Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Matrix”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 649 records · Page 36Linked to original sources
PubMed2004

Effect of matrix and solvent on the analysis of novel poly(phenylenevinylene) derivatives by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

Six novel poly(phenylenevinylene) (PPV) derivatives carrying butoxy or myrtanyl groups, including poly(2-butoxy-m-phenylenevinylene) (Bu-MPV), poly(2,5-dibutoxy-p-phenylenevinylene-alter-p-phenylenevinylene) (Bu-PPPV), poly(2,5-dibutoxy-p-phenylenevinylene-alter-m-phenylenevinylene) (Bu-PMPV), poly(2-myrtanyl-m-phenylenevinylene) (Myr-MPV), poly(2,5-dimyrtanyl-p-phenylenevinylene-alter-p-phenylenevinylene) (Myr-PPPV), and poly(2,5-dimyrtanyl-p-phenylenevinylene-alter-m-phenylenevinylene) (Myr-PMPV), were characterized by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS). The repeat unit mass and the end-group structures of each sample were obtained. Distinctly different spectra with different ion series and/or different ion signal intensities were observed for the analytes Bu-MPV, Myr-MPV, Bu-PPPV, Myr-PPPV and Myr-PMPV when different matrices were used, and different ion series were acquired when different solvents were used for Myr-PPPV and Myr-PMPV. The results show that the PPV oligomers with different shapes and/or with different end groups can be selectively desorbed and ionized in MALDI by using different matrices.

Anthralin↗
PubMed2005

Matrix-assisted ultraviolet laser desorption/ionization time-of-flight mass spectrometry of beta-(1 --> 3), beta-(1 --> 4)-xylans from Nothogenia fastigiata using nor-harmane as matrix.

Three xylan fractions isolated from the red seaweed Nothogenia fastigiata (Nemaliales) were analyzed by ultraviolet matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (UV-MALDI-TOFMS). UV-MALDI-TOFMS was carried out in the linear and reflectron modes, and as routine in the positive and negative ion modes. Of the several matrices tested, nor-harmane was the only effective one giving good spectra in the positive ion mode. The number-average molar masses of two of the fractions, calculated from the distribution profiles, were lower than those determined previously by (1)H NMR analysis, suggesting a decrease in the ionization efficiency with increasing molecular weight; weight-average molar mass and polydispersity index were also determined. As the xylans retained small but significant quantities of calcium salts, the influence of added Ca(2+) as CaCl(2) on UV-MALDI-MS was investigated. The simultaneous addition of sodium chloride and calcium chloride was also analyzed. Addition of sodium chloride did not change the distribution profile of the native sample showing that the inhibitory effect is due to Ca(2+) and not to Cl(-). Addition of calcium chloride with 1:1 analyte/salt molar ratio gave spectra with less efficient desorption/ionization of oligomers; the signals of these oligomers were completely suppressed when the addition of the salt became massive (1:100 analyte/salt molar ratio).

Carbolines↗
PubMed2006

Iminodiacetic acid derivatized porous silicon as a matrix support for sample pretreatment and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry analysis.

Iminodiacetic acid (IDA)-1,2-epoxy-9-decene has been synthesized and covalently linked to the surface of porous silicon wafer through a photochemical reaction. The negatively charged carboxylic acid groups on the porous silicon wafer are capable of binding oppositely charged species from sample solutions through electrostatic interactions. This allows the removal of contaminants prior to matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) by simply washing the porous silicon surface. The carboxylic acid end groups on porous silicon can be used to selectively bind and concentrate target species in sample solutions. Furthermore, Fe(3+)-IDA-derivatized porous silicon was prepared to specifically and effectively concentrate phosphopeptides from the tryptic digests of phosphoproteins, followed by MALDI-MS analysis.

Caseins↗
PubMed1996

Extracellular matrix components of the mouse thymus microenvironment. V. Interferon-gamma modulates thymic epithelial cell/thymocyte interactions via extracellular matrix ligands and receptors.

