Biochem Biophys Res Commun
August 1999
Amyloid beta (Abeta) is a 40- to 42-residue peptide that is implicated in the pathogenesis of Alzheimer's Disease (AD). As a result of conformational changes, Abeta assembles into neurotoxic fibrils deposited as 'plaques' in the diseased brain. In AD brains, the small heat shock proteins (sHsps) alphaB-crystallin and Hsp27 occur at increased levels and colocalize with these plaques.
View Article and Find Full Text PDFExplanted mechanical heart valves were examined nondestructively, and the findings were related to guidelines, technical reports, and other information to judge the risk of failure and its possible impact on valve design and clinical practice. Diagnoses for single valves could be made, but risks and rates of failure for patient populations could not be predicted due to insufficient information concerning the manufacturing process and valve and patient numbers. Based on the results of this study and the principle that decisions on recalls and patient counseling must be based on scientific knowledge rather than on wait and see policies, the following is recommended: registration of all implanted valves, follow-up of a large cohort of valve carriers, comparison of wear test results of preimplant and postretrieval valves, maintenance of a reference stock of valves and materials, and submission of failure scenarios to certifying bodies.
View Article and Find Full Text PDFBiochem Biophys Res Commun
June 1998
Three members of the small heat shock protein family, alphaA-, alphaB-crystallin, and HSP27, confer thermoresistance upon their overexpression in mammalian cells. Phosphorylation, in conjunction with the molecular chaperone-like activity of these small HSPs, is believed to be important for this in situ functional property. We here report the influence of heat shock and other kinds of stress on the phosphorylation of alphaA-, alphaB-crystallin, and HSP27 in stably transfected HeLa cells.
View Article and Find Full Text PDFEur J Cardiothorac Surg
April 1997
Objective: Non-destructive assessment of 62 Björk-Shiley convexo-concave heart valves in view of the risk of fracture and possible detection of defects by means of X-ray or acoustics.
Methods: Scanning electron microscopy and stereomicroscopy of an unselected sample of valves, representing approximately 70% of the valves explanted between 1991 and 1996. Mean duration of implantation was 10.
The bovine eye lens protein alpha A-crystallin has been overexpressed both by stable transfection of HeLa cells and by transient transfection of NIH 3T3 cells. In both experimental systems alpha A-crystallin overexpression results in an increased cellular thermoresistance as judged by different clonal survival assays. In contrast, similar overexpression of another stable lens protein, beta B2-crystallin, does not confer thermoresistance.
View Article and Find Full Text PDFThe C-terminal domain and tail, which is the most conserved region of the alpha-crystallin/small heat shock protein (HSP) family, was obtained from rat alpha A-crystallin, bovine alpha B-crystallin and mouse HSP25. All three domains have primarily beta-sheet conformation and less than 10% of alpha-helix, like the proteins from which they are derived. Whereas the C-terminal part of alpha A-crystallin forms dimers or tetramers, the corresponding regions of alpha B-crystallin and HSP25 form larger aggregates.
View Article and Find Full Text PDFHomogenates of hatching gland explants were fractionated by means of different electrophoretic techniques, and the fractions analyzed for proteolytic activity and for their capacity to affect the envelope of the eggs. Agar gel electrophoresis resulted in two fractions that were able to digest the zona radiata interna, and a third fraction that caused a significant swelling of the egg envelope. All three fractions were proteolytically active.
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