532nm 激光血管内照射血液实验方法

根据现有的低强度５３２ｎｍ激光器的输出特性,建立了简便、可靠的激光血管内照射血液实验方法。通过选择合适的滤光片,可以确保５３２ｎｍ激光的单纯性;通过分束监视,实现了激光输出功率的准确计量;在实验过程中,根据监视功率值对激光输出功率进行实时调节,可以使其比较稳定地保持在设定附近。该实验方法亦可供其它激光生物效应实验参考。     

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。     

Laser power dependence of mechanoluminescence in metals

Mechanoluminescence (ML) glow is produced on the back side when the front of a metal sample is irradiated with infrared Nd:YAG laser pulses. An incident laser beam with a power density below the plasma‐flare onset threshold causes a rise in temperature in the studied metal. As the incident laser power density increases, the intensity of the ML glow signal also increases. On the basis of the laser power density‐induced temperature, an expression is derived for the temperature‐induced thermal stress. An expression is derived for the correlation between thermal stress and laser power density, which indicates that the temperature‐induced thermal stress is directly related to the incident laser power density. In the region of plastic deformation, temperature‐induced thermal stress is related to the strain and, consequently, to the emitted ML intensity. Finally, an expression is derived for the laser power dependence of the ML intensity, and good agreement is found between the theoretical and experimental results. Copyright © 2016 John Wiley & Sons, Ltd.     

PALM成像中激光强度和定位精度相关性的研究

近十年来,基于单分子定位的PALM成像技术快速发展,将显微镜的分辨率提高到了2-25nm。本文发现PALM成像过程中采用的激发光强度与成像的定位精度之间有密切的联系。我们分别选择了PALM成像使用的光激活荧光蛋白、光转换荧光蛋白和光开关荧光蛋白中最常用的荧光蛋白进行验证。实验发现伴随激光强度的增加,大部分荧光蛋白的光子数先升高然后趋于饱和,背景噪声几乎线性升高。进一步分析发现荧光蛋白的定位误差随着激光强度增强先降低后升高,因此选用合适的激光强度在PALM成像实验中至关重要。如何提高PALM成像的分辨率一直是科学家研究的热点,本研究内容可以指导研究人员在PALM成像中选用合适的激发光强度,从而得到高分辨率的图像。     

激光、~(60)Co—r射线对草毒生物效应的研究

本实验用CO_2激光功率密度10.44W/cm~2、3.40W/cm~2,一次10秒及再次6、10、14秒处理草莓、茎尖外植体,可使多数处理的无性后代,产量提高或品质改善。He—Ne激光输出功率10.6mW,原光斑照射30、40秒,也有与CO_2激光相似效应。~(60)Co—r射线吸收剂量193Gy,单独处理及与He—Ne激光30秒复合处理,可改善果实品质,He—Ne激光对~(60)Co—r射线的辐射损伤有修复作用。     

A hand-held photometer for quantitative dot-immunobinding assays

A simple multichannel transmission photometer is presented. This instrument is designed to give a quantitative result from dot-immunobinding assays. The optoelectronic components of the system (yellow GaP light-emitting diode and CdS photoresistor) have been selected to match the absorbance maximum of the product generated by the peroxidase-catalyzed oxidation of 4-chloro-1-naphthol. The standard deviation of duplicate measures is lower than 0.5% on a single channel and lower than 1.5% on different channels. The photometer is able to read linearly the absorbance of samples up to a value of A585 = 3.0. As an application example, the photometer was used to read the results of the titration of sera of Leishmania-infected dogs on Leishmania donovani antigens.     

