Health promotion practices of the old-old

Normal pregnancy is characterized by increased in vivo thrombin generation. A greater proportion of endogenously generated thrombin is complexed to heparin cofactor II in plasma from pregnant women compared to plasma from nonpregnant ones. The increase in thrombin-heparin cofactor II complexes suggests that the site of the additional thrombin generation is relatively rich in dermatan sulfate. We postulated that the site of thrombin generation may be the placenta since endogenous thrombin generation returns rapidly to normal after delivery. This report describes the isolation and characterization of placental dermatan sulfate proteoglycan from villous tissue of the term human placenta. Placental dermatan sulfate was isolated by guanidine HCI extraction and anion exchange chromatography. The isolated material was found to have anticoagulant activity with a relative activity of approximately 40% of that of a porcine mucosal dermatan sulfate which is undergoing clinical trial as an antithrombotic agent. The dermatan sulfate was present as a proteoglycan with a molecular mass of 90-150 kD. Upon degradation with chondroitin ABC lyase, the core protein was demonstrated to be a doublet with molecular masses of 42 and 44 kD. This core protein reacted with antiserum against the core protein of decorin on Western analysis. The role of this placental dermatan sulfate in local regulation of thrombin in the placenta warrants further study.     

Purification of chondroitin 6-sulfotransferase secreted from cultured chick embryo chondrocytes

Chondroitin 6-sulfotransferase, which transfers sulfate from 3'-phosphoadenylyl sulfate to position 6 of N-acetylgalactosamine in chondroitin, was purified 1,430-fold to apparent homogeneity with a 22% yield from the serum-free culture medium of chick embryo chondrocytes by affinity chromatography on heparin-Sepharose CL-6B, wheat germ agglutinin-agarose, and 3',5'-ADP-agarose. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the purified enzyme showed a single broad protein band with an apparent molecular weight of 75,000. Since the purified enzyme has an apparent molecular weight of 160,000 as judged by gel chromatography on Superose 12, the active form of chondroitin 6-sulfotransferase may be a dimer. The purified enzyme transferred sulfate to chondroitin, chondroitin sulfate, and corneal keratan sulfate. Chondroitin sulfate E from squid cartilage, dermatan, sulfate, and heparan sulfate hardly served as acceptors of the sulfotransferase. The sulfated product derived from keratan sulfate was degraded by keratanase but not by chondroitinase ABC.     

Purification and characterization of chondroitin 4-sulfotransferase from the culture medium of a rat chondrosarcoma cell line

Chondroitin 4-sulfotransferase, which transfers sulfate from 3'-phosphoadenosine 5'-phosphosulfate to position 4 of N-acetylgalactosamine in chondroitin, was purified 1900-fold to apparent homogeneity with 6.1% yield from the serum-free culture medium of rat chondrosarcoma cells by affinity chromatography on heparin-Sepharose CL-6B, Matrex gel red A-agarose, 3',5'-ADP-agarose, and the second heparin-Sepharose CL-6B. SDS-polyacrylamide gel electrophoresis of the purified enzyme showed two protein bands. Molecular masses of these protein were 60 and 64 kDa under reducing conditions and 50 and 54 kDa under nonreducing conditions. Both the protein bands coeluted with chondroitin 4-sulfotransferase activity from Toyopearl HW-55 around the position of 50 kDa, indicating that the active form of chondroitin 4-sulfotransferase is a monomer. Dithiothreitol activated the purified chondroitin 4-sulfotransferase. The purified enzyme transferred sulfate to chondroitin and desulfated dermatan sulfate. Chondroitin sulfate A and chondroitin sulfate C were poor acceptors. Chondroitin sulfate E from squid cartilage, dermatan sulfate, heparan sulfate, and completely desulfated N-resulfated heparin hardly served as acceptors of the sulfotransferase. The transfer of sulfate to the desulfated dermatan sulfate occurred preferentially at position 4 of the N-acetylgalactosamine residues flanked with glucuronic acid residues on both reducing and nonreducing sides.     

