The von Willebrand factor (VWF) propeptide (domains D1D2) is essential for the assembly of VWF multimers and its tubular storage in Weibel-Palade bodies. However, detailed molecular mechanism underlying this propeptide dependence is unclear. Here, we prepared Weibel-Palade body-like tubules using the N-terminal fragment of VWF and solved the cryo-electron microscopy structures of the tubule at atomic resolution. Detailed structural and biochemical analysis indicate that the propeptide forms a homodimer at acidic pH through the D2:D2 binding interface and then recruits 2 D’D3 domains, forming an intertwined D1D2D’D3 homodimer in essence. Stacking of these homodimers by the intermolecular D1:D2 interfaces brings 2 D3 domains face-to-face and facilitates their disulfide linkages and multimerization of VWF. Sequential stacking of these homodimers leads to a right-hand helical tubule for VWF storage. The clinically identified VWF mutations in the propeptide disrupted different steps of the assembling process, leading to diminished VWF multimers in von Willebrand diseases (VWD). Overall, these results indicate that the propeptide serves as a pH-sensing template for VWF multimerization and tubular storage. This sheds light on delivering normal propeptide as a template to rectify the defects in multimerization of VWD mutants.

Hemophilia B is almost exclusively caused by mutations of F9 gene and inherited in an X-linked recessive manner(1). The amino acid residue Arginine of FIX with CpG sequence(2) is hot spot for mutation(3), involving CG to TG or CA transitions and causing hemophilia B(4).

Background: It is critical for laboratories to conduct multianalyzer comparisons as a part of daily routine work to strengthen the quality management of test systems. Here, we explored the application of patient‐based real‐time quality controls (PBRTQCs) on comparative assays to monitor the consistency among clinical laboratories.Methods: The present study included 11 commonly tested analytes that were detected using three analyzers. PBRTQC procedures were set up with exponentially weighted moving average (EWMA) algorithms and evaluated using the AI‐MA artificial intelligence platform. Comparative assays were carried out on serum samples, and patient data were collected. Patients were divided into total patient (TP), inpatient (IP), and outpatient (OP) groups.Results: Optimal PBRTQC protocols were evaluated and selected with appropriate truncation limits and smoothing factors. Generally, similar comparative assay performance was achieved using both the EWMA and median methods. Good consistency between the results from patients' data and serum samples was obtained, and unacceptable bias was detected for alkaline phosphatase (ALP) and gamma‐glutamyl transferase (GGT) when using analyzer C. Categorizing patients' data and applying specific groups for comparative assays could significantly improve the performance of PBRTQCs. When monitoring the inter‐ and intraanalyzer stability on a daily basis, EWMA was superior in detecting very small quality‐related changes with lower false‐positive alarms.Conclusions: We found that PBRTQCs have the potential to efficiently assess multianalyzer comparability. Laboratories should be aware of population variations concerning both analytes and analyzers to build more suitable PBRTQC protocols.

Background: Klebsiella pneumoniae (KP) accounts for high antimicrobial resistance and mortality rates of bloodstream infections (BSIs). Objectives: To investigate incidence, antimicrobial resistance and risk factors for mortality of KP BSIs in East China. Methods: A retrospective study of patients with KP BSIs was conducted in a tertiary care hospital from 2018 to 2022. Medical records of all hospitalised patients with KP BSIs were reviewed and analysed. The incidence, antimicrobial resistance and mortality of KP BSIs were evaluated. The Kaplan-Meier method was used to plot survival curves and logistic regression was used to analyse risk factors for crude 30-day mortality. Results: A total of 379 inpatients with KP BSIs were enrolled. The incidence of patients with KP BSIs was fluctuating between 4.77 and 9.40 per 100,000 patient-days. The crude 30-day mortality rate of these patients was 26.39%. Of the 379 KPisolates, 197 (51.98%) were carbapenem-resistant (CR) and 252 (66.49%) were multidrug-resistant (MDR). All isolates showed the lowest resistance to tigecycline (13.77%) and polymyxin B (14.61%). Cases with MDR/CR isolates had significantly longer length of hospital stay, higher crude 30-day mortality and medical costs than non-MDR/non-CR isolates. Age, CR phenotype, paracentesis, indwelling central venous catheter (CVC), use of carbapenems, tetracyclines, polymyxins B, and irrational empiric treatment were independently associated with crude 30-day mortality. Conclusion: MDR/CR KP BSIs are associated with increased mortality, healthcare costs and prolonged hospitalisation. Patients with advanced age, CR phenotype, paracentesis, CVC, exposure to some antibiotics, and irrational empirical antibiotic treatment are at higher mortality risk.