Continuous Modeling of Arterial Platelet Thrombus Formation Using a Spatial Adsorption Equation

In this study, we considered a continuous model of platelet thrombus growth in an arteriole. A special model describing the adhesion of platelets in terms of their concentration was derived. The applications of the derived model are not restricted to only describing arterial platelet thrombus formation; the model can also be applied to other similar adhesion processes. The model reproduces an auto-wave solution in the one-dimensional case; in the two-dimensional case, in which the surrounding flow is taken into account, the typical torch- like thrombus is reproduced. The thrombus shape and the growth velocity are determined by the model parameters. We demonstrate that the model captures the main properties of the thrombus growth behavior and provides us a better understanding of which mechanisms are important in the mechanical nature of the arterial thrombus growth

Сорбенты для экстракорпорального удаления токсических веществ и молекул с нежелательной биологической активностью (обзор)

The review devoted to sorbents and sorbentbased medical devices used in clinical practice for extracorporeal detoxification using a hemoperfusion technique. Clinical data have confirmed the effectiveness of this approach for removal of bacterial endotoxins, lowdensity lipoproteins, and bilirubin. Other studies demonstrated successful application of sorbents to treat autoimmune diseases. Special attention is paid to hemoperfusion in as a possible treatment for severe sepsis and septic shock. The review justifies importance of development and application of novel multimodal sorbents, which combine both properties of selective and nonselective sorbents. The review discusses clinical efficacy of hemoperfusion and key molecular interactions between the sorbent and circulating molecules pathogenetically relevant to developing critical illness and severe diseases. The reference list: 137.В обзоре рассмотрены сорбенты и медицинские изделия на их основе, применяемые в клинической практике для экстракорпоральной детоксикации с помощью процедуры гемосорбции. Представлены данные исследователей, свидетельствующие об эффективности такого подхода с целью удаления бактериальных эндотоксинов, липопротеинов низкой плотности, билирубина, а также при лечении аутоиммунных заболеваний. Основное внимание уделено применению гемосорбции при лечении тяжелого сепсиса и септического шока. Обосновывается необходимость разработки и применения новых «мультимодальных» сорбентов, сочетающих свойства как «селективных», так и «неселективных» сорбентов. В обзоре приведены сведения о клинической эффективности гемосорбции и молекулярном взаимодействии сорбента с циркулирующими молекулами, патогенетически значимыми для развития критических состояний и тяжелых заболеваний. Библиография — 137 ссылок

Numerical analysis of the stress-strain state of osteotomies of the first metatarsal bone

Deviation of the first toe to the outside, interconnected with the deviation of the first metatarsal bone to the inside, occurs in 46% of patients of the older age group and is called valgus deformity of the first toe. The negative impact of this pathology on the quality of life of patients is the reason for seeking medical help, the gold standard of which is surgical correction, and the basic surgical technique is osteotomy (sawing the bone and fixing its fragments with implants) of the first metatarsal. At the same time, an ideal osteotomy should provide initial stability in the early postoperative period. However, a large number of ways to perform osteotomy, as well as the advantages and disadvantages of each of the surgical techniques, do not allow to consider one of them as the most successful. In this regard, the aim of the work was to develop and validate a biomechanical model of osteotomy of the first metatarsal bone to analyze its stability and reliability depending on the type of osteotomy, the degree of displacement of bone fragments, as well as the number of fastening screws. In this study, biomechanical modeling of the most commonly used variants of osteotomy of the first metatarsal bone of the foot in the surgical treatment of its valgus deformity was carried out. For this purpose, 10 models of osteotomies of a separate first metatarsal bone were created, which were then subjected to static loading to analyze their stress-strain state and assess their success. Successful (stable and reliable) treatment options were identified, as well as unsuccessful ones. Two of the ten options considered were unsuccessful – scarf type osteotomies with displacement of bone fragments by 2/3 of its diameter and fixed with a single screw. It was revealed that osteotomies of the chevron type showed higher stability in comparison with scarf osteotomies. As a result, we note that in this study, numerical experiments were conducted for the first time to compare the stability and strength of the most commonly used variants of osteotomies based on a single bone model. A biomechanical model of scarf osteotomy of the first metatarsal bone has been developed and validated on the basis of mechanical experiments

Very high frequency gravitational wave background in the universe

Astrophysical sources of high frequency gravitational radiation are considered in association with a new interest to very sensitive HFGW receivers required for the laboratory GW Hertz experiment. A special attention is paid to the phenomenon of primordial black holes evaporation. They act like black body to all kinds of radiation, including gravitons, and, therefore, emit an equilibrium spectrum of gravitons during its evaporation. Limit on the density of high frequency gravitons in the Universe is obtained, and possibilities of their detection are briefly discussed.Comment: 14 page

Методы определения бактериального эндотоксина в медицине критических состояний (обзор)

Dedicated to reviewing the methods for detecting bacterial endotoxin in aqueous solutions and biological fluids, this review is focused on determining the content of endotoxin as a clinically relevant biomarker of sepsis caused by Gram-negative bacteria. The advantages and disadvantages of each method are described, and the characteristics of test systems currently used in clinical practice are listed and compared.В обзоре рассмотрены методы определения бактериальных эндотоксинов в водных растворах и биологических жидкостях. Основное внимание уделено определению содержания эндотоксинов как клинически значимых биомаркеров сепсиса, вызванного грамотрицательными бактериями. Обсуждены достоинства и недостатки каждого метода и приведены сравнительные характеристики используемых в настоящее время в клинической практике тест-систем

EXPERIMENTAL STUDY OF THE PROTECTIVE PROPERTIES OF POLYMER COMPOSITES WITH POZZOLAN AGAINST GAMMA RADIATION

The article summarizes the results of an experimental study of polymer composite materials as radiation protection against gamma radiation, the filler of which is a mixture of volcanic ash, tuff and pumice