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1.
Dig Dis Sci ; 67(8): 4086-4091, 2022 08.
Artigo em Inglês | MEDLINE | ID: mdl-34486085

RESUMO

BACKGROUND: Early onset colorectal cancer (CRC) incidence is rising under age 50, with a birth cohort effect for increasing incidence among individuals born 1950 and later. It is unclear whether increasing incidence trends will confer increased risk beyond age 50, the previously most commonly recommended age to initiate screening, when screening availability might modify incidence trends. AIM: Evaluate US trends in colorectal cancer (CRC) for ages 40-59 years. METHODS: We analyzed counts and incidence rates for CRC, including by anatomic subsite, using the US Cancer Statistics dataset covering 100% of the population 2003-2017. Joinpoint regression was used to quantify Average Annual Percent Change (AAPC) in cancer incidence by age subgroup. RESULTS: 470,458 CRC cases were observed age 40-59, with absolute numbers of rectal (n = 4173) and distal cases (n = 3327) per year for age 50-54 approaching age 55-59 cases for rectal (n = 4566) and distal (n = 3682) cancer by 2017. Increasing early onset rectal cancer incidence per 100,000 occuring under age 50 was observed to extend to age 50-54, from 4.9 to 6.3 for age 40-44 (AAPC 2.1; 95% CI 1.5-2.7), 9.3 to 12.0 for age 45-49 (AAPC 1.5; 95% CI 1.1-1.4), and from 16.7 to 19.5 for age 50-54 (AAPC 1.0; 95% CI 0.7-1.3). CONCLUSIONS: CRC trends suggest observed increased risks under age 50 are also present after age 50, despite prior availability of screening for this group. Recent CRC trends support initiation of screening earlier than age 50, and promotion of "on-time" screening initiation.


Assuntos
Neoplasias Colorretais , Neoplasias Retais , Adulto , Neoplasias Colorretais/diagnóstico , Neoplasias Colorretais/epidemiologia , Detecção Precoce de Câncer , Humanos , Incidência , Pessoa de Meia-Idade , Pesquisa
2.
Clin Gastroenterol Hepatol ; 19(4): 680-689.e12, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-32428708

RESUMO

BACKGROUND & AIMS: The incidence and mortality of early-onset colorectal cancer (CRC) are increasing. Adenoma detection, removal, and subsequent endoscopic surveillance might modify risk of CRC diagnosed before age 50 years (early-onset CRC). We conducted a systematic review of young-onset adenoma (YOA) prevalence, associated risk factors, and rate of metachronous advanced neoplasia after YOA diagnosis. METHODS: We performed a systematic search of multiple electronic databases through February 12, 2019 and identified studies of individuals 18 to 49 years old that reported prevalence of adenoma, risk factors for adenoma, and/or risk for metachronous advanced neoplasia. Summary estimates were derived using random effects meta-analysis, when feasible. RESULTS: The pooled overall prevalence of YOA was 9.0% (95% CI, 7.1%-11.4%), based on 24 studies comprising 23,142 individuals. On subgroup analysis, the pooled prevalence of YOA from autopsy studies was 3.9% (95% CI, 1.9%-7.6%), whereas the prevalence from colonoscopy studies was 10.7% (95% CI, 8.5%-13.5). Only advancing age was identified as a consistent risk factor for YOA, based on 4 studies comprising 78,880 individuals. Pooled rate of metachronous advanced neoplasia after baseline YOA diagnosis was 6.0% (95% CI, 4.1%-8.6%), based on 3 studies comprising 1493 individuals undergoing follow-up colonoscopy, with only 1 CRC case reported. Overall, few studies reported metachronous advanced neoplasia and no studies evaluated whether routine surveillance colonoscopy decreases risk of CRC. CONCLUSIONS: In a systematic review, we estimated the prevalence of YOA to be 9% and to increase with age. Risk for metachronous advanced neoplasia after YOA diagnosis is estimated to be 6%. More research is needed to understand the prevalence, risk factors, and risk of CRC associated with YOA.


