弱激光的生物学效应及对红细胞变形性的改善作用

简要叙述激光生物效应和弱激光生物刺激作用。概括阐述激光照射血液所产生的生物学效应,叙述了弱激光对红细胞变形性的改善作用并探讨其可能的作用机理。     

Ar+激光、Nd:YAG激光辐照亚心形扁藻生物学效应初探

采用Ar^＋激光（488 nm,照射时间分别为10 min、20 min、30 min）、Nd：YAG（1064 nm,照射时间为1 min、2 min、3 min）辐照扁藻,通过细胞计数以及扫描色素的吸收光谱研究激光辐照扁藻的生物效应.研究结果表明：非色素吸收峰的激光可以产生激光生物效应;不同波长,不同剂量的激光辐照扁藻可以表现出相类似的生物效应;Ar＋辐照20 min、Nd：YAG辐照2 min可以刺激扁藻生长,明显提高色素吸收光密度值,促进光合作用的进行.文中对不同激光辐照扁藻所产生的生物效应进行了比较和探讨.     

低强度激光的生物效应对组织修复的影响

本文概述了近几年低强度激光照射疗法对促进骨骼肌的再生、关节炎与骨折的修复、改善心肌微循环等方面生物效应的实验研究的新进展,其结果表明低强度激光照射组织具有显著的生物刺激作用和损伤后的修复功能。     

用积分球系统测量大鼠组织在不同光阑孔径下对氦-氖激光的温反射特性

本文对大鼠组织在不同光阑孔径下对He-Ne激光的漫反射特性进行了测量。实验采用了不同光阑孔径的积分球系统及He-Ne激光,并根据测量数据计算和分析了大鼠组织对该波长激光的漫反射特性。结果表明,有些大鼠组织在632.8nm波长的He-Ne激光照射下对不同的光阑孔径其漫反射率没有显著性区别,而有些大鼠组织在632.8nm波长的He-Ne激光照射下对不同的光阑孔径其漫长反射率有显著性区别,提示在测定不同生物组织的光学特性时,应考虑组织样品的受光照射的面积的大小对测定结果的精确度的影响。     

氦氖激光穴位照射对兔子宫和卵巢乳酸脱氢酶（LDH）及同工酶的作用效应

对兔用氦氖激光照射穴位、照射外生殖器,用生化方法测定兔子宜和卵巢的ＬＤＨ酶活性,用聚丙烯酰胺凝肢电泳法测定ＬＤＨ同工酶。激光照射后,ＬＤＨ酶活性变化不大,但ＬＤＨ同工酶各区带相对含量百分比产生变化,ＬＤＨ５显著低于对照组,其它各区带均有程度不同的升高或降低。且子宫、卵巢两种不同组织ＬＤＨ同工酶对激光敏感性不一;不同照射部位ＬＤＨ同工酶表现不一。结果说明氦氖激光对与ＬＤＨ有关基因的表达产生一定的作用效应。     

激光针灸治疗机理探讨

给出激光照射对组织热和机械作用微观机制,利用热平衡理论和电磁理论对激光热作用进行定量分析和计算,在此基础上探讨激光针灸作用机理。     

低能量激光在口腔种植中的应用进展

低能量激光照射（low level laser irradiation,LLLI）是一种生物物理学刺激,对多种细胞具有光生物调节作用,可以促进骨组织和软组织的愈合,已经引起口腔种植工作者的重视。本文综述了LLLI在口腔种植中的应用,并简述了低能量激光照射的光生物调节作用可能的分子学机制,最后提出了低能量激光照射的研究展望,为未来低能量激光照射在口腔种植临床的应用奠定基础。     

基于LED作为照射光源的血疗法可行性研究

通过对LED在生物医学领域的应用分析发现,LED光存在与激光相类似的生物刺激效应。目前弱激光血疗已由血管内照射发展到体表照射、黏膜照射。这为LED光照射体表、黏膜实现血疗提供了良好的预期。为了证明LED光可以代替激光作为净血治疗仪的光源,本实验设计了激光与LED光对自由基损伤模型红细胞变形性作用的对比实验,结果表明,两种光照方法均对红细胞变形性有改善作用。LED相比激光安全性更好、成本更加低廉,特别适合往家用小型化方向发展。     

