Purinergic Receptor Functionality Is Necessary for Infection of Human Hepatocytes by Hepatitis Delta Virus and Hepatitis B Virus

Hepatitis B virus (HBV) and hepatitis delta virus (HDV) are major sources of acute and chronic hepatitis. HDV requires the envelope proteins of HBV for the processes of assembly and infection of new cells. Both viruses are able to infect hepatocytes though previous studies have failed to determine the mechanism of entry into such cells. This study began with evidence that suramin, a symmetrical hexasulfated napthylurea, could block HDV entry into primary human hepatocytes (PHH) and was then extrapolated to incorporate findings of others that suramin is one of many compounds that can block activation of purinergic receptors. Thus other inhibitors, pyridoxal-phosphate-6-azophenyl-2′,4′-disulfonate (PPADS) and brilliant blue G (BBG), both structurally unrelated to suramin, were tested and found to inhibit HDV and HBV infections of PHH. BBG, unlike suramin and PPADS, is known to be more specific for just one purinergic receptor, P2X7. These studies provide the first evidence that purinergic receptor functionality is necessary for virus entry. Furthermore, since P2X7 activation is known to be a major component of inflammatory responses, it is proposed that HDV and HBV attachment to susceptible cells, might also contribute to inflammation in the liver, that is, hepatitis

Purinergic signalling and immune cells

This review article provides a historical perspective on the role of purinergic signalling in the regulation of various subsets of immune cells from early discoveries to current understanding. It is now recognised that adenosine 5'-triphosphate (ATP) and other nucleotides are released from cells following stress or injury. They can act on virtually all subsets of immune cells through a spectrum of P2X ligand-gated ion channels and G protein-coupled P2Y receptors. Furthermore, ATP is rapidly degraded into adenosine by ectonucleotidases such as CD39 and CD73, and adenosine exerts additional regulatory effects through its own receptors. The resulting effect ranges from stimulation to tolerance depending on the amount and time courses of nucleotides released, and the balance between ATP and adenosine. This review identifies the various receptors involved in the different subsets of immune cells and their effects on the function of these cells

Magnetic Properties of Low-Dimensional alpha and gamma CoV2O6

In this work, we analyze the magnetic properties of the low-dimensional CoV2O6 powders showing monoclinic (alpha) and triclinic (gamma) crystalline structures. The two phases are constituted of parallel ID Co chains organized in planes that are separated by vanadium oxide thin layers. Both alpha and gamma phases are antiferromagnetic in the ground state with Neel temperatures of 15 and 7 K, respectively. The magnetization curves recorded at 5 (alpha phase) and 1.8 K (gamma phase) show a stepped variation with sharp field-induced magnetic transitions and a magnetization plateau at one-third of the saturation magnetization. In alpha-CoV2O6, additional steps are evidenced when the temperature decreased from 5 to 1.8 K This is accompanied by an increasing hysteresis corresponding to the magnetic field transitions. From the magnetization curves recorded at different temperatures, a magnetic phase diagram could be determined. The estimated Co moment is large and reaches in the alpha and gamma phases 4.5 and 3 mu(B), respectively, suggesting the existence of an orbital contribution in alpha-CoV2O6

Epitaxial growth of gamma-CoV2O6 thin films: Structure, morphology, and magnetic properties:

We report on the epitaxial growth of 100 nm thick triclinic gamma-CoV2O6 thin films deposited by pulsed laser deposition on TiO2(100) substrate. The layers were grown in narrow experimental conditions, at 600 degrees C and 0.1 millibar oxygen pressure. X-ray diffraction and transmission electron microscopy evidenced the presence of two variants and the following epitaxial relation between the layers and the substrate: [001] TiO2(100) vertical bar vertical bar [0 +/- 10]gamma-CoV2O6(100). Besides the magnetization steps expected in gamma-CoV2O6, low temperature magnetic measurements performed along different crystalline axes show the existence of a strong anisotropy compatible with that expected from a one dimensional system, with the easy magnetization axis lying along the b direction (i.e., the Co chains). (C) 2013 AIP Publishing LLC

Spin wave and percolation studies in epitaxial La2/3Sr1/3MnO3 thin films grown by pulsed laser deposition

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