Rat1 promotes premature transcription termination at R-loops.

Certain DNA sequences can adopt a non-B form in the genome that interfere with DNA-templated processes, including transcription. Among the sequences that are intrinsically difficult to transcribe are those that tend to form R-loops, three-stranded nucleic acid structures formed by a DNA-RNA hybrid and the displaced ssDNA. Here we compared the transcription of an endogenous gene with and without an R-loop-forming sequence inserted. We show that, in agreement with previous in vivo and in vitro analyses, transcription elongation is delayed by R-loops in yeast. Importantly, we demonstrate that the Rat1 transcription terminator factor facilitates transcription throughout such structures by inducing premature termination of arrested RNAPIIs. We propose that RNase H degrades the RNA moiety of the hybrid, providing an entry site for Rat1. Thus, we have uncovered an unanticipated function of Rat1 as a transcription restoring factor opening up the possibility that it may also promote transcription through other genomic DNA structures intrinsically difficult to transcribe. If R-loop-mediated transcriptional stress is not relieved by Rat1, it will cause genomic instability, probably through the increase of transcription-replication conflicts, a deleterious situation that could lead to cancer.

Phytoalexins of the crucifer Barbarea vulgaris: Structural profile and correlation with glucosinolate turnover.

Phytoalexins are antimicrobial plant metabolites elicited by microbial attack or abiotic stress. We investigated phytoalexin profiles after foliar abiotic elicitation in the crucifer Barbarea vulgaris and interactions with the glucosinolate-myrosinase system. The treatment for abiotic elicitation was a foliar spray with CuCl2 solution, a usual eliciting agent, and three independent experiments were carried out. Two genotypes of B. vulgaris (G-type and P-type) accumulated the same three major phytoalexins in rosette leaves after treatment: phenyl-containing nasturlexin D and indole-containing cyclonasturlexin and cyclobrassinin. Phytoalexin levels were investigated daily by UHPLC-QToF MS and tended to differ among plant types and individual phytoalexins. In roots, phytoalexins were low or not detected. In treated leaves, typical total phytoalexin levels were in the range 1-10 nmol/g fresh wt. during three days after treatment while typical total glucosinolate (GSL) levels were three orders of magnitude higher. Levels of some minor GSLs responded to the treatment: phenethylGSL (PE) and 4-substituted indole GSLs. Levels of PE, a suggested nasturlexin D precursor, were lower in treated plants than controls. Another suggested precursor GSL, 3-hydroxyPE, was not detected, suggesting PE hydrolysis to be a key biosynthetic step. Levels of 4-substituted indole GSLs differed markedly between treated and control plants in most experiments, but not in a consistent way. The dominant GSLs, glucobarbarins, are not believed to be phytoalexin precursors. We observed statistically significant linear correlations between total major phytoalexins and the glucobarbarin products barbarin and resedine, suggesting that GSL turnover for phytoalexin biosynthesis was unspecific. In contrast, we did not find correlations between total major phytoalexins and raphanusamic acid or total glucobarbarins and barbarin. In conclusion, two groups of phytoalexins were detected in B. vulgaris, apparently derived from the GSLs PE and indol-3-ylmethylGSL. Phytoalexin biosynthesis was accompanied by depletion of the precursor PE and by turnover of major non-precursor GSLs to resedine. This work paves the way for identifying and characterizing genes and enzymes in the biosyntheses of phytoalexins and resedine.

Lessons learned from metabolic engineering in hairy roots: Transcriptome and metabolic profile changes caused by Rhizobium-mediated plant transformation in Cucurbitaceae species.