A histochemical study on the acidic glycoconjugates of the synovial membrane in rheumatoid arthritis

The localization and the nature of glycosaminoglycans (GAGs) in the synovial membrane in 30 patients with rheumatoid arthritis (RA) involving 40 knees were studied by newly developed histochemical methods. To detect the acidic glycoconjugates, sensitized diamine procedures were employed based upon high and low iron diamine stainings. To identify the various molecular species of the GAGs, enzyme (chondroitinase ABC and B, testicular hyaluronidase and keratanase) digestion and chemical modification (nitrous acid treatment) procedures were performed prior to the diamine stainings. The sensitized diamine methods could clearly stain the acidic glycoconjugates contained in the synovial tissue components in shades of brown to black, and could detect the precise distribution patterns of the GAGs. The results obtained in the present study confirmed that the tissue in RA synovial membranes contained various amounts of each GAG molecular species such as dermatan sulfate, chondroitin sulfate A/C, hyaluronic acid and heparan sulfate. Furthermore, the distribution patterns of dermatan and chondroitin sulfates in the diseased synovial tissues were pathophysiologically interesting; in the inflammatory areas, the molecular species of GAGs was primarily dermatan sulfate, whereas in the fibrotic areas, it was mainly chondroitin sulfate A/C. Such results appear to be useful for pathophysiological studies on the synovial tissues of RA.     

Isolation and characterization of chondroitin sulfate proteoglycans from embryonic quail that influence neural crest cell behavior

The movement of neural crest cells is controlled in part by extracellular matrix. Aggrecan, the chondroitin sulfate proteoglycan from adult cartilage, curtails the ability of neural crest cells to adhere, spread, and move across otherwise favorable matrix substrates in vitro. Our aim was to isolate, characterize, and compare the structure and effect on neural crest cells of aggrecan and proteoglycans purified from the tissues through which neural crest cells migrate. We metabolically radiolabeled proteoglycans in E2.5 quail embryos and isolated and characterized proteoglycans from E3.3 quail trunk and limb bud. The major labeled proteoglycan was highly negatively charged, similar in hydrodynamic size to chick limb bud versican/PG-M, smaller than adult cartilage aggrecan but larger than reported for embryonic sternal cartilage aggrecan. The molecular weight of the iodinated core protein was about 400 kDa, which is more than reported for aggrecan but less than that of chick versican/PG-M. The proteoglycan bore chondroitin sulfate glycosaminoglycan chains of 45 kDa, which is larger than those of aggrecan. It lacked dermatan sulfate, heparan sulfate, or keratan sulfate chains. It bound to collagen type I, like aggrecan, but not to fibronectin (unlike versican/PG-M), collagen type IV, or laminin-1 in solid-phase assays and it bound to hyaluronate in gel-shift assays. When added at concentrations between 10 and 30 microg/ml to substrates of fibronectin, trunk proteoglycan inhibited neural crest cell spreading and migration. Attenuation of cell spreading was shown to be the most sensitive and titratable measure of the effect on neural crest cells. This effect was sensitive to digestion with chondroitinase ABC. Similar cell behavior was also produced by aggrecan and the small dermatan sulfate proteoglycan decorin; however, 30-fold more aggrecan was required to produce an effect of similar magnitude. When added in solution to neural crest cells which were already spread and migrating on fibronectin, the embryonic proteoglycan rapidly and reversibly caused complete rounding of the cells, being at least 30-fold more potent than aggrecan in this activity.     

