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Co-Ni alloy nanoparticles, a potential candidate for microwave absorption material, were successfully synthesized by tuning the reduction timing of Co and Ni ions by introducing oleylamine as a complexing agent and 1-heptanol as a reducing solvent. The formation mechanism elucidated using time-resolved sampling and in situ X-ray absorption spectroscopy (XAS) and ultraviolet-visible (UV-vis) spectrophotometry measurements suggested that the delay in the reduction of Co ions via complexation with oleylamine facilitated the co-reduction of Co with Ni ions and led to the formation of Co-Ni alloys. The successful synthesis of Co-Ni alloys experimentally confirmed the differences in magnetic properties between alloy and core-shell structured Co50Ni50 particles. Further, the syntheses of Co-Ni alloys with different compositions were also possible using the above technique. In addition, the microwave absorption properties were measured using the free-space method utilizing a vector network analyzer of Co50Ni50âpolyethylene composite with different sheet thicknesses. A reflection loss (RL) value of -25.7 dB at 13.6 GHz for the alloy structure was more significant than the core-shell counterpart. The above values are high compared to results reported in the past. The validity of the measurements was confirmed by utilizing the parameter retrieval method to extract permittivity and permeability from the scattering parameter (S) and recalculation of the RL as a function of frequency.
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Bimetallic nanomaterials have attracted much attention from various fields such as catalysis, optics, magnetism, and so forth. The functionality of such particles is influenced very much by the intermetallic interactions than their individual contribution. However, compared with the synthesis of monometallic nanoparticles, the reaction parameters that need to be controlled for tuning the size, shape, composition, and crystal structure of bimetallic nanoparticles becomes challenging. This study focuses on synthesizing of bimetallic nanostructures using the alcohol reduction method, where the control over the reducing power is conceivable by varying the combination of the alcohol type, complexing agent, and metal salts. Consequently, various Cu-Co nanostructures such as Cu-Co core-shell (size ranged between 40 and 15 nm) and hollow alloy nanoparticles and nanotubes were successfully synthesized by incorporating diffusion and etching phenomena during the reduction reaction. Moreover, time-resolved sampling revealed that the formation of a Cu-Co alloy hollow nanostructure has been realized by the diffusion of the Cu core into the Co shell by controlling the reduction time gap between Cu and Co and the crystal structure besides the reduction sequences. It should be noted that the synthesis of a high-temperature (â¼1300 °C) Cu-Co alloy phase was carried out at 170 °C. Among the Cu-Co alloy nanostructures, Cu-Co hollow alloy nanoparticles exhibited enhanced catalytic activity compared to metallic Cu and other Cu-Co nanostructures from the degradation reaction of methylene blue. The enhanced catalytic performance was considered to be mainly due to the alloy structure.
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Development of a technology for the synthesis of monometallic or multimetallic nanoparticles is exceptionally vital for the preparation of novel magnetic, optical. and catalytic functional materials. In this context, the polyol process is a safe and scalable method for preparation of metal nanoparticles with controlled sizes and shapes in large scales. However, there is no systematic investigation that discusses the criteria for the selection of metal salt and solvent type that determine the kinetics of reduction reaction that influences the morphology of the particles. Consequently, the design of metallic nanoparticles, which is controlled by the kinetics and thermodynamics of the reduction reaction, has become difficult. In this paper, the selection criterion for metal salt precursor is established based on the presumption that the ligand of the metal precursor promotes the formation of active species of the solvent, and the criterion for the selection of the solvent type is based on the highest occupied molecular orbital (HOMO) energy value estimated using molecular orbital theory. The results suggested that the dissociation constants of metal salt precursors and HOMO energy of the polyol solvent can be tuned to control the kinetics of the reduction reaction. The reduction potential of polyol depends on the number of carbon atoms and the location of hydroxyl ligands within the molecule. Among the polyols considered in this study, 1,4-butanediol had the highest reduction potential. The predictions have been experimentally verified by synthesizing metallic Co and Fe nanoparticles. The findings could be extended to other techniques such as thermal decomposition and alcohol reduction for the synthesis of noble metal-transition metal magnetic and catalytic nanoparticles with novel properties.