Cucurbitaceae species are used in traditional medicine around the world. Cucurbitacins are highly oxygenated triterpenoids found in Cucurbitaceae species and exhibit potent anticancer activity alone and in combination with other existing chemotherapeutic drugs. Therefore, increasing production of these specialized metabolites is of great relevance. We recently showed that hairy roots of Cucurbita pepo can be used as a platform for metabolic engineering of cucurbitacins to modify their structure and increase their production. To study the changes in cucurbitacin accumulation upon formation of hairy roots, an empty vector (EV) control and Cucurbitacin inducing bHLH transcription factor 1 (CpCUCbH1)-overexpressing hairy roots of C. pepo were compared to untransformed (WT) roots. Whilst CpCUCbH1-overexpression increased production of cucurbitacins I and B by 5-fold, and cucurbitacin E by 3-fold when compared to EV lines, this increase was not significantly different when compared to WT roots. This indicated that Rhizobium rhizogenes transformation lowered the cucurbitacins levels in hairy roots, but that increasing expression of cucurbitacin biosynthetic genes by CpCUCbH1-overexpression restored cucurbitacin production to WT levels. Subsequent metabolomic and RNA-seq analysis indicated that the metabolic profile and transcriptome of hairy roots was significantly changed when compared to WT roots. Interestingly, it was observed that 11% of the differentially expressed genes were transcription factors. It was noteworthy that the majority of transcripts showing highest Pearson correlation coefficients to the Rhizobium rhizogenes genes rolB, rolC and ORF13a, were predicted to be transcription factors. In summary, hairy roots are an excellent platform for metabolic engineering of plant specialized metabolites, but these extensive transcriptome and metabolic profile changes should be considered in subsequent studies.

Stepping into the Void: Lessons Learned from Civil Society Organizations during COVID-19 in Rio de Janeiro.

Brazil experienced some of the highest rates of COVID-19 globally. This was complicated by the fact that 35 million of its citizens have limited access to water, a primary resource necessary to stem the spread of infectious diseases. In many cases, civil society organizations (CSOs) stepped into this void left by responsible authorities. This paper explores how CSOs in Rio de Janeiro helped populations struggling with access to water, sanitation, and hygiene (WASH) during the pandemic, and what coping strategies are transferable to similar contexts. In-depth interviews (n = 15) were conducted with CSO representatives in the metropolitan region of Rio de Janeiro. Thematic analysis of the interviews revealed that COVID-19 exacerbated pre-existing social inequities among vulnerable populations, undermining their ability to protect their health. CSOs provided emergency relief aid but faced the counterproductive actions of public authorities who promoted a narrative that diminished the risks of COVID-19 and the importance of non-pharmacological interventions. CSOs fought this narrative by promoting sensitization among vulnerable populations and partnering with other stakeholders in networks of solidarity, playing a vital role in the distribution of health-promoting services. These strategies are transferrable to other contexts where state narratives oppose public health understandings, particularly for extremely vulnerable populations.

The saponin bomb: a nucleolar-localized ß-glucosidase hydrolyzes triterpene saponins in Medicago truncatula.

Plants often protect themselves from their own bioactive defense metabolites by storing them in less active forms. Consequently, plants also need systems allowing correct spatiotemporal reactivation of such metabolites, for instance under pathogen or herbivore attack. Via co-expression analysis with public transcriptomes, we determined that the model legume Medicago truncatula has evolved a two-component system composed of a ß-glucosidase, denominated G1, and triterpene saponins, which are physically separated from each other in intact cells. G1 expression is root-specific, stress-inducible, and coregulated with that of the genes encoding the triterpene saponin biosynthetic enzymes. However, the G1 protein is stored in the nucleolus and is released and united with its typically vacuolar-stored substrates only upon tissue damage, partly mediated by the surfactant action of the saponins themselves. Subsequently, enzymatic removal of carbohydrate groups from the saponins creates a pool of metabolites with an increased broad-spectrum antimicrobial activity. The evolution of this defense system benefited from both the intrinsic condensation abilities of the enzyme and the bioactivity properties of its substrates. We dub this two-component system the saponin bomb, in analogy with the mustard oil and cyanide bombs, commonly used to describe the renowned ß-glucosidase-dependent defense systems for glucosinolates and cyanogenic glucosides.

Resolving drug selection and migration in an inbred South American Plasmodium falciparum population with identity-by-descent analysis.

