Caenorhabditis elegans as a Promising Model Organism in Chronobiology.

Circadian rhythms represent an adaptive feature, ubiquitously found in nature, which grants living beings the ability to anticipate daily variations in their environment. They have been found in a multitude of organisms, ranging from bacteria to fungi, plants, and animals. Circadian rhythms are generated by endogenous clocks that can be entrained daily by environmental cycles such as light and temperature. The molecular machinery of circadian clocks includes a transcriptional-translational feedback loop that takes approximately 24 h to complete. Drosophila melanogaster has been a model organism of choice to understand the molecular basis of circadian clocks. However, alternative animal models are also being adopted, each offering their respective experimental advantages. The nematode Caenorhabditis elegans provides an excellent model for genetics and neuro-behavioral studies, which thanks to its ease of use and manipulation, as well as availability of genetic data and mutant strains, is currently used as a novel model for circadian research. Here, we aim to evaluate C. elegans as a model for chronobiological studies, focusing on its strengths and weaknesses while reviewing the available literature. Possible zeitgebers (including light and temperature) are also discussed. Determining the molecular bases and the neural circuitry involved in the central pacemaker of the C. elegans' clock will contribute to the understanding of its circadian system, becoming a novel model organism for the study of diseases due to alterations of the circadian cycle.

Evolución y costes de la prematuridad por indicación médica en un hospital de tercer nivel / Evolution and costs of the medically indicated preterm birth in a tertiary care university hospital

INTRODUCCIÓN Y OBJETIVO: Analizar la evolución y los costes de los partos prematuros iatrogénicos en un hospital universitario de tercer nivel. MÉTODOS: Estudio de cohortes retrospectivo de los partos con edad gestacional comprendida entre 24 y 36+6 semanas en dos periodos temporales: 2001-2005 y 2011-2016. Se identificaron los partos prematuros por indicación médica o iatrogénicos (PPI). Se analizaron variables demográficas y de resultado. Los costes se calcularon mediante el grupo relacionado con el diagnóstico (GRD) de cada ingreso. RESULTADOS: Se obtuvo una muestra de 620 partos prematuros iatrogénicos. La tasa de prematuridad global se mantuvo estable en 9%. La tasa de prematuridad iatrogénica experimentó un incremento relativo del 9,7%. Entre las pacientes con un PPI se apreció un incremento en la edad materna de 27,7 a 32,9 años, de la obesidad (32,2% a 55,5%) y del uso de técnicas de reproducción asistida (6% a 11,1%). Preeclampsia y retraso del crecimiento (CIR) fueron las principales causas de PPI, en los que se incrementó la tasa de cesáreas de 66,9% a 78%, la estancia media de 7,8 días a 9,6 y el coste por paciente de 3.068,6 a 7.331,9 euros. CONCLUSIONES: Se observa un aumento de PPI en el segundo periodo, manteniéndose la prematuridad global. Los cambios demográficos podrían explicar este incremento. Estos cambios están implicados en la fisiopatología de la preeclampsia y el CIR y en el aumento de su incidencia. La prevención primaria y secundaria de esas complicaciones podría reducir la incidencia y los costes de la prematuridad iatrogénica.

INTRODUCTION AND OBJECTIVES: To evaluate the incidence, evolution, causes and costs of premature births (PB) due to medical indication (iatrogenic) in a tertiary care university hospital METHODS: Retrospective cohort study of all deliveries with gestational age between 24 and 36+6 weeks, in two periods 2001-2005 and 2011-2016. Iatrogenic births were identified. Clinical, epidemiological, diagnostic and economic variables were analysed. RESULTS: A sample size of 620 iatrogenic deliveries was obtained. We found a 9.7% relative increase in iatrogenic prematurity rate in the second period as well as an increase in maternal age from 27.7 to 32.9, obesity from 32.2% to 55.5% and the use of assisted reproductive techniques from 6% to 11.1%. Preeclampsia and intrauterine growth restriction were found to be the main causes of iatrogenic premature delivery. In these cases the rates of cesarean section increased from 66.9% to 78%. The average stay per patient and the cost calculated by diagnosis related group (DRG) also showed a statistically significant increase from 7.8 days and 3,068.6 euros to 9.6 days and 7,331.9 euros. CONCLUSIONS: We observed an increase in iatrogenic prematurity in the second period despite the unchanged rate of spontaneous PB. Demographic changes in the population, as well as an increase in obstetric related conditions, seem to be responsible for this increase. Primary and secondary prevention of clinical characteristics may reduce the incidence and costs derived from this type of prematurity.

[Validation of the Ocular Surface Disease Index Questionnaire for Chilean patients]. / Adaptación cultural y validación del cuestionario Ocular Surface Disease Index en una población chilena.

