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Matrix Interactions (matrix + interaction)
Selected AbstractsInfluence of Reactice Processing on the Properties of PP/Glass Fiber Composites Compatibilized with SilaneMACROMOLECULAR MATERIALS & ENGINEERING, Issue 4 2006Afonso H. O. Felix Abstract Summary: Composites of PP reinforced with 20 wt.-% of short glass fibers were prepared by extrusion using VTES as a coupling agent. The addition of VTES was performed via in-situ functionalization of PP and by a two-step process in which PP was functionalized before the composite preparation. The obtained samples were characterized using rheometry, mechanical tests and microscopy. Both processes allowed the fiber/matrix interaction to increase. It was found that the VTES content affected the viscosity of the system by means of three different mechanisms: reduction of , -scission reactions, decrease of fiber sliding and plasticizing effect on the matrix. Whereas the first two mechanisms increased the viscosity of the final composite after unreacted VTES removal, the third one reduced the viscosity during the process and contributed to fiber-length preservation. The effects of VTES and peroxide contents on the Young's modulus were closely related to their effects on the final fiber length, indicating the effectiveness of using VTES as a coupling agent. Comparison between in-situ functionalization and the two-step process with prefunctionalization showed that in-situ functionalization led to a lower degree of chain breakage, even when it was performed in the presence of peroxide. Scanning electron micrographs of PP/glass fiber composite prepared without coupling agent. [source] Effect of particle size of an amorphous calcium phosphate filler on the mechanical strength and ion release of polymeric composites,JOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 1 2007Soo-Young Lee Abstract The random clustering of amorphous calcium phosphate (ACP) particles within resin matrices is thought to diminish the strength of their polymerized composites. The objective of this study was to elucidate the effect of ball-milling on the particle size distribution (PSD) of ACP fillers and assess if improved dispersion of milled ACP in methacrylate resin sufficiently enhanced filler/matrix interactions to result in improved biaxial flexure strength (BFS), without compromising the remineralizing potential of the composites. Unmilled and wet-milled zirconia-hybridized ACP (Zr-ACP) fillers were characterized by PSD analysis, X-ray diffraction, thermogravimetric and chemical analysis, infrared spectroscopy, and scanning electron microscopy. Composite specimens made from a photoactivated, ternary methacrylate resin admixed with a mass fraction of 40% of un-milled or milled Zr-ACP were evaluated for the BFS (dry and wet) and for the release of calcium and phosphate ions into saline solutions. While having no apparent effect on the structure, composition, and morphology/topology of the fillers, milling significantly reduced the average size of Zr-ACP particulates (median diameter, dm = 0.9 ± 0.2 ,m) and the spread of their PSD. Better dispersion of milled Zr-ACP in the resins resulted in the improved BFS of the composites, even after aqueous soaking, and also gave a satisfactory ion release profile. The demonstrated improvement in the mechanical stability of anti-demineralizing/remineralizing ACP composites based on milled Zr-ACP filler may be beneficial in potentially extending their dental utility. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2007 [source] Heterogeneous expression of Wnt/,-catenin target genes within colorectal cancerINTERNATIONAL JOURNAL OF CANCER, Issue 9 2007Falk Hlubek Abstract Invasion of common colorectal adenocarcinomas is coupled with a transient loss of epithelial differentiation of tumor cells. Previously, we have shown that dedifferentiated tumor cells at the invasive front (IF) accumulate the transcriptional activator ,-catenin in the nucleus, in contrast to cells of the tumor center. To characterize the cells of these two morphogenic tumor areas, gene expression profiling was performed. Our study demonstrates that intratumorous heterogeneity in colorectal cancer correlates with differential expression of 510 genes between the central tumor region (TC) and the IF. Many genes differentially expressed at the IF are involved in cellular invasion processes like cell motility, cell adhesion and extracellular matrix interaction. This in vivo analysis shows overexpression of known Wnt/,-catenin target genes either in the entire tumor tissue (compared to normal mucosa) or specifically at the IF. Thus, even though all tumor cells overexpress ,-catenin, the existence of at least 2 groups of