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Biomedical subjects

H Shintani

Publications and source records attributed to H Shintani.

At least 19 recordsLinked to original sources
PubMed2006

Endoscopic management of pancreaticopleural fistulas: a report of three patients.

Pancreaticopleural fistulas are a rare complication of acute or chronic pancreatitis, and are usually treated by surgery. We report three patients whose pancreaticopleural fistulas were successfully treated by endoscopic retrograde cholangiopancreatography and drainage (stenting, nasopancreatic drainage). In one patient a pancreatic pseudocyst persisted despite successful initial closure of the leak using this method and, as it was also suspected to be infected, additional drainage of the pseudocyst was required. Endotherapy of pancreaticopleural fistulas could obviate the need for surgery when conventional medical treatment has failed in this condition.

Aged↗
PubMed2005

Risk factors for myocardial injury during off-pump coronary artery bypass grafting.

BACKGROUND: Although off-pump coronary artery bypass grafting (CABG) is now used worldwide for coronary revascularization, the pre- and intraoperative risk factors for myocardial injury associated with the surgical procedure remain to be elucidated. We performed a multivariate analysis to investigate factors that contribute to myocardial injury during off-pump CABG. METHODS: The study population consisted of 22 patients who underwent off-pump CABG without apparent intraoperative complications. Blood samples were obtained before surgery and at 3 and 12 hours after the last anastomosis and serum Troponin T (cTnT) levels were measured to assess myocardial injury. Patient characteristics and factors related to preoperative cardiac function and the intraoperative process were analyzed to determine their correlation with serum cTnT levels, and the Spearman's correlation coefficient (r(s)) was computed. RESULTS: Neither age, preoperative cardiac function, time required for anastomosis, the number of grafts, nor the total amount of bleeding were associated with serum cTnT levels. Serum cTnT at 3 and 12 hours after completed anastomosis correlated with the product of mean systolic blood pressure and mean heart rate (double product) during anastomosis. The r(s) values at 3 and 12 hours were 0.62 (P = .002) and 0.58 (P = .004), respectively. With respect to the serum cTnT level at 12 hours, creatinine clearance (Ccr) had a slight effect on the serum cTnT values. CONCLUSIONS: High blood pressure and an increased heart rate during anastomosis are unfavorable factors for off-pump CABG. However, strict control of the blood pressure and heart rate makes it possible to subject even patients at high-risk to off-pump CABG from the viewpoints of myocardial injury.

Aged↗
PubMed2004

Characterization of CO3Ap-collagen sponges using X-ray high-resolution microtomography.

For reconstruction and regeneration of hard tissues, scaffold biomaterials with large size pores and high porosity are important, in addition to their roles as supporting frames. To develop a new biodegradable scaffold biomaterial, CO3Ap, which has crystallinity and a chemical composition similar to bone, was synthesized at pH 7.4 and 60 degrees C. Then, the CO3Ap was mixed with a neutralized collagen gel and the CO3Ap-collagen mixtures with different kinds of CO3Ap contents and porosity were lyophilized into sponges. Scanning electron micrography (SEM) observation of CO3Ap-collagen sponges showed favorable pores for cell invasion. Approximately 50-300 microm size pores appeared to continue through the bulk. Higher magnification of the sponge showed a better adhesion between CO3Ap crystals and collagen. X-ray high-resolution microtomography revealed a clear image of the 3D structure of the sponges. The porosity of 0, 70 and 90%(w/w) CO3Ap-collagen sponges was 79.2 +/- 2.8%, 72.6 +/- 2.4% and 48.9 +/- 6.1%, respectively. The 70%(w/w) CO3Ap-collagen sponge appeared to be the most favorable biomaterial from the viewpoint of natural bone properties. Mouse osteoblast MC3T3-E1 cells were cultured in alphaMEM with 10% FCS for 2 weeks. Hematoxylin-eosin staining confirmed osteoblast cells invaded well into the CO3Ap-collagen sponge. These sponges are expected to be used as hard tissue scaffold biomaterials for therapeutic uses.

3T3 Cells↗
PubMed2004

Leachability of plasticizer and residual monomer from commercial temporary restorative resins.

