RESUMO
BACKGROUND: Additive manufacturing using fused deposition modelling (FDM) has become widely available with the development of consumer-grade three-dimensional printers. To be useful in maxillofacial surgery, models created by these printers must accurately reproduce the craniofacial skeleton. OBJECTIVE: To determine the accuracy of consumer-grade FDM printers in the production of medical models compared with industrial selective laser sintering (SLS) printers. METHODS: Computed tomography images of a dry skull were manipulated using OsiriX (OsiriX, Switzerland) and ZBrush (Pixologic, USA) software. Models were fabricated using a consumer-grade FDM printer at 100 µm, 250 µm and 500 µm layer heights and an industrial SLS printer. Seven linear measurements were made on the models and compared with the corresponding dry skull measurements using an electronic caliper. RESULTS: A dimensional error of 0.30% was observed for the SLS models and 0.44%, 0.52% and 1.1% for the 100 µm, 250 µm and 500 µm FDM models, respectively. CONCLUSION: Consumer-grade FDM printers can produce medical models with sufficient dimensional accuracy for use in maxillofacial surgery. With this technology, surgeons can independently produce low-cost maxillofacial models in an office setting.
HISTORIQUE: La fabrication additive faisant appel à la modélisation par dépôt de fil en fusion (FDM) s'est généralisée grâce au développement des imprimantes tridimensionnelles pour consommation courante. Pour être utiles en chirurgie maxillo-faciale, les modèles créés par ces imprimantes doivent reproduire le squelette craniofacial avec précision. OBJECTIF: Déterminer la précision d'imprimantes FDM pour consommation courante dans la production de modèles médicaux par rapport à des imprimantes industrielles faisant appel au frittage sélectif par laser (SLS). MÉTHODOLOGIE: Les chercheurs ont manipulé les images tomodensitométriques d'un crâne séché à l'aide des logiciels OsiriX (OsiriX, Suisse) et ZBrush (Pixologic, États-Unis). Ils ont fabriqué les modèles à l'aide d'une imprimante FDM pour consommation courante, à des épaisseurs de couche de 100 µm, 250 µm et 500 µm, ainsi qu'à l'aide d'une imprimante SLS industrielle. Au moyen d'un pied à coulisse électronique, ils ont effectué sept mesures linéaires sur les modèles, qu'ils ont comparées aux mesures du crâne séché. RÉSULTATS: Les chercheurs ont observé une erreur dimensionnelle de 0,30 % dans les modèles SLS et de 0,44 %, 0,52 % et 1,1 % dans les modèles FDM à 100 µm, 250 µm et 500 µm, respectivement. CONCLUSION: Les imprimantes FDM pour consommation courante produisent des modèles médicaux de précision dimensionnelle suffisante pour être utilisés en chirurgie maxillo-faciale. Grâce à cette technologie, les chirurgiens peuvent produire eux-mêmes des modèles maxillo-faciaux à faible coût en cabinet.
RESUMO
Proteins of the ephrin-B group operate in nonlymphoid cells through the control of their migration and attachment, and are crucial for the development of the vascular, lymphatic, and nervous systems. Ephrin-B activity is deregulated in various nonlymphoid malignancies; however, their precise role in cancer has only started to be addressed. We show here that ephrin-B1, a member of the ephrin-B group, is expressed in pediatric T-cell leukemias, including leukemia cell line Jurkat. Treatment of Jurkat cells with ephrin-B-stimulating EphB3 enhances ephrin-B1 phosphorylation and induces its relocalization into lipid rafts. These events are mediated by the T lineage-specific kinase, Lck, as ephrin-B1 phosphorylation and lipid raft association are blocked in the Lck-deficient clone of Jurkat, JCAM1.6. Ephrin-B1 also induces colocalization of the CrkL and Rac1 cytoskeleton regulators and initiates in leukemic cells a strong repulsive response. The absence of Lck blocks ephrin-B1-induced signaling and repulsion, confirming the essential role for Lck in ephrin-B1-mediated responses. This shows a new role for ephrin-B1 in the regulation of leukemic cells through the Lck-dependent Rac1 colocalization with its signaling partner, CrkL, in lipid rafts. In agreement with its repulsive action, ephrin-B1 seems to support metastatic properties of leukemic cells, as suppression of ephrin-B1 signaling inhibits their invasiveness. Because ephrin-B1-activating EphB proteins are ubiquitously expressed, our findings suggest that ephrin-B1 is likely to play an important role in the regulation of malignant T lymphocytes through the control of lipid-raft-associated signaling, adhesion, and invasive activity, and therefore may represent a novel target for cancer treatment.