Экспериментальное исследование антибактериальной активности литического стафилококкового бактериофага ph20 и литического бактериофага синегнойной палочки ph57 при моделировании их импрегнации в ортопедические полимерные конструкции из полиметилметакрилата (костного цемента)

Background: The problem of bacterial colonization of implants used in medical practice continues to be relevant regardless of the material of the implant. Particular attention deserves polymeric implants, which are prepared ex tempore from polymethyl methacrylate, for example - duting orthopedic surgical interventions (so-called "bone cement"). The protection of such implants by antibiotic impregnation is subjected to multiple criticisms, therefore, as an alternative to antibiotics, lytic bacteriophages with a number of unique advantages can be used - however, no experimental studies have been published on the possibility of impregnating bacteriophages into polymethyl methacrylate and their antibacterial activity assessment under such conditions.Aims: to evaluate the possibility of physical placement of bacteriophages in polymethylmethacrylate and to characterize the lytic antibacterial effect of two different strains of bacteriophages when impregnated into polymer carrier ex tempore during the polymerization process in in vitro model.Materials and methods:  First stage - Atomic force microscopy (AFM) of polymethyl methacrylate samples for medical purposes was used to determine the presence and size of caverns in polymethyl methacrylate after completion of its polymerization at various reaction  temperatures (+6…+25°C and +18…+50°C).The second stage was performed in vitro and included an impregnation of two different bacteriophage strains (phage ph20 active against S. aureus and ph57 active against Ps. aeruginosa) into polymethyl methacrylate during the polymerization process, followed by determination of their antibacterial activity.Results: ACM showed the possibility of bacteriophages placement in the cavities of polymethyl methacrylate - the median of the section and the depth of cavities on the outer surface of the polymer sample polymerized at +18…+50°C were 100.0 and 40.0 nm, respectively, and on the surface of the transverse cleavage of the sample - 120.0 and 100.0 nm, respectively, which statistically did not differ from the geometric dimensions of the caverns of the sample polymerized at a temperature of +6…+25°C.The study of antibacterial activity showed that the ph20 bacteriophage impregnated in polymethyl methacrylate at +6…+25°C lost its effective titer within the first six days after the start of the experiment, while the phage ph57 retained an effective titer for at least 13 days.Conclusion: the study confirmed the possibility of bacteriophages impregnation into medical grade polymethyl methacrylate, maintaining the effective titer of the bacteriophage during phage emission into the external environment, which opens the way for the possible application of this method of bacteriophage delivery in clinical practice. It is also assumed that certain bacteriophages are susceptible to aggressive influences from the chemical components of "bone cement" and / or polymerization reaction products, which requires strict selection of bacteriophage strains that could be suitable for this method of delivery.Обоснование. Проблема бактериальной колонизации используемых в медицинской практике имплантатов из различных материалов продолжает оставаться актуальной, независимо от использованного для их изготовления материала. Отдельного внимания заслуживают имплантируемые в организм человека полимерные имплантаты, которые изготовляют ex tempore (по мере надобности) из полиметилметакрилата, например при ортопедических хирургических вмешательствах (так называемый костный цемент). Защита таких имплантатов путем импрегнации в них антибиотиков подвергается множественной критике, поэтому в качестве альтернативы антибиотикам могут быть использованы литические бактериофаги, обладающие рядом уникальных преимуществ, однако экспериментальных работ по изучению возможности импрегнации бактериофагов в полиметилметакрилат и антибактериальной активности в таких условиях в литературе не опубликовано. Цель исследования ― изучить возможность физического размещения бактериофагов в полиметилметакрилате и в модели in vitro охарактеризовать литический антибактериальный эффект двух различных штаммов бактериофагов при их импрегнации в изготавливаемый ex tempore полимерный носитель на этапе полимеризации. Методы. Первым этапом была проведена атомно-силовая микроскопия (АСМ) образцов полиметилметакрилата медицинского назначения для выяснения наличия и размеров каверн, образовавшихся после завершения полимеризации при различном диапазоне температур реакционной смеси (+6…+25 °C и +18…+50 °C). Вторым этапом in vitro было проведена импрегнация двух различных штаммов бактериофагов (ph20, активного в отношении Staphylococcus aureus, и ph57, активного в отношении Pseudomonas aeruginosa) в полиметилметакрилат на этапе полимеризации с последующим определением их антибактериальной активности. Результаты. В ходе выполнения АСМ установлена возможность размещения бактериофагов в кавернах полиметилметакрилата: медиана сечения и глубины каверн на внешней поверхности образца, полимеризованного при температуре +18…+50 °C, составила 100,0 и 40,0 нм соответственно, а на поверхности поперечного скола образца ― 120,0 и 100,0 нм соответственно, что статистически не отличалось от геометрических размеров каверн образца, полимеризованного при температуре +6…+25 °C. Изучение антибактериальной активности показало, что импрегнированный при +6…+25 °C в полиметилметакрилат стафилококковый бактериофаг ph20 утратил эффективный титр уже в течение первых шести суток с момента начала эксперимента, тогда как синегнойный бактериофаг ph57 сохранял эффективный титр как минимум в течение 13 сут. Заключение. В исследовании была подтверждена возможность импрегнации бактериофагов в полиметилметакрилат медицинского назначения с поддержанием эффективного титра бактериофага при его эмиссии во внешнюю среду, что открывает пути возможного применения такого способа доставки бактериофагов в клинической практике. Также сделаны предположения о вероятной подверженности некоторых бактериофагов агрессивным воздействиям со стороны химических компонентов «костного цемента» и/или продуктов реакции полимеризации, что требует строгого отбора пригодных для подобного способа доставки штаммов бактериофагов

