Assessment of serological tests for antibodies to different antigens of the SARS-CoV-2 virus: comparison of six immunoassays

The new coronavirus SARS-CoV-2 has become a global challenge to medicine and, in particular, laboratory diagnostics. The study of the antibodies’ level to SARS-CoV-2 can be used as a confirmation test in the diagnosis of a disease, but it becomes of paramount importance in assessing population immunity resulting from a disease or vaccination, as well as in selection of convalescent plasma donors. The kits developed in our country and abroad for detecting antibodies to the SARS-CoV-2 virus differ both in the methods of testing and in the used coronavirus antigens to which the antibodies are directed. The aim of this study was to compare the diagnostic sensitivity and specificity of five kits for the detection of IgG antibodies to the SARS-CoV-2 virus, based on different diagnostic methods. Serum samples from 137 COVID-19 convalescents and 166 donors of blood and its components were examined. The control group consisted of 50 blood sera collected at the beginning of 2019 and 19 sera collected in 2018 (before the advent of the SARS-CoV-2 virus) and stored at -70 °C. Testing was carried out in analytical systems: rapid test “COVID-19 IgM/IgG Rapid Test (Colloidal Gold)” (China), on an automatic immunochemical analyzer Abbott Architect™ i2000 and kit “SARS-CoV2-IgG” (Abbot, Chicago , IL USA), by the chemiluminescence method using an automatic analyzer of the CL series and kits of the “Mindray” company (China) “SARS-CoV-2 IgM” and “SARS-CoV-2 IgG” and by the enzyme immunoassay method on the kits of the companies “Diagnostic Systems” Ltd (Russia, Nizhny Novgorod) “DS-IFA-ANTI-SARS-CoV-2-G”, “Xema” Ltd (Federal State Budgetary Institution “National Medical Research Center of Hematology” of the Ministry of Health of Russia) “SARS-CoV-2-IgG-IFA” and “Vector-Best” CJSC (Russia, Novosibirsk)” SARS-COV-2-IgM-IFA-BEST” and “SARS-COV-2-IgG-IFABEST”. When comparing the results of testing 137 plasma samples on the Vector-Best and Mindray kits for IgG antibodies, 127 samples were positive, 7 samples were negative on both kits, the discrepancy was 2.2%. In the study of IgM antibodies, 32.1% were positive, and 52.6% were negative in both kits. The discrepancy rate was 15.3%. Out of 166 samples, 1 serum (0.6%) was negative in 5 kits. On the Mindray kit, IgG antibodies to the antigens of the SARS-CoV-2 virus were detected in 165 samples (99.4%), on Vector-Best – in 164 sera (98.8%), on Diagnostic systems – in 151 (90.96%), on Xema – in 154 (92.8%), and on Abbott – in 155 samples (93.4%). At the same time, 135 (81.33%) samples were positive in all kits, while 30 samples had discordant results (18.07%), and in 9 sera, specific IgG was not detected in 2 or more kits. ROC analysis revealed a high diagnostic value of all tested kits (AUC from 0.908 to 0.998), which indicates a high quality of the separation model of positive and negative samples (p < 0.001). With the cut-off set by the manufacturers, the sensitivity and specificity ranged from 82.8% and 93.3% for the Diagnostic Systems kit to 99.4% and 95.8% for the VectorBest kit. The calculated correlation coefficients were higher between kits with a similar composition of the antigen used in the kits; therefore, it is better to monitor the dynamics of antibodies by diagnostic kits from the same manufacturer

