Prevalence and analysis of Pseudomonas aeruginosa in chinchillas

<p>Abstract</p> <p>Background</p> <p>Chinchillas (<it>Chinchilla laniger</it>) are popular as pets and are often used as laboratory animals for various studies. <it>Pseudomonas aeruginosa </it>is a major infectious agent that causes otitis media, pneumonia, septicaemia enteritis, and sudden death in chinchillas. This bacterium is also a leading cause of nosocomial infections in humans. To prevent propagation of <it>P. aeruginosa </it>infection among humans and animals, detailed characteristics of the isolates, including antibiotic susceptibility and genetic features, are needed. In this study, we surveyed <it>P. aeruginosa </it>distribution in chinchillas bred as pets or laboratory animals. We also characterized the isolates from these chinchillas by testing for antibiotic susceptibility and by gene analysis.</p> <p>Results</p> <p><it>P. aeruginosa </it>was isolated from 41.8% of the 67 chinchillas included in the study. Slide agglutination and pulsed-field gel electrophoresis discriminated 5 serotypes and 7 unique patterns, respectively. For the antibiotic susceptibility test, 40.9% of isolates were susceptible to gentamicin, 77.3% to ciprofloxacin, 77.3% to imipenem, and 72.7% to ceftazidime. DNA analyses confirmed that none of the isolates contained the gene encoding extended-spectrum β-lactamases; however, 2 of the total 23 isolates were found to have a gene similar to the <it>pilL </it>gene that has been identified in the pathogenicity island of a clinical isolate of <it>P. aeruginosa</it>.</p> <p>Conclusions</p> <p><it>P. aeruginosa </it>is widely spread in chinchillas, including strains with reduced susceptibility to the antibiotics and highly virulent strains. The periodic monitoring should be performed to help prevent the propagation of this pathogen and reduce the risk of infection from chinchillas to humans.</p

Molecular and virulence characteristics of an outer membrane-associated RTX exoprotein in Pasteurella pneumotropica

<p>Abstract</p> <p>Background</p> <p><it>Pasteurella pneumotropica </it>is a ubiquitous bacterium that is frequently isolated from laboratory rodents and causes various clinical symptoms in immunodeficient animals. Currently two RTX toxins, PnxIA and PnxIIA, which are similar to hemolysin-like high-molecular-weight exoproteins are known in this species. In this study, we identified and analyzed a further RTX toxin named PnxIIIA and the corresponding type I secretion system.</p> <p>Results</p> <p>The RTX exoprotein, PnxIIIA, contains only a few copies of the RTX repeat-like sequence and 3 large repeat sequences that are partially similar to the outer membrane protein found in several prokaryotes. Recombinant PnxIIIA protein (rPnxIIIA) was cytotoxic toward J774A.1 mouse macrophage cells, whereas cytotoxicity was attenuated by the addition of anti-CD11a monoclonal antibody. rPnxIIIA could bind to extracellular matrices (ECMs) and cause hemagglutination of sheep erythrocytes. Binding was dependent on the 3 large repeat sequences in PnxIIIA. Protein interaction analyses indicated that PnxIIIA is mainly localized in the outer membrane of <it>P. pneumotropica </it>ATCC 35149 in a self-assembled oligomeric form. PnxIIIA is less cytotoxic to J774A.1 cells than PnxIA and PnxIIA.</p> <p>Conclusions</p> <p>The results implicate that PnxIIIA is located on the cell surface and participates in adhesion to ECMs and enhanced hemagglutination in the rodent pathogen <it>P. pneumotropica</it>.</p

Differentiation of murine B cells induced by chondroitin sulfate B

A two-step culture system was used to investigate the role of chondroitin sulfate (CS) B, which is mitogenic to B cells, in differentiation of B cells. Mouse spleen B cells were incubated for 3 days with CSB in the presence of interleukin (IL)-4 and IL-5. After washing, the cells were replated at 10(5) viable cells/well and recultured without CSB in the presence of IL-4 and IL-5. CSB dose-dependently increased IgM production, the greatest enhancement being 450%. Dextran sulfate had a similar effect, whereas other glycosaminoglycans, CSA, CSC, heparin and hyaluronic acid, were marginally effective. Treatment of B cells with CSB resulted in increases in the number of IgM-secreting cells and numbers of CD138-positive cells and CD45R/B220-negative cells. CSB-induced IgM production was inhibited by the protein kinase C (PKC) inhibitor GF109203X but not by the phosphatidylinositol 3-kinase (P13K) inhibitor wortmannin. These results demonstrated that CSB promoted differentiation of B cells in the presence of IL-4 and IL-5 and suggested that PKC but not P13K is crucial for CSB-induced IgM production.</p

