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Biomedical subjects

S Uno

Publications and source records attributed to S Uno.

At least 55 records · Page 3Linked to original sources
PubMed1996

Effects of acidic conditioners on dentine demineralization and dimension of hybrid layers.

OBJECTIVES: This study was aimed at investigating the relationships between dentine conditioning for different durations with different acids and (1) the resulting depth of dentinal demineralization and (2) the rebounding capacity of collapsed collagen due to primer and adhesive resin penetration. METHODS: Two commercial and four experimental acids were tested directly by light microscopic evaluation of the depth of decalcification of dentine, and indirectly by determination of the hybrid layer thickness and the total depth of demineralization effects on perpendicular sections through Gluma bonded composite resin specimens. RESULTS: Depths of demineralization increased by both acid concentrations and conditioning times following a logarithmic relationship. There was good agreement between the results of the direct and the indirect procedures. Thirty seconds' conditioning with 20% phosphoric-acid gel resulted in 10-microns hybrid layer thickness. This 20% compound was considered a suitable compromise as a uni-etch conditioner since 30-s etch duration also generated an effective enamel retentive pattern and at the same time a frosted enamel appearance for visual control of extent and efficacy of enamel conditioning.

Acid Etching, Dental↗
PubMed1996

Resin-modified glass ionomer cements: bonding to enamel and dentin.

OBJECTIVES: This study was designed to investigate the effect of storage in water on bonding efficacy to enamel and dentin of four resin-modified (Dyract, De Trey Dentsply; Fuji II LC, GC Dental Corp.; Photac Fil, ESPE; Vitremer, 3M Dental Products), one conventional glass ionomer filling material (Ketac Fil, ESPE) and a resin composite system (Pekafill/Gluma bonding system, Bayer). The hypothesis was that water storage would lead to an adverse effect on bond strength of resin-modified glass ionomer cements to enamel and dentin. METHODS: The shear bond strength of each material was determined after storage periods of 24 h, 1 wk, 1 mon, 3 mon and 6 mon. The data were subjected to one-way ANOVA. Significant differences were determined by multiple comparison testing (significance level 5%). The failure modes of the debonded specimens were analyzed with a dissecting microscope. RESULTS: Shear bond strengths to enamel for Dyract, Photac Fil and Pekafill were 5.2 +/- 1.3, 9.9 +/- 1.6 and 17.0 +/- 2.3 MPa, irrespective of storage time (p > 0.05). For Ketac Fil, the average shear bond strength between 1 wk and 6 mon was 4.5 +/- 1.7 MPa, the mean value for Fuji II LC between 24 h and 3 mon was 10.3 +/- 3.9 MPa and after 6 mon was 19.8 +/- 4.4 MPa, while Vitremer showed increasing shear bond strengths between 24 h (2.4 +/- 0.8 MPa) and 1,3 and 6 mon (13.8 +/- 4.3 MPa). Shear bond strengths to dentin were not adversely affected by storage throughout the 6 mon for Dyract (13.0 +/- 2.6 MPa), Fuji II LC (12.7 +/- 1.7 MPa) and Pekafill (14.6 +/- 3.1 MPa), when tested by ANOVA (p > 0.05). Ketac Fil showed 4.9 +/- 1.2 MPa between 1 wk and 6 mon and lower shear bond strength after 24 h. The average shear bond strengths up to 1 mon for Vitremer were 5.4 +/- 2.5 MPa (p > 0.05). However, at 3 and 6 mon immersion in water, three specimens had loosened spontaneously. With Photac Fil, no adhesion to dentin was registered. Most samples showed cohesive failure patterns in the restorative materials. Adhesive or mixed failures were registered only for Vitremer on dentin and enamel up to 1 wk and for Dyract on enamel. SIGNIFICANCE: Long-term water storage generally had no adverse effect on bonding efficacy of resin-modified glass ionomer cements to dentin and enamel.

Acid Etching, Dental↗
PubMed1996

Long-term mechanical characteristics of resin-modified glass ionomer restorative materials.

