Biomedical subjects

K Miyazaki

Publications and source records attributed to K Miyazaki.

At least 217 records · Page 12Linked to original sources

PubMed1999

Effect of water, saliva and blood contamination on bonding of metal brackets with a 4-META/MMA/TBB resin to etched enamel.

PURPOSE: To investigate the influence of contamination by water, human saliva, and blood on the bonding of metal brackets with a 4-META/MMA/TBB resin to etched enamel. MATERIALS & METHODS: For compressive shear bond strength measurements, the surfaces of bovine enamel were prepared either by etching with 37% phosphoric acid solution for 10, 30, or 60 s and then dried with oil-free compressed air for 10 s, or by contaminating with water, human saliva, and blood. Brackets were applied with Super Bond under loads of 200, 400, or 600 g. The bonded samples were immersed in water for 1 d or thermo-cycled for 500 cycles, and the mean shear bond strengths were compared using two-way ANOVA and Scheffé's multiple comparisons test at P = 0.05. RESULTS: The bond strengths to enamel etched for 60 s were independent of the variable load, regardless of the type of contamination. A short etching duration provided higher bond strengths than extended etching of samples contaminated with saliva and blood. The bond strengths to enamel etched for 10 s after thermal stress and immersion in water were from 11.4 to 30.4 MPa. The samples contaminated by saliva showed the lowest bond strength, and thermal stress did not reduce the bond strengths.

Acrylic Resins↗

PubMed1999

Matrix metalloproteinases, tissue inhibitors of metalloproteinases, and glycosaminoglycans in synovial fluid from patients with rheumatoid arthritis.

OBJECTIVE: To investigate the correlation between synovial fluid (SF) concentrations of metalloproteinase (MMP) -2, -3, and -9, tissue inhibitors of metalloproteinases (TIMP)-1 and -2, chondroitin 4-, 6-sulfate (deltadi-C4S, deltadi-C6S), hyaluronic acid (deltadi-HA), antigenic keratan sulfate (KS), and radiologic grade in patients with rheumatoid arthritis (RA) and to assess the clinical value of these factors as disease markers. METHODS: Enzyme linked immunoassays and high performance liquid chromatography were used. SF samples were collected from 52 patients with RA. Radiographic (Larsen grade) and clinical evaluations were also done. RESULTS: There was no significant correlation between the concentrations of MMP, TIMP, and deltadi-C4S, deltadi-C6S, deltadi-HA, and antigenic KS. No significant correlations were found between the radiologic grade and the concentrations of MMP or TIMP in SF. There was a significant increase in the concentration of antigenic KS and deltadi-C6S/deltadi-C4S ratio in SF from patients with Larsen grade 2 compared to grade 5. A significant correlation between deltadi-C6S and antigenic KS concentrations in SF was observed. CONCLUSION: Although there were large variances between the samples in this study, proteoglycan metabolism in the cartilage matrix of the patients with RA might have been increased in the early phases of tissue destruction and decreased in advanced stages because of scanty cartilage tissue. The concentrations of MMP-2, -3, -9 and TIMP-1, -2 in SF did not seem to be influenced by the amount of residual cartilage.

Aged↗

PubMed1998

Reward-quality dependent anticipation in rat nucleus accumbens.

Single unit recording in rat nucleus accumbens (NAcc) was used to ascertain NAcc neuronal activity in mediating of reward including its anticipation. Of the 103 neurons investigated, 63% showed some response in connection with the task activity. Of these, 20 units responded during delivery of the primary reward (food and/or water) and five responded during the time period preceding reward if the reward was delayed (four to food, one to water). These result suggest that NAcc neurons responded not only to the delivery of primary reward and task inducing anticipation of reward, but also represent the difference of reward quality between food and water specifically.

Animals↗

PubMed1998

Detection of tumor promoters by early antigen expression of EB virus in Raji cells using a fluorescence microplate-reader.

As an in vitro assay for possible tumor promoters, we designed a quantitative immunofluorometric method to detect Epstein-Barr virus early antigen (EBV-EA) expression in Raji cells. In this method, anti-EBV-EA monoclonal antibody, a fluorogenic substrate and a fluorescence microtiterplate-reader were employed. 12-O-Tetradecanoylphorbol-13-acetate (TPA) was shown to be a potent inducer. EBV-EA induction by TPA was related to the activation of protein kinase C and phospholipase A2. The chemicals that reacted positively were okadaic acid, diethylstilbestrol, progesterone, sodium phenobarbital, aldrin and dieldrin. Lithocholic acid, testosterone and DDT were equivocal in the present experiments. Eight other chemicals tested did not react.