The human malaria parasite Plasmodium falciparum is globally widespread, but its prevalence varies significantly between and even within countries. Most population genetic studies in P. falciparum focus on regions of high transmission where parasite populations are large and genetically diverse, such as sub-Saharan Africa. Understanding population dynamics in low transmission settings, however, is of particular importance as these are often where drug resistance first evolves. Here, we use the Pacific Coast of Colombia and Ecuador as a model for understanding the population structure and evolution of Plasmodium parasites in small populations harboring less genetic diversity. The combination of low transmission and a high proportion of monoclonal infections means there are few outcrossing events and clonal lineages persist for long periods of time. Yet despite this, the population is evolutionarily labile and has successfully adapted to changes in drug regime. Using newly sequenced whole genomes, we measure relatedness between 166 parasites, calculated as identity by descent (IBD), and find 17 distinct but highly related clonal lineages, six of which have persisted in the region for at least a decade. This inbred population structure is captured in more detail with IBD than with other common population structure analyses like PCA, ADMIXTURE, and distance-based trees. We additionally use patterns of intra-chromosomal IBD and an analysis of haplotypic variation to explore past selection events in the region. Two genes associated with chloroquine resistance, crt and aat1, show evidence of hard selective sweeps, while selection appears soft and/or incomplete at three other key resistance loci (dhps, mdr1, and dhfr). Overall, this work highlights the strength of IBD analyses for studying parasite population structure and resistance evolution in regions of low transmission, and emphasizes that drug resistance can evolve and spread in small populations, as will occur in any region nearing malaria elimination.

Genomic epidemiological models describe pathogen evolution across fitness valleys.

Genomics is fundamentally changing epidemiological research. However, systematically exploring hypotheses in pathogen evolution requires new modeling tools. Models intertwining pathogen epidemiology and genomic evolution can help understand processes such as the emergence of novel pathogen genotypes with higher transmissibility or resistance to treatment. In this work, we present Opqua, a flexible simulation framework that explicitly links epidemiology to sequence evolution and selection. We use Opqua to study determinants of evolution across fitness valleys. We confirm that competition can limit evolution in high-transmission environments and find that low transmission, host mobility, and complex pathogen life cycles facilitate reaching new adaptive peaks through population bottlenecks and decoupling of selective pressures. The results show the potential of genomic epidemiological modeling as a tool in infectious disease research.

An engineered live biotherapeutic for the prevention of antibiotic-induced dysbiosis.

Antibiotic-induced alterations in the gut microbiota are implicated in many metabolic and inflammatory diseases, increase the risk of secondary infections and contribute to the emergence of antimicrobial resistance. Here we report the design and in vivo performance of an engineered strain of Lactococcus lactis that altruistically degrades the widely used broad-spectrum antibiotics ß-lactams (which disrupt commensal bacteria in the gut) through the secretion and extracellular assembly of a heterodimeric ß-lactamase. The engineered ß-lactamase-expression system does not confer ß-lactam resistance to the producer cell, and is encoded via a genetically unlinked two-gene biosynthesis strategy that is not susceptible to dissemination by horizontal gene transfer. In a mouse model of parenteral ampicillin treatment, oral supplementation with the engineered live biotherapeutic minimized gut dysbiosis without affecting the ampicillin concentration in serum, precluded the enrichment of antimicrobial resistance genes in the gut microbiome and prevented the loss of colonization resistance against Clostridioides difficile. Engineered live biotherapeutics that safely degrade antibiotics in the gut may represent a suitable strategy for the prevention of dysbiosis and its associated pathologies.

GeneTargeter: Automated In Silico Design for Genome Editing in the Malaria Parasite, Plasmodium falciparum.

Functional characterization of the multitude of poorly described proteins in the human malarial pathogen, Plasmodium falciparum, requires tools to enable genome-scale perturbation studies. Here, we present GeneTargeter (genetargeter.mit.edu), a software tool for automating the design of homology-directed repair donor vectors to achieve gene knockouts, conditional knockdowns, and epitope tagging of P. falciparum genes. We demonstrate GeneTargeter-facilitated genome-scale design of six different types of knockout and conditional knockdown constructs for the P. falciparum genome and validate the computational design process experimentally with successful donor vector assembly and transfection. The software's modular nature accommodates arbitrary destination vectors and allows customizable designs that extend the genome manipulation outcomes attainable in Plasmodium and other organisms.

