[show abstract][hide abstract] ABSTRACT: Fucan is a term used to denominate sulfated l-fucose rich polysaccharides. Here, a heterofucan, named fucan B, was extracted from the Spatoglossum schröederi seaweed. This 21.5kDa galactofucan inhibited CHO-K1 proliferation and migration when fibronectin was the substrate. Fucan B derivatives revealed that such effects depend on their degree of sulfation. Fucan B did not induce cell death, but promoted G1 cell cycle arrest. Western blotting and flow cytometry analysis suggest that fucan B binds to fibronectin and activates integrin, mainly integrin α5β1, which induces FAK/RAS/MEK/ERK activation. FAK activation inhibits CHO-K1 migration on fibronectin and ERK blocks cell cycle progression. This study indicates that fucan B could be applied in developing new antitumor drugs.
[show abstract][hide abstract] ABSTRACT: We compared the structures and rheology of xanthan-galactomannan (X:G) hydrogels with the addition of curcumin in microemulsion (X:GMC) and ethanol (X:GEC). X:GMC hydrogels have gel characteristics and exhibited a significantly higher elastic response than the X:GEC and X:G hydrogels at room temperature, but after heating, an increase in the elastic modulus was observed for the last two systems. The visualization of the hydrogel microstructures by cryo-scanning electronic microscopy revealed pores within the lamellar structure only for X:GMC. In vitro skin permeation tests showed a more pronounced lag time for X:GMC; however, a more efficient permeation from X:GMC than from X:GEC. This study demonstrates that the X:G system is an alternative to traditional gels for the topical applications of hydrophobic drugs.
Journal of Pharmaceutical Sciences 05/2012; 101(7):2457-67. · 3.13 Impact Factor
[show abstract][hide abstract] ABSTRACT: Brown spider (Loxosceles sp.) venom affects the endothelium of vessels and triggers disruptive activity in the subendothelial matrix. The vascular disorders observed after venom exposure include leukocyte and platelet activation, disseminated intravascular coagulation, an increase in vessel permeability and hemorrhage into the dermis. In this study, we report additional evidence regarding the mechanism of endothelial cell cytotoxicity induced by Loxosceles intermedia venom. Exposure to venom led to endothelial cell detachment in a time-dependent manner. Loss of cell anchorage and cell-cell adhesion following venom exposure was accompanied by changes in the distribution of the α₅β₁ integrin and VE-cadherin. An ultrastructural analysis of cells treated with venom revealed morphological alterations characteristic of apoptosis. Moreover, after venom exposure, the ratio between Bax and Bcl-2 proteins was disturbed in favor of Bax. In addition, late apoptosis was only observed in cells detached by the action of venom. Accordingly, there was no increase in apoptosis when cells were exposed to L. intermedia venom in suspension, suggesting that the loss of cell anchorage provides the signal to initiate apoptosis. Thus, L. intermedia venom likely triggers endothelial cell death indirectly through an apoptotic mechanism known as anoikis.
[show abstract][hide abstract] ABSTRACT: Aging and a variety of pathologies, including cancer, diabetes, cardiovascular and inflammatory diseases have been associated with reactive oxygen species (ROS), such as superoxide anion (O₂·⁻), hydroxyl radical (·OH) and hydrogen peroxide (H₂O₂) generation. Plant polyphenols bear radical scavenging/antioxidant activity. A phytomedicinal preparation obtained from aerial parts of Dicksonia sellowiana (Dicksoniaceae), a native plant from Central and South America, has been widely used in Brazil against asthma and presents beneficial effects in several other diseases, including cardiovascular disturbance. In this work, we investigated whether Dicksonia sellowiana, which is also known to contain high levels of polyphenols, presents antioxidant activity.
The antioxidant activity of the hydroalcoholic extract obtained from Dicksonia sellowiana leaves (HEDS) was investigated by in vitro and in vivo tests.
HEDS (0.1-100 μg/mL) exhibited a strong scavenging activity against all reactive species tested (DPPH, O₂·⁻,·OH and H₂O₂; IC₅₀=6.83±2.05, 11.6±5.4, 2.03±0.4, and 4.8±0.4 μg/mL, respectively). HEDS strongly protected endothelial cells against H₂O₂-induced oxidative stress by mechanisms other than increasing catalase activity. In addition, HEDS protected cell membrane from oxidative damage. HEDS, (20 and 40 mg/kg) inhibited lipid peroxidation in vivo (29.8% and 24.5%, respectively).
