[Maternal eating disorders and their influence on eating behavior of the children: a review of the literature]. / Trastornos alimentarios maternos y su influencia en la conducta alimentaria de sus hijas(os).

BACKGROUND: There is conclusive evidence about the influence of mothers with eating disorders (ED) on their children. OBJECTIVE: To describe different aspects about mothers with ED and its implications in the feeding, growing and development in their children. METHOD: A review of specialized textbooks and the available literature in PubMed was made. RESULTS: Mothers with previous or present ED show restrictive eating patterns, a deficient affective bond with their own mothers, exhibit more psychiatric comorbidities, mainly depression and anxiety; in addition, feelings of guilt and shame, early cessation of breastfeeding, high control of food consumption of their children, and/or pressure them to eat, irregular mealtimes, unbalanced and monotonous meals, proneness to slimness, a critical attitude about the body shape of their daughters. Breastfeeding implies a critical period for the irruption or relapse of an ED due to the adjustment to the characteristic body shape changes during pregnancy. CONCLUSIONS: There is a particular relationship between a maternal ED and its occurrence in their children, and it can be considered a risk factor for its development.

[Pyomyositis in children: report of two cases]. / Piomiositis en niños: Reporte de 2 casos.

Pyomyositis (PM) is an uncommon pyogenic infection of skeletal muscle and, when not properly treated, it can progress to a high-risk clinical situation with high mortality. Because it usually has a subacute presentation, diagnosis is often delayed. We present two cases of PM of the paraspinal muscles in healthy children and discuss the current state of knowledge of this disease.

Spatial aggregation patterns in four mistletoe species: ecological and environmental determinants.

Plant spatial distribution is an important topic in ecology as it determines species coexistence and biodiversity dynamics. Usually, plants show clustered distributions in nature. Mistletoes are a good example of aggregated distributions, as they form dense aggregations due to several factors (availability of competent hosts, seed dispersal vectors, microclimate conditions). We analysed four native mistletoe species with divergent life histories and host ranges: Desmaria mutabilis and Tristerix corymbosus from the temperate rainforests of southern Chile; and Tristerix aphyllus and Tristerix verticillatus from the northern semi-desert zone. While T. corymbosus and T. verticillatus have a wide host range, T. aphyllus and D. mutabilis are specialists that can parasitize only a few plant species. We hypothesized that specialized species would be more aggregated due to ecological and environmental restrictions. We used heterogeneous Poisson models to quantify spatial aggregation. Three of the four mistletoe species were spatially clustered at both environments, with aggregation being stronger in the temperate rainforest of southern Chile and particularly in the host-specialist species. Our results suggest that environmental constraints are more important than ecological constraints (host range) in shaping mistletoe spatial structure. Mistletoe aggregated spatial distribution depends primarily on the environment that they inhabit, which conditions host spatial availability, and arrangement.

[Empyema and pleural effusion in children]. / Empiema y efusión pleural en niños.

INTRODUCTION: Pleural empyema (PE) is a serious complication of community-acquired pneumonia (CAP). OBJECTIVES: To describe the clinical profile of hospitalized patients with PE in the pediatric ward of the Catholic University Hospital between 2000-2005. PATIENTS AND METHODS: Retrospectively, all pediatric admission due to CAP and pleural effusion (86 children) were identified. In 59 (70%) children > 1 thoracocentesis were performed. We considered PE as the presence in the pleural effusion of pus, and/or a positive gram strain and/ or positive culture, and/or a pH < 7.10. Children with effusions not meeting any criteria were used as controls. RESULTS: Twenty four PE and 25 controls were identified, with a global mean age of 2.9 years (range: 8 months to 14.3 years); 78% were < 5 years, with a significant difference between PE and controls [1.6 vs 3.3 years (p = 0.01)]. The mean duration of symptoms in PE patients before admission was 7 days (range: 2-21), and the most frequent symptoms were fever (100%) and cough (96%). In 15/24 cases a microorganism was identified being Streptococcus pneumoniae (n = 9) the most common. In 48 patients management was conservative and in 4 surgical procedures were required. The mean duration of hospitalization was significantly higher in the PE group vs controls group: 15 (range: 5-38) vs 9 days (range 3-16) (p < 0.01). A chest tube was inserted in 83% of children with EP compared with 36% in the control group (p = 0.002). There were no difference in number of days of oxygen use [6 vs 4.5 (p = 0.36)] or number of chest tubes per child [3 vs 2.5 (p = 0.29)]. No deaths were reported. CONCLUSION: PE in children represented an acute respiratory event associated with more prolonged hospitalization especially at younger ages; the majority of cases did not require surgical intervention.

