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Monte Carlo simulation of FCS in laser gradient field
Bo Chen,
Fanbo Meng,
Yao Ding,
et al.
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Fluorescence Correlation Spectroscopy (FCS) is an attractive technique for probing the molecular kinetics in solutions. However, gradient field due to a focused intense laser field may affect the measured results. Since finding an analytical solution of the diffusion equation in a gradient field is not easy, we developed a Monte Carlo method to simulate Browning motion of Rayleigh particles in a laser gradient field. Effects corresponding to different parameters were tested in the simulation. Simulated results for zero gradient field agree well with the analytical solution, which has been used in all the conventional FCS measurements. Simulated results with gradient fields indicate changes in the fitted diffusion time and the average number of fluorescent spheres <N> in the effective volume. The simulated results agree qualitatively to the experimental results obtained using fluorescent spheres. Empirical relations from the simulation are discussed.
Two-photon fluorescence imaging of rat aorta
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Two-photon excitation fluorescence microscopy has become increasingly popular in 3D fluorescence imaging of tissue samples. Observation depth is an important indicator for the performance of the technique. Using the principle of tissue optics, we analyzed quantitatively the effects of optical properties, such as absorption coefficient, scattering coefficient, and the scattering anisotropy factor of the tissue, to the observation depth. An analytical relation between the fluorescence and the observation depth has been derived and tested against experimental results for rat aorta elastic lamina.
Effect of morphine on PC12 cells with molecular radar
Chen Shi,
Xiaoli Yu,
Jiuyi Lu,
et al.
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Molecular Radar (MR) is a new method to detect biological processes in living cells at the level of molecular, it is also the newest means to get intracellular information. In this paper we study the effect of morphine on PC12 cells using MR. The results show that the effect of morphine on PC12 cells is time- and concentration-dependent. Morphine treating for short time induces the increase and fluctuation of intracellular (CA2+), while morphine treating for long time induces chromatin condensation, loss of mitochondria membrane potential apoptosis.
Visual simulation of diffuse light
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Optical tomography is a kind of noninvasive technology in CT field using multiple photon diffusion. With the method of Monte Carlo simulation we carried out some numerical computation of the diffusion transmission disciplinarian in two kinds of simple biological texture. A ring distribution of diffuse light intensity is found and is sensitive to the incident light relative position to the absorption sphere at some certain conditions. The resolution and incident depth are also discussed through analysis of the image in numeric simulation.
New modeling of OCT with wave optics
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A new model (3D) of OCT based on wave optics and Huygens- Fresnel Principle is derived in this paper. In this model, both axial and transverse information is included so that it can be used to discuss the image properties in both directions. The model is further simplified by narrow-band approximation and plane wave approximation. As applications of the simplified model, we developed Monte Carlo simulation programs to calculate the transverse resolution and to simulate the axial signal of our OCT system. The results well coincides the experiments.
Superresolution of subsampled periodic targets by dual-magnification technique
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Dual-magnification technique for the reduction of moire artifacts, the aliasing of periodic targets caused by sub- sampling, by using two aliased frames of the same periodic target with different optical magnifications is proposed. The technique makes aliasing noise be the source of higher frequency extraction so that superresolution is realized. Simulations and experimental results are presented.
Nanometer indicating system based on surface plasma wave
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A new method for nanometer positioning based on surface plasma wave is reported. A fiber probe approaching a coated prism can be equivalent to a four-layer prism-metal-air- fiber system. Analysis of the near-field beam intensity entering the fiber probe is presented. Theoretical analysis shows that the intensity coupling into the fiber probe changes according to the thickness of air gap. Non-contact nanometer indicating system can be set up according to this characteristic. Experiments show that standard deviation of 2nm and resolution of 0.1nm/nV of positioning repeatability can be achieved under air conditions of +/- 1 degree(s)C/h.
New doughnut mode for optical tweezers and spanners
Chunqing Gao
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The doughnut mode is of great importance in optical tweezers and spanners. Such mode is generated by transforming the Hermite-Gaussian mode of a laser-diode end-pumped Nd:YAG laser through a rotated cylindrical lens system. The field distribution and the intensity profile of the doughnut mode were calculated theoretically from the field of the input Hermite-Gaussian mode. The beam transformation was confirmed in the experiments.
New medical image segmentation algorithm based on Gaussian-mixture model
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In this paper, we propose a probability model based method where the image pixels' features are modeled as Gaussian- Mixture distribution. Then the segmentation problem can be reduced to the estimation of the parameters of the Gaussian- Mixture model. Traditional method of estimating the parameters is EM (expectation maximization). But it has the drawbacks of heavy computational load and sensitivity to initialization. IN this paper, we get the initial parameters for EM by two steps: 1) Anisotropic diffusion is applied to original image. The histogram of the image after anisotropic diffusion is expected to have distinct peaks and valleys to detect, while in original image the modes may be overlapped to detect accurately. 2) A histogram analysis method is presented to deal with parameter initialization. Then the EM algorithm is applied to estimate the parameters iteratively. Due to the good initialization, the heavy computational load and instability of EM are overcome.
Formation of sequence-specific telomeric DNA loops via direct effects of psoralen-photosensitization on telomeres
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DNA from HeLa cells was cleaved with Rasl and Hinf, and then purified by Bio-Gel P-2 column. Results showed that upon near-UV-irradiation, psoralen could be targeted to the repetitive sequences of telomeres. Large duplex loops with a tail were observed directly by AFM. The loop-tail junction position was assumed to be a tri- or tetra- strand DNA structure according to its apparent height, corresponding structure model was proposed. The psoralen cross-linking products increased with increase of irradiation time. The expression of p53 oncogene was significantly increased.
Lasers in the treatment of ischemic heart disease in China
Yongzhen Zhang,
Mingzhe Chen
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Myocardial revascularization by laser is a new treatment modality for chronic, severe, refractory angina in the patients with coronary heart disease that is not amenable to angioplasty (PTCA) or bypass surgery (CABG). Transmyocardial revascularization (TMR), typically requiring open thoracotomy, uses laser to create channels that would directly carry blood from left ventricular cavity into the ischemic myocardium. Current data indicate that TMR may provide these patients with improvement in angina severity, quality of life, and myocardial perfusion. The greatest potential future use of TMR is as an adjunct to CABG in patients with disease that prevents bypass grafting due to lack of distal targets or a conduit. Recently, as percutaneous (catheter-based) myocardial revascularization (PMR) has been developed with laser technology that permits the creation of channels from the endocardial surface of the left ventricle. The early results with PMR seem encouraging. Randomized clinical trial has demonstrated symptomatic improvement and increased exercise capacity. The risk: benefit ratio for PMR appears to be much more favorable than that for TMR. The mechanisms of action of them have not yet been clearly elucidated, and several theories have been proposed, including channel patency, angiogenesis, denervation, and placebo effect. The challenge of TMR/PMR is related to improvement of perioperative outcomes and long-term survival without worsening of left ventricular function. In future, it may be feasible to combine TMR/PMR with intramyocardial delivery of angiogenic growth factors to induce further new blood vessel formation.
