Differences between Myeloschisis and Myelomeningocele in patients undergoing prenatal repair of Open Spina Bifida.

INTRODUCTION: Open spina bifida (OSB) manifests as myelomeningocele (MMC) or myeloschisis (MS). Both lesions theoretically leak cerebrospinal fluid (CSF) and produce different degrees of Chiari II malformation (CHMII). However, it is not entirely clear whether these forms of OSB have different clinical manifestations. This study aimed to evaluate the clinical and/or radiological differences between myeloschisis and myelomeningocele in patients who underwent prenatal OSB repair. METHODS: A total of 71 prenatal repairs were performed with the open technique at the Public Hospital of Rancagua, Chile, between 2012 and 2022. We performed follow-up MRI imaging of fetuses that qualified for prenatal OSB repair surgery. We examined the correlations between various anthropomorphic measurements and clinical and imaging variables, such as the type of lesion and dimensions such as ventricle atrium diameter, degree of severity of CHMII, need for CSF shunt at 12 months, and walking at 30 months. RESULTS: This study included 71 fetuses with OSB for which 38 MRI examinations were analyzed; 61% (43/71) of lesions were MMC and 39% (28/71) were MS. Grade 3 (severe) CHMII were found in 80% (12/15) of MS and 43% (10/23) of MMC (p<0.05). Fetuses with an atrial diameter less than 13.48 mm had a lower probability of requiring a CSF shunt at 12 months (p<0.05). MMC was associated with a higher frequency of clubfoot at birth (p<0.05), whereas MS was significantly associated with more severe CHMII (p<0.05). Although the correlations were not significant, we observed clear trends that more children with MS required shunts at 12 months and could walk at 30 months compared to children with MMC. CONCLUSIONS: MS and MMC are distinct subtypes of OSB. Further studies of larger cohorts that include biomolecular and histological analysis are required to better understand differences between these lesions. This study may enable healthcare providers to better advise parents and prepare healthcare teams earlier for the management of patients undergoing prenatal repair of OSB.

Modeling the Impact of Agricultural Mitigation Measures on the Spread of Sharka Disease in Sweet Cherry Orchards.

Sharka is a disease affecting stone fruit trees. It is caused by the Plum pox virus (PPV), with Myzus persicae being one of the most efficient aphid species in transmitting it within and among Prunus orchards. Other agricultural management strategies are also responsible for the spread of disease among trees, such as grafting and pruning. We present a mathematical model of impulsive differential equations to represent the dynamics of Sharka disease in the tree and vector population. We consider three transmission routes: grafting, pruning, and through aphid vectors. Grafting, pruning, and vector control occur as pulses at specific instants. Within the model, human risk perception towards disease influences these agricultural management strategies. Model results show that grafting with infected biological material has a significant impact on the spread of the disease. In addition, detecting infectious symptomatic and asymptomatic trees in the short term is critical to reduce disease spread. Furthermore, vector control to prevent aphid movement between trees is crucial for disease mitigation, as well as implementing awareness campaigns for Sharka disease in agricultural communities that provide a long-term impact on responsible pruning, grafting, and vector control.

Mathematical Model of the Spread of Hantavirus Infection.

A mathematical epidemiological model incorporating the mobility of rodents and human groups among zones of less or major contact between them is presented. The hantavirus infection dynamics is expressed using a model type SEIR (Susceptible-Exposed-Infectious-Removed), which incorporates the displacement of the rodent and the human, between the urban and rural sector, the latter being subdivided in populated and non-populated. The results show the impact that rodent or human displacement may have on the propagation of hantavirus infection. Human mobility is more significant than rodents in increasing the number of hantavirus infection cases. The results found may be used as a reference by the health authorities to develop more specific campaigns on the territorial dynamics of the rodent, attend to the mobility of humans in these territories, mainly agricultural and forestry workers, and strengthen control-prevention actions in the community, to prevent future outbreaks that are fatal.

Collateral Effects of Insecticide-Treated Nets on Human and Environmental Safety in an Epidemiological Model for Malaria with Human Risk Perception.

