Enzymuria in non-insulin-dependent diabetic patients: signs of tubular cell dysfunction

1. To evaluate tubular damage in diabetic patients, we measured the 24 h urinary excretion of five enzymes (N-acetyl-beta-D-glucosaminidase, gamma-glutamyl transpeptidase, dipeptidyl aminopeptidase IV, alanine aminopeptidase and alkaline phosphatase) that originate in renal proximal tubular cells. 2. Studies were performed on 118 non-insulin-dependent diabetic patients, 59 non-diabetic patients with chronic renal disease and 47 normal control subjects. First, the correlation between renal function, glycaemic control and urinary enzyme excretion was investigated. Secondly, the subjects were treated by controlled diet therapy to assess the effects of better glycaemic control on urinary enzyme excretion. 3. Regardless of a diabetic or non-diabetic cause of renal dysfunction, all of the five enzymes showed abnormal urinary excretion in patients with renal insufficiency (serum creatinine concentration > 2.0 mg/dl). In diabetic patients, however, an increase in N-acetyl-beta-D-glucosaminidase excretion and a decrease in gamma-glutamyl transpeptidase excretion were noted even in those who had no signs of renal dysfunction, including microalbuminuria. Moreover, the excretion of these two enzymes had a higher degree of correlation with glycaemic control and renal function than did that of the other three enzymes. Multiple regression analysis revealed that excretion of N-acetyl-beta-D-glucosaminidase is best correlated with urinary protein (r2 = 0.35), whereas excretion of gamma-glutamyl transpeptidase is closely associated with glomerular filtration rate (r2 = 0.33). 4. In diabetic patients, diet therapy improved glycaemic control but had no effects on renal function, microalbumin excretion and beta 2-microglobulin excretion.(ABSTRACT TRUNCATED AT 250 WORDS)

[Comparative study on urinary parameters reflecting renal damage during chemotherapy for urological cancer]

We analyzed the excretion of the three urinary enzymes, N-acetyl-beta-D-glucosaminidase (NAG), alanine aminopeptidase (AAP), and glycyl-prolyl dipeptidyl aminopeptidase (GP-DAP) and the three urinary proteins, beta-microglobulin (beta 2-M), alpha-microglobulin (alpha 1-M), and albumin during the intravenous administration of anti cancer drugs in 4 prostatic cancer patients and 16 urothelial cancer patients. The patients with prostatic cancer were treated with VIP (vincristine, ifosfamide, peplomycin) chemotherapy and the patients with urothelial cancer were treated with MP (methotrexate, cisplatinum) or MEP (methotrexate, Etoposide, cisplatinum) combination chemotherapy. beta 2-M was the best parameter for drug-induced renal damage because of its sharp and large reactivities. Any urinary enzyme or protein especially albumin which had showed a markedly high value before the chemotherapy was not suitable as a urinary drug-induced renal damage parameter. There was a close resemblance in reactivity pattern between GP-DAP and AAP probably because of the same localization of these enzymes in the renal tubular bruch borders. In the patients with renal damage by chemotherapy, all parameters were changed showing two peaks or persisted with high values.

A comparative study of enzymuria, in the rat, of the drug combinations amikacin/vancomycin and amikacin/teicoplanin

The aim of this study was to compare nephrotoxicity of the combinations amikacin/vancomycin and amikacin/teicoplanin. Eighteen male Wistar rats were divided into 3 groups of 6 animals each. The first group received 50 mg.kg-1 of amikacin (i.m. route) and 100 mg.kg-1 of vancomycin (i.p. route). The second group received 50 mg.kg-1 of amikacin (i.m. route) and 40 mg.kg-1 of teicoplanin (i.p. route). The third group received an isotonic solution of sodium chloride. The antibiotics were injected for a period of 6 days. Urine samples of animals were taken 24 h before the beginning of the experiment, then every day, throughout the duration of the treatment (6 days), continuing for an additional 3 days following completion of the administration of the drugs. There were no significant modifications in the urinary excretions of alanine aminopeptidase and the creatinine between the 3 groups; but in the group receiving amikacin/teicoplanin, we observed between days 3 and 8 an increase in the excretion of N-acetyl-beta-D- glucosaminidase when compared to the group receiving amikacin/vancomycin (p < or = 0.05) and to the control group (p < or = 0.01).

