Mejoramiento de un método no comercial para la extracción de ADN de moscas de interés médico-legal

La obtención de ADN de moscas de interés médico-legal es de relevancia para una variedad de aplicaciones. Aunque existen métodos de extracción comerciales de ADN, su uso rutinario es limitado, en algunos escenarios. En este contexto, el uso de métodos no comerciales constituye una alternativa; sin embargo, su optimización es clave para mejorar el flujo de trabajo y los resultados. Este trabajo evaluó el impacto de variaciones a un método de precipitación salina sobre la concentración y la pureza del ADN recuperado. No se encontraron diferencias significativas en la concentración de ADN extraído entre los diferentes tiempos de incubación, probados durante la fase de extracción, mientras que el incremento en el volumen de etanol absoluto, en la fase de precipitación de ADN, mejoró significativamente la concentración de ADN obtenido. Las modificaciones propuestas reducen el tiempo de ejecución y la concentración de ADN obtenido comparado con el protocolo original.

Obtaining DNA from flies of medico-legal interest is relevant for a variety of applications. Although commercial extraction methods offer optimal DNA, their routine use is limited in some settings. In this context, the use of non-commercial methods constitutes an alternative in laboratories with limited resources however, its optimization is key to improving the workflow and the results. This work evaluated the impact of variations to a saline precipitation method on the concentration and purity of the recovered DNA. No significant differences were found in the concentration of extracted DNA between the different incubation times tested during the extraction phase. In contrast, the increased volume of absolute ethanol in the DNA precipitation phase significantly improved the concentration of DNA obtained. The proposed modifications reduce the runtime and DNA concentration obtained compared with the original protocol.

Storage and purification adaptations for the isolation of total RNA from the dura mater / Adaptações no armazenamento e purificação para o isolamento de RNA total da dura-máter

Abstract Background RNA extraction is a step that precedes several molecular techniques. The fibrous tissue, more specifically the dura mater, has several limitations in routine protocols, and lacks optimization protocols to overcome these problems. Objective To test stock reagents and purification kits, optimizing commercial kit protocols for RNA extraction from the dura mater. Methods Dura mater samples were obtained from eight Wistar rats and maintained in two different stabilizers. The samples were purified using four different protocols, and the RNA was evaluated for the yield and purity in NanoDrop 2000 (Thermo Scientific, Wilmington, DE, United States). Beta-actin gene was used for analyzing gene expression, since is one of the most used reference genes. Results The RNA preservation was similar in both stabilizers. The addition of an incubation step prior the purification protocols allowed better tissue digestion and RNA recovery. The RNA purified using the protocols membrane-based showed higher quality than liquid-liquid purification. This impact was observed in the 3-week evaluation using RT-qPCR. Conclusion Stabilizers are efficient for RNA preservation and membrane-based purification protocols are more suitable for RNA recovery from dura mater tissue, allowing the evaluation of gene expression in this type of tissue. Adaptations in the dura mater RNA extraction protocol differ from the pre-established protocols because it takes into account the peculiarity of fibrous tissue and low cellularity. In addition to providing a low-cost mechanism, based on techniques that are part of the laboratory routine, it is possible to improve the quality of the extracted material, ensuring greater efficiency in the use of subsequent techniques.

Resumo Antecedentes A extração de RNA é uma etapa que antecede várias técnicas moleculares. O tecido fibroso, mais especificamente a dura-máter, apresenta várias limitações nos protocolos de rotina e carece de protocolos de otimização para superar estes problemas. Objetivo Testar reagentes de estoque e kits de purificação, otimizando protocolos de kits comerciais para extração de RNA da dura-máter. Métodos Amostras de dura-máter foram obtidas de oito ratos Wistar e mantidas em dois estabilizadores diferentes. As amostras foram purificadas em quatro protocolos diferentes e o RNA foi avaliado quanto ao rendimento e pureza no NanoDrop 2000 (Thermo Scientific, Wilmington, DE, United States). O gene da beta-actina foi utilizado para analisar a expressão gênica, uma vez que é um dos genes de referência mais utilizados. Resultados A preservação do RNA foi semelhante em ambos os estabilizadores. A adição de uma etapa de incubação antes dos protocolos de purificação permitiu uma melhor digestão do tecido e recuperação de RNA. O RNA purificado pelos protocolos baseados em membrana apresentou qualidade superior ao da purificação líquido-líquido. Este impacto foi observado na avaliação de três semanas usando RT-qPCR. Conclusão Os estabilizadores são eficientes para preservação do RNA e os protocolos de purificação baseados em membrana são mais adequados para recuperação de RNA do tecido da dura-máter, permitindo a avaliação da expressão gênica neste tipo de tecido. As adaptações no protocolo de extração de RNA da dura-máter diferem dos protocolos preestabelecidos porque leva em consideração a peculiaridade do tecido fibroso e com baixa celularidade. Além de fornecer um mecanismo de baixo custo, baseado em técnicas que fazem parte da rotina laboratorial, é possível melhorar a qualidade do material extraído, garantindo maior eficácia no uso de técnicas subsequentes.

