Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 26
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Soft Matter ; 15(41): 8197-8200, 2019 Oct 23.
Artigo em Inglês | MEDLINE | ID: mdl-31613305

RESUMO

A series of supramolecular assemblies based on multi-charged calixarene (SC4A), bis(p-calixarene) (BSC4A) and pillararene (CP5A) modified gold nanoparticles (AuNP) was constructed to realize colorimetric sensing of both succinylcholine (SuCh) and butyrylcholinesterase (BChE). With the high binding affinity of BSC4A and CP5A towards SuCh, BSC4A-AuNPs and CP5A-AuNPs could assemble with micromolar level SuCh as SuCh-BSC4A/CP5A-AuNPs. More interestingly, the enzymatic hydrolysis of SuCh by BChE could lead to the disassembly of SuCh-BSC4A/CP5A-AuNPs and provide a sensitive time-dependent color change from blue to red which could be observed by the naked eye and used to monitor BChE activity. As BChE activity is an important biomarker for diseases and poor health conditions, this novel supramolecular tandem colorimetric sensing strategy may have potential use for early diagnosis of diseases.


Assuntos
Butirilcolinesterase/análise , Calixarenos/química , Corantes/química , Ouro/química , Nanopartículas Metálicas/química , Técnicas Biossensoriais/métodos , Colorimetria , Concentração de Íons de Hidrogênio , Cinética , Succinilcolina/análise , Propriedades de Superfície
2.
World J Pediatr ; 2019 Oct 16.
Artigo em Inglês | MEDLINE | ID: mdl-31620982

RESUMO

BACKGROUND: The molecular characteristics and antimicrobial susceptibility of Staphylococcus aureus (S. aureus) in general pediatric wards and county-level hospitals were rarely reported in China. METHODS: Staphylococcus aureus was isolated from children hospitalized with respiratory tract infection (RTI) in Zhongjiang and Youyang counties in 2015. All isolates were typed by multilocus sequence, staphylococcal protein A, accessory gene regulator (agr), and staphylococcal cassette chromosome mec [SCCmec, for methicillin-resistant S. aureus (MRSA) only]. Polymerase chain reaction was used to screen 21 super-antigen (SAg) genes and panton-valentine leukocidin (pvl). Antimicrobial susceptibility testing was performed by E test. RESULTS: A total of 2136 children were enrolled. Overall, 125 (5.9%) children carried S. aureus, among which MRSA accounted for 42.4%. ST59-SCCmec type IV-t437-agr group I (58.5%) was the most prevalent genotype in MRSA, and ST188-t189-agr group I (22.2%) was the top genotype in methicillin-sensitive S. aureus (MSSA). The pvl carriage rate in MRSA and MSSA was 15.1% and 9.7%, respectively (P = 0.4112). About 96.8% of S. aureus isolates were positive for at least one SAg gene. The most common SAg gene profile in the dominant ST59 clone was seb-sek-seq (42.8%). All S. aureus isolates were resistant to penicillin and erythromycin (minimum inhibitory concentration 90 was > 32 and 256 mg/L to penicillin and erythromycin, respectively), but usually susceptible to other tested non-ß-lactam antimicrobials. CONCLUSIONS: Staphylococcus aureus and MRSA were detected with a high frequency in children with RTI in county-level hospitals of China. ST59-SCCmec type IV-t437-agr group I was the dominant MRSA clone. The S. aureus isolates exhibited high resistance to penicillin and erythromycin.

3.
Chem Commun (Camb) ; 55(78): 11790-11793, 2019 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-31524903

RESUMO

Balancing and neutralizing heparin dosing after surgeries and hemodialysis treatment is of great importance in medical and clinical fields. In this study, a series of new amphiphilic multi-charged cyclodextrins (AMCD)s as anti-heparin coagulants were designed and synthesized. The AMCD assembly was capable of selective heparin binding through multivalent bonding and showed a better neutralizing effect towards both unfractionated heparin and low molecular weight heparin than protamine in plasma. Meanwhile, an AMCD and vitamin K (VK) co-assembly was prepared to realize heparin-responsive VK release and provide a novel VK deficiency treatment for hemodialysis patients. This AMCD-VK co-assembly for heparin neutralization & vitamin K supplementation synergistic coagulation represents a promising candidate as a clinical anti-heparin coagulant.


