Clinical equivalence assessment of T2 synthesized pediatric brain magnetic resonance imaging

Background and purposeAutomated synthetic magnetic resonance imaging (MRI) provides qualitative, weighted image contrasts as well as quantitative information from one scan and is well-suited for various applications such as analysis of white matter disorders. However, the synthesized contrasts have been poorly evaluated in pediatric applications. The purpose of this study was to compare the image quality of synthetic T2 to conventional turbo spin-echo (TSE) T2 in pediatric brain MRI.Materials and methodsThis was a mono-center prospective study. Synthetic and conventional MRI acquisitions at 1.5 Tesla were performed for each patient during the same session using a prototype accelerated T2 mapping sequence package (TA_synthetic = 3:07 min, TA_conventional = 2:33 min). Image sets were blindly and randomly analyzed by pediatric neuroradiologists. Global image quality, morphologic legibility of standard structures and artifacts were assessed using a 4-point Likert scale. Inter-observer kappa agreements were calculated. The capability of the synthesized contrasts and conventional TSE T2 to discern normal and pathologic cases was evaluated.ResultsSixty patients were included. The overall diagnostic quality of the synthesized contrasts was non-inferior to conventional imaging scale (P = 0.06). There was no significant difference in the legibility of normal and pathological anatomic structures of synthetized and conventional TSE T2 (all P > 0.05) as well as for artifacts except for phase encoding (P = 0.008). Inter-observer agreement was good to almost perfect (kappa between 0.66 and 1).ConclusionsT2 synthesized contrasts, which also provides quantitative T2 information that could be useful, could be suggested as an equivalent technique in pediatric neuro-imaging, compared to conventional TSE T2.     

间断头高位与站立位可对抗模拟失重大鼠股动脉收缩反应性的降低

目的 观察和比较头高位（HUT）与站立位（STD）对模拟失重所致股动脉收缩反应性降低的影响及其时间依赖性。方法 49只雄笥SD大鼠随机分为对照组、模拟失重组、头高位2h组、头高位4h组、站立位1h组、站立位2h组和站立位4h组，每组7只。利用离体股动脉血管环技术测定7组大鼠股动脉对血管收缩剂的反应。结果 悬吊大鼠股动脉血管环对KCl和苯肾上腺素的收缩反应性显降低，头高位与站立位组大鼠的股动脉血管环对KCl和苯肾上腺素收缩反应均较悬吊组显增强，与同步对照组相比已无显差异。结论 4wk模拟失重可以使大鼠股动脉的收缩反应性降低，而头高位与站立位均可对抗大鼠股动脉的收缩反应性的降低，这些结果提示间断性人工重力可对抗失重对血管所产生的影响。     

基于仿真胸腔生物力学特性的新型模拟人在心肺复苏教学训练中的应用

目的　采用多弹簧组变阻尼结构模拟真实的人体胸腔生物力学特性,结合原有的电子反馈系统设计出一款基于仿真胸腔生物力学特性的新型心肺复苏训练模拟人,并测试其在心肺复苏（cardiopulmonary resuscitation,CPR）教学中的应用效果。方法　选取海军军医大学2019级五年制临床医学专业的60名本科学员作为研究对象,分成试验组和对照组,每组30名。对照组使用传统模拟人进行CPR培训,试验组在对照组基础上应用新型模拟人进行CPR培训。培训结束后对两组人员分别进行单项技能考核。单项技能主要是徒手进行心肺复苏操作,包括人工呼吸与胸外按压。比较两组的CPR理论和技能操作考核情况及对教学方法的满意度。采用SPSS 23.0进行统计学分析。结果　试验组学员单项技能操作考核成绩为（54.33±3.09）分,优于对照组学员（52.33±3.08）分,差异有统计学意义（P <0.05）。调查问卷显示,试验组学员对于新型模拟人的教学训练效果评价较好。结论　新型心肺复苏模拟人相比传统模拟人,更能够模拟真实人体的心肺复苏急救场景,可以有效提高医学学员规范化培训CPR教学效果,助力我国心肺急救技术的标准化、规范化、普及化工作。     

