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S Hamada

Publications and source records attributed to S Hamada.

At least 37 records · Page 2Linked to original sources
PubMed1998

Diversity revealed by a novel family of cadherins expressed in neurons at a synaptic complex.

In mammals, neurons are highly differentiated and play distinctive functions even in the same brain region. We found a novel cadherin-related neuronal receptor (Cnr) gene family by studying Fyn-binding activity in mouse brain. CNR1 protein is located in the synaptic junction and forms a complex with Fyn. Sequence analysis of eight Cnr products of approximately 20 genes indicates that these comprise a novel cadherin family of the cadherin superfamily. The expression patterns of each member of this novel family were grossly similar to each other but restricted to subpopulations of neurons of the same type. The diversity of the Cnr family genes suggests that there are molecular mechanisms that govern highly differentiated neural networks in the mammalian CNS.

Animals↗
PubMed1998

Six Arabidopsis thaliana homologues of the human respiratory burst oxidase (gp91phox).

An NADPH oxidase analogous to that in mammalian phagocytes has been hypothesized to produce reactive oxygen species (ROS) in the plant defence response. A. thaliana contains at least six gp91phox homologues, designated AtrbohA-F (A. thaliana Respiratory Burst Oxidase Homologues), which map to different positions. Transcripts of three of these genes can be detected in healthy plants by RNA gel blot analyses. The Atrboh gene products are closely related to gp91phox and the intron locations suggest a common evolutionary origin. A putative EF-hand Ca(2+)-binding motif in the extended N-terminal region of the Atrboh proteins suggests a direct regulatory effect of Ca2+ on the activity of the NADPH oxidase in plants.

Amino Acid Sequence↗
PubMed1998

The importance of fimbriae in the virulence and ecology of some oral bacteria.

Cumulative evidence indicates that bacterial adherence to mucosal and tooth surfaces as well as bacterial coaggregation are essential steps for colonization of various oral bacterial species. Bacterial fimbriae have been shown to play an important role in the interaction between bacteria and host cells or among bacterial cells. The properties of fimbriae from selected species of oral bacteria are discussed in terms of virulence traits and ecological significance. Among others, Porphyromonas gingivalis fimbriae have been most extensively studied. The fimbrial structure is composed of 41-kDa fimbrillin proteins. DNA sequencing of the fimbrillin gene (fimA) from nine strains of P. gingivalis suggests intraspecies variation in the structure of fimA, while retaining common immunochemical specificities. P. gingivalis fimbriae exhibit a wide variety of biological activities including immunogenicity, binding to various host proteins, stimulation of cytokine production and promotion of bone resorption, Actinobacillus actinomycetemcomitans also possesses fimbriae; however, little is known concerning their chemical, genetical, and biological properties. Fimbriae of Prevotella intermedia are shown to induce hemagglutination reaction, while those of Prevotella loescheii are found to cause coaggregation with other bacteria, i.e., Actinomyces viscosus and sanguis streptococci. Fimbriae from gram-positive oral bacteria such as oral Actinomyces and sanguis streptococci are described. These fimbriae may participate in coaggregation, binding to saliva-coated hydroxyapatite or glycoprotein of the surface layer of oral epithelial cells. Taken together, fimbriae are key components in cell-to-surface and cell-to-cell adherence of oral bacteria and pathogenesis of some oral and systemic diseases.

Actinomyces↗
PubMed1998

Porphyromonas gingivalis lipopolysaccharide modulates the responsiveness of human periodontal ligament fibroblasts to platelet-derived growth factor.

