The Experts below are selected from a list of 6 Experts worldwide ranked by ideXlab platform
I. Janků - One of the best experts on this subject based on the ideXlab platform.
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Physiological modelling of renal drug clearance
European Journal of Clinical Pharmacology, 1993Co-Authors: I. JankůAbstract:A physiological model of renal drug clearance is presented with the aim of establishing a basis for adjusting drug dosing regimens in renal insufficiency. In agreement with the morphology of blood supply to the nephron, the model assumes serial arrangement of the processes involved in drug excretion. Fractional extraction by filtration in the glomeruli is defined in terms of the product of the unbound fraction of the drug, the filtration fraction being responsible for the limited extraction efficiency of this process. For a description of the limitations of the tubular secretory process by Plasma Flow through peritubular capillaries, the parallel tube model is utilized. The assumption of direct proportionality between the transport maximum of the secretory process and filtrate Flow in the tubules permits a quantitative comparison of the intrinsic tubular secretion clearance and the effectiveness of the filtration process. Provided that the secretory mechanism is highly effective, renal clearance becomes dependent only on Kidney Plasma Flow and the fraction of drug not reabsorbed in the tubules. Tubular reabsorption results only in a proportional decrease in renal clearance. The model predicts proportionality of renal drug clearance to GFR, which as a rule is used for dosage adjustment of drugs in renal insufficiency, only for compounds exclusively excreted by filtration. Compounds also excreted by tubular secretion in general exhibit a curvilinear relationship. The curvature is less pronounced as an increasing fraction of the drug is protein bound in blood. Therefore, for dosage adjustment of drugs secreted in the tubules and highly bound in blood, proportionality between renal clearance and GFR can serve as a reasonable approximation. According to the model, distinct deviations from simple proportionality, which will require dosage adjustment methods involving assessment both of glomerular and tubular functions of the Kidney, can be expected mainly for drugs for which an efficient Flow-dependent secretion process is not counteracted by extensive binding of the drug to blood constituents.
R. I. C. Wesdorp - One of the best experts on this subject based on the ideXlab platform.
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Glutamine-Enriched Enteral Diet Increases Renal Arginine Production
JPEN. Journal of parenteral and enteral nutrition, 1994Co-Authors: A. P. J. Houdijk, P.a.m. Van Leeuwen, T. Teerlink, E. L. Flinkerbusch, Marja A. Boermeester, Hans P. Sauerwein, R. I. C. WesdorpAbstract:BACKGROUND Arginine (Arg) is generated in the Kidney by the conversion of circulating citrulline. The most important source for circulating citrulline is the metabolism of glutamine (Gln) by the gut. In this study, we investigated the influence of an enteral diet enriched with Gln on renal Arg synthesis in the rat. METHODS Rats were fed a 12.5% Gln-enriched diet or an isocaloric, isonitrogenous control diet for 14 days. Kidney Plasma Flow and arterial and renal venous Plasma levels of a number of amino acids were measured, and Kidney amino acid fluxes were calculated. RESULTS Compared with the control diet, Gln enrichment resulted in significantly higher arterial Plasma levels of circulating citrulline (30%, p < .0001) and Arg (31%, p < .0005). The uptake of circulating citrulline and the subsequent production of Arg by the Kidneys were significantly higher in the Gln-enriched group (40% and 38%, respectively) and showed an equimolar relationship in both the control (r = .84, p < .0001) and the Gln-enriched group (r = .83, p < .0001). CONCLUSIONS The findings indicate that enteral Gln supplementation caused significantly increased arterial Plasma levels of Arg as a result of increased renal Arg production from circulating citrulline. Considering the multiple important biologic properties of Arg, the reported beneficial effects of Gln in catabolic states might be explained in part by increased renal Arg production.
