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SignificanceDirect ethanol fuel cells are attracting growing attention as portable power sources due to their advantages such as higher mass-energy density than hydrogen and less toxicity than methanol. However, it is challenging to achieve the complete electrooxidation to generate 12 electrons per ethanol, resulting in a low fuel utilization efficiency. This manuscript reports the complete ethanol electrooxidation by engineering efficient catalysts via single-atom modification. The combined electrochemical measurements, in situ characterization, and density functional theory calculations unravel synergistic effects of single Rh atoms and Pt nanocubes and identify reaction pathways leading to the selective C-C bond cleavage to oxidize ethanol to CO2. This study provides a unique single-atom approach to tune the activity and selectivity toward complicated electrocatalytic reactions.
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In this study, a pretreatment method based on the QuEChERS method has been applied for simultaneously extracting 27 residual pharmaceuticals from wastewater solids. The extracted compounds have been analyzed using online solid-phase extraction (SPE) coupled to liquid chromatography with tandem mass spectrometry (LC-MS/MS). A recovery test was conducted according to the absorbent type, and buffers were added in the sample extraction step. The highest recovery efficiency could be observed when Na2SO4 was used as an absorbent and Na2EDTA was injected during the extraction process; the recovery efficiencies of the proposed method for the target compounds ranged from 61.3 to 137.2%, and the repeatability was 6.8%. These recovery and repeatability data showed that the proposed method could reliably analyze the 27 target residual pharmaceuticals. The concentrations of the target compounds were all below the limits of quantification: 830 ng g-1 for the target compounds in suspended solids, 2353 ng g-1 in activated sludge, and 1929 ng g-1 in waste sludge. The analytical method established in this study can be applied to quantify residual pharmaceuticals in solid samples and to investigate their behaviors in a municipal wastewater treatment plant.
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Preparações Farmacêuticas , Poluentes Químicos da Água , Purificação da Água , Cromatografia Líquida , Monitoramento Ambiental , Extração em Fase Sólida , Espectrometria de Massas em Tandem , Águas Residuárias/análise , Poluentes Químicos da Água/análiseRESUMO
Controlling the morphology and composition of nanocatalysts constructed from metals and conductive polymers has attracted attention owing to their great potential for the development of high-efficiency catalysts for various catalytic applications. Herein, a facile synthetic approach for ultrathin-polyaniline-coated Pt-Ni nanooctahedra (Pt-Ni@PANI hybrids) with controllable PANI shell thicknesses is presented. Pt-Ni nanooctahedra/C catalysts enclosed by PANI shells with thicknesses from 0.6 to 2.4â nm were obtained by fine control over the amount of aniline. The various Pt-Ni@PANI hybrids exhibited electrocatalytic activity toward the methanol oxidation reaction that is highly dependent on the thickness of the PANI shell. Pt-Ni@PANI hybrids with the thinnest PANI shells (0.6â nm) showed markedly improved electrocatalytic performance for the methanol oxidation reaction compared with Pt-Ni@PANI hybrids with thicker PANI shells, Pt-Ni nanooctahedra/C, and commercial Pt/C due to synergistic benefits of ultrathin PANI shells and Pt-Ni alloy.
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Octahedral Pt alloy nanocrystals (NCs) have shown excellent activities as electrocatalysts toward oxygen reduction reaction (ORR). As the activity and stability of NCs are highly dependent on their structure and the elemental distribution, it is of great importance to understand the formation mechanism of octahedral NCs and to rationally synthesize shape-controlled alloy catalysts with optimized ORR activity and stability. However, the factors controlling the structural and compositional evolution during the synthesis have not been well understood yet. Here, we systematically investigated the structure and composition evolution pathways of Pt-Ni octahedra synthesized with the assistance of W(CO)6 and revealed a unique core-shell structure consisting of a Pt core and a Pt-Ni alloy shell. Below 140 °C, sphere-like pure Pt NCs with the diameter of 3-4 nm first nucleated, followed by the isotropic growth of Pt-Ni alloy on the seeds at temperatures between 170 and 230 °C forming Pt@Pt-Ni core-shell octahedra with {111} facets. Owing to its unique structure, the Pt@Pt-Ni octahedra show an unparalleled stability during potential cycling, that is, no activity drop after 10â¯000 cycles between 0.6 and 1.0 V. This work proposes the Pt@Pt-Ni octahedra as a high profile electrocatalyst for ORR and reveals the structural and composition evolution pathways of Pt-based bimetallic NCs.
