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At least 235 records · Page 13Linked to original sources

PubMed1991

Extracellular matrix contraction by cultured mesangial cells: an assay system for mesangial cell-matrix interaction.

To investigate the interaction between glomerular mesangial cells (MCs) and extracellular matrix (ECM), we have developed a quantitative assay using a floating culture of MC-populated collagen gel matrix (MCGM). Since MCs can contract such a matrix consisting of type I collagen, MCGM exhibited marked contraction. The apparent cause was tensional interaction between MCs and collagen fibers, because: (1) MCs in the gel attached tightly to surrounding collagen fibers; (2) collagen fibrils surrounding MCs were ordered in a radial array; (3) collagen fibers aggregated around MCs in the contracted gel, but not in an uncontracted gel; (4) cytochalasin B, an actin polymerization blocker, inhibited gel contraction in a dose-dependent manner. We found that this interaction was modulated by some factors. Serum in the medium stimulated the contraction of MCGM. The degree of MCGM contraction was proportional to the number of MCs embedded above 2.3 x 10(4) cells/ml of gel. In MCGM containing a basement membrane-type gel matrix (BGM), gel contraction was increasingly inhibited as the content of BGM rose. Our method is useful for elucidating physiological and pathological interactions between MCs and ECM.

Angiotensin II↗

PubMed1994

Tyrosine-rich acidic matrix protein (TRAMP) is a tyrosine-sulphated and widely distributed protein of the extracellular matrix.

Tyrosine-rich acidic matrix protein (TRAMP; 22 kDa extracellular matrix protein; dermatopontin) is a protein that co-purifies with lysyl oxidase and with dermatan sulphate proteoglycans, with possible functions in cell-matrix interactions and matrix assembly. Using a rabbit polyclonal antiserum raised against porcine TRAMP, which cross-reacts with both the human and murine forms of the protein, we show by immunoblotting that TRAMP has a widespread tissue distribution, including skin, skeletal muscle, heart, lung, kidney, cartilage and bone. In cultures of human skin fibroblasts, TRAMP incorporates both [35S]sulphate and [3H]tyrosine and is secreted into the medium, as shown by immunoprecipitation. Amino acid analysis of immunoprecipitated TRAMP demonstrates that many of the tyrosine residues in TRAMP are sulphated.

Animals↗

PubMed1995

Biomaterials in orthopaedic surgery: effects of different hydroxyapatites and demineralized bone matrix on proliferation rate and bone matrix synthesis by human osteoblasts.

The effects of different biomaterials, used in orthopaedic surgery for bone substitution and/or prosthesis coating to improve fixation and durability of prosthetic implants, have been studied in vitro on cell growth and bone matrix synthesis by human osteoblasts. The materials were a bovine collagen matrix (Osteovit, B. Braun Melsungen AG, Melsungen, Germany) and two hydroxyapatite (Ceros 80, Robert Mathys Co, Instrumentenfabrik Bettlach, Germany and Ostilit, Howmedica International, Staines House, UK). Cell proliferation and bone matrix synthesis were assessed by incorporation of [3H]thymidine and [3H]proline, respectively. Cell viability in the presence of the materials was also morphologically controlled using phase-contrast microscopy. Exposure to Osteovit caused increased proliferation of human osteoblasts, whereas both Ostilit and Ceros 80 induced a decreased cell growth. Osteoblast bone matrix synthesis was increased by all the materials tested.

Biocompatible Materials↗

PubMed1994

DNA repair is less efficient in the nuclear matrix than in non-matrix nuclear fractions in the liver of rats treated with 2-aminofluorene.

The amount of DNA adducts and radioactive thymidine incorporation into DNA fractions attached and not attached to the nuclear matrix in the liver of rats treated with the carcinogen 2-aminofluorene (2-AF) were compared. The rate of [3H]thymidine incorporation was directly proportional to the amount of adducts in total hepatic DNA. Within the first 10 h after the carcinogen treatment, the level of adducts in the nuclear matrix DNA was higher than in the whole nuclei. The rate of [3H]thymidine incorporation into the nuclear matrix DNA was 5-30% lower than into DNA in whole nuclei at any time after 2-AF injection. We suggest that in rat liver cells, the 2-AF-induced DNA repair does not occur in close contact with the nuclear matrix.

Animals↗

PubMed2006

Analysis of native milk oligosaccharides directly from thin-layer chromatography plates by matrix-assisted laser desorption/ionization orthogonal-time-of-flight mass spectrometry with a glycerol matrix.

