Role of cerebrospinal fluid in carrying melatonin to its central target sites

Through the duration of its nocturnal secretion, melatonin is the primary transducer of photoperiodic information to the reproductive axis in seasonal breeders. In this review, we describe recent results supporting the hypothesis that melatonin, released by the pineal gland, reaches its central targets carried by cerebrospinal fluid (CSF), rather than blood. Firstly, melatonin is released in the CSF through a specific site in the pineal recess where protruding pinealocytes contact with the CSF. Consequently, melatonin is present in much higher concentrations (100 times), in the cerebrospinal fluid (CSF) than in the blood. Secondly, CSF melatonin diffuses in the brain tissues quickly and efficiently and thus reaches periventricular structures featuring 2-iodomelatonin binding sites. These data support the idea that CSF melatonin acts as a physiological signal for the brainLa mélatonine, par sa durée nocturne de sécrétion, traduit les effets de la photopériode sur la reproduction. Dans cette revue, nous décrivons des résultats récents qui étayent l'hypothèse selon laquelle la mélatonine est transportée de la glande pinéale vers ses cibles cérébrales par le liquide céphalo-rachidien (LCR), plutôt que par le sang. Premièrement, la mélatonine est libérée dans le LCR en un site spécifique dans le recessus pinéalien où des pinéalocytes sont en contact direct avec le LCR. En conséquence, la mélatonine est présente à des concentrations environ 100 fois plus élevées dans le LCR que dans le sang. Deuxièmement, la mélatonine du LCR est capable de diffuser dans les tissus cérébraux rapidement et efficacement et peut donc atteindre des structures périventriculaires dans lesquelles des sites de liaison à la 2-iodomélatonine sont présents. L'ensemble de ces données conforte l'idée que la mélatonine du LCR est un signal physiologique pour le cerveau

A nanoparticle ink allowing the high precision visualization of tissue engineered scaffolds by MRI

Hydrogels are widely used as cell scaffolds in several biomedical applications. Once implanted in vivo, cell scaffolds must often be visualized, and monitored overtime. However, cell scaffolds appear poorly contrasted in most biomedical imaging modalities such as magnetic resonance imaging (MRI). MRI is the imaging technique of choice for high-resolution visualization of low-density, water-rich tissues. Attempts to enhance hydrogel contrast in MRI are performed with “negative” contrast agents that produce several image artifacts impeding the delineation of the implant’s contours. In this study, a magnetic ink based on ultra-small iron oxide nanoparticles (USPIONs; <5 nm diameter cores) is developed and integrated into biocompatible alginate hydrogel used in cell scaffolding applications. Relaxometric properties of the magnetic hydrogel are measured, as well as biocompatibility and MR-visibility (T1-weighted mode; in vitro and in vivo). A 2-week MR follow-up study is performed in the mouse model, demonstrating no image artifacts, and the retention of “positive” contrast overtime, which allows very precise delineation of tissue grafts with MRI. Finally, a 3D-contouring procedure developed to facilitate graft delineation and geometrical conformity assessment is applied on an inverted template alginate pore network. This proof-of-concept establishes the possibility to reveal precisely engineered hydrogel structures using this USPIONs ink high-visibility approach

Biology and dynamics of potential malaria vectors in Southern France

BACKGROUND: Malaria is a former endemic problem in the Camargue, South East France, an area from where very few recent data concerning Anopheles are available. A study was undertaken in 2005 to establish potential malaria vector biology and dynamics and evaluate the risk of malaria re-emergence. METHODS: Mosquitoes were collected in two study areas, from March to October 2005, one week every two weeks, using light traps+CO(2), horse bait traps, human bait catch, and by collecting females in resting sites. RESULTS: Anopheles hyrcanus was the most abundant Anopheles species. Anopheles melanoon was less abundant, and Anopheles atroparvus and Anopheles algeriensis were rare. Anopheles hyrcanus and An. melanoon were present in summer, whereas An. atroparvus was present in autumn and winter. A large number of An. hyrcanus females was collected on humans, whereas almost exclusively animals attracted An. melanoon. Based on an enzyme-linked immunosorbent assay, almost 90% of An. melanoon blood meals analysed had been taken on horse or bovine. Anopheles hyrcanus and An. melanoon parity rates showed huge variations according to the date and the trapping method. CONCLUSION: Anopheles hyrcanus seems to be the only Culicidae likely to play a role in malaria transmission in the Camargue, as it is abundant and anthropophilic

Antibiotic research and development: business as usual?

This article contends that poor economic incentives are an important reason for the lack of new drugs and explains how the DRIVE-AB intends to change the landscape by harnessing the expertise, motivation and diversity of its partner

La filiacion y la fecundacion "in vitro"

Las tecnicas de reproduccion asistida no solo representan una solucion para ayudar a superar problemas de esterilidad, sino que su practica conlleva problemas eticos y juridicos. Esta Tesis analiza los problemas que plantea la fecundacion "in vitro", desde el punto de vista de la filiacion, para determinar la paternidad y maternidad cuando se utilizan los gametos de la pareja o de un tercero. Desde este punto de vista, se estudian la situacion juridica del tercero -llamado donante- y de las madres subrogadas, asi como las acciones de filiacion Tambien se examina la problematica que plantea la congelacion de semen y embriones, al poder un hombre engendrar un hijo despues de muerto. Entre las fuentes que se analizan estan los principales informes extranjeros que han estudiado la problematica de estas tecnicas, asi como el Informe especial de..

