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PubMed1993

The sign of Leser-Trélat: a cutaneous sign of internal malignancy: weakened subepithelial matrix from the effect of neoplasms on the extracellular matrix of the host.

The sudden onset of many seborrheic keratoses (SK) associated with an internal malignancy (most commonly adenocarcinoma) is called the sign of Leser-Trélat. It is associated with acanthosis nigricans (AN) in 20% of the cases. There are marked changes in the extracellular matrix (ECM) around tumors. Various fractions and depolymerized glycosaminoglycans enter circulation. They can incorporate in the general extracellular matrix. Mechanical factors present in AN produce extrusions of this poor quality ECM in the form of papillae and folds. The poor quality of subepithelial extracellular matrix produces the marked epithelial changes of acanthosis nigricans which shows hyperkeratosis, papillomatosis, slight irregular acanthosis, and keratin material formation. The neoplasm can produce the same qualitative changes in the subepithelial ECM on otherwise normal appearing skin. When the altered same epithelial changes occur on this biologically altered skin the result is many SK (the sign of Leser-Trélat).

Acanthosis Nigricans↗

PubMed2006

The effect of the amelogenin fraction of enamel matrix proteins on fibroblast-mediated collagen matrix reorganization.

Enamel matrix proteins (EMP), extracted from developing porcine teeth, promote not only periodontal regeneration but also cutaneous wound healing presumably via the amelogenin fraction. Because it is unclear whether the effect of EMP can be ascribed to amelogenins, we compared EMP with recombinant amelogenin in the relaxed dermal equivalent (DE) in vitro model for early wound contraction. EMP and recombinant porcine amelogenin (rP172) at 1 mg/ml were incorporated into DEs composed of human dermal fibroblasts and a type I collagen matrix. The area reduction, as a measure of contraction, as well as fibroblast numbers and TGF-beta1 levels, were quantified over 7 days in culture in the presence of 10% foetal bovine serum. Both EMP and recombinant amelogenin increased contraction (p < 0.005) and fibroblast numbers (p < 0.005) compared with controls (acetic acid vehicle and 1mg/ml porcine serum albumin) and the positive control TGF-beta1 added at 10 ng/ml. Increased contraction with EMP and recombinant amelogenin was most pronounced after the first day of incubation and was associated with elevated (p < 0.005) TGF-beta1 levels in conditioned medium. In conclusion, the amelogenin component of EMP augmented fibroblast-driven collagen matrix remodelling, at least partially, by increasing the endogenous production of TGF-beta1. These effects of EMP/amelogenin may be beneficial for cutaneous wound healing.

Amelogenesis↗

PubMed2006

Extracellular matrix remodeling--methods to quantify cell-matrix interactions.

Tissue turnover during wound healing, regeneration or integration of biomedical materials depends on the rate and extent of materials trafficking into and out of cells involved in extracellular matrix (ECM) remodeling. To exploit these processes, we report the first model for matrix trafficking in which these issues are quantitatively assessed for cells grown on both native collagen (normal tissue) and denatured collagen (wound state) substrates. Human fibroblasts more rapidly remodeled denatured versus normal collagen type I to form new ECM. Fluxes to and from the cells from the collagen substrates and the formation of new ECM were quantified using radioactively labeled substrates. The model can be employed for the systematic and quantitative study of the impact of a broad range of physiological factors and disease states on tissue remodeling, integrating extracellular matrix structures and cell biology.

Cell Communication↗

PubMed2005

Matrix-degrading enzymes tissue plasminogen activator and matrix metalloprotease-3 in the hypothalamo-neurohypophysial system.

