Accuracy of medical models made by consumer-grade fused deposition modelling printers.

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.

Online learning in paediatrics: a student-led web-based learning modality.

BACKGROUND: undergraduate medical education is shifting away from traditional didactic methods towards a more self-directed learning environment. E-learning has emerged as a vital learning modality that allows students to apply key principles to practical scenarios in a truly personalised approach. CONTEXT: at the University of Alberta, paediatrics is taught longitudinally, with lectures distributed throughout the preclinical curriculum and concentrated in the 8-week paediatric clinical clerkship. As a result, students entering clerkship lack core foundational knowledge and clinical skills. INNOVATION: PedsCases (http://www.pedscases.com) is a student-driven interactive website designed to achieve the learning outcomes identified by the competency-based paediatric curriculum. This open-access e-learning tool is a comprehensive peer-reviewed learning resource that incorporates various learning modalities. Material is student generated and peer reviewed by staff paediatricians to ensure validity, accuracy and usefulness. After 17 months, PedsCases contains 216 questions, 19 cases, 11 flashcard-type quizzes, 11 podcasts and two clinical videos, and has had 2148 unique visitors from 73 different countries. PedsCases is one of the top five references returned by Internet search engines for the phrase 'paediatrics for medical students'. IMPLICATIONS: PedsCases is a collaborative resource created for and by medical students that provides an opportunity for active self-directed learning while disseminating knowledge in an evidence-based, interactive and clinically relevant fashion. PedsCases encourages students to take an active role in their education and drive medical education initiatives in response to the evolving curriculum. As the focus of medical education shifts towards independent learning, student-led educational tools such as PedsCases have emerged as essential resources for students.

Development of a flexible healthcare form builder using Ruby on Rails.

A collaboratively maintained, centralized web-based clinical decision support system (CDSS) repository could lead to improved quality and standardization of care and decrease duplication of resources. Ruby on Rails (RoR) is an open source web application framework that enables rapid iterative development of database backed applications. We have created a prototype form building application in RoR that has the potential to create and maintain such a CDSS repository. Further study and refinement are required.

In human leukemia cells ephrin-B-induced invasive activity is supported by Lck and is associated with reassembling of lipid raft signaling complexes.

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.