OBJECTIVES: This study was performed to determine the compositions of commercial temporary restorative resins and to evaluate the leachability of plasticizer and residual monomer from them. METHODS: The chemicals in four commercial temporary restorative resins (Dura Seal, Fit Seal, Plast Seal Quick, and Poly Seal) were detected by GCMS and HPLC. The amounts of plasticizers and residual monomers that leached from cured resin samples immersed in ethanol for 1 h to 14 d were determined by HPLC. RESULTS: Phthalate esters used as plasticizers contained 40-55 wt% either di-n-butyl phthalate (DBP) or butyl phthalyl butyl glycolate. The resin monomer included methyl methacrylate (MMA) or a mixture of MMA and 2-hydroxyethyl methacrylate (HEMA); 1,3-butanediol dimethacrylate was added as a cross-linking agent. Each resin contained 40-60 wt% monomer. The amounts of phthalate esters leached increased with immersion time up to 7 d, reaching 120-190 microg/mg, and did not change subsequently. The residual monomers leached gradually for up to 3d and did not change subsequently. The amount of leached residual monomer (MMA, HEMA) was 20-90 microg/mg after 3d storage. More than 50% of the leachable plasticizers and monomers were eluted from the cured resins within 24 and 3 h, respectively. CONCLUSIONS: The amounts of leached plasticizers and residual monomers were extremely large compared with the concentrations of endocrine disrupters and their potentially genotoxic effects. Therefore, it is very important to evaluate the leachability of these compounds from temporary restorative resins.

Acrylic Resins↗
PubMed2004

Comparison of the collecting efficiency of microbiological air samplers.

It is important to evaluate the prevention of nosocomial infections caused by airborne micro-organisms in healthcare facilities. For that purpose, the use of an air sampler is required. A comparison of the collecting efficiency of air samplers has not been studied so far using a single culture medium. Use of the same culture medium is necessary because of the variation of the cultivation efficiency with different culture media. In this study a statistically significant difference in collecting efficiency among air samplers was observed in case of SCDA (soybean casein digest agar) culture medium, but not SCDALP (soybean casein digest agar lecithin polysorbate) culture medium. In addition, a statistically significant difference of the cultivation efficiency was observed between SCDA and SCDALP culture media (P<0.05). These results suggest that any air sampler can be used with SCDALP culture medium.

Air Microbiology↗
PubMed2004

Comparative study on adhesive performance of functional monomers.

Mild self-etch adhesives demineralize dentin only partially, leaving hydroxyapatite around collagen within a submicron hybrid layer. We hypothesized that this residual hydroxyapatite may serve as a receptor for chemical interaction with the functional monomer and, subsequently, contribute to adhesive performance in addition to micro-mechanical hybridization. We therefore chemically characterized the adhesive interaction of 3 functional monomers with synthetic hydroxyapatite, using x-ray photoelectron spectroscopy and atomic absorption spectrophotometry. We further characterized their interaction with dentin ultra-morphologically, using transmission electron microscopy. The monomer 10-methacryloxydecyl dihydrogen phosphate (10-MDP) readily adhered to hydroxyapatite. This bond appeared very stable, as confirmed by the low dissolution rate of its calcium salt in water. The bonding potential of 4-methacryloxyethyl trimellitic acid (4-MET) was substantially lower. The monomer 2-methacryloxyethyl phenyl hydrogen phosphate (phenyl-P) and its bond to hydroxyapatite did not appear to be hydrolytically stable. Besides self-etching dentin, specific functional monomers have additional chemical bonding efficacy that is expected to contribute to their adhesive potential to tooth tissue.

Adhesiveness↗
PubMed2003

Magnetic control of ferroelectric polarization.

The magnetoelectric effect--the induction of magnetization by means of an electric field and induction of polarization by means of a magnetic field--was first presumed to exist by Pierre Curie, and subsequently attracted a great deal of interest in the 1960s and 1970s (refs 2-4). More recently, related studies on magnetic ferroelectrics have signalled a revival of interest in this phenomenon. From a technological point of view, the mutual control of electric and magnetic properties is an attractive possibility, but the number of candidate materials is limited and the effects are typically too small to be useful in applications. Here we report the discovery of ferroelectricity in a perovskite manganite, TbMnO3, where the effect of spin frustration causes sinusoidal antiferromagnetic ordering. The modulated magnetic structure is accompanied by a magnetoelastically induced lattice modulation, and with the emergence of a spontaneous polarization. In the magnetic ferroelectric TbMnO3, we found gigantic magnetoelectric and magnetocapacitance effects, which can be attributed to switching of the electric polarization induced by magnetic fields. Frustrated spin systems therefore provide a new area to search for magnetoelectric media.

Journal Article↗
PubMed2003

Bonding efficacy of polyalkenoic acids to hydroxyapatite, enamel and dentin.

