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Chemotherapy resistance is one of the main challenges in melanoma treatment. Violacein, a natural pigment produced by Chromobacterium violaceum, induces apoptosis in a variety of tumours, including melanoma. Here, we used BRAF-mutated melanoma spheroids to test the potential of violacein as a sensitizer of cellular viability and levels of the proteins p62 and fatty acid synthase (FASN). Importantly, violacein in combination with vemurafenib (ViVe) was able to interfere with spheroid survival at subtoxic concentrations. The results demonstrated that the ViVe protocol triggered cell death assessed by calcein and ethidium homodimer dyes. Accordingly, melanoma cells in 2D systems also showed a higher apoptosis rate when treated with ViVe. In the current study, we show evidence that ViVe downregulates crucial mediators like FASN, which partially explains how it acts as a sensitizer and ultimately improves the effectiveness of vemurafenib against melanoma cells.
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Violacein is an important natural antimicrobial pigment that is mainly produced by Chromobacterium violaceum and Janthinobacterium lividum. It presents a significant range of effects against phytopathogenic and human fungi, besides being featured as having low toxicity, and by its important ecological role in protecting amphibian species and applications in dyed medical fabric. The hypothesis about violacein's action mechanisms against mucormycosis (Rhizopus arrhizus) and candidiasis (Candida auris) is herein discussed based on data available in the scientific literature.
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Antiinfecciosos , Antifúngicos , Antifúngicos/farmacología , Chromobacterium , Hongos , Humanos , IndolesRESUMEN
The development of versatile carriers to deliver chemotherapeutic agents to specific targets with establishing drug release kinetics and minimum undesirable side effects is becoming a promising relevant tool in the medical field. Magnetic hybrid nanostructured lipid carriers (NLC) were prepared by incorporation of 1,8-cineole (CN, a monoterpene with antiproliferative properties) and maghemite nanoparticles (MNPs) into a hybrid matrix composed of myristyl myristate coated with chitosan. Hybrid NLC characterized by DLS and TEM confirmed the presence of positively charged spherical nanoparticles of around 250 nm diameter and +10.2 mV of Z-potential. CN encapsulation into the lipid core was greater than 75 % and effectively released in 24 h. Modification of the crystalline structure of nanoparticles after incorporation of CN and MNPs was observed by XRD, DSC, and TGA analyses. Superparamagnetic NLC behavior was verified by recording the magnetization using a vibrating scanning magnetometer. NLC resulted in more cytotoxic than free CN in HepG2 and A549 cell lines. Particularly, viability inhibition of HepG2 and A549 cells was increased from 35 % to 55 % and from 38 % to 61 %, respectively, when 8 mM CN was incorporated into the lipid NPs at 24 h. Green fluorescent-labeled NLC with DIOC18 showed an enhanced cellular uptake with chitosan-coated NLC. Besides, no cytotoxicity of the formulations in normal WI-38 cells was observed, suggesting that the developed hybrid NLC system is a safe and good potential candidate for the selective delivery and potentiation of anticancer drugs.
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Antineoplásicos , Nanopartículas , Nanoestructuras , Antineoplásicos/farmacología , Portadores de Fármacos , Eucaliptol , Lípidos , Fenómenos Magnéticos , Tamaño de la PartículaRESUMEN
BACKGROUND: Multidrug-resistant bacteria such as extended-spectrum beta-lactamase (ESBL), Enterobacteriaceae, and methicillin-resistant Staphylococcus aureus (MRSA) pose a challenge to the human health care system. MRSA is among the major causes of hospital-acquired and community infections. METHODS: Therefore, in the present study, we evaluated the antibacterial activity of silver nanoparticles synthesized by Fusarium oxysporum (AgNPbio) in combination with simvastatin against reference and multidrug-resistant bacterial strains. RESULTS: Simvastatin showed a minimal inhibitory concentration (MIC) ranging from 0.062 to 0.25 mg mL-1 against MRSA. AgNPbio with a size of 77.68± 33.95 nm and zeta potential -34.6 ± 12.7 mV showed an MIC of 0.212 mg mL-1 against S. aureus including MRSA strains. The checkerboard assay and time-kill curves exhibited a synergistic effect of the simvastatin-AgNPbio combination on antibacterial activity against MRSA strains. The combination of simvastatin and AgNPbio demonstrated antibacterial activity against Escherichia coli producing ESBL. Scanning electron microscopy showed the formation of cell surface protrusions after treatment with AgNPbio and the formation of a large amorphous mass after treatment with simvastatin, both in MRSA. CONCLUSION: Our results indicate that the combination of AgNPbio and simvastatin could be a great future alternative in the control of bacterial infections, where, when combined with simvastatin, smaller doses of AgNPbio are required, with the same antibacterial activity.
