N-acetyl beta-D-glucosaminidase and alpha-L-fucosidase activities in relation to glycosylated hemoglobin levels and to retinopathy in diabetes

Proteins from the 18 glycosyl hydrolase family are associated with kidney dysfunction in patients with diabetes type 2

OBJECTIVES

To investigate chitotriosidase (CHIT1) activity and chitinase-3-like protein 1 (YKL-40) concentration in plasma of type 2 diabetic patients and evaluate their relationship with kidney dysfunction.

MATERIALS AND METHODS

94 diabetic subjects and 33 controls were enrolled in the study. Plasma CHIT1 activity and YKL-40 concentration were measured along with routine laboratory parameters.

RESULTS

Levels of CHIT1 and YKL-40 in plasma of type 2 diabetic patients increased progressively with the degree of albuminuria. CHIT1 discriminated normoalbuminuric subjects from those with abnormal albuminuria better than YKL-40.

CONCLUSIONS

CHIT1represent a supportive biomarker connected with development of diabetic vascular complications, especially kidney dysfunction.

Analytical biochemistry and clinical significance of N-acetyl-beta-D-glucosaminidase and related enzymes

Human N-acetyl-beta-D-glucosaminidase, N-acetyl-alpha-D-glucosaminidase, endo-beta-N-acetylglucosaminidase, hexosaminidase, beta-N-acetylgalactosaminidase and glucocerebrosidase have not been so widely studied as the beta-N-acetylhexosaminidases in bacteria, fungi and arthropods. Their biochemical role has been elucidated, however, and their urinary and plasma determination is being adopted for the early detection of diseases before clinical manifestation, in particular for hypertension, renal injuries and disorders, depression and lysosomal storage diseases. The spectrophotometric determinations of N-acetyl-beta-D-glucosaminidase, most often done with 3-cresolsulphone phthaleinyl N-acetyl-beta-D-glucosaminide, have been recently simplified and adapted to automatic instruments.

Abnormalities in sperm acid glycosidases from infertile men with idiopathic oligoasthenoteratozoospermia

OBJECTIVE

To analyze and compare acid beta-glucuronidase, alpha-mannosidase, alpha-glycosidase, alpha-galactosidase, beta-galactosidase, and beta-N-acetylglucosaminidase activities in fertile and infertile patients.

DESIGN

An observational, controlled, clinical study.

SETTING

A university tertiary hospital.

PATIENT(S)

Thirty-six fertile controls, 24 infertile oligoasthenoteratozoospermic (OAT) patients, and 10 azoospermic patients, who served as negative controls.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Analysis of the six glycosidase activities in seminal plasma and in solubilized spermatozoa.

RESULT(S)

alpha-galactosidase and beta-galactosidase activities in spermatozoa were significantly correlated with the serum levels of gonadotropins both in fertile controls and in OAT patients. The relative contribution of alpha-galactosidase and beta-galactosidase from the soluble fraction of spermatozoa to the total activity measured in the ejaculate of OAT patients was significantly lower than in fertile controls. The activities of beta-galactosidase and beta-N-acetylglucosaminidase in the soluble fraction of spermatozoa from OAT patients were significantly lower than in fertile controls. In seminal plasma, the activity of alpha-mannosidase from OAT patients was significantly higher than in fertile controls. The activity of beta-N-acetylglucosaminidase in the nonsoluble fraction of spermatozoa from OAT patients was three times higher than in fertile controls.

CONCLUSION(S)

The abnormalities in the distributions and contents of alpha-galactosidase, beta-galactosidase, and beta-N-acetylglucosaminidase in sperm suggest possible functional defects in spermatozoa from OAT infertile patients.