Urinary excretion of three specific renal tubular enzymes in patients treated with nonsteroidal anti-inflammatory drugs (NSAID)

Ten patients, mean age 51.50 +/- 3.03 years, with degenerative rheumatism on NSAID treatment without any sign of renal disease, and 11 control subjects, mean age 43.50 +/- 1.51 years, were studied. NSAID treatment was of 11.30 +/- 5.60 weeks duration in average, with ibuprofen, naproxen, or indomethacin. Urinary excretion of three specific renal tubular enzymes--AAP: alanine-amino-peptidase, GGT: gamma-glutamyl-transpeptidase, and beta-NAG: beta-N-acetyl-glucosaminidase, were determined in 8-h overnight urine samples, as well as GFR creatinine clearance/1.73 m2, urinary volume/8 h, specific gravity of the urine, proteinuria and glucosuria. In the group treated with NSAIDs, urinary excretion of the enzymes was significantly higher than in the control group--AAP: 1414.20 +/- 317.60, 864.20 +/- 94.42, p < 0.00001; GGT: 8034.6 +/- 1378.55, 5095.64 +/- 614.40, p < 0.00001, and beta-NAG: 1644.60 +/- 299.97, 964.82 +/- 142.00, p < 0.00001. Patients on NSAID treatment showed abnormal urinary excretion of AAP in 7/10 cases, of GGT in 6/10, and of beta-NAG in 7/10 cases. Duration of the treatment did not correlate with the urinary excretion of the enzymes. Age was in correlation with the urinary excretion of the enzymes only in the control group, r = 0.52, p < 0.005 for AAP, r = -0.43, p < 0.02 for GGT, and r = -0.23, p < 0.05 for beta-NAG.(ABSTRACT TRUNCATED AT 250 WORDS)

Urinary trehalase activity in chronic glomerulonephritis

To determine the diagnostic role of urinary trehalase in chronic glomerular disease, urinary trehalase activity and other urinary markers such as N-acetyl-beta-D-glucosaminidase (NAG), alanine aminopeptidase (AAP), alkaline phosphatase (ALP), gamma-glutamyltranspeptidase (gamma-GTP), lactate dehydrogenase (LDH), lysozyme and beta 2-microglobulin (BMG) were measured in patients with chronic glomerulonephritis, nephrotic syndrome and chronic renal failure. Urinary trehalase activity was significantly increased in chronic glomerular disease, especially nephrotic syndrome, as compared with that in the healthy subjects. The highest incidence of elevated excretion was observed for trehalase with 52% in chronic glomerular disease, followed by NAG. Urinary trehalase activities in the patients were significantly correlated with the urinary levels of protein, NAG and AAP and total score of tubular damage, but not correlated with urinary levels of BMG or lysozyme. In patients with chronic glomerulonephritis and nephrotic syndrome, there was no significant difference in urinary trehalase activities between with and without hematuria. These results indicate that in some patients with chronic glomerular disease, there is tubular involvement as substantiated by elevation of the other urinary enzymes and BMG. Urinary trehalase is elevated more often in these types of disease than other markers of tubular damage.

Proteinuria and Enzymuria in Vesicoureteric Reflux

Vesicoureteric reflux is a common abnormality of the urinary tract leading to significant renal morbidity and premature mortality. No reliable non-invasive method exists for its diagnosis. This study investigated the presence of urinary proteins and enzymes in healthy children and those with reflux. A log normal distribution was found for all analyte/creatinine ratios. Significantly higher tubular protein/creatinine ratios were found in patients with reflux nephropathy. Three enzyme/creatinine ratios (n-acetyl-B-D-glucosaminidase, gamma-glutamyl transferase and lactate dehydrogenase) were higher in children with reflux who had no renal scarring, but the degree of overlap with the normal range was such that it is doubtful whether any will be of use as a urinary marker.

Renal tubular enzyme effects of clarithromycin in comparison with gentamicin and placebo in volunteers

This study assessed the potential nephrotoxicity of clarithromycin in comparison with gentamicin and placebo. Increased urinary excretion of alanine aminopeptidase (AAP) and N-acetyl-beta-D-glucosaminidase (NAG) served as markers of renal tubular injury. The study utilised a multiple-dose, double-blind, randomised, parallel group design. 14 healthy male subjects received 1 of 3 treatment regimens: (a) clarithromycin 500 mg orally every 12h for 13 doses and intravenous placebo every 8h (n = 5); (b) oral placebo every 12h and intravenous placebo every 8h (n = 4); and (c) intravenous gentamicin 1.7 mg/kg every 8h for 19 doses and oral placebo every 12h (n = 5). 24h urine collections were obtained daily for determinations of AAP and NAG activities. Gentamicin produced statistically significant increases (p less than 0.0001) in AAP and NAG excretion, with increases as early as the first and second day of dosing. Clarithromycin, when compared with placebo, did not produce significant elevations in AAP or NAG activity. On the basis of these data, it is unlikely that usual doses of clarithromycin have significant potential for causing nephrotoxicity.

