Hyperelastic behavior of porcine aorta segment under extension-inflation tests fitted with various phenomenological models.

Most of hyperelastic models for the constitutive modeling of the typical mechanical behaviour of the arterial wall tissue in literature are based on the test data from different animals and arteries. This paper is concerned with the material parameter identification of several phenomenological hyperelastic models by fitting the data from five extension-inflation tests of the porcine aorta segment, carried out in our laboratory. A membrane approximation is used to compute stresses and strains achieved during experiments, with usual assumption of material incompressibility.

Histamine index and clinical expression of rheumatoid arthritis activity.

Background/aim: Many arguments prove the pathophysiologic role of histamine in the process of remodeling and joint destruction in rheumatoid arthritis. The aim of our study was to find out if there was a relation between histamine concentration in synovial fluid and blood with clinical expression of disease activity.

Methods: Histamine concentration in synovial fluid and blood was determinated in 19 patients with rheumatoid arthritis.