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1.
Hum Reprod ; 37(7): 1423-1430, 2022 06 30.
Artículo en Inglés | MEDLINE | ID: mdl-35640043

RESUMEN

STUDY QUESTION: Is there a relation between specific Na+/K+ ATPase isoform expression and localization in human blastocysts and the developmental behavior of the embryo? SUMMARY ANSWER: Na+/K+ ATPase α1, ß1 and ß3 are the main isoforms expressed in human blastocysts and no association was found between the expression level of their respective mRNAs and the rate of blastocyst expansion. WHAT IS KNOWN ALREADY: In mouse embryos, Na+/K+ ATPase α1 and ß1 are expressed in the basolateral membrane of trophectoderm (TE) cells and are believed to be involved in blastocoel formation (cavitation). STUDY DESIGN, SIZE, DURATION: A total of 20 surplus embryos from 11 patients who underwent IVF and embryo transfer at a university hospital between 2009 and 2018 were analyzed. PARTICIPANTS/MATERIALS, SETTING, METHODS: After freezing and thawing Day 5 human blastocysts, their developmental behavior was observed for 24 h using time-lapse imaging, and the expression of Na+/K+ ATPase isoforms was examined using quantitative RT-PCR (RT-qPCR). The expressed isoforms were then localized in blastocysts using fluorescent immunostaining. MAIN RESULTS AND THE ROLE OF CHANCE: RT-qPCR results demonstrated the expression of Na+/K+ ATPase α1, ß1 and ß3 isoforms in human blastocysts. Isoforms α1 and ß3 were localized to the basolateral membrane of TE cells, and ß1 was localized between TE cells. A high level of ß3 mRNA expression correlated with easier hatching (P = 0.0261). LARGE SCALE DATA: N/A. LIMITATIONS, REASONS FOR CAUTION: The expression of mRNA and the localization of proteins of interest were verified, but we have not been able to perform functional analysis. WIDER IMPLICATIONS OF THE FINDINGS: Of the various Na+/K+ ATPase isoforms, expression levels of the α1, ß1 and ß3 mRNAs were clearly higher than other isoforms in human blastocysts. Since α1 and ß3 were localized to the basolateral membrane via fluorescent immunostaining, we believe that these subunits contribute to the dilation of the blastocoel. The ß1 isoform is localized between TE cells and may be involved in tight junction formation, as previously reported in mouse embryos. STUDY FUNDING/COMPETING INTEREST(S): This work was supported by the JSPS KAKENHI (https://www.jsps.go.jp/english/index.html), grant number 17K11215. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. The authors have no conflicts of interest.


Asunto(s)
Blastocisto , Embrión de Mamíferos , Animales , Blastocisto/metabolismo , Membrana Celular/metabolismo , Embrión de Mamíferos/metabolismo , Humanos , Ratones , ARN Mensajero/metabolismo , ATPasa Intercambiadora de Sodio-Potasio/genética , ATPasa Intercambiadora de Sodio-Potasio/metabolismo
2.
Phys Chem Chem Phys ; 16(33): 17748-55, 2014 Sep 07.
Artículo en Inglés | MEDLINE | ID: mdl-25030078

RESUMEN

We demonstrate one-step gold nanoparticle (AuNP) coating and the surface nitridation of TiO2 nanowires (TiO2-NWs) to amplify visible-light photon reflection. The surface nitridation of TiO2-NW arrays maximizes the anchoring of AuNPs, and the subsequent reduction of the band gap energy from 3.26 eV to 2.69 eV affords visible-light activity. The finite-difference time-domain (FDTD) simulation method clearly exhibits the enhancement in the strengths of localized electric fields between AuNPs and the nanowires, which significantly improves the photocatalytic (PC) performance. Both nitridation and AuNP decoration of TiO2-NWs result in beneficial effects of high (e(-)/h(+)) pair separation through healing of the oxygen vacancies. The combined effect of harvesting visible-light photons and reducing recombination in Au/N-doped TiO2-NWs promotes the photocatalytic activity towards degradation of methyl orange to an unprecedented level, ∼4 fold (1.1 × 10(-2) min) more than does TiO2-NWs (2.9 × 10(-3) min(-1)). The proposed AuNP decoration of nitridated TiO2-NW surfaces can be applied to a wide range of n-type metal oxides for photoanodes in photocatalytic applications.


