Effects of Different Heating Treatments on the Antioxidant Activity and Phenolic Compounds of Ecuadorian Red Dacca Banana.

The banana is a tropical fruit characterized by its composition of healthy and nutritional compounds. This fruit is part of traditional Ecuadorian gastronomy, being consumed in a wide variety of ways. In this context, unripe Red Dacca banana samples and those submitted to different traditional Ecuadorian heating treatments (boiling, roasting, and baking) were evaluated to profile their phenolic content by ultra-high-performance liquid chromatography coupled to high-resolution mass spectrometry (UHPLC-HRMS) and the antioxidant activity by ORAC, ABTS, and DPPH assays. A total of sixty-eight phenolic compounds were identified or tentatively identified in raw banana and treated samples, highlighting the content in flavonoids (flavan-3-ols with 88.33% and flavonols with 3.24%) followed by the hydroxybenzoic acid family (5.44%) in raw banana samples. The total phenolic compound content significantly decreased for all the elaborations evaluated, specifically from 442.12 mg/100 g DW in fresh bananas to 338.60 mg/100 g DW in boiled (23.41%), 243.63 mg/100 g DW in roasted (44.90%), and 109.85 mg/100 g DW in baked samples (75.15%). Flavan-3-ols and flavonols were the phenolic groups most affected by the heating treatments, while flavanones and hydroxybenzoic acids showed higher stability against the heating treatments, especially the boiled and roasted samples. In general, the decrease in phenolic compounds corresponded with a decline in antioxidant activity, evaluated by different methods, especially in baked samples. The results obtained from PCA studies confirmed that the impact of heating on the composition of some phenolic compounds was different depending on the technique used. In general, the heating processes applied to the banana samples induced phytochemical modifications. Even so, they remain an important source of bioactive compounds for consumers.

Bifunctional Au@Pt/Au nanoparticles as electrochemiluminescence signaling probes for SARS-CoV-2 detection.

A novel immunosensor based on electrochemiluminescence resonance energy transfer (ECL-RET) for the sensitive determination of N protein of the SARS-CoV-2 coronavirus is described. For this purpose, bifunctional core@shell nanoparticles composed of a Pt-coated Au core and finally decorated with small Au inlays (Au@Pt/Au NPs) have been synthesized to act as ECL acceptor, using [Ru (bpy)3]2+ as ECL donor. These nanoparticles are efficient signaling probes in the immunosensor developed. The proposed ECL-RET immunosensor has a wide linear response to the concentration of N protein of the SARS-CoV-2 coronavirus with a detection limit of 1.27 pg/mL. Moreover, it has a high stability and shows no response to other proteins related to different virus. The immunosensor has achieved the quantification of N protein of the SARS-CoV-2 coronavirus in saliva samples. Results are consistent with those provided by a commercial colorimetric ELISA kit. Therefore, the developed immunosensor provides a feasible and reliable tool for early and effective detection of the virus to protect the population.

Effect of Drying Technique on the Volatile Content of Ecuadorian Bulk and Fine-Flavor Cocoa.

Cocoa (Theobroma cacao L.) is one of the most widely consumed edible seeds in the world affected by on-farm processing. This study investigated the effect of different drying techniques, namely oven drying (OD), sun drying (SD), and a modification of sun drying using black plastic sheeting (SBPD), on the volatile profile of fine-flavor and bulk cocoa varieties analyzed by HS-SPME-GC-MS. A total of sixty-four volatile compounds were identified in fresh and dried cocoa. As expected, the volatile profile was clearly modified after the drying step, showing strong differences among cocoa varieties, this factor and its interaction with the drying technique having greater influence according to the ANOVA simultaneous component analysis. A principal component analysis revealed a close relationship between the volatile content of bulk cocoa samples dried by the OD and SD techniques, whereas slight volatile modifications were perceived among fine-flavor samples dried using the three different techniques under study. Overall, the results provide the basis for the potential application of the simplest inexpensive SBPD technique in order to accelerate the drying process of sun drying and produce cocoa with similar (fine-flavor cocoa) or improved (bulk cocoa) aromatic quality to that formed using the traditional SD or the small-scale OD.

Sensitive SARS-CoV-2 detection in wastewaters using a carbon nanodot-amplified electrochemiluminescence immunosensor.