Wnt/,-catenin target genes selectively activated in different tumor regions is suggested. The concomitant high expression of inflammation- and tissue repair-related genes at the IF supports the hypothesis that an inflammation-activated microenvironment may trigger selective Wnt/,-catenin target gene expression and contribute to the malignant progression of colorectal cancer. © 2007 Wiley-Liss, Inc. [source] Modulation of expression of LDH isoenzymes in endothelial cells by laminin: Implications for angiogenesisJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 6 2008V.B. Sameer Kumar Abstract Endothelial cell (EC) matrix interaction is critical in angiogenesis. Although matrix components can regulate the process of angiogenesis by acting as a reservoir of various cytokines, it is not clear if extracellular matrix (ECM) can modulate the production and activity of angiogenic cytokines. Investigations were therefore carried out to study the influence of the basement membrane (BM) protein, laminin (Ln) on the activity of vascular endothelial growth factor (VEGF), the major angiogenic cytokine, using isolated human umbilical vein ECs (HUVECs) in culture. Analysis of the biochemical markers of angiogenesis confirmed proangiogenic effect of Ln. The levels of VEGF protein and mRNA were not different in cells maintained on Ln, collagen I or polylysine substrata. Chorioallantoic membrane assay using VEGF isolated from cell extracts however revealed that Ln increased its angiogenic potency. Immunoblotting and HPLC analysis showed considerable reduction in poly adenosyl ribosylation of VEGF associated with a significant decrease in the levels of NAD+, in cells maintained on Ln substrata. Further, a shift in the isoenzymic pattern of LDH towards the B rich forms and an upregulation of LDH B gene were observed in cells maintained on Ln. Ln modulates expression of LDH gene through ,6,4 integrin mediated downstream signaling involving p38 mitogen activated protein kinases (MAPK) pathway. It thus appears that Ln can affect aerobic metabolism of ECs by modulating the expression of LDH isoenzymes resulting in a decrease in the level of NAD+ that can cause a reduction in the poly adenosyl ribosylation of VEGF altering its angiogenic potency. J. Cell. Biochem. 103: 1808,1825, 2008. © 2007 Wiley-Liss, Inc. [source] Reactions of Th and U Atoms with C2H2: Infrared Spectra and Relativistic Calculations of the Metallacyclopropene, Actinide Insertion, and Ethynyl ProductsCHEMISTRY - A EUROPEAN JOURNAL, Issue 32 2006Lester Andrews Prof. Dr. Abstract Reactions of laser-ablated Th and U atoms with C2H2 during condensation with excess argon at 7 K give several new product species. The metallacyclopropene, inserted hydride, and actinide ethynyl are identified from isotopic frequencies and relativistic DFT calculations. The higher-energy vinylidine isomer was not observed. These actinide metallacyclopropenes exhibit substantially stronger bonding interactions than found recently for the Pd and Pt metals. In the case of Th(C2H2) the argon matrix interaction is strong enough to reverse the computed order of states (MR-CISD) in favor of a triplet ground state for the (Ar)n(Th(C2H2)) complex. The nature of the electronic interactions between various metal atoms and acetylene is compared and the origin of the particularly strong interaction for U and Th is traced to the higher energy of their 6d orbitals. The ThCCH and UCCH actinide ethynyl products are also observed and characterized by CC stretching modes 38±2 cm,1 lower than acetylene itself. [source] Design of Peptide Hydroxamate-Based Photoreactive Activity-Based Probes of Zinc-Dependent MetalloproteasesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 11 2010Paul P. Geurink Abstract Metalloproteases (ADAMs, MMPs) are multidomain proteins that play key roles in extracellular matrix remodelling and degradation, in cell,cell and cell,matrix interactions and in the proteolytic liberation of membrane-anchored proforms of cytokines and growth factors, the so-called ectodomainshedding. In this work we describe the development ofphotoactivatable activity-based probes with which active metalloproteases can be visualised. Our probes are based on the succinyl hydroxamate motif and differ in the positioning of the trifluoromethylphenyldiazirine photoreactive group. We demonstrate that directing the photoactivatable group towards the S1, pocket yields activity-based probes more effective than the corresponding probe with the photoactivatable group directed towards the S2, pocket. [source] Expression of one sponge Iroquois homeobox gene in primmorphs from Suberites domuncula during canal formationEVOLUTION AND DEVELOPMENT, Issue 3 2003Sanja Perovi SUMMARY Sponges (Porifera) represent