Previously, we introduced a methodology to determine the chemical bonding potential of polyalkenoic acids to mineralized tissues through quantification of the degree of ionic bond formation between the carboxyl groups of a polyalkenoic acid with calcium of hydroxyapatite. In a continuation of that study, we now investigated in how far the chemical bonding potential to synthetic hydroxyapatite is influenced by the molecular structure of the polyalkenoic acid and if this also may affect the self-adhesiveness to enamel and dentin. X-ray photoelectron spectroscopy and inductively coupled plasma atomic emission spectrometry were used to quantitatively analyze the chemical bonding efficacy of a polyalkenoic acid consisting of acrylic acid units (PAA) to synthetic hydroxyapatite (HAp) in comparison to the chemical bonding potential of the previously investigated synthesized polyalkenoic acid (s-PA) co-polymer consisting of 90w/w% acrylic and 10w/w% maleic acid units. In addition, the analysis was carried out for enamel and dentin samples. PAA revealed a significantly lower bonding effectiveness with only half of its carboxyl groups bonded to HAp versus about two-third of the carboxyl groups of s-PA. The difference in bonding potential was confirmed by the considerably lower adhesiveness of PAA to enamel and dentin as compared to that of s-PA The present findings indicate that the molecular structure of the polyalkenoic acid significantly influences the chemical bonding efficacy to Hap-based substrates.

Acrylic Resins↗
PubMed2002

Adhesion/decalcification mechanisms of acid interactions with human hard tissues.

In order to study adhesion/decalcification mechanisms of acid interactions with human hard tissues such as bones and teeth, the chemical interaction of five carboxylic acids (acetic, citric, lactic, maleic, and oxalic) and two inorganic acids (hydrochloric and nitric) with enamel and two synthetic hydroxyapatite (HAp) powders with, respectively, a high and a low crystallinity were analyzed using X-ray photoelectron spectroscopy (XPS), atomic absorption spectrophotometry (AAS), and spectrophotometry (S). X-ray diffraction revealed that the crystallinity of the highly crystallized HAp was considerably higher than that of enamel while the crystallinity of the poorly crystallized HAp was similar to that of dentin and bone. XPS of acid-treated enamel demonstrated for all carboxylic acids ionic bonding to calcium of HAp. AAS and S showed for both HAps that all carboxylic and inorganic acids except oxalic acid extracted Ca significantly more than P, leading to a Ca/P ratio close to that of synthetic HAp (2.16 w/w). Oxalic acid extracted hardly any Ca, but substantially more P, leading to a significantly smaller Ca/P ratio than that of HAp. AAS showed that the calcium salt of oxalic acid hardly could be dissolved, whereas the calcium salts of all the other acids were very soluble in their respective acid solution. These results confirm the adhesion/decalcification concept (AD-concept) previously advanced. Depending on the dissolution rate of the respective calcium salts, acids either adhere to or decalcify apatitic substrates. It is concluded that the AD-concept that originally dictated the interaction of carboxylic acids with human hard tissues can be extended to inorganic acids, such as hydrochloric and nitric acid. Furthermore, HAp crystallinity was found not to affect the adhesion/decalcification behavior of acids when interacting with apatitic substrates, so that the AD-concept can be applied to all human hard tissues with varying HAp crystallinity.

Acids↗
PubMed2002

Improved filler-matrix coupling in resin composites.

Ineffective silane coupling between filler and matrix within dental composites is prone to accelerated in vivo degradation. In this study, we examined to what degree a procedure involving chemical decontamination of filler prior to silanization could improve the filler-matrix bonding, and thus the physico-mechanical properties, of composites. X-ray photoelectron spectroscopy revealed that filler-matrix coupling 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. Pre-silanization decontamination based upon boiling silica in 0.05-5% sodium peroxodisulfate, followed by ultrasonic rinsing in acetone, most effectively decontaminated filler. Consequently, it significantly improved the bonding of silane molecules to silanol groups at the silica surface. Experimental composites produced following pre-silanization decontamination of filler revealed a diametral tensile strength that was resistant to degradation by thermocycling.

Composite Resins↗
PubMed2001

The relationship between leachability of polymerization initiator and degree of conversion of visible light-cured resin.

Recently, polymerization-initiator-induced radicals have been identified as a biohazard as well as residual monomers. The present investigation was conducted to clarify the leaching behavior of the polymerization initiator and to measure the relationship between the leached amount of polymerization initiator and the degree of conversion of visible light (VL)-cured resin. Moreover, determining a suitable ratio of polymerization initiator to the base monomer according to the above relationship was carried out. The base monomer (UDMA/TEGDMA) was activated with varying concentrations of polymerization initiator (CQ/DMPT, CQ/DMAEMA) from 0.3-0.9 wt%, respectively, which were exposed to light for 40 s. Gas chromatograph mass spectrometry (GCMS) was carried out to evaluate the leached amount of polymerization initiator. The degree of conversion (DC) of the cured sample was estimated using attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy. As the result, it was recognized that the leachability of the polymerization initiator (CQ, DMPT, and DMAEMA) depended on the degree of conversion of the VL-cured resin. Therefore, the optimal concentration of polymerization initiator can be determined from the relation between the degree of conversion and the leached amount of polymerization initiator, which is about 0.6 wt% for CQ/DMPT (1:1 in weight) and 0.5 wt% for CQ/DMAEMA (1:1 in weight) relative to the UDMA/TEGDMA (1:1 in weight) monomer.