Aproximaciones psicoterapéuticas para el manejo del tinnitus crónico no pulsátil / Psychotherapy approaches for the management of non-pulsatile chronic tinnitus

Resumen La fisiopatología del tinnitus crónico no pulsátil es poco clara, pero se reconoce un componente psicológico relevante, por tanto, existen distintas aproximaciones psicoterapéuticas que han sido estudiadas. La terapia cognitivo conductual es la que cuenta con mayor evidencia. Ella contempla la reestructuración de las cogniciones disfuncionales que favorecen la presencia del tinnitus. Se ha verificado su eficacia en los niveles de distrés, calidad de vida, severidad, sintomatología depresiva e insomnio asociados. La desensibilización y reprocesamiento por movimientos oculares recoge algunos presupuestos de la terapia cognitivo conductual, pero considera técnicas como la estimulación bilateral. Sus resultados en patologías crónicas somáticas han sugerido la aplicación en tinnitus, corroborando su eficacia en calidad de vida, distrés y sintomatología depresiva. Dos psicoterapias basadas en mindfulness aplicadas en tinnitus son la reducción del estrés basado en el mindfulness y la terapia cognitiva basada en mindfulness. La primera ha demostrado eficacia en la calidad de vida y en la disminución y el refuerzo de cogniciones negativas y positivas, respectivamente. La segunda, es eficaz en la severidad, intensidad, distrés, ansiedad, depresión y discapacidad asociadas a tinnitus. Finalmente, la terapia de aceptación y compromiso promueve la aceptación como componente central del tratamiento de condiciones crónicas, considerando el control que ejerce el contexto sobre la vivencia de estas condiciones y el compromiso terapéutico. Esta terapia es eficaz en calidad de vida. Se promueve la investigación en aproximaciones psicoterapéuticas para el tinnitus, lo que posibilitará la aplicación de terapias más específicas y la clarificación de su fisiopatología.

Abstract The pathophysiology of non-pulsatile chronic tinnitus is unclear, but it is recognized a relevant psychological component. In this sense, different psychotherapeutic approaches have been studied. Cognitive behavioral therapy is the psychotherapy with the most evidence. It considers the restructuring of dysfunctional cognitions that favor the presence of tinnitus. Its efficacy has been verified on distress, quality of life, severity, associated depressive symptoms and insomnia. Eye movement desensitization and reprocessing includes some conceptions of cognitive behavioral therapy and considers techniques such as bilateral stimulation. Its results in chronic somatic pathologies have suggested its application in tinnitus, corroborating its efficacy in quality of life, distress, and depressive symptoms. Two mindfulness-based psychotherapies applied in tinnitus are mindfulness-based stress reduction and mindfulness-based cognitive therapy. The first has shown efficacy on quality of life and reduction and reinforcement of negative and positive cognitions, respectively. The second is effective on severity, loudness, distress, anxiety, depression and disability associated with tinnitus. Finally, acceptance and commitment therapy promote acceptance as a central component of the treatment of chronic conditions, considering the control exerted by the context over the experience of these conditions and the therapeutic commitment. This therapy is effective on quality of life. We foster the research on psychotherapeutic approaches to tinnitus, which will make it possible the application of more specific interventions and, at the same time, elucidate its pathophysiology.

Recovering functional independence after a stroke through Modified Constraint-Induced Therapy.

BACKGROUND: Population ageing and changes in the epidemiological profile of neurological pathologies has resulted in an increase in patients with disabilities. Rehabilitation strategies such as Modified Constraint-Induced Movement Therapy (CIMTm) play a key role in treating patients with neurologic deficiencies and motor impairments. This intervention is intended to mitigate disability, promote maximum functional independence, and optimize social and economic participation of patients with upper extremity weakness. Our goal was to assess the recovery of functional independence in patients after a stroke using to CIMTm. PATIENTS AND METHOD: Thirty-six subjects who had suffered stroke took part in a randomised clinical trial. The treatment was applied through either collective or individual modalities for three hours per day for a period of ten days. Participant's functional independence was assessed using the Functional Independence Measure (FIM) scale at the before and after of the intervention. RESULTS: An analysis of covariance carried out on the pre-test assessments indicates that the dependent variable presents significant differences (F1.31 = 42.78, p < 0.001, η2p = 0.72) in favour of the collective intervention modality. CONCLUSION: Both modalities of CIMTm intervention promote functional independence. However, the greatest improvements were observed in participants in the collective modality. Improvements in functional independence pursue a reduction in learned non-use behaviours through greater use of the paretic upper extremity in everyday activities.

Efecto placebo en otorrinolaringología: revisión de la literatura / Placebo effect in otorhinolaryngology: a narrative review

