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T Oho

Publications and source records attributed to T Oho.

At least 19 recordsLinked to original sources
PubMed2006

Serotype-specific polysaccharide of Streptococcus mutans contributes to infectivity in endocarditis.

Streptococcus mutans and other viridans streptococci have been implicated as major etiological agents of infective endocarditis. The serotype-specific rhamnose-glucose polysaccharide (RGP) of S. mutans has several biological functions that appear to be essential for the induction of infective endocarditis. The aim of this study was to examine the contribution of RGP to the infectivity of S. mutans in infective endocarditis using a rat model. The RGP-defective mutant of S. mutans showed reduced ability to induce infective endocarditis compared to the parental strain. The ability of S. mutans to induce infective endocarditis was not consistent with the binding capacity of the organism to extracellular matrix proteins. The results suggest that S. mutans containing whole RGP is more virulent than the RGP-defective mutant, and the RGP has an important role for the induction of infective endocarditis by S. mutans.

Animals↗
PubMed2004

TaqMan real-time polymerase chain reaction assay for the correlation of Treponema denticola numbers with the severity of periodontal disease.

Treponema denticola has been implicated in periodontitis, and the presence of this organism in periodontal pockets has been investigated. However, qualitative analysis is insufficient for the clinical evaluation of periodontal treatments, and quantification of T. denticola populations is essential for monitoring therapeutic efficacy. Therefore, we developed a quantitative method for T. denticola that uses the TaqMan real-time polymerase chain reaction assay. Using this system, we evaluated the relative and absolute numbers of this organism in saliva and subgingival plaque. Furthermore, we analyzed the relationship between the numbers of T. denticola and pocket depth, and found a significant positive correlation (P < 0.0001) between these parameters. This report demonstrates the broad potential of real-time polymerase chain reaction applications in periodontology.

Adult↗
PubMed2004

Prevalence of Porphyromonas gingivalis in relation to periodontal status assessed by real-time PCR.

Many studies have examined the presence of Porphyromonas gingivalis in periodontal pockets. However, monitoring the number of bacterial cells is difficult. In this study, we performed quantitative analyses of P. gingivalis to clarify the relationship between the numbers of this organism and periodontal status. Using the TaqMan real-time PCR system, we found a significant positive correlation (P < 0.0001) between the number of P. gingivalis and pocket depth. The slope of the regression line indicated that for every 1-mm increase in pocket depth, the number of P. gingivalis increased 10- fold. There was also a significant reduction (P < 0.01) in the numbers of P. gingivalis before and after treatment. These results suggest that the absolute and relative numbers of P. gingivalis are closely associated with periodontal status, and that quantitative analysis of this organism is important for the evaluation of periodontal therapy.

Adult↗
PubMed2001

Inhibitory effect of bovine milk lactoferrin on the interaction between a streptococcal surface protein antigen and human salivary agglutinin.

Human whole saliva induces aggregation of Streptococcus mutans cells via an interaction between a surface protein antigen (PAc) of the organism and salivary agglutinin. Bovine milk inhibits the saliva-induced aggregation of S. mutans. In this study, the milk component that possesses inhibitory activity against this aggregation was isolated and found to be lactoferrin. Surface plasmon resonance analysis indicated that bovine lactoferrin binds more strongly to salivary agglutinin, especially to high molecular mass glycoprotein, which is a component of the agglutinin, than to recombinant PAc. The binding of bovine lactoferrin to salivary agglutinin was thermostable, and the optimal pH for binding was 4.0. To identify the saliva-binding region of bovine lactoferrin, 11 truncated bovine lactoferrin fragments were constructed. A fragment corresponding to the C-terminal half of the lactoferrin molecule had a strong inhibitory effect on the saliva-induced aggregation of S. mutans, whereas a fragment corresponding to the N-terminal half had a weak inhibitory effect. Seven shorter fragments corresponding to lactoferrin residues 473-538 also showed a high ability to inhibit the aggregation of S. mutans. These results suggest that residues 473-538 of bovine lactoferrin are important in the inhibition of saliva-induced aggregation of S. mutans.

