小间隙对深部X线治疗体表剂量的影响

[目的]了解用深部X线治疗时 ,限光筒端面与体表之间空隙造成的体表剂量变化。[方法]用半导体电离室和热释光剂量仪测出不同射线质、射野尺寸、源皮距(SSD),以及斜入射存在条件下 ,间隙从1mm～15mm变化时体表剂量改变情况。并用三维水箱扫描出PDD的变化。[结果]取得了不同因素影响下剂量改变情况的数据 ,并分析了以上因素对剂量改变的影响。[结论]当间隙从1mm～15mm变化时 ,体表欠剂量最大可达12 %左右 ,射野尺寸 ,射线质对剂量变化有一定影响 ,SSD的影响可忽略 ,当间隙和斜入射同时存在时 ,欠剂量情况有所改善。小空隙对PDD影响可忽略。     

Plasticity-induced damage layer is a precursor to wear in radiation-cross-linked UHMWPE acetabular components for total hip replacement. Ultra-high-molecular-weight polyethylene.

The mechanism for the improved wear resistance of cross-linked ultra-high-molecular-weight polyethylene (UHMWPE) remains unclear. This study investigated the effect of cross-linking achieved by gamma irradiation in nitrogen on the tribologic, mechanical, and morphologic properties of UHMWPE. The goal of this study was to relate UHMWPE properties to the wear mechanism in acetabular-bearing inserts. Wear simulation of acetabular liners was followed by detailed characterization of the mechanical behavior and crystalline morphology at the articulating surface. The wear rate was determined to be directly related to the ductility, toughness, and strain-hardening behavior of the UHMWPE. The concept of a plasticity-induced damage layer is introduced to explain the near-surface orientation of the crystalline lamellae observed in the wear-tested acetabular liners. Cross-linking reduces abrasive wear of acetabular components by substantially reducing--but not eliminating--the plasticity-induced damage layer that precedes abrasive wear.     

Excessive uterine activity accompanying induced labor

OBJECTIVE: To estimate the incidence and timing of excessive uterine activity accompanying induction of labor with misoprostol using different routes (oral or vaginal) and forms (intact tablet or crushed) and to compare these with dinoprostone gel, oxytocin, and spontaneous labor. METHODS: This retrospective cohort study included 519 women at term who had labor induced and 86 women at term in spontaneous labor. Induction agents included misoprostol, dinoprostone, or oxytocin. Fetal heart rate and uterine activity tracings were analyzed independently by three maternal-fetal medicine physicians. The diagnosis of tachysystole or hyperstimulation required the agreement of two or more reviewers. RESULTS: The incidence of tachysystole was highest with misoprostol administered by vaginal tablet (misoprostol vaginal tablet 50 microg every 4 hours, 48.6%; vaginal tablet crushed 50 microg and suspended in hydroxyethyl gel every 4 hours, 30.7%, P =.009; oral tablet 50 microg every 4 hours, 22.2%, P =.001; oral tablet crushed 50 microg every 4 hours, 15.5%, P <.001; dinoprostone gel, 33.0%, P =.022; intravenous oxytocin, 30.2%, P =.027; and spontaneous onset of labor, 23.3%, P <.001). Hyperstimulation occurred more often with dinoprostone gel (16.5%) than with other forms of induction or spontaneous labor. Hyperstimulation occurred significantly more often with vaginal misoprostol crushed tablet (7.9%) and vaginal misoprostol intact tablet (7.6%) than with crushed oral misoprostol (1.0%) (P =.016 and.018, respectively). There was a shorter time to tachysystole with increasing doses of vaginal misoprostol tablet (P =.01). CONCLUSION: The incidence of tachysystole and hyperstimulation, and time to tachysystole, varied depending on the route and form of misoprostol given.     

