Paula Matos

Residual Stresses around an Expanded Hole in an Aluminum Clad Sheet

Cold working introduces a compressive stress field around rivet holes, reducing the tendency for fatigue cracks to initiate and grow under cyclic mechanical loading. As it is well known, for the accurate assessment of fatigue lifetimes a detailed knowledge of the residual stress profile is required. Powerful experimental and numerical tools are nowadays available for that purpose. In the present work both types of tools, X-ray diffraction and 3D Finite Element Analysis (FEA), were used in order to evaluate the residual stress profile. A comparison of experimental and numerical data is presented and discussed.

The Diagnosing Challenge of a Positive ANCA Vasculitis in the Paediatric Age

ANCA-positive systemic vasculitides, rare in paediatric age, present multiorganic involvement. A female teenager presented with a history of subglottic stenosis diagnosed at the age of 12. From the investigation carried out, we highlight hematoproteinuria and negative ANCAs. At 15 years old, she was admitted for gastrointestinal symptoms and respiratory distress. She presented poor peripheral perfusion, pulmonary haemorrhage, respiratory failure, and severe renal insufficiency. She was started mechanical ventilation and emergency haemodialysis. The immunological study revealed ANCA MPO positive. A presumptive diagnosis of ANCA-positive vasculitis was made, and she was started corticotherapy, cyclophosphamide, and plasmapheresis. A renal biopsy, performed later, showed crescentic glomerulonephritis with chronicity signs. Positive ANCA vasculitis may progress slowly or suddenly. The diagnosis was confirmed by a biopsy; however, we can make a presumptive diagnosis based on clinical findings and in a positive ANCA test in order to start an early treatment and decrease the associated morbimortality.

Pediatric renal transplantation: a single center experience

Introduction: End-stage renal disease in children is associated with numerous comorbidities and with age-specific mortality rates approximately 30 times higher than in healthy children. The first kidney transplantation in children was performed successfully in 1954. Surgical advances and new immunosuppressive medications have greatly improved patient’s and graft’s survival in the last years. Aim: Report Centro Hospitalar do Porto experience in pediatric renal transplantation in the last 30 years. Methods: Epidemiological and clinical data of all patients younger than 18 years, transplanted between January 1984 and August 2013, were collected from our database. In order to analyze the transplantation outcome in our center we compare graft survival between decades (1984-89 / 1990-99 / 2000-09 / 2010-13). We also compare graft survival between two age groups of patients (0-10 years ; 11-17 years) at the time of surgery. Results: One hundred thirty-nine patients (58.3% male) underwent 147 renal transplants (6.8% live donors). Congenital anomalies of the kidney and urinary tract (56.5%) and glomerulonephritis (18.4%) were the major causes of renal disease. Uncensored graft survivals rates at 5, 10, 15 and 20 years were 84.7%, 71.1%, 60.0% and 51.0%, while patient survivals were 97.9%, 95.9%, 94.7% and 94.7% respectively. Graft survival improved over time and the difference between the decades was statistically significant (p=0.004). Despite the better survival in the group of patients older than 11 years, graft’s survival difference between the two age groups was not statistically significant (p=0.697). Conclusion: The results of our hospital are comparable to other international centers. Significant improvement in survival was observed over the time. It seems that an accurate follow-up of our patients helps to minimize the negative impact of adolescence on graft survival rates.