Assuntos
Adenoma , Pólipos do Colo , Neoplasias Colorretais , Adenoma/epidemiologia , Adolescente , Adulto , Colonoscopia , Neoplasias Colorretais/diagnóstico , Neoplasias Colorretais/epidemiologia , Humanos , Pessoa de Meia-Idade , Prevalência , Fatores de Risco , Adulto Jovem
3.
Bioprocess Biosyst Eng ; 43(8): 1339-1357, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32193755

RESUMO

The development of nanoparticle-based drugs has provided many opportunities to diagnose, treat and cure challenging diseases. Through the manipulation of size, morphology, surface modification, surface characteristics, and materials used, a variety of nanostructures can be developed into smart systems, encasing therapeutic and imaging agents with stealth properties. These nanostructures can deliver drugs to specific tissues or sites and provide controlled release therapy. This targeted and sustained drug delivery decreases the drug-related toxicity and increases the patient's compliance with less frequent dosing. Nanotechnology employing nanostructures as a tool has provided advances in the diagnostic testing of diseases and cure. This technology has proven beneficial in the treatment of cancer, AIDS, and many other diseases. This review article highlights the recent advances in nanostructures and nanotechnology for drug delivery, nanomedicine and cures.


Assuntos
Síndrome da Imunodeficiência Adquirida , Portadores de Fármacos/uso terapêutico , Nanomedicina , Nanoestruturas/uso terapêutico , Neoplasias , Síndrome da Imunodeficiência Adquirida/diagnóstico , Síndrome da Imunodeficiência Adquirida/diagnóstico por imagem , Síndrome da Imunodeficiência Adquirida/tratamento farmacológico , Preparações de Ação Retardada/uso terapêutico , Humanos , Neoplasias/diagnóstico , Neoplasias/diagnóstico por imagem , Neoplasias/tratamento farmacológico
4.
Crit Rev Food Sci Nutr ; 59(4): 611-625, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-28956626

RESUMO

Citrus EOs is an economic, eco-friendly and natural alternatives to chemical preservatives and other synthetic antioxidants, such as sodium nitrites, nitrates or benzoates, commonly utilized in food preservation. Citrus based EOs is obtained mainly from the peels of citrus fruits which are largely discarded as wastes and cause environmental problems. The extraction of citrus oils from the waste peels not only saves environment but can be used in various applications including food preservation. The present article presents elaborated viewpoints on the nature and chemical composition of different EOs present in main citrus varieties widely grown across the globe; extraction, characterization and authentication techniques/methods of the citrus EOs; and reviews the recent advances in the application of citrus EOs for the preservation of fruits, vegetables, meat, fish and processed food stuffs. The probable reaction mechanism of the EOs based thin films formation with biodegradable polymers is presented. Other formulation, viz., EOs microencapsulation incorporating biodegradable polymers, nanoemulsion coatings, spray applications and antibacterial action mechanism of the active compounds present in the EOs have been elaborated. Extensive research is required on overcoming the challenges regarding allergies and obtaining safer dosage limits. Shift towards greener technologies indicate optimistic future towards safer utilization of citrus based EOs in food preservation.


Assuntos
Citrus/química , Conservação de Alimentos/métodos , Frutas/química , Óleos Voláteis/isolamento & purificação , Antioxidantes/análise , Quitosana/química , Indústria Farmacêutica/métodos , Emulsões/química , Indústria Alimentícia/métodos , Embalagem de Alimentos/instrumentação , Conservantes de Alimentos , Gelatina/química , Limoneno/análise , Nanotecnologia , Óleos Voláteis/química , Polímeros/química , Terpenos/análise
5.
Bioprocess Biosyst Eng ; 42(1): 1-15, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30238362

RESUMO

The hazardous effects of current nanoparticle synthesis methods have steered researchers to focus on the development of newer environmentally friendly and green methods for synthesizing nanoparticles using nontoxic chemicals. The development of environmentally friendly methods of nanoparticle synthesis with different sizes and shapes is one of the pressing challenges for the current nanotechnology. Several novel green approaches for the synthesis of AuNPs have been explored using different natural sources, such as plants, algae, bacteria, and fungi. Among organisms, algae and blue-green algae are of particular interest for nanoparticle synthesis. Gold nanoparticles (AuNPs) have a range of applications in medicine, diagnostics, catalysis, and sensors because of their significant key roles in important fields. AuNPs have attracted a significant interest for use in a variety of applications. The widespread use of AuNPs can be accredited to a combination of optical, physical, and chemical properties as well as the miscellany of size, shape, and surface composition that has been adopted through green synthesis methods.