Assuntos
Coagulantes/química , Ciclodextrinas/química , Vitamina K/química , Coagulantes/metabolismo , Ciclodextrinas/metabolismo , Heparina/química , Heparina/metabolismo , Tempo de Tromboplastina Parcial , Protaminas/química , Protaminas/metabolismo , Espectrofotometria , Vitamina K/metabolismo
4.
Zhongguo Dang Dai Er Ke Za Zhi ; 18(11): 1059-1064, 2016 Nov.
Artigo em Chinês | MEDLINE | ID: mdl-27817765

RESUMO

Nomenclature and classification of diseases are not only related to clinical diagnosis and treatment, but also involved in the fields such as management and exchange of medical information, medical expense payments, and medical insurance payment. In order to standardize clinical physicians' diagnostic and treatment activities, medical records, and the first page of medical records, this article elaborates on the basic principles and methods for nomenclature and classification of diseases with reference to international nomenclature of diseases and international classification of diseases. Meanwhile, in view of the problems in clinical practice, this article proposes the classification of neonatal diseases, the basic procedure and writing rules in the diagnosis of neonatal diseases, and death diagnosis principles.


Assuntos
Doenças do Recém-Nascido/classificação , Classificação Internacional de Doenças , Humanos , Recém-Nascido , Doenças do Recém-Nascido/diagnóstico , Terminologia como Assunto
5.
Yi Chuan ; 38(10): 940-947, 2016 10 20.
Artigo em Inglês | MEDLINE | ID: mdl-27806935

RESUMO

There were some limitation in the current interpretation about the penicillin resistance mechanism of clinical Streptococcus pneumoniae isolates at the strain level. To explore the possibilities of studying the mechanism based on the sequence types (ST) of this bacteria, 488 isolates collected in Beijing from 1997-2014 and 88 isolates collected in Youyang County, Chongqing and Zhongjiang County, Sichuan in 2015 were analyzed by penicillin minimum inhibitory concentration (MIC) distribution and annual distribution. The results showed that the penicillin MICs of the all isolates covering by the given ST in Beijing have a defined range, either <0.25 mg/L or≥0.25 mg/L, except for the ST342. The isolates with penicillin MIC <0.25 mg/L were mainly collected before 2001, after which the isolates with MIC≥0.25 mg/L occurred and became the major population gradually. This law of year distribution, however, was not obvious for any specific ST. The isolates covering by any given ST could be determined with different penicillin MICs in the first few years after it was identified. The penicillin MIC of isolates identified as common STs and collected in Youyang County, Chongqing and Sichuan Zhongjiang County, including the ST271, ST320 and ST81, was around 0.25~2 mg/L (≥0.25 mg/L). Our study revealed the epidemiological distribution of penicillin MICs of the given STs determined in clinical S. pneumoniae isolates, suggesting that it is reasonable to research the penicillin resistance mechanism based on the STs of this bacteria.


Assuntos
Antibacterianos/farmacologia , Resistência às Penicilinas , Penicilinas/farmacologia , Infecções Pneumocócicas/microbiologia , Streptococcus pneumoniae/efeitos dos fármacos , Streptococcus pneumoniae/isolamento & purificação , China/epidemiologia , Estudos Epidemiológicos , Humanos , Testes de Sensibilidade Microbiana , Infecções Pneumocócicas/epidemiologia , Streptococcus pneumoniae/classificação , Streptococcus pneumoniae/genética
6.
Zhongguo Dang Dai Er Ke Za Zhi ; 18(10): 960-964, 2016 Oct.
Artigo em Chinês | MEDLINE | ID: mdl-27751211

RESUMO

OBJECTIVE: To study clinical features of respiratory distress syndrome (RDS) in neonates of different gestational ages (GA). METHODS: According to GA, 133 neonates with RDS were classified into GA <34 weeks group (n=66), GA 34-36 weeks group (late preterm neonates; n=31), and GA ≥37 weeks group (full-term neonates; n=36). The mothers' medical history during pregnancy and the condition of the neonates at birth were retrospectively analyzed, and the clinical data were compared between groups. RESULTS: Prenatal corticosteroids supplementation in the GA <34 weeks group was more common than that in the GA 34-36 weeks group (P<0.05). Compared with the GA ≥37 weeks group and the GA 34-36 weeks group, the GA <34 weeks group showed a significantly lower rate of primary diseases, a significantly later time of the development of dyspnea (P<0.05), and a higher rate of intraventricular hemorrhage (P<0.05). Serum albumin levels in the GA <34 weeks group were significantly lower than in the GA ≥37 weeks group (P<0.05). The GA ≥37 weeks group and the GA 34-36 weeks group showed a significantly higher reuse rate of pulmonary surfactant (P<0.05). Use of high-frequency oscillatory ventilation was more common in the GA ≥37 weeks group compared with the GA <34 weeks group (P<0.05). CONCLUSIONS: The clinical features of RDS are different across neonates of different GA, suggesting that the pathogenesis of RDS may be different in neonates of different GA.