Agglutinins↗
PubMed2001

Psychological condition of patients complaining of halitosis.

OBJECTIVES: The purpose of this study was to examine the relationship between the actual degree of malodor and the psychological condition of patients complaining of halitosis. METHODS: The subjects consisted of 155 patients aged 46+/-17 years (mean+/-SD) who visited the Halitosis Clinic at Kyushu University Dental Hospital, Fukuoka, Japan. The Cornell Medical Index (CMI) Health Questionnaire was used to evaluate the psychological condition of patients. The degree of halitosis was estimated by the organoleptic test. RESULTS: Fifty-five percent of the patients had no or slight odor. Patients with a lower degree of halitosis showed a stronger psychopathological profile. There was a significant correlation between the degree of halitosis and the tendency toward neurosis (Spearman's rank correlation coefficient r=-0.37, P<0.001). CONCLUSIONS: The results suggest that psychological condition is closely associated with symptoms of patients complaining of halitosis. The CMI Health Questionnaire may be a helpful tool for the diagnosis of patients who complain of halitosis.

Chi-Square Distribution↗
PubMed2001

Characteristics of patients complaining of halitosis and the usefulness of gas chromatography for diagnosing halitosis.

OBJECTIVE: The purpose of this study was to examine the characteristics of patients complaining of halitosis and to evaluate the diagnostic accuracy of 3 methods of measuring halitosis. STUDY DESIGN: The actual degree of halitosis was determined through use of an organoleptic test in 155 patients aged 46 +/- 17 years (mean +/- SD). The volatile sulfur compounds (VSCs) were determined with gas chromatography and with sulfide monitoring. RESULTS: The organoleptic test revealed that 55% of the subjects had either no mouth odor or slight mouth odor. There was a significant correlation between the organoleptic score and the total VSC level as determined through use of other methods. The critical discrimination value of the total VSC level was calculated to be 0.057 ppm for gas chromatography and 0.117 ppm for sulfide monitoring; high sensitivity and specificity were obtained when the gas chromatography value was used. The amount of tongue coating was significantly greater in the halitosis-positive group than in the halitosis-negative group, whereas there was no difference in salivary flow rate between the 2 groups. CONCLUSION: These results indicate that determining VSCs with gas chromatography is a useful means of diagnosing halitosis.

Chi-Square Distribution↗
PubMed2001

Passive immunization with milk produced from an immunized cow prevents oral recolonization by Streptococcus mutans.

Cell surface protein antigen (PAc) and water-insoluble glucan-synthesizing enzyme (GTF-I) produced by cariogenic Streptococcus mutans are two major factors implicated in the colonization of the human oral cavity by this bacterium. We examined the effect of bovine milk, produced after immunization with a fusion protein of functional domains of these proteins, on the recolonization of S. mutans. To prepare immune milk, a pregnant Holstein cow was immunized with the fusion protein PAcA-GB, a fusion of the saliva-binding alanine-rich region (PAcA) of PAc and the glucan-binding (GB) domain of GTF-I. After eight adult subjects received cetylpyridinium chloride (CPC) treatment, one subgroup (n = 4) rinsed their mouths with immune milk and a control group (n = 4) rinsed with nonimmune milk. S. mutans levels in saliva and dental plaque decreased after CPC treatment in both groups. Mouth rinsing with immune milk significantly inhibited recolonization of S. mutans in saliva and plaque. On the other hand, the numbers of S. mutans cells in saliva and plaque in the control group increased immediately after the CPC treatment and surpassed the baseline level 42 and 28 days, respectively, after the CPC treatment. The ratios of S. mutans to total streptococci in saliva and plaque in the group that received immune milk were lower than those in the control group. These results suggest that milk produced from immunized cow may be useful for controlling S. mutans in the human oral cavity.

Adult↗
PubMed2001

Immunodominant region of Actinobacillus actinomycetemcomitans 40-kilodalton heat shock protein in patients with rheumatoid arthritis.

