A Streamwise Constant Model of Turbulence in Plane Couette Flow

Streamwise and quasi-streamwise elongated structures have been shown to play a significant role in turbulent shear flows. We model the mean behavior of fully turbulent plane Couette flow using a streamwise constant projection of the Navier Stokes equations. This results in a two-dimensional, three velocity component ($2D/3C$) model. We first use a steady state version of the model to demonstrate that its nonlinear coupling provides the mathematical mechanism that shapes the turbulent velocity profile. Simulations of the $2D/3C$ model under small amplitude Gaussian forcing of the cross-stream components are compared to DNS data. The results indicate that a streamwise constant projection of the Navier Stokes equations captures salient features of fully turbulent plane Couette flow at low Reynolds numbers. A system theoretic approach is used to demonstrate the presence of large input-output amplification through the forced $2D/3C$ model. It is this amplification coupled with the appropriate nonlinearity that enables the $2D/3C$ model to generate turbulent behaviour under the small amplitude forcing employed in this study.Comment: Journal of Fluid Mechanics 2010, in pres

Significance of Neuropilin-1 Expression in Acute Myeloid Leukemia

Objective: Neuropilin-1 is a vascular endothelial growth factor receptor that acts as a mediator of angiogenesis. Its importance in hematological malignancies such as acute myeloid leukemia (AML) remains to be elucidated. The aim of this study was to evaluate the significance of neuropilin-1 expression in AML patients by both flow cytometry and real-time polymerase chain reaction (PCR) in regard to its diagnostic and prognostic values. Materials and Methods: Bone marrow aspirates of 44 patients with de novo AML and 12 relapsed AML patients were examined in this study. Ten subjects with nonhematological malignancy serving as the control group were also included. Results: Neuropilin-1 expression by flow cytometry showed a highly significant increase in de novo and relapsed AML patients with a mean of 27.1±17.5% and 21.5±16.6%, respectively, compared to control group’s mean of 3.4±1.9%. A cut-off value of 6% was established as differentiating patients from the control group. By real-time PCR, no statistical significance was found in de novo and relapsed AML patients with a mean of 1.9±3.6 IU/L and 0.3±0.2 IU/L, respectively, compared to the control group’s mean of 0.3±0.1 IU/L. Neuropilin-1 surface expression by flow cytometry showed a significant correlation with total leukocyte count and a negative correlation with hemoglobin level in de novo AML patients. In relapsed AML patients, positive significant correlations were found with age, bone marrow blast percentage, and CD14. Neuropilin-1 mRNA level by real-time PCR showed a positive significant correlation with peripheral blood blast percentage and CD117 and a negative correlation with hemoglobin level in de novo AML patients. In relapsed patients, a positive correlation was found with lactate dehydrogenase. Conclusion: Neuropilin-1 can be used as a tool for diagnosis and prognosis in AML patients

Effect of nanostructured lipid carriers on transdermal delivery of tenoxicam in irradiated rats

Transdermal delivery of non-steroidal anti-inflammatory drugs (NSAIDs) is an effective route of drug administration, as it directs the drug to the inflamed site with reduced incidence of systemic adverse effects such as gastric hemorrhage and ulcers. Tenoxicam (TNX) is a member of NSAIDs that are marketed only as oral tablets due to very poor absorption through the skin. The current study intended to formulate and characterize a hydrogel loaded with nanostructured lipid carriers (NLCs) to enhance the transdermal delivery of TNX. Six formulations of TNX were formulated by slight modifications of high shear homogenization and ultrasonication method. The selected formula was characterized for their particle size, polydispersity index (PDI), zeta potential, entrapment efficiency (EE), in-vitro drug release and ex-vivo skin permeation studies. Moreover, the effectiveness of the developed formula was studied in-vivo using carrageenan-induced paw edema and hyperalgesia model in irradiated rats. Formula F4 was chosen from six formulations, as the average diameter was 679.4 ± 51.3 nm, PDI value of about 0.02, zeta potential of −4.24 mV, EE of 92.36%, globules nanoparticles without aggregations and absence of interactions in the developed formula. Additionally, the in-vivo study showed the efficacy of formula F4 (TNX-NLCs hydrogel) equivalent to oral TNX in reducing the exaggerated inflammatory response induced by carrageenan after irradiation. In conclusion, the present findings suggest that TNX-NLCs hydrogel could be a potential transdermal drug delivery system alternative to the oral formulation for the treatment of various inflammatory conditions