Methods of Studying Ultraweak Photon Emission from Biological Objects: I. History,Types and Properties,Fundamental and Application Significance

Biophysics - This review is devoted to the methods for studying the ultraweak luminescence of biological objects; in addition to modern methods aimed at studies in the visible, near-infrared, and...     

Photoaction upon adipose tissue cells in vitro

The effect of a change in the optical properties of human adipose tissue cells in vitro after photodynamic action was studied experimentally. The study of kinetics of this process was carried out based on the digital microscopy of thin layers of tissue. The statistical computer processing of the obtained microimages has allowed one to quantitatively estimate the kinetics of the photodynamic after effects on the biotissue. The optical interpretation of images indicates that the observed phenomenon corresponds to the partial lysis of the adipose tissue cells without their complete destruction.     

Phenomenon of music-induced opening of the blood-brain barrier in healthy mice

Music plays a more important role in our life than just being an entertainment. For example, it can be used as an anti-anxiety therapy of human and animals. However, the unsafe listening of loud music triggers hearing loss in millions of young people and professional musicians (rock, jazz and symphony orchestra) owing to exposure to damaging sound levels using personal audio devices or at noisy entertainment venues including nightclubs, discotheques, bars and concerts. Therefore, it is important to understand how loud music affects us. In this pioneering study on healthy mice, we discover that loud rock music below the safety threshold causes opening of the blood-brain barrier (OBBB), which plays a vital role in protecting the brain from viruses, bacteria and toxins. We clearly demonstrate that listening to loud music during 2 h in an intermittent adaptive regime is accompanied by delayed (1 h after music exposure) and short-lasting to (during 1–4 h) OBBB to low and high molecular weight compounds without cochlear and brain impairments. We present the systemic and molecular mechanisms responsible for music-induced OBBB. Finally, a revision of our traditional knowledge about the BBB nature and the novel strategies in optimizing of sound-mediated methods for brain drug delivery are discussed.     

A robust ex vivo method to evaluate the diffusion properties of agents in biological tissues

A robust method is presented for evaluating the diffusion properties of chemicals in ex vivo biological tissues. Using this method that relies only on thickness and collimated transmittance measurements, the diffusion properties of glycerol, fructose, polypropylene glycol and water in muscle tissues were evaluated. Amongst other results, the diffusion coefficient of glycerol in colorectal muscle was estimated with a value of 3.3 × 10^?7 cm²/s. Due to the robustness and simplicity of the method, it can be used in other fields of biomedical engineering, namely in organ cryoprotection and food industry.      

Glucose and mannitol diffusion in human dura mater

An in vitro experimental study of the control of the human dura mater optical properties at administration of aqueous solutions of glucose and mannitol has been presented. The significant increase of the dura mater optical transmittance under action of immersion liquids has been demonstrated. Diffusion coefficients of glucose and mannitol in the human dura mater tissue at 20 degrees C have been estimated as (1.63 +/- 0.29) x 10(-6)cm(2)/s and as (1.31 +/- 0.41) x 10(-6) cm(2)/s, respectively. Experiments show that administration of immersion liquids allows for the effective control of tissue optical characteristics that make dura mater more transparent, thereby increasing the ability of light penetration through the tissue.     

Functional organization of lymphatic microvessels of the rat mesentery]

Lymph flow as measured with biomicroscopic and speckle-interferometrical techniques was very unstable and its rate did not depend on lymphangion diameter in the rat mesentery. A correlation was found between amount of cells in the lymph flow and other indices of lymphangion functions. All microvessels with phasic contractions and/or working valve were revealed as having a lymph flow. The phasic activity and the valve work correlated with each other. The higher the amplitude and frequency of the phasic activity and the longer the contraction cycle, the higher was the rate of the valve work.     

Controlling the near‐infrared transparency of costal cartilage by impregnation with clearing agents and magnetite nanoparticles

Penetration depth of near‐infrared laser radiation to costal cartilage is controlled by the tissue absorption and scattering, and it is the critical parameter to provide the relaxation of mechanical stress throughout the whole thickness of cartilage implant. To enhance the penetration for the laser radiation on 1.56 μm, the optical clearing solutions of glycerol and fructose of various concentrations are tested. The effective and reversible tissue clearance was achieved. However, the increasing absorption of radiation should be concerned: 5°C‐8°C increase of tissue temperature was detected. Laser parameters used for stress relaxation in cartilage should be optimized when applying optical clearing agents. To concentrate the absorption in the superficial tissue layers, magnetite nanoparticle (NP) dispersions with the mean size 95 ± 5 nm and concentration 3.9 ± 1.1 × 10¹¹ particles/mL are applied. The significant increase in the tissue heating rate was observed along with the decrease in its transparency. Using NPs the respective laser power can be decreased, allowing us to obtain the working temperature locally with reduced thermal effect on the surrounding tissue.      

A comparative study of ex vivo skin optical clearing using two‐photon microscopy

Multiphoton tomography (MPT) is a prospective tool for imaging the skin structure. Aiming to increase the probing depth, a comparative ex vivo study of optical clearing of porcine ear skin was performed by using two optical clearing agents (OCAs), i.e., glycerol and iohexol (Omnipaque^TM) at different concentrations, which exhibit different osmotic properties. The results show that a topical application of glycerol or Omnipaque^TM solutions onto the skin for 60 min significantly improved the depth and contrast of the MPT signals. By utilizing 40%, 60% and 100% glycerol, and 60% and 100% Omnipaque^TM it was demonstrated that both agents improve autofluorescence and SHG (second harmonic generation) signals from the skin. At the applied concentrations and agent time exposure, glycerol is more effective than Omnipaque^TM. However, tissue shrinkage and cell morphology changes were found for highly concentrated glycerol solutions. Omnipaque^TM, on the contrary, increases the safety and has no or minimal tissue shrinkage during the optical clearing process. Moreover Omnipaque^TM allows for robust multimodal optical/X‐ray imaging with automatically matched optically cleared and X‐ray contrasted tissue volumes. These findings make Omnipaque^TM more prospective than glycerol for some particular application.

     

Molecular modeling of immersion optical clearing of biological tissues

The interaction of six low-molecular tissue-clearing agents (1,2 and 1,3-propanediol, ethylene glycol, glycerol, xylitol, sorbitol) with the collagen mimetic peptide (GPH)₃ was studied by applying the methods of classical molecular dynamics (GROMACS), molecular docking (AutoDock Vina) and quantum chemistry (PM6 and B3LYP). The spatial configurations of intermolecular complexes were determined and interaction energies calculated. The dependence of the volume occupied by the collagen peptide on the clearing agent concentration in an aqueous solution was calculated. This dependence is not linear, and has a maximum for almost all the agents in the study. The correlations between the optical clearing potential and intermolecular interactions parameters, such as the time of an agent being in a hydrogen-bonded state, and the relative probability of formation of double hydrogen bonds and interaction energies, were determined. Using the correlations determined, we predicted the numeric value of the optical clearing potential of dextrose molecules in rat skin, which correlates with experimental data. A molecular mechanism of tissue optical clearing within the post-diffusion stage is suggested.

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Graphical abstract The molecular modeling of the interaction between clearing agents and collagen