辐射等效假人数字化建模方法

辐射等效假人主要依靠手工制作,生产周期长、加工精度低,无法满足参数化设计的要求,而通过建立辐射等效假人数字化模型可以有效解决这些问题。以“成都剂量体模”CT扫描切片集为基础,建立辐射等效假人的扫描坐标系[os-xs,ys,zs],利用Mimics软件重建人体主要器官和组织的三维模型;以器官的几何中心点为坐标系原点,根据器官的“特征点”建立器官局部坐标系[(oJ-xJ,yJ,zJ)],利用器官“特征点”在扫描坐标系和局部坐标系的坐标值,计算两个坐标系的变换矩阵;根据人体解剖学方位建立辐射等效假人的人体坐标系[(or-xr,yr,zr)],利用“控制点”在扫描坐标系与人体坐标系中的坐标值计算扫描坐标系与人体坐标系的变换矩阵,进而推导出器官局部坐标系与人体坐标系的变换矩阵。至此可以得到不同器官在人体坐标系中的几何参数,包括器官几何中心点坐标值以及局部坐标系与人体坐标系的旋转角。根据不同器官和组织的三维模型及其几何参数在pro/E软件中建立辐射等效假人数字化模型。建立辐射等效假人数字化模型可以实现辐射等效假人的数字化设计和制造,提高加工精度,缩短生产周期,并为辐射仿真假人的参数化设计打下基础,具有重要的理论意义和实用价值。     

Key role of heparan sulfate chains in assembly of anchoring complex at the dermal-epidermal junction

Epidermal basement membrane forms anchoring complex composed of hemidesmosomes, anchoring filaments, lamina densa and anchoring fibrils to link epidermis to dermis. However, the anchoring complex is rarely formed in skin equivalent models, probably because of degradation of extracellular matrix (ECM) proteins and heparan sulfate chains by matrix metalloproteinases (MMPs) and heparanase, respectively. To explore the roles of ECM proteins and heparan sulfate in anchoring complex assembly, we used specific inhibitors of MMPs and heparanase, and the formation of anchoring complex was analysed in terms of polarized deposition of collagen VII, BP180 and β4 integrin at the dermal-epidermal junction (DEJ) by means of immunohistochemistry and transmission electron microscopy (TEM). The deposition of collagen VII was polarized to the basal side by the addition of MMP inhibitor, and the staining intensity was increased by combined treatment with MMP inhibitor and heparanase inhibitor, which enhanced anchoring fibril formation as observed by TEM. BP180 was polarized to the basal side by heparanase inhibitor, which protects HS chains, but not by MMP inhibitor. MMP inhibitor improved the polarization of β4 integrin. Hemidesmosomes were formed in the presence of each inhibitor, as observed by TEM, and formation was greatly enhanced by the combined treatment. These findings suggest that heparan sulfate chains, in addition to ECM proteins at the DEJ, play an important role in the assembly of anchoring complex, especially hemidesmosomes and anchoring fibrils.     

混合MOM/FDTD电磁分析方法及其在MR射频线圈设计中的应用

研究的目的在于增强磁共振射频线圈仿真的真实性,提高射频线圈设计水平,从而提高线圈的成像质量。充分利用矩量法（MOM）在计算复杂结构线圈上电流分布的优势,以及时域有限差分（FDTD）方法在仿真人体模型等复杂的不均匀电磁介质中的优势,通过惠更斯等效面将MOM和FDTD有机地结合到一起,形成混合MOM/FDTD射频线圈设计方法,并提出一种新的真实人体电磁模型建立方法,融入到混合方法中,充分考虑线圈与真实人体组织之间复杂的电磁相互作用。由该方法设计的原型线圈扫描图像的信噪比达到193.4dB,相比先前未考虑人体与线圈之间作用的方法,所以得到的图像信噪比提高了38.7 dB,从而验证了仿真设计的正确性。     

Influence of heparan sulfate chains in proteoglycan at the dermal-epidermal junction on epidermal homeostasis

