Resumen: Las tecnologías “ómicas” son herramientas novedosas que facilitan el estudio de las comunidades microbianas de distintos ecosistemas, particularmente de la costra biológica del suelo, también llamada biocostra. Entre estas tecnologías se encuentran la genómica, transcriptómica, proteómica, metabolómica y metagenómica, que son utilizadas para analizar la diversidad y las funciones que llevan a cabo los microorganismos a través del estudio de sus biomoléculas y vías metabólicas. Entre los microorganismos que habitan la biocostra destacan las cianobacterias, las cuales son un grupo de bacterias fototróficas encargadas de realizar procesos importantes en el suelo, tal como la fijación de nitrógeno atmosférico, carbono orgánico, síntesis de clorofila y ficobilinas, así como la producción de exopolisacáridos para mejorar la estabilidad y fertilidad del suelo. Por lo tanto, el objetivo de la presente revisión es el de explorar la diversidad y la función que desempeñan estas comunidades microbianas en la biocostra, particularmente las cianobacterias, destacando los estudios realizados mediante el uso de las tecnologías ómicas. El conocimiento generado en los últimos años a través de las tecnologías ómicas ha demostrado la limitada cobertura que presentan las técnicas moleculares tradicionales, resultando en una subestimación de la diversidad real de las comunidades microbianas. Además, se ha mejorado la comprensión de los procesos ecológicos desarrollados por los microorganismos en beneficio de la biocostra, así como las capacidades funcionales individuales y colectivas, las cuales servirán como línea base para proponer estrategias importantes que solucionen la problemática de la degradación de los suelos.

Summary: The "omics" technologies are novel tools that facilitate the study of microbial communities in different ecosystems, particularly the biological soil crust, also called biocrust. These technologies include genomics, transcriptomics, proteomics, metabolomics, and metagenomics, which are used to analyze the diversity and functions carried out by microorganisms through the study of their biomolecules and metabolic pathways. Among the microorganisms that inhabit the biocrust are the cyanobacteria, which are a group of phototrophic bacteria responsible for important processes in the soil, such as the fixation of atmospheric nitrogen, organic carbon, chlorophyll and phycobilin synthesis, as well as the production of exopolysaccharides to improve soil stability and fertility. Therefore, the objective of this review is to explore the diversity and role that these microbial communities play in the biocrust, particularly cyanobacteria, highlighting studies conducted using omics technologies. The knowledge generated in recent years through omics technologies has demonstrated the limited coverage of traditional molecular techniques, resulting in an underestimation of the real diversity of microbial communities. In addition, there has been an improvement in the understanding of the ecological processes developed by the microorganisms for the benefit of the biocrust, as well as the individual and collective functional capacities, which will serve as a baseline to propose important strategies to solve the problem of soil degradation.

Resumen El pasto lobero (Muhlenbergia phleoides [Kunth] Columbus) es un recurso forrajero nativo del norte de México; sin embargo, se desconoce su variabilidad en cuanto a atributos forrajeros. El objetivo de este estudio fue caracterizar la variabilidad morfológica y nutricional de 30 poblaciones de pasto lobero del estado de Chihuahua. La caracterización se realizó el segundo año de establecimiento a través de las variables morfológicas y nutricionales. Los datos morfológicos se analizaron con técnicas multivariadas. Para los datos nutricionales se realizó análisis de varianza y comparación de medias Tukey. Los tres primeros CP (componentes principales) explicaron el 82.38% de la variación total. El análisis de conglomerados jerárquicos identificó cuatro grupos. En el análisis nutricional, las poblaciones solo presentaron diferencias (p < 0.05) en la variable PC. La variabilidad que presentó el pasto lobero permite inferir que existe diversidad morfológica entre poblaciones del estado de Chihuahua; no obstante, las variables nutricionales no presentaron diferencia entre las poblaciones de esta especie.