Given the great utility that having fast, efficient and cost-effective methods for the detection of SARS-CoV-2 in wastewater can have in controlling the pandemic caused by this virus, the development of new dependable and specific SARS-CoV-2 coronavirus sensing devices to be applied to wastewater is essential to promote public health interventions. Therefore, herein we propose a new method to detect SARS-CoV-2 in wastewater based on a carbon nanodots-amplified electrochemiluminescence immunosensor for the determination of the SARS-CoV-2 Spike S1 protein. For the construction of the immunosensor, N-rich carbon nanodots have been synthetized with a double function: to contribute as amplifiers of the electrochemiluminescent signal in presence of [Ru(bpy)3]2+ and as antibody supports by providing functional groups capable of covalently interacting with the SARS-CoV-2 Spike S1 antibody. The proposed ECL immunosensor has demonstrated a high specificity in presence of other virus-related proteins and responded linearly to SARS-CoV-2 Spike S1 concentration over a wide range with a limit of detection of 1.2 pg/mL. The immunosensor has an excellent stability and achieved the detection of SARS-CoV-2 Spike S1 in river and urban wastewater, which supplies a feasible and reliable sensing platform for early virus detection and therefore to protect the population. The detection of SARS-CoV-2 Spike S1 in urban wastewater can be used as a tool to measure the circulation of the virus in the population and to detect a possible resurgence of COVID-19.

Fluorescent enzymatic assay for direct total polyphenol determination in food-related samples.

A direct and simple fluorescent assay for the total polyphenol determination based on the bioconjugate formed between the laccase enzyme (TvL from Trametes versicolor) and carbon nanodots (CD) is developed. One of the most used reactions for the determination of phenols is based on the enzymatic reaction of their oxidation to quinones. In this work, CD has been biofunctionalized with TvL (TvL-CD) and employed as a fluorescent label to follow the enzymatic reaction. The bioconjugate was formed and characterized by spectroscopy and microscopy. The optimal TvL-CD ratio was established. The reaction between the bioconjugate and a phenolic compound such as gallic acid (GA) was followed by monitoring the fluorescence bioconjugate decrease due to the quenching effect of the quinones generated in the enzymatic reaction. These studies confirm that bioconjugation does not inhibit the enzymatic activity and the fluorescence decrease during the enzymatic reaction is mainly due to an electron transfer processes. Based on these results, a new method for the quantitative determination of polyphenols measured as GA concentration is developed. The detection and quantification limit was found to be 7.4 and 25 µM, respectively. Subsequently, the method has been applied to the direct determination of GA in wine, juice, and rice leaf extracts.

Engineering Tropism of Pseudomonas putida toward Target Surfaces through Ectopic Display of Recombinant Nanobodies.

Gram-negative bacteria are endowed with complex outer membrane (OM) structures that allow them to both interact with other organisms and attach to different physical structures. However, the design of reliable bacterial coatings of solid surfaces is still a considerable challenge. In this work, we report that ectopic expression of a fibrinogen-specific nanobody on the envelope of Pseudomonas putida cells enables controllable formation of a bacterial monolayer strongly bound to an antigen-coated support. To this end, either the wild type or a surface-naked derivative of P. putida was engineered to express a hybrid between the ß-barrel of an intimin-type autotransporter inserted in the outer membrane and a nanobody (VHH) moiety that targets fibrinogen as its cognate interaction partner. The functionality of the thereby presented VHH and the strength of the resulting cell attachment to a solid surface covered with the cognate antigen were tested and parametrized with Quartz Crystal Microbalance technology. The results not only demonstrated the value of using bacteria with reduced OM complexity for efficient display of artificial adhesins, but also the potential of this approach to engineer specific bacterial coverings of predetermined target surfaces.

Antioxidant Activity and Bio-Accessibility of Polyphenols in Black Carrot (Daucus carota L. ssp. sativus var. atrorubens Alef.) and Two Derived Products during Simulated Gastrointestinal Digestion and Colonic Fermentation.

