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PubMed1989

Age dependence of renal function: clearance of iohexol and p-amino hippurate in healthy males.

Iohexol, a newly developed non-ionic contrast agent, has been recently documented as a reliable glomerular filtration marker. This study describes the age dependence of the single injection clearance of iohexol in a sample of healthy male volunteers ranging from 21 to 77 years of age. In parallel, renal plasma flow was studied by measuring the total clearance of p-amino hippuric acid administered as a continuous infusion. In subjects older than 50 years a negative correlation to age was found for both p-amino hippuric acid and iohexol clearance, with a reduction of 52 ml/min and 12 ml/min per decade, respectively, whereas no age dependence was found for younger subjects. Correlation between p-amino hippuric acid and iohexol clearances was 0.81. However, the filtration fraction, defined as the ratio of iohexol to p-amino hippuric acid clearance, was higher in the elderly subjects. A consistent discrepancy was found between total and renal clearances of p-amino hippuric acid, indicating significant renal metabolism. Renal clearance of creatinine was poorly correlated to iohexol clearance and did not show any relationship to age.

Adult↗

PubMedDate not supplied

Simultaneous determination of creatine, uric acid, creatinine and hippuric acid in urine by high performance liquid chromatography.

A simple method for the simultaneous determination of creatine, uric acid, creatinine and hippuric acid in urine using reversed-phase high performance liquid chromatography was described. Chromatography was performed on a Nova-Pak C18 (3.9 x 150 mm) column with a mobile phase of 0.02 mol/L KH2PO4, and UV detection at 220 nm. The recoveries of creatine, uric acid, creatinine and hippuric acid were 103.13, 99.86, 98.26 and 98.24%, respectively. The calibration curves were linear within the concentration range of 2-200 micrograms/mL for creatine, uric acid and hippuric acid, and 2-400 micrograms/mL for creatinine. The detection limits of the method were 0.69, 0.21, 0.10 and 0.095 microgram/mL for creatine, uric acid, creatinine and hippuric acid, respectively. This method has been applied to the analysis of urine samples from normal subjects and some patients.

Chromatography, High Pressure Liquid↗

PubMed1987

Hippuric acid and ortho-cresol as biological indicators of occupational exposure to toluene.

Industrial exposure to toluene was studied in a group of 18 subjects working in a printing plant, exposed only to this solvent. Environmental monitoring was carried out using personal samplers for the whole work-shift. Urine samples were collected for the determination of hippuric acid and ortho(o)-cresol before toluene exposure, at the end of the work-shift, and 5, 9, and 17 h after the end of the work-shift. The values of two metabolites in all the urinary samples were corrected for g creatinine and specific gravity (1.024). Toluene time weighted average (TWA) concentrations ranged from 51 to 221 mg/m3 (7-h samples; two samplings lasting 3.5 h each). Urinary hippuric acid and o-cresol values at the end of the work-shift were significantly higher than the prework-shift values. Both hippuricuria and o-cresoluria end-of-work-shift values, corrected for creatinine and specific gravity, were significantly related to the mean daily environmental concentration of toluene, the correlation being weaker for o-cresol. Correlation coefficients were 0.88 and 0.84 for hippuric acid and 0.63 and 0.62 for o-cresol after correction for creatinine and specific gravity, respectively. No significant relationship was observed between environmental exposure and the values of the two urinary metabolites 5, 9, and 17 h after the end of the work-shift. Extrapolated values from the linear regression analysis at 375 mg/m3 were in good agreement with the biological exposure index (BEI) suggested by ACGIH for hippuric acid.(ABSTRACT TRUNCATED AT 250 WORDS)

Cresols↗

PubMed1992

Urinary excretion of o-cresol and hippuric acid after toluene exposure in rotogravure printing.

