Assessment of renal toxicity by urinary enzymes in patients receiving chemotherapy with 8-methyl-8-acetylenic-putrescine

Renal toxicity was assessed in 19 patients receiving methyl acetylenic putrescine (MAP), an irreversible inhibitor of ornithine decarboxylase. Patients received 250 mg t.d.s. for up to 13 weeks. This dose effectively inhibited the target enzyme, as shown by elevations in decarboxylated S-adenosyl methionine levels. No significant nephrotoxicity was observed in these patients as determined by plasma urea, creatinine and creatinine clearance measurements, although minor elevations of the urinary enzymes lactate dehydrogenase, N-acetyl-beta-glucosaminidase, alkaline phosphatase and alanine aminopeptidase were observed. As this could represent sub-clinical renal damage, caution should be exercised when using MAP in combination with other cytotoxic drugs.

Age-dependent excretion of alanine aminopeptidase, alkaline phosphatase, gamma-glutamyltransferase and N-acetyl-beta-D-glucosaminidase in human urine

Urinary excretion of alanine aminopeptidase, alkaline phosphatase, gamma-glutamyltransferase and N-acetyl-beta-D-glucosaminidase was determined in gel-filtered samples of morning random urine specimens of 442 subjects of various ages (5 days to 58 years). Enzyme excretion related to urinary creatinine (enzyme/creatinine ratio; U/mmol creatinine) significantly decreased with increasing age. Sex-related differences of some enzyme excretions were found in age groups over 6 years. From these investigations, we calculated upper reference intervals (97.5 percentiles) for 5 age-dependent groups of children and adolescents and for one group of adults.

[Evaluation of the liberation of urinary necrosis enzymes (NAG-AAP) after administration of plasma expanders: study of dextran 40, hydroxyethyl starch and polymerized gelatin]

We studied the 24-hour urinary elimination of enzymatic markers of renal tubular necrosis (NAG-AAP) in 21 patients (mean age 34.6 years old) who were treated with plasma expanders before peridural anesthesia. The patients were divided into three groups of seven subjects each: - 14 ml/Kg -1 of dextran 40 was administered to group 1 - 14 ml/Kg -1 of gelatin was administered to group 2 - 14 ml/Kg -1 of hydroxyethyl starch was administered to group 3. Urinary elimination of N-acetylglucosaminidase and of alanine aminopeptidase was determined in the 24-hour urine the day before surgery (controls), the day of surgery (G1) and the day after surgery (G2). The values of the samples, taken after plasma expander administration, did differ significantly from the control values (G1, G2). Therefore the administration of 14 ml/Kg -1 of dextran, gelatin or hydroxyethyl starch does not affect the renal tubular epithelium.

[Therapeutic effects and influence on the urinary enzyme activity of human urinary trypsin inhibitor (urinastatin) in cases with acute renal failure--changes in the urinary activities of NAG and AAP]

We studied the therapeutic effects of human urinary trypsin inhibitor (UTI) in 5 cases with acute renal failure, resulting from traumatic shock in 1 case, post-operative shock in 2 cases, septic shock in 1 case, and dehydration in 1 case. We administered 300,000 u/day of UTI intravenously at the initial phase of acute renal failure for 7 days. We measured the activities of urinary N-acetyl-beta-D-glucosaminidase (NAG), alanine aminopeptidase (AAP) and the activities of serum beta-glucuronidase, PMN-elastase serially. As a control, we also studied same markers in 5 cases with acute renal failure without the administration of UTI. We could obtain the following results. 1) Urinary activities of NAG and AAP were already elevated markedly at the onset phase of acute renal failure. 2) The administration of UTI caused a significant decrease of the activities of NAG and AAP in the urine as compared with those in the controls. 3) The administration of UTI caused also the significant suppression of the activities of beta-glucuronidase and PMN-elastase in the serum. These results suggested that UTI has the protective effects on the tubular epithelial cell injuries in cases of acute renal failure.

[Value of enzymuria during antibacterial therapy]

Enzymuria is a well known parameter of evaluation of drugs nephrotoxicity, particularly of antibiotics. Alanine aminopeptidase (AAP), gamma-glutamyltransferase (GGT) and N-acetyl-bêta-D-glucosaminidase activities were measured in native urine. This study included 19 patients treated by an association of netilmicin-vancomycin. Enzymuria was measured on 24 hours urines at J0 then every two days during treatment. Enzymuria increased 24 or 48 hours after the beginning of the treatment. The Principal Components Analysis (PCA) of the results of enzymuria, seric urea and creatininemia shows the presence of two groups of responses. The first principal component exhibits two populations: the patients with pathological seric urea and pathological seric creatinine and the others. The PCA does not allow this discrimination using only the results of enzymuria; in contrast, with these results, the patients may be classified by the PCA on the basis of treatment duration. The enzymuria allows the clear identification of nephrotoxic drugs but does not allow the prediction of renal injury or of its aggravation.

