A novel dynamic multicellular co-culture system for studying individual blood-brain barrier cell types in brain diseases and cytotoxicity testing

Blood brain barrier (BBB) cells play key roles in the physiology and pathology of the central nervous system (CNS). BBB dysfunction is implicated in many neurodegenerative diseases, including Alzheimer’s disease (AD). The BBB consists of capillary endothelial cells, pericytes encircling the endothelium and surrounding astrocytes extending their processes towards it. Although there have been many attempts to develop in vitro BBB models, the complex interaction between these celltypes makes it extremely difficult to determine their individual contribution to neurotoxicity in vivo. Thus, we developed and optimised an in vitro multicellular co-culture model within the Kirkstall Quasi Vivo System. The main aim was to determine the optimal environment to culture human brain primary endothelial cells, pericytes and astrocytes whilst maintaining cellular communication without formation of a barrier in order to assess the contribution of each cell type to the overall response. As a proof of concept for the present system, the effects of amyloid-beta 25-35 peptide (Aβ25-35), a hall mark of AD, were explored. This multicellular system will be a valuable tool for future studies on the specific roles of individual BBB cell type (while making connection with each other through medium) in CNS disorders as well as in cytotoxicity tests

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

Purification of the silica-containing residue after nitric acid leaching of serpentinite

Физико-химическими способами был определен химический, минеральный состав серпентинита Баженовского месторождения и кремнеземистого остатка, полученного при азотнокислотном выщелачивании сырья. Определен химический и минеральный состав кремнезема и магнитной фракции, выделенных при магнитной сепарации кремнеземистого остатка. Проведено повторное кислотное выщелачивание кремнезема и определен химический состав твердого продукта.The chemical and mineral composition of serpentinite from Bazhenovsky deposit, siliceous residue obtained by nitric acid leaching of raw materials was determined using physicochemical methods. The chemical and mineral composition of silica and magnetic fractions obtained by magnetic separation of silica residue was determined. A repeated acid leaching of silica was carried out and chemical composition of the solid product was defined

INTEGRATION OF SCIENTIFIC AND EDUCATIONAL UNIVERSITY WORK: EXPERIENCE OF COMPARATIVE ANALYSIS OF THE THERMAL DECOMPOSITION OF Mg(NO3)2 · 6H2O IN AIR AND SUPERHEATED WATER VAPOR

Abstract. The aim of the investigation is to select how the thermal decomposition of crystallohydrate magnesium nitrates to capture the nitrogen compounds that are harmful to the environment; for the return of nitric acid to the initial stage of the process. Methods. The methods involve physical and chemical analysis (IR spectroscopy, rentgennofazovy analysis), thermolysis and thermal hydrolysis of magnesium nitrate. Results. Magnitudes of thermal effects are determined; mechanisms of thermal decomposition of magnesium nitrate in air and overheated water vapor are posed. Thermohydrolysis renders possible to produce undiluted magnesium oxide and regenerate nitric acid. Scientific novelty. Undiluted magnesium oxide was produced by the method that requires less energy consumption. Practical significance. The research results on regeneration of nitric acid and its reuse in the raw material processing containing magnesium open new prospects for production and can be applied as course materials for a practical training in organic chemistry in postgraduate study on chemical specialties