Asunto(s)
Oro/química , Nanopartículas del Metal/química , Nanoporos/ultraestructura , Nanocables/química , Titanio/química , Catálisis/efectos de la radiación , Oro/efectos de la radiación , Luz , Ensayo de Materiales , Nanopartículas del Metal/efectos de la radiación , Nanocables/efectos de la radiación , Oxidación-Reducción/efectos de la radiación , Dispersión de Radiación , Titanio/efectos de la radiación
3.
Lupus ; 20(8): 871-5, 2011 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-21415254

RESUMEN

Hemophagocytic syndrome (HPS) is a serious complication of systemic lupus erythematosus (SLE). A 15-year-old female with lupus-nephritis developed HPS. Bone marrow study showed florid thrombophagocytosis. There was no associated infection. High-dose methylprednisolone therapy ameliorated HPS. However, atrial fibrillation (Af) repeated after the infusion and required direct-current cardioversion. No underlying diseases were found in the heart and endocrine system. Chest roentgenogram and echocardiography were normal. Electrocardiogram showed slightly prolonged PR interval in sinus rhythm. Af occurred at high circulating levels of interferon-γ and interleukin (IL)-10, but not IL-6, IL-2, tumor necrosis factor-α, C-reactive protein or catecholamines. This is the first observation that high-dose corticosteroid induced Af in a case of lupus-HPS. Af is unusual in SLE children without cardiac disease, while conduction defect occurs associated with lupus-myocarditis. Lupus-HPS may be an aggressive SLE subset with cardiac involvement. High-dose corticosteroid infusion controls lupus activity, but could disclose the cardiac stress in lupus-HPS patients.


Asunto(s)
Fibrilación Atrial/inducido químicamente , Glucocorticoides , Lupus Eritematoso Sistémico , Linfohistiocitosis Hemofagocítica , Metilprednisolona , Adolescente , Médula Ósea/patología , Proteína C-Reactiva/metabolismo , Catecolaminas/sangre , Citocinas/sangre , Femenino , Glucocorticoides/efectos adversos , Glucocorticoides/uso terapéutico , Humanos , Lupus Eritematoso Sistémico/complicaciones , Lupus Eritematoso Sistémico/tratamiento farmacológico , Linfohistiocitosis Hemofagocítica/tratamiento farmacológico , Linfohistiocitosis Hemofagocítica/etiología , Metilprednisolona/efectos adversos , Metilprednisolona/uso terapéutico
4.
Ultrason Sonochem ; 61: 104849, 2020 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-31710997

RESUMEN

The current research work deals with the preparation of TiO2 and GO/TiO2 composite by simple, chemical, cost effective hydrothermal method. Graphene oxide (GO) is prepared by modified Hummer's method. Dispersion of GO is achieved by an ultrasonic cleaning bath for 1 h. using a power of 200 W and at a frequency of 40 kHz. The prepared catalyst material is characterized by different characterization techniques. XRD study confirms the prepared material is polycrystalline in nature. The synthesized TiO2 and GO/TiO2 photocatalyst materials are used to study the photocatalytic degradation of salicylic acid under sunlight illumination. GO/TiO2 composite shows superior photocatalytic activity than TiO2. GO/TiO2 composite shows 57% degradation of salicylic acid. Mineralization of salicylic acid is studied using chemical oxygen demand.