Uso de genomas de SARS-CoV -2 para la estimación del número reproductivo efectivo (Rt) en Perú durante marzo y abril del 2020

La comprensión de la COVID-19, provocada por el coronavirus de tipo 2 (SARS-CoV-2) causante de síndrome respiratorio agudo severo, utilizando un enfoque multidisciplinario, es esencial para mejorar la toma de decisiones basadas en evidencia. Se estimó el número reproductivo efectivo (Rt) en Perú a partir de 113 genomas completos generados por el Instituto Nacional de Salud (INS) del Perú almacenados en la base de datos pública GISAID. La tendencia mostrada por el Rt durante marzo y abril del 2020 fue similar a otras estimaciones epidemiológicas. El Rt disminuyó considerablemente durante la primera quincena de marzo, alcanzando su menor valor la semana posterior al inicio de la cuarentena, pero aumentó moderadamente desde la quincena de abril. Se discute las implicancias de las medidas tempranas tomadas para mitigar la transmisión. La vigilancia genómica será una herramienta necesaria para conocer la transmisión y evolución del virus, y complementará la información epidemiológica.

The understanding of COVID-19, caused by the SARS-CoV-2, is essential to improve evidence-based public health policies. The effective reproductive number (Rt) in Peru was estimated using information from 113 complete genomes sequenced by the Instituto Nacional de Salud del Perú (INS), available in the GISAID public database. The Rt trend during March and April of 2020 was found to be similar to results from other epidemiological reports. The Rt decreased during the first two weeks of March. Its lowest value was reported during the week after the quarantine began. The Rt increased moderately after the second week of April. The implication of early decisions taken to mitigate the transmission are discussed. Genomic surveillance will be necessary to understand the transmission and evolution of SARS-CoV-2 in Peru, and will complement the epidemiological information.

La biopsia líquida en el diagnóstico y monitoreo de pacientes oncológicos: Oportunidades y retos en Latinoamérica / Liquid biopsy in the diagnosis and monitoring of cancer patients: opportunities and challenges in Latin America

Resumen En los últimos años el estudio de los ácidos nucleicos circulantes ha tenido grandes avances en el campo de la oncología, lo que ha permitido avanzar de forma importante en las aplicaciones clínicas de la biopsia líquida en diferentes áreas como el pronóstico, la estadificación, la predicción de recurrencia, la selección y monitorización de tratamientos, entre otros. Lo anterior se debe en gran parte al desarrollo de nuevas y mejores tecnologías, algunas de las cuales incluso han sido autorizadas para el diagnóstico y seguimiento clínico de ciertos tipos de cáncer. No obstante, la utilización de la biopsia líquida como herramienta de apoyo clínico sigue siendo objeto de estudio. Debido a la importancia que ha cobrado este avance tecnológico a nivel mundial, se realizó una revisión de literatura con el fin de establecer el estado actual del uso de biopsia líquida en oncología, así como sus aplicaciones clínicas actuales, con un énfasis en Latinoamérica.

Abstract In recent years, the study of circulating nucleic acids has made great progress in the field of oncology, allowing for significant advances in clinical applications of liquid biopsy in diverse areas such as prognosis, staging, recurrence prediction, selection and monitoring of treatments, among others. This advance is largely due to the development of new and better technologies, some of which have even been validated for the diagnosis and clinical follow-up of certain types of cancer. However, the use of liquid biopsy as an additional tool in clinical oncology remains under study. Given the worldwide importance of this technological advance, a literature review was conducted to establish the current status of the use of liquid biopsy in oncology, as well as its current clinical applications, with a particular focus on Latin America.

Update on the Diagnosis of Sexually Transmitted Infections. / Actualización en el diagnóstico de las infecciones de transmisión sexual.