According to our results, we can speculate that the traditional uses of Dicksonia sellowiana for cardiovascular diseases, asthma and skin diseases could be, at least in part, related to the potent antioxidant and endothelial protective activities of the plant.
Journal of ethnopharmacology 02/2011; 133(3):999-1007. · 2.32 Impact Factor
[show abstract][hide abstract] ABSTRACT: Bites from the Loxosceles genus (brown spiders) cause severe clinical symptoms, including dermonecrotic injury, hemorrhage, hemolysis, platelet aggregation and renal failure. Histological findings of dermonecrotic lesions in animals exposed to Loxosceles intermedia venom show numerous vascular alterations. Study of the hemorrhagic consequences of the venom in endothelial cells has demonstrated that the degeneration of blood vessels results not only from degradation of the extracellular matrix molecule or massive leukocyte infiltration, but also from a direct and primary activity of the venom on endothelial cells. Exposure of an endothelial cell line in vitro to L. intermedia venom induce morphological alterations, such as cell retraction and disadhesion to the extracellular matrix. The aim of the present study was to investigate the interaction between the venom toxins and the endothelial cell surface and their possible internalization, in order to illuminate the information about the deleterious effect triggered by venom. After treating endothelial cells with venom toxins, we observed that the venom interacts with cell surface. Venom treatment also can cause a reduction of cell surface glycoconjugates. When cells were permeabilized, it was possible to verify that some venom toxins were internalized by the endothelial cells. The venom internalization involves endocytic vesicles and the venom was detected in the lysosomes. However, no damage to lysosomal integrity was observed, suggesting that the cytotoxic effect evoked by L. intermedia venom on endothelial cells is not mediated by venom internalization.
[show abstract][hide abstract] ABSTRACT: Alpha5beta1 integrin from both wild-type CHO cells (CHO-K1) and deficient in proteoglycan biosynthesis (CHO-745) is post-translationally modified by glycosaminoglycan chains. We demonstrated this using [35S]sulfate metabolic labeling of the cells, enzymatic degradation, immunoprecipitation reaction with monoclonal antibody, fluorescence microscopy, and flow cytometry. The alpha5beta1 integrin heterodimer is a hybrid proteoglycan containing both chondroitin and heparan sulfate chains. Xyloside inhibition of sulfate incorporation into alpha5beta1 integrin also supports that integrin is a proteoglycan. Also, cells grown with xyloside adhered on fibronectin with no alteration in alpha5beta1 integrin expression. However, haptotactic motility on fibronectin declined in cells grown with xyloside or chlorate as compared with controls. Thus, alpha5beta1 integrin is a proteoglycan and the glycosaminoglycan chains of the integrin influence cell motility on fibronectin. Similar glycosylation of alpha5beta1 integrin was observed in other normal and malignant cells, suggesting that this modification is conserved and important in the function of this integrin. Therefore, these glycosaminoglycan chains of alpha5beta1 integrin are involved in cellular migration on fibronectin.
Biochemistry and Cell Biology 08/2009; 87(4):677-86. · 2.92 Impact Factor
[show abstract][hide abstract] ABSTRACT: Endothelins, acting through specific endothelin ET(A) and/or ET(B) receptors, participate in nociceptive processing in models of cancer, inflammatory and neuropathic pain. The present study investigated which cell types express endothelin receptors in the trigeminal ganglion, and the contribution of mechanisms mediated by endothelin ET(A) and ET(B) receptors to orofacial heat hyperalgesia induced by unilateral constriction of the infraorbital nerve (CION). Both receptor types were identified by immunohistochemistry in the trigeminal ganglion, ET(A) receptors on small-sized non-myelinated and myelinated A-fibers and ET(B) receptors on both satellite glial cells and small-sized non-myelinated neuronal cells. CION promoted ipsilateral orofacial heat hyperalgesia which lasted from Day 2 until Day 10 after surgery. Ongoing CION-induced heat hyperalgesia (on Day 4) was reduced transiently, but significantly, by systemic or local treatment with antagonists of endothelin ET(A) receptors (atrasentan, 10 mg/kg, i.v.; or BQ-123, 10 nmol/lip), endothelin ET(B) receptors (A-192621, 20 mg/kg, i.v.; or BQ-788, 10 nmol/ lip), or of both ET(A)/ET(B) receptors (bosentan, 10 mg/kg, i.v.; or BQ-123 plus BQ-788, each at 10 nmol/lip). On the other hand, CION-induced heat hyperalgesia was transiently abolished over the first 90 min following i.p. injection of morphine hydrochloride (2.5 mg/kg), but fully resistant to reversal by indomethacin (4 mg/kg, i.p.) or celecoxib (10 mg/kg, i.p.). Thus, heat hyperalgesia induced by CION is maintained, in part, by peripheral signaling mechanisms operated by ET(A) and ET(B) receptors. Endothelin receptors might represent promising therapeutic targets for the control of trigeminal neuropathic pain.
