Catecholamine content and acetylcholinesterase activity in the brain of rats exposed to lasers

The catecholamine content was quantitated and acetylcholinesterase activity determined in rat brain locally exposed to laser radiation. It was shown that the adrenaline/noradrenaline ratio changed in the tissues under study and the cholinergic system was involved in the abscopal effect of laser radiation.     

A comparative study of thermal effects of 3 types of laser in eye: 3D simulation with bioheat equation

The application of laser in ophthalmology and eye surgery is so widespread that hardly can anyone deny its importance. On the other hand, since the human eye is an organ susceptible to external factors such as heat waves, laser radiation rapidly increases the temperature of the eye and therefore the study of temperature distribution inside the eye under laser irradiation is crucial; but the use of experimental and invasive methods for measuring the temperature inside the eye is typically high-risk and hazardous. In this paper, using the three-dimensional finite element method, the distribution of heat transfer inside the eye under transient condition was studied through three different lasers named Nd:Yag, Nd:Yap and ArF. Considering the metabolic heat and blood perfusion rate in various regions of the eye, numerical solution of space–time dependant Pennes bioheat transfer equation has been applied in this study. Lambert–Beer's law has been used to model the absorption of laser energy inside the eye tissues. It should also be mentioned that the effect of the ambient temperature, tear evaporation rate, laser power and the pupil diameter on the temperature distribution have been studied. Also, temperature distribution inside the eye after applying each laser and temperature variations of six optional regions as functions of time have been investigated. The results show that these radiations cause temperature rise in various regions, which will in turn causes serious damages to the eye tissues. Investigating the temperature distribution inside the eye under the laser irradiation can be a useful tool to study and predict the thermal effects of laser radiation on the human eye and evaluate the risk involved in performing laser surgery.     

Feasibility of using laser ion accelerators in proton therapy

The feasibility of using laser plasma as a source of high-energy ions for the purposes of proton therapy is discussed. The proposal is based on the efficient ion acceleration observed in recent laboratory and numerical experiments on the interaction of high-power laser radiation with gaseous and solid targets. The specific dependence of proton energy losses in biological tissues (the Bragg peak) promotes the solution of one of the main problems of radiation therapy, namely, the irradiation of a malignant tumor with a sufficiently strong and homogeneous dose, ensuring that the irradiation of the surrounding healthy tissues and organs is minimal. In the scheme proposed, a beam of fast ions accelerated by a laser pulse can be integrated in the installations intended for proton therapy.     

Laser surgery: using the carbon dioxide laser.

In 1917 Einstein theorized tha through an atomic process a unique kind of electromagnetic radiation could be produced by stimulated emission. When such radiation is in the optical or infrared spectrum it is termed laser (light amplification by stimulated emission of radiation) light. A laser, a high-intensity light source, emits a nearly parallel electromagnetic beam of energy at a given wavelength that can be captured by a lens and concentrated in the focal spot. The wavelength determines how the laser will be used. The carbon dioxide laser is now successfully employed for some surgical procedures in gynecology, otorhinolaryngology, neurosurgery, and plastic and general surgery. The CO2 laser beam is directed through the viewing system of an operating microscope or through a hand-held laser component. Its basic action in tissue is thermal vaporization; it causes minimal damage to adjacent tissues. Surgeons require special training in the basic methods and techniques of laser surgery, as well as in the safety standards that must be observed.     

Experimental and theoretical investigations on the validity of the geometrical optics model for calculating the stability of optical traps.

We have developed a computer program based on the geometrical optics approach proposed by Roosen to calculate the forces on dielectric spheres in focused laser beams. We have explicitly taken into account the polarization of the laser light and thd divergence of the laser beam. The model can be used to evaluate the stability of optical traps in a variety of different optical configurations. Our calculations explain the experimental observation by Ashkin that a stable single-beam optical trap, without the help of the gravitation force, can be obtained with a strongly divergent laser beam. Our calculations also predict a different trap stability in the directions orthogonal and parallel to the polarization direction of the incident light. Different experimental methods were used to test the predictions of the model for the gravity trap. A new method for measuring the radiation force along the beam axis in both the stable and instable regions is presented. Measurements of the radiation force on polystyrene spheres with diameters of 7.5 and 32 microns in a TEM00-mode laser beam showed a good qualitative correlation with the predictions and a slight quantitative difference. The validity of the geometrical approximations involved in the model will be discussed for spheres of different sizes and refractive indices.     

