The unconventional
-methyl-d-aspartate (NMDA) receptor subunits GluN3A and GluN3B can, when associated with the other glycine-binding subunit GluN1, generate excitatory conductances purely activated ...by glycine. However, functional GluN1/GluN3 receptors have not been identified in native adult tissues. We discovered that GluN1/GluN3A receptors are operational in neurons of the mouse adult medial habenula (MHb), an epithalamic area controlling aversive physiological states. In the absence of glycinergic neuronal specializations in the MHb, glial cells tuned neuronal activity via GluN1/GluN3A receptors. Reducing GluN1/GluN3A receptor levels in the MHb prevented place-aversion conditioning. Our study extends the physiological and behavioral implications of glycine by demonstrating its control of negatively valued emotional associations via excitatory glycinergic NMDA receptors.
•The anelastic and dielectric spectra of MAPbI3 and FAPbI3 clarify the nature of their structural phase transitions.•The cubic to tetragonal phase transition is mainly driven by tilting of the ...relatively rigid PbI6 octahedra.•The transition to the orthorhombic phase is driven by blocking of the MA/FA rotation, followed by anelastic relaxation of MA.
The metal-organic halide perovskites may have excellent photovoltaic properties, useful to create cheap and efficient solar cells, photodetectors and LEDs with a wide range of colors. Great efforts are spent for improving their scarce stability and clarifying the mechanisms that allow the photocarriers to have so long lifetimes. These phenomena are closely connected to the structural transformations and to the dynamics of the reorienting organic cations, both of which can be studied by anelastic measurements, here combined with dielectric spectroscopy. The complex dynamic Young’s modulus and permittivity of MAPI and FAPI have been measured on samples obtained by pressing the powders into bars or disks. Both perovskites are cubic at and above room temperature (α phase), with freely rotating FA and MA cations, and undergo two tilt transitions of the PbI6 octahedra into a tetragonal (β) and orthorhombic (γ) phase, accompanied by losses of the orientational degrees of freedom of the MA and FA molecular cations. These α → β and β → γ transitions are accompanied respectively by sharp softening and stiffening of the Young’s modulus, while the permittivity has a major drop from a paraelectric rise at the β → γ transition of MAPI and is practically flat everywhere in FAPI. From these behaviors we argue that the α∕β transition is mainly due to octahedral tilting while the latter to the blocking of MA/FA reorientational modes linearly coupled with strain. Comparisons are made with elastic anomalies found in other hybrid 3D and layered perovskites.
Zinc at glutamatergic synapses Paoletti, P; Vergnano, A.M; Barbour, B ...
Neuroscience,
01/2009, Volume:
158, Issue:
1
Journal Article
Peer reviewed
Abstract It has long been known that the mammalian forebrain contains a subset of glutamatergic neurons that sequester zinc in their synaptic vesicles. This zinc may be released into the synaptic ...cleft upon neuronal activity. Extracellular zinc has the potential to interact with and modulate many different synaptic targets, including glutamate receptors and transporters. Among these targets, NMDA receptors appear particularly interesting because certain NMDA receptor subtypes (those containing the NR2A subunit) contain allosteric sites exquisitely sensitive to extracellular zinc. The existence of these high-affinity zinc binding sites raises the possibility that zinc may act both in a phasic and tonic mode. Changes in zinc concentration and subcellular zinc distribution have also been described in several pathological conditions linked to glutamatergic transmission dysfunctions. However, despite intense investigation, the functional significance of vesicular zinc remains largely a mystery. In this review, we present the anatomy and the physiology of the glutamatergic zinc-containing synapse. Particular emphasis is put on the molecular and cellular mechanisms underlying the putative roles of zinc as a messenger involved in excitatory synaptic transmission and plasticity. We also highlight the many controversial issues and unanswered questions. Finally, we present and compare two widely used zinc chelators, CaEDTA and tricine, and show why tricine should be preferred to CaEDTA when studying fast transient zinc elevations as may occur during synaptic activity.
Larval dispersal and juvenile survival are crucial in determining variation in recruitment, stock size and adult distribution of commercially important fish. This study investigates the dispersal of ...early-life stages of common sole (Solea solea L.) in the southern North Sea, both empirically and through modeling. Age at different life-history events of juvenile flatfish sampled along the coasts of Belgium, the Netherlands and the United Kingdom in 2013, 2014 and 2016, was determined through the counting of daily growth rings in the otoliths. Juveniles captured between August and October were estimated to be on average 140 days old with an average pelagic larval duration of 34 days. The hatching period was estimated between early April and mid-May followed by arrival and settlement in the nurseries between May and mid-June. Growth rates were higher off the Belgian coast than in the other nursery areas, especially in 2013, possibly due to a post-settlement differentiation. Empirical pelagic larval duration and settlement distributions were compared with the Larvae&Co larval dispersal model, which combines local hydrodynamics in the North Sea with sole larval behavior. Yearly predicted and observed settlement matched partially, but the model estimated a longer pelagic phase. The observations fitted even better with the modelled average (1995-2015) distribution curves. Aberrant results for the small juvenile sole sampled along the UK coast in March 2016, led to the hypothesis of a winter disruption in the deposition of daily growth rings, potentially related to starvation and lower food availability. The similarities between measured and modelled distribution curves cross-validated both types of estimations and accredited daily ageing of juveniles as a useful method to calibrate biophysical models and to understand early-life history of fish, both important tools in support of efficient fisheries management strategies.
