Professions and the social order: some lessons from Burkina Faso?

The study of professions has been dominated by Anglo-American models, with their focus on a small group of legally-licensed occupations. The field has recently shifted, mainly through studies of European experience, to a wider examination of the social management of expert workers. Very little has been written about developments in Africa and their implications for the way in which we might think about professions. This paper presents a case study of the role and practices of the medical profession in Burkina Faso, which has a relatively open market for the supply of healing services and limited regulation of the suppliers, whether physicians or traditional practitioners. The study returns to classic questions about the extent to which practice is shaped by the nature of occupational niches within the division of labour or to the development of a distinctive moral character among the workers within that niche

Vascular geometry and oxygen diffusion in the vicinity of artery-vein pairs in the kidney

Renal arterial-to-venous (AV) oxygen shunting limits oxygen delivery to renal tissue. To better understand how oxygen in arterial blood can bypass renal tissue, we quantified the radial geometry of AV pairs and how it differs according to arterial diameter and anatomic location. We then estimated diffusion of oxygen in the vicinity of arteries of typical geometry using a computational model. The kidneys of six rats were perfusion fixed, and the vasculature was filled with silicone rubber (Microfil). A single section was chosen from each kidney, and all arteries (n = 1,628) were identified. Intrarenal arteries were largely divisible into two "types," characterized by the presence or absence of a close physical relationship with a paired vein. Arteries with a close physical relationship with a paired vein were more likely to have a larger rather than smaller diameter, and more likely to be in the inner-cortex than the mid- or outer cortex. Computational simulations indicated that direct diffusion of oxygen from an artery to a paired vein can only occur when the two vessels have a close physical relationship. However, even in the absence of this close relationship oxygen can diffuse from an artery to periarteriolar capillaries and venules. Thus AV oxygen shunting in the proximal preglomerular circulation is dominated by direct diffusion of oxygen to a paired vein. In the distal preglomerular circulation, it may be sustained by diffusion of oxygen from arteries to capillaries and venules close to the artery wall, which is subsequently transported to renal veins by convection

The Influence of renal vascular geometry on oxygen delivery to renal tissue

No abstract availabl

A quantitative analysis of the factors influencing oxygen diffusion in the vicinity of artery-vein pairs in the kidney

Background: Diffusion of oxygen from arteries to veins in the kidney (AV oxygen shunting) acts to limit oxygen delivery to renal tissue. We recently employed computational modeling to identify two factors critical to determination of the quantity of AV oxygen shunting within the renal circulation. These were (i) the distance between the artery and the vein, and (ii) the degree to which the vein wraps around the wall of the artery. Aim: To quantify how the factors in (i) and (ii) above change along the course of the renal circulation. Methods: The renal vasculature of Sprague Dawley rats (n=6) was perfusion fixed and filled with Microfil®. A section from each kidney was chosen and the shortest arterial/arteriolar diameter, distance to the nearest vein, and the degree to which a vein wraps an artery were measured. Results: The diffusion distance between arteries and veins increased with decreasing arte-rial diameter (Figure 1). The proportion of the arterial wall surrounded by the vein (wrapping) decreased as arterial diameter decreased (Figure 2). Conclusions: The spatial relationships (separation and wrapping) between arteries and veins that promote AV oxygen shunting are more prominent in the larger vessels than the smaller vessels of the kidney. These observations challenge the conventional notion that most AV oxygen shunting occurs in the smaller cortical vessels (e.g., interlobular arteries) after the divergence of the cortical and medullary circulations. Thus, AV oxygen shunting may limit oxygen delivery to the renal medulla as well as the renal cortex