Purification and characterization of heparan sulfate 2-sulfotransferase from cultured Chinese hamster ovary cells

Heparan sulfate 2-sulfotransferase, which catalyzes the transfer of sulfate from adenosine 3'-phosphate 5'-phosphosulfate to position 2 of L-iduronic acid residue in heparan sulfate, was purified 51,700-fold to apparent homogeneity with a 6% yield from cultured Chinese hamster ovary cells. The isolation procedure included a combination of affinity chromatography on heparin-Sepharose CL-6B and 3',5'-ADP-agarose, which was repeated twice for each, and finally gel chromatography on Superose 12 . Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the purified enzyme showed two protein bands with molecular masses of 47 and 44 kDa. Both proteins appeared to be glycoproteins, because their molecular masses decreased after N-glycanase digestion. When completely desulfated and N-resulfated heparin and mouse Engelbreth-Holm-Swarm tumor heparan sulfate were used as acceptors, the purified enzyme transferred sulfate to position 2 of L-iduronic acid residue but did not transfer sulfate to the amino group of glucosamine residue or to position 6 of N-sulfoglucosamine residue. Heparan sulfates from pig aorta and bovine liver, however, were poor acceptors. The enzyme showed no activities toward chondroitin, chondroitin sulfate, dermatan sulfate, and keratan sulfate. The optimal pH for the enzyme activity was around 5.5. The enzyme activity was minimally affected by dithiothreitol and was stimulated strongly by protamine. The Km value for adenosine 3'-phosphate 5'-phosphosulfate was 0.20 microM.     

Modulation of cAMP-dependent protein kinase by derivatives of chondroitin sulfate

Here, we report investigations about the direct effect of glycosaminoglycans, such as dermatan sulfate, chondroitin 4- and 6-sulfate upon cAMP-dependent protein kinase activity. The results indicate that glycosaminoglycans strongly influence the phosphorylation activity of this enzyme against histone type IIa and [Val6, Ala7]-kemptide. While chondroitin 4-sulfate and dermatan sulfate exhibit inhibitory effects, chondroitin 6-sulfate shows a stimulating effect. In addition, the chondroitin 6-sulfate is also able to reduce the chondroitin 4-sulfate and dermatan sulfate specific inhibition.     

Isolation and characterization of a proteoglycan variant from human aorta exhibiting a marked affinity for low density lipoprotein and demonstration of its enhanced expression in atherosclerotic plaques

Proteoglycans (PG) are implicated in the pathophysiology of atherosclerosis due to their ability to complex with plasma low density lipoproteins (LDL). Studies were conducted to determine whether human aorta contains PG subclasses that exhibit enhanced LDL binding ability. PG were isolated from normal and atherosclerotic aortas by a combination of dissociative extraction and ion-exchange chromatography. The PG were further subfractionated on an LDL affinity column based on their binding affinity to LDL. Two PG fractions exhibiting high-affinity binding to LDL, as evidenced by their elution at 1.0 and 1.5 M NaCl, respectively, were isolated from both normal and atherosclerotic tissue. Compared with normal tissue, atherosclerotic tissue showed a twofold increase in the high-affinity PG that eluted at 1.5 M NaCl. Gel filtration of the high-affinity PG from normal tissue yielded two peaks (nPG2 and nPG3), while the high-affinity PG from plaque tissue was resolved into three peaks (pPG1, pPG2, and pPG3). pPG1 eluted at the void volume of the column, indicating that it was of very large molecular size. The hydrodynamic size of pPG2 was larger than that of the corresponding nPG2 (Kav = 0.44 versus 0.51), while pPG3 had the same hydrodynamic size as nPG3 (Kav = 0.86). The high-affinity PG subfractions from normal aorta contained varying proportions of chondroitin sulfates, dermatan sulfates, and heparan sulfate. In contrast, the PG subfractions from plaque tissue contained predominantly chondroitin sulfates and heparan sulfate. In vitro complexes of LDL and the high-affinity PG fractions from normal aorta and plaque tissue stimulated cholesteryl ester synthesis in human monocyte-derived macrophages. However, the LDL-plaque PG complex was significantly more potent than the LDL-normal aorta PG complex in this respect. These results indicate that PG subclasses with enhanced binding affinity to LDL occur in the normal human aorta and that their concentration increases significantly in atherosclerotic lesions. In addition, the high-affinity PG in plaque tissue have altered characteristics and increased ability to stimulate LDL-mediated cholesterol ester synthesis in macrophages. This could lead to increased lipid deposition during atherogenesis.     

