Room temperature strong coupling in a semiconductor microcavity with embedded AlGaAs quantum wells designed for polariton lasing

We report a systematic study of the temperature and excitation density behavior of an AlAs/AlGaAs, vertically emitting microcavity with embedded ternary Al_0.20Ga_0.80As/AlAs quantum wells in the strong coupling regime. Temperature-dependent photoluminescence measurements of the bare quantum wells indicate a crossover from the type-II indirect to the type-I direct transition. The resulting mixing of quantum well and barrier ground states in the conduction band leads to an estimated exciton binding energy systematically exceeding 25 meV. The formation of exciton-polaritons is evidenced in our quantum well microcavity via reflection measurements with Rabi splittings ranging from (13.93 ± 0.15) meV at low temperature (30 K) to (8.58 ± 0.40) meV at room temperature (300 K). Furthermore, the feasibility of polariton laser operation is demonstrated under non-resonant optical excitation conditions at 20 K and emission around 1.835 eV.

EJ-ras oncogene transfection of endothelial cells upregulates the expression of syndecan-4 and downregulates heparan sulfate sulfotransferases and epimerase

The EC rabbit endothelial cell line was transfected with the EJ-ras oncogene (EJ-ras EC). EJ-ras EC cells display over expression of the Ras oncogene, morphological changes and deregulation of the cell cycle, becoming more densely populated and serum-independent. In addition, EJ-ras-transfectant cells show higher levels of the syndecan-4 mRNA. In addition to the increase in the core protein, a parallel increase in the glycosylation of the syndecan-4 protein, a proteoglycan that bears heparan sulfate chains, also occurs. This increase is observed both for the heparan sulfate proteoglycan synthesized by the cells and for that secreted to the culture medium. This enhancement in heparan sulfate synthesis was observed through metabolic labeling of the cells, immunoprecipitation of syndecan-4 and heparitinases treatment. Furthermore, the EJ-ras-transfectant cells do not exhibit decreased synthesis of heparan sulfate during the G(1)-S phase transition, as observed for the parental cell line. Also, heparan sulfate synthesis is not stimulated by PMA as displayed by parental endothelial cells. Significant structural changes of heparan sulfate, such as decreased O-sulfation, were observed in the EJ-ras-transfected cells. Decreases in the mRNA levels of some enzymes (glucuronosyl C-5 epimerase, iduronosyl-2-O-sulfotransferase, glucosaminyl-6-O-sulfotransferase-1 and N-deacetylase/N-sulfotransferase-1), involved in the biosynthetic pathway of heparan sulfate, were also observed. The results suggest that overexpression of the EJ-ras oncogene alters the cell cycle, through signal transduction cascades, upregulates the expression of syndecan-4, and downregulates enzymes involved in the heparan sulfate biosynthesis related to chain modification, leading to the structural changes of the heparan sulfate syndecan-4 proteoglycan in endothelial cells.

Specific structural features of syndecans and heparan sulfate chains are needed for cell signaling

The syndecans, heparan sulfate proteoglycans, are abundant molecules associated with the cell surface and extracellular matrix and consist of a protein core to which heparan sulfate chains are covalently attached. Each of the syndecan core proteins has a short cytoplasmic domain that binds cytosolic regulatory factors. The syndecans also contain highly conserved transmembrane domains and extracellular domains for which important activities are becoming known. These protein domains locate the syndecan on cell surface sites during development and tumor formation where they interact with other receptors to regulate signaling and cytoskeletal organization. The functions of cell surface heparan sulfate proteoglycan have been centered on the role of heparan sulfate chains, located on the outer side of the cell surface, in the binding of a wide array of ligands, including extracellular matrix proteins and soluble growth factors. More recently, the core proteins of the syndecan family transmembrane proteoglycans have also been shown to be involved in cell signaling through interaction with integrins and tyrosine kinase receptors.

Glycosaminoglycans affect the interaction of human plasma kallikrein with plasminogen, factor XII and inhibitors

Human plasma kallikrein, a serine proteinase, plays a key role in intrinsic blood clotting, in the kallikrein-kinin system, and in fibrinolysis. The proteolytic enzymes involved in these processes are usually controlled by specific inhibitors and may be influenced by several factors including glycosaminoglycans, as recently demonstrated by our group. The aim of the present study was to investigate the effect of glycosaminoglycans (30 to 250 micro/ml) on kallikrein activity on plasminogen and factor XII and on the inhibition of kallikrein by the plasma proteins C1-inhibitor and antithrombin. Almost all available glycosaminoglycans (heparin, heparan sulfate, bovine and tuna dermatan sulfate, chondroitin 4- and 6-sulfates) reduced (1.2 to 3.0 times) the catalytic efficiency of kallikrein (in a nanomolar range) on the hydrolysis of plasminogen (0.3 to 1.8 microM) and increased (1.9 to 7.7 times) the enzyme efficiency in factor XII (0.1 to 10 microM) activation. On the other hand, heparin, heparan sulfate, and bovine and tuna dermatan sulfate improved (1.2 to 3.4 times) kallikrein inhibition by antithrombin (1.4 microM), while chondroitin 4- and 6-sulfates reduced it (1.3 times). Heparin and heparan sulfate increased (1.4 times) the enzyme inhibition by the C1-inhibitor (150 nM).

Enzyme and integrin expression by high and low metastatic melanoma cell lines

Dissemination of a malignant tumour is the result of a cascade of events beginning with detachment of cells from primary tumour followed by extravasation and growth at secondary sites. The differences in metastatic ability could be attributed to properties intrinsic to the various tumour types. Thus the clonal selection of tumour cells from successive metastases apparently results in cells better equipped for survival and formation of colonies in secondary sites, indicating that survival is not a random phenomenon. Many studies of malignant cells have correlated the overexpression of adhesion receptors such as integrins and the production of cysteine proteases and glycosidases with the progression of malignancy. The interaction of cysteine proteases with basement membrane components has been implicated in tumour invasion, activation of hormones and growth factors. On the other hand, the expression of the heparanase gene and its protein has been associated with the metastatic potential of several human and mouse tumour cell lines. This study aimed to investigate the correlations between the metastatic properties of clones with high and low metastatic potential and their ability to adhere to the extracellular matrix and to degrade proteins and sulphated glycosaminoglycans present there. Clonal selection of the B16F10 cell line was performed, and the clones were examined for the expression of an integrin-type laminin receptor. A significantly higher level was detected in a high metastatic clone. Enzymatic assays showed higher activity for alpha-d-N-acetylglucosaminidase, beta-d-N-acetylgalactosaminidase and beta-d-glucuronidase in conditioned medium from low metastatic clones compared with that from high metastatic clones. However, higher endopeptidase activity was observed in conditioned medium from high metastatic clones. In summary, these results showed a positive correlation between high metastatic potential and endopeptidase secretion. Similarly, a positive correlation was observed between low metastatic cells and the secretion of glycosaminoglycan-degrading glycosidases.

Heparan sulfate and control of cell division: adhesion and proliferation of mutant CHO-745 cells lacking xylosyl transferase

We have examined the role of cell surface glycosaminoglycans in cell division: adhesion and proliferation of Chinese hamster ovary (CHO) cells. We used both wild-type (CHO-K1) cells and a mutant (CHO-745) which is deficient in the synthesis of proteoglycans due to lack of activity of xylosyl transferase. Using different amounts of wild-type and mutant cells, little adhesion was observed in the presence of laminin and type I collagen. However, when fibronectin or vitronectin was used as substrate, there was an enhancement in the adhesion of wild-type and mutant cells. Only CHO-K1 cells showed a time-dependent adhesion on type IV collagen. These results suggest that the two cell lines present different adhesive profiles. Several lines of experimental evidence suggest that heparan sulfate proteoglycans play a role in cell adhesion as positive modulators of cell proliferation and as key participants in the process of cell division. Proliferation and cell cycle assays clearly demonstrate that a decrease in the amount of glycosaminoglycans does not inhibit the proliferation of mutant CHO-745 cells when compared to the wild type CHO-K1, in agreement with the findings that both CHO-K1 and CHO-745 cells take 8 h to enter the S phase.

