MNAzymes and gold nanoparticles as isothermal signal amplification strategy for visual detection of miRNA.

MicroRNAs (miRNAs) represent a class of small noncoding RNAs that are considered a novel emerging class of disease biomarkers in a variety of afflictions. Sensitive detection of miRNA is typically achieved using hybridization-based methods coupled with genetic amplification techniques. Although their sensitivity has improved, amplification techniques often present erroneous results due to their complexity. In addition, the use of these techniques is usually linked to the application of protein enzymes, the activity of which is dependent on the temperature and pH of the medium. To address these drawbacks, an alternative genetic enzyme for the highly sensitive detection of miRNAs is proposed in this work. Multicomponent nucleic acid enzymes (MNAzymes), coupled with the use of DNA-functionalized gold nanoparticles (AuNPs), were used in this study to develop an isothermal signal amplification strategy for visual genetic detection. miR146a, a biomarker of bovine mastitis present in milk, was selected as a model analyte. The developed methodology is easily carried out in 80 min at 50 °C, generating a low visual limit of detection of 250 pM based on the observation of a color change. The methodology was successfully applied to the detection of miR146a in raw cow milk samples.

A study of transfer of information in animal collectives using deep learning tools.

We studied how the interactions among animals in a collective allow for the transfer of information. We performed laboratory experiments to study how zebrafish in a collective follow a subset of trained animals that move towards a light when it turns on because they expect food at that location. We built some deep learning tools to distinguish from video which are the trained and the naïve animals and to detect when each animal reacts to the light turning on. These tools gave us the data to build a model of interactions that we designed to have a balance between transparency and accuracy. The model finds a low-dimensional function that describes how a naïve animal weights neighbours depending on focal and neighbour variables. According to this low-dimensional function, neighbour speed plays an important role in the interactions. Specifically, a naïve animal weights more a neighbour in front than to the sides or behind, and more so the faster the neighbour is moving; and if the neighbour moves fast enough, the differences coming from the neighbour's relative position largely disappear. From the lens of decision-making, neighbour speed acts as confidence measure about where to go. This article is part of a discussion meeting issue 'Collective behaviour through time'.

An Affordable NIR Spectroscopic System for Fraud Detection in Olive Oil.

Adulterations of olive oil are performed by adding seed oils to this high-quality product, which are cheaper than olive oils. Food safety controls have been established by the European Union to avoid these episodes. Most of these methodologies require expensive equipment, time-consuming procedures, and expert personnel to execute. Near-infrared spectroscopy (NIRS) technology has many applications in the food processing industry. It analyzes food safety and quality parameters along the food chain. Using principal component analysis (PCA), the differences and similarities between olive oil and seed oils (sesame, sunflower, and flax oil) have been evaluated. To quantify the percentage of adulterated seed oil in olive oils, partial least squares (PLS) have been employed. A total of 96 samples of olive oil adulterated with seed oils were prepared. These samples were used to build a spectra library covering various mixtures containing seed oils and olive oil contents. Eighteen chemometric models were developed by combining the first and second derivatives with Standard Normal Variable (SNV) for scatter correction to classify and quantify seed oil adulteration and percentage. The results obtained for all seed oils show excellent coefficients of determination for calibration higher than 0.80. Because the instrumental aspects are not generally sufficiently addressed in the articles, we include a specific section on some key aspects of developing a high-performance and cost-effective NIR spectroscopy solution for fraud detection in olive oil. First, spectroscopy architectures are introduced, especially the Texas Instruments Digital Light Processing (DLP) technology for spectroscopy that has been used in this work. These results demonstrate that the portable prototype can be used as an effective tool to detect food fraud in liquid samples.

Inorganic nanoparticles coupled to nucleic acid enzymes as analytical signal amplification tools.

Nucleic acid enzymes (NAzymes) are a class of nucleic acid molecules with catalytic activity, which can be modulated by the presence of different species such as metal ions, genetic biomarkers, small molecules or proteins, among others. NAzymes offer several important advantages for development of novel bioanalytical strategies, resulting from their functionality as specific recognition elements and as amplified analytical signal generators, making them ideal candidates for developing highly specific bioanalytical strategies for the detection of a wide variety of targets. When coupled with the exceptional features of inorganic nanoparticles (NPs), the sensitivity of the assays can be significantly improved, allowing the detection of targets using many different detection techniques including visual readout, spectrophotometry, fluorimetry, electrochemiluminescence, voltammetry, and single-particle inductively coupled plasma-mass spectrometry. Here we provide an overview of the fundamentals of novel strategies developed to achieve analytical signal amplification based on the use of NAzymes coupled with inorganic NPs. Some representative examples of such strategies for the highly sensitive detection of different targets will be presented, including metal ions, proteins, DNA- or RNA-based biomarkers, and small molecules or microorganisms. Furthermore, future prospective challenges will be discussed.

