Aeromonas update: new species and global distribution

There are currently eight proposed or validated Aeromonas spp. of which five have been implicated in human disease: A. hydrophila, A. sobria, A. caviae, A. veronii, and A. schubertii. Recent studies have extended the geographic distribution and source of isolation of the newer species and resulted in the possibility of two new species, A. jandaei and A. trota, from diarrheal, wound, blood and environmental sources.     

New lectins and other putative adhesins in Aeromonas hydrophila

The ability of strains of Aeromonas hydrophila to bind 125I-labelled collagen types I and IV, fibronectin, laminin, lactoferrin, and immobilized mucins and orosomucoid on latex beads was found to be a property common to all the isolated strains. The binding was specific, was inhibited by homologous unlabelled glycoproteins, and was protease sensitive. The nature of the binding is discussed.     

Spectrum of Aeromonas and Plesiomonas infections in patients with cancer and AIDS

The spectrum of infection with Aeromonas and Plesiomonas included gastroenteritis, bacteremia, biliary tract infection, perirectal infection, and disseminated disease. Most patients (86%) with bacteremia were neutropenic (less than 500 PMN/mm3). Colonization of stools and sputum also occurred. Therapy with aminoglycosides, beta-lactams, trimethoprim/sulfamethoxazole, and the newer quinolones was effective in patients with AIDS and cancer.     

Methods for the identification of DNA hybridization groups in the genus Aeromonas.

Among the 269 substrates tested in assimilation tests we found some that may help in the identification of DNA hybridization groups in the genus Aeromonas. In addition, isoenzyme analysis and ribotyping seem to be accurate although not routine procedures that allow discrimination between genetic species.     

Form and functions of the regular surface array (S-layer) of Aeromonas salmonicida

The principal virulence factor of Aeromonas salmonicida is its S-layer (A-layer) which is comprised of tetragonally arrayed approximately 50,000 Mr protein subunits tethered to the cell surface via LPS. The detailed composition of its LPS is known, as is the primary sequence, and three-dimensional disposition of the A protein subunits. The A-layer physically protects the cell against bacteriophage, proteases, as well as immune and non-immune complement. The A-layer appears to be uniquely adapted towards binding biologically important molecules such as heme, and to various basement membrane proteins. In addition, the A-layer is required for macrophage infiltration and resistance. Specific mutants containing a disorganized A-layer are avirulent and provide significant protection to salmonids when applied by immersion.     

Studies on aerolysin and a serine protease from Aeromonas trota sp. nov

Hybridization of 257 mesophilic aeromonads revealed that the aerolysin gene is present in virtually all strains irrespective of origin of isolation. A probe comprising the promotor region was specific for a species now defined as Aeromonas trota sp. nov. Finally, isolation of a serine protease that is concomitantly expressed with aerolysin is described.     

Review

In this paper we study some methodological problems associated with the development of one of the major theories in low temperature physics, that of superconductivity. The first experimental results of 1911 were interpreted within a framework that hindered the paradoxical aspects of the new phenomenon. Various research programmes degenerated until new experimental results forced a reappraisal of the existing theoretical framework making possible a different formulation of the problem that had to be solved. This led to a progressive research programme, whose positive heuristic we also study.     

突发性地质灾害研究现状

近年来,突发性地质灾害的频繁发生,给人们的生命财产造成的损失越来越大,对突发性地质灾害的研究已经成为国际社会关注的热点领域.为了及时总结该领域已有的研究成果,为防灾减灾提供科学依据,本文从对突发性地质灾害的成因、危险性评价、预测预警和防治等方面进行了现状综述,分析讨论了突发性地质灾害及防治存在的问题与进一步研究的方向.