Heparin and a cyclic octaphenol-octasulfonic acid (GL-522-Y-1) bind with high affinity to a 47-kda protein from vascular endothelial cell surface and stimulate the synthesis and structural changes of heparan sulfate proteoglycan

The effect of a cyclic octaphenol-octasulfonic acid (GL-522-Y-1), upon the synthesis of a heparan sulfate proteoglycan synthesized by endothelial cells (rabbit aorta and human umbilical vein) were studied. The cells were exposed to the compounds at various concentrations for different periods of time and the synthesized heparan sulfates analyzed by a combination of agarose gel electrophoresis and enzymatic degradation. The GL-522-Y-1, like heparin, change the sulfation pattern and stimulate two- to three-fold the synthesis of heparan sulfate proteoglycan secreted by rabbit and human endothelial cells in culture. GL-522-Y-1, besides being 100 times more active than heparin, also produces a significant enhancement of cell surface heparan sulfate in human vein endothelial cells. The effect of GL-522-Y-1 is completely abolished by methylation or acetylation of its free hydroxyl groups. Both heparin and GL-522-Y-1 have high affinity for a 47-kDa protein present at the surface of endothelial cells. These and other results lead us to speculate that the antithrombotic activity of heparin and GL522 "in vivo" could be related, at least in part, to the increased production of the heparan sulfate proteoglycan by endothelial cells.

Development of new heparin-like compounds and other antithrombotic drugs and their interaction with vascular endothelial cells

The anticlotting and antithrombotic activities of heparin, heparan sulfate, low molecular weight heparins, heparin and heparin-like compounds from various sources used in clinical practice or under development are briefly reviewed. Heparin isolated from shrimp mimics the pharmacological activities of low molecular weight heparins. A heparan sulfate from Artemia franciscana and a dermatan sulfate from tuna fish show a potent heparin cofactor II activity. A heparan sulfate derived from bovine pancreas has a potent antithrombotic activity in an arterial and venous thrombosis model with a negligible activity upon the serine proteases of the coagulation cascade. It is suggested that the antithrombotic activity of heparin and other antithrombotic agents is due at least in part to their action on endothelial cells stimulating the synthesis of an antithrombotic heparan sulfate.

In Vivo and In Vitro Cytotoxicity of Brown Spider Venom for Blood Vessel Endothelial Cells

The effect of brown spider (Loxosceles intermedia) venom on endothelial cells was investigated in vivo and in vitro. Morphological and ultrastructural observations by light microscopy and transmission electron microscopy showed that the venom acts in vivo upon vessel endothelial cells of rabbits that were intradermally injected, evoking vessel instability, cytoplasmic endothelial cell vacuolization, and blebs. Likewise, treatment of rabbit endothelial cells in culture with the venom led to loss of adhesion of the cells to the substrate. Endothelial cells in culture were metabolically radiolabeled with sodium [35S]-sulfate and the sulfated compounds (proteoglycans and sulfated proteins) from medium, cell surface, and extracellular matrix (ECM) were analyzed. Agarose gel electrophoresis and SDS-PAGE showed that the venom is active on the ECM and on cell surface proteoglycans, shedding these molecules into the culture medium. In addition, when purified heparan sulfate proteoglycan (HSPG) and purified laminin-entactin (LN/ET) complex were incubated with the venom we observed a partial degradation of the protein core of HSPG as well as the hydrolysis of entactin. The above results suggest that the L. intermedia venom has a deleterious effect on the endothelium of vessels both in vivo and in culture, removing important constituents such as HSPG and entactin that are involved in the adhesion of endothelial cells and of subendothelial ECM organization.

A fucan from the brown seaweed Spatoglossum schröederi inhibits Chinese hamster ovary cell adhesion to several extracellular matrix proteins

Fucans, a family of sulfated polysaccharides present in brown seaweed, have several biological activities. Their use as drugs would offer the advantage of no potential risk of contamination with viruses or particles such as prions. A fucan prepared from Spatoglossum schröederi was tested as a possible inhibitor of cell-matrix interactions using wild-type Chinese hamster ovary cells (CHO-K1) and the mutant type deficient in xylosyltransferase (CHO-745). The effect of this polymer on adhesion properties with specific extracellular matrix components was studied using several matrix proteins as substrates for cell attachment. Treatment with the polymer inhibited the adhesion of fibronectin to both CHO-K1 (2 x 10(5)) and CHO-745 (2 x 10(5) and 5 x 10(5)) cells. No effect was detected with laminin, using the two cell types. On the other hand, adhesion to vitronectin was inhibited in CHO-K1 cells and adhesion to type I collagen was inhibited in CHO-745 cells. In spite of this inhibition, the fucan did not affect either cell proliferation or cell cycle. These results demonstrate that this polymer is a new anti-adhesive compound with potential pharmacological applications.

Anticoagulant and antiprotease effects of a novel heparinlike compound from shrimp (Penaeus brasiliensis) and its neutralization by heparinase I

Heparin is usually obtained from mammalian organs, such as beef lung, beef mucosa, porcine mucosa, and sheep intestinal mucosa. Because of the increased use of heparin in the production of low-molecular-weight heparin (LMWH), there is a growing shortage of the raw material needed to produce LMWHs. A previous report described the structural features of a novel LMWH from the shrimp (Penaeus brasiliensis). In order to compare anticoagulant and antiprotease effects of this heparin, global anticoagulant tests, such as the prothrombin time, activated partial thromboplastin time, thrombin time, and Heptest, were used. Amidolytic anti-Xa and anti-IIa activities were also measured. The relative susceptibility of this heparin to flavobacterial heparinase was also evaluated. The United States Pharmacopeia (USP) potency of shrimp heparin (SH) was found to be 28 U/mg. SH produced a concentration-dependent prolongation of all of the clotting tests and exhibited marked inhibition of FXa and FIIa. Heparinase treatment resulted in a marked decrease of the anticoagulant effects and neutralized the in vitro anti-IIa actions. However, the anti-Xa activities were only partially neutralized. Protamine sulfate was only partially effective in neutralizing the anticoagulant and antithrombin effects of SH. SH also produced marked prolongation of activated clotting time, which was neutralized by heparinase but not by protamine sulfate. These results suggest that SH is a strong anticoagulant with comparable properties to mammalian heparins and can be used in the development of clinically useful antithrombotic-anticoagulant drugs.

Ultrastructural cytochemical characterization of collagen-associated proteoglycans in the endometrium of mice

The decidual reaction in mice is characterized by the transformation of a specific population of endometrial fibroblasts into epithelioid cells, known as decidual cells. An important feature of decidualization in mice is a remarkable modification of the endometrial extracellular matrix. The present work is an ultrastructural cytochemical study of matrix with the purpose of analyzing the arrangement of collagen-associated proteoglycans (PGs) at various regions of nulliparous endometrium and of the antimesometrial decidua of mice using the cationic dye cuprolinic blue associated with enzymatic treatments with chondroitinase ABC, chondroitinase AC, and hyaluronidase. The staining with cuprolinic blue showed PGs as rods and granules of several sizes. Rods measuring 40-60 nm in length (named F2-rods) were apposed to thin collagen fibrils whereas granules were associated with thick collagen fibrils, particularly in the region occupied by mature decidual cells on the 7th day of pregnancy. The amount of granules was higher than that of F2-rods. Both F2-rods and granules were affected by chondroitinase ABC or AC treatment, indicating that they were PGs containing chondroitin sulfate and dermatan sulfate chains. However, the granules associated with thick collagen fibrils were more resistant to chondroitinase AC treatment than F2-rods, indicating the presence of dermatan sulfate chains that contain both L-iduronic and D-glucuronic acid sugar residues. We suggest that the differences of the nature and amount of PGs may be associated with the changes of the thickness of collagen fibrils observed during decidualization of the endometrium in the mouse.

