Macroscopic Aharonov--Bohm Effect in Type-I Superconductors

In type-I superconducting cylinders bulk superconductivity is destroyed above the first critical current. Below the second critical current the `type-I mixed state' displays fluctuation superconductivity which contributes to the total current. A magnetic flux on the axis of the cylinder can change the second critical current by as much as 50 percent so that half a flux quantum can switch the cylinder from normal conduction to superconductivity: the Aharonov--Bohm effect manifests itself in macroscopically large resistance changes of the cylinder.Comment: five pages, one figur

Le couplage phosphore-phosphore dans l'adenosine di- et triphosphate

AbstractThe pH dependence of spin-spin coupling constants JP-O-P of ADP and ATP has been determined from the phosphorus NMR spectra at 0°. The variation curves have been interpreted as titration curves. These give different pK values. Comparison with the tripolyphosphate shows the existence of triphosphate chain structural deformation in the nucleotides

Evolution des pâturages. Etude de la biologie de deux graminées : Imperata cylindrica (Linn.) et Aristida rufescens (Stend)

L'étude de la biologie d'Imperata cylindrica et Aristida rufescens permet de mettre en évidence l'importance de l'appareil souterrain et l'influence du facteur édaphique sur le développement de ces graminées. Ces espèces seraient secondaires en savane mais dans des conditions de sous-exploitation (écimage des chaumes et suppression des feux) elles peuvent devenir dominantes alors qu'on a pu penser qu'elles étaient favorisées par le surpâturage. Le contrôle de leur expansion est important à considérer parce que leur productivité est faible, leur appétibilité temporaire et surtout parce qu'elles modifient la vocation des zones qu'elles occupen

Dynamic Locomotor Capabilities Revealed by Early Dinosaur Trackmakers from Southern Africa

BACKGROUND: A new investigation of the sedimentology and ichnology of the Early Jurassic Moyeni tracksite in Lesotho, southern Africa has yielded new insights into the behavior and locomotor dynamics of early dinosaurs. METHODOLOGY/PRINCIPAL FINDINGS: The tracksite is an ancient point bar preserving a heterogeneous substrate of varied consistency and inclination that includes a ripple-marked riverbed, a bar slope, and a stable algal-matted bar top surface. Several basal ornithischian dinosaurs and a single theropod dinosaur crossed its surface within days or perhaps weeks of one another, but responded to substrate heterogeneity differently. Whereas the theropod trackmaker accommodated sloping and slippery surfaces by gripping the substrate with its pedal claws, the basal ornithischian trackmakers adjusted to the terrain by changing between quadrupedal and bipedal stance, wide and narrow gauge limb support (abduction range = 31 degrees ), and plantigrade and digitigrade foot posture. CONCLUSIONS/SIGNIFICANCE: The locomotor adjustments coincide with changes in substrate consistency along the trackway and appear to reflect 'real time' responses to a complex terrain. It is proposed that these responses foreshadow important locomotor transformations characterizing the later evolution of the two main dinosaur lineages. Ornithischians, which shifted from bipedal to quadrupedal posture at least three times in their evolutionary history, are shown to have been capable of adopting both postures early in their evolutionary history. The substrate-gripping behavior demonstrated by the early theropod, in turn, is consistent with the hypothesized function of pedal claws in bird ancestors

Serum peptide reactivities may distinguish neuromyelitis optica subgroups and multiple sclerosis