开胸和腔内修复术治疗外伤性主动脉破裂

目的 总结外伤性主动脉破裂的救治经验.方法 2001年7月-2008年12月共收治17例外伤性主动脉破裂患者.其中1例因入院后1 h死于失血性休克未行手术治疗;9例施行开胸手术,在全身麻醉下双腔气管插管,体外循环采用股动静脉插管、心脏不停跳部分转流,转流时间35～139 min,主动脉阻断时间25～87 min.7例手术成功者中1例行主动脉直接修补,6例行人工血管置换.其余7例施行腔内修复术,在全身麻醉或局部麻醉下经右侧股总动脉入路将覆膜支架置放于主动脉破裂处.结果 1例未手术者死于失血性休克.开胸手术组7例治愈,2例死亡;手术时间100～180 min;7例治愈者均获得随访,随访时间2～6年,随访期内无死亡.腔内修复组7例全部治愈,手术时间50～70 min;7例均获得随访,随访时间3～14个月,随访期内无死亡.6例术后2～5个月复查CT见主动脉周围无造影剂外溢,主动脉周围血肿消失.结论腔内修复术治疗外伤性主动脉破裂安全、简单、效果明确.但选择开胸手术还是腔内修复术要根据患者合并多发伤的情况、医院的设备条件及术者的技术熟练程度来决定.     

骨肿瘤在低场强MR强化扫描的诊断价值与临床研究

ＭＲ平扫在骨骼系统中的诊断价值已得到充分肯定。Ｇｄ-ＤＴＰＡ强化扫描又拓宽了相应的应用范围,获得了平扫难以满足的信息,解决了平扫中未能很好解决的一些难点,进一步提高病变组织的分辨率［１］。Ｇｄ-ＤＴＰＡ是目前ＭＲ强化扫描的主要使用药物,因为钆盐含有７个不成...     

中华芦荟多糖提取和粗多糖中总糖的含量测定

1仪器与药品1.1仪器贝克曼高速冷却离心机,752型可见分光光度计,旋转蒸发仪和榨汁机。1.2药品不同产地的中华芦荟:A产地海南;B产地云南;葡萄糖,中国医药集团上海化学试剂公司,其他试剂均为分析纯。      

Application of deep learning to understand resilience to Alzheimer's disease pathology

People who have Alzheimer''s disease neuropathologic change (ADNC) typically associated with dementia but not the associated cognitive decline can be considered to be “resilient” to the effects of ADNC. We have previously reported lower neocortical levels of hyperphosphorylated tau (pTau) and less limbic‐predominant age‐related TDP‐43 encephalopathy neuropathologic change (LATE‐NC) in the resilient participants compared to those with dementia and similar ADNC as determined by current NIA‐AA recommendations using traditional semi‐quantitative assessments of amyloid β and pathological tau burden. To better understand differences between AD‐dementia and resilient participants, we developed and applied a deep learning approach to analyze the neuropathology of 14 brain donors from the Adult Changes in Thought study, including seven stringently defined resilient participants and seven age‐matched AD‐dementia controls. We created two novel, fully automated deep learning algorithms to quantify the level of phosphorylated TDP‐43 (pTDP‐43) and pTau in whole slide imaging. The models performed better than traditional techniques for quantifying pTDP‐43 and pTau. The second model was able to segment lesions staining for pTau into neurofibrillary tangles (NFTs) and tau neurites (neuronal processes positive for pTau). Both groups had similar quantities of pTau localizing to neurites, but the pTau burden associated with NFTs in the resilient group was significantly lower compared to the group with dementia. These results validate use of deep learning approaches to quantify clinically relevant microscopic characteristics from neuropathology workups. These results also suggest that the burden of NFTs is more strongly associated with cognitive impairment than the more diffuse neuritic tau commonly seen with tangle pathology and suggest that additional factors may underlie resilience mechanisms defined by traditional means.     

RP-HPLC双波长梯度洗脱法同时测定通塞脉微丸中阿魏酸、甘草素、肉桂酸、哈巴俄苷的含量

目的建立以RP-HPLC双波长法同时测定通塞脉微丸中阿魏酸、甘草素、肉桂酸、哈巴俄苷4个有效成分含量的方法。方法采用Packing Material HederaODS-2柱(250 mm×4.6 mm,5μm)柱,以乙腈-1.0%磷酸水为流动相,梯度洗脱;双波长检测,λ_1=320 nm,λ_2=276 nm;流速为1.0 mL·min~(-1);柱温30℃;结果阿魏酸、甘草素、肉桂酸和哈巴俄苷分别在32.04～160.2、12.2～61.0、12.24～61.2、11.88～59.4μg·mL~(-1)内有良好线性关系,r≥0.9995。4个份均能达到基线分离,各组分的平均回收率在97.30%～100.94%之间。结论本方法简便,准确,重现性好,可作为该制剂质量控制的方法。