Black carrot has been attracting increasing thanks to its high bioactive compound content. This study presents the polyphenol bio-accessibility of black carrot and two derived products (black carrot snack (BC snack) and black carrot seasoning (BC seasoning)) after in vitro gastrointestinal digestion and colonic fermentation. Additionally, antioxidant activity was measured by 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt (ABTS), 1,1-diphenyl-2-picryl-hydrazyl (DPPH) and oxygen radical absorbance capacity (ORAC) assays. Nine flavonoids and eight anthocyanins were determined by ultra high-performance liquid chromatography high resolution mass spectrometry (UHPLC-HRMS) analysis, the predominant compounds being the hydroxycinnamic acids 3-O-feruloylquinic acid, 4-O-feruloylquinic acid and chlorogenic acid. The BC snack (108 µmol/g DW) presented the highest total polyphenol content, followed by BC seasoning (53 µmol/g DW) and black carrot (11.4 µmol/g DW). The main polyphenols still bio-accessible after in vitro digestion were the hydroxycinnamic acids, with mean recovery rates of 113 % for black carrot, 69% for BC snack and 81% for BC seasoning. The incubation of black carrot and its derived products with human faecal bacterial resulted in the complete degradation of anthocyanins and in the formation of mainly 3-(4'-hydroxyphenyl)propanoic acid as the major catabolic event. In conclusion, our results suggest that the black carrot matrix impacts significantly affects the bio-accessibility of polyphenols and, therefore, their potential health benefits.

Toxocariasis and Toxocara vaccine: a review / Toxocariasis y vacunación para Toxocara: una revisión sistemática / Toxocaríase e vacina para controle de Toxocara: uma revisão

Abstract Based on prevalence and impact on public health, toxocariasis is an underestimated zoonosis in developing and developed countries. The transmission of Toxocara spp. involves pets, stray dogs and cats (Canis familiaris and Felis catus, respectively), which spread the parasite's eggs in their feces to the environment. One of the main risk factors for the infection and development of human toxocariasis, is to cohabit with puppies and kittens. For a long time, the preventive strategy for this parasitic infection has been the regular use of antiparasitic drugs to reduce parasite burden in the short term. A long lasting immunological protection can be achieved with vaccination, however, a vaccine is not yet available. Therefore, it is fundamental to know and to understand the state of the art of vaccine development for effective control of this zoonosis. This paper reviews the experimental studies focused on vaccine development for toxocariasis control, and special attention is given to relevant epidemiological studies on the importance of dogs in human toxocariasis.

Resumen Según la prevalencia y el impacto en la salud pública, la toxocariasis es una zoonosis subestimada en los países en desarrollo y desarrollados. La transmisión de Toxocara spp. involucra animales de compañía caninos y felinos, como también perros y gatos sin hogar (Canis familiaris y Felis catus, respectivamente), que diseminan los huevos del parásito en sus heces al medio ambiente. Uno de los principales factores de riesgo para la infección y el desarrollo de la toxocariasis humana es convivir con cachorros felinos y caninos. Durante mucho tiempo, la estrategia preventiva para esta infección parasitaria ha sido el uso regular de medicamentos antiparasitarios para reducir la carga parasitaria a corto plazo. Se puede lograr una protección inmunológica duradera con la vacunación, sin embargo, todavía no se dispone de una vacuna. Por lo tanto, es fundamental conocer y comprender el estado del arte del desarrollo de vacunas para el control efectivo de esta zoonosis. Este artículo revisa los estudios experimentales centrados en el desarrollo de vacunas para el control de la toxocariasis, y se presta especial atención a los estudios epidemiológicos relevantes sobre la importancia de los caninos domésticos en la toxocariasis humana.

Resumo Com base na prevalência e no impacto na saúde pública, a toxocaríase é uma zoonose subestimada nos países em desenvolvimento e desenvolvidos. A transmissão de Toxocara spp. envolve animais cães e gatos de estimação e vadios (Canis familiaris e Felis catus, respectivamente), que espalham os ovos do parasita nas fezes para o meio ambiente. Um dos principais fatores de risco para a infecção e desenvolvimento da toxocaríase humana é coabitar com filhotes de cachorros e gatos. Por um longo tempo, a estratégia preventiva para essa infecção parasitária tem sido o uso regular de medicamentos antiparasitários para reduzir a carga parasitária a curto prazo. Uma proteção imunológica duradoura pode ser alcançada com a vacinação, no entanto, uma vacina ainda não está disponível. Portanto, é fundamental conhecer e entender o estado da arte do desenvolvimento de vacinas para o controle efetivo dessa zoonose. Este artigo revisa os estudos experimentais focados no desenvolvimento de vacinas para o controle da toxocaríase, e atenção especial é dada a estudos epidemiológicos relevantes sobre a importância dos cães na toxocaríase humana.