Acetophenones↗

PubMed1998

4-Benzylamino-1-chloro-6-substituted phthalazines: synthesis and inhibitory activity toward phosphodiesterase 5.

We synthesized various 4-benzylamino-1-chloro-6-substituted phthalazines (15) and 4-benzylamino-1-chloro-7-substituted phthalazines (16) and evaluated their inhibitory activity toward phosphodiesterase 5 (PDE5) purified from porcine platelets. The PDE5-inhibitory activities of 15 were greater than those of the isomers (16). The preferred substituent at the 4-position of phthalazine was a (3-chloro-4-methoxybenzyl)amino group, and those at the 6-position were cyano, nitro, and trifluoromethyl groups. Compounds 15a (IC50 = 4.8 nM), 15f (3.5 nM), and 15i (5.3 nM) were more potent inhibitors than E4021 (8.6 nM). Compounds 15a and 15f also showed vasorelaxant activity in isolated porcine coronary arteries precontracted with prostaglandin F2alpha (10(-5) M). The EC50 values for vasorelaxant action of 15a, 15f, and E4021 were 150, 160, and 980 nM, respectively. These results show that novel PDE5 inhibitors possessing a potent vasorelaxant effect may exist among phthalazine derivatives.

3',5'-Cyclic-GMP Phosphodiesterases↗

PubMed1998

Matrilysin-specific antisense oligonucleotide inhibits liver metastasis of human colon cancer cells in a nude mouse model.

Human colon cancer frequently develops liver metastasis. Matrilysin (MMP-7), the smallest member of the matrix metalloproteinase (MMP) family, is commonly produced by human colon carcinoma cells and has been suggested to be involved in the progression and metastasis of this type of cancer. In the present study, we tested the effect of a matrilysin-specific antisense phosphorothioate oligonucleotide on liver metastasis of the human colon carcinoma cell line WiDr in nude mice. In culture, the antisense oligonucleotide moderately inhibited the secretion of matrilysin by WiDr cells. Injection of WiDr cells into the spleen of nude mice produced many metastatic tumor nodules in the liver. When the antisense oligonucleotide was injected daily into the mice for 11 days, the formation of the metastatic tumor nodules was strongly inhibited in a dose-dependent manner. An inhibition of liver metastasis of over 70% was obtained at a dose of 120 micrograms of the oligonucleotide per mouse. The antisense oligonucleotide did not inhibit tumor growth in spleen and in liver. A scrambled control oligonucleotide had no effect on liver metastasis of WiDr cells. Our results demonstrate an important role of matrilysin in liver metastasis of human colon cancer and the therapeutic potential of matrilysin antisense oligonucleotides for the prevention of metastasis.

Aged↗

PubMed1998

Mechanism of the inhibitory effect of imipramine on the Na+-dependent transport of L-glutamic acid in rat intestinal brush-border membrane.

The mechanism of the inhibitory effect of imipramine, a lipophilic organic cation on the Na+-dependent transport of L-glutamic acid across intestinal brush-border membrane was investigated. The uptake of L-glutamic acid by intestinal brush-border membrane vesicles was dependent on the concentration of Na+. Fitting of the uptake data in the presence of various concentrations of Na+ using Hill equation yielded a Hill coefficient of 2.18. This result suggest that the carrier system of L-glutamic acid has at least two sites for Na+-binding. By the analysis of double reciprocal plot and Dixon-type plot, it was found that imipramine inhibits the transport of L-glutamic acid by interacting competitively with the binding sites of Na+, but not inhibit L-glutamic acid binding site. Moreover, the effect of imipramine on the transport of L-alanine and D-glucose which are co-transported with only one Na+ molecule was also suggestive of interaction with the Na+-binding sites on the carrier. These results indicate that the mechanism of the inhibitory effect of imipramine on the Na+-dependent carrier systems is common for all systems regardless of the stoichiometry or substrates.

Alanine↗

PubMed1998

Purification by ceftibuten-affinity chromatography and the functional reconstitution of oligopeptide transporter(s) in rat intestinal brush-border membrane.

The transport activity of ceftibuten, a dianionic peptide-like compound, was extracted from rat intestinal brush-border membrane by n-octylglucoside and reconstituted into asolectin liposomes by dialysis. The proteoliposomes prepared from the membrane extract showed an inward H+-gradient-dependent uptake of ceftibuten and glycylsarcosine. Ceftibuten-immobilized affinity chromatography of the membrane extract permitted the isolation of two polypeptides (apparent molecular mass of 117 and 127 kDa) that can recognize the dianionic peptide structure of ceftibuten. Proteoliposomes prepared from reconstituting the isolated proteins into asolectin vesicles showed an overshooting uptake of ceftibuten in the presence of an inwardly directed H+ gradient, and this uptake could be inhibited by L-valyl-L-proline. N-glycanase digestion of the isolated proteins, 117 and 127 kDa, trimmed them into 78 and 120 kDa products, respectively. The protein core size of the smaller protein was in agreement with the calculated molecular mass of approximately 79 kDa for the rat PepT1 transporter obtained by other investigators.

