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Biomedical subjects

Y Kadoma

Publications and source records attributed to Y Kadoma.

At least 55 records · Page 3Linked to original sources
PubMed1988

1H and 13C NMR studies of the interaction of eugenol, phenol, and triethyleneglycol dimethacrylate with phospholipid liposomes as a model system for odontoblast membranes.

To clarify the mechanism of the interaction of eugenol with odontoblast membranes compared with that of phenol and triethyleneglycol dimethacrylate (TEGDMA), we employed dipalmitoylphosphatidylcholine (DPPC) liposomes as a model system for odontoblast membranes. 1H and 13C nuclear magnetic resonance spectroscopy (NMR) was used as the spectroscopic approach in the study of this interaction. No signals of 1H and 13C due to eugenol in the DPPC/eugenol liposomes were observed, indicating that the mobility of eugenol was strongly disturbed by DPPC and that eugenol did not diffuse from the liposomes once it was incorporated. The change in chemical shifts due to phenol between the free state and the DPPC/phenol liposomes was not found, indicating that phenol resides in the aqueous phase or near the surfaces of liposomes, its interaction being markedly weaker than that of eugenol. The signals due to TEGDMA in the DPPC/TEGDMA liposomes were split into two peaks: a lower-field peak (free TEGDMA) and a higher-field one (membrane-bound TEGDMA). TEGDMA with ethyleneglycol groups seemed to be activated on the liposomes as a surfactant-like agent.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1987

A calorimetric study of the interaction of synthetic phospholipid liposomes with lipid-soluble small molecules used as dental materials and devices.

The interaction of 22 lipid-soluble small molecules, widely used in dental materials and devices, with synthetic phospholipid liposomes, was investigated by the application of differential scanning calorimetry (DSC), in order to clarify the mechanism of small molecules in biological systems. Dimyristoyl phosphatidyl choline (DMPC) and dipalmitoyl phosphatidyl choline (DPPC) were used as lipids. The interaction of various monomers with liposomes has been reported by us in this journal. In this experiment, various compounds such as redox-initiator, photo-initiator or photo-sensitizer, inhibitor, root-canal disinfectant, cement-base materials (eugenol and 2-ethoxybenzoic acid) etc., were investigated. From changes in the phase transition temperature (T), enthalpy (delta H kcal mol-1) and H/HHW values of both DMPC and DPPC liposomes induced by these molecules, it was concluded that aromatic tertiary amine, benzoyl peroxide and hydroquinone monomethyl ether had a relatively large effect on liposomes, and that in phenol derivatives, m-cresol and p-chlorophenol had a large effect on liposomes compared to phenol. Eugenol used as dental cement also had a large effect on liposomes due to its high hydrophobicity. Changes in the transition properties of liposomes induced by small molecules (characterized by shift of T to a lower temperature, an increase or decrease in cooperativity (H/HHW), and a decrease in delta H of a endothermic peak) seemed to be related to biological activities.

Calorimetry, Differential Scanning↗
PubMed1987

Incorporation into human enamel of fluoride slowly released from a sealant in vivo.

Fluoride incorporation into human enamel from an experimental sealant resin in vivo was investigated. The sealant consisted of a newly synthesized methacryloyl fluoride-methyl methacrylate (MF-MMA) copolymer resin, which contains acidic fluoride covalently bonded to carbonyl groups and releases fluoride ions slowly by hydrolysis in an aqueous environment. This experimental sealant was applied to the enamel of permanent pre-molars and the control sealant without MF-MMA copolymer to that of the contralateral teeth. Fluoride concentration was determined by an enamel biopsy procedure with acid-etching four weeks after the sealant application. As much as 3500 ppm fluoride was found to be deposited at 10 microns depth in the enamel under the MF-MMA copolymer sealant. The increase in fluoride concentration was significant even at 60 microns. Of the fluoride incorporated into the enamel, from 70 to 80% was present as a tightly bound form. This resin sealant is expected to protect the enamel from caries attack even after detachment of the sealant.