Abstract Wolftail grass (Muhlenbergia phleoides [Kunth] Columbus) is a native forage resource from northern Mexico; however, its variability in terms of forage attributes is unknown. The objective of this study was to characterize the morphological and nutritional variability of 30 populations of wolftail grass in the state of Chihuahua. The characterization was carried out the second year of establishment through the morphological and nutritional variables. Morphological data were analyzed with multivariate techniques. For nutritional data, analysis of variance and comparison of Tukey means were performed. The first three PC (principal components) explained 82.38% of the total variation. Hierarchical cluster analysis identified four groups. In the nutritional analysis, the populations only presented differences (p < 0.05) in the CP variable. The variability that wolftail grass presented allows to infer that there is morphological diversity among populations of the state of Chihuahua; however, the nutritional variables did not show differences between the populations of this species.

Recently, the Chilean Senate approved the main ideas of a constitutional reform and a Neuro-rights bill. This bill aims to protect people from the potential abusive use of “neuro-technologies”. Unfortunately, a literal interpretation of this law can produce severe negative effects both in the development of neuroscience research and medical practice in Chile, interfering with current treatments in countless patients suffering from neuropsychiatric diseases. This fear stems from the observation of the negative effects that recent Chilean legislations have produced, which share with the Neuro-Rights Law the attempt to protect vulnerable populations from potential abuse from certain medical interventions. In fact, Law 20,584 promulgated in 2012, instead of protecting the most vulnerable patients “incapacitated to consent”, produced enormous, and even possibly irreversible, damage to research in Chile in pathologies that require urgent attention, such as many neuropsychiatric diseases. This article details the effects that Law 20.584 had on research in Chile, how it relates to the Neuro-Rights Law, and the potential negative effects that the latter could have on research and medical practice, if it is not formulated correcting its errors.

Abstract Background Postoperative Hyperlactatemia (PO-HL) is a frequent condition associated with poor prognosis. In recent years, there has been growing evidence that adrenergic stimulation may contribute to increased lactate levels. The use of adrenergic agonists for the control of intraoperative hypotension is frequent, and its impact on the development of PO-HL is unknown. Objective To evaluate whether the use of intraoperative adrenergic agents is associated with the occurrence of PO-HL. Methods This was a prospective observational study. The inclusion criteria were undergoing elective open colon surgery, being ≥60 years old and signing informed consent. The exclusion criteria were cognitive impairment, unplanned surgery, and anticipated need for postoperative mechanical ventilation. Baseline and intraoperative variables were collected, and arterial lactate data were collected at baseline and every 6 hours postoperatively for 24 hours. Hyperlactatemia was defined as lactate >2.1 mEq.L-1. Results We studied 28 patients, 61% of whom developed hyperlactatemia. The variables associated with PO-HL in the univariate analysis were anesthetic time, the total dose of intraoperative ephedrine, and lower intraoperative central venous oxygen saturation (ScvO2). Multivariate analysis confirmed the association between the use of ephedrine (p = 0.004), intraoperative hypotension (p = 0.026), and use of phenylephrine (p = 0.001) with PO-HL. Conclusions The use of intraoperative ephedrine, phenylephrine and intraoperative hypotension were independently associated with the development of PO-HL. This finding should lead to new studies in this field, as well as a judicious interpretation of the finding of a postoperative increase in lactate levels.

Abstract This work is aimed to determine the impact of economic growth and the legal complexity of the Value-Added Tax Act (LIVA, in Spanish) in the VAT collection between 1980 and 2016. This analysis is based on an ordinary least squares model transformed using the Box-Cox methodology. The results reveal a positive relation between economic growth and VAT collection, and a negative relation between the legal complexity index and VAT collection. It is suggested to extrapolate this analysis of the effects of legal reforms on the collection of other taxes, because a negative effect may be generated by the modifications made by increasing the complexity of tax laws and reducing the understanding of the tax payers. In consensus with the existing literature, a negative effect on the VAT collection is confirmed by the increase in the legal complexity index.