[Prevention of cisplatin induced nephrotoxicity by administering urinastatin to rabbits--comparison with other protease inhibitors]

The present study was performed to evaluate the mechanism of the protective effect of urinastatin (US) against cisplatin (CDDP) induced nephrotoxicity. We measured consecutively the change in the creatinine clearance (Ccr) level, urinary arylamidase (AA) activity, and urinary gamma-glutamyl transpeptidase (gamma-GTP) activity as the indices of nephrotoxicity. These drugs such as US (10,000 U/kg, 3h: group 1), gabexate mesilate (2mg/kg/h, 4h: group 2), and aprotinin (5,000 U/kg/h, 4h: group 3) as protease inhibitors, and dopamine HCl (0.3mg/kg/h, 4h: group 4) for the increase in renal blood flow were used with the hydration of 15 ml/kg/h during 4 hours of experiments on rabbits. The change in the Ccr value after the intravenous administration of CDDP indicated that the level in groups 3, 4 decreased significantly at one day after the administration of CDDP. On the other hand, there was little significant increase in urinary AA activity and/or urinary gamma-GTP activity in group 1, while a transitional increase was observed in groups 2, 3, and 4, among which the highest level was found in group 4. These results are attributed to the protective action of US against CDDP mainly in the inhibition of the lysosomal enzyme released by the destruction of lysosomes in the proximal tubule cells of the kidney.

Circadian variations and reference intervals for some enzymes in urine of healthy children

Circadian variations of alanine aminopeptidase (EC 3.4.11.2), gamma-glutamyltransferase (EC 2.3.2.2), and N-acetyl-beta-glucosaminidase (EC 3.2.1.30) in urine were studied in 10 healthy children, ages six to 15 years. Urine specimens were collected during 24 h, grouped into four time intervals. Enzymes were measured spectrophotometrically, with automation. These enzymes all showed diurnal variation, with morning (8 a.m.-12 noon) excretion being highest. We also analyzed timed urinary specimens (8 a.m.-12 noon) from 136 healthy children, ages two to 11 years. Reference intervals are presented for these enzymes. High excretion of the three enzymes was observed in children two and three years old.

Clinical significance of urinary N-acetyl-beta-D-glucosaminidase and alanine aminopeptidase

The excretion of urinary N-acetyl-beta-D-glucosaminidase (NAG) and Alanine Aminopeptidase (AAP) increases with renal damage. The variation in enzyme activity due to the fluctuation of urine flow rate could almost be eliminated by expressing it as the ratio of enzyme activity to urinary creatinine concentration. The urinary enzyme activities increased not only by tubular damage but also by the reduced creatinine clearance due to glomerular injury. The normal reference values of NAG were 2.84 +/- 2.50U/g creatinine for 24-hour urine and 3.23 +/- 2.76U/g creatinine for random urine. The normal reference values of AAP were 9.71 +/- 6.68U/g creatinine for both 24-hour urine and random urine. Although 128 patients were with abnormal enzymuria, only 39.1%, 52.3%, 83.6%, and 86.7% of the patients were with abnormal serum creatinine, serum urea N, creatinine clearance, and urine protein, respectively. In view of the sensitivity, the determinations of urinary NAG and AAP are suitable for early detection of renal diseases.

[Clinical investigation of urinary activity of NAG and AAP in patients with various types of primary glomerulonephritis]

We investigated the activity of NAG and AAP in the urine of 36 patients with chronic glomerulonephritis (GN) with special reference to the relation between the levels of the enzymes and histopathological changes of the kidney. The subjects consist of 7 cases of minimal change nephrotic syndrome (MCNS), 3 cases of membranous GN, 5 cases of IgA. GN, 5 cases of membranoproliferative GN, 3 cases of focal glomerulosclerosis and 12 cases of chronic renal failure who had creatinine levels of more than 2 mg/dl resulting from chronic GN. Urinary levels of NAG and AAP were significantly higher in cases with GN than those in cases with chronic renal failure. In cases with GN, urinary levels of NAG and AAP correlated with the amounts of urinary protein, while those levels had no correlation with the classification of histopathological changes of glomeruli. The high value of NAG/mg.protein ratio, NAG by urinary protein, might be explained by the degree of tublointerstitial damage. We concluded that urinary levels of NAG and AAP reflects the proximal tubular damage caused by protein reabsorption.