Resumen La palabra placebo ha sido usada, indistintamente, para referir a una sustancia o procedimiento que es "inerte" ("placebo") y al efecto que ocurre como consecuencia de la administración de un placebo ("efecto placebo"). El efecto placebo es un fenómeno psicobiológico que ha sido explicado desde el conductismo (condicionamiento clásico), desde fenómenos preconscientes (expectativas o "efecto placebo clásico"), desde el cognitivismo (disonancia cognitiva) y también a nivel neurobiológico. No obstante, los ensayos clínicos abiertos que verifican la respuesta a placebo desafían el mecanismo de la expectativa, dando lugar al análisis bayesiano, que integra sensaciones, experiencias, predicciones y claves del contexto; biológicamente, el efecto placebo no es inerte. Por tanto, el placebo ocupa un lugar relevante en la práctica clínica y en la investigación biomédica. Se realizó una búsqueda sistemática sobre placebo y otorrinolaringología en las bases de datos PubMed/Medline, SciELO y Cochrane Library. Se incluyeron estudios primarios y revisiones sistemáticas de la literatura. En cuanto a intervenciones placebo, la literatura publicada indica mejorías significativas en síntomas nasales y calidad de vida en rinitis alérgica (estacional y perenne) y disminución del dolor posoperatorio en amigdalectomía. En la enfermedad de Méniere, las intervenciones placebo son comparables a las de uso habitual, incluyendo las quirúrgicas. No se encontraron ensayos clínicos abiertos en otorrinolaringología ni evidencia sobre otras patologías del área. Las intervenciones y el efecto placebo abren un campo de investigación y desarrollo en otorrinolaringología que desafía la comprensión actual de las patologías, su funcionamiento, su tratamiento y la relación terapéutica.

Abstract The word placebo has been used interchangeably to refer to a substance or procedure that is "inert" ("placebo") and the effect that occurs as a consequence of its administration ("placebo effect"). The placebo effect corresponds to a psychobiological phenomenon that has been explained from behaviorism (classical conditioning), from preconscious phenomena (expectations or "classical placebo effect"), from cognitivism (cognitive dissonance) and at the neurobiological level as well. Nevertheless, some open-label trials that verify the response to placebo challenge the expectation mechanism, giving rise to Bayesian analysis, which integrates sensations, experiences, predictions and context clues; therefore, biologically, the placebo effect is not inert. The placebo has a relevant place both in clinical practice and in biomedical research. We conducted a systematic search on placebo and otolaryngology in PubMed/Medline, SciELO and Cochrane Library databases. We included primary studies and systematic reviews. Regarding placebo interventions, the available literature points out significant improvements in nasal symptoms and quality of life in allergic rhinitis (seasonal and perennial) and a decrease in post-tonsillectomy pain. In Méniére's disease, placebo interventions have demonstrated to be comparable to treatment-as-usual, including surgical interventions. No open-label clinical trials were found in otolaryngology, as well as no evidence on other diseases in the area. Placebo interventions and their effects open a field of research and development in otolaryngology, challenging the current understanding of pathologies, their functioning, their treatment and the therapeutic relationship.

Trastornos somatomorfos y conversivos en otorrinolaringología pediátrica: revisión de la literatura

Resumen Los trastornos somatomorfos (TS) corresponden a un conjunto de entidades de expresión polimorfa cuya característica común es la relevancia de los síntomas somáticos asociados a un malestar psicológico significativo evidente o no, pero sin una base estructural delimitada. Si la sintomatología se asocia al sistema nervioso se denominan trastornos conversivos (TC). Su etiología tiene una naturaleza multicausal y compleja y se expresan en todos los sistemas del organismo. Los TS y los TC han sido poco estudiados en la otorrinolaringología pediátrica y su enseñanza es escasa en la formación médica. Se realizó una búsqueda sistemática sobre TS y TC en otorrinolaringología pediátrica en las bases de datos PubMed/Medline, SciELO y Cochrane Library. Se incluyeron 49 referencias, principalmente estudios observacionales y revisiones narrativas. Los cuadros clínicos descritos fueron el estridor funcional, la sordera psicógena, el trastorno facticio y el vértigo psicógeno. El proceso diagnóstico requiere de la evaluación otorrinolaringológica y psiquiátrica. En todos los estudios se reconoció que los participantes tenían alguna alteración afectiva prominente, aunque a veces oculta. El análisis del contexto social y escolar, además de los antecedentes familiares de TS, TC o cualquier desorden mental son elementos primordiales. La terapia es multidisciplinaria, incluyendo intervenciones otorrinolaringológicas, fonoaudiológicas, psicológicas y psicofarmacológicas. Sin embargo, la evidencia que sustenta a las intervenciones especializadas es escasa. Los niños, niñas y adolescentes con TS y TC presentan hallazgos clínicos y biológicos que no se presentan en los simuladores. Un adecuado diagnóstico y tratamiento se relacionan con un buen pronóstico.

Abstract Somatoform disorders (SD) make up a group of entities with polymorphic expression, characterized by the relevance of somatic symptoms associated to a significant psychological stress whether or not noticeable, but without a defined structural basis. When the symptomatology is related to the nervous system, they are known as conversion disorders (CD). Their etiology has a multicausal and complex nature, having expressions in all the body systems. SD and CD have been scarcely studied in pediatric otolaryngology and are poorly reviewed during medical training. We performed a systematic search on SD and CD in pediatric otolaryngology in PubMed/Medline, SciELO and Cochrane Library databases. We included 49 references, mostly observational studies and narrative reviews. The most described clinical pictures were functional stridor, psychogenic deafness, factitious disorder, and psychogenic vertigo. The diagnostic process requires otolaryngologic and psychiatric evaluations. All studies showed that participants had some relevant affective alteration, although sometimes unnoticeable. Thus, some essential elements are social and school context, family history of SD or CD or any mental disorder. Therapy involves a multidisciplinary approach, including otolaryngologic, audiological, psychological and psychopharmacological interventions. However, evidence supporting specialized interventions is still scarce. Children and adolescents who suffer from SD and CD show clinical and biological findings which are not found in malingering. Proper diagnosis and treatment are related to a good prognosis.