Declines in rodent abundance and diversity track regional climate variability in North American drylands.

Regional long-term monitoring can enhance the detection of biodiversity declines associated with climate change, improving future projections by reducing reliance on space-for-time substitution and increasing scalability. Rodents are diverse and important consumers in drylands, regions defined by the scarcity of water that cover 45% of Earth's land surface and face increasingly drier and more variable climates. We analyzed abundance data for 22 rodent species across grassland, shrubland, ecotone, and woodland ecosystems in the southwestern USA. Two time series (1995-2006 and 2004-2013) coincided with phases of the Pacific Decadal Oscillation (PDO), which influences drought in southwestern North America. Regionally, rodent species diversity declined 20%-35%, with greater losses during the later time period. Abundance also declined regionally, but only during 2004-2013, with losses of 5% of animals captured. During the first time series (wetter climate), plant productivity outranked climate variables as the best regional predictor of rodent abundance for 70% of taxa, whereas during the second period (drier climate), climate best explained variation in abundance for 60% of taxa. Temporal dynamics in diversity and abundance differed spatially among ecosystems, with the largest declines in woodlands and shrublands of central New Mexico and Colorado. Which species were winners or losers under increasing drought and amplified interannual variability in drought depended on ecosystem type and the phase of the PDO. Fewer taxa were significant winners (18%) than losers (30%) under drought, but the identities of winners and losers differed among ecosystems for 70% of taxa. Our results suggest that the sensitivities of rodent species to climate contributed to regional declines in diversity and abundance during 1995-2013. Whether these changes portend future declines in drought-sensitive consumers in the southwestern USA will depend on the climate during the next major PDO cycle.

dCas9 regulator to neutralize competition in CRISPRi circuits.

CRISPRi-mediated gene regulation allows simultaneous control of many genes. However, highly specific sgRNA-promoter binding is, alone, insufficient to achieve independent transcriptional regulation of multiple targets. Indeed, due to competition for dCas9, the repression ability of one sgRNA changes significantly when another sgRNA becomes expressed. To solve this problem and decouple sgRNA-mediated regulatory paths, we create a dCas9 concentration regulator that implements negative feedback on dCas9 level. This allows any sgRNA to maintain an approximately constant dose-response curve, independent of other sgRNAs. We demonstrate the regulator performance on both single-stage and layered CRISPRi-based genetic circuits, zeroing competition effects of up to 15-fold changes in circuit I/O response encountered without the dCas9 regulator. The dCas9 regulator decouples sgRNA-mediated regulatory paths, enabling concurrent and independent regulation of multiple genes. This allows predictable composition of CRISPRi-based genetic modules, which is essential in the design of larger scale synthetic genetic circuits.

Isolate-Specific Effect of Entomopathogenic Endophytic Fungi on Population Growth of Two-Spotted Spider Mite (Tetranychus urticae Koch) and Levels of Steroidal Glycoalkaloids in Tomato.

Entomopathogenic fungi (EPF) can be experimentally established in several plant species as endophytes. Ecological effects of EPF inoculations on plant growth and plant-herbivore interactions have been demonstrated, potentially by altering plant physiological responses. However, the role of these responses in plant-fungus-herbivore tripartite interactions has not been well elucidated. Steroidal glycoalkaloids (SGAs) are plant specialized metabolites with bioactive properties against arthropod herbivores. Here, the effects of seed treatments by three EPF isolates, representing Beauveria bassiana, Metarhizium brunneum, and M. robertsii, on population growth of two-spotted spider mites (Tetranychus urticae Koch) were evaluated on tomato (Solanum lycopersicum). The levels of two SGAs, α-tomatine and dehydrotomatine, were determined in tomato leaves by LC-MS with and without T. urticae infestations after EPF inoculations. Interestingly, the population growth of T. urticae was significantly highest with M. brunneum and lowest with M. robertsii and B. bassiana at 15 days after infestation. Overall there was a significant negative correlation between SGAs content and the number of T. urticae. The levels of SGAs were significantly induced by T. urticae presence in all treatments, while only M. robertsii showed significantly higher levels of SGAs than M. brunneum and control in one of two experiments. Contrastingly, the effects on SGAs accumulation and population growth of T. urticae did not directly correlate with EPF endophytic colonization patterns of the inoculated plants. This study suggests a link between ecological effects and physiological responses mediated by EPF inoculations and T. urticae infestation with potential implications for plant protection.