In 62 male rotogravure printers, the time-weighted average (TWA) toluene exposure during one workweek ranged from 8 to 496 mg/m3 (median 96). Post-shift urinary excretion of hippuric acid showed a poor correlation with the air toluene concentration. Level of o-cresol excretion ranged from 0.08 to 2.37 mmol/mol creatinine and was associated with the exposure (rS = 0.57, P less than 0.0001), although the variation was considerable. However, this metabolite was significantly influenced by smoking habits, both in the workers (0.34 vs 0.10 mmol/mol creatinine after adjustment to zero exposure for the smokers and non-smokers, respectively; P = 0.03) and in 21 unexposed controls (0.18 vs 0.06 mmol/mol creatinine; P = 0.002). The excretion of these metabolites was followed during vacation, when the workers were unexposed. The shared one-compartment half-time was 44 h (+/- SE 30, 82). After 2-4 weeks of vacation, the concentration of o-cresol was significantly higher for the smokers than the non-smokers (0.14 vs 0.06 mmol/mol creatinine; P = 0.02). No smoking-associated difference was found for the urinary hippuric acid concentration. However, there was an association between alcohol consumption and hippuric acid excretion (P = 0.03); no such difference was shown for o-cresol. These results demonstrate that hippuric acid excretion is unsuitable for biological monitoring of toluene exposure when the exposure level is below 200 mg/m3. Also, in spite of the favourable excretion kinetics, the impact of smoking and the large interindividual variation warrant the same conclusion for o-cresol as a means of monitoring low level exposure in an individual worker.

Adult↗

PubMed1986

Ammoniagenesis catalyzed by hippurate-activated gamma-glutamyltransferase in the lumen of the proximal tubule. A microperfusion study in rat kidney in vivo.

gamma-Glutamyltransferase (gamma-GT) is located in the brushborder membrane of the proximal tubule where the catalytic site of the enzyme faces the lumen. The (phosphate-independent) glutaminase activity of gamma-GT in vitro is activated by hippurate. In order to investigate glutamine deamidation in the tubule lumen in vivo, 14C-L-glutamine-containing solutions were continuously microperfused through sections of the proximal convoluted tubule in vivo and in situ. D-aspartate and L-phenylalanine (10 mmol/l, each) were added to the perfusate in order keep the reabsorption of L-glutamine as such low and to block reabsorption of any glutamate possibly formed, respectively. Intraluminal formation of glutamate from glutamine in the absence of hippurate is small. In presence of 10 mmol/l hippurate, 5%-70% of the recovered 14C-activity was 14C-glutamate at an initial 14C-L-glutamine concentration of 1 mmol/l. The respective absolute rate (+/- SEM) of glutamate formation, i.e., 36 +/- 5 pmol X s-1 X m-1, was increased 1.4-fold at an initial L-glutamine concentration of 3 mmol/l, but dropped to one third at initially 0.3 mmol/l. A rough estimate of the apparent kinetic constants resulted in a Km of 0.58 (0.19-0.97) mmol/l and a Vmax of 56 (40-93) pmol X s-1 X m-1. Deamidation of glutamine occurred also in the absence of L-phenylalanine. Acivicin (AT 125), a gamma-GT inhibitor, completely blocked glutamate formation. Endogenous hippurate concentrations determined by free flow micropuncture and HPLC were 0.16 mmol/l in the late proximal convolution, 0.6 mmol/l in the early distal convolution, and 4.9 mmol/l in the final urine.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗

PubMed1993

Solubility, inhibited growth and dissolution kinetics of calcium oxalate crystals in solutions, containing hippuric acid.

An analysis of crystal growth and dissolution of slightly soluble salts in physiological solutions in the presence of complexing ions was carried out, simulating conditions typical in human urine. It was found that hippuric acid, a normal physiological constituent of urine, acts at increased concentrations as a dissolving agent with respect to calcium oxalate (CaOx) and CaOx calculi. The kinetics of dissolution of crystalline CaOx calculi in physiological solutions containing hippuric acid at different concentrations were studied, using the change in the Archimedean weight of samples immersed in the solution. Analysis of the experimental results enabled the determination of the increased solubility of CaOx in the presence of hippuric acid and the quantitative characterization of this substance as a new and promising agent for dissolving CaOx calculi in human urine. The possible effect of hippuric acid as a natural regulator of CaOx supersaturation and crystallization in human and mammalian urine is also discussed.

Calcium Oxalate↗

PubMed2001

Growth of the purple bacterium Rhodobacter capsulatus on the aromatic compound hippurate.

The purple nonsulfur bacterium Rhodobacter capsulatus strain B10 grew phototrophically on the aromatic compound hippurate (N-benzoyl-L-glycine) and related benzoyl amino acids. Absorption spectra, extraction, and GC/MS analysis of culture supernatants showed that hippurate was stoichiometrically converted to benzoate and glycine, with the latter used as a carbon or nitrogen source for growth. This conclusion was supported by detection of the enzyme hippuricase in permeabilized intact cells. Chemotrophic growth on hippurate by Rba. capsulatus, either at full or reduced oxygen tensions, was not observed. The type strain of Rhodobacter sphaeroides as well as four strains of Rhodopseudomonas palustris also grew phototrophically on hippurate, while several other aromatic-degrading species of purple bacteria did not.