Malaria remains a major health problem in many parts of the world, including Sub-Saharan Africa. Insecticide-treated nets, in combination with other control measures, have been effective in reducing malaria incidence over the past two decades. Nevertheless, there are concerns about improper handling and misuse of nets, producing possible health effects from intoxication and collateral environmental damage. The latter is caused, for instance, from artisanal fishing. We formulate a model of impulsive differential equations to describe the interplay between malaria dynamics, human intoxication, and ecosystem damage; affected by human awareness to these risks and levels of net usage. Our results show that an increase in mosquito net coverage reduces malaria prevalence and increases human intoxications. In addition, a high net coverage significantly reduces the risk perception to disease, naturally increases the awareness for intoxications from net handling, and scarcely increases the risk perception to collateral damage from net fishing. According to our model, campaigns aiming at reducing disease prevalence or intoxications are much more successful than those creating awareness to ecosystem damage. Furthermore, we can observe from our results that introducing closed fishing periods reduces environmental damage more significantly than strategies directed towards increasing the risk perception for net fishing.

Health Effects of Pesticide Exposure in Latin American and the Caribbean Populations: A Scoping Review.

BACKGROUND: Multiple epidemiological studies have shown that exposure to pesticides is associated with adverse health outcomes. However, the literature on pesticide-related health effects in the Latin American and the Caribbean (LAC) region, an area of intensive agricultural and residential pesticide use, is sparse. We conducted a scoping review to describe the current state of research on the health effects of pesticide exposure in LAC populations with the goal of identifying knowledge gaps and research capacity building needs. METHODS: We searched PubMed and SciELO for epidemiological studies on pesticide exposure and human health in LAC populations published between January 2007 and December 2021. We identified 233 publications from 16 countries that met our inclusion criteria and grouped them by health outcome (genotoxicity, neurobehavioral outcomes, placental outcomes and teratogenicity, cancer, thyroid function, reproductive outcomes, birth outcomes and child growth, and others). RESULTS: Most published studies were conducted in Brazil (37%, n=88) and Mexico (20%, n=46), were cross-sectional in design (72%, n=167), and focused on farmworkers (45%, n=105) or children (21%, n=48). The most frequently studied health effects included genotoxicity (24%, n=62) and neurobehavioral outcomes (21%, n=54), and organophosphate (OP) pesticides were the most frequently examined (26%, n=81). Forty-seven percent (n=112) of the studies relied only on indirect pesticide exposure assessment methods. Exposure to OP pesticides, carbamates, or to multiple pesticide classes was consistently associated with markers of genotoxicity and adverse neurobehavioral outcomes, particularly among children and farmworkers. DISCUSSION: Our scoping review provides some evidence that exposure to pesticides may adversely impact the health of LAC populations, but methodological limitations and inconsistencies undermine the strength of the conclusions. It is critical to increase capacity building, integrate research initiatives, and conduct more rigorous epidemiological studies in the region to address these limitations, better inform public health surveillance systems, and maximize the impact of research on public policies. https://doi.org/10.1289/EHP9934.

Análisis de modelos tipo SEIR utilizados en los inicios de la pandemia COVID-19 reportados en revistas de alto impacto / Analysis of SEIR-type models used at the beginning of COVID-19 pandemic reported in high-impact journals

Introducción El modelo matemático-epidemiológico Susceptible-Expuesto-Infectado-Recuperado (SEIR) ha sido empleado exhaustivamente en el contexto actual de la pandemia COVID-19. En sus inicios de una manera prevalente, donde se buscaba predecir la carga hospitalaria y evaluar las medidas sanitarias para contener su propagación. En este sentido, se han evidenciado fallas en las predicciones de los primeros modelos publicados. Se considera necesario evaluar las diferencias en el planteamiento y verificación de los modelos. Objetivos Categorizar las publicaciones científicas de revistas de alto impacto que propusieron modelos tipo SEIR para modelar la pandemia COVID-19 en sus inicios. Métodos Realizamos una revisión sistemática de los artículos publicados en revistas indexadas en , de primer cuartil y con factor de impacto mayor que dos, que cumplían con los criterios de selección e inclusión siguiendo los estándares PRISMA-ScR. Incluimos un total de 32 artículos que fueron evaluados según características demográficas como el mes de recepción y publicación, el país de origen de la información, la materia temática de la revista, y las características del modelamiento como la presencia de compartimentos adicionales, análisis gráfico, planteamiento de modelo conceptual, interpretación del número reproductivo básico y estimación de los parámetros empleados. Resultados Los artículos publicados en revistas del área médica y salud fueron predominantes en los meses de febrero a julio de 2020. Estos artículos emplearon con mayor frecuencia datos procedentes de China y se centraron mayoritariamente en modelos SEIR o con compartimento de cuarentena completa. Los artículos publicados en revistas del área matemática fueron predominantes en el período de agosto a diciembre de 2020, y emplearon datos procedentes de diversas regiones del mundo, considerando mayor diversidad de compartimentos como pacientes asintomáticos o en cuarentena parcial o completa. Conclusiones Los artículos analizados en su mayoría emplean modelos tipo SEIR ampliados con compartimentos adicionales. Existen discrepancias en la amplitud y calidad metodológica de los artículos publicados, según la materia temática de la revista. Se recomienda la unificación de criterios de calidad para la descripción de los modelos en cualquier revista.

