Bone Loss Induced by Simulated Microgravity, Ionizing Radiation and/or Ultradian Rhythms in the Hindlimbs of Rats / 生物医学与环境科学（英文）

OBJECTIVE@#To better understand the pathological causes of bone loss in a space environment, including microgravity, ionizing radiation, and ultradian rhythms.@*METHODS@#Sprague Dawley (SD) rats were randomly divided into a baseline group, a control group, a hindlimb suspension group, a radiation group, a ultradian rhythms group and a combined-three-factor group. After four weeks of hindlimb suspension followed by X-ray exposure and/or ultradian rhythms, biomechanical properties, bone mineral density, histological analysis, microstructure parameters, and bone turnover markers were detected to evaluate bone loss in hindlimbs of rats.@*RESULTS@#Simulated microgravity or combined-three factors treatment led to a significant decrease in the biomechanical properties of bones, reduction in bone mineral density, and deterioration of trabecular parameters. Ionizing radiation exposure also showed adverse impact while ultradian rhythms had no significant effect on these outcomes. Decrease in the concentration of the turnover markers bone alkaline phosphatase (bALP), osteocalcin (OCN), and tartrate-resistant acid phosphatase-5b (TRAP-5b) in serum was in line with the changes in trabecular parameters.@*CONCLUSION@#Simulated microgravity is the main contributor of bone loss. Radiation also results in deleterious effects but ultradian rhythms has no significant effect. Combined-three factors treatment do not exacerbate bone loss when compared to simulated microgravity treatment alone.

Modulation of the ultradian human nasal cycle by sleep stage and body position / Modulação do ciclo nasal humano ultradiano pelo estágio do sono e a posição corporal

ABSTRACT Objective: The nasal cycle, which is present in a significant number of people, is an ultradian side-to-side rhythm of nasal engorgement associated with cyclic autonomic activity. We studied the nasal cycle during REM/non-REM sleep stages and examined the potentially confounding influence of body position on lateralized nasal airflow. Methods: Left- and right-side nasal airflow was measured in six subjects during an eight-hour sleep period using nasal thermistors. Polysomnography was performed. Simultaneously, body positions were monitored using a video camera in conjunction with infrared lighting. Results: Significantly greater airflow occurred through the right nasal chamber (relative to the left) during periods of REM sleep than during periods of non-REM sleep (p<0.001). Both body position (p < 0.001) and sleep stage (p < 0.001) influenced nasal airflow lateralization. Conclusions: This study demonstrates that the lateralization of nasal airflow and sleep stage are related. Some types of asymmetrical somatosensory stimulation can alter this relationship.

RESUMO Objetivo: O ciclo nasal é um ritmo ultradiano de lado a lado de ingurgitamento associado com o ciclo da atividade autônoma. O objetivo deste estudo foi abordar a questão assim como a relação presente entre o ciclo nasal e os estágios de sono REM/não-REM. Também analisamos a confusão potencial da influência da posição corporal no fluxo de ar nasal. Métodos: Mensuramos o ciclo nasal em seis sujeitos durante um sono de oito horas usando um termistor nasal. Foi realizada uma polissonografia. Simultaneamente, nós monitoramos a posição corporal usando uma câmera de vídeo juntamente com luzes infravermelhas. Resultados: Um fluxo de ar maior ocorreu através da cavidade nasal direita durante as fases de sono REM do que nos períodos de sono não-REM (p < 0,001). Assim como a posição corporal [F(2.2340) = 86,99, p < 0,001] e o estágio de sono [F(1.2340) = 234.82, p < 0,001] influenciaram a lateralização do fluxo de ar nasal. Conclusões: Este estudo evidencia que a lateralização do fluxo de ar nasal e o estágio do sono estão relacionados. Alguns tipos de estimulação somatosensitiva assimétrica podem alterar esta relação.