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Biomedical subjects

D Kato

Publications and source records attributed to D Kato.

At least 19 recordsLinked to original sources
PubMed2001

Reduced fimbria-associated activities of Porphyromonas gingivalis induced by recombinant fimbrial expression.

The adhesion properties of the recombinant fimbriae (r-fimbriae) recovered from a YH522 transformant of Porphyromonas gingivalis which harbors a chimeric plasmid, pYHF2, containing the fimA gene of strain 381 were compared with those of the endogenous fimA fimbriae of strain 33277. The adhesion level of the r-fimbriae to Actinomyces viscosus was clearly lower than that of the endogenous fimbriae. In addition, the r-fimbriae were shown to lack some minor components detectable in the endogenous fimbriae. The plasmid pYHF2 prepared from the YH522 transformant was then transformed into six different P. gingivalis strains and the resultant pYHF2-containing strains were examined for their fimbrial expression. In spite of the presence of a considerable diversity in the expression level of the r-fimbriae among these transformants, it was evident that the strains expressing higher levels of the r-fimbriae exhibited a greater decrease in adhesion activity to other bacteria and to oral epithelial cells, as well as in self-aggregation.

Actinomyces viscosus↗
PubMed2000

Automatic control of a robot camera for broadcasting based on cameramen's techniques and subjective evaluation and analysis of reproduced images.

With the goal of achieving an intelligent robot camera system that can take dynamic images automatically through humanlike, natural camera work, we analyzed how images were shot, subjectively evaluated reproduced images, and examined effects of camerawork, using camera control technique as a parameter. It was found that (1) A high evaluation is obtained when human-based data are used for the position adjusting velocity curve of the target; (2) Evaluation scores are relatively high for images taken with feedback-feedforward camera control method for target movement in one direction; (3) Keeping the target within the image area using the control method that imitates human camera handling becomes increasingly difficult when the target changes both direction and velocity and becomes bigger and faster, and (4) The mechanical feedback method can cope with rapid changes in the target's direction and velocity, constantly keeping the target within the image area, though the viewer finds the image rather mechanical as opposed to humanlike.

Algorithms↗
PubMed1999

BPD-MA-mediated photosensitization in vitro and in vivo: cellular adhesion and beta1 integrin expression in ovarian cancer cells.

Benzoporphyrin derivative monoacid (BPD-MA) photosensitization was examined for its effects on cellular adhesion of a human ovarian cancer cell line, OVCAR 3, to extracellular matrix (ECM) components. Mild BPD-MA photosensitization (approximately 85% cell survival) of OVCAR 3 transiently decreased adhesion to collagen IV, fibronectin, laminin and vitronectin to a greater extent than could be attributed to cell death. The loss in adhesiveness was accompanied by a loss of beta1 integrin-containing focal adhesion plaques (FAPs), although beta1 subunits were still recognized by monoclonal antibody directed against human beta1 subunits. In vivo BPD-MA photosensitization decreased OVCAR 3 adhesiveness as well. Photosensitized adhesion was reduced in the presence of sodium azide and enhanced in deuterium oxide, suggesting mediation by singlet oxygen. Co-localization studies of BPD-MA and Rhodamine 123 showed that the photosensitizer was largely mitochondrial, but also exhibited extramitochondrial, intracellullar, diffuse cytosolic fluorescence. Taken together, these data show that intracellular damage mediated by BPD-PDT remote from the FAP site can affect cellular-ECM interactions and result in loss of FAP formation. This may have an impact on long-term effects of photodynamic therapy. The topic merits further investigation.

Animals↗
PubMed1999

Growth inhibition of A549 human lung adenocarcinoma cells by L-canavanine is associated with p21/WAF1 induction.

L-Canavanine (CAV) is a higher plant nonprotein amino acid and a potent L-arginine antimetabolite. CAV can inhibit the proliferation of tumor cells in vitro and in vivo, but little is known regarding the molecular mechanisms mediating these effects. We demonstrated that the treatment of human lung adenocarcinoma A549 cells with CAV caused growth inhibition; G1 phase arrest is accompanied by accumulation of an incompletely phosphorylated form of the retinoblastoma protein, whose phosphorylation is necessary for cell cycle progression from G1 to S phase. In addition, CAV induces the expression of p53 and subsequent expression of a cyclin-dependent kinase inhibitor, p21/WAF1. The p53-dependent induction of p21/WAF1 and the following dephosphorylation of the retinoblastoma protein by CAV could account for the observed CAV-mediated G1 phase arrest.

Adenocarcinoma↗
PubMed1999

Transformation and expression of a cloned fimA gene in Porphyromonas gingivalis.