Distribution of sulfated glycosaminoglycans in the animal kingdom: widespread occurrence of heparin-like compounds in invertebrates

Sulfated glycosaminoglycans were isolated from 23 species of 13 phyla of invertebrates and characterized by their electrophoretic migration in three different buffer systems coupled with enzymatic degradation using bacterial heparinase, heparitinases and chondroitinase AC. Heparan sulfate is a ubiquitous compound present in all species analyzed whereas chondroitin sulfate was present in 20 species and heparin-like compounds in 12 species of the invertebrates. The heparin-like compounds were purified from the echinoderm Mellita quinquisperforata (sand dollar) and the crustacean Ucides cordatus (crab) with anticoagulant activities of 60 and 52 IU/mg, respectively. Degradation of these heparins with heparinase produced significant amounts of the trisulfated disaccharide typical of mammalian heparins. This was confirmed by 13C-NMR spectroscopy of the crab heparin. An updated phylogenetic tree of the distribution of sulfated glycosaminoglycans in the animal kingdom is also presented.

Effect of brown spider venom on basement membrane structures

Loxoscelism or necrotic arachnidism are terms used to describe lesions and reactions induced by bites (envenomation) from spiders of the genus Loxosceles. Envenomation has been reported to provoke dermonecrosis and haemorrhage at the bite site and haemolysis, disseminated intravascular coagulation and renal failure. The purpose of this work was to study the effect of the venom of the brown spider Loxosceles intermedia on basement membrane structures and on its major constituent molecules. Light microscopy observations showed that L. intermedia venom obtained through electric shock, which reproduces two major signals of Loxoscelism in the laboratory, exhibits activity toward basement membrane structures in mouse Engelbreth-Holm-Swarm (EHS) sarcoma. Basement degradation was seen by a reduced periodic acid-Schiff (PAS) and alcian blue staining as well as by a reduced immunostaining for laminin when compared to control experiments. Electron microscopy studies confirmed the above results, showing the action of the venom on EHS-basement membranes and demonstrating that these tissue structures are susceptible to the venom. Using purified components of the basement membrane, we determined through SDS-PAGE and agarose gel that the venom is not active toward laminin or type IV collagen, but is capable of cleaving entactin and endothelial heparan sulphate proteoglycan. In addition, when EHS tissue was incubated with venom we detected a release of laminin into the supernatant, corroborating the occurrence of some basement membrane disruption. The venom-degrading effect on entactin was blocked by 1, 10-phenanthroline, but not by other protease inhibitors such as PMSF, NEM or pepstatin-A. By using light microscopy associated with PAS staining we were able to identify that 1,10-phenanthroline also inhibits EHS-basement membrane disruption evoked by venom, corroborating that a metalloprotease of venom is involved in these effects. Degradation of these extracellular matrix molecules and the observed susceptibility of the basement membrane could lead to loss of vessel and glomerular integrity, resulting in haemorrhage and renal problems after envenomation.

A novel heparan sulphate with high degree of N-sulphation and high heparin cofactor-II activity from the brine shrimp Artemia franciscana

With the aid of heparinase and heparitinases from Flavobacterium heparinum and 13C and IH NMR spectroscopy it was shown that the heparan sulphate isolated from the brine shrimp Artemia franciscana exhibits structural features intermediate between those of mammalian heparins and heparan sulphates. These include an unusually high degree of N-sulphation (with corresponding very low degree of N-acetylation), a relatively high content of iduronic acid residues (both unsulphated and 2-O-sulphated) and a relatively low degree of 6-O-sulphation of the glucosamine residues. The major sequences (glucuronic acid-->N-sulphated glucosamine and glucuronic acid-->N, 6-disulphated glucosamine) are most probably arranged in blocks. Although exhibiting negligible anticlotting activity in the APTT and anti-factor Xa assays the A. franciscana heparan sulphate has a high heparin cofactor-II activity (about 1/3 that of heparin).

Patients with head and neck tumors excrete a chondroitin sulfate with a low degree of sulfation: a new tool for diagnosis and follow-up of cancer therapy

The chondroitin sulfate excreted in the urine of 10 patients with cancer of the head and neck and 27 healthy subjects was analyzed. The disaccharide products formed from chondroitin sulfate excreted by these 10 patients by action of chondroitinase ABC show a significant (P < 0.0001) relative increase of nonsulfated disaccharide (35.6% +/- 5.7%) when compared with the nonsulfated disaccharide (10.0% +/- 0.9%) present in the chondroitin sulfate of 27 healthy subjects. In 6 patients the structure of the excreted compound was analyzed up to 4 months after surgery. After removal of the cancer, the percent amounts of the nonsulfated disaccharide tend to approach the values found for the chondroitin sulfate of healthy subjects. A significant (P < 0.0001) change in the ratio of urinary chondroitin sulfate and heparan sulfate and a decrease in the electrophoretic migration of chondroitin sulfate were also observed. All of the patients with head and neck cancer analyzed so far have shown this structural anomaly of urinary chondroitin sulfate. This assay may be useful in the diagnosis and follow-up of cancer therapy.

Structural features and bleeding activity of commercial low molecular weight heparins: neutralization by ATP and protamine

Differences in the structure of three low molecular weight heparins (LMWHs) have been observed by applying physico-chemical methods as well as enzymatic degradation with bacterial heparinase and heparitinase II. The production of enoxaparin maintains the internal structure of the parent heparin with the exception of the unsaturated nonreducing end. In contrast, the production of dalteparin and nadroparin removes part of their nonsulfated uronic acid residues and, unlike enoxaparin and unfractionated heparin (UFH), these LMWHs also contain regions that remain resistant to the action of heparitinase II. Enoxaparin has a lower molecular weight distribution than dalteparin and nadroparin and is composed of at least four discrete molecular weight populations. A rat-tail model demonstrated that LMWHs applied topically or injected intravenously had a lower bleeding potency when compared with UFH treatment. The bleeding potencies of the different LMWHs were similar. Furthermore, adenosine triphosphate (ATP) completely neutralized bleeding caused by LMWHs and UFH in the animal model when applied topically and significantly reduced bleeding in heparinized surgical patients undergoing cardiopulmonary bypass surgery.

Structural features and anticoagulant activities of a novel natural low molecular weight heparin from the shrimp Penaeus brasiliensis

A natural low molecular weight heparin (8.5 kDa), with an anticoagulant activity of 95 IU/mg by the USP assay, was isolated from the shrimp Penaeus brasiliensis. The crustacean heparin was susceptible to both heparinase and heparitinase II from Flavobacterium heparinum forming tri- and di-sulfated disaccharides as the mammalian heparins. (13)C and (1)H NMR spectroscopy revealed that the shrimp heparin was enriched in both glucuronic and non-sulfated iduronic acid residues. The in vitro anticlotting activities in different steps of the coagulation cascade have shown that its anticoagulant action is mainly exerted through the inhibition of factor Xa and heparin cofactor II-mediated inhibition of thrombin. The shrimp heparin has also a potent in vivo antithrombotic activity comparable to the mammalian low molecular weight heparins.