A. P. J. Houdijk - One of the best experts on this subject based on the ideXlab platform.
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Glutamine-Enriched Enteral Diet Increases Renal Arginine Production
JPEN. Journal of parenteral and enteral nutrition, 1994Co-Authors: A. P. J. Houdijk, P.a.m. Van Leeuwen, T. Teerlink, E. L. Flinkerbusch, Marja A. Boermeester, Hans P. Sauerwein, R. I. C. WesdorpAbstract:BACKGROUND Arginine (Arg) is generated in the Kidney by the conversion of circulating citrulline. The most important source for circulating citrulline is the metabolism of glutamine (Gln) by the gut. In this study, we investigated the influence of an enteral diet enriched with Gln on renal Arg synthesis in the rat. METHODS Rats were fed a 12.5% Gln-enriched diet or an isocaloric, isonitrogenous control diet for 14 days. Kidney Plasma Flow and arterial and renal venous Plasma levels of a number of amino acids were measured, and Kidney amino acid fluxes were calculated. RESULTS Compared with the control diet, Gln enrichment resulted in significantly higher arterial Plasma levels of circulating citrulline (30%, p < .0001) and Arg (31%, p < .0005). The uptake of circulating citrulline and the subsequent production of Arg by the Kidneys were significantly higher in the Gln-enriched group (40% and 38%, respectively) and showed an equimolar relationship in both the control (r = .84, p < .0001) and the Gln-enriched group (r = .83, p < .0001). CONCLUSIONS The findings indicate that enteral Gln supplementation caused significantly increased arterial Plasma levels of Arg as a result of increased renal Arg production from circulating citrulline. Considering the multiple important biologic properties of Arg, the reported beneficial effects of Gln in catabolic states might be explained in part by increased renal Arg production.
P.a.m. Van Leeuwen - One of the best experts on this subject based on the ideXlab platform.
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Glutamine-Enriched Enteral Diet Increases Renal Arginine Production
JPEN. Journal of parenteral and enteral nutrition, 1994Co-Authors: A. P. J. Houdijk, P.a.m. Van Leeuwen, T. Teerlink, E. L. Flinkerbusch, Marja A. Boermeester, Hans P. Sauerwein, R. I. C. WesdorpAbstract:BACKGROUND Arginine (Arg) is generated in the Kidney by the conversion of circulating citrulline. The most important source for circulating citrulline is the metabolism of glutamine (Gln) by the gut. In this study, we investigated the influence of an enteral diet enriched with Gln on renal Arg synthesis in the rat. METHODS Rats were fed a 12.5% Gln-enriched diet or an isocaloric, isonitrogenous control diet for 14 days. Kidney Plasma Flow and arterial and renal venous Plasma levels of a number of amino acids were measured, and Kidney amino acid fluxes were calculated. RESULTS Compared with the control diet, Gln enrichment resulted in significantly higher arterial Plasma levels of circulating citrulline (30%, p < .0001) and Arg (31%, p < .0005). The uptake of circulating citrulline and the subsequent production of Arg by the Kidneys were significantly higher in the Gln-enriched group (40% and 38%, respectively) and showed an equimolar relationship in both the control (r = .84, p < .0001) and the Gln-enriched group (r = .83, p < .0001). CONCLUSIONS The findings indicate that enteral Gln supplementation caused significantly increased arterial Plasma levels of Arg as a result of increased renal Arg production from circulating citrulline. Considering the multiple important biologic properties of Arg, the reported beneficial effects of Gln in catabolic states might be explained in part by increased renal Arg production.
T. Teerlink - One of the best experts on this subject based on the ideXlab platform.
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Glutamine-Enriched Enteral Diet Increases Renal Arginine Production
JPEN. Journal of parenteral and enteral nutrition, 1994Co-Authors: A. P. J. Houdijk, P.a.m. Van Leeuwen, T. Teerlink, E. L. Flinkerbusch, Marja A. Boermeester, Hans P. Sauerwein, R. I. C. WesdorpAbstract:BACKGROUND Arginine (Arg) is generated in the Kidney by the conversion of circulating citrulline. The most important source for circulating citrulline is the metabolism of glutamine (Gln) by the gut. In this study, we investigated the influence of an enteral diet enriched with Gln on renal Arg synthesis in the rat. METHODS Rats were fed a 12.5% Gln-enriched diet or an isocaloric, isonitrogenous control diet for 14 days. Kidney Plasma Flow and arterial and renal venous Plasma levels of a number of amino acids were measured, and Kidney amino acid fluxes were calculated. RESULTS Compared with the control diet, Gln enrichment resulted in significantly higher arterial Plasma levels of circulating citrulline (30%, p < .0001) and Arg (31%, p < .0005). The uptake of circulating citrulline and the subsequent production of Arg by the Kidneys were significantly higher in the Gln-enriched group (40% and 38%, respectively) and showed an equimolar relationship in both the control (r = .84, p < .0001) and the Gln-enriched group (r = .83, p < .0001). CONCLUSIONS The findings indicate that enteral Gln supplementation caused significantly increased arterial Plasma levels of Arg as a result of increased renal Arg production from circulating citrulline. Considering the multiple important biologic properties of Arg, the reported beneficial effects of Gln in catabolic states might be explained in part by increased renal Arg production.