5.
Regul Toxicol Pharmacol ; 54(3): 214-20, 2009 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-19328216

RESUMEN

The safety of LP20 and its prototype, a powder, with potential use in food, produced from a mixture of dextrin and heat-killed Lactobacillus plantarum L-137, was assessed in an acute study in mice, and in an in vitro bacterial reverse mutation assay, an in vitro chromosome aberration assay, and an in vivo mouse micronucleus assay. LP20 prototype was not acutely toxic when administered to male and female Slc:ICR mice by single gavage at 2000mg/kg bw. Dosing was not associated with mortality, clinical signs, changes in bodyweight, or macroscopic abnormalities. The LD(50) in mice was greater than 2000mg/kg bw. There was no evidence of genotoxicity of LP20 in the Ames assay (0-5000microg/plate) or in the in vitro chromosome aberration assay with Chinese hamster lung fibroblasts (0-5000microg/mL). Administration of two consecutive daily doses of 500, 1000, or 2000mg/kg bw by gavage to male Crlj:CD-1 mice was not associated with an increased incidence of micronuclei and did not alter the ratio of polychromatic to normochromatic erythrocytes. These studies show that LP20 powder is not acutely toxic and is without genotoxic activity both in vitro and in vivo.


Asunto(s)
Aditivos Alimentarios/toxicidad , Lactobacillus plantarum , Animales , Cricetinae , Femenino , Técnicas In Vitro , Masculino , Ratones , Ratones Endogámicos ICR , Pruebas de Mutagenicidad , Pruebas de Toxicidad Aguda
6.
J Dent Res ; 87(7): 666-70, 2008 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-18573988

RESUMEN

Ceramic restorations with resin-based adhesive systems have been the focus of recent attention in clinical dentistry. Yttrium-oxide-partially-stabilized zirconia (YPSZ) ceramics have optimized physical properties and exhibit favorable fracture toughness, though their bonding properties are problematic. Although functional phosphate monomers and silica-coating by tribochemical modification were expected to improve the bonding properties between YPSZ ceramics and resin-based adhesives, these two methods remain controversial. This study evaluated the efficiency of silica-coating by tribochemical modification of YPSZ ceramics. The application of phosphate monomer and a silane coupling agent on silica-coated YPSZ was also investigated. The silica-coating of YPSZ ceramics by tribochemical modification was not efficient, given the higher mechanical toughness of the densely sintered ceramics. Stable shear bond strength was achieved on silica-coated YPSZ ceramics with the cooperative interaction of phosphate monomer and silane coupling.


Asunto(s)
Recubrimiento Dental Adhesivo/métodos , Cementos Dentales/química , Porcelana Dental/química , Fosfatos/química , Circonio/química , Cerámica/química , Compómeros/química , Análisis del Estrés Dental , Ensayo de Materiales , Polímeros/química , Cementos de Resina/química , Resistencia al Corte , Cemento de Silicato/química , Propiedades de Superficie
7.
J Phys Chem B ; 110(14): 7409-13, 2006 Apr 13.
Artículo en Inglés | MEDLINE | ID: mdl-16599518

RESUMEN

We report for the first time an experimental application of the concept of a "black body" like reactor to measure quantum yields (Phi) of photochemical reactions in liquid-solid heterogeneous systems. A major advantage of this new method is its simplicity since the fractions of reflected and transmitted light are negligible due to reactor geometry and high optical density of the heterogeneous systems. The average quantum yield of a test reaction (phenol photodegradation) over TiO(2) (Degussa P25) as determined by this method was 0.14, identical to the quantum yield measured earlier for this same reaction under similar conditions by Salinaro and Serpone. We also report the quantum yield of phenol photodegradation over N-doped TiO(2) during photoexcitation at the fundamental absorption band (lambda = 365 nm; Phi = 0.12) and at the N-doping induced extrinsic absorption band (lambda = 436 nm; Phi = 0.08) of the photocatalyst.

