Structural Basis of GLUT1 Inhibition by Cytoplasmic ATP

Cytoplasmic ATP inhibits human erythrocyte glucose transport protein (GLUT1)–mediated glucose transport in human red blood cells by reducing net glucose transport but not exchange glucose transport (Cloherty, E.K., D.L. Diamond, K.S. Heard, and A. Carruthers. 1996. Biochemistry. 35:13231–13239). We investigated the mechanism of ATP regulation of GLUT1 by identifying GLUT1 domains that undergo significant conformational change upon GLUT1–ATP interaction. ATP (but not GTP) protects GLUT1 against tryptic digestion. Immunoblot analysis indicates that ATP protection extends across multiple GLUT1 domains. Peptide-directed antibody binding to full-length GLUT1 is reduced by ATP at two specific locations: exofacial loop 7–8 and the cytoplasmic C terminus. C-terminal antibody binding to wild-type GLUT1 expressed in HEK cells is inhibited by ATP but binding of the same antibody to a GLUT1–GLUT4 chimera in which loop 6–7 of GLUT1 is substituted with loop 6–7 of GLUT4 is unaffected. ATP reduces GLUT1 lysine covalent modification by sulfo-NHS-LC-biotin by 40%. AMP is without effect on lysine accessibility but antagonizes ATP inhibition of lysine modification. Tandem electrospray ionization mass spectrometry analysis indicates that ATP reduces covalent modification of lysine residues 245, 255, 256, and 477, whereas labeling at lysine residues 225, 229, and 230 is unchanged. Exogenous, intracellular GLUT1 C-terminal peptide mimics ATP modulation of transport whereas C-terminal peptide-directed IgGs inhibit ATP modulation of glucose transport. These findings suggest that transport regulation involves ATP-dependent conformational changes in (or interactions between) the GLUT1 C terminus and the C-terminal half of GLUT1 cytoplasmic loop 6–7

Photoabsorption Spectra of Atoms in Parallel Electric and Magnetic Fields

Measurements have been made of the absorption spectrum of Ba from the 6s6p 1P1 level to states near the ionization threshold in parallel electric and magnetic fields. The absorption spectrum shows oscillations superposed on a smooth background. Each oscillation is correlated with a closed orbit of the electron. At strong electric fields, trajectories are regular, and closed orbits form orderly patterns. For weak electric fields, trajectories are chaotic, and many more closed orbits are present. Many of these are produced by bifurcations as the electric field is reduced

A long view of liberal peace and its crisis

The ‘crisis’ of liberal peace has generated considerable debate in International Relations. However, analysis is inhibited by a shared set of spatial, cultural and temporal assumptions that rest on and reproduce a problematic separation between self-evident ‘liberal’ and ‘non-liberal’ worlds, and locates the crisis in presentist terms of the latter’s resistance to the former’s expansion. By contrast, this article argues that efforts to advance liberal rule have always been interwoven with processes of alternative order-making, and in this way are actively integral, not external, to the generation of the subjectivities, contestations, violence and rival social orders that are then apprehended as self-evident obstacles and threats to liberal peace and as characteristic of its periphery. Making visible these intimate relations of co-constitution elided by representations of liberal peace and its crisis requires a long view and an analytical frame that encompasses both liberalism and its others in the world. The argument is developed using a Foucauldian governmentality framework and illustrated with reference to Sri Lanka

Non-Invasive Imaging of Acute Renal Allograft Rejection in Rats Using Small Animal 18F-FDG-PET

BACKGROUND: At present, renal grafts are the most common solid organ transplants world-wide. Given the importance of renal transplantation and the limitation of available donor kidneys, detailed analysis of factors that affect transplant survival are important. Despite the introduction of new and effective immunosuppressive drugs, acute cellular graft rejection (AR) is still a major risk for graft survival. Nowadays, AR can only be definitively by renal biopsy. However, biopsies carry a risk of renal transplant injury and loss. Most important, they can not be performed in patients taking anticoagulant drugs. METHODOLOGY/PRINCIPAL FINDINGS: We present a non-invasive, entirely image-based method to assess AR in an allogeneic rat renal transplantation model using small animal positron emission tomography (PET) and (18)F-fluorodeoxyglucose (FDG). 3 h after i.v. injection of 30 MBq FDG into adult uni-nephrectomized, allogeneically transplanted rats, tissue radioactivity of renal parenchyma was assessed in vivo by a small animal PET-scanner (post operative day (POD) 1,2,4, and 7) and post mortem dissection. The mean radioactivity (cps/mm(3) tissue) as well as the percent injected dose (%ID) was compared between graft and native reference kidney. Results were confirmed by histological and autoradiographic analysis. Healthy rats, rats with acute CSA nephrotoxicity, with acute tubular necrosis, and syngeneically transplanted rats served as controls. FDG-uptake was significantly elevated only in allogeneic grafts from POD 1 on when compared to the native kidney (%ID graft POD 1: 0.54+/-0.06; POD 2: 0.58+/-0.12; POD 4: 0.81+/-0.06; POD 7: 0.77+/-0.1; CTR: 0.22+/-0.01, n = 3-28). Renal FDG-uptake in vivo correlated with the results obtained by micro-autoradiography and the degree of inflammatory infiltrates observed in histology. CONCLUSIONS/SIGNIFICANCE: We propose that graft FDG-PET imaging is a new option to non-invasively, specifically, early detect, and follow-up acute renal rejection. This method is potentially useful to improve post-transplant rejection monitoring