the evolutionary oldest multicellular animals. They are provided with the basic molecules involved in cell,cell and cell,matrix interactions. We report here the isolation and characterization of a complementary DNA from the sponge Suberites domuncula coding for the sponge homeobox gene, SUBDOIRX-a. The deduced polypeptide with a predicted Mr of 44,375 possesses the highly conserved Iroquois-homeodomain. We applied in situ hybridization to localize Iroquois in the sponge. The expression of this gene is highest in cells adjacent to the canals of the sponge in the medulla region. To study the expression of Iroquois during development, the in vitro primmorph system from S. domuncula was used. During the formation of these three-dimensional aggregates composed of proliferating cells, the expression of Iroquois depends on ferric iron and water current. An increased expression in response to water current is paralleled with the formation of canal-like pores in the primmorphs. It is suggested that Iroquois expression is involved in the formation of the aquiferous system, the canals in sponges and the canal-like structures in primmorphs. [source] Systemic therapy for metastatic malignant melanoma , from deeply disappointing to bright future?EXPERIMENTAL DERMATOLOGY, Issue 5 2008Paul Lorigan Abstract:, The last decade has seen a considerable improvement in the understanding of the biology of melanoma. Advances have come in the understanding of the importance of critical oncogenes and tumour suppressor genes, epigenetic phenomena, signalling pathways, drug resistance mechanisms, the pivotal role of the local immune system, and the importance of cell,cell and cell,matrix interactions. Many of these pathways and interactions include potentially ,drugable' targets. These developments have allowed the identification and/or design of a range of new, targeted therapies. Evaluation of these new drugs has brought a whole new series of challenges. These include indentification of appropriate pre-clinical models, overcoming the redundancy inbuilt in complex biological systems, identification of appropriate molecular and clinical endpoints to show that the drug is hitting the target, how to combine treatments, and new toxicities. For the first time, there is the possibility of personalised treatment for melanoma patients, based on individual host and tumour characteristics. This paper discusses the range of new drugs and targets have been identified, the outcome of clinical trials, and the directions for future advances. [source] HSP27 mediates SPARC-induced changes in glioma morphology, migration, and invasionGLIA, Issue 10 2008William A. Golembieski Abstract Secreted protein acidic and rich in cysteine (SPARC) regulates cell,extracellular matrix interactions that influence cell adhesion and migration. We have demonstrated that SPARC is highly expressed in human gliomas, and it promotes brain tumor invasion in vitro and in vivo. To further our understanding regarding SPARC function in glioma migration, we transfected SPARC-green fluorescent protein (GFP) and control GFP vectors into U87MG cells, and assessed the effects of SPARC on cell morphology, migration, and invasion after 24 h. The expression of SPARC was associated with elongated cell morphology, and increased migration and invasion. The effects of SPARC on downstream signaling were assessed from 0 to 6 h and 24 h. SPARC increased the levels of total and phosphorylated HSP27; the latter was preceded by activation of p38 MAPK and inhibited by the p38 MAPK inhibitor SB203580. Augmented expression of SPARC was correlated with increased levels of HSP27 mRNA. In a panel of glioma cell lines, increasing levels of SPARC correlated with increasing total and phosphorylated HSP27. SPARC and HSP27 were colocalized to invading cells in vivo. Inhibition of HSP27 mRNA reversed the SPARC-induced changes in cell morphology, migration, and invasion in vitro. These data indicate that HSP27, a protein that regulates actin polymerization, cell contraction, and migration, is a novel downstream effector of SPARC-regulated cell morphology and migration. As such, it is a potential therapeutic target to inhibit SPARC-induced glioma invasion. © 2008 Wiley-Liss, Inc. [source] Consortium for osteogenesis imperfecta mutations in the helical domain of type I collagen: regions rich in lethal mutations align with collagen binding sites for integrins and proteoglycans,,HUMAN MUTATION, Issue 3 2007Joan C. Marini Abstract Osteogenesis imperfecta (OI) is a generalized disorder of connective tissue characterized by fragile bones and easy susceptibility to fracture. Most cases of OI are caused by mutations in type I collagen. We have identified and assembled structural mutations in type I