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It is believed that bioactive compounds from plant foods may have health beneficial effects and reduce the risk of chronic inflammatory diseases. In this study extracts of 121 plants typical for the traditional Mediterranean diet have been screened for their potential anti-inflammatory activities. The ability of the extracts to inhibit cytokinestimulated, iNOS-dependent synthesis of nitric oxide in murine endothelial cells, without affecting cell viability, was the primary indicator of their anti-inflammatory properties. Based on these experiments we selected eight plant extracts for further analysis: Chrysanthemum coronarium L., Scandix pecten-veneris L., Urospermum picroides (L.) Scop. Ex F. W. Smith, Amaranthus cf. graecizans L., Onopordum macracanthum Schousboe, Eryngium campestre L., Artemisia alba Turra and Merendera pyrenaica (Pourret) Fourn. Only the effects of Onopordum macracanthum could be non-specific since the extract strongly inhibited total protein synthesis. All remaining 7 extracts decreased nitric oxide and TNFa synthesis in the cells of monocyte origin activated with LPS, and 4 of them significantly reduced surface expression of VCAM1 on TNFa-stimulated endothelial cells. All seven plant extracts decreased cytokine or LPS-stimulated iNOS mRNA levels in both cell types. Further research to identify bioactive compounds influencing intracellular signaling pathways activated by cytokines and LPS will consequently be needed in order to better understand these in vitro effects.
It is generally accepted that chronic inflammatory disease, either local or generalized, is associated with higher incidence of cancer. Since inflammation is often accompanied by oxidative stress the latter was indicated as the foundation for progressive mutations leading to tumor development (proliferation, invasion, metastasis). Even though, it is very hard to demonstrate by in vitro studies the causal relationship between oxidative stress and cell transformations. From our studies it is clear that cells are more likely to stop divisions and they commit suicide by apoptosis. During last decade, a novel view on the origin of cancer emerged. The so called cancer stem cells (CSC) were found that form the side-population of stem cells (SC) and they are believed to initiate cancer. Are the SC ancestors for CSC? Do SC transform into CSC? These and other questions remain unanswered. We hypothesize that SC might undergo transformation into CSC during prolonged oxidative stress. We claim that several changes in cell biochemistry has to occur to start the molecular modifications leading to neoplasma. These include either hypoxia-promoted apoptosis signal inducing kinase 1 (ASK-1), hypoxia inducing factor 1 alpha (HIF-la) and glycolysis, or normoxia-promoted activating protein-1 (AP-1) or hyperoxia-induced nuclear factor kappa B (NF-kB). Next, harsh microenviron- ment and heterogenous extracellular matrix (ECM) induced by oxidative stress accelerate the selection of clones of cells resistant to apoptogenic signal. HIF-la, protein crucial for transcriptional activation of protooncogene met leads to the overexpression of c-Met receptor that in turn sensitizes cells to hepatocyte growth factor/scatter factor (HGF/SF) mitogen. Finally, both impaired function of mitochondria and hypoxia elevate fibrin protein level and amplify hemostasis as disseminated in- tracapillary coagulation (DIC). In any case, it is very interesting and remains to be answered whether imbalance in prooxidant-antioxidant homeostasis has causal relationship with transformation of SC to CSC.
 Vitamin D (VD) and its different analogues, besides their classic role as regulators of calcium and phosphor homeostasis, have emerged as a large family of antiproliferative agents. Such properties suggested VD potential as a therapy for chronic inflammatory diseases, including nasal polyposis (NP). NP growth involves both an inflammatory process and the proliferation of fibroblast as an important factor inducing aberrations in the phenotype of the epithelium. The aim of this study was to investigate the possible influence of 1α,25-dihydroxyvitamin D3 (calcitriol) and 1α,24(R)-dihydroxyvitamin D3 (tacalcitol) in monotherapy and in combination with budesonid R (BR) on NP fibroblast proliferation. Material and methods: The study involved 26 samples of NP. NP cells were cultured on 96-well plates beginning with a concentration of 5 × 103 cells per well with RPMI 1640 medium supplemented with antibiotics and 10% foetal bovine serum. After the fourth to sixth passage the medium was replaced with a nutrient medium with calcitriol or tacalcitol in a defined concentration (from 10-9 M to 10-3 M) alone or in combination with BR in 1:1, 1:3 or 3:1 ratios, each at concentrations from 10-5 M to 10-3 M. Results: Growth inhibition of nasal fibroblasts exposed to calcitriol or tacalcitol was noted. Significant antiproliferating activity was observed at calcitriol concentrations of 10-4 M and 10-3 M after 48 h, and at a concentration of 10-3 M after 72 h with the percentage of proliferating cells reduced to 30% compared to the control samples (P < 0.05). In cells treated with tacalcitol the maximal effect was seen at 10-4 M after 48 h and at 10-3 M after 72 h with a 60% inhibition with respect to the control (P < 0.05). The inhibition of fibroblast proliferation reached the maximal level when they were exposed to calcitriol: BR (1 : 1) or tacalcitol: BR (1 : 1), each at a concentration of 10-4 M, after 72 h (82% and 69%, respectively). Conclusions: The antiproliferative activity of calcitriol and tacalcitol in NP cultures was confirmed. Because of its lower toxicity and higher activity tacalcitol seems to be the more promising agent in NP therapy, both as a single medication and in treatment protocols with BR.
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