Biochemical and immunological properties of urinary angiotensinase A and dipeptidylaminopeptidase IV. Their use as markers in patients with renal cell injury

Dipeptidyl peptidase IV (EC 3.4.14.5) and angiotensinase A (EC 4.4.11.7) were purified to homogeneity from pooled urine concentrate of patients with renal damage, using ultrafiltration, ammonium sulphate precipitation, lectin affinity chromatography, FPLC-ion-exchange(Mono-Q-)chromatography, and FPLC-gel filtration (Superdex). Based on the specific enzyme activity of the starting material, dipeptidyl peptidase IV was enriched 1629 fold, angiotensinase A 1183 fold. The relative molecular masses, Michaelis constants and isoelectric points were determined. Negative staining of the purified enzymes revealed globular proteins (5-7 nm). Antisera raised against dipeptidyl peptidase IV and angiotensinase A reacted specifically with tubular and, in the case of anti-angiotensinase A sera, with tubular and glomerular structures. In addition, urinary membrane vesicles of proximal tubule origin were eluted with the void volume (Superdex-gel filtration), indicating heavy epithelial cell disintegration. Both soluble tissue enzymes (dipeptidyl peptidase IV, angiotensinase A) and vacuolar blebs shed from epithelia contribute to proteinuria, as was shown in patients with glomerulonephritis, interstitial nephritis, diabetic nephropathy and, for angiotensinase A, in patients with essential arterial hypertension.

More on Effects of Storage Time and Temperature on Urinary Enzymes: A 1-Year Study

Results of our conclusive study on urinary enzyme stability during sample storage are reported. We measured alanine aminopeptidase (AAP) and N-acetyl-beta-D-glucosaminidase (NAG) in morning urines from 9 healthy normal subjects immediately after collection and throughout a 1-year storage at -70 and -20 degrees C. AAP proved to be quite stable at -70 degrees C (99.2% of the basal value at the end of the year). NAG is partially preserved (84.1% of the basal value) at -70 degrees C, but significantly decreased (50.4%) at -20 degrees C.

Chrononephrotoxicity in Rat of a Vancomycin and Gentamicin Combination

The effect of time of administration on excretion of two brush border enzymes--alanine aminopeptidase (AAP) and gamma-glutamyl transferase (gamma GT), and a lysosomal enzyme, N-acetyl-beta-D-glucosaminidase (NAG) with a single high dose of vancomycin, gentamicin or a combination of vancomycin and gentamicin was studied in male Wistar rats and compared with elimination of a control group. The rats received vancomycin intraperitoneally (200 mg.kg-1), gentamicin intramuscularly (100 mg.kg-1) or the combination of the drugs by the same route. A control group received isotonic NaCl solution. The four groups of animals received a single injection at 8 a.m., 2 p.m., 8 p.m., and 2 a.m. and urine excretion values for AAP, gamma GT and NAG were determined 24 hr later. The results show that the nephrotoxicity of gentamicin + vancomycin is greater than that observed with gentamicin, which again is greater than that observed with vancomycin. Furthermore, circadian variations in renal toxicity were observed, the least occurring at 8 a.m.

Enzymuria and tubular proteinuria in diabetic rats: a 12-week follow-up study

Various biochemical parameters of renal tubular function were examined for a period of up to 12 weeks in rats rendered diabetic by an i.v. injection of streptozotocin. Except for a statistically significant decrease in the urinary excretion of gamma-glutamyl-transpeptidase to 64% of control values, the urinary excretion of beta-N-acetyl-D-glucosaminidase, beta-galactosidase, alanine aminopeptidase, and lactate dehydrogenase significantly increases in diabetic rats to between 154% and 712% of control values. This increased enzymuria is not correlated to the marked polyuria induced by diabetes (r between 0.14 and 0.35, not significant). Enzymuria is also accompanied by a 10-fold increase in the urinary excretion of the low molecular weight protein beta 2-microglobulin while the excretion of albumin is not significantly modified, indicating impairment of tubular reabsorption in diabetic animals. Clearance studies reveal that the clearance of both beta 2-microglobulin and infused egg-white lysozyme are also increased. Finally the histopathologic examination of paraffin sections of the kidney show hydropic degenerescence and pycnosis of the tubular cells. It is concluded that early-stage diabetes results in tubular impairment and that the streptozotocin-rat model appears well suited to the study of these early signs of renal dysfunction.