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Antibacterianos/farmacología , Farmacorresistencia Bacteriana Múltiple/efectos de los fármacos , Escherichia coli/efectos de los fármacos , Fusarium/metabolismo , Nanopartículas del Metal/química , Staphylococcus aureus Resistente a Meticilina/efectos de los fármacos , Plata/farmacología , Simvastatina/farmacología , Muerte Celular/efectos de los fármacos , Sinergismo Farmacológico , Eritrocitos/efectos de los fármacos , Fusarium/efectos de los fármacos , Fusarium/ultraestructura , Humanos , Nanopartículas del Metal/ultraestructura , Staphylococcus aureus Resistente a Meticilina/ultraestructura , Pruebas de Sensibilidad MicrobianaRESUMEN
The consumption of sweeteners has increased as a measure to reduce the consumption of calories and thus combat obesity and diabetes. Sweeteners are found in a large number of products, so chronic consumption has been little explored. The objective of the study was to evaluate the effect of chronic sweetener consumption on the microbiota and immunity of the small intestine in young mice. We used 72 CD1 mice of 21 days old, divided into 3 groups: (i) No treatment, (ii) Group A (6 weeks of treatment), and (iii) Group B (12 weeks of treatment). Groups A and B were divided into 4 subgroups: Control (CL), Sucrose (Suc), Splenda® (Spl), and Svetia® (Sv). The following were determined: anthropometric parameters, percentage of lymphocytes of Peyer's patches and lamina propria, IL-6, IL-17, leptin, resistin, C-peptide, and TNF-α. From feces, the microbiota of the small intestine was identified. The BMI was not modified; the mice preferred the consumption of Splenda® and Svetia®. The percentage of CD3+ lymphocytes in Peyer's patches was increased. In the lamina propria, Svetia® increased the percentage of CD3+ lymphocytes, but Splenda® decreases it. The Splenda® and Svetia® subgroups elevate leptin, C-peptide, IL-6, and IL-17, with reduction of resistin. The predominant genus in all groups was Bacillus. The chronic consumption of sweeteners increases the population of lymphocytes in the mucosa of the small intestine. Maybe, Bacillus have the ability to adapt to sweeteners regardless of the origin or nutritional contribution of the same.
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In the global context of an imminent emergence of multidrug-resistant microorganisms, the present work combined the use of nanotechnology and the therapeutic benefits of natural compounds as a strategy to potentiate antimicrobial action of the wide-spectrum antibiotic Ofloxacin (Ofx). Hybrid solid lipid nanoparticles (SLN) were synthesized by incorporation of chitosan (Chi, a cationic biopolymer with antimicrobial activity) and eugenol (Eu, a phenolic compound that interferes with bacterial quorum sensing) into a lipid matrix by hot homogenization/ultrasonication method. The developed SLN/Chi/Eu sustainably released the encapsulated Ofx for 24â¯h. Characterization by DLS, TEM, DSC, TGA and XRD revealed the presence of positively charged spherical nanoparticles with diameters around 300â¯nm and Ofx entrapped in amorphous state. The SLN exhibited an enhanced bactericidal activity against Pseudomonas aeruginosa and Staphylococcus aureus. The minimum inhibitory concentration (MIC) for free and nanoencapsulated Ofx formulations was below 1.0⯵g/ml. The MIC values decreased by 6.1- to 16.1-fold when Ofx was encapsulated in SLN/Chi/Eu. Fluorescent-labeled nanoparticles had the ability to interact with the bacterial cell membrane. Selective toxicity of SLN/Chi/Eu-Ofx was tested in the range of 0.3-30.0⯵g/ml and showed no toxicity up to 3.0⯵g/ml Ofx in human cell models (A549 and Wi-38) at 24â¯h and 48â¯h exposure. It was proved that the administration of hybrid SLN to mice by dry powder inhalation reached therapeutic Ofx levels in lungs.
