Biomedical subjects
Publications and source records attributed to M C Willis.
The synthesis of Tc-99m-labeled, modified RNA is reported. This new class of radiopharmaceuticals is of potential interest as target specific imaging agents. The preparation of N3S-RNA was achieved by coupling protected MAG2-units to amino modified ON's. The N3S-RNA was Tc-99m-labeled with 90-95% radiochemical yield and specific activities of 37MBq/nmol leading to 1:1-Tc-99m-N3S-aptamers.
Augmentation is a well-accepted and common component of coracoclavicular ligament repairs and reconstructions. The purpose of this study was to examine and compare the strength, stiffness, and mode of failure of the coracoclavicular ligament complex and four different augmentation techniques in cadaveric shoulders. There was no significant difference in the mean failure load between the intact ligament complex (724.9+/-230.9 N) and augmentations performed with braided polydioxanone (PDS) (676.7+/-115.4 N) or braided polyethylene placed through (986.1+/-391.1 N) or around (762.7+/-218.2 N) the clavicle. The mean failure load for augmentations using a 6.5-mm cancellous screw through the clavicle and into a single cortex of the coracoid (390.1+/-253.6 N) was significantly lower than that for the intact coracoclavicular ligaments. There was no difference in mean stiffness between the intact coracoclavicular ligament complex (115.9+/-36.2 N/mm) and the braided polyethylene augmentations placed through (99.8+/-22.2 N/mm) or around (90.0+/-25.5 N/mm) the clavicle. Polydioxanone augmentations were significantly less stiff (27.4+/-3.3 N/mm) than the intact complex, while screw augmentations were significantly stiffer (250.4+/-88.2 N/mm). There were no significant differences in strength or stiffness of braided polyethylene reconstructions placed around or through a drill hole in the clavicle.
The one-year survival of regenerated cartilage on a large articular surface is presented using the McDowell in vivo model. The model provides a mechanically shielded environment in which regenerated cartilage can be protected from intra-articular stresses while normal joint motion is maintained. New tissue was allowed to grow from bleeding subchondral bone for 12 weeks at which time the original mechanical environment was reintroduced. Our study showed that neo-cartilage would grow to cover the entire joint surface of a patella and could survive for one year. Histologic observations indicated a maturing hyaline-like tissue. Biomechanical analyses showed that the regenerated cartilage became stiffer and less permeable within the time of this study. Biochemical evaluations demonstrated stable properties out to the longest time point. Control specimens, which were not shielded from stress, showed insignificant amounts of new tissue growing on the patellar surfaces.