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An emerging strategy to improve adhesiveness of biomaterials in wet conditions takes inspiration from the adhesive features of marine mussel, which reside in the chemical reactivity ...of catechols. In this work, a catechol-bearing molecule (dopamine) was chemically grafted onto alginate to develop a polysaccharide-based membrane with improved adhesive properties. The dopamine-modified alginates were characterized by NMR, UV spectroscopy and in vitro biocompatibility. Mechanical tests and in vitro adhesion studies pointed out the effects of the grafted dopamine within the membranes. The release of HA from these resorbable membranes was shown to stimulate fibroblasts activities (in vitro). Finally, a preliminary in vivo test was performed to evaluate the adhesiveness of the membrane on porcine intestine (serosa). Overall, this functionalized membrane was shown to be biocompatible and to possess considerable adhesive properties owing to the presence of dopamine residues grafted on the alginate backbone.
This article describes the development of a mussels-inspired strategy for the development of an adhesive polysaccharide-based membrane for wound healing applications. Bioadhesion was achieved by grafting dopamine moieties on the structural component on the membrane (alginate): this novel biomaterial showed improved adhesiveness to the intestinal tissue, which was demonstrated by both in vitro and in vivo studies. Overall, this study points out how this nature-inspired strategy may be successfully exploited for the development of novel engineered biomaterials with enhanced bioadhesion, thus opening for novel applications in the field of general surgery.
Over the past 20 years, the focus of forest science on air pollution has moved from forest decline to a holistic framework of forest health, and from the effects on forest production to the ecosystem ...services provided by forest ecosystems. Hence, future research should focus on the interacting factorial impacts and resulting antagonistic and synergistic responses of forest trees and ecosystems. The synergistic effects of air pollution and climatic changes, in particular elevated ozone, altered nitrogen, carbon and water availability, must be key issues for research. Present evidence suggests air pollution will become increasingly harmful to forests under climate change, which requires integration amongst various stressors (abiotic and biotic factors, including competition, parasites and fire), effects on forest services (production, biodiversity protection, soil protection, sustained water balance, socio-economical relevance) and assessment approaches (research, monitoring, modeling) to be fostered.
Interactions between air pollution and climate change effects on forest services demand long-term research approaches that integrate multi-factorial field experiments, monitoring and modeling.
•Sterilization of alginate membranes can be performed through scCO2.•The operating conditions can be tuned to limit the decrease of alginate Mw.•scCO2-sterilized membranes do not exert any adverse ...tissue reaction in vivo.
Sterilization methods such as ɣ-irradiation, steam sterilization and ethylene oxide gas treatment can have negative effects on molecular structure and properties of polysaccharide-based biomaterials. In this perspective, the use of supercritical carbon dioxide (scCO2) has been proposed as an alternative method for biomaterial sterilization. In this work, chemical, mechanical and biological properties of polysaccharidic membranes for surgical applications were investigated after sterilization by scCO2. Four sets of sterilizing conditions were considered and SEC analyses were performed in order to identify the one with lower impact on the polysaccharidic matrix of membranes (alginate). Mechanical tests showed that the resistance of membranes was slightly affected after sterilization. Biological analyses proved the biocompatibility of the sterilized membranes both in vitro and in a preliminary in vivo test. Overall, this study points out that this sterilization technique can be successfully employed to achieve an effective and safe sterilization of polysaccharidic membranes for surgical use.
The Italian Society of Contraception identified as one of its priorities the need to give recommendations on management of contraception during Coronavirus-Covid 19 pandemia
A concise communication ...was produced which summarises in an easy-to-read format suitable for clinicians the management of the different contraceptives mostly used. Information how to manage contraception in different conditions is presented.
Women may, in general, continue to use either intrauterine and or hormonal contraceptives. The use of condom should be added to any hormonal contraceptive, when the contraceptive efficacy is reduced or when women stop the contraceptive method.
At the present time, during the Coronavirus-Covid 19 pandemia, no data contraindicate the use of intrauterine or hormonal contraceptives. Conversely the use of an appropriate contraception is advocate to prevent unintended pregnancies.
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