Prospective study of the enzymatic activities in urine of N-acetyl-beta-D-glucosaminidase, alpha-D-mannosidase, alpha- and beta-D-glucosidases, alpha-L- and beta-D-fucosidases, and beta-D-galactosidase in type I diabetes mellitus with early nephropathy

Different surveys have been carried out on the plasma activities of different glycosidases in patients with insulin-dependent diabetes mellitus, but research on urinary glycosidases in this disease is scanty and incomplete. To elucidate the behavior of these lysosomal enzymes in the metabolic alterations occurring in the glomerular basal membrane during the initial stages of diabetic nephropathy, we conducted a prospective study to examine the urinary activities of N-acetyl-beta-D-glucosaminidase (NAG), alpha-D-mannosidase, alpha- and beta-D-glucosidase, alpha-L- and beta-D-fucosidase, and beta-D-galactosidase in patients with type I insulin-dependent diabetes mellitus, surveyed over 18 months, whose early diabetic nephropathy was detected by the presence of microalbuminuria. The simultaneous determination of beta 2-microglobulin in urine confirmed the glomerular origin of the albuminuria. No statistically significant correlation was found between the levels of albuminuria and the activities of any of the glycosidases analyzed. In the diabetic patients, a significant decrease was observed in the activities of all the enzymes (p < 0.05), except NAG and alpha-D-mannosidase, although the decrease in the latter was very close to statistical significance (p = 0.028, unilateral; p = 0.057 bilateral). Similarly, in the patients, there was a significant negative correlation (p < 0.05) with the serum levels of fructosamine, except with beta-D-galactosidase, which showed a positive correlation (p < 0.05) with fructosamine and blood HbA1c.(ABSTRACT TRUNCATED AT 250 WORDS)

Increased serum N-acetyl-beta-D-glucosaminidase and alpha-D-mannosidase activities in obese subjects

We have studied N-acetyl-beta-D-glucosaminidase and alpha-D-mannosidase activities in human sera from 35 control subjects, 47 normo- and hyperinsulinemic obese persons, and 12 diabetic patients after a fasting period of 12 h and at 30, 60, 90, and 120 min after an oral glucose overload. The results show a significantly higher activity of these 2 enzymes in obese subjects and diabetic patients, of similar magnitude, especially in those obese persons with a higher grade of obesity. Moreover, the activity of these glycosidases decreases in a similar way in all these 3 groups after the oral glucose overload.

Immunohistochemical studies of beta-hexosaminidase in neoplastic and normal tissues with monoclonal antibodies

A total of 87 human specimens with 10 histological types of primary neoplasm were studied immunohistochemically with monoclonal antibodies specific for beta-hexosaminidase (Hex). High levels of Hex were found in malignant neoplasms of the skin, cervix, colorectum and in benign as well as neoplastic plasma cells, while no activity was detected in normal epidermis, normal colorectal epithelium or benign naevi. The strongest immunohistochemical reaction was revealed in tumor cells of malignant melanoma. Adenomas and adenocarcinomas of the colorectum showed high levels of Hex with a basal pattern of immunoreactivity more frequent in the tumor cells of adenocarcinomas than adenomas. Fibroblasts and macrophages in the tumors often disclosed immunoreactivity. In most of the sections (including those from plasma cell neoplasms), 7E4 antibody showed low immunoreactivity compared to 2E3, except for non-neoplastic plasma cells, which were as a rule positive with 7E4 and largely negative with 2E3 antibody. This result probably indicated different isoenzymes in benign and neoplastic plasma cells.

Serum beta-N-acetyl hexosaminidase and bile acid levels in patients with benign and malignant biliary obstruction

beta-N-Acetyl hexosaminidase (beta-NAH), a lysosomal enzyme, was measured in the plasma of 15 patients with malignant extrahepatic biliary obstruction, 14 with benign extrahepatic obstruction, and 15 with long-standing benign intrahepatic cholestasis. beta-NAH was correlated with total serum bile acid levels. The correlation was significant (P less than 0.05) for the malignant and benign intrahepatic obstructions but not for the benign extrahepatic obstructions. This is consistent with the idea that circulating high levels of bile acids in patients with long-standing biliary obstruction may cause damage to Kupffer cell membranes and to their receptors for beta-N-acetyl hexosaminidase, impeding the clearance of the enzyme from the circulation resulting in elevated serum levels.

