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Biomedical subjects

J Hopwood

Publications and source records attributed to J Hopwood.

29 records · Page 2Linked to original sources
PubMed1992

The iduronate sulfatase gene: isolation of a 1.2-Mb YAC contig spanning the entire gene and identification of heterogeneous deletions in patients with Hunter syndrome.

A recently isolated cDNA clone from the iduronate sulfatase (IDS) gene has been used both to seed a contig of overlapping yeast artificial chromosomes (YACs) and to investigate the molecular defect in patients with Hunter syndrome (MPS II). Six YAC clones were found to span the IDS gene, and those and 14 other YACs were assembled into a 1.2-Mb contig around the gene in Xq27-q28. The physical map of the region identifies several putative CpG islands, suggesting the presence of other genes in the vicinity. DNA from a patient with a translocation breakpoint in the gene also permitted the orientation of the contig in the chromosome. Southern analysis of DNA from 25 unrelated Italian Hunter syndrome patients revealed 4 with deletions or rearrangements in the IDS gene.

Blotting, Southern↗
PubMed1991

Mucopolysaccharidosis VI (Maroteaux-Lamy syndrome). An intermediate clinical phenotype caused by substitution of valine for glycine at position 137 of arylsulfatase B.

The Maroteaux-Lamy syndrome (mucopolysaccharidosis type VI) is a lysosomal storage disease with autosomal recessive inheritance caused by deficiency of the enzyme arylsulfatase B. Severe, intermediate, and mild forms of the disease have been described. The molecular correlate of the clinical heterogeneity is not known at present. To identify the molecular defect in a patient with the intermediate form of the disease, arylsulfatase B mRNA from his fibroblasts was reverse-transcribed, amplified by the polymerase chain reaction, and subcloned. Three point mutations were detected by DNA sequence analysis, two of which, a silent A to G transition at nucleotide 1191 and a G to A transition at nucleotide 1126 resulting in a methionine for valine 376 substitution, were polymorphisms. A G to T transversion at nucleotide 410 causing a valine for glycine 137 substitution (G137V) was identified as the mutation underlying the Maroteaux-Lamy phenotype of the patient, who was homozygous for the allele. The kinetic parameters of the mutant arylsulfatase B enzyme toward a radiolabeled trisaccharide substrate were normal excluding an alteration of the active site. The G137V mutation did not affect the synthesis but severely reduced the stability of the arylsulfatase B precursor. While the wild type precursor is converted by limited proteolysis in late endosomes or lysosomes to a mature form, the majority of the mutant precursor was degraded presumably in a compartment proximal to the trans Golgi network and only a small amount escaped to the lysosomes accounting for the low residual enzyme activity in fibroblasts of a patient with the juvenile form of the disease.

Alleles↗
PubMed1986

The histological and ultrastructural features of the epiphyseal plate in Morquio type A syndrome (mucopolysaccharidosis type IVA).

Tissue from the epiphyseal plate of a patient with Morquio type A syndrome (mucopolysaccharidosis type IVA) was studied by undecalcified histological and electron microscopical techniques. Cartilage cells in the plate were vacuolated to a variable degree. The orderly proliferating structure of the epiphyseal plate was absent and calcification was markedly reduced. The related bone tissue was morphologically normal although reduced in quantity.

Adolescent↗
PubMed1983

A rapid four column purification of 2-deoxy-D-glucoside-2-sulphamate sulphohydrolase from human liver.

2-Deoxy-D-glucoside-2-sulphamate sulphohydrolase was extracted from human liver and purified 40 000-fold by a simple four column procedure. The purification was followed using a specific substrate isolated from an acid hydrolysate of heparin, O-(alpha-2-sulphamino-2-deoxy-D-glucopyranosyl)-(1 leads to 3)-L-[6,3H]idonic acid. Only one form of the enzyme was seen on either ion exchange chromatography or isoelectric focussing, with a pI of 6.8. The apparent Mr of the holoenzyme as determined by gel filtration was 190 000 +/- 20 000. Two other larger Mr protein peaks observed on gel filtration appear to be an inactive dimer of the 190 000 dalton peak and a larger aggregate near the exclusion limit of the column. On polyacrylamide disc gel electrophoresis in sodium dodecyl sulphate, with or without prior reduction, each protein peak from the gel filtration column electrophoresed as a single major band with an apparent Mr corresponding to 55 000 +/- 6000.

Chromatography, Gel↗
PubMed1975

Stimulation of synthesis of free chondroitin sulfate chains by beta-D-xylosides in cultured cells.

Beta-Xylosides stimulate 2- to 6-fold the synthesis of glycosaminoglycans by three types of nonconnective tissue cells (RG-C6, NB41A, and rat hepatoma cells, and normal and simian virus 40 (SV40)-transformed normal human skin fibroblasts. The effect, which is specific for the anomeric linkage and the glycone, is observed in the presence and absence of puromycin. Beta-Xylosides may substitute for xylosylated core protein as initiators of synthesis of chondroitin sulfate chains. No stimulation of synthesis of heparan sulfate was observed. With the use of a fluorogenic xyloside, 4-methylumbelliferyl-beta-D-xyloside, it was demonstrated that the free chondroitin sulfate chains secreted into the medium bear the xyloside at the reducing end, and have an average molecular weight of 16,500.

Animals↗
PubMed1967

A rat chamber and electrode procedure for avoidance conditioning.

A method was developed for studying the reactions of rats to aversive shock. The distinctive features were the design of the chamber and a method of restraint that allowed the use of surface electrodes to deliver the shock. Advantages of this method were: (1) accurate specification of the shock actually received by the rat; (2) elimination of all unauthorized escape or avoidance reactions; (3) elimination of the shock scramblers and floor grids required with foot-shock; and, (4) rapid acquisition of performance under various avoidance procedures and various frequencies of shock delivery.

Animals↗