Advancement in Cellular Topographic and Nanoparticle Capture Imaging by High Resolution Microscopy Incorporating a Freeze-Drying and Gaseous Nitrogen-based Approach.

Scanning electron microscopy (SEM) offers an unparalleled view of the membrane topography of mammalian cells by using a conventional osmium (OsO4) and ethanol-based tissue preparation. However, conventional SEM methods limit optimal resolution due to ethanol and lipid interactions and interfere with visualization of fluorescent reporter proteins. Therefore, SEM correlative light and electron microscopy (CLEM) has been hindered by the adverse effects of ethanol and OsO4 on retention of fluorescence signals. To overcome this technological gap in achieving high-resolution SEM and retain fluorescent reporter signals, we developed a freeze-drying method with gaseous nitrogen (FDGN). We demonstrate that FDGN preserves cyto-architecture to allow visualization of detailed membrane topography while retaining fluorescent signals and that FDGN processing can be used in conjunction with a variety of high-resolution imaging systems to enable collection and validation of unique, high-quality data from these approaches. In particular, we show that FDGN coupled with high resolution microscopy provided detailed insight into viral or tumor-derived extracellular vesicle (TEV)-host cell interactions and may aid in designing new approaches to intervene during viral infection or to harness TEVs as therapeutic agents.

Estrategias de prosocialidad en jóvenes desvinculados del conflicto armado en Colombia / Strategies of Prosociality in Young People Disengaged from the Armed Conflict in Colombia

Resumen Este trabajo tiene el propósito de establecer las estrategias de prosocialidad de jóvenes desvinculados del conflicto armado colombiano, como un aporte a la comprensión del perfil psicológico de esta población para la implementación de procesos de intervención efectivos que permitan su reincorporación y adapta ción a la vida civil. Se encontró que, las variables que conforman la prosocialidad, la sensibilidad social, la conformidad de lo socialmente correcto y las dificulta des sociales, presentan relaciones importantes tanto positivas como negativas. Se confirma la hipótesis alterna que mostraba la existencia de relaciones direc tas entre la competencia social y el comportamiento prosocial relativo a lo que es socialmente correcto.

Abstract The purpose of this work is to establish the prosociality strategies of young peo ple disengaged from the Colombian armed conflict, as a contribution to the un derstanding of the psychological profile of this population for the implementa tion of effective intervention processes, which allow their reincorporation and adaptation to civilian life. It was found that the variables, which make up proso ciality, social sensitivity, conformity to social correctness and social difficulties, present important positive and negative relationships. The alternative hypo thesis showing the existence of direct relationships between social competence and prosocial behavior related to what is socially correct is confirmed.

Relación entre funciones ejecutivas y la competencia social, en menores que se desvinculan del conflicto armado en Colombia / Relationship between executive functions and social competence, in minors who disassociate themselves from the armed conflict in Colombia

Resumen. El presente estudio tuvo por objetivo determinar el perfil del funcionamiento ejecutivo (Dorsal y orbital) y el tipo de relación con la competencia social que tiene que ver con lo que es socialmente correcto, en una población de menores que se desvinculan del conflicto armado en Colombia. El alcance de la propuesta fue descriptivo-correlacional. El diseno cuasi experimental, de orden longitudinal para la recolección de los datos relacionados con la evaluación neuropsicológica y la evaluación de la competencia social. De carácter cuantitativo, se evaluaron las variables a través de instrumentos estandarizados y sus puntuaciones son de tipo numérico. Se encontró un coeficiente de correlación mùltiple de R=0.759, entre las FE, y la criterio (competencia social) por lo tanto el 57.6% de la variabilidad de lo que se considera Socialmente Correcto, puede explicarse por las variables predictoras contempladas en el modelo. El ajuste del modelo puede considerarse alto. Así mismo, el valor de significancia permite comprobar que la regresión entre las variables independientes y la variable dependiente es significativa. Con ello se rechaza la hipótesis nula (p=0,001). Y se acepta la existencia de relaciones directas/inversas entre el funcionamiento ejecutivo y la competencia social que hace referencia a lo que es socialmente correcto.

Abstract. The objective of the present study was to establish the relationship between the profile of executive functioning and social competence that has to do with what is socially correct, in a population of 70 minors who disassociate themselves from the armed conflict in Colombia. The scope of the proposal was descriptive-correlational. The design we used was quasi-experimental, longitudinal in order to collect the data related to the neuropsychological evaluation and the evaluation of social competence. It is quantitative in nature; the variables were evaluated through standardized and valid instruments. We find positive and negative relationships between executive functions and social competence; that is, the alternative hypothesis of the research is accepted, in which we propose the existence of direct relationships between executive functioning and social competence.