Resumen El objetivo es determinar el impacto del crecimiento económico y de la complejidad legal de la Ley del Impuesto al Valor Agregado (LIVA), en la recaudación del IVA para el periodo 1980 - 2016. Se utilizó un modelo de mínimos cuadrados ordinarios transformado mediante la metodología de Box - Cox. Los resultados muestran que existe una relación positiva entre el crecimiento económico y la recaudación del IVA y una relación negativa entre el índice de complejidad legal y la recaudación del IVA. Se recomienda extrapolar el análisis a otros impuestos para medir el impacto de sus reformas legales sobre su recaudación, se puede generar un efecto negativo por las modificaciones legales realizadas que podrían incrementar la complejidad de las leyes fiscales y reducir la comprensión de los sujetos obligados. En consenso con la literatura, se confirma un efecto negativo sobre la recaudación del IVA por el incremento en el índice de complejidad legal.

Abstract In this paper, a differential neural network (DNN) is used to project Pfizer’s stock returns in the 2018-2020 period. The model uses quarterly data, at the end of the period, the price of the company’s stock (P), net sales (NS), total assets (TA) and accounts receivable (AR). The results are compared with the classic regression models and there is evidence of the superior goodness of fit of the DNN, compared to conventional methods, since the error in out sample forecast is less than 5 %.

Resumen En este trabajo se utiliza una red neuronal diferencial (DNN, por sus siglas en inglés) para proyectar los rendimientos accionarios de Pfizer en el período 2018-2020. El modelo emplea datos trimestrales, al cierre del período, del precio de la acción de la empresa (P), ventas netas (VN), activos totales (AT) y cuentas por cobrar (CC). Los resultados señalan una bondad de ajuste superior de las DNN frente a los métodos convencionales, pues el error en el pronóstico out sample es inferior al 5 %. Este hallazgo contribuye con evidencia empírica para afirmar que las DNN ofrecen mayor robustez predictiva de los rendimientos accionarios de Pfizer.

Abstract From the end of the 1990’s and the beginning of the 2000’s, Latin American region experienced the largest female labor force participation growth in the world. Recent literature (Camou, 2015; Chioda, 2016; Gasparini & Marchionni, 2015; Klasen, 2018; Serrano et al., 2018) conclude that marriage and fertility trends, economic growth and education as important determinants, but agree to the need to analyze women preferences and social factors also as contributing elements. This study contributes to the literature by studying these two factors in the region, from the viewpoint of Akerlof & Kranton’s (2000) Identity Economic Theory, and Welzel’s (2013b) Emancipative Values Theory. Exploiting World Values Survey data and European Values Study, this investigation developed a probabilistic regression model where women’s preference towards egalitarian views as workingwoman is analyzed as Women’s Identity, and social constraints upon gender equality is analyzed integrating a Women’s Emancipative Values indicator. This work also compares Latin American countries results with OECD countries to note differences between the groups. We conclude that Women’s Identity and Women’s Emancipative Value are strong positive statistically significant determinants of FLFP. When compared with OECD countries, we also conclude that women in the two groups of countries share similar self-views as workingwoman, but Latin America still has social constraints at play that are limiting FLFP in the region.

Resumen Desde finales de 1990 y principios del 2000, la región de América Latina experimentó el mayor crecimiento de participación laboral femenina en el mundo. Literatura reciente (Camou, 2015; Chioda, 2016; Gasparini & Marchionni, 2015; Klasen, 2018; Serrano, Gasparini, Marchionni, & Gluzmann, 2018) han concluido que las tendencias en el matrimonio y la fertilidad, crecimiento económico y la educación son determinantes importantes, pero concuerdan en la necesidad de analizar las preferencias de las mujeres y factores sociales elementos que contribuyen, también. Este estudio aporta a la literatura al estudiar estos dos factores en la región, desde el punto de vista de la Teoría Económica de la Identidad de Akerlof & Kranton (2000), y la Teoría de los Valores Emancipativos de Welzel’s (2013b). Mediante la explotación de datos del World Values Survey y del European Values Study, esta investigación desarrolló un modelo de regresión probabilística en dónde las preferencias de las mujeres hacia una visión igualitaria como mujer que trabaja, es analizada como Identidad de las Mujeres, y las restricciones sociales sobre la igualdad de género se analizan integrando un indicador de Valores Emancipativos de las Mujeres. Este trabajo también compara los resultados de los países de Latinoamericanos con países de la OCDE para identificar las diferencias entre los grupos. Concluimos que la identidad de la mujer y el valor emancipativo de las mujeres son fuertes determinantes positivos y estadísticamente significativos de la participación laboral femenina. En la comparación con países de la OCDE, también concluimos que las mujeres en los dos grupos de países comparten opiniones similares de sí mismas como mujer trabajadora, pero América Latina tiene aún limitaciones sociales en juego que limitan su participación en el mercado laboral en la región.