Near-Infrared Sensors for Onsite and Noninvasive Quantification of Macronutrients in Breast Milk.

Breast milk is an optimal food that covers all the nutritional needs of the newborn. It is a dynamic fluid whose composition varies with lactation period. The neonatal units of hospitals have human milk banks, a service that analyzes, stores, and distributes donated human milk. This milk is used to feed premature infants (born before 32 weeks of gestation or weighing less than 1500 g) whose mothers, for some reason, cannot feed them with their own milk. Here, we aimed to develop near-infrared spectroscopy (NIRS) measures for the analysis of breast milk. For this purpose, we used a portable NIRS instrument scanning in the range of 1396-2396 nm to collect the spectra of milk samples. Then, different chemometrics were calculated to develop 18 calibration models with and without using derivatives and the standard normal variate. Once the calibration models were developed, the best treatments were selected according to the correlation coefficients (r2) and prediction errors (SECVs). The best results for the assayed macronutrients were obtained when no pre-treatment was applied to the NIR spectra of fat (r2 = 0.841, SECV = 0.51), raw protein (r2 = 0.512, SECV = 0.21), and carbohydrates (r2 = 0.741, SECV = 1.35). SNV plus the first derivative was applied to obtain satisfactory results for energy (r2 = 0.830, SECV = 9.60) quantification. The interpretation of the obtained results showed the richness of the NIRS spectra; moreover, the presence of specific bands for fat provided excellent statistics in quantitative models. These results demonstrated the ability of portable NIRS sensors in a methodology developed for the quality control of macronutrients in breast milk.

Visual detection of microRNA146a by using RNA-functionalized gold nanoparticles.

Gold nanoparticles of different sizes have been synthesized and surface-functionalized with selected RNA probes in order to develop a rapid, low-cost and sensitive method for detection of microRNA146a (miR146a). The strategy is based on the change of colour that can be observed visually after aggregation of the RNA modified-gold nanoparticles (AuNPs) in presence of miR146a. Experimental conditions have been carefully selected in order to obtain a good sensitivity that allows to perform visual detection of microRNA at the nM level, achieving a detection limit of 5 nM. Good repeatability and selectivity versus other sequences that only differ from miR146a in 3 bases was achieved. miR146a has been described as one of the main microRNA involved in the immune response of bovine mastitis, being expressed in tissue, blood and milk samples. The method was successfully applied to the detection of miR146a in raw cow milk samples. The present scheme constitutes a rapid and low-cost alternative to perform highly sensitive detection of microRNA without the need of instrumentation and amplification steps for the early detection of bovine mastitis in the agrofood industry. Graphical abstract Schematic representation of the assay based on aggregation of RNA-modified gold nanoparticles (blue) in presence of microRNA146a generating a dark blue spot onto a solid support, versus a pink spot observed in absence of miR146a due to dispersed gold nanoparticles (red).

An Affordable Method for Evaluation of Ataxic Disorders Based on Electrooculography.

Ataxias are a group of neurodegenerative disorders characterized by cerebellar dysfunction that cause irregularities in the rate, rhythm, amplitude, and force of voluntary movements. The electrooculogram (EOG) may provide clues about ataxic disorders because most of these patients have difficulty with visual tracking and fixing their gaze. Using electrodes, EOG records the biopotentials generated by eye movements. In this paper, three surface electrodes are placed around the eye socket, and the biopotentials generated by eye movements are acquired using a commercial bioamplifier device. Next, the signals are sent to the computer to be digitally processed to extract the rate of saccades as well as the delay and deviation of the gaze in response to a stimulus. These features are analysed in a novel software application designed to help physicians in evaluating ataxia. After applying several tests to both healthy and ataxia-affected patients, differences in EOG results were found. The evaluation of the reliability of the designed software application is made according to three metrics: sensitivity, specificity, and accuracy. The results indicate the proposed system's viability as an affordable method for evaluation of ataxic disorders.

Deep attention networks reveal the rules of collective motion in zebrafish.