Enlargement and enhancement of electronic endoscopic images based on recursive minimum-maximum method
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To compensate for the imperfections of endoscopic mechanical structure and limitations of working space, in paper, a new approach based on recursive minimum-maximum method is proposed to enlarge images of medical electronic endoscopic. This method can be used repeatedly to realize 2n times image enlargement through optimizing the neighborhood information of the interesting pixels in adjustable windows. In order to ensure the best evaluation of the pixel, the algorithm criterion is presented to decide whether the pixel accept new value. Experimental results on applying the method to the endoscopic images are presented in this paper. The results demonstrate that the recursive minimum-maximum method for enlarging images can succeed in images blowing-up at the same time it preserves the fine details with rich edge-information.
Methods for removing honeycomb noise from fiber endoscopic images
Fang Fang,
Meirong Lin,
Yu Guo,
et al.
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The fiber-endoscope has been widely used in medicine. The image fiber bundle usually has pixels from several thousands to tens of thousand. Because of the non-transparent wall cladding of individual fibers, the images putout by the image fiber bundle present honeycomb pattern (noise). It will influence the image visual effect, so it is very important to find methods to remove these honeycomb noise and improve the image quality. In this paper, three methods were used to process the fiber-endoscopic images for removing the honeycomb noise. First, low-pass spatial filtering mask was used to process the image. Secondly, the image special frequency was gotten by Fourier transform, and the honeycomb pattern frequency is separated from the image message. It's possible to remove these honeycomb pattern frequency without degrading the image quality. Finally, the linear interpolation method was used to process the image. We compared the processing results of these methods. These methods can be used in real color images as well as gray level images.
New image reconstruction method for electrical impedance tomography
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Electrical impedance tomography (EIT) is a functional imaging technique, which has potential application prospect in clinical diagnosis. It is well known that image reconstruction in EIT is a highly ill-posed, non-linear inverse problem. So far, various reconstruction methods have been used in EIT, among which the Newton-Raphson method is regarded as the most effective one, but it suffers the mathematical difficulty and the low resolution of the reconstruction which is far from the requirement of clinical application. In this paper, a quite different image reconstruction method for EIT is presented to solve the above problems. In the new method, a neural network such as BP is used to solve the non-linear inverse problem between the impedance variations inside body and the voltage changes measured at its surface with no need of computation of potential fields. The training sets of neural network are chosen from the solution of the forward problem of EIT in which finite element method (FEM) is used. After the non- linear relation function has been decided, the static image reconstruction can be accomplished by iteratively solving the forward problem with FEM until the voltage difference between measurement and calculation or impedance change is small enough. The provided method avoids calculating Jacobian matrix and solving ill-conditioned equations. Furthermore the resolution of the reconstructed images based on the new method is much higher than other methods with the same numbers of electrode and electrical current pattern. The computer simulation results demonstrate that the new reconstruction algorithm can be converged very quickly with a priori knowledge.
Interferometric microscopy with ultrahigh resolution in three-dimensional imaging
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Three techniques for processing interference fringes were described in this paper. The first one is a phase-shifting fringe processing technique with intelligence control. The second is an inverse filtering technique to the fringe processing, and the third kind is a correlation numerical processing technique. The three processing fringe techniques are based on Mirau interferometric microscope.
Differential confocal microscopy with annular pupil filter
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We combine the differential confocal microscopy and annular pupil filter together. The theory of differential confocal microscopy and the property of the annular pupil filter are discussed in detail. The results of computer simulation and experiment prove that this method can extend the axial dynamic range and improve transversal resolution of 3D profilometry at sacrificing axial resolution.
Linewidth compression and measurement in BBO crystal optical parametric generation and amplifier
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In this paper, we present a detailed computer simulation of the linewidth in optical parametric generator and amplifier caused by the divergence angle of pumping, linewidth of pumping beam, off axis phase matching, high gain coefficient of nonlinear optical (NLO) crystal. It is shown that the linewidth of parametric light is very narrow far away from the degeneracy point, and the linewidth begins to large quickly at the degeneracy point. And the off axis pumping and the divergence angle of pumping beam influenced the signal linewidth more quickly than those of other factors did. The signal linewidth to control less than 0.3nm in experiments are obtained.
Optical fiber underwater fluorometer for measuring chlorophyll-a concentration
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This paper describes an efficient method for in-situ measurement of chlorophyll-a concentration in the seawater with fluorescence method and optical fiber techniques. The instrument uses the pulsed xenon lamp as the excited light resources. Both the exciting light and the fluorescence from algae chlorophyll-a are transmitted along two fiber bundles. The fluorescent signal is detected by using the relevant pulsed detecting technology. The minimal detecting concentration of chlorophyll-a in the ocean can reach 1x10-5mg/cm3. The system has advantages of simple structure, passive sensor head and high sensitivity. The experimental results show that this measurement method is realizable.
Development of laser diode deep-acupuncture stimulator and its clinical practice
Haitao Mao,
Qingguo Wang,
Jishan Wang,
et al.
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The laser acupuncture stimulation has been applied extensively, but the laser is diffusely reflected by the skin as well as scattered and absorbed by the subcutaneous tissue, so the curative effect of the laser irradiation on the acupoints is limited. To solve above problem, we have developed the new laser deep acupuncture stimulator of diode. Its lasing wavelength is 630nm. The lasing beam is modulated into the special wave forms (such as sine wave, rectangular wave, etc.). The modulation frequency and phase may be self-synchronized in the patient's pulse. For the multi-acupoint are stimulated simultaneously, there are 3-7 laser pins on this stimulator. The modulated laser beams are coupled into 50/125 micrometers nonofil optical fibers separately. After that they enter into the laser acupuncture pins through the fiber optic connectors. The lasing beams and pins are stimulated as the customary acupuncture in the depth of the acupoints simultaneously. The output power of the single pin is 0.5-1.5 mW. The outside diameter of the pin is 0.4mm. For the price of the acupuncture pin is lower, thus the laser acupuncture pin can be used only once. Seven hundred patients were treated on the period of the clinical practice. The case of illness contains palsy, post-palsy, apoplexy, tenositis and sactalgia etc. The rate of efficiency (cure of improvement) is 85%.
Effect of HeNe laser irradiation on the phagocytosis of macrophages in the immune organs of mice
Mingji Ren,
Yonghong Shi,
Jianwei Wang,
et al.
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In order to study the effect of HeNe laser on macrophages phagocytosis, the are over liver and spleen of the mice was irradiated with NeHe laser at the dosage of 63.7J/cm2 for 3,5,7, and 10 days respectively, 5 min each day, then observing the phagocytosis of macrophages of the immune organs after trypan blue injecting live mice, and made quantitative analysis of macrophages phagocytosis by image analysis system. The results showed that the four indexes: number of trypan blue granule (GN), area of granule (GA), ratio of granule area to cell area (GA/CA) and granule integral optical density (IOD) at irradiated groups were higher than that of control group (P<0.01). Comparison between different irradiated groups were higher than that of control group (P<0.01). The study indicated that HeNe laser with appropriate dosage can activate macrophages of the immune organs, and enhance their organic immunity.