OBJECTIVES: The purpose of this study was to compare the effects of long-term water storage on the mechanical characteristics of four resin-modified glass ionomer restorative materials with those of a conventional glass ionomer cement and a resin composite material. METHODS: Cylindrical specimens were prepared and stored in water for 1 h, 24 h, 1 wk, 1 mon, 3 mon and 6 mon prior to determination of diametral tensile strength (DTS) and depth of surface indentation both under 1 N load and after removal of the load. RESULTS: Diametral tensile strength was lowest for the conventional glass ionomer cement and highest for the composite; the resin-modified glass ionomer cements were intermediate between the reference materials. Water storage reduced DTS between 24 h and 1 wk or 1 mon but then remained unaffected until the final measurements after 6 mon. The materials showed a trend toward a slight increase in the depth of indentation both under load and after removal of the load with increasing storage time. These mechanical properties indicate the position of four resin-modified glass ionomer cements on a continuum with conventional glass ionomer cement and resin composite as the end points. SIGNIFICANCE: The mechanical properties of resin-modified glass ionomers show that this group of materials is weaker than resin composite but stronger than conventional glass ionomer cement. Water storage for 6 mon has little adverse effect on the mechanical properties.

Analysis of Variance↗
PubMed1996

Production of tissue-type plasminogen activator (t-PA) and type-1 plasminogen activator inhibitor (PAI-1) in mildly cirrhotic rat liver.

We have studied the production of tissue-type plasminogen activator (t-PA) and type-1 plasminogen activator inhibitor (PAI-1) in liver of normal rats and in rats with mild cirrhosis induced by carbon tetrachloride inhalation, to demonstrate the production of these fibrinolytic components and their pathophysiologic role in the liver in vivo. Immunohistochemical study of paraffin-embedded liver sections and fibrin autography of frozen sections showed that the normal rat liver produces very little t-PA or PAI-1. On the contrary, striking t-PA activity and both t-PA and PAI-1 antigens were observed in the cirrhotic liver. Both t-PA and PAI-1 in plasma were also markedly increased in the cirrhotic rats. Because the hepatocyte can internalize t-PA or PA/PAI-1 complexes from circulation, Northern blot analysis of the total liver RNA was performed to demonstrate the endogenous synthesis of t-PA and PAI in the liver. Although the normal liver hardly expresses either t-PA or PAI-1 mRNA, striking t-PA and PAI-1 mRNA expression was observed in the liver of rats with mild cirrhosis. These data demonstrate that t-PA and PAI-1 production is strongly upregulated in the liver in rats with mild cirrhosis. These fibrinolytic components, whose production is closely associated with liver failure, may play important roles in the regulation of hepatocyte proliferation and liver regeneration in vivo.

Animals↗
PubMed1996

Bond strength of Gluma CPS using the moist dentin bonding technique.

PURPOSE: To investigate the effects of acetone or water based Gluma primers on bonding efficacy when applied to acid-etched wet, dry or rewetted dentin. MATERIALS AND METHODS: Shear bond strength (SBS, 24 hours) was measured on human dentin etched with 20% phosphoric acid gel and rinsed with water in the wet (blot dried), the conventional (2 seconds air blast), the dry (10 seconds air drying), and the rewetted stage (10 seconds air drying, remoistening and blot drying). The priming solution was either the original water based or an acetone based experimental Gluma primer. Cavity sealing performance and depth of resin impregnation were determined by solvent and by technique along the margins of 4.5 mm wide cylindrical dentin cavities with 90 degree cavosurface angle. RESULTS: The SBSs of the wet technique groups were approximately 18 MPa, irrespective of the primer solvent. Conventional drying gave an SBS almost as high (16.5 MPa). Rewetting was highly effective with acetone as the primer solvent. The dry techniques resulted in moderate (water) and poor (acetone) bond strengths. The cavity margins of acetone based primer treated specimens were consistently gap free with the wet technique. The other seven groups showed between two and six gaps in each group of six specimens. The resin impregnated layer (RIL) thicknesses were 12.5 microns approximately in the wet groups, and thus identical with the total depth of demineralization resulting from the 30-second etching. The alternative techniques showed significantly thinner RILs particularly in the dry groups (7.5 microns).

Acetone↗
PubMed1996

Marginal adaptation of resin-bonded light-cured glass ionomers in dentin cavities.

