Management of subtrochanteric femur fractures with internal fixation and recombinant human bone morphogenetic protein-7 in a patient with osteopetrosis: a case report

<p>Abstract</p> <p>Introduction</p> <p>Osteopetrosis is a group of conditions characterized by defects in the osteoclastic function of the bone resulting in defective bone resorption. Clinically, the condition is characterized by a dense, sclerotic, deformed bone which, despite an increased density observable by radiography, often results in an increased propensity to fracture and delayed union.</p> <p>Case Presentation</p> <p>We report the case of a 27-year-old Asian man presenting with bilateral subtrochanteric femur fractures. He had a displaced right subtrochanteric femur fracture after a low-energy fall, which was treated surgically. The second fracture that our patient endured was diagnosed as a stress fracture ten weeks later when he complained of pain in the contralateral left thigh. By that time, the right-sided fracture exhibited no radiographic evidence of healing, and when the left-sided stress fracture was being treated surgically, bone grafting with recombinant human bone morphogenetic protein-7 was also performed on the right side.</p> <p>Conclusion</p> <p>While there are no data supporting the use of bone morphogenic proteins in the management of delayed healing in patients with osteopetrosis, no other reliable osteoinductive grafting options are available to treat this condition. Both fractures in our patient healed, but based on the serial radiographic assessment it is uncertain to what degree the recombinant human bone morphogenetic protein-7 may have contributed to the successful outcome. It may have also contributed to the formation of heterotopic bone around the fracture site. Further investigation of the effectiveness and indications of bone morphogenic protein use for the management of delayed fracture healing in patients with osteopetrosis is warranted.</p

Analyse conformationnelle d'antibiotiques β et γ-lactamiques

Geometry optimization, superimposition searches and conformational analysis carried on several lactam antibiotics show that reactivity with the active-site serine penicillin-binding proteins is related to a particular spatial disposition of 2 flanking functional groups - namely a C = O or C-OH on 1 side and a carboxylate on the other - with respect to the central scissile amide bond. Such a binding entity is found in one of the most stable conformers of the tripeptide diacetyl-L-Lys-D-Ala-D-Ala conferring substrate activity, and in benzylpenicillin, cephapyrin, thienamycin, gamma-lactam, the 6-spiro-epoxypenicillin S and in one epimer of lactivicin, conferring inactivating potency. This binding entity generates a particular electronic distribution and the fact that it is conserved in compounds belonging to very different chemical families strongly suggests that it is an important feature required for enzyme recognition.L'étude par optimisation de géométrie, superposition et analyse conformationnelle réalisée sur plusieurs antibiotiques à noyau lactame montre que leur réactivité vis-à-vis des protéines liant la pénicilline et possédant une sérine active dépend de la disposition spatiale particulière des groupements fonctionnels C=O ou C---OH et carboxylate de part et d'autre de la liaison amide sensible. Ce motif existe dans l'un des conformères les plus stables du tripeptide substrat diacétyl-D -Lys-D -Ala-D -Ala et dans les inhibiteurs benzylpénicilline, céphapyrine, thiénamycine, γ-lactame, ainsi que dans l'un des épimères de la 6-spiroépoxypénicilline et de la lactivicine. Ce motif génère une distribution électronique très particulière et le fait qu'il soit conservé dans des composés appartenant à des familles chimiques très différentes suggère fortement qu'il constitue une caractéristique nécessaire à la reconnaissance enzymatique