8.
Cancer Res ; 52(8): 2346-8, 1992 Apr 15.
Artículo en Inglés | MEDLINE | ID: mdl-1559237

RESUMEN

Photoexcited TiO2 particles can drive various chemical reactions due to their strong oxidizing and reducing ability. To investigate the possible use of this effect for cancer treatment, the antitumor activity of photoexcited TiO2 particles was studied in vitro and in vivo. HeLa cells cultured in vitro were completely killed in the presence of TiO2 (50 micrograms/ml) with 10-min UV irradiation by a 500-W-Hg lamp. In contrast, very little cell death was observed from TiO2 treatment without UV irradiation. Photoexcited TiO2 particles also significantly suppressed the growth of HeLa cells implanted in nude mice, compared with those receiving TiO2 alone or UV irradiation alone. The cell death caused by photoexcited TiO2 particles was significantly protected in the presence of L-tryptophan and catalase. These molecules are quenchers of hydroxyl radicals and scavengers of hydrogen peroxide, respectively, suggesting that the cells were killed by the OH. and H2O2 produced from photoexcited TiO2 particles.


Asunto(s)
Células HeLa/efectos de la radiación , Titanio/farmacología , Animales , Supervivencia Celular , Ensayos de Selección de Medicamentos Antitumorales , Humanos , Hidrógeno/metabolismo , Peróxido de Hidrógeno/metabolismo , Ratones , Ratones Desnudos , Terapia Ultravioleta
9.
Biochim Biophys Acta ; 1201(2): 259-65, 1994 Nov 11.
Artículo en Inglés | MEDLINE | ID: mdl-7947940

RESUMEN

We reported that malignant cells are inactivated by photo-excited TiO2 particles (Cai, R.-X., et al. (1992) Cancer Res. 52, 2346-2348). In the present study, the process of cell death of a human bladder cell line T24 with the irradiated TiO2 was investigated by monitoring the time course change in intracellular calcium concentration ([Ca2+]i) under UV irradiation using calcium fluorescence indicator, fura-2. In the presence of photo-excited TiO2 particles (100 micrograms/ml), [Ca2+]i showed a rapid two-step increase; while in the absence of TiO2, it exhibited only a slight and monotonous increase or maintained a constant level. The rapid elevation of [Ca2+]i in the presence of photo-excited TiO2 particles was caused by the influx of extracellular Ca2+ through the plasma membrane and cell death occurred only after the second rapid elevation of [Ca2+]i. These results suggested that the cell membrane permeability to Ca2+ was promoted prior to cell death.


Asunto(s)
Calcio/análisis , Titanio/farmacología , Permeabilidad de la Membrana Celular , Supervivencia Celular , Etidio , Fura-2 , Humanos , Factores de Tiempo , Titanio/efectos de la radiación , Células Tumorales Cultivadas/efectos de los fármacos , Células Tumorales Cultivadas/ultraestructura , Rayos Ultravioleta
10.
J Mol Biol ; 197(2): 373-4, 1987 Sep 20.
Artículo en Inglés | MEDLINE | ID: mdl-3500318

RESUMEN

Recombinant human interleukin 2 produced by Escherichia coli was purified to homogeneity and crystallized after being separated from methionyl interleukin 2. Crystals suitable for structural studies have been obtained by the seed enlargement technique, using the method of vapor diffusion with ammonium sulfate as the precipitant at pH 4.6. The space group is P2(1)2(1)2 with cell dimensions a = 49.2 A, b = 87.6 A and c = 32.4 A. The asymmetric unit contains one molecule of the protein. From preliminary results, the crystals are moderately stable to X-rays and produce measurable reflections to a resolution of about 2.2 A. The diffraction data for the native crystals have been collected on a diffractometer at 2.4 A resolution.


Asunto(s)
Interleucina-2 , Proteínas Recombinantes , Cristalografía , Humanos
11.
J Mol Biol ; 241(2): 281-2, 1994 Aug 12.
Artículo en Inglés | MEDLINE | ID: mdl-8057369

RESUMEN

Single crystals of the RuvC protein, an Escherichia coli endonuclease specific for Holliday junctions, were grown by the microdialysis method. The crystals belong to the space group P2(1), with unit cell dimensions a = 72.8 A, b = 139.6 A, c = 32.4 A and beta = 93.0 degrees, and contain four molecules in an asymmetric unit. Diffraction data to a Bragg spacing of 2.5 A resolution has been obtained using a synchrotron X-ray source.