Delay of progression of diabetic microangiopathy

Three muscle biopsies were performed in 53 overt type II diabetics over a period of approximately 2 years. At baseline, 21 (40%) had an abnormally increased capillary basement membrane width in muscle. Thirty-five subjects received glipizide and 18, placebo. At baseline, no statistically significant difference was found in the muscle capillary basement membrane width between the two groups (P = NS). In the subjects receiving placebo, the mean width of the muscle capillary basement membrane increased (P = NS), but in those receiving glipizide, the mean decreased from 193 +/- 13 nm (SEM) to 161 +/- 10 nm (P = .02). Fasting plasma glucose and glycosylated hemoglobin A1 significantly decreased (P less than .001) after two years in those receiving glipizide. In 15 subjects, mean glycosylated hemoglobin A1 reached the normal range, and mean muscle capillary basement membrane width decreased to a level close to that found in subjects without diabetes (P = NS). Determinations of enzyme activities involved in the synthesis and degradation of glycoproteins revealed a 2-year significant decrease of muscle glucosyltransferase (synthesis) activity (P less than .01) in the glipizide-treated subjects as opposed to a significant increase (P less than .001) in those receiving placebo. Muscle N-acetyl-beta-glucosaminidase activity (degradation) was statistically increased (P less than .001) in those subjects taking glipizide, but decreased in those taking placebo (P less than .001).

Behaviour of some lysosomal enzymes in the plasma of insulin dependent diabetic patients during artificial pancreas treatment

The plasma levels of three lysosomal enzymes, beta-D-N-acetylglucosaminidase, beta-D-glucuronidase, and alpha-L-fucosidase, were fluorimetrically determined in seven insulin-dependent diabetic patients one day before, one day after, and during a two-day treatment with the artificial pancreas, at 4 to 5 h intervals. A statistically significant decrease of the plasma level of each enzyme was observed during artificial pancreas treatment. The extent of decrease was 30 to 35% for beta-N-acetylglucosaminidase, 35 to 40% for beta-D-glucuronidase, and 20 to 25% for alpha-L-fucosidase. The decrease occurred earlier (at the first day of treatment) for beta-D-N-acetylglucosaminidase, and later (at the second day of treatment, and lasting to the first day after treatment) for the other two enzymes. These results suggest a direct connection between the lysosomal apparatus and insulin-controlled metabolic pathways, and a potential role for lysosomal enzymes as indicators of the metabolic compensation in diabetes.

Serum enzymes of lysosomal origin as indicators of the metabolic control in non-insulin-dependent diabetics

Several lysosomal enzymes (beta-N-acetyl-D-glucosaminidase, beta-D-glucuronidase, alpha-D-galactosidase, beta-D-galactosidase, alpha-D-glucosidase, beta-D-glucosidase, alpha-L-fucosidase and alpha-D-mannosidase) were determined in the serum of 54 non-insulin-dependent diabetics with different degrees of metabolic control and without complications and in 18 non-insulin-dependent diabetics with complications. The serum levels of beta-N-acetyl-D-glucosaminidase, beta-D-glucuronidase, alpha-D-galactosidase, and alpha-D-mannosidase were significantly (p less than 0.01) higher in the diabetics without complications. The levels of beta-N-acetyl-D-glucosaminidase and beta-D-glucuronidase were inversely proportional to the degree of metabolic control, in a statistically significant manner. Moreover the levels of these enzymes decreased to normal values during a 2-month period of controlled oral hypoglycemic drug-diet therapy resulting in metabolic compensation. The presence of complications was indicated by a further increase of serum beta-N-acetyl-D-glucosaminidase and beta-D-glucuronidase; however the portion of lysosomal enzyme activities due to complications remained unchanged after controlled therapy aimed at compensating the metabolism. The conclusion is drawn that in non-insulin-dependent diabetics, as already shown for insulin dependent-diabetics, serum lysosomal enzymes, especially beta-N-acetyl-D-glucosaminidase and beta-D-glucuronidase, are good intraindividual indicators of the metabolic control of the disease.

Comparison of N-acetyl-beta-glucosaminidase and albuminuria with clinical finding of microangiopathy in type I diabetes mellitus

N-acetyl-beta-Glucosaminidase activity in serum and urine and microalbuminuria were measured in 70 type-I diabetics and compared with glycated serum protein as well as with the finding of diabetic retinopathy. A significantly increased N-acetyl-beta-glucosaminidase activity in serum correlated positively with glycated protein but not with the development of retinopathy. Urinary N-acetyl-beta-glucosaminidase activity and albuminuria were significantly increased in diabetics with (p less than 0.001) or without (p less than 0.01) retinopathy as compared to healthy controls. A significant positive correlation was observed between urinary N-acetyl-beta-glucosaminidase activity and albuminuria (r = 0.73, p less than 0.01) as well as between blood pressure and albuminuria (r = 0.51, p less than 0.05).