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Antiinfecciosos , Portadores de Fármacos , Eugenol , Nanopartículas , Ofloxacino , Células A549 , Animales , Antiinfecciosos/administración & dosificación , Antiinfecciosos/química , Antiinfecciosos/farmacocinética , Supervivencia Celular/efectos de los fármacos , Portadores de Fármacos/administración & dosificación , Portadores de Fármacos/química , Portadores de Fármacos/farmacocinética , Liberación de Fármacos , Eugenol/administración & dosificación , Eugenol/química , Eugenol/farmacocinética , Humanos , Lípidos/administración & dosificación , Lípidos/química , Lípidos/farmacocinética , Pulmón/metabolismo , Ratones , Nanopartículas/administración & dosificación , Nanopartículas/química , Ofloxacino/administración & dosificación , Ofloxacino/química , Ofloxacino/farmacocinética , Pseudomonas aeruginosa/efectos de los fármacos , Pseudomonas aeruginosa/crecimiento & desarrollo , Staphylococcus aureus/efectos de los fármacos , Staphylococcus aureus/crecimiento & desarrolloRESUMEN
Se presenta el caso de una paciente de 73 años de edad que, a los 30 años aproximadamente, comenzó a quejarse de dolor al caminar, localizando la molestia a nivel de las regiones aquilianas, con subsecuente aumento de volumen; al paso del tiempo, estas molestias la obligaron a efectuar consulta médica. Los análisis de laboratorio mostraron severa dislipidemia mixta. Al lado de información de significativa declinación cognitiva, provista por familiares (vgr., (i.e., olvidos frecuentes, desorientación, atención disminuida, concentración pobre), hubo evidencia de ánimo fluctuante, labilidad emocional, crisis ansiosas evolucionando hacia ataques de pánico. El test minicognitivo de Folstein, mostró severo estado demencial y en el examen neurológico se constataron ataxia cerebelosa y signos de piramidalismo parcial. El examen oftalmológico puso en evidencia xantelasmas, cataratas y un denso arco senil. El estudio del cerebro con resonancia magnética (RM) mostró el daño encefálico y signos sugestivos de depósitos del colastenol en el SNC. La presencia de xantomas , los hallazgos oftalmológicos, la demencia definidamente progresiva y la ataxia cerebelosa fueron hallazgos clÃnicos que permitieron establecer el diagnóstico de xantomatosis cerebrotendinosa.
The case of a 73 years-old woman that, since approximately the age of 30 years started to complain of pain when walking, is presented. The symptom was mainly located in the acchillean regions which, as time advanced, showed gradual volume increase and, finally, forced her to seek medical evaluation. Accompanying relatives reported a several yearsâ history of gradually increasing cognitive difficulties (i.e., forgetfulness, disorientation, poor attention and concentration), fluctuating mood (from periods of good humor switching to sudden episodes of sadness and crying spells), emotional lability and anxiety crises evolving into brief panic attacks. The Mini-cognitive Fenton Test confirmed severe dementia and the neurological evaluation showed cerebellar ataxia and partial pyramidalism. The ophthalmological examination revealed xanthelasmas, cataracts and dense arcus senilis. Xanthomas were detected in the Achillean tendons of both lower extremities. Auxiliary laboratory and densitometric tests demonstrated mixed dyslipidemia and dorsal-lumbar osteoporosis, respectively, and magnetic resonance imaging of the brain (RMC) confirmed SNC damage and suggested deposits of cholestenol, thus confirming the diagnosis of Cerebroitendinous Xanthomatosis.
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Metal nanoparticles and metal oxides nanoparticles (MNPs/MONPs) have been widely included in a great diversity of products and industrial applications and they are already a part of our everyday life. According to estimation studies, their production is expected to increase exponentially in the next few years. Consequently, soil has been suggested as the main sink of MNPs/MONPs once they are deliberately or accidentally released into the environment. The potential negative perturbations that may result on soil microbial communities and ecological processes are resulting in concerns. Several nano-toxicological studies of MNPs/MONPs, reported so far, have focused on aquatic organisms, animals, and soil invertebrates. However, during recent years, the studies have been oriented to understand the effects of MNPs/MONPs on microbial communities and their interaction with soil components. The studies have suggested that MNPs/MONPs are one of the most toxic type to soil biota, amongst different types of nanomaterials. This may threaten soil health and fertility, since microbial communities are known to support important biological processes and ecosystem services such as the nutrient cycling, whereby their protection against the environmental pollution is imperative. Therefore, in this review we summarize the actual knowledge available from the last five years (2013-2018) and gaps about the potential negative, positive or neutral effects produced on soil by different classes of MNPs/MONPs. A particular emphasis has been placed on the associated soil microorganisms and biological processes. Finally, perspectives about future research are discussed.
