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Biomedical subjects

E Giesbrecht

Publications and source records attributed to E Giesbrecht.

25 records · Page 2Linked to original sources
PubMed1988

Effects of quinidine on the renal tubular and biliary transport of digoxin: in vivo and in vitro studies in the dog.

Quinidine is known to inhibit the renal clearance of digoxin without affecting glomerular filtration rate. The renal interaction between these drugs was investigated by a combination of in vivo and in vitro methods. The uptake of digoxin by brush border membrane vesicles was not affected by quinidine. Similarly, digoxin did not inhibit the uptake of the cation N-methylnicotinamide by these vesicles and did not alter the binding kinetics of digoxin to the Na+, K+-adenosine triphosphatase by the antiluminal membrane vesicles. By using the in vivo multiple indicator dilution technique transtubular transport of digoxin was documented; renal-artery infusion of quinidine did not affect the recovery of digoxin in the renal vein or urine. Clearance studies documented that the decrease in the renal clearance of digoxin is paralleled by a significant fall in renal blood flow evidenced by a decrease in p-aminohippuric acid clearance. It is concluded that quinidine inhibits the renal excretion of digoxin not by competition at the tubular cell membrane level, but rather by decreasing renal blood flow. A parallel decrease in biliary clearance of digoxin is documented and may suggest a similar mechanism.

Animals↗
PubMed1987

Receptor radioligand system for measuring digoxin activity.

The purpose of this study was to develop and evaluate a receptor radioligand assay (RRA) for the measurement of digoxin, its metabolites, and endoxin and to compare the results of this assay with those of a fluorescence polarization immunoassay (FPIA) for digoxin. The within-run coefficients of variations for the RRA at digoxin concentrations of 2.0 and 5.0 nmol/L were 21 and 10%, respectively. Serum samples collected from 33 volunteers (not on digoxin medication) measured in the RRA resulted in levels less than 1.23 nmol/L digoxin equivalents (1.23 nmol/L is the lower level of sensitivity for this system). Serum samples collected from 29 patients receiving digoxin for therapeutic purposes and measured in the RRA gave a mean of 3.39 nmol/L digoxin equivalents. The samples collected from the patients receiving digoxin were also measured using FPIA with a mean of 1.75 nmol/L digoxin. The interference of progesterone, 11-alpha-hydroxyprogesterone, cortisone, and six digoxin metabolites on the binding of 3H-ouabain in the RRA was also evaluated.

Animals↗
PubMed1986

A study of lipid effects on the digoxin immunoassay and on the binding to and activity of Na+/K+-ATPase.

The present study has examined the cross-reactivity of fatty acids and mono- and di-glycerides in the fluorescence polarization immunoassay for digoxin. The ability of these compounds to inhibit 86Rb uptake by the erythrocyte as well as their ability to displace 3H-ouabain from membrane-bound dog kidney ATP-ase was also assessed. Some unsaturated fatty acids (palmitoleic, palmitelaidic, oleic, linoleic, linolelaidic, linolenic, gamma-linolenic and arachidonic) were found to cross-react significantly in the digoxin immunoassay and to inhibit 3H-ouabain binding to membrane-bound Na+/K+-ATPase. Of the monoglycerides studied mono-11-eicosenoin was found to cross-react in the digoxin immunoassay, inhibit red cell 86Rb uptake and displace 3H-ouabain from its receptor, membrane-bound Na+/K+-ATPase. Two other monoglycerides, 1-monolinoleoyl and 1-monolinolenoyl glycerides, were able to displace 3H-ouabain from membrane-bound Na+/K+-ATPase, but had no effect on the digoxin immunoassay or on red cell 86Rb uptake.

Animals↗
PubMedDate not supplied

The hippurate ratio as an indicator of functional hepatic reserve for resection of hepatocellular carcinoma in cirrhotic patients.

Predicting the ability of the cirrhotic liver to withstand resection remains a challenge for the surgeon. This study evaluates the use of the hippurate ratio, a novel assessment of glycine conjugation of para-aminobenzoic acid by the liver, as a preoperative indicator of functional hepatic reserve. Between 1998 and 2000, sixty-one cirrhotic patients were prospectively assessed for hepatic resection using the hippurate ratio, indocyanine green retention at 15 minutes (ICG R-15), and other standard measures of liver function. Twenty-six patients were excluded as candidates for resection on the basis of inadequate functional hepatic reserve. Patients excluded from resection had significantly higher ICG R-15 values (29% +/- 9% vs. 16% +/- 12%, P = 0.001), higher Child-Pugh scores (5.9 +/- 0.9 vs. 5.3 +/- 0.4, P = 0.01), and lower hippurate ratios (30% +/- 14% vs. 45% +/- 15%, P = 0.005). There was a significant correlation between the hippurate ratio and ICG R-15. Other indicators of liver function such as factor V, factor VII, albumin, bilirubin, prothrombin time, and transaminases were no different between patients who did and those who did not undergo resection. Of the 35 patients resected, there were seven (20%) who developed varying degrees of liver failure with three perioperative deaths (8.5%). Patients who had some degree of liver failure had significantly lower hippurate ratios than patients who had no liver failure (29% +/- 10% vs. 48% +/- 14%, P = 0.002). There was no difference in ICG R-15 values between patients who had liver failure and those who did not. The hippurate ratio offers information on hepatocellular reserve that is not provided by other measures of liver function and may allow better selection of cirrhotic patients for liver resection.

4-Aminobenzoic Acid↗