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61.
62.
Superparamagnetic iron oxide-enhanced MR imaging: pulse sequence optimization for detection of liver cancer 总被引:3,自引:0,他引:3
Fretz CJ; Elizondo G; Weissleder R; Hahn PF; Stark DD; Ferrucci JT Jr 《Radiology》1989,172(2):393-397
The effects of magnetic resonance (MR) pulse sequences and timing parameters on tumor-liver contrast were studied in an animal model of metastatic liver cancer. Six spin-echo (SE), three inversion-recovery (IR), and four gradient-echo (GRE) sequences were evaluated at 0.6 T before and after injection of super-paramagnetic iron oxide. GRE techniques, irrespective of echo time and flip angle, showed the greatest change in signal intensity (enhancement) of the liver after administration of iron oxide. Single-acquisition GRE sequences (16 seconds) matched the contrast-to-noise ratio (C/N) performance of the most effective 6.4-minute SE sequences. Multiexcitation GRE sequences showed tumor-liver C/Ns per unit time that were significantly (P less than .05) higher than those achieved with SE and IR sequences. GRE sequences, which recruit intravoxel dephasing as an additional source of transverse relaxation enhancement (T2*), show a higher C/N per unit time and in this respect seem superior to SE and IR sequences for MR imaging with superparamagnetic iron oxide. 相似文献
63.
TEELUCKSINGH S; STEER CR; THOMPSON CJ; SECKL JR; DOUGLAS NJ; EDWARDS CRW 《QJM : monthly journal of the Association of Physicians》1991,78(2):185-190
We describe a young man who developed extensive hypothalamicdysfunction including diabetes insipidus, adipsia, hyperprolactinaemia,and poikiliothermia together with central sleep apnoea followingexposure to toluene. 相似文献
64.
目的:临床局部辐射条件下会造成非辐射区域组织及细胞功能损害,最为突出的是对造血功能的影响。实验建立60Coγ射线左半身辐射动物模型,观察局部电离辐射对其非辐射区域骨髓巨核细胞的影响。方法:实验于2003-10/2005-03在解放军第三军医大学辐照中心和全军复合伤研究所完成。①实验动物:6~8周龄SPF级雄性昆明小鼠180只,随机数字表法分为正常对照组、全身辐射组、左半身辐射组、全身屏蔽辐射组,45只/组。②实验方法:全身辐射组小鼠固定于辐射架内;左半身辐射组小鼠麻醉后固定体位,用铅砖屏蔽右半身;全身屏蔽辐射组小鼠麻醉固定体位,用铅砖屏蔽全身。以60Coγ射线一次性辐射,剂量率68.46cGy/min。正常对照组不作任何干预。③实验评估:辐射后不同时相检测小鼠血清丙二醛含量及超氧化物歧化酶活性变化,计数外周血血小板,检测骨髓巨核祖细胞集落形成单位,观察骨髓组织病理改变及CD41a、CD61的表达。结果:全身辐射组第8天死亡2只,第9天死亡4只,其余各组无脱失。①外周血血小板计数:辐射后第2,7天,左半身辐射组外周血血小板数量显著低于正常对照组(P<0.01),但高于全身辐射组(P<0.01)。②血清丙二醛含量及超氧化物歧化酶活性变化:辐射后第2,9天,左半身辐射组血清丙二醛含量显著高于正常对照组(P<0.01),低于全身辐射组(P<0.01);血清超氧化物歧化酶活性显著低于正常对照组(P<0.01),高于全身辐射组(P<0.01)。③骨髓巨核祖细胞集落形成单位的变化:与正常对照组比较,辐射后6h左半身辐射组非辐射侧的巨核祖细胞集落形成单位显著降低(P<0.01),高于全身辐射组及左半身辐射组(P<0.01)。④骨髓组织病理改变:正常对照组有核细胞比例较高,分布均匀,并见多量散在分布的细胞龛;辐射2d后,左半身辐射组非辐射侧骨髓有核细胞较正常对照组减少,但好于全身辐射组、左半身辐射组。⑤骨髓CD41a及CD61表达的变化:辐射后2d与正常对照组比较,左半身辐射组非辐射侧骨髓CD41a及CD61阳性细胞数和相对荧光强度均显著降低(P<0.01),但高于全身辐射组、左半身辐射组(P<0.01)。结论:局部电离辐射作用后,可导致小鼠非辐射区域骨髓巨核细胞增殖能力降低,血小板减少,产生功能障碍。氧自由基激活可能参与了该损伤过程。 相似文献
65.