The hypothalamo-neurohypophysial system (HNS), synthesizing arginine vasopressin (AVP) and oxytocin (OXT), is well known to show structural plasticity during chronic physiological stimulation such as salt loading and lactation. In the present study, we undertook in the HNS to study localization and activity-dependent changes in the expression of matrix-degrading enzymes such as tissue plasminogen activator (tPA) and matrix metalloprotease-3 (MMP-3). Double labeling confocal microscopy demonstrated that the immunoreactivity of tPA was localized at AVP-positive dendrites in the supraoptic nucleus (SON) and AVP-positive terminals in the neurohypophysis (NH). The immunoreactivity of tPA was also seen at astrocytic processes in the HNS. Likewise, the immunoreactivity of MMP-3 was observed at AVP-positive dendrites and terminals. High magnification observation further revealed punctate distribution of tPA and MMP-3 immunoreactivity at dendrites and terminals, suggesting that they are localized at neurosecretory granules. Salt loading, known as the chronic stimulation to cause the structural plasticity, increased protein and mRNA levels of tPA in the SON but reduced protein levels of it in the NH. The chronic stimulation also increased protein levels of urokinase plasminogen activator in the SON, but the stimulation did not change protein levels of MMP-3 in the SON and NH. Depolarizing agent KCl released tPA from isolated neurosecretosomes, and this depolarization-dependent release was abolished by verapamil, a Ca(2+) channel blocker. These results demonstrate that tPA and MMP-3 are localized mainly at dendrites and terminals of AVP-expressing magnocellular neurons and tPA is released in an activity-dependent manner, suggesting that matrix-degrading proteases are candidate molecules to be concerned with the structural plasticity in the HNS.

Animals↗

PubMed2005

Effectiveness of an extracellular matrix graft (OASIS Wound Matrix) in the treatment of chronic leg ulcers: a randomized clinical trial.

BACKGROUND: Venous leg ulcers are a major cause of morbidity, economic loss, and decreased quality of life in affected patients. Recently, biomaterials derived from natural tissue sources have been used to stimulate wound closure. One such biomaterial obtained from porcine small-intestine submucosa (SIS) has shown promise as an effective treatment to manage full-thickness wounds. Our objective was to compare the effectiveness of SIS wound matrix with compression vs compression alone in healing chronic leg ulcers within 12 weeks. METHODS: This was a prospective, randomized, controlled multicenter trial. Patients were 120 patients with at least 1 chronic leg ulcer. Patients were randomly assigned to receive either weekly topical treatment of SIS plus compression therapy (n = 62) or compression therapy alone (n = 58). Ulcer size was determined at enrollment and weekly throughout the treatment. Healing was assessed weekly for up to 12 weeks. Recurrence after 6 months was recorded. The primary outcome measure was the proportion of ulcers healed in each group at 12 weeks. RESULTS: After 12 weeks of treatment, 55% of the wounds in the SIS group were healed, as compared with 34% in the standard-care group (P = .0196). None of the healed patients treated with SIS wound matrix and seen for the 6-month follow-up experienced ulcer recurrence. CONCLUSIONS: The SIS wound matrix, as an adjunct therapy, significantly improves healing of chronic leg ulcers over compression therapy alone.

Adult↗

PubMed2005

Proteolysis of cell-surface tissue transglutaminase by matrix metalloproteinase-2 contributes to the adhesive defect and matrix abnormalities in thrombospondin-2-null fibroblasts and mice.

Thrombospondin (TSP)-2-null dermal fibroblasts display an attachment defect that results from increased matrix metalloproteinase (MMP)-2 levels in their conditioned media. To investigate the molecular mechanisms responsible for this defect, we analyzed the activity of tissue transglutaminase (tTG) in TSP-2-null dermal fibroblasts and in tissues of TSP-2-null mice. tTG functions as a co-receptor for beta1 and beta3 integrins and stabilizes extracellular matrix proteins by introduction of isopeptide cross-links. Cell-surface tTG activity was reduced in TSP-2-null cells (0.50 +/- 0.05 arbitrary units versus 0.84 +/- 0.07 for wild type; P < or = 0.05), and addition of MMP-2 to the culture medium of wild-type cells caused a 35% reduction in cell-surface tTG activity. tTG was susceptible to proteolysis by MMP-2 in vitro, and addition of the MMP inhibitor TIMP-2 to TSP-2-null cells restored tTG activity (0.3 +/- 0.08 for untreated cells; 0.71 +/- 0.09 with TIMP-2). TSP-2-null mice had reduced tTG activity in skin, as measured by incorporation of fluorescein isothiocyanate-labeled cadaverine, and a threefold increase in acetic acid-extracted dermal collagen. Furthermore, isopeptide cross-links were reduced in both uninjured skin and in excisional wounds of TSP-2-null mice, as determined by morphometric immunohistochemical analysis, indicating that isopeptide cross-links are important for the stabilization of the collagenous matrix in dermis. These findings provide a mechanism for the reduced adhesion of TSP-2-null fibroblasts and an explanation for the increased collagen solubility and fragility of TSP-2-null skin.