PURPOSE: To investigate the marginal adaptation of resin-modified glass ionomer cements in dentin cavities placed with or without additional application of resin bonding systems. MATERIALS AND METHODS: Three resin-modified materials (Fuji II LC, Photac-Fil, Vitremer), one compomer (Dyract) and as reference an adhesively bonded resin composite system (Gluma CPS-Pekafill) were used. Flat peripheral dentin surfaces on human molar teeth were produced by wet grinding on SiC paper. Cylindrical cavities, 3.5 mm wide, were prepared in these dentin areas and restored with the individual materials. Sixty cavities were pretreated and restored as requested by the respective manufacturers. Following water storage of the specimens for 15 minutes or 24 hours, excess was gently removed by wet grinding for microscopic inspection of the marginal area. Additionally, in 30 cavities an experimental one-component adhesive resin system, a proprietary dimethacrylate and HEMA mixture dissolved in acetone, was combined with each of the restoratives for evaluation after 15-minutes water storage. Finally, in six cavities each, Dyract was combined with Prime and Bond 2.0, and Vitremer with Scotchbond Multi-Purpose Plus for assessment after 15 minutes. Maximum marginal gap widths (MGW) were measured. One-way ANOVA by ranks (Kruskal-Wallis-Test) followed by Wilcoxon's Two-Sample test were used to study the statistical difference of MGW among the treatment groups at a rejection level P = 0.05. RESULTS: Neither the conventionally placed material systems nor the restorations in combination with adhesives showed consistently gap-free margins after 15-minute water storage. After 24-hour storage with Vitremer 4 of the 6 restorations were gap-free, whereas with all other materials only perfect margins were registered. There was, however, no significant difference between the groups. Application of the experimental and/or the specific resin bonding agents had no effect on early MGW except for the Photac-Fil group, which was significantly reduced.

Analysis of Variance↗
PubMed1995

Steroid hormones upregulate rat angiotensin II type 1A receptor gene: role of glucocorticoid responsive elements in rat angiotensin II type 1A promoter.

The transcription of the rat angiotensin II type 1A receptor gene is stimulated by glucocorticoids. To clarify the molecular mechanism for glucocorticoid action in rat vascular smooth muscle cells, we investigated the effects of dexamethasone on the promoter activity of the angiotensin II type 1A receptor by using promoter/luciferase reporter gene constructs and heterologous context constructs (containing the thymidine kinase promoter) in transfected vascular smooth muscle cells. There are three putative glucocorticoid responsive elements in the promoter. However, only one glucocorticoid responsive element was found to respond to dexamethasone (1 microM). The region was located at positions, -756 to -770 bp upstream of the transcription initiation site. A glucocorticoid antagonist, RU38486, completely blocked the induction by dexamethasone, suggesting that the glucocorticoid responsive element was functional through a specific glucocorticoid receptor. Compared with the angiotensin II type 1A receptor promoter, no effect by dexamethasone was observed in vascular smooth muscle cells transfected with the angiotensin II type 1B receptor promoter/luciferase reporter gene constructs. We concluded that the dexamethasone-induced increase in the transcription of the angiotensin II type 1A receptor gene occurred through the binding to GRE up the glucocorticoid-specific receptor.

Aldosterone↗
PubMed1995

Cytotoxicity of anti-c-erbB-2 immunoliposomes containing doxorubicin on human cancer cells.

We have examined the selective cytotoxicity of immunoliposomes containing doxorubicin (chemoimmunoliposomes, CILs) targeting the c-erbB-2 gene product (gp185) or gp125. Anti-gp185 and anti-gp125 CILs were prepared by conjugation of doxorubicin-containing liposomes with monoclonal antibodies SER4 (IgG) and HBJ127 (IgG) respectively. Both CILs bound to human SKBr-3 breast cancer cells and MKN-7 human gastric cancer cells, which express both antigens in high density. The IC50 of anti-gp185 CILs on protein synthesis by SKBr-3 cells was respectively 2- and 25-fold lower than that of anti-gp125 CILs and unmodified liposomes. Furthermore, anti-gp185 CILs significantly inhibited neither the phytohaemagglutin response of normal lymphocytes nor protein synthesis of gp185-negative T24 bladder cancer. Quantitative analysis of cell-associated doxorubicin revealed that, compared with anti-gp125 CILs, anti-gp185 CILs required, respectively 4.5 and 4.3 times less doxorubicin association in SKBR-3 and MKN-7 cells, for 50% cytotoxicity. In addition, flow cytometric analysis showed that both SKBr-3 and MKN-7 internalised more anti-gp185 CILs and processed them more efficiently than anti-gp125 CILs. These results suggest that anti-gp185 CILs act selectively against gp185-expressing cancer cells and that gp185 is a more sensitive antigen for CIL cytotoxicity associated with endocytosis activity.

