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Biomedical subjects

J S O'Brien

Publications and source records attributed to J S O'Brien.

At least 163 records · Page 9Linked to original sources
PubMed1976

Clinical and biochemical expression of a unique mucopolysaccharidosis.

A boy who presented with painful joints leading to contractures was found to have a mucopolysaccharidosis not previously described. He had severe dysostosis multiplex of the long bones but nearly normal intellectual development and no involvement of the cornea. Lysosomal storage vacuoles were noted in dermal endothelial cells; these were similar to those seen in the genetic mucopolysaccharidoses. Mucopolysacchariduria was not excessive in amount but it was distinctly abnormal in pattern and his excretion of dermatan sulfate resembled that found in the Hunter and Hurler syndromes. The activities of the lysosomal hydrolases in cultured fibroblasts were normal or increased. The degradation of accumulated 35S-mucopolysaccharide in fibroblasts in culture was typical of a mucopolysaccharidosis. His mother accumulated 35S-mucopolysaccharides in fibroblasts, suggesting an X-linked inheritance of the disorder.

Child↗
PubMed1975

Human liver alpha-L-fucosidase. Purification, characterization, and immunochemical studies.

Human liver alpha-L-fucosidase has been purified 6300-fold to apparent homogeneity with 66% yield by a two-step affinity chromatographic procedure utilizing agarose epsilon-aminocaproyl-fucosamine. Isoelectric focusing revealed that all six isoelectric forms of the enzyme were purified. Polyacrylamide gel electrophoresis of the purified alpha-L-fucosidase demonstrated the presence of six bands of protein which all contained fucosidase activity. The purified enzyme preparation was found to contain only trace amounts of seven glycosidases. Quantitative amino acid analysis was performed on the purified fucosidase. Preliminary carbohydrate analysis indicated that only about 1% of the molecule is carbohydrate. Gel filtration on Sepharose 4B indicated an approximate molecular weight for alpha-L-fucosidase of 175,000 +/- 18,000. High speed sedimentation equilibrium yielded a molecular weight of 230,000 +/- 10,000. Sodium dodecyl sulfate polyacrylamide gels indicated the presence of a single subunit of molecular weight, 50,100 +/- 2,500. The enzyme had a pH optimum of 4.6 with a suggested second optimum of 6.5. Apparent Michaelis constants and maximal velocities were determined on the purified enzyme with respect to the 4-methylumbelliferyl and the p-nitrophenyl substrates and were found to be 0.22 mM and 14.1 mumol/mg of protein/min and 0.43 mM and 19.6 mumol/mg of protein/min, respectively. Several salts had little or no effect on fucosidase activity although Ag+ and Hg2+ completely inactivated the enzyme. Antibodies made against the purified fucosidase were dound to be monospecific against crude human liver supernatant fluids and the pure antigen. No cross-reacting material was detected in the crude liver supernatant fluid from a patient who died with fucosidosis.

Amino Acids↗
PubMed1975

Lysosomal storage disorders. Diagnosis by ultrastructural examination of skin biopsy specimens.

Fifteen patients with lysosomal storage diseases were studied. Diagnoses of their illnesses included infantile Gaucher disease; Krabbe disease; Niemann-Pick disease, type A; glycogen storage disease, type 3; Fabry disease, Jansky-Bielschowsky and Spielmeyer-Vogt types of amaurotic idiocy, GM1 gangliosidosis, type 1; Hurler disease; and Sanfilippo disease, types A and B. We carried out ultrastructural examinations of skin biopsy specimens that were taken to establish a cultured fibroblast line on each patient. We found diagnostic storage inclusions in all patients except those with infantile Gaucher disease, Krabbe disease, and Spielmeyer-Vogt disease, This technique can be carried out on a specimen obtained by a primary physician on an out-patient basis, thus avoiding major surgery.

