Background Post-sternotomy mediastinitis (PSM) is a devastating surgical complication affecting 1... more Background Post-sternotomy mediastinitis (PSM) is a devastating surgical complication affecting 1–3% of patients that undergo cardiac surgery. Staphylococcus aureus is one of the most commonly encountered bacterial pathogen cultured from mediastinal samples obtained from patients with PSM. A component of the membrane of the gram positive bacteria, lipoteichoic acid, stimulates the blood monocytes and macrophages to secrete cytokines, radicals and nitrogen species leading to oxido-inflammatory damage. This seems to be responsible for the high mortality rate in PSM. For the evaluation of the pathogenesis of infection or for the investigation of alternative treatment models in infection, no standard model of mediastinitis seems to be available. In this study, we evaluated four mediastinitis models in rats. Methods The rats were divided into four groups to form different infection models. Group A: A suspension of 1 × 107 colony-forming units Staphylococcus aureus in 0,5 mL was inoculated from the right second intercostal space into the mediastinum. Group B: A hole was created in the right second intercostal space and a piece of stainless-steel implant with a length of 0.5 cm was inserted into the mediastinum and a suspension of 1 × 107 cfu bacteria in 0,5 mL was administered via the tail vein. Group C: Precolonized stainless-steel implant was inserted into the mediastinum. Group D: Precolonized stainless-steel implant was inserted into the mediastinum and the bacteria suspension was also injected into the mediastinum. On the 10th day, rats were sacrificed and the extension of infection in the mediastenae was evaluated by quantitative cultures. Myeloperoxidase activity (MPO) and malondialdehyde (MDA) levels were determined in the sera to evaluate the neutrophil activation and assess the inflammatory oxidation. Results The degree of infection in group C and D were 83.3% and 100% respectively (P P Conclusion Infected implants and high bacterial concentration administration were the two important components that played a significant role in the outcome of a successful infection in mediastinum in a rat model.
Infections caused by non-tuberculous mycobacteria (NTM) have increased recently because of the di... more Infections caused by non-tuberculous mycobacteria (NTM) have increased recently because of the dissemination of HIV infection and the appearance of other disease states post-transplantation or chemotherapy. Mycobacterium fortuitum is a rapidly growing mycobacteria that was ...
We consider a toy cosmological model with a gas of wrapped Dp-branes in 10-dimensional dilaton gr... more We consider a toy cosmological model with a gas of wrapped Dp-branes in 10-dimensional dilaton gravity compactified on a p-dimensional Ricci flat internal manifold. A consistent generalization of the low energy effective field equations in the presence of a conserved brane source coupled to dilaton is obtained. It is then shown that the compact dimensions are dynamically stabilized in string frame as a result of a balance between negative winding and positive momentum pressures. Curiously, when p = 6, i.e. when the observed space is three dimensional, the dilaton becomes a constant and stabilization in Einstein frame is also realized.
We consider evolution of compact extra dimensions in cosmology and try to see whether wrapped bra... more We consider evolution of compact extra dimensions in cosmology and try to see whether wrapped branes can prevent the expansion of the internal space. Some difficulties of Brandenberger and Vafa mechanism for decompactification are pointed out. In both pure Einstein and dilaton gravities, we study cosmology of winding brane gases in a continuum approximation. The energy momentum tensor is obtained by coupling the brane action to the gravity action and we present several exact solutions for various brane configurations. T-duality invariance of the solutions are established in dilaton gravity. Our results indicate that phenomenologically the most viable scenario can be realized when there is only one brane wrapping over all extra dimensions.
We present a cosmological model in 1 + m + p dimensions, where in m-dimensional space there are u... more We present a cosmological model in 1 + m + p dimensions, where in m-dimensional space there are uniformly distributed p-branes wrapping over the extra p-dimensions. We find that during cosmological evolution m-dimensional space expands with the exact power-law corresponding to pressureless matter while the extra p-dimensions contract. Adding matter, we also obtain solutions having the same property. We show that this might explain in a natural way why the extra dimensions are small compared to the observed three spatial directions. *
Journal of Cosmology and Astroparticle Physics, 2004
We investigate toy cosmological models in (1+m+p)-dimensions with gas of p-branes wrapping over p... more We investigate toy cosmological models in (1+m+p)-dimensions with gas of p-branes wrapping over p-compact dimensions. In addition to winding modes, we consider the effects of momentum modes corresponding to small vibrations of branes and find that the extra dimensions are dynamically stabilized while the others expand. Adding matter, the compact volume may grow slowly depending on the equation of state. We also obtain solutions with winding and momentum modes where the observed space undergoes accelerated expansion.