Animals↗
PubMed1995

Identification of a cis-acting glucocorticoid responsive element in the rat angiotensin II type 1A promoter.

Enhanced vascular responsiveness to angiotensin II at the AT1 receptor has been considered one of the major contributing factors to vascular hypertrophy and high blood pressure. The transcription of the rat angiotensin II type 1A receptor gene is stimulated by glucocorticoids. To clarify the molecular mechanism for glucocorticoid action in rat vascular smooth muscle cells, we investigated the effects of dexamethasone on the promoter activity of the angiotensin II type 1A receptor by using promoter/luciferase reporter gene constructs and heterologous context constructs (containing the thymidine kinase promoter) in transfected vascular smooth muscle cells (< 12 passages). There are three putative glucocorticoid responsive elements (GREs) in the promoter. However, only one GRE was found to respond to dexamethasone (1 mumol/L) and was located at positions -756 to -770 bp upstream from the transcription initiation site. When compared with the consensus sequence of GRE, 9 of 12 bases were identical. RU38486, a glucocorticoid antagonist, completely blocked the induction by dexamethasone, suggesting that the GRE was functional through a specific glucocorticoid receptor. The response to dexamethasone was lost in vascular smooth muscle cells at higher passage numbers (> 8 passages) but was restored when the cells were transfected with a glucocorticoid-receptor expression construct. This finding provided additional support that the response to dexamethasone was mediated by the glucocorticoid receptor. The gel mobility supershift assay showed that the GRE binds in vitro-translated rat glucocorticoid receptors in a specific manner. Compared with the angiotensin II type 1A receptor promoter, no effect by dexamethasone was observed in vascular smooth muscle cells transfected with the angiotensin II type 1B receptor promoter/luciferase reporter gene constructs.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiotensin II↗
PubMed1995

Molecular structure and transcriptional regulation of the gene for the platelet-derived growth factor alpha receptor in cultured vascular smooth muscle cells.

PDGF has been shown to contribute to hypertrophy in vascular smooth muscle cells (VSMC). PDGF-AA differentially promotes protein synthesis in VSMC from spontaneously hypertensive rats (SHR) but not in those from Wistar-Kyoto rats (WKY). This observation has led us to postulate a role for PDGF alpha receptor (PDGFR-alpha) in the hypertensive hypertrophy of blood vessels. Western and Northern blot analyses demonstrated a high and specific expression of the PDGFR-alpha protein and mRNA in SHR cells but not in WKY cells. To clarify the mechanism of the differential expression of the PDGFR-alpha gene, we isolated the promoter region of the gene. Studies on the promoter functions indicated that this promoter is active in SHR cells but not in WKY cells. The regulatory domain responsible for this difference was narrowed to the sequence between -246 and -139, which enhanced the promoter activity of SHR fivefold over the basal activity. DNase I footprinting and gel-shift assay indicated that this sequence specifically interact with nuclear proteins from VSMC through the binding site for CCAAT/enhancer-binding proteins, and members of the C/enhancer-binding protein family play a significant role in the strain-specific transcription of the PDGFR-alpha gene.

Animals↗
PubMed1995

Inhibition kinetics of theophylline metabolism by mexiletine and its metabolites.

