Daily variation of visual sensitivity to luminance contrast: Effects of time of measurement and circadian typology

This study analyzed the fluctuation of the achromatic visual contrast sensitivity (CS) of adult males (M = 23.42 ± 2.6 years) during a daily period. Twenty-eight volunteers were divided into three groups according to circadian typology (CT): moderate morning (MM; n = 8); intermediate (I; n = 10) and moderate evening (ME; n = 10). The Pittsburgh Sleep Quality Index was used to evaluate sleep quality, and the Horne and Ostberg Morningness-Eveningness Questionnaire was used to measure CT. To measure CS, we used Metropsis software version 11.0 with vertical sinusoidal grids of 0.2, 0.6, 1, 3.1, 6.1, 8.8, 13.2 and 15.6 cycles per degree of visual angle (cpd). The stimuli were presented on a cathode ray tube (CRT) color video monitor with a 19-inch flat screen, a 1024 × 786 pixel resolution, a 100 Hz refresh rate and a photopic luminance of 39.6 cd/m². It was inferred that there is a tendency for visual contrast to vary according to daily rhythmicity and CT, mainly for the median spatial frequencies (1.0 cpd, χ² = 9.93, p < 0.05 and 3.1 cpd, χ² = 10.33, p < 0.05) and high spatial frequencies (13.2 cpd, χ² = 11.54, p < 0.05) of ME participants. ME participants had minimal visual contrast sensitivity during the morning shift and a progressive increase from afternoon to night.     

EMILIN1/α9β1 Integrin Interaction Is Crucial in Lymphatic Valve Formation and Maintenance

Lymphatic vasculature plays a crucial role in the maintenance of tissue interstitial fluid balance. The role of functional collecting lymphatic vessels in lymph transport has been recently highlighted in pathologies leading to lymphedema, for which treatments are currently unavailable. Intraluminal valves are of paramount importance in this process. However, valve formation and maturation have not been entirely elucidated yet, in particular, the role played by the extracellular matrix (ECM). We hypothesized that EMILIN1, an ECM multidomain glycoprotein, regulates lymphatic valve formation and maintenance. Using a mouse knockout model, we show that in the absence of EMILIN1, mice exhibit defects in lymphatic valve structure and in lymph flow. By applying morphometric in vitro and in vivo functional assays, we conclude that this impaired phenotype depends on the lack of α9β1 integrin engagement, the specific lymphatic endothelial cell receptor for EMILIN1, and the ensuing derangement of cell proliferation and migration. Our data demonstrate a fundamental role for EMILIN1-integrin α9 interaction in lymphatic vasculature, especially in lymphatic valve formation and maintenance, and underline the importance of this ECM component in displaying a regulatory function in proliferation and acting as a “guiding” molecule in migration of lymphatic endothelial cells.     

SIRT1 silencing confers neuroprotection through IGF‐1 pathway activation

The following study demonstrated that, in in vitro differentiated neurons, SIRT1 silencing induced an increase of IGF‐1 protein expression and secretion and of IGF‐1R protein levels which, in turn, prolonged neuronal cell survival in presence of an apoptotic insult. On the contrary, SIRT1 overexpression increased cell death. In particular, IGF‐1 and IGF‐1R expression levels were negatively regulated by SIRT1. In SIRT1 silenced cells, the increase in IGF‐1 and IGF‐1R expression was associated to an increase in AKT and ERK1/2 phosphorylation. Moreover, neuronal differentiation was reduced in SIRT1 overexpressing cells and increased in SIRT1 silenced cells. We conclude that SIRT1 silenced neurons appear more committed to differentiation and more resistant to cell death through the activation of IGF‐1 survival pathway. J. Cell. Physiol. 228: 1754–1761, 2013. © 2013 Wiley Periodicals, Inc.     

