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The Rare-RI Ring (R3) is a recently commissioned cyclotronlike storage ring mass spectrometer dedicated to mass measurements of exotic nuclei far from stability at Radioactive Isotope Beam Factory (RIBF) in RIKEN. The first application of mass measurement using the R3 mass spectrometer at RIBF is reported. Rare isotopes produced at RIBF-^{127}Sn, ^{126}In, ^{125}Cd, ^{124}Ag, ^{123}Pd-were injected in R3. Masses of ^{126}In, ^{125}Cd, and ^{123}Pd were measured whereby the mass uncertainty of ^{123}Pd was improved. This is the first reported measurement with a new storage ring mass spectrometry technique realized at a heavy-ion cyclotron and employing individual injection of the preidentified rare nuclei. The latter is essential for the future mass measurements of the rarest isotopes produced at RIBF. The impact of the new ^{123}Pd result on the solar r-process abundances in a neutron star merger event is investigated by performing reaction network calculations of 20 trajectories with varying electron fraction Y_{e}. It is found that the neutron capture cross section on ^{123}Pd increases by a factor of 2.2 and ß-delayed neutron emission probability, P_{1 n}, of ^{123}Rh increases by 14%. The neutron capture cross section on ^{122}Pd decreases by a factor of 2.6 leading to pileup of material at A=122, thus reproducing the trend of the solar r-process abundances. The trend of the two-neutron separation energies (S_{2n}) was investigated for the Pd isotopic chain. The new mass measurement with improved uncertainty excludes large changes of the S_{2n} value at N=77. Such large increase of the S_{2n} values before N=82 was proposed as an alternative to the quenching of the N=82 shell gap to reproduce r-process abundances in the mass region of A=112-124.
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The basic properties of a Talbot interferometer implementing pinhole arrays were experimentally and numerically investigated for the improvement of measurement sensitivity of laser wavefront sensors utilized for electron density imaging over discharge plasmas. A numerical simulation using a plane wave decomposition method indicated that the pinhole arrays with a pitch of 300 µm and a pinhole diameter of 150 µm were most suitable for the measurement of the millimetre-scale discharge plasmas, in consideration of the spatial resolution and measurement accuracy. The plane wave decomposition simulation expected that the measurement sensitivity of the 8th-Talbot-length interferometer could be improved by a factor of 4 compared with the previously developed Shack-Hartmann type laser wavefront sensors, which was experimentally verified by the self-image behavior of the pinhole arrays. The Talbot interferometric system was successfully used for electron density imaging over the vacuum arcs generated between a 3-mm gap. The electron density image observed by the Talbot interferometers was in excellent agreement with that visualized by the previously developed Shack-Hartmann sensors. The practical notification for the pinhole array fabrication was also presented.
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The mechanical properties of nerve guide tubes must be taken into consideration when they are being developed. We previously reported the feasibility of using 50:50 tubes in a canine 40mm peroneal nerve defect model, where 50:50 represents the proportion of poly(L-lactic) acid (PLLA) and polyglycolic acid (PGA). The aim of the current study was to show that 50:50 tubes have suitable mechanical properties for repairing long nerve defects. Four types of nerve guide tubes made with PLLA to PGA fiber ratios of 100:0 (i.e. 100% PLLA) (100:0 tube), 50:50 (50:50 tube), 10:90 (10:90 tube), and 0:100 (0:100 tube) were designed and created using a tubular braiding machine. Their mechanical properties were examined in vitro (up to 16 weeks). In compression testing, 50:50 tubes had the highest normalized force value, followed in order by the 100:0, 10:90, and 0:100 tubes up to 8 weeks after immersion. From the point of view of biomechanics and bioresorbability, out of the 4 tube types tested, 50:50 tubes appeared to have the optimal mechanical properties for longer nerve defects.
