In present study we have considered diffusion of immersion agent into the skin through thermally pretreated stratum
corneum solving the corresponding diffusion problem. Algorithm of refractive index of interstitial liquid and diffusion
coefficient of immersion agent into biotissue estimations at a creation of lattice-like pattern of localized thermal damage
islets in the stratum corneum, was develop. Theoretical model which sufficiently describes the influence of immersion
agents on skin optical properties was presented. The diffusion coefficient of glycerol into pig skin ex vivo at creating a
lattice of islets of damage in the stratum corneum is 0.84±0.08 μm2/s.
We present experimental results of investigation of the optical properties of the human eye sclera controlled by
administration of osmotically active chemical, such as 40%-glucose solution. Administration of the chemical agent
induces diffusion of matter and as a result equalization of the refractive indices of collagen and ground material. Results
of the experimental study of influence of the glucose solution on the absorption and scattering properties of human sclera
are presented. In vitro reflectance and transmittance spectra of the human sclera samples were measured by
commercially available spectrophotometer CARY-2415 in the spectral range from 400 to 1800 nm. The reduced
scattering coefficient of human sclera samples is significantly decreased under action of the osmotical solution were
demonstrated.
The optical properties of human stomach wall mucosa were measured in the wavelength range 400-2000 nm. The
measurements were carried out using the commercially available spectrophotometer CARY-2415 with an integrating
sphere. The combined method includes inverse adding-doubling method and inverse Monte Carlo method was used to
determine the absorption and scattering coefficients and anisotropy factor from the measurements.
Controlling of optical properties of skin is of great interest for skin diseases monitoring and phototherapy. Glycerol, as the
most effective optical clearing agent, was applied in this study. Effects of osmotic properties of glycerol on optical clearing
of the human skin have been investigated. Two main mechanisms of optical clearing at a creation of lattice-like pattern of
localized thermal damage islets in the SC, glycerol diffusion into damaged skin and tissue dehydration, were discussed.
High level of light scattering in mammalian skin significantly deteriorates the effectiveness and precision of light delivery to intra- and subcutaneous targets in therapeutic and diagnostic applications. Optical immersion based on the refractive index matching of tissue scattering centers with surrounding matter via introduction of an exogenous indexmatching agent is capable to alleviate the problem. But this process goes slowly enough because of sluggish diffusion of various immersion agents through a stratum corneum (SC) barrier, making a practical realization of this approach difficult. In order to increase the rate of the process we designed the method of accelerating the penetration of optical clearing agents (OCAs) by enhancing skin permeability through a creation of lattice-like pattern of localized thermal damage (ablation) islets in the SC. OCAs, such as glucose, propylene glycol, and glycerol solutions, were applied. Experimental results show a remarkable increase in the rate of optical clearing. The most of results were obtained on in vivo human skin.
Strong light scattering in skin prevents precise targeting of optical energy in therapeutic and diagnostic applications. Optical immersion based on matching refractive mdcx of scattering centers with that of surrounding matter through introduction of an exogenous index-matching agent can alleviate the problem. However, slow diffusion of the index-matching agent through skin barrier makes practical implementation of this approach difficult. We propose a method of accelerating penetration of the index-matching compounds by enhancing skin permeability through creating a lattice of micro-zones (islets) of limited thermal damage in the stratum comeum. Two index-matching agents, glucose and glycerol, were tested. Glycerol used as index-matching agent gave noticeably better clearance then 40% glucose solution.
The possibilities of characterization of the relaxation processes in thermally treated collagenous tissues with the use of the cumulant analysis of speckle intensity fluctuations are discussed. This method deals with the correlation analysis of spatial-temporal fluctuations of laser light multiply scattered by thermally modified tissue under the condition of polarization discrimination of detected speckle-modulated optical signals. Experimental results, which were obtained
with ex-vivo cartilage samples, are presented.
Thermally induced irreversible changes in mechanical properties of collagen-containing tissue such as tendon are analyzed in order to characterize the process of thermal denaturation of the collagenous matrix in tissues. Based on a simple phenomenological model of a partially denaturated tissue as a binary system consisting of an amorphous phase (denaturated collagen) and a structurized phase (collagen fibrillar structure), the consideration of the temperature-dependent evolution of the elastic module of a thermally modified tendon tissue is carried out. The activation energy of collagen denaturation is estimated with the use of experimental dependencies of the tendon elastic module on the temperature and heating time, which have been obtained by M.S. Wall et al.
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