Lipopolysaccharides (LPS) prepared from periodontopathic bacteria have been known to induce various biological responses which may lead to periodontal tissue breakdown. The purpose of this study was to determine if Porphyromonas gingivalis LPS could affect cellular functions of human periodontal ligament fibroblasts (HPLF). We showed here the responsiveness of cultured HPLF to platelet-derived growth factor (PDGF)-BB, a growth factor for mesenchymal cells, in the presence of P. gingivalis LPS. DNA synthesis of HPLF was enhanced in a dose-dependent manner when LPS were co-incubated for 48 h; thereafter, it decreased to the baseline level within 24 h incubation. The stimulating effect of PDGF-BB was further enhanced by the pretreatment of HPLF with LPS (10 micrograms/ml) for 48 h. The binding assay of [125I]PDGF-BB and the flow cytometric assay using rabbit antiserum to human PDGF receptor (PDGF-R) beta-type indicated that this enhancement was due to the increase of the number of PDGF-R beta-type on HPLF. Immunoprecipitation using antiserum to human PDGF-R beta-type also showed that the synthesis of PDGF-R beta-type was augmented in the LPS-treated HPLF. These results indicate that P. gingivalis LPS stimulate cellular proliferation and responsiveness to PDGF-BB of cultured HPLF. These cellular reactions may be mediated by PDGF-BB binding, followed by increased synthesis of the receptor protein.

Becaplermin↗
PubMed1998

Binding of Porphyromonas gingivalis fimbriae to proline-rich glycoproteins in parotid saliva via a domain shared by major salivary components.

Porphyromonas gingivalis, a putative periodontopathogen, can bind to human saliva through its fimbriae. We previously found that salivary components from the submandibular and sublingual glands bind to P. gingivalis fimbriae and that acidic proline-rich protein (PRP) and statherin function as receptor molecules for fimbriae. In this study, we investigated the fimbria-binding components in parotid saliva. Fractionated human parotid saliva by gel-filtration chromatography was immobilized onto nitrocellulose membranes for the overlay assay following sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The salivary components on the membrane were allowed to interact with fimbriae purified from P. gingivalis ATCC 33277, and the interacted fimbriae were probed with anti-fimbria antibodies. The fimbriae were shown to bind to two forms of proline-rich glycoproteins (PRGs) as well as to acidic PRPs and statherin. Moreover, fimbriae bound to several components of smaller molecular size which appeared to be acidic PRP variants and basic PRPs. Fimbriae bound strongly to the purified PRGs adsorbed onto hydroxyapatite (HAP) beads. In contrast, PRGs in solution failed to inhibit the fimbrial binding to the immobilized PRGs on the HAP beads. These findings suggest that the appearance of binding site(s) of PRGs can be ascribed to their conformational changes. We previously identified the distinct segments within PRP and statherin molecules that are involved in fimbrial binding. The peptides analogous to the binding regions of PRP and statherin (i.e., PRP-C and STN-C) markedly inhibit the binding of fimbriae to PRP and statherin immobilized on the HAP beads, respectively. The PRP-C significantly inhibited the binding of fimbriae to PRG-coated HAP beads as well as to PRP on HAP beads. The peptide did not affect the binding of fimbriae to statherin, whereas the STN-C showed no effect on the fimbrial binding to PRPs or PRGs. In the overlay assay, the PRP-C clearly diminished the interactions between the fimbriae and the various salivary components, including PRPs, the PRGs, and the components with smaller molecular sizes but not statherin. These results strongly suggest that fimbriae bind to salivary components (except statherin) via common peptide segments. It is also suggested that fimbriae bind to saliva through the two distinct binding domains of receptory salivary components: (i) PRGs and PRPs and (ii) statherin.

Adult↗
PubMed1998

Comparison of the cariostatic effects between regimens to administer oolong tea polyphenols in SPF rats.

The cariostatic effect of oolong tea polyphenols administered according to several regimens was examined in specific pathogen-free (SPF) Sprague-Dawley rats given both a diet containing 20% sucrose and infected with S. sobrinus 6715. The crude preparation (OTE) of oolong tea polyphenols showed the most prominent effect on caries reduction in SPF rats when OTE was administered in the drinking water beginning 1 day prior to the inoculation of S. sobrinus 6715, when compared with chromatographically isolated polyphenol fractions (OTF1 and OTF6) of OTE. Reduction in caries development was found even when OTE was given 1 day after inoculation of the organism. OTE was shown to significantly inhibit dental caries in rats at the concentrations of either more than 5 microg/ml in drinking water or more than 10 microg/g in diet. OTF1 and OTF6 also showed significant inhibition of caries induction, with the minimum inhibitory concentration of OTF6 being 50 microg/ml in drinking water and the minimum inhibitory concentration of OTF1 being 100 microg/g in diet. These results indicate that cariostatic activity of OTE was effective even after the establishment of S. sobrinus in the oral cavity and was more effective in drinking water than in diet. Furthermore, OTE may contain some anticaries substances that affect the virulence of S. sobrinus other than glucosyltransferases.

