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Notes: Samples of YBa2Cu3O7 have been prepared with rather sharp inductive transitions having in the best cases breadths of 7 K and midpoint Tc values of 88 K. The resistive Tc midpoints are 92–95 K with transition widths of ±1–2 K. Flux shielding at 4.2 K is normally 100% and flux expulsion at 4.2 K reaches 95%. However, even small fields of order 1 mT decouple some 15%–20% of the volume, allowing flux to enter the samples. Resistive Hc2 measurements suggest that Hc2(0) varies from 〈1 to 〉300 T, depending on the criterion chosen. ac susceptibility measurements suggest that Hc2(0) is ∼60 T. Magnetization current densities are relatively high (150–200 A/mm2 at 1–10 T at 4.2 K) but measured transport current densities are small (≤1 A/mm2). Magnetization current densities at 77 K are about two orders of magnitude lower. The samples were seen to be heavily twinned by light microscopy (scale of 1–5 μm) and by transmission electron microscopy (scale of ∼250 nm). It is concluded that these measurements are consistent with a model of superconducting regions of reduced dimensionality coupled by tunneling.

Notes: 1. The application of functional ecology models to aquatic plants often relies on morphological and life-history traits which may reflect, in part, the phenotypic plasticity displayed by aquatic plants. The present study was designed to evaluate the use of physiological traits, such as nutrition patterns, to describe aquatic plant strategies along a gradient of increasing resource availablity.2. Taking phosphorus (P) as an example, nutrition-use efficiencies were evaluated in five species, through the P-content in plant tissues, the variations in P-content according to nutrient availability and the perenniality of P-storage. Plasticity in P-storage was also investigated in Ranunculus peltatus, a morphologically highly plastic species.3. In 2001, P-content was analysed in Callitriche hamulata, C. obtusangula, C. platycarpa, Elodea nuttallii and R. peltatus tissue samples. These five species were sampled at nine different sites in streams along an increasing resource gradient in the Northern Vosges Biosphere Reserve (NE France). Variations of P-content in the roots, stems and dissected and floating leaves of R. peltatus were also studied.4. Only C. platycarpa and R. peltatus were found to occur in low nutrient availability conditions. Callitriche hamulata, C. obtusangula and E. nuttallii were restricted to mesotrophic and eutrophic sites. The highest nutrient-use efficiency was found for E. nuttallii which was able to adapt its P-storage to varying resource availabilities. Ranunculus peltatus was able to store high concentrations of P, but its P-integration within the vegetative structure was less efficient under eutrophic conditions. Callitriche spp. appeared to have relatively low nutrient-use efficiencies, although C. obtusangula displayed a high P-content. While P was stored preferentially in roots in R. peltatus populations occurring in nutrient-rich sites, there was no particular P-storage organ for populations from nutrient-poor sites.5. On the basis of P-usage, R. peltatus and E. nuttallii presented competitor traits, C. hamulata and C. platycarpa displayed stress-tolerant nutrient signatures and for C. obtusangula, ruderal or competitor characteristics dominated. The use of physiological traits, such as nutrition patterns, may provide valuable, complementary information about aquatic plant strategies, independent from the influence of morphological trait plasticity often displayed by these plants.

Notes: Paraventricular corticotropin-releasing factor (CRF) neurons play a pivotal role in regulating neuroendocrine responses to stress. The mechanisms by which synaptic inputs control the activity of these neurons are not well understood. The present study was undertaken to determine the role of the intrinsic γ-aminobutyric acid (GABA)- and glutamatergic neural circuits of the hypothalamic paraventricular nucleus (PVN) in the control of CRF neural activity. We show that in organotypic cultures of the PVN, blockade of the intrinsic GABAergic neurotransmission by the GABAA receptor antagonist bicuculline resulted in a significant increase in CRF secretion. The bicuculline-induced CRF secretory activity was abolished by the coadministration of the selective α-amino-3-hydroxy-5-methyl-4-isoxazoleprionic acid (AMPA)/kainate receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX). Electrical stimulation of the CRF cell division elicited glutamatergic extracellular field potentials that were dramatically enhanced by bicuculline and were suppressed by CNQX. These results show that the functional activity of CRF neurons in organotypic cultures of the PVN is under a tonic inhibitory influence of an intrinsic GABAergic circuit. Suppression of GABAergic transmission appears to have a permissive role for inducing an increased secretory activity of CRF neurons that is driven by an excitatory glutamatergic network via AMPA/kainate receptors.

Notes: In the hypoglossal nucleus, GABA and glycine mediate inhibition at separate or mixed synapses containing glycine receptors (GlyRs) and/or GABAA receptors (GABAARs). The functional development of mixed inhibitory synapses depends on the brain area studied, but their relative proportion to total synapses generally decreases with time. We have determined the sequential process of inhibitory synapse maturation in the hypoglossal nucleus in vivo. Immunocytochemistry and confocal microscopy were used for codetection of VIAAT, the common presynaptic vesicular transporter of glycine and GABA, GlyRs, GABAAR α1 and γ2 subunits, and gephyrin, the scaffold protein implicated in the synaptic localization of inhibitory receptors. In E17 embryos, GlyRs were already clustered while GABAAR α1 and γ2 subunit immunoreactivity (IR) displayed both diffuse and clustered patterns. Quantitative analysis at this stage revealed that the majority of GlyR clusters were apposed to VIAAT-IR accumulation and that 30% of them colocalized with γ2GABAAR clusters. This proportion increased with age to 50% at P30. GlyR clusters that did not colocalize with γ2GABAAR clusters were associated with GABAAR γ2 diffuse IR. Interestingly, the percentage of GlyR clusters surrounded by GABAAR γ2 diffuse IR decreased with age, while GlyR clusters colocalized with γ2GABAAR clusters increased. The developmental coclustered pattern of gephyrin and GABAAR α1 and γ2 subunits paralleled the coclustered pattern of GlyRs and GABAAR α1 and γ2 subunits. Our results indicate that the proportion of GlyR-GABAAR coclusters increases until adulthood. A developmental sequence of the postsynaptic events is proposed in which diffuse extrasynaptic GABAARs accumulate at inhibitory synapses to form postsynaptic clusters, most of them being colocalized with GlyR clusters in the adult.

Notes: The present study was made to determine the value of drug skin tests in patients with cutaneous adverse drug reactions (CADRs) due to a synergistin (pristinamycin) and to determine the frequency of cross-reactions between synergistins. 29 patients were referred during the onset of the CADR due to pristinamycin: 18 with maculopapular rash, 9 erythrodermas, 1 angioedema and 1 Stevens–Johnson syndrome. They all had patch tests with pristinamycin and, in most cases, with other synergistins [virginiamycin and dalfopristin–quinupristin (DQ)], prick tests (10 cases) and intradermal tests (IDT) (5 cases). Skin tests with synergistins were positive in 27 cases, patch tests with pristinamycin in 20/29 cases (69%), prick tests with pristinamycin in 3/9 cases on immediate (1 case) or on delayed (2 cases) readings, and IDT with DQ in 4/5 cases. Cross-reactions between synergistins occurred in 9/22 with virginiamycin and in 7/8 cases with DQ. Skin tests with synergistins are useful in investigating CADR due to pristinamycin. Synergistins are composed of 2 chains (1 depsipeptide and 1 macrocyclic lactone) with many structural analogies between all synergistins. According to the chemical structures and our results, it seems advisable to avoid all synergistins in patients with CADR due to pristinamycin.

Notes: SUBURBANIZATION