Resumo Justificativa: O delírio pós-operatório é uma complicação séria em pacientes submetidos à cirurgia abdominal de grande porte. Ainda não está claro se as variáveis hemodinâmicas e de perfusão no período perioperatório afetam o risco de delírio pós-operatório. O objetivo deste estudo piloto foi avaliar a associação entre perfusão e hemodinâmica no perioperatório com o surgimento de delírio pós-operatório. Métodos: Estudo prospectivo de coorte de adultos com 60 anos ou mais, submetidos à cirurgia eletiva aberta do cólon. As variáveis multimodais de hemodinâmica e perfusão foram monitoradas, inclusive oxigenação venosa central (ScvO2), níveis de lactato e oxigenação cerebral não invasiva (rSO2), de acordo com um protocolo-padrão de anestesia. O teste exato de Fisher ou o teste t de Student foram usados para comparar os pacientes que desenvolveram delírio pós-operatório com aqueles que não desenvolveram p < 0,05. Resultados: Avaliamos 28 pacientes, 73 ± 7 anos, 60,7% do sexo feminino. Dois pacientes desenvolveram delírio pós-operatório (7,1%). Esses dois pacientes tinham menos anos de escolaridade do que aqueles sem delírio pós-operatório (p = 0,031). Nenhuma das variáveis de pressão arterial no perioperatório foi associada à incidência de delírio. Quanto aos parâmetros de perfusão, ScvO2 foi menor no grupo que apresentou delírio pós-operatório do que no grupo que não apresentou delírio, sem atingir significância estatística (65 ± 10% vs. 74 ± 5%; p = 0,08), mas o delta-ScvO2 (a diferença entre as médias no pós-operatório e intraoperatório) foi associado ao delírio (p = 0,043). As variáveis de lactato e rSO2 no pós-operatório não foram associadas ao delírio. Conclusões: Nosso estudo piloto sugere uma associação entre delta-ScvO2 e delírio e uma tendência à diminuição da ScvO2 no pós-operatório de pacientes com delírio. Estudos adicionais são necessários para elucidar essa associação.

Abstract Background: Post-operative delirium is a serious complication in patients undergoing major abdominal surgery. It remains unclear whether peri-operative hemodynamic and perfusion variables affect the risk for postoperative delirium. The objective of this pilot study was to evaluate the association between perfusion and hemodynamics peri-operative with the appearance of post-operative delirium. Methods: Prospective cohort study of adults 60 years or older undergoing elective open colon surgery. Multimodal hemodynamic and perfusion variables were monitored, including central venous oxygenation (ScvO2), lactate levels, and non-invasive cerebral oxygenation (rSO2), according to a standard anesthesia protocol. Fisher's exact test or Student's t-test were used to compare patients who developed post-operative delirium with those who did not (p < 0.05). Results: We studied 28 patients, age 73 ± 7 years, 60.7% female. Two patients developed post-operative delirium (7.1%). These two patients had fewer years of education than those without delirium (p = 0.031). None of the peri-operative blood pressure variables were associated with incidence of post-operative delirium. In terms of perfusion parameters, postoperative ScvO2 was lower in the delirium than the non-delirium group, without reaching statistical significance (65 ± 10% vs. 74 ± 5%; p = 0.08), but the delta-ScvO2 (the difference between means post-operative and intra-operative) was associated with post-operative delirium (p = 0.043). Post-operative lactate and rSO2 variables were not associated with delirium. Conclusions: Our pilot study suggests an association between delta ScvO2 and post-operative delirium, and a tendency to lower post-operative ScvO2 in patients who developed delirium. Further studies are necessary to elucidate this association.

