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During the last 40 years, Ecuador has based its economy on extractive activities, mainly in Amazonia where there are fossil resources. Industrial practices have had negative effects. The results from a survey about vulnerabilities and capacities against the impacts of petroleum activities suggests a difficult social construction of the sanitarian risk, due to the numerous perceptions, local economic dependencies and an insufficient commitment from public actors with this issue. [ABSTRACT FROM AUTHOR]

Pigment epithelium-derived factor (PEDF), a potent blocker of angiogenesis in vivo, and of endothelial cell migration and tubule formation, binds with high affinity to an as yet unknown protein on the surfaces of endothelial cells. Given that protein fingerprinting suggested a match of a ∼ 60 kDa PEDF-binding protein in bovine retina with Bos taurus F1-ATP synthase β-subunit, and that F1Fo-ATP synthase components have been identified recently as cell-surface receptors, we examined the direct binding of PEDF to F1. Size-exclusion ultrafiltration assays showed that recombinant human PEDF formed a complex with recombinant yeast F1. Real-time binding as determined by surface plasmon resonance demonstrated that yeast F1 interacted specifically and reversibly with human PEDF. Kinetic evaluations revealed high binding affinity for PEDF, in agreement with PEDF affinities for endothelial cell surfaces. PEDF blocked interactions between F1 and angiostatin, another antiangiogenic factor, suggesting overlapping PEDF-binding and angiostatin-binding sites on F1. Surfaces of endothelial cells exhibited affinity for PEDF-binding proteins of ∼ 60 kDa. Antibodies to F1β-subunit specifically captured PEDF-binding components in endothelial plasma membranes. The extracellular ATP synthesis activity of endothelial cells was examined in the presence of PEDF. PEDF significantly reduced the amount of extracellular ATP produced by endothelial cells, in agreement with direct interactions between cell-surface ATP synthase and PEDF. In addition to demonstrating that PEDF binds to cell-surface F1, these results show that PEDF is a ligand for endothelial cell-surface F1Fo-ATP synthase. They suggest that PEDF-mediated inhibition of ATP synthase may form part of the biochemical mechanisms by which PEDF exerts its antiangiogenic activity. Structured digital abstract • : angiostatin (uniprotkb: ) physically interacts ( ) with F-ATPase alpha subunit (uniprotkb: ), F-ATPase beta subunit (uniprotkb: ), F-ATPase gamma subunit (uniprotkb: ), F-ATPase delta subunit (uniprotkb: ) and F-ATPase epsilon subunit (uniprotkb: ) by competition binding ( ) • : angiostatin (uniprotkb: ) physically interacts ( ) with F-ATPase epsilon subunit (uniprotkb: ), F-ATPase delta subunit (uniprotkb: ), F-ATPase gamma subunit (uniprotkb: ), F-ATPase beta subunit(uniprotkb: ) and F-ATPase alpha subunit (uniprotkb: ) by surface plasmon resonance ( ) • : F-ATPase gamma subunit (uniprotkb: ), F-ATPase beta subunit (uniprotkb: ), F-ATPase alpha subunit (uniprotkb: ) and PEDF (uniprotkb: ) physically interact ( ) by molecular sieving ( ) • : F-ATPase epsilon subunit (uniprotkb: ), F-ATPase delta subunit (uniprotkb: ), PEDF (uniprotkb: ), F-ATPase alpha subunit (uniprotkb: ), F-ATPase beta subunit (uniprotkb: ) and F-ATPase gamma subunit(uniprotkb: ) physically interact ( ) by molecular sieving ( ) • : PEDF (uniprotkb: ) physically interacts ( ) with F-ATPase epsilon subunit (uniprotkb: ), F-ATPase delta subunit (uniprotkb: ), F-ATPase gamma subunit (uniprotkb: ), F-ATPase beta subunit (uniprotkb: ) and F-ATPase alpha subunit (uniprotkb: ) by surface plasmon resonance ( ) [ABSTRACT FROM AUTHOR]

Pigment epithelium-derived factor (PEDF) is an extracellular protein derived from the retinal pigment epithelium (RPE), a tissue formed by polarized cells that release growth and trophic factors in a directional fashion. We have investigated the distribution and directional release of PEDF protein by the monkey RPE. We established primary cultures of monkey RPE cells that expressed the PEDF gene, and that synthesized and secreted the PEDF protein. Northern analysis of RPE cultures and monkey ocular tissues showed that PEDF transcripts were highly expressed in RPE as compared with several other monkey ocular tissues, being even more abundant in cultured cells than they were in the native RPE. The differentiated RPE cells in culture secreted protein that shared the immunological, biochemical and biological characteristics of PEDF. The overall PEDF levels in the RPE conditioned media reached 6·5 mg ml− after 8 days in culture (i.e. 1·1 pg of PEDF per RPE cell). RPE cells were cultivated on permeable supports as monolayers forming a barrier between apical and basal compartments. Apical and basal culture media were sampled at three or four-day intervals for 18 cycles, and the PEDF content was quantified. Most of the PEDF protein was significantly higher in the apical than in the basal medium (>4 times) at the initial recovery intervals, to be detected only in the apical medium at the latter intervals. In the native monkey eye, the concentration of soluble PEDF in the interphotoreceptor matrix (144 nm) was 7-fold and 25-fold greater than in vitreous and aqueous, respectively. PEDF was abundant in the interphotoreceptor matrix surrounding rod and cone outer segments, and was detectable at lower levels in the RPE as visualized by confocal microscopy. We concluded that PEDF synthesized by the RPE is secreted preferentially from the apical surface and is distributed apically to the RPE bordering the outer segments of photoreceptors. PEDF can be a useful marker for RPE polarization and differentiation. The polarization of RPE may be an important mechanism to control PEDF secretion and our results offer interesting possibilities on regulation of PEDF. [Copyright &y& Elsevier]

Background: Pigment epithelium-derived factor (PEDF) has binding affinity for cell-surface receptors in retinoblastoma cells and for glycosaminoglycans. We investigated the effects of glycosaminoglycans on PEDF-receptor interactions. Results: 125I-PEDF formed complexes with protease-resistant components of medium conditioned by human retinoblastoma Y-79 cells. Using specific glycosaminoglycan degrading enzymes in spectrophotometric assays and PEDF-affinity chromatography, we detected heparin and heparan sulfate-like glycosaminoglycans in the Y-79 conditioned media, which had binding affinity for PEDF. The Y-79 conditioned media significantly enhanced the binding of 125I-PEDF to Y-79 cell-surface receptors. However, enzymatic and chemical depletion of sulfated glycosaminoglycans from the Y-79 cell cultures by heparitinase and chlorate treatments decreased the degree of 125I-PEDF binding to cell-surface receptors. Conclusions: These data indicate that retinoblastoma cells secrete heparin/heparan sulfate with binding affinity for PEDF, which may be important in efficient cell-surface receptor binding. [ABSTRACT FROM AUTHOR]

The present study compared susceptibilities of Sprague Dawley (SD) and Brown Norway (BN) rats with ischemia-induced retinal neovascularization. An exposure to constant hyperoxia followed by normoxia induced significant retinal neovascularization in BN rats but not in SD rats, as demonstrated by fluorescein retinal angiography, measurement of avascular area, and count of preretinal vascular cells. These results indicate a rat strain difference in susceptibility to retinal neovascularization. To understand the molecular basis responsible for the strain difference, we have measured the levels of pigment epithelium-derived factor (PEDF), an angiogenic inhibitor, and vascular endothelial growth factor (VEGF), a major angiogenic stimulator in the retina. The hyperoxia-treated BN rats showed a significant reduction in retinal PEDF, but they showed a substantial increase of VEGF at both the protein and RNA levels, resulting in an increased VEGF-to-PEDF ratio. Hyperoxia-treated SD rats showed changes in PEDF and VEGF levels that were less in magnitude and of shorter duration than in BN rats. In age-matched normal BN and SD rats, however, there was no detectable difference in the basal VEGF-to-PEDF ratio between the strains. These observations support the idea that different regulation of angiogenic inhibitors and stimulators under ischemia are responsible for the differences in susceptibility to ischemia-induced retinal neovascularization in SD and BN rats. [ABSTRACT FROM AUTHOR]

Retinoprotective proteins play important roles for retinal tissue integrity. They can directly affect the function and the survival of photoreceptors, and/or indirectly target the retinal pigment epithelium (RPE) and endothelial cells that support these tissues. Retinoprotective proteins are used in basic, translational and in clinical studies to prevent and treat human retinal degenerative disorders. In this review, we provide an overview of proteins that protect the retina and focus on pigment epithelium-derived factor (PEDF), and its effects on photoreceptors, RPE cells, and endothelial cells. We also discuss delivery systems such as pharmacologic and genetic administration of proteins to achieve photoreceptor survival and retinal tissue integrity. [ABSTRACT FROM AUTHOR]

Here, we evaluated the effects of PEDF (pigment epithelium-derived factor) and PEDF peptides on cone-photoreceptor cell damage in a mouse model of focal LED-induced phototoxicity (LIP) in vivo. Swiss mice were dark-adapted overnight, anesthetized, and their left eyes were exposed to a blue LED placed over the cornea. Immediately after, intravitreal injection of PEDF, PEDF-peptide fragments 17-mer, 17-mer[H105A] or 17-mer[R99A] (all at 10 pmol) were administered into the left eye of each animal. BDNF (92 pmol) and bFGF (27 pmol) injections were positive controls, and vehicle negative control. After 7 days, LIP resulted in a consistent circular lesion located in the supratemporal quadrant and the number of S-cones were counted within an area centered on the lesion. Retinas treated with effectors had significantly greater S-cone numbers (PEDF (60%), 17-mer (56%), 17-mer [H105A] (57%), BDNF (64%) or bFGF (60%)) relative to their corresponding vehicle groups (≈42%). The 17-mer[R99A] with no PEDF receptor binding and no neurotrophic activity, PEDF combined with a molar excess of the PEDF receptor blocker P1 peptide, or with a PEDF-R enzymatic inhibitor had undetectable effects in S-cone survival. The findings demonstrated that the cone survival effects were mediated via interactions between the 17-mer region of the PEDF molecule and its PEDF-R receptor. [ABSTRACT FROM AUTHOR]

The article focuses on the antiapoptotic effects of hypoxia on photoreceptors. Erythropoietin has neuroprotective effects, in addition to its effects on photoreceptors. It is also involved in the outgrowth of neurites from retinal ganglion cells. A recent report has showed that hypoxic preconditioning protected the morphology and function of photoreceptors by preventing light-induced apoptosis. Hypoxia induces the expression of hypoxia-inducible factor 1. Another study demonstrated that erythropoietin protects retinal ganglion cells from acute ischemia. It also showed that reperfusion injury is protected by erythropoietin through an antiapoptotic mechanism. One more study showed the effect of erythropoietin on promoting neural outgrowth from retinal ganglion cells.

The retinal pigment epithelium (RPE) expresses the Serpinf1 gene to produce pigment epithelium-derived factor (PEDF), a retinoprotective protein that is downregulated with cell senescence, aging and retinal degenerations. We determined the expression of senescence-associated genes in the RPE of 3-month-old mice that lack the Serpinf1 gene and found that Serpinf1 deletion induced H2ax for histone H2AX protein, Cdkn1a for p21 protein, and Glb1 gene for β-galactosidase. Senescence-associated β-galactosidase activity increased in the Serpinf1 null RPE when compared with wild-type RPE. We evaluated the subcellular morphology of the RPE and found that ablation of Serpinf1 increased the volume of the nuclei and the nucleoli number of RPE cells, implying chromatin reorganization. Given that the RPE phagocytic function declines with aging, we assessed the expression of the Pnpla2 gene, which is required for the degradation of photoreceptor outer segments by the RPE. We found that both the Pnpla2 gene and its protein PEDF-R declined with the Serpinf1 gene ablation. Moreover, we determined the levels of phagocytosed rhodopsin and lipids in the RPE of the Serpinf1 null mice. The RPE of the Serpinf1 null mice accumulated rhodopsin and lipids compared to littermate controls, implying an association of PEDF deficiency with RPE phagocytosis dysfunction. Our findings establish PEDF loss as a cause of senescence-like changes in the RPE, highlighting PEDF as both a retinoprotective and a regulatory protein of aging-like changes associated with defective degradation of the photoreceptor outer segment in the RPE. [ABSTRACT FROM AUTHOR]

Pigment epithelium-derived factor (PEDF) is a secreted protein that is essential in tissue homeostasis and is involved in multiple functions in the eye, such as antiangiogenesis and neuroprotection. However, short retention in the retinal microenvironment can limit its therapeutic effects. In this study, we modified the amino acid sequence of PEDF to increase its affinity for heparin and hyaluronic acid (HA), which are negatively charged extracellular matrix (ECM) molecules. HA is the major component of the vitreous humor. We selectively converted neutral or anionic residues into cationic residues to obtain engineered PEDF (ePEDF). Using in vitro binding assays, we demonstrate that ePEDF had higher affinity for heparin and HA than wild-type PEDF (wtPEDF). ePEDF exhibited antiangiogenic and retinal survival bioactivities. It inhibited endothelial cell proliferation and tube formation in vitro. In an ex vivo model mimicking retinal degeneration, ePEDF protected photoreceptors from cell death. The findings suggest that protein engineering is an approach to develop active PEDF with higher ECM affinity to potentially improve its retention in the retina microenvironment and in turn make it a more efficient therapeutic drug for retinal diseases. • Short retention in the vitreous humor prevents the translation of pigment epithelium-derived factor (PEDF) protein therapy. • PEDF engineering increases cationic property and enhances binding to heparin and HA, which are abundant in the vitreous humor. • In vitro and ex vivo models evaluate antiangiogenic and neuroprotective properties of engineered PEDF. [ABSTRACT FROM AUTHOR]

The main objective of this paper was to analyze the arguments employed by residents of a municipality of the State of Mexico to justify some violent practices perpetrated by the State and that have been used as a strategy in recent years to address the issue of public insecurity. To this effect, a research work from the qualitative paradigm was carried out,using the semi- structured interview as the main tool. The argumentative discourse analysis revealed that the justification, rather than being based on a perception of widespread insecurity, paradoxically, haditssupport on social discontent with the authorities responsible for the administration and enforcement of justice. The most frequent arguments were: efficiency, defense, and proportional punishment. In each one of them, the social construction of offenders, the meaning system about "the violent", the concept of justice and the degree of damage perceived for the participant were present.