A variety of simple models has been proposed to understand the collective motion of animals. These models can be insightful but may lack important elements necessary to predict the motion of each individual in the collective. Adding more detail increases predictability but can make models too complex to be insightful. Here we report that deep attention networks can obtain a model of collective behavior that is simultaneously predictive and insightful thanks to an organization in modules. When using simulated trajectories, the model recovers the ground-truth interaction rule used to generate them, as well as the number of interacting neighbours. For experimental trajectories of large groups of 60-100 zebrafish, Danio rerio, the model obtains that interactions between pairs can approximately be described as repulsive, attractive or as alignment, but only when moving slowly. At high velocities, interactions correspond only to alignment or alignment mixed with repulsion at close distances. The model also shows that each zebrafish decides where to move by aggregating information from the group as a weighted average over neighbours. Weights are higher for neighbours that are close, in a collision path or moving faster in frontal and lateral locations. The network also extracts that the number of interacting individuals is dynamical and typically in the range 8-22, with 1-10 more important ones. Our results suggest that each animal decides by dynamically selecting information from the collective.

idtracker.ai: tracking all individuals in small or large collectives of unmarked animals.

Understanding of animal collectives is limited by the ability to track each individual. We describe an algorithm and software that extract all trajectories from video, with high identification accuracy for collectives of up to 100 individuals. idtracker.ai uses two convolutional networks: one that detects when animals touch or cross and another for animal identification. The tool is trained with a protocol that adapts to video conditions and tracking difficulty.

Functionalized phosphorescent nanoparticles in (bio)chemical sensing and imaging - A review.

Inorganic nanoparticles are a fascinating class of materials which promise great potential in numerous fields, including optical (bio)sensing. Many different kinds of such nanoparticles have been widely used for fluorescent sensing and imaging due to the different merits of fluorescent nanoparticles compared to molecular fluorophores. Progress made in the rational design of nanomaterials also allowed the synthesis of hybrid phosphorescent nanoparticles, that finds growing applications in sensing due to the combination of the interesting size- and shape-dependent properties of nanomaterials with a phosphorescence-type emission. In this review, we intend to highlight some of progress made in this active research area and update the database of various phosphorescent nanoparticles-based sensors on the basis of different sensing targets of interest in environmental, industrial and biomedical areas. Following an introduction and a discussion of merits of the synergy between nanomaterials and phosphorescence detection as compared to molecular luminophores the article assesses the kinds and specific features of nanomaterials often used in phosphorescence sensing. Specific examples on the use of phosphorescence nanoparticles in chemical sensing and bioimaging are given next. A final section intends to provide an overview of the prospects of such type of nanomaterials in the design of future devices for analytical chemistry.

Development of a biosensor protein bullet as a fluorescent method for fast detection of Escherichia coli in drinking water.

Drinking water can be exposed to different biological contaminants from the source, through the pipelines, until reaching the final consumer or industry. Some of these are pathogenic bacteria and viruses which may cause important gastrointestinal or systemic diseases. The microbiological quality of drinking water relies mainly in monitoring three indicator bacteria of faecal origin, Escherichia coli, Enterococcus faecalis and Clostridium perfringens, which serve as early sentinels of potential health hazards for the population. Here we describe the analysis of three chimeric fluorescent protein bullets as biosensor candidates for fast detection of E. coli in drinking water. Two of the chimeric proteins (based on GFP-hadrurin and GFP-pb5 chimera proteins) failed with respect to specificity and/or sensitivity, but the GFP-colS4 chimera protein was able to carry out specific detection of E. coli in drinking water samples in a procedure encompassing about 8 min for final result and this biosensor protein was able to detect in a linear way between 20 and 103 CFU of this bacterium. Below 20 CFU, the system cannot differentiate presence or absence of the target bacterium. The fluorescence in this biosensor system is provided by the GFP subunit of the chimeric protein, which, in the case of the better performing sensor bullet, GFP-colS4 chimera, is covalently bound to a flexible peptide bridge and to a bacteriocin binding specifically to E. coli cells. Once bound to the target bacteria, the excitation step with 395 nm LED light causes emission of fluorescence from the GFP domain, which is amplified in a photomultiplier tube, and finally this signal is converted into an output voltage which can be associated with a CFU value and these data distributed along mobile phone networks, for example. This method, and the portable fluorimeter which has been developed for it, may contribute to reduce the analysis time for detecting E. coli presence in drinking water.

Development of a Computer Writing System Based on EOG.

The development of a novel computer writing system based on eye movements is introduced herein. A system of these characteristics requires the consideration of three subsystems: (1) A hardware device for the acquisition and transmission of the signals generated by eye movement to the computer; (2) A software application that allows, among other functions, data processing in order to minimize noise and classify signals; and (3) A graphical interface that allows the user to write text easily on the computer screen using eye movements only. This work analyzes these three subsystems and proposes innovative and low cost solutions for each one of them. This computer writing system was tested with 20 users and its efficiency was compared to a traditional virtual keyboard. The results have shown an important reduction in the time spent on writing, which can be very useful, especially for people with severe motor disorders.