Assuntos
Cianobactérias/fisiologia , Ouro/química , Nanopartículas Metálicas/química , Nanotecnologia/métodos , Antioxidantes/química , Infecções Bacterianas/tratamento farmacológico , Catálise , Linhagem Celular Tumoral , Fungos , Química Verde , Humanos , Nanotecnologia/tendências , Neoplasias/tratamento farmacológico , Plantas , Polímeros/química , Alga Marinha , Sefarose/análogos & derivados , Sefarose/química , Propriedades de Superfície
6.
Bioprocess Biosyst Eng ; 41(1): 1-20, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-28965140

RESUMO

Nanotechnology is a rapidly developing field because of its wide range of applications in science, nanoscience and biotechnology. Nanobiotechnology deals with nanomaterials synthesised or modified using biotechnology. Fungi are used to synthesise metal nanoparticles and they have vast applications in wound healing, pathogen detection and control, food preservation, textiles, fabrics, etc. The present review describes the different types of fungi used for the biosyntheses of silver nanoparticles (AgNPs), along with their characterisation and possible biological applications. AgNPs synthesised by other physical and chemical methods are expensive and have toxic substances adsorbed onto them. Therefore, green, simple and effective approaches have been chosen for the biosynthesis of AgNPs, which are very important because of their lower toxicity and environmentally friendly behaviour. AgNPs synthesised using fungi have high monodispersity, specific composition and a narrow size range. In this regard, among the different biological methods used for metal nanoparticle synthesis, fungi are considered to be a superior biogenic method owing to their diversity and better size control. To further understand the biosynthesis of AgNPs using various fungi and evaluate their potential applications, this review discusses the antimicrobial, antibacterial, antifungal, antiviral, antidermatophytic, anti-inflammatory, antitumor, hepatoprotective, cytotoxic, hypotensive, and immunomodulatory activities of these AgNPs. The synthesis of AgNPs using fungi is a clean, green, inexpensive, eco-friendly, reliable, and safe method that can be used for a range of applications in real life for the benefit of human beings.


Assuntos
Fungos/química , Fungos/metabolismo , Nanopartículas Metálicas/química , Prata/química
7.
Phys Chem Chem Phys ; 18(5): 3921-8, 2016 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-26765211

RESUMO

Developing a high-performance photocatalyst and a photoelectrode with enhanced visible light harvesting properties is essential for practical visible light photocatalytic applications. Noble metal-free, highly visible light-active, elemental red phosphorus (RP) was prepared by a facile mechanical ball milling method, which is a reproducible, low cost and controllable synthesis process. The synthesis used inexpensive and abundant raw materials because most RP hybrids are based on expensive noble-metals. The novel milled RP showed significantly enhanced photocatalytic and photoelectrochemical performances with a lower charge transfer resistance compared to commercial RP under wide visible photoirradiation, making it a feasible alternative for photocatalytic applications.