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Recently, the development of bimetallic nanoparticles with functional properties has been attempted extensively but with limited control over their morphological and structural properties. The reason was the inability to control the kinetics of the reduction reaction in most liquid-phase syntheses. However, the alcohol reduction technique has demonstrated the possibility of controlling the reduction reaction and facilitating the incorporation of other phenomena such as diffusion, etching, and galvanic replacement during nanostructure synthesis. In this study, the reduction potential of straight-chain alcohols has been investigated using molecular orbital calculations and experimentally verified by reducing transition metals. The alcohols with a longer chain exhibited higher reduction potential, and 1-octanol was found to be the strongest among alcohols considered. Furthermore, the experimental evaluation carried out via the synthesis of metallic Cu, Ni, and Co particles was consistent with the theoretical predictions. The reaction mechanism of metallic particle formation was also studied in detail in the Ni-1-octanol system, and the metal ions were confirmed to be reduced via the formation of nickel alkoxide. The results of this investigation were successfully implemented to synthesize Cu-Ni bimetallic nanostructures (core-shell, wire, and tube) via the incorporation of diffusion and etching besides the reduction reaction. These results suggest that the designed synthesis of a wide range of bimetallic nanostructures with more refined control has become possible.
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The acetylcholine receptor-operated K(+) (KACh) channel may be a novel target for atrial-specific antiarrhythmic therapy. Recently it has been demonstrated that tertiapin, a selective blocker of KACh channel, suppressed aconitine-induced atrial fibrillation (AF) in dogs. However, the precise mechanism by which the KACh-channel blocker inhibits the aconitine-induced AF remains unknown. This study was undertaken to determine the role of KACh channel in aconitine-induced AF in guinea pigs. Tertiapin terminated the aconitine-induced AF in anesthetized guinea pigs. The results of an in vitro electrophysiological experiment using atrial cells and atrial preparations suggest that aconitine might activate KACh channels in atrial cells, probably by intracellular Na(+) accumulation, and inhibition of KACh channels by tertiapin might suppress AF by producing conduction block, probably due to further decrease in the resting membrane potential. Since it has been reported that constitutively active KACh channels can be observed in atrial cells of patients with chronic AF, aconitine-induced AF may be used as an experimental model for evaluation of drug effect on chronic AF.
Assuntos
Aconitina/efeitos adversos , Fibrilação Atrial/induzido quimicamente , Fibrilação Atrial/tratamento farmacológico , Venenos de Abelha/farmacologia , Bloqueadores dos Canais de Potássio/farmacologia , Animais , Venenos de Abelha/uso terapêutico , Células Cultivadas , Doença Crônica , Modelos Animais de Doenças , Cães , Eletrocardiografia , Fenômenos Eletrofisiológicos/efeitos dos fármacos , Cobaias , Átrios do Coração/citologia , Átrios do Coração/efeitos dos fármacos , Átrios do Coração/metabolismo , Técnicas In Vitro , Potenciais da Membrana/efeitos dos fármacos , Terapia de Alvo Molecular , Bloqueadores dos Canais de Potássio/uso terapêutico , Canais de Potássio/metabolismo , Canais de Potássio/fisiologia , Sódio/metabolismoRESUMO
Three thienopyrrole-fused thiadiazole (TPT) fluorescent dyes featuring a common amide linker and different alkoxy substituents on peripheral trialkoxybenzene moieties were synthesized, and their self-assembly behavior in solution was investigated. The obtained results revealed a substantial steric effect of the alkoxy substituents on the supramolecular polymerization mechanism, which results from a combination of π-stacking and hydrogen (H)-bonding interactions. Detailed spectroscopic measurements revealed that with increasing steric demand of the substituents, the supramolecular polymerization processes in pure methylcyclohexane (MCH) or a mixture of MCH and toluene become temperature-sensitive and enthalpically favorable, resulting in a change from the isodesmic assembly mechanism to the cooperative mechanism. Theoretical calculations suggested that in TPTs with bulky substituents, steric hindrance causes the H-bonding array of the amide moieties to be aligned along the stacking axis of the π-systems; thus, the H-bonding interactions are strengthened compared to those in TPTs with less bulky substituents, compensating for the weakened π-stacking interactions. A chiral TPT derivative with (S) stereogenic centers was found to form homochiral helical supramolecular assemblies that generate discernible circularly polarized luminescence. Achiral TPTs also generate helical assemblies to which preferential helicity can be imparted through the external chiral bias of the solvents (R)- and (S)-limonene.