Asunto(s)
Proteínas Bacterianas/química , Endodesoxirribonucleasas/química , Proteínas de Escherichia coli , Escherichia coli/metabolismo , Proteínas Bacterianas/genética , Proteínas Bacterianas/aislamiento & purificación , Cristalización , Cristalografía por Rayos X , Reparación del ADN/genética , Endodesoxirribonucleasas/genética , Endodesoxirribonucleasas/aislamiento & purificación , Recombinación Genética
12.
Chem Commun (Camb) ; 51(3): 522-5, 2015 Jan 11.
Artículo en Inglés | MEDLINE | ID: mdl-25412036

RESUMEN

The solar-to-hydrogen generation from the TiO2-CdS-ZnS-MoS2 (TCZM) heterointerface was demonstrated. We found that a Pt-free CdS quantum dot-sensitized TiO2 mesoporous electrode with a metallic-type 1T MoS2 co-catalyst resulted in 0.11 ml cm(-2) h(-1) H2 fuel generation in unassisted potential mode, which was strikingly improved to 1.47 ml cm(-2) h(-1) under 1 V applied potential.

13.
FEBS Lett ; 407(1): 47-50, 1997 Apr 21.
Artículo en Inglés | MEDLINE | ID: mdl-9141479

RESUMEN

We have determined the three dimensional structure of the complex of human cathepsin L and E-64, an irreversible inhibitor of cysteine proteases, at 2.5 A resolution. The overall structure was similar to that of other known cysteine proteases and apparently identical to the mature region of procathepsin L. The electron density for E-64 is clearly visible except for the guanidinobutane moiety. From comparison of the active sites of cathepsin L and B, we found the following: (1) The S' subsites of cathepsin L and B are totally different because of the 'occluding loop' lying on the end of the S' subsites of cathepsin B. (2) The S2 pocket of cathepsin L is shallow and narrow compared to that of cathepsin B. (3) The S3 subsites of the two enzymes are more similar than the other subsites, but cathepsin L may accommodate a more bulky group at this site. Knowledge of the active site structure of cathepsin L should be helpful for the structure-based design of potent and specific inhibitors which are of therapeutic importance.


Asunto(s)
Catepsinas/química , Cisteína Endopeptidasas/química , Inhibidores de Cisteína Proteinasa/química , Endopeptidasas , Leucina/análogos & derivados , Catepsina L , Catepsinas/antagonistas & inhibidores , Catepsinas/genética , Cristalografía por Rayos X , Cisteína Endopeptidasas/genética , Humanos , Leucina/química , Modelos Moleculares , Proteínas Recombinantes/química
14.
J Med Chem ; 42(19): 3982-93, 1999 Sep 23.
Artículo en Inglés | MEDLINE | ID: mdl-10508446

RESUMEN

Cyclic analogues of N-[3,5-bis(trifluoromethyl)benzyl]-7,8-dihydro-N, 7-dimethyl-5-(4-methylphenyl)-8-oxo-1,7-naphthyridine-6-carboxamide (1) having a 6-9-membered ring (6-9) were synthesized and evaluated for NK(1) antagonistic activities. The 8-membered ring compound with a beta-methyl group at the C((9))-position, (aR,9R)-7-[3, 5-bis(trifluoromethyl)benzyl]-8,9,10, 11-tetrahydro-9-methyl-5-(4-methylphenyl)-7H-[1,4]diazocino[2,1-g] [1, 7]naphthyridine-6,13-dione [(aR,9R)-8b], was atropodiastereoselectively synthesized by cyclization of a chiral intermediate, 10g. On the other hand, the 7-membered ring compound with a beta-methyl group at the C((9))-position [(9S)-7b] was obtained as an equilibrium mixture of atropisomers with a ratio of ca. 3:2 in solution at room temperature (measured by NMR in CDCl(3)). Compounds (9S)-7b and (aR,9R)-8b exhibited excellent antagonistic activities both in vitro [IC(50) (inhibition of [(125)I]BH-SP binding in human IM-9 cells) = 0.28 and 0.45 nM, respectively] and in vivo (iv and po). Significantly, the in vitro activity of (aR, 9R)-8b was ca. 750-fold higher than that of its enantiomer (aS, 9S)-8b, ca. 40-fold higher than its atropisomer (aS,9R)-8b, and ca. 20-fold higher than its diastereomer (aR,9S)-8b. The structure-activity relationships in this series, along with the X-ray analysis of (aR,9R)-8b, indicated that the stereochemistry around the -C((6))(=O)-N((7))-CH(2)Ar moiety is important for NK(1) receptor recognition. The NK(1) antagonists showed effects on bladder functions in guinea pigs upon intravenous injection: i.e., the antagonists increased the shutdown time of distension-induced rhythmic bladder contractions and the bladder volume threshold, and the effects on the shutdown time were found to correlate well with the NK(1) antagonistic activities. Compound (aR,9R)-8b has been identified as a potential clinical candidate for the treatment of bladder function disorders.