Benzoates↗

PubMed2006

Human urine certified reference material CZ 6010: creatinine and toluene metabolites (hippuric acid and o-cresol) and a benzene metabolite (phenol).

A reference material for the biological monitoring of occupational exposure to toluene, benzene and phenol was prepared. O-cresol and hippuric acid (metabolites of toluene) are used for the biological monitoring of occupational exposure to toluene. Phenol, a metabolite of benzene, is used for the biological monitoring of exposure to benzene, but phenol can of course also be used as an indicator of exposure to phenol as well. The reference material (RM) used for the determination of these metabolites was prepared by freeze-drying pooled urine samples obtained from healthy persons occupationally exposed to toluene and those taking part in an inhalation experiment. Tests for homogeneity and stability were performed by determining urine concentrations of o-cresol, hippuric acid, creatinine and phenol. To investigate the stability of the RM, the urinary concentrations of o-cresol and phenol were monitored for eighteen months using GC and HPLC, while those of hippuric acid and creatinine were followed for five and six years, respectively, using HPLC. Analysis of variance showed that the concentrations did not change. The certified concentration values (and their uncertainties) of the substances in this reference material (phenol concentration c=6.46+/-0.58 mg l(-1); o-cresol concentration c=1.17+/-0.15 mg l(-1); hippuric acid concentration c=1328+/-30 mg l(-1); creatinine concentration c=0.82+/-0.10 g l(-1)) were evaluated via the interactive statistical programme IPECA.

Benzene↗

PubMed1987

Contributions of hippurate, indoxyl sulfate, and o-hydroxyhippurate to impaired ligand binding by plasma in azotemic humans.

We have evaluated pH, chloride, calcium and several endogenous aromatic acids as possible causes of the impaired binding of drugs by plasma albumin in renal failure. Changes in pH, chloride and calcium over the range found in renal failure had minimal or no effects on the binding of [14C]salicylate, a model probe which binds to both of the major drug-binding loci of human albumin. Hippurate and indoxyl sulfate were weak inhibitors of binding by normal plasma. Ortho-hydroxy-hippurate was undetectable or minimally elevated, except among patients with elevated plasma salicylate concentration. Although plasma hippurate and indoxyl sulfate concentrations were elevated markedly in patients with renal failure, inhibition of salicylate binding was significantly correlated only with the concentration of indoxyl sulfate. Addition of hippurate and indoxyl sulfate separately and together to normal plasma showed that these ligands could account for only 15% of the impaired binding of salicylate by azotemic plasma. The retained solutes which account for most of this binding defect remain to be identified. This uremic disorder (and perhaps others) is due not to a single chemical but to the additive effect of a family of chemicals.

Blood Proteins↗

PubMed1989

Determination of hippuric acid and furanic acid in serum of dialysis patients and control persons by high-performance liquid chromatography.

A high-performance liquid chromatographic method for the determination of 3-carboxy-4-methyl-5-propyl-2-furanpropionic acid (furanic acid) and hippuric acid in human serum is described. Quantitative data were obtained from 20 blood donors, 26 non-dialysis patients and 41 dialysis patients. In healthy persons hippuric acid ranged from 0.2 to 0.6 mg/dl, furanic acid from 0.13 to 0.53 mg/dl. In dialysis patients the mean concentration of hippuric acid was elevated to 17.2 mg/dl (range 1.7-50.8 mg/dl) and the mean concentration of furanic acid was elevated to 1.89 mg/dl (range 0.17-6.45 mg/dl). In patients without renal insufficiency the concentrations were not elevated. These data are in accordance with previous data obtained by gas chromatographic methods. Preliminary results indicate that hippuric acid and furanic acid may be more specific parameters than other uremic retention products, and better indicators for the need for dialysis treatment than urea or creatinine.

Chromatography, High Pressure Liquid↗

PubMed1999

Identification of hippurate-negative thermophilic campylobacters.