Assuntos
Idade Gestacional , Síndrome do Desconforto Respiratório do Recém-Nascido/etiologia , Feminino , Humanos , Recém-Nascido , Masculino , Síndrome do Desconforto Respiratório do Recém-Nascido/sangue , Estudos Retrospectivos , Fatores de Risco , Albumina Sérica/análise
7.
Zhongguo Dang Dai Er Ke Za Zhi ; 18(9): 817-820, 2016 Sep.
Artigo em Chinês | MEDLINE | ID: mdl-27655536

RESUMO

OBJECTIVE: To study the clinical application of ultrasonic cardiac output monitor (USCOM) in evaluation of cardiac function in children with severe pneumonia. METHODS: Twenty-nine children with severe pneumonia were enrolled in the observation group and forty-three children with common pneumonia were enrolled in the control group. The USCOM was used to measure the cardiac function indices in the two groups. The results were compared between the two groups. The changes in cardiac function indices after treatment were evaluated in the observation group. ESULTS: The observation group had a significantly higher heart rate and significantly lower cardiac output, systolic volume, and aortic peak velocity than the control group (P<0.05). There were no significant differences in cardiac index or systemic vascular resistance between the two groups (P>0.05). In the observation group, the heart rate, cardiac output, systolic volume, aortic peak velocity, cardiac index, and systemic vascular resistance were significantly improved after treatment (P<0.05). CONCLUSIONS: The USCOM is a fast, convenient, and accurate approach for dynamic measurement of cardiac function and overall circulation state in children with severe pneumonia. The USCOM can provide a basis for diagnosis, treatment, and evaluation of the disease, which is quite useful in clinical practice.


Assuntos
Débito Cardíaco/fisiologia , Monitorização Fisiológica/instrumentação , Pneumonia/fisiopatologia , Ultrassom , Criança , Feminino , Humanos , Lactente , Masculino
8.
Langmuir ; 31(43): 11932-42, 2015 Nov 03.
Artigo em Inglês | MEDLINE | ID: mdl-26448140

RESUMO

The electrochemical detection of a single nanoparticle (NP) at a support electrode can provide key information on surface chemistry and fundamental electron transfer (ET) properties at the nanoscale. This study employs scanning electrochemical cell microscopy (SECCM) as a fluidic device to both deliver individual citrate-capped gold nanoparticles (AuNPs) and study the interactions between them and a range of alkanethiol-modified Au electrodes with different terminal groups, namely, -COOH, -OH, and -CH3. Single NP collisions were detected through the AuNP-mediated ET reaction of Fe(CN)6(4-/3-) in aqueous solution. The collision frequency, residence time, and current-time characteristics of AuNPs are greatly affected by the terminal groups of the alkanethiol. Methods to determine these parameters, including the effect of the instrument response function, and derive ET kinetics are outlined. To further understand the interactions of AuNPs with these surfaces, atomic force microscopy (AFM) force measurements were performed using citrate-modified Au-coated AFM tips and the same alkanethiol-modified Au substrates in aqueous solution at the same potential bias as for the AuNP collision experiments. Force curves on OH-terminated surfaces showed no repulsion and negligible adhesion force. In contrast, a clear repulsion (on approach) was seen for COOH-terminated surface and adhesion forces (on retract) were observed for both COOH- and CH3-terminated surfaces. These interactions help to explain the residence times and collision frequencies in AuNP collisions. More generally, as the interfacial properties probed by AFM appear to be amplified in NP collision experiments, and new features also become evident, it is suggested that such experiments provide a new means of probing surface chemistry at the nanoscale.