Background Post-sternotomy mediastinitis (PSM) is a devastating surgical complication affecting 1... more Background Post-sternotomy mediastinitis (PSM) is a devastating surgical complication affecting 1–3% of patients that undergo cardiac surgery. Staphylococcus aureus is one of the most commonly encountered bacterial pathogen cultured from mediastinal samples obtained from patients with PSM. A component of the membrane of the gram positive bacteria, lipoteichoic acid, stimulates the blood monocytes and macrophages to secrete cytokines, radicals and nitrogen species leading to oxido-inflammatory damage. This seems to be responsible for the high mortality rate in PSM. For the evaluation of the pathogenesis of infection or for the investigation of alternative treatment models in infection, no standard model of mediastinitis seems to be available. In this study, we evaluated four mediastinitis models in rats. Methods The rats were divided into four groups to form different infection models. Group A: A suspension of 1 × 107 colony-forming units Staphylococcus aureus in 0,5 mL was inoculated from the right second intercostal space into the mediastinum. Group B: A hole was created in the right second intercostal space and a piece of stainless-steel implant with a length of 0.5 cm was inserted into the mediastinum and a suspension of 1 × 107 cfu bacteria in 0,5 mL was administered via the tail vein. Group C: Precolonized stainless-steel implant was inserted into the mediastinum. Group D: Precolonized stainless-steel implant was inserted into the mediastinum and the bacteria suspension was also injected into the mediastinum. On the 10th day, rats were sacrificed and the extension of infection in the mediastenae was evaluated by quantitative cultures. Myeloperoxidase activity (MPO) and malondialdehyde (MDA) levels were determined in the sera to evaluate the neutrophil activation and assess the inflammatory oxidation. Results The degree of infection in group C and D were 83.3% and 100% respectively (P P Conclusion Infected implants and high bacterial concentration administration were the two important components that played a significant role in the outcome of a successful infection in mediastinum in a rat model.
Infections caused by non-tuberculous mycobacteria (NTM) have increased recently because of the di... more Infections caused by non-tuberculous mycobacteria (NTM) have increased recently because of the dissemination of HIV infection and the appearance of other disease states post-transplantation or chemotherapy. Mycobacterium fortuitum is a rapidly growing mycobacteria that was ...
We consider a toy cosmological model with a gas of wrapped Dp-branes in 10-dimensional dilaton gr... more We consider a toy cosmological model with a gas of wrapped Dp-branes in 10-dimensional dilaton gravity compactified on a p-dimensional Ricci flat internal manifold. A consistent generalization of the low energy effective field equations in the presence of a conserved brane source coupled to dilaton is obtained. It is then shown that the compact dimensions are dynamically stabilized in string frame as a result of a balance between negative winding and positive momentum pressures. Curiously, when p = 6, i.e. when the observed space is three dimensional, the dilaton becomes a constant and stabilization in Einstein frame is also realized.
We consider evolution of compact extra dimensions in cosmology and try to see whether wrapped bra... more We consider evolution of compact extra dimensions in cosmology and try to see whether wrapped branes can prevent the expansion of the internal space. Some difficulties of Brandenberger and Vafa mechanism for decompactification are pointed out. In both pure Einstein and dilaton gravities, we study cosmology of winding brane gases in a continuum approximation. The energy momentum tensor is obtained by coupling the brane action to the gravity action and we present several exact solutions for various brane configurations. T-duality invariance of the solutions are established in dilaton gravity. Our results indicate that phenomenologically the most viable scenario can be realized when there is only one brane wrapping over all extra dimensions.
We present a cosmological model in 1 + m + p dimensions, where in m-dimensional space there are u... more We present a cosmological model in 1 + m + p dimensions, where in m-dimensional space there are uniformly distributed p-branes wrapping over the extra p-dimensions. We find that during cosmological evolution m-dimensional space expands with the exact power-law corresponding to pressureless matter while the extra p-dimensions contract. Adding matter, we also obtain solutions having the same property. We show that this might explain in a natural way why the extra dimensions are small compared to the observed three spatial directions. *
Journal of Cosmology and Astroparticle Physics, 2004
We investigate toy cosmological models in (1+m+p)-dimensions with gas of p-branes wrapping over p... more We investigate toy cosmological models in (1+m+p)-dimensions with gas of p-branes wrapping over p-compact dimensions. In addition to winding modes, we consider the effects of momentum modes corresponding to small vibrations of branes and find that the extra dimensions are dynamically stabilized while the others expand. Adding matter, the compact volume may grow slowly depending on the equation of state. We also obtain solutions with winding and momentum modes where the observed space undergoes accelerated expansion.
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