8.
Phys Chem Chem Phys ; 18(13): 9053-60, 2016 Apr 07.
Artigo em Inglês | MEDLINE | ID: mdl-26967202

RESUMO

Fibrous Pani-MnO2 nanocomposite were prepared using a one-step and scalable in situ chemical oxidative polymerization method. The formation, structural and morphological properties were investigated using a range of characterization techniques. The electrochemical capacitive behavior of the fibrous Pani-MnO2 nanocomposite was examined by cyclic voltammetry and galvanostatic charge-discharge measurements using a three-electrode experimental setup in an aqueous electrolyte. The fibrous Pani-MnO2 nanocomposite achieved high capacitance (525 F g(-1) at a current density of 2 A g(-1)) and excellent cycling stability of 76.9% after 1000 cycles at 10 A g(-1). Furthermore, the microbial fuel cell constructed with the fibrous Pani-MnO2 cathode catalyst showed an improved power density of 0.0588 W m(-2), which was higher than that of pure Pani and carbon paper, respectively. The improved electrochemical supercapacitive performance and cathode catalyst performance in microbial fuel cells were attributed mainly to the synergistic effect of Pani and MnO2 in fibrous Pani-MnO2, which provides high surface area for the electrode/electrolyte contact as well as electronic conductive channels and exhibits pseudocapacitance behavior.


Assuntos
Compostos de Anilina/química , Fontes de Energia Bioelétrica , Eletrodos , Compostos de Manganês/química , Nanocompostos/química , Óxidos/química , Catálise , Microscopia Eletrônica de Varredura , Difração de Raios X
9.
Int J Mol Sci ; 18(1)2016 Dec 24.
Artigo em Inglês | MEDLINE | ID: mdl-28029116

RESUMO

Microbial fuel cells (MFCs) are a promising green approach for wastewater treatment with the simultaneous advantage of energy production. Among the various limiting factors, the cathodic limitation, with respect to performance and cost, is one of the main obstacles to the practical applications of MFCs. Despite the high performance of platinum and other metal-based cathodes, their practical use is limited by their high cost, low stability, and environmental toxicity. Oxygen is the most favorable electron acceptor in the case of MFCs, which reduces to water through a complicated oxygen reduction reaction (ORR). Carbon-based ORR catalysts possessing high surface area and good electrical conductivity improve the ORR kinetics by lowering the cathodic overpotential. Recently, a range of carbon-based materials have attracted attention for their exceptional ORR catalytic activity and high stability. Doping the carbon texture with a heteroatom improved their ORR activity remarkably through the favorable adsorption of oxygen and weaker molecular bonding. This review provides better insight into ORR catalysis for MFCs and the properties, performance, and applicability of various metal-free carbon-based electrocatalysts in MFCs to find the most appropriate cathodic catalyst for the practical applications. The approaches for improvement, key challenges, and future opportunities in this field are also explored.


Assuntos
Reatores Biológicos , Carbono/química , Técnicas Eletroquímicas/métodos , Biodegradação Ambiental , Catálise , Oxirredução , Águas Residuárias/química , Águas Residuárias/microbiologia
10.
Environ Microbiol ; 17(4): 1234-44, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-25040348

RESUMO

Bacteria utilize signal molecules to ensure their survival in environmental niches, and indole is an interspecies and interkingdom signalling molecule, which is widespread in the natural environment. In this study, we sought to identify novel roles of indole in soil-borne bacterium Agrobacterium tumefaciens. Agrobacterium tumefaciens was found not to synthesize indole and to degrade it rapidly. The addition of exogenous indole dose-dependently inhibited A. tumefaciens growth and decreased its motility. Surprisingly, indole markedly increased A. tumefaciens biofilm formation on polystyrene, glass and nylon membrane surfaces and enhanced its antibiotic tolerance. Transcriptional analysis showed that indole markedly up-regulated several biofilm-related (celA, cheA, exoR, phoB, flgE, fliR and motA), stress-related genes (clpB, dnaK, gsp, gyrB, marR and soxR) and efflux genes (emrA, norM, and Atu2551) in A. tumefaciens, which partially explained the increased biofilm formation and antibiotic tolerance. In contrast, the plant auxin indole-3-acetic acid did not affect biofilm formation, antibiotic tolerance or gene expression. Interestingly, indole was found to exhibit several similarities with antibiotics, as it inhibited the growth of non-indole-producing bacteria, whereas these bacteria countered its effects by rapidly degrading indole, and by enhancing biofilm formation and antibiotic tolerance.


