462 research outputs found

    Robust Transitivity in Hamiltonian Dynamics

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    A goal of this work is to study the dynamics in the complement of KAM tori with focus on non-local robust transitivity. We introduce CrC^r open sets (r=1,2,...,r=1, 2, ..., \infty) of symplectic diffeomorphisms and Hamiltonian systems, exhibiting "large" robustly transitive sets. We show that the CC^\infty closure of such open sets contains a variety of systems, including so-called a priori unstable integrable systems. In addition, the existence of ergodic measures with large support is obtained for all those systems. A main ingredient of the proof is a combination of studying minimal dynamics of symplectic iterated function systems and a new tool in Hamiltonian dynamics which we call symplectic blender.Comment: 52 pages, 3 figure

    AAV-mediated and pharmacological induction of Hsp70 expression stimulates survival of retinal ganglion cells following axonal injury.

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    We evaluated the effect of AAV2- and 17-AAG (17-N-allylamino-17-demethoxygeldanamycin)-mediated upregulation of Hsp70 expression on the survival of retinal ganglion cells (RGCs) injured by optic nerve crush (ONC). AAV2-Hsp70 expression in the retina was primarily observed in the ganglion cell layer. Approximately 75% of all transfected cells were RGCs. RGC survival in AAV2-Hsp70-injected animals was increased by an average of 110% 2 weeks after the axonal injury compared with the control. The increase in cell numbers was not even across the retinas with a maximum effect of approximately 306% observed in the inferior quadrant. 17-AAG-mediated induction of Hsp70 expression has been associated with cell protection in various models of neurodegenerative diseases. We show here that a single intravitreal injection of 17-AAG (0.2 ug ul(-1)) results in an increased survival of ONC-injured RGCs by approximately 49% compared with the vehicle-treated animals. Expression of Hsp70 in retinas of 17-AAG-treated animals was upregulated approximately by twofold compared with control animals. Our data support the idea that the upregulation of Hsp70 has a beneficial effect on the survival of injured RGCs, and the induction of this protein could be viewed as a potential neuroprotective strategy for optic neuropathies

    Adverse Effects of Systemic Immunosuppression in Keratolimbal Allograft

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    Purpose. Keratolimbal allograft (KLAL) is a treatment for limbal stem cell deficiency. One disadvantage is systemic immunosuppression to avoid rejection. Our purpose was to examine the adverse effects of systemic immunosuppression in KLAL. Methods. A retrospective case review of 16 patients with KLAL who received systemic immunosuppression consisting of a corticosteroid, an antimetabolite, and/or a calcineurin inhibitor was performed. Patients were monitored for signs, symptoms, or laboratory evidence of toxicity. Results. Eleven of 16 patients (68%) experienced an adverse effect. The average age of those with adverse effects was 43.5 years and without was 31.4 years. Ten of 11 patients (91%) had resolution during mean followup of 16.4 months. No serious adverse effects occurred. The most common included anemia, hyperglycemia, elevated creatinine, and elevated liver function tests. Prednisone and tacrolimus were responsible for the most adverse effects. Patients with comorbidities were more likely to experience an adverse effect (82% versus 20%, P = 0.036). Conclusions. KLAL requires prolonged systemic immunosuppression. Our data demonstrated that systemic immunosuppression did not result in serious adverse effects in our population and is relatively safe with monitoring for toxicity. In addition, we demonstrated that adverse effects are more likely in older patients with comorbidities

    Bone mineral density is lower in male than female patients with plaque-type psoriasis in Iran

