December 2007

The aerobic metabolism of lactate by oral Actinomyces was studied. Six of 7 strains of Actinomyces naeslundii increased their growth in the presence of lactate under aerobic conditions. Washed cells grown on lactate aerobically degraded lactate and pyruvate to acetate with a concomitant consumption of oxygen. In the presence of catalase, the molar ratios of oxygen consumed to acetate produced were 1 for lactate degradation and 0.5 for pyruvate degradation. The enzymatic activities found in cell extracts revealed that lactate could be converted to pyruvate by NAD‐independent lactate dehydrogenase (iLDH) and further to acetyl CoA by pyruvate dehydrogenase (PDH). The acetyl CoA formed could be metabolized into acetate by phosphotrans‐acetylase (PTA) and acetate kinase (AK) with the formation of ATP. These results indicate that A. naeslundii metabolizes lactate into acetate by the sequential enzymatic reactions iLDH, PDH, PTA and AK and that hydrogens produced by iLDH and PDH are transferred to oxygen. The activity of lactate degradation and oxygen consumption may modify the environmental conditions of dental plaque.
Investigation of the Actinobacillus actinomycetemcomitans genome by pulsed field gel electrophoresis
Authors: Vaicarcel J. , Allardet‐Servent A. , Bourg G. , O'Callaghan D. , Michailesco P. , Ramuz M.
Published: December 2007

Pulsed field gel electrophoresis was used to investigate nineteen strains of Actinobacillus actinomycetemcomitans. The genome was found to contain a single chromosome whose size we estimate to be 2300 kb from the sum of restriction fragments generated with rare cutting endonucleases. We detected the presence of large plasmids with sizes ranging from 35 to 300 kb. In some strains, extrachromosomal elements constitute over 20% of the total genome. Comparison of the profiles of Apal digests of the 19 strains showed a high degree of polymorphism with 13 different profiles, providing a new tool for epidemiological studies.
Hemagglutinin activity and heterogeneity of related Porphyromonas gingivalis proteinases
Authors: DeCarlo A. A. , Harber G. J.
Published: December 2007

Thiol‐dependent proteinases that are expressed and released by Porphyromonas gingivalis are considered virulence factors in periodontitis because of their potential to effect matrix degradation and inflammation. A number of P. gingivalis thiol‐proteinases have been described, however, with similar biochemical characteristics. In this report we demonstrate that an isolated P. gingivalis proteinase consists of nonco‐valently associated peptides and that slight variations in the association pattern of these peptides could result in different proteinases with different affinities and activities. We also describe the co‐purification of thiol‐proteinase activity with hemagglutinin activity and demonstrate that each type of activity has similar inhibition profiles. With the use of monoclonal antibodies against the P. gingivalis proteinase we follow proteinase released into the culture medium over the course of 10 days and, by Western blot analysis, demonstrate that many of the proteinases with varying molecular weight are related. The identification of a single, immunoreactive, 140 kDa proteinase detected early in the culture and in association with the P. gingivalis cells suggests that multiple proteinases may originate from a single 140 kDa proteinase.
Isolation and characterization of a nonpigmented variant of Porphyromonas endodontalis
Authors: Suzuki K. , Ikeda T. , Nakamura H. , Yoshimura F.
Published: December 2007

Porphyromonas endodontalis forms dark colonies on media containing blood. We isolated, from an infected root canal, a non‐black‐pigmented P. endodontalis variant, KSEW01, which forms beige colonies on blood agar media. To characterize this variant, we compared its properties with those of two black‐pigmented P. endodontalis strains, ATCC35406 and KSE105. Strain KSEW01 had a gelatinase activity comparable to that of the pigmented strains. Cell lysates of these three strains resolved by SDS‐PAGE electrophoresis showed similar protein patterns. Quantitative DNA‐DNA hybridization experiments indicated high homology between the nonpigmented strain KSEW01 and the two dark‐pigmented strains. From these results, we identified strain KSEW01 as a P. endodontalis nonpigmented variant. DNA restriction endonuclease analysis indicated that the variant was closely related to a pigmented strain, KSE105. In constrast to the pigmented strains, strain KSEW01 did not degrade hemoglobin and formed no vesicles when cultured in the presence of blood. The susceptibilities of these three strains to 22 antibiotics were similar except for vancomycin. The nonpigmented variant was the most resistant to vancomycin (MIC: ATCC35406, 6.25 μg/ml; KSE105, 12.5 μg/ml; KSEW01, 100 μg/ml). Overall, a relationship may exist between the presence of black‐pigmentation and outer membrane systems of P. endodontalis.
Environmental effects on the growth and proteolysis of Treponema denticola ATCC 33520
Authors: Mikx F. H. M.
Published: December 2007