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Sulfated steroids can act as a latent form of active free steroids, coexisting with them in biological specimens. To evaluate the metabolic significance of free and sulfated steroid species, a simultaneous analysis of eight free steroids [cholesterol, pregnenolone, 17α-hydroxypregnenolone, progesterone, 17α-hydroxyprogesterone, dehydroepiandrosterone (DHEA), testosterone, and 17ß-estradiol] and four biologically relevant sulfated steroids was developed and validated, using selected-ion and multiple-reaction monitoring modes coupled to polarity-switching liquid chromatography/mass spectrometry (LC/MS). All steroids were separated on a reversed-phase phenyl column (50 mm × 2 mm, 3 µm) at a flow rate of 0.5 mL/min. The limits of quantification ranged from 0.1 to 50 ng/mL at extraction recoveries of 94.1-105.5%, while the precision and accuracy were 2.5-9.3% and 92.4-105.9%, respectively. Quantitative results obtained for samples from obese girls showed that the serum levels of DHEA sulfate were significantly increased (P = 0.004), along with the metabolic ratio representing DHEA sulfotransferase (P < 0.02). The developed novel LC/MS method can quantitatively profile both free and sulfated steroids in a single analytical run.
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A fast and sensitive monitoring method for trace pharmaceuticals in the environment is vital because many of these compounds are ubiquitous, persistent, and biologically active with recognized endocrine-disruption and pharmacological functions. A rapid and reliable ultra high-performance liquid chromatography combined with tandem mass spectrometry was developed in the present study to simultaneously identify, confirm, and quantify 60 target pharmaceuticals in wastewater samples. The method uses a sub-2 µm particle column for separating target compounds, which were subsequently quantified with the mass spectrometer. Using this high-throughput analysis method, a single injection could provide results within 5 min for the pharmaceuticals. All of the target compounds were analyzed by the multiple-reaction monitoring with 15-ms fast polarity switching. Both intraday and interday precision analyses indicate excellent coefficient of variability. To evaluate the performance of the method, a standard solution (100 and 1000 ng L(-1)) was spiked into complex wastewater samples. The tailing factor and peak width were also monitored and adjusted for optimizing peaks from the ultra high-performance liquid chromatograph. Of the target pharmaceuticals in wastewater of a sewage-treatment plant analyzed on an hourly basis, only 17 compounds were detected, and others were lower than the method detection limits. Acetaminophen, cimetidine, and iopromide were all detected at >1 µg L(-1), and their concentration profiles were similar to that of a nonsteroidal anti-inflammatory drug detected in wastewater. Other noticeable pharmaceuticals were sulfamethoxazole and trimethoprim. Sources of pharmaceuticals in wastewater are briefly discussed.