激光照射对角膜蛋白质二级结构影响的光谱分析

为了研究激光照射后角膜蛋白质化学组成的改变,探讨激光角膜损伤的发生机制,将日本大耳白兔随机分为正常对照组和激光损伤组,选取角膜上皮层和基质层作为研究对象,通过傅里叶变换红外光谱技术(Fou-rier transform infrared spectroscopy,FT-IR)对角膜组织酰胺I带中蛋白质二级结构各吸收峰进行定量分析,观察激光照射后蛋白质分子结构的改变情况。结果显示,激光照射后出现蛋白质二级结构吸收峰的位移和积分百分比的改变。激光照射可使角膜上皮层和基质层蛋白质构象发生改变,从而导致蛋白质结构稳定性下降和蛋白质生物功能的破坏。     

低强度激光对离体细胞效应的若干新进展

本文综述了低强度激光照射对离体细胞效应的研究进展。主要讨论了低强度激光照射对造骨细胞,成纤维细胞、骨骼肌细胞,造血细胞的效应和低强度激光生物刺激作用的机制。     

激光和生物组织的光热作用及临床应用

激光和生物组织的光热作用机理及在临床上的应用作了全面的论述,同时建立了一个定量描述光热作用的模型。讨论了光热作用中热产生,传导及热效应。     

Simulation and investigation of quantum dot effects as internal heat-generator source in breast tumor site

The Pennes bio-heat transfer equation, which introduces the exchange magnitude of heat transfer between tissue and blood, is often used to solve the temperature distribution for thermal imaging and sensing. Near-infrared light has the ability to be used as a non-invasive means of diagnostic imaging within the woman's breast. Due to the diffusive nature of light in different tissue, computational model-based methods are required for functional imaging within the breast. In this article, the time-dependent bio-heat transfer is solved by a numerical method. In our model, the heat generation source (intrinsic and extrinsic) involves laser, metabolism, and quantum dot that the metabolism and heat generated by QDs are considered as intrinsic. We supposed the injected quantum dots would target the tumor site by a passive targeting process and then by interaction of laser radiation and quantum dot, the photoluminescence of quantum dot is converted to heat in the tumor site. The extra generated heat can impact on the extracted heat profile. One of the important applications of this research has led to a sensitivity improvement of the imaging system, which is potentially useful in the diagnosis and detection of breast cancer.     

Heat generation in laser irradiated tissue

Many medical applications involving lasers rely upon the generation of heat within the tissue for the desired therapeutic effect. Determination of the absorbed light energy in tissue is difficult in many cases. Although UV wavelengths of the excimer laser and 10.6 microns wavelength of the CO2 laser are absorbed within the first 20 microns of soft tissue, visible and near infrared wavelengths are scattered as well as absorbed. Typically, multiple scattering is a significant factor in the distribution of light in tissue and the resulting heat source term. An improved model is presented for estimating heat generation due to the absorption of a collimated (axisymmetric) laser beam and scattered light at each point r and z in tissue. Heat generated within tissue is a function of the laser power, the shape and size of the incident beam and the optical properties of the tissue at the irradiation wavelength. Key to the calculation of heat source strength is accurate estimation of the light distribution. Methods for experimentally determining the optical parameters of tissue are discussed in the context of the improved model.     

Real-time in vivo imaging of platelets,tissue factor and fibrin during arterial thrombus formation in the mouse

We have used confocal and widefield microscopy to image thrombus formation in real time in the microcirculation of a living mouse. This system provides high-speed, near-simultaneous acquisition of images of multiple fluorescent probes and of a brightfield channel. Vascular injury is induced with a laser focused through the microscope optics. We observed platelet deposition, tissue factor accumulation and fibrin generation after laser-induced endothelial injury in a single developing thrombus. The initiation of blood coagulation in vivo entailed the initial accumulation of tissue factor on the upstream and thrombus-vessel wall interface of the developing thrombus. Subsequently tissue factor was associated with the interior of the thrombus. Tissue factor was biologically active, and was associated with fibrin generation within the thrombus.     