We have recently presented a new method for direct coupling of high-performance thin-layer chromatography (HPTLC) with matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS), illustrated by the analysis of a complex ganglioside mixture. In the current communication, an adaptation of this procedure to mixtures of native oligosaccharides from human and from elephant milk is described. The key features in this method are (1) glycerol as a liquid matrix, to provide a homogeneous wetting of the silica gel and a simple and fast MALDI preparation protocol, (2) an infrared (IR) laser for volume material ablation and particular soft desorption/ionization conditions, and (3) an orthogonal time-of-flight mass spectrometer for a high mass accuracy, independent of any irregularity of the silica gel surface. Chromatographic "mobility profiles" were determined by scanning the laser beam across the analyte bands. The current limit of detection for the MS analysis was determined to approximately 10 pmol of individual oligosaccharides spotted for chromatography. A liquid composite matrix, containing glycerol and the ultraviolet (UV-)MALDI matrix alpha-cyano-4-hydroxycinnamic acid, allows a direct HPTLC-MALDI-MS analysis with a 337 nm-UV laser as well. Compared to the IR-MALDI mode, the analytical sensitivity in UV-MALDI was found to be lower by one order of magnitude, whereas unspecific analyte ion fragmentation as well as adduct formation was found to be more extensive.

Animals↗

PubMed2006

3-Hydroxycoumarin as a new matrix for matrix-assisted laser desorption/ionization time-of-flight mass spectrometry of DNA.

3-Hydroxycoumarin (3-HC) was designed, synthesized, and tested as a matrix for matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) analyses of a variety of synthetic oligodeoxynucleotides ranging long from three to 70 bases. Using the matrix solution of 3-HC dissolved in a mixed solvent of acetone and diammonium hydrogen citrate, DNA segments over the mass range 800 Da to 6900 Da were isotopically resolved with high signal-to-noise (S/N) ratio. The individual isotopic molecular ion peaks of a group of 23-mer mixed-base oligomers differing by one or two bases with mass differences of 9 or 7 Da were recorded. Larger oligodeoxynucleotide segments of 34-mer, 50-mer, and 70-mer have also been analyzed effectively. Less than 250 attomol of a 10-mer DNA segment was clearly detected without any fragmentation. The new matrix can be used for the analysis of DNA segments in both positive- and negative-ion modes, and the quality of all negative-ion mode spectra are as good as that obtained in positive-ion mode shown in this paper. Compared with conventional matrices of 3-hydroxypicolinic acid (3-HPA) and 6-aza-2-thiothymine (ATT), 3-HC had noticeable improvement in resolution, S/N ratio, spot-to-spot-, and sample-to-sample reproducibility for analyzed DNA segments.

Base Sequence↗

PubMed2005

The effect of IL-1beta on the expression of matrix metalloproteinases and tissue inhibitors of matrix metalloproteinases in human chondrocytes.

Interleukin-1 (IL-1) plays key roles in altering cartilage matrix turnover. This turnover is regulated by matrix metalloproteinases (MMPs) and tissue inhibitors of matrix metalloproteinases (TIMPs). In the present study, we examined the effect of IL-1beta on cell proliferation, alkaline phosphatase (ALPase) activity, and the expression of MMPs, and TIMPs in chondrocytes derived from normal human femoral cartilage. The cells were cultured in Dulbecco's modified Eagle's medium containing 15% fetal bovine serum and 0, 1, 10, or 100 U/ml of IL-1beta for up to 28 days. The level of expression of MMPs and TIMPs was estimated by determining mRNA levels using real-time PCR and by determining protein levels using an enzyme-linked immunosorbent assay. Cell proliferation decreased in the presence of IL-1beta after day 21 of culture. ALPase activity decreased significantly in the presence of IL-1beta after day 10 of culture. The expression of MMP-1, -2, and -3 increased markedly in the presence of IL-1beta after day 21 of culture. MMP-13 expression increased markedly in the presence of IL-1beta on day 1 of culture, but decreased markedly after day 7. The expression of TIMP-1 increased significantly after day 14 of culture. The expression of TIMP-2 decreased significantly on day 1, but increased significantly from day 3 to day 14 of culture. These results suggest that IL-1beta may stimulate cartilage matrix turnover by increasing mainly MMP-13 production by the cells.