Boranes↗
PubMed1986

Effects of photoinitiators for the visible-light resin system on hemolysis of dog erythrocytes and lipid peroxidation of their components.

The visible-light (VL) polymerizing resin system with photoinitiators (photosensitizer and reducing agent) is widely used in modern dentistry. In this system, polymerization is initiated by photochemical reactions between the photosensitizers (aromatic or aliphatic ketones) and reducing agents (tertiary amines) during VL irradiation. In order to simulate the VL resin-induced toxicity in dental pulps, the present investigation was conducted to determine whether hemolysis of dog erythrocytes and lipid peroxidation of their components occur on exposure to a VL resin system containing aromatic (9-fluorenone, benzil) or aliphatic ketones (camphoroquinone) plus tertiary amine [2-(dimethylamino) ethyl methacrylate]. It was demonstrated that the hemolysis and lipid peroxidation with aromatic ketones were markedly higher than with those of aliphatic ketones, even when the latter were used at higher concentrations. It was clear that peroxidation-induced hemolysis occurred and, further, that surface-active complexes between photosensitizers and reducing agents, which are formed by irradiation, promote hemolytic activity due to their hydrophobic interactions. VL resin-induced responses to dental pulps are probably promoted due to the double effects of unpolymerized monomers and of both radicals and surface-active complexes formed during irradiation.

Animals↗
PubMed1985

Current status of release of fluoride ions and other bioactive agents from dental materials: prospects for controlled release.

Many kinds of intraoral systems of bioactive agents have been developed. The cariostatic effect of fluoride ions on enamel caries has been demonstrated through numerous clinical studies. In order to maximize the exposure time of fluoride on enamel for improved prevention of dental caries, fluoride compounds were incorporated into various dental materials and other fluoride-releasing devices were made. The application of fluoride-releasing system is accepted as one of effective caries-preventing procedures. The release of other bioactive agents such as antimicrobial agents (antibiotics, chrorhexidines, eugenols, o-ethoxybenzoic acids and nystatins, etc.) and antiinflammatory agents (benzydamine HCl and steroids) from dental materials and devices have also been investigated. In this article, current status of these systems is reviewed and the therapeutic applicabilities are evaluated.

Adhesives↗
PubMed1983

Studies on dental fluoride-releasing polymers. IV: Fluoridation of human enamel by fluoride-containing sealant.

An experimental fluoride-containing acrylic sealant was prepared using methacryloyl fluoride-methyl methacrylate copolymer as powder component. The in vitro fluoride acquisition by human enamel coated with the sealant after 11, 21, 41 and 84 days of incubation in a phosphate buffer of pH7 at 37 degrees C was determined. Fluoride penetration and uptake were increased by prolonging the exposure time of enamel to the sealant. Most of the fluoride retained in enamel was found to be present as fluorapatite. The discharge of fluoride in the sealant was about 12% of initial load after 84 days of immersion.

Apatites↗
PubMed1983

Action of drugs on liposomes with varying charges.

The effects of 12 amphipathic compounds--such as aromatic and aliphatic carboxylic acids, amines, imines, nitrogen-substituted derivatives, and aldehydes--on multilamellar liposomes with varying charges were monitored in biological systems. The stabilization-lysis action of amphipathic compounds on liposomes was influenced by either the electrostatic repulsion or the attraction force between these compounds and liposomes.

Aldehydes↗
PubMed1983

Nuclear magnetic resonance spectroscopic studies of the interaction of phospholipids with stabilizing lysosome agents.

The interaction between phospholipids and stabilizing lysosome agents such as acetylsalicylic acid (ASA), colchicine (CC), prednisolone (PD), etc., was studied using NMR spectroscopy. The peak intensity of protons arising from these compounds was reduced in liposomes containing lecithin and various agents with a molar ratio of 1:1 in D2O. The reduced percentage of protons in the agents differed due to their molecular structures: ASA was about 20%, CC about 30%, and PD about 100%.

Aspirin↗