collagen genes (COL1A1 and COL1A2, encoding the pro,1(I) and pro,2(I) chains, respectively) that result in OI. Quantitative defects causing type I OI were not included. Of these 832 independent mutations, 682 result in substitution for glycine residues in the triple helical domain of the encoded protein and 150 alter splice sites. Distinct genotype,phenotype relationships emerge for each chain. One-third of the mutations that result in glycine substitutions in ,1(I) are lethal, especially when the substituting residues are charged or have a branched side chain. Substitutions in the first 200 residues are nonlethal and have variable outcome thereafter, unrelated to folding or helix stability domains. Two exclusively lethal regions (helix positions 691,823 and 910,964) align with major ligand binding regions (MLBRs), suggesting crucial interactions of collagen monomers or fibrils with integrins, matrix metalloproteinases (MMPs), fibronectin, and cartilage oligomeric matrix protein (COMP). Mutations in COL1A2 are predominantly nonlethal (80%). Lethal substitutions are located in eight regularly spaced clusters along the chain, supporting a regional model. The lethal regions align with proteoglycan binding sites along the fibril, suggesting a role in fibril,matrix interactions. Recurrences at the same site in ,2(I) are generally concordant for outcome, unlike ,1(I). Splice site mutations comprise 20% of helical mutations identified in OI patients, and may lead to exon skipping, intron inclusion, or the activation of cryptic splice sites. Splice site mutations in COL1A1 are rarely lethal; they often lead to frameshifts and the mild type I phenotype. In ,2(I), lethal exon skipping events are located in the carboxyl half of the chain. Our data on genotype,phenotype relationships indicate that the two collagen chains play very different roles in matrix integrity and that phenotype depends on intracellular and extracellular events. Hum Mutat 28(3), 209,221, 2007. Published 2006 Wiley-Liss, Inc. [source] Regulation of chondrocyte differentiation by the actin cytoskeleton and adhesive interactionsJOURNAL OF CELLULAR PHYSIOLOGY, Issue 1 2007Anita Woods Chondrocyte differentiation is a multi-step process characterized by successive changes in cell morphology and gene expression. In addition to tight regulation by numerous soluble factors, these processes are controlled by adhesive events. During the early phase of the chondrocyte life cycle, cell,cell adhesion through molecules such as N-cadherin and neural cell adhesion molecule (N-CAM) is required for differentiation of mesenchymal precursor cells to chondrocytes. At later stages, for example in growth plate chondrocytes, adhesion signaling from extracellular matrix (ECM) proteins through integrins and other ECM receptors such as the discoidin domain receptor (DDR) 2 (a collagen receptor) and Annexin V is necessary for normal chondrocyte proliferation and hypertrophy. Cell,matrix interactions are also important for chondrogenesis, for example through the activity of CD44, a receptor for Hyaluronan and collagens. The roles of several signaling molecules involved in adhesive signaling, such as integrin-linked kinase (ILK) and Rho GTPases, during chondrocyte differentiation are beginning to be understood, and the actin cytoskeleton has been identified as a common target of these adhesive pathways. Complete elucidation of the pathways connecting adhesion receptors to downstream effectors and the mechanisms integrating adhesion signaling with growth factor- and hormone-induced pathways is required for a better understanding of physiological and pathological skeletal development. J. Cell. Physiol. 213: 1,8, 2007. © 2007 Wiley-Liss, Inc. [source] PR-39 coordinates changes in vascular smooth muscle cell adhesive strength and locomotion by modulating cell surface heparan sulfate,matrix interactionsJOURNAL OF CELLULAR PHYSIOLOGY, Issue 2 2001John H. Chon PR-39 is proline-rich peptide produced at sites of tissue injury. While the functional properties of this peptide have not been fully defined, PR-39 may be an important regulator of processes related to cell-matrix adhesion since it reportedly upregulates syndecan-4, which is a critical determinant of focal adhesion formation. The ability of PR-39 to modulate the adhesion and chemokinetic migration behavior of arterial smooth muscle cells (SMCs) in a fashion coordinated with syndecan-4 expression was investigated. Treatment of SMCs with PR-39 did not alter syndecan-1 mRNA, but did induce a two-fold increase in syndecan-4 mRNA (P,<,0.0001) and significantly enhanced cell surface expression of both syndecan-4 (P,<,0.01) and heparan sulfate (HS) (P,<,0.05). These observations were consistent with an observed increase