Animals↗

PubMed1998

cDNA cloning of a novel trypsin inhibitor with similarity to pathogenesis-related proteins, and its frequent expression in human brain cancer cells.

A novel trypsin inhibitor (P25TI) with an apparent molecular size of 25 kDa has previously been purified from the culture medium of human glioblastoma cells. In this study, the cDNA encoding P25TI was isolated by the polymerase chain reaction (PCR) screening system, and its complete amino acid sequence was determined. The cDNA consisted of 1440 nucleotides and encoded a sequence of 258 amino acids. The deduced structure of P25TI seemed to consist of a putative signal peptide sequence (residues 1-25), a propeptide sequence (26-60) and a mature protein (residues 61-258). The P25TI sequence has no homology to other proteinase inhibitors, but has similarity to insect venom allergens, mammalian testis-specific proteins and plant pathogenesis-related proteins. P25TI mRNA was frequently expressed in human neuroblastoma and glioblastoma cell lines. Although Northern blotting analysis failed to detect P25TI mRNA in various human tissues, PCR analysis showed its expression in the brain, placenta and lymphocytes.

Amino Acid Sequence↗

PubMed1998

Purification and liposomal reconstitution of the oligopeptide transport activity in rat renal cortex using ceftibuten-affinity chromatography.

The carrier protein(s) responsible for the transport of ceftibuten, a peptide-like dianionic cefem, in rat renal brush-border membrane were solubilized and purified by a ceftibuten-ligand specific affinity chromatography technique. The proteoliposomes reconstituted from the solubilized brush-border membrane proteins by dialysis had H+-sensitive uptake of ceftibuten and trans-stimulative effect by cephalexin. A specific uptake activity for ceftibuten was found in the 3.5 M-eluted fraction but not the flowthrough and the 0.5 M-eluted fraction of the affinity chromatography. Analyzing this active fraction by SDS/PAGE after reconstituting into liposomes gave two major proteins (approx. molecular masses of 130 and 107 kDa). The purification protocol presented in this study permitted an efficient isolation of the carrier proteins responsible for the transport of ceftibuten and other peptide-like compounds.

Animals↗

PubMed1998

Expression of interleukin (IL)-12 mRNA in gastric carcinoma specimens: cellular antitumor immune responses.

BACKGROUND AND OBJECTIVES: Several tumor-related antigen peptides that are recognized by autologous cytolytic T cells (CTL) have been reported. However, most human solid tumors, including gastric carcinoma, are only weakly immunogenic. In this study, we focused on interleukin (IL)-12 and interferon-gamma (IFN-gamma) as key cytokines for estimating positive cellular immune responses. METHODS: To estimate the immunogenicity of gastric carcinomas, we examined IL-12 and IFN-gamma at mRNA levels by reverse transcription-polymerase chain reaction assay (RT-PCR) in tumor specimens and adjacent nontumor specimens from 36 gastric carcinoma patients. RESULTS: IL-12 expression was detected in 12 tumor specimens and in only two adjacent nontumor specimens (P = .003). The frequency of IFN-gamma gene expression was higher in the IL-12 mRNA-positive tumor specimens than in the IL-12 mRNA-negative tumor specimens (P = .015). In the IL-12 mRNA-positive tumors, IFN-gamma expression was higher in the tumor specimens than in the adjacent nontumor specimens (P = .007). Conversely, in the IL-12 mRNA-negative tumors, IFN-gamma expression was lower in the tumor specimens than in the nontumor specimens (P = .03). Many tumor-infiltrating mononuclear cells, predominantly T cells, were found in four of the 12 IL-12-mRNA-positive tumor specimens and in none of the 24 IL-12-mRNA-negative tumor specimens (P = .008). CONCLUSIONS: These data suggest that possible immune responses against a tumor may occur at the mRNA level in approximately one-third of gastric carcinomas.

Blotting, Southern↗

PubMed1998

Thermal analysis of bones from ovariectomized rats.