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Monitoramento Ambiental/métodos , Preparações Farmacêuticas/análise , Águas Residuárias/química , Poluentes Químicos da Água/análise , Cromatografia Líquida de Alta Pressão , Disruptores Endócrinos/análise , Extração em Fase Sólida , Espectrometria de Massas em TandemRESUMO
Heavy metals and organic dyes are the major source of water pollution. Herein, a trifunctional ß-cyclodextrin-ethylenediaminetetraacetic acid-chitosan (ß-CD-EDTA-CS) polymer was synthesized using an easy and simple chemical route by the reaction of activated ß-CD with CS through EDTA as a cross-linker (amidation reaction) for the removal of inorganic and organic pollutants from aqueous solution under different parameters such as pH, time effect, initial concentration, reusability, etc. The synthesized adsorbent was characterized using powder X-ray diffraction, Fourier transform infrared spectroscopy, field scanning electron microscopy, energy dispersive spectroscopy, Brunauer-Emmett-Teller (BET), thermogravimetric analyzer techniques to investigate their structural, functional, morphological, elemental compositions, surface area and thermal properties, respectively. Two types of heavy metals, i.e., mercury (Hg2+) and cadmium (Cd2+), and three organic dyes, i.e., methylene blue (MB), crystal violet (CV) and safranin O (SO) were chosen as inorganic and organic pollutants, respectively, to study the adsorption capacity of ß-CD-EDTA-CS in aqueous solution. The ß-CD-EDTA-CS shows monolayer adsorption capacity 346.30 ± 14.0 and 202.90 ± 13.90 mg g-1 for Hg2+ and Cd2+, respectively, and a heterogeneous adsorption capacity 107.20 ± 5.70, 77.40 ± 5.30 and 55.30 ± 3.60 mg g-1 for MB, CV and SO, respectively. Kinetics results followed pseudo-second order (PSO) kinetics behavior for both metal ions and dyes, and higher rate constants values (0.00161-0.00368 g mg-1 min-1) for dyes confirmed the cavitation of organic dyes (physisorption). In addition, we have also demonstrated the performance of ß-CD-EDTA-CS for the of four heavy metals Hg2+, Cd2+, Ni2+, and Cu2+ and three dyes MB, CV, and SO in secondary treated wastewater. Findings of this study indicate that ß-CD-EDTA-CS simple and essay to synthesize and can be use in wastewater treatment.
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Quitosana , Metais Pesados , Poluentes Químicos da Água , beta-Ciclodextrinas , Adsorção , Corantes , Ácido Edético , Concentração de Íons de Hidrogênio , Cinética , Polímeros , Águas ResiduáriasRESUMO
This study aimed to assess the association between urinary concentrations of chlorophenols and childhood central obesity. The study subjects were 165 girls (91 with central obesity and 74 with non-central obesity) aged 7-8 years who visited a hospital for regular health check-ups. The urinary concentrations of chlorophenols including 2,4-dichlorophenol (2,4-DCP), 2,5-dichlorophenol (2,5-DCP), 2,4,5-trichlorophenol (2,4,5-TCP), and 2,4,6-trichlorophenol (2,4,6-TCP) were analyzed using liquid chromatography-tandem mass spectrometry. The central obesity group showed significantly higher urinary concentrations of 2,5-DCP (0.56 vs. 0.28 ng/mL) and 2,4,5-TCP (0.06 vs. 0.03 ng/mL) than the non-central obesity group. The sum of molar concentrations of urinary chlorophenols was also significantly higher in the central obesity group than in the non-central obesity group (9.83 vs. 5.26 nmol/L). Girls in the highest quartile of the molar sum of chlorophenols showed significantly higher body mass index (BMI), waist circumference (WC), and waist-to-height ratio (WHtR) compared with the lowest quartile after adjusting for covariates. WC and WHtR, but not BMI, were significantly associated with higher quartiles of the molar sum of chlorophenols (P-for-trend = 0.025 and 0.028, respectively). We found a positive association between chlorophenol exposure and central obesity in Korean girls. Large-scale prospective studies are needed to confirm our findings.
