Elevated serum activity of N-acetyl-beta-glucosaminidase in essential hypertension: diagnostic value and reversal to normal values after antihypertensive therapy

Establishment of blood glycosidase activities and their excursions in sepsis

Glycosidases are hydrolytic enzymes studied principally in the context of intracellular catabolism within the lysosome. Therefore, glycosidase activities are classically measured in experimentally acidified assay conditions reflecting their low pH optima. However, glycosidases are also present in the bloodstream where they may retain sufficient activity to participate in the regulation of glycoprotein half-lives, proteostasis, and disease pathogenesis. We have, herein, established at physiological pH 7.4 in blood plasma and sera the normal ranges of four major glycosidase activities essential for blood glycoprotein remodeling in healthy mice and humans. These activities included β-galactosidase, β-N-acetylglucosaminidase, α-mannosidase, and α-fucosidase. We have identified their origins to include the mammalian genes Glb1, HexB, Man2a1, and Fuca1. In experimental sepsis, excursions of glycosidase activities occurred with differences in host responses to discrete bacterial pathogens. Among similar excursions in human sepsis, the elevation of β-galactosidase activity was a prognostic indicator of increased likelihood of patient death.

Activity of lysosomal exoglycosidases in the urine of healthy normotensive and pre-hypertensive children

PURPOSE

We investigated the relationship between blood pressure (BP) and the activity of lysosomal exoglycosidases: N-acetyl-β-hexosaminidase (HEX), its isoenzymes A (HEX A) and B (HEX B), α-fucosidase (FUC), β-galactosidase (GAL), β-glucuronidase (GLU) and α-mannosidase (MAN) in pre-hypertensive (high normal blood pressure - HNBP) and normal blood pressure (NBP) children.

MATERIAL AND METHODS

The study was carried out with urine samples collected from 176 children, aged 6-17.9 years, divided into 2 groups: 42 HNBP and 134 NBP subjects. The children were stratified depending on systolic and diastolic BP (SBP; DBP): HNBP (SBP and/or DBP greater than or equal to the 90th percentile, but less than the 95th percentile) for sex, age, and height; and NBP (SBP and DBP less than the 90th centile). The activities of lysosomal exoglycosidases were determined by the colorimetric method, and expressed in pKat/mL and pKat/μgCr.

RESULTS

The activity of urinary HEX A in HNBP group was significantly higher than in NBP (p < 0.05). The HNBP group showed significant positive correlation between HEX, HEX A (pKat/mL) and SBP. AUC for HEX A was 0.616, cut-off value -29.351 pKat/mL (sensitivity 51.2%, specificity 71.8%), and 0.589, cut-off value -0.054 pKat/μgCr (sensitivity 31.7%, specificity 86.3%).

CONCLUSIONS

This is the first report of the relationship between BP and the activity of urinary lysosomal exoglycosidases: HEX, HEX A and HEX B, FUC, GAL, GLU, and MAN in healthy children and adolescents. It seems that HEX A (pKat/mL) can be used as a useful tool in identifying children with HNBP.