Animals↗

PubMed2003

Basement membrane-like matrix inhibits proliferation and collagen synthesis by activated rat hepatic stellate cells: evidence for matrix-dependent deactivation of stellate cells.

During liver fibrosis hepatic stellate cells become activated, transforming into proliferative myofibroblastic cells expressing type I collagen and alpha-smooth muscle actin. They become the major producers of the fibrotic neomatrix in injured liver. This study examines if activated stellate cells are a committed phenotype, or whether they can become deactivated by extracellular matrix. Stellate cells isolated from normal rat liver proliferated and expressed mRNA for activation markers, alpha-smooth muscle actin, type I procollagen and tissue inhibitor of metalloproteinases-1 following 5-7 day culture on plastic, but culture on Matrigel suppressed proliferation and mRNA expression. Activated stellate cells were recovered from plastic by trypsinisation and replated onto plastic, type I collagen films or Matrigel. Cells replated on plastic and type I collagen films proliferated and remained morphologically myofibroblastic, expressing alpha-smooth muscle actin and type I procollagen. However, activated cells replated on Matrigel showed <30% of the proliferative rate of these cells, and this was associated with reduced cellular expression of proliferating cell nuclear antigen and phosphorylation of mitogen-activated protein kinase in response to serum. Activated HSC replated on Matrigel for 3-7 days progressively reduced their expression of mRNA for type I procollagen and alpha-smooth muscle actin and both became undetectable after 7 days. We conclude that basement membrane-like matrix induces deactivation of stellate cells. Deactivation represents an important potential mechanism mediating recovery from liver fibrosis in vivo where type I collagen is removed from the liver and stellate cells might re-acquire contact with their normal basement membrane-like pericellular matrix.

Actins↗

PubMed2001

5-Methoxysalicylic acid and spermine: a new matrix for the matrix-assisted laser desorption/ionization mass spectrometry analysis of oligonucleotides.

5-Methoxysalicylic acid (MSA) is demonstrated to be a useful matrix for matrix-assisted laser desorption/ionization time-of-flight (TOF) mass spectrometry of oligonucleotides, when desorption/ionization without fragmentation is desired. When MSA is combined with the additive spermine, the need for desalting is reduced. The MSA/spermine matrix yields linear TOF mass spectra with improved resolution, less fragmentation, and less intense alkali ion adduct peaks than those spectra obtained using 3-hydroxypicolinic acid and 6-aza-2-thiothymine with spermine or diammonium hydrogen citrate as additives. Instrumental conditions are discussed to improve the spectral resolution, specifically the use of longer delay times in the delayed-extraction ion source.

Citric Acid↗

PubMed1995

Matrix-assisted laser desorption ionization of neutral clusters composed of matrix and analyte molecules.

A new version of the matrix-assisted laser desorption ionization experiment is described. Composed clusters created by laser desorption of a mixture of analyte and matrix material were injected into a supersonic jet and then analyzed by multiphoton ionization time-of-flight mass spectrometry. Selective two-photon ionization of matrix molecules of a cluster component caused their dissociation, followed by intercluster proton or cation transfer to an analyte that is transparent for the wavelength of ionizing radiation. The intercluster charge transfer reactions are the only pathway for analyte ion formation under these conditions, as can be concluded from analysis of the mass spectra of a variety of substances.

Amino Acid Sequence↗

PubMed2004

Small-molecule MALDI using the matrix suppression effect to reduce or eliminate matrix background interferences.

The matrix suppression effect (MSE) can lead to high-quality MALDI mass spectra: strong analyte signals and weak or negligible matrix background peaks. Experiment and theory suggest that MSE should be widespread and, therefore, generally applicable to measurement of low molecular weight (LMW) substances. These are otherwise impractical with MALDI due to interference from matrix. Appropriate conditions for MSE were investigated and tested on a variety of LMW substances. Straightforward and semiautomated interpretation was possible for 87.7% of these. Another 3.5% gave poor MSE due to sodium cationization rather than protonation of the analyte, but interpretation was possible. MALDI imaging shows that MSE varies significantly across a typical sample. Selective data accumulation could further increase the utility of the method. Samples containing more than one analyte were also studied. Analyte-analyte suppression was not found to be excessive, and moderately abundant minority species can be adequately detected.