The effect of pH, redox potential, O2 and H2 on the growth and proteolytic activity of Treponema denticola ATCC 33520 was studied in a chemostat at different growth rates. The peptidase and protease activities were estimated using different amido‐methyl coumarin derivatives and azocasein. The maximum growth rate of T. denticola ATCC 33520 was 0.14 h−1. Reduction of the growth rate of T. denticola by 50–60% gave: an increase in cell mass of 150–200%, a higher acetogenesis and a shift of the pH optimum. The protease and phenylalanine peptidase activities seemed to be of greater importance for the growth of T. denticola ATCC 33520 than the rather low arginine and proline peptidase activities. The redox potential (Eh) played a secondary role. At microaerophilic conditions with 1–5% O2, the cultures maintained a redox potential below −311 mV and an optimal acetogenesis. The presence of H? induced a marked growth stimulation of T. denticola ATCC 33520. It is concluded that the cell mass and proteolytic activity of T. denticola ATCC 33520 are modulated by the growth rate and the pH and to a lesser extend by the redox potential and presence of O2. Stagnation of the exudate‐flow influences these factors and will lead to an increase of the spirochetal population and proteolysis in the periodontal pocket.
Albumin and hemalbumin degradation by Porphyromonas gingivalis
Authors: Smalley J. W. , Birss A. J.
Published: December 2007

Degradation of bovine albumin and hemalbumin by Porphyromonas gingivalis W50 cells under non‐reducing conditions at 37°C was examined by sodium dodecyl sulfate‐polyacrylamide gel electrophoresis and densitometry. Albumin and hemalbumins with heme: protein molar ratios of 1:1, 4:1 and 8:1 were degraded, yielding protease‐resistant 55.6‐kDa peptides. Cells of strains WPH 35, 11834 and Bg 381 also produced a similar digestion pattern. TV‐terminal sequencing of the 55.6‐kDa albumin digestion fragment revealed two peptides with the sequences 82glu‐thr‐tyr‐gly‐asp‐met‐ala and 95gln‐pro‐glu‐arg‐asn‐glu‐cys, indicating cleavage in the TV‐terminal hinge region. Tosyllysylchloromethylketone and N‐ethylmaleimide were the most effective in inhibiting breakdown of albumin and hemalbumin with a 1:1 heme: protein ratio. Initial degradation rates of albumin and all hemalbumins were similar, but the total amount of hemalbumins degraded over 7.5 h decreased with increased ratio of bound hemin. The specific proteolysis of hemalbumin may enable P. gingivalis to release hemin from a region of the molecule where heme binding is least avid.
Effects of acidification on growth and glycolysis of Streptococcus sanguis and Streptococcus mutans
Authors: Takahashi N. , Horiuchi M. , Yamada T.
Published: December 2007