Effect of Low-Intensity Laser Radiation on the Lipid Peroxidation in Wheat Callus Culture

The effect of low-intensity laser radiation on the accumulation of secondary products of lipid peroxidation was studied in wheat (Triticum aestivum L.) tissue culture. A five-min-long callus irradiation by the helium-neon laser light with the wavelength = 632.8 nm and the intensity of 10 mW resulted in an increase in the accumulation of the products of reaction with thiobarbituric acid (TBA-reactive products). The effect was less pronounced within two days after laser treatment, but even in this case the content of TBA-reactive products was greater than in the control. The data obtained confirm that the low-intensity laser radiation can induce lipid peroxidation processes in plant tissues.     

Experimental evaluation of the bacteriotoxic phototherapy of inflammatory diseases of the oral cavity

The combined use of laser radiation and Radachlorine revealed the presence of correlation between the number of viable Streptococcus pyogenes cells and the concentration of photosensitizer (r=-0.62), time of irradiation (r=-0.75), as well as energy density (r=-0.80). The death of 100% of suspended S. pyogenes cells was observed at the concentration of Radachlorine reaching 14.4 mM and radiation power reaching 1 W, irrespective of energy density. Pulse and superpulse laser radiation, carried out simultaneously with the use of Radachlorine at a concentration of 1.8 microM, resulted in the death of 100% of S. pyogenes cells in vitro. On the experimental model of inflammation the application of 0.1% Radachlorine gel demonstrated higher effectiveness (in comparison with 0.35% Radachlorine solution) when used simultaneously with laser radiation, both continuous and superpulse (with energy density being 400 j/cm2 and power being 1 W). The use of these parameters in the treatment of the experimental foci of inflammation in the animals led to the complete elimination of S. pyogenes from infected tissues.     

Structural properties of regenerating muscle and the state of thymus after laser therapy of injured muscle in different periods of regeneration

The effect of He-Ne laser (632.8 nm, 2.5–3.0 mW/cm²) on skeletal muscle regeneration proved to depend on the period of regenerating tissue exposure to the radiation. Ten 3-min exposures within 1–15 days after muscle injury at a dose of 4.5–5.4 J/cm² per each operated limb accelerated the inflammation and regeneration of the muscle. The regenerates demonstrated a more muscular structure compared to laser therapy at later periods. The load on the thymus increased, its weight and cortical layer restoration decelerated, and aplasia was observed. The same dose of laser radiation in the period of days 16–30 increased the sclerotization of regenerating muscle tissue. The reactive changes in the thymus were less pronounced, the cortical layer recovery accelerated, and the mitotic index of thymocytes considerably increased. A three times lower laser radiation dose (1.5–1.8 J/cm²) in early regeneration inhibited inflammation and growth of the connective and muscle tissues compared to control. No increase in the functional activity of thymus was observed.     

He-Ne激光照射罗氏沼虾心脏、肌肉、鳃和脑神经节组织细胞光学显微镜观察

本文采用He-Ne激光照射罗氏沼虾的心脏、肌肉、鳃和脑神经节,研究其对罗氏沼虾组织细胞形态结构的影响。结果发现：(1)实验组的心脏、肌肉和鳃组织具有明显异染色质的细胞数量百分比分别为16．70％、6．06％、9．35％,而对照组的心脏、肌肉和鳃组织具有明显异染色质的细胞数量百分比分别为8．10％、2．59％和4．55％,表明He-Ne激光照射后,心脏、肌肉和鳃组织具有明显异染色质的细胞数量均有所增加;(2)在实验组中脑神经节的神经分泌细胞要比对照组的缩小7．4μm,实验组的细胞核要比对照组要缩小1．53μm,表明He-Ne激光照射后,脑神经节的神经细胞和细胞核的大小发生明显变化,尤为突出的是神经细胞发生明显的缩小现象。     

A study of bulky nanotube composites based on albumin by high-resolution microscopy

The structure of biocompatible nanocomposites formed by the action of laser radiation on an aqueous dispersion of albumin with carbon nanotubes has been studied by the high-resolution methods of atomic force and transmitting electron microscopy. It has been shown that the nanocomposites have a bulky structure consisting of conglomerates of nanotubes uniformly distributed in the albumin matrix. The results of the study may be useful in the production of filling nanomaterials for implants of biological tissues and organs and the control of their quality.     