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Clorofenóis , Obesidade Abdominal , Índice de Massa Corporal , Criança , Estudos Transversais , Feminino , Humanos , Obesidade Abdominal/epidemiologia , Estudos Prospectivos , República da Coreia , Circunferência da CinturaRESUMO
Phosphodiesterase-5 inhibitors (PDE-5i, such as Sildenafil, Tadalafil and Vardenafil, mainly prescribed to treat erectile dysfunction) and their generic drug equivalents have been widely marketed and consumed in Korea. From the concentrations detected in wastewater, we could deduce that relatively large amounts of PDE-5i were consumed without a legal prescription. Thus, PDE-5i's presence in the environment via sewage is unavoidable, and their environmental fate within a sewage treatment plant (STP) should be evaluated. In this study, we investigated the occurrence of three PDE-5i analogs in the influent and effluent of two STPs and the receiving water bodies. The PDE-5i concentration in total reached 62 ± 12 (STP#1) and 88 ± 37 ng L-1 (STP#2) in the sewage influent; about 70% of it was Sildenafil in both STPs. However, they were hardly removed by the STPs as the removal efficiency of the STPs was less than 10% ± 5%. Therefore, the pharmaceuticals were detected in the receiving water (lower than 7 ng L-1as a total amount) and the concentration slightly increased downstream of the STPs. A simple mass balance model applied for the compounds in the STP effluent and receiving water bodies also confirmed that the discharged PDE-5i were quite persistent. Lastly, we identified temporal and regional patterns in the consumption of the drugs from daily variations of PDE-5i in the influent to these two STPs. For instance, the levels of PDE-5i in the sewage significantly increased on weekends (from Friday to Saturday), and especially in the area where adult-entertainment businesses are common. We estimated that the amount of PDE-5i consumption in this area was 31% higher than that in the area with fewer nightlife spots. Considering that they are pharmaceutically active and resistant to treatment processes within an STP, it is advised that a regular monitoring and management program for PDE-5i should be developed to prevent the discharge of the pharmaceuticals into the water environment.
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In this study, we analyzed 27 pharmaceuticals in liquid and solid phase samples collected from the unit processes of four different sewage treatment plants (STPs) to evaluate their distribution and behavior of the pharmaceuticals. The examination of the relative distributions of various categories of pharmaceuticals in the influent showed that non-steroidal anti-inflammatory drugs (NSAIDs) were the most dominant. While the relative distribution of antibiotics in the influent was not high (i.e., 3%-5%), it increased to 14%-30% in the effluent. In the four STPs, the mass load of the target pharmaceuticals was reduced by 88%-95% mainly in the biological treatment process, whereas the ratio of pharmaceuticals in waste sludge to those in the influent (w/w) was only 2%. In all the STPs, the removal efficiencies for the stimulant caffeine, NSAIDs (acetaminophen, naproxen, and acetylsalicylic acid), and the antibiotic cefradine were high; they were removed mainly by biological processes. Certain compounds, such as the NSAID ketoprofen, contrast agent iopromide, lipid regulator gemfibrozil, and antibiotic sulfamethoxazole, showed varying removal efficiencies depending on the contribution of biodegradation and sludge sorption. In addition, a quantitative meta-analysis was performed to compare the pharmaceutical removal efficiencies of the biological treatment processes in the four STPs, which were a membrane bioreactor (MBR) process, sequencing batch reactor (SBR) process, anaerobic-anoxic-oxic (A2O) process, and moving-bed biofilm reactor (MBBR) process. Among the biological processes, the removal efficiency was in the order of MBR > SBR > A2O > MBBR. Among the tertiary treatment processes investigated, powdered activated carbon showed the highest removal efficiency of 18%-63% for gemfibrozil, ibuprofen, ketoprofen, atenolol, cimetidine, and trimethoprim.
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Preparações Farmacêuticas/isolamento & purificação , Esgotos , Eliminação de Resíduos Líquidos , Poluentes Químicos da Água/isolamento & purificação , Anti-Inflamatórios não Esteroides/isolamento & purificação , Biodegradação Ambiental , Biofilmes , Reatores BiológicosRESUMO
In this study, a total of 52 pharmaceuticals in the influent and effluent of two sewage treatment plants (STPs) and in the receiving waters were quantified with an analytical method using on-line solid phase extraction coupled to liquid chromatograph-tandem mass spectrometry. 36 out of the 52 pharmaceuticals were detected in the influent and effluent of the STPs at quantifiable levels; influent and effluent concentrations ranged 1â¯ngâ¯L-1 to 30⯵gâ¯L-1 and 3â¯ngâ¯L-1 to 3⯵gâ¯L-1, respectively. They were also detected from the receiving waters (both tributaries and main river); their concentrations ranged from 1 to 310â¯ngâ¯L-1. A simple mass balance model was applied for the pharmaceutical data measured for the STPs, tributaries, and the main river to demonstrate the contribution of the STPs to the pollution of the streams and the main river. The average ratio of the model estimations and the measured concentrations was calculated 97% for the downstream of the STPs, while that for the main river was 89%. This modeling result clearly demonstrates that many pharmaceuticals flowing into an STP are not degraded and discharged to a nearby river, affecting the whole water body, and that the STP is the only source of the pollutants. While their discharge into STPs should be avoided. In addition, development of new technologies capable of completely degrading them is desirable.
