Activity of N-acetyl-beta-D-hexosaminidase (HEX) and its isoenzymes A and B in human milk during the first 3 months of breastfeeding.

PURPOSE: Milk contains free and bound oligo- and heteropolisaccharides, which protect newborns against pathogens and have nutritional value. N-acetyl-beta-D-hexosaminidase (HEX), the most active lysosomal exoglycosidase, modify and degrade oligo- and heteropolysaccharides. The objective of our study was to determine HEX activity and isoenzymes A and B in the progression of lactation. MATERIAL AND METHODS: Human milk samples were collected from 51 women on the 3rd, 21st and 100th day postpartum. Enzymatic activity was determined the Zwierz et al method modified by Marciniak et al. Protein and lactose concentrations were determined by a MilkoScan 4000 apparatus. RESULTS: The total HEX activity decreased by the 21st day in comparison to the 3rd day, and increased by the 100th day as compared to the 21st day. HEX A activity decreased by the 21st and the 100th day as compared to the 3rd day. HEX B activity decreased by 21st day and has the tendency to decrease by the 100th day as compared to the 3rd day. Protein concentration decreased and the lactose concentration increased in milk taken on the 21st day in comparison to concentration of protein and lactose on the 3rd day. HEX and its isoenzymes' activity significantly correlate with the progression of lactation. At the beginning of lactation, HEX A activity, which releases hexosamines from acidic oligosaccharides, dominates; later, HEX B releases hexosamines from neutral oligosaccharides. CONCLUSIONS: To better understand the degradation of human milk oligosaccharides, it would be useful to investigate and document their detailed structures and evaluate the activity of other exoglycosidases' activity in human breast milk over the course of lactation.

Activity of lysosomal exoglycosidases in saliva of patients with HIV infection.

PURPOSE: The aim of this work was to evaluate the influence of HIV infection on the catabolism of glycoconjugates in the oral cavity, by determination of the activity of lysosomal exoglycosidases in mixed saliva. METHOD: The specific activities of the following exoglycosidases were tested: N-acetyl-beta-hexosaminidase (HEX), its isoenzymes A (HEX-A) and B (HEX-B), alpha-mannosidase (MAN), beta-galactosidase (GAL) and alpha-fucosidase (FUC). RESULT: A significant increase of activity of HEX-A, GAL and FUC, and a significant decrease of the activity of HEX-B was found, but no significant changes in the HEX and MAN activity we noted. CONCLUSION: Our results indicate that following HIV infection, there is probably an increased rate of catabolism of glycoconjugates in saliva resulting from changes in the proportions of the activity of isoenzymes A and B of N-acetyl-beta-hexosaminidase, beta-galactosidase and alpha-fucosidase. An increase of HEXA activity can implicate the beginning of neoplastic changes developing in the oral cavity.

Saliva of patients with Type 1 diabetes: effect of smoking on activity of lysosomal exoglycosidases.

OBJECTIVE: The aim of our study was to evaluate the influence of smoking on the activity of N-acetyl-beta-hexosaminidase (HEX), its isoenzymes A (HEX-A) and B (HEX-B) and beta-galactosidase (GAL), in the saliva of patients with Type 1 diabetes. METHODS: In the supernatant HEX and its isoenzymes A and B, and beta-galactosidase were determined by the method of Chatteriee et al in modification of Zwierz et al (mKat kg(-1) of protein). Protein was determined by the Lowry et al method (mg ml(-1)). RESULTS: The results presented here suggest that diabetes and smoking modify activity of HEX and its isoenzymes, but only combination of diabetes and smoking give a significant increase in the specific activity of HEX and its isoenzymes. CONCLUSIONS: Type 1 diabetes slightly changes the composition of saliva. Smoking cigarettes significantly modifies the composition and properties of saliva in healthy individuals and patients with Type 1 diabetes.