Assuntos
Agrobacterium tumefaciens/metabolismo , Biofilmes/crescimento & desenvolvimento , Ácidos Indolacéticos/metabolismo , Indóis/metabolismo , Transporte Biológico , Farmacorresistência Bacteriana , Regulação Bacteriana da Expressão Gênica , Ácidos Indolacéticos/farmacologia , Indóis/farmacologia , Plantas/microbiologia , Transdução de Sinais , Propriedades de Superfície
11.
Chemphyschem ; 16(15): 3214-32, 2015 Oct 26.
Artigo em Inglês | MEDLINE | ID: mdl-26336943

RESUMO

A facile three-step co-precipitation method is developed to synthesize graphitic carbon nanofibers (CNFs) decorated with ZnO nanoparticles (NPs). By interchanging intermediate steps of the reaction processes, two kinds of nanohybrids are fabricated with stark morphological and physicochemical differences. The morphologies differ because of the different chemical environments of the NP/nanocluster formation. The hybrid with larger and non-uniform ZnO nanocluster size is formed in liquid phase and resulted in considerable interfacial defects that deteriorate the charge-transfer properties. The hybrid with smaller and uniform ZnO NPs was formed in a dry solid phase and produced near-defect-free interfaces, leading to efficient charge transfer for superior photocatalytic performance. The results broaden the understanding of the anchoring/bonding mechanism in ZnO/CNF hybrid formation and may facilitate further development of more effective exfoliation strategies for the preparation of high-performance composites/hybrids.

12.
Biofouling ; 31(1): 1-11, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25535776

RESUMO

The emergence of antibiotic resistant Staphylococcus aureus presents a worldwide problem that requires non-antibiotic strategies. This study investigated the anti-biofilm and anti-hemolytic activities of four red wines and two white wines against three S. aureus strains. All red wines at 0.5-2% significantly inhibited S. aureus biofilm formation and hemolysis by S. aureus, whereas the two white wines had no effect. Furthermore, at these concentrations, red wines did not affect bacterial growth. Analyses of hemolysis and active component identification in red wines revealed that the anti-biofilm compounds and anti-hemolytic compounds largely responsible were tannic acid, trans-resveratrol, and several flavonoids. In addition, red wines attenuated S. aureus virulence in vivo in the nematode Caenorhabditis elegans, which is killed by S. aureus. These findings show that red wines and their compounds warrant further attention in antivirulence strategies against persistent S. aureus infection.


Assuntos
Biofilmes/efeitos dos fármacos , Flavonoides/farmacologia , Hemólise/efeitos dos fármacos , Staphylococcus aureus/efeitos dos fármacos , Vinho , Animais , Antibacterianos/farmacologia , Caenorhabditis elegans/microbiologia , Eritrócitos/efeitos dos fármacos , Humanos , Quercetina/farmacologia , Resveratrol , Staphylococcus aureus/patogenicidade , Estilbenos/farmacologia , Taninos/farmacologia , Virulência/efeitos dos fármacos
13.
J Nat Prod ; 77(1): 168-72, 2014 Jan 24.
Artigo em Inglês | MEDLINE | ID: mdl-24456071

RESUMO

Biofilm formation is closely related to bacterial infection and is also a mechanism of antimicrobial resistance. Hence, the antibiofilm approach provides an alternative to an antibiotic strategy. In this study, the antibiofilm activities of resveratrol (1) and five of its oligomers, namely, ε-viniferin (2), suffruticosol A (3), suffruticosol B (4), vitisin A (5), and vitisin B (6), were investigated against enterohemorrhagic Escherichia coli O157:H7 and Pseudomonas aeruginosa PA14. Vitisin B (6), a stilbenoid tetramer, was found to inhibit biofilm formation by the two bacteria the most effectively and at 5 µg/mL inhibited E. coli O157:H7 biofilm formation by more than 90%.