Nonionic iodinated contrast media: potential renal damage assessed with enzymuria

The potential of digital subtraction angiography (DSA) to enable study of the physiology of renal transplantation after a single intravenous injection of nonionic iodinated contrast material stimulated this investigation into the possible nephrotoxicity of the contrast material used. Levels of urinary enzyme activity, used as markers of renal damage, were measured before, immediately after, and up to 72 hours after intravenous injection of nonionic iodinated contrast material in two groups of patients undergoing DSA. Twenty-six patients had undergone renal transplantation and 10 control patients had normal renal function. Both groups showed a transient rise in the level of urinary enzyme activity that peaked within 24 hours and returned to levels obtained before DSA within 72 hours. In the transplantation group, the baseline levels of enzymes were higher, and the response after administration of contrast material was greater. Nevertheless, the duration of the response was the same as in the control group, and the enzyme levels of all patients returned to their pre-DSA baseline levels.

[Microalbumin excretion in the group of patients with asymptomatic hematuria]

Urine albumin was determined in patients with chronic glomerular injuries with normal renal function, who had shown positive test of microhematuria but negative test of proteinuria at any time of our renal clinic. The subjects were divided into 4 groups: (1) IgA nephropathy (IgAN); 13, (2) asymptomatic hematuria (AS); 18, (3) nephrotic syndrome in complete remission (CR); 21 and (4) age matched normal subjects; 44. Urine albumin concentration was measured with radioimmunoassay in the ambulatory urine, and, in some cases, in the urine obtained after supine position for 30 minutes to demonstrate the effect of ambulatory physical movement on albumin excretion. Also urine alanine aminopeptidase (AAP) and N-acetyl-beta-D-glucosaminidase (NAG) were estimated by monitoring the absorbance of products released by the enzyme, as the indices of tubular function. The results indicated that urine albumin were 8.4 +/- 7.3 mg/g Cr (Mean +/- SD) in normal subjects, and 8.8 +/- 8.9 mg/g Cr in CR (vs. controls: N.S.), 18.9 +/- 14.5 mg/g Cr in AS (P = 0.0071), and 22.2 +/- 14.9 mg/g Cr in IgAN (P = 0.0063). The albumin excretion had no relation with the grade of microhematuria and also with the ambulatory physical movement. Moreover, AAP and NAG excretion in each group had shown no significant alterations. These results indicate that urine albumin increases in IgAN and AS with normal renal function and with microhematuria alone, but not in CR. Urine albumin is probably glomerular origin, since no abnormality is found in the tubular functions.

Pharmacokinetics and antibacterial activity of daily gentamicin

Twenty full term neonates with suspected bacterial infection were randomly assigned to a once daily or a twice daily dosage regimen with gentamicin (4 mg/kg/day). Concomitantly all patients were treated with ampicillin (200 mg/kg/day). The gentamicin concentration time curves were analysed by an open two compartment model under steady state conditions on day 4 of treatment. The mean theoretical maximum serum concentration in the group taking gentamicin once daily (10.9 micrograms/ml) was significantly higher than in the group taking it twice daily (7.4 micrograms/ml). Potentially toxic serum concentrations were never reached. Mean trough concentrations were comparable in both groups (once daily 0.8 micrograms/ml; twice daily 1.0 micrograms/ml). Urinary alanine aminopeptidase excretion increased during and even two days after end of treatment in both groups without any significant differences. The results of the dynamic in vitro model revealed that both dosage schedules showed comparable bactericidal effects on pathogens inhibited by low concentrations of gentamicin like Escherichia coli and Staphylococcus aureus. However the once daily regimen was significantly superior in isolates with high minimal inhibitory concentrations.

Enzymuria in neonates receiving continuous intravenous infusion of gentamicin

Urinary excretion of the tubular enzymes NAG and AAP was investigated during gentamicin treatment of 105 newborn infants. The values found for NAG and AAP show a significant positive correlation. The urinary excretion of NAG was on the average 92% higher during gentamicin treatment as compared with non-treatment periods in the same newborn infant (33 infants). The same tendency applied to AAP. Newborn infants receiving continuous intravenous infusion of gentamicin were not found to be at greater risk of nephrotoxicity than those receiving intermittent gentamicin treatment, using NAG and AAP as an index of nephrotoxicity. The changes in NAg and AAP within treatment periods were studied. During gentamicin treatment an insignificant average increase in the urinary excretion of NAG occurred, whereas a significant decrease was found during non-treatment periods. A significant negative correlation was found between urinary excretion of NAG and birth weight/gestational age. The long-term effect of the higher excretion of NAG and AAP in newborn and adult patients during aminoglycoside treatment is unknown.

