Countering cognitive biases in minimising low value care

Cognitive biases in decision making may make it difficult for clinicians to reconcile evidence of overuse with highly ingrained prior beliefs and intuition. Such biases can predispose clinicians towards low value care and may limit the impact of recently launched campaigns aimed at reducing such care. Commonly encountered biases comprise commission bias, illusion of control, impact bias, availability bias, ambiguity bias, extrapolation bias, endowment effects, sunken cost bias and groupthink. Various strategies may be used to counter such biases, including cognitive huddles, narratives of patient harm, value considerations in clinical assessments, defining acceptable levels of risk of adverse outcomes, substitution, reflective practice and role modelling, normalisation of deviance, nudge techniques and shared decision making. These debiasing strategies have considerable face validity and, for some, effectiveness in reducing low value care has been shown in randomised trials

Decreased heat stability and increased chaperone requirement of modified human βB1-crystallins

Purpose: To determine how deamidation and partial loss of the N- and C-terminal extensions alter the heat stability of βB1-crystallin. Methods: Human lens βB1, a deamidated βB1, Q204E, and αA-crystallins were expressed. Truncated βB1 was generated by proteolytic removal of part of its terminal extensions. The aggregation and precipitation of these proteins due to heating was monitored by circular dichroism and light scattering. The effect of heat on the stability of both monomers and oligomers was investigated. The flexibility of the extensions in wild type and deamidated βB1 was assessed by 1H NMR spectroscopy. Results: With heat, deamidated βB1 precipitated more readily than wild type βB1. Similar effects were obtained for either monomers or oligomers. Flexibility of the N-terminal extension in deamidated βB1 was significantly reduced compared to the wild type protein. Truncation of the extensions further increased the rate of heat-induced precipitation of deamidated βB1. The presence of the molecular chaperone, αA-crystallin, prevented precipitation of modified βB1s. More αA was needed to chaperone the truncated and deamidated βB1 than deamidated βB1 or truncated βB1. Conclusions: Deamidation and truncation of βB1 led to destabilization of the protein and decreased stability to heat. Decreased stability of lens crystallins may contribute to their insolubilization and cataract formation

The molecular chaperone, alpha-crystallin, inhibits amyloid formation by apolipoprotein C-II

© 2001 by The American Society for Biochemistry and Molecular Biology, Inc.Under lipid-free conditions, human apolipoprotein C-II (apoC-II) exists in an unfolded conformation that over several days forms amyloid ribbons. We examined the influence of the molecular chaperone, α-crystallin, on amyloid formation by apoC-II. Time-dependent changes in apoC-II turbidity (at 0.3 mg/ml) were suppressed potently by substoichiometric subunit concentrations of α-crystallin (1-10 μg/ml). α-Crystallin also inhibits time-dependent changes in the CD spectra, thioflavin T binding, and sedimentation coefficient of apoC-II. This contrasts with stoichiometric concentrations of α-crystallin required to suppress the amorphous aggregation of stressed proteins such as reduced α-lactalbumin. Two pieces of evidence suggest that α-crystallin directly interacts with amyloidogenic intermediates. First, sedimentation equilibrium and velocity experiments exclude high affinity interactions between α-crystallin and unstructured monomeric apoC-II. Second, the addition of α-crystallin does not lead to the accumulation of intermediate sized apoC-II species between monomer and large aggregates as indicated by gel filtration and sedimentation velocity experiments, suggesting that α-crystallin does not inhibit the relatively rapid fibril elongation upon nucleation. We propose that α-crystallin interacts stoichiometrically with partly structured amyloidogenic precursors, inhibiting amyloid formation at nucleation rather than the elongation phase. In doing so, α-crystallin forms transient complexes with apoC-II, in contrast to its chaperone behavior with stressed proteins.Danny M. Hatters, Robyn A. Lindner, John A. Carver, and Geoffrey J. Howlet

Glycosylation of sputum mucins is altered in cystic fibrosis patients

Cystic fibrosis (CF) is characterized by chronic lung infection and inflammation, with periods of acute exacerbation causing severe and irreversible lung tissue damage. We used protein and glycosylation analysis of high-molecular mass proteins in saline-induced sputum from CF adults with and without an acute exacerbation, CF children with stable disease and preserved lung function, and healthy non-CF adult and child controls to identify potential biomarkers of lung condition. While the main high-molecular mass proteins in the sputum from all subjects were the mucins MUC5B and MUC5AC, these appeared degraded in CF adults with an exacerbation. The glycosylation of these mucins also showed reduced sulfation, increased sialylation, and reduced fucosylation in CF adults compared with controls. Despite improvements in pulmonary function after hospitalization, these differences remained. Two CF children showed glycoprotein profiles similar to those of CF adults with exacerbations and also presented with pulmonary flares shortly after sampling, while the remaining CF children had profiles indistinguishable from those of healthy non-CF controls. Sputum mucin glycosylation and degradation are therefore not inherently different in CF, and may also be useful predictive biomarkers of lung condition

The quaternary organization and dynamics of the molecular chaperone HSP26 are thermally regulated

The function of ScHSP26 is thermally controlled: the heat shock that causes the destabilization of target proteins leads to its activation as a molecular chaperone. We investigate the structural and dynamical properties of ScHSP26 oligomers through a combination of multiangle light scattering, fluorescence spectroscopy, NMR spectroscopy, and mass spectrometry. We show that ScHSP26 exists as a heterogeneous oligomeric ensemble at room temperature. At heat-shock temperatures, two shifts in equilibria are observed: toward dissociation and to larger oligomers. We examine the quaternary dynamics of these oligomers by investigating the rate of exchange of subunits between them and find that this not only increases with temperature but proceeds via two separate processes. This is consistent with a conformational change of the oligomers at elevated temperatures which regulates the disassembly rates of this thermally activated protein.Justin L.P. Benesch, J. Andrew Aquilina, Andrew J. Baldwin, Agata Rekas, Florian Stengel, Robyn A. Lindner, Eman Basha, Glyn L. Devlin, Joseph Horwitz, Elizabeth Vierling, John A. Carver, and Carol V. Robinsonhttp://www.cell.com/chemistry-biology/hom