Cartilage↗

PubMed1995

Nuclear matrix acceptor binding sites for steroid hormone receptors: a candidate nuclear matrix acceptor protein.

Steroid/nuclear-hormone receptors are ligand-activated transcription factors that have been localized to the nuclear matrix. The classic model of hormone action suggests that, following activation, these receptors bind to specific "steroid response elements" on the DNA, then interact with other factors in the transcription initiation complex. However, evidence demonstrates the existence of specific chromatin proteins that act as accessory factors by facilitating the binding of the steroid receptors to the DNA. One such protein, the "receptor binding factor (RBF)-1", has been purified and shown to confer specific, high-affinity binding of the progesterone receptor to the DNA. Interestingly, the RBF-1 is localized to the nuclear matrix. Further, the RBF-1 binds specifically to a sequence of the c-myc proto-oncogene that has the appearance of a nuclear matrix attached region (MAR). These results, and other findings reviewed here, suggest that the nuclear matrix is involved intimately in steroid hormone-regulated gene expression.

Animals↗

PubMed2000

The nuclear matrix of Euglena gracilis (euglenophyta): a stage of nuclear matrix evolution?

Euglena gracilis cell was extracted sequentially with CSK-Triton buffer, RSB-Magik solution and DNase-As solution. DGD embedment-free electron microscopy showed that in the extracted nucleus there was a residual non-chromatin fibrous network. That it could not be removed by hot trichloroacetic acid further supported the idea that it was a non-histone, non-chromatin fibrous protein network, and should be the internal network of the nuclear matrix. After the sequential extraction, the nuclear membrane was removed, leaving behind a layer of lamina; the chromatin was digested and eluted from the dense chromosomes and residual chromosomal structures that should be chromosomal scaffold were revealed. Western blot analysis with antiserum against rat lamins showed that nuclear lamina of the cell possessed two positive polypeptides, a major one and a minor one, which had molecular masses similar to lamin B and lamin A, respectively. Comparing these data with those of the most primitive eukaryote Archezoa and of higher eukaryotes, it was suggested that the lower unicellular eukaryote E. gracilis already had the nuclear matrix structure, and its nuclear matrix (especially the lamina) might represent a stage of evolutionary history of the nuclear matrix.

Animals↗

PubMed2002

Atomic resolution structure of Moloney murine leukemia virus matrix protein and its relationship to other retroviral matrix proteins.

Matrix proteins associated with the viral membrane are important in the formation of the viral particle and in virus maturation. The 1.0 A crystal structure of the ecotropic Gammaretrovirus Moloney murine leukemia virus (M-MuLV) matrix protein reveals the conserved topology of other retroviral matrix proteins, despite undetectable sequence similarity. The N terminus (normally myristylated) is exposed and adjacent to a basic surface patch, features likely to contribute to membrane binding. The four proteins in the asymmetric unit make varied contacts. The M-MuLV matrix structure is intermediate, between those of the lentiviruses and other retroviruses. The protein fold appears to be maintained, in part, by the conservation of side chain packing, which may provide a useful tool for searching for weak distant similarities in proteins.

Amino Acid Sequence↗

PubMed2000

Time-of-flight secondary ion mass spectrometry of matrix-diluted oligo- and polypeptides bombarded with slow and fast projectiles: positive and negative matrix and analyte ion yields, background signals, and sample aging.

Human angiotensin II, chain B of bovine insulin, and porcine insulin were determined by time-of-flight secondary ion mass spectrometry under impact of approximately 25 keV Xe+ and SF5+ ion beams and approximately 100 MeV 252Cf fission fragments. Matrix-embedded samples, dissolved in a large surplus of alpha-cyano-4-hydroxycinnamic acid, were prepared by nebulizer spray deposition, neat samples by the droplet technique. It is shown that the status of the sample can be assessed by evaluating the matrix-specific features of the mass spectra. The beneficial effect of matrix isolation was small for angiotensin but large for the insulin samples, which did not show parent peaks from neat material. Negative ion yields under SF5+ impact were up to a factor of 50 higher than with Xe+. For positive secondary ions, the enhancement was much smaller. The mass spectra produced by slow ion beams or fast fission fragments were qualitatively similar. Quantitative differences include the following: with fast projectiles the yields were about 10-30 times higher than with slow ions, but similar for negative ion emission under SF5+ bombardment; the analyte-to-matrix yield ratios were higher with slow ions and up to 250 times higher than the molar analyte concentration; for analyte ions the peak-to-background ratios were higher using slow projectiles; the fraction of carbon-rich collisionally formed molecular ions was much higher with fast projectiles. Sample aging in vacuum for up to five weeks strongly reduced the yield of protonated analyte molecules ejected by slow ion impact, but not of deprotonated species. Hence protonation seems to correlate with sample "wetness" or the presence of volatile proton-donating additives.