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Percutaneous endoscopic gastrostomy (PEG) has been generally used as a long-term enteral nutrition route for patients in whom oral intake is impossible. Percutaneous trans-esophageal gastrotubing (PTEG) is useful for the patients in whom PEG insertion has not been indicated. A gastroenterologist usually performs PTEG in Japan, but in our hospital otolaryngologists have performed this procedure. From 2006 to 2012, we experienced 9 patients who underwent PTEG insertion without a life-threatening adverse event. An otolaryngologist who is accustomed to the cervical procedures can safely perform PTEG insertion.
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Ingestão de Alimentos/fisiologia , Endoscopia do Sistema Digestório , Nutrição Enteral/métodos , Estado Nutricional/fisiologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Endoscopia do Sistema Digestório/instrumentação , Endoscopia do Sistema Digestório/métodos , Nutrição Enteral/instrumentação , Feminino , Humanos , Japão , Masculino , Pessoa de Meia-Idade , Resultado do TratamentoRESUMO
A new diradical based on diindenocarbazole or difluorenopyrrole was synthesized and experimentally characterized by optical, electrochemical, and magnetic techniques, as well as quantum chemical calculations. The isomerism of these structures tunes the diradical character and the associated properties, representing a unique case of such important modulation. A full study of the electronic structure was carried out considering the perturbative interactions between different canonical forms as well as the anti-aromatic character of the molecular cores. Such a study reveals how we can tune diradical character simply by reorganizing the bonding patterns at constant chemical costs (composition).
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Murine IL-17-producing γδT (γδT17) cells are divided into two subsets: natural γδT17 (nγδT17) cells, whose development is restricted to the fetal thymus, and inducible γδT17 cells, which require antigen exposure for their IL-17 production and are presumed to develop from Rorc + Il17a - CCR9 + immature γδT17 cells in the adult thymus and whose T cell receptor (TCR) is biased toward Vγ4. Although IL-23 is known to be involved in developing γδT17 cells, the roles of other cytokines, such as IL-21, which is involved in developing Th17 cells like IL-23, in the development, maintenance, and pathophysiology of γδT17 cells remain unknown. Here, we show that IL-21 is dispensable for the fetal thymic development of nγδT17 cells but is required for the peripheral maintenance of Vγ4+nγδT17 cells. Upon stimulation with γδTCR, IL-1 plus IL-21 induces the proliferation of Vγ4+nγδT17 cells via STAT3 as effectively as IL-1 plus IL-23. Using bone marrow chimeric mice, we demonstrated that immature γδT17 cells are produced de novo in the adult mice from donor adult bone marrow cells and that IL-21 is dispensable for their development. Instead, IL-21 is required to expand newly induced Vγ4+γδT17 cells in the periphery upon immunization. Finally, using adoptive transfer experiments of γδT17 cells, we found that IL-21 receptors on γδT17 cells are involved in maintaining Vγ4+γδT17 cells, subsequent infiltration of Th17 cells into the spinal cord, and exacerbation of experimental autoimmune encephalomyelitis. Collectively, IL-21 plays a vital role in the maintenance and pathogenesis of Vγ4+γδT17 cells.