Practical Confocal Microscopy and the Evaluation of System Performance

The laser scanning confocal microscope has enormous potential in many fields of biology. Currently there is a subjective nature in the assessment of a confocal microscope's performance by primarily evaluating the system with a specific test slide provided by the user's laboratory. To achieve better performance from the equipment, it is necessary to run a series of tests to ensure that the optical machine is functioning properly. We have devised these methods on the Leica TCS-SP and TCS-4D systems. Tests measuring field illumination, lens clarity, laser power output, dichroic functioning, spectral alignment, axial resolution, laser power stability, machine performance, and system noise were derived to test the Leica laser scanning confocal microscopy system. These tests should be applicable to other manufacturers' systems as well. The relationship between photomultiplier tube (PMT) voltage, laser power, and averaging using a 10-microm-diameter test bead has shown that the noise (coefficient of variation of bead intensity, CV) in an image increases as the PMT increases. Therefore increasing the PMT setting results in increased noise. For ideal image quality, it appears that it is better to decrease the PMT setting and increase laser power, as noise generated by high PMT settings will reduce the image quality far more than the bleaching caused by higher laser power. Averaging can be used to improve the image at high PMT values, provided the sample is not bleached by repeated passes of the laser.     

Molecular level damages of low power pulsed laser radiation in a marine bacterium Pseudoalteromonas carrageenovora

AIM: To study the molecular level damages in a marine bacterium, Pseudoalteromonas carrageenovora, exposed to low power pulsed laser radiation from an Nd:YAG laser. METHODS AND RESULTS: The laser damages in bacterial DNA were monitored by studying the formation of apurinic/apyrimidinic (AP) sites. Molecular probe kits were used for this purpose. Occurrence of lesions in the cell walls was monitored under a transmission electron microscope (TEM). The results showed that laser radiation significantly increased the number of AP sites in the bacterial DNA. This increase corresponded to the laser fluence (J cm(-2)) and to the duration of laser irradiation. TEM observation showed the occurrence of lesions in bacterial cell walls upon laser irradiation. CONCLUSIONS: It is concluded that bacteria exposed to laser irradiation suffers DNA damages and resulted in broken cell walls. These events led to bacterial mortality. These are in addition to the mechanisms reported earlier such as the photochemical reactions occurring inside the cells upon exposure to low power laser. SIGNIFICANCE AND IMPACT OF THE STUDY: These results help us to understand the mechanisms of bacterial mortality on exposure to low power pulsed laser irradiation and are useful in formulating a laser treatment strategy to kill bacteria.     

578.2 nm激光照射对兔视网膜的损伤效应研究

研究578.2 nm激光照射对兔视网膜的作用特点,以新西兰白兔5只10眼为实验对象,铜蒸汽激光(578.2 nm)通过裂隙灯照射兔视网膜后极部,照射时间为100 s,光斑直径为2 mm,照射剂量分别为60 J/cm2、80 J/cm2、100 J/cm2、120 J/cm2、160 J/cm2、200 J/cm2,每组4个光斑。照后1 h及24 h进行眼底照相及光镜观察。照光后可见,随激光功率密度的增加,兔视网膜的损伤也逐渐加重,并且照后24 h的损伤要重于照后1h。80 J/cm2和60 J/cm2在照后1 h和24 h均未发现明显改变。578.2 nm激光照射白兔后的主要病理学改变位于脉络膜。因此,以578.2 nm激光作为光动力治疗眼底疾病的光源时,照射剂量不宜超过80 J/cm2。     

Superficial photothermal laser ablation of ex vivo sheep esophagus using a cone‐shaped optical fiber tip

Superficial photothermal laser ablation (SPLA) may be useful as a therapeutic approach producing a depth of injury that is sufficient to eliminate mucosal lesion but not deep enough to induce thermal effects in deeper tissue layers. The purpose of this preliminary study is twofold: (a) to describe design steps of a fiber probe capable of delivering a tightly focused laser beam, including Monte‐Carlo‐based simulations, and (b) to complete the initial testing of the probe in a sheep esophagus model, ex vivo. The cone‐shaped (tapered) fiber tip was obtained by chemical etching of the optical fiber. A 1505 nm diode laser providing power up to 500 mW was operated in continuous wave. The successful SPLA of the sheep mucosa layer was demonstrated for various speed‐power combinations, including 300 mW laser power at a surface scanning rate of 0.5 mm/s and 450 mW laser power at a surface scanning rate of 2.0 mm/s. Upon further development, this probe may be useful for endoscopic photothermal laser ablation of the mucosa layer using relatively low laser power.     