Historia de la medicina del estado táchira (compendio) / History of medicine in the táchira state (compendium)

En el IV Congreso Venezolano de la Historia de la Medicina celebrado en 1984, se presentó la ponencia titulada "Historia de la Medicina en las Entidades Federales", el correlato correspondiente al Estado Táchira fue recopilado y publicado en 1993. Ese material me sirvió de sustento para la presentación en la Sociedad Venezolana de Historia de la Medicina, a manera de compendio de la Historia Médica del Táchira desde el descubrimiento hasta nuestros días. A pesar de la objetividad que debe poseer todo relato histórico, la narración siempre es más rica y precisa al referirse a los hechos reciente, porque existe la documentación determinada al respecto y la vivencia de los personajes. Los acontecimientos referidos en la época de la conquista y la colonia tienen la subjetividad de lo narrativo y la dificultad de investigar los documentos que pudieron preservarse en el tiempo. Espero que este relato logre satisfacer las expectativas de este grupo de médicos historiadores que se han ocupado de custodiar la memoria de la historia médica de Venezuela y que haya podido en este breve espacio presentar una semblanza de la evolución de la Medicina en el Estado Táchira(AU)

Cáncer avanzado que simula cáncer gástrico precoz: presentación de tres casos / Advanced gastric cancer simulating early gastric cancer: report of cases

El Cáncer Gástrico avanzado presenta características macroscópicas tradicionalmente definidas según la clasificación de Borrman establecida en 1926, no obstante algunos cánceres gástricos avanzados presentan aspectos macroscópicos similares al Cáncer Gástrico Precoz. Este tipo de lesiones han sido diagnósticadas como canceres precoces tanto por gastroenterólogos como por patológos. Presentamos tres casos de Cáncer Gástrico Avanzado que simulan Cáncer Gástrico Precoz. Los tres fueron lesiones ulceradas, dos de ellos se clasificaron como Cáncer Gástrico como Cáncer Gástrico Precoz Tipo III y el otro como Cáncer Gástrico Precoz Tipo III+IIc. En todos los casos se sospechó invasión hasta la submucosa. Estudios histológicos de los especímenes quirúrgicos revelaron el caracter avanzado de las lesiones

Leiomioblastoma gástrico: análisis histomorfológico e inmunológico de tres casos / Gastric leiomioblastoma: presentation of three cases

Se presentan tres casos de Leiomioblastoma gástrico diagnósticados en la Unidad de Patología del Centro de Control de Cáncer Gástrico "Dr. Luis E. Anderson" - San Cristóbal Estado Táchira Venezuela. Las lesiones se analizaron desde el punto de vista clínico patológico e inmunohistoquímico utilizando técnicas de Vimentina y Queratina. Esta neoplasia no es frecuente, pero interesante debido a que su comportamiento biológico no siempre se corresponde con la histología

Cáncer gastrico avanzado: centro de control de cáncer gastriintestinal San Cristobal, Estado Tachira / Gastric cancer advanced

El número de muertes debido a Cáncer Gástrico es alto en el Estado Táchira. En el Programa de Detección del Cáncer Gástrico en el Edo. Táchira, además de 80 Cánceres Precoces de estómago, se han diagnósticado 368 Cánceres Avanzados. De estos últimos fueron intervenidos 131 casos, siendo posible la recección en 123 (93.84%). La sobrevida de los pacientes que tienen más de 5 años de operados es de 16.12%. Se hace un análisis de la incidencia por sexo, edad, procedencia, síntomas digestivos, etc; como los tipos de intervenciones realizados y la histopatología de los tumores. Nuestro estudio nos permite concluir que han mejorado obstensiblemente la operabilidad, resecabilidad y sobrevida de los pacientes tratados por Cáncer Avanzado incluidos en nuestro Programa de Pesquisa. Se hace comparación de los resultados con un Informe de los casos tratados en nuestro Hospital Central antes de comenzar la pesquisa masiva

Cáncer gástrico precoz / Early gastric cancer

Se reporta la experiencia del tratamiento quirúrgico del cáncer gástrico precoz en el Estado Táchira, diagnosticados en el Programa de Pesquisa del Cáncer Gástrico de dicho Estado, desde su inicio en 1980. Se hacen las consideraciones generales sobre las pautas establecidas por la Sociedad Japonesa para la Investigación del Cáncer Gástrico. Entre diciembre 1980 y noviembre de 1986 han sido intervenidos 44 cánceres precoses de estómago, los resultados han sido óptimos, pues solo 1 paciente ha fallecido por tumor en el remanente gástrico. Y aunque solo muy pocos pacientes han sobrepasado el 5§ año de sobrevida, consideramos que, un elevado porcentaje de los casos tratados, están curados de su cáncer gástrico. Se hace comparación de este estudio con uno previo al establecimiento del Programa de Pesquisa