952 research outputs found

    Response processing during visual search in normal aging: the need for more time to prevent cross talk between spatial attention and manual response selection

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    [Abstract] It is still not well known whether the age-related behavioural slowing observed during visual search is due to changes in the allocation of attention, in response activation patterns, or to a combination of both. To help in clarifying it, attention-related (N2 posterior contralateral; N2pc, and N2 central contralateral; N2cc) and response-related (Motor Potential; MP, and Reafferent Potential; RAP) event-related potentials (ERPs) were obtained in healthy young and older participants executing a visual search task. Age was associated with N2pc and N2cc longer latencies, earlier MP onsets and longer MP rise times. Lower N2pc, higher MP and lower RAP amplitudes were also observed. Results suggest that older participants need more time to allocate spatial attention onto the target (N2pc) and to prevent cross talk between response selection and attention direction (N2cc), and that they are slower and need higher cortical activation when preparing and executing correctly selected responses (MP).Ministerio de Ciencia e InnovaciĂłn; PSI2010-21427Xunta de Galicia; 10PXIB211220P

    Response processing during visual search in normal aging: the need for more time to prevent cross talk between spatial attention and manual response selection

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    It is still not well known whether the age-related behavioural slowing observed during visual search is due to changes in the allocation of attention, in response activation patterns, or to a combination of both. To help in clarifying it, attention-related (N2 posterior contralateral; N2pc, and N2 central contralateral; N2cc) and response-related (Motor Potential; MP, and Reafferent Potential; RAP) event-related potentials (ERPs) were obtained in healthy young and older participants executing a visual search task. Age was associated with N2pc and N2cc longer latencies, earlier MP onsets and longer MP rise times. Lower N2pc, higher MP and lower RAP amplitudes were also observed. Results suggest that older participants need more time to allocate spatial attention onto the target (N2pc) and to prevent cross talk between response selection and attention direction (N2cc), and that they are slower and need higher cortical activation when preparing and executing correctly selected responses (MP).This study was supported by grants from the Spanish MICINN (PSI2010-21427) and Xunta de Galicia (10PXIB211220PR)S

    Asymmetry in Drug Permeability through the Cornea

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    The permeability through the cornea determines the ability of a drug or any topically applied compound to cross the tissue and reach the intraocular area. Most of the permeability values found in the literature are obtained considering topical drug formulations, and therefore, refer to the drug permeability inward the eye. However, due to the asymmetry of the corneal tissue, outward drug permeability constitutes a more meaningful parameter when dealing with intraocular drug-delivery systems (i.e., drug-loaded intraocular lenses, intraocular implants or injections). Herein, the permeability coefficients of two commonly administered anti-inflammatory drugs (i.e., bromfenac sodium and dexamethasone sodium) were determined ex vivo using Franz diffusion cells and porcine corneas in both inward and outward configurations. A significantly higher drug accumulation in the cornea was detected in the outward direction, which is consistent with the different characteristics of the corneal layers. Coherently, a higher permeability coefficient was obtained for bromfenac sodium in the outward direction, but no differences were detected for dexamethasone sodium in the two directions. Drug accumulation in the cornea can prolong the therapeutic effect of intraocular drug-release systemThis project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie SkƂodowska-Curie grant agreement N° 813440 (ORBITAL—Ocular Research by Integrated Training And Learning) and is also supported by the Fundação para a CiĂȘncia e Tecnologia (FCT) [UID/QUI/00100/2019, UIDB/00100/2020 and UID/BIM/04585/2020]S

    Le P3 en tant qu’index du niveau de performance de sujets ĂągĂ©s impliquĂ©s dans une tĂąche visuelle

