Louis Nel | PubMed Health

PubMed2005

Bone ingrowth in retrieved Bryan Cervical Disc prostheses.

STUDY DESIGN: Explant analysis for bone ingrowth of retrieved cervical disc prosthesis in chimpanzees and humans. OBJECTIVES: To assess the bone ingrowth into retrieved Bryan Cervical Discs. SUMMARY OF BACKGROUND DATA: Bone ingrowth in cervical disc prosthesis has not been documented in the literature. METHODS: Chimpanzee: Two chimpanzees underwent placement of the Bryan disc at C3-C4 and 3 months later had explantation and interbody fusion. Human: Two patients had removal of their Bryan disc and interbody fusion for failure to resolve symptoms at 8 and 10 months. The explants were analyzed for bone ingrowth. RESULTS: Chimpanzee: Histologic analysis showed bony ingrowth through the interstices of the porous coating and apposition ranging from 10% to 50% of toluidine blue-stained sections. New ingrowth, rather than bony impaction, was confirmed with fluorochrome-labeled sections Human: Bone ingrowth was a mean of 30.1% (12% SD). No difference was observed between peripheral, intermediate, or central locations. CONCLUSIONS: Adequate bony apposition was found in all primate device-to-vertebral body interfaces. Human retrievals also demonstrated significant ingrowth in all four surfaces. This compares with hip and knee arthroplasty percent ingrowth rates of 10% to 30%. All implants had stable fixation judged by radiographs and at the time of implant removal.

Animals↗

PubMed2002

Genetic heterogeneity in the foot-and-mouth disease virus Leader and 3C proteinases.

The Leader and 3C proteinases of foot-and-mouth disease virus (FMDV) are responsible for almost all the proteolytic processing events of the viral polyprotein precursor. Investigation into the genetic heterogeneity of the regions encoding these proteins from isolates of six FMDV serotypes revealed the 3C proteinase to be more conserved than the Leader proteinase. Maximum likelihood analysis indicated similar phylogenetic groupings for the non-structural protein coding regions of both the Leader and 3C. These groupings were different from the structural VP1 protein coding region which, as shown previously, grouped according to serotype. Two distinct clades were apparent for both the Leader and 3C coding regions: one comprising of serotypes A, O and C together with SAT (South African Territories) isolates from eastern Africa. The other clade consisted of SAT isolates originating from southern Africa. Only one virus isolate, obtained from a buffalo in Uganda, did not conform to this phylogenetic pattern. This SAT 1 virus grouped with types A, O and C in the Leader analysis, but with the southern African SAT types in the 3C analysis, implicating intertypic recombination. The leader proteinases of southern African SAT type isolates differed from those present in European type isolates, particularly in the self-processing region. A three-dimensional structure was modeled for the Leader proteinase of one of the SAT type viruses, ZIM/7/83/2, and compared with the previously elucidated crystal structure of O(1)Kaufbeuren Leader proteinase. The active sites of the two leaders were found to superimpose closely, despite the observed sequence variation between the two molecules. Comparison of the 3C proteinase P1 cleavage sites suggested that the FMDV 3C proteinase may possess a broader substrate specificity, as observed in hepatitis A virus 3C proteinase.

3C Viral Proteases↗