[Urinary enzymes: early biochemical indicators in the biological monitoring study of subjects exposed to styrene]

This paper studies the urinary enzymes N-acetyl-beta-glucosaminidase (NAG) and alanine aminopeptidase (AAP) in workers exposed to styrene. It is possible to consider these enzymes as early biochemical indicators of renal damage, owing to their ability to show alterations in the renal tubule when the creatinine clearance is still in the normal range. This preliminary study shows an increase in the two enzymes in workers exposed to styrene.

[Kidney tubule dysfunction caused by acetic acid]

Two patients admitted after ingestion of 80% acetic acid are described. Only the first patient developed haemolysis, slight intravascular coagulation and oliguric kidney insufficiency. They were treated with a nasogastric tube and total parenteral feeding. During the first week after admission urinary excretion of beta 2-microglobulin, alanine-aminopeptidase and N-acetyl-glucosaminidase was significantly increased. The patients remained haemodynamically stable and did not develop fever. The above-mentioned elevated excretions returned to normal levels. Both patients showed similar patterns of tubular proteinuria. The observations in the second patient suggest a direct toxic effect of acetic acid on the proximal tubule of the kidney.

[Preventive effect of urinastatin on cisplatin induced nephrotoxicity in rabbits]

The effect of urinastatin (US) on the prevention of cis-diamminedichloroplatinum (CDDP) induced nephrotoxicity was examined in experiments on rabbits. They were divided into seven groups and treated intravenously as follows: Group 1; intravenous injection of CDDP 3mg/kg only, Group 2; 3% sodium chloride (15ml/kg/h, 1h) + CDDP, Group 3; 3% sodium chloride + CDDP + US (10,000U/kg), Group 4; Hydration A (350ml/body) + 3% sodium chloride + CDDP, Group 5; Hydration A + 3% sodium chloride + CDDP + US, Group 6; Hydration B (200ml/body) + 3% sodium chloride + CDDP, Group 7; Hydration B + 3% sodium chloride + CDDP + US. Creatinine clearance (Ccr) value, arylamidase (AA) activity in urine and gamma-glutamyltranspeptidase (gamma-GTP) activity in urine were consecutively measured as indices of nephrotoxicity. Ccr values in groups 1-3 significantly decreased markedly whereas those in groups 4-7 did not. The change in AA activity and gamma-GTP activity in urine suggests that no nephrotoxicity occurred in groups 5 and 7. Consequently, this experiment indicated that nephrotoxicity was prevented when CDDP was administered in 200mg/body hydration with both 3% sodium chloride and US. The recommended dose of US seems to be a 2,000U/kg intravenous injection before CDDP administration, followed by 8,000U/kg intravenous drip infusion for 2 hours after CDDP administration.

Chronic renal tubular effects in relation to urine cadmium levels

In this study the urine activities of two brush border membrane enzymes, alanine aminopeptidase (AAP) and gamma-glutamyltranspeptidase (GGT), and the lysosomal enzyme N-acetyl-beta-D-glucosaminidase (NAG) were measured in men exposed to cadmium to investigate chronic renal toxicity. The subjects consist of a group with urine cadmium levels less than 2.0 micrograms/l and a group with higher cadmium levels (urine cadmium greater than or equal to 2.0 micrograms/l) with past or present occupational exposure to cadmium. The mean NAG value corrected for creatinine in the higher cadmium group (2.95 U/g creatinine) is significantly different from the mean low cadmium group value (0.92 U/g creatinine, p = 0.0083). Likewise, AAP in the higher group (13.83 U/g creatinine) is significantly different from that of the low group (6.58 U/g creatinine; p = 0.0018). NAG and AAP also give significant correlations with cadmium levels in urine (NAG: r = 0.51; p = 0.0001; AAP: r = 0.56; p = 0.0001). There is no similar statistically significant difference in GGT means in the two groups. In contrast to cadmium correlations, blood lead does not correlate with NAG, AAP, or GGT. A dose-response relationship was found between NAG and cadmium and between AAP and cadmium. The analysis of this relationship gives estimates of a 10% chance of observing an elevated NAG value at a cadmium level of 6.3 micrograms/g creatinine (8.0 micrograms/l) and a 10% chance of observing an elevated AAP at a cadmium level of 5.0 micrograms/g creatinine (3.4 micrograms/l). These data indicate elevations of NAG and AAP at urine cadmium levels below the level of 10 micrograms/g creatinine recommended as an upper limit by the 1980 World Health Organization Study Group. Since elevated levels of NAG and AAP in cadmium-exposed workers may reflect chronic renal tubular nephrotoxicity, these findings indicate that cadmium levels below 10 micrograms/g creatinine may be accompanied by subclinical tubular dysfunction, and that WHO guidelines should be interpreted cautiously, particularly with reference to workers who are no longer exposed and may have had higher cadmium body burdens in the past.