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Interleucina-17 , Interleucinas , Subpopulações de Linfócitos T , Animais , Camundongos , Interleucina-1 , Interleucina-23 , Subpopulações de Linfócitos T/citologiaAssuntos
Síndrome de Hiperostose Adquirida/diagnóstico , Autoanticorpos/sangue , Interferon gama/imunologia , Infecções por Mycobacterium não Tuberculosas/diagnóstico , Síndrome de Hiperostose Adquirida/imunologia , Antibacterianos/uso terapêutico , Claritromicina/uso terapêutico , Diagnóstico Diferencial , Quimioterapia Combinada , Etambutol/uso terapêutico , Humanos , Masculino , Pessoa de Meia-Idade , Infecções por Mycobacterium não Tuberculosas/tratamento farmacológico , Infecções por Mycobacterium não Tuberculosas/imunologia , Rifampina/uso terapêutico , Resultado do TratamentoRESUMO
During the self-assembly of π-conjugated molecules, linkers and substituents can potentially add supportive noncovalent intermolecular interactions to π-stacking interactions. Here, we report the self-assembly behavior of thienopyrrole-fused thiadiazole (TPT) fluorescent dyes that possess ester or ether linkers and dodecyloxy side chains in solution and the condensed phase. A comparison of the self-association behavior of the ester- and ether-bridged compounds in solution using detailed UV-vis, fluorescence, and NMR spectroscopic studies revealed that the subtle replacement of the ether linkers by ester linkers leads to a distinct increase in the association constant (ca. 3-4 fold) and the enthalpic contribution (ca. 3â kcal mol-1 ). Theoretical calculations suggest that the ester linkers, which are in close proximity to one another due to the π-stacking interactions, induce attractive electrostatic forces and augment self-association. The self-assembly of TPT dyes into well-defined 1D clusters with high aspect ratios was observed, and their morphologies and crystallinity were investigated using SEM and X-ray diffraction analyses. TPTs with ester linkers exhibit a columnar liquid crystalline mesophase in the condensed phase.
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Tiadiazóis , Ésteres , Éter , Éteres , Pirróis , Eletricidade EstáticaRESUMO
Recent studies have identified NF-κB1 as a new disease susceptibility gene for psoriasis. Although accumulating evidence has shown the importance of NF-κB signaling in various cell types in the pathogenesis of psoriasis, it remains unclear how NF-κB1 contributes to the pathogenesis of psoriasis. In this study, we examined psoriasis-like skin diseases induced by topical administration of imiquimod in Nf-κb1âdeficient (Nf-κb1-/-) mice and littermate wild-type (WT) mice. Compared with WT mice, Nf-κb1-/- mice exhibited attenuated skin inflammation. The numbers of Vγ4+Vδ4+γδT17 cells, which cause skin inflammation in this model, were significantly reduced in the skin and draining lymph nodes in imiquimod-treated Nf-κb1-/- mice. Nf-κb1 is preferentially phosphorylated in Vγ4+Vδ4+γδT17 cells in WT mice. In vitro proliferation of Vγ4+Vδ4+γδT17 cells but not conventional CD4+ T cells was significantly impaired in Nf-κb1-/- mice compared with that in WT mice. RNA-sequencing analyses revealed that the expression of E2 factor target genes was decreased in Vγ4+Vδ4+γδT cells by the absence of NF-κB1. Consistently, the cell cycle progression of Vγ4+Vδ4+γδT cells was reduced in Nf-κb1-/- mice compared with that in WT mice. These results suggest that Nf-κb1 plays a crucial role in the pathogenesis of imiquimod-induced psoriasis-like skin inflammation by promoting the proliferation of Vγ4+Vδ4+γδT17 cells.
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Dermatite , Psoríase , Animais , Dermatite/patologia , Modelos Animais de Doenças , Imiquimode , Inflamação/patologia , Interleucina-17/metabolismo , Camundongos , Camundongos Endogâmicos BALB C , Psoríase/induzido quimicamente , Psoríase/genética , Psoríase/metabolismo , Pele/patologiaRESUMO
BACKGROUND: Although bacillus Calmette-Guerin (BCG) is a standard treatment for high-risk non-muscle-invasive bladder cancer (NMIBC), a high rate of adverse events with a variety of grades remains a difficulty. OBJECTIVE: In this randomized, prospective, multicenter study, we examined whether levofloxacin, given after each intravesical instillation of BCG, could improve its tolerance in patients with intermediate- to high-risk urothelial carcinoma of the bladder without compromising its efficacy. DESIGN, SETTING, AND PARTICIPANTS: Overall, 106 Japanese patients (85 men and 21 women; age: median, 69.5 yr) with primary or recurrent NMIBC were randomized after transurethral resection to induce treatment with intravesical BCG plus levofloxacin (group 1) or BCG alone (group 2). INTERVENTION: Patients who underwent intravesical instillation of BCG were randomized with or without levofloxacin administration. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Adverse events were assessed using the National Cancer Institute-Common Toxicity Criteria version 3.0. Cumulative incidence functions and Kaplan-Meier methods were applied to estimate survival outcomes. RESULTS AND LIMITATIONS: There was no significant difference in baseline characteristics between the groups. The completion rate of group 1 (85.5%) was not significantly lower than that of group 2 (76.5%; p = 0.321). There was no significant difference in the completion rate of patients with pollakisuria, painful micturition, gross hematuria, fever elevation, and others between the groups. The incidence of adverse events in patients with high-grade pollakisuria (7.3% vs 25.4%, p = 0.041) and fever (0% vs 9.1%, p = 0.034) was significantly lower in group 1. The 5-yr progression-free and cancer-specific survival rates were significantly better in group 1. CONCLUSIONS: Prophylactic levofloxacin administration may reduce the severity of adverse events and contribute to better outcomes from BCG intravesical therapy in patients with NMIBC. PATIENT SUMMARY: Levofloxacin administration seems to be a safe and effective therapy for non-muscle-invasive bladder cancer patients treated with bacillus Calmette-Guerin intravesical therapy.