To further characterize the mode of drug interaction between theophylline (TP) and mexiletine (ME), in vitro kinetic studies were carried out using rat liver microsomes and 9000 x g supernatant. The kinetic study revealed that the Km value and Vmax/Km ratio for the metabolic conversion of TP to 1,3-dimethyluric acid (1,3-DMU) were the second lowest and the highest, respectively, of four metabolic pathways. Thus, the rank of efficiency of the oxidative metabolism by microsomal cytochrome P-450 (P-450) isozymes was TP to 1,3-DMU > TP to 1-methylxanthine (1-MX) > TP to 3-MX > 1,3-DMU to 1-methyluric acid, suggesting that the isozyme metabolizing TP would have a higher affinity for the oxidation at the 8-position in TP molecules than at the 1- and 3-positions. Lineweaver-Burk plots showed that the conversion of TP to 3-MX and to 1,3-DMU was inhibited competitively by ME and its metabolites, and that the pathway of TP to 1-MX was inhibited noncompetitively. In consideration of the Ki values calculated, it seems probable that deamino-p-hydroxy ME (DApHME) might be the most potent inhibitor of the metabolic pathways of TP, and that the rank order of inhibition is approximately DApHME > p-hydroxy ME > deamino-hydroxymethyl ME > ME > hydroxymethyl ME, with some exceptions. The mechanism of the interaction between TP and ME is probably due to the metabolic antagonism in the liver, and TP, ME and their metabolites share some of the same metabolic pathways, mediated by P-450 isozymes.

Animals↗
PubMed1995

Enzymatic method for determining ketone body ratio in arterial blood.

We have developed a new, sensitive, and rapid method for measuring the ketone body concentration in arterial blood and determining the arterial blood ketone body ratio. The procedure involves the sequential use of the enzymes 3-hydroxybutyrate dehydrogenase (3-HBDH; EC 1.1.1.30) and NADH oxidase, followed by a color-generating reaction with the hydrogen peroxide produced by the oxidase reaction. The amount of oxidized chromogen produced is proportional to the 3-hydroxybutyrate (3-HBA) concentration. The acetoacetate (AcAc) concentration is obtained after complete conversion of the AcAc to 3-HBA, in the presence of 3-HBDH. The total 3-HBA concentration is measured and then subtracted from the total ketone body concentration to give the AcAc concentration. This procedure may be applied to plasma samples and the absorbance change measured with an automated chemistry analyzer. Ketone body concentration may be determined over the range 0 to 400 mumol/L. The analysis takes approximately 12 min and requires only 30 microL of plasma.

Arteries↗
PubMed1995

Effect of acid etchant composition and etch duration on enamel loss and resin composite bonding.

PURPOSE: To investigate the effects of different acid etchants' ability to condition enamel as gently as possible to remove a minimum of substance only, to produce a highly retentive pattern, and finally to ensure frosty appearance of the etched enamel for clinical control of the procedure. MATERIALS AND METHODS: Two commercial uni-etch gels, Gluma 2000-1 and Scotchbond Multi-Purpose Etchant, were studied together with gels of 5, 10, 20 and 35% phosphoric acid and varying amounts of thickening agents in the 20% gel. Enamel loss was measured with a contact-free method by materials and etch duration, and the shortest etching times for dull frosty enamel appearance were determined. Shear bond strength (SBS) was measured after 24 hours' storage in water. RESULTS: Enamel loss was very low with the commercial agents and increased with H3PO4 concentrations and with etch duration. While the commercial compounds produced no frosty enamel even after 120-second etch duration, the phosphoric acids produced frosted enamel after 15, 30, 60 and 120-second application of 35, 20, 10 and 5% acids, respectively. All etchants and etch durations tested produced effective retentive patterns. No differences in SBS were noted, and the failure modes were consistently cohesive in resin.

Acid Etching, Dental↗
PubMed1995

[Artificial insemination using the husband's frozen sperm in a patient with chronic myelogenous leukemia after bone marrow transplantation].

