Free radical depolymerization of hyaluronan by Maillard reaction products: role in liquefaction of aging vitreous.

The degradation of hyaluronan was followed by viscosimetry and by HPLC in order to study the possible role of Maillard products (lysine-glucose) on the alteration of the vitreous gel in aging and diabetes. Lysine-glucose generated Maillard products produced a decrease of viscosity and of the number average molecular weight (Mn) of hyaluronan during a 1 h incubation at 37 degrees C. This effect was comparable to that produced by 1 U/ml of testicular hyaluronidase but was weaker than the effect of a Fenton-type reagent (Udenfriend's reagent).

Fibronectin in bovine vitreous. An immunochemical study.

The vitreous body is a transparent gel essentially composed of hyaluronan, collagen and proteoglycans. These components are assembled in a three-dimensional structure that is maintained by self-aggregation of macromolecules and the interactions between these different macromolecules. We confirmed the presence of fibronectin in vitreous body using immunochemical methods and by indirect immunofluorescence on cryostat sections.

[Aging of the vitreous body. Role of glycation and free radicals].

The vitreous body plays an important role in the structure and in the function of the eye. Its bio-rheological properties contribute crucially to the mechanical resistance and optical transparency of ocular tissues. The composition and structure of the vitreous body change during aging and more rapidly in diabetes.

Cyclic adenosine monophosphate-dependent mechanisms induce von Willebrand factor expression in the Dami megakaryoblastic cell line.

It has been proposed that cyclic adenosine monophosphate (cAMP) is involved in the differentiation of several cell types and this study analysed whether von Willebrand factor (vWf) synthesis, which is a marker of the megakaryocyte maturation of these cells, would be enhanced by agents acting on cAMP formation. Different compounds known to stimulate cAMP accumulation in cells were used: dibutyryl cAMP (db-cAMP), isobutyl-methylxanthine (IBMX) or pentoxifylline (PTX) and forskolin. Treatments with db-cAMP or IBMX (10-1,000 microM) induced a dose-dependent increase in vWf synthesis.