Assuntos
Implantes Absorvíveis , Materiais Biocompatíveis , Nervos Periféricos/cirurgia , Fenômenos Biomecânicos , Teste de Materiais , Procedimentos Neurocirúrgicos/instrumentação , Procedimentos Neurocirúrgicos/métodos , Ácido Poliglicólico , Desenho de PróteseRESUMO
BACKGROUND: Interleukin (IL) 33, a novel member of the IL-1 family, is produced mainly by epithelial cells and endothelial cells in response to various types of stress, including necrosis. The effects of IL-33 on the immune cells involved in allergic contact dermatitis have recently been revealed in vitro. However, in vivo, the induction mechanism and function of IL-33 are not fully understood. OBJECTIVES: Our objectives were to investigate induction of IL-33 in keratinocytes and to evaluate the functions of IL-33 and its inducers in a murine model of allergic contact dermatitis. MATERIAL AND METHODS: KERTr cells, a human keratinocyte cell line, were cultured with various cytokines, including tumor necrosis factor (TNF) alpha and interferon (IFN) gamma. IL-33 expression was detected using quantitative reverse transcriptase polymerase chain reaction, immunocytochemistry, and Western blotting. The functions of IL-33, TNF-a, and IFN-y in allergic contact dermatitis were evaluated using a murine model. RESULTS: TNF-alpha and IFN-gamma induced expression of IL-33 mRNA and protein in KERTr cells. Blockade of IL-33 attenuated swelling in the ears of the experimental mice. Similar effects were noted for blockade of TNF-alpha and IFN-gamma in these mice. CONCLUSIONS: TNF-alpha and IFN-gamma induce expression of IL-33, and IL-33 produced by keratinocytes contributes to allergic contact dermatitis. Blockade of IL-33, TNF-alpha, and IFN-gamma could represent novel and potent strategies to treat allergic contact dermatitis.
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Dermatite Alérgica de Contato/metabolismo , Interferon gama/metabolismo , Interleucinas/metabolismo , Queratinócitos/metabolismo , Fator de Necrose Tumoral alfa/metabolismo , Animais , Western Blotting , Linhagem Celular , Dermatite Alérgica de Contato/imunologia , Modelos Animais de Doenças , Feminino , Humanos , Imuno-Histoquímica , Interferon gama/imunologia , Interleucina-33 , Interleucinas/imunologia , Queratinócitos/imunologia , Camundongos , Camundongos Endogâmicos C57BL , Fator de Necrose Tumoral alfa/imunologiaRESUMO
OBJECTIVE: To evaluate the effect of adaptive iterative dose reduction (AIDR) on image noise and image quality as compared with standard filtered back projection (FBP) in 320-detector row CT coronary angiography (CTCA). METHODS: 50 patients (14 females, mean age 68 ± 9 years) who underwent CTCA (100 kV or 120 kV, 400-580 mA) within a single heartbeat were enrolled. Studies were reconstructed with FBP and subsequently AIDR. Image noise, vessel contrast and contrast-to-noise ratio (CNR) in the coronary arteries were evaluated. Overall image quality for coronary arteries was assessed using a five-point scale (1, non-diagnostic; 5, excellent). RESULTS: All the examinations were performed in a single heartbeat. Image noise in the aorta was significantly lower in data sets reconstructed with AIDR than in those reconstructed with FBP (21.4 ± 3.1 HU vs 36.9 ± 4.5 HU; p<0.001). No significant differences were observed between FBP and AIDR for the mean vessel contrast (HU) in the proximal coronary arteries. Consequently, CNRs in the proximal coronary arteries were higher in the AIDR group than in the FBP group (p<0.001). The mean image quality score was improved by AIDR (3.75 ± 0.38 vs 4.24 ± 0.38; p<0.001). CONCLUSION: The use of AIDR reduces image noise and improves image quality in 320-detector row CTCA.
