Browsing by Subject "cardiovascular system"

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    Delayed effects of acute radiation exposure on the cardiovascular system using a murine model of the hematopoietic acute radiation syndrome
    (Office of the Vice Chancellor for Research, 2016-04-08) Thungu, Beatrice; Ortiz, Miguel; Unthank, Joseph L.; Orschell, Christie M.; Miller, Steven J.
    Introduction. Exposure to high level radiation from accidents or belligerent activities results in acute and chronic organ damage. The hematopoietic system is the most sensitive organ to radiation damage (2-10 Gy) and results in the hematopoietic acute radiation syndrome (H-ARS). Survivors of H-ARS are plagued months to years later with delayed effects of acute radiation exposure (DEARE), characterized by chronic illnesses affecting multiple organ systems. Previous results using the murine H-ARS model showed numerous kidney and heart DEARErelated pathologies similar to humans, including tissue fibrosis and elevated blood urea nitrogen. The goal of this study was to utilize the murine H-ARS model to determine possible roles for abnormal iron metabolism, inflammation, oxidant stress, and senescence in the development of cardiac DEARE. Methods. Mice (C57BL/6; 12 week-old) received total body irradiation (TBI: ~8.5-8.7 Gy, 137Cs, LD50to LD70) and hearts were harvested at various times post-TBI from H-ARS survivors. Paraffin tissue sections were stained with hematoxylin/eosin or Perls Prussian Blue, or reacted with a macrophage-specific antibody (F4/80). Total RNA was purified from fresh tissue and changes in mRNA expression were assessed by real-time PCR for the senescence marker p16 and NADPH oxidase subunits Nox2, Nox4, or p47phox. Results/Significance. Compared to age-matched non-irradiated controls (NI), tissue iron deposits were increased in irradiated (IR) hearts at 4 months, and progressively declined with time post-TBI. Numbers of macrophages were greater in IR vs. NI sections at all time points and decreased with time post-TBI. Nox2 and Nox4 mRNA expression was increased at both 9 and 21 months post-TBI, but p47phox increased only at 21 months. Expression of p16 in IR heart was increased at 7, but not at 22 months post-TBI. Taken together, the results indicate abnormal iron metabolism, inflammation, oxidant stress, and early senescence may contribute to development of cardiac DEARE.
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    EFFECTS OF PORPHYROMONAS GINGIVALIS TREATED WITH VARIOUS CIGARETTE CONSTITUENTS ON HUMAN UMBILICAL VEIN ENDOTHELIAL CELLS
    (Office of the Vice Chancellor for Research, 2012-04-13) Gupta, Vinayak; Windsor, L. Jack; Gregory, Richard L.
    Tobacco use affects the cardiovascular system and increases the rate of cardiovascular disease among smokers. However, the effects of tobacco on the endothelial cells that line blood vessels are not yet fully understood. Thus, the objective of this study was to examine some of the effects that a periodontal pathogen such as Porphyromonas gingivalis (P. gingivalis) treated with cigarette smoke condensate (CSC), nicotine, and dissolvable tobacco strips (DST) have on human umbilical vein endothelial cells (HUVECs). P.gingivalis was grown in an anaerobic environment at 37oC with and without CSC, DST, and nicotine. The cells and supernatants were harvested 96 hours later. A Bradford protein assay was conducted to determine the protein amounts of the cells and in the supernatant. The HUVEC will be cultured in Endothelial Basal Medium-2 and plated in 6 well plates and exposed to the P. gingivalis cells and supernatants and after 72 hours, lactate dehydrogenase (LDH) assays will be used to cytotoxicity. Non-toxic amounts of the cells and supernatants will then be used to treat HUVEC cells for 72 hours before the media is collected and analyzed for cytokine/growth factor expression by protein arrays. It is believed that the treated bacteria will increase the levels of the pro-inflammatory cytokines and growth factors expressed by the HUVECs, which could play roles in vascular diseases. The protein assays showed that only the protein amount in the supernatant from the CSC treated bacteria was decreased.
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    VOLUMETRIC LATTICE BOLTZMANN SIMULATION FOR BLOOD FLOW IN AORTA ARTERY PUMPED THROUGH AORTIC HEART VALVE
    (Office of the Vice Chancellor for Research, 2012-04-13) Deep, Debanjan; Yu, Huidan
    Complicated moving boundaries pose a major challenge in compu-tational fluid dynamics for complex flows, especially in the biomechan-ics of both blood flow in the cardiovascular system and air flow in the respiratory system where the compliant nature of the vessels can have significant effects on the flow rate and wall shear stress. We develop an innovative approach to treat arbitrarily moving boundaries in Lat-tice Boltzmann Method (LBM) using a volumetric lattice Boltzmann representation, which distributes particles in fluid lattice cells. A volu-metric bounce-back procedure is applied in the streaming step while momentum exchange between the fluid and moving solid boundary are accounted for in the collision step. Additional boundary-induced migra-tion is introduced to conserve fluid mass as the boundary moves across fluid cells. We use the volumetric LBM to simulate blood flow in aorta pumped from heart focusing on the flow rate, flow structure, pressure distribution within the aorta for different heart pumping con-ditions. For validation, the volumetric LBM is compared with Navier-Stokes computation and good agreements are achieved. We study the flow dynamics within the aorta in the cardiac cycle (systole and diasto-le) through alternatively opening and closing the inlet boundary to mimic the heart pumping mechanism.