Género, mujeres e investigación científica / Gender, women and scientific research

El género es una construcción psicosocial referida a los roles, comportamientos, expresiones e identidades socialmente construidos de niñas, mujeres, niños, hombres y personas con diversidad de género, mientras que el sexo se relaciona con los atributos biológicos de una mujer o un hombre. Aun cuando los términos "sexo" y "género" suelen utilizarse de forma binaria, existe una diversidad considerable en la forma en que los individuos y los grupos los entienden, experimentan y expresan. En esta revisión narrativa se describen algunos aspectos relevantes acerca de la diferencia subjetiva que existe y favorece a los hombres frente a las mujeres en el ámbito de las ciencias e investigación, iniciando desde una perspectiva histórica a la luz de los movimientos feministas. En particular, se describe a la mujer en cuanto investigadora y creadora de conocimiento científico, como también en su calidad de sujeto de análisis. Se analizan además algunos conflictos derivados del sesgo de sexo aplicados a la investigación biomédica, y se entregan casos que ejemplifican el desmedro que ha acompañado históricamente al género femenino en este ámbito, su desconocimiento y poco reconocimiento cultural. Esta revisión es la última entrega de una serie metodológica sobre conceptos generales en bioestadística y epidemiología clínica desarrollada por la Cátedra de Metodología de la Investigación Científica de la Escuela de Medicina de la Universidad de Valparaíso, Chile, que pretende abordar una temática contingente y transversal a toda la investigación científica.

Gender is a psychosocial construct referring to the socially built roles, behaviors, expressions and identities of girls, women, boys, men and people with gender diversity, while sex is related to the biological attributes of a woman or a man. Even though the terms "sex" and "gender" are often used in a binary way, there is considerable diversity in the way individuals and groups understand, experiment and express them. This narrative review describes some relevant aspects of the subjective difference that exists and favors men over women in the fields of sciences and research, starting from a historical perspective in the light of feminist movements. In particular, women are described as researchers - crea-tors of scientific knowledge, as well as the subjects of analysis. Some conflicts arising from sex bias, applied to biomedical research, are also analyzed, and cases are delivered that exemplify the disarray that has historically accompanied the female gender in this area, its ignorance and little cultural recognition. This review is the last article in a methodological series on general concepts in biostatistics and clinical epidemiology developed by the Chair of Methodology of Scientific Research of the School of Medicine of the Universidad de Valparaiso, Chile, which aims to address a contingent and cross-cutting theme to all scientific research.

International Child Care Practices Study: infant sleeping environment.

BACKGROUND: The International Child Care Practices Study (ICCPS) has collected descriptive data from 21 centres in 17 countries. In this report, data are presented on the infant sleeping environment with the main focus being sudden infant death syndrome (SIDS) risk factors (bedsharing and infant using a pillow) and protective factors (infant sharing a room with adult) that are not yet well established in the literature. METHODS: Using a standardised protocol, parents of infants were surveyed at birth by interview and at 3 months of age mainly by postal questionnaire. Centres were grouped according to geographic location. Also indicated was the level of SIDS awareness in the community, i.e. whether any campaigns or messages to "reduce the risks of SIDS" were available at the time of the survey. RESULTS: Birth interview data were available for 5488 individual families and 4656 (85%) returned questionnaires at 3 months. Rates of bedsharing varied considerably (2-88%) and it appeared to be more common in the samples with a lower awareness of SIDS, but not necessarily a high SIDS rate. Countries with higher rates of bedsharing appeared to have a greater proportion of infants bedsharing for a longer duration (>5 h). Rates of room sharing varied (58-100%) with some of the lowest rates noted in centres with a higher awareness of SIDS. Rates of pillow use ranged from 4% to 95%. CONCLUSIONS: It is likely that methods of bedsharing differ cross-culturally, and although further details were sought on different bedsharing practices, it was not possible to build up a composite picture of "typical" bedsharing practices in these different communities. These data highlight interesting patterns in child care in these diverse populations. Although these results should not be used to imply that any particular child care practice either increases or decreases the risk of SIDS, these findings should help to inject caution into the process of developing SIDS prevention campaigns for non-Western cultures.