in cell-matrix adhesive strength (P,<,0.05) and a reduction in cell speed (P,<,0.01) on fibronectin-coated substrates. Incubation of PR-39 treated cells with a soluble fibronectin derived heparin-binding peptide, as a competitive inhibitor of heparan sulfate/matrix interactions, abolished these effects. These data suggest that PR-39 mediated alterations of cell adhesion and motility may be related, in part, to the increased expression of heparan sulfate glycosaminoglycans (GAGs) that accompany the upregulation of cell surface syndecan-4. Futhermore, this investigation supports the notion that factors which control syndecan-4 expression may play an important role in regulating adhesion related cell processes. © 2001 Wiley-Liss, Inc. [source] Functional integrin subunits regulating cell,matrix interactions in the intervertebral discJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 6 2007Christopher L. Gilchrist Abstract Cellular interactions with the extracellular matrix are key factors regulating cell survival, differentiation, and response to environmental stimuli in cartilagenous tissues. Much is known about the extracellular matrix proteins in the intervertebral disc (IVD) and their variations with region, age, or degenerative state of the tissue. In contrast, little is known of the integrin cell surface receptors that directly bind to and interact with these matrix proteins in the IVD. In almost all tissues, these integrin-mediated cell,matrix interactions are important for transducing environmental cues arising from mechanical stimuli, matrix degradation fragments, and cytokines into intracellular signals. In this study, cells from the nucleus pulposus and anulus fibrosus regions of porcine IVDs were analyzed via flow cytometry to quantify integrin expression levels upon isolation and after monolayer culture. Assays of cell attachment to collagens, fibronectin, and laminin were performed after functional blocking of select integrin subunits to evaluate the role of specific integrins in cell attachment. In situ distribution and co-localization of integrins and laminin were also characterized. Results identify integrin receptors critical for IVD cell interactions with collagens (,1,1) and fibronectin (,5,1). Additionally, dramatic differences in cell,laminin interactions were observed between cells of the nucleus and anulus regions, including differences in ,6 integrin expression, cell adhesion to laminin, and in situ pericellular environments. These findings suggest laminin,cell interactions may be important and unique to the nucleus pulposus region of the IVD. The results of this study provide new information on functional cell,matrix interactions in tissues of the IVD. © 2006 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 25: 829,840, 2007 [source] Raman spectroscopy of II,VI semiconductor nanostructures: CdS quantum dotsJOURNAL OF RAMAN SPECTROSCOPY, Issue 2 2003B. Schreder Abstract Information about confinement effects and dot,matrix interactions of CdS nanoparticles was obtained from resonance Raman spectroscopy. The quantum dots had diameters of 3 and 5 nm and were prepared with and without organic spacer groups. It was found that the spacer improves the quality of the nanocrystallites. No phonon confinement shift could be observed even for the small quantum dots. The linewidths of the overtone series point to a mechanism of vibrational relaxation which is dominated by the decay of the LO phonons into acoustic phonons. Copyright © 2003 John Wiley & Sons, Ltd. [source] FGF-2 but not FGF-1 binds fibrin and supports prolonged endothelial cell growthJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 6 2003A. Sahni Summary., Endothelial cell viability and growth are dependent on both polypeptide growth factors, and integrin-mediated matrix interactions. We have now examined the ability of fibrin-binding and non-binding growth factors to support long-term endothelial cell growth in the presence or absence of the soluble form. Endothelial cells were cultured on a fibrin surface, with or without FGF-1 or FGF-2, and proliferation was determined by 3H-thymidine incorporation. Cells cultured on fibrin with no growth factor showed minimal proliferation up to 96 h. In contrast, when FGF-2 was incorporated into fibrin, proliferation was increased 6.5 ± 0.6-fold, equal to growth on a fibrin surface with FGF-2 continually present in the medium. Thymidine incorporation was similar when cells were cultured on a fibrin surface that had been incubated with FGF-2 and then the growth factor removed (8.6 ± 0.5-fold). In contrast to results with FGF-2, a surface of fibrin exposed to FGF-1 supported minimal growth, whereas growth was comparable to either FGF-1 or FGF-2 present in the medium. Comparable