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Monitoramento Ambiental/métodos , Preparações Farmacêuticas/análise , Rios/química , Esgotos/química , Poluentes Químicos da Água/análise , Cromatografia Líquida/métodos , Extração em Fase Sólida/métodos , Espectrometria de Massas em Tandem/métodosRESUMO
Because the hydrogen evolution reaction (HER) in alkaline electrolyzers is initiated by water dissociation, the hydrogen evolution kinetics are sluggish even on highly active Pt catalysts. Here, we have synthesized Ni(OH)2 -decorated Pt nanocubes as a bifunctional catalyst to enhance the HER kinetics in an alkaline medium. Electrochemical cyclic voltammetry and CO-stripping measurements confirmed the selective deposition of Ni(OH)2 on the Pt(1 0 0) facets of nanocubes. Electrocatalytic HER activity of the Ni(OH)2 -decorated Pt nanocubes demonstrated that the bifunctional catalytic surface promotes the Volmer step kinetics and thus the Volmer/Tafel coupling dominant. As the result, catalytic surface specificity of Ni(OH)2 -decorated Pt nanocubes enhanced water dissociation, reduced contamination of OHad on Pt surface, and maintained long-term HER performance in alkaline electrolytes.
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Here we report the synthesis of 9 nm Ni(OH)2 decorated Pt-Cu octahedra (Ni(OH)2-PtCu) in one-pot synthesis for ethanol oxidation reaction (EOR) electrocatalysis in acidic electrolyte. To prepare Ni(OH)2-PtCu octahedra, CO gas was directly introduced in a reaction process as selective capping agents on the PtCu(111) facet. Ni(OH)2 was naturally deposited on the Pt-Cu octahedra during the synthesis. Carbon supported Ni(OH)2-PtCu (Ni(OH)2-PtCu/C) as an EOR catalyst showed enhanced CO tolerance due to the existence of oxophilic Ni(OH)2 on the surface of Pt-Cu, facilitating water dissolution to produce OH adsorption and to promote complete CO oxidation to CO2. In addition, Pt-Cu alloy composition also showed improvement of CO tolerance because of modified d-band structure of the Pt atoms, thereby weakening the binding strength of CO on the catalysts. Therefore, the Ni(OH)2-PtCu/C showed enhanced EOR activity and durability compared to the Pt-Cu octahedra and commercial Pt/C counterparts.
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A layered ß-NiOOH crystal with undercoordinated facets is an active and economically viable nonnoble catalyst for the oxygen evolution reaction (OER) in alkaline electrolytes. However, it is extremely difficult to enclose the ß-NiOOH crystal with undercoordinated facets because of its inevitable crystal transformation to γ-NiOOH, resulting in the exfoliation of the catalytic surfaces. Herein, we demonstrate {111}-faceted Ni octahedra as the parent substrates whose surfaces are easily transformed to catalytically active ß-NiOOH during the alkaline OER. Electron microscopic measurements demonstrate that the horizontally stacked ß-NiOOH on the surfaces of Ni octahedra has resistance to further oxidation to γ-NiOOH. By contrast, significant crystal transformation and thus the exfoliation of the γ-NiOOH sheets can be observed on the surfaces of Ni cubes and rhombic dodecahedra (RDs). Electrocatalytic measurements show that the ß-NiOOH formed on Ni octahedra exhibits highly enhanced OER durability compared to the Ni cubes, Ni RDs, and the state-of-the-art Ir/C catalysts.