Validez del hallazgo de nódulos en la colonoscopia para el diagnóstico de hiperplasia nodular linfoide en niños / Validity of nodules detected at colonoscopy for the diagnosis of nodular lymphoid hyperplasia in children

Resumen Introducción: la hiperplasia nodular linfoide del colon se define como > 10 nódulos linfoides visibles en colonoscopia. No existen estudios de su validez al compararlo con la histopatología. Objetivos: determinar la validez del hallazgo de nódulos en colonoscopia para el diagnóstico de hiperplasia nodular linfoide. Material y métodos: estudio prospectivo de prueba diagnóstica. Se incluyeron colonoscopias realizadas consecutivamente de 2014 al 2018 con equipos Olympus PCFQ150AI y GIFXP150N con obtención de biopsias. El criterio endoscópico fue la presencia de > 10 nódulos de 2 a 10 mm y el criterio histológico fue hiperplasia de folículos linfoides y mantos de linfocitos en lámina propia o submucosa. Los datos se analizaron en Epidat3.1. Se obtuvo la sensibilidad (S), especificidad (E), valor predictivo positivo (VPP) y negativo (VPN), y coeficientes de probabilidad positivo (LR+) y negativo (LR-) con sus intervalos de confianza. Resultados: se incluyeron 327 colonoscopias, la mediana de edad fue de 84 meses. La principal indicación para la colonoscopia fue sangrado digestivo bajo (38,8%). El hallazgo de nódulos se encontró en el 21% y el sitio de mayor frecuencia fue el colon total (46%), mientras que por histopatología se encontró hiperplasia nodular linfoide en el 38%. El hallazgo de nódulos obtuvo una S de 32% (intervalo de confianza [IC] del 95%: 24-140), E de 84% (IC 95%: 79-89), VPP de 56% (IC 95%: 44-68), VPN de 67% (IC 95%: 61-72), LR+ de 2,04 (IC 95%: 1,4-3) y LR- de 0,8 (IC 95%: 0,8-0,9). Conclusiones: la validez diagnóstica del hallazgo de nódulos en colonoscopia para hiperplasia nodular linfoide es pobre, por lo que la toma de biopsia debe recomendarse siempre.

Abstract Introduction: Nodular lymphoid hyperplasia of the colon is characterized by the presence of >10 lymphoid nodules visible in colonoscopy. There are no studies that confirm their validity when compared with histopathology. Objective: To determine the validity of nodules detected at colonoscopy for the diagnosis of nodular lymphoid hyperplasia in children. Materials and methods: Prospective study of diagnostic test accuracy. Colonoscopies performed consecutively from 2014 to 2018 using Olympus PCFQ150AI and GIFXP150N biopsy machines were included. The endoscopic criterion was the presence of >10 nodules from 2 to 10mm of diameter, while the histological criterion was presence of follicular lymphoid hyperplasia and lymphocyte mantles in lamina propia or submucosa. Data were analyzed in Epidat3.1. Sensitivity (SE), specificity (SP), positive predictive value (PPV), negative predictive value (NPV), positive likelihood ratio (LR+) and negative likelihood ratio (LR-) were obtained with their corresponding confidence intervals. Results: 327 colonoscopies were included; the median age was 84 months. The main indication for colonoscopy was lower gastrointestinal bleeding (38.8%). Nodules were found in 21% of the patients, predominantly throughout the whole colon (46%), whereas histopathology found nodular lymphoid hyperplasia in 38%. SE for the finding of nodules was 32% (95% confidence interval [CI]: 24-140), SP was 84% (95% CI: 79-89), PPV was 56% (95% CI: 44-68), NPV was 67% (95% CI: 61-72), LR+ was 2.04 (95% CI: 1.4-3) and LR- was 0.8 (95% CI: 0.8-0.9). Conclusions: The validity of the presence of nodules on colonoscopy for the diagnosis of nodular lymphoid hyperplasia is poor, so biopsy should always be performed.

