Proceedings Volume 4427

Imaging of Tissue Structure and Function

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Proceedings Volume 4427

Imaging of Tissue Structure and Function

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Volume Details

Date Published: 22 August 2001
Contents: 2 Sessions, 16 Papers, 0 Presentations
Conference: Imaging of Tissue Structure and Function 2001
Volume Number: 4427

Table of Contents

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Table of Contents

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  • Light Interaction with Tissues and Cell Structures and Imaging Techniques
  • Optical Diffusion and Laser Doppler Imaging Systems
Light Interaction with Tissues and Cell Structures and Imaging Techniques
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Human brain activity with functional NIR optical imager
In this paper we reviewed the applications of functional near infrared optical imager in human brain activity. Optical imaging results of brain activity, including memory for new association, emotional thinking, mental arithmetic, pattern recognition ' where's Waldo?, occipital cortex in visual stimulation, and motor cortex in finger tapping, are demonstrated. It is shown that the NIR optical method opens up new fields of study of the human population, in adults under conditions of simulated or real stress that may have important effects upon functional performance. It makes practical and affordable for large populations the complex technology of measuring brain function. It is portable and low cost. In cognitive tasks subjects could report orally. The temporal resolution could be millisecond or less in theory. NIR method will have good prospects in exploring human brain secret.
Novel photobleaching model in living cells
A novel photobleaching model was proposed, in which a D-P photobleaching mechanism was developed. By combining with the conventional D-D and D-O photobleaching mechanisms, the dependence of photobleaching rate on the excitation power is well illustrated. The validity of this model was demonstrated with GFP photobleaching experiments in cases of one-photon excitation (1PE) and two-photon excitation (2PE) respectively. Previously inexplicable experimental results published in literature were also illustrated with this new model.
Spatio-temporal characterization imaging of Ca2+ oscillations in rat hippocampal neurons
Zhihong Zhang, Jinling Lu, Wei Zhou, et al.
Ca2+ is the most common signal transduction element in cells and plays critical rolls in neuronal development and plasticity. Ca2+ signals encode information in their oscillation frequency or amplitude and response time to regular cellular function. In this study, in order to reveal the spatio-temporal characterization of Ca2+ oscillations in rat hippocampal neurons, two kinds of Ca2+ fluorescent probes, yellow cameleons 2.1 (YC2.1) and Fluo-3, were used to monitor the change of the intracellular free Ca2+ concentration (]Ca2+[i). Spontaneous Ca2+ oscillations and glutamate elicited Ca2+ oscillations were observed with multi-photon excitation laser scan microscope (MPELSM) and confocal laser scan microscope (CLSM). The observation showed that the spatio- temporal characterization of either spontaneous or glutamate provoked Ca2+ oscillations had difference between the neurites and somata in individual nerons, especially in some distal end of neurites. The result indicated that Ca2+ oscillations were most important signal transduction pattern in neuronal development and activation. The spatio-temporal characterization of difference of Ca2+ signals between the distal endo of neurites and the somata might be associated with the distribution of ionotropic receptor and metabotropic glutamate receptors, and Ca2+ response mechanism mediated by two kinds of glutamate receptor. Ca2+ signal elicited by glutamate in the distal end of neurites appeared more complex and generated faster than that in the somata. It was suggested that Ca2+ signal in glutamate stimulated hippacamal neurons first generated from the distal end of neurites and then transduted to the somata. The complicated Ca2+ signal characterization in the distal end of neurites might be associated with neuronal activitation, neurotransmitter releasing, and other functions of neurons.
Laser biomodulation on stem cells
Timon Cheng-Yi Liu, Rui Duan, Yan Li, et al.
Stem cells are views from the perspectives of their function, evolution, development, and cause. Counterintuitively, most stem cells may arise late in development, to act principally in tissue renewal, thus ensuring an organisms long-term survival. Surprisingly, recent reports suggest that tissue-specific adult stem cells have the potential to contribute to replenishment of multiple adult tissues. Stem cells are currently in the news for two reasons: the successful cultivation of human embryonic stem cell lines and reports that adult stem cells can differentiate into developmentally unrelated cell types, such as nerve cells into blood cells. The spotlight on stem cells has revealed gaps in our knowledge that must be filled if we are to take advantage of their full potential for treating devastating degenerative diseases such as Parkinsons's disease and muscular dystrophy. We need to know more about the intrinsic controls that keep stem cells as stem cells or direct them along particular differentiation pathways. Such intrinsic regulators are, in turn, sensitive to the influences of the microenvironment, or niche, where stem cells normally reside. Both intrinsic and extrinsic signals regular stem cell fate and some of these signals have now been identified. Vacek et al and Wang et al have studied the effect of low intensity laser on the haemopoietic stem cells in vitro. There experiments show there is indeed the effect of low intensity laser on the haemopoietic stem cells in vitro, and the present effect is the promotion of haemopoietic stem cells proliferation. In other words, low intensity laser irradiation can act as an extrinsic signal regulating stem cell fate. In this paper, we study how low intensity laser can be used to regulate stem cell fate from the viewpoint of collective phototransduction.