Human motion estimation from a single view
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Human motion analysis is receiving increasing attention from biomedical image processing researchers. In order to reflect the human motion in reality, the body's structure is recovered using its 2D model. This paper proposes a practical system which tracks human motion automatically. The major processing units are as follows: 1) coarse matching between real image and 2D model, 2) fine matching between real image and 2D model, 3) the formation of body structure from 2D model sequence. We first segment a human body from stationary background. Then prior posture database is established, and the primary posture in image sequence can be estimated coarsely by comparing posture in database and real image series. After this, in the precise adjustment stage, precise matching can be obtained by the criterion of region overlay between image sequence and 2D model. Finally, structure of human body is recovered by adjusting parameters of 2D model series, in the above process, the sizes of the body parts are measured manually from one of the picture of real images. Finally, 2D model can be established, and skeleton or frame representation of human body movement is given. In the end of this paper, future directions are suggested for further improvement.
X-ray source with microbeam
Kaige Wang,
Hanben Niu
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A novel x-ray source with micro-beam which has high brightness and micrometers or sub-micrometers micro-focus comprise primarily emitting system, focusing system, and permutable metallic foil targets. In this paper, the axial potential of system has been calculated by means of Boundary element method (BEM) and the electronic trajectory was traced by Runge-kutta method, respectively. The results show that when the temperature of LaB6 cathode is about 1900K and it was set behind the Wehnelt grid accurately and correctly, with partial pressures being kept below 10-7 torr, micro-focus electron-beam (60 microampere current) focused onto the face of target adapts to the producing x-ray micro- beam requirement.
Orthodontics: computer-aided diagnosis and treatment planning
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The purpose of this article is to introduce the outline of our newly developed computer-aided 3D dental cast analyzing system with laser scanning, and its preliminary clinical applications. The system is composed of a scanning device and a personal computer as a scanning controller and post processor. The scanning device is composed of a laser beam emitter, two sets of linear CCD cameras and a table which is rotatable by two-degree-of-freedom. The rotating is controlled precisely by a personal computer. The dental cast is projected and scanned with a laser beam. Triangulation is applied to determine the location of each point. Generation of 3D graphics of the dental cast takes approximately 40 minutes. About 170,000 sets of X,Y,Z coordinates are store for one dental cast. Besides the conventional linear and angular measurements of the dental cast, we are also able to demonstrate the size of the top surface area of each molar. The advantage of this system is that it facilitates the otherwise complicated and time- consuming mock surgery necessary for treatment planning in orthognathic surgery.
Color image segmentation algorithm based on neural networks
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This paper presents a color image segmentation method with Self-Organize Feature Map and General Learning Vector Quantity which, in the uniform color space, divides color into clusters based on the least sum of squares criterion. At the first step of this method, SOFM is employed to make a preliminary classification on the original image, and then GLVQ is used to segment it. Both of their advantages can be fully taken of to improve the precision and velocity of color image segmentation.
Autofocus methods for automated microscopy
Xiaoqiang Wu,
XinMing Liu,
Yiming Zhou,
et al.
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This paper introduced a basis principle of an autofocus system, including the hardware composition and the software flow chart. The most important work of an autofocus system is to construct or select a suitable focus function. We first discussed some traditional focus functions, pointed out their advantages and shortages. Then we proposed a new autofocus algorithm, which based on wavelet transform. We use the diagonal edge information of the result of the wavelet transform to form focus function. After many experiments we draw a conclusion that the wavelet transform method is superiority than others, use it can get a highly accuracy along with a fast speed, special in the biomedical microscopic image analysis. At the last of this paper we discussed the further work related to the improvement of hardware condition and the optimization of focus function.
Design and on-chip synthesis technology of oligonucleotide microarray
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Genechip engineering includes a set of techniques, such as chip fabrication, target gene preparation and hybridization, pattern detection and processing, bioinformatics related to the probe design and data analysis. In this presentation, I would like to give some present results in on-chip synthesizing the oligonucleotides microarray with molecular stamping or microfluidic molds, and developing software for probe designs.
Design considerations for contact laser scalpels
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Contact laser scalpel has been proved to have many advantages over the traditional non-contact ones since it was first proposed and applied in laser surgery in the middle of 1980's. In order to adapt to different clinical applications and achieve optimum curative effect, the emergent power distribution of the contact laser scalpels is crucial, which highly depends on the construction of the contact probes. By means of the development of restraint equations of light propagation in contact laser scalpels, a design scheme for such scalpels is presented. The coupling problems in different parts of the scalpels are considered carefully and their related construction is determined. In addition, because we generally can not describe the emergent power distribution of a contact laser scalpel in an analytic formula, the Monte Carlo method is introduced to simulate the behavior of light transmitting through the scalper. The simulation results are consistent with those of the experimental measurements. Different design parameters that effect the emergent power distribution are also discussed comprehensively.
Optical properties of plastically bent large-diameter sapphire fiber tips for laser tissue ablations
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Aiming to facilitate laser surgery applications, six 0.75mm- diameter 90mm-length sapphire fiber tips were plastically bent by means of CO2 lasers with bending radii from 1.7mm to 3.6mm and bending angles of 15-120 degree(s). The average bending loss caused by the bending process of the tips is about 0.03dB with the minimum loss less than 0.02dB, the damage thresholds of these tips are higher than 160MW/cm2 for Nd:YAG laser pulses at 1.06micrometers and 2MW/cm2 for CuBr laser pulses at 510.6nm. Satisfactory optical properties of these sapphire fiber tips show that they are promising for use in laser surgery applications such as tissue ablations. 16
Fiber optic thermal source for laser surgery applications
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A novel fiber-optic thermal source, consisting of a Nd3+ doped fiber tip and a pure YAG crystal fiber that grown by LHPG(Laser heated pedestal growth) method, had been studied for laser surgery applications. Pumping by a CuBr laser, the thermal source generated temperature as high as 520 degree(s)C with stability of better than 4% (absolute temperature), the thermal response of the thermal source is about 3 seconds, and the temperature can be controlled by the input laser power. Experimental results show that, the fiber-optic thermal source is promising for laser surgery applications, and is expected to avoid overheating that likely to happen in direct laser tissue interactions.
Valid region recognition in digital images of medical x-ray imaging
Jun Gao,
Yixian Wang,
Jie Bao,
et al.
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An important part of Picture Archive and Communication Systems (PACS) is the Digital processing of Medical X ray images. As a result of the fact that the digital images collected by X ray Imaging facilities in Chinese hospitals generally contain many invalid regions, it is useful to recognize the valid regions and make these regions the only regions to process. Recognition of valid regions not only reduces image storage and the quantity of operations, it also improves the quality of the images. In this paper, we discuss an approach to recognize the valid regions and present the results of the experiment.
Diffuse reflectance from biological tissues
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Based on the Monte Carlo modeling of light transport in tissue, the relations of the diffuse reflectance between the optical parameters are studied intensively. The authors presented a new diffuse reflectance fitted formula in which the refractive indices of tissues are included.