Refractory status epilepticus is a catastrophic illness of the central nervous system, with a mortality rate that reaches 50%. We report three patients admitted with refractory status epilepticus: a 24 year-old male that discontinued antiepileptic medications, a 46 year-old male with a focal epilepsy secondary to an encephalitis that discontinued medications due to gastrointestinal problems and a 59 year-old male with an ischemic encephalopathy AH were treated with topiramate, delivered through a nasogastric tube with a good response.

Limbic encephalitis (LE) can be associated to cancer, viral infection or be idiopathic. One form is associated to voltage dependent potassium channel (VKC) antibodies. The clinical presentation includes impairment of consciousness, amnesia and temporal lobe seizures; typical abnormalities are also found in brain magnetic resonance. We report a 68 year-old male who had LE associated to VKC antibodies. The patient was treated with steroids with a partial response. At the moment of the report he is asymptomatic and continues with prednisone treatment .

Background: Nasal continuous positive airway pressure therapy (CPAP) in the treatment of choice for adult obstructive sleep apnea (OSA). The diagnosis is established with polysomnography, but this study is expensive and must be repeated in those patients that require CPAP, to titrate the pressure of the therapy. Split polysomnography during one night to establish the diagnosis and titrate the pressure has been proposed to reduce costs. Aim: To assess if CPAP pressure can be adequately titrated in patients with OSA using a split-night polysomnography. Material and methods: One hundred fifty six patients with OSA were studied with split night polysomnography. CPAP pressure titration was considered adequate when there were less than five apnea/hypopnea episodes per hour, the registry time was more than 30 min, REM sleep occurred in more than 15% of the time and measurements were made in supine position. Results: An adequate titration was achieved in 80% of patients. The variables associated with an adequate titration were a higher registry time during the titration period, a higher percentage of stage III/IV or REM sleep during such period and the comfort experienced by the patient during the study. On the other hand, patients with an inadequate titration had a longer basal registry period. Conclusions: An adequate CPAP pressure can be prescribed to 80% of patients subjected to a split-night polysomnography. The basal registry period should not be longer than three hours, to allow an adequate titration lapse

Our Editorial Committee presents a panel discussion on conflicts of interest in order to formulate a reflection on the issue. The panel defines "conflict of interest" both in general terms and specifically for publishing, and analyses other scenarios in medical practice in which conflicts of interest could potentially be a problem. The purpose of explicit declarations on conflicts of interest is evaluated as a means of bringing about greater preventive transparency, which is the key to community control over the problem. Finally, an analysis is made of cases and examples in which the interests were not made clear, as well as a study of how users of biomedical information are affected when they learn of conflicts of interest. From the information presented in the panel discussion, it can be concluded that conflicts of interest do indeed exist, that it is an issue that must inevitably be addressed, and that it is naïve to suppose that it is a problem that can easily be brought under control. We must create instruments to make the relationships and ties natural to our daily activities more transparent. Many of those who openly declare their conflicts of interest have healthy ties. In a scenario of explicit declarations, undeclared ties are potentially suspect by their very nature. A group consensus on an issue does not result in immediate behavior changes, but it is a first step that must be taken immediately. The possibility of a particular slant must be taken into consideration in a systematic analysis of any article, even in those articles backed by a group of professionals or by scientific associations. Finally, to distance oneself from the guidelines of the International Committee of Medical Journal Editors is an unwise and isolating course of action for a biomedical publication.