Thermal analyses [thermogravimetry (TG) and differential thermal analysis (DTA)], X-ray diffraction, and infrared absorption analysis of bones from ovariectomized rats were carried out. The rats were divided into five groups: sham operated (Sham); ovariectomized (OVX); OVX given traditional Chinese (Kampo) medicine, Unkei-to; OVX given 17 beta-estradiol; and OVX given the estradiol vehicle, respectively. The activation energy (delta E), a kinetic parameter from TG data of OVX rats, increased by 57% from that in Sham rats. The administration of Unkei-to and 17 beta-estradiol to OVX rats clearly restored the delta E to the levels of Sham rats, while the vehicle for 17 beta-estradiol had no effect. DTA data from thermal analyses of rats from the Sham, OVX, and OVX given various compounds were almost the same except for OVX rats given 17 beta-estradiol. The X-ray diffraction pattern and infrared absorption spectrum of bone powders from Sham rats were not different from those of OVX rats or others. These results strongly suggest that kinetic parameter, delta E calculated from TG data, may be a useful method for assessing both experimentally induced osteoporosis and drug effects on it.

Animals↗

PubMed1998

Additional possible tools for identification of proteins on one- or two-dimensional electrophoresis.

Additional, essentially chemical, identification methods of proteins in polyacrylamide gel electrophoresis are described. Two cleavages of peptide bonds were used at the C-side of aspartic acid with a 0.2% pentafluoropropionic acid (PFPA) aqueous vapor at 90 degrees C for 4-16 h, and the N-side of serine/threonine with an S-ethyl trifluorothioacetate vapor at 50 degrees C for 6-24 h. The products were analyzed by mass spectrometry-peptide mass fingerprinting. A new type of C-terminal sequencing at multisites of protein was introduced. An aqueous vapor of 90% PFPA at 90 degrees C for 2-16 h provided cleavages at the C-side of aspartic acid and the N-side of serine/threonine and simultaneous successive truncation at the C-termini of the cleaved fragments. The product resulted in C-terminal sequences at multisites in proteins by mass spectrometric analysis. The following chemical deblocking methods were used. Anhydrous hydrazine vapor at -5 degrees C for 8 h deblocked the N-formyl group, and the vapor at 20 degrees C for 4 h deblocked pyrrolidone carboxylate. N-acetylserine/threonine was deblocked by aqueous vapor of 75% PFPA at 50 degrees C for 1 h, followed by reaction with p-sulfophenylisothiocyanate at pH 6.0. These methods were applied to a variety of protein spots on polyacrylamide gels. A new stepwise C-terminal sequencing of protein from polyacrylamide gels is also described.

Amino Acid Sequence↗

PubMed1998

Differential expression of trypsin in human ovarian carcinomas and low-malignant-potential tumors.

It is widely recognized that matrix metalloproteinases and serine proteinases play an important role in cancer invasion and metastasis. We have reported that trypsin is synthesized in ovarian carcinomas as well as in some other types of cancers. In general, ovarian cancers easily tend to invade, metastasize, and spread widely into the peritoneal cavity. However, low-malignant-potential (LMP, borderline tumor) ovarian tumors are known to have limited malignant potential for progression, although microinvasion and distant metastasis have been reported among them. To analyze the relationship between varied degrees of trypsin expression and malignant behavior of ovarian tumors, immunohistochemical studies with monoclonal antibodies to human trypsin and clinicopathologic analysis were performed in human ovarian carcinomas, low-malignant-potential tumors, and benign cystadenomas. Thirteen (44.8%) cases of 29 ovarian carcinomas showed prominent trypsin expression, while only 2 (18.2%) cases of 11 LMP ovarian tumors demonstrated low levels of expression. Benign tumors and normal ovaries did not show any positivity for trypsin. These data suggest that tumor-derived heterotropic trypsin may be associated with ovarian tumors in parallel with malignant potential or behavior such as invasiveness or metastasis. At least in some ovarian carcinomas, prominent stromal invasion or metastasis might require the acquisition of or association with tumor-derived trypsin production.

Female↗

PubMed1998

Immunohistochemical expression of thymidine phosphorylase in human endometrial cancer.

