Characterisation of amyloid fibril formation by small heat-shock chaperone proteins human alphaA-, alphaB- and R120G alphaB-crystallins.

AlphaB-Crystallin is a ubiquitous small heat-shock protein (sHsp) renowned for its chaperone ability to prevent target protein aggregation. It is stress-inducible and its up-regulation is associated with a number of disorders, including those linked to the deposition of misfolded proteins, such as Alzheimer's and Parkinson's diseases. We have characterised the formation of amyloid fibrils by human alphaB-crystallin in detail, and also that of alphaA-crystallin and the disease-related mutant R120G alphaB-crystallin. We find that the last 12 amino acid residues of the C-terminal region of alphaB-crystallin are predicted from their physico-chemical properties to have a very low propensity to aggregate. (1)H NMR spectroscopy reveals that this hydrophilic C-terminal region is flexible both in its solution state and in amyloid fibrils, where it protrudes from the fibrillar core. We demonstrate, in addition, that the equilibrium between different protofilament assemblies can be manipulated and controlled in vitro to select for particular alphaB-crystallin amyloid morphologies. Overall, this study suggests that there could be a fine balance in vivo between the native functional sHsp state and the formation of amyloid fibrils.

Multicriteria decision analysis methods with 1000Minds for developing systemic sclerosis classification criteria.

OBJECTIVES: Classification criteria for systemic sclerosis (SSc) are being developed. The objectives were to develop an instrument for collating case data and evaluate its sensibility; use forced-choice methods to reduce and weight criteria; and explore agreement among experts on the probability that cases were classified as SSc. STUDY DESIGN AND SETTING: A standardized instrument was tested for sensibility. The instrument was applied to 20 cases covering a range of probabilities that each had SSc. Experts rank ordered cases from highest to lowest probability; reduced and weighted the criteria using forced-choice methods; and reranked the cases. Consistency in rankings was evaluated using intraclass correlation coefficients (ICCs). RESULTS: Experts endorsed clarity (83%), comprehensibility (100%), face and content validity (100%). Criteria were weighted (points): finger skin thickening (14-22), fingertip lesions (9-21), friction rubs (21), finger flexion contractures (16), pulmonary fibrosis (14), SSc-related antibodies (15), Raynaud phenomenon (13), calcinosis (12), pulmonary hypertension (11), renal crisis (11), telangiectasia (10), abnormal nailfold capillaries (10), esophageal dilation (7), and puffy fingers (5). The ICC across experts was 0.73 [95% confidence interval (CI): 0.58, 0.86] and improved to 0.80 (95% CI: 0.68, 0.90). CONCLUSIONS: Using a sensible instrument and forced-choice methods, the number of criteria were reduced by 39% (range, 23-14) and weighted. Our methods reflect the rigors of measurement science and serve as a template for developing classification criteria.