生物组织激光消融阈值的光谱特性

在一个宽光谱范围内研究不同激光作用下生物组织的消融,对理解激光与组织间相互作用及开发激光在外科的新应用有着极其重要的意义。其中消融阈值及其与激光波长的函数依赖关系是激光外科研究的重点。阐述了消融阈值的物理描述,并对消融阈值的波长依赖关系进行了初步探讨。     

Numerical investigation of thermal response of laser-irradiated biological tissue phantoms embedded with gold nanoshells

The work presented in this paper focuses on numerically investigating the thermal response of gold nanoshells-embedded biological tissue phantoms with potential applications into photo-thermal therapy wherein the interest is in destroying the cancerous cells with minimum damage to the surrounding healthy cells. The tissue phantom has been irradiated with a pico-second laser. Radiative transfer equation (RTE) has been employed to model the light-tissue interaction using discrete ordinate method (DOM). For determining the temperature distribution inside the tissue phantom, the RTE has been solved in combination with a generalized non-Fourier heat conduction model namely the dual phase lag bio-heat transfer model. The numerical code comprising the coupled RTE-bio-heat transfer equation, developed as a part of the current work, has been benchmarked against the experimental as well as the numerical results available in the literature. It has been demonstrated that the temperature of the optical inhomogeneity inside the biological tissue phantom embedded with gold nanoshells is relatively higher than that of the baseline case (no nanoshells) for the same laser power and operation time. The study clearly underlines the impact of nanoshell concentration and its size on the thermal response of the biological tissue sample. The comparative study concerned with the size and concentration of nanoshells showed that 60 nm nanoshells with concentration of 5×10¹⁵ mm⁻³ result into the temperature levels that are optimum for the irreversible destruction of cancer infected cells in the context of photo-thermal therapy. To the best of the knowledge of the authors, the present study is one of the first attempts to quantify the influence of gold nanoshells on the temperature distributions inside the biological tissue phantoms upon laser irradiation using the dual phase lag heat conduction model.     

Melanin Granule Models for the Processes of Laser-Induced Thermal Damage in Pigmented Retinal Tissues. I. Modeling of Laser-Induced Heating of Melanosomes and Selective Thermal Processes in Retinal Tissues

The computer modeling was applied for investigation of the processes of laser-induced tissue damage. The melanin granule models for the processes of laser-induced thermal damage and the results of computer modeling of the optical, thermophysical, and thermochemical processes during selective laser interaction with melanoprotein granules (melanosomes) in retinal pigment epithelium are presented in this paper. Physical-mathematical model and system of equations are formulated which describe thermal interaction processes for “short” laser pulses of duration t _p<10⁻⁶ s and for “ long’ pulses of duration t _p10⁻⁶ s. Results of numerical simulation of the processes give the space–time distributions of temperature and degrees of thermodenaturation of the protein molecules inside and around melanosomes and in the volume of irradiated tissues. Energy absorption, heat transfer and thermochemical (thermodenaturation, coagulation) processes occurring during the interaction of laser pulses with pigmented spherical and spheroidal granules in heterogeneous tissues are theoretically investigated. The possibility for selective interaction of short laser pulses with pigmented granules is discussed which results in the formation of denaturation microregions inside and near the pigmented granules (granular thermodenaturation) without origination of a continuous macroscopic thermodenaturation lesion in tissue. Analytical model of heating of single spherical and spheroidal granule under laser pulse is presented. Simple equations for time dependencies of particle temperature are obtained. The presented results are of essential interest for laser applications in and can be used for investigation of laser interaction with pigmented tissues in different fields of laser medicine.     