Extracellular matrix (ECM) proteins influence cell migration and differentiation in a variety of cell systems. Within the thymus, the ECM distribution pattern is conserved among various mammalian species, but its physiological role is not completely understood. Interferon-gamma (IFN-gamma), a cytokine produced by thymocytes, is able to in vitro modulate ECM production by thymic epithelial cells (TEC) in a dose-dependent biphasic pattern. In the same model, we determined herein that the expression of VLA-5 and VLA-6 (fibronectin and laminin receptors, respectively) were upregulated by low doses of IFN-gamma, whereas high doses of the cytokine induced an opposite effect. In a second in vitro system, we evidenced that thymocyte adhesion to a TEC line was also modulated by IFN-gamma. Importantly, such effects were due to the biphasic modulation of ECM ligands and receptors since they could be specifically prevented by preincubating the TEC cultures with anti-ECM or anti-ECM receptor antibodies. Additionally, spontaneous thymocyte release from thymic nurse cells was similarly biphasically modulated by IFN-gamma. Our data provide support for the notion that thymocyte-derived products can play a role in the dialogue that exists in the thymus, involving differentiating thymocytes and microenvironmental cells. Moreover, we bring arguments indicating that one of the implicated mechanisms involved is the modulation of ECM ligands and receptors by the thymic epithelium.

Animals↗
PubMed2000

Assembly and release of human immunodeficiency virus type 1 Gag proteins containing tandem repeats of the matrix protein coding sequences in the matrix domain.

We have constructed human immunodeficiency virus (HIV) gag mutants by increasing the matrix protein (MA) sequences via tandemly repeated duplication of the central 107-MA codons. Instead of a total of 132 amino acid residues for the wild-type MA, the resultant mutants designated as MA2, MA3, and MA4 contained a total of 242, 352, and 462 codons in the MA domains, respectively. Analysis indicated that the addition of 110 or 220 amino acid residues to the MA did not significantly affect the assembly, release, and processing of particles; however, particle production was markedly reduced when another copy of 110 residues was added to the MA. Subcellular fractionation analysis suggested that the MA tandem repeat mutations enhanced the Gag membrane affinity, in a manner which correlated with the copy number of MA sequences. The effects of enhanced membrane affinity were substantially reduced when sequences downstream of the capsid (CA) domain were deleted. Sucrose density gradient fractionation analysis showed that particles produced by the large insertion mutants possessed wild-type (wt) HIV particle density. Truncation of sequences downstream of the nucleocapsid (NC) domains of the mutants did not influence the budding of particles. In contrast, particle budding was severely impaired when sequences downstream of the CA domain were truncated. Particle densities for the large Gag proteins, which were truncated at the C-terminus of CA, were about 1.12-1.14 g/ml lower than that for wt. Our results suggest that the HIV MA domain could adopt insertions of large protein sequences, and strongly support the proposal that the NC and p2 domains play a crucial role in the process of correct Gag protein packing.

Cell Line↗
PubMed1993

Renin-angiotensin system and myocardial collagen matrix remodeling in hypertensive heart disease: in vivo and in vitro studies on collagen matrix regulation.

The interstitial space of the myocardium is composed of nonmyocyte cells and a highly organized collagen network which serves to maintain the architecture and mechanical behavior of the myocardial walls. It is the myocardial collagen matrix that determines myocardial stiffness in the normal and structurally remodeled myocardium. In hypertensive heart disease, the heterogeneity in myocardial structure, created by the altered behavior of nonmyocyte cells, particularly cardiac fibroblasts which are responsible for collagen synthesis and degradation, explains the appearance of diastolic and/or systolic dysfunction of the left ventricle that leads to symptomatic heart failure. Several lines of evidence suggest that circulating and myocardial renin-angiotensin systems (RAS) are involved in the regulation of the structural remodeling of the nonmyocyte compartment, including the cardioprotective effects of angiotensin converting enzyme (ACE) inhibition that was found to prevent myocardial fibrosis in the rat with renovascular hypertension. In cultured adult rat cardiac fibroblasts angiotensin II was shown to directly stimulate collagen synthesis and to inhibit collagenase activity, which is the key enzyme for collagen degradation, that would lead to collagen accumulation. In the spontaneously hypertensive rat, an appropriate experimental model for primary hypertension in man, left ventricular hypertrophy could be regressed and abnormal myocardial diastolic stiffness due to interstitial fibrosis could be restored to normal by inhibition of the myocardial RAS. These antifibrotic or cardioreparative effects of ACE inhibition that occurred irrespective of blood pressure normalization may be valuable in reversing left ventricular diastolic dysfunction in hypertensive heart disease.