Analysis of Variance↗
PubMed1998

1513-DMIa and 1513-DMIb, DNA methyltransferase inhibitors produced by Streptomyces sp. strain No. 1513.

Two new methyltransferase inhibitors were isolated from the culture filtrate of Streptomyces sp. strain No. 1513 and named 1513-DMIa and 1513-DMIb. 1513-DMIa and 1513-DMIb were distinguished in certain properties from DMI-1, DMI-2, DMI-3 and DMI-4 previously reported. The molecular weight of 1513-DMIa and 1513-DMIb were estimated to be 576 and 8400 from the results of FAB-MS and gel filtration, respectively. The inhibitory activities of 1513-DMIa and 1513-DMIb were shown to be pH- and temperature-dependent and both inhibited M. EcoRI in an uncompetitive manner with respect to DNA or S-adenosylmethionine (SAM).

Chromatography, Gel↗
PubMed1998

Preoperative staging of colorectal cancer by a 15 MHz ultrasound miniprobe.

BACKGROUND: Our objective was to examine the accuracy of a 15 MHz ultrasound miniprobe in the pre-operative staging of colorectal cancer by assessing the depth of tumor infiltration and involvement of pericolonic lymph nodes. METHODS: Thirty-three patients with colorectal cancer who underwent ultrasonography with a miniprobe were studied prospectively. The results of this imaging were compared with the histologic findings of the resected specimens. RESULTS: The accuracy of the miniprobe for depth of invasion (T category) was 82% (27 of 33) for all tumors, 76% (13 of 17) in pT1 cases, and 88% (14 of 16) in pT2 to pT4 cases. The accuracy of the miniprobe for nodal staging (N category) was 87% (26 of 30) overall. The sensitivity was 63% (5 of 8), the specificity was 95% (21 of 22), the positive predictive value was 83% (5 of 6), and the negative predictive value was 88% (21 of 24). CONCLUSIONS: The miniprobe is an accurate method for the preoperative TN staging of colorectal cancer. We recommend its preoperative use because the results may influence the surgical approach.

Aged↗
PubMed1998

[Intraoperative local infusion chemotherapy (ILIC) for gastric cancer].

In order to provide a high dose of cis-diammine dichloro platinum (CDDP) into the regional lymph nodes and surrounding organs during operation, "intraoperative local infusion chemotherapy (ILIC)" was devised and has been applied to advanced gastric cancer patients. The aims of this method are 1) to reduce the possibility of metastasis by affecting the cancer cells before flowing out; 2) to administer drugs to the cancer cells which evade surgical resection; 3) to administer drugs to the lymphatic flow; and 4) to reduce the systemic side effects. After the laparotomy, the part of the stomach for gastrectomy was isolated from the blood supply, applying clamps to the proximal and distal parts of the stomach and hemostats to feeding blood vessels. Through a feeding artery to the tumor, 50 mg of CDDP was injected. Twenty-four patients underwent ILIC from June 1986 to December 1993. The 5-year survival rate was significantly better in the ILIC group compared to the control group which was selected by the matched pair method. The newly devised ILIC chemotherapy is a promising way to improve the prognosis of advanced gastric cancer patients. A randomized prospective study should be undertaken.

Animals↗
PubMed1998

Impaired regional fatty acid uptake and systolic dysfunction in hypertrophied right ventricle.

