Situating prehistoric sites in their past environment helps us to understand their functionality and the organization of early sedentary human societies. However, this is a challenge as the natural environment constantly evolves through time and erases these constructions, especially along riverbanks, thus biasing the archaeological record. This study introduces a reassessment of the paleo-landscape evolution around the Neolithic enclosures at the Noyen-sur-Seine site based on new field observations as well as the synthesis of (un)published and new radiocarbon dating.
View Article and Find Full Text PDFUnderstanding the geodynamic and Earth surface processes at the origin of post-collisional surface uplift in mountain ranges requires reconstruction of paleo-elevation. Here, we focus on the topographic evolution of the Cerdanya Basin in the eastern Pyrenees formed by post-orogenic extension during the Late Miocene. Stable isotope (δO) analyses of small rodent teeth and biogenic carbonates show the basin uplifted by 500 m since 6.
View Article and Find Full Text PDFThe astrocyte-specific enzyme glutamine synthetase (GS), which catalyzes the amidation of glutamate to glutamine, plays an essential role in supporting neurotransmission and in limiting NH toxicity. Accordingly, deficits in GS activity contribute to epilepsy and neurodegeneration. Despite its central role in brain physiology, the mechanisms that regulate GS activity are poorly defined.
View Article and Find Full Text PDFOxygen-isotope thermometry played a critical role in the rise of modern geochemistry and remains extensively used in (bio-)geoscience. Its theoretical foundations rest on the assumption that O/O partitioning among water and carbonate minerals primarily reflects thermodynamic equilibrium. However, after decades of research, there is no consensus on the true equilibrium O/O fractionation between calcite and water (α).
View Article and Find Full Text PDFGABAR-dependent activation of G protein-gated inwardly rectifying potassium channels (GIRK or K3) provides a well-known source of inhibition in the brain, but the details on how this important inhibitory pathway affects neural circuits are lacking. We used sorting nexin 27 (SNX27), an endosomal adaptor protein that associates with GIRK2c and GIRK3 subunits, to probe the role of GIRK channels in reward circuits. A conditional knockout of SNX27 in both substantia nigra pars compacta and ventral tegmental area (VTA) dopamine neurons leads to markedly smaller GABAR- and dopamine DR-activated GIRK currents, as well as to suprasensitivity to cocaine-induced locomotor sensitization.
View Article and Find Full Text PDFThe accumulation of γ-aminobutyric acid receptors (GABAARs) at the appropriate postsynaptic sites is critical for determining the efficacy of fast inhibitory neurotransmission. Although we know that the majority of synaptic GABAAR subtypes are assembled from α1-3, β, and γ2 subunits, our understanding of how neurons facilitate their targeting to and stabilization at inhibitory synapses is rudimentary. To address these issues, we have created knock-in mice in which the pH-sensitive green fluorescent protein (GFP) and the Myc epitope were introduced to the extracellular domain of the mature receptor α2 subunit (pHα2).
View Article and Find Full Text PDFEmerging evidence suggests that functional γ-aminobutyric acid B receptors (GABABRs) are expressed by astrocytes within the mammalian brain. GABABRs are heterodimeric G-protein-coupled receptors that are composed of R1/R2 subunits. To date, they have been characterized in neurons as the principal mediators of sustained inhibitory signaling; however their roles in astrocytic physiology have been ill defined.
View Article and Find Full Text PDFKainate receptors (KARs) are widely expressed in the brain and are present at both presynaptic and postsynaptic sites. GluK3-containing KARs are thought to compose presynaptic autoreceptors that facilitate hippocampal mossy fiber synaptic transmission. Here we identify molecular mechanisms that underlie the polarized trafficking of KARs composed of the GluK3b splice variant.
View Article and Find Full Text PDFIn this study we have compared the tumour-seeking properties of mono-[(123)I]iodoprotohypericin and mono-[(123)I]iodohypericin in C3H mice with a subcutaneous radiation-induced fibrosarcoma-1 tumor. After intravenous injection, both tracers were rapidly cleared from all organs and were retained by the tumors. There was no significant difference in tumor uptake of the two tracers at all studied time points (p > 0.
View Article and Find Full Text PDFProlonged exposure of beta-cells to high glucose (glucotoxicity) diminishes insulin secretion in response to glucose and has been linked to altered generation of metabolism-secretion coupling factors. We have investigated whether glucotoxicity may also alter calcium handling and late steps in secretion such as exocytosis. Clonal INS-1E beta-cells cultured at high glucose (20 or 30 mM vs.
View Article and Find Full Text PDFEur J Nucl Med Mol Imaging
May 2006
Purpose: We have labelled hypericin, a polyphenolic polycyclic quinone found in St. John's wort (Hypericum perforatum), with( 123)I and evaluated mono-[(123)I]iodohypericin (MIH) as a potential necrosis-avid diagnostic tracer agent.
Methods: MIH was prepared by an electrophilic radioiodination method.
The aim of this study was to investigate the in vitro cellular accumulation, distribution and photocytotoxic effect of hypericin in two-dimensional (2-D) and three-dimensional (3-D) cultured RT-112 transitional cell carcinoma cells of the bladder. In addition, two iodinated derivatives of hypericin were incorporated to investigate whether these analogs, with their increased lipophilicity and heavy-atom effect, display a different biological behavior and optimized photodynamic effect. The results indicate that hypericin and mono-iodohypericin behave similarly in terms of cellular accumulation, spheroidal distribution and photocytotoxic effect.
View Article and Find Full Text PDFDue to the low concentrations in which 99mTc-radiopharmaceuticals are obtained (4-40 ng/ml), confirmation of the identity of these tracer agents in the European Pharmacopoeia is generally performed only indirectly by assessment of their retention times on RP-HPLC. We have investigated whether it is possible to obtain more direct proof of the identity of technetium-99m labelled radiopharmaceuticals using radio-LC-MS. As representative examples, negatively charged 99mTc-MAG3, positively charged 99mTc-Sestamibi and neutral 99mTc-ECD were used.
View Article and Find Full Text PDFOver a six year period, 145 pneumococcal septicemias were seen at the Tourcoing Hospital. This represents 0.39% of all hospitalized patients and 19.
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