Molecular Weight↗

PubMed2005

Time-resolved imaging of the plume dynamics in infrared matrix-assisted laser desorption/ionization with a glycerol matrix.

The dynamics of the expanding material plume after irradiation of a matrix sample with two different infrared (IR) lasers, an Er:YAG laser of ca. 100 ns and an optical parametric oscillator (OPO) laser system of 6 ns pulse duration, were investigated by imaging the plumes with nanosecond time resolution. Both lasers emitted at an identical wavelength of 2.94 microm. Laser exposure parameters were typical for infrared matrix-assisted laser desorption/ionization mass spectrometry (IR-MALDI-MS); glycerol was employed as a liquid matrix to provide a homogeneous sample and reproducible plume formation. A Nd:YAG laser (532 nm; 8 ns) was used as the illumination source and a CMOS camera with a ten-bit dynamic range served for recording of the images. Dark-field as well as scattered light illumination was employed to preferentially image the gaseous and particulate components of the plume, respectively. During the initial phase of its expansion (ca. 1 micros) the plume appears to consist of a continuous cloud of material of varying density. At later times after exposure, individual particles of several micrometers in size dominate the images. For both laser pulse durations material ejection was observed for times as long as 100 micros postexposure. Subtle but distinct differences in the plume dynamics are observed for the two different pulse durations. They are related to a transition between the regimes below and above acoustic confinement. The experimental findings are compared to results obtained in two previous studies by photoacoustic analysis of the desorption process and IR-laser postionization of the plume.

Glycerol↗

PubMed1998

Proteolysis of extracellular matrix by invadopodia facilitates human breast cancer cell invasion and is mediated by matrix metalloproteinases.

Breast cancer cell lines vary in invasive behavior and one highly invasive cell line (MDA-MB-231) proteolytically degrades extracellular matrix with invadopodia (Thompson et al. 1992, J Cell Physiol, 150, 534-44; Chen et al 1994, Breast Cancer Res Treat, 31, 217-26). Invadopodial proteolysis of extracellular matrix is thought to be necessary for invasion; however, this has not been demonstrated directly. To obtain such evidence, normal (HBL-100) and malignant (MCF-7, MDA-MB-231) breast cells were evaluated for invadopodial proteolysis of extracellular matrix and invasive behavior. We report that invadopodial proteolysis of immobilized fibronectin is positively correlated with invasion of cells into type I collagen gels. Moreover, reducing the proteolytic activity of invadopodia with the metalloproteinase inhibitor, batimastat (BB-94), also decreases invasion indicating that breast cancer cell invasion is dependent upon proteolytically active invadopodia.

Breast Neoplasms↗

PubMed1996

Transmembrane-deletion mutants of the membrane-type matrix metalloproteinase-1 process progelatinase A and express intrinsic matrix-degrading activity.

Membrane-type matrix metalloproteinase-1 (MT-MMP-1) has been proposed to play a critical role in regulating the expression of tissue-invasive phenotypes in normal and neoplastic cells by directly or indirectly mediating the activation of progelatinase A. To begin characterizing MT-MMP-1 structure-function relationships, transmembrane-deletion mutants were constructed, and the processing of the zymogens as well as the enzymic activity of the mature proteinases was analyzed. We now demonstrate that pro-MT-MMP-1 mutants are efficiently processed to active proteinases following post-translational endoproteolysis immediately downstream of an Arg108-Arg-Lys-Arg basic motif by a proprotein convertase-dependent pathway. The secreted form of active MT-MMP-1 not only displays an N terminus identical with that described for the processed wild-type enzyme at Tyr112 (Strongin, A. Y., Collier, I., Bannikov, G., Marmer, B. L., Grants, G. A., and Goldberg, G. I. (1995) J. Biol. Chem. 270, 5331-5338), but also directly mediated progelatinase A activation via a two-step proteolytic cascade indistinguishable from that observed with intact cells. Furthermore, although the only function previously ascribed to MT-MMP-1 is its ability to act as a progelatinase A activator, purified transmembrane deletion mutants also expressed proteolytic activities against a wide range of extracellular matrix molecules. Given recent reports that MT-MMP-1 ectodomains may undergo intercellular transfer in vivo (Okada, A., Bellocq, J.-P., Rouyer, N., Chenard, M.-P., Rio, M.-C., Chambon, P., and Basset, P. (1995) Proc. Natl. Acad. Sci. U. S. A. 92, 2730-2734), our data suggest that soluble forms of the proteinase confer recipient cells with the ability to not only process progelatinase A, but also directly degrade extracellular matrix components.