Collagen↗
PubMed2004

Effect of interferon beta-1a on serum matrix metalloproteinase-9 (MMP-9) and tissue inhibitor of matrix metalloproteinase (TIMP-1) in relapsing remitting multiple sclerosis patients. One year follow-up results.

There is emerging evidence that matrix metalloproteinases (MMPs) might be involved in blood brain barrier (BBB) breakdown in multiple sclerosis. A group of natural tissue inhibitors of metalloproteinases (TIMPS) regulates proteolytic activity to prevent tissue damage. TIMP-1 and MMP-9 are known to be secreted as heterodimers and TIMP-1 preferentially functions to inhibit MMP-9 activity. In this present study, the effects of IFNbeta-1a on serum MMP-9 and TIMP-1 were evaluated longitudinally during a one-year period. The MMP-9 levels showed no significant changes while TIMP-1 levels gradually and significantly increased during 3rd and 6th months of therapy compared with pretreatment levels.

Adult↗
PubMed2005

Temporospatial expression of matrix metalloproteinases and tissue inhibitors of matrix metalloproteinases in mouse antigen-induced arthritis.

Several lines of evidence speak for an important role of matrix metalloproteinases (MMPs) in the development of progressive joint destruction. To better understand the role of MMPs and their tissue inhibitors (TIMPs) in this process, we have used the antigen-induced arthritis model to study the temporospatial expression of several MMPs and TIMPs during the progression of arthritis. Arthritis was induced by a single intra-articular injection of methylated bovine serum albumin (mBSA) into one or both knee joints of adult mice previously immunised against mBSA. Samples were collected at 3, 7, 21 and 42 days after induction of arthritis for histology and RNA extraction, and analysed by Northern hybridisation, histochemistry and immunohistochemistry for production of several MMPs and TIMPs -1, -2 and -3. A systematic analysis of MMP and TIMP mRNA levels in mouse knee joints demonstrated a general upregulation of both MMPs and TIMPs during progression of arthritis. Upregulation of MMP-9, -13 and -14 coincided with the advancement of cartilage degeneration, but the expression patterns of MMP-9 and -13 also followed the course of synovial inflammation. TIMPs were steadily upregulated throughout the examination period. Immunohistochemical localisation of MMPs and TIMPs suggested the synovium to be the major source of MMP and TIMP production in arthritis, although articular cartilage chondrocytes also showed an increased production of both MMPs and TIMPs.

Animals↗
PubMed1985

Immunological analysis of chick notochord and cartilage matrix development with antisera to cartilage matrix macromolecules.

Transverse frozen sections from the postcephalic region of stage 9-16 chick embryos and from the wing bud region of stage 17-31 embryos were stained with antibodies to the major extracellular matrix components of cartilage. These probes included unfractionated A1 and A2 antisera to the major cartilage proteoglycan, affinity-purified purified antibodies to the proteoglycan core protein and to Type II collagen, and a monoclonal antibody to keratan sulfate. In embryos as early as stage 10, notochord stained specifically with the keratan sulfate monoclonal antibody. At this stage the notochord, as well as surrounding tissues, were negative to cartilage proteoglycan and collagen antibodies. Positive staining with the latter probes was coordinately acquired by notochord cells and their accompanying sheath around stage 15, while surrounding tissues remained negative. At this stage, the ventral region of the perispinal cord sheath exhibited light staining with the proteoglycan and keratan sulfate antibodies though failing to react to Type II collagen antibodies. Positive staining of notochord and ventral spinal cord persisted through later developmental stages. As revealed by immunofluorescence, definitive vertebral chondroblasts first emerged at approximately stage 23 and definitive limb chondroblasts at stage 25. The results are discussed in terms of the possible multiple roles of notochord in early embryogenesis.