Sexually transmitted infections (STIs) are one of the most frequent and universal Public Health problems. Health professionals should be aware of the possibility of STIs due to their high morbidity and the presence of sequelae. The delay in the diagnosis is one of the factors that justifies the difficulty to infections control. Diagnostic tests allow the introduction of aetiological treatment and also lead to treating symptomatic and asymptomatic patients more effectively, as well as to interrupt the epidemiological transmission chain without delay. In this review we have made an update of the main existing diagnostic methods for the more important STIs.

Vacunas para SARS-CoV-2: diferentes estrategias de los desarrollos en curso / Vaccines for SARS-CoV-2: different strategies of ongoing developments

El objetivo de este artículo es proporcionar una guía que sirva para la interpretación y seguimiento de los esfuerzos que se están desarrollando en todo el mundo con el objetivo de obtener una vacuna que pueda generar inmunidad contra el nuevo coronavirus SARS-CoV-2 de 2019, el agente causante de la enfermedad por coronavirus denominada COVID-19. Cinco meses después de haber sido detectada la enfermedad, ya hay 102 vacunas en distintos estadios de desarrollo, registradas por la Organización Mundial de la Salud (OMS), correspondientes a 8 plataformas vacunales con diferentes estrategias, y todos los días aparecen nuevas. Esto representará un enorme desafío de organismos internacionales, para la evaluación, comparación y selección de aquellas que cumplan con los criterios regulatorios indispensables de seguridad y eficacia y que, por otro lado, puedan ser producidas en cantidades suficientes para abastecer la demanda mundial. (AU)

The objective of this article is to provide a guide to help the interpretation and monitoring the efforts that are being carried out worldwide to obtain a vaccine that will be able to generate immunity against the new 2019 SARS-CoV-2 coronavirus, the viral agent causes the disease named COVID-19. Five months after the disease was detected, there are already 102 vaccines at different stages of development, registered by World Health Organization (WHO), corresponding to 8 vaccination platforms base on different strategies, and every day new ones appear. This will represent a huge challenge for international organizations, to evaluate, compare and selects those that will meet the essential regulatory criteria of safety and efficacy and that, would be able to be produced in enough quantities to supply the worldwide demand. Key words: SARS-Cov-2 vaccine, vaccine platform, COVID-19 strategy, attenuated virus, viral vector, viral proteins, viral DNA, viral RNA, nucleic acids, viral like particles, WHO. (AU)

Virology: syndromic diagnosis of meningitis and encephalitis. / Virología: diagnóstico sindrómico de meningitis y encefalitis.

Viral infections of the nervous system represent a major health problem. It is estimated that the incidence of viral meningitis in the general population ranges from 5-17 cases per 100,000 inhabitants per year in developed countries. This heading encompasses highly varied clinical pictures, ranging from meningitis to encephalitis. This article presents the agents involved in our environment and discusses their expressiveness. In immunocompetent patients, the course of these infections is usually benign. Nucleic acid amplification techniques are the gold standard for their etiological diagnosis. The introduction of polymerase chain reaction and serological diagnosis of the main arboviruses has increased the diagnostic capabilities in a wide spectrum of these clinical entities.

Detección molecular del gen de la glicoproteína B del virus herpes felino / Molecular detection of glycoprotein B from feline herpesvirus

El virus herpes felino tipo 1 genera múltiples problemas y el gato termina con consecuencias que afectan su futura calidad de vida. Este virus está distribuido en todo el mundo y es de fácil transmisión y dado que es un patógeno latente, continúa propagándose sin control a toda la población de gatos. El diagnóstico se basa en los signos clínicos, existiendo hoy en Chile solo un método de diagnóstico de laboratorio específico, implementado para identificar el agente, que no se usa regularmente en la clínica de animales pequeños. Así, el tratamiento y diagnóstico generalmente se basan en el conocimiento y la experiencia del médico veterinario, sin dejar una confirmación real sobre qué agente está causando los síntomas. Esta investigación propuso un método de diagnóstico molecular alternativo a la detección del gen de la timidina quinasa viral, para el cual se seleccionaron gatos menores de 1 año de edad, con síntomas compatibles con una infección con el virus del herpes felino. El método de la Reacción en Cadena de la Polimerasa (PCR) se utilizó para detectar el gen de la glicoproteína B del virus herpes felino tipo 1, seguido de la determinación del porcentaje de identidad de nucleótidos (PIN) respecto a los datos oficiales del GenBank®. De los 11 gatos estudiados, en solo uno de ellos se pudo amplificar un segmento que correspondía al gen de la glucoproteína B. El PIN resultante (>96 por ciento) confirma que la secuencia obtenida corresponde al gen de la glicoproteína B tipo 1 del virus del herpes felino y se discute la eficiencia del método implementado(AU)

