[A Massive Open Oneline Course (MOOC) on pratical histology: A goal, a tool, a large public ! Return on a first experience]. / Un « Massive Open Online Course ¼ (MOOC) sur des travaux pratiques en histologie : un objectif, un outil, un public varié ! Retour sur une première expérience.

A goal ! The MOOC entitled "Introduction to Histology, A Human Tissue Exploration" correspond to our vision of the practice of General Histology, which is based on the ability to diagnose 5 families of biological tissues. Ultimately, participants must be able to recognize the different types of cells and all the surrounding elements in order to understand how they organize themselves to form tissues with specific functions. A tool ! This know-how is based on reasoning from observations of microscopic structures. Learners are therefore invited to manipulate a virtual microscope to explore biological samples on histological slides digitized. Annotations, comments, drawings or photos are associated with landmarks that enrich the study of these histological sections. A target audience ! Two educational paths allow deepening the subject in a different way and thus matching the goals or motivations of each one. After a first year of experience, usage statistics and surveys of our learners show that the MOOC Histo has allowed each of them to find an interest and federate a community of motivated learners.

Mechanisms controlling the oxygen consumption in experimentally induced hypochloremic alkalosis in calves.

The study was carried out on healthy Friesian calves (n = 10) aged between 10 and 30 days. Hypochloremia and alkalosis were induced by intravenous administration of furosemide and isotonic sodium bicarbonate. The venous and arterial blood samples were collected repeatedly. 2,3-diphosphoglycerate (2,3-DPG), hemoglobin and plasmatic chloride concentrations were determined. The red blood cell chloride concentration was also calculated. pH, PCO2 and PO2 were measured in arterial and mixed venous blood. The oxygen equilibrium curve (OEC) was measured in standard conditions. The correspondence of the OEC to the arterial and mixed venous compartments was calculated, taking blood temperature, pH and PCO2 values into account. The oxygen exchange fraction (OEF%), corresponding to the degree of blood desaturation between the arterial and mixed venous compartments and the amount of oxygen released at the tissue level by 100 mL of blood (OEF Vol%) were calculated from the arterial and mixed venous OEC, combined with PO2 and hemoglobin concentration. Oxygen delivery (DO2) was calculated using the arterial oxygen content, the cardiac output measured by thermodilution, and the body weight of the animal. The oxygen consumption (VO2) was derived from the cardiac output, OEF Vol% and body weight values. Despite the plasma hypochloremia, the erythrocyte chloride concentration was not influenced by furosemide and sodium bicarbonate infusion. Due to the alkalosis-induced increase in the 2,3-DPG, the standard OEC was shifted to the right, allowing oxygen to dissociate from hemoglobin more rapidly. These changes opposed the increased affinity of hemoglobin for oxygen induced by alkalosis. Moreover, respiratory acidosis, hemoconcentration, and the slight decrease in the partial oxygen pressure in mixed venous blood (Pvo2) tended to improve the OEF Vol% and maintain the oxygen consumption in a physiological range while the cardiac output, and the oxygen delivery were significantly decreased. It may be concluded that, despite reduced oxygen delivery, oxygen consumption is maintained during experimentally induced hypochloremic alkalosis in healthy 10-30 day old calves.