La revisión sistemática como herramienta para la validación científica de propiedades saludables de los alimentos y factores alimentarios / Using systematic reviews in the scientific substantiation of health properties of foods and food constituents

Las revisiones sistemáticas de literatura constituyen una de las principales metodologías utilizadas en la validación de las propiedades saludables de los alimentos, o factores alimentarios, que afectan la fisiología humana. Esta herramienta, basada en la evidencia obtenida a través de ensayos clínicos aleatorizados realizados con un diseño experimental adecuado, permite concluir si existe una relación causal entre el producto consumido y un efecto beneficioso para la salud, principio que sustenta el calificativo de los alimentos como "funcionales". Se presentan y analizan las características y la forma en la que las revisiones sistemáticas pueden contribuir a que las agencias regulatorias aprueben un mensaje saludable (health claim), dirigido al consumidor.

Systematic literature reviews are one of the main methodologies used to substantiate the health properties of foods and food constituents purported to affect human physiology. This tool is based on scientific evidence obtained from correctly performed randomized controlled trials. Systematic reviews make it possible to conclude whether there is a causal relationship between food consumed and health effects observed, thus supporting the use of the term "functional foods." We present and analyze the prinicpal characteristics of, and ways by which, systematic reviews can contribute to the regulatory approval of health claims directed to consumers.

Conceptos generales en bioestadística y epidemiología clínica: error aleatorio y error sistemático / General concepts in biostatistics and clinical epidemiology: random error and systematic error

La investigación biomédica, particularmente la que involucra a seres humanos, está siempre sometida a fuentes de error que deben ser reconocidas. El error sistemático o sesgo, se asocia con debilidades en el diseño metodológico o de la fase de ejecución del estudio. Éste afecta su validez y se valora cualitativamente. Por su parte, el error aleatorio se relaciona con las variaciones producidas por el azar, el cual puede expresarse cuantitativamente, pero nunca eliminarse. Esta revisión es la primera entrega de una serie metodológica sobre conceptos generales en bioestadística y epidemiología clínica desarrollada por la Cátedra de Metodología de la Investigación Científica de la Universidad de Valparaíso, Chile. En este artículo se abordan los conceptos teóricos asociados al error, su evaluación y control. Finalmente, se discuten algunas controversias actuales en cuanto a su conceptualización, de relevancia para estudiantes de pre y posgrado de ciencias de la salud.

Biomedical research, particularly when it involves human beings, is always subjected to sources of error that must be recognized. Systematic error or bias is associated with problems in the methodological design or during the execu-tion phase of a research project. It affects its validity and is qualitatively ap-praised. On the other hand, random error is related to variations due to chance. It may be quantitatively expressed, but never removed. This review is the first of a methodological series on general concepts in biostatistics and clin-ical epidemiology developed by the Chair of Scientific Research Methodology at the School of Medicine, University of Valparaíso, Chile. In this article, we address the theoretical concepts of error, its evaluation, and control. Finally, we discuss some current controversies in its conceptualization that are relevant to undergraduate and graduate students of health sciences.

Conceptos generales en bioestadística y epidemiología clínica: estudios observacionales con diseños transversal y ecológico / General concepts in biostatistics and clinical epidemiology: observational studies with cross-sectional and ecological designs

Los estudios observacionales analizan las variables de interés en la muestra o en la población, sin intervenir en ellas. Pueden ser meramente descriptivos si se focalizan en la descripción de las variables, o analíticos, en el caso de presentar grupos de comparación para establecer asociaciones mediante la inferencia estadística. Los estudios transversales y los estudios ecológicos, también llamados correlacionales, son dos diseños metodológicos observacionales. Los estudios transversales recogen los datos de la variable exposición y desenlace en un mismo momento, para describir sus características y eventualmente estudiar asociaciones. Los estudios ecológicos describen y analizan las correlaciones entre distintas variables, pero su unidad de análisis corresponde a datos agregados de múltiples individuos. En ambos casos no puede inferirse una relación causal, pero sí pueden establecerse asociaciones de gran interés para la investigación biomédica. Esta revisión es la segunda entrega de una serie metodológica sobre conceptos generales en bioestadística y epidemiología clínica desarrollada por la Cátedra de Metodología de la Investigación Científica de la Escuela de Medicina de la Universidad de Valparaíso, Chile. En este artículo se abordan conceptos teóricos generales sobre estudios transversales y estudios ecológicos, considerando sus aplicaciones, medidas de asociación, ventajas, desventajas y reporte. Finalmente, se discuten algunos conceptos de relevancia sobre diseños observacionales para los estudiantes de pre y posgrado de ciencias de la salud.

Observational studies evaluate variables of interest in a sample or a population, without intervening in them. They can be descriptive if they focus on the description of variables, or analytical when comparison between groups is made to establish associations through statistical inference. Cross-sectional studies and ecological­also called correlational­studies are two observational methodological designs. Cross-sectional studies collect the data of the exposure variable and the outcome at the same time, to describe characteristics of the sample or to study associations. Ecological studies describe and analyze correlations among different variables, and the unit of analysis is aggregated data from multiple individuals. In both types of studies, associations of interest for biomedical research can be established, but no causal relationships should be inferred. This is the second of a methodological series of articles on general concepts in biostatistics and clinical epidemiology developed by the Chair of Scientific Research Methodology at the School of Medicine, University of Valparaíso, Chile. In this review, we address general theoretical concepts about cross-sectional and ecological studies, including applications, measures of association, advantages, disadvantages, and reporting guidelines. Finally, we discuss some concepts about observational designs relevant to undergraduate and graduate students of health sciences.