试论生物信息流与激光生物效应的相关性--激光生物效应分子机理研究

为了探索激光生物学效应的分子机理,以便更好的掌控和利用激光生物效应,用XeCl（308 nm）准分子紫外激光以相同变化的激光参量直接辐照有生物活性的生物大分子BTG DNA、BSA（v）蛋白质和糖Mannan.实验结果分析告知：电镜法观察到受辐照的三类生物大分子的表观结构、构象（含结构信息）和光谱法（IR、Vis-UV、FR、CD）分析指出生物大分子的内在结构部件的相关的特征峰的峰位、峰值都受影响,其变迁都与激光参量的变化相呼应;与三类生物大分子中分子内、分子间沟通与信息传递相关的氢键、糖苷键等的形成与否的类似或相同的结构部件（如-C-H、-N-H、-CH-OH、-C-O、-C =O等）其特征峰的变迁都更敏感于激光参量的改变.激光辐照生物体时,激光似生物信号分子通过它的能量以粒子性、电磁波相干性影响生物大分子的分子结构、构象（含结构信息）的稳定性、增加分子内、分子间相互沟通、信息传递,亦增加了结构部件的被修饰的可能性.进而影响着生物信息流的流量与流向和细胞信号转导的协同与整体表达,产生相应的生物效应.掌握获得功能生物大分子结构构象信息与使用适宜的激光参量的相关的关系值（阈值）是重要的关键.     

氦氖激光对离体小鼠腹腔巨噬细胞功能的影响

为探索低功率激光照射治疗的机理,本实验用氦氖激光照射离体小白鼠腹腔巨噬细胞观察其吞噬鸡红细胞折功能。当照射１５分钟时,巨噬细胞蚕噬功能达到最大值,以后开始下降,照射至４０分时,巨噬细胞吞噬功能下降至对照组以下,出现抑制现象。     

低功率He-Ne激光照射下细胞内活性氧自由基的产生和游离Ca^2＋浓度的研究

在临床应用中,低功率He-Ne激光(632.8 nm)能促进骨骼肌修复,加速创伤愈合,降低牙齿的超敏感性,减缓疼痛等.大量研究表明:低功率He-Ne激光能调节细胞的众多行为,如细胞增殖、分泌、迁移、粘附、蛋白质合成和基因表达等.但低功率He-Ne激光调节细胞行为的分子机制并未阐明,考察低功率He-Ne激光照射后细胞内活性氧自由基的产生水平和游离ca2 浓度是否会发生变化,通过激光扫描共聚焦显微镜,分别利用H:DCFDA和Fluo-3/AM这两种荧光探针,检测到经He-Ne激光照射后,肺腺癌细胞内活性氧自由基的水平上调以及游离Ca2 浓度增加.该研究为低功率He-Ne激光的生物光刺激效应提供了可能的分子机理.     

氦氖激光对鱼类生长的影响

本试验采用氦氖激光(632.8nm)以不同的功率和不同功率密度,或者不同的辐照方式,辐照孔雀幼鱼(Poecilia reticulata)、尼罗罗非鱼(Oreochromis niloticus)和淡水白鲳(Ephippus orbis)。实验结果表明,He-Ne激光辐照对三种幼鱼的生长均有促进的作用,并且不同的功率和功率密度的影响是不同的,适当的激光参量会产生较佳的影响效果。     

He—Ne激光照射离体鼠巨噬细胞对线粒体跨膜电势的影响

目的：研究Ｈｅ－Ｎｅ激光照射鼠巨噬细胞对线粒体跨膜电势的影响,及其与激光剂量的关系。方法：用亲脂性阳离子荧光染料Ｒｈｏｄａｍｉｎｅ１２３对鼠巨噬细胞线粒体作荧光标记,以不同的激光剂量照射,采用图像分析系统（ＩＡＳ）和荧光显微镜观察线粒体跨膜电势荧光强度的变化。结果：低功率Ｈｅ－Ｎｅ激光照射５,１０,１５ｍｉｎ,激光剂量分别为０．６４９,１．３８８和２．０８２Ｊ／ｃｍ＾２,巨噬细胞线粒体跨膜电势荧光     

