Cardiac structure and function in humans: a new cardiovascular physiology laboratory

As the traditional cardiovascular control laboratory has disappeared from the first-year medical school curriculum, we have recognized the need to develop another "hands-on" experience as a vehicle for wide-ranging discussions of cardiovascular control mechanisms. Using an echocardiograph, an automatic blood pressure cuff, and a reclining bicycle, we developed protocols to illustrate the changes in cardiac and vascular function that occur with changes in posture, venous return, and graded exercise. We use medical student volunteers and a professional echocardiographer to generate and acquire data, respectively. In small-group sessions, we developed an interactive approach to discuss the data and to make a large number of calculations from a limited number of measurements. The sequence of cardiac events and cardiac structure in vivo were illustrated with the volunteers lying down, standing, and then with their legs raised passively above the heart to increase venous return. Volunteers were then asked to peddle the bicycle to achieve steady-state heart rates of 110 and 150 beats/min. Data were collected in all these states, and calculations were performed and used as the basis of a small-group discussion to illustrate physiological principles. Information related to a surprisingly large number of cardiovascular control mechanisms was derived, and its relevance to cardiovascular dysfunction was explored. This communication describes our experience in developing a new cardiovascular control laboratory to reinforce didactic material presented in lectures and small-group sessions.

Distribution of radiolabelled azelaic cid in eye membranes and fluids of rabbits

A direct cytotoxic effect of azelaic acid on melanocytes of human melanoma has been demonstrated. In view of a possible future therapeutic employment of this drug in the treatment of primary ocular melanoma, we investigated the route of choice of azelaic acid administration in rabbits. Our results evidenced a suden and direct blood absorption of topically (by retrobulbar injection) administered azelaic acid. This is in agreement with the high water solubility of azelaic acid sodium salt. These preliminary reports indicate that the elective route of azelaic administration in primitive eye melanoma is intravenously by continuous infusion.