Analysis of wild tomato introgression lines elucidates the genetic basis of transcriptome and metabolome variation underlying fruit traits and pathogen response.

Wild tomato species represent a rich gene pool for numerous desirable traits lost during domestication. Here, we exploited an introgression population representing wild desert-adapted species and a domesticated cultivar to establish the genetic basis of gene expression and chemical variation accompanying the transfer of wild-species-associated fruit traits. Transcriptome and metabolome analysis of 580 lines coupled to pathogen sensitivity assays resulted in the identification of genomic loci associated with levels of hundreds of transcripts and metabolites. These associations occurred in hotspots representing coordinated perturbation of metabolic pathways and ripening-related processes. Here, we identify components of the Solanum alkaloid pathway, as well as genes and metabolites involved in pathogen defense and linking fungal resistance with changes in the fruit ripening regulatory network. Our results outline a framework for understanding metabolism and pathogen resistance during tomato fruit ripening and provide insights into key fruit quality traits.

Pathways to defense metabolites and evading fruit bitterness in genus Solanum evolved through 2-oxoglutarate-dependent dioxygenases.

The genus Solanum comprises three food crops (potato, tomato, and eggplant), which are consumed on daily basis worldwide and also producers of notorious anti-nutritional steroidal glycoalkaloids (SGAs). Hydroxylated SGAs (i.e. leptinines) serve as precursors for leptines that act as defenses against Colorado Potato Beetle (Leptinotarsa decemlineata Say), an important pest of potato worldwide. However, SGA hydroxylating enzymes remain unknown. Here, we discover that 2-OXOGLUTARATE-DEPENDENT-DIOXYGENASE (2-ODD) enzymes catalyze SGA-hydroxylation across various Solanum species. In contrast to cultivated potato, Solanum chacoense, a widespread wild potato species, has evolved a 2-ODD enzyme leading to the formation of leptinines. Furthermore, we find a related 2-ODD in tomato that catalyzes the hydroxylation of the bitter α-tomatine to hydroxytomatine, the first committed step in the chemical shift towards downstream ripening-associated non-bitter SGAs (e.g. esculeoside A). This 2-ODD enzyme prevents bitterness in ripe tomato fruit consumed today which otherwise would remain unpleasant in taste and more toxic.

Estudio Descriptivo: Perfil Epidemiológico en la Unidad de Cuidados Intensivos Pediátricos del Hospital Vicente Corral Moscoso, 2015 - 2016 / Descriptive Research: Epidemiological Profile of the Pediatric Intensive Care Unit at Vicente Corral Moscoso Hospital, 2015 - 2016