Conceptos generales en bioestadística y epidemiología clínica: estudios observacionales con diseño de cohorte / General concepts in biostatistics and clinical epidemiology: observational studies with cohort design

Los estudios con diseño de cohorte evalúan la relación entre una exposición y la ocurrencia o no de un evento de interés, comenzando el análisis desde la exposición. Habiendo sido diseños muy utilizados en algunas áreas de la medicina, como la descripción de factores de riesgo cardiovascular o los efectos de la radiación ionizante en humanos, representan una herramienta con características atractivas debido a su adaptabilidad a numerosos contextos, sobre todo en el estudio de exposiciones de baja ocurrencia. Esta revisión es la cuarta entrega de una serie metodológica sobre conceptos generales en bioestadística y epidemiología clínica desarrollada por la Cátedra de Metodología de la Investigación Científica de la Escuela de Medicina de la Universidad de Valparaíso, Chile. En este artículo, se abordan conceptos teóricos generales sobre los estudios de cohorte, considerando aspectos históricos, generalidades sobre la construcción de un estudio utilizando este diseño, presentando distintas variantes y diseños derivados de interés, y potenciales sesgos a los que se puede ver enfrentado el investigador.

Cohort studies evaluate the relationship between exposure to a specific event or phenomenon and the occurrence of an associated out-come of interest (or lack thereof). This methodological design has been widely used in certain areas of medicine, such as the study of cardiovascular risk factors and the effects of ionizing radiation in humans. It is a useful study design, especially for research involving low-occurrence exposures, because it can be easily adapted to various contexts. This article, which provides an overview of observational cohort studies, is part of a methodology series on general concepts in biostatistics and clinical epidemiology developed by the Chair of Scientific Research Methodology at the University of Valparaíso's School of Medicine in Chile. It describes historical, practical, and theoretical concepts related to cohort studies; essential elements in cohort study design, and variations and derivations of it; potential types and sources of bias in these types of observational/longitudinal studies, and various methods researchers can use to address/minimize them.

Evaluación psicológica y cognitiva de autismo en un paciente con síndrome de MOMO: reporte de caso y revisión de la literatura / Psychological and cognitive evaluation of autism in a patient with MOMO syndrome: a case report and literature review

MOMO es un acrónimo para los términos macrosomía, obesidad, macrocefalia y anomalías oculares. El síndrome fue descrito por primera vez en 1993, con un total de nueve pacientes publicados a la fecha. Todos los casos reportaron discapacidad intelectual y en un caso se describió a un paciente con autismo. Presentamos un nuevo caso de paciente con síndrome de MOMO que consultó por fenómenos alucinatorios. Se completó una evaluación neuropsicológica, clínica y cognitiva, en donde se demostró un cociente intelectual limítrofe y se corroboraron los criterios para trastorno del espectro autista. Ésta es la primera evaluación neurocognitiva de un paciente con MOMO, la que apoya el uso de escalas estandarizadas a fin de evaluar el autismo y otras comorbilidades psiquiátricas en pacientes con síndromes genéticos.

MOMO is an acronym for macrosomia, obesity, macrocephaly and ocular abnormalities. The syndrome was first described in 1993, with a total of nine patients published thus far. All the cases presented intellectual disability and in one case autism was described. We present a new case of a patient with MOMO syndrome, who consulted for hallucinatory phenomena. He completed a neuropsychological, clinical and cognitive evaluation, showing a borderline intelligence quotient and fulfilled the criteria for autism spectrum disorder. This is the first neurocognitive evaluation of a patient with MOMO, supporting the use of standardized scales in order to assess the autism and other psychiatric comorbidities in patients with genetics syndromes.

Preparation and molecular characterization of chitosans obtained from shrimp (Litopenaeus vannamei) shells.

Four chitosan samples were prepared from shrimp shells without deproteination and decoloration steps, by a deacetylation process at 2 reaction times (2 and 4 h) and with/without using a reducing agent (R.A.). Variations in the physicochemical properties of the final products were analyzed. Viscosity average molecular weight (Mw) determinations demonstrated the protective action of the R.A. on the molecular oxidative degradation. Oppositely, an increase on the reaction time produced samples with low Mw. Deacetylation degrees (DDs) were chemically evaluated by the nitrogen content and by spectroscopic techniques as infrared and nuclear magnetic resonance. The existing differences in crystallinity were studied by X-ray diffraction. Differential scanning calorimetry and thermogravimetry were used to demonstrate the dehydration and thermal degradation processes of the different chitosans. A novel method from calorimetric profiles is presenting for DD determinations of chitosan, which achieved highly satisfactory results (linear fit and Pearson's correlation coefficient) and is proposed to be generally extended to complex curves application.