UNLABELLED: Little information is available regarding the determinants of systolic contractile function of the hypertrophied right ventricle (RV). The purpose of this study was to clarify the relationship between myocardial metabolism and contractile function in the hypertrophied RV due to pulmonary hypertension (PH). METHODS: Iodine-123-labeled 15-(p-iodophenyl)-3-(R,S)-methylpentadecanoic acid (BMIPP) and 99mTc-sestamibi (MIBI) SPECT were performed to calculate the RV-to-left ventricle (LV) tracer uptake ratio (RV/LV) in 21 patients with PH (6 with primary PH and 15 with chronic thromboembolic PH). The patients also underwent electron-beam CT to assess RV ejection function (RVEF) and percentage systolic wall thickening (%SWT) and right heart catheterization to measure mean pulmonary arterial pressure (mPAP). RESULTS: There were significant positive correlations between mPAP and MIBI-RV/LV (r = 0.89, p < 0.001) and between mPAP and BMIPP-RV/LV (r = 0.86, p < 0.001). However, 8 patients showed lower BMIPP-RV/LV than MIBI-RV/LV, indicating the impairment of myocardial fatty acid uptake in the RV. These patients had lower RVEF and %SWT compared to those with normal myocardial fatty acid uptake (RVEF = 28% +/- 10% compared to 40% +/- 9% and %SWT = 33% +/- 27% compared to 74% +/- 30%, respectively; p < 0.05 for both comparisons). Although mPAP did not differ between the groups, the RVEF-mPAP and %SWT-mPAP regression lines drawn from the patients with impaired myocardial fatty acid uptake were located below the lines from the patients with normal myocardial fatty acid uptake, suggesting disproportionately decreased RV myocardial contractility for a given mPAP in patients with impaired myocardial fatty acid uptake. The patients with the impaired fatty acid uptake in the RV had a significantly higher death rate (log-rank test, p < 0.05). CONCLUSION: The results from this preliminary study suggest that myocardial fatty acid uptake is impaired in the failing hypertrophied RV due to PH.

Fatty Acids↗
PubMed1998

Fluorine-18-fluorodeoxyglucose PET identification of cardiac metastasis arising from uterine cervical carcinoma.

Cardiac metastasis of uterine cervical carcinoma is rare. We describe a patient with a past history of uterine cervical carcinoma who presented with metastasis to the heart, lungs and distant lymph nodes 3 yr after surgery and chemotherapy. Since the patient complained of chest pain and demonstrated electrocardiogram abnormalities, we performed echocardiography, electron beam CT and MRI, which revealed a tumor in the right ventricular wall. The tumor was assessed by 67Ga scintigraphy and 18F-fluorodeoxyglucose (FDG) PET scanning. The mean differential 18F-FDG uptake ratio of the tumor was 7.9, suggesting malignancy, which was later confirmed by myocardial biopsy. Information about the extent of the tumor and partial necrosis within it was provided by 18F-FDG PET. Although both radionuclide imaging techniques also detected metastatic lesions in the lungs and lymph nodes, 18F-FDG PET scanning detected small lesions more sensitively than 67Ga scintigraphy.

Adult↗
PubMed1997

A novel alkaline phosphatase-based isolation method allows characterization of intraepithelial lymphocytes from villi tip and crypt regions of murine small intestine.

The isolation of intestinal intraepithelial lymphocytes (IEL) is a major prerequisite for the investigation of cellular and molecular cross-talk in the intestinal mucosa. Since intestinal epithelial cells exhibit distinct functional features at the villi tip and crypt levels, such differences could extend to IEL. We developed a mechanical procedure for isolation of IEL from these distinct epithelial sites to test our hypothesis. Cells isolated from the intestinal epithelium by sequential incubations under stirring were segregated based upon their alkaline phosphatase (AP) activity since villi tip and crypt fractions expressed high and low AP activity, respectively. IEL preparations obtained after a further purification step in Percoll gradient contained > 90% Integrin alpha IEL chain+, CD3+ T cells, and no Ig+ cells. Villi tip IEL preparations possessed increased numbers of low density IEL when compared to crypt IEL, suggesting that distinct IEL-epithelial cell interactions occur at the intestinal villi tip and crypt levels.

Alkaline Phosphatase↗
PubMed1997

Senescence-related change in autologous mixed-lymphocyte reaction in senescence-accelerated mice.