Serum enzymes of lysosomal origin as indicators of the metabolic control in diabetes: comparison with glycated hemoglobin and albumin

Several lysosomal enzymes (beta-N-D-acetylglucosaminidase, beta-D-glucuronidase, alpha-D-galactosidase, beta-D-galactosidase, alpha-L-fucosidase, alpha-D-glucosidase, alpha-D-mannosidase, beta-D-glucosidase), glycated albumin and glycated hemoglobin (HbA1c) were determined in the serum of 81 insulin-dependent diabetics with different degrees of metabolic control (optimal, 21 patients; good, 39 patients; poor, 21 patients) and without signs of complications, and in 42 control subjects. All parameters examined increased in serum in inverse proportion to the degree of metabolic control. A highly significant correlation (p less than 0.01) was found between lysosomal enzymes and both glycated albumin and HbA1c. All parameters correlated with hyperglycemia, glycated albumin having the highest r-value (0.586) and lysosomal enzymes the lowest one. Unlike glycated albumin and HbA1c, serum levels of lysosomal enzymes in patients with optimal metabolic control were undistinguishable or even lower than those of controls. A 2-month longitudinal monitoring of a patient who was hospitalized in conditions of poor metabolic control and adequately treated, proved that lysosomal enzymes diminished in serum parallel to glycated albumin and HbA1c in relation to improvement of the metabolic situation. The conclusion is drawn that serum lysosomal enzymes are good indicators of the metabolic control of diabetic patients probably reflecting the overall metabolic state connected with insulin action rather than hyperglycemia.

Enzyme activities as a predictor of diabetic vasculopathy

Forty-one patients with chemical diabetes had three oral glucose tolerance tests and underwent muscle biopsy three times over a period of three years. Twenty-three received glipizide and 18 placebo. Those taking placebo had an increase in the mean muscle capillary basement membrane width (p = 0.01), but those taking glipizide showed a decrease (p = 0.01) to values no different from those of nondiabetic subjects. Determinations of enzyme activities involved in the synthesis and degradation of glycoproteins revealed a three-year decrease (not significant) in muscle glucosyltransferase activity in the glipizide-treated patients, but a statistically significant difference (p less than 0.01) comparing the adjusted means of the two treatment groups. N-acetyl-beta-glucosaminidase activity was significantly increased in muscle from baseline values (p less than 0.01), with adjusted means also significantly different (p less than 0.01). The data suggest that changes in basement membrane and enzyme activities are correlated, and the latter may be a predictor to follow the development, progression, or regression of diabetic vasculopathy.

Glycosidase activities in sera from convalescent patients who ingested a toxic oil

Some glycosidase activities have been determined in blood sera from 21 patients who ingested a toxic oil (rapeseed oil denatured with aniline(s) and treated by a thermal process). The samples were collected from the same patients on 3 or 4 occasions during a period of 11-12 mth. During this period, the clinical state of the patients improved and, generally, they were restored to health. beta-N-Acetylglucosaminidase, alpha-L-fucosidase, beta-D-glucuronidase, beta-D-glucosidase and alpha-D-mannosidase activities, which were higher in patients than in 17 controls during the first mth decreased to normal values in the period studied, 11-12 mth. In contrast, beta-D-galactosidase, alpha-D-galactosidase and alpha-D-glucosidase activities, which were initially lower in patients than in controls, were finally similar or higher than in controls. One explanation for these results could be the possible alteration of the cell membrane(s) by the toxic substance(s).

