Effects of Various Physical and Chemical Disinfection Methods on the Fine Particle Collection Efficiency of N95 Respirators and Surgical Masks.

Several studies have reported on the effectiveness of various disinfection methods for severe acute respiratory syndrome coronavirus 2 and their applicability to the disinfection of N95 respirators and surgical masks. To date, there have been no reports on the decontamination of deep in the intermediate layers of the multilayered structure. In this study, the conditions required for decontamination of such layers were simulated by considering the thickness and shape of N95 respirators or surgical masks (samples). After applying heat (steam, dry heat, or hot water) at 75°C for 60 min or chemical (benzalkonium chloride or laundry detergent) treatment, the collection efficiency of the samples was evaluated. Following the dry heat treatment, the time between the treatment and heat reaching the intermediate layer of the filter fiber was extended by 10 min. A dry heat disinfection method that combines hot water and a closed container was also evaluated, and satisfactory conditions were extended by 60 min. For each heat treatment, there was almost no effect on the collection efficiency, although there were cases where deformation was caused by mechanical stress. In contrast, chemical treatment resulted in a reduction in the collection efficiency of smaller particles.

Kinetic properties and substrate inhibition of α-galactosidase from Aspergillus niger.

The recombinant AglB produced by Pichia pastoris exhibited substrate inhibition behavior for the hydrolysis of p-nitrophenyl α-galactoside, whereas it hydrolyzed the natural substrates, including galactomanno-oligosaccharides and raffinose family oligosaccharides, according to the Michaelian kinetics. These contrasting kinetic behaviors can be attributed to the difference in the dissociation constant of second substrate from the enzyme and/or to the ability of the leaving group of the substrates. The enzyme displays the grater kcat/Km values for hydrolysis of the branched α-galactoside in galactomanno-oligosaccharides than that of raffinose and stachyose. A sequence comparison suggested that AglB had a shallow active-site pocket, and it can allow to hydrolyze the branched α-galactosides, but not linear raffinose family oligosaccharides.

Qualitative analysis of the perception and acceptability of pathogen transport among housewives using focus group interviews.

We conducted focus group interviews to understand how residents of Japan feel about the transport of pathogens. Twelve randomly selected housewives, who had no special knowledge regarding the topic before the interview, expressed their opinions in 2 separate meetings regarding pathogen transport. The results of the interviews were analyzed by the KJ method. The analysis found that although the transport of pathogens is universally recognized to be necessary, there is not clear consensus on the exact methods of transport, the positive and/or negative value of such information, and how clearly and/or uniquely to label containers, packages, compartments, vehicles, and conditions used for such transportation. Further studies to improve the skills of both the providers and receivers of such information (a technique of risk communication) are necessary.

Cytokine regulation in SARS coronavirus infection compared to other respiratory virus infections.

The pathogenesis of severe acute respiratory syndrome (SARS) is poorly understood and cytokine dysregulation has been suggested as one relevant mechanism to be explored. We compared the cytokine profile in Caco2 cells after infection of SARS coronavirus (SARS-CoV) with other respiratory viruses including respiratory syncytial virus (RSV), influenza A virus (FluAV), and human parainfluenza virus type 2 (hPIV2). Interferon (IFN) system (production and response) was not suppressed by SARS-CoV infection. Therefore, SARS-CoV replication was suppressed by pretreatment with IFN. SARS-CoV and RSV induced high levels of IL-6 and RANTES compared with FluAV and hPIV2. Induction level of suppressor of cytokine signaling-3 (SOCS3) by SARS-CoV was significantly lower than that by RSV in spite of the significant production of IL-6. Toll-like receptors 4 and 9, which correlate with the induction of inflammatory response, were upregulated by SARS-CoV infection. Collectively, overinduction of inflammatory cytokine and dysregulation of cytokine signaling may contribute to the immunopathology associated with "severe" inflammation in SARS.

Serum-dependent expression of promyelocytic leukemia protein suppresses propagation of influenza virus.

The rate of propagation of influenza virus in human adenocarcinoma Caco-2 cells was found to negatively correlate with the concentration of fetal bovine serum (FBS) in the culture medium. Virus replicated more rapidly at lower FBS concentrations (0 or 2%) than at higher concentrations (10 or 20%) during an early stage of infection. Basal and interferon (IFN)-induced levels of typical IFN-inducible anti-viral proteins, such as 2',5'-oligoadenylate synthetase, dsRNA-activated protein kinase and MxA, were unaffected by variation in FBS concentrations. But promyelocytic leukemia protein (PML) was expressed in a serum-dependent manner. In particular, the 65 to 70 kDa isoform of PML was markedly upregulated following the addition of serum. In contrast, other isoforms were induced by IFN treatment, and weakly induced by FBS concentrations. Immunofluorescence microscopy indicated that PML was mainly formed nuclear bodies in Caco-2 cells at various FBS concentrations, and the levels of the PML-nuclear bodies were upregulated by FBS. Overexpression of PML isoform consisting of 560 or 633 amino acid residues by transfection of expression plasmid results in significantly delayed viral replication rate in Caco-2 cells. On the other hand, downregulation of PML expression by RNAi enhanced viral replication. These results indicate that PML isoforms which are expressed in a serum-dependent manner suppress the propagation of influenza virus at an early stage of infection.