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Nine N-nitrosamines (i.e., N-nitrosomethylamine, N-nitrosodiethylamine (NDEA), N-nitrosodimethylamine (NDMA), N-nitrosodi-n-propylamine (NDPA), N-nitrosomorpholine (NMor), N-nitrosopyrrolidine (NPyr), N-nitrosopiperidine (NPip), N-nitorosodi-n-butylamine (NDBA), and N-nitrosodiphenylamine (NDPhA) in atmospheric PM2.5 collected in the fall season from an roadside site and a residential in Seoul, Korea have been analyzed using a newly developed method consisting of simple direct liquid extraction assisted by ultrasonication and subsequent quantification using a gas chromatography-triple quadrupole mass spectrometry (GC-TQMS). Excellent recovery values (92-100%) and method detection limits for the target compounds atmospheric PM samples could be achieved even without an evaporation step for sample concentration. The concentration of total N-nitrosamines in PM2.5 was ranged from 0.3 to 9.4 ng m-3 in this study; NDMA, NDEA, NDBA, NPyr, and NMor in PM2.5 were found to be the most frequently encountered compounds at the sampling sites. Since no industrial plant is located in Seoul, vehicle exhausts were considered major cause of the formation of nitrosamines in this study. The mechanisms how these compounds are formed and detected in the atmosphere are explained from the viewpoint of secondary organic aerosol. Considering the concentrations of N-nitrosamines and their associated potential health risks, a systematic monitoring of nitrosamines present in both ambient air and PM2.5 including seasonal and diurnal variations of selected sites (including potential precursor sources) should be carried out in the future. The proposed sample pretreatment method along with the analytical method will definitely help us perform the monitoring study.
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Atmosfera/química , Monitoramento Ambiental/métodos , Nitrosaminas/análise , Material Particulado/análise , Butilaminas/análise , Cromatografia Gasosa-Espectrometria de Massas , República da Coreia , Espectrometria de Massas em TandemRESUMO
Helicobacter pylori is associated with hypergastrinemia, which has been linked to the development of gastric diseases. Although the molecular mechanism is not fully understood, H. pylori is known to modulate the Erk pathway for induction of gastrin expression. Herein we found that an epidermal growth factor (EGF) receptor kinase inhibitor significantly blocked H. pylori-induced gastrin promoter activity, suggesting involvement of EGF receptor ligands. Indeed, H. pylori induced mRNA expression of EGF family members such as amphiregulin, EGF, heparin-binding EGF-like growth factor (HB-EGF), and transforming growth factor-α. Of these, specific siRNA targeting of HB-EGF significantly blocked H. pylori-induced gastrin expression. Moreover, H. pylori induced HB-EGF ectodomain shedding, which we found to be a critical process for H. pylori-induced gastrin expression. Thus, we demonstrate a novel role for human mature HB-EGF in stimulating gastrin promoter activity during H. pylori infection. Further investigation using specific siRNAs targeting each isoform of Raf, Mek, and Erk elucidated that the mechanism underlying H. pylori-induced gastrin expression can be delineated as the sequential activation of HB-EGF, the EGF receptor, C-Raf, Mek1, and the Erk2 molecules in the MAPK pathway. Surprisingly, whereas Erk2 acts as a potent activator of gastrin expression, siRNA knockdown of Erk1 induced gastrin promoter activity, suggesting that Erk1 typically acts as a repressor of gastrin expression. Elucidation of the mechanism of gastrin modulation by HB-EGF-mediated EGF receptor transactivation should facilitate the development of therapeutic strategies against H. pylori-related hypergastrinemia and consequently gastric disease development, including gastric cancers.