Introduction The Susceptible-Exposed-Infected-Recovered (SEIR) mathematical-epidemiological model has been exhaustively used since de beggining of the COVID-19 pandemic. These models intended to predict hospital burden and evaluate health measures to contain its spread. In this sense, flaws have been evidenced in the predictions of the first published models. It is considered necessary to evaluate the differences in the approach and verification of the models. Objectives We carried out a systematic review of the articles published in journals indexed in the Web of Science, of the first quartile and with an impact factor greater than two, that met the selection and inclusion criteria following the PRISMA-ScR standards. We included a total of 32 articles, which were evaluated according to demographic characteristics such as the month of receipt and publication, the country of origin of the information, the subject matter of the journal, and the characteristics of the modeling such as the presence of additional compartments, graphical analysis, conceptual model approach, interpretation of the basic reproductive number, and estimation of parameters. Methods Articles published in medical and health journals were predominant from February to July 2020. These articles most frequently used data from China and mostly focused on SEIR or full quarantine compartment models. The articles published in journals in mathematics were predominant from August to December 2020. Models used data from different world regions, considering a greater diversity of compartments such as asymptomatic patients or partial or complete quarantine. Results The articles analyzed mostly use SEIR-type models expanded with additional compartments. There are discrepancies in the breadth and methodological quality of the articles published according to the journal's subject matter. The unification of quality criteria for describing the models in any journal is recommended. Conclusions The articles analyzed mostly use SEIR-type models expanded with additional compartments. There are discrepancies in the breadth and methodological quality of the articles published according to the journal's subject matter. The unification of quality criteria for describing the models in any journal is recommended.

Effects of human mobility and behavior on disease transmission in a COVID-19 mathematical model.

Human interactions and perceptions about health risk are essential to understand the evolution over the course of a pandemic. We present a Susceptible-Exposed-Asymptomatic-Infectious-Recovered-Susceptible mathematical model with quarantine and social-distance-dependent transmission rates, to study COVID-19 dynamics. Human activities are split across different location settings: home, work, school, and elsewhere. Individuals move from home to the other locations at rates dependent on their epidemiological conditions and maintain a social distancing behavior, which varies with their location. We perform simulations and analyze how distinct social behaviors and restrictive measures affect the dynamic of the disease within a population. The model proposed in this study revealed that the main focus on the transmission of COVID-19 is attributed to the "home" location setting, which is understood as family gatherings including relatives and close friends. Limiting encounters at work, school and other locations will only be effective if COVID-19 restrictions occur simultaneously at all those locations and/or contact tracing or social distancing measures are effectively and strictly implemented, especially at the home setting.

Modeling of hantavirus cardiopulmonary syndrome. / Modelamiento del síndrome cardiopulmonar por hantavirus.

Introduction: Hantavirus cardiopulmonary syndrome is an infection caused by rodents of the Bunyanvirales family towards humans. This disease in Chile is considered endemic, which has a high fatality rate. At present, some studies show the contagion between people of the Andes virus, whose locality is concentrated in Argentina and Chile. Objectives: Analyze the possibility of hantavirus transmission between humans using an SEIR-type mathematical model. Methods: An SEIR (Susceptible, Exposed, Infectious and Recovered) mathematical model to express the dynamics of hantavirus disease is proposed, including the possibility of human-to-human transmission and the perception of risk. Results: The peak of human-to-human contagion decreases by about 25% after increasing peoples perception of risk by reducing the rate of resistance to changeand increasing the speed of peoples reaction. Conclusions: It is urgent to review risk communication strategies and prevention measures in the face of this possibility of massive human-tohuman infections, in addition to strengthening research and planning the development of a vaccine to protect populations exposed to this disease with a high fatality rate.

