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MxB/Mx2 is an interferon-induced dynamin-like GTPase, which restricts a number of life-threatening viruses. Because of its N-terminal region, predicted to be intrinsically disordered, and its propensity to self-oligomerize, purification of the full-length protein has not been successful in conventional E. coli expression systems. In this chapter, we describe an expression and purification procedure to obtain pure full-length wild-type MxB from suspension-adapted mammalian cells. We further describe how to characterize its GTPase activity and oligomerization function.Purification of dynamin-related proteins is complicated by their oligomeric tendencies. In this chapter, we describe an established purification regime to isolate the mitochondrial fission protein Drp1 using bacterial expression. Key attributes of dynamins include their ability to hydrolyze GTP and self-assemble into larger polymers under specific conditions. Therefore, the GTPase activity of Drp1 should be examined to confirm isolation of functional protein, and we describe a conventional colorimetric assay to assess enzyme activity. To determine the ability of Drp1 to self-assemble, we induce Drp1 polymerization through addition of a non-hydrolyzable GTP analogue. A sedimentation assay provides a quantitative measure of polymerization that complements a qualitative assessment through visualization of Drp1 oligomers using negative-stain electron microscopy (EM). Importantly, we highlight the caveats of affinity tags and the influence that these peptide sequences can have on Drp1 function given their proximity to functional domains.Mammalian DSPs have been historically isolated either from native tissue sources or from transfected insect cell cultures via time-consuming and cumbersome protocols often yielding protein of variable quality and quantity. A facile and highly reproducible alternative methodology involving the heterologous expression and purification of soluble mammalian DSPs from E. coli, which yields highly active and functional protein of a uniform quality and quantity, free of spurious posttranslational modifications inherent to mammalian and insect cell expression systems, is described in this chapter.The dynamin-related proteins (DRPs) are self-assembling membrane remodeling machines that are indispensable for fundamental cellular trafficking and homeostatic processes. We describe in this chapter protocols developed in our laboratory for purification of full-length and minimal constructs of Chaetomium thermophilum Vps1, the model fungal DRP, using mammalian and Escherichia coli expression systems.Mitochondrial fission, an essential process for mitochondrial and cellular homeostasis, is accomplished by evolutionarily conserved members of the dynamin superfamily of large GTPases. These enzymes couple the hydrolysis of guanosine triphosphate to the mechanical work of membrane remodeling that ultimately leads to membrane scission. The importance of mitochondrial dynamins is exemplified by mutations in the human family member that causes neonatal lethality. In this chapter, we describe the subcloning, purification, and preliminary characterization of the budding yeast mitochondrial dynamin, DNM1, from Saccharomyces cerevisiae, which is the first mitochondrial dynamin isolated from native sources. The yeast-purified enzyme exhibits assembly-stimulated hydrolysis of GTP similar to other fission dynamins, but differs from the enzyme isolated from non-native sources.Children were relatively spared during COVID-19 pandemic. However, the recently reported hyperinflammatory syndrome with overlapping features of Kawasaki disease and toxic shock syndrome-"Paediatric Inflammatory Multisystem Syndrome-temporally associated with SARS-CoV-2" (PIMS-TS) has caused concern. We describe cardiac findings and short-term outcomes in children with PIMS-TS at a tertiary children's hospital. Single-center observational study of children with PIMS-TS from 10th April to 9th May 2020. Data on ECG and echocardiogram were retrospectively analyzed along with demographics, clinical features and blood parameters. Fifteen children with median age of 8.8 (IQR 6.4-11.2) years were included, all were from African/Afro-Caribbean, South Asian, Mixed or other minority ethnic groups. All showed raised inflammatory/cardiac markers (CRP, ferritin, Troponin I, CK and pro-BNP). Transient valve regurgitation was present in 10 patients (67%). Left Ventricular ejection fraction was reduced in 12 (80%), fractional shortening in 8 (53%) with resolution in all but 2. Fourteen (93%) had coronary artery abnormalities, with normalization in 6. ECG abnormalities were present in 9 (60%) which normalized in 6 by discharge. Ten (67%) needed inotropes and/or vasopressors. [https://www.selleckchem.com/products/cfi-400945.html CFI-400945 supplier] None needed extracorporeal life support. Improvement in cardiac biochemical markers was closely followed by improvement in ECG/echocardiogram. All patients were discharged alive and twelve (80%) have been reviewed since. Our entire cohort with PIMS-TS had cardiac involvement and this degree of involvement is significantly more than other published series and emphasizes the need for specialist cardiac review. We believe that our multi-disciplinary team approach was crucial for the good short-term outcomes.Surrogates for the shortest pre-excited R-R interval in atrial fibrillation (SPERRI) such as the accessory pathway effective refractory period (APERP) and shortest pre-excited paced cycle length (SPPCL) are flawed assessments of accessory pathway function in patients with WPW. Multi-extrastimulus pacing may have the theoretical advantage of more accurately mimicking the clinical reality of atrial fibrillation and thus may serve to better assess accessory pathway function. This cross-sectional study included 25 consecutive patients, aged ≤ 18 years, undergoing electrophysiology study for WPW. The longest S1S2, S2S3, S3S4 coupling intervals at which the antegrade AP refractoriness occurred, SPERRI, and SPPCL were recorded. Induction of atrial fibrillation was attempted in all patients and induced in 8 (32%, 4 SPERRIbaseline (265 ms ± 61 ms), 4 SPERRIIsuprel (258 ms ± 41 ms)). At baseline, the lower value of the S3ERP or S4ERP (274 ms ± 52 ms) was lower than the SPPCL (296 ms ± 54 ms, p less then 0.0001) and APERP (296 ms ± 41 ms, p less then 0.