960 research outputs found

    Circadian rhythm dysfunction in glaucoma: A hypothesis

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    The absence of circadian zeitgebers in the social environment causes circadian misalignment, which is often associated with sleep disturbances. Circadian misalignment, defined as a mismatch between the sleep-wake cycle and the timing of the circadian system, can occur either because of inadequate exposure to the light-dark cycle, the most important synchronizer of the circadian system, or reduction in light transmission resulting from ophthalmic diseases (e.g., senile miosis, cataract, diabetic retinopathy, macular degeneration, retinitis pigmentosa, and glaucoma). We propose that glaucoma may be the primary ocular disease that directly compromises photic input to the circadian time-keeping system because of inherent ganglion cell death. Glaucomatous damage to the ganglion cell layer might be particularly harmful to melanopsin. According to histologic and circadian data, a subset of intrinsically photoresponsive retinal ganglion cells, expressing melanopsin and cryptochromes, entrain the endogenous circadian system via transduction of photic input to the thalamus, projecting either to the suprachiasmatic nucleus or the lateral geniculate nucleus. Glaucoma provides a unique opportunity to explore whether in fact light transmission to the circadian system is compromised as a result of ganglion cell loss

    Immunosuppressant drugs and quality-of-life outcomes in kidney transplant recipients: An international cohort study (EU-TRAIN)

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    Immunosuppressant; Quality of life; TransplantationImmunosupressor; Qualitat de vida; TrasplantamentInmunosupresor; Calidad de vida; TrasplanteIntroduction: Patient-Reported Outcomes (PRO) integrate a wide range of holistic dimensions that arenot captured within clinical outcomes. Particularly, from induction treatment to maintenance therapy, patient quality-of-life (QoL) of kidney transplant recipients have been sparsely investigated in international settings. Methods: In a prospective, multi-centric cohort study, including nine transplant centers in four countries, we explored the QoL during the year following transplantation using validated elicitation instruments (EQ-5D-3L index with VAS) in a population of kidney transplant patients receiving immunosuppressive therapies. Calcineurin inhibitors (tacrolimus and ciclosporin), IMPD inhibitor (mycophenolate mofetil), and mTOR inhibitors (everolimus and sirolimus) were the standard-of-care (SOC) medications, together with tapering glucocorticoid therapy. We used EQ-5D and VAS data as QoL measures alongside descriptive statistics at inclusion, per country and hospital center. We computed the proportions of patients with different immunosuppressive therapy patterns, and using bivariate and multivariate analyses, assessed the variations of EQ-5D and VAS between baseline (i.e., inclusion Month 0) and follow up visits (Month 12). Results: Among 542 kidney transplant patients included and followed from November 2018 to June 2021, 491 filled at least one QoL questionnaire at least at baseline (Month 0). The majority of patients in all countries received tacrolimus and mycophenolate mofetil, ranging from 90.0% in Switzerland and Spain to 95.8% in Germany. At M12, a significant proportion of patients switched immunosuppressive drugs, with proportion varying from 20% in Germany to 40% in Spain and Switzerland. At visit M12, patients who kept SOC therapy had higher EQ-5D (by 8 percentage points, p < 0.05) and VAS (by 4 percentage points, p < 0.1) scores than switchers. VAS scores were generally lower than EQ-5D (mean 0.68 [0.5–0.8] vs. 0.85 [0.8–1]). Discussion: Although overall a positive trend in QoL was observed, the formal analyses did not show any significant improvements in EQ-5D scores or VAS. Only when the effect of a therapy use was separated from the effect of switching, the VAS score was significantly worse for switchers during the follow up period, irrespective of the therapy type. If adjusted for patient characteristics and medical history (e.g., gender, BMI, eGRF, history of diabetes), VAS and EQ-5D delivered sound PRO measures for QoL assessments during the year following renal transplantation.The project has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No 754995. Open access funding by University of Lausanne

