Albert Dorfman

Nature of the collagen synthesized by a transplanted chondrosarcoma

Abstract A chondrosarcoma grown in rats was found to produce a single kind of collagen. This collagen was identified as a type II collagen, the cartilage specific protein.

The role of hyaluronic acid in intercellular adhesion of cultured mouse cells.

Abstract Aggregation of cultured mouse cells was measured by the rate of disappearance of particles from a suspension of single cells. Treatment with several enzymes which degrade hyaluronic acid (testicular hyaluronidase, streptomyces hyaluronidase, streptococcal hyaluronidase and chondroitinase ABC) inhibited the aggregation of SV-3T3 and several other cell types. Since streptomyces and streptococcal hyaluronidases are specific for hyaluronic acid, it is suggested that hyaluronic acid is involved in the observed aggregation. Hyaluronidase-induced inhibition of aggregation was complete in the absence of divalent cations, but only partial in their presence. This finding is consistent with the hypothesis that two separate mechanisms are responsible for aggregation; one dependent upon and the other independent of calcium and magnesium. Aggregation was also inhibited by high levels of hyaluronic acid. A similar effect was obtained with fragments of hyaluronic acid consisting of six sugar residues or more. Chondroitin (desulfated chondroitin 6-sulfate) and to a lesser extent desulfated dermatan sulfate also inhibited aggregation. Other glycosaminoglycans (chondroitin 4-sulfate, chondroitin 6-sulfate, heparin and heparan sulfate) had little or no effect on aggregation. It is suggested that the hyaluronic acid inhibits aggregation by competing with endogenous hyaluronic acid for cell surface binding sites.

A micromethod for the colorimetric determination of N-acetyl groups in acid mucopolysaccharides.

Abstract Deacetylation of mucopolysaccharides and other N-acetylated compounds with 2 N HCl-methanol is a useful and simple procedure for determining N-acetyl groups in these compounds. The acetyl groups are converted to methyl acetate which is colorimetrically determined as a hydroxamic-ferric complex. This method permits the determination of N-acetyl groups in a range of 1 to 10 μmoles and is more sensitive than previously described methods. The reproducibility and some of the factors affecting the deacetylation and colorimetric analysis have been studied.

The acid mucopolysaccharides in normal urine

Abstract 1. 1. The purpose of this investigation is to report the qualitative distribution of acid munopolysaccharides in normal urine and the composition of a mucopeptide isolated from urine. 2. 2. The predominant mucopolysaccharides in normal urine are a family of chondrotin sulfates characterized by a varying sulfate content. Chondroitin sulfate A and chondroitin sulfate C each constitute about one-third of the total mucopolysaccharide, while chondroitin (non-sulfated chondroitin sulfate) constitutes one-fourth of the total mucopolysaccharide. 3. 3.Heparitin monosulfate makes up approx. 8% of the total mucopolysaccharide excreted. Hyaluronic acid, chondroitin sulfate B, and a highly sulfated keratosulfate are excreted in trace amounts. 4. 4. Monosulfated chrondroitin sulfate, as found in normal urine, is extracted as fragments of small molecular size, some of which are covalently bound to a polypeptide characterized by a high serine, glycine and glutamic acid content.

Morquio's syndrome: Deficiency of a chondroitin sulfate N-acetylhexosamine sulfate sulfatase

Abstract The Morquio syndrome is a spondyloepiphyseal dysplasia characterized by excretion in urine of excessive amounts of keratan sulfate and chondroitin sulfate. To investigate the enzymic basis of this disease, assays for sulfatase were performed using chick embryo chondroitin sulfate and rat chondrosarcoma chondroitin 4-sulfate as substrates. The data obtained, using skin fibroblasts as an enzyme source, indicate that Morquios syndrome is a deficiency of chondroitin sulfate N-acetylhexosamine sulfate sulfatase.

Hurler's syndrome, an a-L-iduronidase deficiency

Abstract The activity of a-L-iduronidase was found to be deficient in extracts prepared from livers, cultured fibroblasts and urine of patients with Hurlers syndrome. Extracts from livers and fibroblasts of Hunters and Sanfilippos syndromes did not show such a deficiency. There was a diminution of activity in extracts of “I-cell” fibroblasts. a-L-Iduronidase is believed to be the underlying enzymic defect of Hurlers disease.

The biosynthesis of chondroitin sulfate

Abstract A particulate enzyme preparation from embryonic chick cartilage catalyzes incorporation of radioactivity from UDP-GalNAc- 3 H or UDP-Glc-UA- 14 C into chondroitin sulfate. In the absence of added oligosaccharide acceptor, incorporation of radioactivity from either nucleotide required the presence of the alternate unlabeled nucleotide. Addition of a sulfated or nonsulfated hexasaccharide derived from chondroitin sulfate (nonreducing terminal glcUA) stimulated incorporation of radioactivity from UDP-GalNAc- 3 H in the absence of UDP-GlcUA, but not from UDP-GlcUA- 14 C in the absence of UDP-GalNAc. In contrast, the addition of nonsulfated pentasaccharide (nonreducing terminal galNAc) did not stimulate the incorporation of radioactivity from UDP-GalNAc- 3 H in the absence of UDP-GlcUA, but did stimulate incorporation of radioactivity from UDP-GlcUA- 14 C in the absence of UDP-GalNAc. The radioactive product of this reaction was characterized as a nonsulfated hexasaccharide with a radioactive nonreducing terminal glcUA. The sulfated pentasaccharide did not accept glcUA- 14 C or galNAc- 3 H from the appropropriate nucleotide.

Biosynthesis of glycosphingolipids by mouse neuroblastoma (nb41a), rat glia (rgc-6) and human glia (chb-4) in cell culture.

Summary A mouse neuroblastoma cell line was found to synthesize at least four of the gangliosides characteristic of nervous tissue, G M2 , G M1 , G D2 and G D1a . Since hematoside (G M3 ) is virtually absent from the neuroblastoma cell line, the data suggest that asialo-G M2 is an intermediate in the synthesis and catabolism of gangliosides. Glial tumor cell lines of both rat and human origin contained mainly G M3 (90% of the total glycolipid content) and negligible amounts of hexosamine-containing glycosphingolipids.

Effect of the thyroid gland on metabolism of acid mucopolysaccharides in skin

In skin of hypothyroid rats, the concentration of hyaluronic acid is increased whereas that of chondroitinsulfuric acid is decreased. These changes are prevented or reversed toward normal by the administration of thyroxine. The effects of hypothyroidism on mucopolysaccharide metabolim appear to be the result of a deficiency of thyroid hormone rather than an excess of circulating thyrotropic hormone.

L-iduronidase in cultured human fibroblasts and liver☆

Abstract Extracts of normal human livers and skin fibroblasts cultured from normal individuals and patients with the Hurler syndrome released L-iduronic acid when incubated with desulfated dermatan sulfate. Enzyme extracts of normal fibroblasts liberated larger amounts of L-induronic acid, as judged by paper chromatography, than did homogenates from Hurler fibroblasts. Preliminary studies with desulfated heparan sulfate using the same enzyme systems have also shown material with the Rf of iduronolactone on paper chromatography.