Bacterial heat shock proteins have been implicated in the pathogenesis of several diseases, and the immunological relationship between rheumatoid arthritis (RA) and Escherichia coli DnaJ has been reported. Since there are similarities in the tissue destruction process of RA and periodontitis, we examined the reactivities of antibodies in sera from RA patients to the DnaJ protein from Actinobacillus actinomycetemcomitans. An enzyme-linked immunosorbent assay showed that IgG titers to the N-terminal conservative region of the DnaJ are significantly higher in RA patients compared with the healthy controls (p < 0.05). Furthermore, we examined IgG titers of disease controls to determine the specificity of the immune responses to this region in RA patients. The difference between RA and infectious disease patients was also significant (p < 0.05). These results suggest that the N-terminal region of DnaJ from A. actinomycetemcomitans may contribute to the etiologic analysis of RA.

Adult↗
PubMed2000

Simple and rapid detection of Streptococcus mutans and Streptococcus sobrinus in human saliva by polymerase chain reaction.

Streptococcus mutans and Streptococcus sobrinus are major pathogens causing dental caries in humans. A simple and rapid method to detect these species in human saliva simultaneously was developed using the polymerase chain reaction (PCR). Chromosomal DNA was extracted by boiling bacterial cells in lysis solution containing 1% Triton X-100. Oligonucleotide primers specific for portions of the glucosyltransferase genes (gtfB of S. mutans and gtfI of S. sobrinus) were designed. After PCR using two sets of these primers, S. mutans and S. sobrinus were specifically identified. The method was capable of amplifying DNA fragments specific for these species from chromosomal DNA extracted from 1 x 10(3) cells, or from 10 microliters of clinical saliva samples containing 1 x 10(3) colony-forming units of either streptococcal species. A second PCR, using the first PCR product as a template with newly designed internal primers, made it possible to detect 1 x 10(2) colony-forming units of either streptococcal species in 10 microliters of saliva samples. These results indicate that the PCR method developed in this study is useful for detecting S. mutans and S. sobrinus in saliva and that it can be used in epidemiological studies to evaluate the prevalence level of these organisms.

Adult↗
PubMed2000

Formation of methyl mercaptan from L-methionine by Porphyromonas gingivalis.

Methyl mercaptan production by oral bacteria is thought to be one of the main causes of oral malodor. We examined the ability of periodontopathic Porphyromonas gingivalis to produce methyl mercaptan from L-methionine and found that the invasive strains W83 and W50 produced large amounts of methyl mercaptan. We cloned and sequenced the mgl gene encoding L-methionine-alpha-deamino-gamma-mercaptomethane-lyase (METase) from P. gingivalis W83. The structural mgl gene consisted of 1,200 bp and encoded a 43.3-kDa protein. To examine the role of methyl mercaptan in the pathogenesis of P. gingivalis, a METase-deficient mutant of P. gingivalis W83 was constructed. The methionine degradation activity and virulence of the mutant (M1217) and the parent strain (W83) in mice were compared. M1217 showed a marked decrease in the formation of methyl mercaptan from L-methionine and decreased virulence compared with the wild-type strain W83. These results suggest that methyl mercaptan not only is one of the sources of oral malodor, but may also play a role in the pathogenicity of P. gingivalis.

Animals↗
PubMed2000

Role of serotype-specific polysaccharide in the resistance of Streptococcus mutans to phagocytosis by human polymorphonuclear leukocytes.

To clarify the role of cell surface components of Streptococcus mutans in resistance to phagocytosis by human polymorphonuclear leukocytes (PMNs), several isogenic mutants of S. mutans defective in cell surface components were studied with a luminol-enhanced chemiluminescence (CL) assay, a killing assay, and a transmission electron microscope. The CL responses of human PMNs to mutant Xc11 defective in a major cell surface antigen, PAc, and mutant Xc16 defective in two surface glucosyltransferases (GTF-I and GTF-SI) were the same as the response to the wild-type strain, Xc. In contrast, mutant Xc24R, which was defective in serotype c-specific polysaccharide, induced a markedly higher CL response than the other strains. The killing assay showed that human PMNs killed more Xc24R than the parent strain and the other mutants. The transmission electron microscopic observation indicated that Xc24R cells were more internalized by human PMNs than the parental strain Xc. These results may be reflected by the fact that strain Xc24R was more phagocytosed than strain Xc. The CL response of human PMNs to a mutant defective in polysaccharide serotype e or f was similar to the response to Xc24R. Furthermore, mutants defective in serotype-specific polysaccharide were markedly more hydrophobic than the wild-type strains and the other mutants, suggesting that the hydrophilic nature of polysaccharides may protect the bacterium from phagocytosis. We conclude that the serotype-specific polysaccharide, but not the cell surface proteins on the cell surface of S. mutans, may play an important role in the resistance to phagocytosis.