Introducción: El síndrome cardiopulmonar por hantavirus es una enfermedad causada por un virus perteneciente al orden bunyanvirales, y transmitida hacia los humanos a través de roedores. Esta enfermedad en Chile es considerada endémica, la cual tiene una alta tasa de letalidad. En la actualidad existen estudios que evidencian el contagio entre personas del virus Andes, cuya localidad se concentra en los países de Argentina y Chile. Objetivos: Analizar la posibilidad de transmisión de hantavirus entre humanos, mediante un modelo matemático tipo SEIR. Métodos: Se plantea un modelo matemático tipo SEIR (susceptible, expuesto, infeccioso y recuperado) para expresar la dinámica de la enfermedad por hantavirus, incluyendo la posibilidad de transmisión entre humanos y la percepción del riesgo. Resultados: El máximo de contagio entre humanos disminuye cerca de 25% tras aumentar la percepción de riesgo de las personas, mediante la reducción de la tasa de resistencia al cambio y aumento la velocidad de reaccionar de las personas. Conclusiones: Es urgente revisar las estrategias de comunicación de riesgo y medidas de prevención ante esta posibilidad de contagios masivos entre humanos, además de fortalecer la investigación y proyectar el desarrollo de una vacuna para proteger las poblaciones expuestas a esta enfermedad con alta tasa de letalidad.

Modelamiento del síndrome cardiopulmonar por hantavirus / Modeling of hantavirus cardiopulmonary syndrome

INTRODUCCIÓN: El síndrome cardiopulmonar por hantavirus es una enfermedad causada por un virus perteneciente al orden bunyanvirales, y transmitida hacia los humanos a través de roedores. Esta enfermedad en Chile es considerada endémica, la cual tiene una alta tasa de letalidad. En la actualidad existen estudios que evidencian el contagio entre personas del virus Andes, cuya localidad se concentra en los países de Argentina y Chile. OBJETIVOS: Analizar la posibilidad de transmisión de hantavirus entre humanos, mediante un modelo matemático tipo SEIR. MÉTODOS: Se plantea un modelo matemático tipo SEIR (susceptible, expuesto, infeccioso y recuperado) para expresar la dinámica de la enfermedad por hantavirus, incluyendo la posibilidad de transmisión entre humanos y la percepción del riesgo. Resultados: El máximo de contagio entre humanos disminuye cerca de 25% tras aumentar la percepción de riesgo de las personas, mediante la reducción de la tasa de resistencia al cambio y aumento la velocidad de reaccionar de las personas. CONCLUSIONES: Es urgente revisar las estrategias de comunicación de riesgo y medidas de prevención ante esta posibilidad de contagios masivos entre humanos, además de fortalecer la investigación y proyectar el desarrollo de una vacuna para proteger las poblaciones expuestas a esta enfermedad con alta tasa de letalidad.

INTRODUCTION: Hantavirus cardiopulmonary syndrome is an infection caused by rodents of the Bunyanvirales family towards humans. This disease in Chile is considered endemic, which has a high fatality rate. At present, some studies show the contagion between people of the Andes virus, whose locality is concentrated in Argentina and Chile. OBJECTIVES: Analyze the possibility of hantavirus transmission between humans using an SEIR-type mathematical model. METHODS: An SEIR (Susceptible, Exposed, Infectious and Recovered) mathematical model to express the dynamics of hantavirus disease is proposed, including the possibility of human-to-human transmission and the perception of risk. RESULTS: The peak of human-to-human contagion decreases by about 25% after increasing people's perception of risk by reducing the rate of resistance to changeand increasing the speed of people's reaction. CONCLUSIONS: It is urgent to review risk communication strategies and prevention measures in the face of this possibility of massive human-tohuman infections, in addition to strengthening research and planning the development of a vaccine to protect populations exposed to this disease with a high fatality rate.

Risk Perception Influence on Vaccination Program on COVID-19 in Chile: A Mathematical Model.

The SARS-CoV-2 virus emergency prompted unprecedented safety measures, which were accepted by the population of each country to different degrees, for example, with more or less willingness to use personal protective elements (PPEs). We have developed a mathematical model of the contagion process, based on chilean data, to assess the interaction between biological factors (such as the impact of vaccination) and behavioral factors (such as the population's perception of risk). The model clearly shows that the virus spreads through three waves of contagion, the second being the most prominent, regardless of any alteration in the variables taken into account, which only affect the overall number of people infected. By considering alternative values of the risk perception variable and examining the different possible scenarios, we have also found that the less reaction to change the population has (and the lower the disposition to use PPEs), the higher the waves of contagion and the death toll are.