[show abstract][hide abstract] ABSTRACT: Accidents involving Brown spider (Loxosceles sp.) venom produce a massive inflammatory response in injured region. This venom has a complex mixture of different toxins, and the dermonecrotic toxin is the major contributor to toxic effects. The ability of Loxosceles intermedia venom and a recombinant isoform of dermonecrotic toxin to induce edema and increase in vascular permeability was investigated. These toxins were injected into hind paws and caused a marked dose and time-dependent edema and increase in vascular permeability in mice. Furthermore, the enzymatic activity of venom toxins may be primal for these effects. A mutated recombinant isoform of dermonecrotic toxin, that has only residual enzymatic activity, was not able to induce these inflammatory events. Besides the previous heating of toxins markedly reduced the paw edema and vascular permeability showing that thermolabile constituents can trigger these effects. In addition, the ability of these venom toxins to evoke inflammatory events was partially reduced in compound 48/80-pretreated animals, suggesting that mast cells may be involved in these responses. Pretreating mice with histamine (prometazine and cetirizine) and serotonin (methysergide) receptor antagonists significantly attenuated toxins induced edema and vascular permeability. Moreover, HPLC analysis of whole venom showed the presence of histamine sufficient to induce inflammatory responses. In conclusion, these inflammatory events may result from the activation of mast cells, which in turn release bioamines and may be related to intrinsic histamine content of venom.
Comparative Biochemistry and Physiology Part C Toxicology & Pharmacology 12/2008; 149(3):323-33. · 2.71 Impact Factor
[show abstract][hide abstract] ABSTRACT: Fucan is a term used to denominate a family of sulfated L-fucose-rich polysaccharides. The brown alga Spatoglossum schröederi (Dictyotaceae) has three heterofucans namely fucan A, B and C. The 21 kDa fucan A is composed of a core of a beta (1-3) glucuronic acid-containing oligosaccharide of 4.5 kDa with branches at C4 of the fucose chains alpha (1-3) linked. The fucose is mostly substituted at C4 with a sulfate group and at C2 with chains of beta (1-4) xylose. This fucan has neither anticoagulant (from from 0.1 to 100 microg) nor hemorrhagic activities (from 50 to 800 microg/mL). The antithrombotic test in vivo showed that fucan A has no activity in any of the concentrations (from 0.2 to 20 microg/g/day) tested 1 h after polysaccharide administration. However, when fucan A was injected endovenously 24 h before the ligature of the venae cavae, we observed a dose-dependent effect, reaching saturation at around 20 microg/g of rat weight. In addition, this effect is also time-dependent, reaching saturation around 16 h after fucan administration. In addition, regardless of the administration route, fucan A displayed antithrombotic activity. The exception was the oral pathway. Of particular importance was the finding that fucan A stimulates the synthesis of an antithrombotic heparan sulfate from endothelial cells like heparin. The hypothesis has been raised that the in vivo antithrombotic activity of fucan A is related to the increased production of this heparan. Taken together with the fact that the compound is practically devoid of anticoagulant and hemorrhagic activity, the data suggest that it may be an ideal antithrombotic agent in vivo.
[show abstract][hide abstract] ABSTRACT: In vitro, heparin and antithrombotic drugs specifically stimulate the synthesis of an antithrombotic heparan sulfate proteoglycan (HSPG) produced by endothelial cells. The putative heparin binding site(s) that may be related to this phenomenon were investigated. In the preceding article, using various heparin probes, it was shown that the heparin does not bind to the endothelial cell surface, but only to the extracellular matrix. The present study demonstrated that, when the cells were exposed to heparin at 37 degrees C, the heparin was internalized and with time was localized in lysosomes. However, endocytosis of heparin was not required for the stimulation of HSPG synthesis. The requirement for heparin degradation in the stimulus of HSPG synthesis was also investigated. When the cells were incubated with chloroquine, a lysosomotropic amine that raises the lysosomal pH thus inhibiting enzymatic degradation of internalized compounds, stimulation of HSPG synthesis was still observed. These combined results indicate that neither internalization nor degradation of heparin is required for stimulation of HSPG synthesis, and suggests that its binding to the extracellular matrix could be responsible for this effect.
