Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.2.1.31 (beta-glucuronidase)
 7,680 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cells of the mononuclear phagocyte system contain a cell surface receptor which mediates the uptake of mannose- and fucose-terminated glycoproteins. We have extended the initial studies to human alveolar and monocyte-derived macrophages in culture using two radiolabelled ligands, the synthetic glycoconjugate mannose-bovine serum albumin and the lysosomal glycosidase, beta-glucuronidase. Uptake (37 degrees C) of 125I-mannose-BSA by freshly isolated alveolar macrophages is saturable with increasing concentrations of ligand. Kuptake values in macrophages of smokers and nonsmokers are similar, and resemble earlier reported values using rabbit alveolar macrophages (Kuptake = 40 nM). Uptake of 125I-mannose-BSA in cultured smoker macrophages is identical to that found in fresh cells, and uptake is stable for 5-10 days in culture. Fucose- and mannose-BSA are the most effective inhibitors of uptake, while N-acetylglucosamine-BSA is inhibitory at slightly higher concentrations. Binding (4 degrees C) of 125I-mannose-BSA is likewise ligand concentration dependent (KD = 30 nM). Freshly isolated human monocytes from healthy subjects and patients with cystic fibrosis do not have mannose-specific uptake. However, after monocytes are in culture for 3 days, mannose-specific uptake appears and Kuptake values and specificity of uptake are identical with the results from the alveolar macrophages. No uptake of mannose-BSA could be found in the human monocyte-like cell line, U937.
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PMID:Characterization of the mannose/fucose receptor on human mononuclear phagocytes. 629 10

Expansion of the lysosomal apparatus occurs in subcortical white matter in brains from persons with AIDS. This study examined whether HIV-associated subcortical dementia (HAD) is significantly related to this lysosomal anomaly. Brain cortex and adjacent white matter from the middle frontal gyrus were obtained from the National NeuroAIDS Tissue Consortium. Lysosomal hydrolase activity was assayed in 57 subjects who underwent neuropsychological testing within 6 months prior to autopsy. Decedents were evaluated from 4 geographical sites in the United States: Galveston/Houston, Texas (n = 36), Los Angeles, California (n = 5), New York, New York (n = 5), and San Diego, California (n = 11). Increased beta-glucuronidase activity, a representative lysosomal glycosidase, was correlated with the amount of neurocognitive impairment. Significant correlation was present in 5 of 7 functional testing domains, including some that draw upon frontal lobe output (r = 0.419; P < 0.002). The biochemical anomaly was negligible in cerebral cortex and cerebrospinal fluid and was not correlated with brain dysfunction in those compartments. Glycosidase activation was associated significantly with increased HIV RNA concentration in brain tissue (r = 0.469; P < 0.021) and possibly with HIV RNA in cerebrospinal fluid (r = 0.266; P < 0.067). HIV RNA in blood plasma was not correlated. These results support the suggestion that abnormal metabolism in white matter glial cells contributes to cognitive slowing in persons with HAD. Because membrane turnover is routed through the endosome-lysosome apparatus, these data are in agreement with brain spectroscopic data that have suggested that there is an increase in membrane turnover in white matter glia.
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PMID:Potential role for white matter lysosome expansion in HIV-associated dementia. 1601 Jan 64