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Angiografia Coronária/métodos , Doença da Artéria Coronariana/diagnóstico por imagem , Tomografia Computadorizada Multidetectores/métodos , Adulto , Idoso , Idoso de 80 Anos ou mais , Índice de Massa Corporal , Protocolos Clínicos , Angiografia Coronária/normas , Feminino , Frequência Cardíaca , Humanos , Masculino , Pessoa de Meia-Idade , Tomografia Computadorizada Multidetectores/normas , Variações Dependentes do Observador , Doses de Radiação , Razão Sinal-RuídoRESUMO
The dynamic behavior and kinetics of the structural transformation of supported bimetallic nanoparticle catalysts with synergistic functions in the oxidation process are fundamental issues to understand their unique catalytic properties as well as to regulate the catalytic capability of alloy nanoparticles. The phase separation and structural transformation of Pt(3)Sn/C and PtSn/C catalysts during the oxidation process were characterized by in situ time-resolved energy-dispersive XAFS (DXAFS) and quick XAFS (QXAFS) techniques, which are element-selective spectroscopies, at the Pt L(III)-edge and the Sn K-edge. The time-resolved XAFS techniques provided the kinetics of the change in structures and oxidation states of the bimetallic nanoparticles on carbon surfaces. The kinetic parameters and mechanisms for the oxidation of the Pt(3)Sn/C and PtSn/C catalysts were determined by time-resolved XAFS techniques. The oxidation of Pt to PtO in Pt(3)Sn/C proceeded via two successive processes, while the oxidation of Sn to SnO(2) in Pt(3)Sn/C proceeded as a one step process. The rate constant for the fast Pt oxidation, which was completed in 3 s at 573 K, was the same as that for the Sn oxidation, and the following slow Pt oxidation rate was one fifth of that for the first Pt oxidation process. The rate constant and activation energy for the Sn oxidation in PtSn/C were similar to those for the Sn oxidation in Pt(3)Sn/C. In the PtSn/C, however, it was hard for Pt oxidation to PtO to proceed at 573 K, where Pt oxidation was strongly affected by the quantity of Sn in the alloy nanoparticles due to swift segregation of SnO(2) nanoparticles/layers on the Pt nanoparticles. The mechanisms for the phase separation and structure transformation in the Pt(3)Sn/C and PtSn/C catalysts are also discussed on the basis of the structural kinetics of the catalysts themselves determined by the in situ time-resolved DXAFS and QXAFS.
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Evolution of the Mn K-edge x-ray absorption near edge structure (XANES) in Pr(0.6)Ca(0.4)MnO(3) at pulsed magnetic fields has been investigated. A small enhancement of XANES spectra is detected across the magnetic-field-induced transition from the charge- and orbital-ordered (COO) insulator to ferromagnetic metal at 20 K. It is found that the magnetic-field dependence of the enhancement shows clear hysteresis, as seen in the magnetization with metamagnetic transition, suggesting a significant correlation between the change in the XANES and the field-induced collapse of the COO state. The enhancement of the absorption can be explained by an increase of the 4p density of states due to a reduction of hybridization between the 4p state of the central Mn ion with the core hole and the neighboring Mn 3d state. Local structural change around Mn ions is expected to modify the strength of the hybridization.
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PURPOSE: The aim of this study was to demonstrate the feasibility of body diffusion-weighted (DW) MR imaging in the evaluation of a pancreatic carcinoma. MATERIAL AND METHODS: In nine normal volunteers and in eight patients with pancreatic carcinoma, DW images were obtained on the axial plane scanning with a multisection spin-echo-type single-shot echo planar sequence with a body coil. Moreover, we measured the apparent diffusion coefficient (ADC) value in a circular region of interest (ROI) within the normal pancreas, pancreatic carcinoma, and tumor-associated chronic pancreatitis. RESULTS: On the DW images, all eight carcinomas were clearly shown as high signal intensity relative to the surrounding tissue. The ADC value (x10(-3) mm(2)/s) in the carcinoma was 1.44 +/- 0.20, which was significantly lower compared to that of normal pancreas (1.90 +/- 0.06) and tumor-associated chronic pancreatitis (2.31 +/- 0.18). CONCLUSION: Diffusion-weighted (DW) images can be helpful in detecting the pancreatic carcinoma and accessing the extent of the tumor.