Urinary excretion of N-acetyl-beta-D-glucosaminidase and alanine aminopeptidase during pregnancy

The assay of enzyme activity in urine seems a reliable and safe method to monitor different kidney diseases. However, its use in pregnant patients might be limited by the modifications of kidney function during pregnancy. The aim of the present study was to evaluate the trend of excretion of the lysosomal enzyme N-acetyl-beta-D-glucosaminidase (NAG) and the brush border enzyme alanine aminopeptidase (AAP) during uncomplicated pregnancies. NAG excretion showed a significant increase (P less than 0.001) throughout pregnancy, while no significant modification of AAP levels was demonstrated. These data support the hypothesis that the two enzymes are excreted into the urine through different mechanisms and might constitute markers for different pathological events. As the increase of NAG excretion may be related to the kidney functional adaptation to pregnancy, different cut-off limits must be established in this period.

Tubular nephrotoxicity during long-term ifosfamide and mesna therapy

The nephrotoxic effects of ifosfamide were assessed in 18 children and adolescents given cumulative doses of 32-112 g/m2 (1.6 g/m2 per day in sequential 5-day courses) with the uroprotectant mesna (1.2 g/m2 per day). Tubular nephrotoxicity was evaluated by measuring the urinary concentrations of N-acetyl-beta-D-glucosaminidase (NAG), alanine aminopeptidase (AAP), and total protein before and during sequential courses of therapy. Of 15 patients who had normal levels of tubular markers before ifosfamide therapy, only 1 developed a persistent increase in baseline values of the three tubular markers with the sixth course of ifosfamide. Although transient increases in the excretion of these markers were observed during each 5-day course of ifosfamide, the magnitude did not increase over sequential courses in these 15 patients. Of the remaining three patients who had increased NAG levels before ifosfamide therapy, two showed a progressive increase in enzymuria and proteinuria, and serum creatinine concentrations increased in a single patient who had obstructive uropathy. Our data suggest that children with normal renal function can be given large cumulative amounts of ifosfamide in fractionated doses with little risk of progressive clinical nephrotoxicity.

Monitoring serum aminoglycoside concentrations in children with amphotericin B nephrotoxicity

We prospectively studied the effect of amphotericin B therapy on aminoglycoside clearance in 20 consecutive children during the remission-induction phase of chemotherapy for acute myelocytic leukemia. Increases (greater than 50%) in the half-life for aminoglycoside excretion were not associated with antileukemic or aminoglycoside therapy alone but occurred in 12 of 17 children when amphotericin B was added to the antimicrobial regimen. Seven children had impaired aminoglycoside clearance without increases (greater than 50%) in serum creatinine; hence the resulting adjustments in aminoglycoside dosage would not have been made had we relied solely on serial measurements of serum creatinine. Evidence for increased excretion of the renal enzymes N-acetyl-beta-D-glucosaminidase and alanine aminopeptidase during amphotericin B therapy suggested that damage to proximal tubular cells may contribute to the renal impairment that has been associated with this drug. Our findings underscore the value of monitoring serum aminoglycoside concentrations in children being treated with amphotericin B.

Recommendation for the measurement of "alanine aminopeptidase" in urine

A method is recommended for the measurement of the catalytic concentration of alanine aminopeptidase in the urine of man, rat, and dog, using L-alanine-4-nitroanilide as substrate. In currently used methods, substrate concentrations between 1.7 and 2.0 mmol/l are used. Kinetic experiments show, however, that the reaction is inhibited by substrate concentrations exceeding 0.8 (man), 0.3 (rat) and 0.5 mmol/l (dog); these concentrations lie in the range of the Km values. Assay conditions were therefore chosen to give the lowest possible Km. The Km value depends on the type of buffer, and it increases with pH and temperature. The recommended assay conditions are: triethanolamine buffer 70 mmol/l, pH 7.6; L-alanine-4-nitroanilide concentrations depending on the species; incubation temperature 25 degrees C.