New insights on the specificity of heparin and heparan sulfate lyases from Flavobacterium heparinum revealed by the use of synthetic derivatives of K5 polysaccharide from E. coli and 2-O-desulfated heparin

The capsular polysaccharide from E. Coli, strain K5 composed of ...-->4)beta-D-GlcA(1-->4)alpha-D-GlcNAc(1-->4)beta-D-GlcA (1-->..., chemically modified K5 polysaccharides, bearing sulfates at C-2 and C-6 of the hexosamine moiety and at the C-2 of the glucuronic acid residues as well as 2-O desulfated heparin were used as substrates to study the specificity of heparitinases I and II and heparinase from Flavobacterium heparinum. The natural K5 polysaccharide was susceptible only to heparitinase I forming deltaU-GlcNAc. N-deacetylated, N-sulfated K5 became susceptible to both heparitinases I and II producing deltaU-GlcNS. The K5 polysaccharides containing sulfate at the C-2 and C-6 positions of the hexosamine moiety and C-2 position of the glucuronic acid residues were susceptible only to heparitinase II producing deltaU-GlcNS,6S and deltaU,2S-GlcNS,6S respectively. These combined results led to the conclusion that the sulfate at C-6 position of the glucosamine is impeditive for the action of heparitinase I and that heparitinase II requires at least a C-2 or a C-6 sulfate in the glucosamine residues of the substrate for its activity. Iduronic acid-2-O-desulfated heparin was susceptible only to heparitinase II producing deltaU-GlcNS,6S. All the modified K5 polysaccharides as well as the desulfated heparin were not substrates for heparinase. This led to the conclusion that heparitinase II acts upon linkages containing non-sulfated iduronic acid residues and that heparinase requires C-2 sulfated iduronic acid residues for its activity.

Heparan sulfates and heparins: similar compounds performing the same functions in vertebrates and invertebrates?

The distribution and structure of heparan sulfate and heparin are briefly reviewed. Heparan sulfate is a ubiquitous compound of animal cells whose structure has been maintained throughout evolution, showing an enormous variability regarding the relative amounts of its disaccharide units. Heparin, on the other hand, is present only in a few tissues and species of the animal kingdom and in the form of granules inside organelles in the cytoplasm of special cells. Thus, the distribution as well as the main structural features of the molecule, including its main disaccharide unit, have been maintained through evolution. These and other studies led to the proposal that heparan sulfate may be involved in the cell-cell recognition phenomena and control of cell growth, whereas heparin may be involved in defense mechanisms against bacteria and other foreign materials. All indications obtained thus far suggest that these molecules perform the same functions in vertebrates and invertebrates.

Heparan sulfate and cell division

Heparan sulfate is a component of vertebrate and invertebrate tissues which appears during the cytodifferentiation stage of embryonic development. Its structure varies according to the tissue and species of origin and is modified during neoplastic transformation. Several lines of experimental evidence suggest that heparan sulfate plays a role in cellular recognition, cellular adhesion and growth control. Heparan sulfate can participate in the process of cell division in two distinct ways, either as a positive or negative modulator of cellular proliferation, or as a response to a mitogenic stimulus.

Oligosaccharide residues of Loxosceles intermedia (brown spider) venom proteins: dependence on glycosylation for dermonecrotic activity

Loxosceles spp. (brown spider) envenomation has been reported to provoke dermonecrosis and haemorrhage at the bite site (a hallmark of accidents) and, to a lesser extent, thrombocytopenia, hemolysis and disseminated intravascular coagulation in some cases. Using lectin-immunolabeling, lectin-affinity chromatography, glycosidase and proteinase K treatments we were able to identify several venom N-glycosylated proteins with high-mannose oligosaccharide structures, complex-type glycoconjugates such as fucosylated glycans, but no galactose or sialic acid residues as complex sugars or glycosaminoglycan residues. Working with enzymatically or chemically deglycosylated venom we found that platelet aggregation (thrombocytopenic activity) as well as the fibronectinolytic and fibrinogenolytic (haemorrhagic) effects of the venom were sugar-independent when compared to glycosylated venom. Nevertheless, zymograph analysis in co-polymerized gelatin gels showed that enzymatic N-deglycosylation of loxolysin-B, a high-mannose 32-35 kDa glycoprotein of the venom with gelatinolytic metalloproteinase activity, caused a reduction of approximately 2 kDa in its molecular weight and a reduction of the gelatinolytic effect to a residual activity of 28% when compared to the glycosylated molecule, indicating a post-translational glycosylation-dependent gelatinolytic effect. Analysis of the dermonecrotic effect of the chemically or enzymatically N-deglycosylated venom detected only residual activity when compared with the glycosylated control. Thus, the present report suggests that oligosaccharide moieties play a role in the destructive effects of brown spider venom and opens the possibility for a carbohydrate-based therapy.

Stimulation of heparan sulfate proteoglycan synthesis and secretion during G1 phase induced by growth factors and PMA

Fetal calf serum (FCS) and PMA (phorbol 12-myristate-13-acetate) specifically stimulate the synthesis of heparan sulfate proteoglycan in endothelial cells. Staurosporine and n-butanol, kinase inhibitors, abolish the PMA effect. Forskolin and 8-bromo adenosine 3':5'-cyclic monophosphate, activators of, respectively, adenylate cyclase and protein kinase A cannot reproduce the PMA effect. The kinetics of cell entry into S phase of the endothelial cells was determined by DNA synthesis ([3H]-thymidine and Br-dU incorporation), and flow cytometry. The mitogenic effect of fetal calf serum is abolished by PMA. Also, PMA pre-treatment inhibits the enhanced synthesis of heparan sulfate proteoglycan after a second PMA exposure. Remarkably, the stimulation of heparan sulfate proteoglycan synthesis by fetal calf serum and PMA seems to be mainly restricted to G1 phase. Therefore fetal calf serum and PMA cause an enhanced synthesis of heparan sulfate proteoglycan, and PMA causes a cell cycle block at G1 phase.

Structure of heparan sulfate: identification of variable and constant oligosaccharide domains in eight heparan sulfates of different origins

The use of specific enzymes (heparinase and heparitinases from Flavobacterium heparinum, endoglucuronidase, alphaN-acetylglucosaminidase and beta-glucuronidase from the mollusc Anomalocardia brasiliana) and chemical methods (nitrous acid degradation, hydrazine N-deacetylation and borohydride reduction), led to the proposal of the total sequence of a heparan sulfate derived from bovine pancreas and partial sequences of heparan sulfates from different origins (bovine: lung, liver, brain; hog: liver, brain; rabbit liver; dog liver). It was shown that all the heparan sulfates contain common structural features such as: a N-acetylated and a N-sulfated domain made of glucuronic acid-containing disaccharides and a more sulfated region made of iduronic acid-containing disaccharides. Separating the two domains a peculiar tetrasaccharide made of GlcNAc-(alpha1-4)-IdoUA-(alpha1-4)-GlcNS-(alpha1-4)-IdoUA was identified in all the heparan sulfates analyzed. It was also shown that the non-reducing ends of the heparan sulfates contain the monosaccharides glucosamine N-sulfate and/or glucosamine 2,6 disulfate.

New pathway of heparan sulphate degradation. Iduronate sulphatase and N-sulphoglucosamine 6-sulphatase act on the polymer chain prior to depolymerisation by a N-sulpho-glucosaminidase and glycuronidases in the mollusc Tagelus gibbus

It has previously been shown that in the mollusc Anomalocardia brasiliana the desulphation of chondroitin sulphate precedes its depolymerisation by beta-glucuronidase and beta-N-acetylgalactosaminidase (Sousa Jr. et al. J. Biol. Chem. 1990;265:20150-20155). This led us to investigate whether in molluscs, sulphatases also act on heparan sulphate before its depolymerisation by glycosidases. Radioactively labelled [35S]heparan sulphate was extensively degraded by enzyme extracts prepared from the mollusc Tagelus gibbus. Several enzymes acting in concert degrade the compound to inorganic sulphate, glucosamine N-sulphate, N-acetylglucosamine-6 sulphate and other oligosaccharide products. These results indicate the presence of iduronate sulphatase, N-sulphoglucosamine 6-sulphatase alpha-N-sulphoglucosaminidase, beta-glucuronidase and alpha-L-iduronidase. The di- and mono-saccharide composition of the oligosaccharides were analysed with the aid of heparitinase II from Flavobacterium heparinum. These analyses led to the characterisation of two sulphatases that act on the polymer chain removing sulphates from the C-2 position of iduronic acid residues and the C-6 position of the glucosamine moieties, respectively. The different enzymes were partially fractionated by ion exchange chromatography and molecular sieving. These results led to the proposition of a new pathway of degradation of heparan sulphate where sulphatases act directly on the polymer chain which is then depolymerised by several glycosidases.