The emergence of Dirofilaria repens in a non-endemic area influenced by climate change: dynamics of transmission using a mathematical model.

Dirofilaria repens is a nematode affecting domestic and wild canids, transmitted by several species of mosquitoes of different genera. It usually causes a non-pathogenic subcutaneous infection in dogs and is the principal agent of human dirofilariasis in the Old World. The geographic distribution of D. repens is changing rapidly, and several factors contribute to the spread of the infection to non-endemic areas. A mathematical model for transmission of Dirofilaria spp. was built, using a system of ordinary differential equations that consider the interactions between reservoirs, vectors, and humans. The transmission simulations of D. repens were carried out considering a projection in time, with intervals of 15 and 100 years. For the dynamics of the vector, seasonal variations were presented as series with quarter periodicity during the year. The results of the simulations highlight the peak of contagions in the reservoir and in humans, a product of the action of the vector when it remains active throughout the year. A 300% infection increase in the reservoir was observed during the first decade and remains present in the population with a representative number of cases. When the vector maintains its density and infectivity during the year, the incidence of the infection in humans increases. Accumulated cases amount to 45 per 100,000 inhabitants, which corresponds to a cumulative incidence of 0.05%, in 85 years. This indicates that early prevention of infection in canids would significantly reduce the disease, also reducing the number of accumulated cases of human dirofilariasis by D. repens. The interaction between the simulations generated by the model highlights the sensitivity of the epidemiological curve to the periodicity of seasonality, reaffirming the hypothesis of the probability of movement of the zoonotic disease to non-endemic areas, due to climate change.

An SIR-type epidemiological model that integrates social distancing as a dynamic law based on point prevalence and socio-behavioral factors.

Modeling human behavior within mathematical models of infectious diseases is a key component to understand and control disease spread. We present a mathematical compartmental model of Susceptible-Infectious-Removed to compare the infected curves given by four different functional forms describing the transmission rate. These depend on the distance that individuals keep on average to others in their daily lives. We assume that this distance varies according to the balance between two opposite thrives: the self-protecting reaction of individuals upon the presence of disease to increase social distancing and their necessity to return to a culturally dependent natural social distance that occurs in the absence of disease. We present simulations to compare results for different society types on point prevalence, the peak size of a first epidemic outbreak and the time of occurrence of that peak, for four different transmission rate functional forms and parameters of interest related to distancing behavior, such as: the reaction velocity of a society to change social distance during an epidemic. We observe the vulnerability to disease spread of close contact societies, and also show that certain social distancing behavior may provoke a small peak of a first epidemic outbreak, but at the expense of it occurring early after the epidemic onset, observing differences in this regard between society types. We also discuss the appearance of temporal oscillations of the four different transmission rates, their differences, and how this oscillatory behavior is impacted through social distancing; breaking the unimodality of the actives-curve produced by the classical SIR-model.

Analysis of the immune response to sciatic nerve injury identifies efferocytosis as a key mechanism of nerve debridement.

Sciatic nerve crush injury triggers sterile inflammation within the distal nerve and axotomized dorsal root ganglia (DRGs). Granulocytes and pro-inflammatory Ly6Chigh monocytes infiltrate the nerve first and rapidly give way to Ly6Cnegative inflammation-resolving macrophages. In axotomized DRGs, few hematogenous leukocytes are detected and resident macrophages acquire a ramified morphology. Single-cell RNA-sequencing of injured sciatic nerve identifies five macrophage subpopulations, repair Schwann cells, and mesenchymal precursor cells. Macrophages at the nerve crush site are molecularly distinct from macrophages associated with Wallerian degeneration. In the injured nerve, macrophages 'eat' apoptotic leukocytes, a process called efferocytosis, and thereby promote an anti-inflammatory milieu. Myeloid cells in the injured nerve, but not axotomized DRGs, strongly express receptors for the cytokine GM-CSF. In GM-CSF-deficient (Csf2-/-) mice, inflammation resolution is delayed and conditioning-lesion-induced regeneration of DRG neuron central axons is abolished. Thus, carefully orchestrated inflammation resolution in the nerve is required for conditioning-lesion-induced neurorepair.

