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Background and Objectives: The compression of human skin is one of the mechanisms of mechanical biotissue optical clearing. In this study we investigated the effects of compression of in vitro cow muscle tissue samples on diffuse reflectance spectra of tissue and changes of its physiological properties. The purpose of research was to identify the correlation between diffuse reflectance of muscle tissue and its compression. Material and Methods: Samples of muscle tissue used in the experiments with a size of 70–50 mm and a thickness of 25 mm were cut from one volume of the loin hart of a cow. After applying pressure to the sample for a time of about 20 minutes, reflectance spectra of the samples were recorded with a time step of 5 seconds. In the experiments, sensors of different sizes were varied with different values of the applied external compression. Results: The dynamics of myoglobin and hemoglobin content in muscle tissue ex vivo in the compression process was determined. In the case of muscle tissue ex vivo, the blood content in it decreases when compression is applied. A similar effect was observed for skin tissue in vivo, but there are also significant differences: if for skin tissue capillary blood, and hemoglobin, when a pressure of about 105 Pa is applied, is completely removed from biological tissue, then myoglobin from muscle tissue samples is not completely removed, the oxygenated form of myoglobin turns into deoxygenated and deoxygenation of myoglobin occurs within a few minutes after the application of compression. Conclusion: In perspective compression of muscle tissue ex vivo can become the basis for a method for controlling the content of hemoglobin and myoglobin derivatives and, as a result, for controlling the color of biological tissue.

Background. Currently, there are a number of unsolved fundamental scientific problems related to obtaining reliable information when monitoring the treatment of various diseases. The problem of diagnostic medical equipment using optical research methods is particularly relevant. This implies the purpose of the study: to determine the system connections and patterns of interaction between technical systems with complex biological systems (bloodstream) in the process of assessing their condition, and on this basis substantiate the principle of constructing a high-resolution laser pulse oximeter with high accuracy characteristics. Materials and methods. Optical research methods related to the depth of penetration of the optical trace and its adequate perception by the comparison system to obtain reliable signals. Results. The principle of constructing a three-wave two-channel laser pulse oximeter using the third wavelength (λ = 805 ± 0.75 nm) is proposed. The radiation wavelength of 804.25... 805.75 nm is an "isobestic point", at this wavelength the spectral characteristics of hemoglobin and oxyhemoglobin coincide. Conclusions. A three-wave two-channel laser pulse oximeter with improved accuracy characteristics has been proposed, the measurement error of which has been reduced to 5 %, %, compared with other analogues, where the error is up to 30 %.

The purpose of the study — to determine the feasibility of using the succinate-based antioxidant for the in vitro reduction of excessive methemoglobin to oxyhemoglobin in blood.Materials and Methods. Blood sampling was performed in five healthy donors in microvettes containing EDTA during prophylactic examinations. NaNO2 solution was added to blood samples in vitro in order to yield methemoglobin (MetHb). The complex drug containing the following active ingredients: succinic acid, inosine, riboflavin, nicotinamide, was used as an antioxidant. The absorption spectrum of red cell suspensions with different drug content Dι (λι )exper was measured with 1 nm increments. The non-linear regression method was used to calculate concentrations of hemoglobin derivatives in suspensions.Results. In our experiments, when methemoglobin reacted with drug the optical density of peaks typical for oxyhemoglobin increased and the spectral peak of methemoglobin decreased. The greater the concentration of drug, the more was the incubation time, the more efficient was the process of reduction of MetHb to HbO2.Conclusion. We proved experimentally that while the baseline concentration of MetHb was an average of 91—93%, addition of drug decreased its concentration to 25—7%. Without drug, due to autoreduction, the concentration of MetHb decreases only to 84%. The revealed effect provide a potential for practical applications in critical illness, during the storage of donor blood, in blood transfusions, and under the action of physico-chemical factors on blood.

Oxygen content in body fluids and tissues is an important indicator of life support functions. A number of ocular pathologies, e.g. glaucoma, are of presumable vascular origin which means altered blood supply and oxygen circulation. Most oxygen is transported in the blood in the association with hemoglobin. When passing through the capillaries, hemoglobin releases oxygen, converting from oxygenated form to deoxygenated form. This process is accompanied by the changes in spectral characteristics of hemoglobin which result in different colors of arterial and venous blood. Photometric technique for the measurement of oxygen saturation in blood is based on the differences in light absorption by different forms of hemoglobin. The measurement of saturation is called oximetry. Pulse oximetry with assessment of tissue oxygenation is the most commonly used method in medicine. The degree of hemoglobin oxygen saturation in the eye blood vessels is the most accessible for noninvasive studies during ophthalmoscopy and informative. Numerous studies showed the importance of this parameter for the diagnosis of retinopathy of various genesis, metabolic status analysis in hyperglycemia, diagnosis and control of treatment of glaucoma and other diseases involving alterations in eye blood supply. The specific method for evaluation of oxygen concentration is the measurement of pressure of oxygen dissolved in the blood, i.e. partial pressure of oxygen. In ophthalmological practice, this parameter is measured in anterior chamber fluid evaluating oxygen level for several ophthalmopathies including different forms of glaucoma, for instillations of hypotensive eye drops as well as in vitreous body near to the optic disc under various levels of intraocular pressure. Currently, monitoring of oxygen saturation in retinal blood vessels, i.e. retinal oximetry, is well developed. This technique is based on the assessment of light absorption by blood depending on hemoglobin saturation with oxygen by analyzing spectral composition of light diffusively reflected from the retina. Oximetry of bulbar conjunctival and episcleral microvasculature can be also performed allowing for the evaluation of oxygen saturation in vessels which collect blood from the anterior segment and the characterization of anterior segment metabolism in a number of ocular pathologies and in the course of the treatment.

The purpose of this review is to present the most significant modifications and transformations of a hemoglobin molecule potentially related to developing a strategy of resuscitation and treatment of lifethreatening forms of anemia. Hemoglobin is one of the wellstudied proteins. The paper reviews the history of hemoglobin studies from 1839 untill present. Methodically, the hemoglobin studies included electrophoresis, spectrophotometric method, Xray diffraction method, atomicforce microscopy. The basic forms of hemoglobin include oxyhemoglobin, deoxyhemoglobin and methemoglobin. Data on protein crystallization and polymerization are discussed. Many forms of hemoglobin have the ability to form crystals or polymers in vitro, some pathological forms can be modified in vivo. The studies of structural features of various hemoglobin forms represent a contemporary task for fundamental researches.