OBJECTIVE: To investigate correlations between the expression of thymidine phosphorylase (TP) by endometrial cancer cells and the density of microvessels within the tumor, the clinicopathologic features, and the prognosis. METHODS: We examined tumor specimens obtained from 46 patients with endometrial cancer (9 FIGO stage IA, 16 stage IB, 8 stage IC, 1 stage IIA, 6 stage IIB, and 6 stage IIIC). The cellular expression of TP and the intratumoral density of microvessels were determined by immunohistochemistry using monoclonal antibodies to TP and factor VIII-related antigen, respectively. We investigated the relationship between the cellular expression of TP and the following factors: clinicopathologic features (menopausal status, histologic type, tumor size, histologic grade, myometrial invasion, cervical invasion, and metastasis), the microvessel count, and the disease-free survival period. RESULTS: Of the 46 tumors, 19 (41%) were TP-positive. The microvessel count was significantly higher in TP-positive tumors than in TP-negative tumors (P = 0.01, Mann-Whitney U test). There was no significant correlation between TP expression and clinicopathologic features, and there was no significant difference in the disease-free survival period between patients with TP-positive tumors and patients with TP-negative tumors. CONCLUSION: TP expression was not correlated with clinicopathologic features or prognosis, but was associated with an increased density of microvessels in endometrial cancer. These findings suggest that TP may play an important role in angiogenesis and may be involved in the tumorigenesis of endometrial cancer.

Adult↗

PubMed1998

A multivariate logistic regression analysis in predicting malignancy for patients with ovarian tumors.

OBJECTIVE: Our objective was to improve the preoperative diagnosis of ovarian malignancy using a multivariate logistic regression analysis on the basis of demographic, serologic, gray-scale morphological, and Doppler variables. METHODS: One hundred seventy-one patients with ovarian tumors (120 benign, 51 malignant including 9 tumors of low malignant potential) were studied with transvaginal B-mode, color, and pulsed Doppler ultrasonography before surgery. Based on the gray-scale ultrasound imaging, each tumor was classified as a unilocular cyst, multilocular cyst, unilocular cyst with solid parts, multilocular cyst with solid parts, or solid tumor. Intratumoral blood flow velocity waveforms were recorded on all tumors except unilocular cyst and were evaluated for resistance index (RI) and peak systolic velocity (PSV). Serum CA 125 levels were also measured. RESULTS: Twenty tumors were unilocular cysts and were all benign. Seventy tumors including all unilocular cysts which showed no flows were all benign. The remaining 101 tumors (50 benign, 51 malignant including 9 tumors of low malignant potential) presented intratumoral blood flows. Univariate and multivariate logistic regression analyses were conducted to identify variables predictive of ovarian malignancy in these 101 tumors. The variables included age, menstrual state, serum CA 125 levels, B-mode classification, RI, and PSV. In univariate analysis, menopause, the positivity of CA 125 (> or = 35 U/ml), and PSV larger than or equal to 10.4 cm/s were found to be significantly associated with malignant tumors. The PSV value of 10.4 cm/s was the median in benign tumors. Multivariate analysis showed that serum CA 125 levels (> or = 35 U/ml) (P = 0.002) and PSV (> or = 10.4 cm/s) (P < 0.001) were to be independent predictors of malignancy. CONCLUSION: These results suggest that intratumoral PSV is the strongest means of differentiating benign from malignant ovarian tumors with suspicious gray-scale ultrasonographic findings.

Adolescent↗

PubMed1998

Localization of vascular endothelial growth factor in synovial membrane mast cells: examination with "multi-labelling subtraction immunostaining".

Mast cells are believed to play a novel part in the development of destructive synovial pannus in rheumatoid arthritis (RA). This study was undertaken to investigate the localization of vascular endothelial growth factor (VEGF) in the synovial membrane using a unique immunostaining technique. Synovial specimens of RA patients were examined immunohistochemically and were compared with specimens from non-RA controls. Multi-labelling subtraction immunostaining, a modification of double- and triple-labelling immunostaining, revealed that the VEGF-positive cells were identical to tryptase-positive cells (mast cells). No other cell types were found to be positive for VEGF. The synovium of RA patients showed a larger number of VEGF-positive mast cells than that of non-RA controls (P<0.001). The study suggests that mast cell-derived VEGF may contribute to the development of synovial pannus in RA.

Arthritis, Rheumatoid↗

PubMed1998

Portal vein reconstruction with conventional polytetrafluoroethylene grafts: an experimental study in dogs.

The purpose of this study was to examine the short- and long-term performance of conventional polytetrafluoroethylene (PTFE) grafts for portal vein reconstruction. The grafts were placed as a portal vein replacement in 11 mongrel dogs. At 1 month and 6 months, the grafts were then retrieved and examined for patency, while also undergoing a pathological analysis. During the observation period (at 55 days), one dog died of an unknown cause with a patent graft. The patency rates of the other 10 grafts were 83% (5/6) at 1 month and 100% (4/4) at 6 months. However, the neointima formation was incomplete even 6 months after implantation. In conclusion, although conventional PTFE grafts may be used as a synthetic alternative to autogenous vein grafts, every effort should be made to use autogenous vein grafts before considering conventional PTFE grafts.

Animals↗