BACKGROUND: Ocular Surface Disease Index (OSDI) is the most commonly used questionnaire worldwide to detect dry eye disease. Although it is massively used in clinical practice in Chile, its use has not been validated yet in the country. AIM: To develop a cultural adaptation and to validate the OSDI questionnaire for the Chilean population. MATERIAL AND METHODS: For cultural adaptation, a translation, retro-translation and an expert panel review was carried out. The resulting questionnaire was applied to a pilot group of twelve participants and their comments were considered for the final questionnaire version. The final questionnaire was applied to a non-random sample of 200 patients aged 53 ± 17 years (75% women). Internal consistency and construct validity were evaluated by Cronbach's alpha and exploratory factor analysis respectively. RESULTS: According to the OSDI score, 81% of respondents had dry eye (55% severe). Reliability was 0.91 and factor analysis resulted in three factors explaining 75.4% of the total variance. CONCLUSIONS: The OSDI questionnaire version obtained in this study demonstrated excellent internal consistency values and adequate construct validity making it applicable to clinical practice and dry eye research.

Adaptación cultural y validación del cuestionario Ocular Surface Disease Index en una población chilena / Validation of the Ocular Surface Disease Index Questionnaire for Chilean patients

Background: Ocular Surface Disease Index (OSDI) is the most commonly used questionnaire worldwide to detect dry eye disease. Although it is massively used in clinical practice in Chile, its use has not been validated yet in the country. Aim: To develop a cultural adaptation and to validate the OSDI questionnaire for the Chilean population. Material and Methods: For cultural adaptation, a translation, retro-translation and an expert panel review was carried out. The resulting questionnaire was applied to a pilot group of twelve participants and their comments were considered for the final questionnaire version. The final questionnaire was applied to a non-random sample of 200 patients aged 53 ± 17 years (75% women). Internal consistency and construct validity were evaluated by Cronbach's alpha and exploratory factor analysis respectively. Results: According to the OSDI score, 81% of respondents had dry eye (55% severe). Reliability was 0.91 and factor analysis resulted in three factors explaining 75.4% of the total variance. Conclusions: The OSDI questionnaire version obtained in this study demonstrated excellent internal consistency values and adequate construct validity making it applicable to clinical practice and dry eye research.

Circadian rhythms identified in Caenorhabditis elegans by in vivo long-term monitoring of a bioluminescent reporter.

Circadian rhythms are based on endogenous clocks that allow organisms to adjust their physiology and behavior by entrainment to the solar day and, in turn, to select the optimal times for most biological variables. Diverse model systems-including mice, flies, fungi, plants, and bacteria-have provided important insights into the mechanisms of circadian rhythmicity. However, the general principles that govern the circadian clock of Caenorhabditis elegans have remained largely elusive. Here we report robust molecular circadian rhythms in C elegans recorded with a bioluminescence assay in vivo and demonstrate the main features of the circadian system of the nematode. By constructing a luciferase-based reporter coupled to the promoter of the suppressor of activated let-60 Ras (sur-5) gene, we show in both population and single-nematode assays that C elegans expresses ∼24-h rhythms that can be entrained by light/dark and temperature cycles. We provide evidence that these rhythms are temperature-compensated and can be re-entrained after phase changes of the synchronizing agents. In addition, we demonstrate that light and temperature sensing requires the photoreceptors LITE and GUR-3, and the cyclic nucleotide-gated channel subunit TAX-2. Our results shed light on C elegans circadian biology and demonstrate evolutionarily conserved features in the circadian system of the nematode.

Potential conservation of circadian clock proteins in the phylum Nematoda as revealed by bioinformatic searches.

Although several circadian rhythms have been described in C. elegans, its molecular clock remains elusive. In this work we employed a novel bioinformatic approach, applying probabilistic methodologies, to search for circadian clock proteins of several of the best studied circadian model organisms of different taxa (Mus musculus, Drosophila melanogaster, Neurospora crassa, Arabidopsis thaliana and Synechoccocus elongatus) in the proteomes of C. elegans and other members of the phylum Nematoda. With this approach we found that the Nematoda contain proteins most related to the core and accessory proteins of the insect and mammalian clocks, which provide new insights into the nematode clock and the evolution of the circadian system.

Convulsión febril / Febrile seizure

Las convulsiones febriles ocurren en niños entre los seis meses y los cinco años de edad, neurológicamente sano y ausencia de infección del sistema nervioso central, precipitadas por la fiebre. Su incidencia se estima entre el 2 por ciento y el 4 por ciento de la población pediátrica, con un porcentaje de recurrencia de un 30 por ciento a un 50 por ciento, siendo de mayor riesgo aquellos niños con convulsión febril que aparece en el curso del primer año de vida. Se clasifican en simples y complejas de acuerdo a la duracion, tipo de convulsión, número de convulsiones en 24 horas y estado neurológico postictal. El tratamiento profiláctico es controversial, utilizándose fármacos tanto en esquemas de administración continua como intermitente, recordando que cada paciente debe manejarse individualmente y considerando siempre los riesgos-beneficios de tales fármacos ante un proceso benigno de la infancia