9.
Anal Chem ; 87(11): 5782-9, 2015 Jun 02.
Artigo em Inglês | MEDLINE | ID: mdl-25942527

RESUMO

Voltammetric scanning electrochemical cell microscopy (SECCM) incorporates cyclic voltammetry measurements in the SECCM imaging protocol, by recording electrochemical currents in a wide potential window at each pixel in a map. This provides much more information compared to traditional fixed potential imaging. Data can be represented as movies (hundreds of frames) of current (over a surface region) at a series of potentials and are highly revealing of subtle variations in electrode activity. Furthermore, by combining SECCM data with other forms of microscopy, e.g. scanning electron microscopy and electron backscatter diffraction data, it is possible to directly relate the current-voltage characteristics to spatial position and surface structure. In this work we use a "hopping mode", where the SECCM pipet probe is translated toward the surface at a series of positions until meniscus contact. Small amounts of residue left on the surface, upon probe retraction, demark the precise area of each measurement. We use these techniques to study hydrazine oxidation on a polycrystalline platinum substrate both in air and in a deaerated environment. In both cases, the detected faradaic current shows a structural dependence on the surface crystallographic orientation. Significantly, in the presence of oxygen (aerated solution) the electrochemical current decreases strongly for almost all grains (crystallographic orientations). The results highlight the flexibility of voltammetric SECCM for electrochemical imaging and present important implications for hydrazine electroanalysis.

10.
Int J Clin Exp Med ; 8(11): 20309-15, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26884945

RESUMO

To investigate the feasibility and changes of biological characteristics before and after synovial mesenchymal stem cells (SMSCs) labelled by super paramagnetic iron oxide (SPIO). The rabbit SMSCs were isolated, cultured, purified and identified in vitro. After adding the different concentrations of SPIO-labelled liquid, the cells were incubated 24 h in 37°C carbon dioxide incubator. The labeled-cell samples were observed by Prussian blue staining, transmission electron microscope (TEM) and the cell biology before and after the labeling was compared. The blue stained particles could be seen in the cytoplasm; the SPIO label was positive in 95% SMSC cells. With the concentration of the label liquid increasing, the blue-stained cytoplasm became darker. A large number of high electron density particles could be seen in the cytoplasm and in the pinocytosis vesicles by TEM, which suggested SPIO label positive. When the SPIO concentration was (12.5~50) µg/mL, the differences in cell proliferation and cell viability between the SMSCs after labelling and the SMSCs before labelling were not significant; when the concentration was over 100 µg/mL, the cell proliferation and cell viability were inhibited. A certain concentration range of SPIO can safely label the rabbit SMSC according to this study, which is important for solving the problem of tracing SMSCs in the joints.

11.
Phys Chem Chem Phys ; 16(34): 18545-52, 2014 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-25072300

RESUMO

The scanning droplet-based technique, scanning electrochemical cell microscopy (SECCM), combined with electron backscatter diffraction (EBSD), is demonstrated as a powerful approach for visualizing surface structure effects on the rate of the oxygen reduction reaction (ORR) at polycrystalline platinum electrodes. Elucidating the effect of electrode structure on the ORR is of major interest in connection to electrocatalysis for energy-related applications. The attributes of the approach herein stem from: (i) the ease with which the polycrystalline substrate electrode can be prepared; (ii) the wide range of surface character open to study; (iii) the possibility of mapping reactivity within a particular facet (or grain), in a pseudo-single-crystal approach, and acquiring a high volume of data as a consequence; (iv) the ready ability to measure the activity at grain boundaries; and (v) an experimental arrangement (SECCM) that mimics the three-phase boundary in low temperature fuel cells. The kinetics of the ORR was analyzed and a finite element method model was developed to explore the effect of the three-phase boundary, in particular to examine pH variations in the droplet and the differential transport rates of the reactants and products. We have found a significant variation of activity across the platinum substrate, inherently linked to the crystallographic orientation, but do not detect any enhanced activity at grain boundaries. Grains with (111) and (100) contributions exhibit considerably higher activity than those with (110) and (100) contributions. These results, which can be explained by reference to previous single-crystal measurements, enhance our understanding of ORR structure-activity relationships on complex high-index platinum surfaces, and further demonstrate the power of high resolution flux imaging techniques to visualize and understand complex electrocatalyst materials.