Animals↗
PubMed1989

Activation of matrix metalloproteinase 3 (stromelysin) and matrix metalloproteinase 2 ('gelatinase') by human neutrophil elastase and cathepsin G.

The ability of human neutrophil elastase and cathepsin G to activate matrix metalloproteinase 3 (MMP-3 = stromelysin) and MMP-2 ('gelatinase') purified from human rheumatoid synovial fibroblasts in culture was examined. The zymogen of MMP-3 (proMMP-3) was activated to full activity with elastase and cathepsin G by limited proteolysis of the molecule into two active forms of Mr approximately 45,000 and Mr approximately 25,000. In contrast, proMMP-2 was not activated at all by these neutrophil serine proteinases, although it was degraded into small fragments. These data suggest that neutrophil elastase and cathepsin G may play an important role in the activation of proMMP-3 in vivo in various inflammatory conditions, but proMMP-2 may be activated in different ways.

Cathepsin G↗
PubMed1993

In vitro Ca deposition by rat matrix vesicles: is the membrane association of alkaline phosphatase essential for matrix vesicle-mediated calcium deposition?

1. Phosphatidylinositol phospholipase C (PI-PLC) treatment of rachitic rat matrix vesicles (MVs) released about 80% of membrane-bound alkaline phosphatase (ALP), AMPase, PPiase into the media. 2. About 20% hydrolytic activity was not released from MV membranes by PI-PLC treatment. 3. SDS-polyacrylamide gel electrophoresis and Western blot analysis showed only one immunoreactive protein corresponding to the molecular weight of ALP present in the soluble fraction after PI-PLC treatment. 4. The specific activity of the released ALP was at least 5-fold higher than the residual activity. 5. After PI-PLC treatment, MVs also demonstrated an 80% reduction of AMP- or beta GP-dependent calcium deposition. 6. The soluble fraction containing 80% of ALP activity was unable to support calcium deposition. The mixing of the soluble and insoluble fractions after PI-PLC treatment failed to fully restore calcium-depositing activity.

Alkaline Phosphatase↗
PubMed2005

Quartz crystal microbalance biosensor study of endothelial cells and their extracellular matrix following cell removal: Evidence for transient cellular stress and viscoelastic changes during detachment and the elastic behavior of the pure matrix.

A quartz crystal microbalance (QCM) cell biosensor utilizing living endothelial cells (ECs) or human breast cancer cells (MCF-7) adhering to the gold QCM surface was used to study the relative contributions of the cells and their underlying extracellular matrix (ECM) to the measured QCM Deltaf and DeltaR shifts. The ECM represents a natural biomaterial that is synthesized by the cells to enable their attachment to surfaces. We followed the detachment of the ECs or MCF-7 cells from their ECM using a nonproteolytic method and were able to apportion the total frequency, Deltaf, decrease of the biosensor into contributions from cell attachment and from the intact underlying ECM. We also demonstrated that the Deltaf shift remaining after EC removal corresponds to ECM as determined by light microscopic visualization of the stained protein. During the process of cell detachment, we observed a novel transient increase in viscoelastic behavior expressed as a transient increase in the motional resistance, DeltaR, parameter. Then we showed via a simulation experiment using ECs stained with fluorescent rhodamine-labeled phalloidin, an actin stain, that the transient viscoelastic increase correlated with cellular stress exhibited by the cells during removal with ethylene glycol bis(2-aminoethyl ether)-N,N,N',N'- tetraacetic acid. Prior to cells lifting from their ECM, the attached ECs rearrange their actin microfilaments first into peripheral stress fibers and second into internal aggregates, to maintain cell-cell connectivity, retain their spread morphology, and attempt to adhere more tightly to their underlying ECM. The decrease in DeltaR following its transient rise corresponds to cells finally losing their attachment focal points and lifting from the ECM. We also characterized the normalized f shifts, -Delta(Deltaf)(ECM)/attached cell and -Delta(Deltaf)(cells)/attached cell, as a function of varying the number of adherent cells. Finally, we demonstrate that the underlying native ECM biomaterial, from which all cells have been removed, does not exhibit any significant level of energy dissipation, in contrast to the cells when they are attached to the ECM.