Assuntos
Benzofuranos/farmacologia , Biofilmes/efeitos dos fármacos , Escherichia coli O157/efeitos dos fármacos , Fenóis/farmacologia , Pseudomonas aeruginosa/efeitos dos fármacos , Estilbenos/farmacologia , Antibacterianos/farmacologia , Benzofuranos/química , Estrutura Molecular , Fenóis/química , Resveratrol , Estilbenos/química
14.
Appl Microbiol Biotechnol ; 98(22): 9447-57, 2014 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-25027570

RESUMO

The long-term usage of antibiotics has resulted in the evolution of multidrug-resistant bacteria. Unlike antibiotics, anti-virulence approaches target bacterial virulence without affecting cell viability, which may be less prone to develop drug resistance. Staphylococcus aureus is a major human pathogen that produces diverse virulence factors, such as α-toxin, which is hemolytic. Also, biofilm formation of S. aureus is one of the mechanisms of its drug resistance. In this study, anti-biofilm screening of 83 essential oils showed that black pepper, cananga, and myrrh oils and their common constituent cis-nerolidol at 0.01 % markedly inhibited S. aureus biofilm formation. Furthermore, the three essential oils and cis-nerolidol at below 0.005 % almost abolished the hemolytic activity of S. aureus. Transcriptional analyses showed that black pepper oil down-regulated the expressions of the α-toxin gene (hla), the nuclease genes, and the regulatory genes. In addition, black pepper, cananga, and myrrh oils and cis-nerolidol attenuated S. aureus virulence in the nematode Caenorhabditis elegans. This study is one of the most extensive on anti-virulence screening using diverse essential oils and provides comprehensive data on the subject. This finding implies other beneficial effects of essential oils and suggests that black pepper, cananga, and myrrh oils have potential use as anti-virulence strategies against persistent S. aureus infections.


Assuntos
Antibacterianos/farmacologia , Cananga/química , Óleos Voláteis/farmacologia , Piper nigrum/química , Sesquiterpenos/farmacologia , Staphylococcus aureus/efeitos dos fármacos , Terpenos/farmacologia , Animais , Antibacterianos/isolamento & purificação , Biofilmes/efeitos dos fármacos , Caenorhabditis elegans/microbiologia , Modelos Animais de Doenças , Perfilação da Expressão Gênica , Hemólise/efeitos dos fármacos , Óleos Voláteis/isolamento & purificação , Sesquiterpenos/isolamento & purificação , Staphylococcus aureus/fisiologia , Análise de Sobrevida , Terpenos/isolamento & purificação , Virulência/efeitos dos fármacos
15.
Biofouling ; 30(5): 627-37, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24735097

RESUMO

Thermoresponsive polymers have potential biomedical applications for drug delivery and tissue engineering. Here, two thermoresponsive oligomers were synthesized, viz. oligo(N-isopropylacrylamide) (ONIPAM) and oligo(N-vinylcaprolactam) (OVCL), and their anti-biofouling abilities investigated against enterohemorrhagic E. coli O157:H7, which produces Shiga-like toxins and forms biofilms. Biofilm formation (biofouling) is closely related to E. coli O157:H7 infection and constitutes a major mechanism of antimicrobial resistance. The synthetic OVCL (MW 679) and three commercial OVCLs (up to MW 54,000) at 30 µg ml(-1) were found to inhibit biofouling by E. coli O157:H7 at 37 °C by more than 80% without adversely affecting bacterial growth. The anti-biofouling activity of ONIPAM was weaker than that of OVCL. However, at 25 °C, ONIPAM and OVCL did not affect E. coli O157:H7 biofouling. Transcriptional analysis showed that OVCL temperature-dependently downregulated curli genes in E. coli O157:H7, and this finding was in line with observed reductions in fimbriae production and biofouling. In addition, OVCL downregulated the Shiga-like toxin genes stx1 and stx2 in E. coli O157:H7 and attenuated its in vivo virulence in the nematode Caenorhabditis elegans. These results suggest that OVCL has potential use in antivirulence strategies against persistent E. coli O157:H7 infection.