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Nanopartículas del Metal , Metales , Óxidos , Microbiología del Suelo , Contaminantes del Suelo , Nanopartículas del Metal/química , Nanopartículas del Metal/toxicidad , Metales/química , Metales/toxicidad , Microbiota , Nanotecnología , Óxidos/química , Óxidos/toxicidad , Suelo/química , Contaminantes del Suelo/química , Contaminantes del Suelo/toxicidadRESUMEN
Currently for bacterial identification and classification the rrs gene encoding 16S rRNA is used as a reference method for the analysis of strains of the genus Nocardia. However, it does not have enough polymorphism to differentiate them at the species level. This fact makes it necessary to search for molecular targets that can provide better identification. The sodA gene (encoding the enzyme superoxide dismutase) has had good results in identifying species of other Actinomycetes. In this study the sodA gene is proposed for the identification and differentiation at the species level of the genus Nocardia. We used 41 type species of various collections; a 386 bp fragment of the sodA gene was amplified and sequenced, and a phylogenetic analysis was performed comparing the genes rrs (1171 bp), hsp65 (401 bp), secA1 (494 bp), gyrB (1195 bp) and rpoB (401 bp). The sequences were aligned using the Clustal X program. Evolutionary trees according to the neighbour-joining method were created with the programs Phylo_win and MEGA 6. The specific variability of the sodA genus of the genus Nocardia was analysed. A high phylogenetic resolution, significant genetic variability, and specificity and reliability were observed for the differentiation of the isolates at the species level. The polymorphism observed in the sodA gene sequence contains variable regions that allow the discrimination of closely related Nocardia species. The clear specificity, despite its small size, proves to be of great advantage for use in taxonomic studies and clinical diagnosis of the genus Nocardia.
Actualmente, para la identificación y clasificación bacteriana se utiliza como método de referencia la secuenciación el gen rrs que codifica al rRNA16S, en el caso del análisis de cepas del género Nocardia, sin embargo, no tiene el suficiente polimorfismo para diferenciarlas a nivel de especie lo que hace necesaria la búsqueda de blancos moleculares que puedan proporcionar una mejor identificación. El gen sodA (que codifica la enzima superóxido dismutasa) ha tenido buenos resultados en la identificación de especies de otros Actinomicetos. En este estudio se propone para la identificación y diferenciación a nivel de especie del género Nocardia. Se utilizaron 41 especies Tipo de diversas colecciones, se amplificó y secuenció un fragmento de 386 pb del gen sodA y se realizó un análisis filogenético comparando los genes rrs (1171 pb) hsp65(401pb) secA1 (494pb), gyrB (1195pb) y rpoB (401pb), las secuencias fueron alineadas utilizando el programa Clustal X, los árboles evolutivos de acuerdo con el método de "Neighbor-Joining"se hicieron con el programa Phylo_win y Mega 6. Se analizó la variabilidad específica del gen sodA del género Nocardia presentando una alta resolución filogenética, una variabilidad genética importante, especificidad y confiabilidad para la diferenciación de los aislados a nivel de especie. El polimorfismo observado en la secuencia del gen sodA contiene regiones variables que posibilitan la discriminación de especies de Nocardia estrechamente relacionadas, y una clara especificidad, a pesar de su pequeño tamaño, demostrando ser de gran ventaja para utilizarse en estudios taxonómicos y en el diagnóstico clínico del género Nocardia.
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This overview highlights the importance of characterization of biogenic nanoparticles of silver and silver chloride in order to understand the action on ticks or pathogens transmitted by them. These nanoparticles appear as important active principles in this area. They can act against ticks or against major pathogens transmitted by the bite of ticks such as bacteria, viruses or protozoa with equal or better efficacy of antibiotics, antiviral or antiparasitic agents. Anti-tickactivities on Rhipicephalus (Boophilus) microplus, Hyalomma anatolicum, Hyalomma isaaci and Haemaphysalis bispinosa are discussed. Perspectives of these nanoparticles acting on bacteria,viruses and protozoa infections are also discussed...