Biosensing Techniques↗
PubMed2006

The matrix reorganized: extracellular matrix remodeling and integrin signaling.

Via integrins, cells can sense dimensionality and other physical and biochemical properties of the extracellular matrix (ECM). Cells respond differently to two-dimensional substrates and three-dimensional environments, activating distinct signaling pathways for each. Direct integrin signaling and indirect integrin modulation of growth factor and other intracellular signaling pathways regulate ECM remodeling and control subsequent cell behavior and tissue organization. ECM remodeling is critical for many developmental processes, and remodeled ECM contributes to tumorigenesis. These recent advances in the field provide new insights and raise new questions about the mechanisms of ECM synthesis and proteolytic degradation, as well as the roles of integrins and tension in ECM remodeling.

Animals↗
PubMed2003

Down-regulation of tissue inhibitor of matrix metalloprotease-1 (TIMP-1) in aged human skin contributes to matrix degradation and impaired cell growth and survival.

Up regulation of matrix metalloproteinases (MMPs), particularly collagenase-1 (MMP-1), stromelysin-1 (MMP-3) and gelatinase A (MMP-2) is responsible for the lysis of dermal collagen and elastin fibers during chronological skin aging. Tissue inhibitor of metalloproteinase-1 (TIMP-1) is one representative of the natural MMP inhibitor family, encompassing four members. Its expression is decreased with fibroblast senescence, both ex vivo and in vivo, thus contributing to increased catabolic activity within dermis. TIMP-1 displays multiple biological functions. It inhibits most MMPs, except membrane-type MMP subfamily, with Ki in the subnanomolar range, but also interacts with the hemopexin-like (PEX) domain of pro MMP-9. Besides, it exhibits keratinocyte and fibroblast growth factor-like activity and has been described as a cell survival factor.

Aged↗
PubMed1999

Further characterization of ATP-initiated calcification by matrix vesicles isolated from rachitic rat cartilage. Membrane perturbation by detergents and deposition of calcium pyrophosphate by rachitic matrix vesicles.

Although membrane associated enzymes such as ATPase, alkaline phosphatase, and NTP pyrophosphohydrolase in matrix vesicles (MVs) may underlie the mechanisms of ATP-promoted calcification, prior to the current investigation, the role of the MV membrane in calcification had not been addressed. In this study, various perturbations were introduced to the MV membrane in in vitro calcification systems to determine ideal conditions for ATP-initiated calcification by MVs isolated from rachitic rat epiphyseal cartilage. Membrane integrity appears to be required, since the rupture of the vesicular membrane by vigorously mixing with 10% butanol abolished calcification. In contrast, a mild treatment of MVs with low concentrations (e.g., 0.01%, which is much below the critical concentration for micelle formation) of either neutral Triton X-100 or anionic deoxycholate stimulated calcification by >2-fold, without inducing obvious changes in vesicular appearance. Fourier transform infrared spectroscopic studies were done to identify the mineral phase formed in these experiments. For the first time, rachitic MVs were shown to induce the formation of a calcium pyrophosphate dihydrate-like phase after their exposure to calcifying medium with 1 mM ATP. The integration of spectral areas indicated that calcification was enhanced by Triton X-100. The detergent effect was reversible and appeared to be not mediated through activation of ATPase, alkaline phosphatase, or ATP pyrophosphohydrolase. In contrast to neutral Triton X-100 and anionic deoxycholate, cationic cetyltrimethylammonium bromide inhibited both ATPase activity (I50=10 microM) and ATP-initiated calcification. These observations suggest that membrane perturbations can affect calcification and that the presence of NTP-pyrophosphohydrolase in MVs may play a role in the deposition of CaPPi in rachitic cartilage.