Extraction, purification and evaluation of structures and physico-chemical properties of glycosaminoglycans

Heparin was extracted and purified from beef intestinal mucosa. The two components, fast moving heparin and slow moving heparin were purified by selective precipitation as barium salts. Heparan sulfate was extracted and purified from beef spleen. Dermatan sulfate was purified from beef intestinal mucosa and chondroitin sulfate from bovine trachea. The purity of the purified glycosaminoglycans was evaluated by agarose-gel and cellulose polyacetate electrophoresis and by specific optical rotation. The relative molecular masses of glycosaminoglycans were estimated by high performance-size exclusion chromatography and the sulfate to carboxyl ratio by titrimetric analysis. The disaccharide pattern of heparin, fast moving and slow moving heparins and heparan sulfate were determined by specific enzymatic cleavage using heparinase I, II and III; the disaccharide composition of dermatan sulfate and chondroitin sulfate was evaluated by cleavage by chondroitinase ABC. The disaccharides obtained by enzymatic cleavage were qualitatively and quantitatively analysed by strong anion exchange-high performance liquid chromatography. The sulfate to carboxyl ratios of glycosaminoglycans were also determined by this technique and compared with the values obtained by titrimetric analysis.     

Demonstration of anionic sites in human eccrine and apocrine sweat glands in post-embedded ultra-thin sections with cationic colloidal gold: effect of enzyme digestion on these anionic sites

We localized anionic sites ultrastructurally in human eccrine and apocrine sweat glands with a poly-L-lysine-gold complex (cationic colloidal gold). Anionic sites were labeled by incubating Lowicryl K4M-embedded sections on droplets of cationic colloidal gold. In eccrine sweat glands, colloidal gold particles were restricted to the basolateral membrane of the secretory cells at low pH, whereas the luminal membrane did not react with the gold particles. Chondroitinase ABC digested these anionic sites. This indicates that chondroitin sulfate and/or dermatan sulfate constitutes anionic sites in the basal labyrinth of eccrine sweat glands. In apocrine sweat glands, the luminal membrane of the secretory cells showed strong reaction at low pH, whereas the contraluminal membrane did not show any reaction. Neuraminidase completely digested these anionic sites, which indicated that the anionic charge of the apocrine lumen was due to sialic acid. Differences in distribution and susceptibility to enzymes of anionic sites in cell membranes between eccrine and apocrine sweat glands may reflect functional differences between these glands. Dark cell granules in eccrine secretory cells were negative for the anionic sites when sections were labeled without any pre-treatment. However, pre-incubation of the grids on EGTA or deionized water unmasked the anionic sites on the dark cell granules. The positive staining after EGTA treatment was greatly decreased by reincubation with CaCl2. These results suggested that Ca blocked anionic sites in dark cell granules. Exposed anionic sites were digested with chondroitinase ABC. This indicated that chondroitinase ABC and/or dermatan sulfate composed the anionic sites in dark cell granules.     

Interferon-gamma inhibits 35S incorporation in heparan sulfate synthesized by human skin fibroblasts

Glycosaminoglycans synthesized by human skin fibroblasts were simultaneously radiolabelled with D-[1-(3H)]glucosamine and Na2(35)SO4. Considering 3H incorporation, we found that IFNgamma increased the production of glycosaminoglycan synthesis, including hyaluronic acid, heparan and chondroitin/dermatan sulfate. In contrast, the production of heparan and chondroitin/dermatan sulfate was slightly decreased on the basis of the 35S signal. Furthermore, when heparan sulfate was treated with nitrous acid, the release of free 35S was greater in control than in treated cells, although the 3H patterns of depolymerization with this agent were similar. These data demonstrate that IFNgamma inhibits the incorporation of sulfate from extracellular medium into heparan sulfate.     