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Animales , Argentum Muriaticum , Garrapatas , Nanopartículas/análisis , Nanopartículas , PlataRESUMEN
Graphene and graphene oxide topography have an effect on the fate of stem cells such as adhesion, differentiation, and proliferation. This overview clearly shows that a new design and manipulation of associated graphene oxide stem cell culture platforms are of paramount importance as a focus in stem cell to tissue engineering applications. This overview also proposes that a film of graphene oxide is an efficient platform to modulate structure and function of multipotent mesenchymal stem/stromal cells (MSCs) and in special human adipose tissue derived mesenchymal stromal/stem cells (AT-MSCs). The implication of graphene oxide on osteogenesis, neurogenesis, oligodendrogenesis, adipogenic and epithelial differentiation is also discussed. Graphene oxide toxicity on stem cells and the importance of GO application on ATMSCs differentiation and proliferation are final topics that are being discussed.
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Tejido Adiposo/citología , Diferenciación Celular , Grafito/química , Células Madre Mesenquimatosas/citología , Osteogénesis , Ingeniería de Tejidos/métodos , Animales , Células Cultivadas , Humanos , Andamios del TejidoRESUMEN
Nocardia species are aerobic, Gram-positive bacteria with branched filaments reported as opportunistic microorganisms associated with infectious diseases of the skin. We report the isolation of N. wallacei in Mexico from a 43-year-old man, an HIV-positive construction worker who sought care for difficulty breathing and abundant sputum.
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OBJECTIVES: In this study, the production of extended spectrum beta-lactamase (ESBL), metallo-betalacatamase (MBL) and AmpC beta-lactamase enzymes of Pseudomonas aeruginosa (P aeruginosa) strains which were isolated from clinical samples were investigated. AmpC gene was also detected by the polymerase chain reaction (PCR) analysis. METHODS: A hundred strains of P aeruginosa were included in the study. The presence of ESBL was investigated with combined disk confirmation test, MBL was investigated with E-test method and AmpC beta-lactamase was investigated with disk induction test. In order to detect the production of AmpC betalactamase genotypically, the PCR method was used. RESULTS: Only one strain was found to be MBL positive. Four per cent of strains were found to be ESBL positive. AmpC beta-lactamase production was positive in 73% of the strains with disk induction test. AmpC gene was detected in 96% of the studied strains with the PCR method. CONCLUSION: While ESBL and MBL rates in this study were significantly lower than those found in other studies, the rate of AmpC beta-lactamase was higher. Although AmpC gene was detected in some strains (23%), they were not found to produce AmpC beta-lactamase with disk induction test.
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For many years, cisplatin has been used to treat many types of cancer, including urogenital, skin and lung cancers. Unfortunately, treatment with this drug causes serious side effects, such as severe toxicity; including nephrotoxicity, neurotoxicity, gastrointestinal toxicity, peripheral neuropathy, ototoxicity, asthenia and hematological toxicity.Therefore, the clinical use of cisplatin has been hampered.The incidence of nephrotoxicity frequently prevents the use of high enough doses to maximize the antineoplastic effects, and strict attention must be given to the hydration of cisplatin-treated patients to minimize kidney damage.Nanobiotechnology, or nanomedicine, was developed to mitigate, or even eliminate,the toxic effects of pharmaceutical compounds; for example, drug-targeting systems were developed to enable site specificity and to control the delivery drug. Therefore, biomedical nanotechnology researchers attempted to develop nanostructures not only to deliver chemotherapeutics to the desired treatment site but also to control when and how quickly the compounds are released. To achieve these ends, a drug can either be encapsulated in a matrix or attached to a particle surface. Studies concerning the encapsulation of cisplatin in liposomes, polymeric nanoparticles, solid lipid nanoparticles and carbon nanotubes, as well as the immobilization of cisplatin on metallic nanoparticles, have already been published. The association of cancer treatment, particularly chemotherapeutics, with nanotechnology is currently one of the most exciting areas of research. In this mini-review, cisplatin will be discussed in terms of its efficacy against many cancers, including bladder cancer. Additionally, established nanostructure-based drug delivery systems for cisplatin and their efficacy against different types of cancer will be reviewed. Because cisplatin is a standard treatment with good performance statistics and with an effective renal function-glomerular filtration rate, we expect that this review will be helpful for future research.