模拟教学联合心理暗示在耳鼻咽喉头颈外科住培模拟教学中的应用

目的 分析模拟教学联合心理暗示在耳鼻咽喉头颈外科住培模拟教学中的应用价值。方法 选取于清华大学附属北京清华长庚医院耳鼻咽喉头颈外科进行住培的36例住培医师,按不同教学模式将其分为研究组（n=20,模拟教学联合心理暗示）与对照组（n=16,传统教学）。比较两组住培医师考核成绩、综合能力、教学效果及教学满意度。采用SPSS 22.0进行t检验和卡方检验。结果 带教后,两组住培医师理论考试、技能考核成绩、学习兴趣、自学能力、沟通能力及临床诊疗水平评分均较带教前上升,且研究组上升程度明显优于对照组（P<0.05）。研究组兴趣程度、难易程度、可参与性、掌握程度评分均明显高于对照组（P<0.05）。研究组住培医师教学总满意度为95.00%,明显高于对照组的68.75%（P<0.05）。结论 模拟教学联合心理暗示在耳鼻咽喉头颈外科住培教学中可提高学员理论知识、技能操作水平、综合能力及教学水平,且学员对该教学方法满意度高。     

C/C复合材料表面等离子喷涂HA涂层在SBF中的试验

目的 探讨不同模拟体液对HA涂层体外生物学行为的影响。方法采用等离子体喷涂法,在碳／碳复合材料表面制备HA涂层,并对涂层进行了热处理。利用X射线衍射仪(X-ray diffraction)、扫描电子显微镜(Scanning electron microscopy)等检测手段,分析该涂层的物相和形貌,观察HA涂层在模拟体液中的影响。结果XRD检测结果表明,在模拟体液浸泡过程中,涂层的主要组成相的相对含量和结晶度不断发生变化。由SEM分析结果可知,在浸泡过程中,内送粉方式下制得的HA涂层的表面沉积物呈现近似网状的结构。同时,在Ringer溶液中,可以观察到HA涂层溶解痕迹。结论通过适当的热处理可以恢复HA的结构完整性,同时提高涂层的结晶度。     

太空发育鸡胚的前庭感受器细胞形态学研究

为了探讨太空微重力对鸡胚前庭感觉上皮细胞的形态发育的影响 ,选取在航天飞机 (STS-2 9)发育鸡胚和地面发育鸡胚各两只 ,利用计算机显微测量技术分别测量椭圆囊和球囊的毛细胞、支持细胞核的切面面积、周长、形状系数。太空发育鸡胚的球囊支持细胞核的切面面积、周长显著大于地面组 ,形状系数无差异 ;太空发育鸡胚的椭圆囊支持细胞核的切面面积、周长、形状系数以及椭圆囊和球囊毛细胞的切面面积、周长与地面发育鸡胚相比无明显差异。微重力可能对球囊支持细胞核的体积发育有影响 ,对椭圆囊和球囊的毛细胞以及椭圆囊支持细胞核的形态发育无影响。     

尾部悬吊大鼠胸主动脉、肺动脉超微结构变化的动态观察

目的观察模拟微重力时大小循环动脉血管超微结构重塑随时间变化的差异,为微重力后立位耐力降低的机制研究积累资料。方法用透射电镜观察-30°尾部悬吊7d(TS7组)、14d(TS14组)及对照组大鼠胸主动脉、肺动脉壁超微结构的变化。结果TS7组胸主动脉内皮细胞表面出现绒毛状突起,部分线粒体空泡变性,内皮下基膜有分层,内弹力板较厚,且厚度不均匀,内弹力板下出现大量的胶原纤维;TS14组胸主动脉内皮细胞变性较明显,部分内皮细胞基质致密化,基膜复层化,内弹力板有破碎,弹力纤维增多。TS7组肺动脉部分内皮细胞突起,细胞内出现脂滴,内皮细胞基膜出现分层状改变,弹力板变薄、断裂,其下方可见收缩型平滑肌及合成型平滑肌细胞;TS14组肺动脉内皮细胞空泡变性较明显,内弹力板未见明显改变,弹力板内外均可见较多的胶原纤维和弹力纤维,内弹力板下方以收缩型平滑肌为主。结论TS7组大鼠胸主动脉和肺动脉出现损伤和增殖并存,以肺动脉较明显;TS14组肺动脉趋于形成新的稳定结构,而胸主动脉新稳定结构还未形成。模拟微重力时大小循环血管发生了结构重塑,大小循环血管重塑的时间过程不同归因于模拟微重力初期由下体转移而来的体液进入大小循环高峰期的时间差。     