目的:认识影响大学生骨密度的各种生活因子,以便指导大学生提高骨密度,预防骨质疏松症的发生。方法:于2005-07/08选择延边大学医学院在校生自愿者638人,其中朝鲜族男生130人,朝鲜族女生110人,汉族男生196人,汉族女生202人。采用问卷调查方式,调查内容包括被调查者的自然状况、饮食、运动情况及其他与骨密度有关的生活方式。同时对调查对象进行右足跟骨骨密度测定。综合骨评价值=透过指数×超声波传导速度。结果:纳入受试对象638人,均进入结果分析。①汉族男生的综合骨评价值明显低于朝鲜族男生(分别为3.0±0.4,3.2±0.4,P<0.05),女生不存在民族差异。②男生的生活方式与骨密度的关系:注意平衡膳食及摄取充足的豆制品有利于骨密度提高(t=10.693,P<0.01;t=2.483,P<0.05);进行定期的运动(足球、篮球、排球、网球等球类运动和使用健身器)以及中学时期除了上体育课之外进行过体育运动能明显提高骨密度(t=10.693,P<0.01;t=1.998,P<0.05);有骨折史的学生骨密度明显低于无骨折史的学生(t=2.028,P<0.05)。③女生的生活方式与骨密度的关系:经常不吃早餐的学生骨密度低于按时吃早餐的学生(t=6.600,P<0.01);注意均衡饮食和进行定期运动的学生骨密度明显高于不注意均衡饮食和不做定期运动的学生(t=4.149,P<0.01;t=2.992,P<0.01)。③女生中也表现出有骨折史的学生骨密度显著低于无骨折史的学生(t=1.965,P<0.05)。结论:影响大学生骨密度的因素有骨折史、定期运动、均衡饮食、豆制品摄取。 相似文献
66.
目的:聚甲基丙烯酸甲酯和磷酸钙骨水泥作为经皮椎体后凸成形术填充物,应用三维有限元分析法比较两种材料治疗骨质疏松性椎体压缩骨折的生物学效应。方法:实验于2003-03/09在南通医学院第一附属医院骨科和上海大学上海生物力学工程研究所合作完成。①利用WD-5型万能材料机测量聚甲基丙烯酸甲酯和磷酸钙骨水泥铸件力学性质。②选取骨质疏松患者1例(患者知情同意),排除其他疾患,应用CT扫描技术、图形数字化方法获取胸腰段的三维坐标,利用ANSYS5.0有限元分析软件等工具建立骨质疏松患者胸腰段的三维有限元模型。③模拟L1经皮椎体后凸成形术,对其和相邻椎体及椎间盘的负荷传递、应力、位移等进行分析。结果:①获取了精确的T11 ̄L3的多排螺旋CT扫描断层影像数据,经ANSYS5.0软件处理后得到4718个节点,1642个薄极单元,4495个八节点等参单元的骨质疏松患者胸腰段三维有限元力学模型。②采用聚甲基丙烯酸甲酯作为经皮椎体后凸成形术的填充物,比骨质疏松椎体应力增加了近15%。后部结构的应力平均增加13.2%,其中椎弓根增加5.9%,峡部增加6.25%,关节点增加27.6%。聚甲基丙烯酸甲酯在稳定椎体、恢复强度和刚度的同时,可能使其后部结构及相邻腰椎出现应力集中现象。③采用磷酸钙骨水泥作为椎体成形术填充物,比骨质疏松椎体应力平均增加了7%,应力集中现象明显小于聚甲基丙烯酸甲酯。结论:三维有限元力学分析表明两种材料均提高了椎体的抗变形能力,有利于椎体功能的重建。与聚甲基丙烯酸甲酯相比,磷酸钙骨水泥能减少成形椎体和相邻椎体之间的应力梯度,从长远看,能减少椎体退变和相邻椎体骨折的机会。 相似文献
67.
