Deficiency of density-dependent regulation of cell growth in the culture of skin fibroblasts from patients with mucolipidosis III

Connective tissue naevus with pseudo-Hurler polydystrophy

We report a 39-year-old patient with a huge connective tissue naevus on his back, in association with pseudo-Hurler polydystrophy (mucolipidosis III). As far as we are aware, this is the first report of the coexistence of these two rare conditions. The lesional skin was composed of densely packed, coarse collagen fibres, which were immunohistochemically found to consist of type I, type III and type VI collagens. The amount of elastic fibres was moderately reduced. The glycosaminoglycan content of lesional skin was similar to that in a normal control. Activities of several glycosidases were markedly decreased in cultured fibroblasts.

Biochemical and immunohistochemical studies on overgrown gingival tissues associated with mannosidosis

The gingival tissues of a male patient suffering from mannosidosis and presenting with gingival overgrowth have been studied. Routine histological assessment highlighted the presence of highly enlarged and vacuolated lymphocytes. The morphology of the connective tissues, fibroblasts and epithelium appeared normal. Immunohistochemical staining of the tissues for chondroitin sulfate proteoglycan demonstrated a normal distribution of this component throughout the connective tissues and intense staining associated with the vacuolated lymphocytes. In vitro studies indicated that fibroblasts isolated from the overgrown tissue did not differ from age and sex matched control fibroblasts with respect to proliferation, protein and proteoglycan synthesis. Taken together, these findings imply that the gingvial overgrowth noted in this patient was not due to a defect in the resident fibroblasts but rather reflected a secondary response to the tissues to impaired host defence mechanisms.

Sulfated proteoglycans synthesized by Neuro 2a neuroblastoma cells: comparison between cells with and without ganglioside-induced neurites

Mouse neuroblastoma Neuro 2a cells are known to extend neurite-like processes in response to gangliosides added to the culture medium. We compared the structural features of proteoglycans (PG) synthesized by conventional Neuro 2a cells with those of neurite-bearing cells. Two different proteoglycans labeled with [35S]sulfate, namely, chondroitin sulfate proteoglycan (CS-PG) and heparan sulfate proteoglycan (HS-PG), were found both in the cell layer and in the culture medium of the conventional cells. CS-PG isolated from the cell layer had a Kav value of 0.38 on Sepharose CL-6B, and had CS side chains with Mr of 27,000. HS-PG in the cell layer was slightly larger (Kav of 0.33) in terms of hydrodynamic size than CS-PG, and the apparent Mr of the heparan sulfate side chains was 10,000. The structural parameters of CS-PG and HS-PG isolated from the medium were almost identical to those of the PGs in the cell layer. In addition to these PGs, single-chain HS, with an average Mr of 2,500, was observed only in the cell layer and this component was the major sulfated component in the cell layers of both control and ganglioside treated cells. The neurite-bearing cells also synthesized both CS-PG and HS-PG which were very similar in hydrodynamic size to those synthesized by the conventional cells, but the size of HS side chains was greater. Radioactivity, as 35S, of each sulfated component from the ganglioside-treated culture seemed to be slightly less than that of the corresponding component from the control culture. These findings indicate that the marked morphological change in Neuro 2a cells, induced by gangliosides is not accompanied by major changes in the synthesis of PGs.