Assuntos
Adenocarcinoma/diagnóstico , Imagem de Difusão por Ressonância Magnética , Neoplasias Pancreáticas/diagnóstico , Adenocarcinoma/patologia , Idoso , Estudos de Viabilidade , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Neoplasias Pancreáticas/patologiaRESUMO
We report (11)B and (195)Pt NMR measurements in noncentrosymmetric superconductor Li(2)Pt(3)B. We find that the spin susceptibility measured by the Knight shift remains unchanged across the superconducting transition temperature T(c). With decreasing temperature (T) below T(c), the spin-lattice relaxation rate 1/T(1) decreases with no coherence peak and is in proportion to T3. These results indicate that the Cooper pair is in the spin-triplet state and that there exist line nodes in the superconducting gap function. They are in sharp contrast to those in the isostructural Li(2)Pd(3)B which is a spin-singlet, s-wave superconductor, and are ascribed to the enhanced spin-orbit coupling due to the lack of spatial inversion symmetry. Our finding points to a new paradigm where exotic superconductivity arises in the absence of electron-electron correlations.
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The effects of saline pushing after contrast material injection were investigated as well as the possibility for this technique to reduce contrast material doses in liver CT examinations. 52 patients were divided randomly into three groups: 100 ml of contrast material (300 mg I ml(-1)) only (A; n = 19), 100 ml of contrast material pushed with 50 ml of saline solution (B; n = 17), and 85 ml of contrast material pushed with 50 ml of saline solution (C; n = 16). Single-level images were obtained at the level of the main portal vein after the initiation of contrast material injection. There were no significant differences in the mean peak enhancement values (PE) and the mean time to peak enhancement values (TPE) of the aorta between the three groups. The mean PE of the portal vein in group B increased 21 HU over that in group A (p<0.05), and there was no significant difference between groups A and C. The mean PE of the liver in group B increased 7 HU over that in group A (p<0.05), and there was no significant difference between groups A and C. The mean TPE of the portal vein was shorter by 4 s (p<0.05), and that of the liver was shorter by 5 s (p<0.05) in group C compared with those in group A. In conclusion, saline pushing increases the enhancement values of the portal vein and liver, and allows a contrast material dose reduction of 15 ml without decreasing hepatic and vascular enhancement at adequate scan timing.
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Aorta Abdominal/diagnóstico por imagem , Meios de Contraste/administração & dosagem , Fígado/diagnóstico por imagem , Veia Porta/diagnóstico por imagem , Cloreto de Sódio/administração & dosagem , Tomografia Computadorizada por Raios X/métodos , Adulto , Idoso , Aorta Abdominal/metabolismo , Meios de Contraste/farmacocinética , Esquema de Medicação , Feminino , Humanos , Iopamidol/administração & dosagem , Iopamidol/análogos & derivados , Iopamidol/farmacocinética , Fígado/metabolismo , Neoplasias Hepáticas/diagnóstico por imagem , Neoplasias Hepáticas/secundário , Masculino , Pessoa de Meia-Idade , Veia Porta/metabolismoRESUMO
The F(1) hybrid of autoimmune hemolytic anemia-prone NZB and nonautoimmune NZW strains of mice has been studied as a murine model of systemic lupus erythematosus. Both NZB and F(1) hybrid mice show age-dependent spontaneous activation of peripheral CD4(+) T cells as reflected by the elevated frequencies of CD4(+) T cells positive for CD69 early activation marker. Both strains also show age-dependent abnormal decrease of the frequencies of CD62L(+) naive CD4(+) T cells and/or NTA260(+) memory CD4(+) T cells in the spleen. We studied the multigenic control of these abnormal features of peripheral CD4(+) T cells in (NZB x NZW) F(1) x NZW backcross mice by quantitative trait loci mapping and by association rule analysis. The abnormally elevated frequencies of CD69(+)CD4(+) T cells and decreased frequencies of CD62L(+) naive and/or NTA260(+) memory CD4(+) T cells were under the common genetic control, in which the interaction between MHC and a hitherto unknown locus, designated Sta-1 (spontaneous T-cell activation) on chromosome 12, plays a major role. The allelic effects of these loci likely predispose CD4(+) T cells to the loss of self-tolerance, and are responsible for the accelerated autoimmune phenotypes of (NZB x NZW) F(1) hybrid mice.