Objective: To assess in an observational study whether serum peptide antibody reactivities may distinguish aquaporin-4 (AQP4) antibody (Ab)–positive and -negative neuromyelitis optica spectrum disorders (NMOSD) and relapsing-remitting multiple sclerosis (RRMS). Methods: We screened 8,700 peptides that included human and viral antigens of potential relevance for inflammatory demyelinating diseases and random peptides with pooled sera from different patient groups and healthy controls to set up a customized microarray with 700 peptides. With this microarray, we tested sera from 66 patients with AQP4-Ab-positive (n = 16) and AQP4-Ab-negative (n = 19) NMOSD, RRMS (n = 11), and healthy controls (n = 20). Results: Differential peptide reactivities distinguished NMOSD subgroups from RRMS in 80% of patients. However, the 2 NMOSD subgroups were not well-discriminated, although those patients are clearly separated by their antibody reactivities against AQP4 in cell-based assays. Elevated reactivities to myelin and Epstein-Barr virus peptides were present in RRMS and to AQP4 and AQP1 peptides in AQP4-Ab-positive NMOSD. Conclusions: While AQP4-Ab-positive and -negative NMOSD subgroups are not well-discriminated by peptide antibody reactivities, our findings suggest that peptide antibody reactivities may have the potential to distinguish between both NMOSD subgroups and MS. Future studies should thus concentrate on evaluating peptide antibody reactivities for the differentiation of AQP4-Ab-negative NMOSD and MS

Antibody signatures in patients with histopathologically defined multiple sclerosis patterns

Early active multiple sclerosis (MS) lesions can be classified histologically into three main immunopathological patterns of demyelination (patterns I-III), which suggest pathogenic heterogeneity and may predict therapy response. Patterns I and II show signs of immune-mediated demyelination, but only pattern II is associated with antibody/complement deposition. In pattern III lesions, which include Baló's concentric sclerosis, primary oligodendrocyte damage was proposed. Serum antibody reactivities could reflect disease pathogenesis and thus distinguish histopathologically defined MS patterns. We established a customized microarray with more than 700 peptides that represent human and viral antigens potentially relevant for inflammatory demyelinating CNS diseases, and tested sera from 66 patients (pattern I n = 12; II n = 29; III n = 25, including 8 with Baló's), healthy controls, patients with Sjögren's syndrome and stroke patients. Cell-based assays were performed for aquaporin 1 (AQP1) and AQP4 antibody detection. No single peptide showed differential binding among study cohorts. Because antibodies can react with different peptides from one protein, we also analyzed groups of peptides. Patients with pattern II showed significantly higher reactivities to Nogo-A peptides as compared to patterns I (p = 0.02) and III (p = 0.02). Pattern III patients showed higher reactivities to AQP1 (compared to pattern I p = 0.002, pattern II p = 0.001) and varicella zoster virus (VZV, compared to pattern II p = 0.05). In patients with Baló's, AQP1 reactivity was also significantly higher compared to patients without Baló's (p = 0.04), and the former revealed distinct antibody signatures. Histologically, Baló's patients showed loss of AQP1 and AQP4 in demyelinating lesions, but no antibodies binding conformational AQP1 or AQP4 were detected. In summary, higher reactivities to Nogo-A peptides in pattern II patients could be relevant for enhanced axonal repair and remyelination. Higher reactivities to AQP1 peptides in pattern III patients and its subgroup of Baló's patients possibly reflect astrocytic damage. Finally, latent VZV infection may cause peripheral immune activation

The N-Terminal domain of SIRT1 is a positive regulator of endogenous SIRT1-dependent deacetylation and transcriptional outputs

SummaryThe NAD+-dependent protein deacetylase SIRT1 regulates energy metabolism, responses to stress, and aging by deacetylating many different proteins, including histones and transcription factors. The mechanisms controlling SIRT1 enzymatic activity are complex and incompletely characterized, yet essential for understanding how to develop therapeutics that target SIRT1. Here, we demonstrate that the N-terminal domain of SIRT1 (NTERM) can trans-activate deacetylation activity by physically interacting with endogenous SIRT1 and promoting its association with the deacetylation substrate NF-κB p65. Two motifs within the NTERM domain contribute to activation of SIRT1-dependent activities, and expression of one of these motifs in mice is sufficient to lower fasting glucose levels and improve glucose tolerance in a manner similar to overexpression of SIRT1. Our results provide insights into the regulation of SIRT1 activity and a rationale for pharmacological control of SIRT1-dependent activities