Search results for "beta-N-Acetylhexosaminidases"
showing 7 items of 7 documents
Progressive cerebellar ataxia, proximal neurogenic weakness and ocular motor disturbances: hexosaminidase A deficiency with late clinical onset in fo…
1997
Tay-Sachs disease is a genetically determined neurodegenerative disorder, resulting from mutations of the hexosaminidase (Hex) A gene coding for the alpha-subunit of beta-D-N-acetyl-hexosaminidase. Clinically, there is severe encephalomyelopathy leading to death within the first few years of life. Hex A activity is usually absent in tissue and body fluids of these patients. Juvenile and adult Hex A deficiencies are less severe but rare variants with some residual Hex A activity. All these variants are most prevalent among Ashkenazi Jews. We describe a non-Jewish family in which four adult brothers and sisters had markedly reduced Hex A activities and onset of symptoms in the second decade o…
Neuraminidase deficiency presenting as non-immune hydrops fetalis
1984
A newborn infant with oedema, ascites and hepatosplenomegaly is described. In ascites fluid foamy macrophages were found, in a liver biopsy cytoplasmic inclusions and membrane-bound vacuoles were seen. Furthermore the child excreted excessive amounts of sialic acid-rich oligosaccharides in the urine, and therefore a neurovisceral degenerative disorder was assumed. The diagnosis of sialidosis was confirmed by enzymatic assay in cultured fibroblasts, in which a complete deficiency of the lysosomal enzyme neuraminidase could be demonstrated. After recurrent septicaemias the child became dystrophic and died at the age of 6 months. Our case is compared with sialidosis observed by other authors, …
Thalamic hyperdensity — is it a diagnostic marker for Sandhoff disease?
1993
Sandhoff disease, also known as GM2-gangliosidoses variant 0, is caused by the deficient activity of both hexosaminidase A and hexosaminidase B. We report a 15-month-old boy diagnosed with Sandhoff disease by demonstrating the enzyme deficiency. The interesting finding was bilateral thalamic hyperdensity on the CT scan. The hyperdensity in all previously published cases was homogeneous and symmetric and limited to the thalamus; the cause still remains unknown. We suggest that the finding of dense thalami may be useful as a specific diagnostic criterion for the GM2-gangliosidoses and especially for Sandhoff disease.
Serum hexosaminidase and ß-glucuronidase activities in infants: effects of age and sex
2003
We investigated the effect of age and sex on the serum activity of hexosaminidase (HEX) and ß-glucuronidase (BGLU) in 275 normal term infants aged 12 h to 12 months. Up to six weeks of life, HEX was significantly higher in boys (P<=0.023). During the age period of 1-26 weeks, BGLU was also higher in boys, but differences were significant only at 2-6 and 7-15 weeks (P<=0.016). The developmental pattern of HEX and BGLU was sex dependent. HEX activity increased in both sexes from 4-7 days of life, reaching a maximum of 1.4-fold the birth value at 2-6 weeks of age in boys (P<0.001) and a maximum of 1.6-fold at 7-15 weeks in girls (P<0.001). HEX activity gradually decreased thereafter, reaching …
Enzyme molecular mechanism as a starting point to design new inhibitors: a theoretical study of O-GlcNAcase.
2011
O-Glycoprotein 2-acetamino-2-deoxy-β-d-glucopyranosidase (O-GlcNAcase) hydrolyzes O-linked 2-acetamido-2-deoxy-β-d-glucopyranoside (O-GlcNAc) residues from post-translationally modified serine/threonine residues of nucleocytoplasmic protein. The chemical process involves substrate-assisted catalysis, where two aspartate residues have been identified as the two key catalytic residues of O-GlcNAcase. In this report, the first step of the catalytic mechanism used by O-GlcNAcase involving substrate-assisted catalysis has been studied using a hybrid quantum mechanical/molecular mechanical (QM/MM) Molecular Dynamics (MD) calculations. The free energy profile shows that the formation of the oxazol…
Stimulation with carbachol alters endomembrane distribution and plasma membrane expression of intracellular proteins in lacrimal acinar cells.
2000
The events that lead to Sjogren's autoimmune processes in the lacrimal gland remain poorly understood. The acinar cell's responses to acute cholinergic stimulation include release of secretory products across the apical plasma membrane (apm) and a number of processes related to traffic between endomembrane compartments and the basal-lateral plasma membranes (blm), such as recruitment of Na, K-ATPase, accelerated recycling, and accelerated transcytosis of secretory IgA. We tested the hypothesis that stimulation-induced acceleration of endomembrane traffic is accompanied by changes in compartmentation and increased blm expression of proteins that are normally sequestered in endomembrane compa…
OGT and OGA expression in postmenopausal skeletal muscle associates with hormone replacement therapy and muscle cross-sectional area
2013
Protein glycosylation via O-linked N-acetylglucosaminylation (O-GlcNAcylation) is an important post-translational regulatory mechanism mediated by O-GlcNAc transferase (OGT) and responsive to nutrients and stress. OGT attaches an O-GlcNAc moiety to proteins, while O-GlcNAcase (OGA) catalyzes O-GlcNAc removal. In skeletal muscle of experimental animals, prolonged increase in O-GlcNAcylation associates with age and muscle atrophy. Here we examined the effects of hormone replacement therapy (HRT) and power training (PT) on muscle OGT and OGA gene expression in postmenopausal women generally prone to age-related muscle weakness. In addition, the associations of OGT and OGA gene expressions with…