Bone Loss Induced by Simulated Microgravity,Ionizing Radiation and/or Ultradian Rhythms in the Hindlimbs of Rats

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-Sb） 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.

人体尿量超日节律的研究

设计一个固定给食和供水的人体受试实验,通过测定一定时间间隔段内的尿量,并用计时图和周期图法找出了其节律周期,证实了人体尿排泄量存在6～12小时为周期的超日节律.

3H生物钟超日节律对图形命名测验一侧化效应的影响

采用半视野速示技术对被试进行连续8h图形命名测验,检查生物钟超日节律对大脑两半球机能优势效应的可能影响.结果表明:①14例被试明显表现出周期约为3h的左右脑半球优势节律;②其中7例被试表现为连续左视野（右半球）优势波动,另7例为左右视野（两半球）交叉优势波动;③女性被试的节律周期明显长于男性被试,且男性被试倾向于出现持续右半球优势波动,而女性被试倾向于出现两脑小球交叉优势波动.

月经周期不同阶段游离皮质醇昼夜节律的变化(英文)

为了研究皮质醇分泌的昼夜节律在月经周期中的变化,实验对15位月经周期正常的育龄期健康妇女,在月经周期的不同阶段分别于24h内每隔两小时采样,检测唾液昼夜游离皮质醇水平。采用非线性回归分析模型分析皮质醇昼夜节律。结果显示,皮质醇昼夜节律在整个月经周期都具有复杂的明显受到亚节律(ultradian)影响的分泌形式;与月经期相比,围排卵期和黄体晚期昼夜节律波峰宽度(peak-width)明显减低(P=0.005与 0.031),而昼夜节律波谷(trough)有抬高趋势(P=0.0622与0.066);黄体晚期的亚节律波幅(ultradian amplitude)与月经期相比显著减低(P=0.002)而与围排卵期相比有减低趋势(P= 0.05)。这些结果提示月经周期的不同阶段对皮质醇分泌的昼夜节律有影响。

睡眠觉醒的昼夜和次昼夜节律发育

睡眠觉醒发育与脑发育密切相关,多数动物睡眠觉醒节律发育规律与人类相似,由脑内生物钟、睡眠觉醒中枢和内平衡稳态等因素调节。成人的觉醒与睡眠呈昼夜节律性出现,整夜睡眠20%为快动眼(REM)睡眠,80%为非快动眼(NREM)睡眠。NREM-REM睡眠转换周期为90~110 min,表现为次昼夜节律。足月新生儿觉醒与睡眠昼夜均匀分布,睡眠常以REM睡眠起始,REM与NREM睡眠各占50%,转换周期为50~60 min;3月龄开始显现昼夜节律分布,睡眠周期以NREM睡眠起始,10岁后NREM-REM睡眠周期呈现近似成年次昼夜节律水平。睡眠与觉醒的昼夜节律及次昼夜节律的发育参与个体的生理和心理发育过程,了解睡眠觉醒节律调控及发育,为理解脑发育和新生儿睡眠节律异常导致的疾病奠定理论基础。

舞草侧生小叶旋转的生态意义——感性运动还是防御行为?

舞草复叶的运动兼具昼夜节律性和次昼夜节律性(周期<24 h),两者运动机制显著不同。舞草侧生小叶叶枕运动细胞呈环状排列,协调可逆的体积变化形成侧生小叶的旋转运动。侧生小叶叶枕可对多种环境因子进行响应,但生态功能不明。对舞草侧生小叶叶枕解剖学、电生理学、细胞生物学等研究进行整合,结合最新的植物行为学、动物行为学及生物力学相关研究进展,对舞草侧生小叶次昼夜节律行为的生态意义进行科学推测,以期为相关研究提供新的思路。