Age-related changes in populations of aortic glycosaminoglycans: species with low affinity for plasma low-density lipoproteins, and not species with high affinity, are preferentially affected

Glycosaminoglycans were extracted from the intima and media layers of normal human thoracic aortas from donors of different ages. The arterial segments were devoid of macroscopically visible lesions obtained from patients who had no clinically evident cardiovascular disease. Total glycosaminoglycan content increases during the first 40 years of life. Changes in the content of hyaluronic acid and heparan sulfate are less noticeable. The content of chondroitin sulfate (mainly the 6-isomer) increases, whereas dermatan sulfate remains constant. Plasma LDL-affinity chromatography of dermatan sulfate+chondroitin 4/6-sulfate fractions allowed the separation of LDL high- and low-affinity glycosaminoglycan species. Remarkably, only glycosaminoglycan species with low affinity for plasma LDL increase with age in the disease-free areas of human thoracic aortas studied. These results suggest that age-related changes in glycosaminoglycan composition of the arterial wall do not contribute to increased deposition of plasma LDL. However, the alternative explanation that individuals with arterial glycosaminoglycans that avidly bind LDL would develop early and severe cardiovascular disease and would thus be excluded from our analysis cannot be ruled out.     

Dermatan sulfate proteoglycans from the mineralized matrix of the avian eggshell

The eggshell of the chicken is a useful model to study matrix components which affect biomineralization. As an extension of our previous immunohistochemical work which suggested the presence of dermatan sulfate proteoglycans in the mineralized region of the eggshell, a study was undertaken to characterize these molecules biochemically. After demineralization with HCl and extraction with 4 M guanidinium chloride containing protease inhibitors, the extract was partitioned by anion exchange chromatography. Step elution with 0.25 M and 1.0 M sodium chloride resulted in the generation of two fractions, both of which contain chondroitinase-sensitive proteoglycans with molecular weights estimated at 200,000 by gel electrophoresis. The proteoglycans in each fraction have core proteins with molecular weights of approximately 120,000 and glycosaminoglycans with average molecular weights of 22,000. Based on differential sensitivity to chondroitinase ABC and AC II, these glycosaminoglycans contain a small proportion of dermatan sulfate. The disaccharide compositions of these glycosaminoglycans differ for the proteoglycans eluted with 0.25 M and 1.0 M sodium chloride. Those eluted with lower sodium chloride are enriched in unsulfated chondroitin and have much more 4-sulfated than 6-sulfated disaccharides; those eluted with 1.0 M sodium chloride contain primarily 4-sulfated disaccharides, a small amount of 6-sulfated disaccharides, and less unsulfated disaccharides than the proteoglycans eluted with 0.25 M sodium chloride. The large difference in the proportions of unsulfated chondroitin may be the reason for the elution at different sodium chloride concentrations. Both of the anion exchange column fractions contain other proteins in addition to the proteoglycans. These proteins are not separated from the proteoglycans by a second anion exchange column or by molecular sieve chromatography under dissociative conditions. Of particular interest is the observation that the eggshell proteoglycans and their core proteins are recognized by a monoclonal antibody which recognizes an epitope on the core protein of avian versican. This suggests that, in spite of the large differences in the sizes of the core proteins of versican and the eggshell proteoglycans, these core proteins share some homology. Because anionic molecules are thought to be important regulators of biomineralization, and because preparations like those analyzed in this study have been shown to influence in vitro calcium carbonate crystallization, the eggshell proteoglycans may play a role in eggshell mineralization.     

Biochemical characterization of the Golgi-complex proteins of Tritrichomonas foetus

Using cell-fractionation techniques (differential and discontinuous gradient centrifugation), we obtained a highly enriched fraction containing the Golgi complex of Tritrichomonas foetus. This fraction was further subfractionated by sodium carbonate (150 mM) treatment at pH 11.5, leading to the isolation of the Golgi content and membrane subfractions. Both fractions were characterized by electron microscopy. The protein content of membrane and luminal subfractions was about 40% and 60% of the total Golgi protein, respectively. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis showed an enrichment of 15 protein bands in the Golgi fraction, with molecular masses varying between 15 and 116 kDa. Alkaline treatment released some proteins into the medium, but most of them were associated with the Golgi membrane.     