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Antineoplásicos/uso terapéutico , Biotecnología , Cisplatino/uso terapéutico , Nanotecnología , Neoplasias/tratamiento farmacológico , HumanosRESUMEN
BACKGROUND: Mexico has the largest number of clinical cases of actinomycetoma in North and South America. Species originally identified by less specific methods have been recently reclassified as other known species or as new species. OBJECTIVE: To assess, by 16S rRNA gene sequencing and phenotypic methods, the species distribution of 18 human clinical isolates originally identified as N. brasiliensis, some of them isolated between 1947 and 1959 in Mexico City. METHODS: Clinical isolates came from the Hospital General, "Dr. Manuel Gea Gonzalez", and Instituto Nacional de Diagnóstico y Referencia Epidemiológica (INDRE) in Mexico, D.F. The strains used in this study included 15 clinical strains isolated between 1947 and 1959 that were originally identified as N. brasiliensis and three more strains obtained in 2007 identified as Nocardia spp. The isolates were identified genotypically by sequencing the 16S rRNA gene, and their phenotypic profiles were obtained with the API Coryne(®) system. Antibiotic susceptibility patterns were tested according to the protocol of the Comité de l'antibiogramme de la Société française de microbiologie[4]. RESULTS: According to 16S rRNA gene, sequencing were identified among 18 human clinical isolates as Nocardia farcinica (n=11) and Nocardia brasiliensis (n=7). A high number of the strains were susceptible to the majority of the antibiotics tested. The phenotypic profiles of the strains were quite uniform for N. farcinica and some variability was observed for N. brasiliensis strains. CONCLUSION: N. farcinica was the most prevalent species identified. Modern methodologies should be applied in clinical laboratories to accurately identify etiological agents.
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Nocardiosis/microbiología , Nocardia/aislamiento & purificación , Antibacterianos/farmacología , Técnicas de Tipificación Bacteriana , Genotipo , Humanos , México/epidemiología , Pruebas de Sensibilidad Microbiana , Nocardia/clasificación , Nocardia/efectos de los fármacos , Nocardia/genética , Nocardiosis/epidemiología , Fenotipo , Filogenia , ARN Ribosómico 16S/genéticaRESUMEN
The interest in developing new sunscreens is increasing due to the harmful effects of UV radiation on the skin, such as erythema, accelerated skin ageing (photoageing) and the induction of skin cancer. However, many molecular sunscreens penetrate into the skin causing photoallergies, phototoxic reactions and skin irritation. Thus, the aim of this work was the preparation and characterization of polymeric and solid lipid nanoparticles to act carriers of benzophenone-3 (BZ3), aiming to improve the safety of sunscreen products by increasing the sun protection factor (SPF), decreasing BZ3 skin penetration and decreasing BZ3 concentration in sunscreen formulation. BZ3 was encapsulated in poly(epsilon-caprolactone) (PCL) nanoparticles by the nanoprecipitation method and in solid lipid nanoparticles (SLN) by the hot high pressure homogenization method. The particles were stable for 40 days. The BZ3 encapsulated in PCL nanoparticles was released faster than BZ3 encapsulated in SLN. The sun protection factor increased when BZ3 was encapsulated in both nanostructures. However, BZ3 encapsulated in PCL nanoparticles decreased its skin permeation more than SLN-BZ3. Furthermore, BZ3 encapsulated in SLN did not exhibit cytotoxic or phototoxic effects in human keratinocytes (HaCaT cells) and BABL/c 3T3 fibroblasts, whereas PCL nanoparticles with BZ3 showed phototoxic potential in HaCaT cells. Nevertheless, BZ3 free and encapsulated in PCL nanoparticles or in SLN did not show allergic reactions in mice. Our results suggest that these nanostructures are interesting carriers for sunscreen.