Relación entre acciones de riesgo y el intento de suicidio en jóvenes universitarios, como factor de Bienestar Psicológico / Relationship between Risk Actions and Attempted Suicide in Young College Students as a Psychological Welfare Factor

Resumen Los comportamientos autodestructivos se pueden entender como factores de riesgo de suicidio, en tanto son condiciones de orden personal o circunstancial que pueden indicar la posibilidad de comportamiento suicida, pero además como un factor de inestabilidad o desequilibrio del Bienestar psicológico. Así, las conductas de riesgo son condiciones que aumentan la probabilidad de que se cometa suicidio o se exponga la vida a constantes peligros.

Abstract This article makes emphasis on two aspects, suicide and life-threatening actions is a product of research carried out at three universities in Medellin, Colombia, on suicide prevention in university scenarios. Self-destructive behaviors can be understood as suicide risk factors, as long as they are personal or circumstantial conditions, which may indicate the possibility of suicidal behavior, but also as a factor of instability or imbalance of psychological well-being. Thus, risky behaviors are conditions, which increase the likelihood of suicide or exposure to constant danger. The results indicate a high relationship between life-threatening behaviors and acts with explicit intent to commit suicide. In conclusion, university students with low levels of psychological well-being are exposed to high-risk situations and are more prone to suicidal thoughts and acts.

El agente educativo en la garantía de la protección integral de la primera infancia / The Educational Agent in Ensuring Comprehensive Early Childhood Protection

Resumen Al identificar los aportes investigativos sobre el rol que ejercen los docentes de primera infancia para la garantía de la protección integral en la niñez, se evidenciaron las brechas en la garantía de la protección integral a la infancia, las cuales surgen desde el mismo núcleo familiar, desde el Estado por la dificultad de cumplir con esta labor, por la falta de corresponsabilidad social frente a los niños y la recarga en los docentes como principales actores en este proceso. Aunque el agente educativo, es un actor significativo para el desarrollo integral de los niños, no puede recaer en su quehacer toda la responsabilidad de la protección a la primera infancia, es necesario articular esfuerzos estatales que comprometan otras instancias institucionales y actores sociales, que posibiliten brindar servicios educativo formativos a la primera infancia, propiciar y recrear espacios para la participación de las familias y de personas significativas en las acciones orientadas a la Protección infantil.

Abstract By identifying research contributions to the role played by teachers in early childhood for ensuring comprehensive protection in children, gaps in ensuring comprehensive child protection, which arise from the same family nucleus, from the State because of the difficulty of fulfilling this work, by the lack of social co-responsibility against children and recharging on teachers as key players in this process, were evident. Although the educational agent, a significant player for the integral development of children, cannot rest with its responsibility for early childhood protection, it is necessary to articulate state efforts, which compromise other institutional instances and social actors, which make it possible to provide educational services early childhood training, to foster, and to recreate spaces for the participation of families and significant people in actions oriented to child protection.

The Association between Needle Size and Waste Product and Its Effect on Cost-Effectiveness of Botulinum Toxin Injections?

Clostridium botulinum toxin (BT) must be administered intramuscularly with a syringe, but dead space in the syringe-needle complex may cause product waste and result in cost implications for the patient and provider. Syringe dead space is the volume of residual fluid that remains within the syringe after the plunger is fully depressed during medication injection. We calculated the average volume of remaining product in a syringe-needle complex and cost loss implication of this volume of BT. This is a single-center, analytical study using saline and four different sized needles for analytics of waste product and cost-effectiveness. Syringes of 1 mL with attached 18, 21, 30, and 32-gauge (G) needles, respectively, were compared. The syringe-needle complex was weighed before drawing 0.05 mL of saline. The fluid was then discarded with the appropriate syringe and then weighed again. This procedure was repeated for the four needle types and the average difference in weight of the syringe-needle complex before and after saline waste was measured. The volume was converted to units of BT used in clinical practice and the cost of waste product evaluated. The mean difference in needle-syringe complex weight before and after intervention was 0.068, 0.056, 0.04, and 0.026 g for the 18, 21, 30, and 32G needles, respectively. We found a statistically significant difference comparing the 18G with the 30 and 32G (0.02 and 0.0007, respectively) and comparing the 21G with the 30 and 32G (0.0042 and 0.00002, respectively). When we extrapolated the data to BT units (4U/0.1 mL), we found that theoretically 2.72, 2.24, 1.6, and 1.04 units of BT are left in the syringe-needle complex for the 18, 21, 30, and 32G syringes, respectively. At a cost of $6.01/U of onabotulinum toxin A, we then calculated a provider loss of a gross average (mean) revenue of $96 and 62.4 per 10 syringes used with 30 and 32G needles. Needle size used for drawing up and administering BT has an effect on the amount of waste product and subsequently on cost-effectiveness.