Numerical study on the thawing process of biological tissue induced by laser irradiation

Most of the laser applications in medicine and biology involve thermal effects. The laser-tissue thermal interaction has therefore received more and more attentions in recent years. However, previous works were mainly focused on the case of laser heating on normal tissues (37 degrees C or above). To date, little is known on the mechanisms of laser heating on the frozen biological tissues. Several latest experimental investigations have demonstrated that lasers have great potentials in tissue cryopreservation. But the lack of theoretical interpretation limits its further application in this area. The present paper proposes a numerical model for the thawing of biological tissues caused by laser irradiation. The Monte Carlo approach and the effective heat capacity method are, respectively, employed to simulate the light propagation and solid-liquid phase change heat transfer. The proposed model has four important features: (1) the tissue is considered as a nonideal material, in which phase transition occurs over a wide temperature range; (2) the solid phase, transition phase, and the liquid phase have different thermophysical properties; (3) the variations in optical properties due to phase-change are also taken into consideration; and (4) the light distribution is changing continually with the advancement of the thawing fronts. To this end, 15 thawing-front geometric configurations are presented for the Monte Carlo simulation. The least-squares parabola fitting technique is applied to approximate the shape of the thawing front. And then, a detailed algorithm of calculating the photon reflection/refraction behaviors at the thawing front is described. Finally, we develop a coupled light/heat transport solution procedure for the laser-induced thawing of frozen tissues. The proposed model is compared with three test problems and good agreement is obtained. The calculated results show that the light reflectance/transmittance at the tissue surface are continually changing with the progression of the thawing fronts and that lasers provide a new heating method superior to conventional heating through surface conduction because it can achieve a uniform volumetric heating. Parametric studies are performed to test the influences of the optical properties of tissue on the thawing process. The proposed model is rather general in nature and therefore can be applied to other nonbiological problems as long as the materials are absorbing and scattering media.     

利用激光共聚焦扫描显微镜对溃疡病菌侵染柑橘叶片的实时观察

柑橘溃疡病对柑橘产业造成了巨大损失,而研究柑橘与溃疡病菌的互作关系以及柑橘的感病和抗病性均需要观察溃疡病菌在柑橘寄主中的侵染和定殖过程。激光共聚焦扫描显微镜不仅可以观察活细胞,活组织的动态代谢过程,而且可以获得三维图像,对于病原菌在柑橘植物组织内的繁殖和致病机制研究具有重要意义。但是,选择适宜的植物材料和制片方法对激光共聚焦扫描显微镜的观察效果影响很大。本文对激光共聚焦扫描显微镜所观察的材料在其处理和观察方法上加以改进,获得了质量更好的图片和实验结果,也使得实验更为方便快捷。激光共聚焦扫描显微观察还在瞬时表达分析中得到应用,提高了柑橘瞬时表达分析的效果。通过将切片和压片相结合观察到溃疡病菌在不同时间点对柑橘叶片的侵染情况,而通过3D建模能观察到柑橘叶片不同组织层面中的病菌数量和病菌位置,为研究溃疡病菌在叶片中的定殖方式和入侵数量提供了前期基础。     

A parametric study of thermal therapy of skin tissue

A thermal therapy for cancer in skin tissue is numerically investigated using three bioheat conduction models, namely Pennes, thermal wave and dual-phase lag models. A laser is applied at the surface of the skin for cancer ablation, and the temperature and thermal damage distributions are predicted using the three bioheat models and two different modeling approaches of the laser effect. The first one is a prescribed surface heat flux, in which the tissue is assumed to be highly absorbent, while the second approach is a volumetric heat source, which is reasonable if the scattering and absorption skin effects are of similar magnitude. The finite volume method is applied to solve the governing bioheat equation. A parametric study is carried out to ascertain the effects of the thermophysical properties of the cancer on the thermal damage. The temperature distributions predicted by the three models exhibit significant differences, even though the temperature distributions are similar when the laser is turned off. The type of bioheat model has more influence on the predicted thermal damage than the type of modeling approach used for the laser. The phase lags of heat flux and temperature gradient have an important influence on the results, as well as the thermal conductivity of the cancer. In contrast, the uncertainty in the specific heat and blood perfusion rate has a minor influence on the thermal damage.