Angiotensins↗

PubMed2003

Effect of local matrix crystal variations in matrix-assisted ionization techniques for mass spectrometry.

Intense intact molecular ion signals have been obtained from phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, and phosphatidyiinositol using matrix-enhanced secondary ion mass spectrometry (ME-SIMS). It was found that the high-mass (m/z >500) regions of the ME-SIMS spectra closely resembled those obtained using matrix-assisted laser desorption/ionization (MALDI). Using high spatial resolution SIMS, a detailed investigation of dried-droplet samples was performed. Based on the detected Na+ and 2,5-DHB matrix signal intensities, different crystal types were distinguished, in addition to different sizes of crystals. Spatially mapping the pseudomolecular and fragment ions of the phospholipids revealed that the nature of the pseudomolecular ions formed, as well as the ratio of intact molecular to fragment ion, was dependent on the type and surface composition of the crystal. The observed chemical bias effects due to crystal heterogeneity and the resulting variation in desorption/ionization efficiency will complicate the interpretation of data obtained from matrix-assisted mass spectrometric (imaging) techniques and is an important factor in the "hot spot" phenomenon frequently encountered in MALDI experiments. In this respect, imaging SIMS was found to be a versatile tool to investigate the effects of the local physicochemical conditions on the detected molecular species.

Crystallization↗

PubMedDate not supplied

Structure-function relationship of avian eggshell matrix proteins: a comparative study of two major eggshell matrix proteins, ansocalcin and OC-17.

The role of individual matrix proteins in avian eggshell calcification is poorly understood despite numerous attempts to characterize and localize their presence in the eggshell matrix. Ansocalcin, the major matrix protein from goose eggshell, was found to induce the formation of calcite crystal aggregates under in vitro. Owing to its high similarity with the chicken eggshell matrix protein ovocleidin 17 (OC-17), a comparative investigation has been carried out to understand the structure-function relationship. RP-HPLC shows that ansocalcin is the major component in extracts of goose eggshells before and after bleach treatment. However, OC-17 was observed in minute quantities in the extract of bleach-treated chicken eggshells. In vitro crystal growth experiments showed that OC-17 and ansocalcin interact differently with the calcite crystals formed. Circular dichroism, intrinsic tryptophan fluorescence, and dynamic light scattering studies showed that, under the conditions used in our experiments, OC-17 does not aggregate in solution or induce the nucleation of calcite aggregates in the concentration range used. These observations indicate that OC-17 and ansocalcin play different roles in the eggshell calcification. To our knowledge, this is the first report on the comparison of properties of homologous eggshell proteins that belong to the same phylogeny.

Animals↗

PubMed2003

Microfluidic patterning of cells in extracellular matrix biopolymers: effects of channel size, cell type, and matrix composition on pattern integrity.

The organization of cells within an extracellular matrix is critical to promote appropriate cellular interactions and tissue function in vivo. The ability to design and create biologically relevant cellular arrangements via microfluidic patterning on surfaces provides new capabilities for tissue engineering and biomimetics. The purpose of this article is to describe techniques using microfluidic patterning of three-dimensional biopolymer matrices to improve cellular pattern integrity and to provide microscale control over cellular microenvironments. Results demonstrated that the incorporation of extracellular matrix biopolymers in cell microfluidic patterning results in a more stable pattern of adherent human endothelial cells than patterning without matrix components after several days in vitro. This may be important for carrying out long-term biological experiments and tissue engineering in vitro. Moreover, chemical components in the patterned biopolymer matrices, such as collagen, chitosan, and fibronectin, influenced the ability of the matrices to control cell migration and pattern stability over time. Thus, microfluidic patterning of cells in extracellular matrix biopolymers was shown to be useful in patterning multiple cell types in well-defined three-dimensional geometries.