The Porphyromonas gingivalis fimbria is an important virulence factor involved in the adherence and colonization of the organism in the oral cavity. In this study, we transformed this organism with a gene, fimA381, encoding the fimbrial subunit of P. gingivalis 381 (fimbrillin) by using the host-vector system that we developed previously and examined expression of the cloned fimA381 gene. The recombinant plasmid pYHF2 was constructed by ligating a fragment containing the fimA381 gene into the plasmid vector pYH420 and transformed into the restriction-deficient P. gingivalis host YH522. pYHF2 was autonomously maintained in YH522 cells, and the fimbrillin polypeptide (recombinant fimbrillin) was fully expressed. The molecular mass of the recombinant fimbrillin was evaluated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis as 41 kDa, which was identical to that of the native fimbrillin of strain 381. The amino acid sequences of the 20 amino-terminal residues of the recombinant fimbrillin and the native fimbrillin of the strain 381 were identical. In addition, characteristic long and thin fimbrial structures (recombinant fimbriae) that were distinguishable from the host's native fimbriae when examined by immunogold electron microscopy were observed around the cell surface of the transformants containing the fimA381 gene. These results suggested that transformation of fimA gene from a different strain of P. gingivalis followed by accumulation of the mature fimbrial subunit protein was sufficient for production of fimbrial structures that were observable by electron microscopy.

Bacterial Proteins↗
PubMed1998

Features of replicative senescence induced by direct addition of antennapedia-p16INK4A fusion protein to human diploid fibroblasts.

The p16INK4A cyclin-dependent kinase (Cdk) inhibitor is now recognized as a major tumor suppressor that is inactivated by a variety of mechanisms in a wide range of human cancers. It is also implicated in the mechanisms underlying replicative senescence since p16INK4A RNA and protein accumulate as cells approach their proscribed limit of population doublings in tissue culture. To obtain further evidence of its role in senescence, we have sought ways of overexpressing p16INK4A in primary human diploid fibroblasts (HDF). To circumvent the low transfection efficiency of primary cells we have exploited a recombinant form of the full-length p16INK4A protein fused to a 16 amino acid peptide from the Drosophila antennapedia protein. This peptide has the capacity to cross both cytoplasmic and nuclear membranes allowing the direct introduction of the active protein to primary cells. Here, we show that antennapedia-tagged wild-type p16INK4A protein, but not a functionally compromised tumor-specific variant, causes G1 arrest in early passage HDFs by inhibiting the phosphorylation of the retinoblastoma protein. Significantly, the arrested cells display several phenotypic features that are considered characteristic of senescent cells. These data support a role for p16INK4A in replicative senescence and raise the possibility of using the antennapedia-tagged protein therapeutically.

Antennapedia Homeodomain Protein↗
PubMed1998

[In vitro susceptibilities of clinical isolates of coagulase-negative staphylococci to glycopeptide antibiotics].

Two hundred and thirteen clinical strains of coagulase-negative staphylococci isolated in Japan between 1980 and 1997 were analyzed for glycopeptide susceptibility by determining MIC using both Mueller-Hinton agar (MHA) and Brain Heart Infusion agar (BHIA) plates. Of 37 Staphylococcus epidermidis strains isolated between 1980 and 1981, all were susceptible to vancomycin and teicoplanin on both MHA and BHIA. However, of 122 isolates of Staphylococcus epidermidis isolated between 1994 and 1997, 1 (0.8%) was intermediate to vancomycin on MHA and 39 (32%) were intermediate on BHIA, while 3 (2.5%) and 27 (22.1%) were intermediate or resistant to teicoplanin on MHA and BHIA, respectively. It was demonstrated that the susceptibilities of the strains in 1990s to vancomycin and teicoplanin were significantly decreased compared with those in 1980s. Population analysis was performed with six strains each of Staphylococcus epidermidis and Staphylococcus haemolyticus (three with vancomycin MIC > or = 8 micrograms/ml and three with vancomycin MIC < or = 4 micrograms/ml using BHIA). The population curves of the Staphylococcus epidermidis strains showed a homogeneous pattern of susceptibility. Whereas, those for two Staphylococcus haemolyticus strains (vancomycin MIC = 8 micrograms/ml using BHIA) showed a typical heterogeneous pattern. Vancomycin-resistant mutants (MIC > or = 32 micrograms/ml) were obtained with a high frequency of 10(-4)-(-5) from the strains by one-step selection with 16 micrograms/ml of vancomycin.

Anti-Bacterial Agents↗
PubMed1997

Retinoblastoma binding factor 1 site in the core promoter region of the human RB gene is activated by hGABP/E4TF1.

We previously reported two oncogenic point mutations present in the RB (retinoblastoma) gene promoter region, found at consensus Sp1 and ATF sites, respectively, and in two separate hereditary RB families. However, Sp1 protein was shown not to bind to the Sp1 site; this indicated that the Sp1 consensus site mutation was blocking the action of an alternative transcription factor, which we called RBF-1 (retinoblastoma binding factor 1). Subsequent purification of RBF-1 revealed it to be hGABP/E4TF1, a transactivator from the adenovirus early-region 4 promoter. In this study, we directly examined the effects of hGABP/E4TF1 on transactivation of the RB gene promoter through the RBF-1 site. As expected, hGABP/E4TF1 enhanced the core RB promoter activity, whereas it did not stimulate a mutant RBF-1 site. We therefore conclude that the most essential transcription factor in the human RB gene is likely to be hGABP/E4TF1.

