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Biomedical subjects

T Ikemi

Publications and source records attributed to T Ikemi.

At least 19 recordsLinked to original sources
PubMed2003

Production of monoclonal antibody inhibiting dipeptidylaminopeptidase IV activity of Porphyromonas gingivalis.

Porphyromonas gingivalis is a Gram-negative anaerobic bacterial species implicated as an important pathogen in the development of adult periodontitis. We previously cloned a gene encoding dipeptydilaminopeptidase IV (DAPIV) from P. gingivalis. In the present study, for immunological diagnosis and development of passive immunization, we produced a mouse monoclonal antibody (MAb) capable of inhibiting the DAPIV activity of P. gingivalis using highly purified recombinant DAPIV as an immunogen. The constructed MAb, designated as MAb-Pg-DAP-1, significantly inhibited DAPIV activity in P. gingivalis, as well as slightly inhibited that in other gram-negative bacteria such as Porphyromonas endodontalis and Prevotella loesheii, whereas no inhibition was seen in the gram-positive bacteria Streptococcus mutans and Actinomyces viscosus. Furthermore, the MAb did not inhibit DAPIV enzyme activity in human serum. This novel MAb may be useful for the development of immunological diagnosis capability and in passive immunization.

Amino Acid Sequence↗
PubMed2001

Isolation and characterisation of dipeptidyl peptidase IV from Prevotella loescheii ATCC 15930.

A proline-specific dipeptidyl aminopeptidase, dipeptidyl peptidase IV (EC 3.4.14.5), was purified from a cell sonicate soluble fraction of Prevotella loescheii ATCC 15930 by sequential column chromatography. The molecular mass of the native enzyme was estimated as 160 kDa by high-pressure liquid gel filtration column chromatography and unheated sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). The subunit molecular mass was 80 kDa when the enzyme was heated to 100 degrees C in the presence of 2-mercaptoethanol before SDS-PAGE, suggesting that the native enzyme consists of two identical subunits and is folded in 2% SDS. The optimum pH, with glycyl-prolyl-4-methyl-coumaryl-7-amide as the substrate, was 8.0; the isoelectric point was 5.2. Purified enzyme showed a strong preference for dipeptide substrates containing proline and, less efficiently, alanine in the P1 position. The enzyme was markedly inhibited by Cd(2+), Zn(2+), Hg(2+), Co(2+), and serine proteinase inhibitor di-isopropylfluorophosphate.

Alanine↗
PubMed1998

Effects of surfactants on glucosyltransferase production and in vitro sucrose-dependent colonization by Streptococcus mutans.

The presence of Tween 80 in media was associated with a significant increase in three glucosyltransferases(GTFs)(I, SI and S), especially GTF-I, produced by Streptococcus mutans strain PS14, indicating that the surfactant is a major cause of the enhanced GTF production observed in cultures in M4 medium. Lecithin and Tween 20 also enhanced GTF-I production, while Triton X-100 depressed it. At a lot concentration of 0.00125%, Tween 80 enhanced markedly only GTF-I production and its effect reached maximum at a concentration of 0.0025%. Water-insoluble glucan synthesis and artificial plaque formation (in vitro sucrose-dependent colonization) by PS14 were significantly enhanced by the addition of Tween 80 at concentrations over 0.00125%. These results suggest that surfactants might vary the cariogenic potential of Strep. mutans even at low concentrations.

Bacterial Adhesion↗
PubMed1998

Rapid isolation of chromosomal DNA from oral streptococci and polymerase chain reaction-oriented restriction fragment-length polymorphism analysis for genetic heterogeneity.