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Autoimunidade/genética , Lúpus Eritematoso Sistêmico/genética , Lúpus Eritematoso Sistêmico/imunologia , Ativação Linfocitária/genética , Linfócitos T Auxiliares-Indutores/imunologia , Fatores Etários , Animais , Anticorpos Monoclonais/imunologia , Antígenos CD/metabolismo , Antígenos de Diferenciação de Linfócitos T/metabolismo , Mapeamento Cromossômico , Cruzamentos Genéticos , Citometria de Fluxo , Selectina L/metabolismo , Lectinas Tipo C , Camundongos , Camundongos Endogâmicos NZB , Repetições de Microssatélites/genética , Locos de Características Quantitativas/genética , Baço/metabolismo , Linfócitos T Auxiliares-Indutores/metabolismoAssuntos
Gastrectomia/métodos , Imageamento Tridimensional , Neoplasias Gástricas/diagnóstico por imagem , Neoplasias Gástricas/cirurgia , Tomografia Computadorizada Espiral , Interface Usuário-Computador , Brometo de Butilescopolamônio , Meios de Contraste , Humanos , Laparoscopia , Metástase Linfática/diagnóstico por imagem , Interpretação de Imagem Radiográfica Assistida por Computador , Estômago/irrigação sanguínea , Neoplasias Gástricas/patologiaRESUMO
Laparoscopic colorectal surgery has been attracting attention for its capacity to improve the quality of life (QOL) of patients. However, there are disadvantages to this approach, namely, it is difficult to obtain an image of the entire view of the operative field, and organs and lesions cannot be manipulated directly by the surgeon during surgery. For this reason, it takes a relatively large amount of time to ligate vessel, which can vary between patients. Furthermore, vessels and organs can be damaged during lymph nodes dissection under laparoscopic guidance, leading to heavy bleeding that prevents the surgeon from having access to a good view of the operative field. Then, to assess preoperatively the vascular anatomy, we carried out multiphase, contrast-enhanced examinations using multidetector-row CT (MDCT) on patients with colorectal cancer, and prepared the fused image of 3D images of arteries, veins, the colorectum, organs, and tumor. We called the utilization of 3D imaging virtual CT colectomy, which contributed to rapid and safe manipulation of the origins of the arteries and the veins, as well as lymph nodes dissection, without incurring injury to the involved arteries and veins.
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Colectomia/métodos , Colonografia Tomográfica Computadorizada , Imageamento Tridimensional/métodos , Laparoscopia/métodos , HumanosRESUMO
Phenylketonuria (PKU) is an autosomal recessive genetic disease caused by the defects in the phenylalanine hydroxylase (PAH) gene. Individuals homozygous for defective PAH alleles show elevated levels of systemic phenylalanine and should be under strict dietary control to reduce the risk of neuronal damage associated with high levels of plasma phenylalanine. Researchers predict that plant phenylalanine ammonia-lyase (PAL), which converts phenylalanine to nontoxic t-cinnamic acid, will be an effective therapeutic enzyme for the treatment of PKU. The problems of this potential enzyme therapy have been the low stability in the circulation and the antigenicity of the plant enzyme. Recombinant PAL originated from parsley (Petroselinum crispum) chemically conjugated with activated PEG2 [2,4-bis(O-methoxypolyethyleneglycol)-6-chloro-s-triazine] showed greatly enhanced stability in the circulation and was effective in reducing the plasma concentration of phenylalanine in the circulation of mice. PEG-PAL conjugate will be an effective therapeutic enzyme for the treatment of PKU.