ЗАКОНОМЕРНОСТИ ФОРМИРОВАНИЯ ДВИГАТЕЛЬНОГО СТЕРЕОТИПА УПРАВЛЕНИЯ ТЕЛОМ В ФАЗЕ ПОЛЕТА У СПОРТСМЕНОВ

Materials and methods. Regularities of movement patterns in the body control the flight phase of the athletes on the example of the long jump were studied by methods of Motion Tracking and electromyography. The findings suggest that a significant difference of motor stereotypes underlying the performance of motor actions – the long jump – in different skill athletes.Results. In the initial phase (phase jumping) differences between the groups are small - repulsion athletes perform in a similar manner, a core group of athletes with a more efficient use of the reserve of the work of the knee. The nature of the work the leg muscles in athletes of both groups in this phase is also not different. However, the further execution of motor actions in athletes of both groups occurs in different ways. Athletes of the control group did not perform virtually control the body in flight phase. This is evidenced primarily high tone muscles in the arms, back and neck throughout the flight phase. Movements are performed only in the knee and hip joints, and already in the phase of “hang-up” – the highest point of the flight path - these movements have focused on the preparation for landing.Conclusions. Athletes of the main group in the flight phase involve the full range of movements - flexion and extension are performed as in the shoulder and elbow joints, as well as in the neck and spine joints. All these movements are designed to increase the range of jumps - this contributes to the removal of the legs forward, and giving the body angular acceleration by the movement of legs and head. Preparation for landing is made directly before contact with the surface, but the very nature of the phase of flight allows the athlete to use the inertia of motion of the body as much as possible to lengthen the jump and thus facilitate shock absorption and retention of balance upon landing.Formation movement patterns in the body control the flight phase of the athletes in the performance of the long jump is caused first of all a transformation of the dominant, defining the objective of motor actions - from a safe landing at the beginning to a maximum distance of the jump from qualified athletes. The result is a motor stereotype that includes only foot traffic at beginners, is complemented by the involvement of the movements of hands and body, reducing the degree of fixation of joints in high-skilled athletes. Цель исследования: изучить закономерности формирования двигательного стереотипа управления телом в фазе полета у спортсменов на примере выполнения прыжка в длину.Материал и методы. Было обследовано 30 мужчин в возрасте 17–24 лет. По степени сформированности двигательного навыка они были разделены на две группы. В основную группу вошли легкоатлеты высокой квалификации – мастера спорта и кандидаты в мастера спорта (16 человек). Контрольную группу составили студенты (14 человек), не имеющие спортивных разрядов. Использовались методы отслеживания движения Motion Tracking и электромиографии.Результаты. В начальную фазу (фаза выпрыгивания) различия между группами незначительны. Отталкивание спортсмены выполняли сходным образом, спортсмены основной группы при этом более эффективно использовали резерв работы коленных суставов. Характер работы мышц ног у спортсменов обоих групп в этой фазе также не различался. Однако дальнейшее выполнение двигательного действия у спортсменов основной и контрольной групп происходило по-разному.Спортсмены контрольной группы практически не осуществляли управления телом в фазе полета. Об этом свидетельствует прежде высокий тонус мышц рук, спины и шеи на протяжении всей фазы полета. Движения выполнялись только в коленном и тазобедренном суставах, причем уже в фазе «зависания» – высшей точке траектории полета – эти движения направлены на подготовку к приземлению. Спортсмены основной группы в фазе полета задействовали весь спектр возможных движений. Сгибания и разгибания выполнялись в плечевых и локтевых суставах, а также в суставах шеи и позвоночника. Все эти движения направлены на увеличение дальности прыжка, этому способствует и вынос ног вперед, и придание телу углового ускорения за счет движения голеней и головы. Подготовка к приземлению производилась непосредственно перед контактом с поверхностью, однако сам характер фазы полета позволял спортсмену максимально использовать инерцию движения тела для удлинения прыжка, тем самым облегчая амортизацию удара, и удержания равновесия после приземления.Формирование двигательного стереотипа управления телом в фазе полета у спортсменов при выполнении прыжка в длину обусловливается прежде всего трансформацией доминанты, определяющей цель двигательного действия – с безопасного приземления у начинающих на максимальную дальность прыжка у квалифицированных спортсменов. В результате формирующийся двигательный стереотип, включающий только движения ног у начинающих спортсменов, дополняется вовлечением движений рук и корпуса, снижением степени фиксации в суставах у спортсменов высокой квалификации.Заключение. Полученные данные свидетельствуют о существенном различии двигательных стереотипов, лежащих в основе выполнения двигательного действия – прыжка в длину – у спортсменов различной квалификации.