12.
Zhonghua Er Ke Za Zhi ; 51(8): 571-7, 2013 Aug.
Artigo em Chinês | MEDLINE | ID: mdl-24225286

RESUMO

OBJECTIVE: Kawasaki disease (KD) is a common autoimmune vasculitis. It has been regarded as the leading cause of acquired heart disease in children. This study aimed to assess the relationship between genome-wide association study (GWAS)-linked gene loci and KD. METHOD: By March of 2013, the published GWAS literatures of KD were retrieved from the databases including PubMed, MEDLINE, Web of Science, Cochrane Library, CNKI, VIP and Wanfang, and the gene loci associated with KD at genome-wide significance of P < 5.0×10(-8) were determined. For each of the gene loci, one single-nucleotide polymorphism (SNP) with strong association with KD was chosen for meta-analysis. Then the published case-control studies reporting the associations of the SNPs with KD were collected from English and Chinese databases with the same criteria. The Meta-analyses were conducted with RevMan 5.1 software after screening and evaluation. RESULT: A total of 4 gene loci including FCGR2A, BLK, CD40 and HLA were observed having association with KD at genome-wide significance of P < 5.0×10(-8) in at least one GWAS. The risk alleles of the SNPs in the gene loci were all more common in patients with KD relative to controls in the systematic reviews with 8, 4, 6 and 4 extracted case-control studies, respectively[ FCGR2A rs1801274: P < 0.001, OR = 1.40, 95% CI (1.30, 1.51); BLK rs2254546: P < 0.001, OR = 1.69, 95% CI (1.52, 1.88); CD40 rs4813003: P < 0.001, OR = 1.31, 95% CI (1.22, 1.41); HLA rs2857151: P < 0.001, OR = 1.41, 95% CI (1.27, 1.57)]. The significant publication bias was not observed in the meta-analyses. CONCLUSION: Our results confirmed the overall association of the 4 gene loci with KD in observed populations, together with the consistent presence of the relationship between BLK or HLA and KD in the populations, suggesting that it is hopeful to find the genetic marker combination predicting the risk of KD, the formation of secondary coronary artery lesions and the resistance of intravenous immunoglobulin, by further seeking the function SNPs of the gene loci and investigating the effect on the important clinical phenotypes of KD.


Assuntos
Grupo com Ancestrais do Continente Asiático/genética , Loci Gênicos , Síndrome de Linfonodos Mucocutâneos/genética , Polimorfismo de Nucleotídeo Único , Receptores de IgG/genética , Criança , Pré-Escolar , Frequência do Gene , Ligação Genética , Marcadores Genéticos , Predisposição Genética para Doença , Estudo de Associação Genômica Ampla , Humanos
13.
Zhongguo Dang Dai Er Ke Za Zhi ; 15(6): 477-83, 2013 Jun.
Artigo em Chinês | MEDLINE | ID: mdl-23791066

RESUMO

OBJECTIVE: To investigate the association of rs72689236, a new functional single nucleotide polymorphism (SNP) of the gene encoding caspase-3 (CASP3), with the occurrence and development of Kawasaki disease by a meta analysis. METHODS: A literature search was performed using databases at home and abroad according to inclusion and exclusion criteria, to acquire studies on the relationship between rs72689236 and Kawasaki disease published up to November 2012, including case-control studies and transmission disequilibrium tests. An integrated meta analysis was performed using RevMan 5.1 software after the studies were screened and evaluated. RESULTS: Six studies were extracted for systematic review of the association between rs72689236 and Kawasaki disease. The frequency of allele A of the SNP was significantly higher in patients with Kawasaki disease than in the controls (OR=1.34, 95%CI=1.24-1.46, P<0.001); the risk for Kawasaki disease in children with allele A (AA+AG) increased by approximately 44% compared with children with GG (OR=1.44, 95%CI=1.27-1.65, P<0.001). The frequency of allele A of the SNP was significantly higher in Kawasaki disease patients with coronary artery lesions than in those without coronary artery lesions (OR=1.51, 95%CI=1.10-2.07, P= 0.01); the risk for coronary artery lesions in Kawasaki disease patients with allele A (AA+AG) increased by approximately 59% compared with Kawasaki disease patients with GG (OR=1.59, 95%CI= 1.00-2.53, P=0.05]. No association between this SNP and the therapeutic effect of intravenous immunoglobulin (IVIG) was found in patients with Kawasaki disease. CONCLUSIONS: The allele A of functional SNP rs72689236 of CASP3 increases the risk for Kawasaki disease, and it may be used as the genetic marker for susceptibility to coronary artery lesions as a complication of Kawasaki disease. Currently, there is still no sufficient evidence that this SNP has an impact on the therapeutic effect of IVIG in patients with Kawasaki disease, and more studies are needed to investigate the feasibility of its application in individualized treatment.


