Topical administration of 8% PFD gel 3 times a day is more effective and safe in the treatment of hypertrophic scars caused by burns in children, as compared with standard pressure therapy.

In Caucasians and Native Americans living at altitude, hemoglobin mass is increased in spite of erythropoietin concentrations ([Epo]) not markedly differing from sea level values. We hypothesized that a nocturnal decrease of arterial oxygen saturation (SaO2) causes a temporary rise of [Epo] not detected by morning measurements. SaO2 (continuous, finger oximeter) and [Epo] (ELISA, every 4 h) were determined in young highlanders (altitude 2600 m) during 24 h of usual daily activity. In Series I (six male, nine female students), SaO2 fell during the night with the nadir occurring between 01:00 and 03:00; daily means (range 92.4–95.2%) were higher in females (+1.7%, P < 0.01). [Epo] showed opposite changes with zenith occurring at 04:00 without a sex difference. Mean daily values (22.9 ± 10.7SD U/L) were higher than values obtained at 08:00 (17.2 ± 9.5 U/L, P < 0.05). In Series II (seven females), only SaO2 was measured. During follicular and luteal phases, SaO2 variation was similar to Series I, but the rhythm was disturbed during menstruation. While daily [Epo] variations at sea level are not homogeneous, there is a diurnal variation at altitude following changes in SaO2. Larger hypoventilation‐dependent decreases of alveolar PO2 decreases during the night probably cause a stronger reduction of SaO2 in highlanders compared to lowlanders. This variation might be enlarged by a diurnal fluctuation of Hb concentration. In spite of a lower [Hb], the higher SaO2 in women compared to men led to a similar arterial oxygen content, likely explaining the absence of differences in [Epo] between sexes.

La importancia de la Epo como hormona central en los procesos de ambientación a la altura es clara dado su efecto estimulante sobre la producción  eritrocitaria. Su naturaleza hormonal ha llevado a que algunas investigaciones evalúen su circadianidad con reportes no contundentes e inclusive contradictorios al respecto. Objetivo: Analizar la circadianidad de la Epo en sujetos que realizan entrenamiento aeróbico en la altura intermedia (2600 msnm) comparando diferencias entre hombres y mujeres. Materiales y métodos: Se reclutaron residentes a la altura intermedia de por lo menos 18 meses, de ambos sexos y que tuvieran entrenamiento aeróbico al menos durante 8 meses previos a la realización del estudio para medir su Epo cada 4 horas durante 24 horas y correlacionarla con algunas variables fisiológicas y ambientales. Resultados: Existe comportamiento circadiano en la Epo tanto para hombres como para mujeres, con un mesor para hombres de 20:10 h y 16:33 h para mujeres. En cuanto a la acrofase, esta se presenta hacia las 17:52 h para hombres y a las 15:50 h para las mujeres. El análisis de diferencia de medias muestra una diferencia estadísticamente significativa entre los dos grupos Conclusión: Existe circadianidad diferencial entre hombres y mujeres en cuanto a sus niveles de Epo, la cual es independiente de variables fisiológicas y ambientales. Tema: Ritmo circadiano. Subtema: Eritropoyetina.

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