    Self-Reported Sleep Latency in Postmenopausal Women

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    The ain of this study was to access how self-reported sleep latency (SRSL) was affected by sleep habits, mood, and circadian rhythm in postmenopausal women. Subjects (n=384, 67.9±7.7 yr) completed sleep and mood questionnaires, sleep log and actigraphic data. The major urinary melatonin metabolite (6-sulphatoxymelatonin, aMT6s) was assayed in fractional urine specimens for two 24-hr intervals. Although SRSL (26.5±24.4 min) and actigraphic sleep latency (ASL; 27.8±20.0 min) were correlated (rs=0.361, p<0.001), the short SRSLs tended to be underestimated whereas the long SRSLs tended to be overestimated as compared to ASL. SRSL was positively correlated with the scales of insomnia, mood and hot flash, hypertension, use of anti-hypertensive drugs and the acrophase and the offset of aMT6s. SRSL was negatively correlated with the global assessment of functioning scale in DSM-IV (GAF scale), and light exposure and wrist activity. Multiple linear regression analysis showed that the best-fit model to predict SRSL was light exposure, GAF scale, and use of anti-hypertensive drugs. SRSL may be determined by psychophysiological factors as well as circadian rhythm function. Therapeutic approaches suggested for trouble falling asleep might include increased daylight exposure, improvements in general health, and modification of anti-hypertensive pharmacotherapy

    Effect of a legume cover crop on carbon storage and erosion in an ultisol under maize cultivation in southern Benin

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    Field experiment was conducted from 1988 to 1999 at an experimental farm at Agonkanmey, near Cotonou in southern Benin, to study the effect of relay-cropping maize through Mucuna pruriens (var. utilis). The relay-cropping system was compared with traditional maize cropping system without any input, and with a maize cropping system with mineral fertilizers (NPK). Special attention was given on the changes in soil C during the period of the experiment in relation to residue biomass C returned to the soil, runoff and soil erosion losses, and loss of C with erosion. The soils are classified as sandy loam Typic Kandiustult. The general properties of these soils are given. For this soil type, relay cropping of maize and mucuna was very effective in enhancing C sequestration: change in Ct (total C content) stock for 0 to 40 cm depth was 1.3 t C/ha per year over the 12-year period of the experiment, ranging among the highest rates recorded for the eco-region. This increase resulted first from the high amount of residue biomass provided by mucuna, which amounted to 10 t DM/ha per year (83% aboveground). Mucuna residues, supplying the soil with N, also favoured the production of maize biomass, and total mucuna plus maize residue biomass returned to the soil was approximately 20 t/ha per year. In contrast, non-fertilized and fertilized continuous maize cultivation resulted in -0.2 and 0.2 t C/ha per year change in Ct stock for 0 to 40 cm depth, respectively. Total residue biomass was 8 and 13 t/ha per year, including 77 and 29% by weeds, respectively. Thick mulch produced by mucuna decreased losses by runoff and erosion, which were 0.28, 0.12 and 0.08 mm/mm and 34.0, 9.0 and 3.0 t/ha per year in unfertilized, fertilized with NPK and mucuna treatments, respectively. Eroded C was estimated at 0.3, 0.1 and 1.0 t C/ha per year in unfertilized, fertilized with NPK and mucuna treatments, respectively. Through its benefits on soil organic matter management, weed suppression and erosion control, cropping systems including a legume crop may have an adverse impact from a global change standpoint

    Effect of a legume cover crop (Mucuna pruriens var. utilis) on soil carbon in an ultisol under maize cultivation in southern Benin

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    Long term fallow is no longer possible in densely populated tropical areas, but legume cover crops can help maintain soil fertility. Our work aimed to study changes in soil carbon in a sandy loam Ultisol in Benin, which involved a 12-year experiment on three maize cropping systems under manual tillage: traditional no-input cultivation (T), mineral fertilized cultivation (NPK), and association with Mucuna pruriens (M). The origin of soil carbon was also determined through the natural abundance of soil and biomass C-13. In T, NPK and M changes in soil carbon at 0-40 cm were -0.2, +0.2 and +1.3 t C ha(-1) yr(-1), with residue carbon amounting to 3.5, 6.4 and 10.0 t C ha(-1) yr(-1), respectively. After 12 years of experimentation, carbon originating from maize in litter-plus-soil (0-40 cm) represented less than 4% of both total carbon and overall maize residue carbon. In contrast, carbon originating from mucuna in litter-plus-soil represented more than 50% of both total carbon and overall mucuna residue carbon in M, possibly due to accelerated mineralization of native soil carbon (priming effect) and slow mulch decomposition. Carbon originating from weeds in litter-plus-soil represented c. 10% of both total carbon and overall weed residue carbon in T and NPK. Thus mucuna mulch was very effective in promoting carbon sequestration in the soil studied

    A De Facto Asian-Currency Unit Bloc in East Asia: It has Been There but We did not Look for It

