Aim It has been suggested that patients with porphyria cutanea tarda (PCT) are at high risk of developing hepatocellular carcinoma (HCC); however, this has not been confirmed by other workers. The aim of our study was to evaluate the incidence of HCC in patients with PCT, and to assess the possible co-factors associated with cancer development. Methods Thirty-nine consecutive patients with a diagnosis of PCT were included. Hepatitis B virus and hepatitis C virus (HCV) infection was investigated, and a percutaneous liver biopsy was performed. Patients were treated with phlebotomies, which resulted in a clinical remission in all. These patients were included in a surveillance programme for the detection of HCC, with ultrasonography and serum alpha-fetoprotein every 6 months. Results Thirty-nine patients (92% male; mean age, 55 +/- 16 years) with PCT were included. Alcohol abuse was reported in 87% of the cases. The mean follow-up time since the initial diagnosis of PCT was 9.7 years (378 patient-years of follow-up). Serological markers of past infection with hepatitis B virus were found in 20% of the patients, while HCV infection was diagnosed in 56%. The stage of fibrosis in patients having liver biopsy was: 0 (32%), 1 (32%), 2 (9%), 3 (18%), and 4 (9%). HCC was diagnosed in 1/39 patients with PCT (cumulative incidence, 2.6%), giving a yearly incidence of 0.26% per patient-year. This patient was a 69-year-old male, alcohol abuser, with HCV infection, with a 12-year period between diagnosis of PCT and HCC, and with liver biopsy (3 years before) showing fibrosis stage 3. Conclusion The risk of developing HCC in patients with PCT in our area is relatively low (a yearly incidence of less than 1% per patient-year of follow-up), and perhaps attributable, at least in part, to concomitant HCV infection. Patients presenting with PCT should undergo both HCV infection determination and liver biopsy, and those with concomitant HCV infection or advanced fibrosis/cirrhosis should probably be included in a standard surveillance programme in order to achieve early diagnosis of HCC.

Proposes an automatic adaptive meshing scheme. Error in strain energy is directly obtained through strain energy density function (SED). Versatility of this function, in comparison with that of others, is looked at in detail. Mesh enrichment method consists of a series of h-refinement steps and concludes with a single p-refinement step. Adds that an examination of the accuracy of the element used in the refinement procedure is made. This scheme has been implemented in ZATILAN, a FE code developed in the Department of the Mechanical Engineering of the University of the Basque Country.

The present paper proposes a procedure for the resolution of non-linear structural problems. It includes a study of the reliability of the results and the adaptive meshing The iterative phase of the solution of the equilibrium equations entails an adaptive strategy for updating the tangent stiffness matrix, with a control of the load step. This results in a higher rate of convergence for the iterative process. The mechanical deformation processes here considered may give rise to considerable geometric distortion in the finite elements of the mesh. If they do, the consequence will be not only that the FE analysis fails to yield precise results, but also, owing to problems deriving from the numerical ill-conditioning that continuation may be impractical. To facilitate the study of these results, we developed an error estimator of the flux projection type, which is based on the mechanical deformation power It is also used as a refinement criterion for the FE mesh. Distorted meshes can be fully or partially submitted to a process of regularization based on the aspect ratio of their elements. The mesh contour may be affected by the refinement and regularization processes, for which reason we developed a procedure for its updating. This procedure is of more importance in the case of contact problems, its Primary object being to avoid interpenetration. The work was done in the ZATILAN code, developed by the Department of Mechanical Engineering of the University of the Basque County.

Reviews the book 'Computer Aided Optimum Design of Structures VII,' by S. Hern 谩 ndez and C. A. Brebbia.