Polyubiquitination is an essential posttranslational modification that plays critical roles in cellular signaling. PolyUb (polyubiquitin) chains are formed by linking the carboxyl-terminus of one Ub (ubiquitin) subunit to either a lysine residue or the amino-terminus of an adjacent Ub. Linkage through the amino-terminus results in linear polyubiquitination that has recently been demonstrated to be a key step in nuclear factor κB activation; however, tools to study linear chains have been lacking. We therefore engineered a linear-linkage-specific antibody that is functional in Western blot, immunoprecipitation, and immunofluorescence applications. A crystal structure of the linear-linkage-specific antibody Fab fragment in complex with linear diubiquitin provides molecular insight into the nature of linear chain specificity. We use the antibody to demonstrate that linear polyUb is up-regulated upon tumor necrosis factor α stimulation of cells, consistent with a critical role in nuclear factor κB signaling. This antibody provides an essential tool for further investigation of the function of linear chains.
BackgroundTo investigate the clinical characteristics and treatment outcomes in necrotizing fasciitis (NF) patients in a reconstructive unit in northeastern China.MethodsMedical records of patients diagnosed with and treated for NF in the extremities from November 2013 to December 2016 were retrospectively reviewed. Demographic data, clinical presentation, duration of signs and symptoms, location of infection, predisposing factors, causative microbiological organisms, laboratory risk indicator for necrotizing fasciitis (LRINEC) score, number of surgical debridements, length of hospital stay, treatments, and outcomes were recorded.ResultsA total of 39 consecutive patients were treated for severe NF (32 male and 7 female). Diabetes mellitus and blunt trauma were the most common risk factors (13 and 9 cases, respectively). The positive predictive value of the LRINEC score in NF diagnosis was 46.2%. Mean duration of signs and symptoms was 4.6 days. Staphylococcus aureus was the most commonly isolated bacteria (20 cases). All patients underwent their first debridement within 12 h of presentation (mean, 4.6 h). Mean number of surgical treatments was 2.8 (range, 2–5) per patient, including debridements. All patients survived, and mean length of hospital stay was 30.81 (range, 21–43) days. Three patients underwent limb amputation.ConclusionsIn our clinical experience, early detection and aggressive debridement are the cornerstones of NF treatment. Antibiotic therapy and intensive care support is essential in severe cases of NF. Anaerobic tissue culture and frozen section biopsy could be adopted as routine tests for diagnosis and decision-making in NF. These findings should inform clinical decisions about the treatment of individual patients with NF.
Wild and domestic aquatic birds are the natural reservoirs of avian influenza viruses (AIVs). All subtypes of AIVs, including 16 hemagglutinin (HA) and nine neuraminidase (NA), have been isolated from the waterfowls. The H5 viruses in wild birds display distinct biological differences from their highly pathogenic H5 counterparts. Here, we isolated seven H5N3 AIVs including three from wild birds and four from domestic ducks in China from 2015 to 2018. The isolation sites of all the seven viruses were located in the region of the East Asian‐Australasian Migratory Flyway. Phylogenetic analysis indicated that the surface genes of these viruses originated from the wild bird H5 HA subtype and the N3 Eurasian lineage. The internal genes of the seven H5N3 isolates are derived from the five gene donors isolated from the wild birds or ducks in Eastern‐Asia region. They were also divided into five genotypes according to their surface genes and internal gene combinations. Interestingly, two of the seven H5N3 viruses contributed their partial internal gene segments (PB1, M and NS) to the newly emerged H7N4 reassortants, which have caused first human H7N4 infection in China in 2018. Moreover, we found that the H5N3 virus used in this study react with the anti‐serum of the H5 subtype vaccine isolate (Re‐11 and Re‐12) and reacted well with the Re‐12 anti‐serum. Our findings suggest that worldwide intensive surveillance and the H5 vaccination (Re‐11 and Re‐12) in domestic ducks are needed to monitor the emergence of novel H5N3 reassortants in wild birds and domestic ducks and to prevent H5N3 viruses transmission from the apparently healthy wild birds and domestic ducks to chickens.
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