Promotion of IL-4- and IL-5-dependent differentiation of anti-μ-primed B cells by ascorbic acid 2-glucoside

The stable ascorbic acid derivative 2-O-alpha-D-glucopyranosyl-L-ascorbic acid (AA-2G) was used to investigate the role of ascorbic acid (AA) in B cell differentiation in vitro. AA-2G is stable in a solution unlike AA but is hydrolyzed by cellular alpha-glucosidase to release AA. Mouse spleen B cells were primed for 2 days with an anti-mu antibody in the presence of interleukin (IL)-4 and IL-5 and then washed and recultured with AA-2G in the presence of IL-4 and IL-5. AA-2G, but not AA, dose-dependently increased IgM production, the greatest enhancement being 150% at concentrations of more than 0.5 mM. In the absence of IL-4 and IL-5, primed B cells produced a negligible amount of IgM, and AA-2G had no effect. AA-2G-induced IgM production in the presence of IL-4 and IL-5 was inhibited by the alpha-glucosidase inhibitor castanospermine. Intracellular AA content, depleted during the priming period, increased by adding AA-2G at the start of reculture. Treatment of B cells with AA-2G resulted in an increase in the number of IgM-secreting cells, CD138-positive cells and CD45R/B220-negative cells. The number of viable cells in untreated cultures decreased gradually, but the decrease was significantly attenuated by AA-2G, resulting in about 70% more viable cells in AA-2G-treated cultures. AA-2G caused a slight but reproducible enhancement of DNA synthesis and a slight decrease in the number of cells with a sub-G1 DNA content. These results demonstrated that AA released from AA-2G enhanced cytokine-dependent IgM production in anti-mu-primed B cells and suggest that its effect is caused through promoting the differentiation of B cells to plasma cells and attenuating the gradual decrease in the number of viable cells

Cementless total hip replacement: past, present, and future

Cementless total hip replacement (THR) is rapidly being accepted as the surgery for arthritic diseases of the hip joint. The bone-ingrowth rate in porous-type cementless implants was about 90% over 10 years after surgery, showing that biological fixation of cementless THR was well maintained on both the stem and cup sides. As for the stress shielding of the femur operated using a distal fixation-type stem, severe bone resorption was observed. The severe bone resorption group showed continuous progression for more than 10 years after surgery. Stem loosening directly caused by stress shielding has been considered less likely; however, close attention should be paid to bone resorption-associated disorders including femoral fracture. Cementless cups have several specific problems. It is difficult to decide whether a cup should be placed in the physiological position for the case of acetabular dysplasia by bone grafting or at a relatively higher position without bone grafting. The bone-ingrowth rate was lower in the group with en bloc bone grafting, and the reactive line was frequently noted in the bone-grafted region. Although no data indicated that en bloc bone grafting directly led to poor outcomes, such as loosening, cup placement at a higher site without bone grafting is now selected by most operators. The polyethylene liner in a cementless cup is thinned due to the metal cup thickness; however, it has been suggested that the apparent relation between the cup size and the wear rate was absent as long as a cementless cup is used. Comparative study indicated cementless THR was inferior with regard to the yearly polyethylene wear rate and incidence of osteolysis on both the stem and cup sides. Meta-analysis study on the survival rate between cement and cementless THR reported that cemented THR was slightly superior. It should be considered that specific problems for cementless THR, especially with regard to polyethylene wear, do occur

Generation of ultrashort optical pulses in the 10 fs regime using multicolor Raman sidebands in KTaO3

We demonstrated Fourier synthesis of a new type of multiple coherent anti-Stokes Raman scatterings in KTaO3 crystal. The signals with a wavelength range of 500-750 nm were generated by two femtosecond pulses whose frequency difference was set to be a two-phonon Raman frequency. Angle dispersion of the signals was compensated into one white-continuum beam by spherical mirrors and a prism. The spectral phase, measured by spectral phase interferometry for direct electric-field reconstruction, was compensated for by carefully aligning the angle and the position of the optical components so that 13 fs isolated pulses were generated. This result shows the robustness of our scheme to produce ultrashort optical pulses