We have extensively modified the published method for the lysis of gram-positive bacteria to isolate chromosomal DNA from only 1 ml of oral streptococcal overnight culture. Cells were incubated with lysozyme and R Nase A in the presence of polyethylene glycol. After centrifugation, cells were lysed with sodium dodecyl sulfate and proteinase K. Following ethanol precipitation, sodium dodecyl sulfate solution was added to the residue, and the pellet was completely dispersed by incubating at 65 degrees C. The chromosome was purified by extraction over phenol and chloroform. Two regions corresponding to the ribosomal RNA (rrn) operon and the glucosyltransferase gene were amplified using the chromosome from Streptococcus mutans and Streptococcus sobrinus by polymerase chain reaction (PCR). Genetic heterogeneity was assessed by restriction fragment-length polymorphism (PCR-RFLP). The PCR-RFLP analysis readily allowed us to subtype each strain, suggesting that the strategy presented here will provide a useful tool to verify epidemiological studies at the molecular level.

Base Sequence↗
PubMed1996

Evaluation of three individual glucosyltransferases produced by Streptococcus mutans using monoclonal antibodies.

We previously established murine hybridomas producing a monoclonal antibody monospecific against three glucosyltransferases (I, SI and S) of Streptococcus mutans which contribute to dental caries formation. Here, we developed a new immunochemical technique (cross-dot system) with which individual levels of glucosyltransferases expressed by S. mutans can be evaluated. We also examined glucosyltransferase production and in vitro artificial plaque formation by a reference strain and several clinical isolates of S. mutans. The findings indicate that the levels of glucosyltransferases produced greatly vary with the cells and the culture medium, and that the cells producing high levels of both glucosyltransferase-SI and glucosyltransferase-I enzymes may possess high in vitro artificial plaque forming ability. We suggest that the cross-dot system will be useful for estimating the cariogenic potential of S. mutans isolates.

Antibodies, Monoclonal↗
PubMed1994

Effects of lining materials on the composite resins shrinkage stresses.

Recently, three types of lining materials have been used in dental clinics, conventional powder-liquid glass ionomer cement, light-cured powder-liquid glass ionomer cement and a light-cured single paste type. This study compared the effects of these lining materials on the shrinkage stress of light-cured composite resins during the early setting stage, when polymerization shrinkage occurs. After the second irradiation, the shrinkage stress of composite resins lined with light-cured powder-liquid type cements was approximately 1.0 to 2.2 MPa when the lining application was 1.5 mm and 0.5 mm thick, respectively, demonstrating that a thicker lining application decreased shrinkage stress. The single paste type was only slightly effective in reducing shrinkage stress in composite resins. Although the sample lined with conventional powder-liquid type showed that stresses were less affected by the thickness of the lining, and had the lowest shrinkage stress of all conditions tested, greater exfoliation from the composite resin or the cavity occurred compared to that occurring with other materials.

Acrylic Resins↗
PubMed1988

Abrasion biopsy in studies of mineral density of experimental enamel lesions.

The profile of mineral density of experimental enamel lesions was determined by means of sampling with a new abrasion biopsy technique. Three types of lesions were produced on bovine enamel slabs: (1) pre-softened in lactic acid buffer for 16 hr; (2) pre-softened and exposed to a test for acid resistance for seven days; and (3) pre-softened, exposed to the seven-day Intra-oral Cariogenicity Test with extra-oral immersions in 1000 ppm F solutions for one min twice daily (ICT/F), plus the seven-day test for acid resistance. Lesions were assessed with measurements of surface microhardness, microradiography of thin sections, and abrasion biopsy. For abrasion biopsy of the experimental lesions, 15 parallel layers of approximately 10 microns each were abraded simultaneously with reference slabs of sound enamel on strips of lapping film. The depth of abrasion for each sample was calculated from the phosphorus content of the reference sample. Exposure to the ICT/F formed an acid-resistant zone within the lesion which diminished the microhardness change, although it did not have an appreciable effect on the total lesion depth as assessed with microradiography; abrasion biopsy indicated the formation of a mineral-dense zone within the lesion. This recently-developed technique of abrasion biopsy of experimental lesions offers the opportunity to link the composition of the lesion to controlled experimental conditions which will improve our understanding of demineralizing and remineralizing reactions on a standard tooth substrate.

Animals↗