Pesticide application, educational treatment and infectious respiratory diseases: A mechanistic model with two impulsive controls.

In this paper, we develop and analyze an SIS-type epidemiological-mathematical model of the interaction between pesticide use and infectious respiratory disease transmission for investigating the impact of pesticide intoxication on the spread of these types of diseases. We further investigate the role of educational treatment for appropriate pesticide use on the transmission dynamics. Two impulsive control events are proposed: pesticide use and educational treatment. From the proposed model, it was obtained that the rate of forgetfulness towards educational treatment is a determining factor for the reduction of intoxicated people, as well as for the reduction of costs associated with educational interventions. To get reduced intoxications, the population's fraction to which is necessary to apply the educational treatment depends on its individual effectiveness level and the educational treatments' forgetfulness rate. In addition, the turnover of agricultural workers plays a fundamental role in the dynamics of agrotoxic use, particularly in the application of educational treatment. For illustration, a flu-like disease with a basic reproductive number below the epidemic threshold of 1.0 is shown can acquire epidemic potential in a population at risk of pesticide exposure. Hence, our findings suggest that educational treatment targeting pesticide exposure is an effective tool to reduce the transmission rate of an infectious respiratory disease in a population exposed to the toxic substance.

Functional Electrical Stimulation and the Modulation of the Axon Regeneration Program.

Neural injury in mammals often leads to persistent functional deficits as spontaneous repair in the peripheral nervous system (PNS) is often incomplete, while endogenous repair mechanisms in the central nervous system (CNS) are negligible. Peripheral axotomy elicits growth-associated gene programs in sensory and motor neurons that can support reinnervation of peripheral targets given sufficient levels of debris clearance and proximity to nerve targets. In contrast, while damaged CNS circuitry can undergo a limited amount of sprouting and reorganization, this innate plasticity does not re-establish the original connectivity. The utility of novel CNS circuitry will depend on effective connectivity and appropriate training to strengthen these circuits. One method of enhancing novel circuit connectivity is through the use of electrical stimulation, which supports axon growth in both central and peripheral neurons. This review will focus on the effects of CNS and PNS electrical stimulation in activating axon growth-associated gene programs and supporting the recovery of motor and sensory circuits. Electrical stimulation-mediated neuroplasticity represents a therapeutically viable approach to support neural repair and recovery. Development of appropriate clinical strategies employing electrical stimulation will depend upon determining the underlying mechanisms of activity-dependent axon regeneration and the heterogeneity of neuronal subtype responses to stimulation.

Longitudinal exposure to pyrethroids (3-PBA and trans-DCCA) and 2,4-D herbicide in rural schoolchildren of Maule region, Chile.

BACKGROUND: Several studies showed that early exposure to pesticides affects the development and health of children. In Maule, there is previous evidence of the high exposure to organophosphate pesticides (OP) of schoolchildren. However, to date, there are no studies assessing exposure to pyrethroids and the herbicide 2,4-D. Objetive. To evaluate children's exposure to pyrethroids insecticides 3-phenoxybenzoic acid (3-PBA), trans 3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylic acid (trans-DCCA) and 2,4 dichlorophenoxyacetic acid (2,4-D) herbicides. METHOD: Longitudinal study with 48 schoolchildren from two rural schools in the Maule region, Chile. Urinary metabolites of pyrethroids 3-PBA, Trans-DCCA and 2,4-D herbicides were evaluated in 2016 and 2017. Mann-Whitney U for repeated measurements and Spearman's rho correlation tests were used for data analysis. Also, we used a system of impulsive differential equations for mathematical modeling. RESULTS: All the schoolchildren assessed had more than two pesticide urinary metabolites in both years, with the 3-PBA metabolite being the most frequent. There was an increase in concentrations of urinary 3-PBA in November 2017, compared to 2016 (from 0.69 µg/L to 1.90 µg/L). In 2016, the specific metabolites of 3-PBA were correlated with Trans-DCCA, 2,4-D, chlorpyrifos, diazinon, and para-nitrophenol. In 2017, 3-PBA was correlated with 2,4-D, and Trans-DCCA. The concentrations of 3-PBA of Chilean children were higher than studies conducted in the USA that found an association of prenatal exposure to these metabolites with cognitive difficulties. CONCLUSIONS: We found high concentrations of pyrethroid metabolites among all the schoolchildren assessed, which may impact on their health and development. These insecticides had received no attention from the scientific community in Chile, and neither from the government agencies, despite the increased use of these chemicals in recent years. This is the first study in South America that confirms the exposure to pyrethroids and herbicides through biomarkers in human population living near farm fields.

