Quantitative evaluation of SARS-CoV-2 inactivation using a deep ultraviolet light-emitting diode

Inactivation technology for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is certainly a critical measure to mitigate the spread of coronavirus disease 2019 (COVID-19). A deep ultraviolet light-emitting diode (DUV-LED) would be a promising candidate to inactivate SARS-CoV-2, based on the well-known antiviral effects of DUV on microorganisms and viruses. However, due to variations in the inactivation effects across different viruses, quantitative evaluations of the inactivation profile of SARS-CoV-2 by DUV-LED irradiation need to be performed. In the present study, we quantify the irradiation dose of DUV-LED necessary to inactivate SARS-CoV-2. For this purpose, we determined the culture media suitable for the irradiation of SARS-CoV-2 and optimized the irradiation apparatus using commercially available DUV-LEDs that operate at a center wavelength of 265, 280, or 300 nm. Under these conditions, we successfully analyzed the relationship between SARS-CoV-2 infectivity and the irradiation dose of the DUV-LEDs at each wavelength without irrelevant biological effects. In conclusion, total doses of 1.8 mJ/cm2 for 265 nm, 3.0 mJ/cm2 for 280 nm, and 23 mJ/cm2 for 300 nm are required to inactivate 99.9% of SARS-CoV-2. Our results provide quantitative antiviral effects of DUV irradiation on SARS-CoV-2, serving as basic knowledge of inactivation technologies against SARS-CoV-2

Design and lyophilization of lipid nanoparticles for mRNA vaccine and its robust immune response in mice and nonhuman primates

mRNA and lipid nanoparticles have emerged as powerful systems for the preparation of vaccines against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection. The emergence of novel variants or the necessity of cold chain logistics for approved mRNA vaccines undermines the investigation of next-generation systems that could preserve both potency and stability. However, the correlation between lipid nanoparticle composition and activity is not fully explored. Here, we screened a panel of ionizable lipids in vivo and identified lead lipid nanoparticles with a branched-tail lipid structure. Buffer optimization allowed the determination of lyophilization conditions, where lipid nanoparticle-encapsulated mRNA encoding SARS-CoV-2 spike protein could induce robust immunogenicity in mice after 1 month of storage at 5°C and 25°C. Intramuscularly injected lipid nanoparticles distributed in conventional dendritic cells in mouse lymph nodes induced balanced T helper (Th) 1/Th2 responses against SARS-CoV-2 spike protein. In nonhuman primates, two doses of 10 or 100 μg of mRNA induced higher spike-specific binding geometric mean titers than those from a panel of SARS-CoV-2-convalescent human sera. Immunized sera broadly inhibited the viral entry receptor angiotensin-converting enzyme 2 (ACE2) from binding to the spike protein in all six strains tested, including variants of concern. These results could provide useful information for designing next-generation mRNA vaccines

Very Low Nucleation Rates of Glucose Isomerase Crystals under Microgravity in the International Space Station

In situ observation of the nucleation and growth of glucose isomerase (GI) crystals under microgravity was conducted using an optical microscope during the first flight of the Advanced Nano Step project undertaken in the International Space Station (ISS). Very low apparent nucleation rates (J’) of GI crystals in the solution and on the substrate of the growth container were confirmed compared with those on the ground. In particular, J’ of GI crystals in the solution were a few times lower than that on the substrate. The growth rates (R) of the {101} faces of GI crystals on the substrate and the apparent growth rates (R’) in the solution were measured. The very low nucleation rates allowed us to successfully measure R at a very high supersaturation region (up to ln(C/Ce) = 6), at which R cannot be measured on the ground

Highly Stretchable Stress-Strain Sensor from Elastomer Nanocomposites with Movable Cross-links and Ketjenblack

Practical applications like very thin stress-strain sensors require high strength, stretchability, and conductivity, simultaneously. One of the approaches is improving the toughness of the stress-strain sensing materials. Polymeric materials with movable cross-links in which the polymer chain penetrates the cavity of cyclodextrin (CD) demonstrate enhanced strength and stretchability, simultaneously. We designed two approaches that utilize elastomer nanocomposites with movable cross-links and carbon filler (ketjenblack, KB). One approach is mixing SC (a single movable cross-network material), a linear polymer (poly(ethyl acrylate), PEA), and KB to obtain their composite. The electrical resistance increases proportionally with tensile strain, leading to the application of this composite as a stress- strain sensor. The responses of this material are stable for over 100 loading and unloading cycles. The other approach is a composite made with KB and a movable cross-network elastomer for knitting dissimilar polymers (KP), where movable cross-links connect the CD-modified polystyrene (PSCD) and PEA. The obtained composite acts as a highly sensitive stress-strain sensor that exhibits an exponential increase in resistance with increasing tensile strain due to the polymer dethreading from the CD rings. The designed preparations of highly repeatable or highly responsive stress-strain sensors with good mechanical properties can help broaden their application in electrical devices

Post-transplant donor-specific anti-HLA antibodies with a higher mean fluorescence intensity are associated with graft fibrosis in pediatric living donor liver transplantation

The roles of post-transplant anti-HLA donor specific antibody (DSA) in pediatric liver transplantation (LT), including therapeutic strategies, remain controversial. This study aimed to identify the risks of post-transplant DSA for graft fibrosis progression in pediatric living donor LT (LDLT). We retrospectively evaluated 88 LDLT pediatric cases between December 1995 and November 2019. DSAs were assessed with single antigen bead test. Graft fibrosis was histopathologically scored with METAVIR and the centrilobular sinusoidal fibrosis system. Post-transplant DSAs were detected in 37 (52.9%) cases at 10.8 (1.3–26.9) years post-LDLT. The histopathological examination of 32 pediatric cases with post-transplant DSA revealed that 7 (21.9%) with a high DSA-MFI (≥9,378) showed graft fibrosis progression (≥F2). No graft fibrosis was observed in the subjects with a low DSA-MFI. The risk factors for developing graft fibrosis in pediatric cases with post-transplant DSA were an older graft age (>46.5 years old), lower platelet count (<10.7 × 104/ml) and higher Fib4 index (>0.7807, recipient age; >1.8952, donor age). Limited efficacy of additional immunosuppressants was observed in DSA positive pediatric cases. In conclusion, pediatric cases with a high DSA-MFI and risk factors should undergo a histological examination. The appropriate treatment for post-transplant DSA in pediatric LT needs to be determined

Outcome of Modified Laparoscopic Sacrocolpopexy and Its Effect on Voiding Dysfunction

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