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Mast Cell Mediators and their Effect on Airway Smooth Muscle
Published in Devendra K. Agrawal, Robert G. Townley, Inflammatory Cells and Mediators in Bronchial Asthma, 2020
Mast cells contain the acid hydrolases β-hexosaminidase, β-glucuronidase, β-D-galactosidase, and arylsulfatase. These enzymes may be important in degrading glycoproteins and proteoglycans and, in the case of arylsulfatase, hydrolyzing p-nitrocatechol sulfates. The role of these enzymes in airway muscle tone and the pathogenesis of asthma is unclear, but likely of little importance in comparison to other mast cell mediators.
Maroteaux-Lamy disease/mucopolysaccharidosis VI/N-acetylgalactosamine-4-sulfatase deficiency
Published in William L. Nyhan, Georg F. Hoffmann, Aida I. Al-Aqeel, Bruce A. Barshop, Atlas of Inherited Metabolic Diseases, 2020
N-acetylgalactosamine-4-sulfatase catalyzes the hydrolysis of the sulfate from moieties of N-acetylgalactosamine-4-sulfate which occur in dermatan sulfate. The moieties are also found in chondroitin-4-sulfate. Defective activity in this hydrolysis may account for some of the abnormalities in the joints, but chondroitin sulfate is not found in the urine because it can be degraded by hyaluronidase. The enzyme is also known as arylsulfatase B. The human enzyme has been purified [37, 38]. Its biosynthesis and processing involve the phosphorylation of mannose moieties and proteolysis in the classic lysosomal enzyme pattern [39, 40].
Metabolism of Chemical Carcinogens by Intestinal Tissue
Published in Herman Autrup, Gary M. Williams, Experimental Colon Carcinogenesis, 2019
Figure 3 presents the relative metabolic profile of organosoluble BP metabolites in human colon, duodenum, bronchus, and esophagus. Certain qualitative differences occurred among these organs. A lower level of tetrols was observed in colon and duodenum when compared to the other tissues. This indicates less activation of BP 7,8-diol to BP diol epoxides. A relatively higher amount of 3-hydroxy BP in colon and duodenum indicates a lower capability for conjugation in the intestinal tissues. Thus, only 10 to 40% of the metabolites were water soluble, the sulfate esters being the major conjugation products in colon and duodenum.90 Treatment of the sulfate and the glucuronide fractions with arylsulfatase and glucuronidase, respectively, released most of the primary metabolites.90 The phenols were primarily sulfate conjugates, while quinones and tetrols were preferentially conjugated with glucuronic acid.90 No correlation between the level of binding to DNA and any single or combination of BP metabolites was found in colon and duodenum in a study of 15 cases.91
Novel chorioretinal findings in two siblings with mucopolysaccharidosis type VI
Published in Ophthalmic Genetics, 2022
Tanya Kowalski, Sarah Donoghue, Gerard de Jong, Heather G. Mack
The Mucopolysaccharidoses are a collection of clinically distinct syndromes grouped together under this nomenclature as they each result from specific genetically defined alterations in the biochemical processing of glycosaminoglycans (GAG). Mucopolysaccharidosis type VI (MPS VI, Maroteaux-Lamy syndrome, OMIM # 253,200) is an autosomal recessive lysosomal storage disorder caused by genetic variants in the arylsulfatase B (ARSB) gene on chromosome 5q14. The arylsulfatase B enzyme is responsible for processing the residues at the ends of dermatan sulfate and chondroitin 4-sulfate by hydrolysing the C4 ester linkage in the N-acetylgalactosamine 4-sulfate residues at the non-reducing end of the GAG (1). Deficiency of ARSB enzyme activity in MPS VI patients leads to the accumulation of partially degraded GAGs dermatan sulfate and chondroitin-4 sulfate. Accumulation of these intermediate breakdown products in the lysosomes of tissues in multiple organ systems causes cellular and structural damage by a number of mechanisms including inflammatory cascades through the activation of the Toll-like receptor-4 (2).
Atypical and ultra-rare Usher syndrome: a review
Published in Ophthalmic Genetics, 2020
Rosalie M. Nolen, Robert B. Hufnagel, Thomas B. Friedman, Amy E. Turriff, Carmen C. Brewer, Christopher K. Zalewski, Kelly A. King, Talah T. Wafa, Andrew J. Griffith, Brian P. Brooks, Wadih M. Zein
Another putative USH gene is ARSG (arylsulfatase G), which encodes a member of a class of enzymes called sulfatases, which are responsible for hydrolyzing ester sulfate bonds and which are implicated in a wide variety of biochemical processes (101). It catalyzes an important step in the breakdown of heparan sulfate (97). Khateb et al. identified a homozygous pathogenic variant in ARSG in patients clinically diagnosed with atypical USH presenting as a retinal degeneration involving a ring scotoma and moderate to severe SNHL (53). It is noteworthy that the patients were also found to have a normal metabolic and neurological function. The authors also demonstrated that the ARSG variant they identified nearly abolishes all enzyme function and that ARSG is expressed in the human retina. Homozygous Arsg knockout mice displays retinal degeneration as well as behavioral dysfunction indicative of systemic effects (97,98).
Gallbladder Papilloma in a Child Unmasking Metachromatic Leukodystrophy: A Case Report With Review of Literature
Published in Fetal and Pediatric Pathology, 2019
Marwa Abdel Aziz, Mostafa Kotb, Yasmine Abdelmeguid, Sameh Shehata, Mona Abdel-Hadi
MLD is a lysosomal storage disease with an autosomal recessive pattern of inheritance. It can be diagnosed by demonstrating the reduced arylsulfatase A activity in peripheral blood leukocytes or detection of sulfatides in urine. However, the development of a screening test is challenging due to the instability of the enzyme in dried blood spots, the frequent occurrence of pseudodeficiency alleles, and the lack of available samples of urine from newborn screening programs [3]. According to the age of onset, it has three forms; late infantile, juvenile, and adult forms with the late infantile being the most common [4]. Its manifestations are attributed to deficiency of arylsulfatase A enzyme responsible for catalyzing the lysosomal breakdown of sulfatides into galactocerebrosides and sulfate. Therefore, in MLD, sulfatides accumulate mainly in lysosomes of oligodendrocytes and Schwann cells leading to progressive demyelination and subsequent motor dysfunction, convulsions and sometimes mental deterioration. These symptoms are often observed in the first two years of life, as in the present case. Sulfatides also accumulate in other organs including the gallbladder, liver, kidneys, pancreas, adrenals, and ovaries [5].