He-Ne laser extravascular irradiation therapy
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Based on the study of tissue optics related with the laser irradiation blood therapy, a new treatment method, extravascular low-level laser irradiation therapy (ELLLI) is developed. The veins of 30 patients with cerebrovascular disease combined with diabetes, asthma were treated by He-Ne laser (632.8nm, 25mW) which was delivered by an optics fiber. The fiber was outside the patient's skin and the laser irradiated on the blood vessel perpendicularly. The therapy time was 60 minutes each time and about 7-10 times a course of the treatment. The values of blood sugar, blood- fat and hemorrheology were measured as the effective indexes. After the treatment the effective indexes and the symptoms of the patients were all improved. With the advantages of simplicity and safety (no medical infection), laser extravascular irradiation therapy is likely to be a new medical method for heart brain and other diseases.
Tissue optics related with laser irradiation blood therapy
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This paper introduces the research on the tissue optics related with the laser irradiation blood therapy. The optical parameters of Chinese blood and vascular tissue have been measured, including absorption coefficient, total attenuation coefficient, scattering coefficient and mean cosine of scattering angle. The model of intravascular low level laser irradiation therapy (ILLLI) and extravascular low level laser irradiation therapy (ELLLI) were developed. The light distribution in the vessel and blood of ILLLI is obtained by using Monte Carlo modeling calculation. Based on the light transmission of ELLLI, the optimum irradiation method and laser parameters are presented. This research is useful to the study of laser irradiation blood therapy and tissue optics.
Preliminary study on the biological effect of different laser-induced mutations in peanut seeds
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This paper reports the biological effect and the laser parameter of laser induced mutation in the peanut seeds. Peanut seed were irradiated with laser Ar+ at 488nm, LD at 650nm and YAG at 1060nm. There were different dose from 0.128w/cm2 x 180s to 35.84w/cm2 x 3s. The ultrastructural of plumule cell of peanut seed irradiated were examined by transmission electron microscopy, and the agro-character of M1 peanut were observed. The result shows that different laser with lower dose can promote the peanut seeds growth; to get the same irradiating effect as shorter wavelength laser, long wavelength laser should be increased does; on the same irradiation does condition, the biological effect related to power density and time combined. With irradiation dose increased, the cells structure were destroyed seriously and the rates of seedling lethality increased.
Radiance distributions in biological tissue and the diffusion approximation
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Based on the Monte Carlo simulation, the radiance distributions of different optical properties in biological tissue are given. From the anisotropy of the radiance, the approximation condition of diffuse theory is discussed intensively. It can be concluded that the reduced scattering dominant to absorption be unnecessary. In addition, the reflective radiance distributions on the boundaries show that surface of biological tissues be not the ideal Lambertian diffuser.
Enhancement of angiograms via M-band wavelet transform
Yan Yang,
Dong Zhang
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The paper presents a new approach to enhancing angiograms using M-band wavelet representations. By exploiting directional properties among M-band wavelet coefficients, M- channel directional filters are introduced in the wavelet domain to achieve edge-preserved denosing. Angiograms are then reconstructed from the transform coefficients modified by local enhancement operator based on multiscale edges. The method has lower computational complexity, yet it is capable of giving visually distinct images and offering considerable benefits in medical diagnosis.
Design of diffractive microlens array integration with focal plane arrays
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The IR spectrum from 3 to 5micrometers has numerous applications in both military and civil industries. High performance at high operating temperature is often important in these applications. Conventional Focal Plane Arrays (FPAs) without integration with concentrator such as microlens have poor sensitivity and low signal-to-noise ratio because of their lower fill factor. The binary optics microlens arrays reported in this paper are designed for integration with FPAs. Thus, the FPAs' fill factor, sensitivity, and signal- to-noise ratio can be improved while retaining a given image resolution and optical collection area. In the paper, we discussed the 256(Horizontal)x290(Vertical) microlens arrays designed for a center wavelength of 4micrometers , with 50micrometers (Horizontalx33micrometers (Vertical) quadrate pixel dimension and a speed (F number) of F/1.96. PtSi FPAs were fabricated on the front side of a 400-micrometers -thick Si substrate. The designed diffractive microlens arrays will be etched on the back side of the same wafer in a register fashion and it will be reported in other paper. Considering the diffraction efficiency, 8-phase-level approximation is enough. For the diffraction efficiency of 8-phase-level diffractive microlens reaches 95%. The process only need three mask-level, so we designed and fabricated three masks with the same dimension 4'x4'. Also, a set of fine verniers was designed and fabricated on each mask to allow accurate alignment during the fabrication process. Through a computer simulation, the microlens arrays are nearly diffraction limited, with the diffraction efficiency of 93%, a bit lower than the theoretical value of 95%. Introduction of microlens arrays has the ability to increase the FPAs' fill factor to 100%, while it is only about 21.6% without microlens. To our knowledge, this is the first trial of integration large area microlens arrays with FPAs at home.
Detection of human colonic adenoma by laser-induced autofluorescence integrated with diffuse reflectance spectroscopy
Guilin Tang,
Haibao Lu,
Yangde Zhang,
et al.
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A combined in vivo measurement system integrating laser- induced autofluorescence (LIAF) and diffuse reflectance spectroscopy (DRS) measurement was developed and investigated for detecting colonic adenoma. The system could work with regular endoscopy examination. A three- layer backpropagating neural network (BNN) was built to differentiate the two tissue classes. The preliminary results gave the mean predictive accuracy, sensitivity and specificity better than either of the two methods used alone.
Introduction to photon traditional Chinese medicine
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Photon traditional Chinese medicine (PTCM), and inter- discipline of photonics and traditional Chinese medicine (TCM), studies TCM, such as the diagnostics, therapeutics, indistinct disease theory, rehabilitation, health care and so forth, by using photonics. IN this paper, we will give an introduction of PTCM and review its progress in the collective interaction of low intensity laser irradiation with biological systems, the propagation of low intensity laser irradiation through tissue, the biophotonics representation of acupoint, low intensity laser therapy, TCM laser hemotherapy, laser acupuncture. In this paper, the concept of biological unit was put forward for acupoint and cell membrane receptors to be considered as an identical particle model. The interaction of identical particles was studied by quantum chemistry, as well as the response of the system interacting with physical factors by the time quantum theory on radiation-matter interaction. It was shown that the identical particles from coherent states, the response rate of the super-change state is a linear function of N2 and N3 (N is the particle number), and the one of the sub-change state is zero. Its application led to the explanation of the contribution of biological unit number of acupoint to acupoint specificity and the contribution of cell membrane receptors to low in tensity laser irradiation. The comparative research of acupoint effect and cell function with biophoton emission showed that acupoint states and the membrane receptor state are related to body diseases.
Membrane mechanism of low-intensity laser biostimulation on a cell
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More than one function of a cell can be influenced by low intensity laser (LIL) irradiation, but the others remained unchanged when one function of the cell was altered by LIL irradiation. This phenomenon has been explained by the signal transduction mechanism (STM) on LIL biomodulation. It has been shown in this paper, the membrane receptors collectively mediate STM; as the frequency of the absorption light of membrane receptors is greater than the one of visible laser irradiation, the membrane absorption of visible light is non-resonant, and its transition rate is extraordinarily small, but can be amplified by the coherent state of the identical and independent membrane receptors of a pathological cell.