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Lípidos/química , Nanocápsulas/química , Polímeros/química , Absorción Cutánea/fisiología , Piel/efectos de los fármacos , Protectores Solares/química , Protectores Solares/farmacocinética , Administración Tópica , Animales , Humanos , Ratones , Nanocápsulas/administración & dosificación , Protectores Solares/administración & dosificaciónRESUMEN
Atrazine is a commonly used herbicide for maize production in Chile, but it has recently been shown to be ineffective in soils that receive applications of cow slurries generated from the dairy industry. This effect may be caused either by the sorption of the pesticide to organic matter or more rapid degradation in slurry-amended soils. The objectives of this study were to evaluate the effects of cow slurry on atrazine dissipation, the formation of atrazine metabolites and the modification of bacterial community in Andisol. The cow slurry was applied at doses of 100,000-300,000 Lha(-1). After 4 weeks, atrazine was applied to the slurry-amended soils at concentrations of 1-3 mg kg(-1). The amounts of atrazine and its metabolites were determined by high performance liquid chromatography (HPLC). The soil microbial community was monitored by measurement of CO(2) evolution and changes in bacterial community using PCR-DGGE of 16S rRNA genes. The results show that cow slurry applications had no effect on atrazine dissipation, which had a half-life of 15-19 days. The atrazine metabolites were detected after 20 days and were significantly higher in soils amended with the slurry at both 20 and 40 days after application of the herbicide. Respiration rates were elevated after 10 days in all soils with atrazine addition. Both the atrazine and slurry amendments altered the bacterial community structures, indicated by the appearance of specific bands in the DGGE gels after 10 days. Cloning and sequencing of the 16S rRNA genes from the DGGE gels showed that the bands represented various genera of beta-proteobacteria that appeared in response to atrazine. According to our results, further field studies are required to explain the lower effectiveness of atrazine in weed control. These studies may include the effect of dissolved organic carbon on the atrazine mobility.
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Agricultura , Atrazina/química , Herbicidas/química , Estiércol , Microbiología del Suelo , Suelo/análisis , Agricultura/métodos , Agricultura/normas , Animales , Bacterias/efectos de los fármacos , Bacterias/crecimiento & desarrollo , Bacterias/aislamiento & purificación , Biodegradación Ambiental , Bovinos , Chile , ADN Bacteriano/análisis , ARN Ribosómico 16S/genética , Suelo/normas , Microbiología del Suelo/normasRESUMEN
Electrochemistry based unidimensional nanoelectrodes, such as carbon nanotubes and metallic nanowires, is now a reality that is leaving the academy and reaching a broad range of high-tech companies around the world. The intrinsic properties of electron-electron interactions, sizes and geometries significantly differentiate those nanostructures from conventional macroelectrodes or electrodes with sizes in a millimetric range. The inherent properties as well as the configuration of carbon nanotubes and metallic nanowires as electrochemical sensors are the main focus of this review. Applications and some future trends on developing of a clear pathway for assembly and integration of these into functional materials, are summarized as well.
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In this work we report the synthesis, characterization and application of silver vanadate nanowires decorated with silver nanoparticles as a novel antibacterial agent. These hybrid materials were synthesized by a precipitation reaction of ammonium vanadate and silver nitrate followed by hydrothermal treatment. The silver vanadate nanowires have lengths of the order of microns and diameters around 60 nm. The silver nanoparticles decorating the nanowires present a diameter distribution varying from 1 to 20 nm. The influence of the pH of the reaction medium on the chemical structure and morphology of silver vanadates was studied and we found that synthesis performed at pH 5.5-6.0 led to silver vanadate nanowires with a higher morphological yield. The antimicrobial activity of these materials was evaluated against three strains of Staphylococcus aureus and very promising results were found. The minimum growth inhibiting concentration value against a MRSA strain was found to be ten folds lower than for the antibiotic oxacillin.
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Antibacterianos/química , Nanopartículas del Metal/química , Nanocables/química , Plata/química , Plata/farmacología , Vanadatos/química , Vanadatos/farmacología , Antibacterianos/farmacología , Cristalografía por Rayos X , Concentración de Iones de Hidrógeno , Pruebas de Sensibilidad Microbiana , Microscopía Electrónica de Rastreo , Tamaño de la Partícula , Espectroscopía Infrarroja por Transformada de Fourier , Staphylococcus aureus/efectos de los fármacosRESUMEN
C. violaceum appeared as important bacterium in different applications and mainly these aspects are related to the production of violacein. This review discusses the last reports on biosynthetic pathways, production, genetic aspects, biological activities, pathological effects, antipathogenic screening through quorum sensing, environmental effects and the products of C. violaceum with industrial interest. An important discussion is on biological applications in medicine and as industrial products such as textile and in cosmetics.