Assuntos
Resinas Acrílicas/farmacologia , Incrustação Biológica/prevenção & controle , Caprolactama/análogos & derivados , Caprolactama/farmacologia , Escherichia coli O157/fisiologia , Polímeros/farmacologia , Temperatura , Resinas Acrílicas/química , Caprolactama/química , Regulação para Baixo , Escherichia coli O157/genética , Escherichia coli O157/patogenicidade , Polímeros/química , Virulência
16.
Foodborne Pathog Dis ; 11(9): 710-7, 2014 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-25007234

RESUMO

Stilbenoids have a broad range of beneficial health effects. On the other hand, the emergence of antibiotic-resistant Staphylococcus aureus presents a worldwide problem that requires new antibiotics or nonantibiotic strategies. S. aureus produces α-hemolysin (a pore-forming cytotoxin) that has been implicated in the pathogenesis of sepsis and pneumonia. Furthermore, the biofilms formed by S. aureus constitute a mechanism of antimicrobial resistance. In this study, we investigated the hemolytic and antibiofilm activities of 10 stilbene-related compounds against S. aureus. trans-Stilbene and resveratrol at 10 µg/mL were found to markedly inhibit human blood hemolysis by S. aureus, and trans-stilbene also inhibited S. aureus biofilm formation without affecting its bacterial growth. Furthermore, trans-stilbene and resveratrol attenuated S. aureus virulence in vivo in the nematode Caenorhabditis elegans, which is normally killed by S. aureus. Transcriptional analysis showed that trans-stilbene repressed the α-hemolysin hla gene and the intercellular adhesion locus (icaA and icaD) in S. aureus, and this finding was in line with observed reductions in virulence and biofilm formation. In addition, vitisin B, a stilbenoid tetramer, at 1 µg/mL was observed to significantly inhibit human blood hemolysis by S. aureus.


Assuntos
Antibacterianos/farmacologia , Biofilmes/efeitos dos fármacos , Hemólise/efeitos dos fármacos , Infecções Estafilocócicas/tratamento farmacológico , Staphylococcus aureus/efeitos dos fármacos , Estilbenos/farmacologia , Animais , Antibacterianos/química , Proteínas de Bactérias/efeitos dos fármacos , Proteínas de Bactérias/genética , Toxinas Bacterianas/genética , Caenorhabditis elegans , Proteínas Hemolisinas/efeitos dos fármacos , Proteínas Hemolisinas/genética , Humanos , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus/patogenicidade , Staphylococcus aureus/fisiologia , Estilbenos/química , Virulência
17.
Appl Microbiol Biotechnol ; 97(10): 4543-52, 2013 May.
Artigo em Inglês | MEDLINE | ID: mdl-23318836

RESUMO

Human pathogens can readily develop drug resistance due to the long-term use of antibiotics that mostly inhibit bacterial growth. Unlike antibiotics, antivirulence compounds diminish bacterial virulence without affecting cell viability and thus, may not lead to drug resistance. Staphylococcus aureus is a major agent of nosocomial infections and produces diverse virulence factors, such as the yellow carotenoid staphyloxanthin, which promotes resistance to reactive oxygen species (ROS) and the host immune system. To identify novel antivirulence compounds, bacterial signal indole present in animal gut and diverse indole derivatives were investigated with respect to reducing staphyloxanthin production and the hemolytic activity of S. aureus. Treatment with indole or its derivative 7-benzyloxyindole (7BOI) caused S. aureus to become colorless and inhibited its hemolytic ability without affecting bacterial growth. As a result, S. aureus was more easily killed by hydrogen peroxide (H2O2) and by human whole blood in the presence of indole or 7BOI. In addition, 7BOI attenuated S. aureus virulence in an in vivo model of nematode Caenorhabditis elegans, which is readily infected and killed by S. aureus. Transcriptional analyses showed that both indole and 7BOI repressed the expressions of several virulence genes such as α-hemolysin gene hla, enterotoxin seb, and the protease genes splA and sspA and modulated the expressions of the important regulatory genes agrA and sarA. These findings show that indole derivatives are potential candidates for use in antivirulence strategies against persistent S. aureus infection.


