Construction of boundary-surface-based Chinese female astronaut computational phantom and proton dose estimation

With the rapid development of China''s space industry, the importance of radiation protection is increasingly prominent. To provide relevant dose data, we first developed the Visible Chinese Human adult Female (VCH-F) phantom, and performed further modifications to generate the VCH-F Astronaut (VCH-FA) phantom, incorporating statistical body characteristics data from the first batch of Chinese female astronauts as well as reference organ mass data from the International Commission on Radiological Protection (ICRP; both within 1% relative error). Based on cryosection images, the original phantom was constructed via Non-Uniform Rational B-Spline (NURBS) boundary surfaces to strengthen the deformability for fitting the body parameters of Chinese female astronauts. The VCH-FA phantom was voxelized at a resolution of 2 × 2 × 4 mm³for radioactive particle transport simulations from isotropic protons with energies of 5000–10 000 MeV in Monte Carlo N-Particle eXtended (MCNPX) code. To investigate discrepancies caused by anatomical variations and other factors, the obtained doses were compared with corresponding values from other phantoms and sex-averaged doses. Dose differences were observed among phantom calculation results, especially for effective dose with low-energy protons. Local skin thickness shifts the breast dose curve toward high energy, but has little impact on inner organs. Under a shielding layer, organ dose reduction is greater for skin than for other organs. The calculated skin dose per day closely approximates measurement data obtained in low-Earth orbit (LEO).     

Pulsed electromagnetic fields stimulate osteogenic differentiation and maturation of osteoblasts by upregulating the expression of BMPRII localized at the base of primary cilium

Pulsed electromagnetic fields (PEMFs) have been considered as a potential candidate for the prevention and treatment of osteoporosis, however, the mechanism of its action is still elusive. We have previously reported that 50 Hz 0.6 mT PEMFs stimulate osteoblastic differentiation and mineralization in a primary cilium- dependent manner, but did not know the reason. In the current study, we found that the PEMFs promoted osteogenic differentiation and maturation of rat calvarial osteoblasts (ROBs) by activating bone morphogenetic protein BMP-Smad1/5/8 signaling on the condition that primary cilia were normal. Further studies revealed that BMPRII, the primary binding receptor of BMP ligand, was readily and strongly upregulated by PEMF treatment and localized at the bases of primary cilia. Abrogation of primary cilia with small interfering RNA sequence targeting IFT88 abolished the PEMF-induced upregulation of BMPRII and its ciliary localization. Knockdown of BMPRII expression level with RNA interference had no effects on primary cilia but significantly decreased the promoting effect of PEMFs on osteoblastic differentiation and maturation. These results indicated that PEMFs stimulate osteogenic differentiation and maturation of osteoblast by primary cilium-mediated upregulation of BMPRII expression and subsequently activation of BMP-Smad1/5/8 signaling, and that BMPRII is the key component linking primary cilium and BMP-Smad1/5/8 pathway. This study has thus revealed the molecular mechanism for the osteogenic effect of PEMFs.     

航天运动病发生发展中的个体化研究策略

在人类的载人航天活动中,近半数航天员会在其飞行的24~72 h内受到运动病的困扰。运动病可能对航天员的健康和安全造成威胁。同时,航天员在运动病期间工作能力上受到的限制会对飞行任务造成巨大影响,尤其是对短期飞行任务。个体化研究策略关注影响运动病发生发展中的个体化因素,对载人航天事业有着重要的应用意义。基于个体化特征的个体化治疗理念对于治疗和缓解运动病病症,指导临床治疗和康复策略方案的制定将具有重要的指导意义。本文回顾了航天运动病发生率及其生理改变特点并进行了评价,对后续的运动病个体化研究提出了建议。     