Enhanced Performance of Reagent-Less Carbon Nanodots Based Enzyme Electrochemical Biosensors.

This work reports on the advantages of using carbon nanodots (CNDs) in the development of reagent-less oxidoreductase-based biosensors. Biosensor responses are based on the detection of H2O2, generated in the enzymatic reaction, at 0.4 V. A simple and fast method, consisting of direct adsorption of the bioconjugate, formed by mixing lactate oxidase, glucose oxidase, or uricase with CNDs, is employed to develop the nanostructured biosensors. Peripherical amide groups enriched CNDs are prepared from ethyleneglycol bis-(2-aminoethyl ether)-N,N,N',N'-tetraacetic acid and tris(hydroxymethyl)aminomethane, and used as precursors. The bioconjugate formed between lactate oxidase and CNDs was chosen as a case study to determine the analytical parameters of the resulting L-lactate biosensor. A linear concentration range of 3.0 to 500 µM, a sensitivity of 4.98 × 10-3 µA·µM-1, and a detection limit of 0.9 µM were obtained for the L-lactate biosensing platform. The reproducibility of the biosensor was found to be 8.6%. The biosensor was applied to the L-lactate quantification in a commercial human serum sample. The standard addition method was employed. L-lactate concentration in the serum extract of 0.9 ± 0.3 mM (n = 3) was calculated. The result agrees well with the one obtained in 0.9 ± 0.2 mM, using a commercial spectrophotometric enzymatic kit.

Enhanced electrochemiluminescence by ZnO nanowires for taurine determination.

A novel electrochemiluminescence (ECL) sensor for the sensitive detection of taurine was developed. Taurine contains an aliphatic amine that gives it co-reactant properties. The ECL response of the taurine/[Ru(bpy)3]2+ system was analyzed on two different electrodes surfaces, screen-printed graphene and gold electrodes, before and after modification with ZnO nanowires (ZnO NWs). The ZnO NWs modified electrode yielded an enhanced ECL signal, allowing rapid detection of taurine at 5.5 × 10-6 mol L-1 detection limit. The ECL signal is stable and reproducible. The sensor has been applied to the determination of taurine in a commercial taurine supplement.

Encephalitis associated with human herpesvirus-7 infection in an immunocompetent adult.

BACKGROUND: Primary Human herpesvirus-7 (HHV-7) infection usually occurs during childhood and causes several clinical manifestations: mainly exanthem subitum (roseola infantum), followed by a lifelong latent state with possible reactivation in case of immunodeficiency. Nevertheless, some considerably different approaches exist regarding the natural history of HHV-7 and the possible consequences of HHV-7 infection in immunocompetent adults. In particular, little is known about its pathogenic role in central nervous system (CNS) disease in nonimmunosuppressed adults. Specifically, in case of encephalitis, it is important to distinguish between infectious encephalitis and postinfectious encephalomyelitis for the management of patients CASE PRESENTATION: We describe here a case of encephalitis associated to human herpesvirus-7 with associated polymyeloradiculopathy in an immunocompetent patient which may contribute to the delineation of the approach to a patient profile with a similar clinical presentation and evolution to those presented in the literature. CONCLUSIONS: This case may alert clinicians to consider this specific etiology in the differential diagnosis of encephalopathy in patients with suspected infectious encephalitis who do not respond to acyclovir or in patients who develop acute polymyeloradiculopathy, considering that HHV-7 may be a pathological factor and that a timely diagnosis is crucial for the early administration of specific treatment.

Reagent-Less and Robust Biosensor for Direct Determination of Lactate in Food Samples.