Using the senescence-accelerated mouse (SAM) strains, we examined the senescence-related changes of autologous mixed-lymphocyte reaction (AMLR) as well as the phenotypic alteration of the T cell subsets. Splenic T cells from senescence-prone (SAM-P) and resistant (SAM-R) strains of mice were incubated with autologous non-T cells, and AMLR was measured on day 1-5. The kinetics of AMLR responses revealed a marked alteration in senescent SAM-P but not in non-senescent SAM-R mice, in which the peak response occurred at day 1, the response decreasing thereafter up to day 5. Similar senescence-related change was observed in aged (24-month-old) SAM-R and BALB/c mice. Furthermore, the T cells from the aged SAM-R mice cultured with non-senescent syngeneic non-T cells showed a very similar pattern to that cultured with autologous non-T cells. Flow cytometric analysis of T cell phenotype indicated that the percentage of CD4+ CD45RBhi T cells correlated with the peak AMLR responses in both SAM-P and SAM-R mice, and that the percentage of the T cell subset with extrathymic properties was significantly higher in SAM-P mice. These findings suggest that the alteration in kinetics of AMLR is related to senescence but not to the strain of mice, and may reflect a senescence-related dysfunction of the autoregulatory immune mechanisms of T cells.

Aging↗
PubMed1997

Nucleotide sequence and molecular characterization of a gene encoding GTP-binding protein from Streptococcus gordonii.

A 1286-bp fragment of chromosomal DNA from Streptococcus gordonii strain Challis was cloned and sequenced. The gene sgg consisted of 897-bp nucleotides encoding a 299-amino acid polypeptide (33,200 Da). The deduced amino acid sequence exhibited significant similarity to Era, G protein of Escherichia coli. The nucleotide binding assay demonstrated that recombinant Sgg bound [32P]GTP but not [32P]ATP, [32P]CTP, or [32P]UTP. These findings indicate that Sgg is a member of the G protein superfamily in the genus Streptococcus.

Amino Acid Sequence↗
PubMed1997

Noninvasive identification of left ventricular involvements in arrhythmogenic right ventricular dysplasia: comparison of 123I-MIBG, 201TlCl, magnetic resonance imaging and ultrafast computed tomography.

We examined the feasibility of myocardial 123I-MIBG, 201TlCl, magnetic resonance imaging (MRI) and ultrafast computed tomography (UFCT) for the early detection of left ventricular involvements in 15 patients with arrhythmogenic right ventricular dysplasia (ARVD). Radionuclide ventriculography (RNV) and myocardial imaging with 123I-MIBG, 201TlCl, MRI and UFCT were performed in all 15 patients and in 10 normal subjects. The patients' scans were visually interpreted by two nuclear medicine physicians taking into consideration the extent score (ES) and severity score (SS) calculated by using the bull's-eye view in relation to normal data derived from the normal subjects. The left ventricular ejection fraction (LVEF) was measured by RNV. Fourteen (93%) patients showed regional 123I-MIBG defects, while 12 (80%) patients showed regional 201TlCl defects. The ES and SS were higher in 123I-MIBG than 201TlCl (ES: 31.5 +/- 18.5 vs. 17.5 +/- 18.2, p < 0.01, SS: 34.8 +/- 42.2 vs. 16.9 +/- 37.5, p < 0.01). Abnormal UFCT and MRI findings suggesting fatty involvements of the LV myocardium were demonstrated in 7 patients (Group B), while 7 patients showed regional 123I-MIBG defects without abnormal UFCT and MRI findings (Group A). 123I-MIBG was significantly more sensitive than UFCT and MRI (p < 0.05), although one patient, an exception, showed abnormal UFCT findings for the apex of the LV myocardium without abnormal 123I-MIBG and MRI findings. The LVEF, as a measure of LV systolic function, was better preserved in Group A than in Group B (59.3 +/- 3.6 vs. 45.8 +/- 5.8, p < 0.01). The present findings indicated that myocardial imaging with 123I-MIBG sensitively detects myocardial damage in patients with ARVD in the early stage when cardiac systolic function is still preserved.

3-Iodobenzylguanidine↗