A New Online Database on Chemicals in Accordance with REACH Regulation

The need for comprehensive and reliable risk management of chemicals requires appropriate information, data integration, and sharing, as suggested in Europe by Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) regulation. REACH requires more sharing of responsibilities among authorities, chemical manufacturers, importers, and users to manage the risks that chemicals can pose to human health and the environment throughout their life cycle. This has obviously enlarged the audience of people who could be interested in gathering this information. A major bottleneck is that information sources on chemicals are frequently sparsely distributed, collected, and managed by different institutions, with different aims, resulting in several practical problems. This article describes the conceptual design and implementation of a free online access database (DESC) as an integrated information system on chemical substances in compliance with the REACH regulation. An interdisciplinary approach was applied by involving several experts from different disciplines (ecotoxicologists, chemists, information technology specialists, regulators). DESC contains relevant environmental and toxicological data (physico-chemical and ecotoxicological data, inclusion in priority lists, current classification and labeling, etc.) on more than 651 chemicals, which can be easily consulted by people with different degrees of expertise interested in knowing the risk from exposure to chemicals and their safe use.     

Synthesis and anti-HIV evaluation of new 2′,3′- dideoxy-3′-thiacytidine prodrugs

Abstract

A series of anti-HIV prodrugs possessing various polyaminated side arms have been developed. The incorporation of a N-Boc protected monoamine or diamine side arm into the backbone of the 2′,3′-dideoxy-3′-thiacytidine 1 (BCH-189) provided an increase in antiviral potency, which could be several orders magnitude greater than the parent drug (1) depending on the cell culture systems used (MT-4 or MDMs). Twenty six 2′,3′-dideoxy-3′-thiacytidine prodrugs which differ from each other by the length, the nature of the 5′-O function and the 5′-O or /and N-4 position on the nucleoside moiety were synthesized. Among this new series of prodrugs, several congeners (12c and 12a) were found to inhibit HIV-1 replication in cell culture with 50% effective concentrations ECso of 10 and 50 nM respectively, in MT-4 cells. Compound 12c was found more active on infected MDMs cells with 50% effective concentration of 0.01 nM. The synthesis and the antiviral properties of these compounds are discussed.     

An evaluation of manual and automated methods for detecting sounds of maned wolves (Chrysocyon brachyurus Illiger 1815)

Although bioacoustics is increasingly used to study species and environments for their monitoring and conservation, detecting calls produced by species of interest is prohibitively time consuming when done manually. Here we compared four methods for detecting and identifying roar-barks of maned wolves (Chrysocyon brachyurus) within long sound recordings: (1) a manual method, (2) an automated detector method using Raven Pro 1.4, (3) an automated detector method using XBAT and (4) a mixed method using XBAT's detector followed by manual verification. Recordings were done using a song meter installed at the Serra da Canastra National Park (Minas Gerais, Brazil). For each method we evaluated the following variables in a 24-h recording: (1) total time required analysing files, (2) number of false positives identified and (3) number of true positives identified compared to total number of target sounds. Automated methods required less time to analyse the recordings (77–93 min) when compared to manual method (189 min), but consistently presented more false positives and were less efficient in identifying true positives (manual = 91.89%, Raven = 32.43% and XBAT = 84.86%). Adding a manual verification after XBAT detection dramatically increased efficiency in identifying target sounds (XBAT+manual = 100% true positives). Manual verification of XBAT detections seems to be the best way out of the proposed methods to collect target sound data for studies where large amounts of audio data need to be analysed in a reasonable time (111 min, 58.73% of the time required to find calls manually).     

Cortical Reorganization after Hand Immobilization: The beta qEEG Spectral Coherence Evidences

There is increasing evidence that hand immobilization is associated with various changes in the brain. Indeed, beta band coherence is strongly related to motor act and sensitive stimuli. In this study we investigate the electrophysiological and cortical changes that occur when subjects are submitted to hand immobilization. We hypothesized that beta coherence oscillations act as a mechanism underlying inter- and intra-hemispheric changes. As a methodology for our study fifteen healthy individuals between the ages of 20 and 30 years were subjected to a right index finger task before and after hand immobilization while their brain activity pattern was recorded using quantitative electroencephalography. This analysis revealed that hand immobilization caused changes in frontal, central and parietal areas of the brain. The main findings showed a lower beta-2 band in frontal regions and greater cortical activity in central and parietal areas. In summary, the coherence increased in the frontal, central and parietal cortex, due to hand immobilization and it adjusted the brains functioning, which had been disrupted by the procedure. Moreover, the brain adaptation upon hand immobilization of the subjects involved inter- and intra-hemispheric changes.     