Ultrafast Mid-IR Laser Scalpel: Protein Signals of the Fundamental Limits to Minimally Invasive Surgery

Lasers have in principle the capability to cut at the level of a single cell, the fundamental limit to minimally invasive procedures and restructuring biological tissues. To date, this limit has not been achieved due to collateral damage on the macroscale that arises from thermal and shock wave induced collateral damage of surrounding tissue. Here, we report on a novel concept using a specifically designed Picosecond IR Laser (PIRL) that selectively energizes water molecules in the tissue to drive ablation or cutting process faster than thermal exchange of energy and shock wave propagation, without plasma formation or ionizing radiation effects. The targeted laser process imparts the least amount of energy in the remaining tissue without any of the deleterious photochemical or photothermal effects that accompanies other laser wavelengths and pulse parameters. Full thickness incisional and excisional wounds were generated in CD1 mice using the Picosecond IR Laser, a conventional surgical laser (DELight Er:YAG) or mechanical surgical tools. Transmission and scanning electron microscopy showed that the PIRL laser produced minimal tissue ablation with less damage of surrounding tissues than wounds formed using the other modalities. The width of scars formed by wounds made by the PIRL laser were half that of the scars produced using either a conventional surgical laser or a scalpel. Aniline blue staining showed higher levels of collagen in the early stage of the wounds produced using the PIRL laser, suggesting that these wounds mature faster. There were more viable cells extracted from skin using the PIRL laser, suggesting less cellular damage. β-catenin and TGF-β signalling, which are activated during the proliferative phase of wound healing, and whose level of activation correlates with the size of wounds was lower in wounds generated by the PIRL system. Wounds created with the PIRL systsem also showed a lower rate of cell proliferation. Direct comparison of wound healing responses to a conventional surgical laser, and standard mechanical instruments shows far less damage and near absence of scar formation by using PIRL laser. This new laser source appears to have achieved the long held promise of lasers in minimally invasive surgery.     

Reactivation of superoxide dismutase by the helium-neon laser irradiation

When incubating SOD for two hours in the buffer with pH 6.0 practically complete loss of the activity of enzyme was observed at insignificant changes of the absorption spectra in the region of 450 and 680 nm. Irradiation of SOD solution with helium-neon laser resulted in the dose-dependent reduction of spectral and enzymic properties. Similar effect of the red light was also observed when SOD was inactivated with hydrogen peroxide: laser irradiation brought about the reduction of initial absorption spectrum of the enzyme. One can believe that the therapeutic effect of helium-neon laser radiation is conditioned, at least partially, by photochemical reactivation of SOD inactivated under pathological conditions (inflammation, hypoxia) in the tissues.     

氦氖激光穴位照射对兔子宫和卵巢酸性磷酸酶（ACP）、碱性磷酸酶（ALP）的作用效应

用不同功率的Ｈｅ—Ｎｅ激光照射雌兔外生殖器,照射穴位,用生化方法分别测定兔子宫和卵巢的酸性磷酸酶（ＡＣＰ）、碱性磷酸酶（ＡＬＰ）的活性。激光照射后,子宫和卵巢的ＡＣＰ酶活性保持基本恒定状态,与正常对照组比较无显著差异;相反,ＡＬＰ酶活性显著提高。分析这两种酶在激光用射后表现出来的差异,作者认为是激光作用使细胞内环境改变之故,且这两种酶对Ｈｅ—Ｎｅ激光的耐受性有所不同。     

A comparative study of the effects of laser and light-emitting diode irradiation on the wound healing and functional activity of wound exudate leukocytes

