Development and experimental in vivo validation of mathematical modeling of laser coagulation

Most clinical procedures using the laser are based on thermal laser-tissue interactions. The treatment often consists of inducing damage of given degree and extent by heating the tissue. The aim of this study was to develop a model called HELIOS. The ability of HELIOS to predict thermal coagulation was evaluated by comparison with in vivo experimental results. Conversion of laser light in tissue was studied using the beam-broadening model. Temperature was described by the heat conduction equation solved using the finite difference method. The tissue dena-turation was modeled by the Henriques equation leading to the determination of the damage coefficient ω. For a given set of laser and tissue parameters, HELIOS makes a graphic representation of coagulation necrosis and temperature evolution in tissue. HELIOS was validated by experimental studies in vivo on rat liver using a CW Nd:YAG laser, a CO₂ laser, and an argon laser. For given sets of laser parameters, temperature measurements were performed using an infrared camera. Histological examinations were carried out on samples to quantify the depth of coagulation necrosis. Experimental data obtained in vivo were compared with those calculated using HELIOS and similar sets of parameters. The difference between the predicted temperature evolution on tissue surface and that measured by the infrared camera was < 5°C in all cases. The difference between the predicted coagulation necrosis depth and the corresponding experimental one was < 10%. In conclusion, HELIOS allows good prediction of tissue temperature and coagulation necrosis. © 1994 Wiley-Liss, inc.     

引导科技干部保持医院发展转型期间和谐心态的着力点

当前部队医院正处于发展转型期，如何引导科技干部适应转型发展新形势，经受住各种考验，始终保持理性平和、协调平衡、积极向上的心理状态，是一个不容忽视的现实问题，也是事关医院内部和谐和医院建设发展又好又快的大事，更是我们思想政治工作者必须着力认真研究、加以解决的重要课题。     

Boundary Ambiguity in Parents With Chronically Ill Children: Integrating Theory and Research

Abstract: This article integrates theory and research related to boundary ambiguity in parents of children with a chronic health condition. We propose that boundary ambiguity is a risk factor for psychological distress in these parents. Clinical applications and a case example highlight how boundary ambiguity can be assessed and managed in clinical settings by professionals working with parents with chronically ill children. Questions are provided for assessing boundary ambiguity in clinical and research settings, and implications for research are discussed.     

肿瘤潜隐期二阶段模型

从宫颈癌、大肠癌等病种的自然史抽象出一个具有时变伴随变量的潜隐期二阶段模型。潜隐期以正常状态为起点,疾病为终点;其前阶段可逆,后阶段不可逆;状态间转移速率因病人状况而异。用Markov过程描述并求解此模型,进而给出参数估计和假设检验方法。利用此模型基于江西省靖安县12年6轮宫颈癌筛查资料进行了自然史研究,并讨论了应用前景。     

Children's concepts and school learning

The apparently limited classroom application of theories of learning led to an emphasis on detailed observational studies of teachers in action which produced data concerning management and teaching techniques of more obvious use to practising teachers. However, it is argued here that research into children's conceptual development is an essential complement to this initiative. Such research demonstrates the range and quality of children's concepts in areas of learning central to the school curriculum; it describes techniques for disclosing children's concepts; and it identifies the developing pattern of children's thinking which can be used to good effect in arranging appropriate and challenging learning experiences. The importance of clarity of intentions in bringing a sense of purpose and direction to the activities of learning and teaching is also emphasized.     

Computation of Time-Constant Histograms from the Forced Expired Volume-Time Curves

An efficient BASIC program was established on Apple-Ⅱmicrocomputer with the CHESTAC-35F pulmonary function testing system tocalculate the time-constant histogram from the spirogram.By a set of analogousstudies,we confirmed that the recovered time-constant histogram was within onecompartment of the assumed one and that the root of mean square values of theresiduals between the experimental and model volume-time curves was 0.02.Infour healthy adult subjects,the mean value of time-constant histograms(TCx)hadthe variation coefficient 6.6％.The results show that our method is reliable andreproducible,and it can be used for clinical investigation.     