Asunto(s)
Naftiridinas/química , Naftiridinas/farmacología , Antagonistas del Receptor de Neuroquinina-1 , Vejiga Urinaria/fisiología , Animales , Línea Celular , Cromatografía Líquida de Alta Presión , Cristalografía por Rayos X , Cobayas , Humanos , Espectroscopía de Resonancia Magnética , Modelos Químicos , Modelos Moleculares , Contracción Muscular/efectos de los fármacos , Conformación Proteica , Vejiga Urinaria/efectos de los fármacos
15.
J Med Chem ; 41(22): 4232-9, 1998 Oct 22.
Artículo en Inglés | MEDLINE | ID: mdl-9784098

RESUMEN

A potent and orally active NK1 antagonist, trans-N-[3, 5-bis(trifluoromethyl)benzyl]-7,8-dihydro-N, 7-dimethyl-5-(4-methylphenyl)-8-oxo-1,7-naphthyridine-6-carboxamide (1t), was shown to exist as a mixture of separable and stable (R)- and (S)-atropisomers (1t-A and 1t-B) originating from the restricted rotation around the -C(6)-C(=O)- bond; the antagonistic activities of 1t-A were ca. 6-13-fold higher than those of 1t-B. Analogues of 1t (3), which have (S)- and (R)-methyl groups at the benzylic methylene portion of 1t, were prepared and separated into the diastereomeric atropisomers, 3a-A, 3a-B and 3b-A, 3b-B, in enantiomerically pure forms. Among the four isomers of 3, the (aR, S)-enantiomer (3a-A) exhibited the most potent antagonistic activities with an IC50 value of 0.80 nM (in vitro inhibition of [125I]BH-SP binding in human IM-9 cells) and ED50 values of 9.3 micrograms/kg (iv) and 67.7 micrograms/kg (po) (in vivo inhibition of capsaicin-induced plasma extravasation in guinea pig trachea), while the activity of the (aS,R)-enantiomer (3b-B) was the weakest with an IC50 value of 620 nM. The structure-activity relationships in this series of antagonists indicate that the (R)-configuration at the axial bond and the stacking (or stacking-like) conformation between the two phenyl rings as shown in 1t-A and 3a-A are essential for high-affinity binding and suggest that the amide moiety functions as a hydrogen bond acceptor in the interaction with the receptor.


Asunto(s)
Naftiridinas/química , Antagonistas del Receptor de Neuroquinina-1 , Administración Oral , Animales , Permeabilidad Capilar/efectos de los fármacos , Capsaicina , Línea Celular , Cristalografía por Rayos X , Cobayas , Humanos , Inyecciones Intravenosas , Modelos Moleculares , Conformación Molecular , Naftiridinas/administración & dosificación , Naftiridinas/síntesis química , Naftiridinas/farmacología , Estereoisomerismo , Tráquea/irrigación sanguínea , Tráquea/efectos de los fármacos
16.
Biomaterials ; 18(15): 1051-7, 1997 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-9239467

