The Effects of Pretreatment of Pericardial Tissue on Alkaline Phosphatase Hydrolytic Activity and Extractability
Buffenn, Angela N.
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Bioprosthetic valves frequently fail due to pathological mineralization, a process that begins in cell remnants that have undergone glutaraldehyde treatment. It has been found that other pathological cardiovascular calcification as well as mineralization in both skeletal and dental tissue is, to a great extent, initiated in matrix vesicles. Matrix vesicles are membrane-enclosed structures containing high levels of the enzyme alkaline phosphatase (AP). As a result, the enzyme AP is believed to play an important role in the mineralization of cardiac valves. The objectives of these studies were 1) to determine the effects of freezing and freeze-drying pericardial tissue on AP activity and extractability, 2) to determine the effect of prolonged glutaraldehyde storage on AP activity and extractability, 3) to determine if AP activity returned with implantation, and 4) to obtain maximum AP hydrolytic activity using the substrate para-nitrophenol phosphate (PNPP). It was concluded that 1) freezing and freeze-drying pericardial tissue did not produce changes in either AP activity or extractability, 2) AP activity and extratability were lost with prolonged glutaraldehyde storage, 3) AP activity returned with implantation, and 4) maximum AP activity was obtained when samples were placed in a shaking water bath and vortexed during the addition of PNPP.Missing pages 14-16, 18, and 20.