Uncoupling of actomyosin adenosinetriphosphatase by heparin and its fragments

Heparin and its enzymatic fragments, prepared by degradation of heparin with heparinase from Flavobacterium heparinum, were capable of inhibiting the actomyosin-ATPase activity obtained from striated and smooth vascular muscles. Heparin did not inhibit the myosin-ATPase activity in absence of actin. The results show that heparin changes the step of ATP hydrolysis of the complex actomyosin-ATPase by uncoupling the conformational transition on the myosin-head induced by actin upon the nucleotide-binding site. This mechanism is cooperative and dependent on conformational states of actomyosin complex which in turn is regulated by ATP and calcium levels. It was observed that in the presence of ATP, actin does not compete with heparin for binding to myosin showing that heparin and actin have different binding sites on myosin. The binding of heparin and ATP is cooperative suggesting that the nucleotide binding leads to an exposition of a second heparin-binding site. However, in the absence of ATP, actin competes with heparin for a binding site on the myosin. These results strongly suggest that in the weakly binding state of actin to myosin, the binding of heparin is powerful and in the rigor state its binding is decreased.

Differences in the nonreducing ends of heparan sulfates excreted by patients with mucopolysaccharidoses revealed by bacterial heparitinases: a new tool for structural studies and differential diagnosis of Sanfilippo's and Hunter's syndromes

Enzymatic and chemical analyses of the structures of heparan sulfates excreted in the urine by patients with Sanfilippo's and Hunter's syndromes revealed that their nonreducing ends differ from each other and reflect the enzyme deficiency of the syndromes. The heparan sulfates from the different syndromes were treated with heparitinase II, crude enzyme extracts from Flavobacterium heparinum, and nitrous acid degradation. The heparan sulfates from patients with Sanfilippo A (deficient in heparan N-sulfatase) and Sanfilippo B (deficient in alpha-N-acetylglucosaminidase) were degraded with heparitinase II producing, besides unsaturated disaccharides, substantial amounts of glucosamine N-sulfate and N-acetylglucosamine, respectively. The heparan sulfate from patients with Hunter's syndrome (deficient in iduronate sulfatase) were degraded by heparitinase II or crude enzyme extracts to several products, including two saturated disaccharides containing a sulfated uronic acid at their nonreducing ends. The heparan sulfate from patients with Sanfilippo's C syndrome (deficient in acetyl Co-A: alpha-glucosaminide acetyltransferase) produced, by action of heparitinase II, among other products, two sulfated trisaccharides containing glucosamine with a nonsubstituted amino group. In addition to providing a new tool for the differential diagnosis of the mucopolysaccharidoses, these results bring new insights into the specificity of the heparitinases from Flavobacterium heparinum.

Role of chondroitin 4-sulphate as a receptor for polycation induced human platelet aggregation

1. Proteoglycans provide negatively charged sites on the surface of platelets, leukocytes and endothelial cells. Since chondroitin 4-sulphate is the main proteoglycan present on the platelet surface, the role of this molecule in mediating the activation of human platelets by polylysine was studied. 2. Platelets were desensitized with phorbol 12-myristate 13-acetate (PMA, 10 nM) 5 min before the addition of polylysine to platelet-rich plasma (PRP). Changes in the intracellular Ca2+ concentration were measured in fura2-am (2 microM) loaded platelets and protein phosphorylation was assessed by autoradiography of the electrophoretic profile obtained from [32P]-phosphate labelled platelets. The release of dense granule contents was measured in [14C]-5-hydroxytryptamine loaded platelets and the synthesis of thromboxane (TXA2) was assessed by radioimmunoassay. Surface chondroitin 4-sulphate proteoglycan was degraded by incubating platelets with different concentrations of chondroitinase AC (3 min, 37 degrees C). The amount of chondroitin 4-sulphate remaining in the platelets was then quantified after proteolysis and agarose gel electrophoresis. 3. The addition of PMA to PRP before polylysine inhibited the aggregation by 88 +/- 18% (n = 3). Staurosporine (1 microM, 5 min) prevented the PMA-induced inhibition. Chondroitinase AC (4 pu ml-1 to 400 muu ml-1, 3 min) abolished the polylysine-induced aggregation in PRP but caused only a discrete inhibition of ADP-induced aggregation. The concentration of chrondroitin 4-sulphate in PRP (0.96 +/- 0.2 microgram/10(8) platelets, n = 3) and in washed platelets (WP; 0.35 +/- 0.1 microgram/10(8) platelets, n = 3) was significantly reduced following incubation with chondroitinase AC (PRP = 0.63 +/- 0.1 microgram/10(8) platelets and WP = 0.08 +/- 0.06 microgram/10(8) platelets). 4. Washed platelets had a significantly lower concentration of chondroitin 4-sulphate than platelets in PRP. The addition of polylysine to WP induced a rapid increase in light transmission which was not accompanied by TXA2 synthesis or the release of dense granule contents. This effect was not inhibited by sodium nitroprusside (SNP), iloprost, EDTA or the peptide RGDS. This event was accompanied by the discrete phosphorylation of plekstrin and myosin light chain, which were inhibited by staurosporine (10 microM, 10 min). The hydrolysis of platelet surface chondroitin 4-sulphate strongly reduced the polylysine-induced phosphorylation. 5. Our results indicate that polylysine activates platelets through a specific receptor which could be the proteoglycan chondroitin 4-sulphate present on the platelet membrane.

Synchronized order of appearance of hyaluronic acid (or acidic galactan) --> chondroitin C-6 sulfate --> chondroitin C-4/C-6 sulfate, heparan sulfate, dermatan sulfate --> heparin during morphogenesis, differentiation and development

The synthesis of glycosaminoglycans and acidic polysaccharides during embryonic and fetal development in mammals and molluscs is briefly reviewed. A sequential order of appearance of each of the acidic polysaccharides was observed, coinciding with the major processes of the ontogeny. In mammals, hyaluronic acid is the first glycosaminoglycan synthesized at the beginning of morphogenesis. This glycosaminoglycan is then replaced by chondroitin 6-sulfate during the migration of the mesenchymal cells. Heparan sulfate, dermatan sulfate and chondroitin 4-sulfate are synthesized only during cell differentiation. The synthesis of heparin, on the other hand, is confined to mast cells in a few tissues and is a late event in the differentiation process. The same general pattern is also observed in molluscs except that hyaluronic acid is replaced by an acidic galactan in the morphogenetic process. The activity of the degrading enzymes responsible for the disappearance of hyaluronic acid, chondroitin sulfate and the acidic galactan in each phase of embryonic development is also reviewed.

Transport of UDP-galactose into the Golgi lumen regulates the biosynthesis of proteoglycans

The lumen of the Golgi apparatus is the subcellular site where galactose is transferred, from UDP-galactose, to the oligosaccharide chains of glycoproteins, glycolipids, and proteoglycans. The nucleotide sugar, which is synthesized in the cytosol, must first be transported into the Golgi lumen by a specific UDP-galactose transporter. Previously, a mutant polarized epithelial cell (MDCKII-RCAr) with a 2% residual rate of transport of UDP-galactose into the lumen of Golgi vesicles was described (Brandli, A. W., Hansson, G. C., Rodriguez-Boulan, E., and Simons, K. (1988) J. Biol. Chem. 263, 16283-16290). The mutant has an enrichment in glucosyl ceramide and cell surface glycoconjugates bearing terminal N-acetylglucosamine, as well as a 75% reduction in sialylation of cell surface glycoproteins and glycosphingolipids. We have now studied the biosynthesis of galactose containing proteoglycans in this mutant and the corresponding parental cell line. Wild-type Madin-Darby canine kidney cells synthesize significant amounts of chondroitin sulfate, heparan sulfate, and keratan sulfate, while the above mutant synthesizes chondroitin sulfate and heparan sulfate but not keratan sulfate, the only proteoglycan containing galactose in its glycosaminoglycan polymer. The mutant also synthesizes chondroitin 6-sulfate rather than only chondroitin 4-sulfate as wild-type cells. Together, the above results demonstrate that the Golgi membrane UDP-galactose transporter is rate-limiting in the supply of UDP-galactose into the Golgi lumen; this in turn results in selective galactosylation of macromolecules. Apparently, the Km for galactosyltransferases involved in the synthesis of linkage regions of heparan sulfate and chondroitin sulfate are significantly lower than those participating in the synthesis of keratan sulfate polymer, glycoproteins, and glycolipids. The results also suggest that the 6-O-sulfotransferases, in the absence of their natural substrates (keratan sulfate) may catalyze the sulfation of chondroitin 4-sulfate as alternative substrate.