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    Aim: To explore the possible changes in the parameters of the P3 event-related potential (ERP) component among groups of young and older healthy subjects characterized as either high- or low-performers in a visual attention task. Methods: Both conventional and single-trial analyses of the visual P3 component were performed on each group of subjects. Results: P3 component significantly increased in latency as a function of age. The high-performing older subjects showed the posterior predominance of P3, as in young subjects. However, the low-performing older subjects showed a significant P3 amplitude reduction at posterior locations and topographically more widespread activity. Furthermore, single-trial analysis showed that low-performing older subjects presented higher intertrial variability in P3 latency, few trials with P3 generation, and a reduced P3 amplitude in these trials in whom P3 was generated. Conclusion: These data suggest a specific decline in visual target processing in the low-performing older subjects, which would imply a reduction in these attentional brain resources that are allocated to correctly select the relevant stimuli. The implications of this finding for the actual compensation versus dedifferentiation debate in normal aging are discussedBut: Comparer les paramĂštres du composant P3 des potentiels Ă©voquĂ©s dans un groupe de sujets jeunes en bonne santĂ© et dans un groupe de sujets ĂągĂ©s classifiĂ©s en fonction de leur niveau d’exĂ©cution d’une tĂąche d’attention visuelle (meilleurs et moins bons exĂ©cuteurs). MĂ©thodes: Des analyses conventionnelles et des analyses « en sweep unique » du composant P3 ont Ă©tĂ© rĂ©alisĂ©es dans chaque groupe de sujets. RĂ©sultats: Le temps de latence du composant P3 augmente de façon significative avec l’ñge. Chez les sujets ĂągĂ©s meilleurs exĂ©cuteurs le P3 prĂ©dominait au niveau des rĂ©gions postĂ©rieures, comme chez les sujets jeunes. Par contre, chez les sujets ĂągĂ©s moins bons exĂ©cuteurs, le P3 Ă©tait significativement moins ample en postĂ©rieur et plus diffusĂ©ment rĂ©parti sur le scalp. Les analyses « en sweep unique » ont montrĂ© que ces derniers prĂ©sentaient une plus grande variabilitĂ© interessai en ce qui concerne le temps de latence de P3, moins de tests oĂč le P3 Ă©tait prĂ©sent, ainsi qu’une rĂ©duction de l’amplitude de P3 dans les tests oĂč il Ă©tait prĂ©sent. Conclusion: Ces donnĂ©es suggĂšrent l’existence d’un dĂ©ficit du traitement visuel des stimuli chez les sujets ĂągĂ©s moins bons exĂ©cuteurs qui pourrait consister en une rĂ©duction des ressources cĂ©rĂ©brales attentionnelles mobilisĂ©es pour sĂ©lectionner correctement le stimulus appropriĂ©. Nous discutons les implications de ces rĂ©sultats dans le dĂ©bat concernant la redistribution des aires corticales actives chez les sujets ĂągĂ©s (hypothĂšses de compensation versus dĂ©diffĂ©rentiation)This research was supported by grants from the Spanish MEC (SEJ2004-01377) and Xunta de Galicia (PGIDT05PXIC21101PN)S

    Vertical asymmetries and inhibition of return: effects of spatial and non-spatial cueing on behavior and visual ERPs

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    [Abstract] The mechanisms underlying inhibition of return (IOR) are still under debate. Besides the probable implication of several processes in its generation, a reason for this uncertainty may be related to experimental factors affecting the presence, time course, and magnitude of IOR. Two of them may be related to the arrangement of the stimuli in the visual field that could cause possible interactions between IOR and response conflict effects (horizontal arrangements) or between IOR and perceptual asymmetries (vertical arrangement). The purpose of the present study was to explore location and color cueing effects with a vertical arrangement of stimuli, free of S–R compatibility effects. To examine this possibility, a cue-back task with stimuli in the vertical meridian was employed. Targets could randomly and equiprobably appear at cued or uncued locations, or with cued or uncued color. These cueing effects were analyzed on behavior and ERPs separately for upper and lower visual fields (UVF and LVF). Under location cueing, behavioral responses were slower (spatial IOR) in both hemifields. In the ERPs, N1 reductions were observed in both visual fields although with different modulations in their latency and scalp distribution. In the P3 rising beginning, posterior negative deflections in the LVF (Nd) and anterior positive deflections (Pd) in the UVF were observed. Under color cueing, P3 amplitude was reduced in the UVF accompanied by no behavioral effects. These results suggest that different patterns of brain activation can be obtained in upper and lower visual fields under spatial- and non-spatial cueing conditions.Ministerio de Economía, Industria y Competitividad; PSI2010-21427Xunta de Galicia; 10PXIB211220P

    Drug-Loaded Hydrogels for Intraocular Lenses with Prophylactic Action against Pseudophakic Cystoid Macular Edema

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    Pseudophakic cystoid macular edema (PCME), caused by chronic inflammation, is the most common cause of visual impairment in the medium-term after cataract surgery. Therefore, the prophylactic topical administration of combined steroidal and non-steroidal anti-inflammatory drugs is commonly done. Drug-eluting intraocular lenses (IOLs) gained interest as an efficient way to overcome the compliance issues related to the use of ocular drops without the need for additional surgical steps. The incorporation of functional monomers and molecular imprinting were herein applied to design hydrogels suitable as IOLs and able to co-deliver steroidal (dexamethasone sodium phosphate) and non-steroidal (bromfenac sodium) drugs. The incorporation of N-(2-aminopropyl) methacrylamide (APMA) increased the drug uptake and improved the in vitro release kinetics. Imprinting with bromfenac resulted in a decreased drug release due to permanent drug bonding, while imprinting with dexamethasone increased the amount of dexamethasone released after dual-drug loading. The application of a mathematical model to predict the in vivo drug release behavior suggests the feasibility of achieving therapeutic drug concentrations of bromfenac and dexamethasone in the aqueous humor for about 2 and 8 weeks, respectively, which is compatible with the current topical prophylaxis after cataract surgeryThis project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie SkƂodowska-Curie grant agreement N° 813440 (OR-BITAL—Ocular Research by Integrated Training and Learning) and is also supported by Fundação para a CiĂȘncia e Tecnologia (FCT) [UID/QUI/00100/2019, UIDB/00100/2020, and UID/BIM/04585/2020].S

    Atorvastatin-Eluting Contact Lenses: Effects of Molecular Imprinting and Sterilization on Drug Loading and Release