Carbohydrate contents, and glycosidase and glycosyl transferase activities in tissues from streptozotocin diabetic mice

The contents of hexoses and hexosamines in brain, liver, and kidney of streptozotocin diabetic mice are significantly increased in comparison to the controls. These differences for hexoses contents in the heart are not significant. N-acetyl-beta-D-glucosaminidase and beta-D-glucosidase activities in brain, liver and kidney of diabetic mice are significantly higher when compared to the controls. However, beta-D-galactosidase activity is significantly lower in brain, liver, spleen and kidney of the diabetic mice, in comparison to the controls and similar in heart. alpha-D-Mannosidase activity of diabetic mice is significantly increased in spleen and heart and significantly decreased in liver and kidney. alpha-L-Fucosidase of diabetic mice shows higher activities, with significant differences, in liver and spleen; however, in heart and kidney the activities are significantly lower. Brain sialyltransferase and galactosyltransferase activities are significantly increased in diabetic mice; but for heart and kidney these differences are not significant. The activity for brain and kidney fucosyltransferase is not significant and that for the other assayed organs is significantly higher in comparison to the controls.

Purification, characterization and kinetics of beta-N-acetylhexosaminidases A and B from the slug Arion rufus L

Two beta-N-acetylhexosaminidases have been purified to homogeneity and characterized, from the digestive gland of the slug A. rufus L., showing very high specific activities. Hexosaminidase A (Hex A) was purified 1300-fold with a yield of 12%, and hexosaminidase B (Hex B) was purified 1400-fold with a yield of 20%. Purified Hex A or Hex B run as a single protein band in polyacrylamide gel disc electrophoresis, showing different mobilities. The purified preparations do not show any of the other glycosidase activities present in the crude extract. beta-N-acetylglucosaminidase (GlcNAc-ase) and beta-N-acetylgalactosaminidase (GalNAc-ase) activities are always associated in a single peak for each enzyme form, with constant activity ratio, in all the purification steps, since they are catalyzed by the same enzyme (Hex A or Hex B). The optimal pH for both forms are 4.5 for GlcNAc-ase and 4.0 for GalNAc-ase activity. Hex B shows thermal and pH-stability higher than Hex A. The isoelectric points are 4.5 and 5.5 for A and B forms, respectively. The molecular weight is 150 000 for Hex A and 320 000 for Hex B. The amino acid composition of purified Hex A and B presents some differences concerning particularly Cys, Thr, Ser, Glu and Ile. The ratios Vmax/Km show that GlcNAc-ase is the main activity of both enzyme forms. beta-N-acetylglucosides and beta-N-acetylgalactosides completely compete for a common active site in mixed-substrates experiments. The Ki values are always coincident for GlcNAc-ase and GalNAc-ase activities, using competitive inhibitors (the corresponding lactones). These results strongly suggest that both activities are catalyzed by the same active site in both Hex A and B. Inhibition of the enzyme activities was found with the corresponding lactones, N-acetyl hexosamines, mannose, mannosides, HgCl2 and lead acetate; activation, with ribose, and with some chlorides and sulphates of divalent cations.

Serum glycosidases in diabetes mellitus in relation to the retinopathy and to the length of the disease

The following glycosidase activities in sera have been studied: alpha-D-mannosidase, beta-D-glucuronidase, N-acetyl-beta-D-galactosaminidase, alpha-D-galactosidase, beta-D-galactosidase, alpha-D-glucosidase, beta-D-glucosidase and beta-D-fucosidase, in diabetic patients in relation to the presence of microangiopathy, evident by retinopathy, and to the length of the disease. A significant increase of all the enzyme activities, except for alpha-D-galactosidase was found. These elevations were independent of the development of retinopathy and the duration of the diabetic process.

Hydrolytic enzyme activities, mainly from lysosomal localization, in sera from patients who ingested a toxic oil

Some hydrolytic enzyme activities, mainly typical of lysosomal localization, have been determined in blood sera from patients who ingested a rapeseed oil (denatured with anilines and treated by a thermal process), and in healthy subjects. beta-N-Acetylglucosaminidase, beta-D-glucosidase, beta-D-glucuronidase, alpha-L-fucosidase and leucine aminopeptidase activities were significantly higher when compared with controls (p less than 0.001); higher activities but not significant (p less than 0.2) differences were found for alpha-D-mannosidase and alkaline phosphatase. In contrast, beta-D-galactosidase, alpha-D-galactosidase, acid phosphatase and lipase showed lower activities than controls. The significance of these results is discussed.