results were observed when proliferation was quantitated by cell counting at times up to 48 h. Binding studies demonstrated no high-affinity interaction of FGF-1 with fibrinogen or fibrin. We conclude that FGF-2 bound to fibrin supports prolonged endothelial cell growth as well as soluble FGF-2, whereas FGF-1 does not bind to fibrin and can support endothelial cell growth only if continually present in soluble form. Fibrin may serve as a matrix reservoir for FGF-2 to support cell growth at sites of injury or thrombosis. [source] Aragonite crystalline matrix as an instructive microenvironment for neural developmentJOURNAL OF TISSUE ENGINEERING AND REGENERATIVE MEDICINE, Issue 8 2008H. Peretz Abstract The ability to mimic cell,matrix interactions in a way that closely resembles the natural environment is of a great importance for both basic neuroscience and for fabrication of potent scaffolding materials for nervous tissue engineering. Such scaffolding materials should not only facilitate cell attachment but also create a microenvironment that provides essential developmental and survival cues. We previously found that porous aragonite crystalline matrices of marine origin are an adequate and active biomaterial that promotes neural cell growth and tissue development. Here we studied the mechanism underlying these neural cell,material interactions, focusing on the three-dimensional (3D) surface architecture and matrix activity of these scaffolds. We introduced a new cloning technique of the hydrozoan Millepora dichotoma, through which calcein or 45Ca2+ were incorporated into the organism's growing skeleton and neuronal cells could then be cultured on the labelled matrices. Herein, we describe the role of matrix 3D architecture on neural cell type composition and survival in culture, and report for the first time on the capacity of neurons and astrocytes to exploit calcium ions from the supporting biomatrix. We found that hippocampal cells growing on the prelabelled aragonite lattice took up aragonite-derived Ca2+, and even enhanced this uptake when extracellular calcium ions were chelated by EGTA. When the aragonite-derived Ca2+ uptake was omitted by culturing the cells on coral skeletons coated with gold, cell survival was reduced but not arrested, suggesting a role for matrix architecture in neural survival. In addition, we found that the effects of scaffold architecture and chemistry on cell survival were more profound for neurons than for astrocytes. We submit that translocation of calcium from the biomaterial to the cells activates a variety of membrane-bound signalling molecules and leads to the subsequent cell behaviour. This kind of cell,material interaction possesses great potential for fabricating advanced biomaterials for neural tissue-engineering applications. Copyright © 2008 John Wiley & Sons, Ltd. [source] Differential expression of glycans in the hippocampus of rats trained on an inhibitory learning paradigmNEUROPATHOLOGY, Issue 6 2006Alejandra Hidalgo The glycan chains of glycoconjugates play important roles in cell,cell and cell,matrix interactions. In the CNS, previous studies on learning and memory suggest the importance of oligosaccharides attached to glycoconjugates in the modulation of synaptic connections. We studied the hippocampal glycan distribution of rats subject to an inhibitory avoidance task. The expression of glycans was examined by lectin-histochemistry using Vicia villosa lectin (VVL) for terminal ,/, N-acetylgalactosamine (,/, GalNAc); Galanthus nivalus lectin (GNL) for terminal mannose ,-1,3 (Man ,-1,3); Peanut agglutinin (PNA) for galactose ,-1,3N-acetylgalactosamine (Gal ,-1,3 GalNAc); Erythrina cristagalli lectin (ECL) for galactose ,-1,4 N-acetylglucosamine (Gal ,-1,4 GlcNAc); Sambucus nigra lectin (SNA) for sialic acid ,-2.6 galactose (SA ,-2,6 Gal); Maackia amurensis lectin II (MAL II) for sialic acid ,-2,3 (SA ,-2,3); Wheat germ agglutinin (WGA) for terminal N-acetylglucosamine with/without sialic acid (GlcNAc wo SA); succynilated WGA (sWGA) for terminal N-acetylglucosamine without sialic acid (terminal GlcNAc without SA); Griffonia simplicifolia lectin II (GSL II) for terminal ,/, N-acetylglucosamine (,/, GlcNAc terminal); and Lotus tetragonolobus lectin (LTL) ,,fucose. Two groups of 10 animals were examined: non-trained (Control) and Trained rats. ECL, sWGA and GSL II were negative for both groups in all the hippocampal subfields studied. For both groups, VVL was negative in CA4 and granular cells of the Dentate Gyrus (DG) and LTL was negative in the CA4 subfield. Expression of ,/, GalNAc, , -fucose and GlcNAc in other hippocampal subfields was positive, with no differences between groups. However, expression of Man ,-1,3 was significantly