[ON URIC ACID AND OTHER CLEARANCES AFTER INTRAVENOUS ADMINISTRATION OF FURSEMID IN MAN].
Explore the source record for details and available documents.
SEARCH · Search PubMed
Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
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.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Urate and p-aminohippurate accumulations of kidney tubule fragments were studied in 5- to 6-week-old normal (LUA) and hyperuricemic (HUA) chickens. Tubules from LUA chicks consistently accumulated two to three-fold as much urate and p-aminohippurate as tubules from HUA chicks and thus confirmed the tubular origin of the urate transport defect in HUA chickens. A sodium gradient was required for optimal urate and p-aminohippurate accumulations and ouabain inhibited the accumulations of both compounds. Similar responses of urate and p-aminohippurate to treatments and reciprocal inhibitions between these compounds suggest that urate and p-aminohippurate are accumulated through a shared transport system.
Explore the source record for details and available documents.
Both para-aminohippurate (PAH) and pyrazinamide inhibited the uricosuric response to probenecid administration. The mechanism of this inhibition of probenecid uricosuria was assessed in 18 male subjects. The decrease in uricosuria was assessed in 18 male subjects. The decrease in uricosuric response to probenecid observed after pyrazinamide administration or PAH infusion occurs by different mechanisms. Administration of PAH and probenecid together resulted in reduced excretion of both drugs. PAH was weakly uricosuric and did not appear to inhibit urate secretion. PAH inhibition of probenecid uricosuria is accounted for by inhibition of probenecid secretion. Probenecid excretion was not affected by pyrazinamide administration. Inhibition of probenecid-induced uricosuria by pyrazinamide is most likely due to inhibition of urate secretion. The urate secretory carrier inhibited by pyrazinamide appears to be independent of that responsible for secretion of probenecid and PAH. Probenecid secretion appears to be required for its uricosuric effect.
At physiological plasma urate concentration (Purate) (0.05 mg/dl), net secretion of urate occurred in the convoluted part of the proximal tubule of micropunctured anesthetized pigs. The fraction of filtered urate delivered to the point of micropuncture ((TF/P)urate/(TF/P)polyfructosan) was 4.8 +/- 0.5 (mean +/- SE, n =10). Urate was reabsorbed from lower tubular segments, since the fractional excretion of urate (FEurate) was only 2.1. Saturation of secretion as well as reabsorption occurred at Purate of 1.6 mg/dl. p-Aminohippurate (PAH) secretion also occurred mainly in the pars convoluta of the proximal tubule: (TF/P)PAH/(TF/P)polyfructosan was 4.0 +/- 0.4 (n = 11), whereas the FEPAH was 4.5 +/- 0.5 (n = 5). Thus, the pars recta does not contribute significantly to the net secretion of either urate or PAH. PAH was a competitive inhibitor of urate secretion. At a PPAH of 60 mg/dl there was overall net reabsorption of urate. Accordingly, in the pig PAH and urate seem to be secreted by the same transport mechanism.
Results of previous studies of urate secretion in isolated perfused S2 segments of the rabbit proximal tubule suggested that a bath of rabbit serum may inhibit urate transport in comparison to a synthetic medium. In the current study we tested for a urate transport inhibitor by determining the steady-state tissue-to-medium ratio (T/M) of [14C]urate in nonperfused S2 segments during incubation in synthetic medium (BSA-Burg) and commercial rabbit serum (RS-PF). With 80-120 microM urate in the bath the T/M ratio was 7.66 +/- 0.53 (n = 29) in BSA-Burg and 5.29 +/- 0.40 (n = 29) in RS-PF. RS-PF decreased the influx of urate into the cells but had no effect on urate efflux. Freshly drawn rabbit serum and plasma also inhibited urate accumulation, and the inhibition was reversible. p-Aminohippurate accumulation was inhibited by RS-PF, but tetraethylammonium bromide uptake was not. RS-PF inhibited transepithelial secretion of urate and PAH, but net fluid absorption was not decreased. The inhibitory material in rabbit serum could not be removed by extensive dialysis (14,000-dalton exclusion), by ultrafiltration (50,000-dalton exclusion), or by charcoal or ethanol extraction. Inhibitory activity was detected in both albumin and globulin fractions of rabbit serum. The relation between bath and intracellular urate concentrations of nonperfused tubules in rabbit serum was sigmoidal, whereas the relation in the BSA-Burg medium was more nearly hyperbolic. We conclude that organic anion transport in rabbit S2 segments is inhibited or suppressed by normal serum and suggest that urate secretion and excretion may be subject to allosteric modification by serum proteins.
The mechanisms involved in urate and p-aminohippurate (PAH) transport in the rabbit renal brush-border membrane were investigated through study of membrane vesicles. Transport of [14C]urate and [3H]PAH was measured by a rapid filtration method. As previously reported by others, no OH(-)-PAH exchanger could be demonstrated by imposing an outwardly directed OH- gradient (pHin 7.4, pHout 6). In contrast, an OH(-)-lactate exchanger (or H(+)-lactate cotransport) was demonstrated. In the presence of valinomycin and an inwardly directed K+ gradient, both [14C]urate and [3H]PAH vesicle uptake were stimulated, demonstrating a potential-driven transport of these two anions. Probenecid, PAH, or cold urate decreased potential-driven urate uptake, suggesting that this transport was facilitated by a specific transport mechanism. The potential-driven urate transport described here may play a role in the second step of urate secretion in rabbits, because rate (or PAH) is transported across the brush-border membrane from the negative interior of the cell to the more positive omen.
Explore the source record for details and available documents.