Invasive aspergillosis in patients with COVID-19 in intensive care units: results of a multicenter study

Objective. To study risk factors, clinical and radiological features and effectiveness of the treatment of invasive aspergillosis (IA) in adult patients with COVID-19 (COVID-IA) in intensive care units (ICU). Materials and Methods. A total of 60 patients with COVID-IA treated in ICU (median age 62 years, male – 58%) were included in this multicenter prospective study. The comparison group included 34 patients with COVID-IA outside the ICU (median age 62 years, male – 68%). ECMM/ISHAM 2020 criteria were used for diagnosis of CAPA, and EORTC/MSGERC 2020 criteria were used for evaluation of the treatment efficacy. A case-control study (one patient of the main group per two patients of the control group) was conducted to study risk factors for the development and features of CAPA. The control group included 120 adult COVID-19 patients without IA in the ICU, similar in demographic characteristics and background conditions. The median age of patients in the control group was 63 years, male – 67%. Results. 64% of patients with COVID-IA stayed in the ICU. Risk factors for the COVID-IA development in the ICU: chronic obstructive pulmonary disease (OR = 3.538 [1.104–11.337], p = 0.02), and prolonged (> 10 days) lymphopenia (OR = 8.770 [4.177–18.415], p = 0.00001). The main location of COVID-IA in the ICU was lungs (98%). Typical clinical signs were fever (97%), cough (92%), severe respiratory failure (72%), ARDS (64%) and haemoptysis (23%). Typical CT features were areas of consolidation (97%), hydrothorax (63%), and foci of destruction (53%). The effective methods of laboratory diagnosis of COVID-IA were test for galactomannan in BAL (62%), culture (33%) and microscopy (22%) of BAL. The main causative agents of COVID-IA are A. fumigatus (61%), A. niger (26%) and A. flavus (4%). The overall 12-week survival rate of patients with COVID-IA in the ICU was 42%, negative predictive factors were severe respiratory failure (27.5% vs 81%, p = 0.003), ARDS (14% vs 69%, p = 0.001), mechanical ventilation (25% vs 60%, p = 0.01), and foci of destruction in the lung tissue on CT scan (23% vs 59%, p = 0.01). Conclusions. IA affects predominantly ICU patients with COVID-19 who have concomitant medical conditions, such as diabetes mellitus, hematological malignancies, cancer, and COPD. Risk factors for COVID-IA in ICU patients are prolonged lymphopenia and COPD. The majority of patients with COVID-IA have their lungs affected, but clinical signs of IA are non-specific (fever, cough, progressive respiratory failure). The overall 12-week survival in ICU patients with COVID-IA is low. Prognostic factors of poor outcome in adult ICU patients are severe respiratory failure, ARDS, mechanical ventilation as well as CT signs of lung tissue destruction

Change in the soils’ fertility level of tea agrocenoses in the transition to cultivation without mineral fertilizers in the humid-subtropical zone of Russia

Research was carried out on the basis of preserved field multifactor experiment on tea crop (Camellia sinensis (L.) Kuntze) in the conditions of the Sochi Black Sea coast. The application of NPK fertilizers in different doses and combinations according to the experimental scheme was carried out annually from 1986 to 2011. Since 2012, the use of fertilizers has been completely discontinued. The fertility indicators of long-fertilized brown forest acidic soils (in layers 0-20/20-40 cm) were compared with those after 7-8 years of fertilizer withdrawal. During the period of fertilizers’ application, the level of soils’ nitrogen supply significantly exceeded the control (by 30-75/30-56 mg/kg depending on the doses of nitrogen fertilizers). After the fertilizers’ discontinuity, nitrogen supply level equalization occurred in all experimental options. The content of labile phosphorus in soils previously fertilized with high phosphorus doses (120 kg P2O5 ha-1 year-1 and more), during the period of experiment’s conservation decreased by 450-500/350-450 mg/kg, but exceeded the control in 2-2.5 times; in soils previously fertilized by low doses, the indicators have not changed significantly. In soils highly supplied with labile potassium, the content of the element decreased by 70-140 mg/kg. The yield of tea in 2019-2020 was equally low (12-26 cwt/ha) on all options, 2.2-3 times lower than fertilized plantations. After the fertilizers’ withdrawal, there was a decrease in acidity (an average increase in pH by 0.18-0.24/0.12-0.20 units) of agrogenic-acidized soils and an increase in their oppressed respiratory activity (on average by 1.6 times). These changes reflect the tendency of soil self-restoration after the removal of the fertilizers’ load

Imperative and dispositive norms in legal regulation of genetic research in Russia