Glycosaminoglycan specificity of a heparin-binding peptide

Glycosaminoglycans are complex sulfated polysaccharides with a diverse range of biological functions. Three glycosaminoglycan standards--chondroitin sulfate, dermatan sulfate and heparin--were characterized during this study. The interaction of the heparin binding site of protein C inhibitor, represented by the peptide sequence 264-283, in solution with the above glycosaminoglycan standards was studied. Circular dichroism spectroscopy was used to determine the dominant secondary structure induced in the peptide upon binding the relevant glycosaminoglycans. The various glycosaminoglycans induced different secondary structures. The level of induced secondary structure by dermatan sulfate and heparin was approximately twice that induced by chondroitin sulfate. For chondroitin sulfate and heparin, alpha-helix was the dominant ordered secondary structure, whereas for dermatan sulfate the beta-strand conformation dominated. The order of secondary structure induction of the protein C inhibitor peptide by the glycosaminoglycans paralleled the reported biological activities of these glycosaminoglycans for mediation of the biological activity in the intact protein. The strength of the interaction of dermatan sulfate and heparin with the protein C inhibitor peptide was measured by determining the concentration of salt required to inhibit 50% of the interaction. The values determined were 0.1 and 0.3 M salt for dermatan sulfate and heparin, respectively. These results show that different glycosaminoglycans can support different secondary structures in the protein C inhibitor peptide.     

Prognostic significance of coronary flow reserve on left ventricular ejection fraction in cardiac transplant recipients

In each of 30 skeletally mature sheep, the posterior cruciate ligament was replaced in one knee by a free patellar tendon autograft using the central third of the ipsilateral patellar tendon. The healing autograft was compared with the contralateral posterior cruciate ligament and the patellar tendons and posterior cruciate ligaments of nonoperated animals. The content of glycosaminoglycans, chondroitin sulfate disaccharides, and dermatan sulfate disaccharides was assessed biochemically at six periods during the 2 years after surgery. The total glycosaminoglycans and chondroitin sulfate disaccharides in the native posterior cruciate ligament was threefold that in the native patellar tendon. In contrast, the amount of dermatan sulfate disaccharides was similar in both the native tendon and native ligament. In the autograft, glycosaminoglycans and chondroitin sulfate disaccharides increased significantly to about 144% and 172%, respectively, of the contralateral posterior cruciate ligament at Week 104. The dermatan sulfate disaccharides in the autograft also showed a significant increase up to Week 26, followed by a remarkable but not significant decrease until the end of the study. In the contralateral posterior cruciate ligament, the dermatan sulfate disaccharides increased significantly between Weeks 52 and 104. Thus, the amount of dermatan sulfate disaccharides was similar in both the autograft and the contralateral posterior cruciate ligament after 2 years. This study suggests that the patellar tendon autograft did not completely assume the biochemical properties of the posterior cruciate ligament.     

Changes in glycosaminoglycan characteristics during progression of a human gingival carcinoma xenograft line in nude mice

We investigated changes in the glycosaminoglycans (GAGs) during progression of a human gingival carcinoma xenograft line, GK -1, in nude mice. The GAGs extracted from cancers 3, 5, 7, 10 and 15 weeks after transplantation consisted of hyaluronic acid (HA), chondroitin sulfate (CS) and heparan sulfate (HS) as major components, and dermatan sulfate (DS) as a trace component for all cancers. HPLC analysis revealed that the HA content per defatted tissue dry weight increased in the cancers 5 weeks after transplantation compared to those of 3 weeks (p < 0.05), while CS for cancers at 10 weeks decreased compared with 7 weeks (p < 0.05). However, HS showed no significant change. Both the CS and DS contained primarily 4-sulfated disaccharide units. Immunohistochemical staining with antibody 2-B-6 for the PGs having delta DI-4S produced by chondroitinase ABC digestion showed that CS is located in the tissue surrounding the cancer nests and mass. These results indicate that the location of accumulation of CS, which primarily contains 4-sulfated disaccharide units, plays an important role in cancer progression.     