Differential Diagnosis of Congenital Pneumonia in Newborns with Low and Extremely Low Body Weight (Morphological Study)

The purpose of the study is a comprehensive assessment of morphological changes in the placenta and lungs to detect early signs of congenital pneumonia in extremely premature infants.Materials and methods. Protocols of post-mortem examinations of 23 preterm newborns died from severe respiratory failure were analyzed. The average gestational age of the newborns was 26.4±2.7 weeks and the body weight at birth was 972.4±355.8 grams. In the sample, 78.3% of infants had an extremely low birth weight (ELBW). At birth, all newborns presented severe asphyxia. Newborn underwent several types of respiratory therapy since birth: Mechanical ventilation was performed in 65.2% of newborns since their birth, non-invasive ventilation was performed in 26.1% of cases, and 8.7% of patients underwent oxygenotherapy through a facial mask. In all cases, there was an unfavorable course of the neonatal period, a progressive deterioration of newborns' condition, and a lethal outcome. A comprehensive histological examination of the placenta and the lungs of deceased premature newborn infants was performed.Results. Congenital infections of different localizations remain the leading cause of death.Congenital pneumonia and generalized infections are clinically manifested at birth by severe perinatal hypoxia and respiratory failure. In the case of congenital pneumonia, the morphological patterns are polymorphic and characterize the severity of lung damage. For some newborns, these patterns include accumulation of exudates and fibrin, segmented leukocytes, fragments of basophilic coccal microflora, and a large number of colony forming bacilli, and desquamated alveolocytes with a deformed nucleus are visualized in the deformed lumen of the alveoli and bronchi. Diffuse lymphoid-leukocyte infiltration in the septa and respiratory parts of the lungs are typical for other infants. Histological examination find lumpy or lamellar eosinophilic hyaline membranes in alveoli in specimens from these newborns. Diffuse, focal or confluent segmentonuclear infiltration in various lung structures is commonly combined with hyaline membranes of various localizations and sizes. Hyaline membranes were detected in 93.5% of cases.Conclusion. Very early preterm delivery is associated with intrauterine pneumonia and systemic infection in extremely premature infants. Early clinical and laboratory signs of intrauterine infectious lung include severe perinatal hypoxia, very low Apgar score and laboratory test findings (hypoxaemia and decompensated metabolic lactate acidosis) that are resistant to standard resuscitation measures. Hypoxemia and decompensated metabolic acidosis persisting during the first hours of postnatal life indicate the severity of intrauterine lung damage and require a rapid change of treatment aimed at normalization of lung function, prevention of complications in the respiratory system, hemostasis and central nervous system. Clinicians should be better informed about the features of early postnatal adaptation of extremely premature infants with congenital pneumonia to provide appropriate treatment