Assuntos
Caspase 3/genética , Síndrome de Linfonodos Mucocutâneos/genética , Polimorfismo de Nucleotídeo Único , Doença da Artéria Coronariana/etiologia , Genótipo , Humanos , Imunoglobulinas Intravenosas/uso terapêutico , Síndrome de Linfonodos Mucocutâneos/tratamento farmacológico , Síndrome de Linfonodos Mucocutâneos/etiologia
14.
Zhonghua Yi Xue Yi Chuan Xue Za Zhi ; 30(2): 180-4, 2013 Apr.
Artigo em Chinês | MEDLINE | ID: mdl-23568731

RESUMO

OBJECTIVE: The minor allele T of rs113420705 (C/T) in caspase-3 gene (CASP3) has been found to significantly increase the risk of Kawasaki disease (KD) and complicate coronary artery lesions (CALs) in Japanese children. In this study, we have explored association of single nucleotide polymorphisms (SNPs) of CASP3 gene and clinic phenotypes of KD. METHODS: A total of 238 unrelated KD patients and 364 healthy controls with matched age, gender and ethnic origins were recruited. Genotypes of the 3 SNPs were determined with PCR-restriction fragment length polymorphism (PCR-RFLP) and DNA sequencing. Allelic, genotypic and haplotypic frequencies were compared between patients and controls, patients with and without CALs, and patients resistant to and responsive to intravenous immunoglobulin (IVIG) treatment. RESULTS: The T allele and T carriers of rs113420705 were significantly more common in KD patients than controls. A significant difference was also detected in haplotype distribution between patients and controls, where two haplotypes involving the T allele of rs113420705 showed higher frequencies in the patient group. Allelic and genotypic frequencies of the 3 SNPs were similar between patients with and without CALs and those resistant to and responsive to IVIG treatment. CONCLUSION: Our results suggested that CASP3 probably plays an important role in KD. The T allele of rs113420705 may provide a useful marker for KD susceptibility, although no association between this SNP and clinical prognosis and treatment effect of KD has been found among the selected Chinese children patients.


Assuntos
Caspase 3/genética , Síndrome de Linfonodos Mucocutâneos/genética , Polimorfismo de Nucleotídeo Único , Criança , Pré-Escolar , Feminino , Predisposição Genética para Doença , Humanos , Lactente , Masculino , Fosfotransferases (Aceptor do Grupo Álcool)/genética
15.
J Am Chem Soc ; 135(10): 3873-80, 2013 Mar 13.
Artigo em Inglês | MEDLINE | ID: mdl-23405963

RESUMO

The influence of electrode surface structure on electrochemical reaction rates and mechanisms is a major theme in electrochemical research, especially as electrodes with inherent structural heterogeneities are used ubiquitously. Yet, probing local electrochemistry and surface structure at complex surfaces is challenging. In this paper, high spatial resolution scanning electrochemical cell microscopy (SECCM) complemented with electron backscatter diffraction (EBSD) is demonstrated as a means of performing 'pseudo-single-crystal' electrochemical measurements at individual grains of a polycrystalline platinum electrode, while also allowing grain boundaries to be probed. Using the Fe(2+/3+) couple as an illustrative case, a strong correlation is found between local surface structure and electrochemical activity. Variations in electrochemical activity for individual high index grains, visualized in a weakly adsorbing perchlorate medium, show that there is higher activity on grains with a significant (101) orientation contribution, compared to those with (001) and (111) contribution, consistent with findings on single-crystal electrodes. Interestingly, for Fe(2+) oxidation in a sulfate medium a different pattern of activity emerges. Here, SECCM reveals only minor variations in activity between individual grains, again consistent with single-crystal studies, with a greatly enhanced activity at grain boundaries. This suggests that these sites may contribute significantly to the overall electrochemical behavior measured on the macroscale.


Assuntos
Técnicas Eletroquímicas , Compostos Férricos/química , Compostos Ferrosos/química , Platina/química , Polímeros/química , Cristalização , Eletrodos , Oxirredução
16.
J Phys Chem B ; 116(24): 7154-61, 2012 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-22650146

RESUMO

In the reaction between trans-resveratrol (resveratrol) and the hydroxyl radical, kinetic product control leads to a short-lived hydroxyl radical adduct with an absorption maximum at 420 nm and a lifetime of 0.21 ± 0.01 µs (anaerobic acetonitrile at 25 °C) as shown by laser flash photolysis using N-hydroxypyridine-2(1H)-thione (N-HPT) as a "photo-Fenton" reagent. The transient spectra of the radical adduct are in agreement with density functional theory (DFT) calculations showing an absorption maximum at 442 or 422 nm for C2 and C6 hydroxyl adducts, respectively, and showing the lowest energy for the transition state leading to the C2 adduct compared to other radical products. From this initial product, the relative long-lived 4'-phenoxyl radical of resveratrol (τ = 9.9 ± 0.9 µs) with an absorption maximum at 390 nm is formed in a process with a time constant (τ = 0.21 ± 0.01 µs) similar to the decay constant for the C2 hydroxyl adduct (or a C2/C6 hydroxyl adduct mixture) and in agreement with thermodynamics identifying this product as the most stable resveratrol radical. The hydroxyl radical adduct to phenoxyl radical conversion with concomitant water dissociation has a rate constant of 5 × 10(6) s(-1) and may occur by intramolecular hydrogen atom transfer or by stepwise proton-assisted electron transfer. Photolysis of N-HPT also leads to a thiyl radical which adds to resveratrol in a parallel reaction forming a sulfur radical adduct with a lifetime of 0.28 ± 0.04 µs and an absorption maximum at 483 nm.


