Gene expression profile and pathogenicity of biofilm-forming Prevotella intermedia strain 17

<p>Abstract</p> <p>Background</p> <p><it>Prevotella intermedia </it>(<it>P. intermedia</it>), a gram-negative, black-pigmented anaerobic rod, has been implicated in the development of chronic oral infection. <it>P. intermedia </it>strain 17 was isolated from a chronic periodontitis lesion in our laboratory and described as a viscous material producing strain. The stock cultures of this strain still maintain the ability to produce large amounts of viscous materials in the spent culture media and form biofilm-like structures. Chemical analyses of this viscous material showed that they were mainly composed of neutral sugars with mannose constituting 83% of the polysaccharides. To examine the biological effect of the extracellular viscous materials, we identified and obtained a naturally-occurring variant strain that lacked the ability to produce viscous materials <it>in vitro </it>from our stock culture collections of strain 17, designated as 17-2. We compared these two strains (strains 17 versus 17-2) in terms of their capacities to form biofilms and to induce abscess formation in mice as an indication of their pathogenicity. Further, gene expression profiles between these two strains in planktonic condition and gene expression patterns of strain 17 in solid and liquid cultures were also compared using microarray assays.</p> <p>Results</p> <p>Strain 17 induced greater abscess formation in mice as compared to that of the variant. Strain 17, but not 17-2 showed an ability to interfere with the phagocytic activity of human neutrophils. Expression of several genes which including those for heat shock proteins (DnaJ, DnaK, ClpB, GroEL and GroES) were up-regulated two to four-fold with statistical significance in biofilm-forming strain 17 as compared to the variant strain 17-2. Strain 17 in solid culture condition exhibited more than eight-fold up-regulated expression levels of several genes which including those for levanase, extracytoplasmic function-subfamily sigma factor (σ^E; putative) and polysialic acid transport protein (KpsD), as compared to those of strain 17 in liquid culture media.</p> <p>Conclusion</p> <p>These results demonstrate that the capacity to form biofilm in <it>P. intermedia </it>contribute to their resistance against host innate defence responses.</p

Operative Outcome of Cardiac Surgery in Patients with Liver Cirrhosis

Introduction: A retrospective study was performed to investigate the relationship between the severity of liver cirrhosis and the outcome of cardiac surgery. Methods and Results: Twenty-one patients with liver cirrhosis underwent cardiac surgery in our institution. According to the Child-Pugh classification, 13 patients were in class A, 7 in class B, and 1 in class C. Coronary artery bypass grafting was performed in 7 patients, surgery for valvular disease in 10 and other procedures in 4. Major postoperative complications occurred in 8%, 29%, and 100% for Child-Pugh class A, B, and C, respectively. Preoperative hemoglobin level was significantly lower in the patients with postoperative complications. None of 4 patients underwent coronary revascularization using off-pump procedure or mini-pump system experienced major complication. The operative mortality was 0%, 14%, and 0% for Child-Pugh class A, B, and C, respectively. Conclusions: Although the overall mortality rate in patients with liver cirrhosis was acceptable in our study, the incidence of severe complications, such as prolonged ventilation, mediastinitis and irreversible hepatic insufficiency was problematic in Child-Pugh class B and class C patients. Application of less invasive cardiac surgery, such as mini-pump system or off-pump procedure will improve the operative outcome in such patient group.長崎大学学位論文 学位記番号:博（医）甲第1,272号学位授与年月日:平成20年7月16

Comparison of the virulence of exopolysaccharide-producing Prevotella intermedia to exopolysaccharide non-producing periodontopathic organisms

<p>Abstract</p> <p>Background</p> <p>Evidence in the literature suggests that exopolysaccharides (EPS) produced by bacterial cells are essential for the expression of virulence in these organisms. Secreted EPSs form the framework in which microbial biofilms are built.</p> <p>Methods</p> <p>This study evaluates the role of EPS in <it>Prevotella intermedia </it>for the expression of virulence. This evaluation was accomplished by comparing EPS-producing <it>P. intermedia </it>strains 17 and OD1-16 with non-producing <it>P. intermedia </it>ATCC 25611 and <it>Porphyromonas gingivalis </it>strains ATCC 33277, 381 and W83 for their ability to induce abscess formation in mice and evade phagocytosis.</p> <p>Results</p> <p>EPS-producing <it>P. intermedia </it>strains 17 and OD1-16 induced highly noticeable abscess lesions in mice at 10⁷colony-forming units (CFU). In comparison, <it>P. intermedia </it>ATCC 25611 and <it>P. gingivalis </it>ATCC 33277, 381 and W83, which all lacked the ability to produce viscous materials, required 100-fold more bacteria (10⁹CFU) in order to induce detectable abscess lesions in mice. Regarding antiphagocytic activity, <it>P. intermedia </it>strains 17 and OD1-16 were rarely internalized by human polymorphonuclear leukocytes, but other strains were readily engulfed and detected in the phagosomes of these phagocytes.</p> <p>Conclusions</p> <p>These results demonstrate that the production of EPS by <it>P. intermedia </it>strains 17 and OD1-16 could contribute to the pathogenicity of this organism by conferring their ability to evade the host's innate defence response.</p

Effects of Non-Structural Carbohydrates on Spikelet Differentiation in Rice

Spikelet number per unit area is a strong determinant of rice yield, and spikelet differentiation must be promoted to increase spikelet number. Nitrogen has been considered to be the most critical factor in promoting spikelet differentiation and the role of non-structural carbohydrates (NSCs) in spikelet differentiation is unclear. To reveal the relation between NSCs and the number of differentiated spikelets, we conducted a field experiment in Matsue, Shimane, Japan, using two japonica cultivars Koshihikari and Nipponbare. The NSC content was changed by shading and thinning during the early reproductive stage. These treatments did not change the amount of nitrogen per hill in the leaves and stems. The number of differentiated spikelets, which was defined as the sum of the numbers of surviving spikelets and vestiges of degenerated spikelets, was not influenced by NSC content in rice plants; neither was the number of primary rachis-branches, which is considered to determine spikelet number per panicle. The ratio of dry matter allocation to leaves and the rest of the plants was changed, but the morphological characteristics such as tiller number and plant length were not influenced by the treatments. It is concluded that the differentiation of spikelets was not influenced by the NSC content within the range examined in the present experiment. The role of NSC in the mechanism of spikelet differentiation is discussed