Biomechanics of the weakened mandible: use of image correlation analysis.

Uninterrupted resection of mandibular bone is often necessary during maxillofacial operations for cancer. This weakens the mandible, and increases the risk of fracture. To our knowledge no biomechanical analysis has been made of deformations and strains that occur during chewing if this happens, so we have made such an analysis of the weakened mandible using a new technique: image correlation. Five fresh explanted human mandibles were prepared with black and white lacquer, and placed in a loading device that allowed replication of a physiological biting exercise. Calibrated pieces of bone were resected from the right body of each mandible. Images of the mandibular surface were recorded by 2 cameras and analysed with an algorithm to correlate them, which allowed us to confirm the distribution of strain on the body of the mandible, and to focus on the weak points. Before the bone was resected, we noted tensile strains on the alveolar border of the body, and compressive strains on the basilar border. The intensity of the strains in the posterior angle of the resected bony area then increased, with reduction in the height of the bone until fracture. The orientation of the fracture line started at the lower posterior angle of the resection area and spread in a lower posterior direction until it reached the basilar border of the mandible. Image correlation is a new technique for the study of mandibular biomechanics that provides accurate measurements on a wide bony surface with high definition images and without modification of the structure. Its application to weakened mandible provided reliable images of modifications to strains during simulated biting exercises.

[Techniques of anastomoses issue from vascular surgery and apply to maxillofacial microsurgery]. / Application des techniques d'anastomoses de chirurgie vasculaire à la microchirurgie maxillofaciale.

Vascular surgeons use an anastomosis technique that has proven its efficiency for a long time. This technique consists in an anastomosis with spatulated ended vessels designed with opposite obliquity. This anastomosis is closed by a continuous suture. Authors expose the results of this technique applied to microvascular surgery in facial reconstruction.

[Abdominoplasty after twin pregnancy: study of 30 cases]. / Plastie abdominale après grossesse gémellaire : à propos de 30 cas.

INTRODUCTION: Compared to single mother-hood, the twin pregnancy results in important esthetic and functional sequelae of the abdominal wall. The considerable uterine growth involves a musculocutaneous diastasis of both the supra-umbilical and the infra-umbilical area. This study presents the modified abdominoplasty technique with an inverted T scar as the appropriate treatment of supra-umbilical and infra-umbilical musculocutaneous defects. METHODS AND MATERIALS: This series reviews a total of 30 female patients of 35 years on average. There was no cases obesity or smoking reported. Surgical treatment consisted in a skin and fat resection following an inverted T scar design and associated to a muscle plication. In 6 patients it has been necessary to repeat the procedure in 6 months time. RESULTS: All 30 patients resolved with an aesthetic and functional improvement. No instances of abdominal diastasis recidivation occurred. There were no complication observed and no impact on the healing process was referred. CONCLUSION: on of the main differences between single and twin pregnancies is that the second ones are concerned by an abdominal diastasis marked on both a vertical and a transversal direction. The complete surgical treatment sometimes includes a second intervention. Clinical results and luck of complications suggest that the T-type abdominoplasty associated to a muscle re-tightening offers an appropriate surgical treatment of patients concerned.

[Management of chicken pox purpura fulminans: a pediatric case report]. / Prise en charge d'un purpura fulminans varicelleux: à propos d'un cas pédiatrique.

The authors report a case of a 4 years old girl who had presented a chicken-pox purpura fulminans. Lesions appeared 5 days after chicken-pox start and were quickly evoluted in cutaneous and sub-cutaneous necrosis on external side of thighs and behind side of right calf. A medical management was done with fresh plasma, blood, antithrombine 3, and fibrin. Specifics treatments were done: heparin and activated C protein. Surgical treatment was realised 5 weeks later. It consisted of clean necrosis areas and put a thin skin graft witch was took on the scalp. The evolution was fast good. The follow-up is 3 years without big esthetic and functional consequences. Some cases of this pathology were described in literature with serious lesions. The management should be multidisciplinary. Surgical treatment should be realised when lesions are stabilized. Scalp is a donor site for skin graft very interesting because of big quantity of skin and not esthetic consequence.

Characterization and molecular basis of the oligomeric structure of HIV-1 nef protein.

The Nef protein of human immunodeficiency virus type I (HIV-1) is an important determinant for the onset of AIDS disease. The self-association properties of HIV-1 Nef are analyzed by chemical cross-linking, dynamic light scattering, equilibrium analytical ultracentrifugation, and NMR spectroscopy. The experimental data show that the HIV-1 Nef core domain forms stable homo-dimers and trimers in solution, but not higher oligomers. These Nef homomers are not covalently linked by disulfide bridges, and the equilibrium between these forms is dependent on the Nef concentration. We further provide the molecular basis for the Nef core dimers and trimers obtained by analysis of crystallographic models. Oligomerization of biological polypeptides is a common tool used to trigger events in cellular signaling and endocytosis, both of which are targeted by Nef. The quaternary structure of Nef may be of physiological importance and may help to connect its cellular targets or to increase affinity of the viral molecule for its ligands. The herein described models for Nef dimers and trimers will allow further mutational studies to elucidate their role in vivo. These results provide novel insight into the structural and functional relationships of this important viral protein. Moreover, the oligomer interface may represent a novel target for the design of antiviral agents.