Self-limited giant cell arteritis: The dilemma associated with its diagnosis and treatment.

Giant cell arteritis (GCA) can result in visual loss and other sequelae. An 81-year-old man presented with a one-week history of fever. He had bilateral temporal headache, jaw claudication, tenderness of the temporal arteries and a recent skin rash. A temporal artery biopsy showed typical GCA, but the symptoms were self-limiting. We continued close observation, without administering prednisolone treatment. Five months later, the symptoms did not recur, and prednisolone again was not administered. Our patient presented with an atypical course of GCA that created a clinical dilemma. The final diagnosis was self-limiting GCA.

Identification and characterization of novel N-acylhomoserine lactonase from nonpathogenic Allorhizobium vitis, a candidate for biocontrol agent.

Some strains of nonpathogenic Allorhizobium vitis can control crown gall disease in grapevines caused by pathogenic A. vitis and are considered candidates for biocontrol agents. Many plant pathogenic bacteria regulate the expression of their virulence genes via quorum sensing using N-acylhomoserine lactone (AHL) as a signaling compound. The eight nonpathogenic A. vitis strains used in this study showed AHL-degrading activity. The complete genome sequence of A. vitis MAFF 212306 contained three AHL lactonase gene homologs. When these genes were cloned and transformed into Escherichia coli DH5α, E. coli harboring the aiiV gene (RvVAR031_27660) showed AHL-degrading activity. The aiiV coding region was successfully amplified by polymerase chain reaction from the genomes of all eight strains of nonpathogenic A. vitis. Purified His-tagged AiiV exhibited AHL lactonase activity by hydrolyzing the lactone ring of AHL. AiiV had an optimal temperature of approximately 30 °C; however, its thermostability decreased above 40 °C. When the AiiV-expressing plasmid was transformed into Pectobacterium carotovorum subsp. carotovorum NBRC 3830, AHL production by NBRC 3830 decreased below the detection limit, and its maceration activity, which was controlled by quorum sensing, almost disappeared. These results suggest the potential use of AHL-degrading nonpathogenic A. vitis for the inhibition of crown gall disease in grapevines and other plant diseases controlled by quorum sensing.