After carbohydrate intake, pH in dental plaque decreases rapidly and reaches about 4 within a few minutes. The acidification not only promotes demineralization of tooth surface but can also cause damage to bacteria in dental plaque. We, therefore, investigated the effect of acidification on the dental plaque bacteria Streptococcus sanguis and Streptococcus mutans. At pH 4.0 and 4.2, both growth and glycolytic activities in these streptococci were repressed. Prolonged acidification (for 60 min at pH 4.0) not only repressed both growth and glycolytic activities but also impaired them in S. sanguis cells with concomitant inactivation of the glycolytic enzymes, hexokinase, phosphofructokinase, glyceraldehyde‐phosphate dehydrogenase and enolase. The impaired abilities of glycolysis and growth recovered following incubation at pH 7.0 for 80–90 min, and this was accompanied by reactivation of the glycolytic enzymes. On the other hand, these impairments were not observed in S. mutans cells exposed to prolonged acidification. These results indicate that the low pH frequently occurring in dental plaque may transiently impair streptococcal glycolysis and growth and that S. mutans is more durable to the acidification than S. sanguis.
Association of salivary immunoglobulin A antibody and initial mutans streptococcal infection
Authors: Smith D. J. , King W. F. , Akita H. , Taubman M. A.
Published: December 2007

We explored the relationship between mutans streptococcal infection and the development of salivary IgA antibody during initial colonization. Repetitive swabbing (n= 292) of the teeth of 33 children revealed that 45% became infected with mutans streptococci between 13 and 36 months of age. In contrast, mutans streptococci could not be detected in 18 children whose last sample was taken at 39–81 months of age (median age=62 months). During the period of mutans streptococcal infectivity, immunoglobulin A (IgA) antibody to several mutans streptococcal antigens appeared in most children, whether or not infection had been demonstrated. Robust responses to mutans streptococcal components occurred during or shortly after, but not before the period of mutans streptococcal infectivity. No consistent differences were observed among the summarized patterns of response of infected and uninfected groups of children, although the IgA Western blot patterns of individual subjects were often quite distinct. For example, sets of siblings, who would be presumed to be challenged with similar maternal mutans streptococcal clonotypes, were shown to develop qualitatively different salivary IgA responses to mutans streptococcal components. These results support a discrete period for mutans streptococcal infection and may suggest that the level of maternal infection is a factor in the success of infection of the child during this period. The data also suggest that exposure to mutans streptococci is a sufficient condition for robust mucosal IgA responses to mutans streptococcal antigens during the period of infectivity and that these responses may be different, even among siblings.
Incidence of mutans streptococci and lactobacilli in oral cleft children wearing acrylic plates from shortly after birth
Authors: van Loveren C. , Buijs J. F. , Bokhout B. , Prahl‐Andersen B. , Cate J. M. Ten
Published: December 2007

Children with a palatal cleft can be treated with preoperative infant orthopedics including an acrylic plate that is applied shortly after birth to obturate the cleft. It is advised to wear these plates until the 18th month of age. Such a plate, being a hard non‐shedding surface, may be expected to facilitate early colonization of mutans streptococci. The first aim of the present investigation was to assess the incidence of mutans streptococci and lactobacilli in children with cleft lip and/ or palate during the first 2 years of life. The second aim was to study whether preoperative orthopedics, that is, the wearing of an acrylic plate, had facilitated the establishment of mutans streptococci and lactobacilli. The third aim was to determine other factors associated with colonization of these organisms in these children. Sixty‐two Caucasian Dutch children with cleft lip and/or palate participated in this study. Twenty‐four of these children were treated with preoperative infant orthopedics and had been wearing an acrylic plate from within a few days after birth. At regular control visits plaque and saliva samples and samples from the surface of the acrylic plate were taken, while a dental examination was performed to document the emergence of the primary teeth, caries status, gingival condition and oral hygiene procedures. Saliva samples were also taken from the accompanying parents. At the visit at the age of 18 months, the parents were interviewed using a structured questionnaire. At this age, the prevalence of mutans streptococci and lactobacilli was compared to that in a control group of non‐cleft children. The oral cleft children wearing an acrylic plate from shortly after birth were colonized earlier with mutans streptococci and lactobacilli than the non‐plate oral cleft children. In the children wearing acrylic plates, the prevalence of lactobacilli decreased with age, while the prevalence of mutans streptococci increased. At the age of 18 months the prevalence of mutans streptococci was comparable in both groups of oral cleft children and in the control children. There was no relation between the numbers of mutans streptococci in the saliva of the mothers and their children. The presence of mutans streptococci in the saliva of the oral cleft children was significantly associated with between‐meal snacking and with the presence of lactobacilli.
Acid‐regulated proteins induced by Streptococcus mutans and other oral bacteria during acid shock
Authors: Hamilton I. R. , Svensäter G.
Published: December 2007