Microinvasive laser surgery for laryngeal carcinoma
Jinping Lai, Zhengde Tao, Jianyun Xiao, et al.
Objective: To investigate the effectiveness of microinvasive Nd:YAG laser surgery in case of early stage laryngeal carcinoma as well as it's effect on the cellular immune function of the tumor-bearing hosts. Material and Method: Thirty-seven patients with glottic Tis or T1 SCC were treated by fiberoptic laryngoscopic Nd:YAG laser surgery. Both before and after therapy, serum levels of soluble interleukin-2 receptor (SIL-2R) and interleukin- 2(IL-2) as well as the NK activity were determined via double-antibody sandwich technique, tritiated thymidine- deoxyribonucleoside incorporation and iodine 125-uridine- deoxyribunocleoside release technique, respectively. Result: All 37 patients tolerated the procedure well. A 3-8 year follow up in a subgroup of 31 patients resulted in a estimated cure rate of 87.1% (27/31). The posttherapy serum levels of SIL-2R were significantly declined (p<0.001), while those of IL-2 and NK activity were significantly elevated (p<0.001) as compared with those detected pretherapeutically. Conclusion: Therapy with fiberoptic laryngoscopic Nd:YAG laser surgery is simple, safe, effective and microinvasive for the patients with early stage laryngeal carcinoma and has an immuno-enhancing effect on its host.
Eye tissues study
Theoretical and in vitro and in vivo experimental study of spectral and polarization characteristics of the human and rabbit eye tissues are presented. The possibility of control of optical properties of eye cornea, lens and sclera is discussed and realized experimentally for glucose solution as the refractive index matching factor.
Optical Diffusion and Laser Doppler Imaging Systems
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Dynamic optical coherence tomography of blood layer
The concept of refractive index matching used for the enhancement of optical penetration depth of the whole blood is discussed on the basis on in vitro studies using NIR optical coherence tomography technique. It was found that blood optical clearing is defined not only by refractive index matching effect, but also by changes of the RBC size and their aggregation ability when chemicals are added. For example, for whole blood twice diluted by a saline adding 6.5% of glycerol reduces the total attenuation coefficient from 4.2 mm-1 to 2.0 mm mm-1, and correspondingly increases the optical penetration at 820 nm up to 117%. For other tested agents (glucose, dextrans, propylene glycol, and trazagraph) the enhancement of penetration was from about 20% up to 77%. In blood sedimentation study the regular or irregular oscillations or jumps of the RBC/plasma boundary were observed. The one- minute time period of regular oscillations well correlates with the kinetics of the aggregation process, described by the two subsequent stages of formation of the linear and 3-D aggregates.
Application of diffusing wave spectroscopy for in-vitro blood testing and skin microcirculation measurements
Alexander N. Korolevich, Natali S. Dubina, Sergei I. Vecherinski, et al.
The extension of the photon correlation spectroscopy in multiple scattering regimes, so-called diffusing wave spectroscopy (DWS) employed to the study of blood samples. Multiple scattered light from a Helium-Neon (He-Ne) laser beam incident on the blood samples was detected by a photomultiplier, and both the temporal autocorrelation intensity functions g2((tau) ) and power spectra S((omega) ) were measured spectrumaanalyzer. The potential of using diffusing wave spectroscopy (DWS) for the qualitative and quantitative determining of the structural characteristics of the blood elements was studied experimentally. The experimental studies made permit stating to use DWS for the blood cells monitoring in a multiple scattering regime. This paper describes our initial attempts at applying DWS to the study of the blood samples of both healthy donors and patients with cardiac ischemia in vivo and in vitro. The subsequent experiments provide a verification of DWS of blood cells shape monitoring under multiple scattering. The second kind of the experimental application of DWS was the skin microcirculation study in vivo. The results of the mean resting capillary red blood cells (RBC) velocity for two patients with cardiovascular diseases are presented. Two maximums in the mean RBC velocity in time dependence of the He-Ne laser exposure are observed in all measurements.
Sampling volume produced by shallow optical probes in skin reflectance measurements
The absolute quantified measurement of hemoglobin skin blood saturation from collected reflectance spectra of the skin is complicated by the fact that the blood content of tissues can vary both in the spatial distribution and in the amount. These measurements require an understanding of which vascular bed is primarily responsible for the detected signal. Knowing the spatial detector depth sensitivity makes it possible to find the best range of different probe geometries for the measurements of signal from the required zones and group of vessels inside the skin. To facilitate this we have developed a Monte Carlo simulation to estimate the sampling volume offered by fiber-optic probes with a small source detector spacing, and by the confocal probe. The optical properties of the modeled medium were taken to be optical properties of the Caucasian type of skin tissues in the visible range of the spectrum. The authors propose this simple numerical methods as a tool for the probes examination to yield measurements which are preferentially sensitive to blood at different depths within the skin.