[Model for a threshold of daily rate reduction of COVID-19 cases to avoid hospital collapse in Chile]. / Modelo de umbral de reducción de tasa diaria de casos COVID-19 para evitar el colapso hospitalario en Chile.

Using a mathematical model, we explore the problem of availability versus overdemand of critical hospital processes (e.g., critical beds) in the face of a steady epidemic expansion such as is occurring from the COVID-19 pandemic. In connection with the statistics of new cases per day, and the assumption of maximum quota, the dynamics associated with the variables number of hospitalized persons (critical occupants) and mortality in the system are explored. A parametric threshold condition is obtained, which involves a parameter associated with the minimum daily effort for not collapsing the system. To exemplify, we include some simulations for the case of Chile, based on a parameter of effort to be sustained with the purpose of lowering the daily infection rate.

Mediante un modelo matemático este trabajo explora la problemática de la disponibilidad versus sobredemanda de procesos críticos hospitalarias (por ejemplo, camas críticas) ante una fuerte expansión epidémica como la que está ocurriendo como consecuencia de la pandemia de COVID-19. En conexión con la estadística de nuevos casos diarios y el supuesto de cupo máximo, exploramos la dinámica asociada a las variables número de hospitalizados (ocupantes críticos) y mortalidad en el sistema. Obtenemos una condición paramétrica umbral que involucra un parámetro asociado al esfuerzo mínimo diario para el no colapso del sistema. En orden a ejemplificar, incluimos algunas simulaciones para el caso de Chile, en función de un parámetro de esfuerzo a sostener para bajar la tasa de infección diaria.

Number of COVID-19 cases in Chile at 120 days with data at 21/03/2020 and threshold of daily effort to flatten the epi-curve. / Número de casos COVID-19 en Chile a 120 días con datos al 21/03/2020 y umbral del esfuerzo diario para aplanar la epi-curva.

We present a straightforward projection with data up to 21/03/2020 of the evolution of the number of COVID-19 cases per day in Chile using data from the Ministry of Health. Assuming an arithmetical growth in the second variation of the data, we present a cubic adjustment model in which we estimate over 100 000 cases at 120 days consistent with the data recorded to date. Furthermore, we use an exponential total case model to represent (using a parameter) the daily effort to reduce a high initial daily growth rate. We simulate this model with different numerical scenarios of feasibility and desired future prevalence.

Realizamos una prospectiva básica, con datos al 21/03/2020 de la evolución del número de casos COVID-19 diarios en Chile con datos del Ministerio de Salud. Asumiendo un crecimiento aritmético en la segunda variación de los datos, se presenta un modelo de ajuste cúbico que estima en más de 100 mil casos a 120 días y que es consistente con los datos registrados a la fecha. Además, se interviene un modelo de casos totales exponencial, para representar en él (mediante un parámetro) el esfuerzo diario por rebajar una elevada primera tasa de crecimiento diario. Este modelo se simula con distinto escenarios numéricos de factibilidad y prevalencia futura deseada.

Estudio CURIE-2017: Nociones de los estudiantes del internado rotativo de medicina del Hospital Carlos Andrade Marín (Quito) con respecto al uso y aplicación de estudios imagenológicos / CURIE-2017 Study: Notions of the students of the rotating medical internship of the Carlos Andrade Marín Hospital (Quito) regarding the use and application of general imaging studies

La solicitud inadecuada de estudios médicos basados en imágenes es un problema en Ecuador y otros países. El estudio se realizó con el objetivo de establecer el nivel de conocimientos de 125 internos rotativos de un hospital de Quito, procedentes de varias universidades locales, en el uso de estudios imagenológicos. Ellos tuvieron en general un bajo desempeño en la prueba de conocimientos, por lo que se recomienda instaurar el uso de criterios más apropiados en la enseñanza de radiología en las universidades.

Wrong application of medical image studies is an issue in Ecuador and other countries. This study was done to stablish the level of knowledge on image studies of 125 fellows from several local universities working at a hospital in Quito. The results show low performance in the knowledge test, therefore recomendation is to establish better teaching criteria on radiology subject at Universities.