Hexosaminidase A deficiency is an uncommon cause of a syndrome mimicking amyotrophic lateral sclerosis

Patients with adult hexosaminidase A (Hex A) deficiency may have clinical manifestations similar to amyotrophic lateral sclerosis (ALS). Mutations in the hexosaminidase A (HEXA) gene are common in the Jewish Ashkenazi population in Israel. Serum samples of 115 Israeli patients with sporadic ALS were screened for enzymatic activity to detect "enzyme-based carriers." Fifteen samples with low (< 50%) enzymatic activity were subjected to mutation analysis, which included the two common mutations in the HEXA gene among Ashkenazi Jews (+1278TATC and IVS12+1G-->C). Three "enzymatic carrier" patients of Moroccan origin were checked for two additional mutations (DeltaF304/305 and Arg170-->Gln), specific to this ethnic group. Two "enzymatic carrier" patients of Iraqi origin were analyzed for the mutation Gly250-->Val, specific to this population. The mutation Gly 269-->Ser was screened in carriers of Ashkenazi origin only (n = 10). The only abnormalities found were heterozygous +1278TATC mutations in two Ashkenazi patients. Their clinical presentation was not different from that usually encountered in ALS. The frequency of mutations in the HEXA gene among Israeli ALS patients was not higher than in the healthy Israeli population. Therefore, Hex A deficiency seems to be a very unlikely cause of an ALS-mimic syndrome.     

Isoenzyme studies in human leukemia — III. β-hexosaminidase (E.C. 3.2.1.30)

Enzymologic profiles of β-hexosaminidase (N-acetyl-β-d-glucosaminidase, E.C.3.2.1.30) were studied in cells from childhood acute leukemias and lymphomas. By analytical isoelectric focusing or disc electrophoresis the β-hexosaminidase activity was separated into its components A, B, I and C. The isoenzyme patterns were correlated with immunologic cell surface marker characteristics found on the investigated leukemic cells. In all cases of T-ALL the β-hexosaminidase forms A and B were observed, an enzyme pattern similar to that found in normal lymphocytes. Seven out of 11 cases with cALL, three of six cases with AML and one case of AUL displayed the intermediate component (Hex I). Marked heterogeneity within the immunologically classified subgroup cALL was reflected in different enzyme patterns of the cALL samples. These biochemical phenotypes may indicate the different maturation and differentiation status of cells expressing the same immunologic surface markers.     

Tay-sachs disease brain cells in culture: Mobilization of stored GM2 after concanavalin A-mediated uptake of hexosaminidase A

A human Tay-Sachs disease (TSD) fetal-brain-cell line is a useful model for the disease since the cells lack hexosaminidase A and accumulate the ganglioside, G_M2. This brain-cell line was used to assess the effect of hexosaminidase A treatment on G_M2 storage material. Entry of placental hexosaminidase A into the cells was obtained by pretreatment of the cultures with concanavalin A. Cells were analyzed periodically during six days. During the course of the experiment, G_M2 in the cells decreased by approximately 50%. A substantial amount of hexosaminidase A was maintained in the cultures throughout the experiment. This strategy was successful in mobilizing stored G_M2 in TSD brain-cell cultures. Therefore, the activating factor needed for hexosaminidase A activity must be present in TSD-cultured brain cells.     

Leukocyte glutamate dehydrogenase and CSF amino acids in late onset ataxias

Leukocyte glutamate dehydrogenase (GDH) activity was measured in 11 healthy control subjects, 16 neurological controls, 12 patients with dominant late onset ataxia, 15 patients with sporadic late onset ataxia and 8 with alcoholic cerebellar ataxia. Serum hexosaminidase activity was also determined in ataxic patients. Concentrations of free amino acids were determined in the lumbal CSF of 16 neurological controls, 8 patients with late onset ataxia and 5 with alcoholic ataxia. Mean total GDH activity was reduced significantly in dominant (p less than 0.05) and sporadic (p less than 0.01) cerebellar ataxia, while the heat-labile form was decreased significantly (p less than 0.01) only in sporadic ataxia. All GDH activities were within normal range in patients with alcoholic ataxia. The serum hexosaminidase activities were also within reference range in all patient groups. The CSF concentrations of alanine, glycine, methionine and valine were significantly elevated and those of GABA and glutamate were normal in patients with late onset ataxia as compared to neurological controls. The most significant (p less than 0.01) increase was found for methionine. The amino acid levels of patients with alcoholic ataxia did not differ from those of the controls. The results suggest that GDH activity is only partially decreased in some ataxic patients and that altered amino acid metabolism may be reflected in the CSF.     