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    Statins are receiving increasing attention in the ophthalmic field. Their activity as 3-hydroxy-3-methylglutaryl–CoA (HMG–CoA) reductase inhibitors is clinically used to regulate cholesterol levels and leads to pleiotropic effects, which may help in the management of diabetes-related ocular pathologies. This work aims to design bioinspired contact lenses (CLs) with an affinity for atorvastatin by mimicking the active site of HMG–CoA reductase. Sets of imprinted and nonimprinted 2-hydroxyethyl methacrylate (HEMA) hydrogels were synthesized, varying the contents in functional monomers that bear chemical groups that resemble those present in HMG–CoA reductase, namely, ethylene glycol phenyl ether methacrylate (EGPEM), 2-aminoethyl methacrylate hydrochloride (AEMA), and N-(3-aminopropyl) methacrylamide hydrochloride (APMA). The hydrogels were characterized in terms of suitability as CLs (solvent uptake, light transmission, mechanical properties, and biocompatibility) and capability to load and release atorvastatin. Three sterilization protocols (steam heat, gamma radiation, and high hydrostatic pressure) were implemented and their effects on hydrogel properties were evaluated. Copolymerization of AEMA and, particularly, APMA endowed the hydrogels with a high affinity for atorvastatin (up to 11 mg/g; KN/W > 200). Only high hydrostatic pressure sterilization preserved atorvastatin stability and hydrogel performance. Permeability studies through the porcine cornea and sclera tissues revealed that the amount of atorvastatin accumulated in the cornea and sclera could be effective to treat ocular surface diseasesThis project is funded by the European Union’s Horizon 2020 research and innovation program under the Marie SkƂodowska-Curie Actions grant agreement N° 813440 (ORBITAL–Ocular Research by Integrated Training and Learning). The work was also partially supported by MINECO [SAF2017-83118-R], Agencia Estatal de InvestigaciĂłn (AEI) Spain, Xunta de Galicia [ED431C 2020/17], FEDER and by Fundação para a CiĂȘncia e a Tecnologia (FCT, Portugal) [UIDB/00100/2020]. M. Vivero-Lopez acknowledges Xunta de Galicia (ConsellerĂ­a de Cultura, EducaciĂłn e OrdenaciĂłn Universitaria) for a predoctoral research fellowship [ED481A-2019/120]S

    Resveratrol-Loaded Hydrogel Contact Lenses with Antioxidant and Antibiofilm Performance

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    Contact lenses (CLs) are prone to biofilm formation, which may cause severe ocular infections. Since the use of antibiotics is associated with resistance concerns, here, two alternative strategies were evaluated to endow CLs with antibiofilm features: copolymerization with the antifouling monomer 2-methacryloyloxyethyl phosphorylcholine (MPC) and loading of the antioxidant resveratrol with known antibacterial activity. MPC has, so far, been used to increase water retention on the CL surface (ProclearÂź 1 day CLs). Both poly(hydroxyethyl methacrylate) (HEMA) and silicone hydrogels were prepared with MPC covering a wide range of concentrations (from 0 to 101 mM). All hydrogels showed physical properties adequate for CLs and successfully passed the hen’s egg-chorioallantoic membrane (HET-CAM) test. Silicone hydrogels had stronger affinity for resveratrol, with higher loading and a slower release rate. Ex vivo cornea and sclera permeability tests revealed that resveratrol released from the hydrogels readily accumulated in both tissues but did not cross through. The antibiofilm tests against Pseudomonas aeruginosa and Staphylococcus aureus evidenced that, in general, resveratrol decreased biofilm formation, which correlated with its concentration-dependent antibacterial capability. Preferential adsorption of lysozyme, compared to albumin, might also contribute to the antimicrobial activity. In addition, importantly, the loading of resveratrol in the hydrogels preserved the antioxidant activity, even against photodegradation. Overall, the designed hydrogels can host therapeutically relevant amounts of resveratrol to be sustainedly released on the eye, providing antibiofilm and antioxidant performanceThis research was funded by MINECO (SAF2017-83118-R), Agencia Estatal de InvestigaciĂłn (AEI) Spain, Xunta de Galicia (ED431C 2020/17), FEDER, and Fundação para a CiĂȘncia e Tecnologia (FCT) Portugal (UIDB/00100/2020 and UIDB/04585/2020). M. Vivero-Lopez acknowledges Xunta de Galicia (ConsellerĂ­a de Cultura, EducaciĂłn e OrdenaciĂłn Universitaria) for a predoctoral research fellowship (ED481A-2019/120)S

    Oral health and non communicable diseases in patients of a higher education institution, Montevideo, Uruguay 2016

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    Determinar la prevalencia ENT y sus factores de riesgo conductuales y metabĂłlicos en personas que concurrieron a la Facultad de OdontologĂ­a de la Universidad de la RepĂșblica. Estudio transversal en el que se aplicĂł un cuestionario sobre caracterĂ­sticas sociodemogrĂĄficas y hĂĄbitos vinculados a factores de riesgo comportamentales. Se realizaron mediciones antropomĂ©tricas, de presiĂłn arterial y glicemia capilar
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