Inhibition of aminopeptidase activity by aromatic and other cyclic compounds

The effect of 2-naphthylamine, p-nitroaniline, o-phenanthroline, sodium deoxycholate and hydrocortisone succinate on the activity of human urine aminopeptidase, rat kidney methionyl and arginyl aminopeptidase, soybean and Enterolobium contortisiliquum seed aminopeptidase was studied using aminoacyl-2-naphthylamide and L-Leu-p-nitroanilide as substrates. Ki values ranged from 10 microM to 2.7 mM. On the basis of Ki and Km values, and catalytic efficiency for each enzyme, it is clear that the aminopeptidases from human urine and from soybean seed should be assayed with both substrates, whereas L-Leu-p-nitroaniline is a more appropriate substrate for the rat kidney aminopeptidases. Sodium deoxycholate is a better inhibitor than hydrocortisone succinate. Non-competitive inhibition was observed in all cases except for E. contortisiliquum seed aminopeptidase.

Infradian rhythms of alanine aminopeptidase excretion during gentamicin therapy

Urinary excretion of alanine aminopeptidase (EC 3.4.11.2) was examined in 30 patients (22 women, 8 men, range 38-81 years; mean age 55.4) receiving gentamicin in a therapeutic dosage, which was based on the monitored blood creatinine concentration. In general, therapy lasted 10 days. The excretion of 24 individuals displayed significant infradian rhythms with periods between 2.2 and 8.1 days. In 10 of these 24 patients (42%) a circaseptan period was detected. The high portion of circaseptan rhythms might have been induced by the detrimental effects of gentamicin on the proximal tubule and the resulting processes of reconstitution.

[Activity of alanine aminopeptidase, beta-glucuronidase and N-acetyl-beta-d-glucosaminidase in urine of children with nephrotic syndrome]

Activity of alanine aminopeptidase (AAP), beta-glucuronidase, and N-acetyl-beta-D-glucosaminidase (NAG) in daily urine has been determined in 27 children with nephrotic syndrome, 14 children in remission, and 11 healthy children. It was found, that these enzymes activity is significantly increased in sick children in comparison with healthy ones. Similarly, the activity of AAP and NAG in daily urine is statistically significantly higher in children with remission, than that in healthy children. An assay of these enzymes in the urine may be used in the diagnosis of nephrotic syndrome and in the evaluation of its course.

[Experimental studies on the elevation of urinary enzyme activities and its pathogenesis in acute renal failure]

The urinary activities of N-acetyl-beta-D-glucosaminidase (NAG), gamma-glutamyl transpeptidase (gamma-GTP) and alanine aminopeptidase (AAP) are known to elevate markedly in initial phase of clinical acute renal failure (ARF). This study was performed to clarify the pathophysiological mechanism of the activation of these enzymes using experimental postischemic reperfusion ARF in rats. The relation between the levels of the lysosomal enzymes and lipid peroxidation induced by oxidant stress in these animal models was the main focus of this study. Renal ischemia was made by clamping renal artery for 30 minutes to create a complete ischemia and reflow. Catheterized urine was collected to measure changes of the activities of NAG. gamma-GTP and AAP from 60 to 480 minutes after reperfusion of the kidney. The activities of renal tissue glutathione peroxidase (GSH-Px), NAG and gamma-GTP, and the values of renal contents of glutathione (GSH) and malondialdehyde (MDA) were measured in each sample. It is already known that GSH redox cycle plays an important role in removing various hydroperoxides induced by oxidant stress, generating oxidated GSH from GSH in scavenging process. In order to confirm if GSH plays an important role in intrinsic anti-oxidant system in this model, buthionine sulfoximine (BSO) which is gamma-glutamylcysteine synthetase inhibitor, was administered intraperitoneally to decrease renal GSH contents before the procedure renal ischemia. The following results were obtained; 1) urinary activities of NAG, gamma-GTP and AAP were elevated markedly in GSH depleted rats compared with controls, 2) renal tissue activities of NAG were higher in BSO administered rats than controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Enzyme activities of urinary alanine aminopeptidase (AAP) and N-acetyl-beta-D-glucosaminidase (NAG) in healthy dogs

