University of Louisville

About: University of Louisville is a education organization based out in Louisville, Kentucky, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 24600 authors who have published 49248 publications receiving 1573346 citations. The organization is also known as: UofL.

Intermittent Hypoxia Is Associated with Oxidative Stress and Spatial Learning Deficits in the Rat

Abstract: In the adult rat, exposure to intermittent hypoxia (IH), such as occurs in sleep-disordered breathing, is associated with neurobehavioral impairments and increased apoptosis in the hippocampal CA1 region and cortex. We hypothesized that the episodic hypoxic-reoxygenation cycles of IH would induce oxidant stress, and the latter may underlie the IH-associated spatial learning and retention deficits. Adult male rats were therefore exposed to IH (90-second alternations of 10% oxygen and 21% oxygen) or room air (RA) for 7 days, and received twice-daily injections of either 3 mg/kg of the antioxidant PNU-101033E (PNU) or vehicle (V). Rats were then trained in a standard place-training task in the water maze. V-IH displayed significant impairments of spatial learning in the water maze, which were attenuated by PNU-101033E. Post hoc analyses further revealed that V-IH had significantly longer latencies and pathlengths to locate the hidden platform than PNU-IH, V-RA, or PNU-RA, indicating that PNU-101033E treatment reduced the behavioral impairments associated with IH. In addition, treatment with PNU-101033E markedly attenuated the increase in lipid peroxidation, and isoprostane concentrations associated with exposure to IH. Collectively, these findings indicate that the IH exposure is associated with increased oxidative stress, which is likely to play an important role in the behavioral impairments observed in a rodent model of sleep-disordered breathing.

Mast cells promote homeostasis by limiting endothelin-1-induced toxicity

Abstract: Endothelin-1 (ET-1) is a 21-amino-acid peptide, derived from vascular endothelial cells, with potent vasoconstrictor activity. ET-1 has been implicated in diverse physiological or pathological processes, including the vascular changes associated with sepsis. However, the factors that regulate ET-1-associated toxicity during bacterial infections, or in other settings, are not fully understood. Both the pathology associated with certain allergic and autoimmune disorders, and optimal host defence against bacterial and parasitic infections are mediated by mast cells. In vitro, mast cells can produce ET-1 (ref. 11), undergo ET-1-dependent and endothelin-A receptor (ET(A))-dependent activation, and release proteases that degrade ET-1 (ref. 14). Although the potential relationships between mast cells and the ET-1 system thus may be complex, the importance of interactions between ET-1 and mast cells in vivo is obscure. Here we show that ET(A)-dependent mast-cell activation can diminish both ET-1 levels and ET-1-induced pathology in vivo, and also can contribute to optimal survival during acute bacterial peritonitis. These findings identify a new biological function for mast cells: promotion of homeostasis by limiting the toxicity associated with an endogenous mediator.

MultiStencils Fast Marching Methods: A Highly Accurate Solution to the Eikonal Equation on Cartesian Domains

Abstract: A wide range of computer vision applications require an accurate solution of a particular Hamilton-Jacobi (HJ) equation known as the Eikonal equation. In this paper, we propose an improved version of the fast marching method (FMM) that is highly accurate for both 2D and 3D Cartesian domains. The new method is called multistencils fast marching (MSFM), which computes the solution at each grid point by solving the Eikonal equation along several stencils and then picks the solution that satisfies the upwind condition. The stencils are centered at each grid point and cover its entire nearest neighbors. In 2D space, two stencils cover 8-neighbors of the point, whereas in 3D space, six stencils cover its 26-neighbors. For those stencils that are not aligned with the natural coordinate system, the Eikonal equation is derived using directional derivatives and then solved using higher order finite difference schemes. The accuracy of the proposed method over the state-of-the-art FMM-based techniques has been demonstrated through comprehensive numerical experiments.

New insights of T cells in the pathogenesis of psoriasis

Abstract: Psoriasis is one of the most common immune-mediated chronic, inflammatory skin diseases characterized by hyperproliferative keratinocytes and infiltration of T cells, dendritic cells, macrophages and neutrophils. Although the pathogenesis of psoriasis is not fully understood, there is ample evidence suggesting that the dysregulation of immune cells in the skin, particularly T cells, plays a critical role in psoriasis development. In this review, we mainly focus on the pathogenic T cells and discuss how these T cells are activated and involved in the disease pathogenesis. Newly identified ‘professional' IL-17-producing dermal γδ T cells and their potential role in psoriasis will also be included. Finally, we will briefly summarize the recent progress on the T cell and its related cytokine-targeted therapy for psoriasis treatment.

A habitat matrix conceptual model for stream periphyton

Abstract: In this paper we suggest a conceptual model for the evaluation of periphyton communities in unshaded temperate streams based on the primary habitat variables of flood disturbance, nutrient resource supply and invertebrate grazing. The core of this model is a classification of 35 periphyton taxa into four main functional groups based on the C-S-R life history strategies of Grime. Possible successional trajectories following system-wide disturbances under different nutrient supply regimes are also discussed. The interaction of disturbance and nutrient supply on species membership, productivity and accrual time results in a predicted gradient from low biomass in frequently disturbed, unenriched habitats to high biomass in infrequently disturbed, enriched habitats. This prediction is verified empirically using literature data. Herbivory can strongly modify such periphyton responses to disturbance and resource supply. However, these grazing effects could vary greatly depending on the dominant invertebrate grazer and their total abundance, which inturn, is also sensitive to changes in disturbance and nutrient resource supply. This interaction is also discussed. The conceptual model complements other more general habitat templet and dynamic equilibrium concepts in ecology.