RESUMEN

Class V cavities were prepared and restored with resin composite containing antibacterial filler powder (Apacider-AW, Ap-AW) using experimental restorations. The restored teeth were incubated in vitro with the cariogenic bacteria Streptococcus mutans IFO 13955. Ground sections were then prepared and examined using macrophotography. Lesions of the outer and inner wall were noted, and the depths of which the lesions penetrated were measured. We found that, in restorations containing 1-5 wt% Ap-AW, caries penetrated the marginal area, while in restorations containing 10 wt% Ap-AW the margin remained free of caries out to a distance of about 1.1 and 1.8 mm on the occlusal and gingival sides, respectively.


Asunto(s)
Resinas Compuestas/farmacología , Caries Dental/prevención & control , Restauración Dental Permanente , Materiales Biocompatibles , Cariostáticos/metabolismo , Cariostáticos/farmacología , Resinas Compuestas/química , Resinas Compuestas/metabolismo , Fuerza Compresiva , Caries Dental/metabolismo , Humanos , Técnicas In Vitro , Propiedades de Superficie , Resistencia a la Tracción
17.
Biomaterials ; 20(9): 839-45, 1999 May.
Artículo en Inglés | MEDLINE | ID: mdl-10226710

RESUMEN

In order to clarify the role of a primer on the adhesion between dental precious metals and resin, surface-enhanced Raman scattering (SERS) technique has been applied to the structural analysis of the adhesive monomer, 6-(N-(4-vinylbenzyl)propylamino)-1,3,5-triazine-2, 4-dithione (VBATDT) adsorbed on colloidal Au surfaces. VBATDT is one of the major components of commercial primers. A mixture of a methanol solution of VBATDT and aqueous Au colloid was illuminated by the 647.1 nm line from a Kr ion laser to obtain the SERS. The most intense peak at 458 cm-1 due to C = S stretching in the Raman spectrum of solid VBATDT disappears completely in the SERS, while all the other peaks due to vinylbenzyl group vibrations remain unchanged. It suggests that some structural change occurs in VBATDT upon adsorption on Au which involves the C = S bonds and that the molecule undergoes thione-thiol-type tautomerization in the adsorption process. The SERS spectrum of a commercial primer containing VBATDT exhibits a similar spectral pattern. The present results lead us to conclude that some specific interactions exist between the sulfur atoms of VBATDT and Au surface to form chemical bond likes, which are effective to improve the bond strength between dental precious metals and resin. The ambivalent properties of the primer, chemical stability in storage and chemical affinity to Au, are also explained by the thione-thiol-type tautomerization of VBATDT on the basis of the spectroscopic evidence.


Asunto(s)
Oro , Triazinas/química , Adhesivos , Adsorción , Coloides , Recubrimiento Dental Adhesivo , Materiales Dentales , Dispersión de Radiación , Espectrometría Raman/métodos , Tensoactivos/química
18.
J Biochem ; 110(3): 360-3, 1991 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-1769963

RESUMEN

We have determined the crystal structures of two types of human basic fibroblast growth factor, the serine analogue and the wild-type, at 1.6 and 2.5 A resolution, respectively. Two good heavy atom derivatives were found and used for multiple isomorphous replacement phasing. The atomic coordinates were refined using the Hendrickson & Konnert program for stereochemically restrained refinement against structure factors. The crystallographic R factors were reduced to 15.3% for the serine analogue structure and 16.0% for the wild-type structure. The serine analogue and wild-type structures have been found to be almost identical, the root-mean-square deviation between the corresponding C alpha atoms being 0.11 A. Their structures are composed of twelve beta-strands forming a barrel and three loops. Their molecules have an approximate threefold internal symmetry and are similar in architecture to that of interleukin-1 beta. A possible heparin-binding site, which comprises five basic residues, Lys119, Arg120, Lys125, Lys129, and Lys135, has been revealed by calculating the electrostatic potential energy.