The effects of coherent He-Ne laser and non-coherent light-emitting diode radiation on rat skin wound healing and functional activity of wound excudate leukocytes were compared. A comparative pathomorphological analysis showed that the He-Ne laser and light-emitting diode irradiation stimulated the transition of the inflammatory phase of the wound healing into the reparative (proliferative) and scarring phases sequentially. It was also detected that the functional activity of leucocytes changed in a dose-dependent manner. The leukocyte activity was found to be similar in the groups with laser and light-emitting diode irradiation. Thus, we can conclude that coherent laser and non-coherent light-emitting diode radiation have very close effects on wound healing and activity of wound exudate leukocytes, and coherence is not required for this activity.     

Photobiological Principles of Therapeutic Applications of Laser Radiation

Laser therapy based on the stimulating and healing action of light of low-intensity lasers (LIL), along with laser surgery and photodynamic therapy, has been lately widely applied in the irradiation of human tissues in the absence of exogenous photosensitizers. Besides LIL, light-emitting diodes are used in phototherapy (photobiostimulation) whose action, like that of LIL, depends on the radiation wavelength, dose, and distribution of light intensity in time but, according to all available data, does not depend on the coherence of radiation.     

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。     

He-Ne激光和增强UV-B辐射对拟南芥叶片微管蛋白的影响

采用He-Ne激光生物辐照仪（632.8 nm,5 mW·mm-2）、UV-B（15.55 KJ·m-2·d-1）及二者复合处理拟南芥幼苗后提取微管蛋白,考马斯亮蓝法测含量和SDS-PAGE凝胶电泳进行初步分析,并用免疫印迹鉴定微管蛋白.结果表明：单独UV-B使微管蛋白解聚,He-Ne激光和UV-B复合处理后,微管蛋白解聚程度减小,单独He-Ne激光处理促进微管聚合.因此认为He-Ne激光在一定程度上缓解了UV-B对微管蛋白的解聚作用.     

用组织光学特性鉴别诊断人离体的正常膀胱和膀胱癌组织

研究正常人膀胱和膀胱癌组织在Kube lka-Munk二流模型下对476.5 nm,514.5 nm和808 nm波长的激光的光学特性的差异。采用双积分球系统和Kube lka-Munk二流模型进行测量研究。实验结果表明,正常膀胱和膀胱癌组织在Kube lka-Munk二流模型下对476.5 nm,514.5 nm和808 nm波长的每一个波长的激光的吸收、散射、总衰减、有效衰减系数都有非常显著性的差异(P<0.01)。膀胱癌组织对476.5 nm,514.5 nm和808nm波长的激光的吸收系数明显地较正常膀胱组织对相应波长的激光的吸收系数要大(P<0.01),膀胱癌组织对476.5 nm和514.5 nm波长的激光的散射系数明显地较正常膀胱组织对相应波长的激光的散射系数要小(P<0.01),而膀胱癌组织对808 nm波长的激光的散射系数明显地较正常膀胱组织对同一波长的激光的散射系数要大(P<0.01)。膀胱癌组织对476.5 nm,514.5 nm和808 nm波长的激光的总衰减系数明显地较正常膀胱组织对相应波长的激光的总衰减系数要大(P<0.01),膀胱癌组织对476.5 nm,514.5 nm和808 nm波长的激光的有效衰减系数明显地较正常膀胱组织对相应波长的激光的有效衰减系数要大(P<0.01)。提示使用双积分球系统和Kube lka-Munk二流模型来确定离体的正常膀胱组织和膀胱癌组织对476.5 nm,514.5 nm和808nm波长的激光的光学特性的差异鉴别诊断病变的膀胱组织是一个有效的方法。     

Effects of intravascular laser irradiation of blood on growth and metastasis of lymphosarcoma in rats

The effect of intravenous blood radiation by low-intensity laser on tumour growth in Wistar rats with Pliss lymphosarcoma has been studied. As a result of single or double blood radiation by laser with wave-length of 510 and 633 nm both the tumour growth inhibition and metastases disappearance have been shown.