Alterations of heparan sulfate moieties in cultured endothelial cells exposed to endotoxin

In previous studies, we observed that exposure to endotoxin markedly reduces the level of heparan sulfate proteoglycans in the extracellular matrix of cultured endothelial cells and at the same time causes the accumulation of proteoglycans bearing glycosaminoglycan chains of reduced size in the conditioned medium (P. Colburn, E. Kobayashi, and V. Buonassisi, 1994, J. Cell. Physiol. 159, 121-130). We have now investigated the structural and ligand-binding features which distinguish the matrix glycosaminoglycan moiety and the nature of the alterations of the truncated glycosaminoglycans. The matrix glycosaminoglycans are less sulfated than those of other cellular compartments and are more extensively degraded by heparitinase I, yielding a larger proportion of smaller oligosaccharides. In the binding assays, matrix glycosaminoglycans had greater specificity than those of the cell surface for a synthetic peptide patterned on the carboxyl-terminal sequence of an N-glycan sulfated protein synthesized by the endothelial cell. The nature of the alteration caused by exposure to endotoxin consists in the loss of a region rich in sulfate, located at the nonreducing end of the glycosaminoglycan chain. We also determined that only proteoglycans with intact chains are found in the extracellular matrix of endotoxin-treated cells.

Minimum fragments of the heparin molecule able to produce the accumulation and change of the sulfation pattern of an antithrombotic heparan sulfate from endothelial cells

Heparin and low molecular weight heparins stimulate two to three fold the accumulation of an antithrombotic heparan sulfate secreted by endothelial cells in culture. This led us to search for the minimum structural requirements of the heparin molecule able to elicit the enhancement of the heparan sulfate. Fragments were prepared from heparin by degradation with bacterial heparinase and heparitinases. A heparin pentasulfated tetrasaccharide was shown to be the minimum structural sequence able to enhance two to three fold the secretion of heparan sulfate by endothelial cells. The stimulation is specific for the endothelial cell, is concentration dependent and the effect is already noticed after one hour of exposure of the cells to heparin and the tetrasaccharide. Degradation of the [35S]-heparan sulfate synthesized in the presence of heparin or the tetrasaccharide has shown a higher degree of sulfation of its iduronic acid residues.

A comparative study on the mechanism of the anticoagulant action of mollusc and mammalian heparins

The anticlotting activities on some steps of the coagulation cascade of mollusc and mammalian heparins were studied. AT III-high affinity heparin is a more potent inhibitor than unfractionated heparin and mollusc heparin in the intrinsic and extrinsic pathways of thrombin and factor Xa generation. Mollusan heparin has about the same activity as the AT III high affinity-heparin on the inhibition of factor Xa and thrombin in the presence of antithrombin III and four times more inhibitory activity than unfractionated heparin on the heparin cofactor II mediated inhibition of thrombin.

Biosynthesis of glycosaminoglycans in the endometrium during the initial stages of pregnancy of the mouse

Significant changes in the synthesis of glycosaminoglycans occur during the transformation of stromal cells of the endometrium into decidual cells which takes place during the initial stages of pregnancy in mice. Hyaluronic acid, which is practically absent in the endometrium of virgin mice, increases dramatically on the fifth day of pregnancy, reaching its maximal concentration on day 6 followed by a 50% decrease on day 7. Changes in hyaluronic acid concentration also occur in pseudopregnant mice indicating that they are not related to the presence of the embryo in the uterus. The absolute concentration of the sulfated glycosaminoglycans, e.g., heparan sulfate, dermatan sulfate and chondroitin sulfate in the decidua did not change significantly. There was, however, a striking decrease of their biosynthesis in pregnant and pseudopregnant mice when compared to virgin mice, as shown by the use of radioactive inorganic sulfate as a precursor for the study of in vivo synthesis. A radioautographical analysis confirmed that the highest incorporation of radioactive sulfate was observed in virgin endometria when compared to pregnant ones. These studies also have shown a characteristic pattern of labeling in different regions of the endometrium that repeats itself during the different days of pregnancy.

Effect of different glycosaminoglycans in a guinea-pig carotid artery thrombosis model

Heparin is the most frequently used drug for the prevention and treatment of thrombosis. Its use, however, is restricted by its side-effects. To study the efficacy of other glycosaminoglycans that could substitute heparin in the management of arterial thrombosis, 60 guinea-pigs were randomly allocated into 6 groups: G1 = control, G2 = heparin (150 IU/kg), G3 = heparan sulfate from beef pancreas (2.5 mg/kg), G4 = heparan sulfate from beef lung (2.5 mg/kg), G5 = N-acetylated heparan from beef pancreas, G6 = dermatan sulfate from beef intestine (2.5 mg/kg). Ten minutes after intravenous injection of the drugs, thrombosis was induced by the injection of a 50% glucose solution into a segment of the right carotid artery isolated between 2 thread loops during 10 minutes. Three hours later the artery was re-exposed and if a thrombus was present it was measured, withdrawn and weighed. Thrombin time and activated partial thromboplastin time were measured in all animals. Thrombus developed in 90% of the animals in the control group, 0% in G2 and G3, 62.5% in G4, 87.5% in G5 and G6. Only in the animals treated with heparin the coagulation tests were prolonged. In conclusion, in the used dose only the heparan sulfate from beef pancreas presented an antithrombotic effect similar to heparin in this experimental model.

The kinetics of chondroitin 4-sulfate release from stimulated platelets and its relation to thromboxane A2 formation and granule secretion

1. In platelet rich plasma (PRP), chondroitin 4-sulfate release from platelets occurred after stimulation with ADP (5 microM), collagen (5-10 micrograms/ml), or adrenaline (10 microM). Release started within 60 s and maximum release (0.7-2.0 mg/l) was reached within 180 s. TXA2 formation and dense granule release reached a maximum within 90 s after stimulation. 2. Using washed platelets (1.5 x 10(8) cells/ml), the platelet responses were faster. Release of chondroitin 4-sulfate and TXA2 started within 20-30 s after thrombin addition (100 mU/ml). Maximum release was reached within 60 s in both cases. Dense granule release started in the first 5 s of stimulation (34.6 +/- 12.4%) reaching maximum secretion (74.4 +/- 8.7%) within 60 s. 3. Our results demonstrate that maximal chondroitin 4-sulfate release occurs after the dense granule release reaction in both PRP and washed platelets. This observation suggests that chondroitin 4-sulfate is unlikely to be stored in the dense granules but may be stored in the alpha-granules.

Sequencing of heparan sulfate proteoglycans: identification of variable and constant oligosaccharide regions in eight heparan sulfate proteoglycans of different origins

The sequence of the disaccharide units of eight heparan sulfate proteoglycans of different origins is described. All heparan sulfates contain 5 variable regions made of oligosaccharide blocks of disaccharides, namely, GlcUA(1-4)GlcNAc, GlcUA(1-4)GlcNS, IdoUA (1-4) GlcNS,6S,IdoUA-GlcNAc,6S, and IdoUA,2S(1-4)GlcNS,6S, besides two constant regions made of an internal tetrasaccharide (IdoUA-GlcNAc-IdoUA-GlcNS) and monosaccharides (GlcNS, and GlcNS,6S) at the non-reducing terminal. The N-acetylated region of the heparan sulfates is linked to the serine of the protein core through a trisaccharide of Xyl-Gal-Gal. Heparan sulfates differ from one another in terms of the number of disaccharides that compose each block.