Asunto(s)
Factor 2 de Crecimiento de Fibroblastos/química , Secuencia de Aminoácidos , Gráficos por Computador , Factor 2 de Crecimiento de Fibroblastos/genética , Humanos , Modelos Moleculares , Conformación Proteica , Serina , Termodinámica , Difracción de Rayos X/métodos
19.
Inorg Chem ; 38(20): 4405-4412, 1999 Oct 04.
Artículo en Inglés | MEDLINE | ID: mdl-11671150

RESUMEN

Two kinds of cobalt-iron cyanides (Rb(0.66)Co(1.25)[Fe(CN)(6)].4.3H(2)O and Co(1.5)[Fe(CN)(6)].6H(2)O) with different electronic structures have been investigated to understand the photoinduced long-range magnetic ordering. Rb(0.66)Co(1.25)[Fe(CN)(6)].4.3H(2)O produces a photomagnetic effect, whereas Co(1.5)[Fe(CN)(6)].6H(2)O does not respond to light. FT-IR and Mössbauer studies revealed that their oxidation states are expressed as Rb(0.66)Co(III)(0.84)Co(II)(0.41)[Fe(II)(CN)(6)] and Co(II)(1.5)[Fe(III)(CN)(6)], respectively. The difference in the oxidation states of the metal atoms in these two compounds has been explained by the Co coordination with H(2)O or CN ligands. In the case of Rb(0.66)Co(1.25)[Fe(CN)(6)].4.3H(2)O, more CN ligands are involved in coordination than expected in the case of Co(1.5)[Fe(CN)(6)].6H(2)O. A charge-transfer (CT) band from Fe(II) to Co(III) is observed at around 550 nm for Rb(0.66)Co(1.25)[Fe(CN)(6)].4.3H(2)O. The magnetism of Rb(0.66)Co(1.25)[Fe(CN)(6)].4.3H(2)O changed from paramagnetic to ferrimagnetic due to the CT from Fe(II) to Co(III) when illuminated at low temperature. The Curie temperature after illumination was 22 K. This metastable state was stable for more than several days at 5 K. The metastable state was restored back to its original one when the sample was heated to 120 K. It is considered that the interconversion proceeded via a pronounced domain formation.

20.
J Chromatogr B Analyt Technol Biomed Life Sci ; 791(1-2): 63-72, 2003 Jul 05.
Artículo en Inglés | MEDLINE | ID: mdl-12798166

RESUMEN

Boron-doped diamond thin film (BDD) electrodes have been used to study the oxidation reactions and to detect leucine-enkephalinamide (LEA) and its metabolites, tyrosine (T), tyrosyl-alanine (TA), tyrosyl-alanine-glycine (TAG) and leucine-enkephalin (LE) using cyclic voltammetry (CV), flow-injection analysis (FIA), and gradient liquid chromatography (LC) with amperometric detection. At diamond electrodes, well-defined and highly reproducible cyclic voltammograms were obtained with signal-to-background (S/B) ratios 5-10 times higher than those observed for glassy carbon (GC) electrodes. The analytical peaks of LC for LEA and its metabolites were well resolved. No deactivation of BDD electrodes was found after several experiments with standard as well as plasma samples, indicating high stability of the electrode. Calibration curves were linear over a wide range from 0.06 to 30 microM with regression coefficients of 0.999 for all compounds. The limits of detection obtained based on a signal-to-noise ratio of 3:1 were 3, 2.2, 2.7, 20 and 11 nM for T, TA, TAG, LE and LEA, respectively. These values were at least one order lower than those obtained at GC electrodes, which has given limits of detection of 22.88, 20.64, 89.57, 116.04 and 75.67 for T, TA, TAG, LE and LEA, respectively. Application of this method to real samples was demonstrated and validated using rabbit serum samples. This work shows the promising use of conducting diamond as an amperometric detector in gradient LC, especially for the analysis of enkephalinamide and its metabolites.


Asunto(s)
Boro/química , Cromatografía Liquida/métodos , Electrodos , Encefalina Leucina/metabolismo , Sensibilidad y Especificidad
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