脑动静脉畸形实验动物模型的建立

脑动静脉畸形是一种比较常见的严重威胁人们生命安全和生存质量的脑血管疾病，目前人们主要是通过尸体解剖以及CT、MRI等影像学的方法认识。近年来，学者们应用各种动物模型来研究脑动静脉畸形的血流动力学，病理生理学以及脑动静脉畸形栓塞材料的评估，栓塞后临床疗效评价，放射照射剂量对脑动静脉畸形的影响等。本文就脑动静脉畸形实验动物的常用种类，动物模型的建立方法以及动物模型的实际应用进行了综述。     

激素性股骨头缺血坏死MRI诊断的实验研究

目的：建立股骨头缺血坏死(ANFH)动物模型，将磁共振成像(MRI)表现与组织病理学结果对照，探讨早期ANFH的病理变化和删表现的病理学基础。方法：成年新西兰兔36只，随机均分成三组。A组：为正常对照组，静脉注射生理盐水。B、C组为实验组，B组：单纯静脉注射地塞米松10mg／kg／d连续7天，间隔两周再重复一次。C组；马血清与激素共用，先静脉注射马血清10g／kg，间隔2周再重复一次；继之重复B组给药。之后4、8、16、26周后分别从3组随机各取3只，先拍X线平片再进行删，然后取双侧股骨头做组织病理检查。结果：实验组兔股骨头第8周T1WI信号强度明显降低，T2WI呈不均匀高信号，对应病理改变为骨髓水肿，骨髓腔内少量出血和少量骨细胞坏死。16、26周T1WI信号强度增高，病理显示骨髓脂肪细胞肥大并融合成大泡状，大量骨细胞坏死，骨小梁变细、中断。16、26周兔股骨头X线平片示骨质稀疏，骨小梁模糊。C组上述变化较B组显著。结论：1．采用马血清和肾上腺皮质激素共用，比单纯用肾上腺皮质激素更易诱导出较典型的ANFH动物模型。2．删能够较全面反映早期激素性ANFH的病理变化。     

神经根慢性嵌压损伤的动物模型建立

目的：建立一种由自身骨性增生造成神经根慢性嵌压损伤的动物模型，为相关实验提供造模方法一方法：30只健康家猫，手术显露右侧C7、C8和L5、L6冲经根及其椎问孔内口，用牙髓钻破坏椎间孔周围骨皮质后，将“V”形松质骨块沿骨壁嵌于神经根通道的骨性管道内及侧隐窝后方，左侧做正常对照。在造模术前和术后第2、4、8、12、24周行磁刺激运动诱发电位(MEP)检测，每次随机选6只，4～5只行影像学检查，以确定神经根通道的狭窄程度和神经根受压状态，6只均做病理组织学检查和椎间孔截面积测量。结果：术后早期实验侧肢体出现行为异常：而后有不同程度肌萎缩；后期部分肢体远端出现溃疡。影像学检查随着嵌压时间延长．实验侧椎间孔骨痂增多，狭窄加重。神经根受压变形，椎间孔骨性截面积8周后明显减小，与对照侧比较有显著性差异。术后2周，神经根组织学检查主要表现为神经束膜、内膜的水肿。髓鞘肿胀；4周后发生节段性脱髓鞘：8周时神经轴突增粗、断裂，远端瓦勒氏变性；12周后变性冲经结构崩解、吸收，形成空洞：24周时整个神经干纤维化。术后4周时实验侧MEP开始出现潜伏期延长；8周时伴有波形分化不清；12周波幅明显下降：24周MEP的引出困难，部分电位消失。结论：采用椎问孔内自体松质骨植入，造成神经根慢性嵌压性损伤模型成功率高，操作简单，适用于脊柱各个节段，其损伤部位和形式与临床更为接近。