Mathematical modeling of laser based potato cutting and peeling

A mathematical model is developed and validated to predict the depth of cut in potato tuber slabs as a function of laser power and travel speed. The model considers laser processing parameters such as input power, spot size and exposure time as well as the properties of the material being cut such as specific heat, thermal conductivity, surface reflectance, etc. The model also considers the phase change of water in potato and the ignition temperature of the solid portion. The composition of the potato tuber is assumed to be of water and solid. The model also assumes that the ablation process is accomplished through ejection of liquid water, debris and water vapour, and combustion of solid. A CO₂ laser operating in c.w. mode was chosen for the experimental work because water absorbs laser energy highly at 10.6 μm, and CO₂ laser units with relatively high output power are available. Slabs of potato tuber were chosen to be laser processed since potato contains high moisture and large amounts of relatively homogeneous tissue. The results of the preliminary calculations and experiments concluded that the model is able to predict the depth of cut in potato tuber parenchyma when subjected to a CO₂ laser beam.     

THE LASER AS A POTENTIAL TOOL FOR CELL RESEARCH

Freshly prepared hemoglobin solutions were successively irradiated up to five times with 1 MW (monochromatic wavelength) of green (530 mµ) laser power. Oxygenated hemoglobin showed no detectable change, but the spectral absorption of reduced hemoglobin showed a shift toward the characteristic curve for the oxygenated form. Intact human erythrocytes exposed to a power density of 110 MW/cm² of green laser radiation showed no appreciable change in diameter or mass, but they became transparent to a wavelength range from 400 to 600 mµ. A similar power density from a ruby laser failed to produce this bleaching effect. This response in the erythrocyte demonstrates a principle which suggests the laser as a tool for cell research: specific molecular components within a cell may be selectively altered by laser irradiation when an appropriate wavelength and a suitable power density are applied.     

Laser irradiation and Raman spectroscopy of single living cells and chromosomes: Sample degradation occurs with 514.5 nm but not with 660 nm laser light

In Raman spectroscopic measurements of single cells (human lymphocytes) and chromosomes, using a newly developed confocal Raman microspectrometer and a laser excitation wavelength of 514.5 nm, degradation of the biological objects was observed. In the experiments high power microscope objectives were used, focusing the laser beam into a spot approximately 0.5 micron in diameter. At the position of the laser focus a paling of the samples became visible even when the laser power on the sample was reduced to less than 1 mW. This was accompanied by a gradual decrease in the intensity of the Raman signal. With 5 mW of laser power the events became noticeable after a period of time in the order of minutes. It is shown that a number of potential mechanisms, such as excessive sample heating due to absorption of laser light, multiple photon absorption, and substrate heating are unlikely to play a role. In experiments with DNA solutions and histone protein solutions no evidence of photo damage was found using laser powers up to 25 mW. No degradation of cells and chromosomes occurs when laser light of 660 nm is used. The most plausible explanation therefore seems to be that the sample degradation is the result of photochemical reactions initiated by laser excitation at 514.5 nm of as yet unidentified sensitizer molecules or complexes present in chromosomes and cells but not in purified DNA and histone protein samples.     

Quality assessment of confocal microscopy slide-based systems: instability.

BACKGROUND: All slide-based fluorescence cytometry detections systems basically include an excitation light source, intermediate optics, and a detection device (CCD or PMT). Occasionally, this equipment becomes unstable, generating unreliable and inferior data. METHODS: A number of tests have been devised to evaluate equipment performance and instability. The following four instability tests are described: galvanometer scanning, stage drift, correct wavelength spectral detection, and long-term laser power. RESULTS: Quality assurance tests revealed that a confocal microscope can become unstable in the following parameters, yielding inaccurate data: laser power, PMTs functionality, spectrophotometer accuracy, galvanometer scanning and laser stability, and stage drift. Long-term laser power stability has been observed to vary greatly. CONCLUSIONS: Confocal systems can become unstable in the following parameters: long-term laser power, galvanometer scanning, spectrophotometer accuracy, and stage stability. Instability in any of these parameters will affect image quality. Laser power fluctuations result from either a defective Acousto-optic tunable filter or improper heat dissipation. Spectrophotometer instability will generate unreliable spectra data, extra light reflections, and poor image quality. Galvanometer scanning instability yields poor image quality while microscope stage drift results in a sample going out of the plane of focus. With minor modifications, these tests may be applicable to other slide-based systems.