Changes of serum hexosaminidase for the presumptive diagnosis of type I Gaucher disease in Tay-Sachs carrier screening

Although reduced acid β-glucosidase activity appears to be the primary enzyme defect in type I Gaucher disease, patients with this disorder also have marked elevation of serum acid phosphatase and β-hexosaminidase activities but with a normal level of lactic dehydrogenase activity. Moreover, there is a characteristic alteration in the hexosaminidase isozyme distribution with a striking increase in hexosaminidase B. Since these changes appear to be consistent and unlike those associated with other disorders or the hormonally induced alterations associated with pregnancy, routine serum testing for the Tay-Sachs carrier state may offer a useful approach for the presumptive diagnosis and screening for Gaucher disease. Unlike the changes in affected homozygotes, there are no characterisitic alterations of acid phosphatase or hexosaminidase in heterozygotes for Gaucher disease.     

B-N-acetyl hexosaminidase (B-NAH) serum levels after endotoxin administration into the portal vein in the rat

ABSTRACT— Endotoxin was injected directly into the portal vein in rats with and without common bile duct (CBD) ligation. B-N-acetyl hexosaminidase (B-NAH) activity levels in the serum were found to be significantly elevated 24 h later in both groups. Serum bile acid levels were found to be significantly higher in the endotoxin-injected groups of rats compared to controls. Thus, endotoxin, as well as bile acids, may cause damage to Kupffer cell membranes, resulting in accumulation of B-NAH in rat serum.     

A modeling study for structure features of β-N-acetyl-D-hexosaminidase from Ostrinia furnacalis and its novel inhibitor allosamidin: species selectivity and multi-target characteristics

Insect β-N-acetyl-D-hexosaminidase, a chitin degrading enzyme, is physiologically important during the unique life cycle of the insect. OfHex1, a β-N-acetyl-D-hexosaminidase from the insect, Ostrinia furna, which was obtained by our laboratory (Gen Bank No.: ABI81756.1), was studied by molecular modeling as well as by molecular docking with its inhibitor, allosamidin. 3D model of OfHex1 was built through the ligand-supported homology modeling approach. The binding modes of its substrate and inhibitor were proposed through docking and cluster analysis. The pocket's size and shape of OfHex1 differ from that of human β-N-acetyl-D-hexosaminidase, which determined that allosamidin can selectively inhibit OfHex1 instead of human β-N-acetyl-D-hexosaminidase. Moreover, the multi-target characteristics of allosamidin that inhibit enzymes from different families, OfHex1 (EC 3.2.1.52; GH20) and chitinase (EC 3.2.1.14; GH18), were compared. The common -1/+1 sugar-binding site of chitinase and OfHex1, and the -2/-3 sugar-binding site in chitinase contribute to the binding of allosamidin. This work, at molecular level, proved that OfHex1 could be a potential species-specific target for novel green pesticide design and also provide the possibility to develop allosamidin or its derivatives as a new type of insecticide to 'hit two birds with one stone', which maybe become a novel strategy in pest control.     

Effects of Flavone Derivatives on Antigen‐Stimulated Degranulation in RBL‐2H3 Cells

Mast cells are primarily responsible for IgE‐mediated allergic responses. The activation level of mast cells is reflected in their degree of degranulation. This can in turn be determined by measuring the amount of β‐hexosaminidase release, a key parameter in degranulation. In this study, 40 flavone derivatives, including flavone, 14 methoxyflavones, 13 hydroxyflavones, and 12 hydroxymethoxyflavones, were evaluated for their inhibition of degranulation in rat basophilic leukemia RBL‐2H3 cells. 3′,7‐Dihydroxyflavone inhibited degranulation (IC₅₀ = 13.56 μm ), which was comparable to PP2 (3‐(4‐chlorophenyl)‐1‐(1,1‐dimethylethyl)‐1H‐pyrazolo[3,4‐d]pyrimidin‐4‐amine) used as a control. In addition, we report quantitative relationships between the structural properties of flavones and their inhibitory effects on degranulation.