Lactic acid is a relevant analyte in the food industry, since it affects the flavor, freshness, and storage quality of several products, such as milk and dairy products, juices, or wines. It is the product of lactose or malo-lactic fermentation. In this work, we developed a lactate biosensor based on the immobilization of lactate oxidase (LOx) onto N,N'-Bis(3,4-dihydroxybenzylidene) -1,2-diaminobenzene Schiff base tetradentate ligand-modified gold nanoparticles (3,4DHS-AuNPs) deposited onto screen-printed carbon electrodes, which exhibit a potent electrocatalytic effect towards hydrogen peroxide oxidation/reduction. 3,4DHS-AuNPs were synthesized within a unique reaction step, in which 3,4DHS acts as reducing/capping/modifier agent for the generation of stable colloidal suspensions of Schiff base ligand-AuNPs assemblies of controlled size. The ligand-in addition to its reduction action-provides a robust coating to gold nanoparticles and a catalytic function. Lactate oxidase (LOx) catalyzes the conversion of l-lactate to pyruvate in the presence of oxygen, producing hydrogen peroxide, which is catalytically oxidized at 3,4DHS-AuNPs modified screen-printed carbon electrodes at +0.2 V. The measured electrocatalytic current is directly proportional to the concentration of peroxide, which is related to the amount of lactate present in the sample. The developed biosensor shows a detection limit of 2.6 µM lactate and a sensitivity of 5.1 ± 0.1 µA·mM-1. The utility of the device has been demonstrated by the determination of the lactate content in different matrixes (white wine, beer, and yogurt). The obtained results compare well to those obtained using a standard enzymatic-spectrophotometric assay kit.

Análisis retrospectivo de los proyectos de ciencia, tecnología e innovación del subsector pecuario financiados por Colciencias, 1991-2010 / Retrospective Analysis of Science, Technology and Innovation Projects in the Livestock Subsector Financed by Colciencias, 1991-2010

Entre las herramientas que ofrece Colciencias para lograr sus objetivos como entidad rectora del Sistema Nacional de Ciencia, Tecnología e Innovación, se encuentran las convocatorias públicas. El objetivo del presente trabajo es identificar y analizar los proyectos financiados por Colciencias durante el periodo 1991-2010 en temáticas correspondientes al subsector pecuario. Para esto se empleó la base de datos de registro de proyectos de Colciencias, a fin de identificar los proyectos del subsector pecuario financiados desde 1991 hasta el 2010. De cada proyecto se identificó el área temática, la especie animal objeto del proyecto, el tipo de entidad ejecutora, el departamento de ejecución y el programa nacional responsable del seguimiento. Durante el periodo de interés, Colciencias financió 4839 proyectos, de los cuales 218 corresponden al subsector pecuario, siendo el 2009 el año con un mayor número de proyectos financiados (23) en este subsector. El área temática con un mayor número de proyectos financiados es acuicultura y pesca seguida de sanidad animal y sistemas de producción, con 86, 39 y 24 proyectos financiados, respectivamente. Las especies objeto del mayor número de proyectos financiados fueron las acuáticas (86 proyectos) y los bovinos (80 proyectos). Las entidades ejecutoras fueron en su mayoría universidades públicas, seguidas por institutos de investigación y CENI; los departamentos de ejecución fueron Bogotá, Antioquia y Cundinamarca con 29,55, 13,64 y 13,64 %, respectivamente. Finalmente, los programas nacionales que hicieron seguimiento a un mayor número de proyectos son agropecuario, mar y recursos hidrobiológicos y biotecnología...

Among the tools offered by Colciencias to achieve their goals as the governing body of theNational Science, Technology and Innovation System, are public calls. The aim of this studyis to identify and analyze projects funded by Colciencias during the 1991-2010 period ontopics related to the livestock subsector. For this purpose, Colciencias project registrationdatabase was used, in order to identify the livestock subsector projects funded from 1991to 2010. The subject area, species targeted by the project, the type of implementing agency,the department of implementation and the national program responsible for monitoring theproject were identified for each project. During the period of interest, Colciencias financed4839 projects, 218 of which correspond to the livestock subsector, where 2009 was the year with the largest number of financed projects (23) in that subsector. The subject areas withthe largest number of projects financed are aquaculture and fisheries, followed by animalhealth and production systems, with 86, 39 and 24 financed projects, respectively. Targetspecies with the largest number of financed projects were water species (86 projects) andbovines (80 projects). The project executing agencies were mostly public universities, followedby research institutes and CENI; departments of execution were Bogotá, Antioquiaand Cundinamarca with 29.55, 13.64 and 13.64%, respectively. Finally, the national programsthat followed up a greater number of projects are agricultural, sea and aquatic resourcesand biotechnology...