Assuntos
Indóis/metabolismo , Staphylococcus aureus/patogenicidade , Virulência , Sequência de Bases , Primers do DNA , Humanos , Reação em Cadeia da Polimerase em Tempo Real
18.
J Nanosci Nanotechnol ; 13(11): 7712-6, 2013 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-24245320

RESUMO

The anode electrode material is a crucial factor for the overall performance of a microbial fuel cell (MFC). In this study, a plain carbon paper modified with the CNT/MnO2 nanocomposite was used as the anode for the MFC and a mixed culture inoculum was used as the biocatalyst. The modified anode showed better electrochemical performance than that of plain carbon paper, and Brunauer Emmett Teller (BET) analysis showed the high surface area (94.6 m2/g) of the composite. The Mn4+ in the nanocomposite may enhance the electron transfer between the microorganisms and the anode material which facilitates electron conduction. Additionally, MnO2 can be used to store electrons due to its supercapacitance, which is comparable to that of the cytochromes present in the outer cell membranes of electrochemically active microorganisms. The MFC with a modified anode produced a maximum power density of 120 +/- 1.7 mW/m2, while the corresponding current density was 0.262 +/- 0.015 A/m2 at an external resistor of 800 omega with an open circuit voltage (OCV) of 1.07 +/- 0.02 V. The unusually high OCV may be attributed to the high charge density developed on the bioanode by the charge accumulation in the MnO2 of the bioanode. This study showed that the CNT/MnO2 nanocomposite can be an excellent anode material for MFC.


Assuntos
Bactérias Anaeróbias/fisiologia , Fontes de Energia Bioelétrica/microbiologia , Eletrodos/microbiologia , Compostos de Manganês/química , Nanotecnologia/instrumentação , Nanotubos de Carbono/química , Nanotubos de Carbono/ultraestrutura , Óxidos/química , Transferência de Energia , Desenho de Equipamento , Análise de Falha de Equipamento , Teste de Materiais , Tamanho da Partícula
19.
J Nanosci Nanotechnol ; 13(9): 6079-85, 2013 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-24205603

RESUMO

Positively charged gold nanoparticles [(+) AuNPs] of 5-20 nm were synthesized by using electrochemically active biofilm (EAB) formed on a stainless steel mesh, within 30 minutes, in aqueous solution containing HAuCl4 as a precursor and sodium acetate as an electron donor. Electrochemically active bacteria present on biofilm oxidize the sodium acetate by producing electrons. Simultaneously, stainless steel also provides electrons because of the Cl- ions penetration into the stainless steel. Combined effect of both the EAB and stainless steel mesh enhances the availability of electrons for the reduction of Au3+ in the solution, which makes this synthesis efficient and fast. Therefore, small size, positively charged (+32.72 mV), monodispersed, controlled, easy separation and extracellular synthesis of (+) AuNPs makes this protocol highly significant. As-synthesized AuNPs were characterized by UV-vis, DLS, XRD, TEM, HRTEM, EDX and SAED. (+) AuNPs shows remarkable enhancement in the rate of reduction of methyl orange by NaBH4 because of the electron relay effect.


Assuntos
Biofilmes , Ouro/química , Nanopartículas Metálicas , Eletroquímica , Microscopia Eletrônica de Transmissão , Análise Espectral , Difração de Raios X
20.
J Nanosci Nanotechnol ; 13(9): 6140-4, 2013 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-24205616

RESUMO

A novel, rapid, one-pot, and facile approach was developed to synthesize positively charged gold nanoparticles [(+) AuNPs] by employing an aqueous solution of HAuCl4 x 3H2O as a precursor at 30 degrees C and a stainless-steel mesh as a reducing agent. The penetration of Cl- ions into the stainless-steel surface results in corrosion on the stainless-steel surface and excretion of electrons which are used for reduction of Au3+ --> Au0. As a result, (+) AuNPs 5-20 nm in size, mostly monodispersed, were synthesized within 3 h. The as-synthesized AuNPs were charaterized by UV-vis, DLS, XRD, TEM, HR-TEM, EDX and SAED. The utilization of non-toxic chemicals and easily available materials, and the non-requirement of energy input, make this methodology easy, inexpensive, and efficient. The new findings about the role of the stainless-steel mesh, which provides electrons in the presence of Cl- ions, for the reduction of Au3+ --> Au0, makes it a novel material for (+) AuNPs synthesis.

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