Journal of Cellular Physiology 07/2008; 217(2):360-6. · 4.22 Impact Factor
[show abstract][hide abstract] ABSTRACT: Exposure of endothelial cells to heparin and other antithrombotic drugs specifically stimulates the synthesis of an antithrombotic heparan sulfate (HS). In the present work, biotinylated heparin (BiotHep) was used to characterize the binding site(s) of heparin responsible for the stimulus in HS synthesis on endothelial cells. No differences were observed between biotinylated and non-biotinylated heparin in their ability to increase the synthesis of HS. In kinetic studies the BiotHep showed fast, saturable and specific binding with an apparent K(D) of 83 nM to adherent cells and 44 nM to the extracellular matrix (ECM) in the absence of cells. By confocal and electron microscopy, BiotHep bound only to the ECM, co-localizing with fibronectin. The same pattern of binding to the ECM was observed using heparin conjugated with FITC or Alexa Fluor 488 in the presence or absence of fetal calf serum. However, after degradation of HS, heparin binds to the cell surface, indicating that endogenous HS possibly occupied the heparin binding sites. Analyses by flow cytometry and confocal microscopy of cells with non-associated ECM, showed labeling of the cell surface using syndecan-4 monoclonal antibody as well as wheat germ agglutinin, but no binding of heparin. Furthermore, the stimulation in HS synthesis is not elicited by heparin in the absence of ECM. These results indicate that the stimulus for the synthesis of HS does not require binding of the heparin to the cell surface, and the signaling may be mediated through the ECM.
Journal of Cellular Physiology 07/2008; 217(2):328-37. · 4.22 Impact Factor
[show abstract][hide abstract] ABSTRACT: Injuries caused by brown spiders (Loxosceles genus) are associated with dermonecrotic lesions with gravitational spreading and systemic manifestations. The venom has a complex composition containing many different toxins, of which metalloproteases have been described in many different species of this genus. These toxins may degrade extracellular matrix constituents acting as a spreading factor. By using a cDNA library from an Loxosceles intermedia venom gland, we cloned and expressed a 900 bp cDNA, which encoded a signal peptide and a propeptide, which corresponded to a 30 kDa metalloprotease, now named LALP (Loxosceles astacin-like protease). Recombinant LALP was refolded and used to produce a polyclonal antiserum, which showed cross-reactivity with a 29 kDa native venom protein. CD analysis provided evidence that the recombinant LALP toxin was folded correctly, was still in a native conformation and had not aggregated. LALP addition to endothelial cell cultures resulted in de-adhesion of the cells, and also in the degradation of fibronectin and fibrinogen (this could be inhibited by the presence of the bivalent chelator 1,10-phenanthroline) and of gelatin in vitro. Sequence comparison (nucleotide and deduced amino acid), phylogenetic analysis and analysis of the functional recombinant toxin revealed that LALP is related in both structure and function to the astacin family of metalloproteases. This suggests that an astacin-like toxin is present in a animal venom secretion and indicates that recombinant LALP will be a useful tool for future structural and functional studies on venom and the astacin family.
[show abstract][hide abstract] ABSTRACT: Purified from Bauhinia rufa seeds, BrTI is a Kunitz proteinase inhibitor that contains the RGD sequence. BrTI inhibits trypsin (K(iapp) 2.9 nM) and human plasma kallikrein (K(iapp) 14.0 nM) but not other related enzymes. The synthetic peptide YLEPVARGDGGLA-NH(2) (70 microM) inhibited the adhesion to fibronectin of B16F10 (high-metastatic B16 murine mouse melanoma cell line) and of Tm5 (murine melanoma cell lines derived from a non-tumorigenic lineage of pigmented murine melanocytes, melan-a). YLEPVARGEGGLA-NH(2) in which Asp(9) was changed into Glu does not affect the cell attachment. Moreover, this peptide was functional only when the sequence present in the native protein was preserved, since YLIPVARGDGGLA-NH(2) in which Glu(3) was changed into Ile does not interfere with B16F10 and was less effective on Tm5 cell line adhesion. Neither YLEPVARGDGGLA-NH(2), YLIPVARGDGGLA-NH(2) or YLEPVARGEGGLA-NH(2) inhibit the interaction of RAEC (endothelial cell line from rabbit aorta) with fibronectin.
