Hepatic acid mucopolysaccharides in the mucopolysaccharidoses type I, II and 3

Nodular lesions of choroid plexus in Hurler disease

Neuropathologic examination of six brains from children with Hurler disease revealed nodular lesions in the glomus of choroid plexus caused by proliferation of vacuolated pericytes, fibroblasts, and arachnoid cells on the background of collagenized and myxoid stroma. This localization of lesions can be explained by the presence of a rich vascular network, as well as cellular heterogeneity greater in the glomus than in other parts of the choroid plexus or in the brain parenchyma. The development of nodules did not correlate with the age, severity of hydrocephalus, or the degree of expansion of the perivascular spaces in the brain.

Ultrastructural and biochemical aspects of the Sanfilippo syndrome,--type III genetic mucopolysaccharidosis

The Sanfilippo Syndrome (SS) is a recessively inherited connective tissue disorder expressed in early life. It is classified as a genetic mucopolysaccharidosis (MPS) because the underlying defect involves the catabolism of heparan sulfate (HS), one of the glycosaminoglycans (GAG). Four variant forms, i.e., type A, B, C, and D, each associated with a different enzymatic defect, have been recognized in affected children. Biochemical studies show that characteristically HS accounts for most of the increased amounts of GAG excreted in the urine and those stored in viscera and brain. Gangliosides GM2, GM3 and GD2 are elevated considerably in the brain. Morphologically, the very water-soluble substances accumulating in the viscera are metachromatic, and consist ultrastructurally of finely granulo-floccular (or filamentous) material which is bound in cytoplasmic vacuoles. These substances are considered to represent the GAG. In the central nervous system (CNS) the stored substances are not soluble in water or alcohol and xylol, give a PAS-positive reaction, and stain for lipids and with luxol fast blue. Ultrastructurally, they consist of membranous arrays which often are of the "zebra body" variety. The CNS-inclusions are considered to represent the stored gangliosides; they were found also in small numbers in viscera of older children with SS. The search for a common denominator in the pathogenetic mechanism(s) culminating in both types of inclusions, continues.

Two cases of mucopolysaccharidosis type III (Sanfilippo). A biochemical study

The mucopolysaccharide and lipid composition of human nervous tissue and viscera from one case of Sanfilippo disease type A and one case of Sanfilippo disease type C, were investigated. In the brain a moderate increase of acid glycosaminoglycans occurred. This phenomenon was much more pronounced in the viscera, especially in the liver. In all tissues this increase was mainly due to an accumulation of heparan sulphate. Changes in lipid composition were noted, but can be regarded as secondary effects. The biochemical results reported also suggest some general conclusions. (a) AGAG and lipid analyses do not permit differentiation between the subtypes of Sanfilippo disease. (b) The differences in lipid composition can probably be considered as consequences of variation in secondary effects. (c) The severe demyelination in brain correlates well with the biochemical lipid analysis. However, in other instances it remains difficult to bridge the gap still existing between some morphological and biochemical data.

Further studies on hepatic acidic glycosaminoglycans in the Hurler syndrome

Acid GAG were isolated from hepatic tissue from 3 patients with Hurler syndrome and 3 normal controls. Gross elevations in the uronic acid and hexosamine contents were found in Hurler livers compared with the normal ones. The total GAG concentration was significantly increased (about 25fold) in Hurler patients.

Defective heparan sulfate metabolism in the Sanfilippo syndrome and assay of this defect in the assessment of the mucopolysaccharidoses patient

The Sanifilippo syndrome is an inherited dementia caused by defective degradation of heparan sulfate. In the course of its catabolism the heparan sulfate polymer must be desulfated. Heparan sulfate sulfatase activity was demonstrated in homogenates of normal tissues and cultured skin fibroblasts, and in normal urine. This activity was found to be grossly depressed or absent in necropsy specimens of liver and spleen from two Sanfilippo patients. The heparan sulfate sulfatase activity was not demonstrable in urine from eleven, or cultured fibroblasts from four Sanfilippo patients. Activities of alpha-N-acetyl-glucosaminidase, the site of the metabolic defect in the Sanfilippo B variant were either normal or slightly elevated in the Sanfilippo tissues and cultured fibroblasts whereas the mean level in the urine of our Sanfilippo patients was about one-third of that encountered in control urines.