The feline herpesvirus type 1, generates multiple problems and the cat ends with consequences that affect its future quality of life. This virus is distributed throughout the world and is easily transmitted and since it is a latent pathogen, it continues to spread uncontrollably to the entire cat population. The diagnosis is based on clinical signs, today there is only a specific laboratory diagnostic method implemented in Chile to identify the agent, which is not used regularly in the clinic of small animals. Thus, the treatment and diagnosis are usually based on the knowledge and experience of veterinarian without leaving a real confirmation about which agent is causing the symptoms. This research proposed a molecular diagnostic method alternative to timidine kinase detection gene, for which cats under 1 year of age were selected, with symptoms compatible with an infection with the feline herpesvirus. The Polymerase Chain Reaction (PCR) method was used to detect the feline herpesvirus type 1 glycoprotein B gene, followed by the determination of the percentage of nucleotide identity (NIP) from official GenBank® data. Of the 11 cats studied, only one of them resulted in the amplification of a segment corresponding to the glycoprotein B gene. The resulting NIP (> 96 percent) confirms that the sequence obtained corresponds to type 1 glycoprotein B gene of feline herpesvirus and the efficiency of the method implemented is discussed(AU)

Epigenética de la enfermedad renal / Epigenetics of Renal Disease

Para nosotros generar una defnición determinada y entendible necesitamos de elementos de comparación; así, por ejemplo, para nosotros "entender "que es el "día" necesariamente debemos conocer que es la "noche". Esta antítesis por contraste nos grafca estos dos conceptos y nos lleva al ámbito de la "certidumbre" y es por esto que un "eclipse total" en pleno día se presenta como un fenómeno de ruptura de lo conocido como "cierto" desde que nacemos y que NO admite contradicción pues es ya parte de nuestra "conciencia genética" ; es decir, un evento externo de la vida real (día-noche) condicionado a eventos internos (genéticos) generando ­ en el caso del ejemplo ­ el "ritmo circadiano", "envejecimiento celular", "esperanza de vida al nacer" , "cronobiología".

For us to generate a definition determined and understandable we need elements of comparison; Thus, for example, for us to "understand" what "day" is, we must necessarily know what is the "night". This contrast antithesis we graph these two concepts and we leads to the field of "certainty" and this is why a "total eclipse" in broad daylight it is presented as a phenomenon of rupture of the known as "true" since we were born and that does NOT admit contradiction it is already part of our "genetic consciousness"; that is, an event external real life (day-night) conditioned to internal events (genetic) generating - in the case from the example - the "circadian rhythm", "Cell aging", "hope of life at birth "," chronobiology ".

[Microbiological diagnosis of invasive mycosis]. / Diagnóstico microbiológico de las micosis invasoras.

The prognosis of invasive fungal infections (IFI) depends on the speed of diagnosis and treatment. Conventional diagnostic methods are of low sensitivity, laborious and too slow, leading to the need for new, faster, and more efficient diagnostic strategies. There are several techniques for diagnosing a candidemia that are faster than the conventional blood culture (BC). Once yeast growth in BC is detected, species identification can be speeded up by mass spectrometry (30minutes), commercialised molecular techniques (60-80minutes) or fluorescent in situ hybridization (90minutes). The combined detection of biomarkers (antimicellium, mannan and anti-mannan or ß-glucan) has shown to be of greater use than their individual use. Commercialised nucleic acid amplification techniques (Septifast®, T2Candida®) are very reliable alternatives to BC. The detection of the capsular antigen of Cryptococcus, by means of latex agglutination or immuno-chromatography, is a valuable technique for cryptococcosis diagnosis. Direct microscopic examination and culture of representative specimens is used for the conventional diagnosis of IFI by filamentous fungi. Detection of galactomannan and ß-glucan are considered diagnostic criteria for probable invasive aspergillosis and probable IFI, respectively, despite the lack of specificity of the latter. The detection of fungal volatile organic compounds in breath is an interesting diagnostic strategy in pulmonary infections. Although widely used, nucleic acid detection techniques are not considered diagnostic criteria for IFIs caused by moulds in consensus documents, due to their lack of standardisation. However, they are the only alternative to culture methods in invasive infections by Scedosporium/Lomentospora, Fusarium, zygomycetes, or dematiaceous fungi.