Pautas Éticas del Consejo de Organizaciones Internacionales de las Ciencias Médicas: avances y temáticas no resueltas en la actualización 2016 / Council for International Organizations of Medical Sciences (CIOMS) Ethical Guidelines: advancements and unsolved topics in 2016 upgrade

A fines del año 2016 se publicó la nueva edición de las Pautas Éticas Internacionales para la Investigación Relacionada con la Salud con Seres Humanos del Consejo de Organizaciones Internacionales de las Ciencias Médicas (CIOMS, por sus siglas en inglés Council for International Organizations of Medical Sciences), estándares universalmente reconocidos en la investigación biomédica. En este artículo se realiza un análisis crítico de las potencialidades y falencias de las nuevas pautas del CIOMS 2016. Algunos avances alcanzados consideran la importancia asignada al valor social de la investigación y su repercusión en la toma de decisiones y la creación de políticas públicas, el desarrollo de investigación en escenarios de bajos recursos, la participación de las comunidades en el proceso investigativo, la determinación de la vulnerabilidad de los participantes de una investigación y los cambios en los procedimientos de consentimiento informado. Esta actualización es una gran herramienta para investigadores y miembros de los comités de ética científica. Asimismo, aunque constituye una adaptación a los rápidos cambios científicos, tecnológicos y sociales; permanecen aspectos no resueltos, principalmente en torno al manejo del riesgo mínimo de los participantes y de los conflictos de interés involucrados en una investigación, además del desarrollo de ésta en escenarios de bajos recursos. No obstante, se hace un positivo progreso en cuanto al contexto y las necesidades de las poblaciones en las que se desarrollarán las investigaciones y la participación comunitaria en las distintas fases del proyecto, accediendo a sus potenciales beneficios. El impacto de las pautas del CIOMS 2016, deberá evaluarse en el tiempo, en particular en escenarios de inequidades socio-sanitarias y de intereses comerciales de la industria en la investigación biomédica.

In 2016, the new edition of the Council for International Organizations of Medical Sciences (CIOMS) Ethical Guidelines was released, which are universally acknowledged as ethical standards in biomedical research. In this article, we critically analyze the improvements and shortcomings of the CIOMS Ethical Guidelines 2016. Among the improvements are the relevance assigned to the social value of research and its effects on decision-making and the creation of public policies; the research development in low-resources scenarios; the communities' involvement in the research process; the determination of participants' vulnerability and changes on informed consent related proceedings. Despite the improved harmonization with scientific, technologic and social changes, and that the guidelines provide a tool for researchers and members of research ethics committees alike, some topics remain unsolved, namely the management of participants' minimal risk and conflicts of interest involved in research, and the development of research in low-incomes scenarios. Nonetheless, we recognize that these new guidelines constitute a progress regarding the context and needs of populations in which research will be conducted, with greater community involvement in the different phases of the investigation project, thus allowing them to access the potential benefits. The impact of the CIOMS Ethical Guidelines 2016, should be appraised over time, particularly in socio-sanitary inequities scenarios and in the context of commercial interests of industry on biomedical research.

Síntesis de información biomédica: revisiones narrativas, revisiones sistemáticas y estructuras emergentes / Syntheses of biomedical information: narrative reviews, systematic reviews and emerging formats

La divulgación de información biomédica se expande de manera exponencial, lo que representa un desafío para aquellos profesionales de la salud que deseen obtener información integrada de alta calidad y relevancia. Las revisiones, en sus distintos formatos, son herramientas que pueden abordar este problema. Este artículo describe los principales tipos de síntesis de información biomédica, sus estructuras, la utilidad de cada una de ellas, y presenta los últimos formatos desarrollados por las diferentes organizaciones que se dedican a la síntesis de información.

Biomedical information dissemination has expanded exponentially, and this can represent a challenge for those health professionals who wish to obtain high quality and relevant integrated information. Reviews, in their different formats, are tools that can address this problem. This article describes the main types of syntheses of biomedical information, their structures, their usefulness, and presents the latest information synthesis formats that were developed by different organizations committed to this purpose.

Pérdida celular endotelial corneal asociada a facoemulsificación y experiencia del oftalmólogo: análisis prospectivo de datos secundarios individuales / Corneal endothelial cell loss associated to phacoemulsification and ophthalmologist experience: prospective analysis of individual secondary data

Resumen Introducción La facoéresis es el procedimiento en que se extrae quirúrgicamente el cristalino para tratar las cataratas. La pérdida endotelial corneal es una complicación reconocida. Si bien se han descrito diversos factores asociados a este daño, la experiencia del cirujano ha sido poco explorada. Objetivos Evaluar la asociación entre la experiencia del cirujano y otras variables asociadas a la pérdida celular endotelial en el contexto de la facoéresis. Métodos Se analizaron registros clínicos de 198 cirugías de cataratas, evaluando el efecto de la experiencia del cirujano y otras variables asociadas: energía disipada acumulada, tipo de viscoelástico empleado, uso de azul tripán, cantidad de fluídica, tiempo de ultrasonido, energía de facoemulsificación combinada y recuento celular endotelial pre y postoperatorio. Resultados No se observaron diferencias en el conteo postoperatorio de células endoteliales. Los oftalmólogos con más de cinco años de experiencia presentaron menor uso de azul tripán pero mayor cantidad de energía disipada acumulada en cada procedimiento, mientras que los oftalmólogos con menor experiencia utilizaron mayor cantidad de fluídica. Conclusiones Aunque hubo diferencias en el manejo de algunos factores influyentes sobre la pérdida endotelial cornal según la experiencia de los oftalmólogos, no se hallaron diferencias en relación a dicha pérdida como resultado final.