The activity of the urinary enzymes alanine aminopeptidase (AAP; EC 3.4.11.2) and N-acetyl-beta-D-glucosaminidase (NAG; EC 3.2.1.30) was measured after eliminating distorting factors in ten healthy dogs on three consecutive days in order to determine inter- and intra-individual variability. All the animals were being housed and fed in the same way. The urine (2nd morning urine) was collected between 8:30 and 10:00 a.m. by means of ultrasound-controlled cystocentesis. Our comparative measurements of native and gel-filtered urine showed an increase in enzyme activity in all of the samples in the case of AAP and in most of the samples in the case of NAG, thus proving the existence in the dog of AAP and NAG urinary enzyme inhibitors. The large inter- and intra-individual AAP and NAG fluctuation ranges were reduced considerably by relating enzyme activity to urine creatinine concentration. The provisional upper limit of the AAP reference range is 6.3 U/g creatinine (90% percentile), that of NAG 6.2 U/g creatinine (90% percentile). The AAP and NAG enzyme activities remained constant in gel-filtered samples kept at 4 degrees C for at least 5 days, in those kept at -18 degrees C for at least 4 weeks.

[Circadian variations in the nephrotoxicity of the vancomycin-gentamicin combination in rats]

Male Wistar rats were used to evaluate the influence of time of administration of a single high dose of vancomycin (V), gentamicin (G) or vancomycin-gentamicin combination (V/G) on excretion of a brush border enzyme, alanine aminopeptidase (AAP) and of a lysosomal enzyme, N-acetyl-beta-D-glucosaminidase (NAG). Increased urinary excretion is considered as an early manifestation of renal toxicity. The rats were placed in temperature-controlled quarters with intermittent lighting (12 hours light/12 hours dark). V was given intraperitoneally in a dose of 200 mg/kg, G was given intramuscularly in a dose of 100 mg/kg, and the V/G combination was given in the same doses and by the same routes as each drug alone. A control batch of rats received an intraperitoneal injection of saline. In the four batches, the injection was given at 8 am, 2 pm, 8 pm and 2 am. Substantial brush border toxicity was found. Toxicity of G was greatest at 2 pm and lowest at 2 am, whereas for V, toxicity was greatest at 2 am and lowest at 2 pm. With the V/G combination, brush border toxicity was greatest at 2 am and lowest at 8 am. Lysosomal toxicity was no significant after administration of V or G. In contrast, the V/G combination induced very significant lysosomal toxicity which was greatest at 2 pm and smallest at 8 am. These results show that circadian variations in renal toxicity occur not only with V and G alone but also with the V/G combination.

[Urinary excretion of glycine.prolile dipeptidile aminopeptidase, N-acetyl-beta-D-glucosaminidase, alanine aminopeptidase and low molecular protein in patients with renal cell carcinoma]

Urinary excretion of glycine.prolile dipeptidile aminopeptidase (GP-DAP), N-acetyl-beta-D-glucosaminidase (NAG), alanine aminopeptidase (AAP) and beta 2-microglobulin (beta 2-M), alpha 1-microglobulin (alpha 1-M) was studied preoperatively in 32 patients with renal cell carcinoma. The excretion indices of GP-DAP, AAP and NAG were significantly higher than those in the healthy control group. The excretion of these enzymes obviously reflected the degree of the tumor progression. However, positive rates were not remarkable (37% for GP-DAP, 37% for AAP and 28% for NAG). The excretion of beta 2-M and alpha 1-M was not increased in renal cell carcinoma patients.

Seasonal effects on the daily variations of gentamicin-induced nephrotoxicity

The effect on kidney damage of the season of year at which gentamicin was administered to rats was studied. Rats received a single intramuscular dose of 200 mg/kg gentamicin at four different times of the day (08.00, 14.00, 20.00 or 02.00 hours. Studies were carried out in January-February, March-April, June-July and October-November. The nephrotoxicity was assessed by the increase of three urinary enzymes: two brush border enzymes, gamma-glutamyl transferase and alanine aminopeptidase, and a lysosomal enzyme: N-acetyl-beta-D-glucosaminidase. The results show that when the injection is administered at 20.00 hours in the January-February and the October-November studies and at 08.00 hours in the March-April study and at 14.00 hours in the June-July study there is a significant increase in the excretion of these enzymes. The renal toxicity of gentamicin therefore has circadian variations as well as seasonal variations. The peak enzyme level is displaced from the start to the end of the rest period of rats depending upon the time of year.