Non-reversible tissue fixation retains extracellular vesicles for in situ imaging.

Extracellular vesicles (EVs) are secreted nanosized particles with many biological functions and pathological associations. The inability to image EVs in fixed tissues has been a major limitation to understanding their role in healthy and diseased tissue microenvironments. Here, we show that crosslinking mammalian tissues with formaldehyde results in significant EV loss, which can be prevented by additional fixation with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) for visualization of EVs in a range of normal and cancer tissues.

Reacción psicológica ante la experiencia de abuso sexual extrafamiliar en padres de niños abusados / Psychological reactions in parents of children who have suffered extra-familiar sexual abuse

Resumen Objetivo: Analizar las reacciones psicológicas en padres de niños que han sufrido la experiencia de abuso sexual extrafamiliar-ASE, realizado en el Centro de Atención Integral a Víctimas de Abuso Sexual-CAIVAS, de la Fiscalía, seccional Medellín, Colombia. Método: El estudio se realizó desde un enfoque cualitativo, histórico hermenéutico, con metodología fenomenológica. Para la recolección de la información, se hicieron entrevistas a diez padres de familia, nueve madres y un padre, quienes acudían a proceso judicial por denuncia penal del evento ASE; estos se eligieron de manera selectiva, desde el archivo de noticia criminal que recibe el área de psicología, y participaron de manera libre, a partir de firma de consentimiento informado. El análisis de la información generada se realizó a través de una categorización y codificación relacional. Resultados: Los más relevantes indican traumas transgeneracionales y sentimientos difusos como padres cuidadores, que dificultan la forma de asumir sus funciones parentales e impiden que sean agentes protectores para sus hijos. Conclusión: Se evidenció que el abuso sexual extrafamiliar tiene implicaciones directas en los padres y que su intervención exige abordar todo el sistema familiar, ya que cuando una familia se expone a este evento, la dinámica se problematiza, dificultando la protección del hijo y la capacidad de afrontamiento de este, ante una amenaza de este tipo.

Abstract Objective: This paper is the result of a research whose objective was to analyze psychological reactions in parents of children who have suffered extra-familial sexual abuse, ASE; this research was conducted at Centro de Atención Integral a Víctimas de Abuso Sexual - CAIVAS - Prosecutor office, in Medellin, Colombia. Method: A qualitative, historical hermeneutic approach was used, through a Phenomenological methodology; for data collection, ten parents taken from criminal new files, and who were received through a free and informed consent signature by psychology area, were sampled, as follows : nine mothers and one father, who attended to judicial process for criminal proceeding related to ASE event In order to analyze the information, a categorization and relational codification, which allowed us to know psychological reactions from parents whose children were victims of sexual abuse, were made. Results: The most relevant results are trans-generational traumas and diffuse feelings, such as caregiver parents, for whom to assume their parental functions is difficult and prevent them to be their children protectors. Conclusion: As a conclusion, it was evident that extra-familial sexual abuse has direct implications on their parents, as well as its intervention, demands to approach the whole family system; because when a family is affected by this event, the dynamics are problematized, not only making the child protection difficult for parents, but also for helping the child develop coping skills with a threat of this type.

Reconocimiento y Participación de nuevos agentes educativos en la Escuela: Auxiliares de la Educación / Recognition and participation of new educational agents in the school: Educational assistants

Resumen Los auxiliares de la educación, es una categoría que abarca a las personas que trabajan en Instituciones Educativas como: vigilantes, conserjes, asistentes administrativos, personal de aseo, secretarias, entre otros. Se plantea desde un enfoque hermenéutico interpretativo, la incidencia de este personal en el proceso educativo. Por ello se precisa analizar la posición que éstos asumen en diferentes situaciones que se presentan en la convivencia escolar permitiendo, desde las categorías de emociones y reconocimiento, identificar sus aportes al proceso formativo en la Institución Educativa.

