Reconstruction of the pelvis and lumbar-pelvic junction using 2 vascularized autologous bone grafts after en bloc resection for an iliosacral chondrosarcoma.

Primary pelvic sarcomas remain challenging and complex surgical problems with significant potential for postoperative impairment of ambulation, as well as bowel, bladder, and sexual function. En bloc resection with negative tumor margins represents the best chance of control or cure as current adjuvant therapies remain ineffective. Tumor involvement of the sacrum with extension to the greater sciatic notch and ipsilateral ilium requires an external hemipelvectomy and sagittal sacrectomy with sacrifice of the lower extremity to achieve en bloc resection, followed by lumbar-pelvic reconstruction. A patient with an iliosacral chondrosarcoma is presented to illustrate a novel lumbar-pelvic reconstruction technique, in which vascularized soft tissue and 2 vascularized bone grafts were harvested from the amputated lower extremity and transferred to the pelvis as composite flaps to restore pelvic ring integrity, augment lumbar-pelvic fusion, and close the soft-tissue defect. The biomechanical dynamics of this unique construct are discussed.

Inhibition of bovine phenol sulfotransferase (bSULT1A1) by CoA thioesters. Evidence for positive cooperativity and inhibition by interaction with both the nucleotide and phenol binding sites.

Previous work with the bovine phenol sulfotransferase (bSULT1A1, EC ) demonstrated inhibition by CoA that was competitive with respect to the sulfuryl donor substrate, 3'-phosphoadenosine-5'-phosphosulfate (PAPS) (Leach, M., Cameron, E., Fite, N., Stassinopoulos, J., Palmreuter, N., and Beckmann, J. D. (1999) Biochem. Biophys. Res. Commun. 261, 815-819). Here we report that long chain acyl-CoAs are more potent inhibitors of bSULT1A1 and also of human dopamine sulfotransferase (SULT1A3) when compared with unesterified CoA and short chain-length acyl-CoAs. A complex pattern of inhibition was revealed by systematic variation of palmitoyl-CoA, PAPS, and 7-hydroxycoumarin, the acceptor substrate. Convex plots of apparent K(m)/V(max) versus [palmitoyl-CoA] were adequately modeled using an ordered rapid equilibrium scheme with PAPS as the leading substrate and by accounting for the possible binding of two equivalents of inhibitor to the dimeric enzyme. Interestingly, the first K(i) of 2-3 microm was followed by a second K(i) of only 0.01-0.05 microm, suggesting that positive subunit cooperativity enhances binding of long chain acyl-CoAs to this sulfotransferase. Simultaneous interaction of palmitoyl-CoA with both the nucleotide and phenol binding sites is suggested by two experiments. First, the acyl-CoA displaced 7-hydroxycoumarin from the highly fluorescent bSULT1A1.PAP.7-HC complex in a cooperative manner. Second, palmitoyl-CoA prevented the quenching of bSULT1A1 fluorescence observed with pentachlorophenol. Finally, titrations of bSULT1A1-pentachlorophenol complex with palmitoyl-CoA caused the return of protein fluorescence, and the binding of palmitoyl-CoA was highly cooperative (Hill constant of 1.9). Overall, these results suggest a model of sulfotransferase inhibition in which the 3'-phosphoadenosine-5'-diphosphate moiety of CoA docks to the PAPS domain, and the acyl-pantetheine group docks to the hydrophobic phenol binding domain.