higher in the CA1, CA2, CA3, and CA4 subfields in the Trained group. On the other hand, expression of Gal ,-1,3 GalNAc was significantly low in CA4 and DG in the Trained group. In conclusion, the results here presented indicate that the exposure of rats to an associative behavioral paradigm related to declarative memory, involves some regulatory mechanism/s for the differential patterns of glycan expression. [source] Analysis of vitamin D-regulated gene expression in LNCaP human prostate cancer cells using cDNA microarraysTHE PROSTATE, Issue 3 2004Aruna V. Krishnan Abstract BACKGROUND 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] exerts growth inhibitory, pro-differentiating, and pro-apoptotic effects on prostate cells. To better understand the molecular mechanisms underlying these actions, we employed cDNA microarrays to study 1,25(OH)2D3 -regulated gene expression in the LNCaP human prostate cancer cells. METHODS mRNA isolated from LNCaP cells treated with vehicle or 50 nM 1,25(OH)2D3 for various lengths of time were hybridized to microarrays carrying approximately 23,000 genes. Some of the putative target genes revealed by the microarray analysis were verified by real-time PCR assays. RESULTS 1,25(OH)2D3 most substantially increased the expression of the insulin-like growth factor binding protein-3 (IGFBP-3) gene. Our analysis also revealed several novel 1,25(OH)2D3 -responsive genes. Interestingly, some of the key genes regulated by 1,25(OH)2D3 are also androgen-responsive genes. 1,25(OH)2D3 also down-regulated genes that mediate androgen catabolism. CONCLUSIONS The putative 1,25(OH)2D3 target genes appear to be involved in a variety of cellular functions including growth regulation, differentiation, membrane transport, cell,cell and cell,matrix interactions, DNA repair, and inhibition of metastasis. The up-regulation of IGFBP-3 gene has been shown to be crucial in 1,25(OH)2D3 -mediated inhibition of LNCaP cell growth. 1,25(OH)2D3 regulation of androgen-responsive genes as well as genes involved in androgen catabolism suggests that there are interactions between 1,25(OH)2D3 and androgen signaling pathways in LNCaP cells. Further studies on the role of these genes and others in mediating the anti-cancer effects of 1,25(OH)2D3 may lead to better approaches to the prevention and treatment of prostate cancer. © 2004 Wiley-Liss, Inc. [source] Cell deposition system based on laser guidanceBIOTECHNOLOGY JOURNAL, Issue 9 2006Russell K. Pirlo Abstract We have designed a laser cell deposition system that employs the phenomenon of laser guidance to place single cells at specific points in a variety of in vitro environments. Here, we describe the components of the system: the laser optics, the deposition chamber, the microinjection cell feeding system and our custom system control software application. We discuss the requirements and challenges involved in laser guidance of cells and how our present system overcomes these challenges. We demonstrate that the patterning system is accurate within one micrometer by repeatedly depositing polymer microspheres and measuring their position. We demonstrate its ability to create highly defined living patterns of cells by creating a defined pattern of neurons with neurite extensions displaying normal function. We found that the positional accuracy of our system is smaller than the variations in cell size and pattern disruptions that occur from normal cell movement during substrate adhesion. The laser cell deposition system is a potentially useful tool that can be used to achieve site- and time-specific placement of an individual cell in a cell culture for the systematic investigation of cell-cell and cell-extracellular matrix interactions. [source] Involvement of E-cadherin, ,-catenin, Cdc42 and CXCR4 in the progression and prognosis of cutaneous melanomaBRITISH JOURNAL OF DERMATOLOGY, Issue 6 2007M.G. Tucci Summary Background, A key event in cancer metastasis is the migration of tumour cells from their original location to a secondary site. The development of melanoma may be viewed as a consequence of the disruption of homeostatic mechanisms in the skin of the original site. Objectives, To investigate whether dysregulation of cell motility (Cdc42 expression), escaping the control of cell,cell and cell,matrix interactions (E-cadherin, ,-catenin expression), enhances melanoma progression, and whether chemokine receptors (CXCR4) mediate cell migration and activation during invasion and metastasis development. Methods, The immunohistochemical expression of Cdc42, E-cadherin, ,-catenin and CXCR4 was investigated in 30 patients with surgically treated nodular melanoma, 18 alive and disease free and 12 with a fatal outcome due to metastatic disease. Results, E-cadherin