ADN, disco duro de la vida / DNA, life's hard drive

A lo largo de los últimos dos siglos la medicina se vio nutrida con los descubrimientos bioquímicos que impulsaron el entendimiento de los mecanismos isiopatológicos y facilitó el desarrollo de la terapéutica. En cambio, en el presente siglo entramos a la era de la genómica y del "big data", por lo que el estudio de las funciones del ADN como dispositivo de almacenamiento de información es esencial para la comprensión de la nueva medicina genómica personalizada, de precisión. En la presente revisión, se analiza el ADN como un dispositivo informático con tres funciones: almacenamiento, expresión y transmisión de la información acumulada a lo largo de la ilogenia en forma de secuencias de nucleótidos. Se describe cada una de estas funciones comparándolas con la información manejada por una computadora o una sociedad, y se brindan ejemplos de patologías que surgen ante el fallo de alguna de las funciones. La revisión bibliográica es amplia e incluye los artículos más relevantes, tanto históricos como del estado del arte, correspondientes a cada tema...(AU)

A incorporação do teste diagnóstico baseado na amplificação de ácidos nucleicos (NAT) para triagem de sangue no SUS: arranjos tecnológicos para a nacionalização do "NAT brasileiro" / The introduction of nucleic acid tests (NAT) for blood screening in the Brazilian public healthcare system: technological arrangements for the nationalization of the "Brazilian NAT"

Resumo Os testes de ácidos nucleicos (NAT) são ferramentas complementares aos testes sorológicos para controle da transmissão de doenças infecciosas por meio de produtos obtidos a partir do sangue. Em 2002, um decreto do Ministério da Saúde tornou obrigatória a realização do NAT por todos os bancos de sangue, medida dificultada por razões como os custos necessários para a sua implantação. Como estratégia para a sua incorporação nos bancos de sangue ligados ao SUS, um consórcio público foi criado para desenvolver uma versão local do kit. A partir de métodos de pesquisa qualitativa, os autores analisam essa iniciativa, visando esmiuçar os detalhes da "nacionalização tecnológica" de um teste diagnóstico in vitro. O artigo descreve como o consórcio compreende o kit e como cada uma das tecnologias que o compõem são obtidas e reunidas no teste brasileiro. A relevância dessa análise é identificar quais os desafios e os limites à produção de testes in vitro para doenças infecciosas no Brasil, assim como a repercussão desse tipo de iniciativa para o sistema nacional de inovação em saúde.

Abstract Nucleic acid based amplification tests (NAT) are employed as complementary tools to control the transmission of infectious diseases through contaminated blood. In 2002, a decree from the Brazilian Ministry of Health made compulsory the use of NAT by all the blood services in the country, a measure that was challenged by costs related to the test incorporation. As the strategy to introduce the test in the blood banks serving the public healthcare system (Sistema Único de Saúde), a public Consortium was constituted to develop a local version of the kit. On the basis of qualitative fieldwork, the authors investigate the strategies used by the Brazilian laboratories and universities to nationalize the kit through capturing and assembling its various components. The paper contributes to revealing the challenges and limits to the production of in vitro tests for infectious diseases in Brazil, as well as the repercussion of such an initiative to the national healthcare innovation system.

In vitro digestibility of specific dsRNA by enzymes of digestive tract of shrimp Litopenaeus vannamei / Digestibilidad in vitro del dsRNA específico por enzimas del tracto digestivo del camarón Litopenaeus vannamei

ABSTRACT Objective. The digestibility of specific dsRNA by action of the enzymes of digestive tract of the whiteleg shrimp Litopenaeus vannamei was determined in vitro. Materials and methods. Digestive enzyme activity (amylase, lipase, protease, DNase and RNase) was measured in the stomach, digestive gland, and anterior, middle, and posterior intestine of juvenile shrimp, and the digestibility of DNA, RNA and the dsRNA-ORF89, specific to WSSV, was determined by in vitro assays, as well as electrophoretic and densitometric analyses. Results. The highest enzymatic activity was found in the digestive gland: amylase (81.41%), lipase (92.60%), protease (78.20%), DNase (90.85%), and RNase (93.14%). The highest digestive capacity against DNA, RNA, and dsRNA was found in the digestive gland (5.11 ng of DNA ​​per minute, 8.55 ng of RNA per minute, and 1.48 ng dsRNA per minute). Conclusions. The highest digestibility of dsRNA-ORF89, specific to WSSV, was found in the digestive gland, whereas the lowest digestibility was observed in the posterior intestine. This is the first report regarding the digestibility of dsRNA-ORF89 by whiteleg shrimp digestive tract enzymes, with potential therapeutic importance in shrimp culture to prevent WSSV disease through balanced feed.

