[Novel criteria for assessing red blood cell viability in blood banks]. / Nouveaux critères d'évaluation de la viabilité des hématies destinées à la transfusion.

UNLABELLED: In light of recent results on the mechanism of programmed cell death of human red blood cells (RBC), the aim of the present study was to solve the enigma of the rapid clearance of transfused RBCs. MATERIALS AND METHODS: We describe new criteria of RBC viability founded on the use of flow cytometry. They were applied, in association with the classical ones: ATP and hemolysis measurements, to RBCs stored in SAGM medium for 42 days. RESULTS AND CONCLUSIONS: Application of an original method of flow cytometric quantitation of in vitro erythrophagocytosis showed that an important proportion of stored RBCs were phagocytized although the following classical signals for phagocytosis were absent, i.e.: desialylation, phosphatidylserine exposure in the outer leaflet of the RBC membrane, loss of CD47 receptor, an antiphagocytosis signal. In addition, ATP was still present and hemolysis was very low. This enigma was solved by the use of scanning electron microscopy, which showed the disappearance of discocytes and the presence of an important proportion of spheroechinocytes, which are the phagocytable forms of RBCs. The mechanism of this dramatic morphological transformation remains to be elucidated.

[Eye controlled microscope used in ophthalmic microsurgery]. / Commande du microscope par le regard appliquée à la microchirurgie ophtalmologique.

This article presents a system of oculomotor control of the microscope used in ophthalmic microsurgery. An eye movement sensor has been integrated within the microscope lens. The information provided by this sensor is used to control the position of the microscope with no alteration of the surgeon's visual functions and no interference with his visual sensori-motor reflexes. Results have been obtained from laboratory experimentations as well as from a series of anterior and posterior segment surgical procedures. They demonstrate the high precision and sensitivity of the gaze control which can be used to compensate for the reduction of the field of vision resulting from the optical magnification of the microscope.