Abstract Educational assistants corresponds to a category that comprises people working for educational institutions, such as security guards, custodians, administrative assistants, cleaning staff, secretaries, among others. The incidence of this staff on the educational process is posed from a hermeneutical interpretive approach. For that reason, it is necessary to analyze the position that these people take on in different situations that arise in the school coexistence allowing, from the categories of emotions and recognition, to identify their contributions to the training process in the educational institution.

Parental styles in the process of raising children with disruptive disorders / Estilos parentales en el proceso de crianza de niños con trastornos disruptivos

RESUMEN El presente artículo aborda desde el concepto de estilos parentales la función de crianza de los padres que tienen hijos con trastornos disruptivos, tema enmarcado dentro de un proyecto de investigación que tuvo por objetivo evaluar la efectividad de un programa de intervención neuropsicológico y psicosocial de niños con diagnóstico de trastornos comportamentales entre 9 y 12 años. Se empleó una metodología fenomenológica desde un enfoque cualitativo. Entre los resultados, sobresalen la relación entre el fortalecimiento de los estilos parentales, desde una autoridad y afecto firmes, y un desarrollo emocional y social más estable en sus hijos. En conclusión, los comportamientos disruptivos se agravan por causa de estilos parentales ambivalentes, permisivos o autoritarios.

ABSTRACT The present article discusses from the concept of parenting styles the parenting function of parents who have children with disruptive disorders, a topic framed within a research project that aimed to evaluate the effectiveness of a program of neuropsychological and psychosocial intervention of children with Diagnosis of behavioral disorders, between 9 and 12 years. A phenomenological methodology was used from a qualitative approach. The results highlight the relationship between strengthening parenting styles, from firm authority and affection, and more stable emotional and social development in their children. In conclusion, disruptive behaviors are aggravated by ambivalent, permissive and/or authoritarian parental styles.

El bullying y el suicidio en el escenario universitario / Bullying and suicide in university settings

El artículo que presentamos, da cuenta de la línea "Acoso y suicidio", del proyecto de investigación nacional La prevención del suicidio en el escenario universitario: acciones, vínculos y significaciones, en el cual participaron 17 universidades de Colombia, liderado por la Fundación Universitaria Luis Amigó. Se realizó un rastreo bibliográfico desde el referente histórico del acoso escolar (bullying). Seguido de esto, se contextualizaron, desde el escenario universitario, los conceptos de intimidación y ciberacoso, relacionados con el suicidio entre pares. Por último, se plantearon algunas formas de prevención e intervención para dichos fenómenos, desde los ámbitos educativo, familiar y social. A través del rastreo bibliográfico, se analizaron los principales aportes de investigaciones de interés sobre el tema. Entre estas destacamos el significado de intimidación, ciberacoso y su relación con el suicidio en los jóvenes y sus características en los escenarios universitarios, así como información sobre formas de prevención e intervención de esta problemática relacional que implica tanto a las víctimas, a los agresores y a los espectadores en los contextos educativos.

The present article subscribes to the "Harassment and Suicide" line of research, and gives account of the national research project Prevention of Suicide in University Settings: Actions, Links, and Meanings, which was led by Luis Amigó University, with the participation of 17 universities in Colombia. After reviewing the literature, we place bullying, cyberbullying, and harassment in the university context, and we link them to peer-promoted suicide. Then we propose some forms of prevention and intervention at the family, school, and social levels to this phenomenon that involves victims, aggressors, and onlookers.

Barcoded cDNA library preparation for small RNA profiling by next-generation sequencing.

The characterization of post-transcriptional gene regulation by small regulatory (20-30 nt) RNAs, particularly miRNAs and piRNAs, has become a major focus of research in recent years. A prerequisite for characterizing small RNAs is their identification and quantification across different developmental stages, and in normal and disease tissues, as well as model cell lines. Here we present a step-by-step protocol for generating barcoded small RNA cDNA libraries compatible with Illumina HiSeq sequencing, thereby facilitating miRNA and other small RNA profiling of large sample collections.

RNA-ligase-dependent biases in miRNA representation in deep-sequenced small RNA cDNA libraries.