Entre as ferramentas que oferece Colciencias para atingir seus objetivos como entidade reitorado Sistema Nacional de Ciência, Tecnologia e Inovação, encontram-se as convocatóriaspúblicas. O objetivo do presente trabalho é identificar e analisar os projetos financiados porColciencias durante o período 1991-2010 em temáticas correspondentes ao subsetor pecuário.Para isto, foi utilizado o banco de dados de registro de projetos de Colciencias, como objetivo de identificar os projetos do subsetor pecuário financiados desde 1991 até 2010.Para cada projeto identificou-se a área temática, a espécie animal objeto do projeto, o tipode entidade executora, o departamento de execução e o programa nacional responsável peloacompanhamento do projeto. Durante o período de interesse, Colciencias financiou 4839projetos, dos quais 218 correspondem ao subsetor pecuário, sendo 2009 o ano com maiornúmero de projetos financiados (23) neste subsetor. A área temática com o maior númerode projetos financiados é aquicultura e pesca seguida pela sanidade animal e sistemas de produção,com 86, 39 e 24 projetos financiados, respectivamente. As espécies objeto do maiornúmero de projetos financiados foram as aquáticas (86 projetos) e os bovinos (80 projetos).As entidades executoras dos projetos foram em sua maioria universidades públicas, seguidaspor institutos de pesquisa e CENI; os departamentos de execução foram Bogotá, Antioquiae Cundinamarca com 29,55%, 13,64% e 13,64%, respectivamente. Finalmente, os programasnacionais que fizeram acompanhamento a um maior número de projetos são agropecuário,mar e recursos hidrobiológicos e biotecnologia...

Plan nacional de investigación forestal y plan estratégico del programa nacional de ciencia y tecnologías agropecuarias (Colciencias) / National forestry research plan and strategic plan of the agricultural science and technology program (Colciencias)

El presente artículo divulga a la comunidad científica las prioridades de investigación nacional de las áreas agropecuaria y forestal, con base en las líneas de investigación identificadas por el Programa de Ciencia y Tecnologías Agropecuarias, para los planes estratégicos 2010-2019 de Colciencias. El plan estratégico agropecuario ha establecido que las prioridades de investigación para Colombia son gestión de la cadena de suministros, nutrición, pobreza rural, calidad e inocuidad, lenta transformación productiva: costo de oportunidad e investigación insuficiente y descontextualizada; cada una de las problemáticas anteriormente mencionadas es descrita brevemente en el documento. En cuanto al Plan Nacional de Investigación Forestal, se han propuesto las siguientes tres líneas temáticas: fortalecer un programa nacional de mejoramiento genético de especies forestales que contribuyan a la productividad y al incremento de los servicios ambientales; identificar y caracterizar áreas, especies y productos potenciales para programas de reforestación; e identificar especies, arreglos y densidades que optimicen los bienes obtenibles de una plantación forestal y sus servicios ambientales, para las condiciones sociales y agroecológicas prioritarias del país. Se espera divulgar la información de los dos planes estratégicos en el ámbito nacional, durante el primer semestre del año 2011, a fin de que el Departamento Administrativo de Ciencia, Tecnología e Innovación (Colciencias), apoye los proyectos de investigación que cumplan con las expectativas de las prioridades identificadas.

This paper aims to share the national research priorities in agriculture and forestry areas with the scientific community, based on the lines of research identified by the Agricultural Science and Technology Program for the 2010-2019 Strategic Plans by Colciencias. The Strategic Agriculture Plan has determined that the research priorities are Colombia to manage the supply chain, nutrition, rural poverty, quality and innocuousness, as well as the slow production transformation: cost of opportunity and insufficient, decontextualized research. Each of the aforementioned problems is briefly described in the document. As far as the National Plan of Forestry Research is concerned, the following three main topics were suggested: to strengthen a national genetic improvement of tree species that contribute to productivity and the increase of environmental services; to identify and characterize areas, species and potential products for reforestation programs; and to identify species, arrangements and densities that optimize the goods that may be obtained from a forest plantation and its environmental services for the top priority social and agro-ecological conditions of the country. The information regarding the two National Strategic Plans is expected to be disclosed during the first semester of 2011, so that the Administrative Department of Science, Technology and Innovation (Colciencias) can support the research projects that meet the expectations of the identified priorities.

Interactions of Schiff-base ligands with gold nanoparticles: structural, optical and electrocatalytic studies.

