The effect of procyanidolic oligomers on the composition of normal and hypercholesterolemic rabbit aortas

Enhanced oral bioavailability of oligomeric proanthocyanidins by a self-double-emulsifying drug delivery system

The present study aims at the formulation and evaluation of solid self-double-emulsifying drug delivery system (SDEDDS) to increase the bioavailability of oligomeric proanthocyanidin (OPC). The formulation is prepared through two-step method and is able to form water-in-oil-in-water (W/O/W) double emulsions after diluted with aqueous medium while keeping the drug in inner water phase. Solid-state characterization is performed by DSC and X-ray powder diffraction. Furthermore, antioxidant capacity shows that OPC is preserved by the solid SDEDDS. OPC-SDEDDS exhibit sustained release of OPC under the conditions mimicking gastrointestinal tract. The result shows that bioaccessibility of OPC is improved after incorporating into SDEDDS formulation compared to pure drug. The proposed SDEDDS is a promising carrier strategy for delivering the hydrophilic compounds with low-oral bioavailability.

Substrate-protecting antiproteolytic agents for the prevention of pathological degradation of connective tissues. A review

Connective tissues play an important role in the physiological functions of the organism. The integrity of the macromolecular components of these tissues, also called extracellular matrix, is necessary for their functional efficiency. A number of proteinases present in the organism, and the activity of which increases with age and with several pathologies, specifically degrade the components of the extracellular matrix. For a long time, tentatives for the protection of the matrix-components against degradation were made with low molecular weight inhibitors, not very efficient in vivo and not devoid of inconveniencies. We initiated a different approach for the preservation of the macromolecules of the extracellular matrix against proteolytic degradation with substances which exert an intense antiproteolytic activity not only in vitro, but also in vivo. The particularity of these substances is the fact that they do not act on the enzymes, but combine with the macromolecules. This is the type of combination of substances with the macromolecules of the matrix that prevents their degradation by the proteinases. Because of this affinity of such antiproteolytic agents not for the enzymes but for the substrates, we called them "substrate protectors" (Robert et al., 1979). The aim of the present review is to summarise the essential of our experiments which led to the description of substrate protectors.

Effect of procyanidolic oligomers on corneal collagen of rabbits treated by excimer laser photoablation

Procyanidolic oligomers (PCO) are mainly used for their therapeutic effect on the vascular wall. We could show that the mechanism of this effect involves interactions with mesenchymal cells and extracellular matrix (ECM). Recently we demonstrated in vitro that they also act on cornea, a tissue rich in ECM. For instance they stimulate the corneal biosynthesis of type VI collagen and proteoglycans. A potent antiprotease effect also could be demonstrated on corneas. In our present work we examined in vivo action of PCO on corneas. A group of rabbits received during 1 week on their right eye a treatment by procinaidolic oligomers, the left eyes were kept as controls. After 1 week both eyes underwent excimer laser photobalation. Another group of rabbits also received the PCO treatment on the right eye, not on the left, but was not treated by photoablation. One week after the surgical intervention corneas were collected and biochemical and morphological observations were carried out. Ocular administration of PCO was well tolerated and no toxic or inflammatory side-effects could be seen. In the control group photoablation was followed by a decrease of the content of corneas in type I collagen and a strong increase in type III collagen. On the corneas treated by PCO these alterations of the composition were not observed. These results indicate that PCO treatment before excimer laser photoablation maintains within normal limits the biochemical composition of the operated corneas.

Influence of baroreflex on volume elasticity of heart and aorta in the rabbit

Optimal ventriculoaortic coupling includes tuning of elastic properties. The ratio of effective arterial elastance and left ventricular endsystolic elastance is often taken as a measure for mechanical and energetical efficiency. The present study determined the time course of ventricular and aortic volume elasticity (VE = dp/dV) throughout a complete heartbeat. This was achieved by using changes of eigenfrequency of two catheter-transducer systems under closed chest conditions in rabbits. Short-term VE modulation was studied by a baroreflex response, as induced by pressure changes applied to the carotid sinus. Long-term changes were studied in atherosclerotic rabbits (12 wk of high-cholesterol feeding). The time course and mean values of ventricular and aortic VE were changed by the baroreflex stimulus. Cholesterol feeding diminished the response. The degree of ventriculoaortic coupling, as quantified by VE(Aorta)/VE(Ventricle) ratio, varied during a single ejection period. The large span allows either maximal energetical efficiency or maximal stroke work. Although normal rabbits adjusted their ventriculoaortic coupling during baroreflex input, the cholesterol-fed rabbits failed to do so.