L'AUDIT MEDICAL

Three essential rules for organizing an audit are laid down: the application must be feasible, legitimate (a real need must exist) and acceptable (it must be instructive and non-coercive). Six stages in setting up an audit are identified: problem selection; criteria selection; data analysis; results analysis; corrective action; reassessment. The example is discussed of an audit of digoxin utilization in hospital.SCOPUS: NotDefined.jinfo:eu-repo/semantics/publishe

Facebook: the revenge of the nerds (February 2012)

Mark Zuckerber is interviewed by The Guardian in 201

Effects of acetylcholine on glomerular sieving of macromolecules

Using a new biomathematical model recently proposed to calculate, from glomerular sieving data for PVP125I, the pores radius (r) and the total area per unit of path length (AP/ΔX) i.e. the parameters characterizing the permeability of an ideal isoporous equivalent membrane, a mean value for the effective glomerular filtration pressure (GFPe) in the dog has been derived from Poiseuille's law. The effects of the intra arterial perfusion of acetylcholine have been studied. As a mean r decreased by 5%, AP/ΔX decreased by 35% while GFPe increased by 60% in the perfused kidney. The same effects have been noticed but less pronounced in the controlateral kidney. These changes are accompanied by an increase in effective renal plasma flow but without modification of glomerular filtration rate (GFR). The significance of these results as far as GFR autoregulation is concerned, is discussed.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

LES HYPERLIPIDEMIES

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CONCEPTION ACTUELLE DU MECANISME DE LA PROTEINURIE

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The effects of angiotensin II on the determinants of glomerular filtration rate (GFR)

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Measurement of the glomerular filtration pressure from sieving data for macromolecules

Equations describing restricted filtration and diffusion of molecules in solution through porous membranes, macromolecular gels and capillary walls have been formulated by Pappenheimer; Renkin; and Landis and Pappenheimer. These formulations allow to calculate the radius of pores, r, (supposed cylindrical) and their total area per unit of path length: {Mathematical expression}. In this study, they have been applied to characterize the glomerular sieve, starting from sieving data for PVP125I. From the mean values for r and {Mathematical expression}, supposing the membrane isoporous, the effective glomerular filtration pressure (GFP) was derived, applying Poiseuille's law. {Mathematical expression} was 30(±2.2) mm Hg in dogs (n=20), and 19.6(±1.9) in humans (n=11). The isoporous model however does not account for the passage in the urine of comparatively large amounts of molecules with a radius higher than 41 Å. Assuming a lognormal distribution of pore radii allows a quite satisfactory adjustment of calculated and experimental values for sieving coefficients in a larger range of molecular radii (23 to 79 Å). This assumption necessitates to compute the value for GFP simultaneously to those characterizing the distribution (median and standard deviation). The values for GFP obtained by this method are slightly lower than [27.1(±2.8) mm Hg], but closely correlate with, those derived supposing the membrane isoporous in dogs. In humans {Mathematical expression} was 11.7(±1.7) mm Hg. However the sieving coefficients higher than 0.65 have to be discarded from the calculations on which rests the choice of the final value for {Mathematical expression}. The reasons for the discrepancies between experimental and calculated values for sieving coefficients close to 1 are discussed by light of recent studies on sieving processes and membrane permeability. © 1971 Springer-Verlag.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Autoregulation of effective glomerular filtration pressure

The curvilinear relationship between the sieving coefficients for polyvinylpyrrolidone 125I (fractional clearances/GFR) and the molecular radii of hydrodynamically equivalent spheres was studied in 42 normal mongrel dogs under Nembutal anesthesia. The parameters characterizing the porosity of an equivalent isoporous membrane, r (radius of cylindrical pores) and Ap/Δx (pore area per unit of path length), were calculated according to sieving equations recently modified on the basis of theoretical studies calculating the drag on a sphere moving in a viscous liquid undergoing a Poiseuille flow inside a cylinder. Effective glomerular filtration pressure (GFPe) has been calculated from the Poiseuille law. The values for r, Ap/Δx, and GFPe have been related to the mean arterial blood pressure (MBP). At MBP levels between 120 and 150 mmHg (group A: n = 22), nonsignificantly different values were calculated: r = 50.2 ± 0.78 Å SEM, Ap/Δx = (1.35 ± 0.1) x 10 5 cm, GFPe = 14.9 ± 0.63 mmHg. At MBP levels above 150 mmHg (group B: n = 20), GFPe was significantly higher (24.2 ± 1.2 Å) and Ap/Δx was significantly lower (0.84 ± 0.007) x 10 5 cm, r remaining unchanged. In 17 dogs (10 from group A, 7 from group B) the aorta was clamped. Autoregulation of GFPe, GFR, and ERPF was present in the first group and almost abolished in the latter. It is suggested that changes in the filtering area contribute to keep GFR constant at increased perfusion pressures.SCOPUS: ar.jinfo:eu-repo/semantics/publishe