NLRP3 Controls Trypanosoma cruzi Infection through a Caspase-1-Dependent IL-1R-Independent NO Production

Trypanosoma cruzi (T. cruzi) is an intracellular protozoan parasite and the etiological agent of Chagas disease, a chronic infectious illness that affects millions of people worldwide. Although the role of TLR and Nod1 in the control of T. cruzi infection is well-established, the involvement of inflammasomes remains to be elucidated. Herein, we demonstrate for the first time that T. cruzi infection induces IL-1β production in an NLRP3- and caspase-1-dependent manner. Cathepsin B appears to be required for NLRP3 activation in response to infection with T. cruzi, as pharmacological inhibition of cathepsin B abrogates IL-1β secretion. NLRP3^−/− and caspase1^−/− mice exhibited high numbers of T. cruzi parasites, with a magnitude of peak parasitemia comparable to MyD88^−/− and iNOS^−/− mice (which are susceptible models for T. cruzi infection), indicating the involvement of NLRP3 inflammasome in the control of the acute phase of T. cruzi infection. Although the inflammatory cytokines IL-6 and IFN-γ were found in spleen cells from NLRP3^−/− and caspase1^−/− mice infected with T. cruzi, these mice exhibited severe defects in nitric oxide (NO) production and an impairment in macrophage-mediated parasite killing. Interestingly, neutralization of IL-1β and IL-18, and IL-1R genetic deficiency demonstrate that these cytokines have a minor effect on NO secretion and the capacity of macrophages to control T. cruzi infection. In contrast, inhibition of caspase-1 with z-YVAD-fmk abrogated NO production by WT and MyD88^−/− macrophages and rendered them as susceptible to T. cruzi infection as NLRP3^−/− and caspase-1^−/− macrophages. Taken together, our results demonstrate a role for the NLRP3 inflammasome in the control of T. cruzi infection and identify NLRP3-mediated, caspase-1-dependent and IL-1R-independent NO production as a novel effector mechanism for these innate receptors.     

Characterization of Adult Rat Astrocyte Cultures

Astrocytes, a major class of glial cells, regulate neurotransmitter systems, synaptic processing, ion homeostasis, antioxidant defenses and energy metabolism. Astrocyte cultures derived from rodent brains have been extensively used to characterize astrocytes'' biochemical, pharmacological and morphological properties. The aims of this study were to develop a protocol for routine preparation and to characterize a primary astrocyte culture from the brains of adult (90 days old) Wistar rats. For this we used enzymatic digestion (trypsin and papain) and mechanical dissociation. Medium exchange occurred from 24 h after obtaining a culture and after, twice a week up to reach the confluence (around the 4^th to 5^th week). Under basal conditions, adult astrocytes presented a polygonal to fusiform and flat morphology. Furthermore, approximately 95% the cells were positive for the main glial markers, including GFAP, glutamate transporters, glutamine synthetase and S100B. Moreover, the astrocytes were able to take up glucose and glutamate. Adult astrocytes were also able to respond to acute H₂O₂ exposure, which led to an increase in reactive oxygen species (ROS) levels and a decrease in glutamate uptake. The antioxidant compound resveratrol was able to protect adult astrocytes from oxidative damage. A response of adult astrocytes to an inflammatory stimulus with LPS was also observed. Changes in the actin cytoskeleton were induced in stimulated astrocytes, most likely by a mechanism dependent on MAPK and Rho A signaling pathways. Taken together, these findings indicate that the culture model described in this study exhibits the biochemical and physiological properties of astrocytes and may be useful for elucidating the mechanisms related to the adult brain, exploring changes between neonatal and adult astrocytes, as well as investigating compounds involved in cytotoxicity and cytoprotection.