A study on optical and electrochemical properties resulting upon interaction of Schiff base ligands with gold nanoparticles is presented. The measurements of the optical absorption and fluorescence properties have provided important information about structure-properties dependence. We show that in function of the isomer structure and its attachment orientation with respect to the metal nanoparticle, their optical properties can be modulated. Nanoparticle assemblies mediated by 3,4-DHS were also obtained based on a control of the interparticle interactions and their electrocatalytic activity toward NADH oxidation was investigated.

Aspectos moleculares relevantes de las proteínas de patogenicidad de Leptospira sp / Relevant molecular aspects of leptospiral pathogenicity proteins

La leptospirosis es una zoonosis ampliamente difundida, que afecta cerca de 160 especies salvajes y domésticas, las cuales se constituyen en reservorios latentes y son fuente primaria de contaminación para el hombre. Esta zoonosis es causada por la Leptospira sp., bacteria Gram negativa que tiene la capacidad de sobrevivir en la orina. Esto, sumado a la presencia de charcos, lagunas y aguas estancadas que se contaminan fácilmente y se convierten en un foco permanente de transmisión, hace de la leptospirosis una enfermedad de impacto en salud pública. La leptospirosis se diagnóstica utilizando la técnica convencional por icroglutinación (MAT). Sin embargo, no existen criterios unificados respecto a los títulos considerados como positivos, originando un número relevante de falsos positivos y negativos. Por consiguiente, es necesario evaluar nuevas estrategias diagnósticas altamente sensibles y específicas para lograr un diagnóstico preciso y confiable. Con este artículo se busca hacer una revisión sobre el papel de las proteínas asociadas con patogenicidad y la utilidad de estudios de expresión génica, en la implementación de nuevas técnicas diagnósticas que permitan postular marcadores moleculares de infección...

[Review of the actions in prevention of infections in total arthroplasty of hip]. / Revisión de las acciones para prevenir infecciones en la artroplastía total de cadera.

The prophylactic use of antibiotics when a hip replacement procedure is performed has been subject of intense debate. Prevention of such an infection is complex, with many unresolved issues that require considerable investigation. The attentive application of reasonable principles of infection control with the goals of optimization of the wound environment, augmentation of the host response, and minimization of bacterial contamination in the preoperative, and postoperative time-period is essential to that overall reduction of the frequency of infection. We present the antibiotic prophylaxis used in the American British Cowdray Medical Center between January 1999 to July 2003. after hip arthroplasty in 532 patients. The main antibiotic used was cefalotin in 53.76% of the cases, but only in 3.2 % a one day prophylaxis treatment recommended in the literature is used, with septic loosening of 3.9%.

Comprehensive study of interactions between DNA and new electroactive Schiff base ligands. Application to the detection of singly mismatched Helicobacter pylori sequences.

N,N'-Bis(3,4-dihydroxybenzylidene)-1,2-diaminobenzene (3,4-DHS) and N,N'-bis(2,5-dihydroxybenzylidene)-1,2-diaminobenzene (2,5-DHS) have been used as electrochemical probes in DNA sensing. These ligands, containing ortho and para quinone functional groups, respectively, as well as planar aromatic domains, are capable of binding to double stranded DNA (ds-DNA) more efficiently than to single stranded DNA (ss-DNA). Emphasis has been placed on the elucidation of the nature of the interaction by combining spectroscopic and electrochemical techniques. From spectrophotometric titration experiments, the binding constants of 3,4-DHS and 2,5-DHS with ds-DNA were found to be (9.0+/-0.3) x 10(3) and (3.3+/-0.2) x 10(3)M(-1), respectively. These values are consistent with a binding mode dominated by interactions with the minor groove of ds-DNA. The electroactivity of the quinone moiety in 3,4-DHS bound to DNA could be employed as an electrochemical indicator to detect hybridization events in DNA biosensors. These biosensors have been constructed by immobilization of a thiolated capture probe sequence from Helicobacter pylori onto gold electrodes. After hybridization with the complementary target sequence, 3,4-DHS was accumulated within the double stranded DNA layer. Electrochemical detection was performed by differential pulse voltammetry over the potential range where the quinone moiety is redox active. Using this approach, complementary target sequences of H. pylori can be quantified over the range of 8.9-22.2 microM with a detection limit of 8.3+/-0.4 microM and a linear correlation coefficient of 0.989. In addition this approach is capable of detecting hybridization of complementary sequences containing a single mismatch.