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Fenilalanina Amônia-Liase/administração & dosagem , Fenilalanina/sangue , Fenilalanina/efeitos dos fármacos , Fenilcetonúrias , Polietilenoglicóis/química , Animais , Ativação Enzimática/fisiologia , Feminino , Camundongos , Camundongos Endogâmicos BALB C , Petroselinum/enzimologia , Fenilalanina Amônia-Liase/química , Fenilcetonúrias/sangue , Proteínas Recombinantes/administração & dosagem , Proteínas Recombinantes/química , Relação Estrutura-Atividade , Fatores de TempoRESUMO
We present a rare case of perineal-onset Fournier's gangrene in a patient undergoing hemodialysis. A 51-year-old Japanese man manifested an acute-onset perineal pain with perirectal abscess; subsequently, the pain extended to the abdomen, chest, and loin despite quick treatment. His consciousness deteriorated to delirium and he died of septic shock on the third day of admission. Computed tomography (CT) revealed soft-tissue air along the right rectal wall, moreover, the infection extended to the anterior wall of the bladder and the right peripsoas muscle. On the basis of the clinical course and CT findings, the patient was diagnosed as having the complications of Fournier's gangrene, however, no scrotal lesions were detected. Fournier's gangrene is considered to be easily diagnosed on the basis of skin lesions, such as scrotal erythema and swelling. However, in the early stage, the diagnosis of Fournier's gangrene is difficult in a patient with perineal pain before the detection of skin lesions. In conclusion, definitely the key to improving the prognosis of this fulminant infection is the prompt recognition of the pathological process. Therefore, Fournier's gangrene should always be considered when patients undergoing hemodialysis manifest perirectal disorders, even when no scrotal lesions are detected, because there is the possibility of intra-abdominal and intra-retroperitoneal infections resulting in septic shock.
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Gangrena de Fournier/complicações , Neuralgia/etiologia , Períneo , Diálise Renal , Abscesso/complicações , Abscesso/diagnóstico por imagem , Evolução Fatal , Gangrena de Fournier/diagnóstico por imagem , Humanos , Falência Renal Crônica/terapia , Masculino , Pessoa de Meia-Idade , Neuralgia/diagnóstico por imagem , Doenças Retais/complicações , Doenças Retais/diagnóstico por imagem , Índice de Gravidade de Doença , Tomografia Computadorizada por Raios XRESUMO
To clarify the aspects and role of oropharyngeal closure, soft palate movements during sucking were observed and then assessed by electromyographic and fluoroscopic analyses. Three patterns of sucking movements by the palatoglossus and levator veli palatini muscles were analyzed with electromyographic means in seven healthy adults. Furthermore, a forced sucking maneuver, which required special effort to produce a strong sucking pressure by opening the jaw, was analyzed using lateral fluoroscopy in three of the subjects. During all tested sucking movements, the palatoglossus muscle showed continuous activity. The levator veli palatini muscle did not show remarkable activity during regular air sucking or water sucking when water was held in the oral cavity. However, its participation increased when intraoral sucking pressure was increased by opening the jaw, and lateral fluoroscopic examinations revealed that the soft palate was pulled toward the oral cavity to form a tight contact between the rostral portion of the soft palate and the retrotongue, causing the soft palate to make an "L" shape. The palatoglossus muscle plays a major role in palatal movement during sucking. Furthermore, the levator veli palatini muscle, whose activity was observed only during high-pressure sucking with an open jaw, may act to maintain tension in the soft palate against strong negative pressure in the oral cavity.
