Evaluation of fixed-dose versus variable-dose prothrombin complex concentrate for warfarin reversal.

INTRODUCTION: The purpose was to compare hemostatic efficacy rates for fixed- and variable-dose four-factor prothrombin complex concentrate (4F-PCC) for warfarin reversal. MATERIAL AND METHODS: Retrospective study of patients with non-intracranial major bleeding or undergoing emergent surgery/procedure who received 4F-PCC for warfarin reversal from September 2013 through August 2020. Hemostatic efficacy at 48 h following fixed- or variable-dose 4F-PCC was evaluated using modified International Society on Thrombosis and Hemostasis (ISTH) criteria for major bleeding. Secondary outcomes included occurrence of post-4F-PCC INR ≤ 1.5, in-hospital mortality, time to 4F-PCC administration, and 4F-PCC cost. Univariate analyses were completed and logistic regression used to identify patient-specific factors associated with hemostatic efficacy. RESULTS: A total of 265 patients, 90 (34%) fixed- and 175 (66%) variable-dose 4F-PCC, were included. Hemostatic efficacy was achieved in 34 (37.8%) and 38 (21.7%) in fixed- and variable-dose groups, respectively, p = 0.005. Achievement of INR ≤ 1.5 occurred in 55 (62.5%) in the fixed- and 120 (69.4%) in the variable-dose groups, p = 0.26, and there was no in-hospital mortality difference. Time to administration was a mean 20 min faster and cost was reduced by a mean $1881/dose in the fixed-dose group. The unadjusted odds of achieving hemostatic efficacy was 2.27 among those receiving fixed-dose compared to variable-dose 4F-PCC (95% CI 1.30, 3.98); this was not confounded by initial INR or patient weight. CONCLUSION: Fixed-dose 4F-PCC is associated with a higher likelihood of achieving hemostatic efficacy, quicker time to administration, and reduced cost compared to variable-dose 4F-PCC for warfarin reversal.

A subset of FG-nucleoporins is necessary for efficient Msn5-mediated nuclear protein export.

The transport of proteins between the cytoplasm and nucleus requires interactions between soluble transport receptors (karyopherins) and phenylalanine-glycine (FG) repeat domains on nuclear pore complex proteins (nucleoporins). However, the role of specific FG repeat-containing nucleoporins in nuclear protein export has not been carefully investigated. We have developed a novel kinetic assay to investigate the relative export kinetics mediated by the karyopherin Msn5/Kap142 in yeast containing specific FG-Nup mutations. Using the Msn5 substrate Crz1 as a marker for Msn5-mediated protein export, we observe that deletions of NUP100 or NUP2 result in decreased rates of Crz1 export, while nup60Δ and nup42Δ mutants do not vary significantly from wild type. The decreased Msn5 export rate in nup100Δ was confirmed using Mig1-GFP as a transport substrate. A nup100ΔGLFG mutant shows defects in nuclear export kinetics similar to a nup100Δ deletion. Removal of FG-repeats from Nsp1 also decreases export kinetics, while a loss of Nup1 FXFGs does not. To confirm that our export data reflected functional differences in protein localization, we performed Crz1 transcription activation assays using a CDRE::LacZ reporter gene that is upregulated upon increased transcription activation by Crz1 in vivo. We observe that expression from this reporter increases in nup100ΔGLFG and nsp1ΔFGΔFXFG strains that exhibit decreased Crz1 export kinetics but resembles wild-type levels in nup1ΔFXFG strains that do not exhibit export defects. These data provide evidence that the export of Msn5 is likely mediated by a specific subset of FG-Nups and that the GLFG repeat domain of Nup100 is important for Msn5-mediated nuclear protein export.