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Carcinoma de Células de Transição , Neoplasias da Bexiga Urinária , Humanos , Feminino , Vacina BCG/efeitos adversos , Carcinoma de Células de Transição/tratamento farmacológico , Neoplasias da Bexiga Urinária/tratamento farmacológico , Levofloxacino/uso terapêutico , Estudos ProspectivosAssuntos
Hiperplasia do Linfonodo Gigante/tratamento farmacológico , Ciclofosfamida/administração & dosagem , Adulto , Biópsia , Medula Óssea/patologia , Hiperplasia do Linfonodo Gigante/patologia , Ciclofosfamida/uso terapêutico , Humanos , Infusões Intravenosas , Masculino , Resultado do TratamentoRESUMO
OBJECTIVE: Recently, podocytes have been recognised not only as a physical barrier to prevent urinary protein loss but also as producers of proinflammatory cytokines. However, the roles of podocytes in the pathogenesis of lupus nephritis (LN) remain largely unknown. This study aims to determine the roles of suppressor of cytokine signalling (SOCS) family members expressed in glomeruli in the regulation of LN. METHODS: We investigated the expression of SOCS family members in glomeruli in murine lupus model induced by repeated epicutaneous administration of the TLR7/8 agonist imiquimod. We also investigated the roles of SOCS3 expressed in podocytes in the imiquimod-induced glomerulonephritis and systemic autoimmunity by using podocyte-specific SOCS3-deficient mice (podocin-Cre x SOCS3fl/fl mice (SOCS3-cKO mice)). Finally, we investigated the expression of proinflammatory cytokines and chemokines in SOCS3-deficient podocyte cell lines. RESULTS: qPCR analysis revealed that among SOCS family members, SOCS3 was preferentially induced in glomeruli on epicutaneous administration of imiquimod and that interleukin 6 (IL-6) induced SOCS3 expression in podocyte cell lines. SOCS3-cKO mice exhibited severe glomerulonephritis, high levels of serum creatinine and urine albumin and decreased survival rate compared with control SOCS3-WT mice. Levels of anti-double-strand DNA antibody, SOCS (GC) formation and the numbers of follicular helper T (Tfh) cells and GC B cells in the spleen were higher in SOCS3-cKO mice than those in SOCS3-WT mice. Serum IL-6 levels and expression of IL-6 mRNA in glomeruli were also elevated in SOCS3-cKO mice. IL-6-induced IL-6 expression was enhanced in SOCS3-deficient podocyte cell lines compared with that in SOCS3-sufficient podocyte cell lines. CONCLUSION: SOCS3 expressed in podocytes plays protective roles for the development of glomerulonephritis and inhibits autoantibody production in the imiquimod-induced lupus model presumably by suppressing IL-6 production of podocytes.