© 2020, Universidad del Zulia. All rights reserved. The article is devoted to the analysis of diverse utilization varieties of regulatory framework at adjusting genetic techniques and global legal practice research. Internal determinants of the development of national systems and external universal laws of legal transformation influence the evolution of views of the professional community of lawyers in Russia and in foreign countries, regarding the choice of dispositive or mandatory ways of regulating genetic research. The discussion on a number of legal institutions and on the choice of effective methods and forms of legal regulation in the world and Russian legal practice continues

Quality of life - the factor of Russia success at present and in the future

The quality of life and human development - these concepts are substantial characteristics of contemporary approaches to the challenges of economic growth and development of society. The quality of life in contemporary quality concepts means the integrated characteristics of social-economic, political, cultural-ideologic, ecologic factors and living conditions and social status of a person. State policy in the field of regulating population’s quality of life and living standards is the basis of creating totally new work force, essential needs in material wealth, life quality and working conditions indicators. We consider the definition "quality of life" within the concept of human development to define the system of the factors influencing it. We review the modern approaches to the analysis of the quality of life. Features and aspects of quality of life are considered, its role in social and economic development of the country is analysed. The main criteria define specifics of human development and social wellbeing of the population. To evaluate the quality of life of the population we use the statistical analysis of the United Nations (UN), Human Development Index (HDI).We conclude that the level of life is an integrated social and economic category that presents the level of development of physical, immaterial and social needs which influence the quality of life and population wellbeing Index

Digital Economy and Digital Twins. Main Research Area

The work is devoted to the consideration and research of methods for transforming economic structures that underlie the transition to the dominant digital task of economic processes and their relationship with digital forms of representing economic relations. The main stages of the possible assignment of enterprises and the levels of building digital twins have been determined. Using the example of an object that belongs to the external area of ​​the enterprise – the supplier of the constituent components of the product – it is shown how the transition to the digital form of this object can be built.Мета роботи – запропонувати основні етапи, які визначать перехід від звичайних підприємств до його цифрового подання (цифрового двійника) в умовах переходу до цифрової економіки.Цель работы – предложить основные этапы, которые определят переход от обычных предприятий к их цифровому представлению (цифровому двойнику) в условиях перехода к цифровой экономике

DYNAMICS OF PLASMA PHENOMENA IN "PLASMA FOCUS" UNDER THE ACTION OF POWERFUL LASER RADIATION

No abstract availabl

Оптимизация иммуноферментного метода для определения цилиарного нейротрофического фактора в слезной жидкости человека

The concentration of ciliary neurotrophic factor (CNTF) was measured in lacrimal fluid (LF) using Human CNTF Quantikine ELISA kit (“R&D Systems”, USA) on a ChemWell 2910 automatic analyzer (“Awareness Technology Inc.”, USA). We initially attempted to use commercial kits, designed for serum and plasma CNTF detection, to quantify lacrimal CNTF. The results, however, were rarely above the minimum detection level of the kits, most likely due to matrix complexity and low concentrations of CNTF in diluted LF (LF had to be diluted because of the small volume of collected samples). The optimal sensitivity and the lowest background for the best minimum quantifiable value were determined empirically. Phosphate buffer solution containing 1% bovine serum albumin was selected as an optimal diluent for CNTF measurements in small fluid samples. A standard curve was produced using the calibrating solutions 0-250 pg/ml. Acid treatment of LF samples before the analysis allowed to increase the detectable concentration of the CNTF two-fold. The 1:3 dilution was selected based on the available volume of collected LF and a reasonable variation coefficient. The described protocol allowed to develop a sandwich ELISA optimized for lacrimal CNTF.Определение цилиарного нейротрофического фактора – ciliary neurotrophic factor (CNTF) в слёзной жидкости (СЖ) человека рутинными лабораторными методами затруднено из-за его низкой концентрации в структурах глаза и недостаточного количества материала для анализа. Были подобраны условия для определения CNTF в СЖ твердофазным методом иммуноферментного анализа (ИФА) на основе набора Human CNTF Quantikine ELISA Kit (“R&D Systems”, США) с использованием автоматического иммуноферментного анализатора ChemWell 2910 Combi (“Awareness Technology Inc.”, США). Предварительная кислотная обработка проб СЖ позволила вдвое повысить концентрацию CNTF. Полностью автоматизированная система проведения анализа и выбор разбавителя с низкой оптической плотностью бланка (0.011) обеспечили линейную зависимость калибровочного графика от 0 до 250 пг/мл с возможностью его использования для расчета концентрации CNTF в области низких значений. Рабочие характеристики оптимизированной тест-системы ИФА (линейность метода, предел обнаружения, воспроизводимость, интерференция матрицы) в указанном диапазоне концентраций соответствовали критериям приемлемости для используемого метода определения. Разведение образцов СЖ в четыре раза, совмещённое с кислотной обработкой проб, оказалось оптимальным для получения стабильных результатов при проведении анализа. В этом случае концентрация CNTF в пробе составляла в среднем 10.4±0.4 пг/мл с коэффициентом вариации 4.2% и близостью определяемых значений к ожидаемым величинам на уровне 104%