Our previous research has demonstrated that with the more aciduric oral bacteria, an acid shock to sub‐lethal pH values results in the induction of an acid tolerance response that protects the cells at extremely low pH (pH 3.0–4.0) that kills unadapted control cells maintained at pH 7.5 (Oral Microbiol Immunol 1997: 12: 266–273). In this study, we were interested in comparing the protein profiles of acid‐shocked and control cells of nine organisms from three acid‐ogenic genera that could be categorized as strong, weak and non‐acid responders in an attempt to identify proteins that could be classified as acid‐regulated proteins and which may be important in the process of survival at very low pH. For this, log‐phase cultures were rapidly acidified from pH 7.5 to 5.5 in the presence of [14C]‐amino acids for varying periods up to 2 h, the period previously shown to be required for maximum induction of the acid response. The cells were extracted for total protein and subjected to one‐dimensional sodium dodecyl sulfate‐poly‐acrylamide chromatography with comparable control and acid‐shocked protein profiles compared by scanning and computer analysis. Of particular interest were the proteins in the acid‐shocked cells that showed enhanced labeling (i.e., synthesis) over the control cells, since these were considered acid‐regulated proteins of importance in pH homeostasis. Streptococcus mutans LT11 generated the most rapid and complex pattern: a total of 36 acid‐regulated proteins showing enhanced synthesis, with 25 appearing within the first 30 min of acid shock. The enhanced synthesis was transient with all proteins, with the exception of two with molecular weights of 50/49 and 33/32 kDa. Within the acid‐regulated proteins were proteins having molecular weights comparable to the heat shock proteins and the various subunits of the membrane H+/ATPase. By comparison, the strong responder, Lactobacillus casei 151, showed the enhanced formation of only nine proteins within the first 30 min of the acid shock, with a total of 11 acid‐regulated proteins formed during the 2‐h adaptation period with enhanced synthesis transient for seven of these proteins. Streptococcus salivarius AT2 and Streptococcus gordonii TH12 had the formation of 6 and 8 proteins enhanced, while the weakly responding organisms, Streptococcus sanguis ATCC 10556 and Streptococcus oralis ATCC 10557, exhibited 8 and 6 such proteins, respectively. Even non‐responding strains unable to survive at very low pH, such as Streptococcus sobrinus CH125/43, Streptococcus mitis ATCC 12261 and Actinomyces naeslundii 301‐13 showed the initial formation of 3–9 acid‐regulated proteins, but protein synthesis was not sustained over the entire adaptation period. Clearly, the survival of oral bacteria at very low pH is related, not to the total number of the acid‐regulated proteins induced per se but to the formation of key proteins that function to augment normal pH homeostasis.
Antimicrobial susceptibility of oral isolates of Enterobacter cloacae and Klebsiella pneumoniae from a southern Chinese population
Authors: Sedgley C. M. , Samaranayake L. P.
Published: December 2007

The antibiotic susceptibilities of 59 Enterobacter cloacae and 39 Klebsiella pneumoniae human oral isolates collected from a southern Chinese population in Hong Kong were investigated for their susceptibility to eight antibiotics: ampicillin, cephalothin, cefuroxime, ceftazidime, ciprofloxacin, gentamicin, tetracycline and trimethoprim/sulfamethoxazole using the E‐Test method for direct quantification of minimum inhibitory concentrations. Most strains were sensitive to all antibiotics except ampicillin and cephalothin. Ampicillin resistance was exhibited by 82% of K. pneumoniae and 69% of E. cloacae isolates. Eighty‐eight percent of E. cloacae isolates were resistant to cephalothin. Several strains fell within the intermediate category of sensitivity for ampicillin (E. cloacae and K. pneumoniae), cefuroxime (E. cloacae) and tetracycline (K. pneumoniae). Comparison with other Hong Kong data suggests that resistance rates to cefuroxime, ceftazidime, ciprofloxacin, gentamicin, tetracycline and trimethoprim/sulfamethoxazole exhibited by the oral isolates are generally lower than in enterobacters and Klebsiella spp. isolated from urine, skin and soft tissues in Hong Kong populations.
Identification of hemolytic activity in Prevotella intermedia
Authors: Beem J. E. , Nesbitt W. E. , Leung K.‐P.
Published: December 2007