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Glomerulonefrite , Podócitos , Proteína 3 Supressora da Sinalização de Citocinas/metabolismo , Animais , Citocinas/metabolismo , Glomerulonefrite/induzido quimicamente , Imiquimode , Camundongos , Camundongos Endogâmicos BALB C , Podócitos/metabolismo , Proteína 3 Supressora da Sinalização de Citocinas/genéticaRESUMO
In guinea-pig cardiomyocytes, a cAMP-dependent Cl(-) current (I(Cl,cAMP)) flows through a cardiac isoform of the cystic fibrosis transmembrane conductance regulator (CFTR), which belongs to a family of the ATP-binding cassette (ABC) proteins. Although several K(+)-channel openers and sulfonylurea ATP-sensitive K(+) (K(ATP))-channel blockers reportedly inhibit I(Cl,cAMP), effects of nicorandil on the Cl(-) current have not been evaluated. This study was conducted to examine the effects of nicorandil on I(Cl,cAMP) in isolated guinea-pig ventricular cells using patch clamp techniques. Nicorandil in concentrations higher than 300 microM enhanced the I(Cl,cAMP) preactivated by 0.1 microM isoproterenol. The isoproterenol-induced I(Cl,cAMP) was inhibited by 100 microM glibenclamide, but not by 100 microM pinacidil. SNAP (S-nitroso-N-acetyl-D,L-penicillamine, 10 microM), a nitric oxide (NO) donor, similarly enhanced the isoproterenol-induced I(Cl,cAMP). However, SG-86, a denitrated metabolite possessing K(+ )channel-opening action, failed to enhance the Cl(-) current. When the I(Cl,cAMP) was activated by 3-isobutyl-1-methylxanthine (IBMX, 30 microM), either nicorandil or SNAP failed to enhance the isoproterenol-induced I(Cl,cAMP). Thus, nicorandil enhances I(Cl,cAMP) in guinea-pig cardiomyocytes through an increase in intracellular cGMP, although direct modulation of I(Cl,cAMP) by NO cannot be completely excluded.
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Anti-Hipertensivos/farmacologia , Canais de Cloreto/efeitos dos fármacos , AMP Cíclico/metabolismo , Ventrículos do Coração/efeitos dos fármacos , Nicorandil/farmacologia , Antagonistas Adrenérgicos beta/farmacologia , Animais , Canais de Cloreto/metabolismo , Glibureto/farmacologia , Cobaias , Ventrículos do Coração/citologia , Hipoglicemiantes/farmacologia , Isoproterenol/farmacologia , Doadores de Óxido Nítrico/farmacologia , Técnicas de Patch-Clamp , Pinacidil/farmacologia , S-Nitroso-N-Acetilpenicilamina/farmacologiaRESUMO
Streptococcus pneumoniae is a common cause of respiratory tract infections (RTIs). The prevalence of Streptococcus pneumoniae strains with reduced susceptibility to antimicrobial agents has dramatically increased worldwide. Susceptibility to nine antimicrobial agents and serotypes were determined among 1,644 Streptococcus pneumoniae strains isolated from patients with RTIs in the Tohoku district of Japan from October to December every year from 1998 to 2007. The prevalence of penicillin G-nonsusceptible Streptococcus pneumoniae (PNSP) strains increased gradually from 48.5% in 1998, reached a statistical peak in 2004 (65.1%) and then decreased to 51.5% in 2007. Streptococcus pneumoniae strains with each serotype 3, 6, 19 and 23 were constantly detected, and the distribution of these serotypes in PNSP strains did not significantly change during the study period. A trend of Streptococcus pneumoniae strains nonsusceptible to other beta-lactams tested was similar to that of PNSP strains, except for cefditoren, to which the resistance rate was < 20% throughout the analysis period. The prevalence of strains nonsusceptible to erythromycin and minocycline were consistently > 60%. Almost all penicillin G-resistant Streptococcus pneumoniae (PRSP) strains were resistant to both erythromycin and minocycline throughout the analysis period. The prevalence of strains resistant to fluoroquinolones tested were < 3% over the study period. Our longitudinal surveillance demonstrated for the first time that decreased prevalence of both beta-lactam- and multidrug-resistant strains has been occurring since 2004 in a region of Japan. Careful monitoring of antimicrobial susceptibility of Streptococcus pneumoniae should be continued.