Heparan sulfate proteoglycan and control of cell proliferation: enhanced synthesis induced by phorbol ester (PMA) during G(1)-phase

The effect of phorbol 12-myristate-13-acetate (PMA), a tumor-promoting phorbol ester, on the synthesis of proteoglycans of endothelial cells in culture was investigated. This phorbol activates protein kinase C (PKC) when added to cells in culture. PKC, in turn, modulates the activity of growth factors. Using [35S]-sulfate or [3H]-glucosamine to label the proteoglycans we have observed a 4-24-fold increase of the heparan sulfate (HS) synthesis in a dose-dependent manner (0-100 ng/ml). Chondroitin sulfate (CS) synthesis was not affected by PMA. The effect of PMA could be completely abolished by a calcium ionophore (A23187). By the use of synchronized cells and PMA pulses at different periods of the cell cycle, as well as [3H]-thymidine incorporation, we were able to show that the enhancement of heparan sulfate synthesis is most prominent during G1. Our data suggest that the release of HS to the medium could be one of the responses of the cell to a mitogenic stimulus.

Binding of heparin and compound Y to endothelial cells stimulates the synthesis of an antithrombotic heparan sulfate proteoglycan

The mechanism by which heparin and antithrombotic agents, including a cyclic octaphenolsulfonic acid (compound Y), stimulate the synthesis of an antithrombotic heparan sulfate by endothelial cells in culture was investigated. Compound Y increases the amount of heparan sulfate from the cell surface and secreted to the medium by endothelial cells by three-fold. Binding experiments have shown saturation of the endothelial cell receptors at a concentration of 0.16 microM for heparin and 2.7 microM for compound Y. The kinetic binding constants (Ks) for compound Y and heparin were 1,333 nM and 42 nM, respectively. It was also shown that both compounds bind to the same receptors. The Scatchard plots indicated that 1,319 nmoles compound Y and 35 nmoles heparin bound per microgram cell protein, indicating that 40-fold more molecules of compound Y bound to the receptors when compared to heparin. No significant internalization of the compounds was observed.

Glycosaminoglycan structure and content differ according to the origins of human tumors

The glycosaminoglycans of the tumor mass and from the urine of patients with a nephroblastoma of embryonic origin (Wilms' tumor) and hypernephroma were analyzed. The urine of patients with Wilms' tumors prior to treatment, and two patients with metastasis contained high levels of hyaluronic acid (2-5 mg/l of urine) when compared to patients after surgery or chemotherapy where the content of hyaluronic acid was less than 0.1 mg/l. Urine of patients with hypernephroma and normal individuals contained even smaller amounts of hyaluronic acid. Normal kidneys contain mainly dermatan sulfate and heparan sulfate, while the hypernephroma and Wilms' tumor contain substantial amounts of chondroitin sulfate. The amount of glycosaminoglycans isolated from Wilms' tumor and hypernephroma were 10 times and 3 times, respectively, greater than normal kidneys. The amounts of hyaluronic acid in Wilms' tumor varied from 56 to 73% whereas normal kidneys contained about 13%. Chondroitin sulfate was also increased in Wilms' tumor and hypernephroma. It corresponded to 11% and 42%, respectively, of the total glycosaminoglycans. These and other findings indicate that the glycosaminoglycans of Wilms' tumors resemble those present during embryonic development of normal tissues whereas those in hypernephroma are typical of other carcinomas of different origins.

Appearance and fate of a beta-galactanase, alpha, beta-galactosidases, heparan sulfate and chondroitin sulfate degrading enzymes during embryonic development of the mollusc Pomacea sp

The characterization and properties of a beta-galactanase and alpha- and beta-galactosidases as well as heparan sulfate and chondroitin sulfate degrading enzymes which appear during the 15 days of the embryonic development of the mollusc Pomacea sp. is reported. The beta-galactanase, which appears around day 7 of development, was separated from alpha- and beta-galactosidase which emerge at day 1 and 4 after oviposition, respectively. The galactanase seems to be responsible for the degradation of an acidic beta-galactan (which is also synthesized by the eggs around day 5) to galactose and di- and tri-galactosides. Heparan sulfate appears around day 10 of development together with a heparan sulfate endoglucuronidase responsible for the degradation of its N-acetylated region. An alpha-N-acetylglucosaminidase and a beta-glucuronidase which act upon the N-acetylated fragments formed from heparan sulfate emerge around day 4 of development. Chondroitin sulfate and a chondroitin sulfate sulfatase emerge around day 9 of development whereas a beta-N-acetylgalactosaminidase and the beta beta-galactan, heparan and chondroitin sulfate, respectively. The possible role of these elements in the migration of mesenchymal cells, in the processes of cell-cell recognition and control of cell growth is discussed.

Antithrombotic agents stimulate the synthesis and modify the sulfation pattern of a heparan sulfate proteoglycan from endothelial cells

Low molecular weight heparins, namely CY 216 and CY 222 (Sanofi/Choay); OP 622 and OP 386 (Opocrin); PK 10169 (Pharmuka); an oligosaccharide prepared from heparin by heparitinase II digestion; chemically sulfated glycosaminoglycans and polysaccharide namely Suleparoid (Syntex), Aprosulate (Luitpold-Werk); chemically modified glycosaminoglycans GAGPS and MPS (Luitpold-Werk) as well as unmodified heparin stimulate two to three fold the synthesis of a heparan sulfate with antithrombotic activity secreted by endothelial cells in culture. The stimulation is concentration dependent and specific for the endothelial cell. The [35S]-heparan sulfate synthesized in the presence of heparin and/or the tested antithrombotic agents has shown a high degree of sulfation of the iduronic acid residues as revealed by the analyses of the disaccharide products formed from the heparan sulfate by the action of bacterial heparitinases. The features of the above compounds in common with heparin are their polymeric nature and a high change density, as well as their pharmacological activities as potent antithrombotic agents "in vivo". These combined observations reinforce the proposition that the antithrombotic activity of heparin, low molecular weight heparins and the chemically modified polysaccharides could be related to the increased production of this peculiar heparan sulfate by endothelial cells.

ATP reduces blood loss produced by heparin in cardiopulmonary bypass operations

It was previously shown that topical application of heparin produces enhanced bleeding from small vessels and capillaries. Adenosine triphosphate at low concentrations is able to dislodge heparin bound to a receptor, counteracting its antihemostatic activity. These results led us to measure the amounts of heparin remaining in the blood after protamine neutralization of the patients subjected to cardiopulmonary bypass operation and to test the topical application of the nucleotide. Adenosine triphosphate at a concentration of 10(-4) mol/L significantly reduces the blood volume (p < 0.005) oozed from the thoracic cavity of the patients (mean, 288 +/- 188 mL) when compared with controls (mean, 564 +/- 288 mL). Adenosine triphosphate at 5 x 10(-5) mol/L reduces the blood loss to a mean of 370 +/- 155 mL in the patients tested (p < 0.08). About 10% of heparin of low molecular weight (< or = 6.0 Kda), which is also found in the oozed blood, is not neutralized by protamine. We suggest that the excessive blood loss of the patients is probably produced by low molecular weight heparins in the commercial preparations that are not neutralized by protamine.