Abstract Introduction Phacoeresis is the procedure through which the lens is surgically removed to treat cataracts. A corneal endothelial loss is a recognized sequel. Although several factors associated with this harm have been described, the surgeon's prior experience has been scarcely evaluated. Objectives To assess the association between the surgeon's experience and other variables associated with a corneal endothelial cell loss in the context of phacoeresis. Methods Clinical records of 198 patients undergoing cataract operations were prospectively reviewed. The experience of the surgeon and other variables were recorded, including cumulative dissipated energy, viscoelastic type, the use of trypan blue, amount of fluidics, ultrasound time, combined phacoemulsification energy, and pre- and postoperative corneal endothelial cell counts. Results No differences were observed in the postoperative corneal endothelial cell count between surgeons with more or less than five years of experience. Nevertheless, ophthalmologists with more than five years' experience used less trypan blue, but more cumulative dissipated energy in each procedure, while less experienced ophthalmologists used less fluidics. Conclusions Although there were differences in the surgical management regarding the surgeons' experience in factors known to influence corneal endothelial cell loss, no differences in endothelial cell loss were observed as an outcome.

Estado actual de los trastornos somatomorfos y conversivos en niños y adolescentes / Current state of somatoform and conversion disorders in children and adolescents

Introducción: Los trastornos somatomorfos (TS) y conversivos (TC) han aumentado su incidencia durante las dos últimas décadas en niños y adolescentes, aunque ambos son habitualmente subdiagnosticados. Objetivo: Efectuar una puesta al día de la evidencia sobre TS y TC en niños y adolescentes. Método: Se realizó una búsqueda bibliográfica mediante las bases de datos Medline/PubMed, SciELO y textos especializados. Resultados: Existe una alta intercurrencia con trastornos afectivos y ansiosos y se han identificado algunos factores de riesgo, especialmente mayor vulnerabilidad al estrés, disfunción familiar, sobreprotección parental y limitada mentalización de los síntomas físicos (alexitimia), que también perpetuan la sintomatología. Desde la perspectiva etiopatogénica se han invocado hipótesis psicodinámicas, psicosomáticas, traumático-ambientales y biológicas. Los pacientes con TS y TC frecuentemente son mujeres, presentan rasgos más introvertidos de personalidad, más eventos vitales estresantes y défictis ejecutivos. Las convulsiones psicógenas no epilépticas se relacionan con más comorbilidades psiquiátricas y peor pronóstico. Las psicoterapias cognitivo-conductual y la hipnoterapia-psicodinámica combinadas con fármacos inhibidores de la recaptura de serotonina han demostrado ser eficaces en el tratamiento. Conclusiones: Los TS y TC en poblaciones infanto juveniles se observan en contextos médicos y psiquiátricos. Su reconocimiento es difícil debido a su etiología multifactorial, la falta de consenso diagnóstico yla escasa experiencia clínica, implicando un verdadero desafío terapéutico, por lo que es indispensable realizar futuras investigaciones en este tópico. Su manejo en la atención primaria parece apropiado, pero en casos más complejos es necesaria su derivación al especialista.

Background: Somatoform (SD) and conversion (CD) disorders have increased their incidence during the last two decades in children and adolescents, although both are currently underdiagnosed. Objective: To review the evidence on SD and CD in children and adolescents. Method: A review ofspecialised textbooks and the available literature in Medline/PubMed and SciELO was made. Results: There is a high intercurrence with affective and anxiety disorders and some riskfactors have been identified, especially higher vulnerability to stress, family disfunction, parental overprotection, and limited mentalization of physical symptoms (alexithymia), which at the same time, perpetuate the symptomatology. From an ethiopathogenicperspective, psychodynamic, psychosomatic, traumatic-environmental and biological hypothesis have been invoked. Patients with SD and CD are frequently females, show more introversive personality features, more stressful life events and executive deficits. Psychogenic non-epileptic seizures are related with more psychiatric co-morbidities and worse outcome. Cognitive-behavioural psychotherapy and psychodynamic-hypnotherapy combined with selective serotonin reuptake inhibitors have been effective. Conclusions: SD and CD in child and adolescent populations have been observed in medical and psychiatric contexts. Their recognition is difficult due to their multifactorial ethiology, the lack of diagnosis consensus and the scarce clinical experience, involving a true therapeutic challenge; therefore, it is imperative to carry out future researches on this issue. Their management in primary care seems suitable, but in more complex cases the referral to the specialist is necessary.