International Journal of Biological Macromolecules 01/2007; 40(1):22-9. · 2.60 Impact Factor
[show abstract][hide abstract] ABSTRACT: Lead is a heavy metal of considerable environmental and occupational concern and there is growing evidence that it is toxic to the human immune system. In this regard, this study examined the effect of lead (Pb) exposure to peritoneal macrophages (Mvarphis) of mice (Mus musculus) cultivated in DMEM medium supplemented with fetal bovine serum, in order to investigate cell damage related to cell death. Cells were exposed to two concentrations of inorganic lead [Pb(II)] for 4, 24 and 72h. Cell viability declined during the treatment, with responses including cell death, cellular damage and DNA damage. Cell death images were found in treated cells with an increase in Bax expression, but the inorganic lead failed to induce the loss of membrane asymmetry (Annexin V conjugates), suggesting that cell death was mainly due to necrosis induction. The effects of Pb(II) on the mechanisms of cell death is not completely understood, but the immunosuppression due to DNA damage and Mvarphis death is discussed here. We have previously shown the effect of inorganic lead in mitochondria and phagocytosis in Mvarphis, suggesting here a pathway for the effect of the metal on mechanisms of cell death, also discussing its effects on the immune system.
Cell Biology International 08/2006; 30(7):615-23. · 1.64 Impact Factor
[show abstract][hide abstract] ABSTRACT: Spiders of the Loxosceles genus have been responsible for severe clinical cases of envenomation worldwide. Accidents involving brown spiders can cause dermonecrotic injury, hemorrhage, hemolysis, platelet aggregation and renal failure. Histological findings of animals treated by venom have shown subendothelial blebs, vacuoles and endothelial cell membrane degeneration of blood vessel walls, as well as fibrin and thrombus formation. The mechanisms by which the venom causes these disorders are poorly understood. In this work, with an endothelial cell line derived from rabbit aorta, we were able to demonstrate that venom binds to the cell surface and the extracellular matrix. Moreover, we observed that the venom also induced morphological alterations, such as cell retraction, homophilic disadhesion and an increasing in filopodia projections. We also demonstrated that toxins present in the venom disorganized focal adhesion points and actin microfilaments of endothelial cells. Nevertheless, endothelial cell viability showed no alterations compared to controls. Additionally, venom treatment changed the fibronectin matrix profile synthesized by these cells as well as cell adhesion to fibronectin. These results suggest that the deleterious effects of venom on blood vessel walls could be a consequence of the direct effect on the endothelial cell surface and adhesive structures involved in blood vessel stability. These effects indirectly lead to leukocyte and platelet activation, disseminated intravascular coagulation and an increase in vessel permeability.
[show abstract][hide abstract] ABSTRACT: The brown alga Spatoglossum schroederi contains three fractions of sulfated polysaccharides. One of them was purified by acetone fractionation, ion exchange, and molecular sieving chromatography. It has a molecular size of 21.5 kDa and contains fucose, xylose, galactose, and sulfate in a molar ratio of 1.0:0.5:2.0:2.0 and contains trace amounts of glucuronic acid. Chemical analyses, methylation studies, and NMR spectroscopy showed that the polysaccharide has a unique structure, composed of a central core formed mainly by 4-linked beta-galactose units, partially sulfated at the 3-O position. Approximately 25% of these units contain branches of oligosaccharides (mostly tetrasaccharides) composed of 3-sulfated, 4-linked alpha-fucose and one or two nonsulfated, 4-linked beta-xylose units at the reducing and nonreducing end, respectively. This sulfated galactofucan showed no anticoagulant activity on several "in vitro" assays. Nevertheless, it had a potent antithrombotic activity on an animal model of experimental venous thrombosis. This effect is time-dependent, reaching the maximum 8 h after its administration compared with the more transient action of heparin. The effect was not observed with the desulfated molecule. Furthermore, the sulfated galactofucan was 2-fold more potent than heparin in stimulating the synthesis of an antithrombotic heparan sulfate by endothelial cells. Again, this action was also abolished by desulfation of the polysaccharide. Because this sulfated galactofucan has no anticoagulant activity but strongly stimulates the synthesis of heparan sulfate by endothelial cells, we suggested that this last effect may be related to the "in vivo" antithrombotic activity of this polysaccharide. In this case the highly sulfated heparan sulfate produced by the endothelial cells is in fact the antithrombotic agent. Our results suggested that this sulfated galactofucan may have a potential application as an antithrombotic drug.