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    Background There are many similarities with regard to contributing cytokines in patients with psoriasis and osteoporosis. A theory of probable relationship between these two entities has been proposed but there is no concordant consensus. The aim of this study was to evaluate bone mineral density (BMD) in patients with psoriasis. Method and materials This cross-sectional study of BMD was conducted with 64 eligible patients with psoriasis who were referred to the dermatology clinic of Razi hospital in Tehran, Iran in between 2011 and 2012. Results The mean T score of femoral neck was �1.17 and �0.49 in men and women, respectively, which was statistically significant (p =.047). The mean T score of the lumbar spine was �0.93 and �0.30 in men and women, respectively, but not statistically significant (p =.058). In total except with the exclusion of the study site (femur or lumbar), men and women did not have a statistically significant difference with regard to osteoporosis or osteopenia in BMD (p =.114). The Pearson correlation coefficient demonstrated a moderate inverse relationship between age and T score of the femoral neck and lumbar spine (r = �0.419 and �.406, respectively), which was statistically significant (p =.001). Although there was no statistically significant relationship between the Psoriasis Area and Severity Index (PASI) and T scores of the femoral neck (p =.596), a positive and weak correlation was observed between the PASI and T scores for the lumbar spine, which was statistically significant (r = 0.269; p =.03). Conclusion Patients with psoriasis had decreased bone density, which was more significant in men. Prevalence of osteoporosis showed no statistically significant difference when compared with the healthy population in Iran. © 201

    Design and Production of a Novel Recombinant Chimeric IL2-Omp31 Antigen against Brucella Infection

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    Brucellosis is a zoonotic disease in human and animals. Brucella melitensis is one of the most pathogenic species of Brucella in goat and sheep. Omp31 is an outer membrane protein of Brucella that acts as an immunogenic protein. Cytokines are glycoproteins with low molecular weight that play the role of an immune adjuvant and regulate immune responses. Interleukin-2 is one of the most important cytokines, which are secreted by the white blood cells and involved in T cell immune responses. In the present study, a chimeric Omp31-Interleukin2 recombinant protein was generated by means of genetic engineering techniques. This chimeric coding sequence was amplified by using specific primers and using Splicing Overlap Extension (SOE) PCR technique. The fusion of the two mentioned proteins was accomplished using a rigid linker. The generated chimeric IL2-Omp31 fragment was TA cloned, and then subcloned into pEt22b vector as an expression vector. The chimeric protein was successfully expressed in E. coli BL21 (DE3) and confirmed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and also Western-blotting analysis. Finally, in order to assess the antigenic features of the recombinant chimeric IL2-Opm31 protein, its secondary structure and antigenicity were predicted in silico

    Bone mineral density is lower in male than female patients with plaque-type psoriasis in Iran

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    Background There are many similarities with regard to contributing cytokines in patients with psoriasis and osteoporosis. A theory of probable relationship between these two entities has been proposed but there is no concordant consensus. The aim of this study was to evaluate bone mineral density (BMD) in patients with psoriasis. Method and materials This cross-sectional study of BMD was conducted with 64 eligible patients with psoriasis who were referred to the dermatology clinic of Razi hospital in Tehran, Iran in between 2011 and 2012. Results The mean T score of femoral neck was �1.17 and �0.49 in men and women, respectively, which was statistically significant (p =.047). The mean T score of the lumbar spine was �0.93 and �0.30 in men and women, respectively, but not statistically significant (p =.058). In total except with the exclusion of the study site (femur or lumbar), men and women did not have a statistically significant difference with regard to osteoporosis or osteopenia in BMD (p =.114). The Pearson correlation coefficient demonstrated a moderate inverse relationship between age and T score of the femoral neck and lumbar spine (r = �0.419 and �.406, respectively), which was statistically significant (p =.001). Although there was no statistically significant relationship between the Psoriasis Area and Severity Index (PASI) and T scores of the femoral neck (p =.596), a positive and weak correlation was observed between the PASI and T scores for the lumbar spine, which was statistically significant (r = 0.269; p =.03). Conclusion Patients with psoriasis had decreased bone density, which was more significant in men. Prevalence of osteoporosis showed no statistically significant difference when compared with the healthy population in Iran. © 201

    Level Crossing Analysis of Burgers Equation in 1+1 Dimensions

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    We investigate the average frequency of positive slope να+\nu_{\alpha}^{+}, crossing the velocity field u(x)uˉ=αu(x)- \bar u = \alpha in the Burgers equation. The level crossing analysis in the inviscid limit and total number of positive crossing of velocity field before creation of singularities are given. The main goal of this paper is to show that this quantity, να+\nu_{\alpha}^{+}, is a good measure for the fluctuations of velocity fields in the Burgers turbulence.Comment: 5 pages, 3 figure
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