[Relation between the distribution and orientation of collagen fibers and the inorganic phase of calcification processes in the anterior leaflet of the human mitral valve]

The collagen fibers observed in calcified valves appear randomly distributed without any preferential arrangement. In these areas also the hydroxylapatite crystals do not show any orientation. It is suggested that the disorder of the organic phase is a factor favouring the deposition of the calcium crystals.

Arrangement of microfibrils in collagen fibrils of tendons in the rat tail. Ultrastructural and x-ray diffraction investigation

The microfibrillar arrangement in collagen fibrils of tendons in the tail of the rat was examined by electron microscopy and X-ray diffraction. Fresh and air-dried collagen fibers were examined in unstretched and stretched conditions. The results demonstrate that the microfibrils have a course parallel to the longitudinal axis of the collagen fibrils. The influence of stretching and hydration of the samples on the orientation of fibrils and microfibrils is also assessed.

[The relation between erythrocyte filterability and platelet aggregation (in vitro studies in normal subjects and those with vascular disease before and after isotonic exercise)]

The aim of this study was to evaluate the possible action in vitro of the platelets on the rheological behavior of red blood cells in healthy subjects and in patients with peripheral obliterative arterial disease before and after an isotonic exercise. Red blood cells and platelets from control subjects and from patients were tested in several ratios before and after the exercise studying the erythrocyte filterability. beta-thromboglobulin, a platelet-specific protein, was determined in vivo in all subjects before and after the exercise and in vitro as percent of increase between PPP and PRP activated, to monitor the platelet release. The results showed the interrelationship between platelet activation and rheological behavior of red blood cells.