Dental Cements↗
PubMed2000

Assessment of decontamination methods as pretreatment of silanization of composite glass fillers.

In terms of mechanical properties and durability, the surface of glass fillers should be decontaminated in order to optimize the silanization process for the production of resin composites. The objective of this study was to evaluate the decontamination efficiency of 18 cleaning methods on glass fillers as pretreatment of silane coupling. X-ray photoelectron spectroscopy revealed that SiO(2) boiled with a 5% sodium peroxodisulfate aqueous solution for 15 min, followed by ultrasonic rinsing with acetone for 30 min was most effective among all the decontamination methods investigated. In addition, nano-indentation measurements on SiO(2) treated by the above-mentioned method revealed that the surface was not significantly weakened as compared to untreated SiO(2). The results of this study should lead to an improved filler-matrix coupling and thus contribute to the development of better wear and fatigue-resistant composites. Therefore, sodium peroxodisulfate is proposed as a presilanization filler decontamination step in the production process of resin composites.

Bisphenol A-Glycidyl Methacrylate↗
PubMed2000

Cynomolgus monkey liver aldehyde oxidase: extremely high oxidase activity and an attempt at purification.

Aldehyde oxidase (EC 1.2.3.1) in monkey (Macaca fascicularis) liver was characterized. Liver cytosol exhibited extremely high benzaldehyde and phthalazine oxidase activities based on aldehyde oxidase, compared with those of rabbits, rats, mice and guinea pigs. Monkey liver aldehyde oxidase showed broad substrate specificity distinct from that of the enzyme from other mammals. Purified aldehyde oxidase from monkey liver cytosol showed two major bands and two minor bands in sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). These bands were also observed in Western blotting analysis using anti-rat aldehyde oxidase. The molecular mass of the enzyme was estimated to be 130-151 kDa by SDS-PAGE, and to be about 285 kDa by HPLC gel filtration. The results suggest that isoforms of aldehyde oxidase exist in monkey livers.

Aldehyde Oxidase↗
PubMed2000

Effect of calcium in assay medium on D value of Bacillus stearothermophilus ATCC 7953 spores.

The D value of commercial biological indicator spore strips using Bacillus stearothermophilus ATCC 7953 was increased by higher calcium concentrations in assay media. The calcium concentration in assay media varied among the manufacturers. The calcium concentration in assay media is an important factor to consider to minimize the variation of D value.

Bacteriological Techniques↗
PubMed2000

A case of cigarette smoking-induced acute eosinophilic pneumonia showing tolerance.

It has been proposed that acute eosinophilic pneumonia (AEP), which is characterized by the absence of recurrence, is associated with cigarette smoking (CS), because Japanese patients with AEP are young and have a high incidence of short-term smoking history. However, there has been no direct evidence that CS causes AEP. We hypothesized that tolerance might develop against repeated resumption of smoking cigarettes in CS-induced AEP cases. In this connection, we challenged a patient with CS-induced AEP with repeated resumption of CS, and it was demonstrated that CS induced AEP in conjunction with tolerance to repeated resumption of smoking.

Acute Disease↗
PubMed2000

Acute eosinophilic pneumonia caused by cigarette smoking.

It has been suggested that acute eosinophilic pneumonia (AEP) is associated with cigarette smoking because in Japan, the patients with AEP are young and have a high incidence of short-term smoking history. However, there has been no direct evidence to support that cigarette smoke causes AEP. Herein is reported the first case showing the direct evidence and a long-term clinical course of cigarette smoking-induced AEP, in which tolerance to repeated resumption of smoking cigarettes might have occurred. We should pay attention to the history of cigarette smoking in seeing patients with AEP, especially in young patients.

Adult↗
PubMed2000

Mercury evaporation from amalgams with varied mercury contents.

This study examined the relationship between mercury content and mercury evaporation from amalgams during setting. Two different types of commercial high-copper amalgams (single composition and admixed types) were used. Cylindrical specimens of each amalgam were prepared with five different mercury contents according to ADA Specification No.1. Specimens were also prepared by hand condensation. Mercury evaporation from amalgam specimens maintained at 37 degrees C was measured using a gold film mercury analyzer from 10 min after the end of trituration until the mercury concentration in air reached an undetectable level. The mercury content more clearly influenced the mercury evaporation from the admixed type amalgam specimens when the mercury content decreased below the manufacturers' recommended trituration conditions. Triturating with less mercury than the manufacturers' recommended amount cannot lower the evaporation of mercury from freshly made amalgam. Proper condensing procedures can minimize the mercury evaporation from the amalgam surface.

Chemistry, Pharmaceutical↗