Sequencing of small RNA cDNA libraries is an important tool for the discovery of new RNAs and the analysis of their mutational status as well as expression changes across samples. It requires multiple enzyme-catalyzed steps, including sequential oligonucleotide adapter ligations to the 3' and 5' ends of the small RNAs, reverse transcription (RT), and PCR. We assessed biases in representation of miRNAs relative to their input concentration, using a pool of 770 synthetic miRNAs and 45 calibrator oligoribonucleotides, and tested the influence of Rnl1 and two variants of Rnl2, Rnl2(1-249) and Rnl2(1-249)K227Q, for 3'-adapter ligation. The use of the Rnl2 variants for adapter ligations yielded substantially fewer side products compared with Rnl1; however, the benefits of using Rnl2 remained largely obscured by additional biases in the 5'-adapter ligation step; RT and PCR steps did not have a significant impact on read frequencies. Intramolecular secondary structures of miRNA and/or miRNA/3'-adapter products contributed to these biases, which were highly reproducible under defined experimental conditions. We used the synthetic miRNA cocktail to derive correction factors for approximation of the absolute levels of individual miRNAs in biological samples. Finally, we evaluated the influence of 5'-terminal 5-nt barcode extensions for a set of 20 barcoded 3' adapters and observed similar biases in miRNA read distribution, thereby enabling cost-saving multiplex analysis for large-scale miRNA profiling.

MicroRNA-24 regulates vascularity after myocardial infarction.

BACKGROUND: Myocardial infarction leads to cardiac remodeling and development of heart failure. Insufficient myocardial capillary density after myocardial infarction has been identified as a critical event in this process, although the underlying mechanisms of cardiac angiogenesis are mechanistically not well understood. METHODS AND RESULTS: Here, we show that the small noncoding RNA microRNA-24 (miR-24) is enriched in cardiac endothelial cells and considerably upregulated after cardiac ischemia. MiR-24 induces endothelial cell apoptosis, abolishes endothelial capillary network formation on Matrigel, and inhibits cell sprouting from endothelial spheroids. These effects are mediated through targeting of the endothelium-enriched transcription factor GATA2 and the p21-activated kinase PAK4, which were identified by bioinformatic predictions and validated by luciferase gene reporter assays. Respective downstream signaling cascades involving phosphorylated BAD (Bcl-XL/Bcl-2-associated death promoter) and Sirtuin1 were identified by transcriptome, protein arrays, and chromatin immunoprecipitation analyses. Overexpression of miR-24 or silencing of its targets significantly impaired angiogenesis in zebrafish embryos. Blocking of endothelial miR-24 limited myocardial infarct size of mice via prevention of endothelial apoptosis and enhancement of vascularity, which led to preserved cardiac function and survival. CONCLUSIONS: Our findings indicate that miR-24 acts as a critical regulator of endothelial cell apoptosis and angiogenesis and is suitable for therapeutic intervention in the setting of ischemic heart disease.

Evaluation of a Group A Streptococcus synthetic oligosaccharide as vaccine candidate.

Bacterial infections caused by Group A Streptococcus (GAS) are a serious health care concern that currently cannot be prevented by vaccination. The GAS cell-wall polysaccharide (GAS-PS) is an attractive vaccine candidate due to its constant expression pattern on different bacterial strains and protective properties of anti-GAS-PS antibodies. Here we report for the first time the immunoprotective efficacy of glycoconjugates with synthetic GAS oligosaccharides as compared to those containing the native GAS-PS. A series of hexa- and dodecasaccharides based on the GAS-PS structure were prepared by chemical synthesis and conjugated to CRM(197). When tested in mice, the conjugates containing the synthetic oligosaccharides conferred levels of immunoprotection comparable to those elicited by the native conjugate. Antisera from immunized rabbits promoted phagocytosis of encapsulated GAS strains. Furthermore we discuss variables that might correlate with glycoconjugate immunogenicity and demonstrate the potential of the synthetic approach that benefits from increased antigen purity and facilitated manufacturing.

Differential regulation of mature and precursor microRNA expression by NMDA and metabotropic glutamate receptor activation during LTP in the adult dentate gyrus in vivo.