Information biology on low-intensity laser irradiation effects on red blood cells
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The cytochrome absorption makes the photon act as a carrier of biological energy as the cytochrome system in the mitochondria can absorb the photon and stimulate electron transport, which generates bioenergy in the form of ATP from ADP. Many feel that the respiratory chain is at the base of any effects that laser therapy might have. However, there is a kind of effect of He-Ne laser irradiation on red blood cells (RBC) in which there is no mitochondria. In other words, the photon acts also as a carrier of biological information. Recently, Liu et al have studied the information biology on low intensity laser by use of time approach on generation of biological information, and put forward the membrane-receptor-mediated signal transduction mechanism, i.e., the biological information model of low- intensity laser (BIML) and the biological information transformation model (BITML), to explain the biomodulation function. As the frequency of the absorption light of membrane receptors is greater than the one of visible laser irradiation, the membrane absorption of visible light is non-resonant, and its transition rate is extraordinarily small, but can be amplified by the coherent state of the identical and independent membrane receptors of a pathological cell. In this paper, we apply these results to study Information biology on low intensity laser irradiation effects on RBC.
Sonoluminescence imaging and its biomedical applications
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Sonoluminescence (SL) images of living bodies were obtained by a luminescence enhancement method with a high-sensitive back-illuminated CCD system. We found that the rare-gas- contained (prepared) PBS or some nonpoisonous chemiluminescent analytic agent could enhance the SL by chemiluminescence through a reaction with free radicals, and can be used for in vivo experiments. Based on ultrasound could sensitize HpD to produce the oxygen free radicals, a novel method for early-stage cancer diagnosis named as Sono- Dynamic Diagnosis was proposed. By use of sonosensitization to produce tumor-selective oxygen radicals, a clear diagnostic image of FCLA (Fluoresceinyl Cypridina Luminescent Analog)-enhanced sono-pumped chemiluminescence from tumor region is obtained. Finally, a confocal scanning technique was developed for the sonoluminescence tomography imaging for the first time. The spatial resolution was largely improved to about 100 micro with the ultrasonic intensity less than the safety limit of FDA. With the components-labeling and confocal techniques, the SL imaging method has potential applications in clinical diagnosis.
Free-calcium distribution and calcium pulses in rat peripheral macrophages
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With Laser Confocal Scanning Microscope (LCSM) system, three aspects of characteristics of free cytoplasmic calcium in rat peripheral macrophages are studied. One is the Ca2+ concentration in different area in the same cell. Second is the Ca2+ concentration in the same area in different dividing stage. Third is the feature of calcium pulses evoked by Kcl or pH changing. The results show that even in one cell, the evolution of the Ca2+ concentration is not the same in a different area. In the same area, the nucleolus Ca2+ concentration in division breaking stage is much higher than that in division stage. From the experiment phenomena, we conclude that Kcl itself can not evoke calcium pulses in the unexcitable macrophage, but the change of pH can trig calcium pulses in the same cells.
Determination of simulated burn depth using relative fluctuation of backscattering light
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The determination of burn depth is an important problem for surgeons to remedy severe skin burns. The burn can be simplified as a two-layer media model: a static layer and a dynamic layer. In this paper, the relative fluctuation of backscattering light was used to distinguish the simulated burn depth. The experimental results show that the relative fluctuation of light intensity increases with the increasing of simulated burn depth. The depth less than 0.1mm can be resolved in the present experiment. This new method may be very useful for burn diagnosis in clinics.
Correlation properties of scattering light in ultrasound-modulated random media
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In this paper, the correlation properties of scattering light in ultrasound-modulated media were studied. The expression of temporal auto-correlation function of scattering light amplitude in an infinite media was presented. The feature of autocorrelation function was studied. The modulation amplitude of the correlation function decays with the correlation time and the decreasing becomes quickly as the Brownian diffusion coefficient increases. The autocorrelation imaging of hidden objects in random media was also discussed by use of Monte Carlo simulations.
Ultraweak biophoton emission of new and aged rice seeds during early imbibition
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The characters of ultra-weak biophoton emission (UBE) of rice seeds during the initial imbibition period (0-1 hour) were observed with high sensitive single-photon-counting equipment. The results showed that the shorter the seed store time, the higher the intensity and the increase rate of the UBE in the early imbibition period (0-10 minus). It was concluded that the store time of rice seeds could be judged from their UBE characters during the early imbibition period, which might be a way to examine new and aged seeds. In addition, there were differences in rise rate, peak value and attenuation tendency of UBE among new seeds of different strains during the early imbibition period. It indicated that such characters of UBE might be quantitative indexes to identify new rice seeds.
New method of ultrasound-modulated optical tomography
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A new method of ultrasound-modulated optical tomography is reported, which ultrasound wave is amplitude modulated to increase detection sensitivity and signal-to-noise rate. Near-infrared laser is incident to tissue simulating medium and modulated by focused ultrasound. A buried object in simulating medium mis imaged with modulated multi-diffuse light that pass through ultrasound focal zone. The light signal is demodulated by real-time FFT. A two-dimensional tomographic image is obtained through scanning and detecting the ultrasound-modulated optical signal.
Experimental research of photodynamic diagnosis mediated by chemiluminescence reagents
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There are some serious limitations existing in conventional photodynamic diagnosis (PDD), such as autofluorescence disturbance, weak red-band absorption efficacy of traditional photosensitizers and quite short penetration depth of excitation light. In this paper a novel method of PDD mediated by chemiluminescence reagents is presented in fabricated mixed samples. Photodynamic therapy (PDT) is believed to act via singlet oxygen (1O2) generated by energy from photosensitizers. 5-Fluoresceinyl Cypridina Luciferin Analog (FCLA), a chemiluminescence reagent, can react with singlet oxygen and emit chemiluminescence with peak wavelength about at 526 nm. In the experiments, FCLA was chosen as an optical reporter of localization of singlet oxygen produced from photosensitized reaction of Hematoporphyrin Derivative (HpD) excited by 630 nm laser. Experimental results, the measurement of fluorescence spectra and the detection of image from chemiluminescence, show that the mixed HpD and FCLA in biologic tissue mixture excited with the laser of 630 nm can emit detectable light signals.
Insoluble components in human gallstones by Raman and IR spectroscopy
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Human gallstones were immersed with chloroform, ethanol and ether. The insoluble components were studied by normal Raman (SER) and FT-infrared (IR) spectroscopy. The results show that bilirubinate salts and proteins are the main components in the insoluble materials of gallstones. The secondary structure of the proteins in gallstones are dominated by (alpha) -helix structure. The results suggest that proteins play a key role in the formation of gallstones.
Monte Carlo study of light distribution in biological tissues with different types of incident beams
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In this paper, we use Monte Carlo method to simulate the diffuse reflectance and transmittance of laser light in dermis with different incident beams, including infinitely narrow beam, Gaussian beam and flat beam with different radiuses respectively. The results show that photon density distribution of infinitely narrow incidence is adaxial, and when finite size beams are incident, if the radius is small, the photon distribution is also adaxial, and with the radius rising, the photon density decreases rapidly along the r- axis.