Effect of tissue absorption on statistical properties of biospeckles
Zhi Zhang, Qingming Luo, Shaoqun Zeng, et al.
Effects of tissue absorption on statistical properties of biospeckles are studied. The probability density function of intensity and the spatiotemporal cross-correlation function considering light absorption are derived. It is shown theoretically and experimentally that as valves of absorption coefficients increase, the probability density of low light intensity increases and that of high light intensity decreases, which means that dark spots increase and bright spots decrease in bio-speckle pattern. However, the second-order statistics properties of bio-speckles don't' change with the increase of tissue absorption.
Laser Doppler technique for investigation of blood microcirculation in tooth pulp and mucous membranes of an oral cavity
Alexey V. Sedykh, Natalia A. Kharish, Anatoliy Karpovitch, et al.
The results of statistical analysis of intensity fluctuations of scattered light, obtained from tissues of oral cavity membrane of healthy volunteers, are presented. The dependence of the spectral moments of Doppler signal on cutoff frequency is investigated. Some physiological tests in combination with LDF technique are suggested as a new diagnostic tool. In addition, the results of statistical analysis of Doppler spectra, obtained from tooth pulp of patients are presented.
Microvascular resistance in essential hypertension and flowmetry as a diagnostic method
Valdimir F. Lukjanov
New Doppler-Laser flowmetry diagnostic test of functional condition of microcirculation was worked out of find precapillar and postcapillar resistance. Flowmetry was used to measure vasomotion and blood flow after arterial compression, decompression and venous hyperemia were held. Patients of essential hypertension were examined with the help of Doppler-Laser Flowmetry, optical photometry (540 nm). Precapillar resistance included next basis parameters: vasomotion with high frequency (10-16 per/min) and low amplitude, latent time after decompression, large postocclusive reactive hyperemia, absent venous hyperemia. Postcapillar resistance included next basis parameters: vasomotion with low frequency (4-8 per/min) and high amplitude, paradoxical hyperemia in arterial compression, little or absent postocclusive reactive hyperemia, large venous hyperemia. This test-method was applied to select patogenetic treatment of essential hypertension.
Dynamic light scattering: a quantitative approach to determination of the fraction of Doppler-shifted photons
We suggest a method for quantitative determination of the total fraction of Doppler-shifted photons in light scattered by an object containing both moving and static scatterers. The method is based on two approaches: time-varying speckle and laser Doppler were we consider the speckle fluctuations as the primary phenomenon with the Doppler effect being the main cause of these fluctuations. A validation of the method and one of its practical applications is demonstrated. The total fraction of Doppler-shifted photons in light backscattered from human skin has been measured in vivo.
Speckle diagnostics and biomicroscopy of lymph flow in microvessels
Ekateryna I. Galanzha, Anastasiya V. Solov'eva, Sergey S. Ulyanov, et al.
In the present study speckle-interferometry and TV intravital biomicroscopy techniques has been proposed for the analysis of microcirculatory parameters. The power spectra of fluctuation of intensity, scattered by these vessels, have a complicated shape. The mean value of first spectral movement M1 (which is assumed to be directly proportional to average velocity) in lymphatics with spontaneous contractions differ from vessels without phasic activity. We register two types of histogram of M1 in contracting and non-contracting vessels. The phasic contractions may be caused by the modification of lymph flow in microvessels and/or by the changes of the speckle signal values. An application of lymphotropic drugs (staphylococcal toxin, N-nitro-L-arginine and dimethyl sufoxide) on the lymph microvessels has been investigated. The study of lymph flow by two methods (intravital TV biomicroscopy and speckle-interferometry) allows to determine the ways of the action of vasoactive drugs on lymph flow.
Blood flow assessment in capillaries of human eye conjunctiva using laser Doppler technique
Ivan V. Fedosov, Vladimir A. Galanzha, Valery V. Tuchin
The method of blood flow assessment narrow blood capillaries located on the frontal surface of human eye had been developed. In vivo experiments that were performed to investigate a quasiellastic light scattering from the blood capillaries located on scattering surface are described. The obtained results illustrate the influence of multiple scattering on Doppler frequency shift power spectrum forming. The developed method might be serves as a base of noninvasive diagnostics of ophthalmic and cardiovascular diseases.
Investigation of blood microcirculation in paradentium by cross-correlation speckle methods
Leopold A. Googe, Sergey S. Ulyanov, Nina G. Lebedeva
New method of monitoring of blood microcirculation in orthodontics is suggested. Influence of own noise of measuring system on formation of speckle-interferometric signal is studied.