Browsing by Subject "nitric oxide"
Now showing items 1-4 of 4
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(2020)A hypoxic (low oxygen level) microenvironment and nitric oxide paracrine signaling play important roles in the control of both biological and pathological cell responses. In this study, we present a microfluidic chip architecture for nitric oxide delivery under a hypoxic microenvironment in human embryonic kidney cells (HEK-293). The chip utilizes two separate, but interdigitated microfluidic channels. The hypoxic microenvironment was created by sodium sulfite as the oxygen scavenger in one of the channels. The nitric oxide microenvironment was created by sodium nitroprusside as the light-activated nitric oxide donor in the other channel. The solutions are separated from the cell culture by a 30 µm thick gas-permeable, but liquid-impermeable polydimethylsiloxane membrane. We show that the architecture is preliminarily feasible to define the gaseous microenvironment of a cell culture in the 100 µm and 1 mm length scales.
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(Helsingfors universitet, 2016)Chlamydia pneumoniae is an intracellular bacterium that causes a variety of respiratory infections to humans such as pneumonia and bronchitis. In addition C. pneumoniae -infection has been associated with multiple chronic diseases of which the most important are atherosclerosis and vascular diseases, asthma, chronic obstructive pulmonary disease and different kinds of neurological disorders. C. pneumoniae is a very common pathogen that has the ability to hide in the system in a persistent chronic form out of reach of the immune defences. C. pneumoniae has been shown to infect many other cell types besides bronchial epithelial cells. These cells include monocytes, macrophages and vascular endothelial cells. C. pneumoniae induces the secretion of different kinds of cytokines and cell signalling molecules and the expression of adhesion molecules in all of these cell types. Too strong cytokine and immune response is detrimental to cells and to whole system. Currently available antibiotics aren't effective enough against C. pneumoniae -infection, especially against its chronic form. Furthermore, the lack of effective anti-chlamydial drugs impairs the research of the association between C. pneumoniae and chronic diseases. The aim of this study was to investigate the effect of anti-chlamydial compounds on the release of cytokines and cell signaling molecule, nitric oxide, induced by C. pneumoniae -infection in different cell types. These anti-chlamydial compounds are currently under the investigation in the faculty of pharmacy. In addition the anti-inflammatory properties of the compounds were further investigated with the help of lipopolysaccharide of another gram-negative bacterium E. coli. The groups of compounds investigated in this study were β2,2-amino acid derivatives, Schisandra chinensis -lignans, TE-compounds synthesized in Vienna and benzimidazole compounds synthesized in the faculty of pharmacy. There were four cell types used in this study, HL- and BEAS-2B-epithelial cells, THP-1-monocytes/macrophages and RAW264.7-macrophages. The study focused on the determination of vascular endothelial growth factor VEGF and interleukins IL-8, IL-10 and IL-12. The concentrations of cytokines in the cell medium were measured after infection using ELISA-method. Nitric oxide measurements were also determined from the medium using Griess' reagent. Immunofluorescence labeling was used to confirm the infection and the infection was verified by fluorescence microscope. In addition some of the compounds were tested for the cell viability using resazurin assay. All the groups of compounds showed desired effects on the release of cytokines and nitric oxide. Especially β2,2-amino acid derivatives reduced clearly the release of both cytokines and nitric oxide. β2,2-amino acid derivatives could thus be potential drug candidates for the development of anti-chlamydial and anti-inflammatory drugs. Schisandra chinensis -lignans inhibited especially the release of nitric oxide in both C. pneumoniae -infected and LPS-stimulated cells which may tell about their broad anti-inflammatory properties. There were also found desired results with TE-compounds and benzimidazole compounds. Interleukins were not secreted by any of the studied cells so that part needs more research and further investigation. Based on the results found in this study it can be concluded that the studied compounds could be potential lead compounds in the discovery of anti-chlamydial drugs and drugs that specifically inhibit C. pneumoniae -infection. Further research is needed concerning the effects of these compounds on cytokines and especially on chronic infection.
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(2022)It has been postulated that the activation of NMDA receptors (NMDAr) and nitric oxide (NO) production in the hippocampus is involved in the behavioral consequences of stress. Stress triggers NMDAr-induced calcium influx in limbic areas, such as the hippocampus, which in turn activates neuronal NO synthase (nNOS). Inhibition of nNOS or NMDAr activity can prevent stress-induced effects in animal models, but the molecular mechanisms behind this effect are still unclear. In this study, cultured hippocampal neurons treated with NMDA or dexamethasone showed an increased of DNA methyltransferase 3b (DNMT3b) mRNA expression, which was blocked by pre-treatment with nNOS inhibitor n(omega)-propyl-l-arginine (NPA). In rats submitted to the Learned Helplessness paradigm (LH), we observed that inescapable stress increased DNMT3b mRNA expression at 1h and 24h in the hippocampus. The NOS inhibitors 7-NI and aminoguanidine (AMG) decreased the number of escape failures in LH and counteracted the changes in hippocampal DNMT3b mRNA induced in this behavioral paradigm. Altogether, our data suggest that NO produced in response to NMDAr activation following stress upregulates DNMT3b in the hippocampus.