Antigens, Bacterial↗
PubMed1999

A novel dnaK operon from Porphyromonas gingivalis.

The nucleotide sequence of the dnaK operon cloned from Porphyromonas gingivalis revealed that the operon does not contain homologues of either dnaJ or grpE. However, there were two genes which encode small heat shock proteins immediately downstream from the dnaK and they were transcribed together with dnaK as one unit. The ATPase activity of the P. gingivalis DnaK was synergistically stimulated up to 40-fold in the simultaneous presence of Escherichia coli DnaJ and GrpE. These results suggest that the DnaK homologue of P. gingivalis, with its unique genetic structure and evolutionary features, works as a member of the DnaK chaperone system.

Adenosine Triphosphatases↗
PubMed1999

Bovine milk antibodies against cell surface protein antigen PAc-glucosyltransferase fusion protein suppress cell adhesion and alter glucan synthesis of Streptococcus mutans.

Cell surface protein antigen (PAc) and glucosyltransferases (GTF) produced by Streptococcus mutans are considered major colonization factors of the organism, and the inhibition of these factors is thought to prevent dental caries. In this study, 8-mo-old pregnant Holstein cows were immunized with fusion protein PAcA-GB, a fusion of the saliva-binding alanine-rich region (PAcA) of PAc with the glucan binding (GB) domain of GTF-I, an enzyme catalyzing the synthesis of water-insoluble glucan from sucrose. High titers of immunoglobulin antibodies specific for the fusion protein were found in normal milk after reimmunization, and they persisted for approximately 3 mo. The immunoglobulin G (IgG) antibodies against PAcA-GB were purified from immunized milk. The antibodies significantly inhibited the adhesion of S. mutans cells to saliva-coated hydroxyapatite beads. IgG antibodies purified from immunized milk also inhibited total glucan synthesis by cell-associated GTF preparation and GTF-I from S. mutans. The immunized milk may be useful as a means of passive immunization for the prevention of dental caries in humans.

Animals↗
PubMed1999

Recombination between gtfB and gtfC is required for survival of a dTDP-rhamnose synthesis-deficient mutant of Streptococcus mutans in the presence of sucrose.

The rml genes are involved in dTDP-rhamnose synthesis in Streptococcus mutans. A gene fusion between gtfB and gtfC, which both encode extracellular water-insoluble glucan-synthesizing enzymes, accompanied by inactivation of the rml genes was observed for cells grown in the presence of sucrose. The survival rates of rml mutants isolated in the absence of sucrose were drastically reduced in the presence of sucrose. The rates were consistent with the frequency of spontaneous gene fusions between gtfB and gtfC, suggesting that the spontaneous recombinant organisms were selected in the presence of sucrose. The rml mutants with a gtfB-gtfC fusion gene had markedly reduced water-insoluble glucan synthetic activity and lost the ability to colonize glass surfaces in the presence of sucrose. These results suggest that the rml mutants of S. mutans, which are defective in dTDP-rhamnose synthesis, can survive only in the absence of water-insoluble glucan synthesis.

Gene Expression Regulation, Bacterial↗
PubMed1998

Binding of salivary glycoprotein-secretory immunoglobulin A complex to the surface protein antigen of Streptococcus mutans.

