Expression modes of urinary N-acetyl-beta-D-glucosaminidase in patients with chronic renal insufficiency.

BACKGROUND: Urinary N-acetyl-beta-D-glucosaminidase (NAG) activity has emerged as potentially useful early marker of renal tubular injury. This activity is usually evaluated in random urine samples and is related to urinary creatinine concentration. Reports about the lack of correlation between NAG activity of 24-h urines and activity of random urine samples in some clinical and experimental situations led us to study the correlation existing between different procedures for expressing urinary NAG in patients with chronic renal insufficiency. METHODS: Thirty samples of 24-h urine and 30 random urine samples from chronic renal insufficiency patients were collected. The activity of urinary NAG was examined fluorimetrically. RESULTS: The following correlations were observed: (1) r = 0.431 (P = 0.017) for activity in random urine samples and total activity in 24-h urines); (2) r = 0.281 (P = 0.005) for activity in random samples and activity, expressed as U/l, in 24-h urines. CONCLUSIONS: The data show that collection of urine excreted over the whole day and evaluation of total daily excretion of NAG seems the method of choice, at least for patients with chronic renal insufficiency.

Activity and isoenzyme profile of N-acetyl-beta-D-glucosaminidase in urine from workers exposed to cadmium.

The urinary excretion of N-acetyl-beta-D-glucosaminidase (U-NAG) and urinary Cadmium (U-Cd) concentration, a measure of the metal load in the body, were evaluated in 28 workers exposed to Cd, to determine the relation between the two parameters. In urine from 22 exposed workers with U-Cd<2 microg/g creatinine (Cr) there was no significant difference in U-NAG value (0.98+/-0.59 U/gCr) compared to non-exposed (0.73+/-0.48 U/gCr). In the six workers with 2 microg/gCr < or =U-Cd<10 microg/gCr the U-NAG (2.32+/-0.61 U/gCr) was statistically (P<0.05) higher than in other workers. In both the U-Cd intervals examined there were no altered values of beta2-microglobulin from urine of exposed workers compared to non-exposed (<0.30 mg/l). The U-NAG isoenzymes were separated by DEAE-cellulose chromatography from urine of non-exposed subjects and exposed workers. The U-NAG isoenzyme profile in urine of non-exposed subjects showed a high percentage (about 95%) of the A (acid) form, a much lower percentage (about 4.5%) of B (basic) form and a negligible percentage (about 0.5%) of I (intermediate) form. In the urine of 22 exposed workers with U-Cd<2 microg/gCr, the percentages of U-NAG isoenzymes were not different from non-exposed. In the urine of six workers with 2 microg/gCr< or =U-Cd<10 microg/gCr the percentage (8.34+/-0.91) of isoenzyme B (U-NAG-B), a marker of lesional enzymuria, was statistically increased (P<0.05) compared to non-exposed (4.42+/-0.56). These results suggest that adopting a biological limit for U-Cd equal to 10 microg/gCr might not be sufficiently protective. The increase in U-NAG-B content at 2 microg/gCr

N-acetyl-beta-D-glucosaminidase activity in urine of dental personnel.

BACKGROUND: Dental personnel is exposed to several potential nephrotoxic agents. Urinary N-acetyl-beta-d-glucosaminidase (U-NAG) activity has emerged as a sensitive marker of early nephrotoxicity. METHODS: U-NAG was evaluated, by fluorimetric assay, in urine from 30 healthy subjects and 30 dental personnels. RESULTS: The median value of U-NAG activity (133.5 U/mmol urinary creatinine (U-Cr) in urines of dental personnel was not statistically different (P>0.05) from activity (100.7 U/mmol U-Cr) of control urines. CONCLUSIONS: The results suggest that, for dental personnel, exposure to potential nephrotoxic agents is not usually high enough to increase U-NAG activity.

Beta-N-acetylhexosaminidase activity and isoenzyme profile in the kidney and urine of trained rats.

Lysosomes play an important role in the immune system functioning and are involved in different aspects of inflammatory reaction, repair processes and tissue damage at various levels. Among various effects, it is known that physical exercise influences the release of different lysosomal components. The aim of this study was to evaluate enzyme activity and isoenzymatic profile of beta-N-acetylhexosaminidase both in kidney and urine of normal and trained rats. Enzyme activity was measured by fluorimetric assay while beta-N-acetylhexosaminidase isoenzymes were separated using DEAE-cellulose chromatography. Hexosaminidase specific activity was significantly increased in urine of trained rats whereas there was no increase in the kidneys of trained rats. Indeed, no significant differences were observed in the isoenzyme profile of kidney and urine extracts from normal and trained rats. Our findings suggest the exercise-induced release of lysosomal enzymes is a functional effect and not due to disruption of lysosomal membranes.