Regulation of microRNA (miRNA) expression and function in the context of activity-dependent synaptic plasticity in the adult brain is little understood. Here, we examined miRNA expression during long-term potentiation (LTP) in the dentate gyrus of adult anesthetized rats. Microarray expression profiling identified a subpopulation of regulated mature miRNAs 2 h after the induction of LTP by high-frequency stimulation (HFS) of the medial perforant pathway. Real-time polymerase chain reaction analysis confirmed modest upregulation of miR-132 and miR-212, and downregulation of miR-219, while no changes occurred at 10 min post-HFS. Surprisingly, pharmacological blockade of N-methyl-d-aspartate receptor (NMDAR)-dependent LTP enhanced expression of these mature miRNAs. This HFS-evoked expression was abolished by local infusion of the group 1 metabotropic glutamate receptor (mGluR) antagonist, (RS)-1-aminoindan-1,5-dicarboxylic acid (AIDA). AIDA had no effect on LTP induction or maintenance, but blocked activity-dependent depotentiation of LTP. Turning to the analysis of miRNA precursors, we show that HFS elicits 50-fold elevations of primary (pri) and precursor (pre) miR-132/212 that is transcription dependent and mGluR dependent, but insensitive to NMDAR blockade. Primary miR-219 expression was unchanged during LTP. In situ hybridization showed upregulation of the pri-miR-132/212 cluster restricted to dentate granule cell somata. Thus, HFS induces transcription miR-132/212 that is mGluR dependent and functionally correlated with depotentiation rather than LTP. In contrast, NMDAR activation selectively downregulates mature miR-132, -212 and -219 levels, indicating accelerated decay of these mature miRNAs. This study demonstrates differential regulation of primary and mature miRNA expression by mGluR and NMDAR signaling following LTP induction, the function of which remains to be defined.

The PTEN-regulating microRNA miR-26a is amplified in high-grade glioma and facilitates gliomagenesis in vivo.

Activated oncogenic signaling is central to the development of nearly all forms of cancer, including the most common class of primary brain tumor, glioma. Research over the last two decades has revealed the particular importance of the Akt pathway, and its molecular antagonist PTEN (phosphatase and tensin homolog), in the process of gliomagenesis. Recent studies have also demonstrated that microRNAs (miRNAs) may be responsible for the modulation of cancer-implicated genes in tumors. Here we report the identification miR-26a as a direct regulator of PTEN expression. We also show that miR-26a is frequently amplified at the DNA level in human glioma, most often in association with monoallelic PTEN loss. Finally, we demonstrate that miR-26a-mediated PTEN repression in a murine glioma model both enhances de novo tumor formation and precludes loss of heterozygosity and the PTEN locus. Our results document a new epigenetic mechanism for PTEN regulation in glioma and further highlight dysregulation of Akt signaling as crucial to the development of these tumors.

miRNA in situ hybridization in formaldehyde and EDC-fixed tissues.

MicroRNAs are small regulatory RNAs with many biological functions and disease associations. We showed that in situ hybridization (ISH) using conventional formaldehyde fixation results in substantial microRNA loss from mouse tissue sections, which can be prevented by fixation with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide that irreversibly immobilizes the microRNA at its 5' phosphate. We determined optimal hybridization parameters for 130 locked nucleic acid probes by recording nucleic acid melting temperature during ISH.

MicroRNA-21 contributes to myocardial disease by stimulating MAP kinase signalling in fibroblasts.

MicroRNAs comprise a broad class of small non-coding RNAs that control expression of complementary target messenger RNAs. Dysregulation of microRNAs by several mechanisms has been described in various disease states including cardiac disease. Whereas previous studies of cardiac disease have focused on microRNAs that are primarily expressed in cardiomyocytes, the role of microRNAs expressed in other cell types of the heart is unclear. Here we show that microRNA-21 (miR-21, also known as Mirn21) regulates the ERK-MAP kinase signalling pathway in cardiac fibroblasts, which has impacts on global cardiac structure and function. miR-21 levels are increased selectively in fibroblasts of the failing heart, augmenting ERK-MAP kinase activity through inhibition of sprouty homologue 1 (Spry1). This mechanism regulates fibroblast survival and growth factor secretion, apparently controlling the extent of interstitial fibrosis and cardiac hypertrophy. In vivo silencing of miR-21 by a specific antagomir in a mouse pressure-overload-induced disease model reduces cardiac ERK-MAP kinase activity, inhibits interstitial fibrosis and attenuates cardiac dysfunction. These findings reveal that microRNAs can contribute to myocardial disease by an effect in cardiac fibroblasts. Our results validate miR-21 as a disease target in heart failure and establish the therapeutic efficacy of microRNA therapeutic intervention in a cardiovascular disease setting.