Journal of Biological Chemistry 01/2006; 280(50):41278-88. · 4.65 Impact Factor
[show abstract][hide abstract] ABSTRACT: In recent years, sulfated fucans have emerged as an important class of natural biopolymers. In this study, the anti-adhesive activity of a fucan from the brown seaweed Spatoglossum schröederi was analyzed using tumorigenic cells: wild-type Chinese hamster ovary cells (CHO-K1) and the mutant type deficient in xylosyltransferase (CHO-745). Fibronectin (FN) was used as substrate for cell attachment. For both cell types, this fucan has shown a dose-dependent anti-adhesive effect, reaching saturation at around 400 mug/mL. This effect was abolished by desulfation of the fucan. In addition, this polymer exhibited the highest inhibitory effect in comparison to other sulfated polysaccharides. The fucan was biotinylated and used as a probe to identify its action sites. Biotinylated fucan was detected in the extracellular matrix environment by confocal microscopy and flow cytometric analysis, but not at the cell surface. The results suggest that the fucan shows anti-adhesive activity by binding directly to FN, and blocking FN sites that are recognized by cell surface ligands, possibly the integrin family.
[show abstract][hide abstract] ABSTRACT: The structural characteristics of mesoionic compounds, which contain distinct regions of positive and negative charges associated with a poly-heteroatomic system, enable them to cross cellular membranes and interact strongly with biomolecules. Potential biological applications have been described for mesoionic compounds. 1,3,4-Thiadiazolium mesoionic compound (MI-D), a new mesoionic compound, has been demonstrated to be extremely cytotoxic to B16-F10 murine melanoma cells when compared to fotemustine and dacarbazine, drugs of reference in melanoma treatment protocols, describing inhibition of tumours grown in vitro and in vivo. We now evaluate the effects of mesoionic compound MI-D on different human melanoma cell lines. The drug decreased the viability and proliferation of MEL-85, SK-MEL, A2058 and MEWO cell lines in vitro, showing a considerable cytotoxic activity on these human cells. Adhesion of MEL-85 cells was evaluated in the presence of the drug using different extracellular matrix (ECM) constituents. MI-D decreased MEL-85 adhesion to laminin, fibronectin and matrigel. The morphology and actin cytoskeleton organisation of MEL-85 cells were also modified on MI-D treatment. These results on human melanoma cell lines indicate that MI-D is a very encouraging drug against melanoma, a tumour that is extremely resistant to chemotherapy.
British Journal of Cancer 08/2004; 91(2):297-304. · 5.08 Impact Factor
[show abstract][hide abstract] ABSTRACT: Brown spider (Loxosceles genus) venom causes necrotic lesions often accompanied by fever, hemolysis, thrombocytopenia, and acute renal failure. Using mice exposed to Loxosceles intermedia venom, we aimed to show whether the venom directly induces renal damage. The experimental groups were composed of 50 mice as controls and 50 mice that received the venom. Light microscopic analysis of renal biopsy specimens showed alterations including hyalinization of proximal and distal tubules, erythrocytes in Bowman's space, glomerular collapse, tubule epithelial cell blebs and vacuoles, interstitial edema, and deposition of eosinophilic material in the tubule lumen. Electron microscopic findings indicated changes including glomerular epithelial and endothelial cell cytotoxicity as well as disorders of the basement membrane. Tubule alterations include epithelial cell cytotoxicity with cytoplasmic membrane blebs, mitochondrial changes, increase in smooth endoplasmic reticulum, presence of autophagosomes, and deposits of amorphous material in the tubules. We also found that the venom caused azotemia with elevation of blood urea levels but did not decrease C3 complement concentration or cause hemolysis in vivo. Confocal microscopy with antibodies against venom proteins showed direct binding of toxins to renal structures, confirmed by competition assays. Double-staining immunofluorescence reactions with antibodies against type IV collagen or laminin, antibodies to venom toxins, and fluorescent cytochemistry with DAPI revealed deposition of toxins in glomerular and tubule epithelial cells and in renal basement membranes. Two-dimensional electrophoresis showed venom rich in low molecular mass and cationic toxins. By immunoblotting with antibodies to venom toxins on renal extracts from venom-treated mice, we detected a renal binding toxin at 30 kD. The data provide experimental evidence that L. intermedia venom is directly involved in nephrotoxicity.
Journal of Histochemistry and Cytochemistry 05/2004; 52(4):455-67. · 2.26 Impact Factor
[show abstract][hide abstract] ABSTRACT: 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.
Brazilian Journal of Medical and Biological Research 09/2001; 34(8):971-5. · 1.14 Impact Factor