Renal tolerance of fleroxacin in healthy volunteers

In order to evaluate kidney tolerance of fleroxacin, a new fluoroquinolone, we performed a volunteer study with 16 healthy males, 20-27 years old. On three consecutive days 800 mg of fleroxacin was administered orally. Alanine-aminopeptidase and distal- and pan-tubular antigens were determined in 24 h urine collections with specific monoclonal antibodies. Routine haematological and biochemical parameters were determined daily and were in the normal range during the follow-up. No significant changes in excretion of alanine-aminopeptidase and of the urinary antigens were observed during the three days of fleroxacin administration and on the following three days. The results obtained in this volunteer study indicate that fleroxacin has no nephrotoxic side effects.

Urinary alanine-aminopeptidase (AAP) excretion in patients with urinary tract infection treated with ceftazidime (CAZ) or cefotaxime (CTX) plus tobramycin (TOB)

It is well known that some antibiotics are particularly nephrotoxic. In the present study we investigated kidney function and AAP excretion (as an index of nephrotoxicity) in patients with urinary tract infection treated with CAZ or CTX plus TOB. The main cause of infection was E. coli in both treated groups. After 10 days of treatment similar beneficial effects were stated in both groups. At the end of treatment urinary AAP excretion in both groups was higher than before treatment. Despite a significant increase in urinary AAP in only one patient of each group, the serum creatinine level rose by more than 45 mumol/l. Monitoring of urinary AAP may be useful in early detection of nephrotoxicity caused by antibiotics.

Noninvasive renal diagnostic studies

Traditional methods of noninvasively evaluating patients for renal injury do not accomplish the following tasks: reliably distinguish potentially treatable forms of acute renal failure from acute tubular necrosis; provide a sensitive indicator of early allograft rejection in renal transplant recipients, particularly those in the pediatric age group; provide an early warning of incipient drug-induced nephrotoxicity; or serve as an adequate screening test for renal injury due to exposure to occupational or environmental toxins, especially heavy metals. Because of this, considerable effort has been devoted to the development of assays to satisfy these needs. Three approaches include measurement in the urine of low-molecular-weight plasma proteins such as beta 2-microglobulin; a variety of kidney-derived enzymes, such as L-alanine aminopeptidase and N-acetyl-beta-D-glucosaminidase; and specific renal antigens using immunologic detection. The first two of these have not proved to be adequately sensitive or specific, complicated by the frequent loss of activity associated with the physicochemical characteristics of the urine or the presence of pyuria. Despite this, useful information has been obtained. In particular, assays of beta 2-microglobulin urinary excretion and retinol binding protein appear to have clinical utility that should be pursued. Recent experience with a monoclonal antibody-based assay for a unique proximal tubular antigen, the adenosine deaminase binding protein, suggests that a battery of such assays, each directed against an antigen localized to a particular segment of the nephron, may be particularly useful.

The increase in urinary alanine aminopeptidase excretion associated with enflurane anesthesia is increased further by aminoglycosides

Urinary excretion of alanine aminopeptidase (AAP) is an extremely sensitive indicator of drug-induced renal tubular damage. The urinary excretion of AAP was determined in patients after enflurane anesthesia with or without concurrent aminoglycoside administration to determine if enflurane enhances the nephrotoxic potential of aminoglycosides. Twenty-two patients with normal renal function were studied. Ten received enflurane alone, eight received enflurane plus gentamicin or tobramycin, and four patients who underwent nitrous oxide and narcotic anesthesia were the control group. Preoperative values ranged from 1010 to 2461 microU/24 hour. Urinary AAP excretion increased significantly in both enflurane groups 2 days postoperatively (P less than 0.025). Patients who received both enflurane and aminoglycosides had significantly greater urinary AAP excretion on postoperative day 2 than did patients given enflurane alone: 21,342 +/- 4074 microU/24 hour and 6336 +/- 1496 microU/24 hour, respectively (mean +/- SEM, P less than 0.005). There was no change in AAP excretion in the control group compared to baseline; on day 3 AAP was 1412 +/- 710 microU/24 hour. No changes in blood urea nitrogen or serum creatinine levels were observed. These data suggest that enflurane increases the renal tubular effects of aminoglycosides, possibly increasing the risk of aminoglycoside renal toxicity.