45d-6°头低位卧床对下肢肌萎缩的影响及中药红景天的作用

目的观察模拟失重效应对下肢肌萎缩的影响及中药红景天的干预作用。方法 16名成年男性健康志愿者随机分为对照组(8人)和用药组(8人),进行45 d-6°头低位卧床模拟长期失重效应实验。卧床期间,用药组和对照组每天分别服用红景天(红益胶囊)和安慰剂。卧床前、中、后动态测量小腿围径;并采用MRI技术,测试和分析卧床前、后大腿和小腿肌群最大横截面积和肌肉体积的变化。结果1)卧床期间用药组和对照组小腿围径进行性下降,在卧床30和45 d均显著下降(P0.01),但用药组下降幅度显著减少(P0.05);2)卧床45 d,用药组和对照组大腿和小腿肌肉最大横截面积均显著降低(P0.01),其中小腿比目鱼肌下降幅度最大。用药组肌肉最大横截面积的减少较对照组均有改善作用(P0.05);3)对照组大腿和小腿肌群肌肉体积在卧床45 d均显著下降(P0.01),以比目鱼肌体积下降最为明显,用药组下降幅度显著减少,且比目鱼肌对抗作用最为明显(P0.01)。结论 45 d-6°头低位卧床引起进行性加重的肌萎缩,中药红景天可部分对抗模拟长期失重效应诱导的下肢肌萎缩。     

回转器模拟微重力对神经细胞自噬的影响(英文)

目的探讨回转模拟微重力对人神经母细胞瘤细胞(SH-SY5Y)自噬的影响。方法利用回转模拟微重力的细胞学效应,回转条件下培养细胞12 h、24 h,相同条件下静置培养细胞作为对照。WesternBlot方法检测LC3蛋白表达变化水平。荧光显微镜观察GFP-LC3点状聚集物,计数含有大于5个GFP-LC3点状聚集物的细胞数量。结果回转组SH-SY5Y细胞LC3-II蛋白表达高于对照组,荧光显微镜检测到GFP-LC3点状聚集物也随之增多。结论回转可以引起SH-SY5Y细胞自噬增多。     

镉、铅、乐果和对硫磷雌激素样联合作用初步研究

目的探讨镉、铅、乐果和对硫磷对未成年雌性小鼠雌激素样联合作用。方法选择断乳后17天龄SPF级雌性昆明小鼠192只,体重(25±2)g,随机分为16个组:空白对照组,氯化镉、醋酸铅、乐果和对硫磷组单独作用12个组,联合作用3个组。给药浓度为氯化镉、醋酸铅、乐果和对硫磷LD50(分别为9.3、140、45和3mg/kg)的1/20、1/50及1/100,给药体积为10ml/kg BW,每天腹腔注射,连续3天。实验第4天,处死小鼠,测量子宫脏器系数、子宫上皮细胞高度及子宫雌激素受体(ER)表达。结果氯化镉1/50LD50、醋酸铅1/50LD50及联合作用1/100LD50剂量组能显著改变子宫脏器系数;氯化镉各剂量组、醋酸铅1/20LD50剂量组和联合作用的1/20LD50、1/50LD50剂量组可引起未成年雌性小鼠子宫上皮细胞高度的显著增加,即引起子宫内膜的明显增生;除氯化镉和乐果的1/20LD50、1/50LD50剂量组其他所有实验组与空白对照比较均能显著增强雌激素受体(ER)的表达。结论镉、铅、乐果和对硫磷对未成年雌性小鼠雌激素样联合作用与单因素作用存在显著差异,且在不同剂量不同指标中表现不尽相同。     

Keeping the right time in space: importance of circadian clock and sleep for physiology and performance of astronauts

The circadian clock and sleep are essential for human physiology and behavior; deregulation of circadian rhythms impairs health and performance. Circadian clocks and sleep evolved to adapt to Earth’s environment, which is characterized by a 24-hour light–dark cycle. Changes in gravity load, lighting and work schedules during spaceflight missions can impact circadian clocks and disrupt sleep, in turn jeopardizing the mood, cognition and performance of orbiting astronauts. In this review, we summarize our understanding of both the influence of the space environment on the circadian timing system and sleep and the impact of these changes on astronaut physiology and performance.