Mode d'action de la mélatonine sur le système nerveux central (distribution par le liquide cérébrospinal et caractérisation d'un nouveau site de liaison mélatoninergique exprimé dans les régions périventriculaires)

Melatonin, a hormone secreted at night by the pineal gland, is found in the blood and the cerebrospinal fluid, where its concentrations are 20 times as high as in the blood. Firstly, we studied the implication of the cerebrospinal fluid in providing the brain with melatonin and secondly, we characterised a new 2-[125I]-melatonin binding site. The assessment of tissue melatonin content and of the penetration of the 2-[123I]-melatonin from the cerebrospinal fluid into the brain by in vivo scintigraphy lead to the conclusion that melatonin is present in the brain and that the cerebrospinal fluid contributes highly to the presence of the hormone. Characterisation of the new melatoninergic binding site, named mtx, revealed a new pharmacological profile, with among other things melatoninergic and serotoninergic components.La mélatonine, hormone sécrétée la nuit par la glande pinéale, est présente dans le sang et le liquide cérébrospinal, où ses concentrations son 20 fois supérieures à celles du sang. Nous avons d'une part étudié l'implication du liquide cérébrospinal dans l apport de mélatonine dans le cerveau, et d'autre part caractérisé un nouveau site de liaison à la 2-[125I]-mélatonine. Par dosage des contenus tissulaires de mélatonine et par le suivi, par scintigraphie in vivo, du passage de la 2-[123I]-mélatonine du liquide cérébrospinal vers le tissu cérébral, nous avons démontré que la mélatonine est présente dans le cerveau et que le liquide cérébrospinal contribue fortement à la présence de l'hormone. La caractérisation du nouveau site de liaison mélatoninergique, nommé mtx, a mis en évidence un profil pharmacologique original, avec entre autres une composante mélatoninergique et sérotoninergique.TOURS-BU Sciences Pharmacie (372612104) / SudocSudocFranceF

Regulating the Poverty of Roma Migrants: the French, Italian, and Spanish Cases

contribution à un site webFirst lines: Generally speaking, the presence of foreigners in precarious situations appears to be a recurring problem for local governments. More than the difficulties encountered by migrants, it is the “vision of foreign poverty” that raises concerns(1). Public officials therefore often pursue interventions that oscillate between conditional integration and “expulsion”. While these policies are fairly well documented, their medium and long-term effects remain obscure.Yet these policies, combining acts of rejection (evacuation of shantytowns, expulsion of people) with local housing and inclusion policy instruments, have serious consequences on the lives of the people concerned. Drawing on this observation, we undertook a research project* aiming to study these effects by examining the case of Roma migrants in French, Italian and Spanish cities

Regulating the Poverty of Roma Migrants: the French, Italian, and Spanish Cases

contribution à un site webFirst lines: Generally speaking, the presence of foreigners in precarious situations appears to be a recurring problem for local governments. More than the difficulties encountered by migrants, it is the “vision of foreign poverty” that raises concerns(1). Public officials therefore often pursue interventions that oscillate between conditional integration and “expulsion”. While these policies are fairly well documented, their medium and long-term effects remain obscure.Yet these policies, combining acts of rejection (evacuation of shantytowns, expulsion of people) with local housing and inclusion policy instruments, have serious consequences on the lives of the people concerned. Drawing on this observation, we undertook a research project* aiming to study these effects by examining the case of Roma migrants in French, Italian and Spanish cities

Experimental characterization of the different nitrogen dilution effects on soot formation in ethylene diffusion flames

International audienceThis paper addresses the discrimination of dilution and thermal effects on soot production when nitrogen is added to the fuel stream of a steady laminar ethylene diffusion flame. In this context, the mixture-strength flame height Hf and visible flame height Hv are unambiguously documented and exhibit opposite trends within experimental diluted range (N2 volume fraction from 0 to 0.56). Simultaneous soot volume fraction and temperature fields are mapped for different N2 volume fractions by the Modulated Absorption/Emission (MAE) technique. Two characteristic flame heights and the temperature at the peak soot volume fraction are shown to be crucial parameters to assess the extent of the dilution and thermal effects together with their impact on soot formation in the flame. As a result, the mixture-strength flame height is proposed to characterize the soot formation rate within soot growth region, while the visible flame height is more appropriate to describe the overall sooting propensity in the flame. The probed soot temperature is recommended as the characteristic temperature to assess N2 dilution and thermal effects since the thermal effect is overestimated when using the adiabatic temperature

Fièvre de la vallée du Rift : diagnostic d'une arbovirose peu classique en France métropolitaine, à ne pas méconnaître !

International audienc