Amino Acid Sequence↗

PubMed1997

The hemopexin-like domain (C domain) of human gelatinase A (matrix metalloproteinase-2) requires Ca2+ for fibronectin and heparin binding. Binding properties of recombinant gelatinase A C domain to extracellular matrix and basement membrane components.

The binding properties of the COOH-terminal hemopexin-like domain (C domain) of human gelatinase A (matrix metalloproteinase-2, 72-kDa gelatinase) were investigated to determine whether the C domain has binding affinity for extracellular matrix and basement membrane components. Recombinant C domain (rC domain) (Gly417-Cys631) was expressed in Escherichia coli, and the purified protein, identified using two antipeptide antibodies, was determined by electrospray mass spectrometry to have a mass of 25,925 Da, within 0.1 Da of that predicted. As assessed by microwell substrate binding assays and by column affinity chromatography, the matrix proteins laminin, denatured type I collagen, elastin, SPARC (secreted protein that is acidic and rich in cysteine), tenascin, and MatrigelTM were not bound by the rC domain. Unlike the hemopexin-like domains of collagenase and stromelysin, the rC domain also did not bind native type I collagen. Nor were native or denatured types II, IV, V, and X collagen, or the NC1 domain of type VII collagen bound. However, binding to heparin and fibronectin (Kd, 1.1 x 10(-6) M) could be disrupted by 0.58-0.76 and 0.3 M NaCl, respectively. Using nonoverlapping chymotrypsin-generated fragments of fibronectin, binding sites for the rC domain were found on both the 40-kDa heparin binding and the 120-kDa cell binding fibronectin domains (Kd values, approximately 4-6 x 10(-7) M). The Ca2+ ion, but not the potential structural Zn2+ ion, were found to be essential for maintaining the binding properties of the protein. The apo-form of the rC domain did not bind heparin, and both ethylenediaminetetraacetic acid and the specific Ca2+ ion chelator 1, 2-bis(2-aminophenoxy) ethane-N,N,N',N'-tetraacetic acid, but not the Zn2+ ion chelator 1,10-phenanthroline, eluted the holo form of the rC domain from both heparin-Sepharose and fibronectin. Inductive coupled plasma mass spectrometry also did not detect a Zn2+ ion in the rC domain. In contrast, reduction with 65 mM dithiothreitol did not interfere with heparin binding, further emphasizing the crucial structural role played by the Ca2+ ion. Together, these data demonstrate for the first time that the hemopexin-like domain of gelatinase A has a binding site for fibronectin and heparin, and that Ca2+ ions are important in maintaining the structure and function of the domain.

Binding Sites↗

PubMed1997

Human thyroid carcinoma cell lines and normal thyrocytes: expression and regulation of matrix metalloproteinase-1 and tissue matrix metalloproteinase inhibitor-1 messenger-RNA and protein.

