Synthesis of glycoconjugates by human diseased veins: modulation by procyanidolic oligomers

Venous diseases become steadily more common and severe with age, and are often accompanied by venous lymphatic oedema. We have investigated the role of glycoconjugates in this disorder and the action of procyanidols used to treat these diseases. Explants of vein wall from patients with or without venous lymphatic oedema were cultured for 24 hours and the incorporation of radioactive glucosamine into total glycoconjugates and into hyaluronan was measured. The explants from patients with oedema incorporated more glucosamine than those without oedema (+42% expressed as c.p.m./mg dry weight into total glycosaminoglycans and +12% expressed as c.p.m./mg dry weight into hyaluronan). The explants from oedematous patients secreted less glycoconjugates into the culture medium than those from non-oedematous veins (−63% of total incorporated radioactivity into hyaluronan and −66% into hyaluronidase-resistent glycoconjugates). Explants placed in medium containing procyanidols (1 mg/ml, 2.8 m m) incorporated less glucosamine (−19%) and secreted more into the medium (+119%). Glycoprotein and sulphated glycosaminoglycan synthesis were mainly affected which may well explain the beneficial effect of procyanidols on vein disorders

Age-Related Variation in the Biomechanical and Structural Properties of the Corneo-Scleral Tunic

With increasing age, the mechanical performance of the cornea and sclera is impaired due to structural changes in the major structural proteins, namely collagens , proteoglycans and elastin. In addition, the level of hydration in the ocular tunic decreases over time. These structural changes profoundly impact on the biomechanical properties of the corneo-scleral tunic. This chapter focuses on the structural and biomechanical changes that occur in the corneo-scleral tunic with age. The techniques that are utilized in order to determine the mechanical properties of both the cornea and sclera are discussed, and a comprehensive review of studies which have characterized age-related changes in ocular biomechanics are presented. The cornea is found to increase in stiffness with age and all the characteristics of viscoelastic behavior (creep , stress-relaxation and hysteresis) decrease with age. Similarly, the stiffness of the sclera increases markedly with age although the reported magnitude of stiffening varies significantly from one study to another. This may be related to variations amongst the different techniques that have been utilized. Increased stiffening in the cornea and the sclera with age is strongly associated with the increase in collagen crosslinking that occurs as part of the natural aging process