Basement membrane (BM) plays important roles in skin morphogenesis and homeostasis by controlling dermal-epidermal interactions. However, it remains unclear whether heparan sulfate (HS) chains of proteoglycan in epidermal BM contribute to epidermal homeostasis. To explore the function of HS chains at the dermal-epidermal junction (DEJ), we used a skin equivalent (SE) model. This model lacked HS at the DEJ and showed abnormal expression of the differentiation markers filaggrin and loricrin; similar changes were seen in ultraviolet B-irradiated human skin. Perlecan (core-protein of HS proteoglycan) remained localized at the DEJ in both SE and UV-irradiated human skin. Heparanase, which degrades HS, was increased in epidermis of UV-irradiated skin, compared with unirradiated skin. We found that deposition of HS at the DEJ in the SE model was markedly augmented by a synthetic heparanase inhibitor, and release of HS into conditioned medium was suppressed. The inhibitor also increased filaggrin and loricrin expression. Moreover, the recovery of HS was associated with an increase of Ki67-positive basal cells, compared with control SE cultured without inhibitor. Comparative gene expression analysis in epidermis of SE cultured in the presence and absence of heparanase inhibitor, using DNA microarrays, showed that recovery of HS was associated with increased expression of differentiation-related genes and down-regulation of degradation-enzyme-related genes. These results indicate that degradation of HS at the DEJ by heparanase impairs epidermal homeostasis in SE, leading to abnormal differentiation and proliferation behaviour. Thus, HS chains in epidermal BM appear to play an important role in epidermal homeostasis.     

Neurological examination of preterm infants at term equivalent age

BACKGROUNDS: We previously reported the neurological findings of the Dubowitz neonatal examination in a cohort of 157 low-risk preterms born between 25 and 33 weeks gestational age (GA) and examined at term equivalent age (TEA). Median and range of scores were wider than those found in term-born infants and preterms showed a different neurological behaviour in specific items. However, the cohort number was too small to draw any definitive conclusion about the distribution of findings. AIMS: We provide normative data from a low-risk cohort of 380 preterm infants; we also assess the findings and their relationship to motor outcome in preterms with major cranial ultrasound (US) abnormality. STUDY DESIGN: We assessed, at TEA, 380 low-risk preterms born <35 weeks gestation (range 25-34.9, median 29) with normal 2 year motor outcome and 85 preterm infants with major US abnormality. RESULTS: At TEA low-risk preterms had less flexor limb tone, poorer head control but better visual following than term-born infants. For 28/34 of the neurological items the range and median scores were similar across gestational ages. In infants with major US lesions the range and median scores differed from low-risk preterms in 20/34 items; 40% of infants developing a diplegia and 80% developing a tetraplegia had >7 items outside the 90th centile; all infants with >12 items outside the 90th centile developed a tetraplegia. CONCLUSIONS: We provide reference values for the neurological examination of low-risk preterms at TEA. In infants with major US abnormality the number of items outside the 90th centile was an indicator of outcome severity.     

Corneal parameters and their correlations with refractive error,axial length,anterior chamber depth and lens thickness in black South Africans

目的:收集南非健康黑人的角膜直径(CD)、曲率(ACC)和角膜中央厚度(CCT)的数据并探讨其与屈光不正等效球镜(SE)、眼轴长度(AL)、前房深度(ACD)、晶状体厚度(LT)的相关性,及三个角膜参数之间的相关性.方法:选取600例受试者,包括305例男性和295例女性(平均年龄:28.15±13.1y,年龄范围:10~66y)接受全面的眼科检查,包括验光,裂隙灯和眼底镜检查.Oculus Keratograph 4检测CD和ACC,ivue-100光学相干断层扫描检测CCT.Nidek AR-310 A自动验光仪和主观验光检测屈光不正.Nidek US-500 A超检测AL,ACD和LT.结果:由于左右眼参数评估的差异无统计学意义,此处只显示右眼的结果.角膜各项参数平均值如下:CD=11.77±0.32 mm(10.30-13.70 mm),ACC=7.88±0.29 mm(7.13~8.88 mm),CCT=493.05±33.2μm(412~590μm).CD与SE无相关性(r=0.05,P=0.24).CD与AL(r=0.58,P=0.00)、ACD(r=0.63,P=0.00)显著相关,但与LT(r=-0.40,P=0.00)呈负相关.ACC与SE(r=-0.03,P=0.48)无显著相关性.ACC与AL(r=0.40,P=0.00)呈正相关.ACC与ACD(r=0.04,P=0.56)、LT(r=-0.03,P=0.88)无显著相关性.CCT与角膜以外其他参数间无显著相关性.角膜各项参数的相关性表明,CD与ACC(r=0.71,P=0.00)、CCT(r=-0.68,P=0.00)相关.结论:CD与AL、ACD、LT相关,ACC与AL相关.CCT与角膜以外其它参数无相关性,是一个独立的因素.在角膜各项参数中,CD与ACC、CCT相关.     