Enhanced sonoluminescence of tissues
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In this paper, biological sonoluminescence (SL) of different tissues was investigated for the first time. Tissue samples (muscle, liver and fat) were prepared and put into a column- shaped ultrasound field. A photomultiplier tube and a back- illuminated cooled CCD were used to detect the SL signal. In the experiments, FCLA (Fluoresceinyl Cypridina Luminescent Analog) was used to enhance SL. With the chemiluminescence technique, we suggest that the biological SL mainly come from the free radicals produced by the ultrasound cavitation, which is different from the mechanism of the SL in aqueous solutions.
Photoacoustic imaging of a biological sample using in-phase-sum focus algorithm
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Photoacoustic (PA) imaging is a new imaging modality, which converts pressure signals received by an array of transducers to a regional distribution of electromagnetic absorption density. In this paper we present an experiment result of a photoacoustic imaging to depths of approximately 3mm for a fabricated absorber within a real tissue, using a 1064-nm pulse YAG laser. The time-resolved stress detection technique was used for PA signal detection and an in-phase- sum-focus algorithm was used for image reconstruction. To obtain excellent temporal resolution, a wideband PVDF membrane hydrophone and a fast-digitizing oscilloscope was used for time-resolved detection of PA signals. A computer controlled translation stage on which the sample cell was fixed was used to a 2D scanning mode. Images of different depth profile was obtained with a lateral and depth resolution of approximately 0.5mm.
Determination of biological tissue property by spectrum of photoacoustic signal
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Photoacoustic signals generated in solid and liquid are detected, and its characteristics are analyzed in time domain and in frequency domain. The results show that spectrum of photoacoustic signal changes with the property of medium sensitively, so it maybe is a potential approach to diagnose special disease at the early stage.
Absorption of human skin and its detecting platform in the process of laser cosmetology
Yong-Lin Zhang,
Li Ouyang,
Yang Wang
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Because of the melanin, hemoglobin and water molecules, etc. contained, light absorption of human skin tissue changes with wavelength of light. This is the principle used in laser cosmetology for treating pigment diseases and vascular lesion diseases as well as skin decoration such as body tattooing, eyebrow tattooing, etc. The parameters of treatment used in laser cosmetology principally come from the research of the skin tissue optical characteristics of whites, and it is not suitable for the Oriental. The absorption spectrum of yellow race alive skin has been researched. The detecting platform for use in the measuring of vivi-tissue absorption spectrum has been developed which using opto-electronic nondestructive testing and virtual instrument techniques. The degree of pathological changes of skin can be detected by this platform also, thus the shortcoming of dosage selection in laser clinical treatments which have been decided only by naked eye observation and past experience of doctors can be solved.
Design of the deeply etched binary optics even device for the exposure system of the quasimolecule laser
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In this paper, the new binary optical even device is presented. Whose phase depth exceeded 2(pi) . This device has the characteristics of less weight, convenient adjusting, high utilization rate of energy and well- distributed light beam, which can be used in quasi-molecule laser exposure system.
Study of brainwave frequency spectrum by AFT and FFT
Zhiling Jiang
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A new Fourier analysis technique caller arithmetic Fourier transform (AFT) is presented in this paper. This algorithm gives a new approach for the fast computation of discrete Fourier transform (DFT) at an arbitrary length. The fast Fourier transform (FFT) combined with AFT is used to analyze the electroencephalogram (EEG) in the frequency field. This method overcomes the disadvantage of the traditional FFT and improves speed and accuracy of the calculation.
High-definition laser display system using multibeam scanning
Zhenming Zhao,
Yongda Li,
Baihe Lang
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The design and principles of a high definition laser display system with multi-beam scanning are described. The system employs 4 laser beams each being composed of red, green and blue components. The four beams from one scanner are scanned simultaneously by a rotating polygonal mirror for horizontal deflection and by a galvanometer for vertical deflection. Compared with conventional single-beam scanning, the new design has the following advantages: 1) The rotational speed of the polygonal mirrors can be reduced by a factor of 4, which would improve the system performance and decrease the difficulties of the manufacture of the system. The size of the polygonal facet and, therefore, the laser beam diameter can be increased which would decrease the pixel diffusion. 2) The simultaneous operation of the 4 modulators would improve the horizontal resolution by a factor of 4. 3) For the same screen brightness, the single pixel power density can be reduced by a factor of 4 which would decrease the hazardous laser radiation.
Data analysis in green-fluorescent-protein-based fluorescence resonance energy transfer
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Green fluorescent protein based fluorescence resonance energy transfer is widely used in studies of inter-and intra-molecular dynamic interactions in alive cells. But it is a trade off between quantitative measurement and real time measurement because of the emission cross talk. In stead of using more than one excitation wavelength and several sets of filters, we proposed a more efficient correction scheme which needs only a single excitation and one filter set. This method makes use of the known emission spectra of the fluorophores and can be run in real time. The validity and advantages were demonstrated by experiments with chamaeleons.
Fluorescence spectrum of normal and carcinoma human lung tissue
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Laser-induced fluorescence (LIF) is a promising method for pre-malignant lung tissue diagnosis and it is very important to find effective common diagnosis criteria needed by clinic. In this paper, some differences between normal and cancer lung tissue, such as I444/I414 ratio, main peak width, and integral area were exhibited and discussed. By using the fourth harmonic at 266nm of a Q-switched Nd:YAG laser as an excitation source, Optical Multi-channel Analyzer (OMA) as a detector, laser-induced fluorescence spectra of normal and cancer lung tissue in-vitro were measured. According to the spectra characteristics, three independent diagnosis criteria were obtained and analyzed. The total specificity is above 95%.
Confocal scanning fluorescence detection system and its optimization
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Fluorescence detection by confocal scanning systems has advantages of large area detection, small focus depth, large numerical aperture, complete laser rejection, low background noise, high sensitivity and S/N ratio. It is a sensitive and precise method to record and analyze results of biological or biomedical assay, such as DNA hybridization assay or micro capillary electrophoresis assay on biochip. Parameters like power of laser or sensitivity of PMT are responsible for signal to noise ration and sensitivity of the system, which should be optimized relative to different situations. The structural design and experimental analysis on parameter optimization of a confocal scanning fluorescence detection system are presented in this paper.
Optic fiber Fabry-Perot interferometer made through ionic self-assembly approach
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Polyelectrolyte multilayer thin films were coated onto flat glass substrates and optic fibers by using the ionic self-assembly technology. The deposition of the multilayers was monitored by using UV-vis spectroscopy, and the assembled thin films were characterized by small-angle X-ray reflectivity. Optic fiber polymer Fabry-Perot cavities were created by assembling polyelectrolytes onto the end faces of glass fibers, and the Fabry-Perot interference phenomena has been observed. It can be expected that novel fiber optical devices, such as Fabry-Perot filters, reflectors and Fabry-Perot cavity-based fiber optic sensors, can be developed via this approach.
High-power microwave generation using high-gain photoconductive semiconductor switches
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This research has focused on optically triggered, high gain nonlinear GaAs switches for high speed, high power microwave generation. A microstrip and a parallel-plate pusle generator have been constructed and tested. The experimental results are reported. Further studies on optically triggered, high gain, nonlinear PCSS are proposed.