W Nadia H Koek Joyce B van Meurs Bram CJ van der Eerden Fernando Rivadeneira M Carola Zillikens Albert Hofman Barbara Obermayer‐Pietsch Paul Lips Huibert A Pols André G Uitterlinden Johannes PTM van Leeuwen 《Journal of bone and mineral research》2010,25(9):1980-1987
The C‐variant of a T‐13910C polymorphism (rs4988235; NT_022135.15:g.25316568G > A) upstream of the lactase phlorizin hydrolase (LPH) gene causes lactose intolerance. Association studies with differences in bone parameters and fracture risk have been inconclusive. The objective of this study was to examine the association of LPH rs4988235 with body height and bone parameters and calcium homeostasis in two elderly populations of Dutch Caucasians and assess interaction with vitamin D receptor (VDR) polymorphisms. Genotyping of LPH and VDR polymorphisms was performed in 6367 individuals from the Rotterdam Study and 844 from the Longitudinal Aging Study Amsterdam (LASA). Associations with age, height, weight, bone mineral density (BMD), skeletal morphometric parameters and serum vitamin D and calcium levels, and dietary calcium intake were assessed using ANOVA or analysis of covariance, and allele dose effect was assessed using linear regression analysis. Fracture risk was analyzed using Cox's proportional hazard regression analysis. Associations with body height (p = 2.7 × 10?8) and vertebral area (p = .048) found in the Rotterdam Study were explained by population stratification, as assessed by principal‐component analyses, and disappeared after additional adjustments. No associations with femoral neck or lumbar spine BMD or with fracture risk were detected. Calcium intake and serum ionized serum calcium were significantly lower in C‐homozygotes (p = 9.2 × 10?7, p = .02, respectively). For none of the parameters studied was interaction between the T‐13910C polymorphism and VDR block 5 haplotype 1 observed. We show that the C allele of the T‐13910C polymorphism causing lactose intolerance is associated with lower dietary calcium intake and serum calcium levels but not with BMD or fractures. The associations observed with height and vertebral area were the result of population stratification. This demonstrates the impact of population stratification and urges researchers to carefully take this into account in genetic associations, in particular, in dietary intake–related phenotypes, of which LPH and lactose intolerance are a strong example. © 2010 American Society for Bone and Mineral Research 相似文献
68.
CJ Chantry JS Cervia MD Hughes C Alvero J Hodge P Borum J Moye Jr. for the PACTG Team 《HIV medicine》2010,11(9):573-583
Objectives
The aim of the study was to describe growth and body composition changes in HIV‐positive children after they had initiated or changed antiretroviral therapy (ART) and to correlate these with viral, immune and treatment parameters.Methods
Ninety‐seven prepubertal HIV‐positive children were observed over 48 weeks upon beginning or changing ART. Anthropometry and bioelectrical impedance analysis results were compared with results from the National Health and Nutrition Examination Survey 1999–2002 (NHANES) to generate z‐scores and with results for HIV‐exposed, uninfected children from the Women and Infants Transmission Study (WITS). Multivariate analysis was used to evaluate associations between growth and body composition and disease parameters.Results
All baseline lean and fat mass measures were below those of controls from NHANES. Weight, height and fat free mass (FFM) index (FFM/height2) z‐scores increased over time (P=0.004, 0.037 and 0.027, respectively) and the waist:height ratio z‐score decreased (P=0.045), but body mass index and per cent body fat z‐scores did not change. Measures did not increase more than in uninfected WITS controls. In multivariate analysis, baseline height, mid‐thigh circumference and FFM z‐scores related to CD4 percentage (P=0.029, P=0.008 and 0.020, respectively) and change in FFM and FFM index z‐scores to CD4 percentage increase (P=0.010 and 0.011, respectively). Compared with WITS controls, baseline differences in height and mid‐thigh muscle circumference were also associated with CD4 percentage. Case–control differences in change in both subscapular skinfold (SSF) thickness and the SSF:triceps skinfold ratio were inversely associated with viral suppression. No measures related to ART class(es) at baseline or over time.Conclusions
In these HIV‐positive children, beginning or changing ART was associated with improved growth and lean body mass (LBM), as indicated by FFM index. Height and LBM related to CD4 percentage at baseline and over time. Altered fat distribution and greater central adiposity were associated with detectable virus but not ART class(es) received. 相似文献69.
70.