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Antibacterianos/farmacologia , Streptococcus pneumoniae/efeitos dos fármacos , Adolescente , Adulto , Distribuição por Idade , Idoso , Técnicas de Tipagem Bacteriana , Criança , Pré-Escolar , Demografia , Farmacorresistência Bacteriana/efeitos dos fármacos , Feminino , Humanos , Pacientes Internados , Japão , Estudos Longitudinais , Masculino , Testes de Sensibilidade Microbiana , Pessoa de Meia-Idade , Pacientes Ambulatoriais , Penicilina G/farmacologia , Sistema Respiratório/microbiologia , Caracteres Sexuais , Streptococcus pneumoniae/classificação , Streptococcus pneumoniae/isolamento & purificação , Adulto JovemRESUMO
Ideal interaction-free magnetite nanoparticles were prepared, and their magnetic properties were measured to clarify the true nature of magnetic anisotropy of individual magnetite nanoparticles at the nanoscale and to analyze the shape, surface, and crystalline anisotropy contributions. Spherical (17.7 nm), cubic (10.6 nm), and octahedral-shaped magnetite nanoparticles with average sizes ranging from 7.6 to 23.4 nm were synthesized using solution techniques. Then, these nanoparticles were coated with silica at appropriate shell thicknesses to prepare magnetic interaction-free samples, and their noninteractive nature was confirmed through first-order reversal curve diagrams. For these well-isolated nanoparticles, remanent magnetizations of the hysteresis loops are just equal to a half of the saturation magnetization. This result clearly indicates that uniaxial magnetic anisotropy is predominant in each nanoparticle. In order to clarify the details of the uniaxial magnetic anisotropy, the analysis of blocking temperature-switching field distribution diagrams is constructed based on thermal decay curves of isothermal remanent magnetization at various applied fields. The obtained effective magnetic anisotropy constant Keff is distributed around 10-20 kJ/m3 and has insignificant size dependence. This result seems inconsistent with the inverse proportion relation of Keff with size predicted for surface magnetic anisotropy. The theoretical calculation suggested that the crystalline magnetic anisotropy plays a major role in magnetic properties of the magnetite nanoparticles at lower temperatures. However, it should be noted that Keff seems slightly different for the different shapes. The above study indicates that control size, shape, and interparticle interactions is required to strictly discuss such delicate differences of magnetic anisotropy of individual magnetite nanoparticles for the design of thermal seeds for magnetic hyperthermia.
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OBJECTIVE: Musculoskeletal ultrasound (US) is more sensitive than physical examination in detecting synovitis and helps physicians to understand its pathophysiology. In this study, we aimed to determine if the experience in musculoskeletal US scanning is independently associated with improved physical examination skills to detect synovitis. METHOD: Seventy patients with rheumatoid arthritis and twenty-three physicians were enrolled. Patients were first assessed by multiple physicians with a range of clinical/sonographic experience for the swelling of the wrist, metacarpophalangeal and proximal interphalangeal (PIP) joints and next underwent US assessment performed by another physician experienced in musculoskeletal US. We then calculated the positive/negative predictive values (PPV/NPV) of joint swelling to identify US-detected synovial hypertrophy. Finally, the factors independently associated with the accuracy of clinical assessment were identified by using multivariate analyses. RESULTS: One thousand five hundred forty joints were assessed 6116 times in total for swelling. Overall, PPV and NPV of joint swelling were 51.7% and 88.3%, respectively. Multivariate analyses identified wrist joint, tenderness, male and greater patients' age as the factors significantly associated with higher PPV. In addition, there was a trend that longer experience in rheumatology clinical practice was associated with higher PPV (p = 0.058). On the other hand, longer experience in musculoskeletal US, PIP joint and positive rheumatoid factor were identified as the significant factors for higher NPV, while wrist joint, tenderness, presence of osteophyte and obesity as those for lower NPV. CONCLUSION: Our data suggest that the experience in musculoskeletal US improves physical examination skills particularly to avoid overestimation.Key Points⢠Physicians with longer US experience are less likely to overestimate synovitis by physical examination.⢠Musculoskeletal US is a useful tool for rheumatologists to improve their physical examination skill.⢠Presence of osteophytes, joint tenderness and obesity influence the accuracy of physical examination of joints.