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Movimento/fisiologia , Palato Mole/fisiologia , Comportamento de Sucção/fisiologia , Adulto , Eletromiografia , Fluoroscopia , Humanos , Masculino , Palato Mole/diagnóstico por imagem , Valores de ReferênciaRESUMO
We studied the binding properties of KRH-594, a new selective antagonist of angiotensin II (AII) type 1 (AT1) receptors, to rat liver membranes and to recombinant AT1 and AT2 receptors. Preincubation of rat liver membranes with KRH-594 produced maximal inhibition of [125I]-AII binding when the preincubation time was 1-2 h. Preincubation with KRH-594 for 2 h decreased the B(max) value and increased the Kd value. For human AT1, human AT2, rat AT1A and rat AT1B receptors, the Ki values for KRH-594 were 1.24, 9360, 0.67, and 1.02 nm, respectively. The rank order of K1 values for human AT1 receptors was KRH-594 >> EXP3174 > candesartan = AII. The order of specificities for human AT1 and AT2 receptors was candesartan > EXP3174 > KRH-594. Although a 2-h preincubation of human AT2 receptors with KRH-594 (30 microM) or CGP 42112 (a selective AT2 receptor antagonist; 0.3 nM) inhibited binding of [125I]-AII, the suppression by KRH-594 was not significant. These results indicate that KRH-594 binds potently to AT1 receptors in an insurmountable manner, and that at a very high dose (30 microM) it may also bind to AT2 receptors, but in a surmountable manner.
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Angiotensina II/antagonistas & inibidores , Antagonistas de Receptores de Angiotensina , Tetrazóis/farmacologia , Tiadiazóis/farmacologia , Animais , Benzimidazóis/farmacologia , Compostos de Bifenilo , Células COS , Chlorocebus aethiops , Relação Dose-Resposta a Droga , Humanos , Imidazóis/farmacologia , Técnicas In Vitro , Fígado/efeitos dos fármacos , Fígado/metabolismo , Losartan/farmacologia , Membranas , Oligopeptídeos/farmacologia , Ensaio Radioligante , Ratos , Ratos Sprague-Dawley , Receptor Tipo 1 de Angiotensina , Receptor Tipo 2 de Angiotensina , Receptores de Angiotensina/genética , Receptores de Angiotensina/metabolismo , Fatores de Tempo , TransfecçãoRESUMO
We succeeded in the detection of the sitting-atop (SAT) copper(II) complex of TPP (5,10,15,20-tetraphenylporphyrin) in acetonitrile (AN) as a solvent with a very low Brønsted basicity, where two pyrrolenine nitrogens in the Cu(II)-SAT complex coordinate to the metal ion and two protons still remain on the pyrrole nitrogens. The structure parameters around the copper(II) ion in the Cu(II)-SAT complex, as determined by a fluorescent EXAFS method, suggest an axially elongated and equatorially distorted six-coordinate geometry. We measured the rates of the formation reaction of the SAT complexes for a series of transition metal(II) ions in AN using the stopped-flow technique. We propose the mechanism where there is a rapid deformation equilibrium of the porphyrin ring prior to the rate-determining step of the bond rupture of a coordinated solvent molecule on the metal(II) ion. Furthermore, we measured the rates of the deprotonation reaction of the Cu(II)-SAT complex by some Brønsted bases and indicated that the rate-determining step is the attack of the base on the proton of the pyrrole nitrogen in the SAT complex. Finally, a unified mechanism relevant to the porphyrin metalation mechanism has been proposed.