LAWS OF FORMATION MOVEMENT PATTERNS MANAGEMENT BODY IN PHASE OF FLIGHT IN ATHLETES

Materials and methods. Regularities of movement patterns in the body control the flight phase of the athletes on the example of the long jump were studied by methods of Motion Tracking and electromyography. The findings suggest that a significant difference of motor stereotypes underlying the performance of motor actions – the long jump – in different skill athletes.Results. In the initial phase (phase jumping) differences between the groups are small - repulsion athletes perform in a similar manner, a core group of athletes with a more efficient use of the reserve of the work of the knee. The nature of the work the leg muscles in athletes of both groups in this phase is also not different. However, the further execution of motor actions in athletes of both groups occurs in different ways. Athletes of the control group did not perform virtually control the body in flight phase. This is evidenced primarily high tone muscles in the arms, back and neck throughout the flight phase. Movements are performed only in the knee and hip joints, and already in the phase of “hang-up” – the highest point of the flight path - these movements have focused on the preparation for landing.Conclusions. Athletes of the main group in the flight phase involve the full range of movements - flexion and extension are performed as in the shoulder and elbow joints, as well as in the neck and spine joints. All these movements are designed to increase the range of jumps - this contributes to the removal of the legs forward, and giving the body angular acceleration by the movement of legs and head. Preparation for landing is made directly before contact with the surface, but the very nature of the phase of flight allows the athlete to use the inertia of motion of the body as much as possible to lengthen the jump and thus facilitate shock absorption and retention of balance upon landing.Formation movement patterns in the body control the flight phase of the athletes in the performance of the long jump is caused first of all a transformation of the dominant, defining the objective of motor actions - from a safe landing at the beginning to a maximum distance of the jump from qualified athletes. The result is a motor stereotype that includes only foot traffic at beginners, is complemented by the involvement of the movements of hands and body, reducing the degree of fixation of joints in high-skilled athletes

A European map of groundwater pH and calcium

Water resources and associated ecosystems are becoming highly endangered due to ongoing global environmental changes. Spatial ecological modelling is a promising toolbox for understanding the past, present and future distribution and diversity patterns in groundwater-dependent ecosystems, such as fens, springs, streams, reed beds or wet grasslands. Still, the lack of detailed water chemistry maps prevents the use of reasonable models to be applied on continental and global scales. Being major determinants of biological composition and diversity of groundwater-dependent ecosystems, groundwater pH and calcium are of utmost importance. Here we developed an up-to-date European map of groundwater pH and Ca, based on 7577 measurements of near-surface groundwater pH and calcium distributed across Europe. In comparison to the existing European groundwater maps, we included several times more sites, especially in the regions rich in spring and fen habitats, and filled the apparent gaps in eastern and southeastern Europe. We used random forest models and regression kriging to create continuous maps of water pH and calcium at the continental scale, which is freely available also as a raster map (Hájek et al., 2020b;). Lithology had a higher importance than climate for both pH and calcium. The previously recognised latitudinal and altitudinal gradients were rediscovered with much refined regional patterns, as associated with bedrock variation. For ecological models of distribution and diversity of many terrestrial ecosystems, our new map based on field groundwater measurements is more suitable than maps of soil pH, which mirror not only bedrock chemistry but also vegetation-dependent soil processes

Benchmarking plant diversity of Palaearctic grasslands and other open habitats

Abstract Aims: Understanding fine-grain diversity patterns across large spatial extents is fundamental for macroecological research and biodiversity conservation. Using the GrassPlot database, we provide benchmarks of fine-grain richness values of Palaearctic open habitats for vascular plants, bryophytes, lichens and complete vegetation (i.e., the sum of the former three groups). Location: Palaearctic biogeographic realm. Methods: We used 126,524 plots of eight standard grain sizes from the GrassPlot database: 0.0001, 0.001, 0.01, 0.1, 1, 10, 100 and 1,000 m² and calculated the mean richness and standard deviations, as well as maximum, minimum, median, and first and third quartiles for each combination of grain size, taxonomic group, biome, region, vegetation type and phytosociological class. Results: Patterns of plant diversity in vegetation types and biomes differ across grain sizes and taxonomic groups. Overall, secondary (mostly semi-natural) grasslands and natural grasslands are the richest vegetation type. The open-access file ”GrassPlot Diversity Benchmarks” and the web tool “GrassPlot Diversity Explorer” are now available online (https://edgg.org/databases/GrasslandDiversityExplorer) and provide more insights into species richness patterns in the Palaearctic open habitats. Conclusions: The GrassPlot Diversity Benchmarks provide high-quality data on species richness in open habitat types across the Palaearctic. These benchmark data can be used in vegetation ecology, macroecology, biodiversity conservation and data quality checking. While the amount of data in the underlying GrassPlot database and their spatial coverage are smaller than in other extensive vegetation-plot databases, species recordings in GrassPlot are on average more complete, making it a valuable complementary data source in macroecology