Assuntos
Carbono/química , Radical Hidroxila/química , Fenóis/química , Estilbenos/química , Transporte de Elétrons , Isomerismo , Modelos Moleculares , Fotólise , Prótons , Teoria Quântica , Resveratrol , Espectrofotometria
17.
Zhonghua Yi Xue Yi Chuan Xue Za Zhi ; 28(6): 644-8, 2011 Dec.
Artigo em Chinês | MEDLINE | ID: mdl-22161096

RESUMO

OBJECTIVE: Kawasaki disease (KD) is a form of acute multi-systemic vasculitis with unknown etiology. It is the leading cause of acquired heart disease in children due to the frequent occurrence of coronary artery lesions (CALs). Recently, a C allele of rs28493229 (G/C) in inositol 1,4,5-trisphosphate 3-kinase C (ITPKC) gene was found to significantly increase the risk for KD/CALs in Japanese population. It is important to confirm such finding in Chinese population to enable prognosis and personalized therapy for KD. METHODS: A case-control study was performed. The patient group has included 206 unrelated patients with KD, and the control group included 285 age, gender and ethnically matched children who never had KD. Genotyping of rs28493229 was performed using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and DNA sequencing. The allele, genotype and C allele carrier frequencies were compared between the two groups, patients with or without CALs, and patients who were resistant or responsive to (intravenous immunoglobulin, IVIG) treatment. RESULTS: Frequency of the C allele of rs28493229 was significantly lower in both groups than that in the Japanese population (P< 0.01). No significant difference was detected between the two groups in terms of allele, genotype and C carrier of rs28493229 frequencies. Such frequencies were also similar between patients with or without CALs, resistant or responsive to IVIG treatment. CONCLUSION: Our study has failed to prove any association between rs28493229 and KD/CALs in Chinese patients, which indicated that the C allele of rs28493229 may not be used as a molecular marker for determining KD susceptibility, prognosis and effect of treatment. The much lower frequency of C allele does not support its significance in the occurrence of KD/CALs in Chinese population. It is still necessary to find functional SNPs in ITPKC gene which is associated with KD/CALs in Chinese population.


Assuntos
Predisposição Genética para Doença , Síndrome de Linfonodos Mucocutâneos/genética , Fosfotransferases (Aceptor do Grupo Álcool)/genética , Polimorfismo de Nucleotídeo Único , Grupo com Ancestrais do Continente Asiático/genética , Sequência de Bases , Estudos de Casos e Controles , Criança , Pré-Escolar , China , Feminino , Frequência do Gene , Genótipo , Humanos , Imunoglobulinas Intravenosas/uso terapêutico , Lactente , Recém-Nascido , Masculino , Síndrome de Linfonodos Mucocutâneos/terapia , Resultado do Tratamento
18.
J Agric Food Chem ; 59(18): 10367-72, 2011 Sep 28.
Artigo em Inglês | MEDLINE | ID: mdl-21863887