Matrix metalloproteinase-1 (MMP-1) and tissue matrix metalloproteinase inhibitor 1 (TIMP-1) play an important role in remodeling the extracellular matrix in normal and pathological processes. The effect of phorbol-myristate acetate (PMA), interleukin-1 (IL-1), and tumor necrosis factor-alpha (TNF-alpha) on MMP-1 and TIMP-1 expression was studied on highly purified thyrocytes and undifferentiated 8505 C, C 643, HTh 74, SW 1736 thyroid carcinoma cells compared with thyroid-derived fibroblasts. Messenger RNA (mRNA) levels were monitored by competitive semiquantitative reverse transcriptase polymerase chain reaction (RT-PCR) after 24 hours. Culture supernatants were assayed for free and/or complexed MMP-1 and TIMP-1 after 48 hours using enzyme-linked immunosorbent assay (ELISA) systems (detection limit: <2 ng/mL). MMP-1 and TIMP-1 mRNA were present in all cell types, although thyrocytes showed MMP-1 mRNA levels near the detection limit. 8505 C expressed MMP-1 mRNA levels of up to 10(6) times those of the other cells analyzed. PMA and IL-1 increased MMP-1 mRNA in most cell types. TIMP-1 mRNA increased after treatment with PMA in all cells except 8505 C, whereas only slight effects were shown after IL-1 stimulation. MMP-1 protein was undetectable in normal thyrocyte cultures, but was secreted spontaneously by all cell lines ([ng/mL]; C 643: 15+/-7; HTh 74: 81+/-1; SW 1736: 13+/-2; 8505 C: 2097+/-320). There was a strong correlation between levels of MMP-1 mRNA and protein (r = 0.99, p < .0001). PMA and IL-1 increased MMP-1 secretion in all cell types after 48 hours. Fibroblasts ([ng/mL] 517+/-55) and the cell lines (C 643: 142+/-48; HTh 74: 115+/-13; SW 1736: 202+/-14; 8505C: 120+/-19) secreted TIMP-1 in unstimulated cultures, whereas only a trace amount was detected in thyrocyte cultures, even after PMA treatment. IL-1 upregulated TIMP-1 secretion after 48 hours in SW 1736, HTh 74, and C 643 cells. Our data suggest that in contrast to normal thyrocytes, dedifferentiated thyroid carcinoma cell lines are potential producers of MMP-1 as well as TIMP-1. High MMP-1 or MMP-1/TIMP-1 expression may play a role in tissue invasion of undifferentiated thyroid cancer cells.

Adult↗

PubMed1993

Extracellular matrix. 2: Role of extracellular matrix molecules and their receptors in the nervous system.

Extracellular matrix molecules help regulate many aspects of neural development, including survival, migration, axon growth, and synapse formation by neurons. These same molecules have been shown to modulate regeneration of neurons after injuries. They also regulate the development and differentiation of other neural cells, such as astroglia and Schwann cells. Significant progress has been made recently in characterizing both ECM constituents and their receptors in the nervous system. Extracellular matrix molecules promote cell adhesion, activate intracellular signaling pathways, and modulate the activities of several growth factors and proteins. Our current understanding of the extracellular matrix, its receptors, and its functions in the nervous system are discussed.

Animals↗

PubMed2002

Suppression of transgene silencing by matrix attachment regions in maize: a dual role for the maize 5' ADH1 matrix attachment region.

Matrix attachment regions (MARs) are DNA sequences that bind an internal nuclear network of nonhistone proteins called the nuclear matrix. Thus, they may define discrete gene-containing chromatin loops in vivo. We have studied the effects of flanking transgenes with MARs on transgene expression levels in maize callus and in transformed maize plants. Three MAR elements, two from maize (Adh1 5' MAR and Mha1 5' MAR) and one from yeast (ARS1), had very different effects on transgene expression that bore no relation to their affinity for the nuclear matrix in vitro. In callus, two of the MAR elements (Adh1 5' MAR and ARS1) reduced transgene silencing but had no effect on the variability of expression. In transgenic plants, Adh1 5' MAR had the effect of localizing beta-glucuronidase expression to lateral root initiation sites. A possible model accounting for the function of Adh1 5' MAR is discussed.

Culture Techniques↗

PubMedDate not supplied

Phenotypic modifications of human mesangial cells by extracellular matrix: the importance of matrix in the contractile response to reactive oxygen species.

The progression of chronic renal diseases is characterized by the accumulation of extracellular matrix proteins in the glomerulus. The present experiments were designed to analyze the effect of hydrogen peroxide on the contractile and proliferative phenotypes of human mesangial cells grown on different culture substrates: plastic, collagen type I, and collagen type IV. Contraction was analyzed by measuring planar cell surface area and myosin light chain phosphorylation, whereas proliferation was studied by [(3)H]thymidine incorporation. No changes were detected in the proliferation rate of human mesangial cells grown on different culture substrates, neither under basal conditions nor in the presence of fetal calf serum or H(2)O(2). Cells grown on plastic or collagen did not contract in the presence of H(2)O(2), but cells grown on collagen I elicited a significant contraction with H(2)O(2). Platelet-activating factor induced contraction of human mesangial cells on the three culture substrates. The different contractile responses observed were not due to different degradation rates of H(2)O(2). The present experiments support the importance of extracellular matrix in the response to exogenous stimuli and point to the possibility that patients with changes in the mesangial matrix as a result of chronic renal diseases may have an increased susceptibility to the pathological actions of reactive oxygen species.

Cells, Cultured↗