Structure of heparan sulfate from the fresh water mollusc Anomantidae sp: sequencing of its disaccharide units

1. The disaccharide sequences of a heparan sulfate isolated from Anomantidae sp. was determined with the aid of heparitinase I, heparitinase II from Flavobacterium heparinum, mollusc beta-glucuronidase and alpha-N-acetylglucosaminidase besides nitrous acid degradation and chemical analyses. 2. Like the mammalian heparan sulfates the mollusc heparan sulfate is composed of different oligosaccharide blocks of N-acetylated disaccharides, N-sulfated disaccharides and N,6-sulfated disaccharides and has in its nonreducing end the monosaccharide glucosamine 2,6-disulfate. 3. The oligosaccharides produced by heparitinase I degradation contain at their reducing ends a N-acetylated, 6-sulfated disaccharide. 4. These and other results lead to the conclusion that the general structure of the heparan sulfate is maintained through evolution.

Mitogenic activity of acidic fibroblast growth factor is enhanced by highly sulfated oligosaccharides derived from heparin and heparan sulfate

The mitogenic activity of acidic fibroblast growth factor (aFGF) is potentiated by the highly sulfated hexasaccharide [IdoUA,2S-GlcNS,6S]2-[GlcUA-GlcNS,6S] the structural repetitive unit of lung heparin chains. On a mass basis, the effect of both heparin and oligosaccharide are equivalent whereas on a molar basis, heparin, which contains about seven hexasaccharide repeats, is more efficient. On the other hand, a pentasulfated tetrasaccharide or di- and tri-sulfated disaccharides are much less effective in potentiating aFGF activity than the hexasaccharide. If the growth factor is pre-incubated with the hexasaccharide at pH 7.2 and then exposed to pH 3.5 the 306/345 nm fluorescence ratio is similar to that of native aFGF indicating that the oligosaccharide stabilizes a native conformation of the protein. Heparan sulfates extracted from various mammalian tissues were also able to potentiate aFGF mitogenic activity. On a mass basis they were in general less efficient than heparin; however, heparan sulfate prepared from medium conditioned by 3T3 fibroblasts is more efficient than heparin both on a mass and molar basis. A highly sulfated oligosaccharide isolated after digestion of pancreas heparan sulfate with heparitinase I is more active than the intact molecule, reaching a potentiating effect equivalent to that of lung heparin, whereas an N-acetylated oligosaccharide isolated after nitrous acid degradation is inactive. These data suggest that the mitogenic activity of aFGF is primarily potentiated by interacting with highly sulfated regions of heparan sulfates chains.

Anomalous structure of urinary chondroitin sulfate from cancer patients. A potential new marker for diagnosis of neoplasias

BACKGROUND

Chondroitin sulfate is significantly increased in tumors (10 to 100 times) when compared to the amounts present in normal adjacent tissues. To investigate if the changes in concentration of chondroitin sulfate could be reflected in the urine of cancer patients we have analyzed the chondroitin sulfate excreted by 44 patients with different types of tumors, 50 normal individuals and 15 patients with unrelated diseases.

EXPERIMENTAL DESIGN

The identification and structural analyses of the sulfated glycosaminoglycans were made by electrophoresis and degradation with specific enzymes (chondroitinases AC and ABC), identification/quantitation of their disaccharide products by chromatography (paper and HPLC) and chemical determinations.

RESULTS

The disaccharide products formed from chondroitin sulfate of the 44 cancer patients by action of chondroitinase ABC show a substantial relative increase of non sulfated disaccharide (32.1% +/- 15.2) with a relative decrease of 6-sulfated disaccharide (28.9% +/- 11.5) and 4-sulfated disaccharide (39.0% +/- 13.5) when compared to the chondroitin sulfate of normal subjects (9.1% +/- 2.2, 40.6% +/- 4.5 and 50.2% +/- 4.5, respectively) or from patients with unrelated diseases. There is a direct correlation between the non sulfated disaccharide content and the stage of malignancy of the cancer patients. A significant change of the ratio of chondroitin sulfate and heparan sulfate and a decrease in the electrophoretic migration of chondroitin sulfate were also observed in cancer patients.

CONCLUSIONS

All the cancer patients analyzed so far have shown the structural anomaly of the urinary chondroitin sulfate and this may be useful in the diagnosis and follow up of cancer therapy.

Interaction of heparin with myosin ATPase: possible involvement with the hemorrhagic activity and a correlation with antithrombin III high affinity-heparin molecules

Up to 50% of [35S]-heparin molecules prepared from rat skin bind to rabbit muscle myosin ATPase, in a concentration dependent manner, producing a stable complex with a dissociation constant of 3 x 10(-7) M. The [35S]-heparin in the complex has a distinct electrophoretic behaviour and is precipitated by TCA together with myosin. Other [35S]-glycosaminoglycans, namely, heparan sulfate, dermatan sulfate and chondroitin sulfate also prepared from rat tissues are unable to form complexes with the enzyme. Among the sulfated glycosaminoglycans obtained from different sources only heparin is able to displace the bound [35S]-heparin from the ATPase. Heparin with high affinity for antithrombin III, prepared by antithrombin-affinity chromatography, dislodges up to 90% of the bound [35S]-heparin. Furthermore, antithrombin III-high affinity heparin shows a high affinity for myosin ATPase when compared to antithrombin III-low affinity heparin which shows a low affinity for the enzyme. It is also shown that myosin ATPase inhibits the "in vitro" plasma anticoagulant activity of heparin. These are suggestive that the special structure of the heparin molecules needed for the binding to antithrombin and myosin ATPase bears important similarities. The mechanism of the hemorrhagic effect of heparin is discussed in view of these interactions.

Effect of monensin on the sulfation of heparan sulfate proteoglycan from endothelial cells

Monensin is a monovalent metal ionophore that affects the intracellular translocation of secretory proteins at the level of trans-Golgi cisternae. Exposure of endothelial cells to monensin results in the synthesis of heparan sulfate and chondroitin sulfate with a lower degree of sulfation. The inhibition is dose dependent and affects the ratio [35S]-sulfate/[3H]-hexosamine of heparan sulfate from both cells and medium, with no changes in their molecular weight. By the use of several degradative enzymes (heparitinases, glycuronidase, and sulfatases) the fine structure of the heparan sulfate synthesized by control and monensin-treated cells was investigated. The results have shown that among the six heparan sulfate disaccharides there is a specific decrease of the ones bearing a sulfate ester at the 6-position of the glucosamine moiety. All other biosynthetic steps were not affected by monensin. The results are indicative that monensin affects the hexosamine C-6 sulfation, and that this sterification is the last step of the heparan sulfate biosynthesis and should occur at the trans-Golgi compartment.

Decrease in sulphated glycosaminoglycans in aortic dissection--possible role in the pathogenesis

STUDY OBJECTIVE

The aim was to investigate alterations in sulphated glycosaminoglycans in aortic dissection.

DESIGN

Aortic fragments were taken from 10 patients within the first 3 d after onset of symptoms of aortic dissection and from nine age matched patients with no aortic disease. Sulphated glycosaminoglycans were analysed and quantified by agarose gel electrophoresis and densitometry after degradation with specific enzymes.

MEASUREMENTS AND MAIN RESULTS

The amount of chondroitin sulphate was similar (7.14 v 7.60 mg.g-1 of dry tissue, n = 10, p greater than 0.5) in patients with dissection and in the control group. Total sulphated glycosaminoglycan content was decreased (11.51 v 14.26 mg.g-1 of dry tissue, n = 10, p less than 0.001). This difference was due to heparan sulphate (1.79 v 2.48 mg.g-1 of dry tissue, n = 10, p less than 0.05) and mainly to dermatan sulphate (2.58 v 4.18 mg.g-1 of dry tissue, n = 10, p less than 0.001). The ratio of 6-/4-sulphated disaccharides after chondroitinase ABC digestion was increased in the affected group. No correlation between these biochemical results and a histological evaluation of mucoid content was found. On the other hand, a significant increase in chondroitin sulphate could be observed related to aging.

CONCLUSIONS

The diminution in sulphated glycosaminoglycans and its possible relationship with fat, collagen, and other extracellular matrix molecules could lead to a weakness in the aortic wall related to the dissection.