Biomedical subjects

Kenichi Shirai

Publications and source records attributed to Kenichi Shirai.

7 recordsLinked to original sources

PubMed2005

Effect of cavity configuration and aging on the bonding effectiveness of six adhesives to dentin.

OBJECTIVES: The purpose of this study was to determine the effect polymerization contraction stress may have on bond durability. METHODS: Bonding effectiveness was assessed by micro-tensile bond strength testing (muTBS) and electron microscopy. The muTBS to flat dentin surfaces and in standardized cavities was determined (this after 1 day as well as 1 year water storage). Six adhesives representing all current classes were applied: two etch-and-rinse (OptiBond FL, Kerr; Scotchbond 1, 3M ESPE), two self-etch (Clearfil SE Bond, Kuraray; Adper Prompt, 3M ESPE) and two glass-ionomer (Fuji Bond LC, GC; Reactmer, Shofu) adhesives. RESULTS: The conventional 3-step etch-and-rinse adhesive OptiBond FL bonded most effectively to dentin, and appeared insensitive to polymerization shrinkage stress and water degradation. The 2-step self-etch adhesive Clearfil SE Bond most closely approached this superior bonding effectiveness and only slightly lost bond strength after 1-year water exposure. The 2-step etch-and-rinse adhesive Scotchbond 1 and the 'strong' 1-step self-etch adhesive Adper Prompt appeared very sensitive to cavity configuration and water-aging effects. The 2-step resin-modified glass-ionomer adhesive Fuji Bond LC only suffered from shrinkage stress, but not from 1-year water-exposure. Remarkable also is the apparent repairability of the 'mild' 1-step glass-ionomer adhesive Reactmer when stored for 1 year in water, in spite of the very low 1-day muTBS. SIGNIFICANCE: Simplified bonding procedures do not necessarily imply improved bonding performance, especially in the long term.

Acid Etching, Dental↗

PubMed2005

Effect of fracture strength of primer-adhesive mixture on bonding effectiveness.

OBJECTIVE: The purpose of this study was to measure the micro-tensile bond strength (microTBS) of two adhesives to dentin and to correlate this microTBS with the micro-tensile fracture strength (microTFS) of primer-adhesive mixtures of the two adhesives. METHODS: The three-step etch&rinse adhesive OptiBond FL (Kerr) and the two-step self-etch adhesive Clearfil SE Bond (Kuraray) were used to bond Filtek Z100 (3M ESPE) to twenty mid-coronal dentin surfaces. The microTBS was determined at 1 and 24 h after light-curing. In addition, the microTFS of primer-adhesive mixtures (primer:adhesive=1:3 by weight) and of the pure adhesives (controls) were measured after the same time intervals. RESULTS: The microTBS to dentin of OptiBond FL at 24 h was significantly higher than at 1 h and than the microTBS of Clearfil SE Bond at 24 h. The mean microTFS of the primer-adhesive mixtures was always lower than the microTFS of the respective adhesives. The highest reduction in microTFS due to mixing primer with the adhesive resin was measured for Clearfil SE Bond. Both the microTFS of the primer-adhesive mixtures and the pure adhesives of OptiBond FL and Clearfil SE Bond increased with time. SIGNIFICANCE: The early 1 h microTBS to dentin was lower than the 24 h microTBS for OptiBond FL, but not for Clearfil SE Bond. Differences in polymerization efficiency as well as in the resulting interfacial strength may explain such varying early bond strengths to dentin.

Composite Resins↗

PubMed2005

Is 2.5 mEq/L the optimal calcium concentration of dialysate in the use of sevelamer hydrochloride? A study of the dialysate calcium concentration recommended by K/DOQI guidelines.

We tested the effect of three different dialysate calcium concentrations on calcium-phosphorus metabolism during the use of sevelamer hydrochloride. After a calcium-containing phosphate binder was switched to sevelamer, the serum calcium, phosphorus, and intact parathyroid hormone levels and the markers of bone turnover were measured in the patients whose dialysate calcium concentrations were 2.5, 2.75, and 3.0 mEq/L. As a result, in the 2.75-mEq/L group, the serum calcium concentrations decreased and the intact parathyroid hormone level increased significantly. In the 2.5-mEq/L group, transient hypocalcemia occurred and the levels of both bone-alkaline phosphatase and osteocalcin increased. In the 3.0-mEq/L group, the serum calcium concentrations did not change significantly and only bone-alkaline phosphatase increased. If a calcium-containing phosphate binder is completely switched to sevelamer, dialysis using a dialysate calcium concentration below 3.0 mEq/L may result in hypocalcemia and acceleration of bone turnover.

Alkaline Phosphatase↗

PubMed2004

[Endothelin].

Explore the source record for details and available documents.

Acute Kidney Injury↗

PubMed2003

[A case of sarcoidosis overlapping with rheumatoid arthritis].

We report the case of a 54-year-old woman who presented on May 28, 2001 with sarcoidosis overlapping with rheumatoid arthritis. She had experienced morning stiffness 2 years previously and was diagnosed as having rheumatoid arthritis. She had been treated with bucillamine and loxoprofen for 3 months. In October 2000, she developed proteinurea. The patient discontinued treatment with bucillamine and loxoprofen. Proteinurea persisted, and the patient's renal function declined. On admission, subcutaneous nodules were palpable in the patient's legs. The patient's serum creatinine and calcium levels were 2.49 mg/dl and 11.6 mg/dl, respectively. Intact-PTH was suppressed, and PTHrP was not elevated. Despite the presence of hypercalcemia, the patient's serum 1 alpha 25(OH)2D3 was not suppressed. Serum ACE and lysozyme levels were elevated beyond the normal ranges. A renal biopsy was performed, and non-caseous epithelioid granuloma was found in the renal interstitium. Based on the histological findings, the patient was diagnosed as having sarcoidosis. Following treatment with prednisolone, the patient's serum calcium levels returned to normal and her renal function improved.

Anti-Inflammatory Agents↗

PubMed2002

Identification of genes expressed preferentially in the honeybee mushroom bodies by combination of differential display and cDNA microarray.

To clarify the molecular basis underlying the neural function of the honeybee mushroom bodies (MBs), we identified three genes preferentially expressed in MB using cDNA microarrays containing 480 differential display-positive candidate cDNAs expressed locally or differentially, dependent on caste/aggressive behavior in the honeybee brain. One of the cDNAs encodes a putative type I inositol 1,4,5-trisphosphate (IP(3)) 5-phosphatase and was expressed preferentially in one of two types of intrinsic MB neurons, the large-type Kenyon cells, suggesting that IP(3)-mediated Ca(2+) signaling is enhanced in these neurons.

Animals↗

PubMed2002

Effect of presilanization filler decontamination on aesthetics and degradation resistance of resin composites.

Filler-matrix coupling determines, to a large extent, the mechanical strength and clinical longevity of dental composites. The aim of this study was to examine how far a methodology to decontaminate filler prior to silanization may improve aesthetic performance in addition to physico-mechanical properties such as degradation resistance. It was reported that filler particles are surrounded and wrapped by a film that consists of multiple layers of silane molecules. X-ray photoelectron spectroscopy, however, revealed that silanization of filler particles largely depended upon siloxane bridge (Si-O-Si) formation between the silica surface and the silane molecule rather than on intermolecular bonding between adjacent silane molecules. In this study, we showed that filler decontamination resulted in a higher translucency, thereby providing a better aesthetic potential. In addition, experimental composites produced following presilanization decontamination of filler revealed a higher Vickers hardness value and a diametral tensile strength that was resistant to degradation by thermo-cycling.

Bisphenol A-Glycidyl Methacrylate↗