模拟退火算法在图像配准中的应用

近年来 ,脑功能成像技术发展迅速 ,已在脑科学研究中占有重要地位。研究中通常需要将同一被试的多种模式成像结果或同一模式的时间序列结果结合起来分析 ,首先要解决的问题就是几幅图像的严格对齐问题 ,即所谓的图像配准。在模拟退火算法和其它工作的基础之上 ,较好的解决了图像配准中的连续变量全局优化问题 ,通过基于点的配准方法 ,实现了时间序列脑功能图像的高精度配准。     

Effects of 84‐days of bedrest and resistance training on single muscle fibre myosin heavy chain distribution in human vastus lateralis and soleus muscles

Aim: This investigation determined the effects of 84 days of bedrest on the composition of myosin heavy chain (MHC) in single skeletal muscle fibres with and without a resistance‐training countermeasure programme. Methods: Muscle biopsies were obtained from the m. vastus lateralis (VL) and m. soleus (SOL) before and after 84 days of bedrest. While control (BR) subjects (VL n = 9; SOL n = 3) refrained from exercise, BRE subjects (VL n = 8; SOL n = 3) performed knee extensor and plantar flexor resistance exercise every third day. Approximately 110 fibres per sample were analysed for MHC composition using SDS‐PAGE. Results: BR–VL had 16 and 14% decreases (P < 0.05) in MHC I and IIa fibres, respectively. There were 10% increases (P < 0.05) in MHC I/IIa, IIa/IIx, I/IIa/IIx, and a ～30% increase (P < 0.05) in total hybrid fibres. BRE‐VL showed a 15% reduction (P < 0.05) in MHC I fibres, no change in MHC IIa fibres, and a 13% increase (P < 0.05) in total hybrids. BR–SOL had a 19% decrease (P < 0.05) in MHC I fibres with a 22% increase in total hybrids. BRE–SOL showed no change in MHC composition across all fibre types. Conclusion: These data suggest that the exercise countermeasures programme prevented MHC shifts in the SOL and mitigated MHC shifts in the VL. Furthermore, in the VL it appears that the resistance training programme employed in this investigation during bedrest, emphasized the use of MHC IIa phenotype muscle fibres.     

Calbindins decreased after space flight

Exposure of the body to microgravity during space flight causes a series of well-documented changes in Ca²⁺ metabolism, yet the cellular and molecular mechanisms leading to these changes are poorly understood. Calbindins, vitamin D-dependent Ca²⁺ binding proteins, are believed to have a significant role in maintaining cellular Ca²⁺ homeostasis. In this study, we used biochemical and immunocytochemical approaches to analyze the expression of calbinding-D_28k and calbindin-D_9k in kidneys, small intestine, and pancreas of rats flown for 9 d aboard the space shuttle. The effects of microgravity on calbindins in rats from space were compared with synchronous Animal Enclosure Module controls, modeled weightlessness animals (tail suspension), and their controls. Exposure to microgravity resulted in a significant and sustained decrease in calbindin-D_28k content in the kidney and calbinding-D_9k in the small intestine of flight animals, as measured by enzyme-linked immunosorbent assay (ELISA). Modeled weightlessness animals exhibited a similar decrease in calbindins by ELISA. Immunocytochemistry (ICC) in combination with quantitative computer image analysis was used to measurein situ the expression of calbindins in the kidney and the small intestine, and the expression of insulin in pancreas. There was a large decrease of immunoreactivity in renal distal tubular cell-associated calbindin-D_28k and in intestinal absorptive cell-associated calbindin-D_9k of space flight and modeled weightlessness animals compared with matched controls. No consistent difference in pancreatic insulin immunoreactivity between space flight, modeled weightlessness, and controls was observed. Regression analysis of results obtained by quantitative ICC and ELISA for space flight, modeled weightlessness animals, and their controls demonstrated a significant correlation. These findings after a short-term exposure to microgravity or modeled weightlessness suggest that a decreased expression of calbindins may contribute to the disorders of Ca²⁺ metabolism induced by space flight.