Con motivo de incorporar la declaración de conflicto de interés en nuestra revista, el comité editorial presenta un Panel sobre el tema. En éste, se define conflicto de interés en términos generales y editoriales, así como se analizan otros escenarios de la práctica médica con potenciales conflictos de intereses. Se evalúa el sentido de las declaraciones explícitas de conflicto de interés, como expresión de preventiva transparencia, clave del control comunitario del problema. Finalmente se evalúan casos y ejemplos de subnotificación de intereses y el impacto del conocimiento de los conflictos de intereses en los usuarios de la información biomédica. De la información presentada en el panel es posible concluir que: el conflicto de interés existe, el aludirlo es inevitable, el pensar controlarlo con facilidad es ingenuo. El generar instrumentos que sirvan para transparentar relaciones y vínculos que son naturales en nuestro quehacer, es necesario. Muchos de los que declaran sus conflictos de interés tienen vínculos sanos. En un escenario de declaraciones explícitas los vínculos no declarados por ese solo hecho resultan potencialmente sospechosos. El acuerdo y consenso conceptual en un tema tarda en cambiar conductas, pero el paso inicial es impostergable. La responsabilidad de pensar en el sesgo, como manera sistemática de análisis de un artículo, es una responsabilidad indelegable, incluso en aquellos artículos que cuentan con gran soporte corporativo profesional o de sociedades científicas. Finalmente el abstraerse de las pautas del International Committee of Medical Journal Editors, es editorialmente imprudente e insular.

Normal EEG variants recognition is very important in order to reduce diagnostic errors in epilepsy. There are no reports in our country regarding this EEG activity, and in regular practice only one of them it is mentioned ocassionally, which prompted us to investigate this issue. Objective. To establish the incidence of normal variants in routine EEGs in a laboratory population older than a year. Methods. The presence of normal variants (wicket spikes, 14 and 6 positive spikes, psychomotor variant, small spikes of sleep, slow waves of the elderly, pseudo petit mal, arousal theta, dicrotic alpha, µ rhythm, phantom spikes and rhythmic subclinic discharges of the adult) was studied prospectively in all routine EEGs (standard and after sleep deprivation) performed in patients older than one year at the EEG laboratory of the Hospital Clínico de la Universidad Católica de Chile between october 1999 and September 2000. All the records were read by one of the authors. Results. From a total number of 1816 normal EEG recordings, 4,8% (n=88) showed normal variants, reaching in patients over 60 years old to 11,4%. Within the normal variants the most frequently found were µ rhythm (45,5%), wicket spikes (21,6%) and psychonmotor variant (9,1%). No phantom spikes neither subclinical rhytmic discharges of the adult were found. Conclusion. Normal variants are found not infrequently in normal routine EEGs in our country, specially in patients over 60; it is convenient to have them in mind for avoiding overdiagnosis of epileptiform activity

El reconocimiento de variantes normales en electroencefalogramas de rutina es de gran importancia para reducir errores diagnósticos, especialmente en epilepsia ya que la mayoría de estas variantes presenta morfología aguda o epileptiforme y suelen ser foccales. No existen en nuestro medio trabajos que reporten esta actividad y en la práctica clínica sólo una de ellas es descrita ocasionalmente, lo que motiva esta investigación. Objetivo. Conocer la incidencia de variantes normales en electroencefalogramas normales en mayores de un año, tomados de una población de laboratorio de EEG. Material y Métodos. Se estudia prospectivamente la presencia de variantes normales (espigas "wicket", espigas positivas a 14 y 6 Hz, variante psicomotora, pequeñas espigas de sueño, ondas lentas de la senectud, pseudo petit mal, theta del despertar, alfa dicroto, ritmo µ, espigas fantasmas y descargas rítmicas subclínicas del adulto), en todos los EEG de rutina (estándares o post privación de sueño), practicados a mayores de un año en el Laboratorio de Electroencefalografía del Hospital Clínico de la Universidad Católica de Chile entre Octubre de 1999 y Septiembre de 2000. Todos los registros fueron analizados por alguno de los autores. Resultados. De un total de 1816 registros normales, el 4,8% (n=88) mostró alguna variante normal, llegando en el grupo sobre los 60 años a 11,4%. Del total de variantes las más frecuentemente encontradas fueron el ritmo µ (45,5%), las espigas wicket (21,6%) y las variantes psicomotoras (9,1%). No se pesquisaron espigas fantasmas ni descargas rítmicas subclínicas del adulto. Conclusión. Las variantes normales de aspecto epileptiforme se encuentran con relativa frecuencia en EEGs normales de rutina en nuestro medio, especialmente en personas sobre 60 años de edad y conviene tenerlas presente para evitar sobrediagnóstico de actividad genuinamente patológica