RESUMEN Objetivo. La digestibilidad del dsRNA específico para el virus de la mancha blanca (WSSV) por acción de las enzimas del tracto digestivo del camarón Litopenaeus vannamei fue analizada in vitro. Materiales y métodos. Se midió la actividad de enzimas digestivas (proteasa, amilasa, lipasa, ADNasa y ARNasa) en el estómago, la glándula digestiva, el intestino anterior, medio y posterior en juveniles de camarón patiblanco y se evaluó la digestibilidad de ácidos nucleicos ADN, ARN y dsRNA-ORF89 especifico contra el virus WSSV, por análisis electroforéticos y densitometría. Resultados. La actividad enzimática más alta se encontró en la glándula digestiva del camarón: amilasa (81.41%), lipasa (92.60%), proteasa (78.20%), ADNasa (90.85%) y ARNasa (93.14%). Se evidenció la capacidad digestiva del camarón patiblanco contra el ADN, ARN y dsRNA-ORF89 encontrando en la glándula digestiva la mayor digestión (5.11 ng de ADN por minuto, 8.55 ng de ARN por minuto y 1.48 ng de dsRNA por minuto). Conclusiones. La mayor digestibilidad del dsRNA-ORF89, específico contra el virus WSSV, se encontró en la glándula digestiva y la menor en el intestino posterior. Este es el primer informe relacionado con la digestibilidad del dsRNA-ORF89 por las enzimas del camarón patiblanco con potencial importancia terapéutica en el cultivo de camarón para prevenir la enfermedad del WSSV a través del alimento balanceado.

Preservación de biopsias obtenidas por colonoscopia en pacientes con cáncer colorrectal para análisis moleculares / Preservation of obtained biopsies by colonoscopy in patients with colorectal cancer for molecular analysis

Introducción: los estudios relacionados con el análisis del ADN han marcado una pauta para los avances en las ciencias básicas y uno de los requisitos para la obtención de buenos resultados es la calidad del material genético extraído, en conjunto con el método empleado para la preservación de las muestras. Objetivo: comparar tres métodos de preservación de biopsias obtenidas por colonoscopia en pacientes con cáncer colorrectal con fines de uso en estudios de biología molecular. Materiales y métodos: se tomaron biopsias por colonoscopia a nueve pacientes con diagnóstico clínico de cáncer de colon, las cuales se preservaron en solución salina y dos solventes estabilizadores de ácidos nucleicos, RNAlater® y LifeGuard™ Soil Preservation Solution; se realizó extracción del ADN total a las nueve muestras y se verificó la concentración y la calidad del ADN extraído. Resultados: la extracción del ADN a las 24 horas, ocho días, quince días, un mes, seis meses, uno y dos años después de la toma de la muestra, mostró que el ADN de las biopsias preservadas en solución salina se presentaba con baja concentración y degradado a los ocho días, mientras que el preservado en soluciones comerciales estabilizadoras presentó una buena calidad y alta concentración. Por otro lado, la calidad del ADN fue verificada mediante la amplificación por reacción en cadena de la polimerasa (PCR) de un fragmento de ADN asociado al gen APC. Conclusiones: las soluciones LifeGuard™ y RNAlater® pueden ser usadas durante el transporte y conservación de tejidos humanos, y pueden ser recomendados para aquellos laboratorios que deseen preservar muestras con métodos diferentes al embebido de muestras en parafina o que no cuentan con métodos de conservación altamente eficientes como la criogénesis. (AU)

Introduction: Studies related to DNA analysis have set a standard for development in the basic sciences, and one of the requirements for obtaining good results is the quality of the genetic material extracted, together with the method used for the samples preservation. Objective: To compare three methods of preserving biopsies obtained by colonoscopy in patients with colorectal cancer, for purposes of use in molecular biology studies. Materials and methods: Biopsies by colonoscopy from nine patients with clinical diagnosis of colon cancer were taken and preserved in saline solution and two nucleic acids stabilizing solvents, RNAlater® y LifeGuard™ Soil Preservation Solution. The extraction of total DNA was carried out to the nine samples and the concentration and quality of the extracted DNA was verified. Results: DNA extraction at 24 hours, eight days, 15 days, one month, six months, one year and two years after sampling showed that the DNA from biopsies preserved in saline solution had low concentration and degraded at eight days. DNA from samples preserved in commercial stabilizing solutions had high concentration and good quality. This last one was verified by amplification of a DNA fragment associated to the APC gene by polymerase chain reaction. Conclusions: The LifeGuard™ solution as well as the RNAlater® can be used in transport and conservation of human tissues, and may be recommended for laboratories wishing to preserve specimens with different methods to paraffin-embedded specimen or that do not have highly efficient conservation methods such as cryogenics. (AU)