Adenosine Triphosphate↗
PubMed2001

Three-dimensional imaging of extracellular matrix and extracellular matrix-cell interactions.

In summary, noninvasive and nondestructive imaging modalities such as reflection and autofluorescence can readily be used in conjunction with the 3-D optical sectioning capabilities of confocal and multiphoton microscopy to investigate biological processes within living systems. The elimination of specimen fixation and extensive processing reduces the possibility of structural artifacts and facilitates repeat observations within a single sample. Therefore, information representing up to four dimensions (x, y, z, and time) can be readily collected and reconstructed for purposes of visualization and/or quantitative analysis. An advantage of using the techniques described in this chapter is the possibility of performing quantitative measurement of cell size, surface area, volume, depth (in matrix), orientation, receptor density, as well as fluorescence-based indicators of phenotype and function. At present, we are effectively utilizing these techniques to study collagen fibrillogenesis and ECM assembly, structural aspects of ECM-based biomaterials, as well as cell interactions within 3-D matrices (e.g., migration). New insights provided by these techniques regarding ECM and ECM-cell signaling will further the understanding of tissue structure and function and contribute to the development of new and improved strategies for tissue repair, replacement, and maintenance.

Animals↗
PubMed1993

TRAMP (tyrosine rich acidic matrix protein), a protein that co-purifies with lysyl oxidase from porcine skin. Identification of TRAMP as the dermatan sulphate proteoglycan-associated 22K extracellular matrix protein.

A protein (M(r)24 K) that co-purifies with porcine skin lysyl oxidase (M(r)34 K) has been isolated and characterised. Five variants of the 24 K protein were identified by Mono Q ion-exchange FPLC, as were four variants of lysyl oxidase. Amino acid analysis and partial sequencing revealed near identity of a 36-residue CNBr peptide from porcine skin lysyl oxidase to corresponding regions of the putative lysyl oxidase precursor derived from rat and human cDNA. The 24 K protein was found to be unrelated to lysyl oxidase, but comparison with a protein sequence database showed it to be the same as a recently described protein from bovine skin that is associated with dermatan sulphate proteoglycans. The 24 K protein is relatively rich in tyrosine, and isoelectric focussing shows it to be acidic, with pI's in the range 4.1 to 4.4. In view of these properties, we propose the name TRAMP (Tyrosine Rich Acidic Matrix Protein) to identify this protein. Though TRAMP appears not to be glycosylated, several experiments indicate the presence of sulphotyrosine residues. When assayed using an elastin substrate, the activity of lysyl oxidase is unaffected by TRAMP.

Alcian Blue↗
PubMed1999

Do charge-remote fragmentations occur under matrix-assisted laser desorption ionization post-source decompositions and matrix-assisted laser desorption ionization collisionally activated decompositions?

The precursor ions of tetraphenylporphyrins that are substituted with fatty acids can be introduced into the gas phase by matrix-assisted laser desorption ionization (MALDI) and undergo post-source and collisionally activated decompositions (CAD) in a time-of-flight mass spectrometer. The goal of the research is to obtain a better understanding of post-source decompositions (PSD); specifically, we asked the question of whether ions undergoing PSD have sufficient energy to give charge-remote fragmentations along an alkyl chain. We chose the porphyrin macrocycle because we expected it to act as an inert "support," allowing the molecule to be desorbed by MALDI and to be amenable to charge-remote fragmentation. MALDI-PSD and MALDI-CAD spectra are similar to high-energy CAD spectra and considerably more informative than low-energy CAD spectra, showing that charge-remote fragmentations of the fatty acid moieties do occur upon MALDI-PSD and MALDI-CAD.

Fatty Acids↗