Contraintes de dose en radiothérapie conformationnelle fractionnée et en radiothérapie stéréotaxique dans les hippocampes,le tronc cérébral et l’encéphale : limites et perspectives

Cerebral radiation-induced toxicities after radiotherapy (RT) of brain tumors are frequent. The protection of organs at risk (OAR) is crucial, especially for brain tumors, to preserve cognition in cancer survivors. Dose constraints of cerebral OAR used in conventional RT, radiosurgery (SRS) and stereotactic radiotherapy (SRT) are debated. In fact, they are based on historical cohorts or calculated with old mathematical models. Values of α/β ratio of cerebral OAR are also controversial leading to misestimate the equivalent dose in 2 Gy fractions or the biological equivalent dose, especially during hypofractionated RT. Although recent progresses in medical imaging, the diagnosis of radionecrosis remains difficult. In this article, we propose a large review of dose constraints used for three major cerebral OAR: the brain stem, the hippocampus and the brain.     

辅助防护设施对降低介入职业人员眼晶状体受照剂量的影响

目的 探索降低介入职业人员眼晶状体受照剂量的方法,为介入职业人员放射防护措施的改进提供数据支持。方法 选取1台配备常规辅助防护设施的介入设备和两种常见的神经介入手术类型,在辅助防护设施改造前和改造后分别测量46例和35例手术,用直读式电子剂量计读取各例介入手术中职业人员的眼晶状体受照剂量,并分析剂量变化趋势。结果 辅助防护设施改造后,全脑血管造影术、脑部栓塞术中第1术者和第2术者的左眼晶状体平均剂量分别由（9.71±10.86）和（9.51±12.34）μSv降低为（3.23±5.59）和（0.68±0.78）μSv、（14.83±19.13）和（14.12±21.76）μSv降低为（4.17±4.59）和（1.23±1.57）μSv;辅助防护设施改造前后测得的剂量差异具有统计学意义（U=-2.760和-2.467、-1.967和-2.655,P<0.05）。结论 改进介入手术中使用的辅助防护设施可以有效降低介入职业人员眼晶状体受照剂量,该方法可行性的验证为介入职业人员辐射防护效果的改善提供了新的依据。     

Exploring risk factors for stuttering development in Parkinson disease after deep brain stimulation

BackgroundStuttering is a speech disorder with disruption of verbal fluency, occasionally present in Parkinson's disease (PD). PD co-incident stuttering may either worsen or improve after Deep Brain Stimulation (DBS).MethodsSixteen out of 453 PD patients (3.5%) exhibited stuttering after DBS (PD-S) and were compared with a group of patients without stuttering (PD-NS) using non-parametric statistics.ResultsAfter DBS, stuttering worsened in 3 out of 4 patients with co-incidental stuttering. Most PD-S underwent subthalamic (STN) DBS, but 4 were implanted in the globus pallidus (GPi). Nine out of 16 PD-S (56.3%) reported a positive familial history for stuttering compared to none of the PD-NS. PD-S were mainly male (81.3%) with slight worse motor features compared to PD-NS.ConclusionHerein, we describe a group of PD patients developing stuttering after DBS and report the presence of a positive familial history for stuttering as the most relevant risk factor, suggesting a possible underlying genetic cause. The fact that stuttering occurred after either STN or GPi DBS is an argument against the impact of medication reduction on stuttering.