Infecciones de transmisión sexual silentes: la muestra de orina permite una adecuada detección / Non symptomatic sexually transmitted infections: urine sample allows an adequate detection

Detection of non-symptomatic sexually transmitted infections (NSSTD) has taken great relevance, primarily due to global increase. This has led to implement various laboratory techniques with the aim of early detection of these silent infections to decrease the incidence. Techniques usually used for the detection and identification of NSSTD require invasive samples (blood, citobrush, etc.), so the urine could be a simpler option and noninvasive sample when the patient be subjected to test for some of these infections.

La detección de infecciones de transmisión sexual silentes (ITSS) ha tomado gran relevancia, debido principalmente a su incremento en el mundo. Esto ha llevado a implementar diversas técnicas de laboratorio con la finalidad de la detección precoz de estas infecciones silentes para disminuir su incidencia. Las técnicas que habitualmente se utilizan para la detección e identificación de ITSS requieren de una muestra invasora (sangre, citobrush, entre otras), por lo que la orina podria ser una opción de muestra más simple y no invasora al momento que el paciente se deba someter a un examen para detectar alguna de estas infecciones.

Contribuciones de la técnica de la Reacción en Cadenas de la Polimerasa a la Epidemiología Molecular de las enfermedades infecciosas en Cuba / Contributions of the Polymerase Chains Reaction technique to the Molecular Epidemiology of the infectious diseases in Cuba

Introducción: la Epidemiología Molecular es una disciplina que emplea elementos de la epidemiología clásica apoyado en resultados obtenidos mediante herramientas moleculares, por lo que la introducción de la técnica de la Reacción en Cadenas de la Polimerasa (RCP) ha sido muy importante en el desarrollo de la misma. Objetivo: realizar un análisis cronológico de las principales contribuciones desde la introducción de la técnica de Reacción en Cadenas de la Polimerasa en investigaciones de la Epidemiología Molecular de las enfermedades infecciosas en Cuba. Material y Métodos: se realizó una revisión de 105 artículos científicos publicados en las principales bases de datos médicas (Infomed, Scielo, PubMed, EBSCO, HINARI), en los que se han expuesto los distintos avances de la introducción de esta técnica molecular en Cuba. Resultados: esta técnica se introdujo con fines epidemiológicos por primera vez en Cuba en 1992 para el diagnóstico perinatal de la infección por VIH-1. En 1997 se realiza la confirmación de la presencia del virus linfotrópico tipo I de las células T humanas y un año después se realiza la primera identificación molecular de cepas del Virus del Papiloma Humano. Entre 1998 y la actualidad se ha introducido en nuestro país la mayoría de los tipos de RCP con fines epidemiológicos y diagnósticos. Conclusiones: la introducción de la técnica de RCP ha revolucionado las investigaciones de Epidemiología Molecular de enfermedades infecciosas en Cuba(AU)

Introduction: the Molecular Epidemiology is a discipline that uses elements of the classic epidemiology supported in results obtained by means of molecular tools, therefore the introduction of Polymerase Chain Reaction technique (PCR) it has been very important in the development of the same one. Objective: to carry out a chronological analysis of the main contributions of the PCR technique in Molecular Epidemiology investigations of the infectious diseases in Cuba. Material and Methods: it was carried out a revision of 105 scientific articles published in the main medical databases (Infomed, Scielo, PubMed, EBSCO, HINARI) where they are shown the different advances of the introduction of this molecular technique in Cuba. Results: it was found that this technique was introduced for the first time with epidemiologic grounds in Cuba in 1992 for the perinatal diagnosis of HIV-1 infection. In 1997 it was carried out the confirmation of the presence of the human T-cells limphotrophic virus type I and one year later it was carried out the first molecular identification of Human Papillomavirus strains. Between 1998 and the present time it was introduced in our country most of the types of PCR with epidemiologic and diagnostic purpose. Conclusions: the introduction of the PCR technique has revolutionized the investigations of Molecular Epidemiology of infectious diseases in our country(AU)