expression was significantly reduced (P < 0·05) and cytoplasmic ,-catenin was increased in the patients who had died compared with disease-free individuals, while membrane expression of ,-catenin was similar in the two groups. Patients with fatal outcome had increased Cdc42 (P < 0·01) and CXCR4 (P < 0·05). In this group a positive correlation was found between melanocytic Cdc42 expression and Breslow thickness (r = 0·598, P < 0·05) and between CXCR4 expression and Breslow thickness (r = 0·583, P < 0·05). Conclusions, Findings suggest that primary cutaneous melanoma with a high Breslow thickness is characterized by tumour cells with high motility and invasion ability, in line with the hypothesis that low E-cadherin levels and overexpression of Cdc42 and CXCR4 could be prognostic markers of poor outcome. [source] Mast cell matrix interactionsCLINICAL & EXPERIMENTAL ALLERGY, Issue 4 2000Okayama No abstract is available for this article. [source] PR-39 coordinates changes in vascular smooth muscle cell adhesive strength and locomotion by modulating cell surface heparan sulfate,matrix interactionsJOURNAL OF CELLULAR PHYSIOLOGY, Issue 2 2001John H. Chon PR-39 is proline-rich peptide produced at sites of tissue injury. While the functional properties of this peptide have not been fully defined, PR-39 may be an important regulator of processes related to cell-matrix adhesion since it reportedly upregulates syndecan-4, which is a critical determinant of focal adhesion formation. The ability of PR-39 to modulate the adhesion and chemokinetic migration behavior of arterial smooth muscle cells (SMCs) in a fashion coordinated with syndecan-4 expression was investigated. Treatment of SMCs with PR-39 did not alter syndecan-1 mRNA, but did induce a two-fold increase in syndecan-4 mRNA (P,<,0.0001) and significantly enhanced cell surface expression of both syndecan-4 (P,<,0.01) and heparan sulfate (HS) (P,<,0.05). These observations were consistent with an observed increase in cell-matrix adhesive strength (P,<,0.05) and a reduction in cell speed (P,<,0.01) on fibronectin-coated substrates. Incubation of PR-39 treated cells with a soluble fibronectin derived heparin-binding peptide, as a competitive inhibitor of heparan sulfate/matrix interactions, abolished these effects. These data suggest that PR-39 mediated alterations of cell adhesion and motility may be related, in part, to the increased expression of heparan sulfate glycosaminoglycans (GAGs) that accompany the upregulation of cell surface syndecan-4. Futhermore, this investigation supports the notion that factors which control syndecan-4 expression may play an important role in regulating adhesion related cell processes. © 2001 Wiley-Liss, Inc. [source] Characterization of Tissue Transglutaminase in Human Osteoblast-like CellsJOURNAL OF BONE AND MINERAL RESEARCH, Issue 8 2001Deborah J. Heath Abstract Tissue transglutaminase (tTG) is a calcium-dependent and guanosine 5,-triphosphate (GTP) binding enzyme, which catalyzes the post-translational modification of proteins by forming intermolecular ,(,-glutamyl)lysine cross-links. In this study, human osteoblasts (HOBs) isolated from femoral head trabecular bone and two osteosarcoma cell lines (HOS and MG-63) were studied for their expression and localization of tTG. Quantitative evaluation of transglutaminase (TG) activity determined using the [1,414C]-putrescine incorporation assay showed that the enzyme was active in all cell types. However, there was a significantly higher activity in the cell homogenates of MG-63 cells as compared with HOB and HOS cells (p < 0.001). There was no significant difference between the activity of the enzyme in HOB and HOS cells. All three cell types also have a small amount of active TG on their surface as determined by the incorporation of biotinylated cadaverine into fibronectin. Cell surface-related tTG was further shown by preincubation of cells with tTG antibody, which led to inhibition of cell attachment. Western blot analysis clearly indicated that the active TG was tTG and immunocytochemistry showed it be situated in the cytosol of the cells. In situ extracellular enzyme activity also was shown by the cell-mediated incorporation of fluorescein cadaverine into extracellular matrix (ECM) proteins. These results clearly showed that MG-63 cells have high extracellular activity, which colocalized with the ECM protein fibronectin and could be inhibited by the competitive primary amine substrate putrescine. The contribution of tTG to cell surface/matrix interactions and to the stabilization of the ECM of osteoblast cells therefore could by an important factor in the cascade of events leading to bone differentiation and mineralization. [source] | |||||||||||||||||||