A 37-year-old man with chronic myelogenous leukemia (CML) was scheduled to receive a bone marrow allograft from an HLA-matching sibling. He was married without children, and desired to have a child in the future. Sperm was collected before transplantation and frozen for preservation. Induction therapy performed using 8 mg/kg of busulfan, 120 mg/kg of cyclophosphamide, splenic irradiation (4.5Gy), and total body irradiation (10Gy), and then allogenic bone marrow transplantation (BMT) was carried out. His post-transplantation course was uneventful and cyclosporin therapy was finished on day 187. The Philadelphia chromosome disappeared on day 20 after BMT and PCR analysis was negative for the bcr/abl rearrangement, suggesting the possibility of cure. Accordingly, artificial insemination was attempted using the frozen sperm. His wife became pregnant after the 4th attempt and a healthy baby was delivered. Transplantation recipients often become sterile because they receive ultra-high doses of chemotherapy and irradiation. However, it is still possible to have children if sperm or ova are preserved prior to transplantation. This is thought to improve the quality of life after BMT.

Adult↗
PubMed1995

Phosphoric acid as a conditioning agent in the Gluma bonding system.

PURPOSE: To investigate the effect of phosphoric acid conditioning gels on compatibility with the Gluma dentin bonding system. MATERIALS AND METHODS: Sheer bond strengths (BS), marginal performance in dentin cavities and microleakage resistance in mixed cavities were used as target parameters to determine the efficacy of Gluma/Pekafill on dentin pretreated with conditioners of 5, 10, 20 or 35% H3PO4 and different amounts of silica (0, 5 and 10%) after 15, 30 60 or 120-second treatment duration. The thicknesses of the hybrid layers were determined along the dentin cavity margin by light microscopy. RESULTS: Neither the phosphoric acid concentration and the silica content nor the conditioning times tested had a significantly different effect on SBS or marginal performance (P > 0.05). There was no relationship between the hybrid layer thickness and the target parameters either. The SBS recorded on dentin were in the same order of magnitude as previously found on acid etched enamel (+/- 17 MPa). The marginal performance and microleakage results after thermocycling proved adequate dentin bonding and cavity sealing. Phosphoric acid etching of dentin is compatible with the gluma bonding system.

Acid Etching, Dental↗
PubMed1995

Function of the hybrid zone as a stress-absorbing layer in resin-dentin bonding.

The effects of dentinal surface conditioning with phosphoric acid or with phosphoric acid and subsequent deproteinization by sodium hypochlorite on resin bonding are presented. Bond strengths mediated by the Gluma/Pekafill bonding and restorative system were not affected by the alternative pretreatment methods, while marginal performance of restorations in dentinal cavities was significantly adversely affected by the deproteinization procedure. The resin polymer coupling zone has an important function as a layer that compensates for the curing stresses of the restorative material that act in a wall-to-wall direction.

Acid Etching, Dental↗
PubMed1994

Endocytosis does not necessarily augment the cytotoxicity of adriamycin encapsulated in immunoliposomes.

We studied the relationship between endocytosis and cytoxicity of adriamycin (ADM) encapsulated in antibody-coated liposomes (immunoliposomes, IL) which are called chemoimmunoliposomes (CIL), by using several human cancer cell lines. IL coated with a monoclonal antibody, HBJ127 (IgG), which recognizes human gp125 antigen, specifically bound to gp125-positive target cancer cell lines, KU-1, T24, MKN-7, SKBr-3 and LS174T. Flow cytometric analysis using IL encapsulating carboxyfluorescein (CF) revealed that efficiencies of endocytosis varied among different cancer cells. The rate of IL internalization was in the order KU-1 > T24 > MKN-7 > SKBr-3 > LS174T. In 1 h incubation at 37 degrees C, all the four cell lines other than LS174T internalized about 60% of IL which were bound on their cell surfaces. KU-1, T24 and MKN-7, but not SKBr-3, significantly processed IL in endosome or lysosome. On the contrary, 80% of CIL bound to LS174T remained on the cell surface even after 2 h incubation. Furthermore, we evaluated the cytotoxic activities of CIL against the same panels of cancer cells. CIL inhibited the growth of all cancer cells tested in antibody-dependent manner, but, contrary to our expectation, KU-1 and T24 cells, which showed significant endocytosis activity, required a 7-14-fold higher amount of ADM binding than LS174T cells with low endocytosis activity for 50% cell growth inhibition. The difference of sensitivity to free ADM was only within 2.3-fold among those cancer cells. These results showing that liposomal ADM endocytosed is less effective than that remaining on the cell surface suggest that endocytosis is not necessarily required for cytotoxicity of CIL.

Antigens, Neoplasm↗