ВЛИЯНИЕ НАНОЧАСТИЦ ЗОЛОТА НА АГРЕГАЦИЮ МИТОХОНДРИАЛЬНОЙ АСПАРТАТ-АМИНОТРАНСФЕРАЗЫ

We have studied the dependence of aggregation of mitochondrial aspartate aminotransferase (mAspAT) from the concentration of gold nanoparticles (AuNP). It has been shown that AuNPs decreased the aggregation of mAspAT in the temperature range from 55 to 73 °C. The maximal anti-aggregational effect of AuNP reached 56 % and was observed at 60 °C. Increase of AuNP concentration led to a decrease of the constant rate of enzyme aggregation. We suggest here that interaction between Au-NPs and mAspAT increases conformational stability of the enzyme molecule. It also reduces the probability of polypeptide chain unfolding, which causes exposure of hydrophobic patches on the protein surface resulting in intra molecular adhesion followed by the protein aggregation.Исследована зависимость агрегации митохондриальной аспартат-аминотрансферазы (мАспАТ) от концентрации наночастиц золота (НЧЗ). Установлено, что в температурном диапазоне от 55 до 73 °С НЧЗ снижают агрегацию мАспАТ. Наиболее выраженный антиагрегационный эффект НЧЗ достигает 56 % и проявляется при 60 °С. Увеличение концентрации НЧЗ приводит к снижению константы скорости агрегации фермента. Высказывается предположение, что формирование связей между НЧЗ и мАспАТ будет приводить к повышению конформационной жесткости молекулы фермента, снижать вероятность анфолдинга и экспонирования на поверхности молекулы гидрофобных фрагментов, обеспечивающих межмолекулярное «слипание» и последующую агрегацию белка

Влияние элементного состава и температуры осаждения покрытий Ti-AL-C-N на их морфологию и жизнеспособность клеток на таких покрытиях

Nanostructural Ti-Al-C-N coatings were produced by reactive magnetron sputtering at substrate temperatures of 220, 340 and 440 °C using mosaic targets with different Al/Ti ratios. Using atomic-force and scanning electron microscopy, it was found that the variation of the elemental composition leads to a change in the morphology of Ti-Al-C-N coatings: at an Al/Ti ratio of 0.39, the films have a mixed columnar-granular structure with no visible defects and a low roughness (3.30–5.86 nm); at an Al/Ti ratio of ~ 0.96, the films show a porous columnar structure with a higher roughness (8.83–11.07 nm) and for an Al/Ti ratio of ~ 1.71, the films have a fine-grained structure and the smallest roughness values (0.48–1.74 nm). Substrate heating from 220 to 440 °C did not significantly affect the elemental composition of Ti-Al-C-N films, but it affected the deposition rate, surface roughness, and the microstructure of the coatings. MTT-test results showed no relationship between the fibroblasts viability, the coating roughness and the coating elemental composition. However, the cells viability and their ability to proliferate on the Ti-Al-C-N coatings surface were preserved.Наноструктурные покрытия Ti-Al-C-N формировались методом реактивного магнетронного осаждения из мозаичных мишеней с различным соотношением Al/Ti при температурах подложки 220, 340 и 440 °C. Методами атомно-силовой и растровой электронной микроскопии обнаружено, что варьирование элементного состава приводит к изменению морфологии покрытий Ti-Al-C-N: при соотношении Al/Ti ~ 0,39 пленки имеют столбчато-зернистую структуру без видимых дефектов и низкую шероховатость Sq  (3,30–5,86 нм); при Al/Ti ~ 0,96 пленки показали столбчатую пористую структуру и более высокую шероховатость Sq (8,83–11,07 нм); при Al/Ti ~ 1,71 имели мелкозернистую структуру и наименьшие значения шероховатости Sq  (0,48–1,74 нм). Нагрев подложки от 220 до 440 °C не оказывал значительного влияния на элементный состав Ti-Al-C-N пленок, однако воздействовал на скорость осаждения, шероховатость поверхности и микроструктуру покрытий. По результатам МТТ-теста прямой зависимости между жизнеспособностью фибробластов, шероховатостью покрытий и их элементным составом не обнаружено, однако жизнеспособность клеток и их способность к пролиферации при контакте с поверхностью покрытий Ti-Al-C-N сохранялась

Evaluation of cell-based and surrogate SARS-CoV-2 neutralization assays

Determinants of protective immunity against SARS-CoV-2 infection require the development of well-standardized, reproducible antibody assays. This need has led to the emergence of a variety of neutralization assays. Head-to-head evaluation of different SARS-CoV-2 neutralization platforms could facilitate comparisons across studies and laboratories. Five neutralization assays were compared using forty plasma samples from convalescent individuals with mild-to-moderate COVID-19: four cell-based systems using either live recombinant SARS-CoV-2 or pseudotyped viral particles created with lentivirus (LV) or vesicular stomatitis virus (VSV) packaging and one surrogate ELISA-based test that measures inhibition of the spike protein receptor binding domain (RBD) binding its receptor, human angiotensin converting enzyme 2 (hACE2). Vero, Vero E6, HEK293T expressing hACE2, and TZM-bl cells expressing hACE2 and transmembrane serine protease 2 were tested. All cell-based assays showed 50% neutralizing dilution (ND50) geometric mean titers (GMTs) that were highly correlated (Pearson r = 0.81–0.89) and ranged within 3.4-fold. The live-virus assay and LV-pseudovirus assays with HEK293T/hACE2 cells showed very similar mean titers: 141 and 178, respectively. ND50 titers positively correlated with plasma IgG targeting SARS-CoV-2 spike and RBD (r = 0.63–0.89), but moderately correlated with nucleoprotein IgG (r = 0.46–0.73). ND80 GMTs mirrored ND50 data and showed similar correlation between assays and with IgG concentrations. The VSV-pseudovirus assay and LV-pseudovirus assay with HEK293T/hACE2 cells in low and high-throughput versions were calibrated against the WHO SARS-CoV-2 IgG standard. High concordance between the outcomes of cell-based assays with live and pseudotyped virions enables valid cross-study comparison using these platforms. 24

THE STUDY OF REGULARITIES OF INDUCTION OF IL-8 SYNTHESIS BY NEUTROPHIL DEFENSINS IN VITRO

Abstract. We explored the effects of defensins on IL-8 synthesis in various human cells, including bronchoepithelial cell line A-549, monocytes, monocyte-derived macrophages differentiated in the presence of M-CSF, HU-VEC cells, HEK293 and THP-1 cell lines. HNP at 10-5-10-4М induced IL-8 production and cytotoxicity in serum-less A-549 culture. The addition of serum abrogated the cytotoxicity along with the induction of IL-8 synthesis. Similar effects were observed in HEK293 cell line and HUVEC.The induction of cytotoxicity along with IL-8 production by HNP at 10-5-10-4М was also observed in the serum-less cultures of human monocytes and macrophages. However, monocytes and macrophages retained HNP-induced production of IL-8 after the addition of serum, while cytotoxic effect of HNP was completely inhibited. The data imply a specific interaction of alpha-defensins with some membrane receptors of monocytes and macrophages that leads to the induction of IL-8 and might also occur in vivo.</p