Hemolysin production was measured in strains of Prevotella intermedia. Zones of beta‐hemolysis were detected on agar plates supplemented with either sheep, rabbit or human erythrocytes. A standard tube assay was performed on cell suspensions of the organism to measure hemolytic activity, which was found to be dose dependent, eliminated by heat treatment, and saturable with increasing concentrations of blood. Growth‐phase experiments suggested that hemolysin production was increased during logarithmic growth and was reduced during stationary phase. Cell fractionation, performed on several strains of P. intermedia, localized the activity in the outer membrane and in cell vesicles. The biological implication of this study is that P. intermedia, by virtue of its hemolytic activity, is capable of liberating the hemoglobin from erythrocytes, thereby acquiring an essential nutrient, iron, for its metabolism.
Seismic Protection of Unreinforced Masonry and Adobe Low‐cost Housing in Less Developed Countries: Policy Issues and Design Criteria*
Authors: Razani Reza
Published: December 2007

In this paper the magnitude of death caused by the seismic collapse of low‐rise unreinforced masonry and adobe buildings is discussed. The small amount of research efforts spent on the seismic study of these types of buildings is found to be not proportionate to the high level of human loss caused by their destruction. The causes of the popularity and abundance of this type of construction in less developed countries (LDCS) are discussed. It is shown that this type of construction will continue to be the major type of construction for low cost housing in most LDCs for many decades to come. The causes of roof collapse of these buildings under earthquake action are described. It is concluded that the use of advanced high technology and costly methods for earthquake strengthening of masonry buildings are not feasible or easily implementable in most LDCs. The need for development of a suitable earthquake protection policy and design criteria for unreinforced masonry and adobe low‐cost housing (UMALCH) in LDCs is discussed and some findings are presented. Some principles and methods for designing UMALCH to resist seismic collapse are discussed. Also, some low‐cost methods for reduction of earthquake damage to UMALCH are given. The scope of research and development needs in the areas of improving the mechanical properties of low‐cost construction materials, developing a low‐cost light weight roofing system, and in improving the design methods for this type of construction are described.
PRACTICAL EVALUATION OF A PILOT IMMUNIZATION CAMPAIGN AGAINST TYPHOID FEVER IN A CAMBODIAN REFUGEE CAMP
Authors: Bollag Ueli
Published: December 2007

An epidemic outbreak of typhoid fever in the largest refugee camp of the besieged capital of Phom‐Penh, Cambodia; the concomitant lack of personal and public hygiene and the availability of a locally manufactured Tetanus‐Typhoid‐Paratyphoid vaccine, prompted us to test the practicability of a mass immunization campaign by carrying out a trial in the smaller, well delineated refugee camp of Pochentong. Attendances by adults as well as children throughout the three or four inoculation rounds showed a steady decline with only 30 (20%) of the people completing the course. The general initial acceptance by the people on the other hand was good, due to a comprehensive service (information, health education and individual care of patients). It is concluded from these results that multi‐injection immunization campaigns against typhoid‐paratyphoid are a waste of money in a war‐torn situation with an unstable population.
6.12. Insect pest control in refugee camps
Authors: Murlis John , Stephenson Rob
Published: December 2007

This paper is intended as a practical guide to help camp administrators with insect pest control problems. It has been neccessary to mention certain types of proprietary chemicals by name as examples of the types of compound available for various control purposes. Similarly, it has been necessary to include the names of certain items of equipment. However, the inclusion of a compound or item should not be regarded as a recommendation that this is the best, or only, one available for the particular purpose described.