Twenty-eight thermophilic campylobacter isolates showing negative hippurate hydrolysis were further characterized. Using Campylobacter jejuni and coli specific primers for ceuE gene, five of the isolates with repeatedly negative results in rapid hippurate hydrolysis were positive in C. jejuni-specific polymerase chain reaction (PCR) and 13 isolates were shown to be C. coli. All except one isolate with positive results in C. jejuni PCR were negative in C. coli PCR including those with repeatedly negative hippurate hydrolysis results. One isolate was positive in both PCRs due to a mixed culture. In comparison with PCR, API Campy gave concordant results in only 20 of the 28 isolates tested. Hybridization with PCR probes for ceuE gene of known C. jejuni and coli strains confirmed PCR results in all 27 isolates tested. In contrast to hippurate hydrolysis, PCR seemed to be a more reliable method to identify C. coli.

Bacterial Proteins↗

PubMed2003

Detection of carboxylic acids and inhibition of hippuric acid formation in rats treated with 3-butene-1,2-diol, a major metabolite of 1,3-butadiene.

Epidemiological studies have indicated that 1,3-butadiene exposure is associated with an increased risk of leukemia. In human liver microsomes, 1,3-butadiene is rapidly oxidized to butadiene monoxide, which can then be hydrolyzed to 3-butene-1,2-diol (BDD). In this study, BDD and several potential metabolites were characterized in the urine of male B6C3F1 mice and Sprague-Dawley rats after BDD administration (i.p.). Rats given 1420 micromol kg(-1) BDD excreted significantly greater amounts of BDD relative to rats administered 710 micromol kg(-1) BDD. Rats administered 1420 or 2840 micromol kg(-1) BDD excreted significantly greater amounts of BDD per kilogram of body weight than mice given an equivalent dose. Trace amounts of 1-hydroxy-2-butanone and the carboxylic acid metabolites, crotonic acid, propionic acid, and 2-ketobutyric acid, were detected in mouse and rat urine after BDD administration. Because of the identification of the carboxylic acid metabolites and because of the known ability of carboxylic acids to conjugate coenzyme A, which is critical for hippuric acid formation, the effect of BDD treatment on hippuric acid concentrations was investigated. Rats given 1420 or 2272 micromol kg(-1) BDD had significantly elevated ratios of benzoic acid to hippuric acid in the urine after treatment compared with control urine. However, this effect was not observed in mice administered 1420 or 2840 micromol kg(-1) BDD. Collectively, the results demonstrate species differences in the urinary excretion of BDD and show that BDD administration in rats inhibits hippuric acid formation. The detection of 1-hydroxy-2-butanone and the carboxylic acids also provides insight regarding pathways of BDD metabolism in vivo.

Animals↗

PubMed1985

Comparison of four hippurate hydrolysis methods for identification of thermophilic Campylobacter spp.

The test for hippurate hydrolysis is critical for separation of Campylobacter jejuni and C. coli strains. Glycine and benzoic acid are formed when hippurate is hydrolyzed by C. jejuni. The test used in most laboratories is one of several variations of the ninhydrin tube test described by Hwang and Ederer (M. Hwang and G. M. Ederer, J. Clin. Microbiol. 1:114-115, 1975) for detection of glycine. We evaluated three modifications of the Hwang and Ederer method and the gas-liquid chromatographic (GLC) method described by Kodaka et al. (H. Kodaka, G. L. Lombard, and V. R. Dowell, Jr., J. Clin. Microbiol. 16:962-964, 1982) for detecting benzoic acid. Campylobacter strains comprised 22 C. jejuni, 11 C. coli, and 8 C. laridis strains. The species identification of each strain was confirmed by DNA relatedness. All strains of C. jejuni were positive and all strains of C. coli and C. laridis were negative by the GLC method for detecting hippurate hydrolysis, whereas three strains of C. jejuni gave negative or variable results in the tube tests. The GLC method is more sensitive than the tube methods for detecting hippurate hydrolysis and should be used on cultures yielding variable or questionable test results.

Bacteriological Techniques↗

PubMed1977

Evaluation of the rapid hippurate hydrolysis test with enterococcal group D streptococci.