Seleção de aptâmeros que se ligam ao receptor humano para o gosto doce / Screening for aptamers that bind to the human sweet taste receptor (hT1R2/hT1R3)

Foi demonstrado que o gosto doce é transduzido por receptores acoplados a proteína G classe III (GPCRs), T1R2 e T1R3. Essas proteínas exibem longas extremidades amino-terminais que formam um domínio de ligação globular extracelular. Elas são expressas em células associadas ao gosto (células epiteliais que constituem os botões gustativos nas papilas gustativas), que respondem a moléculas associadas ao gosto doce. Quando T1R2 e T1R3 são co-expressas em células heterólogas, elas respondem, como heterômeros, a uma série de açúcares, alguns D-aminoácidos, edulcorantes artificiais e proteínas doces. Foi também demonstrado que o receptor humano T1R2/T1R3 para o gosto doce apresenta múltiplos sítios de ligação. Para melhor compreender a estrutura desse receptor e responder à pergunta de como um único quimiorreceptor pode ser responsivo a uma variedade de ligantes, foi utilizada a abordagem denominada evolução sistemática de ligantes por enriquecimento exponencial (SELEX) para isolar, a partir de uma biblioteca combinatória de oligonucleotídeos, aptâmeros de RNA resistentes a nuclease que se ligam ao receptor humano para o gosto doce com alta afinidade. Após um enriquecimento de doze ciclos do pool original de RNA contendo em torno de 1013 sequências diferentes (contra preparações de membrana de células HEK293T que expressam hT1R2/hT1R3) e outros ciclos de contrasseleção negativa (para eliminar moléculas de RNA que se ligam de forma inespecífica à membrana de nitrocelulose e a outras proteínas diferentes do alvo, ou seja, proteínas de membrana de células HEK293T selvagem), realizou-se a transcrição reversa do RNA seguida de amplificação por PCR e sequenciamento. Aptâmeros do ciclo 12 com sequências consenso foram selecionados, e a ligação de alguns deles com hT1R2/hT1R3 foi então avaliada. Cinco desses aptâmeros mostram claramente uma maior afinidade por células HEK293T que expressam hT1R2/hT1R3. Como segunda parte desta tese, estudamos outro receptor, denominado CD36, que, como o receptor T1R2/T1R3, é expresso na língua. Estudos indicam que ele age como receptor gustativo de gordura. Neste trabalho, verificamos que essa proteína é expressa em uma subpopulação de neurônios olfatórios presentes no epitélio olfatório, indicando que ela pode ter também uma função olfatória, ainda não caracterizada

It has been shown that sweet taste is transduced by the Class III G Protein-Coupled Receptors (GPCRs) T1R2 and T1R3, which show long N-termini that form a globular extracellular ligand-binding domain. These receptors are expressed in the taste cells (epithelial cells that constitute the taste buds in taste papillae) that respond to sweet tastants, and when T1R2 and T1R3 are coexpressed in heterologous cells, they respond, as heteromers, to a series of sugars, some D-amino acids, artificial sweeteners and sweet proteins. It has also been demonstrated that the sweet taste receptor has multiple binding sites. In order to better understand the structure of this receptor and answer the question of how a single chemoreceptor can respond to a variety of ligands, we used the combinatorial oligonucleotide library screening approach, denominated Systematic Evolution of Ligands by Exponential Enrichment (SELEX), to isolate nuclease-resistant RNA aptamers that bind to the human sweet taste receptor with high affinity. Following a twelve round enrichment of the previous random RNA pool containing around 1013 different sequences (against membrane preparations of hT1R2/hT1R3-expressing HEK293T cells) and negative counterselection cycles (to eliminate RNA molecules that bind nonspecifically to the nitrocellulose membrane and to proteins other than the target, that is, HEK293T cells membrane proteins), the RNA was reverse-transcribed for DNA sequencing. Aptamers from cycle 12 with consensus sequences were selected, and the binding of some of them to the human sweet taste receptor was then evaluated. Five out of the aptamers clearly show greater affinity for hT1R2/hT1R3-expressing HEK293T cells than for hT1R2/hT1R3-non-expressing HEK293T cells. In this thesis we have also analyzed another receptor, denominated CD36, which is also expressed in the tongue. Studies indicate that it acts as a receptor for fat. In this work, we found that CD36 is expressed in a subset of the olfactory neurons localized in the olfactory epithelium, indicating that it may also have an as yet uncharacterized olfactory function