Image reconstruction in near-infrared time-resolved optical tomography using analogous parallel-beam scanning mode
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An experimental system for time-resolved optical tomography has been constructed from Ti:Sapphire laser and synchroscan streak camera. With a 3D step-motor driving translation- rotation stage, the system can scan the object to be imaged in a parallel-beam mode analogous to X-ray CT, by which the time-resolved projections at a variety of incident angles can be obtained automatically. By applying a nonlinear image reconstruction algorithm, the promising images have been produced from the time-resolved measurements for three kinds of tissue-like phantoms that represent the different combinations of the absorption and scattering properties of the embedded single inclusion. Our results have demonstrated this system as a reliable and ideal platform for the research of time-resolved tomographic imaging.
3D-image-based collaboration system for telemedicine
Toshihiko Kobayashi,
Syuji Satou,
Hao Jiang,
et al.
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This paper described a 3D image based collaboration system for telemedicine. This system enables doctor to observe 3D images transferred from image database through network, and also has collaboration function which operate 3D position of viewing of each doctor by 3D image displaying and data transferring through network. It is constructed based on server client style, and the server has the function of transferring data from a 3D image database and a collaboration record database, and also has control unit of transferring data between doctors during operating the system. The client has a user interface including operation part for parameter selection of viewing and sending comments, and display part for displaying 3D image based on volume rendering and 3D position and direction of observer by suing avatar. Doctors can use this system to do collaboration work by sending comments with viewing 3D image each other. We implement this system in different platforms including UNIX workstation and PC, and also supply Web browser based user interface for considering various user environments. We applied the 3D images of MRI in head for examining the structure of soft tissues and tumor in detail. We also evaluated the performance of the system through network including LAN and Internet, and experimental result shows that this system is useful.
Electron microscopy study of antioxidant interaction with bacterial cells
Oleg P. Plotnikov,
Olga V. Novikova,
Nikolai P. Konnov,
et al.
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To maintain native microorganisms genotype and phenotype features a lyophylization technique is widely used. However in this case cells are affected by influences of vacuum and low temperature that cause a part of the cells population to be destruction. Another factor reduced microorganisms vitality is formation of reactive oxygen forms that damage certain biological targets (such as DNA, membranes etc.) Recently to raise microorganism's resistance against adverse condition natural and synthetic antioxidants are used. Antioxidant- are antagonists of free radicals. Introduction of antioxidants in protective medium for lyophylization increase bacteria storage life about 2,0-4,8 fold in comparison with reference samples. In the article the main results of our investigation of antioxidants interaction with microorganism cells is described. As bacteria cells we use vaccine strain yersinia pestis EV, that were grown for 48 h at 28 degree(s)C on the Hottinger agar (pH 7,2). Antioxidants are inserted on the agar surface in specimen under test. To investigate a localization of antioxidants for electron microscopy investigation, thallium organic antioxidants were used. The thallium organic compounds have an antioxidant features if thallium is in low concentration (about 1(mu) g/ml). The localization of the thallium organic antioxidants on bacteria Y. pestis EV is visible in electron microscopy images, thallium being heavy metal with high electron density. The negatively stained bacteria and bacteria thin sections with thallium organic compounds were investigated by means of transmission electron microscopy. The localization of the thallium organic compounds is clearly visible in electron micrographs as small dark spots with size about 10-80nm. Probably mechanisms of interaction of antioxidants with bacteria cells are discussed.
High-resolution optical tomographic imaging of human gastrointestinal tissue in vitro with optical coherence tomography
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Optical Coherence tomography is a recently developed imaging technique that has potential to improve the diagnostic limits of the currently available imaging techniques, allowing wide range of clinical disorders to be addressed at an early stage. To assess the clinical applicability of OCT, both the normal and pathological specimens from the G.I. tract were imaged, including oesophagus, oesophago- gastric junction, stomach and colon. Sharp differentiation of structures and features was observed between different stages of tissue. The images acquired in this study provide information on tissue microstructure that could only previously be obtained with conventional excisional biopsy.
In-vivo and in-vitro study of control of rat skin optical properties by action of osmotical liquid
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We present experimental results on optical properties of the rat skin controlled by administration of osmotically active chemical, such as glycerol. In vivo reflectance and in vitro reflectance and transmittance spectra of the rat skin were measured. Results of experimental study of influence of glycerol on reflectance spectra of the rat skin are presented. The significant increase of transmittance and decrease of reflectance of the rat skin under action of osmotical agent are demonstrated. Basing on mathematical modeling the optical parameters of the rat skin are determined.
In-vitro study of penetration of magnetic particles into the human skin
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We present experimental study of penetration of magnetic particles into the human skin in vitro. The administration of the particles through he skin into the body leads to localization and retention of the particles at the desired site. This technology can be used for selective damage of tumor cells by hyperthermia or to remove unwanted or excess hair. The maximal depth of particle penetration into the skin achieved in this paper was 0.7mm.
Tissue image contrasting using optical immersion technique
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Experimental data for in vitro and in vivo studies of various solutions action on optical properties of human tissues is presented. The dynamics of tissue optical properties depending on matter diffusion rate within tissue is studied. The possible application of refractive index matching effect for tissue imaging is discussed. Results on optical properties control of the human sclera, skin, connective tissue membranes, such as dura mater, muscle and blood due to their impregnation by the osmotically active chemicals, such as trazograph, glucose, propylene glycol, glycerol are presented.
Imaging of lymph flow in single microvessels in vivo
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In this study parameters of lymph microcirculation are investigated. The microcirculation was studied on small intestine mesentery in norm and during Dimethyl sulfoxide (DMSO) application. The direct measurement of lymph flow velocity (parameter V) in individual microvessels was based on the technique of light intravital videomicroscopy. The first spectral moments of Doppler signal, characterizing the mean velocities of lymph flow in microvessels (parameter M1), were measured by speckle-interferometrical method. Simultaneously, diameters of lymph microvessels as well as parameters of phasic contractions and valve function of lymphatics were registered. The value of V was very changeable; the mean V was equal to 270+/- 24micrometers /s. The M1 was the varying characteristic of the lymph flow too. The temporal dynamic of M1 was reflected alternating- translation motion of lymph flow. DMSO application during 15 min caused the constriction in a majority of lymphatics and the phasic contractions. DMSO induced lymphostatis in 20% of cases. But the other microvessels responded to the rise of lymph flow velocity. These changes led to the stimulation of drainage function of lymph microcirculation function.
Functions of laser light, laser-absorbing dye, and immunoadjuvants in photodynamic immunotherapy
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Photo Dynamic Immuno Therapy (PDIT) is a novel approach for treatment of metastatic tumors. It involves an intratumor administration of a laser-absorbing dye and an immunoadjuvant, followed by a non-invasive laser irradiation. Previous studies using a novel immunoadjuvant, glycated chitosan, showed the effect of the treatment on a metastatic breast tumor in rats, including the eradication of treated primary tumors, regression of untreated metastases, and the evidence of immune responses induced by the treatment. To further understand the mechanism of PDIT, tumor-bearing rats were treated by different combinations of the three PDIT components. The rat survival rates and profiles of primary and metastatic tumors, after treatment by individual component and different combinations of components, were analyzed. All the experimental groups without using immunoadjuvant showed none or little positive effect. The use of glycated chitosan, either by itself or in combination of other components, has showed that among the concentrations of 0.5%, 1% and 2%, glycated chitosan was most effective at 1% in PDIT. Another immunoadjuvant, incomplete Freund's adjuvant, was also used and the results were compared with that of using glycated chitosan. PDIT was applied to a different tumor model- Met-Lu, a prostatic tumor with lung metastases in male rats and the preliminary results are reported.