The interaction between a surface protein antigen (PAc) of Streptococcus mutans and human salivary agglutinin was analyzed with a surface plasmon resonance biosensor. The major component sugars of the salivary agglutinin were galactose, fucose, mannose, N-acetylglucosamine, N-acetylgalactosamine, and N-acetylneuraminic acid. Binding of salivary agglutinin to PAc was calcium dependent and heat labile and required a pH greater than 5. Binding was significantly inhibited by N-acetylneuraminic acid and alpha2,6-linked sialic acid-specific lectin derived from Sambucus sieboldiana in a dose-dependent manner. Pretreatment of the salivary agglutinin with sialidase reduced the binding activity of the agglutinin to the PAc molecule. The agglutinin was dissociated into high-molecular-mass glycoprotein and secretory immunoglobulin A (sIgA) components by electrophoretic fractionation in the presence of 1% sodium dodecyl sulfate and 1% 2-mercaptoethanol. Neither of the components separated by electrophoretic fractionation, high-molecular-mass glycoprotein or sIgA, bound to the PAc molecule. Furthermore, the high-molecular-mass glycoprotein strongly inhibited the binding of the native salivary complex to PAc. These results suggest that the complex formed by the high-molecular-mass salivary glycoprotein and sIgA is essential for the binding reaction and that the sialic acid residues of the complex play an important role in the interaction between the agglutinin and PAc of S. mutans.

Acetylgalactosamine↗
PubMed1997

Effects of antibodies against cell surface protein antigen PAc-glucosyltransferase fusion proteins on glucan synthesis and cell adhesion of Streptococcus mutans.

Cell surface protein antigen (PAc) and glucosyltransferases (GTFs) produced by Streptococcus mutans are considered to be major colonization factors of the organism, and the inhibition of these two factors is predicted to provide protection against dental caries. In this study, we have constructed fusion protein PAcA-GB, a fusion of the saliva-binding alanine-rich region (PAcA) of PAc with the glucan binding (GB) domain of GTF-I, an enzyme catalyzing the synthesis of water-insoluble glucan from sucrose, and fusion protein PAcA-SB, a fusion of PAcA with the sucrose binding (SB) domain of GTF-I. The recombinant fusion proteins were purified from cell extracts of Escherichia coli harboring the fusion genes, and rabbit antibodies against these fusion proteins were prepared. Water-insoluble glucan synthesis by cell-associated and cell-free GTF preparations from S. mutans as well as total glucan synthesis by GTF-I was markedly inhibited by anti-PAcA-GB immunoglobulin G (IgG) antibodies but not by anti-PAcA-SB IgG antibodies. Significant inhibition of the sucrose-independent and sucrose-dependent adhesion of S. mutans to saliva-coated hydroxyapatite beads was observed when anti-PAcA-GB antibodies were added to the reaction mixture. Anti-PAcA-SB antibodies inhibited the adhesion of S. mutans to the beads in the absence of sucrose but not in the presence of sucrose. Immunization with the fusion protein PAcA-GB may be useful for controlling the colonization of teeth by S. mutans.

Animals↗
PubMed1997

Identification of a fourth gene involved in dTDP-rhamnose synthesis in Streptococcus mutans.

We had isolated three genes (rmlA, rmlB, and rmlC) involved in dTDP-rhamnose synthesis in Streptococcus mutans and found that three genes were insufficient for dTDP-rhamnose synthesis (Y. Tsukioka, Y. Yamashita, T. Oho, Y. Nakano, and T. Koga, J. Bacteriol. 179:1126-1134, 1997). The rmlD gene of S. mutans, encoding the enzyme which catalyzes the last step of dTDP-rhamnose synthesis, has been cloned and sequenced. The cell extract of Escherichia coli expressing the rmlD gene of S. mutans exhibited enzymatic activity corresponding to its counterpart in Shigella flexneri, a gram-negative bacterium. Rhamnose was not detected in the cell wall preparation purified from the mutant in which the cloned gene was insertionally inactivated. Rabbit antiserum against S. mutans serotype c-specific antigen did not react with autoclaved extracts from the mutant. The rmlD gene product of S. mutans compensated for the incompleteness of dTDP-rhamnose synthesis by the three previously isolated genes. These results indicate that the rmlD gene product is indispensable for the dTDP-rhamnose pathway and subsequently for the synthesis of serotype-specific antigen in S. mutans. Furthermore, conservation of the rmlD gene in Streptococcus species was demonstrated by Southern blot analysis.

Amino Acid Sequence↗