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.     

Skin reactions to irritants assessed by non-invasive bioengineering methods

Pathophysiological components of irritant contact dermatitis caused by 3 chemically-different irritants were investigated. 20 healthy volunteers were patch tested with sodium lauryl sulphate, nonanoic acid and hydrochloric acid on the flexor side of the upper arm. The skin response was evaluated after 24, 48 and 96 h by visual scoring and measured by the following bioengineering methods: transepidermal water loss measurement, electrical conductance for measurement of skin hydration, laser Doppler flowmetry for measurement of cutaneous blood flow and 20 MHz ultrasound A-scan for measurement of skin thickness. In spite of homogeneous inflammatory responses, significant differences in the severity of the injury to the skin barrier function caused by the different irritants were found. Also significant differences between irritants were found in the time course of development of maximum irritant reactions. Bioengineering methods indicating inflammatory responses (measurement of blood flow and skin thickness) were helpful in quantifying the irritant response in general, while bioengineering methods indicating epidermal damage (measurement of TEWL and electrical conductance) were helpful in classifying the individual irritants.     

经尿道非接触式激光前列腺切除技术的应用与改进

１９９３年１１月至１９９６年５月应用改进的经尿道非接触式激光治疗前列腺增生１２０例，并对病人进行术前术后的症状评分，尿动力学，残余尿检查，随访病人１－２４个月，结果显示病人无论是症状评分，还是尿流率，残余尿等各项指标均有明显的改善，此种手术具有简单，安全，副作用小，术后恢复快，治疗效果好等优点。     

应用荧光探针H2DCF-DA检测光照致细胞内活性氧产生的初步研究

目的应用荧光显微镜及新型荧光探针H2DCF-DA检测在光源照射过程中人脐静脉血管内皮细胞(ECV304)内活性氧的产生情况。方法将ECV304细胞接种于35mm培养皿中,24h后加入H2DCF-DA,使其终浓度为10μmol/L,孵育30min。利用荧光显微镜的激发光源作为照射光源,在采集荧光图像的同时完成光源照射,光源输出波长范围为460～490nm,功率密度约为100mW/cm2。连续采集DCF的荧光图,观察细胞内DCF荧光的变化情况,采用计算机图像处理和分析技术,求得细胞内不同照射时间点DCF平均荧光强度,进而得到平均荧光强度-时间曲线。另外,使用线粒体特异标记探针MitoFluorRed589与H2DCF-DA共同孵育细胞,分别采集同一细胞的DCF的荧光图和MitoFluorRed589的荧光图,并利用像素-荧光强度分析方法来确定DCF荧光在细胞内的分布位置。结果在光源照射的开始阶段,ECV304细胞内的DCF荧光强度迅速增加,在第10s时便上升至第2s时的2.2倍,但是随着照射时间逐渐延长,荧光强度增幅逐渐变小,到第60s时上升至第2s时的4.7倍。观察时间进一步延长,DCF的荧光强度的变化似乎进入平台期,继而开始出现下降。考察DCF荧光在ECV304细胞内的分布位置主要通过比较细胞内不同区域的I1/I2值,通过图像分析与计算得到线粒体区、细胞核区以及细胞质非线粒体区内I1/I2值分     

光动力疗法中不同激光条件癌肿杀伤效果的比较

本文报告应用两种不同波长激光为 PDT(光动疗法)的激光源,对小鼠移植肿瘤进行杀伤实验。结果表明:在相同光剂量下,HPD—氩离子泵浦的染料激光(波长6 300(?))对肿瘤杀伤的效果强于 HPD—氩离子激光(波长5 145(?))(P<0.01);同一波长激光在光剂量相同时,采用不同的瞬间功率,对肿瘤杀伤的效果相同(P>0.20)。     

苯并恶唑类化合物的研究——Ⅰ.化合物的合成及光物理性能

合成了四种结构类型的苯并恶唑化合物共15个:测试了它们的红外吸收光谱,以及它们在DMF中的紫外吸收、荧光发射和激光发射光谱。苯基取代物的荧光量子产率在0.64～0.66,无激光性能。其余的化合物荧光量子产率都大于0.70,在最大吸收波长下的激光转换效率为2.5～5.9%。     

CO2激光治疗肛肠科疾病300例的报告

本文对３００例肛肠疾病采用ＣＯ_２激光治疗，治愈率为９４．３３％，一次切割完成，不需止血缝合，一般７－１５天痊愈，疗效明显优于其它治疗方法。     

Monitoring of skin response to sodium lauryl sulphate: clinical scores versus bioengineering methods

The present trial was designed to evaluate clinical scores (single observer) of sodium lauryl sulphate (SLS)-induced skin irritation in a group of subjects (n = 10) over a 10-day period along with various skin function parameters. In order to avoid significant variations due to secondary phenomena, the following parameters were recorded with non-invasive instruments in this order: skin capacitance (C1; arbitrary units; CM420 Corneometer), transepidermal water loss (TEWL; g/m2.h; Evaporimeter) and laser Doppler flowmetry (CBFV: cutaneous blood flow values; Periflux). All examinations were performed during winter on reclined relaxed subjects present for at least 10 min in a test room with controlled temperature and relative humidity (t degrees: 19.5-20.7 degrees C and RH: 47.3-60.3%). The analysis of differential data (delta = value at tx-value before test; 2-way ANOVA) was made on single parameters as a function of site (volar forearm versus neck) and time (from 24 h after 48-h occlusion with 5% SLS up to 10 days later). The profile of erythema scores over time differed between neck and forearm, but the delta CBFV readings with the laser Doppler instrument did not detect significant site-time interactions. Roughness (blind evaluation with palpating finger) and capacitance readings (delta C1) showed significant differences between sites, but the profile over time was similar in both locations. delta TEWL did not differ according to anatomical location. The reason for different erythema scores on neck and forearm might be related to inherent regional variation of optical properties of the skin or to a substantial contribution of SLS-induced roughness to the readings of erythema.(ABSTRACT TRUNCATED AT 250 WORDS)     

Prostatectomy by transurethral balloon Laserthermia™ (PROSTALASE™) in the canine

Prostatectomy by transurethral balloon Laserthermia (PROSTA-LASE?) was performed in a canine model. This balloon device monitored by transrectal ultrasound can cylindrically irradiate with a laser beam. The treatment was performed in 8 canines using 15 watts for 20 minutes at 60°C at a 5 mm depth of the prostate from the urethral surface. Immediately following the laser therapy, an area of coagulation necrosis was observed around the urethra to a depth of 4–5 mm from the surface. After 1 week, cavitation formation was seen in 3 or 4 canines by ultrasound, and the urethral reepithelialization was shown in 1 of 2 canines. After 2 weeks, cavitation formation was observed in both canines, and the urethra was completely reepithelialized in one canine. There was no tissue damage in the bladder neck of urethral sphincter and no urinary incontinence in any animal. This system is thought to be simple and, satisfactorily performed, is an effective transurethral prostatectomy. © 1994 Wiley-Liss, Inc.