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Gastrinas/genética , Regulação da Expressão Gênica , Infecções por Helicobacter/genética , Infecções por Helicobacter/microbiologia , Helicobacter pylori/fisiologia , Fator de Crescimento Semelhante a EGF de Ligação à Heparina/genética , Transdução de Sinais , Proteínas de Ligação a DNA/metabolismo , Receptores ErbB/metabolismo , Gastrinas/metabolismo , Genes Reporter , Infecções por Helicobacter/metabolismo , Fator de Crescimento Semelhante a EGF de Ligação à Heparina/metabolismo , Humanos , Proteína Quinase 1 Ativada por Mitógeno/metabolismo , Mutação , Regiões Promotoras Genéticas , Proteínas Proto-Oncogênicas c-raf/metabolismo , RNA Mensageiro/genética , Fatores de Transcrição/metabolismoRESUMO
Infection with Helicobacter pylori is a major risk factor for development of gastric disease, including gastric cancer. Patients infected with H. pylori strains that express CagA are at even greater risk of gastric carcinoma. Given the importance of CagA, this report describes a new molecular mechanism by which the cagA copy number dynamically expands and contracts in H. pylori Analysis of strain PMSS1 revealed a heterogeneous population in terms of numbers of cagA copies; strains carried from zero to four copies of cagA that were arranged as direct repeats within the chromosome. Each of the multiple copies of cagA was expressed and encoded functional CagA; strains with more cagA repeats exhibited higher levels of CagA expression and increased levels of delivery and phosphorylation of CagA within host cells. This concomitantly resulted in more virulent phenotypes as measured by cell elongation and interleukin-8 (IL-8) induction. Sequence analysis of the repeat region revealed three cagA homologous areas (CHAs) within the cagA repeats. Of these, CHA-ud flanked each of the cagA copies and is likely important for the dynamic variation of cagA copy numbers. Analysis of a large panel of clinical isolates showed that 7.5% of H. pylori strains isolated in the United States harbored multiple cagA repeats, while none of the tested Korean isolates carried more than one copy of cagA Finally, H. pylori strains carrying multiple cagA copies were differentially associated with gastric disease. Thus, the dynamic expansion and contraction of cagA copy numbers may serve as a novel mechanism by which H. pylori modulates gastric disease development.IMPORTANCE Severity of H. pylori-associated disease is directly associated with carriage of the CagA toxin. Though the sequences of the CagA protein can differ across strains, previous analyses showed that virtually all H. pylori strains carry one or no copies of cagA This study showed that H. pylori can carry multiple tandem copies of cagA that can change dynamically. Isolates harboring more cagA copies produced more CagA, thus enhancing toxicity to host cells. Analysis of 314 H. pylori clinical strains isolated from patients in South Korea and the United States showed that 7.5% of clinical strains in the United States carried multiple cagA copies whereas none of the South Korean strains did. This study demonstrated a novel molecular mechanism by which H. pylori dynamically modulates cagA copy number, which affects CagA expression and activity and may impact downstream development of gastric disease.
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Antígenos de Bactérias/genética , Proteínas de Bactérias/genética , Dosagem de Genes , Infecções por Helicobacter/microbiologia , Infecções por Helicobacter/patologia , Helicobacter pylori/genética , Gastropatias/microbiologia , Gastropatias/patologia , Perfilação da Expressão Gênica , Helicobacter pylori/patogenicidade , Humanos , Coreia (Geográfico) , Sequências Repetitivas de Ácido Nucleico , Análise de Sequência de DNA , Homologia de Sequência , Estados UnidosRESUMO
The array of outer membrane proteins (OMPs) found in Helicobacter pylori provides a crucial component for persistent colonization within the gastric niche. Not only does H. pylori harbor a wide number of OMPs, but these OMPs often vary across strains; this likely contributes to immune evasion, adaptation during long term colonization, and potentially differential disease progression. Previous work from our group described OMP differences among the Bab family (babA, babB, and babC) and Hom family (homA and homB) from 80 American H. pylori clinical isolates (AH) and 80 South Korean H. pylori clinical isolates (KH). In the current study, we expanded our investigation to include the less well characterized Hom family member, HomC.Overall, we identified and genotyped three homC variants: homC S , homC L , and homC M , in both populations. Similar to other polymorphic genes, the KH group showed less overall diversity, with 97.5% of strains harboring homC L . In contrast, a more heterogeneous profile was observed in strains derived from an American population; we found nearly equal distribution of homC S and homC L . Further analysis of the AH group identified associations between homC polymorphism and bab genotype; in AH strains, there was a significant association between homC L and carriage of babA at locus A. Since babA is an important virulence factor for the development of severe gastric disease, these data may suggest that homC polymorphism plays a role in H. pylori pathogenesis.