RESUMO

Regeneration of ß-carotene from the ß-carotene radical cation by the 4'-propylpuerarin anion (second-order rate constant=1.5×10(9) L mol(-1) s(-1) in methanol/chloroform=1:9 (v/v) solution at 25 °C as determined by laser flash photolysis) was found to be marginally slower than regeneration by the 7-propylpuerarin anion (2.3×10(9) L mol(-1) s(-1)), in agreement with the 7-propylpuerarin anion being more reducing (E'=0.56 V vs NHE) than the 4'-propylpuerarin anion (E'=1.01 V vs NHE). The potentials were calculated from E°=1.12 and 1.44 V (vs NHE) as determined by cyclic voltametry in aqueous solution and pKa=9.51 and 7.23 obtained previously for 7-propylpuerarin and 4'-propylpuerarin, respectively. The less reducing but more acidic 4'-propylpuerarin showed less antioxidant activity in liposome of pH 7.4, but more significant antioxidant synergism with ß-carotene than the more reducing but less acidic 7-propylpuerarin for oxidation initiated in the liposome lipid phase. Electrostatic effects are concluded to be important in the regeneration of ß-carotene from the radical cation in the water/lipid interface because approximately 50% of 4'-propylpuerarin is present as the anion, whereas only 0.5% of 7-propylpuerarin is present as the anion. In contrast, penetration of the undissociated phenolic group into the lipid phase, more significant for 7-propylpuerarin than for 4'-propylpuerarin according to the calculated water/lipid partition coefficients, becomes important for the chain-breaking action in lipid oxidation of the puerarin derivatives as models for (iso)flavonoids and their glycosides.


Assuntos
Antioxidantes/farmacologia , Flavonoides/farmacologia , Fenóis/química , beta Caroteno/farmacologia , Sinergismo Farmacológico , Flavonoides/química , Concentração de Íons de Hidrogênio , Isoflavonas/química , Isoflavonas/farmacologia , Oxirredução , beta Caroteno/química
19.
Zhongguo Dang Dai Er Ke Za Zhi ; 13(2): 153-6, 2011 Feb.
Artigo em Chinês | MEDLINE | ID: mdl-21342629

RESUMO

OBJECTIVE: To study the effect of different concentrations of bilirubin on expression of toll-like receptor 4 (TLR4) in cord blood monocytes (CBMC). METHODS: Under the sterile condition, umbilical vein blood samples were obtained from normal full-term newborns, and the monocytes were in vitro separated by the method of gelatin/plasma coated flasks. The monocytes were preincubated with various concentrations (0-307.8 µmol/L) of bilirubin dissolved in bovine albumin solution for 1 hr. Bilirubin-treated CBMC were further cultured with LPS (1 µg/mL) to induce cellular activation for 24 hrs, and then the CBMC were collected. The expression of TLR4 in monocytes was measured by indirect immunofluorescence method. RESULTS: Bilirubin at the concentrations of 102.6, 153.9, 220.6 and 307.8 µmol/L inhibited the expression of TLR4 of CBMC. The inhibition effect increased with the increasing concentration of bilirubin. CONCLUSIONS: Bilirubin can inhibit the TLR4 expression of CBNC in a dose-dependent manner.


Assuntos
Bilirrubina/farmacologia , Sangue Fetal/química , Monócitos/química , Receptor 4 Toll-Like/sangue , Relação Dose-Resposta a Droga , Sangue Fetal/efeitos dos fármacos , Humanos , Recém-Nascido , Monócitos/efeitos dos fármacos
20.
J Phys Chem B ; 115(9): 2082-9, 2011 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-21323327

RESUMO

Hydroxyl radical reacts readily with ß-carotene following submicrosecond laser photolysis of N-hydroxypyridine-2(1H)-thione (N-HPT) as a "photo-Fenton" reagent generating hydroxyl and thiyl radicals in acetonitrile:tetrahydrofuran (4:1, v/v) solution. On the basis of spectral evidence, and supported by kinetic considerations and thermodynamic calculations, a short-lived transient species, detected by time-resolved absorption spectroscopy with an absorption maximum at ∼750 nm and a lifetime of ∼150 ns at 25 °C under anaerobic conditions, is suggested to be the long-sought neutral ß-carotene radical formed by hydrogen-atom abstraction. The transient spectrum is different from the spectra of the ß-carotene radical cation (∼1000 nm absorption maximum with a millisecond lifetime), the ß-carotene radical adducts (∼520 nm, several microsecond lifetime), the ß-carotene radical cation ion pair (∼750 nm, several hundred microsecond lifetime), and the ß-carotene radical anion (∼880 nm, a few tens of microsecond lifetime). In parallel, ß-carotene reacts with the thiyl radical to yield a sulfur radical adduct with absorption maximum at ∼520 nm with a lifetime of 3.0 µs. For astaxanthin and canthaxanthin, the reaction with the thiyl radical dominates and the neutral radical is hardly formed in agreement with the less reducing properties of these 4,4'-diketo carotenoids without the reactive 4,4'-hydrogens.


Assuntos
Radical Hidroxila/química , beta Caroteno/química , Absorção , Cantaxantina/química , Lasers , Fotólise , Piridinas/química , Análise Espectral , Tionas/química , Xantofilas/química
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA