3,104 research outputs found

    Balance of corneal horizontal coma by internal optics in eyes with intraocular artificial lenses: Evidence of a passive mechanism

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    It is well known that the aberrations of the cornea are partially compensated by the aberrations of the internal optics of the eye (primarily the crystalline lens) in young subjects. This effect has been found not only for the spherical aberration, but also for horizontal coma. It has been debated whether the compensation of horizontal coma is the result of passive mechanism [Artal, P., Benito, A., & Tabernero, J. (2006). The human eye is an example of robust optical design. Journal of Vision, 6 (1), 1–7] or through an active developmental feedback process [Kelly, J. E., Mihashi, T., & Howland, H. C. (2004). Compensation of corneal horizontal/vertical astigmatism, lateral coma, and spherical aberration by internal optics of the eye. Journal of Vision, 4 (4), 262–271]. In this study we investigate the active or passive nature of the horizontal coma compensation using eyes with artificial lenses, where no active developmental process can be present. We measured total and corneal aberrations, and lens tilt and decentration in a group of 38 eyes implanted with two types of intraocular lenses designed to compensate the corneal spherical aberration of the average population. We found that spherical aberration was compensated by 66%, and horizontal coma by 87% on average. The spherical aberration is not compensated at an individual level, but horizontal coma is compensated individually (coefficients of correlation corneal/internal aberration: _0.946, p < 0.0001). The fact that corneal (but not total) horizontal coma is highly correlated with angle lamda (computed from the shift of the 1st Purkinje image from the pupil center, for foveal fixation) indicates that the compensation arises primarily from the geometrical configuration of the eye (which generates horizontal coma of opposite signs in the cornea and internal optics). The amount and direction of tilts and misalignments of the lens are comparable to those found in young eyes, and on average tend to compensate (rather than increase) horizontal coma. Computer simulations using customized model eyes and different designs of intraocular lenses show that, while not all designs produce a compensation of horizontal coma, a wide range of aspheric biconvex designs may produce comparable compensation to that found in young eyes with crystalline lenses, over a relatively large field of view. These findings suggest that the lens shape, gradient index or foveal location do not need to be fine-tuned to achieve a compensation of horizontal coma. Our results cannot exclude a fine-tuning for the orientation of the crystalline lens, since cataract surgery seems to preserve the position of the capsule

    RHOMOLO V3: A Spatial Modelling Framework

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    In this paper we provide the mathematical presentation of the RHOMOLO model. In addition, we perform some stylized and illustrative simulations with the aim to make the reader familiar with the economic adjustment mechanisms incorporated into the model. Essentially, we attempt to offer the reader and the potential users of the model an intuition of the transmission channels existing in the current version RHOMOLO. The analysis is kept simple to facilitate a better understanding of the model's findings. We simulate a permanent demand-side shock implemented separately for each of the 267 regions contained in the model. We repeat the same simulation under three alternative labour market closures and three different imperfectly competitive product market structures.JRC.B.3-Territorial Developmen

    The N-glycan structures of the antigenic variants of chlorovirus PBCV-1 major capsid protein help to identify the virus-encoded glycosyltransferases

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    The chlorovirus Paramecium bursaria chlorella virus 1 (PBCV-1) is a large dsDNA virus that infects the microalga Chlorella variabilis NC64A. Unlike most other viruses, PBCV-1 encodes most, if not all, of the machinery required to glycosylate its major capsid protein (MCP). The structures of the four N-linked glycans from the PBCV-1 MCP consist of nonasaccharides, and similar glycans are not found elsewhere in the three domains of life. Here, we identified the roles of three virus-encoded glycosyltransferases (GTs) that have four distinct GT activities in glycan synthesis. Two of the three GTs were previously annotated as GTs but the third GT was identified in this study. We determined the GT functions by comparing the wild-type glycan structures from PBCV-1 with those from a set of PBCV-1 spontaneous GT genes mutants resulting in antigenic variants having truncated glycan structures. According to our working model, the virus gene a064r encodes a GT with three domains: domain 1 has a β-L-rhamnosyltransferase activity, domain 2 has an α -L-rhamnosyltransferase activity and domain 3 is a methyltransferase that decorates two positions in the terminal α -L-rhamnose (Rha) unit. The a075l gene encodes a β -xylosyltransferase that attaches the distal D-xylose (Xyl) unit to the L-fucose (Fuc) that is part of the conserved N-glycan core region. Lastly, gene a071r encodes a GT that is involved in the attachment of a semiconserved element, α-D-Rha, to the same L-Fuc in the core region. Our results uncover GT activities that assemble four of the nine residues of the PBCV-1 MCP N-glycans. Includes supplemental material

    Antimicrobial peptides : insights into membrane permeabilization, lipopolysaccharide fragmentation and application in plant disease control

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    The recent increase in multidrug resistance against bacterial infections has become a major concern to human health and global food security. Synthetic antimicrobial peptides (AMPs) have recently received substantial attention as potential alternatives to conventional antibiotics because of their potent broad-spectrum antimicrobial activity. These peptides have also been implicated in plant disease control for replacing conventional treatment methods that are polluting and hazardous to the environment and to human health. Here, we report de novo design and antimicrobial studies of VG16, a 16-residue active fragment of Dengue virus fusion peptide. Our results reveal that VG16KRKP, a non-toxic and non-hemolytic analogue of VG16, shows significant antimicrobial activity against Gram-negative E. coli and plant pathogens X. oryzae and X. campestris, as well as against human fungal pathogens C. albicans and C. grubii. VG16KRKP is also capable of inhibiting bacterial disease progression in plants. The solution-NMR structure of VG16KRKP in lipopolysaccharide features a folded conformation with a centrally located turn-type structure stabilized by aromatic-aromatic packing interactions with extended N-and C-termini. The de novo design of VG16KRKP provides valuable insights into the development of more potent antibacterial and antiendotoxic peptides for the treatment of human and plant infections

    Aging-Associated miR-217 Aggravates Atherosclerosis and Promotes Cardiovascular Dysfunction.

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    microRNAs are master regulators of gene expression with essential roles in virtually all biological processes. miR-217 has been associated with aging and cellular senescence, but its role in vascular disease is not understood. Approach and Results: We have used an inducible endothelium-specific knock-in mouse model to address the role of miR-217 in vascular function and atherosclerosis. miR-217 reduced NO production and promoted endothelial dysfunction, increased blood pressure, and exacerbated atherosclerosis in proatherogenic apoE-/- mice. Moreover, increased endothelial miR-217 expression led to the development of coronary artery disease and altered left ventricular heart function, inducing diastolic and systolic dysfunction. Conversely, inhibition of endogenous vascular miR-217 in apoE-/- mice improved vascular contractility and diminished atherosclerosis. Transcriptome analysis revealed that miR-217 regulates an endothelial signaling hub and downregulates a network of eNOS (endothelial NO synthase) activators, including VEGF (vascular endothelial growth factor) and apelin receptor pathways, resulting in diminished eNOS expression. Further analysis revealed that human plasma miR-217 is a biomarker of vascular aging and cardiovascular risk. Our results highlight the therapeutic potential of miR-217 inhibitors in aging-related cardiovascular disease.V.G. de Yébenes was supported by Ramón y Cajal grant RYC-2009-04503 and AECC foundation grant INVES18013GARC and by the Universidad Complutense de Madrid. S.M. Mur and A.R. Ramiro are supported by Centro Nacional de Investigaciones Cardiovasculares (CNIC) funding. A.R. Ramiro was supported by the Spanish Ministerio de Ciencia e Innovación (PID2019-107551RB-I00), the Spanish Ministerio de Economía, Industria y Competitividad (SAF2013-42767-R and SAF2016-75511-R), and the European Research Council StG BCLYM. M. Salaices was supported by the Ministerio de Ciencia e Innovación (SAF2016-80305P) and with J. Miguel Redondo by Instituto de Salud Carlos III (CIBER de Enfermedades Cardiovasculares, CB16/11/00286 and CB16/11/00264) and Comunidad de Madrid (B2017/BMD-3676). V.G. de Yébenes was supported by Ministerio de Ciencia e Innovación (PID2019-107551RB-I00). Further support was provided by the European Social Fund and the European Regional Development Fund “A Way to Build Europe.” The CNIC is supported by Ministerio de Ciencia, Innovacion y Universidades, and the Pro CNIC Foundation and is a Severo Ochoa Center of Excellence (SEV-2015-0505).S

    Protection from Staphylococcus aureus mastitis associated with poly-N-acetyl beta-1,6 glucosamine specific antibody production using biofilm-embedded bacteria

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    Staphylococcus aureus vaccines based on bacterins surrounded by slime, surface polysaccharides coupled to protein carriers and polysaccharides embedded in liposomes administered together with non-biofilm bacterins confer protection against mastitis. However, it remains unknown whether protective antibodies are directed to slime-associated known exopolysaccharides and could be produced in the absence of bacterin immunizations. Here, a sheep mastitis vaccination study was carried out using bacterins, crude bacterial extracts or a purified exopolysaccharide from biofil

    Plk1 regulates contraction of postmitotic smooth muscle cells and is required for vascular homeostasis

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    Polo-like kinase 1 (PLK1), an essential regulator of cell division, is currently undergoing clinical evaluation as a target for cancer therapy. We report an unexpected function of Plk1 in sustaining cardiovascular homeostasis. Plk1 haploinsufficiency in mice did not induce obvious cell proliferation defects but did result in arterial structural alterations, which frequently led to aortic rupture and death. Specific ablation of Plk1 in vascular smooth muscle cells (VSMCs) led to reduced arterial elasticity, hypotension, and an impaired arterial response to angiotensin II in vivo. Mechanistically, we found that Plk1 regulated angiotensin II-dependent activation of RhoA and actomyosin dynamics in VSMCs in a mitosis-independent manner. This regulation depended on Plk1 kinase activity, and the administration of small-molecule Plk1 inhibitors to angiotensin II-treated mice led to reduced arterial fitness and an elevated risk of aneurysm and aortic rupture. We thus conclude that a partial reduction of Plk1 activity that does not block cell division can nevertheless impair aortic homeostasis. Our findings have potentially important implications for current approaches aimed at PLK1 inhibition for cancer therapy.This work-was supported by the Marie Curie activities of the European Commission (Oncotrain program; fellowship to P.W), the Spanish Ministry of Economy and Competitiveness (MINECO; fellowship to A.G.-L.), the CENIT AMIT Project "Advanced Molecular Imaging Technologies" (TEC2008-06715-C02-1, RD07/0014/2009 to F.M.), the Red de investigacion Cardiovascular (RIC), cofunded by FEDER (grant RD12/004240022 to J.M.R.; grant RD12/0042/0056 to L.J.J.-B), Fundacio La Marato TV3 (grant 20151331 to J.M.R.), the Castilla-Leon Autonomous Government (BIO/SA01/15, CS049U16 to X.R.B.), the Solorzano and Ramon Areces Foundations (to X.R.B.), MINECO (grants RD12/0036/0002 and SAF2015-64556-R to X.R.B.; SAF2015-63633-R to J.M.R.; and SAF2015-69920-R to M.M.), Consolider-Ingenio 2010 Programme (grant SAF2014-57791-REDC to M.M.), Red Tematica CellSYS (grant BFU2014-52125-REDT to M.M.), Comunidad de Madrid (OncoCycle Programme; grant S2010/BMD-2470 to M.M.), Worldwide Cancer Research (grants 14-1248 to X.R.B., and 15-0278 to M.M.) and the MitoSys project (European Union Seventh Framework Programme; grant HEALTH-F5-2010-241548 to M.M.). CNIC is supported by MINECO and the Pro-CNIC Foundation. CNIO and CNIC are Severo Ochoa Centers of Excellence (MINECO awards SEV-2015-0510 and SEV-2015-0505, respectively).S

    Multivalent glycoconjugates as anti-pathogenic agents

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    Multivalency plays a major role in biological processes and particularly in the relationship between pathogenic microorganisms and their host that involves protein–glycan recognition. These interactions occur during the first steps of infection, for specific recognition between host and bacteria, but also at different stages of the immune response. The search for high-affinity ligands for studying such interactions involves the combination of carbohydrate head groups with different scaffolds and linkers generating multivalent glycocompounds with controlled spatial and topology parameters. By interfering with pathogen adhesion, such glycocompounds including glycopolymers, glycoclusters, glycodendrimers and glyconanoparticles have the potential to improve or replace antibiotic treatments that are now subverted by resistance. Multivalent glycoconjugates have also been used for stimulating the innate and adaptive immune systems, for example with carbohydrate-based vaccines. Bacteria present on their surfaces natural multivalent glycoconjugates such as lipopolysaccharides and S-layers that can also be exploited or targeted in anti-infectious strategie
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