The in vivo quantitative assessment of the effectiveness of low-dose photodynamic therapy on wound healing using optical coherence tomography

The effect of low-dose photodynamic therapy on in vivo wound healing was investigated using optical coherence tomography. This work aims to develop an approach to quantitative assessment of the wound’s state during wound healing including the effect of low-dose photodynamic therapy using topical application of two different photosensitizers, 5-aminolevulinic acid and methylene blue, and two laser doses of 1 J/cm2 and 4 J/cm2. It was concluded that the laser dose of 4 J/cm2 was better compared to 1 J/cm2 and allowed the wound healing process to accelerate

In vivo quantification of the effectiveness of topical low-dose photodynamic therapy in wound healing using two-photon microscopy

The effect of low-dose photodynamic therapy on in vivo wound healing with topical application of 5-aminolevulinic acid and methylene blue was investigated using an animal model for two laser radiation doses (1 and 4 J/cm2). A second-harmonic-generation-to-auto-fluorescence aging index of the dermis (SAAID) was analyzed by two-photon microscopy. SAAID measured at 60–80 μm depths was shown to be a suitable quantitative parameter to monitor wound healing. A comparison of SAAID in healthy and wound tissues during phototherapy showed that both light doses were effective for wound healing; however, healing was better at a dose of 4 J/cm2

The mechanisms of the antimicrobial function of the mucus layer. Current research gaps

The mucus layer is secreted by epithelial cells. Its antimicrobial function is to prevent the pathogens from entering the epithelial cells. Modern concepts of evolution, composition, structure and protective functions of the mucus layer related to the physical and chemical characteristics of glycoproteins, and the peculiarities of their synthesis and degradation are discussed. Hypotheses about the poorly studied participants in the antimicrobial functions of the mucus layer: the possible virucidal and bactericidal role of circulating enzymes of the digestive tract and anions in the composition of polymerized and degraded glycoproteins are presented. Further research on the physiological mechanisms of the barrier function of the mucus layer may provide a rationale for new means of limiting epidemics of viral and bacterial nature

Comparative study of the biological efficacy of titanium dioxide nano- and microparticles

Chronic experiments with male Wistar rats were carried out to investigate the delayed effects of oral administration of titanium dioxide nanoand microparticles on the integral indices of the body condition and level of the oxidative stress. It was found that the studied titanium dioxide (TiO2) particles produced different effects on the indicated characteristics: on the 7th day after the experiment, the animal bodyweight decreased in both experimental groups as compared to control; weight factors in the brain and testicles of the rats fed with TiO2 microparticles increased with respect to control group and to the group of rats fed with TiO2 nanoparticles; the oxidative stress developed in the group of rats fed with TiO2 microparticles because the level of oxidized products increased in the brain (cerebellum) and antioxidant ability of the tissue decreased in the liver. In the group of rats fed with TiO2 nanoparticles, no changes in the level of oxidized products and antioxidant ability in the body tissues were found in comparison with control group on the 7th day after the experiment. Thus, in the study of biological effects of TiO2 nanoparticles, an additional control with investigation of TiO2 macro-or microparticles is necessary, because TiO2 microparticles were shown to have the biological efficacy.</jats:p

Analysis of collagen spatial structure using multiphoton microscopy and machine learning methods

Pathogenesis of many diseases is associated with changes in the collagen spatial structure. Traditionally, the 3D structure of collagen in biological tissues is analyzed using histochemistry, immunohistochemistry, magnetic resonance imaging, and Xradiography. At present, multiphoton microscopy (MPM) is commonly used to study the structure of bio logical tissues. MPM has a high spatial resolution comparable to histological analysis and can be used for direct visualiza tion of collagen spatial structure. Because of a large volume of data accumulated due to the high spatial resolution of MPM, special analytical methods should be used for identification of informative features in the images and quantitative evalua tion of relationship between these features and pathological processes resulting in the destruction of collagen structure. Here, we describe current approaches and achievements in the identification of informative features in the MPM images of collagen in biological tissues, as well as the development on this basis of algorithms for computeraided classification of col lagen structures using machine learning as a type of artificial intelligence methods

Quantitative Assessment of Low-Dose Photodynamic Therapy Effects on Diabetic Wound Healing Using Raman Spectroscopy

One of challenges that faces diabetes is the wound healing process. The delayed diabetic wound healing is caused by a complicated molecular mechanism involving numerous physiological variables. Low-dose photodynamic therapy (LDPDT) provides excellent results in rejuvenation and wound healing. In this study, the LDPDT effect on diabetic wounds in mice was studied using two photosensitizers, 5-aminolevulinic acid and methylene blue, and two laser dose expositions of 1 J/cm2 and 4 J/cm2 by Raman spectroscopy (RS). The latter was used as a noninvasive method, providing specific information about tissue state based on the fundamental vibrational modes of its molecular components. RS allows high spatial resolution acquisition of biochemical and structural information through the generation of point spectra or spectral images. An approach to in vivo quantitative assessment of diabetic wound healing state was developed. This approach is based on an application of the principal component analysis combined with the Mahalanobis metrics to skin Raman spectra, in particular, intensities of the amide I and CH2 bands

An evaluation of lymphedema using optical coherence tomography: A rat limb model approach

Lymphedema is a pathology caused by poor lymphatic flow which may lead to complete disability. Currently, precise, non-invasive techniques for quantifying lymphedema are lacking. In this paper, the results of an in vivo assessment of lymphedema via a developed small-animal model using the hindlimbs of rats and an optical coherence tomography (OCT) technique are presented. This model of lymphedema was based on a surgical lymph node resection and subsequent two-step X-ray exposure. The development of lymphedema was verified via the histological examination of tissue biopsies. The properties of the lymphedematous skin were analyzed in vivo and compared with healthy skin via OCT. The main differences observed were (1) a thickening of the stratum corneum layer, (2) a thinning of the viable epidermis layer, and (3) higher signal attenuation in the dermis layer of the lymphedematous skin. Based on the distribution of the OCT signal’s intensity in the skin, a machine learning algorithm was developed which allowed for a classification of normal and lymphedematous tissue sites with an accuracy of 90%. The obtained results pave the way for in vivo control over the development of lymphedema

Use of terahertz spectroscopy for in vivo studies of lymphedema development dynamics

A laboratory model of lymphedema development induced by lymphatic vessel resection in rat extremities is presented. In vivo analysis of lymphedema development (monitoring for 4 weeks) employed reflective terahertz spectroscopy with a Dove prism. The incidence angle for an s-polarized electromagnetic wave directed to the boundary of the prism and the biological tissue was close to the Brewster’s angle. Significant changes in the spectral characteristics of the tissue in the animals’ extremities were detected on days 21– 28 of lymphedema development. A predictive model for disease diagnostics based on monitoring the changes of the tissue absorbance curve in the 0.4–1.1 THz range was constructed. Principal component analysis and support vector machines were used in the model