Stability of SARS-CoV-2 on Commercial Aircraft Interior Surfaces with Implications for Effective Control Measures.

BACKGROUND: The COVID-19 pandemic from 2019 to 2022 devastated many aspects of life and the economy, with the commercial aviation industry being no exception. One of the major concerns during the pandemic was the degree to which the internal aircraft environment contributed to virus transmission between humans and, in particular, the stability of SARS-CoV-2 on contact surfaces in the aircraft cabin interior. METHOD: In this study, the stability of various major strains of SARS-CoV-2 on interior aircraft surfaces was evaluated using the TCID50 assessment. RESULTS: In contrast to terrestrial materials, SARS-CoV-2 was naturally less stable on common contact points in the aircraft interior, and, over a 4 h time period, there was a 90% reduction in culturable virus. Antiviral and surface coatings were extremely effective at mitigating the persistence of the virus on surfaces; however, their benefit was diminished by regular cleaning and were ineffective after 56 days of regular use and cleaning. Finally, successive strains of SARS-CoV-2 have not evolved to be more resilient to survival on aircraft surfaces. CONCLUSIONS: We conclude that the mitigation strategies for SARS-CoV-2 on interior aircraft surfaces are more than sufficient, and epidemiological evidence over the past three years has not found that surface spread is a major route of transmission.

Cellular tropism of SARS-CoV-2 in the respiratory tract of Syrian hamsters and B6.Cg-Tg(K18-ACE2)2Prlmn/J transgenic mice.

Several animal models have been developed to study the pathophysiology of SARS-CoV-2 infection and to evaluate vaccines and therapeutic agents for this emerging disease. Similar to infection with SARS-CoV-1, infection of Syrian hamsters with SARS-CoV-2 results in moderate respiratory disease involving the airways and lung parenchyma but does not lead to increased mortality. Using a combination of immunohistochemistry and transmission electron microscopy, we showed that the epithelium of the conducting airways of hamsters was the primary target for viral infection within the first 5 days of infection, with little evidence of productive infection of pneumocytes. At 6 days postinfection, antigen was cleared but parenchymal damage persisted, and the major pathological changes resolved by day 14. These findings are similar to those previously reported for hamsters with SARS-CoV-1 infection. In contrast, infection of K18-hACE2 transgenic mice resulted in pneumocyte damage, with viral particles and replication complexes in both type I and type II pneumocytes together with the presence of convoluted or cubic membranes; however, there was no evidence of virus replication in the conducting airways. The Syrian hamster is a useful model for the study of SARS-CoV-2 transmission and vaccination strategies, whereas infection of the K18-hCE2 transgenic mouse results in lethal disease with fatal neuroinvasion but with sparing of conducting airways.

TRPM7 kinase-mediated immunomodulation in macrophage plays a central role in magnesium ion-induced bone regeneration.

Despite the widespread observations on the osteogenic effects of magnesium ion (Mg2+), the diverse roles of Mg2+ during bone healing have not been systematically dissected. Here, we reveal a previously unknown, biphasic mode of action of Mg2+ in bone repair. During the early inflammation phase, Mg2+ contributes to an upregulated expression of transient receptor potential cation channel member 7 (TRPM7), and a TRPM7-dependent influx of Mg2+ in the monocyte-macrophage lineage, resulting in the cleavage and nuclear accumulation of TRPM7-cleaved kinase fragments (M7CKs). This then triggers the phosphorylation of Histone H3 at serine 10, in a TRPM7-dependent manner at the promoters of inflammatory cytokines, leading to the formation of a pro-osteogenic immune microenvironment. In the later remodeling phase, however, the continued exposure of Mg2+ not only lead to the over-activation of NF-κB signaling in macrophages and increased number of osteoclastic-like cells but also decelerates bone maturation through the suppression of hydroxyapatite precipitation. Thus, the negative effects of Mg2+ on osteogenesis can override the initial pro-osteogenic benefits of Mg2+. Taken together, this study establishes a paradigm shift in the understanding of the diverse and multifaceted roles of Mg2+ in bone healing.

Precisely controlled delivery of magnesium ions thru sponge-like monodisperse PLGA/nano-MgO-alginate core-shell microsphere device to enable in-situ bone regeneration.

A range of magnesium ions (Mg2+) used has demonstrated osteogenic tendency in vitro. Hence, we propose to actualize this concept by designing a new system to precisely control the Mg2+ delivery at a particular concentration in vivo in order to effectively stimulate in-situ bone regeneration. To achieve this objective, a monodisperse core-shell microsphere delivery system comprising of poly (lactic-co-glycolic acid) (PLGA) biopolymer, alginate hydrogel, and magnesium oxide nano-particles has been designed by using customized microfluidic capillary device. The PLGA-MgO sponge-like spherical core works as a reservoir of Mg2+ while the alginate shell serves as physical barrier to control the outflow of Mg2+ at ∼50 ppm accurately for 2 weeks via its adjustable surface micro-porous network. With the aid of controlled release of Mg2+, the new core-shell microsphere system can effectively enhance osteoblastic activity in vitro and stimulate in-situ bone regeneration in vivo in terms of total bone volume, bone mineral density (BMD), and trabecular thickness after operation. Interestingly, the Young's moduli of formed bone on the core-shell microsphere group have been restored to ∼96% of that of the surrounding matured bone. These findings indicate that the concept of precisely controlled release of Mg2+ may potentially apply for in-situ bone regeneration clinically.

Biodegradable metallic materials for orthopaedic implantations: A review.

Non-degradable metals such as stainless steel, cobalt-chromium-based alloys, titanium and its alloys may lead to stress shielding effect after fractured bone has healed. This complication may attribute to the non-degradability and the mismatch of the mechanical properties between these metallic implants and human bone. Biodegradable metallic materials have been therefore studied as alternative implantable metals in orthopaedics for some years. Magnesium is a potential candidate, as its mechanical properties are similar to human. Additionally, it is degradable and its ions are essential for cell functions. However, rapid degradation and release of hydrogen gas may inhibit its applications clinically. Hence, this paper reviews the development of the biodegradable metallic implants and various methods to improve the degradation of magnesium alloys.