The rapid hippurate hydrolysis test was evaluated with the conventional test, using 17 group A streptococci, 9 non-enterococcal group D streptococci, 108 enterococcal group D streptococci, and 2 strains of Listeria monocytogenes. There was complete correlation between the rapid and conventional tests with all organisms except enterococcal group D. The rapid hippurate hydrolysis method was more sensitive with the enterococci; 95.4% were positive with the rapid method, and 9.3% were positive with the conventional method. Thin-layer chromatography (TLC) was performed on all isolates to determine if the end product of hydrolysis, glycine, was indeed present. The TLC results were in agreement with the rapid and conventional methods for group A streptococci, nonenterococcal group D streptococci, and L. monocytogenes. TLC results were in total agreement with the rapid hippurate hydrolysis test for the enterococcal group D isolates, thus verifying the accuracy of this more sensitive test. Trace amounts of glycine were found in the substrate, indicating the need for including an uninoculated substrate control as well as stock strains of group A and B beta-hemolytic streptococci (negative and positive controls, respectively) each time the rapid hippurate hydrolysis test is performed.

Amidohydrolases↗

PubMed1977

Quantitative determination of hippuric and m-methylhippuric acids in urine by high-speed liquid chromatography.

High-speed liquid chromatography employing an ultraviolet photometric detector has been applied to the simultaneous determination of hippuric and m-methylhippuric acids in urine. Reversed-phase partition chromatography is carried out on a muBondapak C18 column with methanol-water as the eluent system. This method obviates the necessity for isolation or reaction of these acids before assay. The only pretreatment necessary is extraction of sample with ethyl acetate. A linear relationship is obtained between the peak heights and the hippuric or m-methylhippuric acid concentrations. Mean recovery of hippuric and m-methylhippuric acids in urine is 99.8% and 99.3% respectively. The determination of hippuric acid by this method gives lower concentrations in normal urine than does the colorimetric method of Umberger and Fiorese (1963).

Chromatography, High Pressure Liquid↗

PubMed1978

Urinary hippuric acid concentration after occupational exposure to toluene.

The results of industrial investigations have shown a correlation between the rate of hippuric acid excretion in a single urine sample collected after daily occupational exposure and the amount of toluene absorbed. The rate of hippuric acid excretion and the average concentration of toluene vapour during exposure time were also related. The quantitative range of the test has been limited to amounts exceeding 425 mg of toluene and concentrations exceeding 69 ppm of toluene in the air because of the physiological presence of hippuric acid in urine. The rate of hippuric acid excretion in urine depends on diuresis and is constant for urinary fractions with diuresis of 30 ml/h. The physiological excretion rate was 20 mg/h with a standard deviation +/- 4.3 mg/h, maximal physiological level 33 mg/h.

Diuresis↗

PubMed1982

TLC separation of hippuric, mandelic, and phenylglyoxylic acids from urine after mixed exposure to toluene and styrene.

A method using thin-layer chromatography is described to determine the concentration of hippuric acid, mandelic acid, and phenylglyoxylic acid present in the urine after occupational mixed exposure to toluene and styrene. These substances are known metabolites of toluene and styrene, and therefore the evaluation to mixed exposure to toluene and styrene may be carried out separating these metabolites beforehand. Procedures are proposed to separate the metabolites as follows: (1) separation of hippuric acid from mandelic acid, (2) separation of mandelic acid from phenylglyoxylic acid, and (3) separation of hippuric acid and mandelic acid from phenylglyoxylic acid. The developing reagent p-dimethylaminobenzaldehyde in acetic acid anhydride was used after separation on Kieselgel and Silicagel. The sensitivity of the method was 6 microgram of hippuric acid, 10 microgram of mandelic acid, and 7 microgram of phenylglyoxylic acid with an average recovery of 94%.

Chromatography, Thin Layer↗

PubMed1987

Plasma hippurate in renal failure: high-performance liquid chromatography method and clinical application.

We have developed a high-performance liquid chromatography (HPLC) method for assay of hippurate in plasma of patients with renal failure. Hippurate accounts, in part, for the impaired binding of drugs and metabolites to albumin and may cause other disorders in azotemic patients. The method is precise, accurate and reproducible. Among 25 patients with acute and chronic renal failure having serum creatinine in the range of 2.9-43 mg/dl (256-3,801 mumol/l), plasma hippurate ranged from 0.11 to 16.2 mg/dl (6.1-904 mumol/l). Hippurate concentration correlated moderately closely with plasma creatinine, urea and anion gap. Its curvilinear relation to the reciprocal of serum creatinine indicated a proportional decline of GFR and tubular function or the accumulation of inhibitors of the proximal tubular anion secretory pathway. The method should be useful for further studies of abnormal albumin binding as well as other disorders in azotemic patients.

Acid-Base Equilibrium↗