INTRODUCCIÓN: La medicina intensiva pediátrica es una rama relativamente nueva dentro de la pediatría. En los últimos años gracias al desarrollo tecnológico y los avances en tratamientos médi-cos, se ha logrado disminuir la morbilidad y mortalidad en estas áreas críticas; sin embargo, existen complicaciones asociadas a la estancia prolongada. La mortalidad se ha correlacionado de forma inversa con la disponibilidad de cuidados intensivos, número de intensivistas pediátricos, número de camas y número de centros pediátricos de especialidad. El objetivo de este estudio fue determi-nar el perfil epidemiológico clínico de los pacientes ingresados en la Unidad de Cuidados Intensivos Pediátricos del Hospital Vicente Corral Moscoso, durante el periodo 2015-2016. MATERIALES Y MÉTODOS: Estudio descriptivo retrospectivo, el universo se constituyó de 386 pacientes ingresados en la unidad de cuidados intensivos pediátricos en los años 2015 y 2016, la información fue recolectada de las respectivas historias clínicas. Las variables estudiadas fueron: edad, sexo, mes y año de ingreso, diagnóstico, procedimientos utilizados, mortalidad y ocupación de camas. RESULTADOS:Se incluyeron 386 pacientes, 55.2% fueron varones. El promedio de edad fue 5.3 años. Las principales causas de ingreso fueron neumonía, trauma cráneo-encefálico, estatus epi-léptico y sepsis. El 50% recibió ventilación mecánica. La tasa de mortalidad fue de 17% y se asoció con falta de procedimiento quirúrgico (p= 0.026); nutrición parenteral (p= 0.023); inotrópicos y ven-tilación mecánica (p= <0.001). La estancia hospitalaria promedio fue de 6.2 días. El porcentaje de ocupación de camas fue del 92.6%. CONCLUSIONES: Con el fin de satisfacer las necesidades del creciente número de niños susceptibles de recibir cuidados críticos, cada país debería obtener datos epidemiológicos sobre de la prevalen-cia de las enfermedades que requieren cuidados intensivos pediátricos para implementar su infraes-tructura y ejecutar programas preventivos(AU)

BACKGROUND: Pediatric intensive medicine is a relatively new branch within pediatrics. In recent years, with the technological development and improvement in medical treatments, morbidity and mortality have been reduced; however, there are complications associated with prolonged hospitalization. Mortality has been inversely correlated with the availability of intensive care, number of pediatric intensivists, number of beds and number of specialty pediatric centers. The aim of this study was to determine the clinical epidemiological profile of patients admitted to the Pediatric Intensive Care Unit of the Hospital Vicente Corral Moscoso, during the period 2015 - 2016. METHODS: A retrospective descriptive study was performed; the universe included 386 patients admitted to the pediatric intensive care unit in 2015 and 2016; the information was collected from the respective medical records. The variables studied were: age, sex, month and year of admission, diagnosis, and procedures, mor-tality and bed occupancy. RESULTS: 386 patients were included, 55.2% were male. The average age was 5.3 years. The main causes of admission were pneumonia, cranioencephalic trauma, status epilepticus and sepsis. 50% received mecha-nical ventilation. The mortality rate was 17% and was associated with lack of surgical procedure (p= 0.026); parenteral nutrition (p= 0.023); inotropes and mechanical ventilation (p= <0.001). The average hospital stay was 6.2 days; the percentage of bed occupancy was 92.6%. CONCLUSIONS: In order to meet the needs of the growing number of children susceptible to critical care, each country should obtain epidemiological data on the prevalence of diseases requiring intensive pediatric care to implement its infrastructure and execute preventive programs.(AU)

Host Resistance, Genomics and Population Dynamics in a Salmonella Enteritidis and Phage System.

Bacteriophages represent an alternative solution to control bacterial infections. When interacting, bacteria and phage can evolve, and this relationship is described as antagonistic coevolution, a pattern that does not fit all models. In this work, the model consisted of a microcosm of Salmonella enterica serovar Enteritidis and φSan23 phage. Samples were taken for 12 days every 48 h. Bacteria and phage samples were collected; and isolated bacteria from each time point were challenged against phages from previous, contemporary, and subsequent time points. The phage plaque tests, with the genomics analyses, showed a mutational asymmetry dynamic in favor of the bacteria instead of antagonistic coevolution. This is important for future phage-therapy applications, so we decided to explore the population dynamics of Salmonella under different conditions: pressure of one phage, a combination of phages, and phages plus an antibiotic. The data from cultures with single and multiple phages, and antibiotics, were used to create a mathematical model exploring population and resistance dynamics of Salmonella under these treatments, suggesting a nonlethal, growth-inhibiting antibiotic may decrease resistance to phage-therapy cocktails. These data provide a deep insight into bacterial dynamics under different conditions and serve as additional criteria to select phages and antibiotics for phage-therapy.