Pt Government Assoct Laboratory

Braga, Portugal

Pt Government Assoct Laboratory

Braga, Portugal

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Moreira A.H.J.,Pt Government Assoct Laboratory | Moreira A.H.J.,University of Minho | Moreira A.H.J.,Polytechnic Institute of Cávado and Ave | Queiros S.,Pt Government Assoct Laboratory | And 11 more authors.
Progress in Biomedical Optics and Imaging - Proceedings of SPIE | Year: 2015

The success of dental implant-supported prosthesis is directly linked to the accuracy obtained during implant's pose estimation (position and orientation). Although traditional impression techniques and recent digital acquisition methods are acceptably accurate, a simultaneously fast, accurate and operator-independent methodology is still lacking. Hereto, an image-based framework is proposed to estimate the patient-specific implant's pose using cone-beam computed tomography (CBCT) and prior knowledge of implanted model. The pose estimation is accomplished in a threestep approach: (1) a region-of-interest is extracted from the CBCT data using 2 operator-defined points at the implant's main axis; (2) a simulated CBCT volume of the known implanted model is generated through Feldkamp-Davis-Kress reconstruction and coarsely aligned to the defined axis; and (3) a voxel-based rigid registration is performed to optimally align both patient and simulated CBCT data, extracting the implant's pose from the optimal transformation. Three experiments were performed to evaluate the framework: (1) an in silico study using 48 implants distributed through 12 tridimensional synthetic mandibular models; (2) an in vitro study using an artificial mandible with 2 dental implants acquired with an i-CAT system; and (3) two clinical case studies. The results shown positional errors of 67±34μm and 108μm, and angular misfits of 0.15±0.08 and 1.4, for experiment 1 and 2, respectively. Moreover, in experiment 3, visual assessment of clinical data results shown a coherent alignment of the reference implant. Overall, a novel image-based framework for implants' pose estimation from CBCT data was proposed, showing accurate results in agreement with dental prosthesis modelling requirements. © 2015 SPIE.

Gonalves T.C.,Hospital da Senhora da Oliveira | Barbosa M.,Hospital da Senhora da Oliveira | Rosa B.,Hospital da Senhora da Oliveira | Moreira M.J.,Hospital da Senhora da Oliveira | And 3 more authors.
World Journal of Gastroenterology | Year: 2016

AIM To identify risk factors for P1 lesions on small bowel capsule endoscopy (SBCE) and to describe the natural history of anemic patients with such type of lesions. METHODS One hundred patients were consecutively selected for a case-control analysis performed between 37 cases with P1 lesions and 63 controls with negative SBCE. Age, gender, comorbidities and regular medication were collected. Rebleeding, further investigational studies and death were also analyzed during the follow-up. RESULTS No significant differences on gender, median age or Charlson index were found between groups. Although no differences were found on the use of proton pump inhibitors, acetylsalicylic acid, anticoagulants or antiplatelet agents, the use of non-steroidal antiinflammatory drugs (NSAID) was associated with a higher risk of P1 lesions (OR = 12.00, 95%CI: 1.38-104.1). From the 87 patients followed at our center, 39 were submitted to additional studies for investigation of iron-deficiency anemia (IDA), and this was significantly more common in those patients with no findings on SBCE (53.7% vs 30.3%, P = 0.033). A total of 29 patients had at least one rebleeding or IDA recurrence episode and 9 patients died of non-anemia related causes but no differences were found between cases and controls. CONCLUSION P1 lesions are commonly found in patients with IDA submitted to SBCE. The use of NSAID seems to be a risk factor for P1 lesions. The outcomes of patients with P1 lesions do not differ significantly from those with P0 lesions or normal SBCE. © The Author(s) 2016.

Srisuk P.,European Institute of Excellence on Tissue Engineering and Regenerative Medicine | Srisuk P.,Pt Government Assoct Laboratory | Srisuk P.,Khon Kaen University | Correlo V.M.,European Institute of Excellence on Tissue Engineering and Regenerative Medicine | And 7 more authors.
Journal of Macromolecular Science, Part B: Physics | Year: 2015

Melanins are phenol-based pigments with the potential for widespread applications, including bioelectronics and tissue engineering. The concentration-dependent structural transition of sepia melanin in water is analyzed. This biopolymer at high concentration gives the well-known nanospheres, whereas sample dilution gives unforeseen nanofibres exhibiting the structural features of mature amyloid fibrils. We propose a mechanism of pigment self-assembly dependent on the interaction of residual melanosomal protein(s) with eumelanin heteropolymer. Our results contribute to understanding the peculiar physicochemical properties of this ubiquitous pigment. Copyright © Taylor & Francis Group, LLC.

Leite A.J.,European Institute of Excellence on Tissue Engineering and Regenerative Medicine | Leite A.J.,Pt Government Assoct Laboratory | Caridade S.G.,European Institute of Excellence on Tissue Engineering and Regenerative Medicine | Caridade S.G.,Pt Government Assoct Laboratory | And 2 more authors.
Journal of Non-Crystalline Solids | Year: 2016

Chitosan (CHT) spheres incorporating bioactive glass nanoparticles (BGNPs) were prepared to obtain a composite system able to induce the deposition of an apatite layer upon immersion in a biological-like environment. Spheres were synthesized with different concentrations of BGNPs obtained from a sol-gel route and genipin (GNP, the crosslinking agent). Biomimetic superhydrophobic surfaces were used to support droplets of chitosan-based solutions that after crosslinking enabled to produce well developed spherical particles with controlled sizes. From SEM and EDS analysis it was observed the successful formation of bone-like apatite on the surface when the spheres were immersed in a simulated body fluid (SBF). Lower GNP concentration promoted more apatite formation. The spheres presented shape memory behaviour triggered by hydration with high values of shape fixity and shape recovery. This effect was used to introduce these spheres in a bone defect showing a good geometrical accommodation in the implanted site. The bioactive spheres allowed the incorporation of a drug model and its effective release. Overall the developed nanocomposite spheres showed great potential for bone tissue engineering in particular as a device to be implanted using minimal invasive procedures. © 2015 Elsevier B.V.

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