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    Pegging in a coordinated way to a regional basket currency is considered by many as optimal for east-Asian countries. By contrast, according to existing empirical studies, these countries have most often relied on noncooperative United States dollar or G3 pegs. We show for the first time that by the late 1990s, with some reversals, a majority of east-Asian countries had already moved, de facto, away from the dollar peg and started targeting a basket, including east-Asian currencies (an Asian Currency Unit). Common-shock or market-based interpretations of such moves are ruled out since we document that, with few exceptions, countries in the region have in reality stuck to fixed exchange rates. We obtain such results using a Markov-switching estimation benchmarked against Bai-Perron structural break tests for the synthesis model of Frankel and Wei (2007), which augments the inference about currency weights in a basket with the weight on exchange-market pressure. In order to measure the latter, the forward positions of central banks in the foreign exchange market are taken into account

    Design of AB5-AB5´ alloy mixtures applied to hidrogen compression

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    El estudio de las propiedades estructurales y de interacción con hidrógeno de compuestos tipo AB5 se ha vuelto de interés actual debido a su aplicación en dispositivos de compresión térmica de este fluido. En este trabajo, se discuten y se analizan los datos experimentales de sorción de hidrógeno de la mezcla La0.68Ce0.18Nd0.08Pr0.06Ni5 –LaNi5 en función de esta aplicación. Se obtuvieron las condiciones experimentales para el funcionamiento de un compresor térmico de una etapa con una relación final de compresión de 3.80. A partir de las mismas, se calcularon los valores de ΔH y ΔS de formación y descomposición del hidruro para el sistema AB5-AB5´-H2 en el rango de temperaturas entre 25 ºC y 90 ºC.The study of the structural and sorption properties of AB5 compounds are of current interest due to its application to thermal hydrogen compression devices. In this work, the experimental sorption of hydrogen by a La0.68Ce0.18Nd0.08Pr0.06Ni5-LaNi5 mixture is discussed in relation to this application. The experimental conditions for a one stage thermal compressor were obtained. A final compression relationship of 3.80 was achieved. From these data, the ΔH and ΔS values corresponding to the hydride formation/decomposition in the AB5-AB5´-H2 system were obtained for the 25 to 90 ºC range.Facultad de Ciencias Exacta

    Design of AB5-AB5´ alloy mixtures applied to hidrogen compression

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    El estudio de las propiedades estructurales y de interacción con hidrógeno de compuestos tipo AB5 se ha vuelto de interés actual debido a su aplicación en dispositivos de compresión térmica de este fluido. En este trabajo, se discuten y se analizan los datos experimentales de sorción de hidrógeno de la mezcla La0.68Ce0.18Nd0.08Pr0.06Ni5 –LaNi5 en función de esta aplicación. Se obtuvieron las condiciones experimentales para el funcionamiento de un compresor térmico de una etapa con una relación final de compresión de 3.80. A partir de las mismas, se calcularon los valores de ΔH y ΔS de formación y descomposición del hidruro para el sistema AB5-AB5´-H2 en el rango de temperaturas entre 25 ºC y 90 ºC.The study of the structural and sorption properties of AB5 compounds are of current interest due to its application to thermal hydrogen compression devices. In this work, the experimental sorption of hydrogen by a La0.68Ce0.18Nd0.08Pr0.06Ni5-LaNi5 mixture is discussed in relation to this application. The experimental conditions for a one stage thermal compressor were obtained. A final compression relationship of 3.80 was achieved. From these data, the ΔH and ΔS values corresponding to the hydride formation/decomposition in the AB5-AB5´-H2 system were obtained for the 25 to 90 ºC range.Facultad de Ciencias Exacta

    Litter removal in a tropical rain forest reduces fine root biomass and production but litter addition has few effects.

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    Many old-growth lowland tropical rain forests are potentially nutrient limited, and it has long been thought that many such forests maintain growth by recycling nutrients from decomposing litter. We investigated this by continuously removing (for 10 yr) freshly fallen litter from five (45 m × 45 m) plots, adding it to five other plots, there were five controls. From monthly measures over 1 yr we show that litter removal caused lower: fine root (≤2 mm diameter) standing mass, fine root standing length, fine root length production and fine root length survivorship. Litter addition did not significantly change fine root mass or length or production. Nutrient concentrations in fine roots in litter removal plots were lower than those in controls for nitrogen (N), calcium (Ca) and magnesium (Mg), concentrations in fine roots in litter addition plots were higher for N and Ca. Chronic litter removal has resulted in reduced forest growth due to lack of nutrients, probably nitrogen. Conversely, long-term litter addition has had fewer effects
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