maleic-acid and thiobarbituric-acid

Adhesion between dentin and MMA resin was investigated using chemically activated initiator system consisting of 1,3,5-trimethyl-2-thiobarbituric acid, cupric salt, chloride ion, and tert.-butyl peroxymaleic acid (MA) with carboxyl group which usually has affinity to tooth. The adhesive strength of the MMA/PMMA resin to bovine dentin increased significantly to 8-10 MPa by addition of MA, while the adhesive strength was 4 MPa without MA. When the bonding broke at higher than 7 MPa, the adhesive resin layer usually fractured cohesively and the interfacial fracture did not occur. The bond strength obtained in this experiment was comparable to that obtained with MMA resin using TBBO and ferric ion initiator system which is known as the best initiator system for dentin available.

Topics: Acrylic Resins; Adhesives; Animals; Cattle; Cold Temperature; Dental Bonding; Dental Cements; Dentin; Esters; Maleates; Methylmethacrylates; Thiobarbiturates

The reaction of gamma-glutamyltranspeptidase with phenobarbital or with thiobarbituric acid resulted in a irreversible loss of its enzymatic activity. The inactivation followed pseudo-first-order kinetics. Half-maximal velocity of inactivation (Ki) at 37 degrees C in the presence of phenobarbital or thiobarbituric acid was calculated to be 43 mM and 20 mM, respectively. The inactivation of the enzyme activity by both these inhibitors was prevented by serine borate, a known competitive inhibitor, and by the substrate, reduced glutathione, suggesting an active-site-directed nature of the these inhibitors. Maleate provided slight protection against inactivation by thiobarbituric acid. Complete inactivation of the enzyme with tritium-labeled phenobarbital resulted in a stoichiometric incorporation of radioactivity into the enzyme protein. Upon sodium dodecyl sulfate polyacrylamide gel electrophoresis of tritium-labeled phenobarbital-enzyme complex, nearly all the radioactivity was found to be associated with the small subunit (Mr = 22 000) of the enzyme, indicating that the catalytic component of the enzyme is on the small subunits.

Topics: Animals; gamma-Glutamyltransferase; Glutathione; Kidney; Male; Maleates; Phenobarbital; Rats; Rats, Inbred Strains; Thiobarbiturates