Dimethylmethylene blue-based spectrophotometry of glycosaminoglycans in untreated urine: a rapid screening procedure for mucopolysaccharidoses.

Abstract

Glycosaminoglycans (GAGs) are measured in urine to screen for mucopolysaccharidoses. Other assay procedures are only qualitative (spot tests), can give false-negative results (spot tests, turbidity tests), or are relatively laborious (uronic acid-carbazole test). The present spectrophotometric procedure, based on the color reaction with dimethylmethylene blue (DMB), can be performed directly on untimed urine samples without prior precipitation. Reference values were age dependent. We tested urines of 27 patients with various mucopolysaccharidoses and compared results by three other procedures (cetylpyridinium chloride turbidity tests at pH 4.8 and at pH 7.0, and the uronic acid-carbazole test). In the DMB assay, GAGs were increased in 26 of the 27 patients. The exception was a Morquio A patient, whose activity of the defective enzyme was higher than in classical Morquio patients. Uronic acid, measured in precipitated GAG by the carbazole test, was increased in 23 of the 25 patients so tested. In the turbidity test at pH 7.0, values were increased in 24 of the 27 patients. In contrast, with the citrate-buffered (pH 4.8) turbidity measurement, GAG content was increased in only 19 of the 27 patients. This rapid and easy DMB method is a reliable screening procedure for mucopolysaccharidoses and compares well with procedures used hitherto.

Genistein supplementation in patients affected by Sanfilippo disease

“…The concentration of urinary glycosaminoglycans was determined using spectrophotometric procedures (DMB assay) based on the color reaction with 1,9-dimethylmethylene blue as previously reported (de Jong et al 1989(de Jong et al , 1992Colome Mallolas et al 1999) The Wilcoxon paired data test was used for comparison between baseline and after 1 year of treatment. Statistical significance was considered as p<0.05.…”

The characterization of a murine model of mucopolysaccharidosis II (Hunter syndrome)

“…GAG concentration in urine and tissue extracts was quantified by a colorimetric assay using 1,9-dimethylmethylene blue (DMB) dye (de Jong et al 1989(de Jong et al , 1992 and a standard curve (1.56-25 2g/ml) was prepared from dermatan sulfate (MP Biomedicals, Aurora, OH, USA). GAG concentrations in urine were adjusted for creatinine to compensate for differences in kidney function and expressed as 2g GAG/mg creatinine.…”

Interference of an algal nutritional supplement with a urinary metabolic screening test for glycosaminoglycans in a dog suspected to have a storage disease

“…A urinary GAG test using dimethylmethylene blue, a reaction based upon a color change from blue to lilac when increased GAG are present, was highly positive and suggestive of MPS (Figure ). A one‐dimensional cellulose acetate electrophoresis of the isolated urinary GAG stained with toluidine blue revealed bands migrating in the same regions as dermatan sulfate and chondroitin sulfate, consistent with a tentative diagnosis of MPS I, II, or VI (Figure ) .…”