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Metais/química , Porfirinas/química , CinéticaRESUMO
The formation of the sitting-atop (SAT) complexes of 5,10,15,20-tetraphenylporphyrin (H(2)tpp), 5,10,15,20-tetrakis(4-chlorophenyl)porphyrin (H(2)t(4-Clp)p), 5,10,15,20-tetramesitylporphyrin (H(2)tmp), and 2,3,7,8,12,13,17,18-octaethylporphyrin (H(2)oep) with the Cu(II) ion was spectrophotometrically confirmed in aqueous acetonitrile (AN), and the formation rates were determined as a function of the water concentration (C(W)). The decrease in the conditional first-order rate constants with the increasing C(W) was reproduced by taking into consideration the contribution of [Cu(H(2)O)(an)(5)](2+) in addition to [Cu(an)(6)](2+) to form the Cu(II)-SAT complexes. The second-order rate constants for the reaction of [Cu(an)(6)](2+) and [Cu(H(2)O)(an)(5)](2+) at 298 K were respectively determined as follows: (4.1 +/- 0.2) x 10(5) and (3.6 +/- 0.2) x 10(4) M(-1) s(-1) for H(2)tpp, (1.15 +/- 0.06) x 10(5) M(-1) s(-1) and negligible for H(2)t(4-Clp)p, and (4.8 +/- 0.3) x 10(3) and (1.3 +/- 0.3) x 10(2) M(-1) s(-1) for H(2)tmp. Since the reaction of H(2)oep was too fast to observe the reaction trace due to the dead time of 2 ms for the present stopped-flow technique, the rate constant was estimated to be greater than 1.5 x 10(6) M(-1) s(-1). According to the structure of the Cu(II)-SAT complexes determined by the fluorescent XAFS measurements, two pyrrolenine nitrogens of the meso-substituted porphyrins (H(2)tpp and H(2)tmp) bind to the Cu(II) ion with a Cu-N(pyr) distance of ca. 2.04 A, while those of the beta-pyrrole-substituted porphyrin (H(2)oep) coordinate with the corresponding bond distance of 1.97 A. The shorter distance of H(2)oep is ascribed to the flexibility of the porphyrin ring, and the much greater rate for the formation of the Cu(II)-SAT complex of H(2)oep than those for the meso-substituted porphyrins is interpreted as due to a small energetic loss at the porphyrin deformation step during the formation of the Cu(II)-SAT complex. The overall formation constants, beta(n), of [Cu(H(2)O)(n)()(an)(6)(-)(n)](2+) for the water addition in aqueous AN were spectrophotometrically determined at 298 K as follows: log(beta(1)/M(-1)) = 1.19 +/- 0.18, log(beta(2)/M(-2)) = 1.86 +/- 0.35, and log(beta(3)/M(-3)) = 2.12 +/- 0.57. The structure parameters around the Cu(II) ion in [Cu(H(2)O)(n)(an)(6-n)](2+) were determined using XAFS spectroscopy.
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A reversed pedicled venous flap containing perivenous areolar tissue and/or nerve was used to cover traumatic skin defects of seven fingers in six patients. The series consisted of six men, ranging in age from 20 to 57 years (average: 39 years). The reconstructed sites were four dorsal skin defects and three volar skin defects of the finger. The flap was designed on the dorsum of the hand, in such a way as to place a vein at the centre of the flap and not to involve the dorsal metacarpal artery. The flap contained a dorsal vein, perivenous areolar tissue and fascia of the interosseous muscle. Cutaneous nerves were present in three of the seven flaps. The pedicle of the flap was dissected distally to the finger web space and the flap was transferred to the skin defect. The size of the flap ranged from 1.4x4.5 cm to 6.0x7.0 cm. The average length of the pedicle was 1.6 cm. Skin grafting was needed at the donor site in one case (flap size: 6.0x7.0 cm), but primary closure was possible in the remaining cases. Postoperatively, the largest flap showed superficial necrosis, although it survived. The remaining flaps survived completely. This suggests that in a large flap the skin should be attached to the pedicle to prevent congestion. The flap can be elevated without reference to the dorsal metacarpal artery at the ulnar side of the dorsum of the hand. The flap is an effective option to reconstruct skin defects of the finger, especially the little finger.