Adolescent↗
PubMed1975

An electrophoretic variant of beta-galactosidase with altered catalytic properties in a patient with GM1 gangliosidosis.

In nine patients with GM1 gangliosidosis, liver ganglioside GM1 beta-galactosidase (EC 3.2.1.23) activity ranged from less than 0.01% to 0.05% of normal. In a tenth patient's liver, much higher activity was found (0.5% of normal). In this patient the residual enzyme had the same molecular weight as beta-galactosidase A, the major form of beta-galactosidase of normal human liver. No activity was found that corresponded to beta-galactosidase B, the minor form of human liver beta-galactosidase. On starch gel electrophoresis, the patient's enzyme migrated less anodally than normal beta-galactosidase A, both before and after treatment with neuraminidase. Beta-Galactosidase from the patient had a Km that was higher then normal; 5-fold higher with ganglioside GM1 and 2-fold higher with 4-methylumbelliferyl beta-galactoside. The patient's enzyme crossreacted immunologically with normal beta-galactosidase A and had about 100-fold more antigenic activity per unit catalytic activity than the normal enzyme. The results indicate that in this patient a beta-galactosidase A protein with altered charge and altered catalytic properties was present in relatively normal amounts, the first electrophoretic variant reported for a patient with a lysosomal hydrolase deficiency.

Brain↗
PubMed1975

Characterization of beta-D-galactosidase isolated from I-cell disease liver.

The residual beta-D-galactosidase activity (10% of normal) present in an autopsy sample of liver derived from an I-cell patient has been characterized. The pH optima for both I-cell and normal acid 4-methylumbelliferyl beta-D-galactoside activities were 4.35. The adsorption and elution profiles of the I-cell enzyme from Con A-Sepharose were similar to those of normal liver beta-D-galactosidase. Although starch gel electrophoresis revealed the presence of beta-D-galactosidase A and B in I-cell disease liver, the A band was more diffuse and migrated less anodally than the A band from normal liver. The electrophoretic mobilities of both I-cell and normal beta-D-galactosidase A appeared to decrease after treatment with neuraminidase. Kinetic studies of the I-cell and normal level beta-D-galactosidase demonstrated similar apparent Km values with respect to the 4-methylumbelliferyl beta-D-galactoside and Gm1 ganglioside, whereas the Vmax values obtained for the I-cell enzyme were 10- to 12-fold lower than those of the normal enzyme for both substrates.

Autopsy↗
PubMed1975

Molecular genetics of GM1 beta-galactosidase.

The molecular genetics of GM1 beta-galactosidase is reviewed. This enzyme exists in two forms, A and B. Form A is monomeric with a molecular weight of 72,000 and appears to be coded by a single autosomal locus. Form B is polymeric and cross-reacts with anti-A antibodies; it is coded wholly or in part by the same locus that codes for A. The simultaneous loss of A and B in GM1 gangliosidosis is explained. None of the other beta-galactosidases, including neutral beta-galactosidase, ceramide lactoside beta-galactosidase or cerebroside beta-galactosidase cross-react with anti-A antibodies, demonstrating that they are coded by loci separate from A. GM1 beta-galactosidase A is heterocatalytic, cleaving beta-D-galactose from ganglioside GM1, lactose, N-acetyllactosamine, and galactose-containing glycoproteins such as asialofetuin, red cell stromal glycoproteins and keratan sulfate. The pleotropic effects of a single mutation affecting the locus for beta-galactosidase A can be explained by a one gene:one polypeptide:many substrates model. Phenotypic variability among beta-galactosidase A mutants may result from better residual activity of the mutant enzyme for one substrate than for another. Patients with normal intelligence and severe bony deformities, who are homozygous for a mutation affecting the enzyme, illustrate this point. Thus far all human mutants for GM1 beta-galactosidase studied are structural mutants, synthesizing nearly normal quantities of mutant enzyme; one is a proven Km mutant, the others are very likely so.

Chromosome Aberrations↗