Biopolymers↗

PubMed2006

A matrix of 3,4-diaminobenzophenone for the analysis of oligonucleotides by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

A new matrix of 3,4-diaminobenzophenone (DABP) was demonstrated to be advantageous in the analysis of oligonucleotides by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. With DABP as a matrix, intact oligonucleotide ions can be readily produced with lower laser powers, resulting in better detection limits, less fragmentation and fewer alkali metal ion adducts compared with the results obtained with conventional matrices. Importantly, minimal fragmentation and fewer alkali metal ion adducts were seen even at low concentrations of oligonucleotides. It was also found that samples prepared with DABP are highly homogenous and therefore reducing the need for finding 'sweet' spots in MALDI. In addition, excellent shot-to-shot reproducibility, resolution and signal-to-noise ratio were seen with DABP as the matrix.

Benzophenones↗

PubMed1999

Structural similarities between influenza virus matrix protein M1 and human immunodeficiency virus matrix and capsid proteins: an evolutionary link between negative-stranded RNA viruses and retroviruses.

The evolutionary relationship of retroviruses to the negative-stranded RNA virus superfamily was examined by comparing protein structures. Since protein structures are more conserved over time than primary protein sequences, three-dimensional structural comparisons permit the identification of evolutionary relationships that were previously undetected. Human immunodeficiency virus (HIV) and influenza virus were used as representatives of the virus groups, and proteins with similar functions were compared. Since M1 of influenza virus has membrane- and RNA nucleocapsid-binding activities that are functionally analogous to those of the HIV matrix and capsid proteins, the structural similarities between these proteins were determined. Sequence alignments were based on superimposition of the three-dimensional structures. Helices 2, 2', 3 and 4 of the HIV matrix protein aligned and superimposed with the four-helix bundle of the membrane-binding N domain of M1 with a root mean square (RMS) of 3.48 A. Helices A, B and C of the HIV N-terminal capsid protein aligned and superimposed with three helices of the four-helix bundle of the RNA-binding N domain of M1 with an RMS of 2.63 A. The HIV Gag protein and influenza virus matrix protein may have evolved from a common ancestor protein. The similarities between influenza virus M1 and HIV matrix and capsid proteins may indicate an evolutionary link between retroviruses and negative-sense RNA viruses.

Amino Acid Sequence↗

PubMed2004

Sequence and structure relatedness of matrix protein of human respiratory syncytial virus with matrix proteins of other negative-sense RNA viruses.

Matrix proteins of viruses within the order Mononegavirales have similar functions and play important roles in virus assembly. Protein sequence alignment, phylogenetic tree derivation, hydropathy profiles and secondary structure prediction were performed on selected matrix protein sequences, using human respiratory syncytial virus matrix protein as the reference. No general conservation of primary, secondary or tertiary structure was found, except for a broad similarity in the hydropathy pattern correlating with the fact that all the proteins studied are membrane-associated. Interestingly, the matrix proteins of Ebola virus and human respiratory syncytial virus shared secondary structure homology.

Amino Acid Sequence↗

PubMed2004

Matrix metalloproteinase/tissue inhibitors of matrix metalloproteinase phenotype identifies poor prognosis colorectal cancers.

PURPOSE: The matrix metalloproteinases (MMPs) are a family of proteolytic enzymes involved in tumor invasion; several individual members of which have been implicated in tumor prognosis. These enzymes and their physiologic inhibitors, the tissue inhibitors of matrix metalloproteinases (TIMPs), act in a coordinated manner to form an integrated system. Therefore, to understand their role in tumor invasion, it is necessary to evaluate them collectively. EXPERIMENTAL DESIGN: In this study all of the major members of the matrix metalloproteinase (MMP-1, MMP-2, MMP-3, MMP-7, MMP-9, MMP-13, MT1-MMP and MT2-MMP)/tissue inhibitor of matrix metalloproteinase (TIMP-1, TIMP-2, and TIMP-3) system have been investigated by immunohistochemistry in a series (n = 90) of stage III (Dukes' C) colorectal cancers. An immunohistochemical score based on the intensity of immunoreactivity and proportion of immunoreactive cells was established for each MMP and TIMP. RESULTS: The MMP/TIMP profile defined by hierarchical cluster analysis of the immunohistochemical score identifies a distinct group of colorectal cancers with poor prognosis (log-rank test, 12.22, P = 0.0005). The median survival time of patients in this survival group was 18 months compared with a median survival of 49 months in the "good" survival group. Multivariate analysis showed that this profile was independently the most significant prognostic factor (P = 0.001). CONCLUSIONS: This study has identified that the MMP/TIMP profile is an independent indicator of poor prognosis in colorectal cancer.

Adenocarcinoma↗