ABSTRACT
Association of bovine serum albumin (BSA) on heating in the presence and absence of 2% xylose has been studied using dynamic light scattering and sedimentation velocity. When 3% solutions of the protein alone are heated at 95 degrees C association products are formed with molar masses of approximately 2 x 10(6) g/mol, a value which is independent of the time of heating. These aggregates can be dissociated in solvents that disrupt non-covalent bonds. When the reducing sugar xylose is present there is a continuous change in the hydrodynamic properties with time. After 80 min a molar mass in excess of 7 x 10(6) g/mol is obtained. This increase in molar mass is attributed to additional non-disulphide linkages resulting from the Maillard reaction. Information about the gross conformation of the Maillard induced association products has been obtained from MHKS (Mark-Houwink-Kuhn-Sakarada) double logarithmic plots of D20,w and S20,w against molar mass. The values of the MHKS coefficients obtained are most consistent with a linear rod: i.e. the association is of an end-to-end type.
Subject(s)
Serum Albumin, Bovine/chemistry , Animals , Cattle , Cross-Linking Reagents , Hot Temperature , Hydrogen-Ion Concentration , In Vitro Techniques , Light , Macromolecular Substances , Maillard Reaction , Molecular Weight , Protein Conformation , Scattering, Radiation , Solutions , XyloseABSTRACT
One hundred seventy-three cases of intertrochanteric fractures treated by internal fixation are reviewed: 72 treated with the Jewett nail and 101 with the Richards compression hip screw. Both devices maintained adequate reduction in the majority of cases. Treatment failure: loss of fixation, symptomatic joint penetration, aseptic necrosis, malunion and nonunion occurred in 25% of the Jewett nail cases and 6% of the Richards screw cases. In vitro biomechanical studies demonstrate that the compression screw is subjected to less bending stress by acting as a lateral "tension band" in stable reductions and by allowing sliding, thus shortening the bending movement lever arm in unstable reductions. The compression hip screw is valuable in the treatment of intertrochanteric hip fractures. In stable conditions, it acts as a tension band producing more force transmission through the medial cortex, stressing the implant more in tension and less in bending. In unstable conditions with higher shearing forces, the device will shorten the lever arm, decreasing the bending moment, as well as avoiding penetration of the femoral head.