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Proteínas da Membrana Bacteriana Externa/genética , Helicobacter pylori/genética , Polimorfismo Genético , Adesinas Bacterianas , Sequência de Aminoácidos , Proteínas da Membrana Bacteriana Externa/química , Variação Genética , Genótipo , Infecções por Helicobacter/microbiologia , Helicobacter pylori/classificação , Helicobacter pylori/patogenicidade , Humanos , Fatores de VirulênciaRESUMO
Influenza is a serious public health concern worldwide, as it causes significant morbidity and mortality. The emergence of drug-resistant viral strains requires new approaches for the treatment of influenza. In this study, Rubus coreanus seed (RCS) that is left over from the production of wine or juice was found to show antiviral activities against influenza type A and B viruses. Using the time-of-addition plaque assay, viral replication was almost completely abolished by simultaneous treatment with the RCS fraction of less than a 1-kDa molecular weight (RCSF1). One of the polyphenols derived from RCSF1, gallic acid (GA), identified by liquid chromatography-tandem mass spectrometry, showed inhibitory effects against both influenza type A and B viruses, albeit at relatively high concentrations. RCSF1 was bound to hemagglutinin protein, inhibited hemagglutination significantly and disrupted viral particles, whereas GA was found to only disrupt the viral particles by using transmission electron microscopy. In BALB/c mice infected with influenza virus, oral administration of RCSF1 significantly improved the survival rate and reduced the viral titers in the lungs. Our results demonstrate that RCSF1 and GA show potent and broad antiviral activity against influenza A and B type viruses and are promising sources of agents that target virus particles.
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Antivirais/farmacologia , Ácido Gálico/farmacologia , Vírus da Influenza A/efeitos dos fármacos , Vírus da Influenza B/efeitos dos fármacos , Rubus/química , Sementes/química , Replicação Viral/efeitos dos fármacos , Animais , Antivirais/administração & dosagem , Antivirais/isolamento & purificação , Cromatografia Líquida , Modelos Animais de Doenças , Ácido Gálico/administração & dosagem , Ácido Gálico/isolamento & purificação , Vírus da Influenza A/fisiologia , Vírus da Influenza B/fisiologia , Camundongos Endogâmicos BALB C , Infecções por Orthomyxoviridae/tratamento farmacológico , Análise de Sobrevida , Espectrometria de Massas em Tandem , Ensaio de Placa ViralRESUMO
Areca nut (AN) chewing is a habit in many countries in Central, Southern, and Southeast Asia. It is strongly associated with the occurrence of oral, pharyngeal, and esophageal cancer as well as systemic inflammation. However, the association between AN intake and the development of gastric lesions has not yet been identified. The aim of this study was to investigate the effect of AN on gastric diseases using a mouse model for Helicobacter pylori infection. We studied four groups of mice: those fed a normal diet (ND), those fed a diet containing 2.5% AN (AD), those fed ND and infected with H. pylori PMSS1 strain (ND/HP), and those fed AD and infected with H. pylori PMSS1 strain (AD/HP). Food intake and body weight were monitored weekly during the experiments. At 10 weeks, the mice were sacrificed, and the stomach weight, H. pylori colonization, and gastric inflammation were evaluated. The stomach weight had increased significantly in the ND/HP and AD/HP groups along with increases in H. pylori colonization; however, there was no significant difference between these two groups with respect to stomach weight and colonization. On histological grading, mononuclear cell infiltration was severer in the AD/HP group than in the ND/HP group. These data suggest that chronic gastric inflammation was aggravated by AN treatment in the mice with H. pylori-induced gastric lesions. Furthermore, as previously suggested, this animal model is useful to determine the effect of potential carcinogens on gastric lesions induced by H. pylori infection.