Autofluorescence properties of skin and applications in dermatology
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Skin autofluorescence was observed as early as 1908. Its applications in dermatology was first reported in 1925- the use of Wood's lamp for the detection of fungal infection. In the first part of the paper, a historical review was presented on skin autofluorescence properties. In the second part, systematic research done in out laboratory on autofluorescence properties of normal and diseased skin was summarized. We developed three tools for the study: 1) a compact fiber optic spectrometer for in vivo macroscopic fluorescence spectral measurements on volunteers and patients; 2) a CCD camera based fluorescence imaging for in vivo macroscopic imaging of 2D fluorescence intensity distributions over various skin diseases; 3) a fiber optic microspectrophotometer (MSP) system for in vitro microscopic fluorescence spectral measurements and fluorescence imaging of frozen tissue sections. With these tools, we obtained the excitation-emission matrices (EEMs) of in vivo normal skin, the temporal dynamics of skin autofluorescence decay under continuous wave laser exposure, and fluorescence spectra of 1500 lesions from 600 patients spanning 35 disease types. Monte Carlo simulation has been employed to explain the autofluorescence decay dynamics and to reconstruct the in vivo spectra from in vitro microscopic fluorophore distribution and intrinsic fluorescence spectra of various skin structures. Spectral feature based linear discrimination function analysis and principal components decomposition analysis are performed to assess the potential of autofluorescence spectroscopy for skin cancer detection. Clinical test of a fluorescence scope system for skin cancer margin delineation is under way.
Statistical characteristics of optical response of random medium with cylindrical scatterers
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A model of a scattering biological 3D medium with irregularities in the form of the monoorientated cylindrical particles is considered. It is assumed that these scatterers have random geometrical parameters and randomly located in the space with Poisson statistics. Their optical parameters differ from the corresponding background values. The characteristic functional of such random field and its derivatives that give the expressions for the mean value and autocorrelation function are analytically obtained. The Wiener- Khinchine's spatial spectrum is calculated too. The obtained expressions contain the statistical moments of geometrical and optical parameters of scattering centers and their space density.
Field emission x-ray tube for mammography
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We propose to develop a time-gated x-ray imaging technique for screening mamography. If successful, it will greatly improve the accuracy of current mammography with about 50% reduction of current patient radiation. The technique can be applied to other x-ray imaging procedures also. We are now working to determine the feasibility of the key technologies- an x-ray source that can be pulsed on and off at a subnanosecond rate and a detector that can be gated at the same rate- that represent potential roadblocks to achieving this goal. A field emission x-ray tube will be used as the source. The field emission cathode consists of a substrate with sharp points and a metallic grid. A voltage on the grid creates an electric field that produces tunnel emission from the array of tips. The geometry of such a tube make electron optics easier, high currents are possible and the tube can be turned on and off rapidly. It also appears that synchronous electronic gating of the detector is possible.
10-year experience of CO2-laser application in ambulance gynecology
Michael L. Stachanov,
Victor I. Masychev,
Leonid Z. Velsher,
et al.
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CO2-laser surgical systems have come to stay in everyday practice of modern physicians and are successfully used in colposcopic and laparoscopic surgery. Results, obtained in ambulance gynecology are especially impressing. CO2- laser provides high medical- and cost-effective treatment. Presented work describes many-years experience of CO2- laser application. 439 patients with various vulvaric and cervix diseases were operated within this period. Laser beam parameters were selected according to requirements ((tau) =4 J/cm2) treatment without carbonization. Analyses of the results showed that the laser successfully destructs uterine cervix erosion, endocervicosis, dysplasia, leukoplakia, eritoplakia of uterine cervix, various benignant pathologies and focus degenerative process in ambulate conditions.
Mathematical modeling and fiber optics parameter optimization in diagnostics of biotissue by PNC method
Alexander A. Sokolovsky,
Victor I. Masychev
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Optical PNC-diagnostics is one of the methods to diagnose biotissue in norm and pathology. In primary case backscattering and fluorescent components of detected secondary radiations are registered by means of PNC-method. These radiations are stimulated and occur when probing laser beam radiates biotissue. For diagnostic purposes both monofibers and multifiber probes (fiber bundle), where probing radiation transmits to biotissue via one of the fibers, are usually used. Registered secondary radiations from biotissue are detected by distal end of a multifiber probe (peripheral fibers). This work was intended to mathematically modulate and determine optimization parameters of fiberoptic probes, applied in PNC-diagnostics inclusive localization and depth of pathological underskin hearth. Main mathematical correlations and formulas for calculation and optimization of backscattering radiation in dependence on applied waveguide characteristics inclusive radiation absorption in biotissue were obtained. All calculations are made regarding each biotissue layer as reflective or Lambert quasi-source of backscattering signal. It is found out, that varying parameters in a probe we can vary the depth of tissue where the maximum signal received from and optimize the value of the signal.
Noninvasive imaging of biological tissue structure, function, and abnormalities with optical coherence tomography
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Optical coherence tomography (OCT) is a novel noninvasive optical imaging technique that enables cross-sectional imaging of highly scattering biological tissues at the axial resolution of 10 micrometers or less. Technological advances in our laboratory and others have been permitted high-contrast and high-resolution OCT imaging of turbid biological tissues at depths of up to 2-3 mm, highly desirable for screening various kinds of superficial lesions and the invasion of these lesions. In this study, we will demonstrate the potential of OCT as a powerful tool of optical biopsy or optical guided biopsy for the purpose of noninvasive imaging diagnosing malignancies in these tissues. We will present ex vivo OCT images of animal urinary bladders and lesions (including cancers) in these tissues in comparison with the corresponding histologic evaluations. Based on the comparative studies between OCT and histology, we will analyze the image contrast of OCT or the patterns in OCT images in relation to the micro morphologies in these tissues and their alternations or lesions at different stages of tumorigenesis. We will also analyze the image contrast of OCT related to the blood vessels as well as other tissue functions such as fluid penetration and buildup in these tissues. Our results demonstrate the utility of OCT in high- resolution imaging to delineate the micro morphology of highly scattering tissues such as urinary bladders and the clinical relevance of OCT in diagnosing alternations or tumor growth in these tissues. Because of limitations to specificity and resolution of current techniques, OCT is presently unable to provide distinctive diagnosis of malignancies that require subcellular imaging or identification of subtle changes in nuclear morphology. However, certain characteristics associated with malignancies in bladders such as heavy vascularization and proliferation within the urothelial tissue can be clearly demonstrated.
Modeling complex tissue optics and boundary conditions with simple perturbation theory
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The modeling of the complex tissue optics of a light- scattering tissue with imbedded objects of irregular shape with variable absorption and scattering properties can be accomplished with a relatively simple computation based on perturbation theory. The general method has been described. This report describes the specifics of how to implement the method for steady-state light distributions and adds an air/tissue boundary of irregular shape.