Eating disturbances and outcome of gastric bypass surgery: a pilot study

Fucan, a sulfated polysaccharide extracted from brown seaweeds, inhibits smooth muscle cell (SMC) proliferation with a higher antiproliferative activity than heparin (Logeart et al., Eur. J. Cell Biol. 74, 1997, this issue). In order to investigate the structure-activity relationship of fucan on SMC growth, we have prepared by size exclusion chromatography fucan fractions of various molecular masses ranging from 5.5 to 556 kDa. Our experiments showed that the antiproliferative activity is dependent on the molecular weight of the polysaccharide. The molecular weight threshold indicated that about 30 saccharidic units on fucan were necessary to give the antiproliferative activity on SMCs. A kinetics study of DNA synthesis using tritiated thymidine uptake was also performed with different molecular weight fucan fractions. Although all tested fractions acted as soon as the cells enter the first cell cycle, the duration and potency of action varied. Moreover, displacement experiments of iodinated fucan revealed that the low molecular fucan fraction interacted weakly with the binding sites. Finally, gel permeation chromatography of internalized radiolabeled heparin and fucans was performed with SMCs. A rapid degradation of internalized heparin was observed, whereas only low molecular weight fucan fractions were partially degraded by SMCs. Together, these results indicate the significance of molecular weight on the antiproliferative activity of fucans on SMCs, and might help to understand their mechanism of action. In addition, the degradation experiments with internalized heparin and fucans ruled out a direct link between polysaccharide degradation and the antiproliferative effect on SMCs.     

Proteoglycans from bovine proximal humeral articular cartilage. Structural basis for the polydispersity of proteoglycan subunit

Polydisperse proteoglycan subunit from bovine proximal humeral articular cartilage has been separated into a series of relatively monodisperse fractions which have been chemically and physically characterized. The proteoglycan subunit species of the lowest molecular weight contains the least chondroitin sulfate and had an amino acid composition relatively low in serine and glycine and relatively high in cysteine, methionine, and aspartic acid, almost identical to that of the hyaluronic acid-binding region of proteoglycan subunit isolated by Heinegard and Hascall (Heinegard, D., and Hascall, V.C. (1974) J. Biol. Chem. 249, 4250-4256). The molecular weight of proteoglycan subunit increases in proportion to its chondroitin sulfate content. As the molecular weight and chondroitin sulfate content of proteoglycan subunit increase, there is a parallel increase in the serine and glycine contents, and a decrease in the cysteine, methionine, and aspartic acid contents of proteoglycan subunit core protein. The pattern of polydispersity observed strongly supports the concept that proteoglycan subunit core protein contains a hyaluronic acid-binding region of constant size and composition and a polysaccharide attachment region of variable length and composition, composed of repeating peptide sequences containing serine and glycine in equimolar amounts.     

Prospective study of the significance of contact sensitization caused by metal implants

Cell nuclei of mouse hepatoma contain various proteoglycans (PG) which include heparan sulfate proteoglycan (HS-PG), dermatan sulfate proteoglycan (DS-PG), and chondroitin sulfate proteoglycan (CS AC-PG). The latter is not found in cell nuclei of normal mouse liver. Heparan sulfate (HS) and dermatan sulfate (DS) are the main constituents of carbohydrate chains of nuclear proteoglycans of tumor and normal cells, respectively. Changes in the composition of nuclear PG during malignant transformation are discussed considering the concept of their possible involvement in the regulation of cell mitotic activity.