Animals↗
PubMed1997

Construction of a plasmid vector for transformation of Porphyromonas gingivalis.

A host-vector system for transformation of Porphyromonas gingivalis was constructed using a set (1) strains that can incorporate plasmid DNA by electroporation regardless of its source and (2) stable vector plasmids with a selectable marker. First, restriction-negative mutants were isolated, because P. gingivalis possesses restriction modification systems by which DNA introduced by transformation even from heterologous strains of the same species is excluded. For screening of the mutants, plasmid pE5-2 was employed since it could be transconjugated (mobilized) to P. gingivalis from Escherichia coli and is able to replicate in this species, albeit not stably. pE5-2 DNA prepared from E coli was introduced by electroporation into chemically mutagenized P. gingivalis cells. By this method, three putative restriction-negative clones were selected. These strains exhibited a capacity for electroporation with plasmid DNAs both from E. coli and from various P. gingivalis strains at a similar efficiency. Using one of the derivatives thus obtained, YH522, we then screened for plasmids that could replicate stably in P. gingivalis. Since no plasmids were found from P. gingivalis, cryptic plasmids from other species of black-pigmented oral anaerobic rods were examined for their ability to transform P. gingivalis. A series of plasmids constructed by ligation with pBR322 for replication in E. coli and the EcoRI-B fragment from pBF4 containing erythromycin resistance were prepared from E. coli and were used for electroporation of P. gingivalis. Among these, a recombinant plasmid containing the replicon of pYHBA1 from Porphyromonas asaccharolytica, designated pYH400, was found to be incorporated into the restriction-negative P. gingivalis strain and replicated stably. This set of recipient strains and stable plasmids with a selectable marker constitutes the first practical host-vector system for this species.

Cloning, Molecular↗
PubMed1996

Intraperitoneal photodynamic therapy of human epithelial ovarian carcinomatosis in a xenograft murine model.

The objective of this investigation was to determine the efficacy of i.p. photodynamic therapy (PDT) against solid, multifocal ovarian carcinoma using a newly described NIH:OVCAR-5 induced murine model. PDT was initiated when diffuse microscopic disease and small multifocal tumor nodules were present, similar to the extent of residual carcinoma that may persist clinically after laparotomy and tumor debulking. The photosensitizer, benzoporphyrin derivative monoacid ring A (BPD-MA), was administered in a dose of 0.25 mg/kg body weight i.p. 90 min prior to light exposure. An argon-pumped dye laser was used to deliver low intensity light (20 J) i.p. through a cylindrically diffusing fiberoptic tip. Treatment regimens consisted of a series of three to five treatments at 3-7 day intervals, with the extent of macroscopic disease or death from disease being the evaluable outcome parameters for tumoricidal and survival studies, respectively. The mean tumor burden at necropsy for treated animals was 0.034 +/- 0.014 g compared to 0.379 +/- 0.065 g in untreated controls (P<0.001). Survival studies were initiated in two groups at day 7 and day 14 following cell inoculation. The first group received either three or five treatments at 5-day intervals, and both had a significant increase in median survival compared to untreated controls (57 and 53 days, respectively, compared to 43 days, P<0.05). The second group was treated every 7 days until death and also had a significant survival advantage over controls (57 days compared to 47 days, P<0.05). These studies suggest that benzoporphyrin derivative mono acid ring A-mediated PDT is a feasible, well-tolerated, experimental treatment approach that elicits a tumoricidal response against diffuse, solid i.p. disease in tumor-bearing mice, with concomitant prolongation of survival and needs careful optimization.

Animals↗
PubMed1994

Uterine papillary serous carcinoma: patterns of metastatic spread.

Uterine papillary serous carcinoma (UPSC) is a distinct histologic type of endometrial cancer which is associated with a high relapse rate and poor prognosis. Between 1983 and 1993, 50 patients with UPSC of the endometrium were surgically staged. Thirty-three patients had pure UPSC and 17 had UPSC admixed with other histologies. Extrauterine disease was found in 36 women (72%). Lymph node metastases were present in 36% of women without myometrial invasion, 50% with inner one-half invasion, and 40% with outer one-half invasion. Similarly, the presence of intraperitoneal disease or positive washings did not correlate with increasing myometrial invasion. Grade and histology (mixed vs pure) were also not predictive of extrauterine disease. Patients with lymphatic/vascular space invasion (LVSI) were more likely to have extrauterine disease (85%); however, even without LVSI the incidence of extrauterine disease was 58% (P = 0.05). Unlike endometrioid adenocarcinomas, grade and depth of myometrial invasion were not significant predictors for extrauterine disease. This study reinforces the need for complete surgical staging in all patients with UPSC regardless of depth of invasion.

Aged↗